In this paper, an approach for the autonomous motion planning for an underwater manipulator is proposed. An aim of this approach is to decide tip positions of the manipulator and manipulator's postures in the water. Therefore this approach is composed of the tip position planning and the posture planning. And in order to execute each planning, a workspace of a manipulator is divided into cubes. In the tip position planning, a cube is selected as an objective tip position from among twenty-six cubes in the workspace. And in the posture planning, manipulator's postures are evaluated using the positional relation between the manipulator and obstacle domains defined by some cubes, so that a secure manipulator's posture to avoid obstacle is decided. And owing to executing each planning repetitively, the whole manipulator's motion is planned. In this paper, the validity of the proposed approach is shown in experimental results.
