Feedback linearized joint torque control of a geared, DC motor driven industrial robot

This paper examines the computed torque control method applied as an outer torque loop supplying desired torque signals to industrial manipulators with flexible, geared, DC motor driven links executing independent inner joint torque control loops. This paper proposes a new control law that restores the desired closed loop dynamic equations to remove the configuration dependence from the manipulator performance through dynamic feedback linearization of the joint torque control signals. Conventional PID, standard computed torque with joint torque control and the new feedback linearized joint torque controllers are applied to the first three joints of a 6 degrees-of-freedom industrial manipulator. The system performance of the controllers in a standard task is evaluated with experiments on an industrial robot. The results show that both computed torque methods provide substantial tracking performance improvements over a conventional PID controller