Tuning Servos

Hello, I'm currently in the middle of doing a retrofit on a Hurco KMB-1. I have reached the point of being able to run gcode. I'm having trouble getting the servos tuned correctly so that my drives don't alarm out with a "Max.error" alarm.

I have spent around 10 hrs so far researching how to tune servos as this is my first servo system. I have the tuning doc from cnc4pc as well as some others, but none of them are really that clear on what I actually need to do. With statements like "after you arrive at a reasonable value for Kp, then move on to Kd." they assume that you already know what a reasonable value is. Or at least you know that when you plotted graph looks like this you need to change that, which at this point I have not been able to figure out.

Here are the specs of my system.

Motors: Electrocraft 0703-02-089 Brushed DC servos. 45V, Max cont. current 9.6A, max peak current 45A. (motors from machine)

Power supply: 88VDC (stock supply from machine)

Drives: Dugong DG2S-16035 (cncdrive.com)

Encoders: US Digital E6 500CPR (set at 4x on my drives for 2,000counts/rev)

Ball screws are .2"/rev or 5 turn per inch.

Mach3 is control software

Kflop is hardware controller

Here is a picture of what I think is the best tuning I have been able to get. Problem with it is if I I try and continues jog feed the x-axis my drive will alarm out, "Max.error". If I only jog about 1 inch at a time then I can jog all day long. This is with my motor tuning in Mach3 set for 100IPM.

It also seems that having an max error of 2000 is really high. With my ball screws and my encoders I have 10,000 counts/inch so I could be .2" off of location if my understanding is correct.

I have also include a zip file with 30+ screens shots of my tuning. Starting from 0 and trying to get the optimal graph according to the docs I have read on line.

Just looking for a little guidance on how to get these things tuned.

Thanks
-Wes

Hi Wes,

I assume you are just using our KFLOP as a Step/Dir generator and the servo is all inside the Dugong drive?

Are you connecting the encoder back to KFLOP so we can plot what is going on?

Regards
TK

Thanks for the reply Tom. I posted this in the wrong forum. Had too many tabs open :confused: I meant to post in the servo forum, and I see that some one moved it there but it is also showing up here. Not sure what is up with that.

Any it is not a problem with the Kflop/kanalog that is working just fine. It's on the Dugong side or I should say its me, being this is my first servo system. Still trying to get everything all figured out.

Problem figured out. I have a bad servo motor.