Experimental Validation of a Framework for the Design of Controllers that Induce Stable Walking in Planar Bipeds

This paper presents 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 sub-dynamic of the full walking model. A practical introduction to and interpretation of the framework is given. In addition, the paper develops 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.