Distance sensor for diameter compensation

[lukin1977]

We have in operation one re-spooler machine to wind welding mig wire on 15 kg plastic spools

The machine consists on a un-winder, a dancer unit and a winder

As the unwinder gives wire to the winder the diameter of the wire coil decrease. To compensate the diameter reduction there is installed a sensor (see picture attached)

The sensor is very old and it was custom made for it. I am not sure what kind of sensor is, but I am guessing is an ultrasonic sensor

The signal from the sensor is unstable (it varies +/- 1V ) while the coil is spinning and this is making the speed syncronism between winder and unwinder to become unstable too
My first thought was that the problem was a signal interference through the cables so I made a few measurements and the signal is coming unstable from the sensor it self

Is an ultrasonic distance sensor good for this application?
Is there another type of sensor that will not be affected by the spin of the wire coil?

Any help will be apreciated

 

[itsmoked]

Thanks for checking that.

Those values are still a great place to start and likely will do the trick for you.

Let us know how it works out!

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

Your originally noted variation in readings seem large compared to your full scale values, i.e., ~20%

The resistance and capacitance values mentioned above result in a 1 second time constant, so you need to be careful about whether the time constant is compatible with the timing of how the transition from one layer to the next is detected.

TTFN
faq731-376

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[lukin1977]

Just finished the test with the L-P Filter. The signal from the sensor is much more stable now but I want to stabilize it a little more
Now the signal oscillation is +/- 0,3 V

Should I used a bigger cap? 150 uF? 200 uF?
Resistor used is 10k

Process speed performance has improved a lot!

 

[Skogsgurra]

Yes, increase. The 1 second time constant was just an informed guess. Nothing beats reality - so increase until it looks good.

Gunnar Englund

http://www.gke.org

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

 

[lukin1977]

Tried with a 220uF cap and now the signal is very unstable again. I think even worst than without the filter! Not sure what is going on. I think I am going back to the 100 uF cap

 

[Skogsgurra]

Sounds like you are getting too near the phase margin. Sometimes, you have to accept what you get.

How did the problem start? Did it ever work well?

Gunnar Englund

http://www.gke.org

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

 

[lukin1977]

It was an used machine when we got it. A little after we bought it, I have to update the controls: old analog DC drives and analog control boards. I have installed new drives and a PLC. I also have to installed a dancer PID control board

Did it ever work well?
I am not sure. It took me a lot of time to get the machine to work. Specially to calibrate the PID control. Now I think that 50% of the problem was the signal from the distance sensor. I did not notice back then