Uncertainty and Disturbance Estimator-Based Robust Control of Quadrotor without Velocity Measurements

In this paper, an uncertainty and disturbance estimator (UDE)-based position controller for quadrotors in the absence of velocity measurements is presented. Firstly, the nonlinear dynamics of a quadrotor is derived and simplified into a decoupled control design model using small angle approximation. Secondly, an UDE is constructed to compensate the system uncertainties and external disturbances. By applying passivity techniques to produce damping in the system, the proposed UDE-based controller can achieve trajectory tracking without velocity measurements and has a good robust performance. Moreover, the stability analysis of the closed-loop system is also introduced. Finally, the proposed method and the control method based on classical uncertainty and disturbance estimator are implemented and compared in the Gazebo simulation and flight experiment with a real quadrotor platform, are implemented and compared in the Gazebo simulation and flight experiment with a real quadrotor platform. Both simulation and experiment results demonstrate the effectiveness and advantages of the proposed control method in signal tracking and disturbance rejection.