On Wed, 6 Apr 2016, Marshland Engineering wrote: > Date: Wed, 6 Apr 2016 20:53:54 +1200 > From: Marshland Engineering <marshl...@marshland.co.nz> > Reply-To: "Enhanced Machine Controller (EMC)" > <emc-users@lists.sourceforge.net> > To: emc-users@lists.sourceforge.net > Subject: [Emc-users] Servos and Drives PID Values > > I finally have my mill table moving under CNC control. > > I'm using a 70 volt supply with DCM D6 drives in Torque mode, Mesa 7i48 cards, > Linear scales for position and 1.2 kw DC brush motors (my guess on the power > as they are 90 volt motors but no current rating) > > The only way I can get any control over the travel is setting P = 0.5 which of > course makes the position accuracy poor. Any more P and I get sever > oscillation. With the size of motor and the 1m table, there is quite a lot of > inertia in the system. > > Anyone suggest starting values or any other suggestions to get this under > control.
This is expected, the mathmatical solution to a double integral loop (what you have with just P controlling a torque mode drive) is a sine wave For a single loop torque mode PID control (what you currently have) I would set a small amount of P (say your 0.5) and then add as much D term as you can without getting oscillations. After this is done you should be able to increase P somewhat. In this case the more D you can get, the more P you can use. You will be able to get a higher stable D amount if you increase the servo thread rate (to say 2 or 4 KHz = 500000 or 250000 ns period) > > Thanks Wallace. > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
