Abstract:
An apparatus for measuring a ball hitter&#39;s “leg drive” for training and coaching purposes and for developing a strong leg drive (ground force). The apparatus includes a ground engaging lower plate and an upper plate that supports the hitter&#39;s foot. The plates are slidingly secured to one another such that the upper plate is linearly moveable relative to the lower plate. A force measuring element is provided between the upper and lower plates. The apparatus is used by the hitter stepping on the upper plate and pushing while hitting, thereby linearly moving the upper plate against the lower plate and the force measuring element, which may comprise a load cell or a spring mechanism. The apparatus provides an output indicative of the hitter&#39;s leg drive (ground force) level. In some embodiments, an audible sound is generated when a preselected leg drive level is reached.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an apparatus and method for measuring the “leg drive” or “ground force” of, for example, a baseball or softball hitter, for training and coaching purposes, and for developing a strong leg drive that ultimately increases energy that creates more power and bat speed. 
         [0003]    2. Background 
         [0004]    As is well known to those familiar with the games of baseball and softball, the hitter hits a baseball thrown by a pitcher who intends to make the batter miss. It is, of course, desirable to hit the ball with as much power as possible and the longest distance. In this regard, a hitter pushes against the ground and thereby “drives” with his or her legs to propel his or her body into a rotational manner to ultimately swing the bat more forcibly. The force (Ground Force) exerted by hitters against the ground is known as the hitter&#39;s “leg drive”. It has been found that the speed at which the bat is swung can be increased by increasing the hitter&#39;s leg drive force (Ground Force). 
         [0005]    Devices for measuring “leg drive” are currently known. For example, U.S. Pat. No. 6,616,556 (Osmundson) discloses a method and apparatus for measuring leg drive wherein a pressure transducer element or gauge is integrated into a pitching rubber and wherein the output of the pressure gauge is used for creating a “leg drive” pressure profile. The device is useful in evaluating baseball pitchers, determining if a pitcher has recovered from injury, determining if a pitcher is tiring during a game, providing an indication of the pitchers ability to throw hard, for training and coaching purposes for developing a strong leg drive, etc. However, this apparatus cannot be used without a display device such as a computer making it generally cumbersome for use outdoors on baseball fields. Because this apparatus locates the pressure transducer element(s) along the front surface of the pitching rubber, the output is dependent on the pitcher making proper contact therewith. Accordingly, this apparatus could potentially be unreliable. 
         [0006]    A need exists for an improved leg drive (Ground Force) measuring and training apparatus which is generally easily usable and which reliably provides a consistent output indicative of the leg drive (Ground Force). 
       SUMMARY OF THE INVENTION 
       [0007]    In one exemplary embodiment, the hitting training apparatus of the present invention comprises a lower ground engaging plate and an upper hitter&#39;s foot supporting plate. The lower and upper plates are linearly movable relative to each other. The present invention further comprises a force measuring element provided between the upper and lower plates. When pushed by a hitter during the act of swinging, for example, a bat, the upper plate moves linearly and the force element exhibits an output indicative of the hitter&#39;s leg drive. 
         [0008]    The present invention may further comprise a plurality of slides sandwiched between the upper and lower plates, wherein each of the slides is secured to each of the lower and upper plates whereby the lower and upper plates are linearly movable relative to each other. Further, preferably, a pair of oval holes are provided extending through the upper plate and a shoulder bolt is received through each of the holes and is secured to the lower plate, whereby the upper and lower plates are maintained in parallel adjacent to one another and the linear movement is limited by the size of the holes. 
         [0009]    The force measuring element of the present invention may comprise a load cell providing an electrical output indicative of the hitter&#39;s leg drive (Ground Force) and the output can further include an audible sound. 
         [0010]    The element can also comprise a spring mechanism. The spring mechanism includes a cylindrical shell having a bore extending therethrough. A plunger is located in the bore and projects beyond a terminal end of the shell. The plunger abuts the upper plate. A spring is located in the bore and urges the plunger against the upper plate with a spring force. A threaded fastener is provided adjacent the spring. The fastener is adapted to engage the spring and thereby adjust a length of the spring, whereby the spring force is selectively adjustable. The output can include an audible sound generated by the upper plate hitting the shell when the spring force is overcome. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of the embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0012]      FIG. 1  is a perspective view of a first embodiment of a leg drive (Ground Force) measuring and training apparatus constructed in accordance with the principles of the present invention; 
           [0013]      FIG. 2  is a top plan view of the apparatus shown in  FIG. 1 ; 
           [0014]      FIG. 3  is a side elevation view of the apparatus shown in  FIG. 1 ; 
           [0015]      FIG. 4  is a perspective view of a second embodiment of a leg drive measuring and training apparatus constructed in accordance with the principles of the present invention; 
           [0016]      FIG. 5  is a top plan view of the apparatus shown in  FIG. 4 ; 
           [0017]      FIG. 6  is a side elevation view of the apparatus shown in  FIG. 4 ; 
           [0018]      FIG. 7  is a perspective exploded view of the apparatus shown in  FIG. 4 ; 
           [0019]      FIG. 8  is a top plan view of the lower ground engaging plate of the apparatus shown in  FIG. 4 ; 
           [0020]      FIG. 9  is a top plan view of the upper hitter&#39;s foot supporting plate of the apparatus shown in  FIG. 4 ; 
           [0021]      FIG. 10  is a front elevation exploded view of the apparatus shown in  FIG. 4 ; 
           [0022]      FIG. 11  is a side elevation exploded view of the spring force measuring and sound generating mechanism used in the embodiment of  FIGS. 4-6 ; and 
           [0023]      FIG. 12  is a cross-sectional view of an assembled mechanism shown in  FIG. 11 . 
       
    
    
       [0024]    Corresponding reference characters indicate corresponding parts throughout several views. Although the exemplification set out herein illustrates embodiments of the invention, in several forms, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed. 
       DETAILED DESCRIPTION 
       [0025]    A leg drive measuring and training apparatus constructed in accordance with the principles of the present invention is shown in the drawings and generally designated by the numeral  10 . Apparatus  10  can be used by baseball and softball hitters and coaches for measuring leg drive (ground force), for training purposes and for increasing leg drive (ground force). Although described herein for use by baseball and softball hitters and coaches, it should be understood that the apparatus  10  can be used for measuring leg drive in other sports and other applications. 
         [0026]    Apparatus  10  includes a ground engaging lower plate  12  and an upper plate  14  on which a hitter&#39;s foot is supported. Plates  12 ,  14  are preferably made of 3/16 inch thick steel which have been surface treated to prevent rust such as by painting, galvanizing, etc. Plates  12 ,  14  can also be made of other materials including, for example, aluminum, plastics and nylon etc. The ground engaging lower plate is rectangular having a front edge  12 F, a left edge  12 L, a right edge  12 R and a back edge  12 B. Ground engaging lower plate  12  is preferably about 15×17 inches. The foot supporting upper plate  14  is also rectangular having a front edge  14 F, a left edge  14 L, a right edge  14 R and a back edge  14 B. Upper plate  14  is preferably about 13×15 inches. 
         [0027]    Plates  12  and  14  are slidingly secured to one another whereby, when the lower plate  12  is engaged or otherwise secured to the ground, upper plate  14  is slidingly linearly movable along a plane parallel with the plates  12 ,  14  and in a direction as indicated by double-headed arrow  16 . In this regard, a pair of slides  18  is provided and is sandwiched and secured between the upper and lower plates  12 ,  14 . Slides  18  can be center mount ball-bearing drawer slides having a lower slide bar  20  slidingly secured to an upper slide bar  22  in a known and customary manner Drawer slides  18  are well known, commercially available, and are commonly used for slidingly supporting cabinet drawers and other objects. It is contemplated that other slide devices, mechanisms and structures can equally be used which are capable of slidingly securing upper and lower plates  12 ,  14  to one another and allowing them to slide linearly relative to each other in a plane as indicated by arrow  16 . 
         [0028]    As best seen in  FIGS. 7-11 , the lower slide bars  20  of each of the slides  18  are secured to the lower plate  12  with spring/roll pin fasteners  24  which extend through holes (not shown) in the lower slide bars  20  and holes  26  in the lower plate  12 . Similarly, the upper slide bars  22  of each of the slides  18  are secured to the upper plate  14  with spring/roll pin fasteners  24  which extend through holes  27  in the upper slide bars  22  and holes  28  in the upper plate  14 . For added strength, the spring/roll pin fasteners can be tack welded in their respective holes. 
         [0029]    The lower and upper plates  12 ,  14  are retained together/adjacent one another with the slides  18  sandwiched therebetween with four shoulder bolts  30 . Shoulder bolts  30  include a tool engagement head  32 , a central shaft  34  and a threaded terminal end  36 . Shoulder bolts  30  are received through oval holes/openings  38  in the upper plate  14  and the threaded terminal ends  36  thereof threadingly engage and are secured in threaded holes  40  in the lower plate  12 . The length of the central shafts  34  is such that, when the shoulder bolts  30  are securely engaged in holes  40 , the tool engagement heads  32  are located a short distance/slightly above the upper plate  14 . Preferably, oval openings  38  are about 0.390 inch in the short direction and about 0.465 inch in the long direction. Also preferably, the diameter of the shoulder bolt central shaft is about 0.375 inch. Accordingly, because the shoulder bolt heads  32  are larger than the oval openings  38 , plates  12  and  14  are maintained adjacent and parallel to one another with the slides  18  sandwiched therebetween. Also, because the oval openings are larger in the long direction, the upper plate  14  is freely slidable/movable as indicated by arrow  16  but limited to a travel distance of the long length of each opening  38  less the diameter of the respective central shaft  34 , or about 0.090 inch (0.465-0.375=0.090). Of course, the tolerances of the several components are such that the upper plate  14  will slide freely relative to the lower plate  12  without excessive frictional engagement or binding. 
         [0030]    Mounting holes  50  are provided in and extend through the lower plate  12 . Mounting holes  50  are adapted to receive a mounting stake or screw therethrough whereby, during use, the apparatus  10  can be secured to the ground, a batter&#39;s box, interior floors, etc. The upper plate  14  is provided with access holes  52  which are aligned with and which provide access to the mounting holes thereunder. 
         [0031]    Referring now to the embodiment shown in  FIGS. 1-3 , the apparatus  10  includes a force/compression load cell  54  secured by fasteners or other suitable means between the lower plate  12  and upper plate  14 . Preferably, a bracket  56  is secured to the lower plate  12  by welding, fasteners or other suitable means and the load cell  54  is secured thereto with fasteners (not shown) for locating the load cell sensor/plunger adjacent the upper plate  14  as needed. A stud  58  can be welded or otherwise secured to the upper plate  14  and the load cell sensor/plunger can be located adjacent thereto. 
         [0032]    Force/compression load cells are commercially available and well known to those skilled in the art and are capable to providing an analog or digital electrical output responsive to the compressive force being exerted thereon. Load cell  54  is electrically connected to a computer or other similar device (not shown) whereat the output thereof can be stored, displayed and transmitted as needed or desired. As should now be appreciated, load cell  54  acts as a stop for the linearly moveable upper plate  14  relative to the lower plate  12  and measures the applied force/leg drive therebetween. 
         [0033]    The apparatus  10  of  FIGS. 1-3  is used by a baseball or softball hitter by placing his/her foot on the upper plate  14 . The hitter then goes into the swing pattern, as is known and customary, pushing against upper plate  14  with his or her back foot. The hitter&#39;s leg drive/force (Ground Force) against upper plate  14  thereby causes the upper plate  14  to slide toward and against the load cell  54 . The load cell  54 , therefore, effectively measures and provides an output responsive to the hitter&#39;s leg drive which can be stored, displayed and transmitted. The measured leg drive force can then, of course, be used as needed for training and other purposes. 
         [0034]    Referring now to the embodiment shown in  FIGS. 4-12 , the apparatus  10  includes an adjustable spring force/compression measuring and sound generating mechanism  60 . As shown in  FIGS. 11 and 12 , mechanism  60  includes a cylindrical shell  61  having a bore  62  extending therethrough between axial terminal ends  64 ,  66 . Bore  62  includes a plunger receiving section  68  adjacent terminal end  64 , a threaded section  70  adjacent terminal end  66  and a spring receiving section  72  between terminal end  64  and terminal end  66 . An annular seat  74  is provided between the plunger receiving section  68  and the spring receiving section  72 . 
         [0035]    Plunger  76  is received through the threaded section  70  and the spring receiving section  72  and is located within plunger receiving section  68  whereat the annular shoulder  78  thereof is seated against annular seat  74 . In this position, the terminal end  80  of plunger  76  extends beyond the terminal end  64  of the shell  61 , preferably, a distance which is equal to or greater than the travel distance of the upper plate  14  described hereinabove. Spring  82  is received through the threaded section  70  and is located within the spring receiving section  72  and abutting the head  84  of plunger  76 . Spring  82  is compressed and an alien screw  86  is threadingly received in threaded section  70  of bore  62 . As can be appreciated, alien screw  86  maintains spring  82  in compression which, in turn, maintains the plunger shoulder  78  seated against the annular seat  74 . Additionally, by threadingly axially adjusting alien screw  86  along the bore threaded section  70 , the force F required to move plunger  76  against the spring  82  and lift the plunger head  84  off of the annular seat  74  is selectively adjustable. Alternatively, a thumb screw  87  can be used, as shown in  FIGS. 4-6  for selectively turning and adjusting the spring force by hand. 
         [0036]    Similar to the embodiment using a load cell  54  described hereinabove, the cylindrical shell  61  is secured by welding, fasteners or other suitable means between the lower plate  12  and upper plate  14 . Cylindrical shell  61  is preferably welded to the lower plate  12  as shown with its longitudinal axis being parallel with the upper plate  14  linear direction of travel as indicated by arrow  16 , and with its terminal end  64  adjacent the upper plate back edge  14 B. The terminal end  64  is spaced from the upper plate back edge  14 B a distance which is less than the upper plate travel distance described hereinabove, and with the plunger terminal end  80  abutting the back edge  14 B. 
         [0037]    The embodiment of  FIGS. 4-12  is similarly used by a hitter by placing his/her foot on the upper plate  14  and performing the customary bat swing mechanics. In this embodiment, the hitter&#39;s leg drive/force (ground force) causes the upper plate  14  to be forced against the plunger  76 . When a sufficient leg drive/force F is exerted to overcome the spring force, plunger  76  axially retracts into the cylindrical shell  61  and the upper plate  14  slidingly moves in the direction of arrow  16  until its back edge  14 B abuts/hits the shell terminal end  64 . The back edge  14 B hitting the shell terminal end  64  generates an audible sound output which is transmitted through the lower and upper plates  12 ,  14  and which thereby notifies the hitter that the spring force has been overcome. As should now be appreciated, the spring force can be calibrated so that, depending on the axial location of the screw  86 ,  87  the hitter will know by apparatus  10  generating such an audible sound output, the value of the drive force required to overcome the spring force and generate the audible sound output. Accordingly, the apparatus  10  can thereby be used as needed or desired for training and improving the hitter&#39;s leg drive (Ground Force). 
         [0038]    While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles.