Visual Servoing of an ROV for Servicing of Tethered Ocean Moorings

This paper presents an approach for shared control of a Remotely Operated Vehicle (ROV) to assist the vehicle´s pilots in servicing of moored underwater platforms. By providing precise automatic control of the ROV with respect to the mooring, a shared control system is established such that the ROV hovers automatically with respect to the mooring and the pilot is free to focus only on the manipulation tasks. The positioning system uses a single calibrated camera to measure bearings to several fiduciary markers on a test mooring of known position in the mooring´s coordinates. An Unscented Kalman Filter (UKF) fuses these bearing measurements with vehicle sensors such as compass, inclinometers and rate gyros to estimate the relative position and orientation of the mooring with respect to the ROV. The approach leverages technology that has been presented previously for vision-based automatic tracking and observation of deep ocean animals. Results from simulation and field trials of this positioning system using the ROV Ventana in Monterey Bay are presented