Servo - August 2008

Rhyme of the Modern Submariner

great way to tackle the challenges of the MATE

Competition. The event demands that teams complete three underwater missions that are part of a scenario inspired by mid-oceanic ridge research.

The first mission was to free an OBS trapped mercilessly on the ocean floor. An OBS is an

Ocean Bottom Seismometer, and in the game scenario, it was placed in order to gather information on ocean floor seismic events like underwater eruptions and earthquakes. The good news is that the OBS did indeed gather the hoped for information, but the bad news is that the OBS became trapped in a fierce lava flow in the process. Our first mission — should we choose to accept it — would be to free the OBS from the lava flow.

It’s basically like an episode of the Thunderbirds, but instead of sending puppets to save the day, we’ll be sending in our ROV.

After freeing the helpless OBS from the ocean floor, the second mission was to collect three samples of the lava flow for analysis. The final mission was to take a temperature reading from a hydrothermal vent.

For the competition, the OBS is represented by a PVC box skeleton; the lava is represented by eight, two pound soft dive weights; and the hydrothermal vent is another PVC structure spewing hot water. The missions will be discussed in more detail later, because first and foremost we wanted to have a working platform.

The ROV-in-a-box would give us a functional ROV that could be expanded upon to complete the missions. We wanted to finish our basic ROV before worrying about the details of the missions, and with that in mind, we popped open the instruction manual to the first step.

ROV-IN-A-BOX MOTORS.

TAU BATES AT WORK.

ROV is primarily made up of speaker wires, and their 50 foot length was the perfect size for the MATE Competition. The ROV kit comes with three motors from Mayfair Marine: two for the right and left thrusters, and one for the lift thruster. The motors come with easy to install couplers for small plastic propellers. A soldering iron and the associated paraphernalia is one of those things not included in the kit, but once again these are essentials for every robot project that roboticists should have in their arsenal.

After preparing the motors, the next step is to prepare the CCD camera and LED cluster used for lighting. The unforgiving work environment faced by the ROV requires some extra

MOUNTED MOTORS.

The Life Aquatic Meets the Life Robotic

Now that we had a team of mechanical engineers, structural engineers, computer science

engineers, and many more, it was time to pop open the ROV.

When we first opened it, we were reminded of our experiences at the beginning of every FIRST build season — we were faced with a somewhat intimidating box of loose parts. Motors, wire, PVC, and switches abounded, and the project might have seemed a bit overwhelming had it not been for the handy instruction manual. The ROV-In-A-Box K it comes with a comprehensive manual that gives easy to read, step-by-step instructions that are illustrated by clear pictures.

The first thing that the manual walks you through is the construction of the frame for the ROV. The PVC bits are all nicely cut and ready to go, but the kit does not include PVC cement or primer. That’s nothing a preemptive trip to the hardware store won’t fix, and the beginning of each step in the manual conveniently lists any additional parts required for the step not already included in the kit. Thankfully, this list is usually very short, and most of the entries are simple tools that any self-respecting tinkerer should have at the ready.

The PVC frame goes together very easily, and it’s a nice thing to do first because it already gives you a sense of the scale of the ROV. The bot was a bit smaller than we had initially guessed, but there’s nothing wrong with that — just ask the Thunderbirds.