Passivity Based Control of Bipedal
Walking Robots
Coordinated Science
Laboratory
University
of Illinois at Urbana-Champaign
Passive
walking, the notion that mechanisms can be designed to exhibit stable walking
gaits down shallow inclines, has intrigued researchers for more than a
decade ever
since the work of McGeer, who built planar passive bipeds both with and without
knees. Such mechanisms rely on a
careful balance among kinetic energy, potential energy, and energy loss during
impacts to achieve passive periodic gates. In this talk we will explore the relationship between passive walking and passivity based
nonlinear control. We will show,
as a consequence of some symmetry properties in the Lagrangian description of
the dynamics of bipeds, how active feedback control can achieve the same energy
balance independent of the ground slope. The result is a simple control design
method to generate stable walking on any slope including level ground and
uphill. We will also discuss ways to increase the basin of attraction of the
resulting limit cycles for enhanced disturbance rejection. Animations of a
biped with knees and a torso will be shown to illustrate the theory.
3:30 – 4:30
p.m.