Development of a Variable-Configuration Bionic Robotic Fish

Bionic robotic fish have advantages over traditional underwater propulsion. Most of the existing studies have been conducted with only one type of fish as a bionic object, but a single propulsion mode may not be able to achieve the different needs of underwater operations. In this paper, we designed a pneumatic variable-configuration soft bionic fish and completed the overall structure design. It was built with a cownose ray as the main-configuration bionic object and a Caranx melampygus as the secondary-configuration bionic object. The base structure, actuators, and variable-configuration modules of the robot were made using flexible materials. After completing the design of the structure and control system of the robot, the prototype was manufactured and an underwater test was completed. The tests results indicated that the robot fish could achieve underwater linear propulsion and turning movements in both configurations. The maximum propulsion speed of the main configuration was 38.24 mm/s and the turning angle speed was 5.6°/s, and the maximum propulsion speed of its secondary configuration was 43.05 mm/s and the turning angle speed was 30°/s. The feasibility of the machine fish structure and control scheme were verified.