Artificial ankle-foot system with spring, variable-damping, and series-elastic actuator components

• US 8,734,528 B2
• Filed: 12/21/2012
• Issued: 05/27/2014
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Herr, Hugh M., Au, Kwok Wai Samuel, Paluska, Daniel Joseph, Dilworth, Peter
• Primary Examiner(s): SNOW, BRUCE EDWARD
• Application Number:
  US13/723,743
• Publication Number:
  US 20130110256A1
• Time in Patent Office: 522 Days
• Field of Search: 623 47- 55
• US Class Current: 623/24
• CPC Class Codes: A61F 2/60 Artificial legs or feet or parts thereof
• CPC Class Codes: A61F 2/605 Hip joints
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/6607 Ankle joints
• CPC Class Codes: A61F 2/68 Operating or control means
• CPC Class Codes: A61F 2/70 electrical
• CPC Class Codes: A61F 2002/5004 operated by electro- or magnetorheological fluids
• CPC Class Codes: A61F 2002/5006 Dampers, e.g. hydraulic damper
• CPC Class Codes: A61F 2002/503 for adjusting elasticity, flexibility, spring rate or mechanical tension
• CPC Class Codes: A61F 2002/5033 for adjusting damping damping means A61F2002/5003
• CPC Class Codes: A61F 2002/5073 Helical springs, e.g. having at least one helical spring
• CPC Class Codes: A61F 2002/5075 Multiple spring systems including two or more helical springs
• CPC Class Codes: A61F 2002/5079 Leaf springs A61F2002/6657 takes precedence
• CPC Class Codes: A61F 2002/509 specially designed for children, e.g. having means for adjusting to their growth implantable A61F2250/0082
• CPC Class Codes: A61F 2002/6657 having a plate-like or strip-like spring element, e.g. an energy-storing cantilever spring keel
• CPC Class Codes: A61F 2002/6678 L-shaped
• CPC Class Codes: A61F 2002/6818 for braking
• 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 2002/763 : for measuring spatial position, e.g. global positioning system [GPS]
• 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: B25J 19/0008 : Balancing devices
• CPC Class Codes: B62D 57/032 : with alternately or sequentially lifted supporting base and legs; with alternately or sequentially lifted feet or skid B62D57/024 takes precedence

Abstract

An artificial foot and ankle joint consists of a curved leaf spring foot member having a heel extremity and a toe extremity, and a flexible elastic ankle member that connects the foot member for rotation at the ankle joint. An actuator motor applies torque to the ankle joint to orient the foot when it is not in contact with the support surface and to store energy in a catapult spring that is released along with the energy stored in the leaf spring to propel the wearer forward. A ribbon clutch prevents the foot member from rotating in one direction beyond a predetermined limit position. A controllable damper is employed to lock the ankle joint or to absorb mechanical energy as needed. The controller and sensing mechanisms control both the actuator motor and the controllable damper at different times during the walking cycle for level walking, stair ascent, and stair descent.

Claims

1. A device comprising:

a) a mechanical ankle joint;

b) a controllable actuator to exert a torque about the joint, the actuator including a motor and

a spring that is operatively coupled with the motor;

c) an artificial sensory system comprising at least one sensor selected from the group consisting of a position sensor, a velocity sensor, a gyroscope, an accelerometer, and a force sensor; and

d) a control system configured to cause the motor to store elastic energy in the spring during controlled dorsiflexion based on information from the at least one sensor for later release of stored elastic energy from the spring during powered plantar flexion of the gait cycle, wherein the motor stores elastic energy during controlled dorsiflexion over a longer period of time than the amount of time to release energy from the spring during powered plantar flexion to augment power output of the joint.

2. The device of claim 1, further comprising a stop adapted to prevent rotation of the joint beyond a predetermined limit.