Servo driver SG-AS20 YUHAI or CTB
- besriworld
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10 Jul 2023 21:11 - 10 Jul 2023 21:12 #275162
by besriworld
Servo driver SG-AS20 YUHAI or CTB was created by besriworld
Hello ,
I open a new topic for this brand.I needed to buy an 11kw servo motor and driver for my mill and decided to buy new motors for the lathe(diy project). (Because I don't have additional shipping costs). So the spindle and driver brand is CTB . but the small servo motors have no brand. The CTB company says it is their production.But I think this is the real manufacturer : www.xyuhai.com/
Where is the problem ?
I wasted 5 days trying to get this driver to work properly.And it still doesn't work as it should.
There is a 23-bit encoder and the driver has an encoder output. But this output has a delay. Any speed higher than 200mm/min (screw pitch 10mm) linuxCNC gives a following error .The driver does not have a maximum error parameter that works. The encoder output cannot be used. There is a lag which prevents setting the PID regulator. No PC connection/setup software. Has anyone worked with this driver?
Can linuxcnc use feedback but with delay filter on.
I open a new topic for this brand.I needed to buy an 11kw servo motor and driver for my mill and decided to buy new motors for the lathe(diy project). (Because I don't have additional shipping costs). So the spindle and driver brand is CTB . but the small servo motors have no brand. The CTB company says it is their production.But I think this is the real manufacturer : www.xyuhai.com/
Where is the problem ?
I wasted 5 days trying to get this driver to work properly.And it still doesn't work as it should.
There is a 23-bit encoder and the driver has an encoder output. But this output has a delay. Any speed higher than 200mm/min (screw pitch 10mm) linuxCNC gives a following error .The driver does not have a maximum error parameter that works. The encoder output cannot be used. There is a lag which prevents setting the PID regulator. No PC connection/setup software. Has anyone worked with this driver?
Can linuxcnc use feedback but with delay filter on.
Last edit: 10 Jul 2023 21:12 by besriworld.
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- tommylight
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10 Jul 2023 21:36 #275165
by tommylight
Replied by tommylight on topic Servo driver SG-AS20 YUHAI or CTB
Are you using it in "torque" or "velocity" or "position" mode?
Setting it to position mode and using step/dir to control it would at least show if the drive is roughly tuned with the motor to be usable.
And LinuxCNC can do closed loop even with step/dir/position mode drives, and should be easier to tune.
Setting it to position mode and using step/dir to control it would at least show if the drive is roughly tuned with the motor to be usable.
And LinuxCNC can do closed loop even with step/dir/position mode drives, and should be easier to tune.
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10 Jul 2023 21:57 #275169
by besriworld
Replied by besriworld on topic Servo driver SG-AS20 YUHAI or CTB
I apologize for the missing information.
The servo uses position mode , and step direction signal. The output of the encoder from the driver is connected to the mesa card. But this encoder output has a delay from the actual position. This makes closed-loop setup impossible . But if there is a delay option, linuxcnc can delay the follow. So we let the driver take care of the exact position and linuxcnc intervenes only if it makes a big mistake. For example, a missed step or an error in the program.
The servo uses position mode , and step direction signal. The output of the encoder from the driver is connected to the mesa card. But this encoder output has a delay from the actual position. This makes closed-loop setup impossible . But if there is a delay option, linuxcnc can delay the follow. So we let the driver take care of the exact position and linuxcnc intervenes only if it makes a big mistake. For example, a missed step or an error in the program.
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10 Jul 2023 22:11 #275171
by tommylight
Replied by tommylight on topic Servo driver SG-AS20 YUHAI or CTB
How much of a delay? Can you do a plot of joint.0.f-error using halscope?
You should set everything to open loop and test the drives alone, if this seems OK, then try to use the feedback in LinuxCNC.
LinuxCNC will not work with delay on feedback as that would be very dangerous for a lot of machines, and that same delay would absolutely destroy the ability to produce precision parts with any machine.
Might be possible to do something in case of to much error, but no idea how for now and i assume it would still not be very effective.
If you must have closed loop in LinuxCNC ( i absolutely insist on this whenever possible), you can add encoders or linear scales and use those to close the loop in LinuxCNC.
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On a personal note, i just ordered a cheap (340Euro) servo drive and motor, 750W one, with a normal incremental encoder, i explicitly looked for that, although being chinese i will probably get a 17 bit one.
Are you in Bulgaria? There is a shop there that has china stuff very cheap, i bumped into it by accident once and could never find it again. Ask around, they had a lot of CNC stuff and some descent drive/motor combos. This was a few years back.
You should set everything to open loop and test the drives alone, if this seems OK, then try to use the feedback in LinuxCNC.
LinuxCNC will not work with delay on feedback as that would be very dangerous for a lot of machines, and that same delay would absolutely destroy the ability to produce precision parts with any machine.
Might be possible to do something in case of to much error, but no idea how for now and i assume it would still not be very effective.
If you must have closed loop in LinuxCNC ( i absolutely insist on this whenever possible), you can add encoders or linear scales and use those to close the loop in LinuxCNC.
-
On a personal note, i just ordered a cheap (340Euro) servo drive and motor, 750W one, with a normal incremental encoder, i explicitly looked for that, although being chinese i will probably get a 17 bit one.
Are you in Bulgaria? There is a shop there that has china stuff very cheap, i bumped into it by accident once and could never find it again. Ask around, they had a lot of CNC stuff and some descent drive/motor combos. This was a few years back.
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11 Jul 2023 02:42 - 11 Jul 2023 02:48 #275182
by besriworld
Replied by besriworld on topic Servo driver SG-AS20 YUHAI or CTB
With very low follow error from the servo and linuxcnc set to P300 and d0.3 Minimum error setting 0.005mm. Linux works with the feedback but the servo motor is very noisy. Maybe I should put an extra encoder to measure the delay error?
I thought I was buying a better Chinese
Yes, I'm from Bulgaria . Maybe this site? www.vallder.com/bg/magazin (the english version doesn't seem to work) or www.exoror.com
I thought I was buying a better Chinese
Yes, I'm from Bulgaria . Maybe this site? www.vallder.com/bg/magazin (the english version doesn't seem to work) or www.exoror.com
Last edit: 11 Jul 2023 02:48 by besriworld.
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11 Jul 2023 07:11 #275193
by Aciera
Replied by Aciera on topic Servo driver SG-AS20 YUHAI or CTB
Delay of encoder output on servo controllers is found even in top of the line products. I have Mitsubishi drives for motors with absolute encoders and those also have a delay big enough to make it necessary to increase the following error in linuxcnc. It's not really a big issue since the drive already takes care of the positioning and monitors the following error on its own.
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11 Jul 2023 09:35 #275199
by besriworld
Replied by besriworld on topic Servo driver SG-AS20 YUHAI or CTB
So, if the servo driver works well (follows the set step pulses). I can set in linuxCNC a higher followed error. Like a value of Max Erro 0.5mm?
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11 Jul 2023 10:06 #275201
by tommylight
Replied by tommylight on topic Servo driver SG-AS20 YUHAI or CTB
Yes, it is Walder, thank you.
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There are two settings for each joint in LinuxCNC dealing with feed error
ferror = usually 10 in metric systems
min-ferror = usually 1 in metric systems
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There are two settings for each joint in LinuxCNC dealing with feed error
ferror = usually 10 in metric systems
min-ferror = usually 1 in metric systems
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11 Jul 2023 10:23 #275202
by Aciera
Replied by Aciera on topic Servo driver SG-AS20 YUHAI or CTB
Note, to use the 'home to index' feature with the mesa board you would want to use the custom firmware that allows resetting the step generator. This is the preferred solution.
With the regular firmware the index resets the encoder count and you will need to close the loop in linuxcnc with a pid in hal using a P value (50 in my config) so the homing process actually works.
With the regular firmware the index resets the encoder count and you will need to close the loop in linuxcnc with a pid in hal using a P value (50 in my config) so the homing process actually works.
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11 Jul 2023 10:38 #275203
by besriworld
Replied by besriworld on topic Servo driver SG-AS20 YUHAI or CTB
Yes, I have custom firmware but I also want linuxCNC to have feedback from the encoder. That is, I adjust by a large followed error and not aggressive PID regulator on linuxCNC.
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