DG4S Tuning

[dan13]

Hi,

Need help tuning these drives. I replaced the original drives on a machine, leaving the original motors. Originally the motion was smooth and quiet. With the new drives the motion is not not quiet. The tuning and response look OK, but when jogging the axes, they produce noise which doesn't seem normal. Only one axis (Z) works smooth, may be due to the huge load.

Also, the encoders are 2500ppr, but no matter how stiff I tune the drive, I can rotate the motor axis by a couple of degrees each direction (5 degrees total), without the motor even trying to compensate. The software shows +-40 counts error. In this margin of +-40 counts I can leave the motor anywhere and it won't return back to 0. This is not normal! This is the first time I am using these drives, so I don't know if this is something normal with these, never seen such behavior.

Can anyone from the support guys take over my PC and remotely try to help with this? I am feeling stuck, well, unless it's normal with these.

Thanks,
Dan

[cncdrive]

We do not do that, sorry.
We do not know what is in your shop, what the motor do, if it harms somebody etc. so we do not move motors online.

No, what you described is not normal.

If you can't deal with the issue then you can send the drives back to us for a refund.

[dan13]

I expect to get some sort of support for the product I bought. Sending them back for a refund doesn't solve the problem at this point - the project is past the deadline and a solution must be found.

Have had remote support with practically any drives I have used, including brands like Allen Bradley and Delta. But if your policy is different, then please suggest a way how this can be sorted out.

Thanks,
Dan

[cncdrive]

So, you don't get support here is what you saying? And what is your other thread is about?
My suggestion is to tune the PID loop harder, because if you have 40 encoder counts steady position error then it is still pretty soft.

[dan13]

Regarding the support, it was in response to your last message, where you suggested returning the product instead of offering support. The other thread is still not responded to, by the way.

Tried tuning the drives more stiffer, but don't see it affects any on the 40 counts and with stiffer system I am getting only more noise. Do you have some documentation about tuning using your software? The document I downloaded doesnt list the min/max values of the parameters and there is no correct tuning sequence specified there, I am just tuning as I am used to with other drives, but may be these require a different approach.

Thanks,
Dan

[cncdrive]

Yes, we are nice enough that we take back products if it does not meet your expectations or if you don't know how to use them.
We do not offer support which could possibly cause harm or death (moving something remotely which we have no control over locally), sorry.

PID tuning: https://en.wikipedia.org/wiki/PID_controller

I would try the Ziegler Nichols method.

[dan13]

Thanks, will try again.

I don't think I have to "know" how to use a new product I bought and which I am not familiar with, I expect to have sufficient documentation and support to be able to setup the system, that's all.

Would appreciate if you could respond to the other thread as well

Thanks,
Dan

[Dave Barbs]

Hi Dan13

I'm having the same issue with the drivers allowing the motor to turn 20 to 30 steps each way before feedback is provided.
Did you resolve this in your system?

Regards,
Dave

[dan13]

Hi Dave,

It's so old. To be honest I don't remember the details. I do remember that I had to live with the not perfectly tuned motors. Meaning, I couldn't get them to a point that would 100% satisfy me. Whether it was 40 or less counts, I am not able to tell at this point. I know that machine works to date. Sorry.

Dan

[cncdrive]

Servo control is based on feedback and therefor it is not possible that a servo motor system works with 0 position error all the time, because if the position error is 0 then there is nothing to control.
How much the servo error maximum is in the motions depends on several factors, these are the PID tuning (how hard or soft it is), the motor and load inertia, the load mass, the set acceleration for the axis etc.
If the position error is too high when the motor is accelerating or deccelerating then try to set the acceleration lower to see if it makes a difference.
If the position error is too high when the motor is running with constant speed (not in the acceleration phase and if the error is too high only on high velocities then try to lower the velocity or try to increase the power supply voltage.

Also you can try to change the integral gain and the proportional gain higher (P and I) to see if it makes any difference.