Consensus tracking control for multiple UAVs demonstrates critical theoretical value and application potential, improving system robustness and addressing challenges in complex operational environments. This paper addresses the challenge of event-triggered prescribed-time synchronization tracking control for 6-DOF fixed-wing UAVs with state constraints. We propose a novel prescribed-time command filtered backstepping approach to effectively tackle the issues of complexity explosion and singularities. By utilizing a state-transition function, we manage asymmetric time-varying state constraints, including limitations on speed, roll, yaw, and pitch angles in UAVs. The theoretical analysis demonstrates that all signals in the 6-DOF UAV system remain bounded, with tracking errors converging to the origin within the prescribed time. Finally, simulation results validate the effectiveness of the proposed control strategy.

The cooperative flight of manned and unmanned aerial vehicles (MAV/UAVs) has recently become a focus in the research of civilian and humanitarian fields, in which formation control is crucial. This paper takes the improvement of convergence performance and resource conservation as the entry point to study control problems of cooperative formation configuration of MAV/UAVs. Following the backstepping recursive design procedures, an event-triggered fixed-time formation control strategy for MAV/UAVs operating under modeling uncertainties and external disturbances is presented. Moreover, a novel switching threshold event-triggered mechanism is introduced, which dynamically adjusts control signal updates based on system states. Compared with periodic sampling control (Controller 1), fixed threshold strategies (Controller 2) and relative threshold strategies (Controller 3), this mechanism enhances resource efficiency and prevents Zeno behavior. On the basis of Lyapunov stability theory, the closed-loop system is shown to be stable in the sense of the fixed-time concept. Numerical simulations are carried out in Simulink to validate the effectiveness of the theoretical findings. The results show that compared with the three comparison methods, the proposed control method saves 86%, 34%, and 43% of control transmission burden respectively, which significantly reduces the number of triggered events.

This study proposes a cross-scale reinforcement strategy for ultra-high-performance concrete (UHPC) using polyoxymethylene fibers (POMFs) and cellulose nanofibers (CNFs). The mechanical behavior and cross-scale synergistic reinforcement mechanisms of POMF/CNF-reinforced UHPC are systematically investigated through compressive, three-point bending, and split Hopkinson pressure bar (SHPB) tests, together with thermogravimetric (TG) analysis, scanning electron microscopy (SEM), and pore structure characterization. The results show that POMFs improve the post-cracking load-bearing capacity of UHPC through macroscopic crack bridging and pullout-induced energy dissipation, thereby transforming the failure mode from brittle to quasi-ductile. The incorporation of CNFs further enhances the matrix strength and flexural performance. At a CNF content of 0.2 wt.%, the compressive and flexural strengths of POMF-reinforced UHPC increase by 9.7% and 21.9%, respectively. Under high strain rates, the POMF-CNF composite system exhibits a pronounced strain-rate strengthening effect. In particular, UHPC containing 2 vol.% POMFs and 0.2 wt.% CNFs achieves both high dynamic load-bearing capacity and energy dissipation capacity, with an impact toughness of 5.2 MJ/m³ at a high strain rate. Microstructural results indicate that CNFs improve matrix compactness and resistance to microcracking by promoting hydration, refining the pore structure, and providing nanoscale bridging. They also enhance stress transfer across the POM fiber–matrix interface, which acts synergistically with the macroscopic crack-bridging effect of POMFs to produce cross-scale toughening. This study provides a reference for the cross-scale design of UHPC with high strength, high toughness, and superior resistance to dynamic damage.