On Tuesday, May 08, 2012 04:42:52 PM andy pugh did opine: > On 8 May 2012 21:06, Dave <[email protected]> wrote: > > You have no Pgain, but Igain and Dgain. That's a problem. An all I > > and D loop is almost always unstable. > > That depends…. > > For a spindle P gain is not much help, as you need a non-zero PID > output even when at the set speed (and when the error is zero). That > is why the Wiki example is all-I.
The page I am looking at right now says D-I are both 1.0. Silly Q probably, but could the pid.0.command value also be sent to sum2.0.in0, and the pid.0.output sent to sum2.0.in1 to furnish the desired offset, allowing the pid module to work with a much more balanced (read closer to zero) output? To my simple mind, which ignores the latency of a 1 khz servo thread for all this, that does seem like it should be a workable scenario. Let sum2.0.output drive the pwmgen.0.value. In fact, I'll try that first just for S&G. Thanks Andy. I _think_ the lights are a bit brighter now. > I assume that FF0 wasn't available > when that page was written. > > I spent most of this afternoon at work tuning something that turned > out to work best with 99% of the control coming from the D-term and 1% > from I. But that was a rather unusual situation. Oh, can you share the hardware details? Thanks again Andy. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> If you keep anything long enough, you can throw it away. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
