Advanced torque control of robot manipulators driven by AC induction motors

A new control architecture termed 'advanced torque control' is developed for robot manipulators driven by induction motors. The motor is regarded as a torque source, and a desired torque signal is designed based on the desired position trajectory. A commanded input to the torque loop is further developed to cause the torque to track the designed torque signal, utilizing a torque feedforward plus a PI-type torque feedback control. The method utilizes partial knowledge of the electromechanical dynamic model of the induction motor. Both position and current signals are controlled in the generation of the input to the torque loop. Experimental results conducted on a commercial AC induction servo system demonstrates that this new method exhibits good motion performance.