Design of an Environmentally Responsive Grooming Tool to Aid in Underwater Navigation
Abstract
Underwater hull grooming is a proactive approach to ship hull husbandry. It has been
defined as the frequent and gentle wiping of a ship hull coating to maintain it free of fouling.
One of the challenges to implementing a grooming schedule is the control and navigation of
the devices over the surface of the hull. This thesis presents prior research that has developed
self-attaching rotating brushes as an effective method to groom fouling control coatings and
the results from several years of implementation in the marine environment. The hypothesis
of this thesis is that the condition of the ship hull surface can be interpreted by monitoring the
current draw of the grooming tool and that this information can be used to aid in navigation.
The present grooming tool design comprises five self-attaching rotating brushes that maintain
constant RPM by regulating current through a control system which monitors the back EMF
of a brushless DC motor. Experiments were performed to investigate the relationship between
current draw and surface condition by operating the grooming tool on artificial roughness’s
and fouling control coatings with known levels of biofouling. The results demonstrated that
coating type, coating roughness and biofouling type all contributed to the current draw by the
brush motor. This knowledge may be used to help locate the grooming device when
operating in a lawn mower type pattern.