Actuator Fault-Tolerant Control in Hexacopters Based on Directional Residual Analysis Under External Disturbances

Abstract

This paper presents an active fault diagnosis and fault-tolerant control scheme for a hexacopter under severe actuator efficiency losses and environmental disturbances. The proposal combines an asymptotic state observer with an isolation algorithm based on directional cosines, enabling a geometric interpretation of residual signals, shielded by a time-latching mechanism with an anti-reduction barrier to prevent disturbance-induced false positives. In the presence of critical faults, the control reconfigures the allocation matrix via pseudoinverse, ensuring lateral-longitudinal stability. The scheme is numerically validated across four operational scenarios combining wind gusts and total faults. The results demonstrate the effectiveness of the memory-based logic in retaining the correct diagnosis under concurrent turbulence, guaranteeing aircraft survivability.