Abstract:
A practice device comprising a plurality of striking targets arranged about a frame in an overall configuration which approximates the shape of an opponent. The targets are individually articulated to the frame, so that each individual target reacts independently in response to a strike. The targets are each in communication with a common force sensor, through a load transfer shaft movable relative to the frame and bearing on a force sensor such as a load cell, which provides feedback to the athlete regarding the force of each strike.

Description:
FIELD OF INVENTION 
     This invention relates to practice targets. In particular, this invention relates to a striking practice device providing a plurality of striking targets and a sensor for providing an indication of the striking force imparted to an individual striking target. 
     BACKGROUND OF THE INVENTION 
     Practice devices having striking targets are used by athletes in martial arts and martial sports, to hone desirable qualities such as speed, coordination, accuracy and flexibility. For example, one popular practice device is a large punching bag known as a “heavy bag”, also known as a “kicking bag” or “body bag”, which typically comprises a canvas, vinyl or leather sac filled with a heavy material such as sand, water or the like. The filler imparts resilience and inertial resistance to the bag, reproducing the effect of striking a human opponent and thus allowing an athlete to practice potentially injurious techniques without actually harming an opponent. The heavy bag also provides the advantage of approximating the breadth and height of an opponent, which adds to the realism of the heavy bag as a practice device. 
     However, the heavy bag provides little feedback to the athlete regarding the accuracy or force of a strike. In general the degree to which the bag deflects under the force of a strike increases with the force of the strike, which provides a rough visual indication of striking power. However, the degree of deflection of the bag is also influenced by other factors such as the point of impact, a strike remote from the anchoring point deflecting the bag more than a higher strike of the same force near the anchoring point, and the angle of impact, since a glancing blow imparts less energy to the bag than a centred strike of equal force and thus deflects the bag less. 
     At a typical striking speed it is difficult for an athlete, particularly while concentrating on an exercise, to determine whether and to what extent the degree of deflection of the bag may have been attributable to factors other than the force of the strike. The heavy bag thus provides very poor feedback to the athlete, in a sport which relies very heavily on feedback to provide a means and motivation for improving the athlete&#39;s skills. 
     Practice devices are known which provide striking force feedback to an athlete. For example, U.S. Pat. No. 5,605,336 issued Feb. 25, 1997 to Gaoiran et al, which is incorporated herein by reference, provides a shock sensor affixed to a heavy bag for measuring the magnitude of a shock experienced by the bag during a strike. The shock sensor provides a quantified feedback indication to the athlete relating to the force of the strike. However, the shock detected by the sensor is affected by the vertical position at which the strike impacts the bag, and radial point of impact due to the rounded exterior of the bag, and thus still provides only a rough indication of the actual striking force. 
     U.S. Pat. No. 4,534,557 issued Aug. 13, 1985 to Bigelow et al, which is incorporated herein by reference, provides sensors associated with a variety of different types of striking targets, including a heavy bag and a number of smaller targets, to provide striking force feedback to the user. The smaller targets to some degree avoid the extraneous factors which influence the measured striking force, because limiting the size of the striking surface commensurately reduces the athlete&#39;s freedom to strike positions remote from the sensor. However, randomly positioned small targets do not realistically reflect the shape of an opponent&#39;s body, nor the arrangement of the sensitive areas of an opponent which martial arts and sports emphasize as striking targets for maximum efficacy. 
     As such, striking individually positioned small targets for practice does not improve the athlete&#39;s ability to selectively strike at susceptible target areas, as opposed to invulnerable or strike-resistant target areas of an actual opponent. The provision of multiple targets with separate sensors also renders this type of equipment complex and expensive. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes these disadvantages by providing a practice device which comprises a plurality of striking targets arranged about a frame in an overall configuration which can be made to approximate the shape of an opponent. The targets are individually articulated to the frame, so that each individual target reacts independently in response to a strike. The targets are each in communication with a common force sensor, which provides feedback to the athlete regarding the power of each strike. 
     The invention accomplishes this by providing a load transfer shaft movable relative to the frame and bearing on a force sensor such as a load cell. The striking targets are hinged to the frame, preferably spring biased to a rest position, such that when an individual target is struck the force of the strike is transferred to the load transfer shaft. The load transfer shaft is thereby moved to alter a resting force on the load cell. The difference between the resting force and the striking force is output to an indicator, for example a visual indicator such as an LCD display, to provide striking force feedback to the athlete. 
     In alternate embodiments the striking targets may be removable, and replaceable with targets of different shape or resilience/hardness. The targets may be positioned as desired, for example to accommodate a particular martial art or style or to emphasize particular sensitive areas of an opponent. The force indicator may be visual or audible, and may be enabled by a threshold striking force. These and other embodiments of the invention will be apparent from the description which follows. 
     The present invention thus provides a practice device, comprising a frame, a load transfer shaft movable relative to the frame, a plurality of striking targets supported on the frame, each striking target being operably affixed to a load transfer arm movable relative to the frame and affixed to the load transfer shaft, and a force sensor in operative communication with the load transfer shaft, for providing an indication of striking force, wherein a striking force applied to a target is transferred through the load transfer arm and moves the load transfer shaft to alter a resting force of the load transfer shaft on the force sensor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In drawings which illustrate by way of example only a preferred embodiment of the invention, 
     FIG. 1 is a side elevation of a practice device embodying the invention, 
     FIG. 2 is a partial elevation of the practice device of FIG. 1 showing the motion of a striking target, 
     FIG. 3 is an enlarged elevation of a striking target in the practice device of FIG. 1, 
     FIG. 4 is a top cross-section of the practice device of FIG. 1, and 
     FIG. 5 is a plan view of the practice device of FIG. 1 showing a striking target extension for reorienting the striking surface. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A preferred embodiment of the practice device  10  of the invention is illustrated in FIGS. 1 and 4. The device  10  comprises a frame  12 , which may be free-standing or adapted to be affixed to a floor or wall, which is rigid and sufficiently strong to withstand the force of repeated strikes on the striking targets  50 . The illustrated frame  12  is composed of steel and bolted, riveted, welded or otherwise suitably connected to form an integral frame structure. 
     The preferred embodiment of the frame  12 , best illustrated in FIG. 4, comprises front and side sections  14 , each channel-shaped with sides  16  for hingedly mounting sway arms  40  supporting the striking targets  50 , for example on axels  42  pivotally mounted in bushings  18  for relatively free rotation. The front and side sections  14  have suitably positioned openings  14   a  through which load transfer arms  60  extend, as described below. The openings  14   a  also help to reduce the cost and weight of the device  10 . Alternatively, the frame  12  may be constructed from rails, angle irons, tubes or any other suitably strong structural members, and the number of sides provided by the frame is determined by the desired number and positions of striking targets  50 . 
     The illustrated embodiment is adapted to be affixed to a wall. A back section  22  is thus connected along rear edges of the side sections  14 , for example by brackets  22   a,  rigidifying the frame  12 . Projecting from the back section  22  is a spacer channel  24  having a back plate  26  with holes (not shown) for screws, lag bolts or other fasteners suitable for the wall surface to which it will be affixed. 
     A plurality of striking targets  50  are supported on the frame, each striking target  50  being mounted on preferably two sway arms  40 , as shown in FIGS. 2 and 3. The sway arms  40  are preferably formed from metal, which may for example be configured as a channel or tube for strength, but may alternatively be rigid plastic, wood or any other suitably strong rigid material that will transfer the force of a strike against the striking target  50 . 
     The striking targets  50  may comprise a mounting plate  52  to which the striking surface  80  will be mounted, integrally formed with side flanges  54 . The sway arms  40  may be welded, bolted, clipped or otherwise suitably affixed to the inner face of the mounting plate  52  near both the top and bottom of the striking target  50 , forming a parallelogram which maintains the mounting plate  52  generally parallel to the frame  12  at all times. The other ends of the sway arms  40  are attached to the axels  42  so as to prevent rotation therebetween, as by welding, bolts, flats or in any other suitable manner. The axels  42  are in turn pivotably affixed to the sides  16  of a front or side frame section  14 . The striking targets  50  can thus pivot relative to the frame  12 , and as the striking target  50  pivots the axel  42  to which it is mounted rotates in the bearings  18 . 
     A load transfer arm  60 , also preferably formed from a metal channel or tube, is similarly affixed to each axel  42  so as to prevent rotation therebetween, as by welding, bolts or in any other suitable manner. The load transfer arm  60  thus pivots with the associated sway arm  50  whenever the striking target  50  is moved by the force of a strike. 
     The other end of each load transfer ann  60  is operably affixed to a load transfer shaft  30  that is mounted so as to be movable relative to the frame  12 , preferably disposed generally centrally within the frame  12  as shown in FIG.  4 . The load transfer shaft  30  may be composed of wood, metal or any other suitably rigid material, and in the preferred embodiment rests on a force sensor  32 , for example a load sensor cell, which is mounted to the frame in a stationary position. The force sensor  32  may be any commercially available load cell connected to associated detector/indicator circuitry, for example load cells manufactured by Entran Devices Inc. or Omegadyne, Inc., or may be a torque sensor, pressure sensor or the like suitably coupled to the load transfer shaft  30 . 
     A plurality of shoulder plates  62  are axially fixed to the load transfer shaft  30 , one at each position corresponding to the horizontal levels of the load transfer arms  60 . In the embodiment shown, with striking targets  50  along both sides and the front of the device  10 , the shoulder plates are “T”-shaped so as to provide an end corresponding to the load transfer arm  60  from each striking target  50 . The shoulder plates  62  may be provided with any other configuration suitable for accommodating the positions of the striking targets  50 . 
     Each load transfer arm  60  is affixed to one end of the corresponding shoulder plate  62 , preferably through a shock absorber such as compression spring  64  retained between the shoulder plate  62  and a cap  66 . The load transfer arm  60  is affixed to the end of a shaft  68  secured to the cap  66  and slidably extending through the spring  64  and the shoulder plate  62 . Thus, when the load transfer arm  60  is drawn away from the shoulder plate  62  the spring  64  is compressed as the cap  66  is drawn toward the shoulder plate  62 . 
     The load transfer arm  60  is thereby retained in a generally horizontal orientation by the shaft  68 , which in a rest position holds the inner end of the load transfer arm  60  beneath the shoulder plate  62 . The load transfer arm  60  is preferably spaced from the shoulder plate  62 , thus allowing the shoulder plate  62  to move under the force of a strike hitting any striking target  50  without encountering resistance from other striking targets  50  in the rest position, as can be seen in FIG.  2 . The load transfer arm  60  in turn retains the sway arm  40  in an oblique orientation as shown, preferably at a sharply acute angle relative to the frame  12  so that the path of travel of the striking target  50  is largely radial (horizontal) relative to the frame  12 . 
     With this arrangement, in the rest position the plurality of striking targets  50  can be retained in substantially vertically aligned relation by the load transfer shaft  30  resting on the load cell  32 . If desired, the striking targets  50  may be retained in staggered rest positions, by making suitable adjustments to the angles of the sway arms  40  for different striking targets  50 . 
     It will be appreciated that in a basic embodiment, for each striking target  50  only a single load transfer arm  60  is required. In the preferred embodiment load transfer arms  60  are provided for both the upper and lower sway arms  40  along one side of the striking target  50 . If desired, all four sway arms  40  may be provided with load transfer arms  60 , however this would be unnecessary in most cases. 
     The striking surface  80 , the rigidity of which may be selected according to the requirements of the user, may be formed integrally with the mounting plate  52  of the striking target  50 . However, in a preferred embodiment a striking surface  80  is provided as a separate attachment and removably mounted to each striking target  50 . This allows the user to select a striking surface  80  having suitable resilience (cushioning) for the type of practice desired. For example, a barehanded striker may desire more cushioning than a boxer wearing cushioning gloves. This also allows different sizes of striking surfaces  80  to be mounted to the striking targets in any desired arrangement, as shown in FIG. 1, to more closely approximate the sizes of targets on an actual opponent, and facilitates cleaning of the striking surfaces  80 . (The striking surfaces  80 , shown in FIG. 1, have been omitted from FIGS. 2 to  5  for purposes of illustration.) 
     In operation, when the striking targets  50  are in the rest position the load transfer arms  60  are also in a rest position beneath the shoulder plates  62 . The weight of the load transfer shaft rests on the load cell  32 . The load cell indicator circuitry (not shown) is calibrated to zero with the weight of the load transfer shaft  30  at rest. As a striking surface  80  is struck, the striking target  50  on which the striking surface  80  is mounted is pushed toward the frame  12 , as shown by the arrow at the bottom left in FIG.  2 . The arcuate motion of the striking target  50  pivots the sway arms  40 , and thus the load transfer arms  60  associated with the moving target  50 . The inner ends of the load transfer arms  60  draw the shafts  68  downwardly, forcing the caps  66  and thus the associated shoulder plates  62  downwardly. The load transfer shaft  30  moves with the shoulder plates  62 , and the force of the load transfer shaft  30  against the detector component of the load cell  32  increases. This increase in force is indicated by the load cell indicator circuitry (not shown), which provides a visual or audible indication of force to the user. 
     Thus, irrespective of which striking target  50  is struck, the force of the strike is imparted to the load transfer shaft  30  and the force of the load transfer shaft  30  on the load cell  32  increases. The space between the shoulder plates  62  and the load transfer arms  60  of all resting striking targets  50  allows the shoulder plates  62  to move with the load transfer shaft  30  without resistance. When the force of the strike is removed, the load cell  32  forces the load transfer shaft  30  to the rest position. 
     It will be noted that for most conventional load cells  32 , only a slight movement of the load transfer shaft  30  is required to obtain the desired force indication. The extent of movement of the load transfer shaft  30 , load transfer arms  60  and springs  64  has been exaggerated in FIG. 2 for purposes of illustration. 
     It will be appreciated that any number of striking targets  50  may be mounted to the frame  12 , and the orientations of the striking targets  50  may be selected by selecting the angles between frame sections  14  for any particular application. 
     In another preferred embodiment a striking extension plate  90  is provided, as shown in FIG. 5, which alters the angle of a striking target  50 . The extension plate  90  is hingedly mounted to the frame  12  along one side of the extension plate  90 , as by hinge  93  on brace  92  shown in FIG. 5, so that the extension plate  90  can pivot in a horizontal plane. An extension bar  94  projects from the rear face of the extension plate  90  and contacts the striking target  50 . The striking surface  80  (not shown) can then be mounted to the extension plate  90  in any suitable fashion. 
     The extension plate  90  effectively changes the angle of the striking target  50  by transferring the force of a strike through the extension bar  94  to a striking target  50 . The operation of the practice device is otherwise as described above. This allows for a versatile rearrangement of the orientations of the striking surfaces  80 , merely by selecting the position of the brace  92  and the length of the extension bar  94 , without requiring any realignment of the frame sections  14 . 
     It will be appreciated that the indication of striking force is provided by the difference between the force of the load transfer shaft  30  against the load cell  32  at rest and the force of the load transfer shaft  30  against the load cell  32  during a strike. In the preferred embodiment the load cell  32  is positioned beneath the load transfer shaft  30 , and the striking force increases the force against the load cell  32 . The force sensor  32  could be positioned elsewhere, for example above the load transfer shaft  30 , such that the striking force decreases the force of the load transfer shaft  30  against the force sensor  32 , and the effect would be the same so long as the force sensor indicator circuitry is calibrated accordingly. The particular position of the load cell  32  in the embodiment shown is merely one preferred example. 
     In a further preferred embodiment of the invention a sensor  100  is affixed to a part of the strike load transfer assembly (i.e. the striking target  50 , sway arms  40 , axels  42  or load transfer arms  60 ) of each target to indicate which target has been struck. The sensor  100 , shown in FIG. 3, may for example be a vibration detector, or any other sensor adapted to detect movement of the strike load transfer assembly. The sensors  100  are individually wired to a controller, for example a microprocessor, which is thus capable of discriminating between the various striking targets  50  to provide an indication to the user as to which striking target  50  has been struck. This information can be conveyed to the user by a numerical or other symbolic indication generated on a display, or by an indicator, for example a light (not shown), physically associated with the striking targets  50 . 
     In this embodiment, as each striking target  50  is struck the sensor  100  associated with that striking target  50  sends a signal to (or closes a circuit within) the controller (not shown) in conventional fashion, and the controller in turn displays a symbol associated with the striking target  50  or activates an indicator associated with the striking target  50  to convey this information to the user. 
     A preferred embodiment of the invention having been thus described by way of example only, it will be apparent to those skilled in the art that certain modifications and adaptations may be made without departing from the scope of the invention. The invention includes all such modifications and adaptations as fall within the scope of the appended claims.