Temporally and Spatially Deconflicted Path Planning for Multiple Autonomous Marine Vehicles

There is currently a surge of interest in the development of advanced systems for cooperative control of multiple autonomous marine vehicles. Central to the implementation of these systems is the availability of efficient algorithms for multiple vehicle path planning that can take explicitly into account the capabilities of each vehicle and existing environmental conditions. Multiple vehicle path planning methods build necessarily on key concepts and algorithms for single vehicle path following. However, they go one step further in that they must explicitly address inter-vehicle collision avoidance, together with a number of criteria that may include simultaneous times of arrival at the assigned target points and energy minimization, to name but a few. As such, they pose considerable challenges both from a theoretical and practical implementation standpoint. This paper is a short overview of multiple vehicle path planning techniques. The exposition is focused on specific algorithms developed in the scope of research work in which the authors have participated. Namely, algorithms that ensure that at no time will two vehicles get closer in space than a desired safety distance, that is, achieve trajectory deconfliction. The algorithms make ample use of direct optimization methods that lead to efficient and fast techniques for path generation using a polynomial-based approach. The paper affords the reader a fast paced presentation of key algorithms that had their genesis in the aircraft field, discusses the results of simulations, and suggests problems that warrant further consideration.