Sports implement testing methods and apparatus

[0002] This application is a continuation-in-part of U.S. patent application Ser. No. 08/761,707, filed Dec. 6, 1996 which is now U.S. Pat. No. 5,988,861, which claims priority of U.S. provisional application Ser. No. 60/008,285, filed Dec. 6, 1995, and Ser. No. 60/030,403, filed Oct. 21, 1996, the entire contents of each of which are incorporated herein by reference.

[0003] The present invention relates generally to sports equipment testing and, more particularly, to a system and methods for testing the performance of a striking implement such as a baseball bat or racket in conjunction with a ball or other associated projectile.

[0004] There is an outstanding need in professional sports to quantify the performance of the equipment involved, and to provide tools to evaluate the performance of existing devices. At the present time, for example, the evaluation of bats, balls, and so forth, is almost completely dependent on the experience and observations of the players who use such equipment. These observations are supported only by an empirically derived historical database of performance statistics. Other than radar guns to measure ball velocity and video cameras for player viewing, there are no quantitative measures of ball movement (s), bat performance, etc. The need remains, therefore, for an analysis and testing system which may be used to monitor the swing of a striking type sports implement such as a bat as it strikes a ball, and to gather information as to swing speed, projectile delivery, and exit velocity. Such information may be used to create performance databases for a variety of analytical and/or statistical evaluations. When used as an input into implement manufacturing, the results obtained from the system may also be used to maximize player safety, for example, by ensuring that exit velocity does not exceed a predetermined threshold.

[0005] The present invention provides methods and apparatus for testing striking-type sports implements. Although many of the descriptions contained herein relate to baseball batting, the system is equally applicable to sports which use rackets or mallets and projectiles other than round balls. Thus, the invention may be used to test and evaluate equipment associated with softball, tennis, squash, badminton, and other sports.

[0006] Broadly, a testing process according to the invention comprises the steps of mechanically swinging the striking implement along a predetermined swing path while delivering the ball or other appropriate projectile along a predetermined delivery path and into the swing path such that it is struck and enters a flight path. As this occurs, one or more of the following are measured: the swing speed of the implement, the delivery speed of the projectile and the exit velocity of the projectile. Preferably the swing speed of the implement and the delivery speed of the projectile are measured near a point proximate to the point of striking contact, whereas exit velocity is preferably measured at a plurality of points along the flight path, not only to determine speed, but also to determine and use angular displacement along the trajectory for a more accurate reading. Based upon these measurements, a programmed computer is used to develop, compile and/or display performance characteristics, such as the ability of different implements to produce a given exit velocity as a function of projectile type, delivery speed, swing speed, and so forth.

[0007] With specific regard to baseball, a hardware embodiment of a batting machine according to the invention includes a bat-swinging module, a ball-delivery module, and one or more programmed computers. Preferably, a main computer is used for data acquisition and analysis purposes as discussed above, with a second computer being dedicated to bat-swing and ball-delivery module control, thereby off-loading the main computer of tasks associated with bat and ball timing, speed and contact-point coordination.

[0008] A bat-swinging module according to the invention includes means to grip a bat at its handle end, and an electromotive source to swing the bat. A ball-delivery module may include a ball support and a different electromotive source operative to place the ball into the swing of the bat along a delivery path, enabling the bat to strike the ball and cause the ball to travel along a trajectory path. The electromotive sources are preferably implemented as computer-controlled servo motors, with the second computer being used to develop and deliver appropriate control signals to the motors to effectuate a highly accurate and predictable interaction between the bat and ball and a consistent flight path.

[0009] In a preferred arrangement, the ball delivery module includes a swing arm terminating in a fork with upper and lower members between which the ball is supported. The use of a fork shape enables the bat to swing between the upper and lower members while accurately adjusting the contact point. The ball support itself may either includes means for actively releasing the ball immediately prior to contact through the use of computer-controlled solenoid release switches. Alternatively, a break-away structure may be used which automatically releases the ball when struck. Different structures of this type are disclosed, including a two-piece arrangement having upper and lower cradles, and a one-piece unit having a central aperture within which the ball is carried. In preferred embodiments, these break-away structures are composed primarily of lightweight foam to minimize their impact on the various measurements.

[0010] A bat-swing sensor is used to output a signal carrying information associated with the swing speed of the bat. A ball-delivery speed sensor, disposed along the delivery path, is used to output a signal carrying information relating to the velocity of the ball, that is the “pitch” speed. In the preferred embodiment, a plurality of sensors are used to accurately determine exit velocity, with a first set of sensors being used to determine initial exit velocity as a function of angular displacement.

[0011] In response to an operator input, the main computer activates a hitting sequence mediated by the second computer while monitoring the signals output by the various sensors for data acquisition and analysis purposes. By selecting the sensed values indicative of the highest exit velocity, the system is able to automatically obtain accurate measurements despite slightly curved or angled trajectories, whatever the reason for such departures from a ‘perfect’ flight path.

[0012] The automated batting machinery and methods just described may be used in conjunction with a swing tester and an automated manufacturing process, both of which are also described herein. In the case of the swing tester, a human player is used to test a particular implement. For example, regard to baseball, a ball is positioned on a vertical, nonrigid support, with sensors on either side being used to measure bat swing and ball speed to determine a range of potential performance criteria, which may then be fed into the hitting machine for a much more refined analysis, including the ability to set more appropriate swing speeds.

[0013] In terms of automated manufacturing, as the performance characteristics are developed according to the invention, the information derived may be fed into a forming process to create an implement with specific performance range or restrictions. For example, in the case of a baseball bat, with knowledge of certain physical characteristics of the starting blank or “billet,” such as material composition, size, weight, center of gravity, density, and so forth, the information obtained from the hitting machine may be input to an automated lathe or other automatically controlled formation apparatus to create a bat exhibiting a particular performance aspect or range of behavioral attributes. This input to automated manufacturing is also applicable to non-wooden, composite, and metal implements, including aluminum bats, graphite rackets, and so forth.

[0014] The combination of the swing tester, which may be used to determine a particular range of performance capabilities, the hitting machine, which may be used to analyze a highly refined set of performance criteria, and the automated manufacturing processes may be used cooperatively to form a closed loop linking the capabilities of a human player to an end product having extremely exacting performance capabilities.

[0015] FIG. 1 is a drawing from an oblique overview depicting major modules comprising the invention;

[0016] FIG. 2 is a top-view drawing of the embodiment of FIG. 1 showing the placement of various sensors to monitor bat swing and to sense ball movement(s);

[0017] FIG. 3 is a more detailed drawing of a bat-swing module according to the invention showing a preferred motor drive and bat handle clamping arrangement;

[0018] FIG. 4 is a more detailed drawing of a ball-delivery module according to the invention;

[0019] FIG. 5 is an oblique view drawing illustrating the breakaway action of a ball support according to the invention;

[0020] FIG. 6 is an oblique view drawing illustrating the breakaway action of an alternative, preferred ball support;

[0021] FIG. 7 i s a screen display associated with a computer control aspect of the invention, illustrating some of the performance characteristics compiled for presentation on an attached display device;

[0022] FIG. 8 is a front-view drawing of a swing tester according to a different aspect of the invention; and

[0023] FIG. 9 is a schematic drawing of a feedback loop made possible by information extracted through the invention to establish an automated manufacturing process to realize an implement with particularized performance characteristics.

[0024] The present invention provides methods and apparatus for testing striking-type sports implements. As discussed in the Summary of the Invention, although the following description relates primarily to baseball batting, the teachings are equally applicable to sports which use rackets, mallets, or other types of striking implements, as well as objects to be struck other than round balls. Thus, the inventive concepts contained herein may be used to test and evaluate equipment associated with softball, tennis, squash, badminton, and any other sport wherein an object is struck by an implement.

[0025] Turning now to the drawings, FIG. 1 shows, from an oblique perspective, major components of a baseball bat hitting machine embodiment of the invention, which includes a bat-swing module 102, a ball-delivery module 104, and a movement-control computer 106 interfaced to modules 102 and 104 through communication paths 108 and 110, respectively. Interfaced to the movement-control computer 106 is a main computer 114 which communicates to computer 106 through connection 116. Although a suitably equipped multitasking type of computer may be utilized for all purposes, in the preferred embodiment the main computer 114 is used for the data acquisition and analysis functions discussed in further detail below, with movement-control computer 106 being relegated to bat-swing and ball-delivery module control, thereby off-loading the main computer of tasks associated with bat and ball timing, speed and contact-point coordination.

[0026] The bat-swing module 102, which is also discussed in reference to FIG. 3, includes a source of electromotive energy (not shown in this figure), coupled to means 120 for gripping the bat 122 at its handle end, and swinging the bat, as indicated by arrow 124. Ball-delivery module 104, which is discussed again with reference to FIGS. 4, 5 and 6, includes its own source of electromotive energy (also not shown in this figure), preferably coupled to an arm 130 having a distal end 131 adapted to support a ball 132, and being operative to swing the arm and ball, as indicated by arrow 134.

[0027] According to the invention, the paths of the swinging bat 122 and that of the ball 132 are precisely controlled to create a point of striking contact, in this case, in the vicinity of area 140, causing the ball 132 to leave its support, and travel off on a flight path or trajectory, as indicated by arrow 142. Although, in the preferred embodiment, the ball is actively delivered into the swing of the bat at high speed, the system may alternatively be programmed to simply hold the ball in a stationery position in the swing path of a moving bat.

[0028] Computer systems 106 and 114 serve several purposes, some of which are not evident in FIG. 1, but which will become more apparent from the specification as a whole. Broadly, both systems include a processor, which may be of conventional design, coupled to a user input, such as keyboard 146, and means for outputting program-related information, for example, on display device 148. It will be apparent to those of skill in the art that different input and output means may be used in conjunction with the computer systems, depending upon the circumstances.

[0029] Although both computer systems may be of conventional design, the hardware options of each will preferably be selected in accordance with their respective tasks, and the software programs of the two machines will be quite different. Specifically, system 106 will preferably include expansion modules and input/output interfaces associated with real-time control and, more particularly, to servomotor control, as further discussed below. The software resident on system 106 is also preferably dedicated to real-time, industrial-type control. Although such control software may be available, in part, from the manufacturer of the particular servo-motor used as the electromotive source, in the preferred embodiment, additional code, familiar to one skilled in computer programming, is provided to ensure proper coordination between the bat-swing and ball-delivery modules. In contrast, system 114 is more adapted to data acquisition and analysis, and may include expansion modules and input/output interfaces associated with sensor inputs such as analog-to-digital (A-D) converters. Additionally, the software resident on the system 114 will be more applicable to data formatting for operator interpretation and print-outs, as shown in FIG. 7.

[0030] Now making reference to FIG. 2, there is depicted certain aspects of the apparatus of FIG. 1, now viewed from a top-down perspective, and including other features of the invention such as bat and ball sensors to gather the performance data mentioned above. In particular, the system preferably includes a first set of optical sensor 202 and 202′ located approximately one inch from the point of impact 200 to determine swing speed. A second set of optical sensors 204 and 204′ are likewise provided approximately one inch from the point of impact 200 to determine the speed of the ball delivery or “pitch speed.” If the width of the ball and bat are known quantities, it may be possible to use a single sensor for bat and ball speed, respectively, however, in the preferred embodiment, a pair of sensors is utilized in each case, with one being designated as a ‘start’ sensor and the other being designated as a ‘finish’ sensor. More particularly, sensors 202 and 202′ in FIG. 2 constitute, respectively, the start sensor and finish sensors for the bat, whereas sensors 204′ and 204 constitute, respectively, the start sensor and finish sensors associate with ball delivery.

[0031] As a further aspect of a preferred arrangement, a plurality of optical detectors are arranged along the trajectory path discussed with reference to FIG. 1, to determine the exit velocity of the ball having been struck by the bat. In particular, a first arrangement of exit velocity sensors is positioned relatively close to the point of impact, whereas a third set of sensors is placed at a somewhat more distant point along the trajectory for the following reasons. The first sets of exit-velocity sensors, which are preferably arranged at 9 inches and 13 inches along the trajectory from the point of impact, are used not only to determine exit velocity, but, in the event that one of the two sets records a faster speed, the computing means associated with the invention automatically chooses this faster velocity, knowing that angular displacement or deviation of the ball from a “perfect” light path may have been responsible for the slower measurement. Additionally, the third set of sensors 216, which are placed at approximately six feet from the point of impact, not only measure exit velocity at this point, but in addition, performs yet a further check of the first two sets of sensors both in terms of speed and angular deviation, as the case may be. Though not shown in the figures, it should be mentioned that the bat-swing and ball-delivery modules are contained within a protective cage having an aperture through which the ball exits (i.e., a ‘target’), this aperture being only slightly larger than the ball itself, thus serving as yet a further indication that the ball is traveling on the correct path, that is, that the movements of the swing and delivery modules are properly coordinated by the computing means, which is preferably located outside of this protective cage for user interaction.

[0032] The various sensors are interfaced to the main and control computers along the paths illustrated in the drawing, as are the bat-swing and ball-delivery modules, as discussed above. These sensors are preferably of the type which comprise an emitter directed onto a detector defining an optical path which is broken by the bat, or ball, as the case may be. The various emitter/detector pairs may either be activated continuously (or cycled at a rapid rate), such that, by monitoring the amount of time that a particular path is interrupted, the computer 220 may calculate swing speed, bat movement, and so forth, in a relatively straightforward manner apparent to one of skill in the art of microprocessor-type system design. In terms of geometrical configuration, the emitter may be placed above or below the area through which the bat or ball is expected to travel, with the detector being placed oppositely such that the path is broken by virtue of the movement being monitored. Side-to-side arrangements are also possible, depending upon the circumstances.

[0033] As a further option, sensors may be added to determine bat and/or ball vibration, with the signals from such sensors being used to determine further performance characteristics such as “sweet spot.” These vibrations sensors are preferably implemented as accelerometer-type sensors, as described in co-pending U.S. application Ser. No. 08/717,549, the entire contents of which is also incorporated herein by reference. Whereas the bat vibration sensor(s) may be supported directly onto or within the bat and hard-wired to the computer for analysis, the ball sensor(s) are preferably installed along with an RF transmitter to permit a wireless communication. The ball sensor(s) may either be embedded within the ball or, since the point of impact is well known, may be placed on the backside of the ball elsewhere to avoid a direct hit by the bat.

[0034] FIG. 3 is an oblique representation of a bat-swing module which better illustrates certain features of this aspect of the invention. In particular, in a preferred embodiment, the electromotive source utilized to swing the bat is provided in the form of a servomotor 304, which is coupled to a vertical shaft 306 through some form of mechanical coupling, whether in the form of a gear, chain or pulley 308, as shown. In alternative embodiments, the drive means may be coupled directly to the vertical shaft 306, depending upon the particular mechanical capabilities of the drive unit chosen. The shaft 306 preferably emerges through a top panel 314 of an enclosure 310 through a series of bearings 320, which also assist in stabilizing bat movement, as coupled through the drive means.

[0035] At the top end of the rotating shaft 306, means are provided for gripping a bat at its handle end. Preferably, this grip takes the form of a padded cradle 330 which is attached to a base 332 which is, in turn, coupled to the upper end of the shaft 306. A clamping element 334 is provided which, when brought down in mating agreement with cradle 330, grasps the bat at its handle end to make possible a rigidly coupled swing without excessive slippage, but with an impact comparable to that delivered by a human batter. Note that by moving the bat along its longitudinal axis with the clamp loosened, the mechanism may be tightened to simulate the position of the batter's hands at various points along the bat, including “choked-up” positions.

[0036] Turning now to FIG. 4, there is shown, from a side. and cross-sectional perspective, a ball-delivery module according to the invention. As with the bat-swing module of FIG. 3, a separately computer-controlled servo motor 402 is used in a preferred embodiment to provide electromotive power for ball delivery, this motor 402 being coupled to a vertical shaft 404 which, in turn, is joined to a swing arm 406 having a distal, ball-supporting end, 408. Also, as with the bat-swing module, the electromotive source and coupling of the source to shaft 404 is preferably contained within an enclosure 410, with the shaft 404 emerging through the enclosure through a set of bearings 412 to provide overall stability.

[0037] The distal end 408 of the arm 406 preferably takes on a fork-like configuration, having upper and lower members spaced apart by a distance on the order of five or six inches or more. This fork-like configuration serves as to two purposes, first, as evident from FIGS. 2, 4, 5 and 6, the arrangement enables the end of the bat to swing between the upper and lower members when striking the ball, which affords a convenient mechanism by which the point of contact may be adjusted. In addition, the fork-like configuration at the distal end of the ball-delivery swing arm is used to accommodate the ball-release mechanisms described below.

[0038] These ball-release devices may either be “active” or “passive” according to the invention. The active mechanisms use upper and lower electromechanical components such as electric solenoids which automatically retract immediately prior to contact with the ball, with the computer system described in further detail below being responsible for coordinating such release to ensure that it occurs on the order of a millisecond prior to the moment of contact.

[0039] In a preferred embodiment, however, the invention utilizes a passive break-away type structure which automatically releases the ball upon impact. One such structure is illustrated in FIG. 5, which shows a pair of upper and lower lightweight shells 502 and 504, respectively. Preferably composed of foam, these shells 502 and 504 leave exposed the girth of the ball 506 to be struck in an unimpeded fashion by the bat, while readily falling away upon impact, as indicated by shells 502′ and 504′ in the drawing.

[0040] FIG. 6 is an oblique view drawing illustrating an alternative breakaway type of ball support which, in fact, is used in a preferred embodiment. In place of the two-part structure of FIG. 5, a single apertured block 602 is used which, again, is preferably composed of a lightweight foam material. This block 602 is held between the upper member 604 and lower member 606 of the swing-arm assembly of the ball-delivery module, with stops 608 and 610 being used to contain the block 602 as the arm swings. The block 602 preferably includes a more or less centralized aperture 620 within which the ball 622 rests. Preferably, the aperture 620 is made slightly larger than the diameter of the ball 622, with a small plastic spacer member 624 being used to ensure a snug fit of the ball 622 against the inner wall of the aperture 620 and against a sheet of adhesive material 640 (i.e, tape), preferably placed flush against the backside of the block 602.

[0041] With the ball supported in this way the point of contact 630 is sufficiently pronounced relative to the surface 632 of the block 602 that, upon impact, the bat strikes the ball in advance of the block material, enabling the ball to be ejected by the block and enter an exit trajectory in a substantially unimpeded fashion, with the block 602 trailing far behind, with little negative impact. The adhesive properties and tensile strength of the tape 640 are carefully selected so as to carry the supported ball through a controlled swing, yet readily give way upon impact.

[0042] As an adjunct to this invention, a swing tester apparatus depicted in FIG. 8 may be used in conjunction with a human batter 806 to provide a range of performance characteristics such as actual swing speed as a function of bat weight, length, center of gravity, and so forth. These characteristics may be gathered prior to the automated testing of the equipment involved, thereby allowing the settings of the hitting machine to be that much more directed, refined, and/or practical for a particular range of performance.

[0043] Continuing the reference to FIG. 8, the swing tester preferably includes a lower frame 802 upon which there is disposed a vertical support 804 upon which the ball 805 rests, an element commonly referred to as a “tee.” This tee 804 is sufficiently rigid to hold the ball in a desired configuration, but not so rigid as to interfere with the swinging movements of the batter 806. Accordingly, the tee may be comprised of a non-rigid or somewhat flexible accordion-type of member.

[0044] A first set of emitters 820 and detectors 822 are used to determine the swing velocity of the bat 810, and a second set of emitters 830 and detectors 832 are used to obtain at least a rough approximation of exit velocity, given the characteristics of the bat 810 and, to some extent, the characteristics of the ball 805. Note that, whereas the emitters and detectors 820 and 822 may form vertical lines which are broken by the bat, in a preferred embodiment of the swing tester the light from emitters 830 fans out to bar-shaped detectors 832, preferably transverse to the path of trajectory, enabling an accurate determination of exit velocity to be calculated despite the angular deviation of the ball 805 as it leaves the top of the pedestal 804.

[0045] FIG. 9 shows how the hitting machine depicted in FIGS. 1-7, and the swing tester of FIG. 8 may be used in conjunction with a computer numerically controlled (CNC) lathe 902 or other automated formation or modification system to produce a striking-type sports implement such as bat 903 (shown in broken-line form), in this case, from a starting billet of wood 904. Given the comprehensive performance data made possible by the hitting machine, and knowing the physical characteristics of the billet 904, such as center of gravity, density, and/or density per unit of length, by measuring a similar implement, and recording its performance characteristics at a number of contact points along its length, this information may be fed into the CNC lathe 902, to create a bat 903 having a desired set of performance characteristics. For example any given set of physical criteria may be used to achieve a desired target center of gravity. Moreover, this capability may not only be used to ensure that a particular implement for its maximum performance for a given weight, length, or cross-sectional aspect, but may also be used to limit performance, for example, to ensure that exit velocity will also be below a certain amount for a given object being struck, thereby contributing to player safety.

[0046] Having produced an implement in this fashion, it may then be given to a human for testing, for example, using the swing tester of FIG. 8 in the case of a baseball bat. In the event that the bat produced with CNC lathe 902 exhibits performance characteristics which deviate from those desirable, the output of swing tester may be fed to hitting machine, and again to the lathe, in closed-loop fashion, until a particular characteristic or range of performance features is ultimately realized.

[0047] Having been presented with this disclosure, it will be readily apparent to one of skill that various modifications may be made to the apparatus and method disclosed herein while remaining in the spirit of the invention. For example, one or more video monitors and appropriate object-tracking hardware and software may be used in place of light emitters and detectors described with reference to the hitting machine of FIGS 1-7 and/or the swing tester described with reference to FIG. 8, as discussed in my co-pending patent application Ser. No. 09/244,909, the entire contents of which are incorporated herein by reference. In particular, one or more video monitors may be used in conjunction with appropriate image processing capabilities to replace or augment the optical sensors used to determine swing speed, pitch speed and/or exit velocity with reference to the hitting machine, as well as the optical sensors used to monitor the swing velocity and/or exit velocity of the swing tester discussed with reference to FIG. 8.

[0048] Various alternative embodiments are also possible with respect to the way in which the ball is delivered to the batting machine, or to a human batter, for that matter. For example, in place of a swing arm that holds the ball until impact, the ball may be placed into a cup or other open-ended device, and wherein the arm used to swing the device is reversed prior to impact, so as to “fling” the ball toward the bat, rather than carrying it all the way to the point of impact. The fork described above and holder of FIG. 6 may also be used for such purpose. In such a configuration, the radius of the bat and the radius of the delivery arm would not necessarily overlap, since the cup or other device used to fling the ball could essentially “get out of the way” before entering into the radius of the bat swing. As a further alternative, an air cannon or other such device may be used in lieu of a swing arm, in which case controls may be added along with mechanical tripping to provide a match to a desired air speed.

[0049] The invention is also applicable to other types of testing methods beyond sports implement performance. For example, since the invention may be used to provide a precise swing of one object to another, it may be used for impact testing of composites, models, and other materials, for example, in the automotive industry. That is to say, the hitting machine may be used to “hit” materials to determine their relative strength given a precise impact delivered by the invention.