Uniform Fault-Tolerant Control of a Quadcopter With Rotor Failure

This article provides a uniform fault-tolerant controller for a quadcopter without controller switching in case one rotor fails completely. The fault-tolerant control adopts control allocation based on an optimization method as the core of control. It will abandon the yaw channel when a rotor fails completely, for which the motion characteristics of the free-rotation quadcopter and the degree of controllability are analyzed. For practical implementation, the rotor dynamics have been further taken into consideration as first-order dynamics and then a compensator is used to improve the rotor response. To validate the proposed controller, first, digital simulation studies are conducted to verify the control logic. Second, the hardware-in-the-loop simulation highlights the feasibility and high efficiency of the fault-tolerant control method on an embedded system. Finally, an outdoor experiment with onboard sensors and GPS demonstrates that the fault-tolerant controller has the ability to make quadcopters fly safely when an arbitrary rotor fails completely.