Matt Clarke's Autonomous Boat, Powered by Pixhawk and a Raspberry Pi, Targets an Atlantic Crossing

Software engineer Matt Clarke has put together a 3D-printed aquatic drone, dubbed Casper, boasting fully autonomous control courtesy of a Pixhawk autopilot system and a Raspberry Pi single-board computer (SBC) — and is hoping for it to take part in the Microtransat Challenge to cross the Atlantic ocean unaided.

"It's an international competition with the goal to send an autonomous or unmanned boat across the Atlantic Ocean," Clarke explains of the Microtransat Challenge. "Usual entries to it are sailboats — so robotic boats, effectively, where they control their sails. I'm going to be a little bit different: I want to do pure electric propulsion, so we're talking solar panels, propellers, and all the other power shenanigans that come along with it."

In preparing for his entry, Clarke is starting small with a proof-of-concept: a 3D-printed autonomous drone boat. "It took a lot longer than I thought it would do," Clarke says of the printing process. "I had to split the model for the hull into multiple segments, so it's quite a large catamaran design and [the print bed] is way too small to be printed in a single piece on my Prusa Mini. The first parts came out really badly warped, so I went on a multi-month detour to build a 3D-printing enclosure as a totally reasonable reaction, right?"

The assembled boat body, sealed with epoxy and ABS cement, plays host to a Holybro Pix32 V5 Pixhawk flight controller, which is in turn connected to a Raspberry Pi Zero W for telemetry and control. The controller, however, doesn't drive a rudder, as Clarke has a different idea in mind for steering: "I'm using differential thrust to provide yaw control," he explains.

Following a bathtub test, Clarke took the boat out for a field test — which was going well, after a little last-minute rewiring, until the universal joint popped off the prop shaft at one side, causing the boat to drift into bushes. "The solution here," Clarke suggests, "is going to be to take a Dremel and create a little flat surface on the prop shaft itself so the little grub screw can bite onto it properly and prevent it from slipping."

A final change to the electronics saw the telemetry switched from the Raspberry Pi Zero W to an Espressif ESP32 board running the Drone Bridge firmware, after a badly-delayed disarm command required a second rescue mission. Now Clarke is tweaking the design, ahead of entry into the Microtransat Challenge — though plenty of work remains before Casper is ready for its trans-Atlantic mission.

More information on the project is available on Clarke's YouTube channel, while 3D print files for the boat hull are available on Dropbox. Clarke has also written more on how to interface Pixhawk controllers with a Raspberry Pi here on Hackster, and full details on the Microtransat Challenge can be found on the competition website.