On the Design of Outdoor Leader-Follower UAV-Formation Controllers From a Practical Point of View

This work presents a control structure designed to autonomously guide two of-the-shelf quadrotors navigating in outdoor environments, as a leader-follower formation. The objective is to show how simple is to design controllers to guide the two vehicles when taking into account practical assumptions and simplifications in their model. This way, the main contribution of the paper is to show how practical knowledge obtained from real experiments using of-the-shelf quadrotors, translated to the assumptions and simplifications applied to its model, can help in the design of a suitable controller. The basic premise is that the quadrotor is driven by high-level commands that excite its degrees of freedom. The control system here designed following such reasoning is implemented in a ground station that allows manual or automatic control of the leader vehicle, with the follower one always automatically controlled. Experimental results in real outdoor scenarios, subject to unpredicted disturbances, validate the assumptions and simplifications applied to the model of the quadrotor, and the proposed control structure as well.