Discrete quasi-sliding mode tracking controller with time delay technique

Robust discrete quasi-sliding mode tracking controller is developed with discrete reachinglaw for trajectory tracking in the presence of modeling uncertainty and unknown disturbance. The conventional prior knowledge of uncertainty upper bounds being replaced by an on-line estimation used in the controller to cancel the slowly varying uncertainties by the mechanism of time delay. This method reduces the feedback gain substantially and improves tracking accuracy. The system behavior in the vicinity of the sliding surface is examined for the existence and bandwidth of quasisliding mode. Simulation results show the effectiveness of the strategy.