SLIDING MODE CONTROL OF A DISCRETE SYSTEM

Conventional sliding mode control designed on the basis of a continuous system is known to be robust to the plant uncertainties. A realized digital system, however, not only yields chattering, but also may become unstable by a long sampling interval. This paper presents a stable discrete sliding mode control insensitive to the choice of sampling interval and not yielding chattering. The control system is designed on the basis of a discrete Lyapunov function and a sufficient condition of the control gain to make the system stable is given. Contrary to the continuous case, the derived switching plane of the control law is different from the sliding mode, and in its neighborhood, the control law is given by the linear state feedback. Simulations show the effectiveness of the proposed method. © 1990.