Identification and implementation of locomotion modes using surface electromyography

• US 8,828,093 B1
• Filed: 04/07/2009
• Issued: 09/09/2014
• Est. Priority Date: 04/15/2008
• Status: Active Grant

• Current Assignee: Rehabilitation Institute of Chicago (Tenet Healthcare Corporation)
• Original Assignee: Rehabilitation Institute of Chicago (Tenet Healthcare Corporation)
• Inventors: Kuiken, Todd, Huang, He
• Primary Examiner(s): Isabella, David
• Assistant Examiner(s): Woznicki, Jacqueline
• Application Number:
  US12/419,521
• Time in Patent Office: 1,981 Days
• Field of Search: 623/25
• US Class Current: 623/25
• CPC Class Codes: A61F 2/60 Artificial legs or feet or parts thereof
• CPC Class Codes: A61F 2/72 Bioelectric control, e.g. myoelectric
• CPC Class Codes: A61F 2/80 Sockets, e.g. of suction type
• CPC Class Codes: A61F 2002/607 Lower legs
• CPC Class Codes: A61F 2002/701 operated by electrically controlled means, e.g. solenoids or torque motors
• CPC Class Codes: A61F 2002/704 computer-controlled, e.g. robotic control
• CPC Class Codes: A61F 2002/7615 Measuring means for implanting artificial joints A61F2/4657
• CPC Class Codes: A61F 2002/762 for measuring dimensions, e.g. a distance
• CPC Class Codes: A61F 2002/7625 for measuring angular position
• CPC Class Codes: A61F 2002/7635 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2002/764 for measuring acceleration
• CPC Class Codes: A61F 2002/7645 for measuring torque, e.g. hinge or turning moment, moment of force

Abstract

Apparatus and methods are provided for determining a locomotion mode that can be provided to a controller of a lower prosthesis limb in order to accurately control the prosthesis. One or more prosthesis sensors are provided that break a gait cycle down into a plurality of gait phases. EMG sensors provide signals to a processor that directs them to a gait phase specific classifier that is used to determine a particular locomotion mode for the wearer. With the locomotion mode accurately known, the prosthetic device can be accurately controlled.

Claims

1. A lower-limb prosthesis operating assembly, comprising:

(a) one or more prosthesis sensors, each one for measuring one or more prosthesis characteristics and for providing signals corresponding to values of the prosthesis characteristics at a prosthesis sensor output;

(b) a plurality of EMG sensors for receiving non-stationary EMG signals;

(c) a processor comprising;

(i) one or more processor inputs, configured to be connected to one or more of (1) a prosthesis sensor output, for receiving one or more prosthesis characteristic value signals, and (2) an EMG sensor, for receiving EMG signals;

(ii) a gait phase means for determining a gait phase, a gait phase information relating to the gait phase, based on the prosthesis characteristic values; and

(iii) a means for determining a locomotion mode based on the EMG signals received during a phase window of a gait cycle and the gait phase information; and

(d) a locomotion mode output that provides a signal corresponding to the determined locomotion mode at the determined gait phase to a prosthesis controller input.

2. The assembly according to claim 1, the EMG sensor signals are digitized prior to receipt by the one or more inputs of the processor.

3. The assembly according to claim 1, further comprising:

a memory for storing the determined locomotion mode.

4. The assembly according to claim 1, further comprising:

a memory for storing the determined gait phase information.

5. The assembly according to claim 1, wherein the gait phase means comprises a gait phase algorithm comprising program instructions that execute on the processor.

6. The assembly according to claim 1, wherein the means for determining a locomotion mode comprises a locomotion mode algorithm comprising program instructions that execute on the processor.

7. The assembly according to claim 1, wherein the locomotion mode comprises level walking, obstacle, stair ascent, stair descent, ipsi-turn, contra-turn, and standing.

8. The assembly according to claim 1, wherein the gait phases comprise a post-heel-contact phase, a pre-toe-off phase, a post-toe-off phase, and a pre-heel-contact phase.

9. The assembly according to claim 1, wherein the phase window is between about 120 ms and 200 ms in duration.

10. The assembly according to claim 1, wherein the prosthesis sensors include a heel sensor and a toe sensor and the gait phase is determined based on prosthesis characteristic value signals of these sensors.

11. The assembly according to claim 1, wherein the prosthesis sensors include a three-degree-of-freedom load cell and the gait phase is determined based on the output of this load cell.

12. The assembly according to claim 1, wherein the processor is a floating point processor.

13. The assembly according to claim 1, wherein the prosthesis characteristics are selected from the group consisting of position, angle, velocity, acceleration, torque, and linear vector forces.

14. The assembly according to claim 1, wherein the means for determining the locomotion mode is configured as a pattern recognition algorithm.

15. The assembly according to claim 14, wherein the pattern recognition algorithm is a linear discriminant analysis-based classifier.

16. The assembly according to claim 14, wherein a classifier for the pattern recognition algorithm is selected from the group consisting of:

a Gaussian mixed model, a multilayer perceptron network, a hidden Markov model, an artificial neural network, and a fuzzy logic classifier.

17. The assembly according to claim 1, wherein the EMG sensors are placed for measuring a plurality of signals from muscles selected from the group consisting of:

gluteus maximus;

gluteus medius;

sartorius;

rectus femoris;

vastus lateralis;

vastus medialis;

gracilis;

biceps femoris long head;

semitendinosus;

biceps femoris short head;

tibialis anterior;

peroneus longus;

gastrocnemius lateral head;

gastrocnemius medial head;

soleus; and

extensor digitorum brevis.

18. The assembly according to claim 1, wherein the EMG sensors are polarizable stainless steel domes embedded into a socket or liner of a prosthesis.

19. The assembly according to claim 1, further comprising a communication module for communication between the processor and a computer output information acquired by the assembly or input information utilized by the assembly.

20. The assembly according to claim 1, wherein the EMG sensors are affixed to a portion of the assembly.

21. The assembly according to claim 1, wherein the phase window is of a shorter duration than an entire stride of the assembly.

22. The assembly according to claim 1, wherein the means for determining a locomotion mode is based on the EMG signals received during a phase window of the immediately prior gait cycle.