A nonlinear quadrotor trajectory tracking controller with disturbance rejection

This paper addresses the problem of designing and experimentally validating a controller for steering an autonomous quadrotor vehicle along a time-dependent trajectory, while rejecting constant force disturbances. The proposed solution consists of a nonlinear adaptive state feedback controller that asymptotically stabilizes the closed-loop system and ensures perfect tracking even in the presence of force disturbances. We consider quadrotors vehicles actuated in thrust and angular velocity, and ensure that the actuation does not grow unbounded as a function of the position error. The constant force disturbance is estimated through the use of a smooth projector operator. We build a rapid prototyping and testing environment to streamline the implementation and the tuning of the control laws and present experimental results to demonstrate the performance and robustness of the proposed controller.