Boxing It Up

The last 10 days or so have been spent organizing the layout for the 3 waterproof boxes that are to be mounted on top of the surfboard. One of the boxes is a bit larger and is on the back end. It holds the air propeller and rudders on top, and contains A to D and sensor circuitry inside. The middle box has the battery, electronic speed controller, and solar power regulator, and the front box has everything else: Raspberry Pi, wireless serial module, GPS module, camera, LiDAR, etc.

All of the boxes are watertight (at least according to Amazon) and have had holes of various sizes drilled into them for routing cables. These holes should also be waterproof thanks to a multi-pack of cable glands. The solar panel is held down with some plastic bolts and wingnuts that were 3D-printed and glued into the board. At some point I will need to attach some lightweight plastic tubing to the edges of the board for organizing the cables,  and attach some rope handles to the front and back for carrying or towing.

Right now the big challenge is getting all of the circuitry back to the state where it was with the old beer cooler AMOS. There have been a couple of issues so far, as the layout of power and signal wires has proved to be problematic for control of the rudder; for some configurations that I have tried, the voltage getting to the rudder servo motor is too low (less than 4.8 V) and in other configurations turning on / off the rudder servo motor has resulted in power supply fluctuations for the Raspberry Pi board, causing it to crash. I have decided to try solving this problem by giving the rudder servo motor its own power supply (probably ~ 6.5 V, as it affords a bit more torque than the previous 5.0 V).

The second issue encountered was a short-circuit in the battery box that accidentally shorted out the +5 V fuse on the +12 V battery terminal. The fuse had pulled out of its holder when I was mucking about with wires, and I was surprised to notice an LED on the A to D board flash on, even though the power had been switched off. Later troubleshooting indicated that the I2C bus on the Raspberry Pi had been fried. Possibly also the A to D board (which was connected to the I2C bus) is damaged. A new Pi has been ordered, so once that arrives I'll know for sure whether or not the A to D board also needs replaced. Kind of ironic that the fuse that was inserted into the box to protect the Raspberry Pi happened to be responsible for destroying it. 😕

The total current weight of AMOS, with most of its electronics installed is now 28 lbs, about 8 lbs less than its beer cooler predecessor. I had been hoping for somewhat more dramatic weight savings with this re-design, but oh well. All those electronics and plastic boxes certainly add up I guess. Hopefully the improved hydrodynamic shape will make a big difference in the water. Before getting anywhere near the water though, there are still a lot of electronic hookups and cable routing to do!