Estun Servo Tuning

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tblough
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Re: Estun Servo Tuning

Post by tblough »

<rant on>
Just a quick comment about encoder counts. You have a 8mm/rev ballscrew. Assuming your motors are connected to the ballscrew 1:1, then with an encoder set a 4194304 counts per rev, you have a theoretical resolution of 1.9 nanometers per encoder count. Even the best machine tools are going to be hard pressed to hold 1/5000 that accuracy (10 microns). If you had your encoder set to 8000 counts per rev, that would mean that each encoder count was 0.001mm - still 10 times your machine accuracy.

Approached from another direction, Centroid has stated previously that their encoder interfaces have a bandwidth around 2MHz. Assuming you run rapids around 10,000mm/min with a 8mm pitch screw, that's 1250rpm at the motor, or 21 revs per second. If you have your encoder set to 4194304 counts/rev then you need a bandwidth of 87MHz or 40 times more than Centroid provides.

Just because the encoder can generate an interpolated resolution of 4 million counts per rev, doesn't mean more is better. I don't know what kind of encoder is used in the EMJ motors, but my guess is it's magnetic with 100-1000 pole changes - physically less accuracy than a 2000 line glass encoder. The magic of software is making it seem amazingly accurate by subdividing those 1000 divisions into even smaller make-believe numbers.

Try this analogy. You just put a 10 foot diameter speedometer in your car and now you can read out your speed down to 0.001 MPH. Can you really adjust your foot on the accelerator such a minute amount to change your speed by 0.001 MPH? Could you do 0.01 MPH? I bet you'd be hard pressed to even do 0.1 MPH.

Overloading any system with extraneous data does not make it better.
<rant off>
Cheers,

Tom
Confidence is the feeling you have before you fully understand the situation.
I have CDO. It's like OCD, but the letters are where they should be.
MRW
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Re: Estun Servo Tuning

Post by MRW »

Pn200 = 16384 if I put this number in the counts/rev it faults out. Nothing is working as per our instructions Tech Bull or anything. I have paid for your support. please let me know when I can call you to team viewer this machine and get it set up. I cannot be wasting my time like this much longer.
MRW
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Re: Estun Servo Tuning

Post by MRW »

"Tblough" I understand what you are saying exactly. But any numbers less than 400000 the thing faults out. this is what I do not understand.
AcornJosh
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Re: Estun Servo Tuning

Post by AcornJosh »

MRW wrote: Wed Aug 14, 2019 12:48 pm Pn200 = 16384 if I put this number in the counts/rev it faults out. Nothing is working as per our instructions Tech Bull or anything. I have paid for your support. please let me know when I can call you to team viewer this machine and get it set up. I cannot be wasting my time like this much longer.
Counts/rev is 4 x Pn200 = 65536.
MRW
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Re: Estun Servo Tuning

Post by MRW »

Ok Ill try this again as well.
Just to be clear this gets input into the encoder counts per rev. in the motor config settings correct?
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Re: Estun Servo Tuning

Post by Centroid_Liviu »

MRW wrote: Wed Aug 14, 2019 12:48 pm Pn200 = 16384 if I put this number in the counts/rev it faults out. Nothing is working as per our instructions Tech Bull or anything. I have paid for your support. please let me know when I can call you to team viewer this machine and get it set up. I cannot be wasting my time like this much longer.
Please give us a call at 814-353-9290 Option 4 for Tech Support. We are open 8am to 5pm EST. A quick Teamviewer session can probably get your issues resolved.
When requesting support READ THIS POST first. https://www.viewtopic.php?f=60&t=1043

Please ALWAYS post a FRESH report. To make a report: https://www.youtube.com/watch?v=Ecvg0VJp1oQ.

(We pride ourselves on providing timely solid technical support but, without good information we may not be able to help and/or reply until such information is posted.)
AcornJosh
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Re: Estun Servo Tuning

Post by AcornJosh »

Issue resolved.
I will release a revised TB291 in the next few days explaining the setup with more detail.
MRW
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Re: Estun Servo Tuning

Post by MRW »

Thanks so much. Now I can hopefully get this thing making parts. :lol:
MRW
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Re: Estun Servo Tuning

Post by MRW »

Can someone tell me how a properly tunes drive looks like? For some reason I cannot seem to get mine to where the instructions say I should be at. I can get it running fairly good in low rpms. but as soon as i get up over 200 it faults out. I am not sure what is wrong, what I am doing right or wrong and where these scopes should really be since I cannot get anything to match even close to the Tech bulletin.

Report is attached.
Attachments
report_0320190764_2019-09-03_11-48-59.zip
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Last edited by MRW on Tue Sep 03, 2019 11:55 am, edited 2 times in total.
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Re: Estun Servo Tuning

Post by cnckeith »

maybe it is time for a teamviewer session with josh in support. email him to arrange.. support@centroidcnc.com
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
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