Online Gain Reconfiguration Using Incremental Attainable Acceleration Sets for Active Fault-Tolerant Flight Control

Actuator faults can reduce aircraft control authority and render nominal feedback demands unattainable. This study develops an online gain-reconfiguration method using an incremental attainable acceleration set (IAAS) constructed from aerodynamic control effectiveness and actuator position and rate constraints. The IAAS supplies directional acceleration limits for an analytical inner-loop gain update, while an outer-loop update maintains a prescribed bandwidth separation. A set-theoretic Lyapunov formulation distinguishes attainable accelerations from stabilizing ones and provides a necessary and sufficient condition for their intersection to be nonempty. Under stated realization and authority assumptions, the inner-loop analysis establishes an attractive tracking-error set and convergence for constant references. For the channel model underlying the outer-loop design, a Routh–Hurwitz condition characterizes the admissible gains of the fixed-parameter closed loop. Nonlinear F-16 simulations examine three lock-in-place fault scenarios and separately assess reporting delays of 0.1–0.3 s. In these scenarios, the reconfigured controller maintains bounded responses and follows the maneuver commands, whereas the fixed-gain responses develop growing excursions. The results demonstrate the method in the investigated conditions.