Out-of-phase detectors produce two pulse signals that indicate relative rotation as well as direction for an incremental encoder. Counting edges or monitoring binary values can increase resolution fourfold.
Great article - I particularly liked the mention of using hall effect sensors. Makes sense since historically they have been used as rotary position gear tooth sensors such as crank and camshaft sensing in automotive applications. They are usually a lot cheaper than optical encoders too.
Hello, TJ. As far as I can tell, the magnetic field for a Wiegand detector must be very localized, so magnetic interference shouldn't become a problem. Resolvers get used with equipment that uses electric motors, so I bet the manufacturers have added shielding as needed. Worth asking about before you buy a resolver, and worth the time to run some tests in proximity to specific equipment.
In my applications, I often need an axis with a hollow bore, so the position encoder either needs to be hollow. From what I can tell, the Wiegard effect only works when the rotating magnet axis of rotation is centered about the Wiegard wire. I'm sure I've misunderstood the tech in some way and hope that my understanding is wrong.
If my understanding is wrong and the axial rotations do not have to align, then I'd be inclined to merge an optical absolute encoder with a Wiegard sensor for counting rotations. You'd get the resolution of optical with the persistent turn counting of the Wiegard sensor.
I hope to see more of the Wiegand effect encoders in the near future. It might be a good alternative to optical encoders in a closed loop stepper motor system. Which, by the way, are getting cheap enough for anyone to buy.
Truchard will be presented the award at the 2014 Golden Mousetrap Awards ceremony during the co-located events Pacific Design & Manufacturing, MD&M West, WestPack, PLASTEC West, Electronics West, ATX West, and AeroCon.
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