A Buoyancy-Controlled Underwater Vehicle for Gliding and Station Keeping

This thesis develops a design method of underwater glider with fore and aft type buoyancy engines. Underwater glider design focuses on the gliding performance. This work enhances the glider function by adding the abilities of posture control and station keeping. A glider with gliding, posture control, and station keeping capabilities could be applied as a data and/or energy commuter in between surface and underwater nodes. This work at first design the body elements to withstand high pressure environment to 300dbar. The design is then proved through a stress simulation environment using a pressure testing device. A buoyance engine is a mechanism which changes buoyancy of an underwater vehicle by attracting and expelling water and can change the position of the center of gravity of the glider. Dynamic equations of an underwater glider is derived which implies the steady-state performance of gliding. Design methodology for the size of wings is used to choose the position of wings and the buoyancy engine operating limits. By the fore and aft buoyance changes, a depth control and constant posture of the glider can be achieved. Finally, the experimental data to demonstrate the gliding, depth and posture control are presented.