On the Coordination of Constrained Fixed-Wing Unmanned Aerial Vehicles

Abstract

A formal distributed control methodology to coordinate a team of fixed-wing UAVs (Unmanned Aerial Vehicles) in a three-dimensional workspace is addressed. The complete task to be accomplished is divided in three stages: (i) each UAV tracks a circle parallel to the \(xy\) plane in a given altitude (different altitudes for different UAVs); (ii) the UAVs distribute themselves in such a way that their projection onto the \(xy\) plane are evenly spaced around a circle; (iii) each UAV converges to the same altitude to track the same circle. The main contribution of this work lies in the mathematical proofs of the proposed strategy for a given UAV model. We consider minimum and maximum limits in the forward speed command, maximum limit in the absolute value of the yaw rate, maximum limit in the absolute value of the altitude speed, second-order dynamics, and a non-holonomic constraint. Stability and collision avoidance are guaranteed during the whole task including the stage transitions and without violating the constraints. Simulation results are given to illustrate the proposed approach.