SYSTEMS AND METHODS FOR CONTROLLING DISPLACEMENT MEMBER MOTION OF A SURGICAL STAPLING AND CUTTING INSTRUMENT

[0001] The present disclosure relates to surgical instruments and, in various circumstances, to surgical stapling and cutting instruments and staple cartridges therefor that are designed to staple and cut tissue.

[0002] In a motorized surgical stapling and cutting instrument it may be useful to control the velocity of a cutting member or to control the articulation velocity of an end effector. Velocity of a displacement member may be determined by measuring elapsed time at predetermined position intervals of the displacement member or measuring the position of the displacement member at predetermined time intervals. The control may be open loop or closed loop. Such measurements may be useful to evaluate tissue conditions such as tissue thickness and adjust the velocity of the cutting member during a firing stroke to account for the tissue conditions. Tissue thickness may be determined by comparing expected velocity of the cutting member to the actual velocity of the cutting member. In some situations, it may be useful to articulate the end effector at a constant articulation velocity. In other situations, it may be useful to drive the end effector at a different articulation velocity than a default articulation velocity at one or more regions within a sweep range of the end effector.

[0003] During use of a motorized surgical stapling and cutting instrument it is possible that the force to fire on the cutting member and firing member may vary based on the stroke location of the cutting member during the firing process, tissue thickness encountered by the cutting member, and the overall length of the firing stroke of the cutting member. Therefore, it may be desirable to provide variable firing pauses based on the stroke location of the cutting member. Therefore, it may be desirable to provide powered firing actuation with variable automatic pauses where the pause number, pause duration, and stroke location are based on the force and the stroke location of the firing system.

[0004] In one aspect, the present disclosure provides a surgical instrument comprising: a displacement member configured to translate within the surgical instrument; a motor coupled to the displacement member to translate the displacement member; a sensor configured to sense a thickness of a tissue grasped by an end effector; and a control circuit coupled to the motor and the sensor, the control circuit configured to: retrieve an expected thickness of the tissue; determine the thickness of the tissue via the sensor; and set a duty cycle for driving the motor, wherein the duty cycle corresponds to the thickness of the tissue relative to the expected thickness of the tissue.

[0005] In another aspect, the present disclosure provides a surgical instrument comprising: a displacement member configured to translate within the surgical instrument; a motor coupled to the displacement member to translate the displacement member; and a control circuit coupled to the motor, the control circuit configured to: determine a force on the displacement member; and pause the motor according to whether the force is greater than a threshold force.

[0006] In another aspect, the present disclosure provides a method of controlling a motor in a surgical instrument, the surgical instrument comprising a displacement member configured to translate within the surgical instrument, a motor coupled to the displacement member to translate the displacement member, a sensor configured to sense a thickness of a tissue grasped by an end effector, and a control circuit coupled to the motor, the method comprising: retrieving, by the control circuit, an expected thickness of the tissue; determining, by the control circuit, the thickness of the tissue via the sensor; and setting, by the control circuit, a duty cycle for driving the motor, wherein the duty cycle corresponds to the thickness of the tissue relative to the expected thickness of the tissue.

[0007] In another aspect, the present disclosure provides a method of controlling a motor in a surgical instrument, the surgical instrument comprising a displacement member configured to translate within the surgical instrument, a motor coupled to the displacement member to translate the displacement member, and a control circuit coupled to the motor, the method comprising: determining, by the control circuit, a force on the displacement member; and pausing, by the control circuit, the motor according to whether the force is greater than a threshold force.

[0030] Applicant of the present application owns the following patent applications filed concurrently herewith and which are each herein incorporated by reference in their respective entireties:

[0031] Attorney Docket No. END8191USNP/170054, titled CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON ANGLE OF ARTICULATION, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0032] Attorney Docket No. END8192USNP/170055, titled SURGICAL INSTRUMENT WITH VARIABLE DURATION TRIGGER ARRANGEMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0033] Attorney Docket No. END8194USNP/170057, titled SYSTEMS AND METHODS FOR CONTROLLING MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT ACCORDING TO ARTICULATION ANGLE OF END EFFECTOR, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0034] Attorney Docket No. END8195USNP/170058, titled SYSTEMS AND METHODS FOR CONTROLLING MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0035] Attorney Docket No. END8196USNP/170059, titled SURGICAL INSTRUMENT HAVING CONTROLLABLE ARTICULATION VELOCITY, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0036] Attorney Docket No. END8197USNP/170060, titled SYSTEMS AND METHODS FOR CONTROLLING VELOCITY OF A DISPLACEMENT MEMBER OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0037] Attorney Docket No. END8198USNP/170061, titled SYSTEMS AND METHODS FOR CONTROLLING DISPLACEMENT MEMBER VELOCITY FOR A SURGICAL INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0038] Attorney Docket No. END8222USNP/170125, titled CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON ANGLE OF ARTICULATION, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0039] Attorney Docket No. END8199USNP/170062M, titled TECHNIQUES FOR ADAPTIVE CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0040] Attorney Docket No. END8275USNP/170185M, titled TECHNIQUES FOR CLOSED LOOP CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT, by inventors Raymond E. Parfett et al., filed Jun. 20, 2017.

[0041] Attorney Docket No. END8268USNP/170186, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON MAGNITUDE OF VELOCITY ERROR MEASUREMENTS, by inventors Raymond E. Parfett et al., filed Jun. 20, 2017.

[0042] Attorney Docket No. END8276USNP/170187, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON MEASURED TIME OVER A SPECIFIED DISPLACEMENT DISTANCE, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

[0043] Attorney Docket No. END8266USNP/170188, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON MEASURED DISPLACEMENT DISTANCE TRAVELED OVER A SPECIFIED TIME INTERVAL, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0044] Attorney Docket No. END8267USNP/170189, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON MEASURED TIME OVER A SPECIFIED NUMBER OF SHAFT ROTATIONS, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0045] Attorney Docket No. END8269USNP/170190, titled SYSTEMS AND METHODS FOR CONTROLLING DISPLAYING MOTOR VELOCITY FOR A SURGICAL INSTRUMENT, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

[0046] Attorney Docket No. END8270USNP/170191, titled SYSTEMS AND METHODS FOR CONTROLLING MOTOR SPEED ACCORDING TO USER INPUT FOR A SURGICAL INSTRUMENT, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

[0047] Attorney Docket No. END8271USNP/170192, titled CLOSED LOOP FEEDBACK CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON SYSTEM CONDITIONS, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0048] Applicant of the present application owns the following U.S. Design Patent Applications filed concurrently herewith and which are each herein incorporated by reference in their respective entireties:

[0049] Attorney Docket No. END8274USDP/170193D, titled GRAPHICAL USER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

[0050] Attorney Docket No. END8273USDP/170194D, titled GRAPHICAL USER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors Jason L. Harris et al., filed Jun. 20, 2017.

[0051] Attorney Docket No. END8272USDP/170195D, titled GRAPHICAL USER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017.

[0052] Certain aspects are shown and described to provide an understanding of the structure, function, manufacture, and use of the disclosed devices and methods. Features shown or described in one example may be combined with features of other examples and modifications and variations are within the scope of this disclosure.

[0053] The terms “proximal” and “distal” are relative to a clinician manipulating the handle of the surgical instrument where “proximal” refers to the portion closer to the clinician and “distal” refers to the portion located further from the clinician. For expediency, spatial terms “vertical,” “horizontal,” “up,” and “down” used with respect to the drawings are not intended to be limiting and/or absolute, because surgical instruments can used in many orientations and positions.

[0054] Example devices and methods are provided for performing laparoscopic and minimally invasive surgical procedures. Such devices and methods, however, can be used in other surgical procedures and applications including open surgical procedures, for example. The surgical instruments can be inserted into a through a natural orifice or through an incision or puncture hole formed in tissue. The working portions or end effector portions of the instruments can be inserted directly into the body or through an access device that has a working channel through which the end effector and elongated shaft of the surgical instrument can be advanced.

[0055] FIGS. 1-4 depict a motor-driven surgical instrument 10 for cutting and fastening that may or may not be reused. In the illustrated examples, the surgical instrument 10 includes a housing 12 that comprises a handle assembly 14 that is configured to be grasped, manipulated, and actuated by the clinician. The housing 12 is configured for operable attachment to an interchangeable shaft assembly 200 that has an end effector 300 operably coupled thereto that is configured to perform one or more surgical tasks or procedures. In accordance with the present disclosure, various forms of interchangeable shaft assemblies may be effectively employed in connection with robotically controlled surgical systems. The term “housing” may encompass a housing or similar portion of a robotic system that houses or otherwise operably supports at least one drive system configured to generate and apply at least one control motion that could be used to actuate interchangeable shaft assemblies. The term “frame” may refer to a portion of a handheld surgical instrument. The term “frame” also may represent a portion of a robotically controlled surgical instrument and/or a portion of the robotic system that may be used to operably control a surgical instrument. Interchangeable shaft assemblies may be employed with various robotic systems, instruments, components, and methods disclosed in U.S. Pat. No. 9,072,535, entitled SURGICAL STAPLING INSTRUMENTS WITH ROTATABLE STAPLE DEPLOYMENT ARRANGEMENTS, which is herein incorporated by reference in its entirety.

[0056] FIG. 1 is a perspective view of a surgical instrument 10 that has an interchangeable shaft assembly 200 operably coupled thereto according to one aspect of this disclosure. The housing 12 includes an end effector 300 that comprises a surgical cutting and fastening device configured to operably support a surgical staple cartridge 304 therein. The housing 12 may be configured for use in connection with interchangeable shaft assemblies that include end effectors that are adapted to support different sizes and types of staple cartridges, have different shaft lengths, sizes, and types. The housing 12 may be employed with a variety of interchangeable shaft assemblies, including assemblies configured to apply other motions and forms of energy such as, radio frequency (RF) energy, ultrasonic energy, and/or motion to end effector arrangements adapted for use in connection with various surgical applications and procedures. The end effectors, shaft assemblies, handles, surgical instruments, and/or surgical instrument systems can utilize any suitable fastener, or fasteners, to fasten tissue. For instance, a fastener cartridge comprising a plurality of fasteners removably stored therein can be removably inserted into and/or attached to the end effector of a shaft assembly.

[0057] The handle assembly 14 may comprise a pair of interconnectable handle housing segments 16, 18 interconnected by screws, snap features, adhesive, etc. The handle housing segments 16, 18 cooperate to form a pistol grip portion 19 that can be gripped and manipulated by the clinician. The handle assembly 14 operably supports a plurality of drive systems configured to generate and apply control motions to corresponding portions of the interchangeable shaft assembly that is operably attached thereto. A display may be provided below a cover 45.

[0058] FIG. 2 is an exploded assembly view of a portion of the surgical instrument 10 of FIG. 1 according to one aspect of this disclosure. The handle assembly 14 may include a frame 20 that operably supports a plurality of drive systems. The frame 20 can operably support a “first” or closure drive system 30, which can apply closing and opening motions to the interchangeable shaft assembly 200. The closure drive system 30 may include an actuator such as a closure trigger 32 pivotally supported by the frame 20. The closure trigger 32 is pivotally coupled to the handle assembly 14 by a pivot pin 33 to enable the closure trigger 32 to be manipulated by a clinician. When the clinician grips the pistol grip portion 19 of the handle assembly 14, the closure trigger 32 can pivot from a starting or “unactuated” position to an “actuated” position and more particularly to a fully compressed or fully actuated position.

[0059] The handle assembly 14 and the frame 20 may operably support a firing drive system 80 configured to apply firing motions to corresponding portions of the interchangeable shaft assembly attached thereto. The firing drive system 80 may employ an electric motor 82 located in the pistol grip portion 19 of the handle assembly 14. The electric motor 82 may be a DC brushed motor having a maximum rotational speed of approximately 25,000 RPM, for example. In other arrangements, the motor may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. The electric motor 82 may be powered by a power source 90 that may comprise a removable power pack 92. The removable power pack 92 may comprise a proximal housing portion 94 configured to attach to a distal housing portion 96. The proximal housing portion 94 and the distal housing portion 96 are configured to operably support a plurality of batteries 98 therein. Batteries 98 may each comprise, for example, a Lithium Ion (LI) or other suitable battery. The distal housing portion 96 is configured for removable operable attachment to a control circuit board 100, which is operably coupled to the electric motor 82. Several batteries 98 connected in series may power the surgical instrument 10. The power source 90 may be replaceable and/or rechargeable. A display 43, which is located below the cover 45, is electrically coupled to the control circuit board 100. The cover 45 may be removed to expose the display 43.

[0060] The electric motor 82 can include a rotatable shaft (not shown) that operably interfaces with a gear reducer assembly 84 mounted in meshing engagement with a with a set, or rack, of drive teeth 122 on a longitudinally movable drive member 120. The longitudinally movable drive member 120 has a rack of drive teeth 122 formed thereon for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84.

[0061] In use, a voltage polarity provided by the power source 90 can operate the electric motor 82 in a clockwise direction wherein the voltage polarity applied to the electric motor by the battery can be reversed in order to operate the electric motor 82 in a counter-clockwise direction. When the electric motor 82 is rotated in one direction, the longitudinally movable drive member 120 will be axially driven in the distal direction “DD.” When the electric motor 82 is driven in the opposite rotary direction, the longitudinally movable drive member 120 will be axially driven in a proximal direction “PD.” The handle assembly 14 can include a switch that can be configured to reverse the polarity applied to the electric motor 82 by the power source 90. The handle assembly 14 may include a sensor configured to detect the position of the longitudinally movable drive member 120 and/or the direction in which the longitudinally movable drive member 120 is being moved.

[0062] Actuation of the electric motor 82 can be controlled by a firing trigger 130 that is pivotally supported on the handle assembly 14. The firing trigger 130 may be pivoted between an unactuated position and an actuated position.

[0063] Turning back to FIG. 1, the interchangeable shaft assembly 200 includes an end effector 300 comprising an elongated channel 302 configured to operably support a surgical staple cartridge 304 therein. The end effector 300 may include an anvil 306 that is pivotally supported relative to the elongated channel 302. The interchangeable shaft assembly 200 may include an articulation joint 270. Construction and operation of the end effector 300 and the articulation joint 270 are set forth in U.S. Patent Application Publication No. 2014/0263541, entitled ARTICULATABLE SURGICAL INSTRUMENT COMPRISING AN ARTICULATION LOCK, which is herein incorporated by reference in its entirety. The interchangeable shaft assembly 200 may include a proximal housing or nozzle 201 comprised of nozzle portions 202, 203. The interchangeable shaft assembly 200 may include a closure tube 260 extending along a shaft axis SA that can be utilized to close and/or open the anvil 306 of the end effector 300.

[0064] Turning back to FIG. 1, the closure tube 260 is translated distally (direction “DD”) to close the anvil 306, for example, in response to the actuation of the closure trigger 32 in the manner described in the aforementioned reference U.S. Patent Application Publication No. 2014/0263541. The anvil 306 is opened by proximally translating the closure tube 260. In the anvil-open position, the closure tube 260 is moved to its proximal position.

[0065] FIG. 3 is another exploded assembly view of portions of the interchangeable shaft assembly 200 according to one aspect of this disclosure. The interchangeable shaft assembly 200 may include a firing member 220 supported for axial travel within the spine 210. The firing member 220 includes an intermediate firing shaft 222 configured to attach to a distal cutting portion or knife bar 280. The firing member 220 may be referred to as a “second shaft” or a “second shaft assembly”. The intermediate firing shaft 222 may include a longitudinal slot 223 in a distal end configured to receive a tab 284 on the proximal end 282 of the knife bar 280. The longitudinal slot 223 and the proximal end 282 may be configured to permit relative movement there between and can comprise a slip joint 286. The slip joint 286 can permit the intermediate firing shaft 222 of the firing member 220 to articulate the end effector 300 about the articulation joint 270 without moving, or at least substantially moving, the knife bar 280. Once the end effector 300 has been suitably oriented, the intermediate firing shaft 222 can be advanced distally until a proximal sidewall of the longitudinal slot 223 contacts the tab 284 to advance the knife bar 280 and fire the staple cartridge positioned within the channel 302. The spine 210 has an elongated opening or window 213 therein to facilitate assembly and insertion of the intermediate firing shaft 222 into the spine 210. Once the intermediate firing shaft 222 has been inserted therein, a top frame segment 215 may be engaged with the shaft frame 212 to enclose the intermediate firing shaft 222 and knife bar 280 therein. Operation of the firing member 220 may be found in U.S. Patent Application Publication No. 2014/0263541. A spine 210 can be configured to slidably support a firing member 220 and the closure tube 260 that extends around the spine 210. The spine 210 may slidably support an articulation driver 230.

[0066] The interchangeable shaft assembly 200 can include a clutch assembly 400 configured to selectively and releasably couple the articulation driver 230 to the firing member 220. The clutch assembly 400 includes a lock collar, or lock sleeve 402, positioned around the firing member 220 wherein the lock sleeve 402 can be rotated between an engaged position in which the lock sleeve 402 couples the articulation driver 230 to the firing member 220 and a disengaged position in which the articulation driver 230 is not operably coupled to the firing member 220. When the lock sleeve 402 is in the engaged position, distal movement of the firing member 220 can move the articulation driver 230 distally and, correspondingly, proximal movement of the firing member 220 can move the articulation driver 230 proximally. When the lock sleeve 402 is in the disengaged position, movement of the firing member 220 is not transmitted to the articulation driver 230 and, as a result, the firing member 220 can move independently of the articulation driver 230. The nozzle 201 may be employed to operably engage and disengage the articulation drive system with the firing drive system in the various manners described in U.S. Patent Application Publication No. 2014/0263541.

[0067] The interchangeable shaft assembly 200 can comprise a slip ring assembly 600 which can be configured to conduct electrical power to and/or from the end effector 300 and/or communicate signals to and/or from the end effector 300, for example. The slip ring assembly 600 can comprise a proximal connector flange 604 and a distal connector flange 601 positioned within a slot defined in the nozzle portions 202, 203. The proximal connector flange 604 can comprise a first face and the distal connector flange 601 can comprise a second face positioned adjacent to and movable relative to the first face. The distal connector flange 601 can rotate relative to the proximal connector flange 604 about the shaft axis SA-SA (FIG. 1). The proximal connector flange 604 can comprise a plurality of concentric, or at least substantially concentric, conductors 602 defined in the first face thereof. A connector 607 can be mounted on the proximal side of the distal connector flange 601 and may have a plurality of contacts wherein each contact corresponds to and is in electrical contact with one of the conductors 602. Such an arrangement permits relative rotation between the proximal connector flange 604 and the distal connector flange 601 while maintaining electrical contact there between. The proximal connector flange 604 can include an electrical connector 606 that can place the conductors 602 in signal communication with a shaft circuit board, for example. In at least one instance, a wiring harness comprising a plurality of conductors can extend between the electrical connector 606 and the shaft circuit board. The electrical connector 606 may extend proximally through a connector opening defined in the chassis mounting flange. U.S. Patent Application Publication No. 2014/0263551, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, is incorporated herein by reference in its entirety. U.S. Patent Application Publication No. 2014/0263552, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, is incorporated by reference in its entirety. Further details regarding slip ring assembly 600 may be found in U.S. Patent Application Publication No. 2014/0263541.

[0068] The interchangeable shaft assembly 200 can include a proximal portion fixably mounted to the handle assembly 14 and a distal portion that is rotatable about a longitudinal axis. The rotatable distal shaft portion can be rotated relative to the proximal portion about the slip ring assembly 600. The distal connector flange 601 of the slip ring assembly 600 can be positioned within the rotatable distal shaft portion.

[0069] FIG. 4 is an exploded view of one aspect of an end effector 300 of the surgical instrument 10 of FIG. 1 according to one aspect of this disclosure. The end effector 300 may include the anvil 306 and the surgical staple cartridge 304. The anvil 306 may be coupled to an elongated channel 302. Apertures 199 can be defined in the elongated channel 302 to receive pins 152 extending from the anvil 306 to allow the anvil 306 to pivot from an open position to a closed position relative to the elongated channel 302 and surgical staple cartridge 304. A firing bar 172 is configured to longitudinally translate into the end effector 300. The firing bar 172 may be constructed from one solid section, or may include a laminate material comprising a stack of steel plates. The firing bar 172 comprises an I-beam 178 and a cutting edge 182 at a distal end thereof. A distally projecting end of the firing bar 172 can be attached to the I-beam 178 to assist in spacing the anvil 306 from a surgical staple cartridge 304 positioned in the elongated channel 302 when the anvil 306 is in a closed position. The I-beam 178 may include a sharpened cutting edge 182 to sever tissue as the I-beam 178 is advanced distally by the firing bar 172. In operation, the I-beam 178 may, or fire, the surgical staple cartridge 304. The surgical staple cartridge 304 can include a molded cartridge body 194 that holds a plurality of staples 191 resting upon staple drivers 192 within respective upwardly open staple cavities 195. A wedge sled 190 is driven distally by the I-beam 178, sliding upon a cartridge tray 196 of the surgical staple cartridge 304. The wedge sled 190 upwardly cams the staple drivers 192 to force out the staples 191 into deforming contact with the anvil 306 while the cutting edge 182 of the I-beam 178 severs clamped tissue.

[0070] The I-beam 178 can include upper pins 180 that engage the anvil 306 during firing. The I-beam 178 may include middle pins 184 and a bottom foot 186 to engage portions of the cartridge body 194, cartridge tray 196, and elongated channel 302. When a surgical staple cartridge 304 is positioned within the elongated channel 302, a slot 193 defined in the cartridge body 194 can be aligned with a longitudinal slot 197 defined in the cartridge tray 196 and a slot 189 defined in the elongated channel 302. In use, the I-beam 178 can slide through the aligned longitudinal slots 193, 197, and 189 wherein, as indicated in FIG. 4, the bottom foot 186 of the I-beam 178 can engage a groove running along the bottom surface of elongated channel 302 along the length of slot 189, the middle pins 184 can engage the top surfaces of cartridge tray 196 along the length of longitudinal slot 197, and the upper pins 180 can engage the anvil 306. The I-beam 178 can space, or limit the relative movement between, the anvil 306 and the surgical staple cartridge 304 as the firing bar 172 is advanced distally to fire the staples from the surgical staple cartridge 304 and/or incise the tissue captured between the anvil 306 and the surgical staple cartridge 304. The firing bar 172 and the I-beam 178 can be retracted proximally allowing the anvil 306 to be opened to release the two stapled and severed tissue portions.

[0071] FIGS. 5A-5Bis a block diagram of a control circuit 700 of the surgical instrument 10 of FIG. 1 spanning two drawing sheets according to one aspect of this disclosure. Referring primarily to FIGS. 6A-6B, a handle assembly 702 may include a motor 714 which can be controlled by a motor driver 715 and can be employed by the firing system of the surgical instrument 10. In various forms, the motor 714 may be a DC brushed driving motor having a maximum rotational speed of approximately 25,000 RPM. In other arrangements, the motor 714 may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. The motor driver 715 may comprise an H-Bridge driver comprising field-effect transistors (FETs) 719, for example. The motor 714 can be powered by the power assembly 706 releasably mounted to the handle assembly 200 for supplying control power to the surgical instrument 10. The power assembly 706 may comprise a battery which may include a number of battery cells connected in series that can be used as the power source to power the surgical instrument 10. In certain circumstances, the battery cells of the power assembly 706 may be replaceable and/or rechargeable. In at least one example, the battery cells can be Lithium-Ion batteries which can be separably couplable to the power assembly 706.

[0072] The shaft assembly 704 may include a shaft assembly controller 722 which can communicate with a safety controller and power management controller 716 through an interface while the shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702. For example, the interface may comprise a first interface portion 725 which may include one or more electric connectors for coupling engagement with corresponding shaft assembly electric connectors and a second interface portion 727 which may include one or more electric connectors for coupling engagement with corresponding power assembly electric connectors to permit electrical communication between the shaft assembly controller 722 and the power management controller 716 while the shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702. One or more communication signals can be transmitted through the interface to communicate one or more of the power requirements of the attached interchangeable shaft assembly 704 to the power management controller 716. In response, the power management controller may modulate the power output of the battery of the power assembly 706, as described below in greater detail, in accordance with the power requirements of the attached shaft assembly 704. The connectors may comprise switches which can be activated after mechanical coupling engagement of the handle assembly 702 to the shaft assembly 704 and/or to the power assembly 706 to allow electrical communication between the shaft assembly controller 722 and the power management controller 716.

[0073] The interface can facilitate transmission of the one or more communication signals between the power management controller 716 and the shaft assembly controller 722 by routing such communication signals through a main controller 717 residing in the handle assembly 702, for example. In other circumstances, the interface can facilitate a direct line of communication between the power management controller 716 and the shaft assembly controller 722 through the handle assembly 702 while the shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702.

[0074] The main controller 717 may be any single core or multicore processor such as those known under the trade name ARM Cortex by Texas Instruments. In one aspect, the main controller 717 may be an LM4F230H5QR ARM Cortex-M4F Processor Core, available from Texas Instruments, for example, comprising on-chip memory of 256 KB single-cycle flash memory, or other non-volatile memory, up to 40 MHz, a prefetch buffer to improve performance above 40 MHz, a 32 KB single-cycle serial random access memory (SRAM), internal read-only memory (ROM) loaded with StellarisWare® software, 2 KB electrically erasable programmable read-only memory (EEPROM), one or more pulse width modulation (PWM) modules, one or more quadrature encoder inputs (QEI) analog, one or more 12-bit Analog-to-Digital Converters (ADC) with 12 analog input channels, details of which are available for the product datasheet.

[0075] The safety controller may be a safety controller platform comprising two controller-based families such as TMS570 and RM4x known under the trade name Hercules ARM Cortex R4, also by Texas Instruments. The safety controller may be configured specifically for IEC 61508 and ISO 26262 safety critical applications, among others, to provide advanced integrated safety features while delivering scalable performance, connectivity, and memory options.

[0076] The power assembly 706 may include a power management circuit which may comprise the power management controller 716, a power modulator 738, and a current sense circuit 736. The power management circuit can be configured to modulate power output of the battery based on the power requirements of the shaft assembly 704 while the shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702. The power management controller 716 can be programmed to control the power modulator 738 of the power output of the power assembly 706 and the current sense circuit 736 can be employed to monitor power output of the power assembly 706 to provide feedback to the power management controller 716 about the power output of the battery so that the power management controller 716 may adjust the power output of the power assembly 706 to maintain a desired output. The power management controller 716 and/or the shaft assembly controller 722 each may comprise one or more processors and/or memory units which may store a number of software modules.

[0077] The surgical instrument 10 (FIGS. 1-4) may comprise an output device 742 which may include devices for providing a sensory feedback to a user. Such devices may comprise, for example, visual feedback devices (e.g., an LCD display screen, LED indicators), audio feedback devices (e.g., a speaker, a buzzer) or tactile feedback devices (e.g., haptic actuators). In certain circumstances, the output device 742 may comprise a display 743 which may be included in the handle assembly 702. The shaft assembly controller 722 and/or the power management controller 716 can provide feedback to a user of the surgical instrument 10 through the output device 742. The interface can be configured to connect the shaft assembly controller 722 and/or the power management controller 716 to the output device 742. The output device 742 can instead be integrated with the power assembly 706. In such circumstances, communication between the output device 742 and the shaft assembly controller 722 may be accomplished through the interface while the shaft assembly 704 is coupled to the handle assembly 702.

[0078] The control circuit 700 comprises circuit segments configured to control operations of the powered surgical instrument 10. A safety controller segment (Segment 1) comprises a safety controller and the main controller 717 segment (Segment 2). The safety controller and/or the main controller 717 are configured to interact with one or more additional circuit segments such as an acceleration segment, a display segment, a shaft segment, an encoder segment, a motor segment, and a power segment. Each of the circuit segments may be coupled to the safety controller and/or the main controller 717. The main controller 717 is also coupled to a flash memory. The main controller 717 also comprises a serial communication interface. The main controller 717 comprises a plurality of inputs coupled to, for example, one or more circuit segments, a battery, and/or a plurality of switches. The segmented circuit may be implemented by any suitable circuit, such as, for example, a printed circuit board assembly (PCBA) within the powered surgical instrument 10. It should be understood that the term processor as used herein includes any microprocessor, processors, controller, controllers, or other basic computing device that incorporates the functions of a computer's central processing unit (CPU) on an integrated circuit or at most a few integrated circuits. The main controller 717 is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and provides results as output. It is an example of sequential digital logic, as it has internal memory. The control circuit 700 can be configured to implement one or more of the processes described herein.

[0079] The acceleration segment (Segment 3) comprises an accelerometer. The accelerometer is configured to detect movement or acceleration of the powered surgical instrument 10. Input from the accelerometer may be used to transition to and from a sleep mode, identify an orientation of the powered surgical instrument, and/or identify when the surgical instrument has been dropped. In some examples, the acceleration segment is coupled to the safety controller and/or the main controller 717.

[0080] The display segment (Segment 4) comprises a display connector coupled to the main controller 717. The display connector couples the main controller 717 to a display through one or more integrated circuit drivers of the display. The integrated circuit drivers of the display may be integrated with the display and/or may be located separately from the display. The display may comprise any suitable display, such as, for example, an organic light-emitting diode (OLED) display, a liquid-crystal display (LCD), and/or any other suitable display. In some examples, the display segment is coupled to the safety controller.

[0081] The shaft segment (Segment 5) comprises controls for an interchangeable shaft assembly 200 (FIGS. 1 and 3) coupled to the surgical instrument 10 (FIGS. 1-4) and/or one or more controls for an end effector 300 coupled to the interchangeable shaft assembly 200. The shaft segment comprises a shaft connector configured to couple the main controller 717 to a shaft PCBA. The shaft PCBA comprises a low-power microcontroller with a ferroelectric random access memory (FRAM), an articulation switch, a shaft release Hall effect switch, and a shaft PCBA EEPROM. The shaft PCBA EEPROM comprises one or more parameters, routines, and/or programs specific to the interchangeable shaft assembly 200 and/or the shaft PCBA. The shaft PCBA may be coupled to the interchangeable shaft assembly 200 and/or integral with the surgical instrument 10. In some examples, the shaft segment comprises a second shaft EEPROM. The second shaft EEPROM comprises a plurality of algorithms, routines, parameters, and/or other data corresponding to one or more shaft assemblies 200 and/or end effectors 300 that may be interfaced with the powered surgical instrument 10.

[0082] The position encoder segment (Segment 6) comprises one or more magnetic angle rotary position encoders. The one or more magnetic angle rotary position encoders are configured to identify the rotational position of the motor 714, an interchangeable shaft assembly 200 (FIGS. 1 and 3), and/or an end effector 300 of the surgical instrument 10 (FIGS. 1-4). In some examples, the magnetic angle rotary position encoders may be coupled to the safety controller and/or the main controller 717.

[0083] The motor circuit segment (Segment 7) comprises a motor 714 configured to control movements of the powered surgical instrument 10 (FIGS. 1-4). The motor 714 is coupled to the main microcontroller processor 717 by an H-bridge driver comprising one or more H-bridge field-effect transistors (FETs) and a motor controller. The H-bridge driver is also coupled to the safety controller. A motor current sensor is coupled in series with the motor to measure the current draw of the motor. The motor current sensor is in signal communication with the main controller 717 and/or the safety controller. In some examples, the motor 714 is coupled to a motor electromagnetic interference (EMI) filter.

[0084] The motor controller controls a first motor flag and a second motor flag to indicate the status and position of the motor 714 to the main controller 717. The main controller 717 provides a pulse-width modulation (PWM) high signal, a PWM low signal, a direction signal, a synchronize signal, and a motor reset signal to the motor controller through a buffer. The power segment is configured to provide a segment voltage to each of the circuit segments.

[0085] The power segment (Segment 8) comprises a battery coupled to the safety controller, the main controller 717, and additional circuit segments. The battery is coupled to the segmented circuit by a battery connector and a current sensor. The current sensor is configured to measure the total current draw of the segmented circuit. In some examples, one or more voltage converters are configured to provide predetermined voltage values to one or more circuit segments. For example, in some examples, the segmented circuit may comprise 3.3V voltage converters and/or 5V voltage converters. A boost converter is configured to provide a boost voltage up to a predetermined amount, such as, for example, up to 13V. The boost converter is configured to provide additional voltage and/or current during power intensive operations and prevent brownout or low-power conditions.

[0086] A plurality of switches are coupled to the safety controller and/or the main controller 717. The switches may be configured to control operations of the surgical instrument 10 (FIGS. 1-4), of the segmented circuit, and/or indicate a status of the surgical instrument 10. A bail-out door switch and Hall effect switch for bailout are configured to indicate the status of a bail-out door. A plurality of articulation switches, such as, for example, a left side articulation left switch, a left side articulation right switch, a left side articulation center switch, a right side articulation left switch, a right side articulation right switch, and a right side articulation center switch are configured to control articulation of an interchangeable shaft assembly 200 (FIGS. 1 and 3) and/or the end effector 300 (FIGS. 1 and 4). A left side reverse switch and a right side reverse switch are coupled to the main controller 717. The left side switches comprising the left side articulation left switch, the left side articulation right switch, the left side articulation center switch, and the left side reverse switch are coupled to the main controller 717 by a left flex connector. The right side switches comprising the right side articulation left switch, the right side articulation right switch, the right side articulation center switch, and the right side reverse switch are coupled to the main controller 717 by a right flex connector. A firing switch, a clamp release switch, and a shaft engaged switch are coupled to the main controller 717.

[0087] Any suitable mechanical, electromechanical, or solid state switches may be employed to implement the plurality of switches, in any combination. For example, the switches may be limit switches operated by the motion of components associated with the surgical instrument 10 (FIGS. 1-4) or the presence of an object. Such switches may be employed to control various functions associated with the surgical instrument 10. A limit switch is an electromechanical device that consists of an actuator mechanically linked to a set of contacts. When an object comes into contact with the actuator, the device operates the contacts to make or break an electrical connection. Limit switches are used in a variety of applications and environments because of their ruggedness, ease of installation, and reliability of operation. They can determine the presence or absence, passing, positioning, and end of travel of an object. In other implementations, the switches may be solid state switches that operate under the influence of a magnetic field such as Hall-effect devices, magneto-resistive (MR) devices, giant magneto-resistive (GMR) devices, magnetometers, among others. In other implementations, the switches may be solid state switches that operate under the influence of light, such as optical sensors, infrared sensors, ultraviolet sensors, among others. Still, the switches may be solid state devices such as transistors (e.g., FET, Junction-FET, metal-oxide semiconductor-FET (MOSFET), bipolar, and the like). Other switches may include wireless switches, ultrasonic switches, accelerometers, inertial sensors, among others.

[0088] FIG. 6 is another block diagram of the control circuit 700 of the surgical instrument of FIG. 1 illustrating interfaces between the handle assembly 702 and the power assembly 706 and between the handle assembly 702 and the interchangeable shaft assembly 704 according to one aspect of this disclosure. The handle assembly 702 may comprise a main controller 717, a shaft assembly connector 726 and a power assembly connector 730. The power assembly 706 may include a power assembly connector 732, a power management circuit 734 that may comprise the power management controller 716, a power modulator 738, and a current sense circuit 736. The shaft assembly connectors 730, 732 form an interface 727. The power management circuit 734 can be configured to modulate power output of the battery 707 based on the power requirements of the interchangeable shaft assembly 704 while the interchangeable shaft assembly 704 and the power assembly 706 are coupled to the handle assembly 702. The power management controller 716 can be programmed to control the power modulator 738 of the power output of the power assembly 706 and the current sense circuit 736 can be employed to monitor power output of the power assembly 706 to provide feedback to the power management controller 716 about the power output of the battery 707 so that the power management controller 716 may adjust the power output of the power assembly 706 to maintain a desired output. The shaft assembly 704 comprises a shaft processor 719 coupled to a non-volatile memory 721 and shaft assembly connector 728 to electrically couple the shaft assembly 704 to the handle assembly 702. The shaft assembly connectors 726, 728 form interface 725. The main controller 717, the shaft processor 719, and/or the power management controller 716 can be configured to implement one or more of the processes described herein.

[0089] The surgical instrument 10 (FIGS. 1-4) may comprise an output device 742 to a sensory feedback to a user. Such devices may comprise visual feedback devices (e.g., an LCD display screen, LED indicators), audio feedback devices (e.g., a speaker, a buzzer), or tactile feedback devices (e.g., haptic actuators). In certain circumstances, the output device 742 may comprise a display 743 that may be included in the handle assembly 702. The shaft assembly controller 722 and/or the power management controller 716 can provide feedback to a user of the surgical instrument 10 through the output device 742. The interface 727 can be configured to connect the shaft assembly controller 722 and/or the power management controller 716 to the output device 742. The output device 742 can be integrated with the power assembly 706. Communication between the output device 742 and the shaft assembly controller 722 may be accomplished through the interface 725 while the interchangeable shaft assembly 704 is coupled to the handle assembly 702. Having described a control circuit 700 (FIGS. 5A-5B and 6) for controlling the operation of the surgical instrument 10 (FIGS. 1-4), the disclosure now turns to various configurations of the surgical instrument 10 (FIGS. 1-4) and control circuit 700.

[0090] FIG. 7 illustrates a control circuit 800 configured to control aspects of the surgical instrument 10 (FIGS. 1-4) according to one aspect of this disclosure. The control circuit 800 can be configured to implement various processes described herein. The control circuit 800 may comprise a controller comprising one or more processors 802 (e.g., microprocessor, microcontroller) coupled to at least one memory circuit 804. The memory circuit 804 stores machine executable instructions that when executed by the processor 802, cause the processor 802 to execute machine instructions to implement various processes described herein. The processor 802 may be any one of a number of single or multi-core processors known in the art. The memory circuit 804 may comprise volatile and non-volatile storage media. The processor 802 may include an instruction processing unit 806 and an arithmetic unit 808. The instruction processing unit may be configured to receive instructions from the memory circuit 804.

[0091] FIG. 8 illustrates a combinational logic circuit 810 configured to control aspects of the surgical instrument 10 (FIGS. 1-4) according to one aspect of this disclosure. The combinational logic circuit 810 can be configured to implement various processes described herein. The circuit 810 may comprise a finite state machine comprising a combinational logic circuit 812 configured to receive data associated with the surgical instrument 10 at an input 814, process the data by the combinational logic 812, and provide an output 816.

[0092] FIG. 9 illustrates a sequential logic circuit 820 configured to control aspects of the surgical instrument 10 (FIGS. 1-4) according to one aspect of this disclosure. The sequential logic circuit 820 or the combinational logic circuit 822 can be configured to implement various processes described herein. The circuit 820 may comprise a finite state machine. The sequential logic circuit 820 may comprise a combinational logic circuit 822, at least one memory circuit 824, and a clock 829, for example. The at least one memory circuit 820 can store a current state of the finite state machine. In certain instances, the sequential logic circuit 820 may be synchronous or asynchronous. The combinational logic circuit 822 is configured to receive data associated with the surgical instrument 10 an input 826, process the data by the combinational logic circuit 822, and provide an output 828. In other aspects, the circuit may comprise a combination of the processor 802 and the finite state machine to implement various processes herein. In other aspects, the finite state machine may comprise a combination of the combinational logic circuit 810 and the sequential logic circuit 820.

[0093] Aspects may be implemented as an article of manufacture. The article of manufacture may include a computer readable storage medium arranged to store logic, instructions, and/or data for performing various operations of one or more aspects. For example, the article of manufacture may comprise a magnetic disk, optical disk, flash memory, or firmware containing computer program instructions suitable for execution by a general purpose processor or application specific processor.

[0094] FIG. 10 is a diagram of an absolute positioning system 1100 of the surgical instrument 10 (FIGS. 1-4) where the absolute positioning system 1100 comprises a controlled motor drive circuit arrangement comprising a sensor arrangement 1102 according to one aspect of this disclosure. The sensor arrangement 1102 for an absolute positioning system 1100 provides a unique position signal corresponding to the location of a displacement member 1111. Turning briefly to FIGS. 2-4, in one aspect the displacement member 1111 represents the longitudinally movable drive member 120 (FIG. 2) comprising a rack of drive teeth 122 for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84. In other aspects, the displacement member 1111 represents the firing member 220 (FIG. 3), which could be adapted and configured to include a rack of drive teeth. In yet another aspect, the displacement member 1111 represents the firing bar 172 (FIG. 4) or the I-beam 178 (FIG. 4), each of which can be adapted and configured to include a rack of drive teeth. Accordingly, as used herein, the term displacement member is used generically to refer to any movable member of the surgical instrument 10 such as the drive member 120, the firing member 220, the firing bar 172, the I-beam 178, or any element that can be displaced. In one aspect, the longitudinally movable drive member 120 is coupled to the firing member 220, the firing bar 172, and the I-beam 178. Accordingly, the absolute positioning system 1100 can, in effect, track the linear displacement of the I-beam 178 by tracking the linear displacement of the longitudinally movable drive member 120. In various other aspects, the displacement member 1111 may be coupled to any sensor suitable for measuring linear displacement. Thus, the longitudinally movable drive member 120, the firing member 220, the firing bar 172, or the I-beam 178, or combinations, may be coupled to any suitable linear displacement sensor. Linear displacement sensors may include contact or non-contact displacement sensors. Linear displacement sensors may comprise linear variable differential transformers (LVDT), differential variable reluctance transducers (DVRT), a slide potentiometer, a magnetic sensing system comprising a movable magnet and a series of linearly arranged Hall effect sensors, a magnetic sensing system comprising a fixed magnet and a series of movable linearly arranged Hall effect sensors, an optical sensing system comprising a movable light source and a series of linearly arranged photo diodes or photo detectors, or an optical sensing system comprising a fixed light source and a series of movable linearly arranged photo diodes or photo detectors, or any combination thereof.

[0095] An electric motor 1120 can include a rotatable shaft 1116 that operably interfaces with a gear assembly 1114 that is mounted in meshing engagement with a set, or rack, of drive teeth on the displacement member 1111. A sensor element 1126 may be operably coupled to a gear assembly 1114 such that a single revolution of the sensor element 1126 corresponds to some linear longitudinal translation of the displacement member 1111. An arrangement of gearing and sensors 1118 can be connected to the linear actuator via a rack and pinion arrangement or a rotary actuator via a spur gear or other connection. A power source 1129 supplies power to the absolute positioning system 1100 and an output indicator 1128 may display the output of the absolute positioning system 1100. In FIG. 2, the displacement member 1111 represents the longitudinally movable drive member 120 comprising a rack of drive teeth 122 formed thereon for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84. The displacement member 1111 represents the longitudinally movable firing member 220, firing bar 172, I-beam 178, or combinations thereof.

[0096] A single revolution of the sensor element 1126 associated with the position sensor 1112 is equivalent to a longitudinal linear displacement d1 of the of the displacement member 1111, where d1 is the longitudinal linear distance that the displacement member 1111 moves from point “a” to point “b” after a single revolution of the sensor element 1126 coupled to the displacement member 1111. The sensor arrangement 1102 may be connected via a gear reduction that results in the position sensor 1112 completing one or more revolutions for the full stroke of the displacement member 1111. The position sensor 1112 may complete multiple revolutions for the full stroke of the displacement member 1111.

[0097] A series of switches 1122a-1122n, where n is an integer greater than one, may be employed alone or in combination with gear reduction to provide a unique position signal for more than one revolution of the position sensor 1112. The state of the switches 1122a-1122n are fed back to a controller 1104 that applies logic to determine a unique position signal corresponding to the longitudinal linear displacement d1+d2+ . . . dn of the displacement member 1111. The output 1124 of the position sensor 1112 is provided to the controller 1104. The position sensor 1112 of the sensor arrangement 1102 may comprise a magnetic sensor, an analog rotary sensor like a potentiometer, an array of analog Hall-effect elements, which output a unique combination of position signals or values.

[0098] The absolute positioning system 1100 provides an absolute position of the displacement member 1111 upon power up of the instrument without retracting or advancing the displacement member 1111 to a reset (zero or home) position as may be required with conventional rotary encoders that merely count the number of steps forwards or backwards that the motor 1120 has taken to infer the position of a device actuator, drive bar, knife, and the like.

[0099] The controller 1104 may be programmed to perform various functions such as precise control over the speed and position of the knife and articulation systems. In one aspect, the controller 1104 includes a processor 1108 and a memory 1106. The electric motor 1120 may be a brushed DC motor with a gearbox and mechanical links to an articulation or knife system. In one aspect, a motor driver 1110 may be an A3941 available from Allegro Microsystems, Inc. Other motor drivers may be readily substituted for use in the absolute positioning system 1100. A more detailed description of the absolute positioning system 1100 is described in U.S. patent application Ser. No. 15/130,590, entitled SYSTEMS AND METHODS FOR CONTROLLING A SURGICAL STAPLING AND CUTTING INSTRUMENT, filed on Apr. 15, 2016, the entire disclosure of which is herein incorporated by reference.

[0100] The controller 1104 may be programmed to provide precise control over the speed and position of the displacement member 1111 and articulation systems. The controller 1104 may be configured to compute a response in the software of the controller 1104. The computed response is compared to a measured response of the actual system to obtain an “observed” response, which is used for actual feedback decisions. The observed response is a favorable, tuned, value that balances the smooth, continuous nature of the simulated response with the measured response, which can detect outside influences on the system.

[0101] The absolute positioning system 1100 may comprise and/or be programmed to implement a feedback controller, such as a PID, state feedback, and adaptive controller. A power source 1129 converts the signal from the feedback controller into a physical input to the system, in this case voltage. Other examples include pulse width modulation (PWM) of the voltage, current, and force. Other sensor(s) 1118 may be provided to measure physical parameters of the physical system in addition to position measured by the position sensor 1112. In a digital signal processing system, absolute positioning system 1100 is coupled to a digital data acquisition system where the output of the absolute positioning system 1100 will have finite resolution and sampling frequency. The absolute positioning system 1100 may comprise a compare and combine circuit to combine a computed response with a measured response using algorithms such as weighted average and theoretical control loop that drives the computed response towards the measured response. The computed response of the physical system takes into account properties like mass, inertial, viscous friction, inductance resistance, etc., to predict what the states and outputs of the physical system will be by knowing the input. The controller 1104 may be a control circuit 700 (FIGS. 5A-5B).

[0102] The motor driver 1110 may be an A3941 available from Allegro Microsystems, Inc. The A3941 driver 1110 is a full-bridge controller for use with external N-channel power metal oxide semiconductor field effect transistors (MOSFETs) specifically designed for inductive loads, such as brush DC motors. The driver 1110 comprises a unique charge pump regulator provides full (>10 V) gate drive for battery voltages down to 7 V and allows the A3941 to operate with a reduced gate drive, down to 5.5 V. A bootstrap capacitor may be employed to provide the above-battery supply voltage required for N-channel MOSFETs. An internal charge pump for the high-side drive allows DC (100% duty cycle) operation. The full bridge can be driven in fast or slow decay modes using diode or synchronous rectification. In the slow decay mode, current recirculation can be through the high-side or the lowside FETs. The power FETs are protected from shoot-through by resistor adjustable dead time. Integrated diagnostics provide indication of undervoltage, overtemperature, and power bridge faults, and can be configured to protect the power MOSFETs under most short circuit conditions. Other motor drivers may be readily substituted for use in the absolute positioning system 1100.

[0103] Having described a general architecture for implementing aspects of an absolute positioning system 1100 for a sensor arrangement 1102, the disclosure now turns to FIGS. 11 and 12 for a description of one aspect of a sensor arrangement 1102 for the absolute positioning system 1100. FIG. 11 is an exploded perspective view of the sensor arrangement 1102 for the absolute positioning system 1100 showing a circuit 1205 and the relative alignment of the elements of the sensor arrangement 1102, according to one aspect. The sensor arrangement 1102 for an absolute positioning system 1100 comprises a position sensor 1200, a magnet 1202 sensor element, a magnet holder 1204 that turns once every full stroke of the displacement member 1111, and a gear assembly 1206 to provide a gear reduction. With reference briefly to FIG. 2, the displacement member 1111 may represent the longitudinally movable drive member 120 comprising a rack of drive teeth 122 for meshing engagement with a corresponding drive gear 86 of the gear reducer assembly 84. Returning to FIG. 11, a structural element such as bracket 1216 is provided to support the gear assembly 1206, the magnet holder 1204, and the magnet 1202. The position sensor 1200 comprises magnetic sensing elements such as Hall elements and is placed in proximity to the magnet 1202. As the magnet 1202 rotates, the magnetic sensing elements of the position sensor 1200 determine the absolute angular position of the magnet 1202 over one revolution.

[0104] The sensor arrangement 1102 may comprises any number of magnetic sensing elements, such as, for example, magnetic sensors classified according to whether they measure the total magnetic field or the vector components of the magnetic field. The techniques used to produce both types of magnetic sensors encompass many aspects of physics and electronics. The technologies used for magnetic field sensing include search coil, fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect, anisotropic magnetoresistance, giant magnetoresistance, magnetic tunnel junctions, giant magnetoimpedance, magnetostrictive/piezoelectric composites, magnetodiode, magnetotransistor, fiber optic, magnetooptic, and microelectromechanical systems-based magnetic sensors, among others.

[0105] A gear assembly comprises a first gear 1208 and a second gear 1210 in meshing engagement to provide a 3:1 gear ratio connection. A third gear 1212 rotates about a shaft 1214. The third gear 1212 is in meshing engagement with the displacement member 1111 (or 120 as shown in FIG. 2) and rotates in a first direction as the displacement member 1111 advances in a distal direction D and rotates in a second direction as the displacement member 1111 retracts in a proximal direction P. The second gear 1210 also rotates about the shaft 1214 and, therefore, rotation of the second gear 1210 about the shaft 1214 corresponds to the longitudinal translation of the displacement member 1111. Thus, one full stroke of the displacement member 1111 in either the distal or proximal directions D, P corresponds to three rotations of the second gear 1210 and a single rotation of the first gear 1208. Since the magnet holder 1204 is coupled to the first gear 1208, the magnet holder 1204 makes one full rotation with each full stroke of the displacement member 1111.

[0106] The position sensor 1200 is supported by a position sensor holder 1218 defining an aperture 1220 suitable to contain the position sensor 1200 in precise alignment with a magnet 1202 rotating below within the magnet holder 1204. The fixture is coupled to the bracket 1216 and to the circuit 1205 and remains stationary while the magnet 1202 rotates with the magnet holder 1204. A hub 1222 is provided to mate with the first gear 1208 and the magnet holder 1204. The second gear 1210 and third gear 1212 coupled to shaft 1214 also are shown.

[0107] FIG. 12 is a diagram of a position sensor 1200 for an absolute positioning system 1100 comprising a magnetic rotary absolute positioning system according to one aspect of this disclosure. The position sensor 1200 may be implemented as an AS5055EQFT single-chip magnetic rotary position sensor available from Austria Microsystems, AG. The position sensor 1200 is interfaced with the controller 1104 to provide an absolute positioning system 1100. The position sensor 1200 is a low-voltage and low-power component and includes four Hall-effect elements 1228A, 1228B, 1228C, 1228D in an area 1230 of the position sensor 1200 that is located above the magnet 1202 (FIGS. 15 and 16). A high-resolution ADC 1232 and a smart power management controller 1238 are also provided on the chip. A CORDIC processor 1236 (for Coordinate Rotation Digital Computer), also known as the digit-by-digit method and Volder's algorithm, is provided to implement a simple and efficient algorithm to calculate hyperbolic and trigonometric functions that require only addition, subtraction, bitshift, and table lookup operations. The angle position, alarm bits, and magnetic field information are transmitted over a standard serial communication interface such as an SPI interface 1234 to the controller 1104. The position sensor 1200 provides 12 or 14 bits of resolution. The position sensor 1200 may be an AS5055 chip provided in a small QFN 16-pin 4×4×0.85 mm package.

[0108] The Hall-effect elements 1228A, 1228B, 1228C, 1228D are located directly above the rotating magnet 1202 (FIG. 11). The Hall-effect is a well-known effect and for expediency will not be described in detail herein, however, generally, the Hall-effect produces a voltage difference (the Hall voltage) across an electrical conductor transverse to an electric current in the conductor and a magnetic field perpendicular to the current. A Hall coefficient is defined as the ratio of the induced electric field to the product of the current density and the applied magnetic field. It is a characteristic of the material from which the conductor is made, since its value depends on the type, number, and properties of the charge carriers that constitute the current. In the AS5055 position sensor 1200, the Hall-effect elements 1228A, 1228B, 1228C, 1228D are capable producing a voltage signal that is indicative of the absolute position of the magnet 1202 in terms of the angle over a single revolution of the magnet 1202. This value of the angle, which is unique position signal, is calculated by the CORDIC processor 1236 is stored onboard the AS5055 position sensor 1200 in a register or memory. The value of the angle that is indicative of the position of the magnet 1202 over one revolution is provided to the controller 1104 in a variety of techniques, e.g., upon power up or upon request by the controller 1104.

[0109] The AS5055 position sensor 1200 requires only a few external components to operate when connected to the controller 1104. Six wires are needed for a simple application using a single power supply: two wires for power and four wires 1240 for the SPI interface 1234 with the controller 1104. A seventh connection can be added in order to send an interrupt to the controller 1104 to inform that a new valid angle can be read. Upon power-up, the AS5055 position sensor 1200 performs a full power-up sequence including one angle measurement. The completion of this cycle is indicated as an INT output 1242, and the angle value is stored in an internal register. Once this output is set, the AS5055 position sensor 1200 suspends to sleep mode. The controller 1104 can respond to the INT request at the INT output 1242 by reading the angle value from the AS5055 position sensor 1200 over the SPI interface 1234. Once the angle value is read by the controller 1104, the INT output 1242 is cleared again. Sending a “read angle” command by the SPI interface 1234 by the controller 1104 to the position sensor 1200 also automatically powers up the chip and starts another angle measurement. As soon as the controller 1104 has completed reading of the angle value, the INT output 1242 is cleared and a new result is stored in the angle register. The completion of the angle measurement is again indicated by setting the INT output 1242 and a corresponding flag in the status register.

[0110] Due to the measurement principle of the AS5055 position sensor 1200, only a single angle measurement is performed in very short time (˜600 μs) after each power-up sequence. As soon as the measurement of one angle is completed, the AS5055 position sensor 1200 suspends to power-down state. An on-chip filtering of the angle value by digital averaging is not implemented, as this would require more than one angle measurement and, consequently, a longer power-up time that is not desired in low-power applications. The angle jitter can be reduced by averaging of several angle samples in the controller 1104. For example, an averaging of four samples reduces the jitter by 6 dB (50%).

[0111] FIG. 13 is a section view of an end effector 2502 of the surgical instrument 10 (FIGS. 1-4) showing an I-beam 2514 firing stroke relative to tissue 2526 grasped within the end effector 2502 according to one aspect of this disclosure. The end effector 2502 is configured to operate with the surgical instrument 10 shown in FIGS. 1-4. The end effector 2502 comprises an anvil 2516 and an elongated channel 2503 with a staple cartridge 2518 positioned in the elongated channel 2503. A firing bar 2520 is translatable distally and proximally along a longitudinal axis 2515 of the end effector 2502. When the end effector 2502 is not articulated, the end effector 2502 is in line with the shaft of the instrument. An I-beam 2514 comprising a cutting edge 2509 is illustrated at a distal portion of the firing bar 2520. A wedge sled 2513 is positioned in the staple cartridge 2518. As the I-beam 2514 translates distally, the cutting edge 2509 contacts and may cut tissue 2526 positioned between the anvil 2516 and the staple cartridge 2518. Also, the I-beam 2514 contacts the wedge sled 2513 and pushes it distally, causing the wedge sled 2513 to contact staple drivers 2511. The staple drivers 2511 may be driven up into staples 2505, causing the staples 2505 to advance through tissue and into pockets 2507 defined in the anvil 2516, which shape the staples 2505.

[0112] An example I-beam 2514 firing stroke is illustrated by a chart 2529 aligned with the end effector 2502. Example tissue 2526 is also shown aligned with the end effector 2502. The firing member stroke may comprise a stroke begin position 2527 and a stroke end position 2528. During an I-beam 2514 firing stroke, the I-beam 2514 may be advanced distally from the stroke begin position 2527 to the stroke end position 2528. The I-beam 2514 is shown at one example location of a stroke begin position 2527. The I-beam 2514 firing member stroke chart 2529 illustrates five firing member stroke regions 2517, 2519, 2521, 2523, 2525. In a first firing stroke region 2517, the I-beam 2514 may begin to advance distally. In the first firing stroke region 2517, the I-beam 2514 may contact the wedge sled 2513 and begin to move it distally. While in the first region, however, the cutting edge 2509 may not contact tissue and the wedge sled 2513 may not contact a staple driver 2511. After static friction is overcome, the force to drive the I-beam 2514 in the first region 2517 may be substantially constant.

[0113] In the second firing member stroke region 2519, the cutting edge 2509 may begin to contact and cut tissue 2526. Also, the wedge sled 2513 may begin to contact staple drivers 2511 to drive staples 2505. Force to drive the I-beam 2514 may begin to ramp up. As shown, tissue encountered initially may be compressed and/or thinner because of the way that the anvil 2516 pivots relative to the staple cartridge 2518. In the third firing member stroke region 2521, the cutting edge 2509 may continuously contact and cut tissue 2526 and the wedge sled 2513 may repeatedly contact staple drivers 2511. Force to drive the I-beam 2514 may plateau in the third region 2521. By the fourth firing stroke region 2523, force to drive the I-beam 2514 may begin to decline. For example, tissue in the portion of the end effector 2502 corresponding to the fourth firing region 2523 may be less compressed than tissue closer to the pivot point of the anvil 2516, requiring less force to cut. Also, the cutting edge 2509 and wedge sled 2513 may reach the end of the tissue 2526 while in the fourth region 2523. When the I-beam 2514 reaches the fifth region 2525, the tissue 2526 may be completely severed. The wedge sled 2513 may contact one or more staple drivers 2511 at or near the end of the tissue. Force to advance the I-beam 2514 through the fifth region 2525 may be reduced and, in some examples, may be similar to the force to drive the I-beam 2514 in the first region 2517. At the conclusion of the firing member stroke, the I-beam 2514 may reach the stroke end position 2528. The positioning of firing member stroke regions 2517, 2519, 2521, 2523, 2525 in FIG. 18 is just one example. In some examples, different regions may begin at different positions along the end effector longitudinal axis 2515, for example, based on the positioning of tissue between the anvil 2516 and the staple cartridge 2518.

[0114] As discussed above and with reference now to FIGS. 10-13, the electric motor 1122 positioned within the handle assembly of the surgical instrument 10 (FIGS. 1-4) can be utilized to advance and/or retract the firing system of the shaft assembly, including the I-beam 2514, relative to the end effector 2502 of the shaft assembly in order to staple and/or incise tissue captured within the end effector 2502. The I-beam 2514 may be advanced or retracted at a desired speed, or within a range of desired speeds. The controller 1104 may be configured to control the speed of the I-beam 2514. The controller 1104 may be configured to predict the speed of the I-beam 2514 based on various parameters of the power supplied to the electric motor 1122, such as voltage and/or current, for example, and/or other operating parameters of the electric motor 1122 or external influences. The controller 1104 may be configured to predict the current speed of the I-beam 2514 based on the previous values of the current and/or voltage supplied to the electric motor 1122, and/or previous states of the system like velocity, acceleration, and/or position. The controller 1104 may be configured to sense the speed of the I-beam 2514 utilizing the absolute positioning sensor system described herein. The controller can be configured to compare the predicted speed of the I-beam 2514 and the sensed speed of the I-beam 2514 to determine whether the power to the electric motor 1122 should be increased in order to increase the speed of the I-beam 2514 and/or decreased in order to decrease the speed of the I-beam 2514. U.S. Pat. No. 8,210,411, entitled MOTOR-DRIVEN SURGICAL CUTTING INSTRUMENT, which is incorporated herein by reference in its entirety. U.S. Pat. No. 7,845,537, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, which is incorporated herein by reference in its entirety.

[0115] Force acting on the I-beam 2514 may be determined using various techniques. The I-beam 2514 force may be determined by measuring the motor 2504 current, where the motor 2504 current is based on the load experienced by the I-beam 2514 as it advances distally. The I-beam 2514 force may be determined by positioning a strain gauge on the drive member 120 (FIG. 2), the firing member 220 (FIG. 2), I-beam 2514 (I-beam 178, FIG. 20), the firing bar 172 (FIG. 2), and/or on a proximal end of the cutting edge 2509. The I-beam 2514 force may be determined by monitoring the actual position of the I-beam 2514 moving at an expected velocity based on the current set velocity of the motor 2504 after a predetermined elapsed period T₁ and comparing the actual position of the I-beam 2514 relative to the expected position of the I-beam 2514 based on the current set velocity of the motor 2504 at the end of the period T₁. Thus, if the actual position of the I-beam 2514 is less than the expected position of the I-beam 2514, the force on the I-beam 2514 is greater than a nominal force. Conversely, if the actual position of the I-beam 2514 is greater than the expected position of the I-beam 2514, the force on the I-beam 2514 is less than the nominal force. The difference between the actual and expected positions of the I-beam 2514 is proportional to the deviation of the force on the I-beam 2514 from the nominal force. Such techniques are described in attorney docket number END8195USNP, which is incorporated herein by reference in its entirety.

[0116] FIG. 14 illustrates a block diagram of a surgical instrument 2500 programmed to control distal translation of a displacement member according to one aspect of this disclosure. In one aspect, the surgical instrument 2500 is programmed to control distal translation of a displacement member 1111 such as the I-beam 2514. The surgical instrument 2500 comprises an end effector 2502 that may comprise an anvil 2516, an I-beam 2514 (including a sharp cutting edge 2509), and a removable staple cartridge 2518. The end effector 2502, anvil 2516, I-beam 2514, and staple cartridge 2518 may be configured as described herein, for example, with respect to FIGS. 1-13.

[0117] The position, movement, displacement, and/or translation of a liner displacement member 1111, such as the I-beam 2514, can be measured by the absolute positioning system 1100, sensor arrangement 1102, and position sensor 1200 as shown in FIGS. 10-12 and represented as position sensor 2534 in FIG. 14. Because the I-beam 2514 is coupled to the longitudinally movable drive member 120, the position of the I-beam 2514 can be determined by measuring the position of the longitudinally movable drive member 120 employing the position sensor 2534. Accordingly, in the following description, the position, displacement, and/or translation of the I-beam 2514 can be achieved by the position sensor 2534 as described herein. A control circuit 2510, such as the control circuit 700 described in FIGS. 5A and 5B, may be programmed to control the translation of the displacement member 1111, such as the I-beam 2514, as described in connection with FIGS. 10-12. The control circuit 2510, in some examples, may comprise one or more microcontrollers, microprocessors, or other suitable processors for executing instructions that cause the processor or processors to control the displacement member, e.g., the I-beam 2514, in the manner described. In one aspect, a timer/counter circuit 2531 provides an output signal, such as elapsed time or a digital count, to the control circuit 2510 to correlate the position of the I-beam 2514 as determined by the position sensor 2534 with the output of the timer/counter circuit 2531 such that the control circuit 2510 can determine the position of the I-beam 2514 at a specific time (t) relative to a starting position. The timer/counter circuit 2531 may be configured to measure elapsed time, count external evens, or time external events.

[0118] The control circuit 2510 may generate a motor set point signal 2522. The motor set point signal 2522 may be provided to a motor controller 2508. The motor controller 2508 may comprise one or more circuits configured to provide a motor drive signal 2524 to the motor 2504 to drive the motor 2504 as described herein. In some examples, the motor 2504 may be a brushed DC electric motor, such as the motor 82, 714, 1120 shown in FIGS. 1, 5B, 10. For example, the velocity of the motor 2504 may be proportional to the motor drive signal 2524. In some examples, the motor 2504 may be a brushless direct current (DC) electric motor and the motor drive signal 2524 may comprise a pulse-width-modulated (PWM) signal provided to one or more stator windings of the motor 2504. Also, in some examples, the motor controller 2508 may be omitted and the control circuit 2510 may generate the motor drive signal 2524 directly.

[0119] The motor 2504 may receive power from an energy source 2512. The energy source 2512 may be or include a battery, a super capacitor, or any other suitable energy source 2512. The motor 2504 may be mechanically coupled to the I-beam 2514 via a transmission 2506. The transmission 2506 may include one or more gears or other linkage components to couple the motor 2504 to the I-beam 2514. A position sensor 2534 may sense a position of the I-beam 2514. The position sensor 2534 may be or include any type of sensor that is capable of generating position data that indicates a position of the I-beam 2514. In some examples, the position sensor 2534 may include an encoder configured to provide a series of pulses to the control circuit 2510 as the I-beam 2514 translates distally and proximally. The control circuit 2510 may track the pulses to determine the position of the I-beam 2514. Other suitable position sensor may be used, including, for example, a proximity sensor. Other types of position sensors may provide other signals indicating motion of the I-beam 2514. Also, in some examples, the position sensor 2534 may be omitted. Where the motor 2504 is a stepper motor, the control circuit 2510 may track the position of the I-beam 2514 by aggregating the number and direction of steps that the motor 2504 has been instructed to execute. The position sensor 2534 may be located in the end effector 2502 or at any other portion of the instrument.

[0120] The control circuit 2510 may be in communication with one or more sensors 2538. The sensors 2538 may be positioned on the end effector 2502 and adapted to operate with the surgical instrument 2500 to measure the various derived parameters such as gap distance versus time, tissue compression versus time, and anvil strain versus time. The sensors 2538 may comprise a magnetic sensor, a magnetic field sensor, a strain gauge, a pressure sensor, a force sensor, an inductive sensor such as an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor for measuring one or more parameters of the end effector 2502. The sensors 2538 may include one or more sensors.

[0121] The one or more sensors 2538 may comprise a strain gauge, such as a micro-strain gauge, configured to measure the magnitude of the strain in the anvil 2516 during a clamped condition. The strain gauge provides an electrical signal whose amplitude varies with the magnitude of the strain. The sensors 2538 may comprise a pressure sensor configured to detect a pressure generated by the presence of compressed tissue between the anvil 2516 and the staple cartridge 2518. The sensors 2538 may be configured to detect impedance of a tissue section located between the anvil 2516 and the staple cartridge 2518 that is indicative of the thickness and/or fullness of tissue located therebetween.

[0122] The sensors 2538 may be is configured to measure forces exerted on the anvil 2516 by the closure drive system 30. For example, one or more sensors 2538 can be at an interaction point between the closure tube 260 (FIG. 3) and the anvil 2516 to detect the closure forces applied by the closure tube 260 to the anvil 2516. The forces exerted on the anvil 2516 can be representative of the tissue compression experienced by the tissue section captured between the anvil 2516 and the staple cartridge 2518. The one or more sensors 2538 can be positioned at various interaction points along the closure drive system 30 (FIG. 2) to detect the closure forces applied to the anvil 2516 by the closure drive system 30. The one or more sensors 2538 may be sampled in real time during a clamping operation by a processor as described in FIGS. 5A-5B. The control circuit 2510 receives real-time sample measurements to provide analyze time based information and assess, in real time, closure forces applied to the anvil 2516.

[0123] A current sensor 2536 can be employed to measure the current drawn by the motor 2504. The force required to advance the I-beam 2514 corresponds to the current drawn by the motor 2504. The force is converted to a digital signal and provided to the control circuit 2510.

[0124] Using the physical properties of the instruments disclosed herein in connection with FIGS. 1-14, and with reference to FIG. 14, the control circuit 2510 can be configured to simulate the response of the actual system of the instrument in the software of the controller. A displacement member can be actuated to move an I-beam 2514 in the end effector 2502 at or near a target velocity. The surgical instrument 2500 can include a feedback controller, which can be one of any feedback controllers, including, but not limited to a PID, a State Feedback, LQR, and/or an Adaptive controller, for example. The surgical instrument 2500 can include a power source to convert the signal from the feedback controller into a physical input such as case voltage, pulse width modulated (PWM) voltage, frequency modulated voltage, current, torque, and/or force, for example.

[0125] The actual drive system of the surgical instrument 2500 is configured to drive the displacement member, cutting member, or I-beam 2514, by a brushed DC motor with gearbox and mechanical links to an articulation and/or knife system. Another example is the electric motor 2504 that operates the displacement member and the articulation driver, for example, of an interchangeable shaft assembly. An outside influence is an unmeasured, unpredictable influence of things like tissue, surrounding bodies and friction on the physical system. Such outside influence can be referred to as drag which acts in opposition to the electric motor 2504. The outside influence, such as drag, may cause the operation of the physical system to deviate from a desired operation of the physical system.

[0126] Before explaining aspects of the surgical instrument 2500 in detail, it should be noted that the example aspects are not limited in application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The example aspects may be implemented or incorporated in other aspects, variations and modifications, and may be practiced or carried out in various ways. Further, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the example aspects for the convenience of the reader and are not for the purpose of limitation thereof. Also, it will be appreciated that one or more of the following-described aspects, expressions of aspects and/or examples, can be combined with any one or more of the other following-described aspects, expressions of aspects and/or examples.

[0127] Various example aspects are directed to a surgical instrument 2500 comprising an end effector 2502 with motor-driven surgical stapling and cutting implements. For example, a motor 2504 may drive a displacement member distally and proximally along a longitudinal axis of the end effector 2502. The end effector 2502 may comprise a pivotable anvil 2516 and, when configured for use, a staple cartridge 2518 positioned opposite the anvil 2516. A clinician may grasp tissue between the anvil 2516 and the staple cartridge 2518, as described herein. When ready to use the instrument 2500, the clinician may provide a firing signal, for example by depressing a trigger of the instrument 2500. In response to the firing signal, the motor 2504 may drive the displacement member distally along the longitudinal axis of the end effector 2502 from a proximal stroke begin position to a stroke end position distal of the stroke begin position. As the displacement member translates distally, an I-beam 2514 with a cutting element positioned at a distal end, may cut the tissue between the staple cartridge 2518 and the anvil 2516.

[0128] In various examples, the surgical instrument 2500 may comprise a control circuit 2510 programmed to control the distal translation of the displacement member, such as the I-beam 2514, for example, based on one or more tissue conditions. The control circuit 2510 may be programmed to sense tissue conditions, such as thickness, either directly or indirectly, as described herein. The control circuit 2510 may be programmed to select a firing control program based on tissue conditions. A firing control program may describe the distal motion of the displacement member. Different firing control programs may be selected to better treat different tissue conditions. For example, when thicker tissue is present, the control circuit 2510 may be programmed to translate the displacement member at a lower velocity and/or with lower power. When thinner tissue is present, the control circuit 2510 may be programmed to translate the displacement member at a higher velocity and/or with higher power.

[0129] In some examples, the control circuit 2510 may initially operate the motor 2504 in an open-loop configuration for a first open-loop portion of a stroke of the displacement member. Based on a response of the instrument 2500 during the open-loop portion of the stroke, the control circuit 2510 may select a firing control program. The response of the instrument may include, a translation distance of the displacement member during the open-loop portion, a time elapsed during the open-loop portion, energy provided to the motor 2504 during the open-loop portion, a sum of pulse widths of a motor drive signal, etc. After the open-loop portion, the control circuit 2510 may implement the selected firing control program for a second portion of the displacement member stroke. For example, during the closed loop portion of the stroke, the control circuit 2510 may modulate the motor 2504 based on translation data describing a position of the displacement member in a closed-loop manner to translate the displacement member at a constant velocity.

[0130] FIG. 15 illustrates a diagram 2580 plotting two example displacement member strokes executed according to one aspect of this disclosure. The diagram 2580 comprises two axes. A horizontal axis 2584 indicates elapsed time. A vertical axis 2582 indicates the position of the I-beam 2514 between a stroke begin position 2586 and a stroke end position 2588. On the horizontal axis 2584, the control circuit 2510 may receive the firing signal and begin providing the initial motor setting at t₀. The open-loop portion of the displacement member stroke is an initial time period that may elapse between t₀ and t₁.

[0131] A first example 2592 shows a response of the surgical instrument 2500 when thick tissue is positioned between the anvil 2516 and the staple cartridge 2518. During the open-loop portion of the displacement member stroke, e.g., the initial time period between t₀ and t₁, the I-beam 2514 may traverse from the stroke begin position 2586 to position 2594. The control circuit 2510 may determine that position 2594 corresponds to a firing control program that advances the I-beam 2514 at a selected constant velocity (Vslow), indicated by the slope of the example 2592 after t₁ (e.g., in the closed loop portion). The control circuit 2510 may drive I-beam 2514 to the velocity Vslow by monitoring the position of I-beam 2514 and modulating the motor set point 2522 and/or motor drive signal 2524 to maintain Vslow. A second example 2590 shows a response of the surgical instrument 2500 when thin tissue is positioned between the anvil 2516 and the staple cartridge 2518.

[0132] During the initial time period (e.g., the open-loop period) between t₀ and t₁, the I-beam 2514 may traverse from the stroke begin position 2586 to position 2596. The control circuit may determine that position 2596 corresponds to a firing control program that advances the displacement member at a selected constant velocity (Vfast). Because the tissue in example 2590 is thinner than the tissue in example 2592, it may provide less resistance to the motion of the I-beam 2514. As a result, the I-beam 2514 may traverse a larger portion of the stroke during the initial time period. Also, in some examples, thinner tissue (e.g., a larger portion of the displacement member stroke traversed during the initial time period) may correspond to higher displacement member velocities after the initial time period.

[0133] FIG. 16 illustrates a cross-sectional view of an end effector 912 of a surgical instrument according to one aspect of this disclosure. The end effector 912 is one aspect of the end effector 300 (FIGS. 1 and 4) that may be adapted to operate with surgical instrument 10 (FIG. 1) to measure the various derived parameters such as gap distance versus time, tissue compression versus time, and anvil strain versus time. Accordingly, the end effector 912 may include one or more sensors configured to measure one or more parameters or characteristics associated with the end effector 912 and/or a tissue section captured by the end effector 912. The end effector 912 may comprise a first sensor 920 and a second sensor 926. In various examples, the first sensor 920 and/or the second sensor 926 may comprise, for example, a magnetic sensor such as, for example, a magnetic field sensor, a strain gauge, a pressure sensor, a force sensor, an inductive sensor such as, for example, an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor for measuring one or more parameters of the end effector 912. Although the illustrated end effector 912 comprises two sensors, additional or fewer sensors can be employed.

[0134] The first sensor 920 and/or the second sensor 926 may comprise, for example, a magnetic field sensor embedded in an anvil 914 and configured to detect a magnetic field generated by a magnet 924 embedded in a jaw member 916 and/or the staple cartridge 918. The anvil 914 is pivotally rotatable between open and closed positions. The strength of the detected magnetic field may correspond to, for example, the thickness and/or fullness of a bite of tissue located between the anvil 914 and the jaw member 916. In certain instances, the first sensor 920 and/or the second sensor 926 may comprise a strain gauge, such as, for example, a micro-strain gauge, configured to measure the magnitude of the strain in the anvil 914 during a clamped condition. The strain gauge provides an electrical signal whose amplitude varies with the magnitude of the strain.

[0135] In some aspects, one or more sensors of the end effector 912 such as, for example, the first sensor 920 and/or the second sensor 926 may comprise a pressure sensor configured to detect a pressure generated by the presence of compressed tissue between the anvil 914 and the jaw member 916. In some examples, one or more sensors of the end effector 912 such as, for example, the first sensor 920 and/or the second sensor 926 are configured to detect the impedance of a tissue section located between the anvil 914 and the jaw member 916. The detected impedance may be indicative of the thickness and/or fullness of tissue located between the anvil 914 and the jaw member 916.

[0136] The sensors of the end effector 912 such as, for example, the first sensor 920 may be configured to measure the gap 922 between the anvil 914 and the jaw member 916. In certain instances, the gap 922 can be representative of the thickness and/or compressibility of a tissue section clamped between the anvil 914 and the jaw member 916. The gap 922 can be representative of the force applied to the anvil 914 to compress the tissue. In one aspect, the gap 922 between the anvil 914 and the jaw member 916 can be measured by positioning a magnetic field sensor on the anvil 914 and positioning a magnet on the jaw member 916 such that the gap 922 is proportional to the signal detected by the magnetic field sensor and the signal is proportional to the distance between the magnet and the magnetic field sensor. It will be appreciated that the location of the magnetic field sensor and the magnet may be swapped such that the magnetic field sensor is positioned on the jaw member 916 and the magnet is placed on the anvil 914.

[0137] The sensors of the end effector 912 such as, for example, the first sensor 920 may be configured to measure one or more forces exerted on the anvil 914 by the closure drive system 30. For example, the first sensor 920 can be at an interaction point between the closure tube 260 (FIG. 3) and the anvil 914 to detect the closure forces applied by the closure tube 260 to the anvil 914. The forces exerted on the anvil 914 can be representative of the tissue compression experienced by the tissue section captured between the anvil 914 and the jaw member 916. In certain aspects, the first sensor 920 and/or other sensors can be positioned at various interaction points along the closure drive system 30 (FIG. 2) to detect the closure forces applied to the anvil 914 by the closure drive system 30. The first sensor 920 and/or the second sensor 926 may be sampled in real time during a clamping operation by a processor as described in FIGS. 5-10, for example, and more particularly, the system 970. The processor receives real-time sample measurements to provide analyze time based information and assess, in real time, closure forces applied to the anvil 914.

[0138] FIG. 17 is a logic flow diagram depicting a process 4070 of a control program or a logic configuration for controlling the duty cycle of the motor 2504 in accordance with one or more aspects of the present disclosure. In the following description of the process 4070 in FIG. 15, reference should also be made to FIG. 14 and FIG. 15. Accordingly, the control circuit 2510 retrieves 4072 the expected tissue thickness TCe of the tissue that is grasped or is to be grasped upon use of the surgical instrument 2500. The expected tissue thickness TCe can be stored, for example, in a memory of the surgical instrument 2500. The expected tissue thickness TCe can additionally be input or pre-programmed by an operator of the surgical instrument 2500 or can be downloaded, or otherwise received, by the surgical instrument 2500 from an external source prior to use. One such external source can include a staple cartridge 2518 that is configured to store the expected tissue thickness TCe with which the staple cartridge 2518 is intended to be used and then transmit the expected tissue thickness to the control circuit 2510 upon the staple cartridge 2518 being engaged with the surgical instrument 2500.

[0139] The control circuit 2510 then determines 4074 the actual thickness TCa of the tissue grasped by the surgical instrument 2500 at or by the end effector 2502. In various aspects, the actual tissue thickness can be determined 4074 either directly or via one or more proxy measurements carried out by the surgical instrument 2500 prior to or during operation. In one aspect, the surgical instrument 2500 comprises a tissue thickness sensor disposed at the distal end of the end effector 2502. The tissue thickness sensor can comprise a Hall-effect sensor, a reed switch sensor, an optical sensor, a magneto-inductive sensor, a force sensor, a pressure sensor, a piezo-resistive film sensor, an ultrasonic sensor, an eddy current sensor, an accelerometer, a pulse oximetry sensor, a temperature sensor, a sensor configured to detect an electrical characteristic of a tissue path (such as capacitance or resistance), or any combination thereof. The tissue thickness sensor can be configured to measure a thickness of a tissue located between the anvil 2516 and the staple cartridge 2518, a gap or distance between the anvil 2516 and the staple cartridge 2518, a gap or distance between the jaw members of the surgical instrument 2500, and a variety of other parameters indicating the thickness of the grasped tissue.

[0140] In another aspect, the surgical instrument 2500 can alternatively be configured to measure a proxy for the tissue thickness either prior to initiating the firing stroke or during an initial portion of the firing stroke. One such proxy can include the force on a displacement member such as the drive member 120 (FIG. 2); the firing member 220 (FIG. 3), 2520 (FIG. 13); I-beam 2514, 178 (FIG. 4); the firing bar 172 (FIG. 4); and/or on a proximal end of the cutting edge 182 (FIG. 4), 2509 (FIG. 13). For conciseness and clarity, the proxy for the tissue thickness will be described in connection with the force experienced by the I-beam 2514. Accordingly, a proxy for the tissue thickness can be determined by the I-beam 2514 force, which may be determined using various techniques. In one aspect, the I-beam 2514 force may be determined by measuring the motor 2504 current, where motor 2504 current is based on the load experienced by the I-beam 2514 as it advances distally. In another aspect, the I-beam 2514 force may be determined by way of a strain gauge positioned on the displacement member such as the drive member 120 (FIG. 2); the firing member 220 (FIG. 3), 2520 (FIG. 13); I-beam 2514, 178 (FIG. 4); the firing bar 172 (FIG. 4); and/or on a proximal end of the cutting edge 182 (FIG. 4), 2509 (FIG. 13). In yet another aspect, the I-beam 2514 force may be determined by monitoring the actual position of the I-beam 2514 moving at an expected velocity based on motor 2504 set speed after a predetermined elapsed period t₁ and comparing the actual position of the I-beam 2514 relative to the expected position of the I-beam 2514 based on the set velocity of the motor 2504 at time t₁. Thus, if the actual position of the I-beam 2514 is less than the expected position of the I-beam 2514, the I-beam 2514 is experiencing greater than a nominal force. Conversely, if the actual position of the I-beam 2514 is greater than the expected position of the I-beam 2514, the I-beam 2514 force is less than the nominal force. The difference between the actual and expected positions of the I-beam 2514 is proportional to the deviation of the I-beam 2514 force from the nominal force. The latter technique is described in detail in commonly owned attorney docket number END8195USNP filed on same date, which is incorporated herein by reference in its entirety.

[0141] The control circuit 2510 then provides a motor set point 2522 to the motor controller 2508, which provides the motor drive signal 2524 to set 4076 the initial duty cycle of the motor 2504 to a value corresponding to actual tissue thickness relative to the expected tissue thickness. If the actual tissue thickness TCa is greater than the expected tissue thickness TCe, then the initial duty cycle will be set to a lower value than the default duty cycle. The relative degree to which the actual tissue thickness TCa is greater than the expected tissue thickness TCe can additionally affect the value to which the initial duty cycle is set. In some aspects, the thicker the actual tissue thickness TCa is relative to the expected tissue thickness TCe, the lower the initial duty cycle will be set. Therefore, for increasingly thicker tissue, the I-beam 2514 will be initially advanced increasingly slower. If the actual tissue thickness TCa is not greater than the expected tissue thickness TCe, then the initial duty cycle will be set to a default duty cycle. The default duty cycle can be, for example, 100%.

[0142] In one aspect, the process 4070 as executed by the control circuit 2510 is configured to establish one or more discrete zones covering a range of tissue thickness values and then set 4076 the initial duty cycle of the motor 2504 according to which zone the actual tissue thickness TCa falls within. For example, if the expected tissue thickness TCe is 2 mm, then a first zone can include tissue thickness of 0-2 mm, a second zone can include tissue thickness of 2-4 mm, and a third zone can include tissue thickness of greater than 4 mm. In this example, if the actual tissue thickness TCa falls within the first zone, then the motor 2504 duty cycle is set to a default or first duty cycle. If the actual tissue thickness TCa falls within the second zone, then the motor 2504 duty cycle is set to a second duty cycle that is lower than the first duty cycle. Lastly, if the actual tissue thickness TCa falls within the third zone, then the motor 2504 duty cycle is set to a third duty cycle that is lower than the second duty cycle. The zones can be defined in terms of explicit ranges of values, ratios to the expected tissue thickness TCe, or in any other such manner according to various aspects. The number and ranges of such zones can likewise various according to various aspects. In another aspect, the process 4070 as executed by the control circuit 2510 is configured to calculate the initial duty cycle according to the actual tissue thickness TCa, the expected tissue thickness TCe, and the ratio therebetween. In this aspect, the initial duty cycle set by the control circuit 2510 is a unique value according to the inputs, rather than having a set value for a range of inputs.

[0143] Once the initial duty cycle is set 4076, the control circuit 2510 then causes the motor 2504 to initiate 4078 a firing stroke by advancing the displacement member such as, for example, the I-beam 2514 distally. In the example where the displacement member is the I-beam 2514, during the course of the firing stroke, the control circuit 2510 determines 4080 the position of the I-beam 2514 and updates 4082 the duty cycle of the motor 2504 according to the determined 4080 I-beam 2514 position. The position of the I-beam 2514 can be determined 4080 via a number of different techniques. In one aspect, the surgical instrument 2500 can comprise a position sensor 1112 (FIG. 10) that is configured to track the longitudinal displacement of the I-beam 2514, as described above. The duty cycle of the motor 2504 can be updated according to an algorithm executed by the control circuit 2510, a look-up table stored in a memory that is accessed by the control circuit 2510, or any other such technique for retrieving or calculating an updated value according to one or more inputs. In one aspect, the duty cycle of the motor 2504 is updated 4082 such that it increases over the course of the stroke of the I-beam 2514, i.e., the duty cycle directionally corresponds to the magnitude of the linear displacement of the I-beam 2514. The control circuit 2510 next determines 4084 whether the stroke of the I-beam 2514 is completed. If the firing stroke is complete, then the process 4070 proceeds along the YES branch and the process 4070 is completed 4086. If the firing stroke is not complete, then the process 4070 proceeds along the NO branch and continues a loop of determining 4080 the position of the I-beam 2514 and updating 4082 the duty cycle of the motor 2504, as described above. Stated differently, the process 4070 continues to update the duty cycle of the motor 2504 as the position of the I-beam 2514 changes throughout its firing stroke. In one aspect, the process 4070 can additionally be configured to exit the loop of determining 4080 the I-beam 2514 position and updating 4082 the duty cycle if the duty cycle reaches 100% as the duty cycle cannot exceed that value.

[0144] FIG. 18 is a first diagram 4030 plotting three example firing member strokes executed according to the process 4070 of FIG. 17 according to one or more aspects of this disclosure. The first diagram 4030 includes a horizontal axis 4034 representing the displacement or position of the displacement member, e.g., the I-beam 2514, over a stroke between a stroke begin position 4006 and a stroke end position 4008 and a vertical axis 4032 representing the duty cycle of the motor 2504. The stroke end position 4008 depends, in part, upon the type of staple cartridge 2518 utilized by the surgical instrument 2500 as the staple cartridges 2518 can vary in length. In one illustrative aspect, the stroke end position 4008 is 60 mm from a stroke begin position 4006 of 0 mm.

[0145] A first example 4022 shows a response of the surgical instrument 2500 when the tissue grasped by the end effector 2502 is not greater than the expected thickness TCe. When the actual tissue thickness TCa is not greater than the expected tissue thickness TCe, then the motor 2504 drives the I-beam 2514 from the stroke begin position 4006 to the stroke end position 4008 at the default duty cycle DC₀ over time t₁. In the illustrated aspect, the default duty cycle DC₀ is equal to 100%. It should be noted that in alternative aspects, the default duty cycle DC₀ can be less than 100%. As the duty cycle DC₀ is 100% throughout the stroke of the I-beam 2514 in the first example 4022, there are no periods in which the motor 2504 is inactive; thus, there are no pauses in the first example 4022 from the stroke begin position 4006 to the stroke end position 4008, as there are in the second example 4024 and the third example 4026.

[0146] A second example 4024 shows a response of the surgical instrument 2500 when the tissue grasped by the end effector 2502 is greater than the expected thickness TCe. When the actual tissue thickness TCa is greater than the expected tissue thickness TCe, the control circuit 2510 causes the motor control 2508 to drive the motor 2504 at an initial duty cycle DC₃ that is less than the default duty cycle DC₀. The initial duty cycle can be a function of the degree to which the actual thickness TCa is greater than the expected thickness TCe. When the motor control 2508 drives the motor 2504 at a duty cycle that is less than 100%, the I-beam 2514 translates at a comparatively lower velocity. After the initial duty cycle is set and the I-beam 2514 begins its stroke, the control circuit 2510 updates or adjusts the duty cycle at which the motor control 2508 drives the motor 2504 over the course of the I-beam 2514 stroke. In one aspect, the control circuit 2510 is configured to increase the motor 2504 duty cycle over the course of the stroke. In the case of the second example 4024, the control circuit 2510 causes the duty cycle of the motor 2504 to increase from the initial value DC₃ to an ending value DC₁, as illustrated in the first diagram 4030. As the velocity of the I-beam 2514 corresponds to the duty cycle of the motor 2504, the velocity of the I-beam 2514 accordingly increases over the course of the firing stroke.

[0147] As with the second example 4024, the third example 4026 shows a response of the surgical instrument 2500 when the tissue grasped by the end effector 2502 is greater than the expected thickness TCe. The difference in the third example 4026 being that the actual thickness TCa of the grasped tissue is greater relative to the expected thickness TCe than in the second example 4024. In other words, the tissue is even thicker in the third example 4026 than the second example 4024. As the initial duty cycle is a function of the degree to which the actual thickness TCa is greater than the expected thickness TCe and the tissue in third example 4026 is thicker than in the second example 4024, the control circuit 2510 therefore causes the motor control 2508 to drive the motor 2504 at an initial duty cycle DC₄ that is less than the initial duty cycle DC₃ of the second example 4024.

[0148] Because the average motor 2504 duty cycles are lower over the course of the firing strokes of the second example 2024 and the third example 2026 as compared to the first example 4022, the average velocities of the I-beam 2514 over the firing strokes in the second example 4024 and the third example 4026 are likewise comparatively lower. It can be desirable to translate the I-beam 2514 at a reduced velocity when the actual thickness TCa of the tissue is greater than the expected thickness TCe to ensure proper staple formation in the tissue. Furthermore, translating the I-beam 2514 at a lower velocity can provide time for fluid in the tissue that is being cut and/or stapled to escape away from the surgical site and for the tissue itself to elastically respond to the clamping, stapling, and/or cutting operations, both of which can improve the performance of the surgical instrument 2500 and the quality of the staple formation. Additionally, it can be desirable to increase the duty cycle of the motor 2504 over the course of the stroke of the I-beam 2514 because the resistance encountered from clamped tissue decreases as the tissue is cut and/or staples are formed in the tissue by the I-beam 2514. As resistance from the tissue decreases, the I-beam 2514 can be translated at a correspondingly increased velocity without negatively impacting staple formation.

[0149] It should be noted that the various duty cycle values depicted in FIG. 18 are intended solely for illustrative purposes and no relationship between the values beyond that which is described herein should be implied. For example, although the ending duty cycle of the third example 4026 DC₂ is depicted as greater than the initial duty cycle of the second example 4024 DC₃, no such specific relationship is intended or implied. As another example, although the ending values DC₁ and DC₂ of the first example 4022 and the second example 4024, respectively, are depicted as less than the default duty cycle DC₀, it is not intended to be implied that in any situation wherein the actual tissue thickness is greater than the expected tissue thickness that the duty cycle of the motor 2504 will never reach the default duty cycle DC₀ over the course of the firing stroke. Furthermore, although the relationship between the firing stroke displacement and the motor duty cycle is depicted as roughly exponential in FIG. 20, their relationship can alternatively be linear or described via any other type of mathematical function.

[0150] FIG. 19 is a logic flow diagram depicting a process 4200 of a control program or a logic configuration for controlling the displacement of the displacement member according to one or more aspects of this disclosure. In the following description of the process 4200 in FIG. 15, reference should also be made to FIG. 14 and FIG. 15. Accordingly, the control circuit 2510 initiates 4202 the stroke of the displacement member. As discussed above, the displacement member can include the drive member 120 (FIG. 2); the firing member 220 (FIG. 3), 2520 (FIG. 13); I-beam 2514, 178 (FIG. 4); the firing bar 172 (FIG. 4); and/or on a proximal end of the cutting edge 182 (FIG. 4), 2509 (FIG. 13). For conciseness and clarity, the displacement member in the process 4200 will primarily be discussed in terms of the I-beam 2514. In one aspect, the initial velocity or duty cycle at which the motor 2504 is set can vary according to the detected tissue thickness or another such tissue parameter, as discussed above with respect to the process 4070 (FIG. 17). In another aspect, the initial velocity or duty cycle at which the motor 2504 is set upon initiation 4202 of the displacement member stroke can be a fixed or default value.

[0151] After the displacement member stroke is initiated 4202, the control circuit 2510 monitors the I-beam 2514 force through the firing stroke and determines 4204 whether the force is greater than or equal to a threshold force. As discussed above, the I-beam 2514 force can be determined in several different ways in different aspects. In one aspect, the I-beam 2514 force can be determined by measuring the motor 2504 current, where motor 2504 current is based on the load experienced by the I-beam 2514 as it advances distally. In another aspect, the I-beam 2514 force can be determined by way of a strain gauge positioned on one or more components of the firing drive system. In yet another aspect, the I-beam 2514 force may be determined by monitoring the actual position of the I-beam 2514 compared to an expected position. In this aspect, when the actual position of the I-beam 2514 is less than the expected position, then the I-beam 2514 is experiencing a greater than expected force.

[0152] The threshold force can be, for example, a fixed value stored in a memory of the surgical instrument 2500. The threshold force can additionally be input or pre-programmed by an operator of the surgical instrument 2500 or can be downloaded, or otherwise received, by the surgical instrument 2500 from an external source prior to use.

[0153] If the control circuit 2510 determines 4204 that the I-beam 2514 force exceeds a threshold force, then the process 4200 proceeds down the YES branch and the control circuit 2510 pauses 4206 the I-beam 2514 for a length of time. In one aspect, the control circuit 2510 pauses 4206 the I-beam 2514 by deactivating the motor 2504. The length of time for which the I-beam 2514 is paused 4206 can be fixed or variable. In one aspect, the pause length is a fixed value that is stored in a memory of the surgical instrument 2500, input or pre-programmed by an operator of the surgical instrument 2500, or received by the surgical instrument 2500 from an external source prior to use. In another aspect, the pause length can vary according to a position of the I-beam 2514. For example, the pause length can decrease as a function of the I-beam 2514 position from the begin position 4006 to the end position 4008 of the firing stroke. In another aspect, the pause length can vary according to one or more parameters or characteristics associated with the end effector 912 and/or a tissue section captured by the end effector 2502 as measured, for example, by the sensors 920, 926 (FIG. 16) at the end effector 2502. For example, the pause length can increase as a function of the thickness of the tissue detected by the sensors 920, 926. In yet other aspects, the pause length can vary according to a combination of multiple variables.

[0154] The control circuit 2510 next determines 4208 whether the stroke of the I-beam 2514 is completed. If the firing stroke is complete, then the process 4070 proceeds along the YES branch and the process 4200 is completed 4210. If the firing stroke is not complete, then the process 4200 proceeds along the NO branch and continues a loop of determining 4204 whether I-beam 2514 force exceeds a threshold force and pausing 4206 the translation of the I-beam 2514 accordingly, as described above. Stated differently, the process 4200 continues to monitor the I-beam 2514 force throughout its firing stroke. If the control circuit 2510 determined 4204 that the I-beam 2514 force was less than a threshold force, then the process 4200 proceeds down the NO branch, which skips the pausing 4206 the translation of the I-beam 2514 and proceeds directly to determining 4208 whether the stroke of the I-beam 2514 is completed, which then proceeds as described above.

[0155] FIG. 20 is a second diagram 4300 plotting three examples of I-beam 2514 firing stroke displacement executed according to the process 4200 of FIG. 19 in accordance with one or mare aspects of the present disclosure. For clarity, a third diagram 4400 in FIG. 21 further includes a waveform of the motor activation status 4402 of each of the three examples in FIG. 20. The second diagram 4300 includes a horizontal axis 4002 representing elapsed time and a vertical axis 4004 representing the displacement or position of the I-beam 2514 over a stroke between a stroke begin position 4006 and a stroke end position 4008. When the motor 2504 is activated 4404, the control circuit 2510 can be causing the motor control 2508 to apply a voltage or current to the motor 2504. When the motor 2504 is deactivated 4406, the control circuit 2510 can be causing the motor control 2508 to not apply a voltage or current to the motor 2504.

[0156] A first example 4302 shows a response of the surgical instrument 2500 when the I-beam 2514 force does not exceed a threshold force for the entire length of the firing stroke of the I-beam 2514. Accordingly, the process 4200 executed by the control circuit 2510 does not pause the I-beam 2514 at any point and thus the motor 2504 driving the I-beam 2514 is activated 4404 during the entire length of the firing stroke, which ends at time t₁.

[0157] A second example 4304 shows a response of the surgical instrument 2500 when the I-beam 2514 force exceeds a threshold force at various points. This can be visualized by the fact that the initial slope 4322 of the second example 4304 is smaller than the slope 4320 of the first example 4302. In other words, the I-beam 2514 is advancing at a lower velocity in the second example 4304 than the first example 4302. When all other factors are held constant, when the I-beam 2514 is advancing at a lower than expected velocity, the I-beam 2514 can be correspondingly experiencing a larger than expected force. Accordingly, the process 4200 executed by the control circuit 2510 pauses the I-beam 2514 when the I-beam 2514 force exceeds a threshold. The motor 2504 thus alternates between periods of activation 4404 and deactivation 4406, separated by a first pause p₁ and a second pause p₂. Note that the periods of motor activation 4404 correspond to translation of the I-beam 2514 and the periods of motor deactivation 4406 correspond to the I-beam 2514 not translating, i.e., pausing. The second example 4304 illustrates an aspect wherein the length of the pauses is a function of the displacement position of the I-beam 2514. Specifically, the lengths of the pauses decrease as the I-beam 2514 translates from the first or begin position 4006 to the second or end position 4008 of the firing stroke such that p₂<p₁. The introduction of the pauses to the firing stroke decreases the average velocity of the I-beam 2514 over the course of the firing stroke, causing the firing stroke to end at time t₂, which is larger than t₁.

[0158] A third example 4306 likewise shows a response of the surgical instrument 2500 when the I-beam 2514 force exceeds a threshold force at various points. Accordingly, the process 4200 executed by the control circuit 2510 pauses the I-beam 2514 and the motor 2504 thus alternates between periods of activation 4404 and deactivation 4406, separated by a first pause p_1′, a second pause p_2′, and a third pause p_3′. The third example 4306 represents a situation wherein the I-beam 2514 force exceeds the threshold force to a greater degree than in the second example 4304. This can be visualized by the fact that the initial slope 4324 of the third example 4306 is smaller than the corresponding initial slope 4322 of the second example 4304. Therefore, the I-beam 2514 is advancing at a lower velocity in the third example 4306 than the second example 4304, which can be indicative of the thickness of the tissue being cut by the I-beam 2514 being greater in the third example 4306. The third example 4306 illustrates an aspect wherein the length of the pauses is a function of both the tissue thickness and the displacement position of the I-beam 2514. Specifically, the number of pauses increases and the pause length increases as the tissue thickness increases, such that p_1′>p₁. Furthermore, the pause length decreases as the I-beam 2514 translates from the first or begin position 4006 to the second or end position 4008 of the firing stroke such that p_3′<p_2′<p_1′. The introduction of the pauses to the firing stroke decreases the average velocity of the I-beam 2514 over the course of the firing stroke, causing the firing stroke to end at time t₃, which is larger than t₁. As the lengths of the pauses are larger and the pauses are more numerous than in the second example 4304, t₃ is likewise larger than t₂.

[0159] The functions or processes 4070, 4200 described herein may be executed by any of the processing circuits described herein, such as the control circuit 700 described in with FIGS. 5-6, the circuits 800, 810, 820 described in FIGS. 7-9, the microcontroller 1104 described in with FIGS. 10 and 12, and/or the control circuit 2510 described in FIG. 14.

[0160] The functions or processes 4070, 4200 described herein may be executed by any of the processing circuits described herein, such as the control circuit 700 described in with FIGS. 5-6, the circuits 800, 810, 820 described in FIGS. 7-9, the microcontroller 1104 described in with FIGS. 10 and 12, and/or the control circuit 2510 described in FIG. 14.

[0161] Aspects of the motorized surgical instrument may be practiced without the specific details disclosed herein. Some aspects have been shown as block diagrams rather than detail. Parts of this disclosure may be presented in terms of instructions that operate on data stored in a computer memory. An algorithm refers to a self-consistent sequence of steps leading to a desired result, where a “step” refers to a manipulation of physical quantities which may take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. These signals may be referred to as bits, values, elements, symbols, characters, terms, numbers. These and similar terms may be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities.

[0162] Generally, aspects described herein which can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or any combination thereof can be viewed as being composed of various types of “electrical circuitry.” Consequently, “electrical circuitry” includes electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer or processor configured by a computer program which at least partially carries out processes and/or devices described herein, electrical circuitry forming a memory device (e.g., forms of random access memory), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, or optical-electrical equipment). These aspects may be implemented in analog or digital form, or combinations thereof.

[0163] The foregoing description has set forth aspects of devices and/or processes via the use of block diagrams, flowcharts, and/or examples, which may contain one or more functions and/or operation. Each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one aspect, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), Programmable Logic Devices (PLDs), circuits, registers and/or software components, e.g., programs, subroutines, logic and/or combinations of hardware and software components. logic gates, or other integrated formats. Some aspects disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure.

[0164] The mechanisms of the disclosed subject matter are capable of being distributed as a program product in a variety of forms, and that an illustrative aspect of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.).

[0165] The foregoing description of these aspects has been presented for purposes of illustration and description. It is not intended to be exhaustive or limiting to the precise form disclosed. Modifications or variations are possible in light of the above teachings. These aspects were chosen and described in order to illustrate principles and practical application to thereby enable one of ordinary skill in the art to utilize the aspects and with modifications as are suited to the particular use contemplated. It is intended that the claims submitted herewith define the overall scope.

[0166] Various aspects of the subject matter described herein are set out in the following numbered examples:

[0167] Example 1. A surgical instrument comprising: a displacement member configured to translate within the surgical instrument; a motor coupled to the displacement member to translate the displacement member; a sensor configured to sense a thickness of a tissue grasped by an end effector; and a control circuit coupled to the motor and the sensor, the control circuit configured to: retrieve an expected thickness of the tissue; determine the thickness of the tissue via the sensor; and set a duty cycle for driving the motor, wherein the duty cycle corresponds to the thickness of the tissue relative to the expected thickness of the tissue.

[0168] Example 2. The surgical instrument of Example 1, wherein the control circuit is configured to update the duty cycle based on a position of the displacement member.

[0169] Example 3. The surgical instrument of Example 1 through Example 2, wherein the control circuit is configured to increase the duty cycle as the displacement member is translated.

[0170] Example 4. The surgical instrument of Example 1 through Example 3, wherein the control circuit is configured to set the duty cycle to a default duty cycle when the thickness of the tissue is less than or equal to the expected thickness of the tissue.

[0171] Example 5. The surgical instrument of Example 4, wherein the control circuit is configured to set the default duty cycle to 100%.

[0172] Example 6. The surgical instrument of Example 1 through Example 5, wherein the control circuit is configured to retrieve the expected thickness of the tissue is retrieved from a memory.

[0173] Example 7. A surgical instrument comprising: a displacement member configured to translate within the surgical instrument; a motor coupled to the displacement member to translate the displacement member; and a control circuit coupled to the motor, the control circuit configured to: determine a force on the displacement member; and pause the motor according to whether the force is greater than a threshold force.

[0174] Example 8. The surgical instrument of Example 7, wherein the control circuit is configured to pause the motor for a fixed length of time.

[0175] Example 9. The surgical instrument of Example 7 through Example 8, wherein the control circuit is configured to pause the motor for a variable length of time.

[0176] Example 10. The surgical instrument of Example 9, wherein the variable length of time corresponds to a position of the displacement member.

[0177] Example 11. The surgical instrument of Example 9 through Example 10, wherein the variable length of time corresponds to the force compared to the threshold force.

[0178] Example 12. The surgical instrument of Example 9 through Example 11, further comprising: a sensor configured to detect a tissue parameter, the sensor operably coupled to the control circuit; wherein the variable length of time corresponds to the tissue parameter.

[0179] Example 13. The surgical instrument of Example 12, wherein the sensor comprises a tissue thickness sensor.

[0180] Example 14. The surgical instrument of Example 7 through Example 13, wherein the control circuit determines the force on the displacement member according to a current drawn by the motor.

[0181] Example 15. A method of controlling a motor in a surgical instrument, the surgical instrument comprising a displacement member configured to translate within the surgical instrument, a motor coupled to the displacement member to translate the displacement member, a sensor configured to sense a thickness of a tissue grasped by an end effector, and a control circuit coupled to the motor, the method comprising: retrieving, by the control circuit, an expected thickness of the tissue; determining, by the control circuit, the thickness of the tissue via the sensor; and setting, by the control circuit, a duty cycle for driving the motor, wherein the duty cycle corresponds to the thickness of the tissue relative to the expected thickness of the tissue.

[0182] Example 16. The method of Example 15, further comprising updating, by the control circuit, the duty cycle based a position of the displacement member.

[0183] Example 17. The method of Example 15 through Example 16, further comprising setting, by the control circuit, the duty cycle to a default duty cycle when the thickness of the tissue is less than or equal to the expected thickness of the tissue.

[0184] Example 18. The method of Example 17, further comprising setting, by the control circuit, the default duty cycle to 100%.

[0185] Example 19. The method of Example 15 through Example 18, further comprising retrieving, by the control circuit, the expected thickness of the tissue from a memory.

[0186] Example 20. The method of Example 15 through Example 19, further comprising detecting, by the control circuit, a position of the displacement member by another sensor.