Path tracking for waypoint lists based on a pure pursuit method for fixed wing UAS

This paper introduces a method for path tracking based on a basic pure pursuit (PP) algorithmic strategy. To increase the robustness and reliability in coverage and tracking tasks using multiple Unmanned Aerial Systems (UAS), several criteria must be taken into consideration, like safe separation between the vehicles and complete area coverage based on their on board sensors. In this context, we propose a guidance strategy where initially a straight line path between previously calculated waypoints for coverage tasks is calculated. Then, for each next turn of the vehicle, a goal point is chosen in order to minimize a deviation error from the straight line path and the current position of the vehicle. In order to calculate this point, an offline lookup table is created, which correlates the underlying control model with the turn angles; during flight, the best value is chosen for each next turn. The algorithm has been tested in different scenarios and against a robust simulation framework by the means of Software-in-the-Loop (SITL). The results show that this strategy manages to provide a computationally inexpensive method for the goal points of the pure pursuit algorithm and minimizes the deviation from the straight line trajectories of the waypoint planning.