PROSTHETIC HYDRAULIC JOINT WITH ACCUMULATOR AND METHODS FOR CONTROLLING JOINT

• US 20130173022A1
• Filed: 07/02/2012
• Published: 07/04/2013
• Est. Priority Date: 07/01/2011
• Status: Active Grant

• Current Assignee: Ottobock SE & Co. KGaA
• Original Assignee: Orthocare Innovations, LLC
• Inventors: Arabian, Adam, Boone, David Alan, Macomber, Ben Gilbert, Butel, Tyler, Lane, Robert Dustin
• Granted Patent: US 9,820,871 B2
• Time in Patent Office: Days
• US Class Current: 623/49
• CPC Class Codes: A61F 2/6607 Ankle joints
• CPC Class Codes: A61F 2/70 electrical
• CPC Class Codes: A61F 2/74 fluid , i.e. hydraulic or pneumatic
• CPC Class Codes: A61F 2/741 using powered actuators, e.g. stepper motors or solenoids
• CPC Class Codes: A61F 2/748 Valve systems
• CPC Class Codes: A61F 2002/5003 having damping means, e.g. shock absorbers
• CPC Class Codes: A61F 2002/5006 Dampers, e.g. hydraulic damper
• CPC Class Codes: A61F 2002/5018 for adjusting angular orientation
• CPC Class Codes: A61F 2002/5033 for adjusting damping
• CPC Class Codes: A61F 2002/6854 for locking or unlocking a joint
• 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 2002/7625 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
• CPC Class Codes: A61F 2002/765 for measuring time or frequency
• CPC Class Codes: A61F 2002/7665 for measuring temperatures

Abstract

A prosthetic foot assembly is disclosed. The assembly includes a pivoting ankle joint with a hydraulic system, a prosthetic foot connected to the distal side of the ankle joint, and, at the proximal side, the ankle joint includes a transducer with pyramid adaptor for attaching to a pylon. The ankle joint sensor provides data collection during the stance and optionally, the swing, phases of walking using, for example, strain gages and accelerometers. Also disclosed are methods for real-time feature extraction. Key parameters are captured to which are applied linear, fuzzy logic, neural net, or generic algorithms to determine current state (walking flat, uphill, downhill etc.) in real time and execute changes to the angle between the ankle and foot almost instantaneously based on those parameters.

Claims

1. A method for controlling a prosthetic ankle joint employing a processor and a sensor, the method, comprising:

determining if a prosthetic ankle joint is weight bearing;

if the prosthetic ankle joint is weight bearing, determining if a stance phase is qualified to be a true stance phase of a patient ambulating;

if the stance phase is qualified to be a true stance phase, determining a ground slope or a speed of the patient, and controlling the angular alignment of the prosthetic ankle joint based on the ground slope or speed; and

if the prosthetic ankle joint is not weight bearing, locking or relaxing the ankle joint.

2. The method of claim 1, further comprising collecting training gait data from the patient with a normal gait, and comparing the training gait data to data that is collected when the ankle joint is weight bearing, and, based on the comparison, qualifying the stance phase.

3. The method of claim 1, further comprising collecting training gait data from the patient walking on a level ground and at a normal speed, and determining a home position for the ankle joint based on the level ground and normal speed.

4. The method of claim 3, further comprising, when a level ground slope is detected, controlling the ankle joint at the home position.

5. The method of claim 3, further comprising, when a normal speed is detected, controlling the ankle joint at the home position.

6. The method of claim 1, further comprising collecting training gait data from a patient with a normal gait, comparing the training gait data to data that is collected from the qualified stance phase, and, based on the comparison, detecting the ground slope or speed.

7. The method of claim 6, further comprising, when the ground slope is detected to be uphill, dorsiflexing the prosthetic ankle joint.

8. The method of claim 6, further comprising, when the ground slope is detected to be downhill, plantarflexing the prosthetic ankle joint.

9. The method of claim 6, further comprising, when the patient is detected to be walking slow, dorsiflexing the prosthetic ankle joint.

10. The method of claim 6, further comprising, when the patient is detected to be walking fast, plantarflexing the prosthetic ankle joint.

11. The method of claim 1, further comprising, if the stance phase is qualified to be a true stance phase, determining if the patient is ascending stairs or descending stairs.

12. The method of claim 1, further comprising determining anterior moment and posterior moment during a stance phase, and comparing the anterior moment and posterior moment to training data.

13. The method of claim 12, further comprising detecting downhill when a maximum anterior moment is less than a maximum anterior moment of the training data and a maximum posterior moment is greater than a maximum posterior moment of the training data.

14. The method of claim 12, further comprising detecting uphill when a maximum anterior moment is greater than a maximum anterior moment of the training data and a maximum posterior moment is less than a maximum posterior moment of the training data.

15. The method of claim 12, further comprising detecting ascending stairs when an axial force is greater than an axial force of the training data and a posterior or anterior moment is greater than a posterior or anterior moment of the training data.

16. The method of claim 12, further comprising detecting descending stairs when an axial force is greater than an axial force of the training data and a posterior or anterior moment is greater than a posterior or anterior moment of the training data.

17. The method of claim 1, further comprising, when the ankle joint is not weight bearing, detecting if a keel angle is greater than a predetermined value and an anterior moment is greater than a predetermined value for a specified time period.

18. The method of claim 17, further comprising, in response to detecting a keel angle is greater than a predetermined value and an anterior moment is greater than a predetermined value for a specified time period, locking the ankle joint.

19. The method of claim 17, further comprising, in response to not detecting a keel angle is greater than a predetermined value and an anterior moment is greater than a predetermined value for a specified time period, relaxing the ankle joint.

20. The method of claim 19, further comprising, when the ankle joint is relaxed, detecting at least one condition from the ankle joint is weight bearing, the ankle joint rate of motion exceeds a predetermined value, or the axial force rate of change exceeds a predetermined value, and, in response to detecting the one condition, moving the ankle to a home position determined from training gait data.

21. The method of claim 1, further comprising plantarflexing the ankle joint when a posterior moment is sensed during a stance phase.

22. The method of claim 1, further comprising dorsiflexing the ankle joint when an anterior moment is sensed during a stance phase.

23. The method of claim 1, further comprising determining if a swing phase is qualified to be a true swing phase of a patient ambulating, and, if the stance phase and swing phase are qualified to be a true stance phase and swing phase of a person ambulating, determining a ground slope or a speed of the patient.

24. The method of claim 23, further comprising collecting training gait data from the patient with a normal gait, and comparing the training gait data to data that is collected when the ankle joint is weight bearing, and, based on the comparison, qualifying the stance and swing phase.

25. The method of claim 23, further comprising collecting training gait data from a patient with a normal gait, comparing the training gait data to data that is collected from the qualified stance and swing phase, and, based on the comparison, detecting the ground slope or speed.

26. A prosthetic ankle joint, comprising:

a base having a pivot secured to a body;

a first and second piston in contact with the base;

the body having a first and second cylinder within which the first and second pistons are placed, wherein the first cylinder and piston are placed anteriorly to the pivot and the second cylinder and piston are placed posteriorly to the pivot;

a hydraulic system connecting the first and second cylinders, wherein the system comprises one or more values to control transfer of fluid between the first and second cylinders; and

a processor programmed with instructions to control the one or more valves.

27. The prosthetic ankle joint of claim 26, further comprising a first and second cam on the base, wherein the first cam supports the first piston, and the second cam supports the second piston, and the cams have a parabolic upper surface.

28. The prosthetic ankle joint of claim 26, further comprising a hydraulic fluid accumulator in each of the first and second piston, wherein the accumulator comprises a subpiston and a spring biasing the subpiston within a chamber, wherein the chamber is allowed to receive and expel hydraulic fluid to and from the cylinder corresponding with the accumulator.

29. The prosthetic ankle joint of claim 26, further comprising a transducer connected to the upper side of the ankle joint and a foot connected to the lower side of the base.