Reactive Swarm Formation Control Using Realistic Surface Vessel Dynamics and Environmental Effects

Abstract

Abstract : This Trident Project focuses on the development of a controller for the coordination of a swarm of Autonomous Surface Vessels (ASVs) under mission and environmental constraints. For this research project, we first improved an existing Four Degree of Freedom (4DOF) vessel model. The model of a 360 metric ton patrol contains nonlinear hydrodynamics for the vessel's surge, sway, roll, and yaw motions. This model was modified to take into account environmental conditions including wind, waves and currents. Additionally, the control inputs of the model (propeller thrust, and desired ruder angle) were adapted for easier integration with a swarm level controller and additional nonholonomic motion constraints were applied to increase model fidelity. We then integrated this model into a simulated swarm of ASVs. It is the intention that this model will more accurately depict nonlinear vessel dynamics than did models used in previous ASV swarm studies. Using a redundant robot manipulator formulation, the swarm controller enables ASVs to travel in a formation with the intent of protecting and escorting a hypothetical asset. To provide flexibility, the controller is capable of modifying its overall formation shape and mission parameters in response to varying environmental conditions. The Atlantic Center for the Innovative Design and Control of Small Ships, a research initiative sponsored by the Office of Naval Research, plans to apply techniques and methods developed in this study towards the construction and testing of a physical swarm of ASVs.