Fault Tolerant Control in Over-Actuated Hybrid Tilt-Rotor Unmanned Aerial Vehicles

Quad-planes combine hovering and Vertical Takeoff and Landing (VTOL) capabilities with efficient forward flight. However, they are often vulnerable to gust disturbances and are not well-equipped to handle actuator faults. Dual-axis Tilt-Rotor quad-planes offer enhanced maneuverability due to their overactuation, which also enables stable hovering even after actuator failures. These vehicles can employ an Incremental Nonlinear Dynamic Inversion (INDI ) controller paired with a nonlinear Sequential Quadratic Programming (SQP ) Control Allocation (CA ) algorithm that can find hover solutions under actuator failure conditions. We explore both a combined allocation of linear and angular accelerations and a cascaded allocation scheme. Due to the large required changes in roll and pitch angles, the cascaded approach is selected for this research. The proposed algorithm was tested on a flying vehicle, demonstrating successful hovering and position control capabilities under a simulated Fault Detection and Identification (FDI) mechanism.