An enhanced smith predictor based robust control over networked control system with random time delays

In this paper, a newly robust control scheme that contains an enhanced smith predictor is proposed to adaptively estimate and identify control law on line to reply to the time-varying network induced delays. A control sequence that contains a series of control signals is generated from a queue of possible future time delays at the controller node and the final option on which control signal is selected is given to the actuator according to the actual transmission delay. Two buffers are used respectively at the controller node and actuator node, which can transform the continuous time-varying delays into several discrete values and make sure time delays exactly predicted. Finally the simulation results demonstrate the effectiveness of the proposed methods to guarantee the robust performance of networked control system with random time-varying delay.