Automatic relative motion control and photogrammetry mapping on steep underwater walls using ROV

This paper describes an equipment setup and motion control strategy for automated visual mapping of steep underwater walls using a Remotely Operated Vehicle (ROV) equipped with a horizontally facing DVL to provide vehicle velocity and distance measurements relative to the underwater wall. The still images recorded by the stereo cameras of the ROV are post-processed into a 3D photogrammetry model using a combination of commercially available software and freeware. The system was implemented on an ROV and tested on a survey of a rock wall in the Trondheimsfjord in April 2016. The main scientific contribution is in the development of the motion control strategy for distance keeping using measurements from a DVL mounted in an arbitrary orientation.