A Robust Vision-Based Hover Control for ROV

The main field of application for small- and middle-class ROVs is the inspection of underwater structures or other objects of interest. Approaching such an object, one would want to hold a steady position in front of the object to study it in detail without having to concentrate on the control of the vehicle. This kind of "hover control" could be implemented by using an inertial measurement unit (IMU), but most of the small-and middle-class ROVs do not have one. Furthermore, even the best IMUs tend to drift. On this account our approach, which is presented in this paper, uses video data to estimate the movements of the vehicle and uses these data to keep the vehicle hovering in front of a particular structure. The used vision algorithms are aimed at real world applications and are robust enough to handle various light and visibility conditions.