Continuous and discrete sliding mode control for systems with parametric uncertainty using delay-ahead prediction

In this paper, first order continuous and discrete sliding mode controllers are designed for second-order-plus-delay-time model (SOPDT). As the presented methodology is based on SOPDT model, the higher order model is reduced into SOPDT structure using model order reduction technique. The sliding surface is chosen as a linear function of the system states. In order to handle the system time delay and uncertainties due to plant-model mismatch, a delay ahead predictor is used for prediction of the system states. The control laws are derived from the model and sliding surface with predicted states. The methodology integrates reduced model, sliding surface and delay ahead prediction. Simulation examples are included to show the usefulness of the proposed controllers and to analyze the effect of sampling period on continuous and discrete sliding mode controllers.