Design of memoryless output feedback controller of discrete-time systems with input delay

This study addresses the output feedback stabilisation problem of discrete-time linear systems with input delay. By viewing the difference between the current input and the delayed input as a special disturbance, full- and reduced-order extended state observers are constructed, respectively, to estimate both the state and the disturbance simultaneously. Then the composite control laws are synthesised to actively compensate the input delay by using the state and disturbance estimates. Different from existing predictor-based control approaches, the proposed controllers are memoryless, and the past input information are thus not needed. Moreover, it can be observed that the information on the size of the input delay is not involved in either the observers or the controllers. Finally, simulation results are provided to illustrate the advantages and effectiveness of the proposed approaches.