Variable structure control (VSC) systems consist of a set of subsystems referred to as structures and supplied with appropriate switching functions. The most common approach used for variable structure in continu-ous or discrete time systems is sliding mode. In this paper,a new scheme to design a discrete variable structure con-trol (DVSC) for an nth-order type one system is presented.First, a set of discrete subsystems is constructed relying on the assumption that every system is considered as a vari-able structure system when its poles can be assignment to other locations. The adopted method for constructing dif-ferent discrete structures involves switching alternatively two zero-order hold (ZOH) devices, having different char-acteristics. Second, a suitable switching function is devised based on minimizing a quadratic sum of discrete error sig-nal criterion, to perform one switching without chattering.New advantageous properties are carried out via compos-ing a desired performance from parts of performances of the constructed structures. Simulation results are made to illustrate the quality of control being achieved.
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