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Vision Core

by

Vicki Banh, Curtis McCabe, Juan Deleon, Jonathan Riestra

Link to Executive Summary

Overview

Background

Sediment contamination is a significant liability for the Department of Defense (DoD), with overall cleanup costs approaching $265 billion over a span of 30 years. There is a focus and need for technologies that support clean-up remedy selection, evaluation of remedy success, and sustainable long-term management at DoD sites. Visual tools play a key role in supporting these goals. Existing Sediment Profile Imaging (SPI) technology has proved to be highly applicable to tracking the conditions of surface sediments for a range of physical, chemical and biological characteristics that are important to remedy success. These include aspects such as grain size, redox, burrowing, and debris. The primary limitation of the existing SPI technology is that it can only penetrate and profile to about 15 cm, and thus is only useful for surface sediments. Many sediment remedies require information beyond this depth. Currently the only reliable method to obtain these visual profiles is through the collection and processing of sediments obtained by a coring tube. These methods are generally time consuming and expensive, and thus the ability to use them over wide areas for sustainable long-term monitoring is very limited. Thus, a tool specifically designed to provide a visual in-situ measure in surface and subsurface sediments to greater depths than current technology would greatly enhance confidence in the efficacy of remedial actions before, during, and after implementation.

Diagram of typical coring systems (left) and commonly obtained sediment samples (right)

Objective

The specific aspects of this project can be modified to fit students interests and skill sets, but generally, we would like them to design and build the underwater housing that holds the camera and associated electronics for providing real-time imaging of the sediment particles as the housing is pushed through the seafloor. The housing will have to fit within the constraints of the machine driving the instrument into the ground. The housing must withstand up to ~60 feet of depth plus about 6-10 feet of immersion into the sea floor. The housing requires a window for the camera to view the sediment. The housing requires an instrument feed-through cable to deliver the ethernet cable to the surface for real-time video. The team will research the best housing design and location to place the window based on analysis of how the displaced sediment will move around the housing as it is driven into the sea floor. The students will have the opportunity to determine the best camera and lens and optical environment (lighting) for use in this application. The mentor already has a number of materials including a camera that the students can use for prototyping. The students may have the opportunity to program the camera such that changes to the camera f-stop can be made in real-time.

Final Product

Description

The final design of this project as seen in figures below is a housing made from a 7.6 cm (3 in) square tube that has been sealed at one end where the tip has been attached. The top end has a detachable lid through which a Subconn wetmate connector runs the Ethernet cable to the camera. The lid seals with two O-rings, while a sapphire widow attached on the side of the housing seals with one O-ring. An Ethernet cable connects to the cable lead which in turn connects to the housing lid through a Subconn wetmate connector. The wet mate connector runs the cable to the camera. A small industrial camera is mounted using spring steel flexures that effectively isolate the camera from the 60 Hz vibrations caused by the driving motor. Attached to the camera is a mirror set at 45 degrees that allows it to view the window on the side wall of the housing. The tip is rigidly connected to the bottom of the housing and serves to make the flow of material around the housing one directional and effectively preserves the layers of sand and sediment that pass over the window.

Annotated CAD

Housing shell with the tip

Performance Results

Movie