Quote:
Originally Posted by Inconceivable
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?
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Spencer,
Yes, it goes full speed. We had this happen two days ago. That really helped drive home the safety issues to several of our students. No one got hurt even slightly, but it was scary.
We are looking to do something like Joe suggested by adding some code to look for this state. We also have the encoder signals on the drive train routed to the cRio to get distance, so we will likely put the safety code in that part of the loop. The good news is that it did stop when we disabled it.
I like your idea to have it switch to voltage mode if that happens. That might be a bit tricky to do, but it seems feasible.
-Hugh