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Help! how to use sensor to detect gap 0.2mm?


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saloi

Mon Jun 23 2008, 10:05PM

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Hello all,

currently I have a problem with the gap of my project. My project compenent have gap btw the motor and chassis. It supose to be no gap (<0.2mm). So my question is how to
design the sensor that detect the gap. thank you.

Ajay

Tue Jun 24 2008, 08:30AM

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laser sensor?

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saloi

Thu Jun 26 2008, 11:16PM

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omron smart sensor? but it will cost a lot. i want a cheap and easy to develop sensor which can detect gap between 2 metal. thank you.

Ajay

Sat Jun 28 2008, 07:01AM

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I dont think you will get cheap sensors for such high precision.

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sashijoseph

Sat Jun 28 2008, 11:17AM

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@saloi
You could probably use an LDR attached to a 0.2mm shim or feeler gauge and arranged like this...

If the gap is more than 0.2mm more light would fall on the ldr,which after a certain threshold would trigger a gap violation condition.
A high sensitivity ldr would be needed.The physical arrangement,ambient light conditions,proper sealing of the ldr from ambient light etc would be critical.Even with all this the repeatability and precision would have to be seen after construction.

Let there be music........

shyam

Sat Jun 28 2008, 11:29AM

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go u only want to detect gap or measure it??

lProgress is not made by early risers or hard workers, but by LAZY people, trying to find easier ways to do the same........

Arun Kumar V

Sat Jun 28 2008, 07:31PM

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hi saloi,

you also can try using a Peizoelectric wafer between the motor and the chassis to know if there is any deviation. Peizo element inside any buzzer can be inserted and if the motor is too close and hits the peizo element an AC pulse is generate from it which can be used to trigger the gate of a sensitive mosfet which connects to a micro........

Arun