Passivity based force control of hydraulic robots

This paper gives a new nonlinear force control of hydraulic robots. Unlike the electrical robots, hydraulic robots are governed not only by the energy conservation but also by the mass conservation. First we propose a generalized continuity law and a canonical form of hydraulic robots. Second, we propose a new nonlinear robust force control based on passivity in order to achieve the desired force in the presence of unknown environment consisting of the energy storing elements and dissipative elements. Finally, we confirm the validity of our proposed methods by simulation and experiment.