Design and Development of Underwater Robotic Arm for Automated Camera Calibration for Aquatic Environment

This paper presents the design and implementation of a 4 degrees of freedom (DoF) robotic arm to assist in the calibration process for underwater cameras in aquaculture conditions. New imaging technologies with remarkable accomplishments have come to the forefront, offering a new field of research in underwater domain. To achieve accurate predictions using underwater cameras, it necessitates high estimations with proper camera calibration, especially in the aquatic environments where the challenges arise. Taking into consideration the necessity for accuracy in aquaculture image applications, a proper calibration system had to be made. In this work, we propose a novel, low-cost, user-friendly and easy to handle calibration process using an underwater robotic arm that calibrates the cameras with a pattern of known distances (checkerboard) as reference points. The arm consists of three revolute joints that can position the calibration pattern to the desired orientations, while a prismatic joint can steer it vertically. The system is designed and manufactured to operate in real conditions and has been evaluated at various aquaculture units in Greece, with highly relevant results.