Servo Wiring and Tuning detailed How To example Mesa 7i77.

viesturs.lacis wrote:

tommylight wrote: Vhat VFD? Any schematics ?

I meant that Commander VFD in Biesse machines. Nevermind, I managed to find the manual: www.acontrol.com.pl/uploads/pdf/instrukc...er-CD-user-guide.pdf

There is a schematic wiring diagram on the cover of the green commander. There is also a pot interface. Use that, real easy for spindle output.

I cant help with the 7i48. Never even seen one. With a 7i77 I tuned my CACR drives/motors in an hour 3 years ago and never been back in the control. I would suspect your pwm stuff before the analog out to be the issue. I don't know, never used that card.

tommylight wrote: Check the hal file and make sure the right encoder is using the right PWM.
When it jumps, does it trigger a disable ?

Yes, it disables the drives. Well, X and Z axes are fine, so there is only one pwmgen left and encoder works fine. Ok, I will check for 14th time tomorrow.

bevins wrote: I would suspect your pwm stuff before the analog out to be the issue. I don't know, never used that card.

I have used them previously, they are great. I will return there tomorrow and probably will paste my config files somewhere, because I completely agree that it is something about config before pwmgen. Because it works great, if I manually set pwmgen-value.

So I have managed to get the axes almost tuned.
I am happy with X axis (see attached picture with HalScope screenshot). Basically I have get max spike of following error 0,02 mm at jog speed 45 m/min. Just like I am happy about Z axis - following error of 0,01 mm at 6,4 m/min. And that is only with P and FF1 parameter, like Tomy suggested.

What I do not understand, is WTF is wrong with Y axis. My main issue are the spikes at the beginning and end of movements. I tried to tune this the same way I did all the rest - set the P parameter and then worked on FF1 gradually increasing the jog speed. Up to 36 m/min.
I made it to the point in which it seems to me that FF1 is good enough that movement does not lag behind nor rushes forward command - see screenshot of y_axis_36m-min. All that is left are those spikes. I have tried to remove them with FF2, but this is the best I can do - if I increase this parameter, the graph changes so that there is an increase of 0,2 mm for whole accel or decel phase.
And one more thing that puzzles me is that I dropped the velocity to 9 m/min and now the graph looks like FF1 is too much, because it runs ahead of commanded position.
I tried addding I term. Only thing it does is makes the whole graph go up or down, it does not help with the spikes. I tried also D term. It started vibrating at 0.006, so I tested it with 0.004, but the spikes are exactly the same.
I would appreciate any ideas, what is wrong with my approach.

Can you describe the mechanics of the Y-axis? Is the feedback encoder mounted directly to the Y motor or is it mounted to a ball-screw or is it a linear feedback device?

Tuning FF2 can be very touchy. Your plot shows you were using an FF2=0.000002. What happens with FF2=0.000003 or 0.0000025

Todd Zuercher wrote: Can you describe the mechanics of the Y-axis? Is the feedback encoder mounted directly to the Y motor or is it mounted to a ball-screw or is it a linear feedback device?

Encoder on motor shaft, motor coupled to ballscrew with belt

Todd Zuercher wrote: Tuning FF2 can be very touchy. Your plot shows you were using an FF2=0.000002. What happens with FF2=0.000003 or 0.0000025

So you mean that my approach was correct and that the FF2 value is not good enough?