SERVO MODEL PREDICTIVE CONTROL FOR OFFSET-FREE SETPOINT TRACKING

Offset-free tracking to setpoint signal generated by arbitrary unstable dynamics, such as constant, ramp, sinusoidal and periodic signals, is often required in practical control applications. It is usually achieved in Model Predictive Control (MPC) via the disturbance estimation approach. In this paper, an alternative based on the internal model principle, which is common in linear servo controller design, is adopted for MPC design. Therefore the proposed servo MPC can be interpreted as a hybrid of servo control and MPC. Two variants, depending on the availability of future setpoint information, are presented. Compared to the disturbance estimation approach, it provides a compact and straightforward controller design; offset-free tracking can be achieved even if the future setpoint trajectory is not known to the controller. Simulation studies validate the offset-free tracking property of the proposed MPC algorithm.