STUDY ON A UNDERWATER VEHICLE FOR LOW SPEED GOOD MANEUVERING

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Under water vehicles usually have the combination of propellers for their propulsion and maneuvering. Sometimes, the low-speed precise maneuvering is needed for observation of marine environment. But, the present under water vehicles are not suitable for that purpose. In this study, the undulating side fins that are used by a squid or a flat fish is investigated to examine that they are suitable for a low-speed under water vehicle. The fish-like body consists of the resistance body whose movement is small and two undulating fins as the propulsor. This system is expected to have the advantage for the change of movement direction and quick maneuvering without vertical motion in low speed region from the observation of a squid.. The laminar flow computation of the flow field around the simple model with two undulating side fins and resistance body was computed. The features of the flow field and hydrodynamic forces aging on the body and fins were discussed based on the computed results. T … More hese results provided good information for understanding the complex fluid mechanics that this type of fish uses to propel itself. The two models were constructed and used for preliminary experiments. The free-run tests, hydrodynamic force measurements and PTV(3D volumetric PTV) measurements for flow field were conducted. The computation between computations and experiments was carried out and the validity of the computation was shown.Finally, the new model was constructed and experiments were done. The new model has the servo motor units to produce any fin's motion, servo controller and the motion control computer inside the model. So, it does not have the strut t or the big cable. The model has one thin cable that is connected to the floating wireless communication units to the remote computer on the ground for control of microcomputer inside the model. The model can run freely to any direction and change the angle around any axis. Firstly, the advance speed and the angular velocity of turning motion were measured. Secondly, the free-run test to follow the prescribed route was conducted. Next some basic fin's motions that make the 6 degrees of freedom motion are investigated. The results show very promising. Thrust measurements are conducted. In this result, the characteristics of propulsive forces are shown. The simple motion of new model is predicted by the solving equations of motion using the results of force measurements. The results were compared with free-run test results and good agreement, to some extent, was obtained.The precise maneuvering control of the model with two pair of pectoral fins was also, studied. The results show promising results. Less