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The fault detection and estimation problems for the physical layer network in the cyber-physical systems with unknown external disturbances are investigated in this study. Both bias fault and loss of efficiency scenarios are considered for the actuators. Based on the adaptive threshold method and sliding mode observer approach, a distributed fault detection observer (DFDO) is constructed for each physical layer node to detect the occurrence of actuator faults. Then a relative global estimation error system is defined for the distributed fault estimation observer (DFEO). Compared with the existing results, the proposed DFEO can provide the estimation for not only the actuator bias faults but also the actuators' efficiency factors under the impact of exogenous disturbance with two gain dynamic update processes. Finally, the feasibility and effectiveness of the given DFDO and the DFEO are examined by Lyapunov stability method and the simulation results. • Proposed a distributed robust fault detection observer for CPSs. • Proposed a distributed robust fault estimation observer for actuator faults of CPSs in this paper. • Both bias fault and loss of effectiveness fault are taken into consideration. [ABSTRACT FROM AUTHOR]

This study investigates a finite‐time fault‐tolerant control scheme for a class of non‐affine nonlinear system with actuator faults and unknown disturbances. A global approximation method is applied to non‐affine nonlinear system to convert it into an affine‐like expression with accuracy. An adaptive terminal sliding mode disturbance observer is proposed to estimate unknown compound disturbances in finite time, including external disturbances and system uncertainties, which enhances system robustness. Controllers based on finite‐time Lyapunov theory are designed to force tracking errors to zero in finite time. Simulation results demonstrate the effectiveness of proposed method. [ABSTRACT FROM AUTHOR]

In this paper, a decentralized fault-tolerant control (FTC) system is proposed for near-space vehicle (NSV) attitude dynamics. First, NSV reentry attitude dyna mic models with an uncertainty, actuator failure models, and a control surface damage model are described. Next, a new local fault identification algorithm is proposed to iden tify different types of actuator faults, which is based on multiobserver techniques. The local fault identification is constituted by a fault detection observer, fault parameter identification observers, and a decision-making mechanism. Then, a global adaptive sliding-mode observer is used to design the command filter backstepping fault- tolerant controller. Our focus is on the accommodation for actuator faults, control surface damage, uncertainties, and the resulting disturbances of the NSV. Finally, simulation results are given to demonstrate the effectiveness and poten tial of the proposed FTC scheme. [ABSTRACT FROM PUBLISHER]

• In the controller design, all the states of each vehicle are with constraints so as to fit the demands in real application. The proposed BLF-PPC control framework is a novel one in that the singularity problem in traditional PPC methods is solved by using an interval notion-based error transformation approach. To offset the disturbance, an interval observer-based identical reconstruction method is provided and the control input is decoupled from the reconstruction process. • During the attack diagnosis, the proposed virtual system functions as the ideal system which is immune from the FDI attack. Based on this, a fixed threshold-based attack detection method is realized. In addition, the detection process is simplified and the estimation for the authentication signal is eliminated. As for the attack estimation module, the estimation process can be done within a finite time and the accurate bound for the FDI attack is not necessary. • Differing from the existing fixed-threshold fault detection methods, a more accurate detection result can be ensured in this paper by importing the time-varying detection threshold. As for the fault estimation observer, the given intermediate variable even bridges the system states and the fault together such that the fault estimation is accomplished by the pure mathematical calculations of the system state and the intermediate variable. • In this paper, not only the FDI attack but also the actuator fault is considered. Due to the differences in the characteristics and the working mechanism, the impacts caused by FDI attack and actuator fault are discussed separately. This leads to the development of the attack and fault diagnosis modules. In addition, the resilient controller, attack and fault diagnosis modules can be designed separately. This paper investigates the full states-constrained resilient control for vehicle platoon systems with false data injection(FDI) attack, and actuator fault. A cyber-physical notion-based vehicle platoon system is firstly constructed. To meet the constraints for states and the transformed errors generated by the prescribed performance control(PPC) scheme, a novel PPC controller is constructed with barrier Lyapunov function(BLF). For eliminating the impact caused by FDI attack, a threshold-based attack detection mechanism including a virtual system, an authentication signal, and an attack detection filter, is developed. The amplitude of the FDI attack is then estimated by a finite time adaptive attack estimation observer. To offset the influence induced by actuator fault, an adaptive threshold-based fault detection observer is designed which reduces the false alarm ratio affected by external disturbance. Additionally, the amplitude of the actuator fault is estimated by an auxiliary variable-based fault estimation observer. By injecting the estimation of the FDI attack and actuator fault into the reference signal and controller, the resilient control is achieved. Finally, simulation results are given to exemplify the effectiveness of the control strategy. [ABSTRACT FROM AUTHOR]