Discrete-Time Velocity Servo System Design Using Sliding Mode Control Approach With Disturbance Compensation

This work presents a new approach to high performance velocity servo system design. The approach is based on a discrete-time sliding mode (DSM) control with disturbance compensation. For the purpose of design, the controlled plant is approximated by first-order model. The traditional, as well as the integral type of DSM control is considered. The disturbance compensator is based on the fact that the matched disturbances are directly reflected in the previous value of the switching function. In this paper, slow varying disturbances are estimated by a parallel connection of first- and second-order estimators. The integral type of DSM velocity servo system with such combined compensator can track references and significantly reject bounded disturbances, both up to cubic parabola type. The proposed control system is chattering-free. Theoretically obtained results are verified by simulations and experiments.