A. Hofmann, S. Massaquoi, M. Popovic, and H. Herr. A sliding controller for bipedal balancing using integrated movement of contact and non-contact limbs, IEEE/RSJ International Conference on Intelligent Robots and Systems, vol. 2, pp. 1952–1959, 2004.

Abstract

We present an algorithm that provides enhanced flexibility and robustness in the control of single-leg humanoid standing through the coordination of Stance leg ankle torqoer and stabllizlng movemenb of non-contact Umbs. Current control approaches generally assume the presence of expllcltly specifled joint reference trajectories or desired virtual force calculatiaas that ignore system dynamics. Here we describe a practical controller that 1) simplifies control of abstrad variables such as the center of mass loentioo using a two-stage model-based plant Uoearization; 2) determines motion of non-contact limbs useful for achieving control targets while satisfying dynamic balance constraints; and 3) provides robustoess to modeling error using a sliding controller. The controller is tested with B morphologically redistic, 3-dimensiona1, 18 degree-offreedom humanoid model serving as the plant. It is demou?trated that the controller can use less detailed control targets, and reject stronger distnrbancer, than previously implemented Controllers that employ desired Virtual forces and static body calculations.