Abstract:
A practice dummy comprising a remotely controlled, self-propelled base unit supporting a detachable upper body enables athletes to practice football skills against a dummy that can simulate the speed and mobility of a human player.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to practice dummies used to teach football skills to athletes and, more particularly, to a mobile, remotely controlled practice dummy particularly useful for teaching and practicing skills to be employed with mobile opponents. 
     Practice dummies are widely used to teach tackling and blocking techniques and skills to football players. Practice dummies enable players to learn and practice proper technique while reducing bodily wear and tear and the potential for injury that accompanies live tackling and blocking drills with other players. Practice dummies typically comprise a simple padded structure which may be either handheld, freestanding or attached to a sled. The practice dummy is usually located in front of the player to provide a target for practicing blocking and tackling techniques. Sled mounted and standalone dummies provide resistance to the tackler and blocker simulating the resistance encountered in tackling and blocking a human player but provide only a static target. Dummies held by members of the coaching staff can be moved but movement is limited because the holder of the dummy typically must be stationary to resist the impact of the tackler or blocker and to avoid injury when the dummy is impacted. While practice dummies are useful for teaching basic blocking and tackling techniques, opposing players are not static objects and live drills with other players are typically required to teach techniques useful when the tackler or blocker is opposed by a human player who is moving while initiating or evading contact. 
     What is desired, therefore, is a practice dummy sufficiently mobile to simulate a human player. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially cutaway perspective of an exemplary mobile practice dummy. 
         FIG. 2  is a bottom view of a cover portion of the exemplary mobile practice dummy of  FIG. 1 . 
         FIG. 3  is a side elevation view of a propulsion unit for the exemplary mobile practice dummy of  FIG. 1 . 
         FIG. 4  is a side elevation view of a mobile base unit for the exemplary mobile practice dummy of  FIG. 1 . 
         FIG. 5  is a plan view of the propulsion unit of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring in detail to the drawings where similar parts are identified by like reference numerals, and, more particularly to  FIG. 1 , the mobile practice dummy  20  comprises generally an upper body  22  and a remotely controllable, self-propelled base unit  24 . The upper body  22  comprises a pliant mass intended to simulate the body of an opposing player. The upper body preferably comprises a compressible material such as a plastic foam covered with an abrasion resistant outer shell such as a vinyl covering and may have a mass intended to simulate the mass of an opposing player. The upper body may be any shape including the shape of a human torso but commonly available practice dummies have a generally frustoconical shape as illustrated in  FIG. 1 . 
     Referring also to  FIGS. 2, 3, 4 and 5 , the base unit  24  is self-propelled and remotely controllable and comprises generally a propulsion unit  23  and a cover  25 . The propulsion unit  23  comprises generally a chassis  43  supported by a plurality of ground engaging elements, for examples, wheels  40 ,  42  or caterpillar treads. The chassis comprises generally a plurality of longitudinal plates  44  spaced apart by and secured to each other by a plurality of lateral members  46 . 
     The wheels  40 ,  42  are mounted on axles  52 ,  54  which rotate in bearings  56  that are secured to longitudinal chassis plates  44 . Batteries  60 , secured in the chassis, provide the energy to operate the self-propelled base unit. The exemplary base unit  24  is propelled and steered by two powered wheels  40 , each driven by a respective motor  62 ,  64 . Power is transferred to the respective wheel from its motor by a transmission comprising a gear set including a pinion  66  attached to the motor shaft and a driven gear  68  which rotates a jackshaft  70  rotatably supported in the chassis. A first pulley  72  attached to the jackshaft  70  is coupled by a drive belt  76  to a second pulley  74  which is drivingly connected to the respective powered wheel. The speed and direction of rotation of each motor  62 ,  64  are separately controllable by a respective electronic speed controller  78 ,  80 . The electronic speed controllers  78 ,  80  respond to signals from at least one receiver  82  of electromagnetic signals by applying variable width electrical pulses to the respective motors. The motor responds to the pulses by rotating at substantially the same speed as it would if it was excited by a continuous voltage equal to the time weighted average voltage of the series of pulses. Although signals in another portion of the electromagnetic spectrum, such as infrared light, might be used to control the practice dummy, the receiver  82  is typically a radio frequency receiver receiving signals from a remote radio frequency transmitter  84  which is typically operated by a member of the coaching staff. The operator is able to remotely control the speed and direction of rotation of the individual motors and thereby the speed and direction of the mobile practice dummy to simulate the actions of a human player. 
     A resilient bumper assembly  47  substantially encircles the chassis  43  of the propulsion unit. The bumper assembly preferably comprises a resilient outer bumper band  48  that substantially encircles the chassis and resilient supporting bumper bands  49 ,  50 ,  51  which are affixed to respective longitudinal and lateral members  44 ,  46  defining the perimeter of the chassis. The bumper bands which preferably comprise a resilient plastic, such as an ultra-high molecular weight (UHMW) plastic, resiliently deform when the propulsion unit comes in contact with another object, such as a player, to protect the propulsion unit and the other object. 
     The cover  25  is generally cylindrical in shape and preferably comprises resilient plastic foam covered with an abrasion resistant outer shell, such as vinyl. The cover includes a portion, in the underside of the cover, defining a cavity  26  that is arranged to fit over the propulsion unit and an upper interface surface  33  to engage and support the upper body  22  when it is installed on the base unit  24 . The cover is supported by the propulsion unit and the cavity  26  includes a base surface  28  and a side wall  30  which is arranged to encircle and engage the outer bumper band  48  to support the cover and aid in restraining lateral displacement of the cover and the upper body when the speed and direction of the base unit changes. The cover  25  is detachably restrained to the propulsion unit  24  by a first element  94  and a complementary second element  96  of a hook and loop fastener affixed respectively to the outer bumper band  48  and to the sidewall  30  of the cavity  26  in the cover. The restraint provided by the hook and loop fastener reduces the likelihood of separation of the cover when the speed or direction of the dummy changes or when the dummy is impacted or tipped by a blocker or tackler but allows removal the cover for access to the propulsion unit. The side wall  30  is the inner surface of a skirt portion  32  of the cover  25  which encircles the base unit. When a tackler or blocker engages the upper body  22  it is possible that the player will make contact with the base unit as well. The resilient skirt  32  prevents direct contact with the bumper of the propulsion unit and reduces the likelihood that the blocker or tackler will make contact with more rigid elements of the propulsion unit. 
     A significant portion of the practice dummy&#39;s weight is represented by the base unit  24  and the low center of mass of the practice dummy enables rapid direction and speed changes without tipping, simulating the speed and mobility of a human player. The inventor realized that the upper body could tip or slide and become detached from the mobile base unit during rapid maneuvering. In addition, when a tackler or blocker makes contact with the upper body of the practice dummy, the force of the contact will tend to overturn the practice dummy and, if the base unit remained attached to the upper body and tipped, with the upper body the tackler or blocker could fall on the upturned base unit. To reduce the likelihood of contact between a player and the base unit and to retain the upper body during rapid maneuvering, the inventor arranged the upper body  22  to be supported by and restrained to the base unit, but separable from the base unit  24  when the upper body is contacted by another object such as a player tackling or blocking the dummy. Although other mechanisms for increasing the separation resistance of the engaged surfaces of the upper body and the base unit, such as magnets, might be used, the inventor concluded that separability with an appropriate resistance to separation could be achieved by affixing portions of first element  90  and a complementary second element  92  of a hook and loop fastener to respective portions of surfaces, the interface surface  33  of the cover and the supporting surface  35  of the upper body, which engage each other when the upper body is installed on the base unit. 
     The self-propelled, remotely controlled practice dummy can simulate the speed and mobility of a human athlete enabling potential tacklers and blockers to practice appropriate techniques for engaging other players without engaging in live drills with other players. Releasably securing the upper body to the mobile base unit allows the practice dummy to change speed and direction rapidly without separating the upper body from the base unit but allows separation of the upper body and the base unit when a player tackles or blocks the dummy. 
     The detailed description, above, sets forth numerous specific details to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuitry have not been described in detail to avoid obscuring the present invention. 
     All the references cited herein are incorporated by reference. 
     The terms and expressions that have been employed in the foregoing specification are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims that follow.