Resilient Recovery Control for Fixed-Wing UAV Formations in the Event of Actuator Failures

Formations of fixed-wing unmanned aerial vehicles (UAVs) must maintain mission-level coordination despite actuator degradation, bias faults, model uncertainty, wind disturbances, and command limits. This study presents a mission-oriented formation-recovery framework. Acceptable relative position and velocity performance is represented by an ellipsoidal tolerance set, and resilient formation recovery time (RFRT) is the elapsed time from fault onset to the first permanent re-entry into that set. The controller generates relative demand commands that are reconstructed from the parent limited command and then clipped componentwise. A second-order edge-based extended state observer, driven by the relative limited command, estimates the physical edge fault–disturbance mismatch, while the command-saturation residual is retained explicitly in the closed-loop analysis. A distributed fault-tolerant controller combines linear recovery feedback, observer-based compensation, and a continuous robust term. The analysis uses a finite Lyapunov energy-jump inequality at step-fault instants and an upper-right Dini derivative at saturation breakpoints to establish uniform ultimate boundedness, a sufficient recovery-set inclusion condition, and an RFRT upper bound. In the one-leader–four-follower baseline simulation, permanent re-entry occurs at 22.3313 s, corresponding to an RFRT of 2.3313 s. Relative to Edge-ESO-FTC, the proposed method reduces the post-fault peak metric by 61.2%, RFRT by 25.2%, cumulative position deviation by 54.6%, and out-of-bounds duration by 67.7%.