Need motion sensor

[Larry E]

Hello, my name is Larry E Elliott,  My wife is confined to bed and  is not allowed to sit-up for long periods.  I would like to build an alarm to sound  when she does.  This not a life and death thing, it would just be convenient to know when she first sits up so I can go she what she wants.  I have an Aduino board and can build simple stuff.  Could you please recommend a system that I might build to help me with this project.  Attached is a Sketchup of her room.

Thanks for what ever help you can offer, Larry  615 969 0688

[robtillaart]

Just thinking out loud:

- a pressure sensor under the pillow/matras(?) could be an alternative as it won't trigger the alarm if you walk through the bundle.
might need some calibration

- a distance sensor (aka PING) that will measure distance to the wall and will detect if she sits up.
Note the range of these differ quite a bit. There are examples on the playground.

- Also add some buttons she can press when she needs you. You could even add multiple buttons for different requests
button 1 = come quick
button 2 = come ( no hurry)
button 3 = meal (BF, L, E)
button 4 = phone
button 5 = cup of tea, water, orange, juice
etc.

[Larry E]

Thanks for the suggestions.  Jane is not with it enough to push buttons.  Bed alarms don't work, if she only sits up, we tried those things.  I think I need a system with a beam that she would interrupt when she sits up.  Thanks again for the input.  I will go find this playground thing.............LEE

[keeper63]

Thanks for the suggestions.  Jane is not with it enough to push buttons.  Bed alarms don't work, if she only sits up, we tried those things.  I think I need a system with a beam that she would interrupt when she sits up.  Thanks again for the input.  I will go find this playground thing.............LEE

Other possible suggestions:

PIR sensor - motion sensor like that used on alarms - http://www.goldmine-elec-products.com/prodinfo.asp?number=G12959 - you would have to hack this, of course (just hook up to the LED)

Laser "tripwire" type sensor - something similar to this: http://www.goldmine-elec-products.com/prodinfo.asp?number=C6739; there are also similar circuits using a phototransistor, etc. Sense the "beam break".

What you would probably want, though, is more than one of these sensors; maybe a pillow sensor, the tripwire sensor, and the PIR sensor - then set things up to eliminate potential "false positives".

Although - if I am reading your situation right (and if I am, my sincerest best wishes for your family) - a false positive will be better than missed one...

Hope this helps.

[Larry E]

Thanks for real good the suggestions.  I think you are right about duel systems.  I went to the goldmine site.  I am going to buy both of those items and see what I can work out.  Thanks again, I will keep your address and let you know how I do....LEE 

[wayneft]

A lot of the newer digital accelerometers have orientation detection functions built right in that can be tied to interrupts.  You would really just need to tweak the angle that it trips at.

[Larry E]

Thanks for the tip. I am looking into that now......Thanks again....LEE

[pYro_65]

I am messing around with an HB-100 doppler radar motion sensor.
These are used in stuff like automatic door openers, alarm false positive prevention, speed guns...
This could even be positioned on the end of the bed, rather than on the opposite wall

Got mine off ebay

http://www.ebay.com.au/sch/i.html?_from=R40&_trksid=p4712.m570.l1313&_nkw=Microwave+Doppler+Radar+Wireless+Module+Motion+Sensor&_sacat=See-All-Categories

I easily got it sensing 3 - 4 metres with a simple audio op-amp circuit.

http://gilmore2.chem.northwestern.edu/projects/cmoy2_prj.htm

Here is a link to a useful topic also

http://arduino.cc/forum/index.php/topic,61989.0.html

and the post down the bottom has a link to a data sheet with circuit diagrams

http://www.agilsense.com/pdf/x-band%20sensor/MSAN001-V101.pdf

[Larry E]

Thank you Down-under, for taking the time to lend a hand.  I am looking into your idea.  I am looking for a sketch that I can use.  I have looked at the amplifier circuits, I think I could handle that.  I will post my results.

Thanks for you help, Larry