Volume 23 Issue 6 - Publication Date: 1 June 2004
Experimental Validation of a Framework for the Design of Controllers that Induce Stable Walking in Planar Bipeds
E. R.Westervelt Department of Mechanical Engineering, The Ohio State University, Columbus, Ohio 43210, USA, G. Buche Laboratoire d’Automatique de Grenoble, Ecole Nationale d’Ingénieurs Electriciens de Grenoble, BP 46, 38402 St Martin d’Hères, France and J.W. Grizzle Control Systems Laboratory, Electrical Engineering and Computer Science Department, University of Michigan, Ann Arbor, Michigan 48109–2122, USA

In this paper we present the experimental validation of a framework for the systematic design, analysis, and performance enhancement of controllers that induce stable walking in N-link underactuated planar biped robots. Controllers designed via this framework act by enforcing virtual constraints-holonomic constraints imposed via feedback-on the robot’s configuration, which create an attracting two-dimensional invariant set in the full walking model’s state space. Stability properties of resulting walking motions are easily analyzed in terms of a two-dimensional subdynamic of the full walking model. A practical introduction to and interpretation of the framework is given. In addition, in this paper we develop the ability to regulate the average walking rate of the biped to a continuum of values by modification of within-stride and stride-boundary characteristics, such as step length.

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