Visual servoing for underwater docking of an autonomous underwater vehicle with one camera

Docking systems are required to increase the capability of autonomous underwater vehicles (AUVs) to recharge the batteries and to transmit data in real time in underwater. This paper presents a docking system for an AUV to dock into an underwater station with one camera installed at the nose center of the AUV. To make a visual servo controller, this paper presents an optimal control algorithm based on a state equation composed of the AUV dynamics and the optical flow equation. The control inputs of the AUV are generated with the projected target position on the CCD plane of the camera and with the AUVs motion. This paper introduces a test bed AUV for underwater docking developed in Korea Research Institute of Ships and Ocean Engineering (KRISO), KORDI of Korea. The AUV is propelled with one thruster and controlled with two horizontal planes and two vertical planes. Experiments will be performed in Ocean Engineering Basin of KRISO to demonstrate the effectiveness of the modeling and control law of the visual servoing AUV. The AUV identifies target position with processing the captured image of the lights mounted around the entrance of the dock. This paper also presents a strategy to identifier the target with lights arrays.