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Project Summary

    For the senior design class in the 2006-2007 year, the team’s project was to design a submersible robot that could travel through underwater cave systems. Through the design process the team developed several main objectives which would allow the robot to achieve success in traversing the cave systems and allow for data to be retrieved.  The team decided on three main objectives which the team considered to be the primary requirements for the robot to operate properly.

    The first objective to develop a resurfacing system to allow the robot to return to the surface once it has reached the end the cave system.  This was done to allow the robot to be retrieved so that the data could be recovered. For the final design the team the developed, the robot used a solar cell to trigger a resurfacing system. The system used carbon dioxide to generate positive buoyancy.  This was done by allowing the carbon dioxide to travel through a series of fittings and tubing and was controlled by a solenoid valve which operated when the solar cell developed electricity.

    The second objective was to develop an oscillating buoyancy system that would allow the robot to free itself if it got stuck against any obstacles in the cave system and to allow for the robot to operate in areas of minor density change. The buoyancy system was designed to be very similar to the resurfacing system. Unlike the resurfacing system, the buoyancy system used a microcontroller to regulate the opening and closing of three solenoid valves.  This allowed the team the control the flow of carbon dioxide which was used to inflate a bladder which then displaced water from the housing to generate positive buoyancy.  By inflating and deflating the bladder the robot would oscillate around the neutral buoyancy value that was decided from the housing design and component selection.

    The final objective was to develop a housing system which would provide protection for the internal systems while also providing the neutral buoyancy required for the water current to carry the robot. The final part of the design was to develop the housing and the team did this by constructing the housing around the other systems of the project.  Using these requirements the team went with a clear PVC pipe design which was threaded at the end to allow for access to the internal components.  The final design used three 4” diameter 15” long pipes, one of which was split by a bulkhead in half to allow for partial flooding, as the main housing. One 3” diameter 10.5” long regular PVC pipe was used to protect the carbon dioxide canister.  The pipes were all connected together through the ends by plastic tubing which was used to provide a water tight seal from one housing to the next housing.  Together the 4 pipes provided the required buoyancy to allow the robot to be carried by the water current.  The final buoyancy of the robot was 27.5lbs and the final mass of the robot was 22lbs.  This allowed to team to install a sensor package weighing up to five pounds at a later date.