Abstract: The dynamic of a robot manipulator performing the grinding task is examined. According to some kinematic and kinetic parameters, the variable structure dynamic treatment is used and the whole process is divided into free flight, impact and sliding long the rough surface. For these different stages, two kinds of control feedback are suggested. As usual, the computer torque method is used in the free fligt case. In order to achieve hybrid position/force control when the robot manipulator moves on a rough surface, a dynamic decoupling and linearing feedback control method is proposed, which decouples the the original nonlinear manipulator system into a number of decoupled liner subsystems. Thus the end-effector trajectory and contact force can be controlled separately. A numerical example of two-link planar manipulator performing the grinding task is presented to prove the control algorithm.

Key words: Manipulator, Nonlinear decoupling control, Rough surface contact