Gain-Scheduled Passive Fault-Tolerant Control Design for Dual-System UAV Transition Flight

Dual-system UAVs with vertical takeoff and landing capabilities have become increasingly popular in recent years. As a safety-critical system, it is important that a dual-system UAV can maintain safe flight after faults/failures occur. This paper proposes a gain-scheduled passive fault-tolerant control (PFTC) method for the transition flight of dual-system UAVs. In this FTC design method, the model uncertainties arising from loss of control effectiveness caused by actuator faults/failures are, for the first time, treated as model input uncertainties, enabling the use of multiplicative uncertainty descriptions to represent them. The proposed method offers the advantage of significantly reducing the number of design points, thereby simplifying the control synthesis process and improving the efficiency of FTC system design for dual-system UAV transition flight compared with existing methods. As a general approach, it can be applied to the design of FTC systems with multiple uncertain parameters and multiple control channels. The developed passive FTC system is validated on a high fidelity nonlinear six-degree-of-freedom simulator. The simulation results demonstrate that the gain-scheduled structured H∞ (GS SHIF) PFTC system provides superior fault-tolerant performance compared with LQR and structured H∞ control systems, thereby showcasing the effectiveness and the advantages of the proposed GS SHIF PFTC approach.