  Accurate positioning of remotely operated underwater vehicles (ROVs) in
confined environments is crucial for inspection and mapping tasks and is also a
prerequisite for autonomous operations. Presently, there are no positioning
systems available that are suited for real-world use in confined underwater
environments, unconstrained by environmental lighting and water turbidity
levels and have sufficient accuracy for long-term, reliable and repeatable
navigation. This shortage presents a significant barrier to enhancing the
capabilities of ROVs in such scenarios. This paper introduces an innovative
positioning system for ROVs operating in confined, cluttered underwater
settings, achieved through the collaboration of an omnidirectional surface
vehicle and an ROV. A formulation is proposed and evaluated in the simulation
against ground truth. The experimental results from the simulation form a proof
of principle of the proposed system and also demonstrate its deployability.
Unlike many previous approaches, the system does not rely on fixed
infrastructure or tracking of features in the environment and can cover large
enclosed areas without additional equipment.
