Spiral Search Pattern for Scalable Assemblages of Uncrewed Surface Vehicles

A spiral search algorithm has been developed for one or more cohesive formations of one to three vehicles. The technique was developed for a specific uncrewed surface vehicle that dives to take measurements, but it can be applied to any type of vehicle and measurement technique limited to sampling a scalar field at discrete points instead of continuously recording a time series. A formation, or cluster, of three vehicles was used as a basis of the search pattern, so the pattern itself was arranged upon a triangular grid. In practice, the algorithm provides cluster-coordinate measurement waypoints for each formation, and a lower-level controller directs commands to the individual vehicles. Each cluster search is deemed successful if any vehicle within the cluster reports an elevated measurement beyond some threshold used to define the goal of the search. By extension, multiple clusters could each locate features in the same mission. Although a search does not require a full cluster of three vehicles, the subsequent characterization phase utilizes higher-order quantities such as field gradients, which can be estimated from simultaneous measurements by a formation of vehicles. For this reason, using a cluster during the search allows for an immediate transition to the next mission phase once the feature is located.