Centroid CNC11 Servo Auto Tune

[bakeng]

I would like a more in-depth explanation of the CNC11 Servo Auto tune.
What is it looking for?
Does it have a max feedrate it will allow?
What determines max feed rate in the auto tune?
What parameters in the PID settings does it affect?
Whenever I run it on a machine it seems to have a "preset" feed rate for each axis.

I have the servo tuning tech sheet, but it does not explain the settings very well. Is there a more in-depth explanation of the PID parameters?

[bonestock]

I too would be interested in tuning AutoTune.
My servos are more capable then my machine and power will allow so autotune triggers over over voltage faults when it really kicks in.

Any ability to tune the max values it uses would be nice.

[bakeng]

Bonestock, if you are getting over voltage most likely the control software is acceling and/or deceling to fast. Try a slower accel and decel rate until you get the other parameters in your software tuned correctly. Then slowly decrease the accel and decel rates until you get it tuned. Be sure to retune the softwares PID loop every time you decrease the accel and decel rates. This is kind of a long process but until we get more info on the auto tune this is the only way I know how.
Do you have good motion from the servo drives tuning software? If not you have to start by tuning the drives real good before even attempting to tune from the control software. It has been my experience that most any control software will only be able to do around 80% the speed the drive alone will do.

[Centroid_Liviu]

Please check out Technical bulletin 44 and 45 (http://www.ajaxcnc.com/ajax-technical-bulletins/) for more information on tuning and auto-tuning parameters.

[bonestock]

bakeng and ajaxliviu, Thank you.

My servos and drives are 1KW Teco reproductions of Yaskawa Sigma II line. I have not performed any software tuning of the drives aside from applying the general Yaskawa settings used on other Centroid system. (lots of googling, and scouring of Tech Bulletins)

I have nice smooth motion due to extensive tuning in Mach. While certainly not tuned for max velocity and torque, things are operating very smoothly at about 60% of their potential. This was done intentionally until I could access the mill would not pull it's self apart with 250IPM rapids.

Sadly my PID settings in Mach are not quite as smooth in CNC11. I was hoping to use auto-tune to optimize these values, but the tests very quickly result in an overvoltage. Tweaking the max Ka and the autotune move distance parameters have not seemed to resolved the issue. When I left off params 95-98 were set to 0.5 and params 87-90 were set to a low "6". I did not start at these low settings but instead worked my way down to them running auto-tune and seeing over-voltage faults each time. It did not seem that max Ka was changing the auto-tuned acceleration like I thought it might.


Ajaxliviu,
http://www.centroidcnc.com/dealersuppor ... hp?TBID=44
Do you have a similiar Autotune PID baseline like TB44 for Yaskawa Sigma II drives in which I can compare my controller and drive settings.
I have a large kneemill (similiar size to Bridgeport Series II) with Teco 1KW servos on the X/Y and Teco 750W on the Quill.

[bakeng]

Bonestock, I'm at a loss to give you any more info until we get more info on how the cnc11 auto tune works. As with my orginal post it seems the auto tune is preset to a max feed rate. I'm guessing this was done to give a conservitive setting for auto tune. The tech papers do not explain how auto tune functions and what it's preset values are. Without this info the auto tune will not be much help in setting up a drive for maximum feed and position. Until we get some hard answers about auto tune I'm afraid we are on our own with tuning.

[cncsnw]

Autotune sets the max rate (rapid rate), acceleration time, and PID feedforward parameters (Kg, Kv1 and Ka).

It is premised on torque mode control. If you are running third-party drives in velocity mode, the Autotune facility will not give you useful results.

Autotune does not tune or adjust the PID feedback parameters (Kp, Ki and Kd). You need to hand-tune Kp, Ki and Kd as needed to obtain stable and reasonably-smooth operation before attempting to use Autotune to set rapid rates and feedforward gains.

[bakeng]

Thanks for the info. That definitely clears up a lot of crazy things I have seen in cnc11 PID tuning.

Bonestock, with the info provided by cncsnw, third party drives in velocity mode will not tune with cnc11 autotune. Basically with a third party drive auto tune is useless. It will only give you suggested accel and max IPM AFTER cnc11's PID is tuned.

[bonestock]

Ahh that would explain it. No short cuts to tuning I guess. Thank you all for the help.