Instrumented People, Places and Things: the napkin dispenser study, 2011
Start here
Sensing an object in use. In the winter of 2010–11 Iota put small wireless sensor modules on the napkin and paper-towel dispensers of a small independent coffee shop, to see what one everyday object could say about the people using it: how many napkins each person takes, and when, how full the dispenser is, and how long an empty one waits to be refilled.
Each module read eight inputs about eight times a second and radioed them to a PC in the shop, which logged them with the time. A webcam on the same PC took a picture four times a second. This replays the day, the readings and the pictures together.
A first look
This page puts the streams and the pictures side by side, so we can work out together which module sat on which dispenser, what each input sensed, and what taking a napkin looks like in the data. Nothing here is a model yet.
From the modules' firmware: inputs A0–A2 were an accelerometer, and A3–A7 plug-in sensors. Inputs that never changed are left out; each is drawn across its own range for the day.
Jolts are moments a module's accelerometer moved well past its noise: the three axes together more than 60 counts from their 10-second average (a g is about 250). They are candidates to check against the pictures, not napkins taken.
Space plays and pauses. The arrow keys step a picture, with Shift ten seconds; N and P open the next and previous jolt. Click a graph to set the time; scroll to zoom.
An Iota project. Thanks to the coffee shop.
Modules
| Graph | Module | Inputs | Jolts |
|---|
Jolts
Data panel
Tick Graph beside a module to graph its inputs here.