This study introduces a novel adaptive fuzzy fault-tolerant controller designed for tailless aircraft's attitude tracking problem, even in the absence of angular velocity measurements. The controller addresses challenges posed by external disturbances, model uncertainties, and actuator faults. Initially, we propose a fixed-time sliding mode differentiator to estimate unmeasured angular velocity. Model uncertainties and external disturbances are approximated using fuzzy logic systems. Subsequently, a nonsingular fixed-time adaptive fuzzy fault-tolerant control scheme is developed based on the backstepping theory, which actively mitigates the impact of actuator faults, resulting in superior attitude tracking performance. The theoretical foundation of the proposed control scheme guarantees the boundedness and convergence of all closed-loop attitude control system states to a confined region around the origin within a fixed time. Notably, this convergence is achieved regardless of initial errors. Finally, simulation examples are presented to verify the effectiveness of the estimator and controller.

This work develops a morphing decision strategy to optimize the cruising efficiency for a variable-sweep morphing aircraft, and a simple and practical guidance and control system is given as well. They can work in tandem to accomplish a cruise mission effectively. To make the morphing decision accurately, we take into account the equilibrium equations of forces; the variations in airspeed, altitude, and mass and the optimal configurations for different cruise conditions are solved based on the nonlinear programming method with the objective of minimum engine thrust. Considering that a large amount of computational resources are required to solve the nonlinear programming problems, we establish an offline database of the optimal configurations and design a database-based online morphing decision process. In addition, the proposed morphing decision strategy includes an anti-disturbance mechanism, which ensures that the optimal configuration can be given accurately without chattering under fluctuating airspeed measurements. Comparative results from the simulations finally validate the effectiveness of the proposed strategy.

This work investigates the short-term dynamics caused by shape changes of morphing aircraft. We select a symmetric variable sweep morphing aircraft as the object of study and establish a six-degree-of-freedom multi-loop cascade model, and the coupling between derivative terms is eliminated by matrix transformation. Considering that the change in aerodynamic shape significantly affects the aerodynamic forces of the aircraft in a short period of time, and the variation in mass distribution generates additional aerodynamic forces and moments, we analyze the effects of these factors on the dynamic characteristics of the aircraft based on the open-loop response starting from the steady-state flight conditions. In addition, we analyze the improvement in maneuvering performance brought by morphing as an additional control input. We apply reachable set theory to multi-loop equations of motion and use the size of the reachable set to measure the maneuverability of aircraft. The results confirm that morphing can effectively improve the maneuverability of the aircraft.

This paper proposes an adaptive fuzzy fault-tolerant attitude control scheme for the fixed-wing unmanned aerial vehicles (UAVs) in the presence of external disturbance, uncertain parameters, and time-varying actuator failures. Firstly, a control-oriented attitude control model based on the six-degree-of-freedom (6-DOF) dynamics model of the UAVs is established, then the external disturbance, uncertainty, and time-varying actuator failures are transformed into a lumped uncertainty. Subsequently, an approximator is constructed by employing the fuzzy logic systems, meanwhile, a robust term is introduced to improve the tracking performance. The Lyapunov stability analysis shows that all the signals of the closed-loop system are uniformly ultimately bounded. Finally, simulations are conducted to validate the effectiveness and superiority of the proposed strategy.

​​​​​​​This paper proposes an optimization method for the Equality Set Projection algorithm to compute the orthogonal projection of polytopes. However, its computational burden significantly increases for the case of dual degeneracy, which limits the application of the algorithm. Two improvements have been proposed to solve this problem for the Equality Set Projection algorithm: first, a new criterion that does not require a discussion of the uniqueness of the solution in linear programming, which simplifies the algorithm process and reduces the computational cost; and second, an improved method that abandons the calculation of a ridge's equality set to reduce the computational burden in the case of high-dimensional dual degeneracy.