An AUV(autonomous underwater vehicle) for scientific and industrial tasks such as precise surveying, inspection and sample gathering is being researched. The vehicle is operated both as a cruising type and an exact automatic position control type vehicle. A quarter size model vehicle named "Diving Beetle" was developed for this study. The paper is concerned with an outline of the vehicle, its hydrodynamic coefficients obtained from experiments and simulation of the vertical motion.
Many remote operated vehicles (ROV) are now widely used for important scientific and industrial tasks such as ocean measurement, precise surveying, inspection and sample gathering (Whitcomb et al., 1993, Mikagawa et al., 1999 and Nakamura et al., 2000). Most of these are self-propulsive vehicles with a tethered cable so that the electric power can be supplied and control signals and obtained data can be transmitted easily. These allow the vehicle to be accurately directed to a target location and to carry out the desired tasks. However, the cruising radius is limited and survey for danger such as a submarine volcano is very difficult because of the umbilical cable tethering the vehicle to the mother ship. Development of autonomous underwater vehicles (AUV) for investigation of the marine environment has been active in recent years (Obara et al., 1994, Bradley et al., 1995 and Aoki et al., 2001). An AUV which could be operated both as a cruising type and an exact automatic position control type vehicle would be most advantageous. But it is difficult for an AUV to have both these functions, because the hydrodynamic characteristics and control method required for the two types of vehicle differ greatly. A quarter size model vehicle named "Diving Beetle" was developed for this study. Fig.1 illustrates a sample mission of the full-scale "Diving Beetle".