Posted December 17th, 2020 by SimpliSafe
In unprecedented times like these, you’ll want a sweater that can say, “happy Christmas” and, “back off!” all at once. So, we made a prototype.
The SimpliSafe Social Distancing Sweater. The only festive sweater designed to keep loved ones apart while together.
We use four low resolution thermal cameras to monitor your entire perimeter. The simple algorithm calculates the baseline background temperature and searches for a warm body in the vicinity. When the interloper is detected, flashing LEDs and a siren remind them to keep their distance.
This project is best suited for a skilled tinkerer, ideally with prior experience playing with hobby electronics. Have you dabbled with 3D printing, soldering, and programming? Awesome! That’s a lot of qualifiers, we know, but we wouldn’t be your DIY home security company without a nod to safety first.
If you’re under 18, you’ll need to enlist the help of an adult to supervise your soldering. Also, maybe do a quick self-assessment.
Still good to move forward? Great!
Adafruit Feather Microcontroller
Adafruit FeatherWing Music Maker
Small 4-8Ohm speaker
LilyPad Neopixel LEDs
AMG8833 Thermal Array Breakout
Ribbon cable (~28AWG)
USB Power Pack Battery
Inline USB Power Switch
Needle and thread
Adafruit Feather M0
The Feather platform is great for tinkering. Adafruit offers extensive libraries along with an array of Feather Wing add-ons that can be stacked on the main processor board if desired. The Feather M0 uses an ATSAMD M0 core processor, which provides ample Flash and RAM, along with a 48MHz processor. It also allows us to have a second I2C bus to handle the thermal sensors. We nixed the floating point arithmetic in the thermal library and just used integers for everything. In the end, the algorithm is simple enough that it could probably run on a slower processor.
Our RGB warning lights are 12 Flora NeoPixels wired in two sets of six, since we were using a pretty light gauge ribbon cable. We powered these directly from the USB, but our logic was 3.3v and we saw no issues.
We used an Adafruit Breakout to allow us to position them on our sweater, but they even have a GridEye Feather Wing that could make the wiring much easier.
Adafruit FeatherWing Music Maker
Since we’re using the Feather, this just made sense. It allows you to put your audio files on an SD card and play them back programmatically. This one has a small AMP on board which makes it super easy to hook up a little speaker and make some noise!
We picked Sobertons mostly because their form factor fit well, and their sensitivity is top notch at 90dB. But these are only 2W speakers on a 3W AMP, so be careful not to overdrive them. We used two because... full stereo alarm.
We kept it simple and used a 3.6-5V USB power pack instead of a smaller single cell LiPo. We recommend this route; keep it easy.
We used a 3D printer to make custom Lilypad LED and sensor mounts. Download the .stl files here to print your own. A high-resolution printer is recommended as the parts are very small; we used an MSLA printer with clear resin for our production. There are four parts total that serve three purposes: the stitch spanner, the LED mount, and the sensor mount.
The LED mounts consist of two parts—the light pipe and light diffuser. The light pipe is installed first using the stitch spreader to create a span in the knit of the sweater. The knob on the light pipe is then pushed through the span, and the sweater knit will close back around it. The legs of the light diffuser are worked through the knit to the inside and snap onto the light pipe. The LED module then snaps into the back of the light pipe.
The sensor mount is installed in a similar fashion; use the stitch spanner to create space in the knit to receive the “porthole” on the front of the sensor mount. The sensor snaps into the back of the mount, inside the sweater, and has a clear view through the knit to anyone that may come within six feet of you.
To get started, have a look at our schematic. We used 28AWG ribbon cable to connect most of our sensors and LEDs but we mounted the microcontroller on a custom PCB we milled with our Bantam Mill. We know—you probably don’t have your own mill. If that’s the case, you can use perfboard or even wires since there aren’t really components. The board just connects the Feather, FeatherWing, LEDs and sensors together.
Our Arduino sketch should be able to get you started. Feel free to modify the human detection algorithm to improve performance. Or for bonus points, you could probably even use these sensors to determine if someone has a fever. Speaking of fever, you can definitely update the alarm audio file on the SD card to feature more cowbells!
Ok, we didn’t quite knit it into our sweater, but our 3D printed mounts are sewn in! We used twill tape to cover our wires (so they don ’t get snagged if you’re trying to bust a move at the Christmas party). We also used wider twill tape to hold the battery and microcontroller boards in place at the bottom of the sweater. Want extra safety points? Wrap your battery in fire-retardant material to make sure you’re safely powered up and ready to keep friends and family at bay.
Once your sweater is complete, it’s time to show it off. Put it on, bust a move, and share it on social media for that sweet, sweet Internet attention. And don’t forget to tag @SimpliSafe_UK / @SimpliSafe with the hashtag #SocialDistancingSweater!
Handling your sweater
Like anyone, we love a deal, but make sure to buy safe reputable components for your sweater.
We recommend wearing a tee underneath your sweater as a buffer against the wires.
It’ll be tough to part ways with your new go-to sweater, but please don’t take a shower while wearing an electronic device.
It’s probably best not to put these electronics and 3D prints in your washer or dryer.
Remember to disconnect your sweater before storing it in your attic for next winter.
These DIY Instructions are provided “as is” without any warranty on suitability for any intended purpose. Further, any changes or modifications to these instructions are done at your own risk. You should review these instructions with your own sound judgment and take reasonable precautions involved with any DIY electronics project involving something you would wear on your body.
Don’t do anything we wouldn’t do. We’re not daredevils.
The Social Distancing Sweater is intended as a fun holiday conversation piece and not as a serious COVID-19 prevention device. Please follow the government guidelines.