Sliding plane design for discrete-time networked control of cable suspended loads

The paper addresses the problem of controlling the position of a cable suspended mass from a remote location with communication network used for information exchange. Since in industrial applications it is a common practice to apply digital controllers, in particular in networked environment, the design is performed with explicit consideration of finite sampling rate. Discrete sliding-mode control is proposed with sliding hyperplane providing delay compensating features. The plane parameters are selected for dead-beat response, and the control law is synthesized in easy-to-implement closed form. In order to satisfy input constraints (e.g. mass downward motion restricted by gravity constant), a time-varying hyperplane is introduced. The proposed control strategy provides fast error elimination without overshoots and oscillations.