Development of underwater robotic arm and leg for seabed robot, CRABSTER200

This paper presents the development of arm and leg of six-legged walking robot for precise seabed exploration and underwater works under coastal area with strong tidal current. For both seabed walking and precise underwater works, the seabed robot named CRABSTER200(CR200) uses six legs during walking and front two legs as manipulators during underwater work. To achieve the operation objective, the degree of freedom, dimensions, motion range, joint structure, and mass of the arm and leg are determined, and then suitable joint actuators and reduction gears are selected through a simple force analysis. In addition, a communication method, actuator controllers, and sensors are selected. The detailed mechanical design for 200m class pressure-resistance and watertight is performed, and the arms and legs are built by fabricating the mechanical parts and assembling them. Finally, in order to verify the performance of the arm and leg, the watertight test with 25bar pressure-resistance and joints operating test by using a posture control of CR200 are performed. This paper describes the whole design and implementation process of the underwater robotic arm and leg of the seabed robot CR200.