To solve the problem of finite-time trajectory tracking control for quadrotor UAVs with actuator gain loss and bias fault, a Finite-Time Adaptive Sliding Mode Fault-Tolerant Control (FT-ASMFTC) is developed by combining fast terminal sliding mode control with a certainty equivalence adaptive mechanism. Adaptive laws are constructed to achieve real-time estimation of composite fault parameters, while hyperbolic tangent function is employed to suppress sliding mode chattering. Using finite-time Lyapunov stability theory, the closed-loop system states are rigorously proven to converge to the equilibrium point within a prescribed-time after the occurrence of faults. The adaptive process boundaries are constrained through the sliding mode surface, and the dependence of traditional adaptive control on precise fault parameter identification is overcome, achieving collaborative optimization of robust stability and finite-time convergence for the system with composite faults. Quantitative comparative analyses among FT-ASMFTC, Robust Global Fast Terminal Sliding Mode Control (RGFTSMC) and Asymptotic Adaptive Control (AAC) are given and demonstrate that the faulty system controlled by FT-ASMFTC method exhibits fast transient response, high steadystate accuracy, strong robustness, and good fault-tolerant control capability.

This paper investigates the issue of fault-tolerant control for swarm systems subject to switched graphs, actuator faults and obstacles. A geometric-based partial differential equation (PDE) framework is proposed to unify collision-free trajectory generation and fault-tolerant control. To deal with the fault-induced force imbalances, the Riemannian metric is proposed to coordinate nominal controllers and the global one. Then, Riemannianbased trajectory length optimization is solved by gradient’s dynamic model–heat flow PDE, under which a feasible trajectory satisfying motion constraints is achieved to guide the faulty system. Such virtual control force emerges autonomously through this metric adjustments. Further, the tracking error is rigorously proven to be exponential boundedness. Simulation results confirm the validity of these theoretical findings.

This paper presents the recent developments in Fault-Tolerant Cooperative Control (FTCC) of multiple unmanned aerial vehicles (multi-UAVs). To facilitate the analyses of FTCC methods for multi-UAVs, the formation control strategies under fault-free flight conditions of multi-UAVs are first summarized and analyzed, including the leader-following, behavior-based, virtual structure, collision avoidance, algebraic graph-based, and close formation control methods, which are viewed as the cooperative control methods for multi-UAVs at the pre-fault stage. Then, by considering the various faults encountered by the multi-UAVs, the state-of-the-art developments on individual, leader-following, and distributed FTCC schemes for multi-UAVs are reviewed in detail. Finally, conclusions and challenging issues towards future developments are presented.

The problem of fault-tolerant controller design for a class of polytopic uncertain systems with actuator faults is studied in this paper. The actuator faults are presented as a more general and practical continuous fault model. Based on the affine quadratic stability (AQS), the stability of the polytopic uncertain system is replaced by the stability at all corners of the polytope. For a wide range of problems including H_∞ and mixed H₂ / H_∞ controller design, sufficient conditions are derived to guarantee the robust stability and performance of the closed-loop system in both normal and fault cases. In the framework of the linear matrix inequality (LMI) method, an iterative algorithm is developed to reduce conservativeness of the design procedure. The effectiveness of the proposed design is shown through a flight control example.