Underwater Robotics Questions

[Greg Marra]

This is rather outside the usual scope of ChiefDelphi, but it's a forum full of smart robotically-minded people, so here I go:

I am taking a class at Olin College this semester, and our final project is to build a robotic fish. We’ve been building “robotic fish” all semester, but so far they’ve only been above water and haven’t seen any submersed action. (videos: http://vimeo.com/gregmarra/videos). The final project goes in a swimming pool.

We’re planning on building a watertight head compartment and using hydraulics to transfer power from inside the head to outside. The head will be rapid-prototyping-3D-printed, epoxied for watertightness, and have fittings to pass the hydraulic lines. I have high confidence this will work. What I’d really like to be able to do is use hobby servos outside of the head for controlling pectoral fins for swimming up/down. My research online suggests that waterproofing servos is a decent idea, but won’t really hold up that well. We may end up using more hydraulics here, but that's more complicated than I'd like.

Do you have any specific resources regarding building underwater electromechanical systems you could point me at, or any specific words of advice? My team doesn’t have that much planned out yet, but we’re working on a short timeline (4 weeks total!) so any advice or pointers at all would be extremely useful!

Thanks!