Active Fault-Tolerant Control for a Quadrotor with Sensor Faults

An active fault-tolerant control scheme for a quadrotor with velocity sensor faults is presented in this paper. A two-level control scheme is designed to guarantee the quadrotor to track the given trajectory in case of no faults. The control scheme consists of an external-loop Proportion Differentiation (PD) control law and an internal-loop Proportion Integration Differentiation (PID) control law. A fault diagnosis unit is designed to detect and estimate sensor faults. The fault detection is achieved by using a Luenberger observer based residual generator and the fault estimation problem is solved by utilizing a new proposed augment variable observer. A sufficient condition on the existence of the augment variable observer is given based on Linear Matrix Inequalities (LMIs). The uniformly ultimately bounded property of state and fault estimation errors is proved. By combining the external-loop PD control law and the result of fault estimation, a fault-tolerant control law is proposed. Finally, the effectiveness of the scheme is demonstrated by the simulation and experimental results.