Leader–Follower Trajectory Control for Quadrotors via Tracking Differentiators and Disturbance Observers

In this paper, both a trajectory tracking controller and a position controller are investigated for leader-follower trajectory control of quadrotors. A tracking differentiator is designed to generate speed signals for the quadrotors which are composed of a leader and some followers. Based on state errors between the leader and followers, a nonlinear disturbance observer is used in the trajectory tracking controller. A saturation law with anti-trigonometric functions is adopted in the position controller for the leader and followers. Experiment results are given to show the applicability of the proposed method for quadrotors.