Friction compensation for an industrial hydraulic robot

A model based friction compensation scheme using a novel dynamical friction model was implemented on an industrial Schilling Titan II hydraulic robot. Off-line estimation of parameters was carried out, using the results of two kinds of experiments. These experiments were done independently at each joint. A nonlinear PI type controller was used in the inner torque loop to improve its performance. The complete control scheme has shown to substantially improve the position precision in regulation and tracking. Higher precision applications can be performed by the hydraulic robot with this controller.