Abstract
This paper considers the problem of designing digital sliding mode control systems. Sliding mode control schemes are often implemented in digital fashion because the complex switching logic can be easily carried out. In digital control systems, the ideal sliding mode does not occur since the structure cannot be switched during the sampling interval, however there can be exist a motion which is confined to a region including the sliding surface and proceeds to the origin along the surface. Such a motion is referred to as quasi-sliding mode. Itkis gave a condition of taking place quasi-sliding mode in a linear digital control system, but it is conservative and much complicated. In this paper, a new sufficient condition is presented, in which the upper bound of the sampling period and the upper and lower bounds of the magnitude of feedback gain are shown explicitly. Based on this result, a practically useful design procedure is proposed.
