Trajectory Tracking Control of Robot Arms Using Orbix

Abstract

A practical method of trajectory tracking control and the robot language ORBIX are proposed. The model-following servo controller is used so that the linearized robot arm, compensating for the nonlinear effects, follows the model of the reference trajectory. If the state feedback is used for this control law, the resultant control law is shown to be equivalent to the resolved acceleration control, which indicates that the proposed control structure is general for the robot control. The robust controller for the constant disturbances is developed in order to make the tracking error zero at stopping points of reference trajectories even if the parameters of the arm are not correct. Integrator wind-up due to the saturation of actuator torques is eliminated by resetting the integrator so that consistency of the control system is maintained. The method has been applied experimentally to the three-joint control of an industrial robot and has been found effective.