Disturbance Observer Based Fault Tolerant Control of a Quadrotor Helicopter

In this paper, a fault tolerant control system for a quadrotor helicopter is developed. Fault tolerant controllers have many advantages over regular controllers for keeping midair flight safety and increasing mission reliability. A high-fidelity nonlinear model of a quadrotor is constructed using Newton-Euler formulation where Dryden wind effects and sensor noise are included to simulate real-world fight conditions. For managing accurate full state estimations, an Extended Kalman Filter is utilized. To increase robustness to external disturbances and uncertainties in the plant dynamics, a Velocity-based Disturbance Observer (VbDOB) is constructed and combined with the control law. Simulations carried out with the high fidelity model have shown that the proposed method has successfully compensated for actuator faults in a trajectory tracking task, and hence provides good tracking performance with a feasible control effort.