The manta ray, Manta birostris, demonstrates excellent swimming capabilities; generating highly efficient thrust
via flapping of dorsally flattened pectoral fins. In this paper, we present an underwater robot that mimics the
swimming behavior of the manta ray. An assembly-based fabrication method is developed to create the artificial
pectoral fins, which are capable of generating oscillatory with a large twisting angle between leading and trailing
edges. Ionic polymer-metal composite (IPMC) actuators are used as artificial muscles in the fin. Each fin consists
of four IPMC beams bonded with a compliant poly(dimethylsiloxane) (PDMS) membrane. By controlling each
individual IPMC strips, we are able to generate complex flapping motions. The fin is characterized in terms of tip
deflection, tip blocking force, twist angle, and power consumption. Based on the characteristics of the artificial
pectoral fin, a small size and free-swimming robotic manta ray is developed. The robot consists of two artificial
pectoral fins, a rigid body, and an on-board control unit with a lithium ion rechargeable battery. Experimental
results show that the robot swam at a speed of up to 0.055 body length per second (BL/sec).
|