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Unread 22-08-2013, 23:55
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Re: Low Cost Encoders

Quote:
Originally Posted by techhelpbb View Post
Finally all the parts arrived:

So I have a 5V 4096 position per revolution stepper (it is geared down) with ULN2003 to be driven by an Arduino or the like.

A dual LS7366R quadrature encoder PCB to monitor the encoder outputs.
U.S. Digital sells this component I bought the PCB from SuperDroidRobots.com.

A ServoCity set screw hub for the stepper.
A ServoCity set screw hub for the encoder.
They are different size bores. The same 6-32 tapped bolt pattern.

The Chinese encoders to be tested.

Now I need to make a mount and wire this up.

Then I will have set up a realistic environment turning the encoder back and forth for an extended period of time.

I will be able to tell if the encoder is missing pulses because I will mount 2 limits at either end of the rotation (so it won't rotate all the way around).

I will program the stepper to rotate till the encoder hits a point just before the limits on either extreme.

If it misses (by any serious margin) it will smack the limit and an error can be recorded.

Leave that run for a good long time and eventually it'll exceed the entire service lifetime FIRST will likely ever ask of it.

Plus, of course, it gives me lots of time to record samples of the output waveform.

As the entire motion is under Arduino control various speeds of rotation can be tested.

It would be extremely unlikely the LS7366R would roll over or miss a pulse so it would be safe to say any error like that is the encoder or an electronic issue.
Wow, it looks like a very thorough test. My test would be to see if it reasonably well, drop it out a window and see if it still works. : But I think your test is much better.
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