Prototrak Plus Retrofit with Mesa 7i77 & 5i25 cards

Thank you, Andy!!

I have turned each of the variables (paid special attention to the P,I,D,Deadband,FF2,FF1), in that order, more so the 1st of the 3 (P,I,D) until there was noise (admittedly low noise that would settle down, quickly, some appeared to come and go, when I would revisit a prior setting that was known) but what you see is what I could tune "pid.n.error" to around "x axes" f(.095)=.0272 (ddt -.054) and "y axes"f(.085)=.0258 (ddt -.0182), see below:


I know this is not what is required, I will try some more tuning. If the plus side of the duel loop is to limit the velocity, I can see how wonderful that would be. If there is any thinking about the tuning of AMC amps I could review that if necessary, like say more amps would help. Your comments and suggestions are warmly welcomed.

Many, many thanks!!

That does not look to me like the plot of a torque mode servo. I think your drives may be using some voltage feedback from the motor to fake velocity control. That is a good thing though.
It does look like you need to do some tuning on the drive itself. See how, even with a very high pid.N.output the acceleration is constant and linear, but way less than the commanded acceleration. You either need to adjust the tuning of the drive (this is in the drive not in Linuxcnc) so that it can accelerate the motors at least as fast (preferably a little faster) than you are commanding them in Linuxcnc. These adjustemets will likely be with trim pots on the drive or with a software program provided by the drive manufacturer. If you can't improve the drives performance, then reduce your max acceleration for the joint in Linuxcnc to something less than the drive is capable of.

Which drives did you end up getting?

Andy, what can I say? I have read so many threads.
Todd, I am very thankful for you taking time to help!! Thank you!
the amps are AMC Advanced Motion Control, Brush Type, this is link to pic; forum.linuxcnc.org/media/kunena/attachments/21712/IMG_1001.JPG

www.a-m-c.com/wp-content/uploads/support...ual_Analog_Panel.pdf

this is a manual for setup.

thanks!!

As I recall he got drives that only accept tach, (+=10volt), feed backs. But his motors are fitted with quad encoders. I'm pretty sure about it, but...

ADDED: So the amps may not be set properly to torque mode????

Best, Dan.

new2linux wrote:

Andy, what can I say? I have read so many threads.
Todd, I am very thankful for you taking time to help!! Thank you!
the amps are AMC Advanced Motion Control, Brush Type, this is link to pic; forum.linuxcnc.org/media/kunena/attachments/21712/IMG_1001.JPG

www.a-m-c.com/wp-content/uploads/support...ual_Analog_Panel.pdf

this is a manual for setup.

thanks!!

Unfortunately that picture doesn't show the model# of the amp (They made lots of different ones), and that manual is kind of generic, covering lots of different models.

According to that manual you need the "specific drive data sheet" to know how to configure the switches on the drive to properly set the drive's mode and tune it. If you don't have that it can easily be looked up from on line with the drive's model number.

I suspect the drive is in "Duty Cycle (Open Loop) Mode" described on pg.14 of that manual (other drives might call this voltage mode). It is best described as somewhere in between torque and velocity mode. and should be a lot simpler to tune than true torque mode.

Tuning this drive in voltage mode should be mostly the same as tuning a Pico systems amp here is a very good tutorial.
wiki.linuxcnc.org/cgi-bin/wiki.pl?PWM_Servo_Amplifiers

If I'm guessing your amp model# right this should be the data sheet.
www.researchconcepts.com/Files/20a14.pdf

Many, many thanks for the input, I will be working in the suggestions offered!

Just as a side note I was unable to access the forum yesterday "all day" it just would request "reload" to go no where. I have reviewed the manuals for setup and tuning.

To keep all the information in one place this is a pdf from earlier thread. servosystems.com/pdf/amc/12a8.pdf This is not in order if you follow the sheet numbers. The amp is a 12A8E Advanced Motion Control, brush type.

many thanks!

Edit: Setup for "current mode" DIP switch are 1,2 & 4 = off; 3=on;

I would suggest setting the drive for voltage mode. It should behave mostly the same as velocity mode.