Walking of a Five-Link Planar Biped Robot:

Controller Analysis and Design

Based on the Zero Dynamics


Eric Westervelt
Control Systems Laboratory

EECS Department

University of Michigan


This presentation will discuss controller analysis and design for the walking motion of a 5-link planar biped robot equipped with four actuators: two at the hips acting between the torso and each femur and one at each of the knees, with no actuation at the ankles. The system is thus underactuated. Moreover, the robot's  model is hybrid in nature, assuming a rigid contact when the swing leg impacts the ground and an instantaneous double-support phase. It will be shown how to reduce the stability analysis and performance enhancement aspects of the controller design to a one-degree of freedom dynamical system. This is done by computing what may be called the zero dynamics of the hybrid model, and relating closed-loop stability and performance properties of the overall model of the robot to its behavior on a two dimensional invariant surface.


Friday, October 19, 2001

3:30 - 5:00 p.m.

1500 EECS