I typed this up last night but realized I forgot to send it: Thanks to all for the feedback so far. I'll try to answer all the questions in one thread:
Peter: The servos are not getting enabled too soon, in fact they are getting enabled later than is typical due to an extra servo reset signal that emulates previous Anilam behavior and sets up a hardware-level relay latch that allows estop and limit switches to disable the servos in hardware. However, I have not tuned PID at all (I currently have the pncconf defaults), so that is likely my problem. I was using the pncconf wizard, so it was open loop. Grounding the servo input is a great idea as a diagnostic. If I make ferror larger it will eventually hit even that limit and go to a machine off state. I do believe I have the servo amp ground and shield both grounded. I'll measure cable power to see if I should switch it. Karl: It is possible there is some offset, but trying to tune that out with pncconf (DAC offset I believe) showed that it was not a fixed value. Since this system is fine with the Anilam controls, I am thinking it is probably ok, but I'll try shorting the servo amp inputs (in a safe way of course), to see if the drives move. I definitely don't have a reasonable Igain as I am currently at pncconf defaults, so that needs to be tested. The drives are physically moving and the chance for encoder noise should be low, but that can be tested as well. Interesting thoughts on applying a load, I'll try that if the PID tuning does not work. Chris: Thanks, I will definitely add a link once the docs are finished. You are correct that I don't have the encoders scaled properly, and that needs to be done. I'm looking to get that done soon, and will use your suggested technique to determine the encoder count. Mark: Thanks, pictures are definitely coming to the wiki page. Agreed about this group being great. John: Thanks, I'm hoping the documentation will turn out to be useful. We got the mill second or third hand, so we don't have the conversion information. Do you know if you can see the tuning parameters in the Anilam control software? Even with the following error at 1 inch it eventually hits following error. This Anliam mill has the velocity feedback going directly to the servo amps, both for EMC2 and Anilam control (I did not change that wiring). I have rotary encoders only. Thanks to all for the solid advice! Looking forward to taking this conversion forward! My current plan is to first try PID tuning for real, and see what kind of effect that has. Scott On Wed, Aug 17, 2011 at 7:55 AM, John Thornton <[email protected]> wrote: > The 1100M came both ways with glass scales (earlier model) then with > encoder feedback. Mine is the encoder variety of 1100M. > > John > > On 8/17/2011 7:28 AM, andy pugh wrote: > > On 17 August 2011 04:15, Scott Hasse<[email protected]> wrote: > > > >> To the point, though, I am having one not-so-minor problem. When I > enable > >> the servos, they are not completely stable, and I'll get following error > >> almost immediately after enabling them. They don't run away, but the > >> encoders show them moving ever so slightly, and physically the motors > >> actually are moving. > > Are you retaining the velocity feedback to the amps, so that they run > > an internal velocity loop, and then you use velocity commands to close > > your position loop based on the encoders? > > > > The previous Anilam system I chatted to someone about had velocity > > tachs on the motors and linear scales, no rotary encoders. > > > > So, in Anilam control is the feedback from linear scales, and encoders > > in EMC2 mode? > > > > > ------------------------------------------------------------------------------ > Get a FREE DOWNLOAD! and learn more about uberSVN rich system, > user administration capabilities and model configuration. Take > the hassle out of deploying and managing Subversion and the > tools developers use with it. http://p.sf.net/sfu/wandisco-d2d-2 > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Get a FREE DOWNLOAD! and learn more about uberSVN rich system, user administration capabilities and model configuration. Take the hassle out of deploying and managing Subversion and the tools developers use with it. http://p.sf.net/sfu/wandisco-d2d-2 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
