On Apr 2, 2009, at 9:16 AM, Kirk Wallace wrote: > On Wed, 2009-04-01 at 22:18 -0700, Dave Engvall wrote: > ... snip >> Indeed that ( + and - ) would be the intuitive way to do it but it >> doesn't work. >> >> I tried changing the sign on INPUT SCALE and the sign on >> OUTPUT_SCALE >> independently but that doesn't work either. Axis moves on command and >> then >> faults on following error. >> So I have more work to do. >> >> Dave > > I briefly looked over the Servo Dynamics ( www.servodynamics.com ) > 1525-BR manual > ( http://www.servodynamics.com/Manuals/1525br_manual.pdf ). They do > seem > to indicate that the + input is a single ended common, but don't > explain > why. It would be nice to see what chip or circuit they use for the > input. If you can take the cover off without voiding your warranty, > can > you get a close up picture of the input area on both sides of the > board? > Another thing that came to mind is that the enable input is pulled > high > or active by default, so it seems that if the enable signal fails, > most > likely the amp will be active. It looks like the position limit switch > inputs are the same way, they seem to fail with the amp active. > > The manual indicates the amp has inputs for torque and velocity > feedback, which may complicate things. The amp output to the motor > will > vary with, the input from EMC2, and the feedback to the amp from the > motor. I like to have EMC2 handle all of the feedback, but looks like > the torque mode feedback really is a current limit to protect the > motor, > so this should be the setup to use. > > What are you using as the analog output to the amp? > > Now that you have some motion working, if you set the FERROR and > MIN_FERROR, for the axis under test, to a large number, such as 1", > does > the encoder display in AXIS match the the commanded motion? In other > words, for a command for a .5" plus movement at a slow feed rate , > increase the displayed position by .5"? > --------- > Kirk > http://www.wallacecompany.com/machine_shop/ > Hi Kirk,
Yes, one can use torque mode as the crew did on the Mazak at Galesburg. However, tuning is much easier if one has an internal velocity loop and then has to tune only the position loop. Using a battery box and halscope I tuned the gain vs tach on the amp to get good response. The X is not geared right so is slow to respond, i.e like 200 ms to plateau on velocity. On the other hand the Y comes up in about 40 ms. I just finished tuning both axes and the Y is much better than the X. Both are pushing the resolution of the encoders tho. The FF1 values are quite high 8.5 for X and 15 for Y. Not exactly ideal but I'll take what works. Now that things are running I can relax a bit. Many thanks to all those that offered advise on my problem(s). Dave ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
