Lower leg mechanism for humanoid robots that enables natural transition between resistive/compliant behaviors to gravity and ankle pronation/supination

Abstract

A novel lower leg mechanism for humanoid robots is designed. The pronation/supination motion of the ankle is added to an existing planar complex knee-ankle mechanism that enables firm support against gravity and natural swinging by gravity. The increase of total moment of inertia is prevented by a linkage mechanism that remotely rotates the ankle, where the motors are assigned at the knee part. A prototype of the machanism was designed on 3D CAD.