Analog Inductive Sensor for Constant Height Offset?

[ddowns46]

I'm a mechanical engineer by trade and don't have a lot of experience with inductive sensors. What I want to do is a use an analog output inductive sensor (something like the Fargo S6108) mounted to a vertical slide controlled with a stepper motor so that the analog sensor is used to make adjustments to the stepper motor in order to keep the sensor always at 10mm above a metal plate. I'd plug the inductive sensor and the stepper motor driver into an Arduino for reading the sensor output voltage and converting this signal to a movement on the stepper motor.

Basically if everything was working properly, I could hold a steel plate 10mm below the sensor and move it up and down and this would cause the whole slide to move up and down (powered by the stepper motor) to maintain a constant 10mm of clearance distance. It would be a feedback loop to keep the sensor always at 10mm. For example if the nominal 10mm of distance on the sensor was equivalent to 6V and the sensor was currently reading 5V then the arduino would tell the stepper motor to move up in order to reach the desired 6V aka 10mm. Due to the presence of water and other contaminants, an optical sensor will not work.

I'm wondering if this setup is feasible and could work as described? How fast can the analog inductive sensor signal be read to make adjustments to the slide position with the stepper motor? The stepper motor will be capable of 500 IPM travel with high acceleration so it should be able to keep up fairly easily.

 

[itsmoked]

That should work. You never said the accuracy but if you're looking for a couple of thousandths it should work okay. Expect about a 1ms update rate of the inductive sensor.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Skogsgurra]

There is a little thing to care about. If temperature changes or if the plate moves in X or Y direction (assuming vertical is Z), you will have an influence which may or may not be tolerable.

But if stationary, it would be OK. And, with the liquid present, I guess that temperature variation will not be a problem.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[IRstuff]

Rate loops can pretty much keep up with the update rate of the sensors, but position loops are are typically 5 to 10 times slower than rate loops.

TTFN (ta ta for now)
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