Design of servocontroller via the sliding mode technique

A new discrete-time servocontroller is presented which uses the sliding mode technique inspired by Hwang et al. (1987) for tracking a desired time-varying reference command. The reference command is not necessarily periodic. One of the features of the proposed servocontroller is that the larger switching gains are used for greater deviation from the sliding surface and the equivalent linear control law is employed as the operating point is on the sliding surface. Under suitable conditions, the stability properties for the servosystems subject to the uncertainties are also achieved. Compared with other methods the simulations show a fast response without overshoot and good robust performances in the presence of parameter variations.