Uncertain Multiple Contacts: A New Class of Bio-Inspired Controllers

摘要: Many of the models used in the study of locomotion and manipulation are “hybrid–the equations of motion governing them undergo a discontinuous change at surfaces (“guards”) corresponding to changes in the contact state. Furthermore, even when driven by deterministic internal commands the transition sequences themselves–the order of footfalls or finger contacts–are often uncertain due to external influences. We have developed new methods for integration and analysis of this class of hybrid dynamical systems, allowing us to compute the stability properties associated with trajectories passing through intersections of guards. These suggest potential advantages associated with multiple contact gaits such as quadruped trots and paces, and hexapod alternating tripod gaits. Our theoretical results allowed us to design and prove the correctness of a piecewise constant state-feedback law that produced a stable alternating tripod gait for the RHex robot. The controller is “nearly” distributed–it requires only one message request-response exchange between the legs per stride.