2015-03-26 1:06 GMT-03:00 Jon Elson <el...@pico-systems.com>: > Do you mean to extract velocity from the encoder and then > feed it out a DAC channel to > a velocity servo amp? This is what almost all FANUC > controls do, and a few people are > doing this with LinuxCNC. I think Chris Radek is doing this > on his machine, and John Kasunich and Chris > Kelley at Tx/Rx Labs in Texas got this working on their > PowerHawk mill. >
Well, If I understand you correctly, yes we're talking about the same. Extract the encoder velocity, feed the DAC through a PID to close the velocity loop and also close the position loop to move that axis. What I'm using here is not a servo drive as you know but the purpose is the same. I'm thinking about using the approach on the link you sended to me from the wiki but instead of using two feedback devices, use just one. I'm going to try it out tomorrow to see what happens, anyway as I said before.. LinuxCNC is working great so far without closing the velocity loop. What I'm doing so far is, closing the position loop and the DACs are feeding the VFDs without really closing the velocity loop, LinuxCNC is only asking to VFDs for a velocity but without knowing if the motor is reaching the speed at the moment LinuxCNC expects them to reach it. I guess this is why closing the loop both ways makes it more accurate. Anyway I don't expect them to be as delicate as a permanent magnet servo but I think they can be improved. -- *Leonardo Marsaglia*. ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
