A Visual Servo Algorithm for Underwater Docking of an Autonomous Underwater Vehicle (AUV)

J. Ocean Eng. Technol. 2003;17(1):1-7.

자율무인잠수정의 수중 도킹을 위한 비쥬얼 서보 제어 알고리즘

이판묵,전봉환,이종무

한국해양연구원 해양시스템안전연구소 해양개발시스템연구본부,한국해양연구원 해양시스템안전연구소 해양개발시스템연구본부,한국해양연구원 해양시스템안전연구소 해양개발시스템연구본부

Keywords: Visual Servoing, AUV(Autonomous Underwater Vehicle), Underwater Docking, Optimal Control, Optical Flow Equation

핵심용어: 비쥬얼 서보 제어, 자율무인잠수정, 수중 도킹, 최적제어, 광유동 방정식

Abstract

Autonomous underwater vehicles (AUVs) are unmanned, underwater vessels that are used to investigate sea environments in the study of oceanography. Docking systems are required to increase the capability of the AUVs, to recharge the batteries, and to transmit data in real time for specific underwater works, such as repented jobs at sea bed. This paper presents a visual :em control system used to dock an AUV into an underwater station. A camera mounted at the now center of the AUV is used to guide the AUV into dock. To create the visual servo control system, this paper derives an optical flow model of a camera, where the projected motions of the image plane are described with the rotational and translational velocities of the AUV. This paper combines the optical flow equation of the camera with the AUVs equation of motion, and deriver a state equation for the visual servo AUV. Further, this paper proposes a discrete-time MIMO controller, minimizing a cost function. The control inputs of the AUV are automatically generated with the projected target position on the CCD plane of the camera and with the AUVs motion. To demonstrate the effectiveness of the modeling and the control law of the visual servo AUV simulations on docking the AUV to a target station are performed with the 6-dof nonlinear equations of REMUS AUV and a CCD camera.