Objectives The motion state of autonomous underwater vehicle (AUV) is impacted by different densities of water, so it is necessary to recalculate the balance and control parameters. However, the use of a variable buoyancy device can add a more effective self-regulation capability to the AUV, making it suitable for operation in a wider range of scenarios.
Methods This paper proposes the design of a variable buoyancy device for an AUV. Through adopting an oil bladder that can intake/discharge oil and transfer it quantitatively in a dual manner, the device can change the volume of the external oil bladder and regulate the AUV's buoyancy status.
Results The results of the tank and lake tests show that the designed device can help the AUV to achieve the functions of fixed-depth hovering and diving during navigation, and complete a 90-hour mission of low-power-consumption parking for in-situ observation after soft-landing on the lakebed at a depth of 51 m.
Conclusions The results prove the validity of the variable buoyancy device and lay the groundwork for enhancing the operation effectiveness of AUVs, as well as extending their application scope.
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