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Author Topic: Measure the force of a hug...ASAP  (Read 424 times)
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I am working on a project where I need to have both audio and visual representation of the force applied by a hug.  I have asked around to several techies and in both cases the arduino has come up.  First, some Force Sensing Resistor would be placed on a mannequin torso (not sure of the quantity but would need to cover enough of the area to get readings).  Then with respect to amount of force a scale of high powered LEDS  would need to light up (bright enough to be seen in daylight, perhaps clusters of LEDS).  Finally given what ever the peak reading is a audio sound file would play.  A different sound for each range of peak readings.  There would be eight ranges, lowest to highest.  I would love for the lower LEDS to stay lit then decay down while the peak LED stays lit for 3 or 4 seconds or until released (reset) by someone.  Now for the real reason for the post-I have no idea what i am doing and need help getting this project completed in a very limited time.

Any help is greatly appreciated (shopping list, parts needed, programing codes)

I am located just outside of Philadelphia, PA in NJ

Thanks for your insight
Scott
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Most interesting project!  I am wondering what the units of HUG force are? luvies? huggies?

Think you need multiple force sensors and monitor them over the duration of the hug. Hugging is sort of a (body) language. I would advise also to include a temperature sensor to measure that dimension too.

Have you already code to read the force sensor?  Please post
What sensor are you using? Please post a link to the datasheet?

Familiar with the FREE HUG campaign - - ?
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Perhaps an air bladder inside the torso and air pressure sensor?
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Thank you both for your replies. 

The units of hug force can be what ever you would like them to be.  The end result of the hug only needs to be an audio and visual representation of how tight the person is squeezing the torso.  I would rather not make it more complex than it needs to be, no need to over think it.

I have no code, I have no hardware, I have no knowledge of how to do any of this other than basic theory.

The sensors that my techie friends directed me to are the Interlink Electronics FSR-402 Force Sensing Resistor.  http://www.trossenrobotics.com/productdocs/2010-10-26-DataSheet-FSR402-Layout2.pdf

I have though about doing Pneumatics and hydraulics.  The draw back I have with those is that this project will be dragged across America by an nontechnical person.  If a leak were to develop the piece would need to come back for repairs.  If it is possible to keep everything to a single technology that would be great (being electrical circuitry).

The time line for this project to be completed is 2 week from yesterday (not joking).  If either you (or anyone else reading this) have solid know how to make this project happen I am will to continue communications offline.  To get this project completed.

Scott
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It doesn't sound as if you have to measure anything specific and just want a way to get a general indication of force.

I would try to split the front half of a manikin torso from the rest of it, and mount it on a mechanism that holds it in place and orients it but leaves it free to move along one axis in the direction it will move when crushed by a hug. This would be very similar to the design of a set of bathroom scales and if you can find some suitable scales that would be an ideal solution - simple, robust, cheap and easy to source. Then you just need to have a way to make the reading from the scales actuate your display - if you use digital scales you may be able to read the force sensor output with an Arduino; if you use mechanical scales you could use a potentiometer to measure deflection of the load spring.
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Just to be clear, I was not talking about any complicated pneumatics or hydraulics, and there would be no need to really store air in it. Just a bladder connected to an air pressure switch. Nothing complicated.

A whoopy cushion could be your bladder. Having the chest set on springs, the movement of chest expanding after a hug would fill the air bag. A squeeze of the torso would deform the bag changing the pressure.

All that is needed is a check valve in the bag to allow air to draw in on one end. The pressure sensor would be attached to another port on the bag and that shouldn't require a check valve.

You would simply arrange it so that when to springs expand the chest, it pulls the bag open which would draw in air.

Perhaps a force resistor would work, but it will likely be about as much difficulty in installation. Simply slapping it on the outside of the torso is unlikely to work as you desire. So you would need some way of providing a moving chest plate and focusing the pressure on the sensor. This is not at all different than what I am suggesting.

BTW, all of the parts that I am suggesting could be salvaged from the cheapest blood pressure monitor that you can find. I could build this within a matter of hours.
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