This is a quote from peter on the forum.. 'I have done some experimentation and have found that you can get better stepgen following performance on systems with moderate jitter by using a PID loop for position control instead of the stepgen drivers built-in position control loop. The problem with the built in driver position control is that its tends to overcorrect for measured position errors cause by sampling jitter.'
On Thu, Oct 28, 2021 at 12:35 PM Gene Heskett <[email protected]> wrote: > On Thursday 28 October 2021 11:45:49 Sam Sokolik wrote: > > > All my machines - steppers and servos are running pid. I think > > Peter forgot to mention - The reason PID is recommended is because it > > handles latency spikes way better. We have seen situations where a > > latency spike confuses the hell out of position mode stepgens. > > (ymmv) > > But thats why we run preempt-rt kernels Sam. Even on the pi, the maximum > spike is 200 microseconds while FF is initializing. W/O FF, 4 to 50 > u-secs. And the big lathe has never noticed that. The little mill, > before it commited suicide by spitting out all the balls of the y nut, > was running sw steppers, and they did notice occasionally. It also > severely limited that machines rapids, to around 8 or 9" a minute. > Putting a 5i25 in it and it ran about 50 ipm w/o any stutters. > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
