Oil-Sniffing Underwater Glider Projects
The team has successfully built two underwater gliders over the past two years - a small mini glider to gain experience with gliders and a better understanding of their components and one larger glider we have successfully deployed. Both gliders use a piston-based buoyancy engine system and have internal roll and pitch mechanisms. The large glider dove autonomously to 50 ft during a testing trip in Ketchikan, Alaska and was also tested in the Carderock Naval Base in Bethesda, Maryland.
Image of glider taken from a SeaBotix ROV during an autonomous dive in Ketchikan, Alaska.
We are currently working on an updated version of the glider to implement improvements on previous glider designs (based on observations from testing), to explore innovative buoyancy engines, and to include provisions for testing sensors.
Bladder-Based Buoyancy Engine
We are working on a buoyancy engine design that explores the use of an inexpensive gear pump as the main system actuator. The gear pump has has a fixed displacement of .128 cubic inches/revolution, and is rated to 3000 psi. The motor is couples to an electric motor with an in-built worm gear.
SolidWorks design for bladder-based buoyancy engine
We have assembled and tested the engine in the laboratory and are now working to complete fabrication of the pressure vessel and finalize the electrical components and motor control in the engine.
Nitinol Buoyancy Engine
We are also working to evaluate the potential of nitinol, a shape memory alloy, for use in a passive thermal buoyancy engine that derives energy from the thermocline of the ocean. Initial work characterizing the material properties of candidate nitinol wires has been done and we are in the progress of conducting further studies. After a full evaluation of nitinol properties, we plan to demonstrate its use in a small buoyancy system in a simulated environment in the laboratory
CAD model for preliminary nitinol glider design
ROV Chase Vehicle
A complete system was designed and fabricated during summer 2013. The system is modular, easy to use and assemble, and can be easily adapted to suit specific purposes. We also did preliminary testing on a system that can be used to track light off the vehicle. A summary of the system is presented below.
- Two pressure vessels mounted on an 80/20 chassis
- One pressure vessel contains the controls systems (an Arduino Mega, BeagleBone Black, and an XBee Series I) and a camera
- The controls pressure vessel is housed in a clear acrylic tube and will send the depth, camera angle, vehicle orientation, camera visual, and motor information to the surface via the tether
- The second pressure vessel includes the motors, 4 ESCs, an Arduino Mega, and an Xbee
- The main controls goal is to autonomously track a light below the surface
- The system will come with a built-in override for autonomous movement so that the motors and camera angle can be controlled from the surface
- The electrical components are powered with 9V batteries
- The motors are powered with two NiMH 7.2 V Batteries
- The ROV utilizes small, brushless motors as brushless motors perform better in salt water
We are currently experimenting with the use of inductive couplings nad RF to transmit wireless data. We are also designing wireless thruster modules that can be easily added to or removed from the vehicle and are updating the mechanical design of the ROV to include a sensor mounting system.
Our team began to explore wave energy in fall 2013. We have a general interest in wave energy conversion and its applications in providing nominal power to and communicate with underwater vehicles. We are currently in the stage of researching and evaluating current wave energy conversion designs. We are planning on using a modular buoy system to do initial wave energy tests and data collection. We are exploring the potential of the following energy conversion methods: (1) oscillating water column systems, (2) compressed air energy systems, (3) pizeoelectric systems , and (4) thermoelectric systems. A summary of each potential system is presented below.
Oscillating Water Column
Compressed Air Energy