meaurement of Revolution per second of static shaft around which bearing is moving.

Hi i have come acorss a problem in which i need to measure revolutions per second (rate ) and direction of spin in such a way that main shaft is static and only bearings across it is moving.Now i can not use potentiometer for the measurement because shaft is static so i am thinking about the shaft optical encoder ?? Any one having better idea can please guide me

Ali

I think you can use the approach below for that ..... you can use two detector and a light beam and need to have reflective area on the shaft on the rotating machine movement you start rotating machine you will get the reflection of light on the sensor ... on either direction.....and will able to get the signal from the sensor and the direction on the motor too .....but remember .....this is a concept ....I need to work out with lot of details like do u planning to use pulse laser, what should be geometrical consideration of detector and source position etc.....



I had attached the picture for your reference....

Good Luck

Hi ,Thanks for help but have you considered this fact that one shaft is static and another ring is moving across it .
Best regards
Ali

Sorry Ali,
I think I miss understood the problem....I think I really miss read the post....

With regards,

milind

Ali, you say that the shaft is static and the bearings are moving; and I'm guessing you want your sensor to be static w.r.t. the shaft? (i.e., as the bearings spin, the sensor and its signal wires don't spin with them). Anyway, you are only counting full revolutions which makes things easy. You can adapt Milind's idea to your situation by shining a laser at the bearings rather than at the shaft. Or, you can use an opto-interrupter. Another alternative is to use a hall effect sensor. There are many methods you can use, and the decision boils down to what application it is being used for.

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Ali, you say that the shaft is static and the bearings are moving; and I'm guessing you want your sensor to be static w.r.t. the shaft? (i.e., as the bearings spin, the sensor and its signal wires don't spin with them). Anyway, you are only counting full revolutions which makes things easy. You can adapt Milind's idea to your situation by shining a laser at the bearings rather than at the shaft. Or, you can use an opto-interrupter. Another alternative is to use a hall effect sensor. There are many methods you can use, and the decision boils down to what application it is being used for.

Hi i have uploaded the image of my system so that you guys can better understand the scenario.I can not use optical interrupter because my light source on moving part and optical strip is also moving while my light sensor to pick off light is on the static part .
Some how i need to design a system to accommodate optical encoder scheme but i don't know in which configuration i must use it.
Secondly i need to measure degrees/second of revolution i.e i want to know the rotational displacement with resolution of atleast 10 degrees.
I have tried to used Hall sensor but its resolution i s limited in a a sense that i can use limited Hall sensors around the shaft.

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i have put two detectors and light source on the static shaft and shining part is present on the moving part around it.Will it be enough to give me measurement in degrees/sec i.e i want not only revolutions per second but also i need to measure the revolutions with enhanced resolution.I have also uploaded the picture of the system so that you can understand better.

Thanks for your precious time sparing.

Ali