Postural Equilibrium criteria concerning Feet Properties for Biped Robots

Abstract

 A research on the postural equilibrium conditions for biped robots is presented in this article. Dynamic
 walking criteria like ZMP and CoP are presented, and their parallels are examined. The consequences
 of a compliant foot are also introduced and taken into account while evaluating the criterion.
 The VICON motion capture technology records a human subject's movements, which are then
 replicated using a model of a planar biped. Ground reaction forces and body segment accelerations are
 required to estimate the criterion. For the motion of the model, ZMP and CoP are examined in both
 single and double support phases.During the double support phase, the biped's load is transferred
 between the supporting legs using a linear shift function. We compare the simulated CoP trajectories
 produced by a compliant, deformable spring-damper system situated between the foot sole and the
 ankle joint, and a rigid foot. It is evident that the deformation of the foot enhances the stability of the
 biped and smoothes the CoP trajectory