Kirk Wallace wrote: > I need help with tuning my brushed servo setup using HALScope. I have > done a search on linuxcnc.org but only found this: > > "First, you need to fire up Halscope. Start EMC2 from a command window > like this : node:/home/user/emc2$ scripts/emc & The "&" gets you your > command prompt back while EMC runs in the "background". Now, start > halscope like this : node:/home/user/emc2$ bin/halscope & You can pull > the corner of the scope window to make it bigger. Select the boxed "1" > on the lower left corner, and it will show a list of signals to look at. > The one you want is ppmc.0.pid.error." > > This gets me started, but any other information and links would be > helpful. Such as, what to use for the trigger and I thought the signals > for commanded position and position feedback would be the ones to look > at Some of this is outdated, if you have a recent EMC2. You can start Halscope from the pulldown menus on either TKEMC or Axis.
I trigger the scope from ppmc.0.encoder.00.delta, which is instantaneous velocity derived from the encoder. Commanded pos and actual pos are good for the grossest error, but quickly you converge to where these two lines fall on top of each other. What really matters is the DIFFERENCE between them, ie. the following error. So, ppmc.0.pid.error is very obsolete, what it is called now, is -- I think -- pid.0.error (for the X axis). Since this is just the difference between commanded and actual, it should always be a small number. I finsih tuning with this on the 200 u scale, that's 200 micro-inches/division. Depending on your encoder resolution, you may not be able to get down quite that far. You've obviously read my now outdated wiki page on tuning, most of the rest of the info there is valid, just the graphs look different. I need to do a set of new graphs with Halscope and revise that page. Jon ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
