Open-loop Stable Control of Running Robots - A Numerical Method for Studying Stability in the Context of Optimal Control Problems

Abstract

An open-loop controlled robot must have strong stability properties. This paper presents a numerical method for studying the stability of robots in the context of optimal control problems. Parameter studies for a one-legged hopping robot are performed. 1 Introduction Most running robots use sensor-based feedback to actively control the stability of their motion. Perturbations of the desired position histories are detected and appropriate counteractions are computed and performed. In the case of complex robot congurations this task can be too compute-intensive to be handled in real time. It has been shown that it is also possible to construct legged monopods and bipeds which can sustain stable dynamic locomotion without any sensors. Examples are the selfstabilizing MIT robot described by Ringrose [7] and passive dynamic walking machines, see e.g. [4]. These robots are designed in such a way that they are inherently stable and can recover automatically from small perturbations even ..