Tom Easterday wrote: > Well, I feel like I need to put in a good word for these encoders when Jon > puts in a bad one :-) ... I used these encoders with success on a small EMCO > mill retrofit with stepper motors. I then used them on this machine > (http://wiki.linuxcnc.org/cgi-bin/wiki.pl?GantryPlasmaMachine) which uses > 1125 oz-in servo motors and has very high acceleration. We use Granite Device > servo drives on this machine and it runs absolutely great. I didn't > experience the problems which Jon refers to in tuning due to these encoders. > Also, you can improve the time constant on these encoders with a small > modification (#3 in this FAQ: http://www.cui.com/AMT_FAQ) if you find that > is an issue. > > By the way, Jon, did you try testing these with the modification? > I tried it, it didn't seem to make a very big difference. Also, the trouble I was complaining about was with a very low-inertia brushless motor with no machine connected to it. So, that is the worst case for unstable acceleration measurement. I was trying to get down to an equivalent of .0002" following error during all phases (accel, cruse and decel) and also get the motors to not rattle and grind at rest.
I was able to do this easily with the standard optical encoder, I couldn't do better than .0005" with the CUI, and got some grinding that I couldn't eliminate. This was with the encoder set to the highest resolution setting, I think the CUI does better at lower resolution settings. Anyway, I never tried the CUI on a real machine, it may do fine. Also, I tested it with LinuxCNC and my own encoder interface and servo drives, as you say, it may work fine with other servo systems. Jon ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
