Closing the servo loop with HAL mesa 7i76

Todd wrote:

Try something more like 200mm/sec/sec. (You probably should use your servo drive's configuring software to increase the acceleration there or at least look up what it is set for, there is no reason to be guessing at these numbers.)

Todd I do have the manual but not skilled enough to understand it. The manual is actually quite good. but is to big to put on the forum
I could load it into Dropbox with a link to it

200mm/sec/sec seems quite slow it does not error at 1000 if I keep the speed down to about 8-10mtr/min

It does not error at the slow speed because the acceleration time is too short for the following error to grow large enough to trigger the alarm.

Todd wrote:

It does not error at the slow speed because the acceleration time is too short for the following error to grow large enough to trigger the alarm.

Can you explain what that means Todd? Are you saying the large servo cannot reach those speeds with that acceleration? Or something inside the drive needs to be changed?

I'm saying you have your drive configured to limit acceleration to a very slow rate, and you should look into adjusting those settings in your drive. But first you can confirm this by setting the limits in Linuxcnc to something within the limits your drive is currently configured to and see if your following error problems go away.

If the drive is limiting acceleration to something lower than what Linuxcnc is commanding. During the acceleration portion of the move the following error will increase at a linear rate for the entire acceleration time. The higher the commanded velocity is the longer the acceleration time will be and the larger the resulting following error. So a move at F10 would result in twice as much following error as a move at F5 because the acceleration time would be twice as long. Then once the acceleration part of the move is over the drive would start to catch up with where it should be and the following error decreases.

Ideally the maximum acceleration and velocity programed into the servo drive should be a little more than the limits programed into Linuxcnc. I think it might be ok if they matched the limits for the STEPGEN_MAXVEL and STEPGEN_MAXACCEL. However I don't know how to program those limits in your drives. You will need to study their manuals to figure that out. When setting them they will likely be programed either in motor RPM or RPS or encoder counts/sec. So you will have to calculate the conversion of that to mm/sec to compare with your settings in Linuxcnc.

Todd This is a big ask but would you have the time to have a look through my manual on the drive to point me in the right direction. I could put a link on it my google drive or dropbox.

I might look as I have time.

You could just post a link to where ever you downloaded the pdf. (or even post the model number of the drive. Google usually comes up with something.)

Todd wrote:

I might look as I have time.

You could just post a link to where ever you downloaded the pdf. (or even post the model number of the drive. Google usually comes up with something.)

Todd Thank you for your time.

The drive is a AASD-30A_V4 ... Servo motor 110SD_ m06030 These were purchased together.

I think this is the website www.cncservocontrol.com/servomotor/servomotor_20.html

But the full manual in English is here:-

www.dropbox.com/s/jp7t9hcszjcg6na/1.8Kw%...vo%20manual.pdf?dl=0

Todd I have found this on page 64 of the manual.


Would this have something to do with the problem?

Those pertain to tuning the position loop in the drive (something that may need done). But not directly to the velocity or acceleration limits.