System and method of estimating joint loads using an approach of closed form dynamics

• US 20050209536A1
• Filed: 01/19/2005
• Published: 09/22/2005
• Est. Priority Date: 06/29/2001
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Dariush, Behzad
• Granted Patent: US 7,684,896 B2
• Time in Patent Office: Days
• US Class Current: 600/595
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1038 Measuring plantar pressure during gait
• CPC Class Codes: A61B 5/1121 Determining geometric values, e.g. centre of rotation or angular range of movement
• CPC Class Codes: A61B 5/1122 of movement trajectories
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence

Abstract

A method for estimating joint load at a joint of a segment. The method comprises the steps of receiving kinematic data, determining a modified acceleration using at least the kinematic data, estimating a joint load using at least the modified acceleration; and determining simulated kinematic data for the segment using at least the joint load. The present invention thus addresses the problems with conventional inverse dynamics analysis by providing a forward dynamics solution for estimation of joint loads that is stable, guaranteed to converge, computationally efficient, and does not require acceleration computations. According to one embodiment, a joint load is estimated using an approach of closed form dynamics.

Claims

1. A computer based method for automatically estimating a joint load at a joint of a segment, comprising the steps of:

receiving kinematic data representing a serial chain system;

determining a modified acceleration using at least said kinematic data;

estimating the joint load using at least said modified acceleration, wherein said step of estimating the joint load uses an approach of closed form dynamics; and

determining simulated kinematic data for the segment using at least the joint load.

2. The method of claim 1, wherein said kinematic data represents measured values.

3. The method of claim 1, wherein said kinematic data includes at least one of positional kinematic data or velocity kinematic data.

4. The method of claim 1, wherein said step of determining said modified acceleration includes:

determining an error value representing a difference between previously simulated kinematic data simulated at a previous time and said kinematic data; and

applying a feedback gain to said error value.

5. The method of claim 4, wherein said kinematic data comprises at least positional kinematic data, said previously simulated kinematic data comprises at least previously simulated positional data, and said error value comprises a positional tracking error representing a difference between said previously simulated positional data and said positional kinematic data.

6. The method of claim 4, wherein said kinematic data comprises at least velocity kinematic data, said previously simulated kinematic data comprises at least previously simulated velocity data, and said error value comprises a velocity tracking error representing a difference between said previously simulated velocity data and said velocity kinematic data.

7. The method of claim 4, wherein said feedback gain comprises at least one of a positional feedback gain or a velocity feedback gain.

8. The method of claim 1, wherein said serial chain system is one of an open kinematic chain or a closed kinematic chain.

9. The method of claim 1, wherein said step of determining said simulated kinematic data for the segment further comprises:

determining an induced acceleration for the segment; and

determining said simulated kinematic data for the segment by integration of said induced acceleration.

10. The method of claim 1, further comprising the step of obtaining at least one of a reaction force and a moment acting at one or more joints.

11. The method of claim 10, wherein said step of estimating the joint load uses said at least one of said reaction force and said moment in addition to said modified acceleration.

12. The method of claim 10, wherein said step of determining said simulated kinematic data uses said at least one of said reaction force and said moment in addition to the joint load.

13. The method of claim 10, wherein said at least one of said reaction force and said moment is determined by at least one of measurement or estimation.

14. The method of claim 1, wherein said serial chain system is one of a two-dimensional system or a three-dimensional system.

15. A system for automatically estimating a joint load at a joint of a segment, comprising:

means for receiving kinematic data representing a serial chain system;

first determining means for determining a modified acceleration using at least said kinematic data;

means for estimating the joint load using at least said modified acceleration wherein said means for estimating the joint load uses an approach of closed form dynamics; and

second determining means for determining simulated kinematic data for the segment using at least the joint load.

16. The system of claim 15, wherein said first determining means for determining said modified acceleration further includes:

third determining means for determining an error value representing a difference between previously simulated kinematic data simulated at a previous time and said kinematic data; and

means for applying a feedback gain to said error value.

17. The system of claim 15, wherein said second determining means for determining said simulated kinematic data for the segment further includes:

third determining means for determining an induced acceleration for the segment; and

fourth determining means for determining said simulated kinematic data for the segment by integration of said induced acceleration.

18. The system of claim 15, wherein said serial chain system is one of a two-dimensional system or a three-dimensional system.