A year ago, Greg Holloway set out to build an ocean drone, based on the tiny Raspberry Pi $35 computer.

Wired covered the start of the project, called FishPi, last summer, as Holloway was working on a Proof of Concept Vehicle (POCV), which at that time was essentially an upturned lunch container on the hull of a model ship. Now that he's approaching the one-year anniversary, the initial testing and research is paying off, and with collaborator Al Gray he's revealing plans for the final design to the FishPi community.

"When I began the project I had the optimistic expectation of being on the high seas by now," says Holloway. "FishPi will cross the Atlantic, it might just take a bit longer than I expected!"

FishPi Proof of Concept Vehicle, on the one year anniversary. What the FishPi looks like now.

"The Proof-Of-Concept Vehicle (POCV) is finished, just about," says Holloway. "I began the project with little to no experience of robotic control so even the smallest of details has taken, in some cases, weeks of investigation before a decision was made and a part purchased."

In fact, Holloway says, research has ended up being the bulk of his time on the project, to which he's devoting ten to twenty hours a week.

Perhaps the biggest change is the addition of software engineer Al Gray to the team.

Gray has taken on responsibility for incorporating the device's various bits of hardware into a functioning system. "Having begun with almost nothing, Al Gray has done a fantastic job integrating the Compass, GPS, Temperature Sensor, Rudder, Webcam, and the Electronic Speed Controller into the C & C [command and control] software," says Holloway. "We can drive the POCV remotely using the Webcam as a visual guide, but it has only been done in the bath so far."

"Since seeing Stanley (the car that won the DARPA grand challenge) at the Smithsonian a few years back, I've been inspired to get involved in an autonomous robotics project," says Gray, revealing his enthusiasm for the project.

Now that they have managed to get the POCV to drive, the next big challenge is getting it to drive itself. "The starting points for this are well established but calibrating for the particular craft and motion model will be fun," says Gray.

What the FishPi looked like in June. What the FishPi looked like in June.

Meanwhile, Holloway has been working towards a design for the prototype. Gone will be the clunky plastic box. The sleek new design is built around the requirements of the solar panel that will ensure the vehicle remains powered. Though Holloway was hoping to avoid the need for a keel, the shape of the panel has ended up demanding one.

"Given that the vehicle is likely to capsize in rough seas it would be silly not to have a self-righting mechanism," says Holloway. The keel will serve double duty as protection for the trolling motor and the weight bulb may be used to house certain instruments as well.

After ensuring power with the panel, the biggest concern for the hull is keeping the electronics dry. They'll be stored in cases from Pelican, with packs of silica gel in case of small leaks. The space in the hull between the cases will then be filled with high density self-expanding foam.

If you want to build a POCV of your own, Holloway has released WIP information on Instructables. And don't worry about getting your stuff wet. "The beauty of the Raspberry Pi and most parts is their relatively low price, if something goes wrong, you can always get another one!" says Holloway.

Photos and images: Courtesy Greg Holloway