how to synchronize two servomotors
22 Jun 2017 20:21 #94805
by andypugh
Replied by andypugh on topic how to synchronize two servomotors
Oscillation is almost certainly tuning. Try lowering the P-gain until if stops doing it. (initially).
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28 Jun 2017 06:55 #95093
by Jasper 3
Replied by Jasper 3 on topic how to synchronize two servomotors
hey,
the last days I tried to tune the servos so they run smooth. I tried to connect the couplings between servo and Gantry after I homed my axis and switched everthing on. But nothing worked.
When I run the servos (when they are not connected with the gantry) they run both in the same direction and also they run both with the same speed. So there the driver settings are all correct. Also the Linux settings should be correct.
So It seems, that either the servos cannot run synchronous (maybe because my gantry is to rigid? )or I make something wrong.
Is there any possibility to set something in Linux to run the servos as sychronous as possible?
regards Jasper
The P value is the last one I tried and als the value that worked best.
the last days I tried to tune the servos so they run smooth. I tried to connect the couplings between servo and Gantry after I homed my axis and switched everthing on. But nothing worked.
When I run the servos (when they are not connected with the gantry) they run both in the same direction and also they run both with the same speed. So there the driver settings are all correct. Also the Linux settings should be correct.
So It seems, that either the servos cannot run synchronous (maybe because my gantry is to rigid? )or I make something wrong.
Is there any possibility to set something in Linux to run the servos as sychronous as possible?
regards Jasper
The P value is the last one I tried and als the value that worked best.
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29 Jun 2017 10:49 #95162
by andypugh
Replied by andypugh on topic how to synchronize two servomotors
Your Y motor PIDs seem to be running open-loop, you have an FF1 term but no P-gain. You need at least some P-term to close the loop.
If these are step-dir servos in position mode you could try configuring as a plain step/dir system without PID.
If these are step-dir servos in position mode you could try configuring as a plain step/dir system without PID.
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30 Jun 2017 10:00 #95203
by Jasper 3
Replied by Jasper 3 on topic how to synchronize two servomotors
hey,
I also tried higher P -values.
when I run the servomotors without an closed loop they turn off after a while. The Driver then says overcurrent. But I can run them without any withle or so.
In the halscope I also checkt the encoder -position of both servos. They were absolutely identical. The F-error were slightly different.
what i also noticed is, that when I quick change the dirction of the motors I get a following error 3.
One question I have is. How do I tune the servos? I cant connect them to my gantry while tuning, because of the issues. But tuning them without any load is also not ideal.
I also tried higher P -values.
when I run the servomotors without an closed loop they turn off after a while. The Driver then says overcurrent. But I can run them without any withle or so.
In the halscope I also checkt the encoder -position of both servos. They were absolutely identical. The F-error were slightly different.
what i also noticed is, that when I quick change the dirction of the motors I get a following error 3.
One question I have is. How do I tune the servos? I cant connect them to my gantry while tuning, because of the issues. But tuning them without any load is also not ideal.
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30 Jun 2017 15:41 #95222
by PCW
Replied by PCW on topic how to synchronize two servomotors
Did you fix the 0 P terms? (a 0 P term cannot work)
Did you use identical PID values for the two slaved axis?
Can you post your _current_ hal and ini files?
Did you use identical PID values for the two slaved axis?
Can you post your _current_ hal and ini files?
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30 Jun 2017 16:22 #95224
by Jasper 3
Replied by Jasper 3 on topic how to synchronize two servomotors
hey,
here are my actual ini an hal files.
here are my actual ini an hal files.
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02 Jul 2017 16:19 #95282
by andypugh
Replied by andypugh on topic how to synchronize two servomotors
How does the gantry behave with a P of one? How did you settle on that number?
I would suggest setting up the HAL so that the two motors share a set of PID terms from the INI file, just to make sure that the PID Gains stay identical for the two sides.
Or, there is the option (that I think I mentioned earlier) of running the drives in position mode.
I would suggest setting up the HAL so that the two motors share a set of PID terms from the INI file, just to make sure that the PID Gains stay identical for the two sides.
Or, there is the option (that I think I mentioned earlier) of running the drives in position mode.
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03 Jul 2017 09:33 #95295
by Jasper 3
Replied by Jasper 3 on topic how to synchronize two servomotors
hey,
my servomotors get there cmd's in step dir signals. I set my servodrive up, so he runs in position mode. But not sure if you mean that?
The P value 1 is also ok but the servo overshoots a lot. For the p values I used the halscope. But I didnt connect the gantry cause of the whistle.
my servomotors get there cmd's in step dir signals. I set my servodrive up, so he runs in position mode. But not sure if you mean that?
The P value 1 is also ok but the servo overshoots a lot. For the p values I used the halscope. But I didnt connect the gantry cause of the whistle.
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03 Jul 2017 10:02 #95296
by andypugh
I have never set up a system with step/dir servos in position mode and with a PID in LinuxCNC HAL, though I am aware that it is the preferred method.
However, I _think_ that with such a system the P-gain should always be 1000. (and I _think_ that the other gains should all be zero)
Can you try this and see what happens?
Replied by andypugh on topic how to synchronize two servomotors
my servomotors get there cmd's in step dir signals. I set my servodrive up, so he runs in position mode. But not sure if you mean that?
The P value 1 is also ok but the servo overshoots a lot. For the p values I used the halscope. But I didnt connect the gantry cause of the whistle.
I have never set up a system with step/dir servos in position mode and with a PID in LinuxCNC HAL, though I am aware that it is the preferred method.
However, I _think_ that with such a system the P-gain should always be 1000. (and I _think_ that the other gains should all be zero)
Can you try this and see what happens?
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03 Jul 2017 10:22 #95297
by Jasper 3
Replied by Jasper 3 on topic how to synchronize two servomotors
hey,
I tried it but i makes fast oscillating movements.
when I run my motors in openloop modus than it works great. But than I have no possibility to synchronize my servomotors. After a while than by driver turns off and said overcurrent (I think because both motors work against eachother).
I tried it but i makes fast oscillating movements.
when I run my motors in openloop modus than it works great. But than I have no possibility to synchronize my servomotors. After a while than by driver turns off and said overcurrent (I think because both motors work against eachother).
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