Fish Pi

Liz: I try to keep an eye out for some of the kookier projects people are using their Raspberry Pis in. This autonomous, solar-powered, Atlantic-exploring work-in-progress fits the bill precisely (and it has a great name and incorporates Tupperware into its design), so I asked Greg Holloway, the Mind Behind, to write a few words about what he’s doing for us. Hoist the mainsail, Greg!

Massive 25 foot waves, 60mph winds, torrential rain, lightning, and the Kraken.  None of those things should be put anywhere near a Raspberry Pi. On the Atlantic Ocean all of those are commonplace, and that is exactly where I’m sending my Raspberry Pi.  The project is called FishPi, and the aim is to develop an Autonomous Marine Surface Vehicle, and have it cross the Atlantic Ocean.

I don’t suppose it will happen quite like the illustration depicts when the Kraken shows up; FishPi will be powered by a 130watt solar panel, so there will be no masts or sails. The propulsion will run from batteries, charged by the solar panel, and it will utilise a Kort Nozzle to gain maximum thrust from what will be limited power.

There’s a long way to go yet before the Raspberry Pi gets its sea legs, but that’s not to say progress has not been made. At the moment my time is being spent developing the Proof-Of-Concept Vehicle. The POCV has a hull of 20 inches, so it’s quite small. Below deck sits a brushed 540 motor coupled to a 2.5:1 reduction gearbox, which in turn drives a ducted 40mm Kort propeller. There’s also a servo which will rotate the nozzle to turn the vessel.

The Raspberry Pi is going into a waterproof container, an upside down lunch box, along with all the other important components. The important bits will run on the i²c bus, a GPS, a servo controller board (which will drive the rudder and the Electronic Speed Controller (ESC) for the motor), and a compass. I hope to attach the Raspberry Pi’s camera once it becomes available, if it’s not ready in time a USB one will do instead.

 One of the systems I’m looking at now is the power for the POCV, and it looks like I’ll be running it from six 1.2v NiMh batteries. Power to the Raspberry Pi will come from an LDO outputting a regulated 5v, a similar LDO will be used to provide 3.3v for the devices on the i²c bus. The ESC will draw directly from the battery pack, but the output to the motor will be controlled by the Raspberry Pi via the Servo controller board on the i²c bus. The batteries are to be spread around the hull to help balance it on the water and to add ballast for stability.

There is a lot of head scratching going on, and I’m always ready to hear fresh ideas, and of course the occasional warnings associated with undertaking such a task. The project website is at fishpi.org, you’re all welcome to pop onto our forum, and follow the projects progress, and there is also a twitter account; @TheFishPi.

I’ll be taking the FishPi along to the Nottingham Hackspace Raspberry Jam on Tuesday the 3rd of July. Feel free to ask questions, make suggestions, and if you’re raucous enough, you can join in with some sea shanties too, ye landlubbers.