Research On The Water-exit Movement Simulation And Energy Conversion Mechanism Of Robotic Dolphin

The dolphin has exceptional athletic ability, such as high swimming speed and propulsion efficiency and the ability of jumping out of water, so it becomes the bionic object which the scholars focus on. However, the mechanism of dolphin’s water-exit movement is not yet clear, which restricts the development of robotic dolphin with higher water-exit movement ability. At the same time, the existing robotic fish is still confined to underwater swimming and still doesn’t have the ability of water-exit movement. Therefore, a research on the kinetics model of the water-exit movement and its energy conversion mechanism is carried out in this paper, which will provide a theoretical basis for the further development of robotic dolphin in order to expanding the movement space of the current robotic fish.Firstly, through the analysis of kinematics model and the stress situation of robotic dolphin during the process of the water-exit movement, the kinetics model of robotic dolphin’s water-exit movement is established. And considering the interaction between the dolphin and fluid, a kind of numerical method for solving the water-exit movement of robotic dolphin is put forward. Secondly, the tuna and dolphin is analyzed and compared in terms of their morphology and kinematics. And through the three-dimensional numerical simulation on tuna’s and dolphin’s swimming underwater, the underwater swimming performance of tuna and dolphin under different conditions is analyzed and compared. The result shows that dolphin has higher propulsion efficiency. Thirdly, through using the numerical method proposed for solving the water-exit movement of robotic dolphin and combining with the kinematics and kinetics model of robotic dolphn’s water-exit movement, the three-dimensional numerical simulation on the whole process of robotic dolphin’s water-exit movement is carried out and time course on the displacement, speed, force and torque of robotic dolphin and the phase diagrams and pressure contours at different times in the whole process of robotic dolphin’s water-exit movement is obtained. And the relationship between water-exit movement performance of robotic dolphin and the water-exit movement angel and oscillation frequency of robotic dolphin is discussed and it indicates that the water-exit movement height of robotic dolphin increases with the water-exit movement angle and oscillation frequency. Finally, via the establishment of energy function during the process of robotic dolphin’s water-exit movement, the change of the kinetic energy, gravitational potential energy and the total energy which robotic dolphin gets and consumes with time is analyzed. At the same time, through the establishment of efficiency evaluation function of robotic dolphin’s water-exit movement and comparative analysis, it is found that the water-exit movement efficiency of robotic dolphin increases with the water-exit movement angle and oscillation frequency.The research on the kinetics model of the water-exit movement and its energy conversion mechanism broadens the research field of the existing bionic propulsion mechanism and it provides theoretical possibility for the existing robotic fish achieving further water-exit movement. Further development and deepening of the present research work will provide a solid theoretical basis and key technologies for the future development of other underwater vehicles and the near surface weapon systems that can achieve the water-exit movement.