This paper investigates the problem of robust output feedback control of uncertain continuous-time time-delay systems with both external disturbances and saturating actuators. Both the system uncertainties and the external disturbances are assumed to be time-varying and bounded, and the states of the system under consideration are not available but detectable. First, in the absence of external disturbances, some delay-dependent conditions for designing observer-based output feedback controller are derived which ensure that the system without perturbations on its input matrices can be stabilized together with the domain of attraction. To obtain a maximal estimate of the domain of attraction, an iterative optimization algorithm is proposed. When the system input matrices are subject to perturbations, new stabilization conditions are obtained to adjust the gain of the observer on the basis of the above-mentioned controller design rules. Second, in the presence of external disturbances, the robust observer-based output feedback controller is designed to guarantee that the corresponding closed-loop system converges uniformly exponentially to a ball with an initial admissible domain. Finally, numerical results are given to demonstrate the effectiveness of the proposed method.
Wei, Y., Zheng, W. X., & Xu, S. (2015). Robust output feedback control of uncertain time-delay systems with actuator saturation and disturbances. Journal of the Franklin Institute, 352(5), 2229–2248. https://doi.org/10.1016/j.jfranklin.2015.03.013