Variable-structure model following adaptive control for systems with time-varying delay

In this paper, the problem of model-reference control for linear systems with time-varying delay is investigated. By applying the theory of variable structure control, we propose a delay-independent control law to drive the error system between the model state and plant state to zero. The proposed control can drive the error system onto the chosen switching surface (sliding mode) once the error system is on the sliding mode, the system with time-varying delay acts as a delay-independent system. Also, we design a special type of sliding mode, which is easy for assigning the poles of the error system in the sliding mode. The control effect of our method is demonstrated by an illustrative example.