Thanks a lot for this explanation! Matsche
On 2013-03-09 21:28, Jon Elson wrote: > Hugh Wylie wrote: >> This is a request for assistance from those who understand the code >> structure of LinuxCNC better than I do, and arises from some (historic) >> frustration trying to set MIN_FERROR & FERROR parms to achieve best results. >> > First, MIN_FERROR and FERROR define limits which cause LinuxCNC top > stop with a following error message, but have nothing to do with the servo > response. The way these work is that MIN_FERROR sets a base limit > when standing still. Then, FERROR defines an additional sliding limit > that is proportional to velocity. So, of you set MIN_FERROR to 0.001 > and FERROR to 0.0005 and were moving at 1 inch/second, the total > limit tolerance would be .001 + (.0005 X 1) = .0015" > > Now, there has recently arisen a debate about how these errors should > be calculated, and it was shown that the following error used in the > PID calculation is different from the one used for the following error > trip point. This made optimal tuning difficult, as the error trip > is looking at a different calculated error than the PID is using. > So, you could get an incredibly low pid.0.error and yet get > following error trips at several times larger values. > > I think there is an optional setting to unify these two ways of > computing error, but they may not enter the mainline code > until rev 2.6 > > The [TRAJ] settings only affect the maximum velocity and acceleration > that the trajectory planner will request. Then, it is up to the PID > for each specific axis to close the loop based on the settings in > the [AXIS_n] section. > > Jon > > > ------------------------------------------------------------------------------ > Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester > Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the > endpoint security space. For insight on selecting the right partner to > tackle endpoint security challenges, access the full report. > http://p.sf.net/sfu/symantec-dev2dev > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users -- "In der Wissenschaft siegt nie eine neue Theorie, nur ihre Gegner sterben nach und nach" Max Planck ------------------------------------------------------------------------------ Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the endpoint security space. For insight on selecting the right partner to tackle endpoint security challenges, access the full report. http://p.sf.net/sfu/symantec-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
