APPARATUS AND METHOD FOR IDENTIFYING AND ANALYZING THE FREE FLIGHT DYNAMICS OF A BODY

• US 20130073247A1
• Filed: 09/20/2011
• Published: 03/21/2013
• Est. Priority Date: 09/20/2011
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Noel Perkins
• Inventors: King, Kevin, PERKINS, NOEL, Doss, Ryan
• Granted Patent: US 9,140,717 B2
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: A63B 2024/0034 during flight
• CPC Class Codes: A63B 2220/40 Acceleration
• CPC Class Codes: G01C 21/185 for gravity
• CPC Class Codes: G01P 3/44 for measuring angular speed G01P3/56 takes precedence

Abstract

An apparatus for analyzing free flight of a body including an inertial measurement unit having at least one accelerometer continuously measuring three orthogonal axes of acceleration and outputting data representative thereof and a processing unit operably receiving the data and determining three components of an angular velocity of the body during free flight.

Claims

1. An apparatus for analyzing free flight of a body, said apparatus comprising:

an inertial measurement unit having at least one accelerometer continuously measuring three orthogonal axes of acceleration and outputting data representative thereof; and

a processing unit operably receiving said data, said processing unit determining three components of an angular velocity of the body.

2. The apparatus according to claim 1 wherein said processing unit calculates said angular velocity (ω

_y, ω

_y, ω

_z) of the body based on a predetermined acceleration due to gravity and simultaneous solution of the equations

a_x=−

x(ω

_y²+ω

_z²)+yω

_xω

_z+zω

_xω

_z

a_y=−

y(ω

_z²+ω

_x²)+zω

_yω

_z+xω

_yω

_x

a_z=−

z(ω

_x²+ω

_y²)+zω

_zω

_x+yω

_zω

_y

wherein x, y, z is the position of the mass center of the body and a_x, a_y, a_z is said measured three orthogonal axes of acceleration from said inertial measurement unit.

3. The apparatus according to claim 1 wherein said processing unit calculates said angular velocity (ω

_x, ω

_y, ω

_z) of the body based on a predetermined acceleration due to gravity and simultaneous solution of the measured output of the at least one accelerometer ({right arrow over (a)}_measured)

{right arrow over (a)}_measured=[−

I_c<sup>−

1</sup>({right arrow over (ω

)}×

I_c{right arrow over (ω

)})]×

{right arrow over (r)}_p/c+{right arrow over (ω

)}×

({right arrow over (ω

)}×

{right arrow over (r)}_p/c)

wherein I_c is the inertia tensor about principal axes through the mass center.

4. The apparatus according to claim 1 wherein said processing unit compensates for errors in said data by comparing a calculated acceleration of a mass center of the body to a predetermined acceleration due to gravity.

5. An apparatus for analyzing free flight of a body, said apparatus comprising:

an inertial measurement unit measuring three rigid body degrees of freedom and outputting data representative thereof; and

a processing unit operably receiving said data, said processing unit determining six rigid body degrees of freedom of the body during free flight.

6. The apparatus according to claim 5 wherein said inertial measurement unit comprises at least one single-axis accelerometer.

7. The apparatus according to claim 5 wherein said inertial measurement unit comprises at least one dual-axis accelerometer.

8. The apparatus according to claim 5 wherein said inertial measurement unit comprises at least one three-axis accelerometer.

9. The apparatus according to claim 5 wherein said inertial measurement unit comprises at least one single-axis rate gyro.

10. The apparatus according to claim 5 wherein said inertial measurement unit comprises at least one dual-axis rate gyro.

11. The apparatus according to claim 5 wherein said inertial measurement unit comprises at least one three-axis rate gyro.

12. A method of sports training, said method comprising:

providing a sports device having an inertial measurement unit measuring three rigid body degrees of freedom of said sports device during free flight and outputting data representative thereof; and

a processing unit operably receiving said data, said processing unit determining six rigid body degrees of freedom of said sports device during said free flight.

13. The method according to claim 12, further comprising:

displaying at least one of said six rigid body degrees of freedom to provide feedback to a user.

14. The method according to claim 12, further comprising:

displaying a parameter determined in response to at least one of said six rigid body degrees of freedom to provide feedback to a user.

15. The method according to claim 13 wherein said feedback is used to train said user.

16. The method according to claim 13 wherein said feedback is used to design said sports device.

17. The method according to claim 13 wherein said feedback is used to aid in fitting said sports device for said user.