Building walking gaits for irregular terrain from basis controllers

This paper presents an online technique for constructing walking gaits for legged robots on irregular terrain. The approach involves designating sequences of closed-loop control laws derived from a control basis. A control basis is a set of artificial potential functions that are device and task independent. A variety of walking contexts can be achieved by varying the sequence of controllers drawn from the control basis, avoiding the need to re-plan leg placements or redesign task-specific behaviors. A control basis previously shown to span the task of walking over flat terrain is shown to also span the task of locomotion over unknown piece-wise planar terrain by incrementally modifying the control composition policy. The resulting gaits are aperiodic, discontinuous, non-sequential, and incorporate controlled slippage of the feet