Cascade control of a hydraulically driven 6-DOF parallel robot manipulator based on a sliding mode

A cascade-control algorithm based on a sliding mode in the legspace is proposed to realize the trajectory tracking control of a hydraulically driven six degrees of freedom (6-DOF) parallel robot manipulator. The cascade controller, which consists of an inner loop and an outer loop, is applied to separate the hydraulic dynamics from the mechanical part so that the designed controller takes into account not only the mechanical dynamics but also the hydraulic dynamics of the manipulator. The experimental results investigate the effectiveness of the proposed approaches and demonstrate the satisfactory position tracking behaviour of the parallel manipulator for the proposed cascade controller based on a sliding mode.