Strain gauges

[Qubix]

Anyone implemented a strain gauge circuit? Whats the easiest way to do it?

I know you need a wheatstone bridge arrangment, but will I need to build it myself? or can I buy some set up that lets me do it in a more plug and play method (at a reasonable cost  )

Thanks

David

[Admin]

Hmmmm does it need to be electrical, as opposed to a simple mechanical gauge?

What type of strain, and on what material? Whats your typical expected forces and strain %?

[Qubix]

Yeah it would need to be electrical. I'm looking to find the force in flexible link, when its bending. Probably going to go with something like a cable tie for the link, so plastic would be the material.

Not sure about the percentage strain, the but forces would be quite small I would imagine. I'm not that worried about finding a suitable strain gauge or attaching it, really I was wondering about the easiest way to condition the signal to make in usable by a microcontroller? if anyone has any experience with them.

Many Thanks

(its a project to control a simple flexible robot "arm", I'm not that interested in cable tie forces in general )

David

[Admin]

Not sure about the percentage strain, the but forces would be quite small I would imagine. I'm not that worried about finding a suitable strain gauge or attaching it, really I was wondering about the easiest way to condition the signal to make in usable by a microcontroller?

Sounds like you need something expensive professional . . . you basically buy these sensor strips, then buy some expensive 'special' glue to attach it on to your thing that needs to be measured. With what you seem to require, it definitely needs to be sensitive and I wouldn't know how to custom make one with those specs.

For the electronics, you basically need to amplify it with a wheatstone bridge as you said. Try and get it so the signal maxes out around 5V, the max of your ADC on your MCU:
http://www.societyofrobots.com/sensors_forcetorque.shtml#wheatstonebridge

You will need have to calibrate the signal:
http://www.societyofrobots.com/sensors_interpret.shtml

I hope that gets you in the right ball park!

[Qubix]

Thanks for your advice. I'll let you know how I get on.