The Design of a Kind of Two-Joint Mechanical Fish

Bionic mechanical fishes mainly involve single-joint mechanical fishes and multi-joint mechanical fishes. Although the motions of multi-joint mechanical fishes are more similar with those of fishes in nature, micro servos, whose torques are limited, are chosen as the driving mechanism in multi-joint mechanical fishes, and the movement speed of such mechanical fishes are not high. In contrast, DC motors with greater power and torques can be used as the driving mechanism in single-joint mechanical fishes, which is simple in structure but has higher oscillation frequency and can achieve faster forward speed. Therefore, a new type of two-joint caudal fin propulsion bionic robotic fish is designed. It has a novel tail structure that uses one DC motor to drive two tail joints so that it can achieve a higher tail fin swing frequency than most of the traditional multi-joints mechanical fish. 3D modeling is carried out for the mechanical fish, and then dynamics analysis and strength analysis are done by ADAMS and ANSYS Workbench. The result shows that the design is feasible and reasonable.