Quadrotor Tracking Control: Design and Experiments

This paper proposes a design method for a two-degrees-of-freedom tracking controller for a quadrotor to ensure trajectory following. The controller consists of two parts. A flatness-based feedforward controller ensures trajectory tracking of the undisturbed vehicle and a feedback controller composed of an altitude controller and a position and attitude controller in a cascaded structure compensates the tracking error due to disturbances and model uncertainties. The feedback controller is designed with the root locus method based on the linearized model of the quadrotor. Experiments are made in a testbed under windy conditions with a bounded windforce. The results show that the quadrotor with the proposed controller follows a given trajectory closely with small, bounded deviations, which can be estimated in advance with the model of the quadrotor.