Float state and static stability analysis of the biomimetic robotic dolphin designed on the change of the barycenter

In this paper, the structure of biomimetic robotic dolphin designed on changing the barycenter is described. Through a barycenter adjustor which can change the dolphin´s center of gravity by swinging an inside counterweight, it can realize the dolphin´s pitching movement underwater. By means of the mass properties function of SolidWorks, the dolphin´s buoyant center and barycenter, and the center of gravity for every part are analyzed and calculated. They are the foundation for further study. The dolphin´s zero trimming and trimming caused by the barycenter adjustor are analyzed and calculated. According to the barycenter moving principle and the principle of the motion of a point in Cartesian coordinate system, the influence on the dolphin´s float state and static stability caused by the counterweight swinging in vertical and horizontal longitudinal direction are respectively presented. The above analysis and calculation are validated by the moment balance principle. Finally, the factors which influence the dolphin´s float state and static stability are discussed. The study in this paper is the foundation of the subsequent mechanical design, control system design, simulation and optimum design for the biomimetic robotic dolphlin.