Robust task-space control of hydraulic robots

This paper presents a model-based robust controller for hydraulically driven robot manipulators. The approach guarantees that the output error of the plant remains within a prescribed bound despite of model uncertainties. Manipulator dynamics and actuator dynamics including the dynamics of the valves are taken into account. The stability proof is based on the Lyapunov method and passivity arguments. It is shown that the stability proof is not restricted to the proposed control law of the hydraulic actuators but also holds for arbitrary hydraulic force control laws as long as certain requirements are fulfilled.