Gene, You have no Pgain, but Igain and Dgain. That's a problem. An all I and D loop is almost always unstable.
Chances are you are going to want Pgain and a little Igain and little Dgain(maybe.. if at all). Start out by trying some Pgain and no Igain or Dgain and see what happens.. Bump up the Pgain until something starts to work and then dribble in some Igain... I'd start with .05 Pgain and zero everything else and bump that up until things begin to work.. Then start at Igain of .001 and bump that up until you start to see some I action.. "I action" is a lot different than "P action" as it slides in over time. Then start Dgain at .001 and increase that and see what effect it has (it may not be desireable). Dave On 5/8/2012 3:45 PM, gene heskett wrote: > I currently have the commanded spindle velocity, NDI if it is supposed to > be rpms or what, essentially being fed thru the abs function directly into > the pid.0.command input. > > I am sending the encoder.0.velocity thru the abs function also then into > pid.0.feedback. This voltage on the hal meter is noisy but visually > averages someplace in the 3 to 5 range, which I believe is about 2x the > real speed it is turning in rps, and is not majorly modifiable by the plus > and minus buttons on the gui, which issue 1 to 1101 numbers in 100 > increments and that i what I see with the halmeter at the pid.0.command > input. The whole range of numbers presented to pid.0.command in can modify > the spindle speed by perhaps 20%. Running like this, the spindle speed is > extremely stiff, responding to an increased load in a small fraction of a > second. > > If and when I wire up a reverse, it will be done with a dpdt relay > controlled the .rev command from motion module. > > But 2 things, one being that in the halscope, the pid.0.output is > oscillating rail to rail, according to the scope at several hundred volts > peak to peak, and of course the pwmgen is outputting little trains of > pulses at the oscillation speed which is something in 100 hz range. > > I am getting the impression that the gain of the pid.0.feedback pin is many > decades higher than the gain of the command pin. > > Presently from the hal file: > > setp pid.0.Pgain 0 > setp pid.0.Igain 1 > setp pid.0.Dgain 1 > setp pid.0.maxoutput 401 # to keep it from running away > > Those values are straight from the Closed_Loop_Spindle_Speed page of the > wiki, and obviously I don't know enough about PID controls to make > intelligent adjustments. > > I sure could use some help in taming this beast. > > Thanks everybody. > > Cheers, Gene > ------------------------------------------------------------------------------ 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
