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Topic: Sit Time (Read 300 times) previous topic - next topic

googlebot1

Hello,

I'm wondering what you would suggest?  I just want to create a simple sensor to stick on my chair to measure/log the amount of time I am sitting.

Best,

Coding Badly


http://arduino.cc/forum/index.php?topic=99510.0

googlebot1

#2
Jul 12, 2012, 06:18 am Last Edit: Jul 12, 2012, 06:59 am by googlebot1 Reason: 1
I had seen this, and it looks like it would sense that it is being squeezed. Agreed?  
http://www.sparkfun.com/products/9376

Or would it be better to use an LDR?  Or is there a LilyPad Arduino that would work well?

Any idea what I should do to have my mac recognize/track how long it's being squeezed?

googlebot1

#3
Jul 12, 2012, 06:22 am Last Edit: Jul 12, 2012, 06:31 am by googlebot1 Reason: 1


http://arduino.cc/forum/index.php?topic=99510.0



Thanks!  I hadn't even seen this post-  I'm wondering if there is something similar i could do but just for my one chair?

Coding Badly

I had seen this, and it looks like it would sense that it is being squeezed. Agreed?  


Bear in mind in may not be comfortable sitting on that thing.

Quote
Or would it be better to use an LDR?


I would go with something light sensitive like an LDR.  The problem is you may have to drill a small hole in your chair.

Quote
Or is there a LilyPad Arduino that would work well?


LilyPad.  Uno.  It doesn't matter.  You are still going to have to choose a sensor.

Quote
Any idea what I should do to have my mac recognize/track how long it's being squeezed?


I suggest you first choose a sensor likely to work well then worry about the programming.

Coding Badly

I'm wondering if there is something similar i could do but just for my one chair?


The question is how much are you willing to modify your chair?  Not at all?  Then an LDR is probably not a good choice.  A proximity sensor may be better.

Small hole in a discrete location?  Then an LDR is a probably a good choice.  They are simple, easy to work with, and cheap.

AWOL

Whoopee cushion and air-pressure sensor.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

dxw00d

How is the chair constructed? Is there a way to attach a flex sensor?

googlebot1

#8
Jul 12, 2012, 04:50 pm Last Edit: Jul 12, 2012, 04:53 pm by googlebot1 Reason: 1

I'm wondering if there is something similar i could do but just for my one chair?


The question is how much are you willing to modify your chair?  Not at all?  Then an LDR is probably not a good choice.  A proximity sensor may be better.

Small hole in a discrete location?  Then an LDR is a probably a good choice.  They are simple, easy to work with, and cheap.



I would be willing to modify it in any way, but of course the least modification the better.  But it was a chair that I was given for free.  Attached is an image of a similar one, it's just a standard task chair.

Knit fabric suspension back, Upholstered molded foam seat (no-tool replaceable cushion that pops off)


googlebot1


How is the chair constructed? Is there a way to attach a flex sensor?


Hi - See my last post about what the chair looks like.  The flex sensor might be a good option, but I'm curious, if it seems that as they flex the resistane across the sensor increases/decreases.  I'm not really interested in that, just on having the sensor know that it's being flexed, even if just slightly from being sat on and then beginning the tracking of the time.  I'm concerned though as you stand up if the sensor might still be flexed a bit just from the way a cushion is built.  Or if I were to stick it on a more stiff cushion chair would it even flex enough to recognize that I am sitting?  Any thoughts on that? 

winner10920

Id go with something capacitive, then no holes, just slip it under the fabric and maybe increase sensitivity if its too far away, look on the playground for capacitive sensing

googlebot1

#11
Jul 13, 2012, 06:54 am Last Edit: Jul 14, 2012, 06:23 am by googlebot1 Reason: 1

Id go with something capacitive, then no holes, just slip it under the fabric and maybe increase sensitivity if its too far away, look on the playground for capacitive sensing


I'm liking this idea for the sensor.  Do you have any suggestions of what parts/products to use to pull this together?  I've seen a few things now looking through some other examples but any thoughts in terms of this application?  

From this wiki http://www.arduino.cc/playground/Main/CapSense  it looks like I could use copper tape?   Also a little unsure on how the grounding would work?

Here is a snapshot of what the chair looks like with the cushion pulled off

winner10920

You don't actually connect ground to the setup, the ground is sensed thru the object
the larger the sensor the more sensistive it can be, it may take some trial and error to find out exactly what works

googlebot1

#13
Jul 14, 2012, 05:48 am Last Edit: Jul 14, 2012, 07:41 am by googlebot1 Reason: 1

You don't actually connect ground to the setup, the ground is sensed thru the object
the larger the sensor the more sensistive it can be, it may take some trial and error to find out exactly what works

Got it. As I am a beginner with this, would you be able to suggest which parts I would need to order to most easily put one of these together?  The overview here http://www.pjrc.com/teensy/td_libs_CapSense.html makes great sense, but its hard to know which parts are being used from the image and exactly how to put them together.  Does anyone know of a walkthrough tutorial for creating something similar? I greatly appreciate the support, this community is really amazing.

winner10920

I've only briefly played around with it myself, and that was with a 2.2Mohm resistor on the send pin, worked okay, but you may want something higher since the distance is a little farther, I would try a hard piece of metal so it doesn't get messed up under the seat, some scrap steel or something, attach a wire and wire like in that tutorial
but like I said it may take some trial and error, and just looking at that picture again perhaps the frame of the chair itself would work, hopefully without being too big and picking up too much noise, which in that case try a lower value resistor
and definetly connect the arduino ground to the earth ground if you can

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