Numerical techniques for optimization of gait generation

Abstract

Optimization of robotic bipedal walking widely uses simplified dynamical models to minimize the computational cost and generate fast solutions, but this poses the problem of modeling errors and increased inaccuracy. Moreover, direct methods of optimization are almost always used; however, most are not implemented to satisfy Pontryagin's Principle, which can lead to suboptimal solutions. This study presents the optimization of planar robotic bipedal walking using exact dynamics. We apply pseudospectral optimal control to optimize gait generation using two accuracy requirements: nonlinear multi-degree-of-freedom whole-body dynamics and satisfied conditions of optimality according to Pontryagin's Principle. In order to consistently achieve solvability of optimization in this type of problem, we present a novel methodology consisting of synergic techniques that address well-known numerical difficulties of optimization.