Torque-Based Balancing

Abstract

This chapter presents an overview of balance control approaches which utilize joint torque as the control input. Such control approaches are particularly useful for robots with explicit measurement of the generalized actuation forces allowing for an inner loop torque control. As a system model, floating base robot dynamics is considered in combination with a set of contact constraints. After discussion of the problem of how to control contact forces for a constrained mechanical system, a detailed treatment of the force distribution problem is given, which appears in multi-contact situations of legged robots. In addition, the basic approaches to implement joint torque control in electrically and hydraulically actuated robots are discussed. The chapter presents the general control theory based on dynamic inversion and passivity theory and highlights some successful implementations using two torque-controlled humanoid robots based on electric and hydraulic actuation.