Kinematic model analysis and design optimization of a bionic pectoral fins

Cownose rays have excellent characteristics as the fish with oscillating pectoral fins. Therefore, in order to construct bionic fish prototype with high efficiency, low noise and high stability characteristics, cownose rays is chosen as the prototype in bionic research. In the paper, simplified flapping kinematic model is established based on the study of the characteristic of cow rays´ pectoral fins. The mechanism characteristics and motion feature of the Robo-rayI-IV generation robotic fish mimicking cownose rays are summarized, and the shortcomings in the current design is analyzed. Then, optimization design ideas of heaving and pitching airfoil based on space parallel mechanism with two degree of freedom are proposed in the design of pectoral fin skeleton. The feasibility of new pectoral fin skeleton is verified through simulation. Bionic pectoral fin is constructed and processed. Finally, experiments were carried out and the rationality of the optimal design is verified. Experiments shows that the new pectoral fin skeleton has good active and passive flexible deformation capacity, and robotic fish with new pectoral fin has better propulsion performance than Robo-rayIV while maintaining the high mobility of the premise.