I want to build my own wii balance board which I can use at the computer - I'll use the Teensyduino for this project - which then will interpret the sensor values into key presses.
I don't want exact measurements about wheigt, I want information about the users is leaning to the left/right/back/forward or just standing on the board.
I don't want to use a gyro-solution - because I want a stable board - really with pressure:
I read this instructable but the sensors are really expensive:
I read that the original wii balance board use strain gauge
But how what kind of strain gauge? Where to shop? How should the curcuit for my application look like?
I also read about FSR at lady ada - but are these sensors a good idea? Read about only 10 kg per sensor? And I think I would need 4 FSR in every corner? http://www.ladyada.net/learn/sensors/fsr.html
Or building an own FSR with conductive foam - but not sure about if it is too much wheight when standing on the board.
Is there a reason to not use the actual wii balance board? They connect to the wii via bluetooth, all you need is a bluetooth dongle for the computer and a driver..
Do you need this home-made board to support the full weight of an average adult? Do you need to know which corner is depressed or do you also want to know how much the corner is pressed down? If you just need which corner is depressed, put a push button (heavy duty) on each corner with some spring support. It might be easy to do.
I don't use the wii balance board itself, because since windows 7 (before vista) I can't even connect my wiimote to the computer anymore - tried different bluetooth stacks + sticks - but doesn't work anymore. So I don't want to buy a 80 EUR balance board and then it doesn't work. I want a usb-cable connection - I want to build my own - with the teensyduino.
@liudr
Might be a good idea with the switches, but I am afraid, that it is to unprecise to regognize when just standing in the middle of the board and doing nothing - because switches only have on/off-state.
So are those FSR sensors "to weak" for that ?? - thought maybe I could put one in every corner and when just standing on the board I take this info as the - "just-standing" info and then I can recognize every leaning to a corner.
The frs you linked to has a max range of 20lb so with one on each corner and person standing in the middle you have a maximal range of 80lb, not so big especially when someone leans over one side and that side can overload. If you use those sensors you need some lever to reduce force acting on them.
Why don't you use a simple digital balance? someones have four load cells, one for each corner.
Simply disconnect the four cells from contol board and pull out their own supply and signal wires.
With four INA125 you could amplify signal accurately enough to be read by four analog pins.
INA 125 are quite expensive, if you wanna build the BB cheaper there are a lot of LM328/358 load cell signal amplifiers project on the net, a bit difficult to build & less precise, but you'll keep a bunch of $$$$$$$$$ in your pocket!
@liudr: how should I use or apply a lever to the sensor? Is this what you mean with that: Lever - Wikipedia
@lucareds7: I also thought of using a digital balance - because I read of those sensors. But I thought - hey what's in the digital balance - you can also shop online So first I would have to find a suitable scale and this makes my project depending on digital balance availability
So first I would have to find a suitable scale and this makes my project depending on digital balance availability 