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Author Topic: Tuning dspMC with Axis Works.  (Read 10478 times)

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Tuning dspMC with Axis Works.
« on: December 23, 2008, 10:14:51 AM »
Im running a 2 axis plasma with dual servos and the dspMC motion controller.

I've tuned the servo drives and im trying to get motion via the motion controller but they dont give much information on setting up your drives with the axis works in the install manual.

When I arm the PID, the motor moves 3000 steps and stops and it seams to be regardless of what i have setup to jog in the axis works. I put in the suggested PID values with no luck. Anyone had any experience with this controller, how did you set up your PID values?

And how is the "execute command" function supposed to work. It seams like this button does nothing. I'll press "arm PID" once and nothing happens, and if i press it again, i get movement. Then the third time the light beside "arm PID" go green and nothing happens. It seems like the "execute command" button has no function.

« Last Edit: December 23, 2008, 10:17:26 AM by halkintool »
Re: Tuning dspMC with Axis Works.
« Reply #1 on: December 23, 2008, 11:06:29 AM »
can you post your settings for the axis control?  send me your dspmc.xml file and I will take a look at it.  have you updated to the latest version available on the web?
Re: Tuning dspMC with Axis Works.
« Reply #2 on: December 23, 2008, 11:25:27 AM »
I downloaded the version listed at the sale point on the vital website, i would assume its the latest version.

What kind of settings are you looking for?
Re: Tuning dspMC with Axis Works.
« Reply #3 on: December 23, 2008, 12:35:29 PM »
I suggest you first go thru the manual thoroughly, and then send me your specific question.  the latest manual was updated on the web site few days ago.
Re: Tuning dspMC with Axis Works.
« Reply #4 on: December 23, 2008, 12:46:35 PM »
I've read through the manual about 4 times now. The new manual does not contain any new information in the PID tuning section.

There is no real process for determining PID values. Im not sure why a scale factor is required either, seems to confuse the process needlessly.  I could try numbers all day long and not get anywhere, the baldor drives for example have an auto tune function which determine PI values with relative accuracy.
Re: Tuning dspMC with Axis Works.
« Reply #5 on: December 23, 2008, 12:57:16 PM »
pls see page 24:

"Scale is used as a divider for all the setting in the PID gain box. This makes it possible for the software to use smaller manageable numbers and still get the same effect.  An example is if you put a gain of 4000 and a scale of 100, it is the same as a scale of 1 and a gain of 400,000."

making the axis move is not just matter of PID values.  Control configuration is also required to be correct.  eg motion source, DAC number, encoder, amp enable pin, etc.  you can change PID values all day long, but if you have not set the DAC number correct for your axis, you will never see any motion.  so the first thing is to make sure your control configuration is correct.  when you run axisWorks and connect to an axis, you will see the current configuration on the bottom right side of the main window in Setup.Axis.? box.  If you see undefined printed there, then you first need to download the proper configuration file to dspmc.

Pls send your dspmc.xml file to the sales address listed on our website so we can see all the settings. 

« Last Edit: December 23, 2008, 03:57:46 PM by vitalsystem »
Re: Tuning dspMC with Axis Works.
« Reply #6 on: December 23, 2008, 01:20:26 PM »
Heres a screenshot. Theres no mention of "input index" in the manual, but i assume is just for naming an axis.

24576 is the encoder counts per inch etc, axis is capable of 2600 ipm motion.
« Last Edit: December 23, 2008, 01:22:07 PM by halkintool »
Re: Tuning dspMC with Axis Works.
« Reply #7 on: December 23, 2008, 01:33:08 PM »
I can see the problem now.  Your input index is 0 for axis 1.  this is not correct.  Input index must be same as the axis number.  only for slave axis it is different.

page 41:
A.7 ControlInput Index
Defines the index of the PID input source. Normally this is equal to the axis number. For slave application, this
defines the data index of the master.
Re: Tuning dspMC with Axis Works.
« Reply #8 on: December 23, 2008, 02:00:01 PM »
I had it at 1 before, but when i changed the config last i put it back to zero.

Im still having the same problem as before. When i try to arm the PID with the suggested PID numbers, the axis jumps a few thousand counts and stops before i've even input a motion, then i get the ERR led on the motion controller itself. I tried running P: 1 D:25 with no scale factor and the PID arms without the bump but when i try to run motion, it start accellerating slowly then the PID disarms. The "follow error" indicator is very hard to use because if you are infact having a follow error, it seems like everything shuts down and its difficult to conclude that it was infact a follow error. The software seems to lack the feedback needed to tune.
Re: Tuning dspMC with Axis Works.
« Reply #9 on: December 23, 2008, 05:22:11 PM »
I had it at 1 before, but when i changed the config last i put it back to zero.

Im still having the same problem as before. When i try to arm the PID with the suggested PID numbers, the axis jumps a few thousand counts and stops before i've even input a motion, then i get the ERR led on the motion controller itself. I tried running P: 1 D:25 with no scale factor and the PID arms without the bump but when i try to run motion, it start accellerating slowly then the PID disarms. The "follow error" indicator is very hard to use because if you are infact having a follow error, it seems like everything shuts down and its difficult to conclude that it was infact a follow error. The software seems to lack the feedback needed to tune.

I have a funtionong sytem using the dspmc box, maybe I can help you get it set up. Once you get the hang of it the axis works is a great way to set the pid and to fine tune your drives.

I will try to answer your questions so far.


1.When you arm the pid and the axis goes 3000 steps and then faults out sounds like your encoder is wired backwards into the dspmc, or the motor polarity is wrong. When the pid is armed, the motor should lock into the current position, or possibly bounce between encoder counts, generating a hum or growl.

2. Arming pid. If you arm the pid and the actual vs commanded encoder counts are off by more than the following error, it will fault, which then resets the actual to the commanded, so when you arm the pid again, it turns on.

3.You will have to get the pid to arm and be stable before the execute will function.

4. Yes, the scale function keeps the number of zero's to something resonable as some people have trouble gett a number with 8 or 9 zero's typed correctly.

I have a couple of questions for you.

1.What are the make and model of the servo amps?

2.Do the encoders feed back into just the dspmc or do they go into the servo amp as well?

3.What are the encoder counts?

4.Are the encoders differential or single ended with converter board?

 5.Did you use the enable circuit?


 When it is up and running, I would love to see a video of it going 2600ipm


If you have any other questions, just let me know.


Mike

We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.