Ball spin rate measurement system and method

Abstract

A system and method wherein ball spin rate and axis orientation are determined according to an electronic circuit that includes a magnetometer spin sensor module and, in the alternative, an electronic circuit that includes a spin sensor module with a plurality of accelerometers.

We claim: 
     
         1 . A system for determining a spin rate and spin axis orientation of a body in motion, said system comprising:
 an electronics circuit that is located in said body, wherein said electronics circuit collects and processes data defining a reference frame of said body and data defining a global reference frame, said electronics circuit including;
 an inertial measurement unit that generates IMU data in accordance with the motion of said body; 
 a spin sensor module that generates spin sensor data in accordance with rotation of said body relative to a reference frame; 
 one or more microcontrollers that manage and execute data acquisition, power management, and communication processes associated with the IMU data and the spin sensor module data; 
 a data storage module for storing data from said spin sensor module or said at least one microcontroller or at least one IMU; 
 a wireless communication module that is in communication with a processing device and that sends said spin sensor data or data from said at least one microcontroller, or data from said at least one IMU; 
 a battery that supplies electrical power for said at least one microcontroller and said wireless communication module; and 
   a processing device that communicates with said wireless communication module, said processing device processing data from said electronics circuit to display the spin rate of said body,
 wherein said electronics circuit alone or said processing device alone or said electronics circuit in combination with said processing device determine the spin rate of said body, and 
 wherein the spin rate of said body is determined from said spin sensor data that is segmented according to said IMU data, and 
 wherein said electronics circuit determines selected events of the motion of said body according to said IMU data and wherein said spin sensor data is segmented according to said IMU data. 
   
     
     
         2 . The system of  claim 1  wherein said electronics circuit determines the spin rate of said body. 
     
     
         3 . The system of  claim 1  wherein said processing device determines the spin rate of said body. 
     
     
         4 . The system of  claim 1  wherein the spin sensor module contains one or more magnetometers each with one or more axes of measurement. 
     
     
         5 . The system of  claim 1  wherein the spin sensor module contains two or more accelerometers, each with one or more axes of measurement. 
     
     
         6 . The system of  claim 1  wherein the spin sensor module contains a combination of one or more or magnetometers and one or more accelerometers. 
     
     
         7 . The system of  claim 1  wherein the spin sensor module, microcontroller, or remote processor, or a combination thereof determines spin rate of said body by analyzing frequency of data from one or more axes of magnetometers. 
     
     
         8 . The system of  claim 1  wherein spin sensor module, microcontroller, or remote processor determines spin rate of said body by analyzing the centripetal accelerations measured by multiple accelerometers. 
     
     
         9 . The system of  claim 1  wherein the spin sensor module, microcontroller, or remote processor determines spin direction of said body in the global reference frame or the field reference frame by transforming spin direction from the sensor frame using a rotation matrix calculated from gyroscope data. 
     
     
         10 . The system of  claim 1  wherein the spin sensor module, microcontroller, or remote processor determines spin direction of said body in the sensor reference frame using multiple measurements from a magnetometer. 
     
     
         11 . The system of  claim 1  wherein the spin sensor module, microcontroller, or remote processor determines spin direction of said body in the sensor reference frame using measurements from at least two accelerometers. 
     
     
         12 . The system of  claim 1  wherein said system reconstructs the motion of said body in 3-dimensional space in accordance with said IMU data. 
     
     
         13 . The system of  claim 1  wherein said selected events correspond to a free flight beginning and a free flight ending. 
     
     
         14 . The system of  claim 13  wherein said spin sensor module includes a magnetometer with three independent magnetometer sensors arranged along orthogonal axes. 
     
     
         15 . The system of  claim 13  wherein each of said independent magnetometer sensors generates respective magnetometer data and wherein said respective magnetometer data is weighted. 
     
     
         16 . The system of  claim 15  wherein the weighted magnetometer data from each independent magnetometer sensor is processed to develop the overall frequency components of spin motion of said body. 
     
     
         17 . The system of  claim 1  wherein said spin sensor module includes more than one 3-axial accelerometer. 
     
     
         18 . The system of  claim 17  wherein data from first and second 3-axial accelerometers represents centripetal acceleration for different locations within said body. 
     
     
         19 . A method for determining a spin rate and spin axis orientation of a body in motion, said method comprising the steps of:
 transforming data defining a reference frame of said body to global frame data that defines a global reference frame, said transforming data step including the sub-steps of:
 collecting data from an inertial measurement unit that generates IMU data in accordance with the motion of said body; 
 collecting data from a spin senor module in accordance with rotation of said body relative to said reference frame; 
 computing spin rate and spin axis information in terms of the body reference frame and the global reference frame; 
 managing and executing acquisition of said IMU data and spin sensor data, computations based on said IMU data and said spin sensor data, and power and communication processes that are associated with said IMU data and said spin sensor data; 
   storing said spin sensor data, or spin rate and spin axis computations, or computed spin rate and spin axis information;
 communicating with a processing device such that spin sensor data, or computed spin sensor data based on said IMU data and said spin sensor data, or data from said at least one IMU is transmitted; 
   communicating processing data to display the spin rate of said body, wherein the spin rate of said body is determined from said spin sensor data that is segmented according to said IMU data, and determining selected events of the motion of said body according to said IMU data such that said method determines body motion according to said IMU data.   
     
     
         20 . The method of  claim 19  wherein the spin sensor module contains a combination of one or more or magnetometers and one or more accelerometers. 
     
     
         21 . The method of  claim 19  wherein the spin rate of said body is determined by analyzing frequency of data from one or more axes of magnetometers. 
     
     
         22 . The method of  claim 19  the spin rate of said body is determined by analyzing the centripetal accelerations measured by multiple accelerometers. 
     
     
         23 . The method of  claim 19  wherein the spin direction of said body in the global reference frame or in the field reference frame is determined by transforming spin direction from the sensor frame using a rotation matrix calculated from gyroscope data. 
     
     
         24 . The method of  claim 19  wherein the spin direction of said body in the sensor reference frame is determined using multiple measurements of a magnetometer. 
     
     
         25 . The method of  claim 19  wherein the spin direction of said body in the sensor reference frame is determined using measurements from at least two accelerometers.