A unified approach to motion and force control of flexible joint robots

This paper addresses motion and force control issues of flexible joint robots in constrained motion in the presence of parametric uncertainty. Assuming that values of all system parameters, including joint flexibility, are unknown, except for some of their bounds, a new adaptive and sliding mode control scheme is developed, that provides a unified approach to motion and force control of flexible joint robots in general coordinate space. The proposed control scheme, consisting of an adaptive constrained motion/force controller and a joint torque sliding mode controller, guarantees that motion, force and joint torque tracking errors converge asymptotically to zero without persistent excitation. Simulation results illustrate the effectiveness of the proposed control method