7i40hv pid

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04 Sep 2017 10:09 #98448 by billykid
billykid created the topic: 7i40hv pid
hello
i am going to use 2 drivers 7i40hv can you tell me what terms PID to use?
I've read jhon's example but talk about velocity mode, these are nude bridges I think.
as a starting point,% of P of ff1 ff2.
regards
Mauro
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04 Sep 2017 12:36 #98460 by andypugh
andypugh replied the topic: 7i40hv pid
I would start with just P at 0.00001 then make it 10x bigger until something happens.
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04 Sep 2017 17:09 #98499 by billykid
billykid replied the topic: 7i40hv pid
thanks Andy
the pid works already very well with only P = 160.
more than anything I was interested in knowing which tuning parameters and what not.
I'm testing with an unmanned engine I know is not a good condition
but g1 x10 f1000 stops + - 0.001 mm.
according to you is a good system with this closed loop or better how do I have drives that hold their position commanded step-dir?
regards
Mauro
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04 Sep 2017 20:14 #98504 by andypugh
andypugh replied the topic: 7i40hv pid
An PID will tend to stop at the right place. You should plot how well it follows dynamic movements using halscope.

You will probably find that some I-term is needed to remove steady-state error.
D-term might let you run more P, for a stiffer response.

But, until the servo is mounted to the machine and is under load there is no point taking the tuning too far.
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04 Sep 2017 20:45 #98508 by billykid
billykid replied the topic: 7i40hv pid
I have four homemade drives and work fine
elm-chan.org/works/smc/report_e.html
as I'm now making a small plasma and I wanted to use 7i40hv + 5i23
I was interested in knowing whether the results will be as good as other drivers
the next few days I will try to calibrate the pid on a real axis, but I'm quite satisfied
sorry but I can not explain well with the translator
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06 Sep 2017 12:38 #98575 by billykid
billykid replied the topic: 7i40hv pid
I did the tests work very well.
now i use a 1024 encoder but i think it's a little for a closed loop system.
I would have found this: HEDR-55L2-BY09 3600 cpr line driver. with 5i23 I should not have counting problems.
Usually what do you use as a resolution?
regards
Mauro
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06 Sep 2017 14:01 #98582 by andypugh
andypugh replied the topic: 7i40hv pid
1024 lines or 1024 counts?

Assuming a 5mm pitch screw and that f-error is 4 counts (typical) then the accuracy of the system will be +/- 0.02mm with a 1024 count encoder (0.005mm with a 1024 _line_ encoder).

What do you need?
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06 Sep 2017 17:18 - 06 Sep 2017 18:45 #98590 by billykid
billykid replied the topic: 7i40hv pid
in fact you are right.
I'm 1024 cpr, I wanted to change them for two reasons: when I get the 7i40 i would like to use differential encoders (my not) and index.
I thought I would use HEDR-55L2-BY09 3600 cpr which I can replace on the fly and have both features.
they will go 100khz maximum i do not think there are any problems.
I found the output-scale parameter at 10 from pnconf is right for this configuration?
thank you
Mauro
Last Edit: 06 Sep 2017 18:45 by billykid.
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