Modeling and Experimental Research of Integrating Propulsion Mechanism of Pectoral Fin’s Fluctuation and Swing for the Biomimetic Robotic Fish

For developing a high-performance biomimetic underwater thruster, this paper takes stingray as a biomimetic prototype and learns from the fish’s swing-mode propulsion mechanism to propose a new type of propulsion mode that integrates pectoral fin’s fluctuation and swing propulsion mechanisms. The mechanical structure and control system of the biomimetic robotic fish are designed, and a dynamic model integrating the pectoral fin’s fluctuation and swing propulsion mechanisms is built. Based on the theoretical analysis, the relations of the average propulsive force and swimming speed with the motion parameters such as area of swinging pectoral fin, the swing frequency, and amplitude are studied experimentally. The results show that the theoretical calculations and the experimental results have the same tendency; the average propulsive force and the average swimming speed of the robotic fish increase first and then decrease with the increase of the swing pectoral fin area, and they increase linearly with the swing frequency and amplitude increasing—the maximum average propulsive force reaches to 2.8 N, and the maximum swimming speed reaches to 121 mm/s. The research may provide a reference for improving swimming performance of the robotic fish.