Control of uncertain linear systems with a state delay based on an uncertainty and disturbance estimator

In this paper, a robust control strategy based on the uncertainty and disturbance estimator (UDE) is extended and applied to uncertain linear continuous-time systems with state delays and disturbances. It does not require the knowledge of the bounds of uncertainties and disturbances. Both known and unknown delay cases are considered. In the case of an unknown time delay, the term with the delay is treated as an additional disturbance to the system. The proposed algorithm shows excellent tracking and disturbance rejection capabilities. The robust stability of LTI-SISO systems is analysed and simulations are given to show the effectiveness of the UDE-based control.