9 Days In

So it has been 9 days since I switched to half-time at my regular day job and half-time on AMOS. Well actually it's working out to be significantly more than just "half-time" on AMOS, since a good chunk of my evenings have also been spent sourcing parts and trying to figure out the best possible way to put all this stuff together.

Some progress has been made over the past few days, albeit with a bit of a setback last Thursday: the day before I had written some test code for a sort of crude object detection algorithm, using image data from the two Raspberry Pi cameras. That evening I had re-drilled a hole for mounting one of the cameras, while the camera was still mounted on a post in its old hole. Very bad idea!!! Never drill next to a circuit board with tiny little parts if you can help it. Some small component (possibly an inductor or a zero ohm resistor?) fell off the board and was lost forever. I attempted to repair it myself, the next day, but ended up accidentally shorting out a connection (which I believe) fried the camera interface circuitry on my Raspberry Pi Compute module. So crap. Anyway, this required ordering both a new camera and Compute module. Hopefully they will be here soon.

I also got some code written for testing out a number of different things:

1. Code for turning on thrusters and controlling their speed and direction. Right now I have it limited to about 50 W per thruster, well below the maximum possible 350 W that they are capable of. This is a fairly small boat with limited power resources (10 Amp-hour battery) so I think 50 W per thruster is probably reasonable. Can't wait for the battery to arrive so I can try them out :-)!

2. Leak sensor code: this was pretty simple and worked as expected... I used the SOS leak sensor (https://www.bluerobotics.com/store/electronics/sos-leak-sensor/) from BlueRobotics and just had to monitor a GPIO pin to see if any of the sensors had gotten wet. A couple of drops of water on one of these little disc sensors caused it to swell up and grow (kind of like those kids toys that expand in water) and it must have changed its impedance or something because the digital output of the SOS leak sensor changed right away.

3. Code for sending SMS text messages: for this I used a service provided by Twilio (www.twilio.com). It was pretty simple to get going... basically I got a free trial account from Twilio which gives me a local phone number that can be used for sending and receiving SMS text messages. I think it can even do voice calls too, but I won't be using it for that. I'm not sure if the Twilio account will still be required once I have a cell modem up and running with actual data service, but it works great for now with my Wifi Internet connection.

A crude bathtub buoyancy test of the AMOS boat (beer cooler) showed that it will ride pretty high in the water if there isn't much weight in it. With 30 lbs worth of dumbbells inside, it sat a little bit lower, but tended to list to one side a lot if the weights were not well balanced. 

Last night I spent some time in the garage cutting out strips of plywood, with the intention of building a framework of sorts for supporting the 100W flexible solar panel. If possible, I would like to also mount the thrusters on the same framework and hopefully avoid drilling holes in the hull of the boat. Some holes will inevitably be required for cabling and the cameras, but these could be above the waterline, and would not be subject to significant stresses, such as might occur from the thrusters.

Lastly, I have ordered some more electronics components:

1. Micro 3G/GSM Shield for Arduino & Raspberry Pi ($120 Cdn)
2. Raspberry PI GPS Module ($47 Cdn)
3. LSM303D 3-Axis Accelerometer and Compass ($10 Cdn)

Just this morning I started writing some code for the LM303D; planning on connecting it to the I2C interface of the Compute Module. There's a lot of functionality packed into that $10 board, although I'm not sure how accurate it will be; my experience with other magnetometer-based equipment seems to be that you are "doing well" if you can achieve something like +/- 10 degrees of heading accuracy. With a working GPS though, this hopefully won't be too much of an issue.