RACKET SPORT INERTIAL SENSOR MOTION TRACKING AND ANALYSIS

• US 20130053190A1
• Filed: 02/10/2012
• Published: 02/28/2013
• Est. Priority Date: 08/29/2011
• Status: Active Grant

• Current Assignee: icuemotion, LLC
• Original Assignee: icuemotion, LLC
• Inventors: Mettler, Brnice
• Granted Patent: US 8,944,940 B2
• Time in Patent Office: Days
• US Class Current: 473/463
• CPC Class Codes: A63B 2220/13 Relative positions
• CPC Class Codes: A63B 2220/34 Angular speed
• CPC Class Codes: A63B 2220/40 Acceleration
• CPC Class Codes: A63B 2220/62 Time or time measurement used for time reference, time stamp, master time or clock signal
• CPC Class Codes: A63B 2225/15 with identification means that can be read by electronic means
• CPC Class Codes: A63B 2225/50 Wireless data transmission, e.g. by radio transmitters or telemetry
• CPC Class Codes: A63B 24/0003 Analysing the course of a movement or motion sequences during an exercise or trainings sequence, e.g. swing for golf or tennis
• CPC Class Codes: A63B 24/0062 Monitoring athletic performances, e.g. for determining the work of a user on an exercise apparatus, the completed jogging or cycling distance
• CPC Class Codes: A63B 49/00 Stringed rackets, e.g. for tennis strings therefor A63B51/00
• CPC Class Codes: A63B 60/46 Measurement devices associated with golf clubs, bats, rackets or the like for measuring physical parameters relating to sporting activity, e.g. baseball bats with impact indicators or bracelets for measuring the golf swing
• CPC Class Codes: G09B 19/0038 Sports

Abstract

A system for a racket comprises an inertial sensor for coupling to the racket, a processor connected to the inertial sensor, and a memory device connected to the processor. The inertial sensor includes an accelerometer array with three degrees of freedom in acceleration and a gyro array with three degrees of freedom in rotation. The processor is configured to generate stroke profiles describing acceleration and rotation of the racket based on signals from the accelerometer and the gyro arrays, and the memory device is configured to store the stroke profiles.

Claims

1. A system for a racket, the system comprising:

an inertial sensor for coupling to the racket, the inertial sensor comprising an accelerometer array with three degrees of freedom in acceleration and a gyro array with three degrees of freedom in rotation;

a processor connected to the inertial sensor, the processor configured to generate stroke profiles describing acceleration and rotation of the racket based on signals from the accelerometer and the gyro arrays; and

a memory device connected to the processor, the memory device configured to store the stroke profiles.

2. The system of claim 1, wherein the processor is configured to segment the stroke profiles in real time based on interaction impulses identified within the stroke profiles.

3. The system of claim 1, wherein the processor is configured to generate stroke trajectories based on the stroke profiles, the stroke trajectories describing position, velocity and orientation of the racket.

4. The system of claim 3, wherein the inertial sensor comprises a magnetometer and the processor is configured to correct the orientation of the racket based on signals from the magnetometer.

5. The system of claim 3, wherein the processor is configured to determine aerodynamic forces and moments on the racket based on the stroke trajectories.

6. The system of claim 5, wherein the processor is configured to determine grip and interaction forces and moments on the racket based on the stroke trajectories and the aerodynamic forces and moments.

7. The system of claim 1, wherein the inertial sensor and the processor are recessed within a cavity in the racket.

8. The system of claim 7, further comprising a wireless transmitter coupled to the processor within the internal cavity, the wireless transmitter configured to transmit the stroke profiles.

9. The system of claim 7, further comprising a cueing device coupled to the processor for generating real-time feedback based on the stroke profiles.

10. The system of claim 1, further comprising a plurality of tracking markers coupled to the racket, the tracking markers distributed to indicate a centroid of the head and an orientation of the racket.

11. A motion tracking system comprising the system of claim 10 and a motion detector configured to determine the centroid of the head and the orientation of the racket based on positions of the tracking markers.

12. A stroke analysis method comprising:

sensing acceleration of a racket;

sensing angular velocity of the racket;

generating stroke histories based on the acceleration and angular velocity of the racket;

identifying interaction impulses within the stroke histories; and

generating stroke profiles by segmenting the stroke histories based on the interaction impulses.

13. The method of claim 12, further comprising separating the stroke profiles into stroke types based on a number of peaks in the interaction impulses.

14. The method of claim 12, further comprising generating a real-time cue based on the stroke profiles, the real-time cue describing conformance of a stroke profile to a model.

15. The method of claim 12, further comprising converting the stroke profiles into stroke trajectories, the stroke trajectories describing position, velocity and orientation of the racket.

16. The method of claim 15, further comprising separating the stroke profiles into stroke types based on pattern recognition of the stroke trajectories.

17. The method of claim 15, further comprising sensing a magnetic field local to the racket and correcting the orientation of the racket based on the magnetic field.

18. The method of claim 17, further comprising determining aerodynamic forces on the racket based on the stroke trajectories.

19. The method of claim 18, further comprising determining grip forces on the racket based on the stroke trajectories and the aerodynamic forces.

20. The method of claim 19, further comprising determining interaction forces on the racket based on the stroke trajectories the aerodynamic forces and the grip forces, the interaction forces describing momentum transfer to a ball.

21. A motion tracking method comprising:

sensing accelerations and angular velocity of a racket in three dimensions;

generating stroke profiles based on the accelerations and angular velocity of the racket;

segmenting the stroke profiles based on interaction impulses identified therein; and

reconstructing racket trajectories based on the stroke profiles, the racket trajectories describing position and velocity of the racket in the three dimensions and orientation of the racket in two dimensions.

22. The method of claim 21, further comprising separating the stroke profiles into stroke types based on a number of peaks in the interaction impulses.

23. The method of claim 21, further comprising generating a real-time cue based on the stroke profiles, the real-time cue describing conformance of a stroke trajectory to a model.

24. The method of claim 21, further comprising determining aerodynamic forces and moments on the racket in the three dimensions based on the racket trajectories.

25. The method of claim 24, further comprising determining grip and interaction forces on the racket based on the racket trajectories and the aerodynamic forces.