Control system and teach pendant for an industrial robot

[0001] This application claims priority to European patent application 05027996.7 filed 21 Dec. 2005.

[0002] The invention relates to a control system for an industrial robot of the kind comprising a portable robot controller or teach pendant for manually controlling movement of a robot or manipulator arm. In particular the invention relates to an live handle switch or enabling device for safe use of a robot or other machine under manual control.

[0003] Manually controlled movement of a robot arm is used especially during a programming stage in order to teach the robot to follow an operating path defined by a number of set points. A memory means in the control system may store the coordinates of said set points as position instructions and other operating instructions which, together with said set points, may define a work cycle of the robot and means arranged, during automatic running of the robot, to control the robot in accordance with information stored in the memory means during the programming stage.

[0004] In a control system for an industrial robot, the robot during programming is often run with the aid of a first control means which can be manually influenced, a means such as a joystick. The joystick is often comprised in a portable control unit also called a Teach Pendant Unit or TPU. The robot or end effector of the robot is successively moved to each of said set points or waypoints which define the movement path or the operating positions that the robot is to follow or assume during automatic operation. These positions may be stored in the form of a sequence of position instructions in a program memory, i.e. the memory means, present in the robot, or in a control unit. In addition to the pure position instructions, other operating instructions are stored in the program memory giving further information about the working cycle of the robot. For example the operating instructions may give information about the desired robot velocity in a certain section of the movement, about control of outputs from the robot to external equipment, about a desired precision of the robot movement, about conditions for the robot movement in dependence on input signals from external sensors or equipments, about events such as switch on/off paint spray, about calls for pre-programmed subroutines, and so on. During automatic operation of the robot, the program instructions are run through successively, and the robot is displaced successively between the different programmed positions in accordance with the position instructions and further carries out the measures which are programmed into the instructions.

[0005] U.S. Pat. No. 4,888,708 to Brantmark entitled Control system for an industrial robot describes a portable unit or teach pendant unit for manual control of the robot during programming for teaching the robot to follow a trajectory or working path defined by a number of set points. The TPU described comprises a joystick arranged for controlling the movement of the robot as well as other control means with a plurality of other control functions.

[0006] A control unit or TPU for use with robot must include a safety switch of the type known as a dead man's handle or also known as a live handle switch. This device requires the operator to hold a switch in a run position such that if the operator lets go of the switch, the machine stops. A live handle switch of a TPU may comprise a certified safety switch type as described in U.S. Pat. No. 5,444,203 to Gunnarsson assigned to ABB entitled Safety Switch for an Industrial Machine. The above specification describes a three position safety switch, which is operable from a first end position via an operating position to a second end position, the safety circuit being closed (made) only in the operating position.

[0007] The present invention aims to provide an improved safety switch for a control system for an industrial robot of the kind mentioned above.

[0008] According to an embodiment of the present invention an improved live handle switch is provided arranged to control robot movement so as to stop movement in the event that the operator does not hold the live handle switch in a run position. In another embodiment the live handle switch is arranged connected to a first and a second safety switch operating means arranged such that the robot may be moved if one safety switch operating means only is held in the a run position, and such that robot movement stops if neither safety switch operating means is held in the run position. In another embodiment the live handle switch is arranged connected to a first and a second safety switch operating means arranged such that the robot may not be moved if any one of two safety switch operating means urged or held in a panic stop position.

[0009] According to another aspect of an embodiment of the present invention there is provided a portable robot control wherein the controller or TPU comprises an improved live handle switch according to an embodiment of the invention and complying with an industrial safety standard arranged to control robot movement so as to stop movement in the event that the operator does not hold the live handle switch in a run position. In another embodiment the live handle switch is arranged connected to a first and a second safety switch operating means arranged such that the robot may be moved if one safety switch operating means only is held in the a run position, and such that robot movement stops if neither safety switch operating means is held in the run position.

[0010] According to another embodiment of the present invention there is provided an improved portable robot control unit wherein the controller or TPU comprises at least two areas for holding or gripping the TPU panel, at least two of which arranged on opposite sides of the TPU, such that the one first joystick is arranged within reach of a one first hand and operable using the thumb of the one first hand and the second joystick arranged within reach of the second or other hand and operable using the thumb of the second other hand whilst holding the TPU with the second hand.

[0011] In another embodiment the improved robot controller is arranged configurable or programmable wherein the switch means operable by an up or down movement of the joystick may be arranged configured to switch on or off equipment arranged around the robot including any from the list of: colour changer device, air supply, an actuator, a tool, a tool-changer, a turntable or a jig.

[0012] According to another aspect of the present invention there is provided one or more methods for moving or controlling a robot or manipulator arm using a robot controller or teach pendant comprising an improved live handle switch according to an embodiment of the present invention, a first joystick moving or controlling a movement of a robot or manipulator arm in a first (x) and/or second (y) axis, and a second joystick moving or controlling a movement of the robot or manipulator arm in a third or z direction.

[0013] According to another embodiment of the present invention there is provided one or more methods for moving or controlling a robot or manipulator arm using a robot controller or teach pendant by holding or urging an operating handle of at least one an improved live handle switch operating means so that it is held in a run position to move or control the robot by the operator.

[0014] According to another embodiment of the present invention there is provided a system for moving or controlling a robot or manipulator arm using one or more robot controllers or teach pendants further comprising a said robot controller, a robot control unit arranged for control of at least one a robot or manipulator and wherein movement of the robot arm may be controlled by a TPU comprising an improved live handle switch according to an embodiment of the invention comprising two operating handles arranged to operate a single set of safety certified switches.

[0015] A very significant advantage of the improved robot controller according to an embodiment of the invention is provided by comprising a safety means arranged to permit an operator to operate the robot controller using one hand only. This is also a feature that provides opportunities to reduce operator fatigue. The embodiment also permits a changeover of operation from one hand to the other hand such that control of the robot does not have to be interrupted. This is because the safety arrangement provides two live handle switch operating means, one being located within reach of the left hand and the other one within reach of the right hand. The operator can hold one first live handle switch operating means in one hand, grip the second live handle switch operating means with the other hand, and then let go of the first live handle switch operating means, and control the robot with the second means. By doing so the operator can change hands or take away either hand from the TPU without interrupting control. The above new features of improved TPU offer considerably improved ease-of-use for an operator and also contributes to significant reductions in operator fatigue.

[0016] A further advantage of the improved live handle switch is that it provides for two handed operation and yet still retains the robust logic of a single-handed safety switch. A more obvious two-handed solution using two sets of safety switches, one set of switches per handle, connected in series or in parallel, would require more complex circuitry or mechanisms to avoid the undesirable alternative conditions such a configuration would cause. Conditions such as with two series-connected safety switches requiring that both handles to be enabled at the same time in order to operate; or condition in the case of two parallel-connected safety switches of having to release both handles in order to stop the machine.

[0017] Another advantage of the improved live handle switch according to an embodiment of the invention is that the established logical operations of an existing double set of certified safety switches can be used as they are now. New certification is not necessary. For example there may also be a built-in feature that will disable re-connection after panic break until the switches have been fully released. Another advantage of the improved live handle switch is that it is robust and simple compared to a possible solution based on more than one set of switches arranged in parallel, which would introduce a number of new logical (connection) case combinations to be resolved.

[0018] A robot controller comprising an improved live handle switch according to an embodiment of the invention proposes a new way for safely operating a robot under manual control. The effort required to program a robot is reduced because the movement control task may be shared between two hands as required.

[0019] In addition the improved live handle switch may be incorporated in other devices for controlling machines while under manual control. Providing safety switch devices with improved ease of use means a wider range of control and programming or configuration options is available.

[0026] FIG. 1 shows an improved live handle switch with two actuating handles according to an embodiment of the invention. It shows the live handle switch 1 and an enclosing housing. Two safe switches 4a, 4b are arranged beside each other in the switch mechanism and connected in parallel. Each switch includes a movable part 9a, 9b, which parts when urged into the switch, in the direction R from left to right in the diagram, then actuate or switch each of the two switches more or less simultaneously. Safe switches 4a, 4b are arranged mounted on a first moveable member 2. A second movable member 5 is arranged relative first member 2 so that either member may be urged and moved in the left or right direction independently of the other.

[0027] FIG. 2 is a view of the underside of the live handle switch. It shows the first member 2 with a view of the safe switches 4 arranged on it. The second member 5 is shown arranged relative to first member 2.

[0028] Referring again to FIG. 1, the first member 2 may be urged in the left direction L by an operator pressing on an actuating handle 6L. Similarly, the second movable member 5 may be urged to the right hand side direction R by an operator pressing on an actuating handle 6R in a direction to the right. When actuating handle 6R and thus second member 5 are urged to the right the actuating “button” 9a, 9b of the two safe switches 4a, 4b are urged to the right and the switch is actuated (see also additional details on typical switching sequences below). The identical result is produced when an operator urges the left actuating handle 6L to the left. When handle 6L and first member 2 are urged to the left, the switches mounted on first member 2 are urged from right to left against second member 5, and the switches are thus actuated.

[0029] FIG. 3a-3e illustrates the operating positions that are typically available. These may be summarised as:

[0030] 3a: Relaxed state O, no connection

[0031] 3b: Left-side operation, L_O switches are engaged to provide connection

[0032] 3c: Left-side panic position L_P, full extent left and connection broken.

[0033] 3d: Right-side operation R_O, switches are engaged to provide connection,

[0034] 3e: Right-side panic position R_P, full extent right and connection is broken.

[0035] In the improved live handle one set of certified double live handle switches is operated using double mechanical live handles. The operator grip can be shifted from one hand to the other without breaking the circuit, but both sides cannot be operated simultaneously. As shown and described, this is effectively and efficiently accomplished by attaching the double set of switches to one of the actuators so they are located in between the two moveable members, one from each left and right live handle part.

[0036] In another embodiment of the improved TPU a live handle switch is comprised in a robot control unit or Teach Pendant Unit, TPU. The live handle switch may comprise a certified safety switch type as described in U.S. Pat. No. 5,444,203 to Gunnarsson assigned to ABB entitled Safety Switch for an Industrial Machine. The above specification describes a three position safety switch, which specification is hereby incorporated in this description in full by means of this reference. The safety switch is operable from a first end position via an operating position to a second end position, the safety circuit being closed (made) only in the operating position. During the return movement from second position to the first end position, the contact device is not affected, and the safety circuit thus remains open during the whole of this return movement.

[0037] FIG. 5 shows a view in 3D of a TPU comprising an improved live handle switch according to an embodiment of the invention. This TPU also comprises two joysticks 22_L, 22_R

[0038] The TPU shown has on the upper side a display screen 20 and an emergency stop button ES. It is arranged to be held using one or both handgrips, H_R and/or H_L.

[0039] FIG. 4 shows a schematic view from below of a TPU comprising an improved live handle switch according to an embodiment of the invention. The figure shows a TPU in the form of a panel 15 or console. An emergency stop button ES is arranged as a push button on a part of the panel.

[0040] The TPU is also shown formed with a handgrip pattern on two sides. The handgrip patterns on the TPU are advantageous to make it more comfortable for the operator to grip and hold the TPU. An operator normally holds the TPU that is shown in FIG. 4 by holding the left handgrip H_L in the left hand and right handgrip H_R in the right hand.

[0041] The panel is preferably further arranged on the top side with a display 20 of some sort and one or more switch means (not shown). The switch means may be arranged as single pushbuttons or groups of pushbuttons. The functions of the pushbuttons are controlled by the robot control system and may be presented in plain text on the display. Generally each pushbutton when activated displays to the operator information about what measures are permitted at each moment.

[0042] One or two control means 22_L, 22_R, preferably a joystick, is/are mounted on the top side with its vertical axis perpendicular to the panel. It may be moved or manually influenced in a direction that may be represented as a movement with two degrees of freedom. The second control means may, if it also is a joystick, also be moved or manually influenced in a direction that may be representing a movement with up to two degrees of freedom. For example one direction may be configured to control or move the robot in a vertical or Z axis direction, even though in real time the operator also moves the second joystick generally in an x or y direction. On the underside of the panel are arranged two recesses 21_L and 21_R. Two handles, 6_L, 6_R which actuate the live handle switch inside the enclosing panel or console are arranged in the recesses. At least one of the live handle switch operating means handles 6_L, 6_R arranged to operate the safety switch may be regarded as a form of enabling device within the context of robot control, and portable robot control units in particular.

[0043] The operator may hold the TPU in, say, the left hand about handgrip H_L and at the same time press the safety switch operating handle 6_L substantially in the direction indicated L with fingers of the same hand, so holding the live handle in the run position, and capable of moving further left to the panic position. At the same time, the operator may also operate a joystick 22_L on the top of the panel by using the left thumb. At the same time with the TPU held and operated in the left hand, the right hand may be free, the right hand may hold the TPU, or the right hand may hold the TPU and operate one or more buttons or controls such as a right joystick 22_R. The operator can also hold the TPU in the right hand and then remove the left hand as soon as the fingers of the right hand have pressed the safety switch operating means 6_R, for example in the right direction R. That is to say that so long as one of the safety switch operating means 6_L or 6_R is held in a connection position L_O or R_O by the operator the robot can be moved. The great advantage of the improved TPU is that the operator can operate the TPU with one hand, hold the TPU in one hand and then change it to the other hand without stopping movement control of the robot.

[0044] The TPU comprising an improved live handle switch may be used to program and control an industrial robot or manipulator arm to carry out one or more of many tasks, including any task from the list of: gripping an object, manipulating an object, stacking, pick and place objects, controlling and operating an amusement ride or an installation comprising a human passenger, welding, framing a vehicle body, riveting, de-burring, fettling, grinding, coating, painting, applying sealant, applying glue, dry spraying, gluing, folding plate, bending plate, hemming plate.

[0045] In this description two opposing movements, urging to the left and/or urging to the right have been described. Plainly mechanical handles may be arranged to be urged in opposite directions to one another along another axis, one up and one down for example. In another embodiment of the invention the safety switch operating means 6_L or 6_R may be urged in another direction than L or R in order to enable use of the TPU.

[0046] In another embodiment an improved live handle switch may be arranged to operate a safety device used for operations with machines and especially robots. Robots and other machinery in an enclosed working area or cell may be arranged with safety switches to prevent machinery from operating if, for example, a gate of the cell is open. For an operator or technician to inspect equipment in a working area while machinery is under manual control the person may carry a personal safety switch comprising an improved live handle according to any embodiment. The operator can thus hold a switch by one of two mechanical actuating handles and subsequently change control over and use the other hand as required, thus reducing fatigue and improving flexibility.

[0047] It should be noted that while the above describes exemplifying embodiments of the invention, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention as defined in the appended claims.