Gait Control of a Fully Actuated Walking Robot

Abstract

This paper considers the problem of feedback control of a fully actuated biped robot such that a virtual holonomic constraint (VHC) is enforced concomitant with control of the stance leg using a reach control methodology. The reach controller achieves safety and liveness specifications on the stance leg speed and the step size, resulting in a polytopic state space for the restricted hybrid dynamics on the VHC constraint manifold. It is shown that both the restricted system and the full hybrid system exhibit a stable, hybrid limit cycle. The design method can provide a way to compliantly adjust gait speed, for instance, to gently transition between different gaits, while maintaining transients within safe bounds.