Controller Design for Robot Arm Guarded and Compliant Motions

Controller designs for the guarded and compliant phases of a robot arm task are proposed. For the guarded-motion phase a state-feed-back controller with linearized decoupling is proposed. This controller is cascaded with a force-feedback loop during the compliant phase. This differs from those schemes already presented in the literature in that position and velocity feedback are retained along the force-controlled axes. The guarded and compliant controllers take over from a proportionalderivative free-motion controller near the end of the free-motion path. Simulation studies on a two-link robot arm are carried out to evaluate the proposed desing as well as to compare it with a more conventional proportional-integral-derivative design.