Artificial joints using agonist-antagonist actuators

Abstract

Artificial limbs and joints which behave like a biological limbs and joints employ a synthetic actuator which consume negligible power when exerting zero force, consume negligible power when outputting force at constant length (isometric) and while performing dissipative, nonconservative work, are capable of independently engaging flexion and extension tendon-like, series springs, are capable of independently varying joint position and stiffness, and exploit series elasticity for mechanical power amplification.

1 . An artificial limb comprising, in combination, 
 first and second members connected for movement relative to one another at a joint,    a flexion actuator connected between said first and second members, said extendable flexion actuator comprising the series combination of a first motor and a first elastic element drawing said first and second members together to reduce the angle between said first and second members at said joint,    a extension actuator connected between said first and second members, said extension actuator comprising the series combination of a second motor and a second elastic for urging said first and second members apart to increase the angle between said first and second members at said joint, and    a controller for independently energizing said first motor and said second motor at different times to control the movement of said artificial limb.