This paper investigates the fault tolerance problem of flexible satellites subject to multiple disturbances and actuator faults. An adaptive fault tolerant control (FTC) approach based on disturbance observer is presented for attitude control system (ACS) with actuator faults, elastic modal, modeling error and environmental disturbance torque in this paper. Different from some existing disturbance observer-based control (DOBC) approaches, Takagi-Sugeno (T-S) fuzzy modeling technology is applied to describe the elastic modal. A fuzzy disturbance observer and a fault diagnosis observer are constructed to estimate the elastic modal and actuator fault, respectively. Then, based on fault accommodation and DOBC, a new adaptive FTC strategy is designed to achieve the anti-disturbance performance and improve the system reliability. Finally, the efficiency of the proposed FTC scheme is verified by simulation results.

<abstract><p>With the rapid development of smart campus, this paper studies the attitude tracking control of flexible manipulator (FM) in colleges and universities under elastic vibration and external disturbances. First, different from the traditional modeling based on ordinary differential equations (ODEs), the partial differential equations (PDEs) dynamic model of a manipulator system is established based on the Hamilton principle (HP). Second, the boundary control condition of the end system of the manipulator is introduced to adjust the vibration of the manipulator. Furthermore, a Proportional-Derivative (PD) boundary control (PDBC) strategy is proposed by the Lyapunov function to suppress the vibration of the manipulator. Finally, a numerical comparison simulation based on MATLAB/SIMULINK further verifies the robustness and anti-disturbance performance of the control method proposed in this paper.</p></abstract>

<abstract><p>This paper investigates the fault tolerance problem of flexible satellites subject to actuator faults and multiple disturbances. An adaptive sliding mode fault tolerant control (ASMFTC) approach based on Takagi-Sugeno (T-S) fuzzy disturbance observer (TSFDO) is presented for attitude control system (ACS) under loss of actuator effectiveness, environmental disturbance torque and elastic modal generated by flexible appendages. Compared with the traditional disturbance observer based control (DOBC) methods, the T-S fuzzy technology is applied to estimate the unknown nonlinear elastic modal. Then, the energy bounded disturbance is eliminated by designing an adaptive sliding mode controller. The proposed ASMFTC design can guarantee the sliding surface to approach zero. Finally, the effectiveness of the control method proposed in this paper is further verified by comparative simulation.</p></abstract>

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