Thread: What happens when an encoder goes out?
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Unread 11-02-2011, 02:04
jhersh jhersh is offline
National Instruments
AKA: Joe Hershberger
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Re: What happens when an encoder goes out?
Quote:
Originally Posted by Inconceivable View Post
Hello! I'm am using a CAN based (speed mode) control this year for a mechanum drive equipped with the us digital E4P encoders that come in the KOP (with 360 encoder wheels), and a mentor brought up a very good question. What happens if an encoder stops working or malfunctions? My gut feeling is that with all the safety checks implemented in the CAN Libraries (Labview), The Jag would figure out that it's not getting a valid signal from the encoder and simply shut down, but is there the possibility that it would just go full speed ahead in attempt to get to the set RPM (because it's reading 0 RPM)? If a Jag can detect whether or not an encoder is out, and one does, I intend to have all of the drive-motor jags switch to voltage mode so you aren't stuck with a dead wheel, or robot, depending on how it reacts... Does anyone know?
The Jag can't tell if an encoder is out because the signal from a dead encoder is perfectly valid and could be telling the real state of a good encoder. I believe it would behave as your second guess... it would go full speed ahead. If you choose to monitor the speed by reading the feedback over CAN, then you could write code to attempt to detect the issue and switch modes.

-Joe
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