Sliding modes in sampled-data systems

The sliding mode application in discrete-time systems can result in unwanted oscillations of the controlled variable (so called chattering). To avoid above-mentioned oscillations a new approach in the design of sliding mode control is proposed in this paper. In the proposed approach the calculation of the equivalent control is not necessary while the influence of the system uncertainty and chattering are reduced. The proposed method is applicable to linear as well as nonlinear systems. It allows the design of the control without transformation of the system description to the discrete-time form (z-domain). Upper bound of the sapling time is determined from the switching function changes during the sampling period. The systems with state observers are analyzed. Experimental and simulation results are presented to clarify the design procedure and the features of the proposed algorithm.