Ball joint center locating method using data from attached inertial measurement unit

• US 9,955,915 B2
• Filed: 08/29/2013
• Issued: 05/01/2018
• Est. Priority Date: 08/30/2012
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Perkins, Noel, McGinnis, Ryan
• Primary Examiner(s): DO, AN H
• Application Number:
  US14/423,852
• Publication Number:
  US 20150223753A1
• Time in Patent Office: 1,706 Days
• Field of Search: 702127, 702141, 702142, 702145, 702151, 702155, 600302, 600595
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/0223 Magnetic field sensors
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/1112 Global tracking of patients, e.g. by using GPS
• CPC Class Codes: A61B 5/1121 Determining geometric values, e.g. centre of rotation or angular range of movement
• CPC Class Codes: A61B 5/4851 Prosthesis assessment or monitoring
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61F 2/30 Joints
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2250/0002 for data transfer
• CPC Class Codes: A61F 5/0113 Drop-foot appliances
• CPC Class Codes: G01B 21/04 by measuring coordinates of points
• CPC Class Codes: G01M 13/04 Bearings

Abstract

A method for calculating the location of the center-of-rotation of a joint with an attached member. The method employs an inertial measurement unit (IMU) having an angular rate gyro and an accelerometer and coupling the inertial measurement unit to the member for detection of movement of the member. The inertial measurement unit outputs data representative of angular velocity and acceleration of the member mounted IMU in response to movement of the joint. The method further comprising analyzing the angular rate and acceleration data to determine the center-of-rotation of the joint.

Claims

1. A method for calculating the location of the center-of-rotation of a joint of a member, said method comprising:

providing an inertial measurement unit having an angular rate gyro and an accelerometer;

fixedly coupling said inertial measurement unit to the member for movement therewith;

outputting data from said inertial measurement unit in response to movement about the joint, said data being representative of angular velocity and acceleration of the member;

calculating a center-of-rotation location of the joint based directly on said angular velocity data and said acceleration data without need to integrate said acceleration data; and

outputting said center-of-rotation location.

2. The method according to claim 1 wherein said outputting data from said inertial measurement unit in response to movement about the joint comprises outputting data from said inertial measurement unit in response to movement about the joint via a wireless module.

3. The method according to claim 2 wherein said wireless module is a Wi-Fi module.

4. The method according to claim 2 wherein said wireless module is a Bluetooth module.

5. The method according to claim 1 wherein said outputting data from said inertial measurement unit in response to movement about the joint comprises outputting data from said inertial measurement unit in response to movement about the joint via a wired module.

6. The method according to claim 1 wherein said providing an inertial measurement unit comprises providing an inertial measurement unit having a digital tri-axial angular rate gyro and accelerometer.

7. The method according to claim 1 wherein said providing an inertial measurement unit comprises providing an inertial measurement unit and a magnetometer.

8. The method according to claim 1 wherein said providing an inertial measurement unit comprises providing an inertial measurement unit and a global positioning system (GPS) sensor.

9. The method according to claim 1 wherein said outputting data from said inertial measurement unit in response to movement about the joint comprises outputting data from said inertial measurement unit to a memory device in response to movement about the joint.

10. The method according to claim 1, further comprising:

calibrating said inertial measurement unit prior to said outputting data from said inertial measurement unit in response to movement about the joint.

11. The method according to claim 1 wherein said calculating a center-of-rotation location of the joint based directly on said angular velocity data and said acceleration data comprises calculating a center-of-rotation location of the joint based directly on said angular velocity data and said acceleration data and an associated biasing value, said associated biasing value being predetermined to accommodate environmental variations.

12. A method for computing the location of the center-of-rotation of a joint of a member, said method comprising:

fixedly coupling an inertial measurement unit having an angular rate gyro and an accelerometer to the member for movement therewith;

outputting data from said inertial measurement unit representative of angular velocity and acceleration of the member in response to movement about the joint;

computing a center-of-rotation location of the joint based directly on said angular velocity data and said acceleration data without need to integrate said acceleration data; and

outputting said center-of-rotation location.

13. The method according to claim 12 wherein said outputting data from said inertial measurement unit comprises outputting data from said inertial measurement unit via a wireless module.

14. The method according to claim 13 wherein said wireless module is a Wi-Fi module.

15. The method according to claim 12 wherein said fixedly coupling an inertial measurement unit having an angular rate gyro and an accelerometer to the member for movement therewith comprises fixedly coupling an inertial measurement unit having a digital tri-axial angular rate gyro and accelerometer.

16. The method according to claim 12 wherein said outputting data from said inertial measurement unit representative of angular velocity and acceleration of the member in response to movement about the joint comprises outputting data from said inertial measurement unit representative of angular velocity and acceleration of the member to a flash memory device operably coupled to said inertial measurement unit in response to movement about the joint.

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

calibrating said inertial measurement unit prior to said outputting data from said inertial measurement unit representative of angular velocity and acceleration of the member in response to movement about the joint.

18. The method according to claim 12 wherein said computing a center-of-rotation location of the joint based directly on said angular velocity data and said acceleration data without need to integrate said acceleration data comprises computing a center-of-rotation location of the joint based directly on said angular velocity data and said acceleration data and an associated biasing value, said associated biasing value being predetermined to negate environmental variations.

19. A method for displaying the location of the center-of-rotation of a joint of a limb, said method comprising:

fixedly coupling an inertial measurement unit having an angular rate gyro and an accelerometer to the limb for movement therewith;

outputting data from said inertial measurement unit representative of angular velocity and acceleration of the limb in response to movement about the joint;

computing a center-of-rotation location of the joint based directly on said angular velocity data and said acceleration data via a processor according to a predetermined algorithm without need to integrate said acceleration data, said predetermined algorithm being stored in said processor on a non-transitory media; and

outputting said center-of-rotation location via a display device.