Active Fault-Tolerant Tracking Control of an Unmanned Quadrotor Helicopter under Sensor Faults

Abstract

This paper is devoted to the design of a nonlinear active fault-tolerant tracking control (AFTTC) scheme for an unmanned quadrotor helicopter (UQH) under sensor faults. The proposed AFTTC scheme is divided into two loops, where the outer loop and inner loop controllers are designed for the position control and the attitude control, respectively. The sliding mode control (SMC) algorithm is introduced to make the UQH track the desired trajectory and yaw angle, and to stabilize the pitch and roll motions. For implementing the active fault-tolerant control, a fault detection and diagnosis (FDD) scheme is constructed by utilizing a robust three-step unscented Kalman filter. Based on the precise fault information, the SMC-based control laws are updated online to mitigate the adverse effects of sensor faults. Simulation results show that the proposed AFTTC scheme works well in both normal and different faulty scenarios.