Trajectory tracking control of robot arms using ORBIX

A practical method of the 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. In this article the robust controller for the constant disturbances is practically designed and 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 effective. For the execution of these experiments, the robot language ORBIX written in the C language has been developed and used for both generation of the desired trajectory and specification of parameters in the control system.