Abstract:
A sports ball position reckoning system, comprising instrumentation in a sports ball that allows one or more players to be electronically located on a playing field or court each time a goal attempt is made. The instrumentation is configured to fit through the opening of an inflation port of the ball when the fill valve is removed. The system works in conjunction with a performance monitor system that detects ball interactions with a goal and is used to trigger the system to analyze the ball flight path just prior to the goal interaction. Player position is ascertained through the localization of the initial position of the ball&#39;s flight path. For multiple players, each player is pre-assigned a uniquely marked ball. The identity of the player who executed the attempt is determined through the player&#39;s association with the ball that executed the flight path towards the goal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 62/353,120, filed Jun. 22, 2016. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates generally to automated systems and method for measuring, recording, recalling and displaying results from attempted shooting at a goal on a sports playing field or court for one or more players. More specifically, the present invention relates to systems and methods that utilize wireless transmitters and receivers in addition to electronic sensors to locate and identify sports balls and players on a sports playing field or court and collect shooting statistics for such players at various locations. 
         [0003]    The present invention relates to a sports game performance tracking system that utilizes an instrumented (active electronic or passive RF-reflective) sports ball, a performance monitor on or in the vicinity of the goal and one or more antennae placed around a court or playing field to electronically localize shooters (players) and determine the location where a shot was taken and whether the shot resulted in a goal. Data is recorded for the purpose of monitoring, archiving and subsequent review. 
         [0004]    In sports games, such as basketball, monitoring a player&#39;s skill level and improvements in making goals has typically been manually tracked and documented. Skills coaching could only be accomplished if the coach was present during a practice session or game or by viewing a lengthy video recording. A practice session may be drills, exercises, scrimmages, etc. that occur outside of a formal game. Previously described systems have utilized a variety of sensor means to monitor shots taken, goals missed and goals made, however, they have not included an easy-to-use, cost-effective system that automatically locates players on a court, nor are they able to simultaneously monitor a plurality of balls and players on the court. 
         [0005]    When collecting statistics for a sports game such as number of goals and misses when shooting a sports ball, it may be desirable to calculate such statistics at various locations across a court or playing field. By “shot” or shooting,” we mean the propelling of a sports ball towards a goal. For basketball, shooting data is often displayed in a “Shot Chart,” which consists of a graphical picture of a half basketball court with various numbers or colored regions indicating shooting percentages across court locations. Shot Charts constructed from a significant number of shot attempts may be used to discover the areas on a court where one or more players have high success or low success in making a goal. It should be noted that the term “court” as used throughout this document is intended to mean any type and size of sports playing field, rink, pool, arena, court, etc. Shooting statistics for particular court locations during shooting practice drills may be collected without manual intervention by either of two methods: 1) deterministic—instructing a known player to shoot from one or more specified locations prior to starting such statistics collection or 2) reckoning—measuring the player&#39;s or ball&#39;s location on the court while shooting is underway. Ideally, when multiple players are on the court, statistics collection also includes determining the identity of the player that is shooting the ball. The reckoning method has advantages over the deterministic method because 1) it gives players more freedom to take practice shots from whatever positions players desire without prescriptive assignments and 2) it may be used during a game or scrimmage practice in addition to shooting drills. 
         [0006]    A number of methods have been described to locate one or more players and game balls on a court including machine vision (for example U.S. Pat. No. 7,854,669), motion sensing (for example U.S. Pat. No. 8,540,560), radio frequency transmission (www.quupa.com), ultrasonic echolocation, radar, optical (laser or LED) radar, etc. Electronic location of a player on a basketball court in order to collect shooting statistics requires an accuracy of a fraction of a meter; however, in order to electronically detect a goal by localization of a ball, wherein a ball passes through a hoop, the accuracy must be closer to about 5 or 10 cm. For accurate real-time ball tracking, not only does the electronic location technology have to be accurate in three dimensions, but data needs to be collected at a relatively high rate in order to not miss fast events, like the ball passing through the rim and net without touching the rim (a “swish” shot). Thus, the volume of the 3D location data may become large, especially when multiple players and multiple balls are utilized. When used in conjunction with a performance monitoring system, such as the one described in U.S. application Ser. No. 14/662,419, reckoning-based systems may be simplified and have a lower spatial resolution and a lower sampling frequency to obtain the desired results, since the result of a shot (goal or miss) may be determined by the performance monitoring system rather than the ball position reckoning (ball localization) system. In certain circumstances, where only the initial position for a shot is desired, it may be sufficient to collect 2D data in a plane parallel to the court rather than full 3D data, further simplifying data collection, reduction and analysis. 
         [0007]    Previously described methods for locating players on a court require either a complex machine vision system to analyze images of the field or court from multiple perspectives (for example Sportvu—www.stats.com) or require players to wear a transponder on their person (www.quupa.com). These are generally useful systems for continuously tracking players during an entire practice session or game playing period. We propose a way to simplify the determination of one or more players&#39; locations on a court for the sole purpose of locating each player&#39;s position just prior to a shot, thereby allowing the calculation of shooting statistics at various locations on a court. The proposed system would likely not be appropriate to continuously track players, for example during a game; however, it does allow for tracking multiple shooters who are simultaneously on the court. 
       SUMMARY 
       [0008]    The objective of the current invention is to automatically localize (measure the position of) one or more players&#39; shooting position and performance at different locations on a court. It accomplishes this by utilizing one or more instrumented balls that may be electronically located across a court at recorded times (an electronic ball position reckoning system) in conjunction with a sensor system (performance monitoring system) that measures ball/goal interactions as well as the time at which such events occur. In the case of basketball, the term “ball/goal interaction” is intended to mean a ball bouncing off a rim and not passing through, a ball colliding or just glancing off the backboard, a ball going through the rim after bouncing off the rim and/or the backboard or a ball “swishing” through the rim without touching either the backboard or the rim. The term “ball/goal interaction” for other sports games may have analogous meanings. When a ball/goal interaction is detected and the time of such interaction recorded by the performance monitoring system, the data generated by the electronic ball tracking system is analyzed for only relatively recently collected data points in order to locate the origination of a shot. In addition to instrumentation that allows balls to be tracked on a court, the electronic ball position reckoning (ball localization) system within each ball also transmits a unique identifier for that ball, so multiple balls may be simultaneously located. In contrast to other systems, no player-wearable devices are required, as only the location and identity of the ball, not the player, is determined. When multiple players are shooting, each player is assigned to a different ball; thus, as long as players use their assigned ball, ball identity and locations at the start of a shot may be determined and through association, the identity of a particular player and the player&#39;s location at the beginning of a shot are also known. In order to make sure multiple players do not use one another&#39;s ball, the balls are marked on a portion of or over their entire exterior with an easily identifiable marking or badge such as alphanumeric characters, graphical symbols, moniker, textures, or color patches. 
         [0009]    In a preferred embodiment, a ball position reckoning (ball localization) system is a radio-frequency-based (RF) 3D location system such as those sold by Decawave (www.decawave.com) and Quuppa (www.quuppa.com) or an RF radar system such as monopulse systems or those sold by Analog Devices (www.analog.com) or RFbeam Microwave GmbH (www.rfbeam.ch). These systems typically use one or more antennae, transmitter/transponders or locators positioned around a court that pick up RF signals from either a transmitter/transponder or “tag” in or on an object to be tracked or reflected signals from the object. The one or more locators communicate with a remote computational system that uses the collected data to calculate the 3D location of the object being tracked through multilateration from multiple antennae or directly from just individual antennae. By using multiple tags that have a unique identification signal, that is, they each transmit a unique code along with their locating beacon signal, multiple objects may be simultaneously tracked. 
         [0010]    Outfitting a game ball with wireless electronic sensors, tags and other devices is well known in the art (for example U.S. Pat. Nos. 6,287,225, 8,517,870, 9,283,457). The present invention utilizes a game ball that incorporates an RF tag, a microprocessor, an energy source such as an energy-harvesting generator or energy storage system (battery or capacitor), and optionally additional sensors, switches etc. It should be noted that in some embodiments, no sensing elements within the game ball are required in order to track the ball on a court, only an RF transmitter/transponder (tag). To conserve power, the microprocessor and radio transmitter may be put into sleep mode when not in use. A motion detection system (such as a switch that closes or opens a contact in response to vibration or tilt—such as RB-231X2 from C&amp;K Components, Newton, Mass.) may be used to help wake and activate the system. Such switches consume very little or no power to detect when the ball is likely in motion. 
         [0011]    For basketball, once a player releases a ball for a shot, the ball traces a ballistic parabolic arc within a vertical plane until it impacts an object such as the basketball rim, backboard, floor, another player, etc. In certain embodiments, the present invention utilizes the detection of a ball/goal interaction by the performance monitoring system to trigger the measurement of the ball&#39;s path including the initial ball position in the ballistic arc. By locating the position where the arc was initiated, the location of the player on the court may be inferred without the need for extraneous wearables on the player. Thus, the present invention is simple in that it only requires the player to pick up and use an instrumented (electronic or passive RF-reflective) ball to track the player&#39;s shooting locations on the court rather than donning a specialized device. 
         [0012]    In another embodiment, the start of the ballistic flight of the ball may be calculated in two dimensions rather than in three dimensions by projecting all of the 3D points found by the ball localization system into a horizontal plane. Since during the ball&#39;s flight there are no horizontal accelerations (only the vertical acceleration of gravity), the ball has a constant velocity in the horizontal plane during its flight. Even if there is some air resistance or other aerodynamic effects that slightly alter the ball&#39;s path from a pure parabolic, in practice the ball velocity in the horizontal plane is close to a constant. Thus, the initial location where the ball starts its ballistic path is the first point whose horizontal speed is approximately the same as the horizontal speed of the other points in the path. Although Doppler-radar-based 3D reckoning systems measure speed, most others only measure position, not speed. For those systems, speed must be calculated by subtracting the position of two adjacent points and dividing by the difference in time that the points were measured. 
         [0013]    The systems in the prior art that describe electronics within various balls require that balls be manufactured with the components sealed within the ball. Thus, users must purchase specialized balls that include the sealed components within the ball exclusively from the manufacturers of the specialized balls. This approach limits the market for such products, as many teams and individual athletes have a particular ball brand with which they exclusively play. This may be either dictated by rules of an affiliated organization or by personal or coach preference. It would be highly advantageous if the balls to which players are accustomed could either be instrumented with either the electronics to perform the desired function or an RF-reflective system. In the current invention, we describe a method for instrumenting any inflatable ball, old or new, with the electronics and/or reflective properties necessary to perform the ball tracking and identification functions. 
         [0014]    Other details of the X are set forth in the following detailed description and the accompanying drawing wherein like reference numerals depict like elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  shows an embodiment of an exemplary performance monitoring and ball location reckoning system with a plurality of players and balls on a half basketball court. 
           [0016]      FIG. 2  shows a cross section of an exemplary construction of a portion of a sports ball in the vicinity of the inflation valve. 
           [0017]      FIG. 3  shows a cross section of an exemplary embodiment of a low-profile electronics package that fits through the valve hole in a sports ball. 
           [0018]      FIG. 4  shows a cross section of an exemplary embodiment of a low-profile electronics package fitted in the valve hole in a sports ball with an inflation needle inserted. 
           [0019]      FIG. 5  shows the combined exterior and cross section of a sports ball fitted with an exemplary embodiment of a low-profile electronics package. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Many sports balls are air-inflatable and constructed with multiple layers. Generally, these balls consist of an outside layer  3  that is designed to directly interact with a player and promote good grip, bounce, spin, wear, etc. There is also typically an impenetrable inside layer which serves as the bladder  2  for containing the pressurized air. There may optionally be additional layers to increase strength, stiffness, etc. of the inflated ball. 
         [0021]    The bladders  2  of inflatable sports balls  1  typically have a thicker valve retention section  4  that is shaped to capture a valve  7 , which is used for inflating and deflating the ball with the insertion of a needle  20  through a hole  8  in the valve  7 . Valves  7  in sports balls  1  fail fairly frequently and may create a “leaky” ball that loses pressure; thus, standard valves  7  are used throughout the industry and replacement valves are readily available (Tachikara USA, Inc., Sparks, Nev., USA). The standard valve  7  is comprised of a top portion that includes a hole  8  for insertion of an inflation needle  20 , a disc-shaped center portion that both seals the interface between the valve  7  and bladder  2  so air will not escape and locates the valve  7  in the valve retention section  4  and a cylindrical bottom section with a hemispherical end, which closes and seals itself after an inflation needle  20  is removed. 
         [0022]    In one embodiment of the current invention, a low-profile electronics package  5  is attached to a valve  7  and inserted into the valve retention section  4  of a ball  1 . The recent advent of miniaturized electronics and RF components have enabled this “aftermarket” instrumentation of a ball, wherein the old valve is removed from any inflatable ball that utilizes a standard valve and then replaced with the new valve that incorporates the low-profile electronics package  5  or reflective system. Other prior-art descriptions of instrumented balls require that balls be manufactured with instrumentation within the bladder  2  and do not contemplate instrumentation insertion into a conventional ball. By combining the universality of standard valve design in inflatable balls throughout the industry with the miniaturization of an RF tag and other electronic components, the present invention is unique as it may be used in almost any inflatable sports ball that has ever been manufactured. Thus, players that have a strong preference for a particular brand, model or individual ball may still get the benefits of an instrumented ball. An additional advantage to the low-profile package is that the system may be disassembled and reassembled in order to change batteries. Thus, the life of the product may be much longer than a system that has permanently sealed batteries inside the inflation bladder. 
         [0023]    In one embodiment of the current invention, the electronics package  5  is comprised of a tube  10  which encases the electronics and is attached to the cylindrical bottom section of the valve  7 . It should be understood that although the vessel that encases the electronics is referred to herein as a tube, it may be a vessel of any shape, material and size as long as it will fit thought the valve retention section  4  and attach to the valve  7 . If a potting compound  18  is used to encase the electronics, the tube not be necessary if the potting compound attaches directly to the valve  7 . Within the tube  10 , there is an empty channel  11  to accept the needle valve  20  and allow air coming through the needle valve outlet ports  21  to escape through a hole  12  into the bladder interior, a circuit board  14  (which may be rigid or flexible), one or more batteries  13 , generators or supercapacitors, various electronic components  16  and an RF chip antenna  17  (such as model number AH-086M555003 from Taiyo Yuden Co. Ltd., Tokyo, Japan) to transmit and receive RF signals. One or more contact buses  15  that connect multiple batteries to one another may also be present. The entire tube and electronics assembly may be optionally potted with a potting compound  18  to create a solid package that is more resilient to the high accelerations and jerks that are inherent in the use of a sports ball  1 . 
         [0024]    In another embodiment, the ball may be made more reflected to RF transmission by placing a coating or material layer within the ball on the interior of the bladder  2 , interior or exterior of the outer layer  3  or between other layers of the ball. Such coating or layer may be comprised of metal powders or other materials that can enhance RF signal reflectivity. 
         [0025]    In order to instrument a conventional ball with the electronics package  5  or a foldable, corner-cube RF reflector, the entire package  5  must fit through the valve opening in the valve retention section  4 . Similarly a reflective coating spray head must fit through such opening in order to apply the coating to the inside surface of the bladder  2 . Optionally, the opening may be temporarily expanded by using a retractor, similar to a Kolbel retractor (Becton, Dickinson and Company, Franklin Lakes, N.J.) used by surgeons or other similar device for expanding an opening. A typical valve opening is about 6.5 mm in diameter, which may be expanded through stretching an oval to about 12 mm. In addition to the RF chip antenna  17 , the electronics package  5  has a number of electronics components  16 . These may include some or all of the following as well as various other components not listed: a microprocessor or microcontroller, an RF signal generating chip (such as the Decawave DW1000—Dublin, Ireland), an accelerometer, a vibration switch, a tilt switch, an altimeter, a digital compass, voltage regulation, clock signal generation, energy harvesting components, supercapacitors and batteries  13 . All of these components are available in packages that are 6 mm or less in width. So called coin cell batteries are available in a wide variety of sizes, several of which are small enough to fit through the valve opening including the SR64, which is 5.8 mm in diameter and the SR66 which is 6.8 mm in diameter. A variety of other batteries may also be appropriate. Each coin cell is typically about 1.5 volts, so two in series are necessary to supply the voltage for 3 volt DC electronics. Additional batteries in parallel may be added to extend battery life of the system. One configuration of three parallel sets of battery pairs  13  is shown in  FIG. 3  where one end of the batteries  13  is in contact with two different conductors (anode and cathode) on the circuit board  14  and a metal contact strip  15  is used to tie together the other ends of the batteries  13 . Other configurations where the axes of the coin cells  13  are collinear are also possible. 
         [0026]    Because RF transmissions and receptions are only required when the basketball is in use and actively moving, bouncing, spinning, etc., it is possible to use an energy harvesting system in lieu of or in combination with a conventional battery. Energy harvesting systems have commonly been used in “shake” flashlights (for example model DA84170 form Klenck Tools, Canton, Ohio), as well as a number of wireless devices. In these systems, some form of electricity generation (from changing magnetic fields across a conductive coil, piezo crystal strain, etc.) is used to charge an energy storage system (battery or capacitor) for later use. Dribbling, tossing, catching, shooting and bouncing a ball off a goal or backboard can all create sufficient acceleration within the ball to allow an energy harvesting system to charge an energy storage system (capacitor or a rechargeable battery). When no motion is sensed by the motion detection system within the ball after some period of time, the electronics may be put to sleep to conserve power and the frequency of RF transmissions may be curtailed or stopped. When motion is once again detected by the motion detection system, RF transmissions can be re-initiated and if energy harvesting is being used, power may once again be generated from the motion. The energy harvesting system may also be used to detect motion without the use of a separate motion detection system by detecting when it is generating power. 
         [0027]    If the location of the center of mass of the entire electronics package  5  does not correspond to the center of mass of the uninstrumented ball  1 , the ball will be out of balance. In other words, the total center of mass will not be coincident with the center of the spherical ball shape and the ball will spin with a wobble when tossed. To correct this and balance the ball  1 , material  6  may be added inside the bladder at a location that is opposite the valve  7 . This may be accomplished by either gluing a solid object to the bladder  2  or by injecting a curable liquid material through the valve hole and letting it cure on the side of the bladder that is opposite the valve  7 . The material may also be comprised of metal powders or other materials to enhance RF signal reflectivity. To balance the ball, the mass of the material  6  added should equal the mass of the electronics package times the ratio of the distance from the ball center to the electronics package  5  center of mass and the distance from the ball center to the added material  6  center of mass. 
         [0028]    In order for players to readily identify one instrumented ball from another, an easily identifiable, unique mark  9  such as alphanumeric characters, graphical symbols, moniker, textures, or color badges may be added to the ball&#39;s exterior. In a preferred embodiment, each ball  1  used on the same court would have a different color badge  9  attached to its exterior. When the instrumented valve assembly  5  is assembled to the ball  1 , the unique code it transmits through RF to identify itself is known and correlated to the unique exterior mark  9  on the ball. Thus, during use, a remote computational system  30  will know that the say blue-marked ball transmits through RF a particular identification code that is different from say the yellow-marked (or any other) ball. 
         [0029]    When used during a shooting practice session, where say three players are shooting at a single goal, each player&#39;s performance may be individually tracked and recorded. At the beginning of the session, the players must agree on ball assignments and communicate those to the remote computational system  30 . For example, player  1  uses the blue-marked ball, player  2  uses the yellow-marked ball and player  3  uses the red-marked ball. When the system determines that a shot was taken based either from the signal form a performance monitoring system  27  or from the reckoning data from a ball  1 , it can determine the identity of the ball that was shot based on the transmitted RF code of the ball most proximate the goal. If the code corresponding to say the red-marked ball was received, the system knows that the results of that shot should be attributed to player  3 . Similarly, when the system determines that a shot was taken based on the transmitted RF code corresponding to say the blue-marked ball, it knows that the results of that shot should be attributed to player  1 , etc. Although signals from a plurality of balls may be received during a shooting session, only the ball proximate the goal is attributed with the shot. If a plurality of balls are proximate the goal, then additional information such as the ball height above the court or the trajectory of the ball just prior to the shot being registered may give additional information as to which ball the shot should be attributed. The remote computational system  30  collects such shooting statistics for the individual players and records them in a database for later review. 
         [0030]    To monitor the position of one or more balls  1  on a court, the court is instrumented with a plurality of RF antennae  25  that are spaced around its periphery. This may include locations on the floor, on the goal or backboard, on walls, suspended from the ceiling, etc. Although there is some flexibility in where antennae may be located, they should generally be fixed in dispersed stationary locations during the course of play. To avoid mathematical singularities, at least one of three or more antennae should not be collinear and at least one of four or more should not be coplanar. These antennae are in wired or wireless communication with a remote computational device  30 , either directly or relayed through one another. Each antenna may also include a separate microprocessor to control incoming and outgoing signals. The remote computational device  30  may be a smart phone, a tablet computer, a laptop computer, a microprocessor or any other computational device that has sufficient compute power to both communicate with the antennae and compute ball locations from the received antennae signals. The calculation of ball locations may also be performed in whole or part by microprocessors that may be located proximate the antennae. The remote computational device  30  may also be in communication with a database that can store data for later review and editing. Wireless communication amongst the various devices may be through Bluetooth, Wi-Fi, IEEE 802.11, or any other RF, optical or acoustic protocol. The goal  26  is fitted with a performance monitoring system  27  that can detect when a ball/goal interaction has occurred, which places the ball close to the goal  26 . The performance monitoring system  27  is also in wired or wireless communication with the same or a separate remote computational device  30 . 
         [0031]    During a shooting session, the RF antennae  25  are continuously monitoring the position of all balls  1  on the court preferably at a rate between 2 and 40 Hertz and more preferably between 10 and 20 Hertz and sending signals to the remote computational device  30 ; however, most of the data received by the remote computational device does not contribute to determining the location of the player position for a shot and therefore may be ignored. Such data is only relevant when a shot trigger event occurs. A shot trigger event may be the detection of a ball/goal interaction by the performance monitoring system  27  or the calculation of a ball location by the ball location reckoning system that is proximate the goal  26  within some threshold distance. A shot trigger event means that a shot was likely taken by a player and once it occurs, the antennae  25  signal data that were received within a time window prior to the trigger event are analyzed in order to determine the initial location of the shot. If a shot trigger event was generated by the performance monitoring system  27 , the data corresponding to each ball  1  are analyzed by the remote computational device  30  to determine which ball is closest to the goal and likely caused the trigger event. Once determined, the data from the identified ball are analyzed to determine which points lie along a ballistic arc  28 . This may be accomplished by starting with the point just prior to the trigger event and adding each additional point backwards in time until a point no longer fits closely to a ballistic arc  28 . The last point (first point in time) that fits the arc is an approximation of the location of the ball when the shot was initiated. The calculation for how closely a set of points fit the ballistic arc may be performed in 3D space by fitting the points to a parabola or in 2D space by fitting the points to a line. Not only do points have to fit to proscribed curves in Cartesian space, but they must also fit proscribed curves in distance versus time space. This means for points that lie on the arc, calculated vertical distances should be a quadratic function of time and calculated horizontal distance should be a linear function of time. 
         [0032]    It is apparent that there has been provided in accordance with the present invention a basketball performance monitoring system which fully satisfies the objects, means and advantages set forth hereinbefore. While the present invention has been described in the context of specific embodiments thereof, other alternatives, modifications, and variations will become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations as fall within the broad scope of the appended claims.