Robust global stabilization of the underactuated 2-DOF manipulator R2D1

In this paper a switching control strategy for robust stabilization of the 2nd-order nonholonomic 2-DOF SCARA robot R2D1 is presented. The first joint is actuated by a direct drive motor, whereas the second joint is equipped with a brake. The unactuated second joint is controlled by non-collocated linearization and a PD-controller. A stability region is derived and robustness is achieved by exploiting the contractive character of the perturbed stability region. The proposed switching control strategy assures global and robust position control of the second joint. Experimental results confirm the efficiency of the proposed approach.