Cartesian control of a hydraulic redundant manipulator

A controller for redundant manipulators with a small, fast manipulator mounted on a positioning part has been developed. The controller distributes the fast motion to the small, fast manipulator and the slow, gross motion to the positioning part. A position reference is generated on-line to the positioning part to avoid singularities and the loss of degrees of freedom. The task space position vector is augmented by the generalized coordinates of the positioning part. Feedback linearization and decoupling are then applied in the augmented task space to obtain a model consisting of decoupled double integrators. These decoupled double integrators are controlled by the use of linear quadratic optimal control. The controller has been applied to an eight-link hydraulic spray painting robot. The experiments showed that a high bandwidth and a large working area were possible with moderate motor torques.