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Unread 16-01-2012, 03:54
Jeremy Germita's Avatar
Jeremy Germita Jeremy Germita is offline
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Re: Potentiometer vs. Encoder

Quote:
Originally Posted by eannevelink View Post
Which option will give you a more accurate angle measure?

For example, an encoder gives you 360 pulses for every rotation. Is there a similar measurement for a potentiometer?
It depends on your potentiometer's number of turns.

Remember that the ADC on the cRIO is 10 bit. 1024 unique values.

If you have a 270 degree pot, that's .2636 degrees per 1 value.
Now look at your 360 pulses / rotation encoder. That's 1 degree per 1 value.
Conclusion: the 270 degree pot would be more accurate, at the expense of limited rotation.

Now consider a 10 turn pot. That's 3.515625 degrees per 1 value.
Conclusion: the Encoder would be more precise in this case, at the cost of being relative and not absolute.

So to answer your question about accurate angle measures, you must consider the pot in question.

Encoders
Pros: Infinite rotation.
Cons: Relative, a little more complex to wire up(3-4 lines depending on the encoder), very delicate.

Potentiometers
Pros: Absolute, simple to wire up(3 lines), a little more robust, more widely available
cons: (depending on the pot)Limited rotation.

Each has it's own applications. Encoders are traditionally used in drivetrains and other things requiring velocity and distance readings. Pots are used where absolute angle values are required.
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