Towards computationally efficient planning of dynamic multi-contact locomotion

Abstract

This paper considers the problem of numerically efficient planning for legged robot locomotion, aiming towards reactive multi-contact planning as a reliability feature. We propose to decompose the problem into two parts: an extremely low dimensional kinematic search, which only adjusts a geometric path through space; and a dynamic optimization, which we focus on in this paper. This dynamic optimization also includes the selection of foot steps and hand-holds-in the special case of instantaneous foot re-location. This case is interesting because (1) it is a limiting behavior for algorithms with a foot switching cost, (2) it may have merit as a heuristic to guide search, and (3) it could act as a building block towards algorithms which do consider foot transition cost. The algorithm bears similarity both to phase space locomotion planning techniques for bipedal walking and the minimum time trajectory scaling problem for robot arms. A fundamental aspect of the algorithm's efficiency is its use of linear programming with reuse of the active set of inequality constraints. Simulation results in a simplified setting are used to demonstrate the planning of agile locomotion behaviors.