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Unread 05-11-2013, 10:11
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AKA: James
FRC #2168 (The Aluminum Falcons)
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Re: Optical sensors getting tricked

Quote:
Originally Posted by Gdeaver View Post
We had a similar problem in 2012 with sharp IR sensors from Pololu electronics.
http://www.pololu.com/catalog/product/1134
The SHARP IR sensors can be GREAT if used in the right application, but here are my lessons learned.
  • The version linked above is affected by long wire runs and supply voltage fluctuations. You can remedy this by putting a capacitor 'backpack' on the sensor, across the supply voltage pins (VIN, GND). I think we used soemthing around 300uF electrolytic cap. This significantly reduced our intermittent detections due to supply voltage fluctuation.
  • There are quite a few different models of these sensors available, they are each tuned to work at different distances. Make sure you get the right sensor for the job. You need to know the minimum and maximum distances the object you are trying to detect will be from the sensor. This page has a good break down of ranges supported by different models.
  • The larger versions that are mounted within their own plastic housing MUST be mounted so that the plastic is isolated from the chassis. I know it sounds crazy, but the plastic shroud on these is conductive.
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