Proposal of Several Swimming Methods for a Disk-shaped Underwater Robot with an Annular Pectoral Fin Propulsion Mechanism

In a conventional manta ray robot with a pectoral fin propulsion mechanism, the periodic pitch motion during swimming adversely affected the accuracy of optical flow calculations using a camera. To solve this problem, an underwater robot with an annular pectoral fin propulsion mechanism was developed, in which the shape of the robot is a disk with low fluid resistance and is surrounded by pectoral fins. In this study, we first describe how floating and sinking motions that are possible with a conventional manta ray robot can be realized using the developed underwater robot. Next, we propose a new control method for floating and sinking motions using the annular pectoral fin propulsion mechanism and a control method to reduce the pitch motion generated during forward motion by the tail fin, respectively. Finally, several in-water experiments in a swimming pool are conducted to confirm the effectiveness of the proposed methods.