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In this study, a robust adaptive flight controller is developed to achieve anticipant trajectory tracking performance for a medium-scale unmanned autonomous helicopter (UAH) with external disturbances, actuator faults and full state constraints. The flapping dynamics of the main rotors is taken into consideration in the modeling process. The adaptive method is employed to handle the unknown bounded disturbances. A novel fault tolerant control (FTC) strategy is proposed to cope with actuator faults, which can effectively overcome the singularity problem in many adaptive estimation approaches by using projection function. Meanwhile, a suitable barrier Lyapunov function (BLF) is constructed to refrain from the violation of the state constraints. Combining with the backstepping technique, the four control inputs of the medium-scale UAH system are designed in sequence. Via the Lyapunov analysis, it is proved that all error signals in the closed-loop system converge to a small neighborhood around zero. Simulation studies are carried out to reveal the validity of the presented approach. • The flapping dynamics are introduced to embody the movement of the medium-scale UAH. • A novel FTC approach is proposed to deal with the actuator faults. • The singularity problem of direct adaptive estimation can be solved conveniently. • The developed FTC scheme can guarantee that all state constraints are not violated. [ABSTRACT FROM AUTHOR]

In this article, an adaptive neural fault-tolerant control (FTC) scheme is proposed for the medium-scale unmanned autonomous helicopter subject to external disturbance, actuator fault, and input saturation. Multiple approximators are constructed to handle the unknown terms and promote the control design. The nonlinear coupled function terms are approximated by virtue of the radial basis function neural networks. The unknown disturbance is tackled by the developed disturbance observer. Meanwhile, two auxiliary systems are introduced to handle the actuator fault and input saturation, respectively. In the framework of the backstepping method, a multiapproximator-based adaptive FTC strategy is presented, which assures the boundedness of all closed-loop system signals. Simulation results are presented to validate the availability of the designed controller. [ABSTRACT FROM AUTHOR]

This article deals with the problem of attitude tracking control for flexible satellite under flexible vibration disturbance, actuator fault and time delay. Based on disturbance observer and fault tolerant control techniques, the flexible vibration disturbance and actuator fault are effectively estimated by disturbance observer and fault estimation observer, respectively. Meanwhile, a delay-dependent attitude tracking feedback controller is designed to ensure that the reference attitude is stably tracked. To reduce the conservatism of the designed algorithm, a time delay correlative decomposition factor is introduced to make the flexible satellite have a better performance for attitude tracking control. Finally, the effectiveness of the proposed method is illustrated by numerical simulations. [ABSTRACT FROM AUTHOR]

This study proposes a sliding mode fault‐tolerant control (FTC) scheme for the medium‐scale unmanned autonomous helicopter with rotor flapping dynamics in the presence of wind gusts and actuator faults using extended state observer technique. The radial basis function neural networks are employed to tackle the unknown non‐linear interaction functions and adaptive neural network extended state observers are constructed to estimate the unknown wind gusts. Meanwhile, the adaptive fault observers are developed to estimate the fault parameters in position, attitude and flapping motion subsystems. With the aim of obtaining satisfactory trajectory tracking performance, a robust adaptive sliding mode FTC scheme is presented based on the backstepping sliding mode control technique and the closed‐loop system stability is rigorously proved via Lyapunov analysis. Simulation results are carried out to validate the effectiveness of the proposed control method. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a robust active fault‐tolerant control (AFTC) approach for medium‐scale unmanned autonomous helicopter (UAH) with rotor flapping dynamics in the presence of unknown external disturbances and actuator faults. The robust items are adopted to improve the disturbance rejection capability of the UAH system. The adaptive fault observers are developed to estimate the fault parameters and the fault detection (FD) algorithms are presented to detect the actuator faults in different loops. In order to obtain satisfactory trajectory tracking performance, a backstepping‐based robust AFTC scheme is designed for the simplified 6‐degree‐of‐freedom (DOF) UAH nonlinear dynamics model and the global stability of the closed‐loop system is proved by using the Lyapunov method. Several groups of numerical simulation results are carried out to verify the effectiveness of the developed method. [ABSTRACT FROM AUTHOR]

This paper addresses the suppressing problem of cable vibration and the positioning control design for a suspension cable system of a helicopter with disturbances. Hamilton's principle is applied to obtain a distributed parameter system for the suspension cable system of a helicopter. Two observers are employed to restrain the effect of unknown external disturbances. Based on the proposed disturbance observers and Lyapunov's direct method, two boundary control laws are designed, which are provided by the actuators at the top and bottom boundaries of the suspension cable, respectively. Under the proposed control laws, the oscillation amplitude and the error between the bottom boundary payload and the desired point are proven to be uniformly ultimately bounded. Moreover, they will converge to a small neighbourhood of zero by selecting proper design parameters. Meanwhile, some sufficient conditions are provided to guarantee the validity of the proposed control laws. Finally, simulation results show the rationality and effectiveness of the control scheme developed in this paper. [ABSTRACT FROM AUTHOR]

The problem of state feedback stabilization is studied for networked control systems (NCSs) subject to actuator saturation and network-induced delays. To facilitate the controller design, the NCSs are modeled as a class of discrete-time systems with bounded delays and input saturation. Based on Lyapunov-Krasovskii theory and free weighting matrix approach, the sufficient condition is derived in terms of linear matrix inequality for the asymptotic stability. Finally, the effectiveness of the developed control approach is proved through numerical examples. [ABSTRACT FROM AUTHOR]