Date of Award

5-5-2025

Degree Type

Capstone Project

First Advisor

Bahram Nassersharif

Abstract

Unmanned Underwater Vehicles (UUV) have a range of applications. Researchers in many fields utilize them for underwater mapping and inspection of structures. They are also used by the military for mine detection, intelligence gathering and surveillance activities. UUVs must be neutrally buoyant for optimal control and stability, meaning that their depth and position can be easily controlled regardless of ocean movement. In the event of communication or propulsion loss, retrieval can be extremely difficult due to the neutrally buoyant nature. Retrieval increases human and financial cost of the overall operation, and in many cases the entire hull is lost.

The team was tasked with making a modular system that would enable the UUV to become positively buoyant, allowing it to float up to the surface. This recovery system must release two half pound ballasts on either side of the hull within five seconds of a return to surface command. This system must work at a depth of up to 400ft, as well as work on a maximum of 12V at 3 amps. The system must be watertight before and after the release of the ballasts. The hull itself will be made from Aluminum 6061-T6, with an outer diameter and length of 5in, and thickness of 0.125in. The ballasts cannot be released inadvertently, as they are a ‘last resort’ system. The ballasts themselves do not have to be retrievable.

The team went through several design iterations and used a Pugh analysis to compare designs based on functionality, reliability and complexity. The initial choice was a threaded back out system, where ballasts would unscrew from the hull. After creating a tangible model, a redesign was initiated due to the complexity of the stepper motor and the need for multiple rotations. The team shifted to a simpler lock-and-key method, requiring one 90-degree turn to release the ballasts. The lock-and-key method was successful in meeting all the given design specifications, and met the sponsor’s needs.

Comments

Team Name: Team 7

Company Sponsor: RTX Corporation

Sponsor Representative: Dave Lavallee, Adam Maziarz, Mike Travisono

Document Reference: URI-MCE-402-007-2025

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