The problem of robust fault tolerant control for continuous-time fractional-order (FO) systems with interval parameters and sensor faults of has been investigated. By establishing sensor fault model and state observer, an observer-based FO output feedback controller is developed such that the closed-loop FO system is asymptotically stable, not only when all sensor components are working well, but also in the presence of sensor components failures. Finally, numerical simulation examples are given to illustrate the application of the proposed design method. 1. Introduction Fault tolerant control research and their application to a wide range of industrial and commercial processes have been the subjects of intensive investigations over the past two decades [1, 2]. Since unexpected faults or failures may result in substantial damage, much effort has been devoted to the fault tolerant control for various systems, such as active fault tolerant control for T-S fuzzy systems [3], reliable controller design for linear systems [4], robust satisfactory fault tolerant control of discrete-time systems [5], fault tolerant controller design for singular systems [6], and observer based fault-tolerant control for networked control systems [7]. On the other hand, fractional-order (FO) systems have attracted increasing interests, mainly due to the fact that many real-world physical systems are better characterized by FO differential equation [8–13]. The stability analysis of FO systems has been widely investigated, and there have been many stability results related to the continuous-time FO systems [14–20] and discrete-time FO systems [21]. In particular, in terms of linear matrix inequality, the stability condition has been given for continuous-time FO systems of order in [18] and of order in [20]. For FO-LTI systems with interval parameters, the stability and the controllability problems have been addressed for the first time in [22] and [23], respectively. Recently, for the FO controller design problem, many authors have done some valuable works [24–26] and applied them to control a variety of dynamical processes, including integer-order and FO systems, so as to enhance the robustness and performance of the control systems. While for interval FO systems, in [27, 28], authors have investigated the stabilization problem of and , respectively. However, the above papers dealt with state feedback control design that requires all state variables to be available. In many cases, this condition is too restrictive. So it is meaningful to control the FO systems via output
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