Dog Weight Scale part 16: Data!

In my previous post I changed the uploader app to run when the Raspberry Pi turns on, and installed the scale under Pippa’s dog bed. In this post, I get interesting data from the scale.

The scale has been running for a little over a week now, and has been surprisingly reliable for a first version. There is some sort of bug in which, every few days, the scale stops supplying new data BLE notifications to the gateway. I plan to refactor the scale and gateway to avoid that, but that’s another post.

Today I looked at the data and saw some very interesting things.

Total weight in the bed, over 8 nights
Total weight in the bed, over 8 nights

You can clearly see when Pippa is in or out of the bed, from the large jump or drop in weight. Ignore the angled line – that’s an artifact of the scale stopping and the graphing program drawing through the missing data.

Most nights Pippa sleeps through the night, with one or two 15-minute periods of wandering around the bedroom in the middle of the night.  On the two Monday nights, she seems to get up a lot more. Monday evenings we take Pippa to Nose Work class – the hobby version of bomb-sniffing dogs – where she works very hard, gets lots of treats, and gets dinner about 3 hours later than normal.  We’re not sure which of these things makes her sleep poorly on Monday nights.

Weight from each corner of the bed over 8 nights
Weight from each corner of the bed over 8 nights

Pippa does flop around in bed every night. The above graph shows the weight measured by each of the four corner Load Sensors in the scale (again, ignore the angled lines). Whenever the values change, it indicates Pippa has shifted her weight in the bed – for example, by turning over.

If I want to see Pippa’s weight gain or loss, I do need to calibrate the bed better.  If the bed were properly calibrated, the total weight on the bed should remain close to the same number as Pippa shifts about in bed.  Looking back at the Total Weight graph, you can see how Pippa seems to become lighter and heavier as she moves around in bed – clearly not true. By the way, I’m now thinking of calibration as two distinct factors: 1) how closely sum of the four Load Sensors remains the same as the weight shifts (how closely the Load Sensors are matched), and 2) how accurately the sum of the weights reflects the actual weight on the bed. More on that in a later post.

Weight at the four corners for one night - July 12
Weight at the four corners for one night – July 12

Pippa shifts a little every few minutes, all through the night. Does this mean she’s uncomfortable? …dreaming of chasing rabbits? …listening to coyotes? …cooling off? More data means more questions.

The Quantified Dog is here. All this data is readable at Pippa’s Bed Weight stream.  Upload your own dog or cat’s bed weight at data.sparkfun.com