Oscillations after rotating

Coding Python programming
1

I’ve been working on putting together a program that draws out a logo and I’m running into some interesting things. More specifically, I’m having issues where the XRP will randomly oscillate after completing a turn for 10 or so seconds before continuing on. It doesn’t happen at the same time every time I run the same code. Any ideas what would be causing this? I’m guessing it has to do with the PID settings, so i may start tweaking that a bit first, but I’d appreciate any other ideas you may have.

ezgif.com-optimize (2)

1 Like
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Sorry, I can’t help answer your question. But I really appreciate how your video shows how the marker fits in the holder and is free to move and rotate as the XRP moves! Thanks for sharing.

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I’ve also seen this behavior sometimes, seems like the PID controller isn’t finishing when it should. I wonder if reducing the PID controller’s min_output would help?

0.35 seem high to me, I think something closer to 0.2 might do better. @TFossDK want to give that a try?

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So far that has seemed to fix the issue. If it pops up again i’ll reach out. Thanks @SparkFro

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Sure thing!

@k.siegall how would you feel about officially incorporating this change in XRPLib?

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Yea I can change that in the library - particular tuning values are always a little tedious but you’re definitely right that 0.35 as a minimum is a little large

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I’m seeing the same jittery problem today. I just reloaded the python dev environment
(switching back from the WPI/Java environment using this method) and the section of differential_drive quoted above looks like:

        if main_controller is None:
            main_controller = PID(
                kp = 0.1,
                ki = 0.04,
                kd = 0.04,
                min_output = 0.3,
                max_output = max_effort,
                max_integral = 10,
                tolerance = 0.25,
                tolerance_count = 3,
            )

And that’s completely different from what’s in the file linked above.
Did I end up with the wrong version of the library?

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Those values are for the main_controller for the Straight function, not the Turn function. They look almost identical.