Unified Smith Predictor for MIMO Systems with Multiple Time Delays

Abstract

In this chapter, a design methodology is developed to design a 2-DOF (degree of freedom) controller for multi-input multi-output (MIMO) systems having multiple time delays. MIMO systems with multiple delays are converted to lower-fractional transformation using weighting function whose parameters are tuned using a genetic algorithm (GA). The converted delayed plant is transformed to augmented plant using the unified Smith predictor (USP). Setpoint tracking is isolated from disturbance rejection using the 2-DOF controller structure. An observer-based feedback controller is designed for disturbance rejection and reference-based model matching controller for setpoint tracking. Robust stability is obtained from the designed controller. The 2-DOF controllers provide the advantage of complete separation of reference tracking and feedback properties. This is very advantageous to provide a good compromise between setpoint tracking and disturbance rejection if input and disturbance have a different behavior toward error.