Active Fault Diagnosis and Control of a Morphing Multirotor Subject to a Stuck Arm

In this paper, we propose a fault tolerant control law for a morphing quadrotor, where the considered morphing ability is that of extendable/telescopic arms. This quite recent class of systems is able to provide a good trade-off between payload capabilities, maneuverability, and space occupancy. However, such degrees of freedom require dedicated servomotors, which in turn implies more possible faults. Thus, the problem of diagnosis for the telescopic servo motors subject to a stuck fault is considered. System symmetries are exploited and used in a residual generator design, which triggers an active fault isolation/identification phase. External disturbances are also taken into account and estimated through a nonlinear disturbance observer. A classical double-loop controller closes the loop, providing an overall control system structure that follows the disturbance observer-based control paradigm. The control scheme is validated through realistic numerical simulations, and the closed-loop performances are analyzed.