Ball spin rate measurement system and method
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.
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, said electronics circuit determining a rotation matrix that relates a reference frame of said body to a global reference frame whereby data defining the reference frame of said body is transformed to global frame data that defines said global reference frame, said electronics circuit including;
an inertial measurement unit (IMU) that generates IMU data in accordance with the motion of said body relative to a starting location and an ending location;
a spin sensor module that generates spin sensor data in accordance with rotation of said body relative to a reference frame;
at least one microcontroller that manages and executes acquisition of the IMU data and the spin sensor data computations based on the IMU data and the spin sensor data, and power management and communication processes associated with the IMU data and the spin sensor data;
a data storage module for storing data from said spin sensor or said at least one microcontroller;
a wireless communication module that receives instruction data from a remote device and that sends said spin sensor data or data from said at least one microcontroller to a computing device;
a battery that supplies electrical power for said 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 reconstructed from said spin sensor data that is segmented according to said IMU data and from said global frame 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 such that said system reconstructs a pitch motion 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 said system reconstructs the motion of said body in 3-dimensional space in accordance with said IMU data.
5. The system of claim 1 wherein said selected events correspond to a start position and a stop position.
6. The system of claim 1 wherein said spin sensor module includes more than one 3-axial accelerometer.
7. The system of claim 6 wherein data from first and second 3-axial accelerometers represents centripetal acceleration for different locations within said body.
8. The system of claim 1 wherein said spin sensor module includes a magnetometer with three independent magnetometer sensors arranged along orthogonal axes.
9. The system of claim 8 wherein each of said independent magnetometer sensors generates respective magnetometer data and wherein said respective magnetometer data is weighted.
10. The system of claim 9 wherein the weighted magnetometer data from each independent magnetometer sensor is processed to develop the overall frequency components of spin motion of said body.