title: Controlled Reduction with Unactuated Cyclic Variables: Application to 3D Bipedal Walking with Passive Yaw Rotation.
abstract: This paper shows that viscous damping can shape momentum conservation laws in a manner that stabilizes yaw rotation and enables steering for underactuated 3D walking. We first show that unactuated cyclic variables can be controlled by passively shaped conservation laws given a stabilizing controller in the actuated coordinates. We then exploit this result to realize controlled geometric reduction with multiple unactuated cyclic variables. We apply this underactuated control strategy to a five-link 3D biped to produce exponentially stable straight-ahead walking and steering in the presence of passive yawing.
authors.affiliation: Department of Mechanical Engineering, Northwestern University and the Center for Bionic Medicine, Rehabilitation Institute of Chicago, Chicago, IL 60611 rgregg@ieee.org.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Gregg
authors.affiliation: Max-Planck Institute for Intelligent Systems, Tübingen, Germany ludovic.righetti@a3.epfl.ch.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Righetti