The stabilization of attitude of a Manta robot by a mechanism for moving the center of gravity and improvement of diving ability

The development of underwater robots has been required for biological research in the sea. Therefore, it needs biomimetic robots because they hardly affect the behavior of creatures. We have developed a Manta robot that has propulsion mechanisms with pectoral fins, mimicking the pectoral fin of the manta. The conventional Manta robot is influenced by a righting moment varies according to the distance between the center of gravity (c.g) and the center of buoyancy. The righting moment keeps an object in the water in a certain posture. If the righting moment is large, the diving ability is reduced, so that the Manta robot is expected to not follow the movement of any organism. On the other hand, if the righting moment is small, the stability of the posture is insufficient, so that it is difficult to acquire the camera image. Therefore, we improve the diving ability of the Manta robot as well as stabilizing the posture, by changing the righting moment due to adjusting c.g. In this paper we explain the mechanism for moving c.g, and the way to adjust c.g. Furthermore, several swimming experiments are conducted, using the Manta robot equipped with the mechanism for moving c.g.