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Unread 10-03-2014, 00:08
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Levansic Levansic is offline
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AKA: Len Evansic
FRC #0585 (Cyber Penguins)
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Location: Tehachapi, CA
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Re: Information on PID Control

That's unfortunate. We're using CAN and LabView and omni-wheels, but not with closed loop speed (yet). So far, we have not had problems, but we are using additional surrounding loops and filters on driver inputs and rotations to limit commanded speed changes.

In past years, we tried to start from the wheels up, and hit many frustrations. This year, we are starting from the top (driver) down, and doing better, although we have not closed the last loop at the jaguar to wheel.

We noticed in the past that the Jaguars cut out when they seem to predict that they will exceed a limit, under PID control. We decided to filter the driver input by limiting the maximum acceleration allowed, both linear and rotational. Further, we implemented a PID in LabView to compare a modeled rotation to our gyro reading, and use that to drive the holonomic.vi rotational input. So far, this is the best control we've ever had for mechanum or omni-wheel.

We would like to do the one last step of closing the loop at the wheel, now that we have more restrained inputs. That will have to wait until our bag gets opened later this week. In the end, we are good enough now, and have no issues with CAN Jaguars.
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