Robust Output Feedback Control for Attitude Tracking of a Quadrotor UAV

This work proposes a new robust output feedback control method for attitude reference tracking of a quadrotor unmanned aerial vehicle without using the angular velocity measurements. By using the K-filters well known in the adaptive control community, the necessity of velocity measurements or estimating is avoided. The attitude system model is transformed into a second-order model where the angular velocity measurements are not involved. However, the model includes mismatched uncertainties which should be estimated and compensated by the disturbance observers. The controller is designed in a backstepping manner, and the dynamic surface control technique is adopted to avoid the explosion of the controller complexity. For each Euler angle, the prescribed performance control technique is adopted to ensure a prescribed performance. The control performance of the overall control system is analyzed rigorously from the viewpoint of input-to-state practical stability. And simulation examples are provided to demonstrate the performance of the proposed method.