Passive Hydrostatic Stability Design of a Box-shaped Autonomous Underwater Vehicle

This paper presents a passive hydrostatic stabilization system design for a box-shaped autonomous underwater vehicle. In order to ensure the quality of data collected, underwater inspection mission require a high stability AUV, especially in roll and pitch direction. However, conventional AUV adopt torpedo-shaped body, which has limited passive restoring moment in roll and pitch direction. Therefore, this paper presents design of a box-shaped autonomous underwater vehicle which is highly stable in roll and pitch direction. The passive stability of the designed autonomous underwater vehicle is improved by putting the heavy components at the bottom part of the vehicle whereas light component at the top part of the vehicle. The designed vehicle weights 68.8 kilogram in air with 0.6 kilogram positive buoyant. It has centre of buoyancy exactly above the centre of gravity with 7.39 centimeter metacentric height. By calculation, the vehicle will have 35.68 newton meter restoring moment at 45 degree. By pool test, result shows that the vehicle is able to retain its original vertical axis as vertical without steady state error.