Mechatronic Design and Maneuverability Analysis of a Novel Robotic Shark

In this paper, the mechatronic design and maneuverability analysis of a novel robotic shark are presented. To obtain good maneuverability, a barycenter regulating device is designed to assist the posture adjustment at low speeds. Based on the Newton-Euler approach, an analytical dynamic model is established with particular consideration of pectoral fins for three-dimensional motions. The hydrodynamic coefficients are computed using computational fluid dynamics (CFD) methods. Oscillation amplitudes and phases are determined by fitting an optimized fish body wave. The performance of the robotic shark is estimated by varying the oscillation frequency and offset angle. The results show that with oscillation frequency increasing, the swimming speed increases linearly. The robotic shark reaches the maximum swimming speed of 1.05 m/s with an oscillation frequency of 1.2 Hz. Furthermore, the turning radius decreases nonlinearly as the offset angle increased. The robotic shark reaches the minimum turning radius of 1.4 times the body length with 0.2 Hz frequency and 12 degrees offset angle. In the vertical plane, as the pectoral fin angle increases, the diving velocity increases nonlinearly with increase rate slowing down.