Motion dynamics of subsea vehicles are reviewed on the basis of vehicle configuration in order to develop a simulation method for vehicles of a general shape. After an initial literature survey, extensive hydrodynamic tests have been carried out with an existing tethered Remotely Operated Vehicle (ROV), which was used as a test vehicle, and with its full-scale model. The experiments have given data of maneuvering capabilities, and of hydrodynamic characteristics of small subsea vehicles. A. simulation method has been developed on this basis to compute the vehicle trajectory in the time domain as a function of different control commands. The method can be applied to any subsea vehicle controlled by thruster units.
A programme of underwater technology research was undertaken by the Technical Research Centre of Finland (VTT) during the years 1987 to 1989. This programme was of an extent of 22.5 Person years, and included eight research projects. These included a wide range of technology including underwater material technology, flexible risers, and underwater vehicles with their equipments, including especially manipulators. One of the projects was Motion dynamics of submersibles, which will be described in the present paper. Underwater vehicles can be divided into various groups on the basis of vehicle external shape and size. The vehicle shape is the most important factor, when hydrodynamics of underwater vehicles are concerned, since the external shape of a vessel determines principally the fluid flow characteristics around an underwater vehicle. Another important factor is the hydrodynamic angle of attack encountered by a vessel in practical or emergency maneuvers.