Spine posture reminder
I've recently started a project for my electronics class:
My idea is to use angle sensors positioned on the spine to track it's position in 3D.
If the user slouches or goes into a non-optimal posture for a certain time (maybe 1min to avoid accidental triggering), the system recognizes this and reminds the user via an eletrostimulation-induced tingling sensation.
Here's a shitty paint drawing of my idea:
For now, I'm thinking of using simple potentiometers with a solid linked chain. Adhesion will be provided by one of my labmate's silicon adhesive (resists sweat, good strength and doesn't leave residue behind.)
My big problem currently is the electrostimulation system. I'm having trouble finding data on where I should start, most of what I can find is made to cause pain...
Any thoughts/ideas/criticism/etc?
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If you got paralyzed from a low voltage zap then we would have quads all over the planet from taser. Oh ya and I forgot to point out again that we made these in high school and used them on each other and guess what we are still walking. A camera doesn't have enough juice to do that kind of damage.
How do you plan to map the spine in 3D with potentiometers and chain? You can get a distance reading between potentiometers but that will only be accurate if the spine is perfectly straight and nothing touches the chain. Unless you're sitting on a stool your back will likely touch a chair's backrest while sitting.
Perhaps two potentiometers and a rod running to an eyelet on the next potentiometer module?
[Joystick modules]
This would be bulky and may be cumbersome but it would give you a good idea of where each module was.
If you wanted to go overboard, you could add a linear pot to the connecting rod and get your distance that way.
Depending on how many inputs you have you may also be looking at an analog MUX.
I have been using a tens machine for back pain and arthritis in my hands. I bought a cheap unit off ebay and have mainly been trial and error to get the right settings and positions.
One thing I noticed is that the some of the patterns and frequencies feel much different. Some of the settings, with the electrodes on my back, have a feeling almost like someone pressing on the skin under the electrodes. You would have to figure out exactly what frequency of pulses give that effect but it felt like it could be used to input data into the body from whatever sensor you wanted.
Another thing is that the "shocking" sensation becomes a lot more tolerable the longer it is running. At first, the low settings seemed pretty strong but soon I was cranking the power up to the highest setting. The low setting still could be felt though so even a low power should work as an alert signal.
Many years ago, back in high school, I made very simple shocking devices using a simple transformer and a dry cell battery. I think we often used a hacksaw blade and a nail to "pulse" the power going into the transformer as a kind of AC current. With DC, you only got the shock when first connected and when disconnected.
Nobody ever got hurt doing these experiments which included holding one electrode in each hand or having a whole group of people join hands and send the shock through all of them but looking back, it might not have been a great idea but it was a lot of fun.
Couldn't the same concept be used for this?
Three parallel strips should be able to gauge the position of the spine in 3d. This would be paper thin and super cheap.
I think any conductive film could work.