17 July 2019

I haven't been doing much with this project except collecting data from my one and only prototype currently living under the lid of my recycling can. I placed it there in April and was happy it survived its maiden pickup. Since then I have mostly ignored it. Well, today I finally took a look on CayenneLPP and this is what I found:

Not great resolution but you can see 1) the device has been continuously operating for about three months, 2) it is more or less recording fill level (in millimeters, but this might as well be percent for a 100 mm deep bin!), and 3) it has survived about a dozen pickup events where the bin is clutched by steel arms, hoisted up from the ground, dumped upside down, then dropped on the ground again. Yay for VHB foam tape!

Here is the record over the last one month for better resolution:

I have marked the last four pickup events by hand in red (we missed the one on July 3). I am still getting excursions when the bin is empty above the 100 mm mark due to both high temperatures when the bin lid is exposed to the sun and inherent inaccuracy in the VL53L0 due to the low-power (i.e., fast) setting I had chosen rather than perhaps a more appropriate high-accuracy setting. Still, this record is clearly capturing the instantaneous fill level of the bin. In particular, it shows that the bin often gets more or less full days before the pickup. This kind of information could be used to adjust the pickup times; in this case more often than once a week is indicated.

Of course, I recorded other environmental information (last month shown):

temperature (top), pressure (middle), and humidity (bottom). Also battery voltage and lux from the light sensor, but none of these are as interesting as the bin level itself.

Next step is to have my 15-year-old son design a 3D-printed case for the bin level monitor. The Hammond case works well but required "subtractive" machining to make the well for the VL53L0 + window assembly. I am wondering if I couldn't have an inexpensive 3D-printed lid made for the Hammond box that would allow quick assembly of dozens of these bin level monitors so I might offer them for sale as a complete device. I'll report on this next time.