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This study deals with the fault-tolerant control problem for a class of two independent wheeled mobile robot systems with actuator faults and unknown robot parameters. Partial loss of control effectiveness and bias-actuator faults are addressed without knowing eventually faulty information of actuators. Adaptive schemes are developed to estimate unknown faulty parameters of actuator faults and unknown robot parameters of viscous friction factor and driving gain. Then, the backstepping control technique is utilised to construct the state feed-back control strategy based on the adaptive estimations. By using the Lyapunov stability theory, it is shown that the forward speed and azimuthal angle of wheeled mobile robots can track the given trajectory asymptotically in the case of actuator faults and unknown parameters. The effectiveness of the proposed designs is illustrated via a mobile robot system.

In this paper, the insensitive fault tolerant control (FTC) problem is addressed for a class of linear continuous-time systems against bounded and time-varying actuator faults, external disturbances, and controller coefficient variations. Unparametrizable time-varying actuator faults are considered without the knowledge of fault efficiency factors. To obtain the information of the constant bounds of faults and disturbances, an adaptive mechanism is designed to estimate the bounds. Based on these estimations, an adaptive FTC controller is constructed to eliminate the effects of faults, disturbances, and coefficient variations. Then bounded stability of the closed-loop adaptive system is achieved based on Lyapunov stability theory. The efficiency of the developed adaptive control strategy is verified by a rocket fairing structural-acoustic model.