This study investigates the fault detection and fault estimation problem of a quadrotor with disturbances. A synthesized design of adaptive and sliding-mode observer is proposed to address the effective detection and estimation of incipient faults. First, the decomposed subsystems are obtained through the coordinate transformation, and the initial and incipient faults are separated from the disturbances. Second, an adaptive observer is applied to the decomposed unperturbed subsystem to estimate incipient faults, while the sliding-mode observer remains robust to disturbances for the perturbed subsystem. Lyapunov stability theory ensures the convergence of dynamic errors and the stability of the quadrotor system. Finally, the effectiveness of the proposed synthesized algorithm of incipient fault detection is verified by the quadrotor simulation.

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Decentralized Fault Estimation and Distributed Fault-tolerant Tracking Control Co-design for Sensor Faulty Multi-agent Systems with Bi-directional Couplings 3 the following condition, i.e., llg(x;(t),t)-g(x o (t),t) II � JLll x;(t) -XQ(t) 11-(iii) The external disturbance do(t) of the leading agent is .C2[ 0 , oo ) bounded. DECENTRALIZED FAULT ESTIMATIONAccording to the differentiable sensor fault f s ; (t) in (1), the sensor fault can be actively hidden in the ex tended state through the following augmented transforma tion. The dynamics of the following one are extended as

Summary The purpose of this study is to discuss the fully distributed design of output estimation error observer and fault‐tolerant consensus tracking control for a class of multi‐agent systems with Lipschitz nonlinear dynamics and actuator faults. Firstly, based on the relative output measurements of neighboring agents, the distributed output estimation error observer is developed to adaptively estimate the state and fault information of each agent, and further overcome the difficulties of online updating the adaptive estimations of unknown hyper‐parameters. Secondly, to achieve the state consensus tracking goal and compensate for the negative effects of actuator faults, the distributed fault‐tolerant consensus tracking control scheme is proposed on the basis of the state estimation and adaptive fault estimation information, and has excellent robustness and consensus tracking control performance. Moreover, sufficient criteria can ensure that consensus tracking error of each agent converges to a small set near the origin. Finally, numerical simulations are provided to show the effectiveness of the proposed fully distributed algorithm.