Looking for recommendations/creative solutions (…and yes this will be used to trigger an LED sequence).
Here is the scenario… Imagine your outside at a evening festival drinking a beer (or beverage of choice) and you want to trigger a LED sequence (wearables project) every time you raise your cup/bottle to your mouth (without any interaction by you, ie. button pushing) just by the natural arm/wrist motion that you make raising the drink).
My leading contender for a solution involves a hall sensor placed somewhere near my inside wrist and a magnet sewn into my front shoulder area (…right now I suspect many of you are making the drinking motion to see the spacial relationship…). But I have never used hall sensors before and not sure about this approach.
The thing that sucks about reed sensors is proximity. I have one currently on my garage door to tell if it’s closed or not and if it’s not within an inch or so it does not activate. Have you looked into the accelerometer/gyro sensors? It would also activate if you were walking unless you programmed it not to, so I’m not sure that would suit your purpose. Sensors are about 30 dollars at radio shack but I’m sure you can get them cheaper online.
I think accelerometer would give you better results than proximity modes. RFID & Hall sensors both must be very close for it to trigger correctly.
A final thought would be a long piezo-resistor (sensitive to stretch) strategically placed over the elbow to read a stretch threshold trigger when you go to take a drink
Might be fun to hide a pressure sensor in each shoe located under your big toe for additional super sly triggering. Something like https://www.sparkfun.com/products/9375
Janine/James - I like the tilt switch idea (as long as I don’t raise my hand for any other reason…) That might be a good simple approach…Thanks!
Marc - I thought about a pressure sensor but as the ummm…evening progresses…I have to remember to trigger it when I’m actively drinking. I have one these laying around (https://www.adafruit.com/products/1332) and had planned on sewing it into the cuff of the left arm of the jacket to trigger different modes, etc…BUT I really like the idea of the sensor in the shoe for the super sly trigger of some special sequence or something…hmmmmmm
How about an IR LED on one side and an IR detector on the other. Should be able to measure the brightness, and you can use a special signature (eg, ON off ON off ON off) to make sure you’re actually reading the LED and not ambient IR radiation. (And brightness will be a proxy for distance.)
Won’t you get a lot of false positives with a tilt switch? I suppose if you made a beer cozy, as long as the beer is upright you can assume it’s not being consumed. But for drinks with a straw in them… #overengineering
How about a Wii nunchuck? It has an accelerometer and you can get clone ones dead cheap on eBay. I picked up 5 for 10ukp. And they are a doddle to connect to Arduino, with an adapter or hardwired, and lots of examples of code are available online. You could strip the innards from the controller to sew into some clothing. Not sure how it would work in tandem with FastLED though…