Variable structure tracking of DC motor for high performance applications

The authors present a novel application of variable structure system control (VSS) for online tracking of DC motors. By the proposed technique, the rotor position, speed, and current can follow preselected tracks (a track is a time history selected in advance). The theory of the VSS is modified to include the tracking option for the general case of the multi-input/multi-output system. The robustness of the proposed tracking controller is ensured at all times. By selecting the tracks as proposed here, the electrical and mechanical stresses on the motor are substantially reduced, and soft starting of the motor is achieved. The entire drive system was built and tested in the laboratory by using off-the-shelf components and software. The test results show the effectiveness of the proposed tracking controller in high-performance drive applications such as robotics, manipulation, and actuation