Cooperative Motion Control of Multiple Autonomous Marine Vehicles: Collision Avoidance in Dynamic Environments

This paper addresses the problem of cooperative motion control (CMC) of multiple autonomous marine vehicles, taking explicitly into account collision avoidance in dynamic environments. A Collision Avoidance System (CAS) for a CMC architecture is proposed that consists of two subsystems: Collision Prediction and Collision Avoidance. Collision Prediction aims at estimating the most probable trajectory of a given obstacle. To this effect, a bank of Kalman filters are run in parallel, with each filter using a different plausible model for obstacle motion. The most probable model is chosen according to a decision algorithm. Each of the vehicle trajectories is then checked for possible collision with the obstacle. Should the possibility of a collision occur, Collision Avoidance is achieved either by controlling the speed of each vehicle along its assigned path or through path re-planing using harmonic potential fields. Because group coordination must be taken into consideration, collision avoidance is implemented using a decentralized system that is suited for multiple heterogeneous vehicles. The paper summarizes the key concepts and the methodology used to implement a Collision Avoidance System for teams of vehicles. The efficacy of the system is assessed in simulation with dynamic models of a group of marine surface craft using NetMarSys, a Cooperative Motion Control Simulator developed at ISR/IST.