Design and Development of Low Cost Variable Buoyancy System for the Soft Grounding of Autonomous Underwater Vehicles

Abstract

To provide a vehicle with the ability to hold position in a coastal environment requires a significant amount of onboard power. This power requirement either forces the vehicle size to increase to allow for suitable mission duration or reduces the amount of time the vehicle has to conduct its mission. To relax the power requirement, we propose to develop vehicles that can employ a bottom-sitting or soft grounding behavior. To obtain this behavior requires vehicles that have the capability to selfballast. By optimally positioning itself and sitting on the bottom, the AUV can be placed in a sleep mode, with only monitoring sensors awake, thereby conserving power. In this paper we present the preliminary work conducted in the areas of simulation, design and testing of a Variable Buoyancy System (VBS) for an Autonomous Underwater Vehicle (AUV). This buoyancy system will be integrated into the new NPS AUV which is currently under construction, to support the upcoming joint operations with the University of Lisbon's MARIUS vehicle. We will discuss the tradeoffs and analysis that went into the design of the system, as well as the challenges associated with the integration of such a behavior and system into the vehicle.