EXPERIMENTAL STUDY OF A VARIABLE BUOYANCY SYSTEM FOR LOW DEPTH OPERATION

Autonomous Underwater Vehicles (AUVs) are used for underwater surveying both in coastal areas and deep sea without human intervention during their operations. AUV's performance, including range and endurance, is adversely affected by their high energy consumption by their thrusters. Herein, we have presented a novel design and development of a standalone variable buoyancy system for an autonomous underwater vehicle. We have studied the numerical and experimental analysis of Variable Buoyancy System (VBS) in standalone mode. Design idea is based upon the 'Pump Driven Variable Buoyancy System (PDVBS)' using 'Water Hydraulic Variable Buoyancy System (WHVBS)' method to control buoyancy using a diaphragm type positive displacement pump (PDP) with maximum buoyancy change capacity at a rate of 4.5 kg/ min. An in-depth investigation of the performance of the developed VBS has been conducted both experimentally and in simulation. Linear regression analysis has been investigated and the performance of the Linear Regression Model (LRM) is evaluated based on the computation of the Root Mean Square Error (RMSE) of the LRM. The developed VBS is tested at maximum depth of 5 m and compared to experimental and simulation results. Presented results demonstrate that the designed VBS is effective at changing buoyancy and controlling heave velocities. This will result in achieving higher range and endurance and better performance in rescue/attack operations.