Dual-Coordinated Prescribed-Time Fault-Tolerant Control for Redundant UAVs Under Actuator Faults

In this paper, an innovative dual coordinated prescribed-time fault-tolerant control framework is proposed for redundant unmanned aerial vehicles (UAVs) subjected to non-vanishing disturbances, actuator faults, and mismatched control signals (MCS). First, a less restrictive criterion for prescribed-time stability is introduced and integrated with the backstepping technique to formulate a novel prescribed-time control (PTC) algorithm for redundant UAVs. The proposed PTC algorithm features a user-specified prescribed time, independent of initial conditions and control parameters, and is characterized by the elimination of singularity issues and excessive initial control input. Second, the proposed enhanced prescribed-time control barrier function-based control allocation (PTCBF-CA) framework transforms the CA issue into an objective function that must be optimized within a specified time. Additionally, it allows actuator constraints to be formulated as a forward invariance set, ensuring that actuator states remain within a safe set at all times. Then, MCS resulting from actuator saturation and faults is coordinated by enhanced PTCBF-CA and PTC algorithm: the former penalizes the absolute values of MCS-related terms within the optimization cost function, while the latter employs these absolute values as new bounds on tracking errors, thereby enhancing system performance or mitigating performance degradation to the fullest extent. Finally, the effectiveness of the proposed control scheme is verified by simulation.