View Full Version : Pid

01-03-2004, 07:32 PM
Sorry to be hogging so much bandwidth, one more question for the gurus out there...

PID parameters for me right now are a flat-out mystery. I am using Logosol digital servo drivers, 3 axis, for my bench metal mill. As part of the entire DIY process, I am trying to wring the utmost performance from the machine, with an emphasis on speed and accuracy. The Logosol drivers come with a utility to set the PID values and write them to the driver's EEPROM. I can follow the typical PID "recipe" and get a set of parameters which work, but ultimately I'd like to know that what I have delivers the best accuracy + speed, not just something that "works".

Sometimes during the tuning, the motor(s) go beserk and vibrate so badly that I'm afraid things will fall apart, or worse begin to run away.

Does anyone have a resource on the web that is a favorite which explains this a bit, or can perhaps offer some pointers to a new guy? Thanks again.

01-04-2004, 02:22 PM
Hi Swede,

Check out www.galilmc.com

Loads of info there. Also, they have some servo tuning software, which I have attempted to use. At least it graphs the servo response to real time sampling, to allow you to see how your settings work. Most likely their software only works in combination with their own motion control cards, but I wouldn't swear on that.

I have tried the automatic tuning routines. However, in the end, I have always ended up tweaking the PID values myself. Once you find the right ballpark for the values, it is easier to tweak, so at least the auto-tune helps get you there.