Deviation observed on 3+2 axis CNC milling setup.

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TomKerekes
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Re: Deviation observed on 3+2 axis CNC milling setup.

Post by TomKerekes » Tue Aug 02, 2022 6:44 pm

Hi Wilson,

That all sounds reasonable. But still quite aggressive on Velocity, Acceleration, and Jerk. 1e7 is over 1/2G acceleration. Most CNCs operate at about 10% of that. If you can't achieve your accuracy goals you may want to decrease those.
5. Reduced the P gain till the servo would freeze and then bumped it back up a tiny bit.
I'm not sure what you mean by freeze? Following error? Normally you want to increase P as much as possible to reduce error.

Ambitiously I bumped up the ‘Max Velocity’ to ‘700,000’ but the servo stalled so I increased the P gain in increments of 0.01 and then when it was stable I added an extra 20% to be sure. Ie. A value of 0.37 finally
Not sure what you mean by stalled? Following error? What is your following error and other settings?

It looks like your errors are quite large. Its hard to see from your plots. If you plot error or post the raw data so we can zoom in so we can see it. But I'm guessing maybe 5000 counts (0.1 inches) ?

The next step would be to try to reduce errors by increasing gains.

You will want to increase max integrator to about 4000 so it can provide the necessary output without any error.

To utilize D gain you might add a 2nd order Low pass filter of around Freq=1000Hz Q=1.4 to smooth the output.
Regards,

Tom Kerekes
Dynomotion, Inc.

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