Stability of motion of the crewed autonomous underwater vehicle

In this article I investigate the issues related to the motion stability of a crewed autonomous underwater vehicle of the 'wet' type. In vehicles of this kind, the necessity to perform decompression imposes certain requirements relating to the parameters of the motion. In particular it requires maintaining a constant depth regardless of the operating conditions. For this reason, the investigation is limited to an analysis of a two-dimensional motion within the vertical plane. The analysis of motion stability is based on the classic motion equations. In formulating the relations of forces, along with the hydrostatic influences, viscosity and inertia of the water environment are considered. Forces relating to the viscosity are examined through the resistance coefficients. The specific calculations draw from the results of model tests. Forces related to the inertia of the environment are accounted for considered through the water added-mass coefficients. In order to assess the quality of motion, a coefficient of damping and a degree of stability are used as values indicating the character of the results of the dynamic motion equations. The results of the example calculations are presented in the form of diagrams, complete with the lines representing the constant values of the above indicators of the motion stability for different structural solutions under various conditions in which the vehicle is operated