Development and three-dimensional modeling of a bionic robotic fish with pectoral fins

Biomimetic fishes have received widespread attention due to their maneuverability, acceleration, and high efficiency. This article designs a bio-inspired robotic fish with a realistic streamlined appearance, consisting of flexible pectoral fins made of carbon fiber fins and silicone skin. Using an artificial central pattern generator as the system motion driver, the prototype can generate multimodal motions and reach a max speed of 0.72m/s, which is 1.2 times body length per second. In addition, we use analytical methods to establish a universal three dimensional dynamic model of the prototype driven by pectoral fins, taking into account the effects of buoyancy, damping, and inertia forces, and more importantly, we conclude that the swimming speed is not greater than the wave speed that transmitting on the pectoral fins. Finally, detailed comparisons between simulations and experiments are conducted for open-loop swimming, as well as the influence of pectoral fin motion parameters on swimming speed. The overall results have verified the motion capability of the prototype and the predictive ability of the designed model for the three-dimensional motion trajectory, attitude, and swimming speed of the prototype.