Evaluation of Artificial Caudal Fin for Fish Robot with Two Joints by Using Three-Dimensional Fluid-Structure Simulation

Abstract

A fish robot with image sensors is useful to research for underwater creatures such as fish. However, the propulsion velocity of a fish robot is very slow compared with live fish. It is necessary to swim at a speed several times faster than the speed of the current robots for various usages. Therefore, we are searching for the method of making the robot swim fast. The simulation before making the robot is important. We have made the computational simulation program of three-dimensional fluid-structure analysis. The flow around the caudal fin can be examined by analyzing the fin as an elastic body. We compared the results of numerical analysis with the results of PIV measurement. Both were agreed well. Because the performance of a fish robot with two joints is better than that of a fish robot with one joint, we searched for an excellent fin for the fish robot with two joints by using CFD. We confirmed that the swimming performance of a fish robot becomes very good when the caudal fin is rigid except for the root of the fin which is comparatively flexible.

Small Robotic Fish with Two Magnetic Actuators for Autonomous Tracking of a Goldfish

“…The central part of the tip of the tail fin is made softer than others. [11] The tail fin is connected to the main body by two joints [12][13] and each joint drives independently. COMET can bend the tail fin by up to 90 degree by these two joints.…”

Position Estimation of Small Robotic Fish Based on Camera Information and Gyro Sensors

“…However, the performance of a fin is still inferior to that of a screw propeller, and we are currently investigating ways of improving this. We are also comparing the propulsion mechanisms of real fish and robotic fish [17][18][19][20][21].…”