DOB Design for Nonminimum-Phase Delay Systems and Its Application in Multivariable MPC Control

This brief first presents an improved disturbance observer (IDOB) design method to deal with disturbance observation for the nonminimum-phase delay systems. Then, an IDOB-based compound control scheme is developed to enhance the disturbance rejection performance of multivariable model predictive control (MPC) under various disturbances and uncertainties. In such an IDOB–MPC scheme, the MPC controller acts as a prefilter and generates appropriate control actions such that a desired setpoint tracking response is achieved. The IDOB is used to estimate the various disturbances dynamically and suppress them by feedforward compensation design. Both theory analysis and simulation comparisons have shown good disturbance estimation and rejection performances of the proposed method.