Monday, April 18, 2022

AMOS Wireless HAT Module

 A lot has happened in the last few months, both in the greater world and in my own life. The war in Ukraine has unfortunately occupied much of my attention. I'm hopeful that the Russian invaders will be repelled from that country, but the present situation there is terrible, and I fear for the worst, both for Ukraine and the world as a whole. In my own life, I started officially working full-time at Measurand in March, although I had been unofficially working there full-time since November of last year. This means a bit less time for AMOS and In Nature Robotics, but the job itself is interesting, involving embedded product development and firmware. Plus having a full-time salary is helpful, given the way costs seem to be going higher and higher lately. 

In my own experience using AMOS, and in some of the feedback I've gotten from customers, one recurring issue has been the tangle of wires within the AMOS CPU box that connect the Raspberry Pi to the rest of the equipment (wireless module, AtoD, sensors, etc.). Sometimes one or more of these wires become disconnected, and it can be a challenge to find the disconnected wire and attach it to the correct location. 

Enter the new AMOS Wireless HAT (HAT stands for Hardware Attached on Top). 

It has a 40-pin header that plugs directly into the Raspberry Pi board, and uses printed circuit board traces rather than wires to connect the AMOS wireless equipment, AtoD board, and temperature and humidity sensors. It also allows direct soldering in of wires from the battery box module (for the propeller and rudder control). 

I have already noticed a few things that should be changed on the board, but the order for the first 5 prototypes is already in production, so I'll populate one to see how it goes, and then make some changes after that. 

The weather here is warming up; I'll need to get the demo AMOS up and running again to do some weekend testing again soon!

Sunday, January 23, 2022

Winter QA Testing

 Generally it's not a great idea to do AMOS testing in the winter-time. The local rivers and lakes are frozen, so an hour's drive is required to find the nearest available liquid water in the Bay of Fundy. And careful planning is required to ensure that tides, wind, waves, and the cold are all manageable. 

Two recent AMOS robot sales however required that the testing be done, so the van was loaded up in early January for a test down to McLaren Beach, just outside of St. John.

Both AMOS robots were equipped with underwater camera modules. Unfortunately, these proved to be problematic for the air temperatures of -7 deg C and water temperatures of 5 deg C. The plastic tubing, normally quite flexible at room temperature, became as stiff as steel in the cold. In shallow water, this meant that AMOS would get stuck (if it was moving slowly) or might snap off the top connector of the tubing if it struck the bottom at a high speed. So I packed everything up and headed back to make a couple of plugs for the camera holes; the underwater testing component would have to happen indoors. Fortunately the final destinations for these robots are considerably warmer than Canada in the wintertime, so freezing camera tubing won't be an issue. 

A return trip was then made to the Irving Nature Park a few days later, as McLaren Beach was inaccessible due to a recent snowstorm. The waves were stronger here, as it was less sheltered, but the first AMOS went through its sampling course flawlessly. The second one had trouble even starting however. It started up fine prior to leaving, and started up fine inside the van, but within a few minutes of having it outside on the beach (again about -7 deg C) it abruptly lost power and the LED light on the  power switch went out. My guess at this point was that the switch was faulty and didn't perform well in the cold, so after driving back I replaced it. 

A third trip was then made a few days later to Lorneville, as there was a strong wind out of the south that day, and the selected spot offered a bit of shelter from the strong open-water waves. Once again however, the AMOS robot lost power in the cold, usually shortly after the propeller was driven at high speed. This time I thought to carefully check the solar charge controller, and realized that its short-circuit protection circuit was engaging. This was a newer version of a controller which I've been using for the last 3 years; previous versions allowed you to disable the short-circuit protection feature, but this version did not. So back to Fredericton, to replace the solar charge controller with an older model. 

On the fourth trip back (to McLaren Beach), the 2nd AMOS robot also worked flawlessly:

So now both units have been shipped out and are due to arrive early this week. I'm looking forward to seeing how they will be used over the next few months. Hopefully around the middle of this year I will be able to provide an update blog with some details!

In support of these systems, the support page has been updated, and a number of YouTube instructional videos for assembly and testing have been created. These are a bit rough at present, but they should be effective I think.