In recent years, biological research of an aquatic life
is carried out actively. The sea is a dangerous environment for
humans, so that we cannot investigate an aquatic life for a long
period of time. In addition, conventional underwater robots have
a common mechanism for propulsion with screw propellers.
Noises generated by screw propellers have a possibility of giving
a bad effect on the biological behavior. On the other hand,
biomimetic robots can investigate aquatic lives without affecting
them significantly. Our laboratory has developed a Manta robot
that has propulsion mechanisms with pectoral fins, mimicking
the pectoral fin of the manta ray. Conventional Manta robots
have a problem that its swimming speed is insufficient for
investigating aquatic lives. In this paper, we develop an
autonomous Manta robot that is excellent in the propulsion
performance by taking account of propulsion resistance caused
by the body shape. Several experiments are conducted to show
the effectiveness of the proposed method, in the point of the
swimming speed and propulsive efficiency