Relative Position Sensing and Automatic Control for Observation in the Midwater by an Underwater Vehicle

A vision-based automatic tracking and observation system installed on an ROV has successfully tracked midwater ocean animals (such as jellyfish) in Monterey Bay, California. This system uses stereo vision to localize the tracking vehicle with respect to the target of interest and closes control loops to maintain the target in the views of the cameras. The vision and control algorithms have been reported previously. This paper documents the partial redesign of the system in response to issues identified during extensive field testing of the system. The sensing system has been redesigned with the specific objectives of improving initialization, achieving better robustness to disturbances, and enabling tracking of smaller specimens. All of these improvements are achieved by redesigning the stereo camera system to increase significantly the volume that is viewable by both cameras. Also, an optional heading control loop now augments the control architecture to prevent sustained clocking of the vehicle due to disturbances in the tracking control system’s null space. With these design improvements, the automatic tracking and observation system has been fielded as a pilot aid on the ROV Ventana, and has proven capable of tracking specimens that vary widely in size, appearance and behavior.