A couple more questions with reference to: http://imagebin.org/73098
Looks to me like harmonics in the constant speed section; any suggestions as to its source? There are spikes at the change constant speed/acceleration and vice versa. I wouldn't expect to see that in a smooth transition, any comments? My setup: Brushed DC motors with tacho feedback to servo amps (+-10v control) Ignore limits and f-error: [AXIS_1] TYPE = LINEAR HOME = 0.000 MAX_VELOCITY = 5.8 MAX_ACCELERATION = 20.0 BACKLASH = 0.000 INPUT_SCALE = 20000 OUTPUT_SCALE = 1 OUTPUT_OFFSET = 0.0 MIN_LIMIT = -2 MAX_LIMIT = 2 FERROR = 0.5 MIN_FERROR = 20 HOME_OFFSET = 0.0 HOME_SEARCH_VEL = -0.1 HOME_LATCH_VEL = 0.03 HOME_USE_INDEX = YES HOME_IGNORE_LIMITS = YES MAX_OUTPUT = 10 # PID tuning params DEADBAND = 0.000015 P = 20 I = 0 D = 0.1 FF0 = 0 FF1 = 0.15 FF2 = 0.00045 BIAS = 0.0005 Richard Arthur wrote: > Referring to: > http://imagebin.org/72841 > I've added the motor-pos-cmd trace. > > Jeff Epler wrote: > >> The coarse-position-command is the motor position before applying screw >> compensation or backlash compensation, so it differs from the >> motor-pos-cmd on machines that have these compensations enabled. >> >> > > I don't use screw or backlash compensation so I guess coarse-pos-cmd > should equal motor-pos-cmd. 'A' shows two servo periods. Am I correct in > thinking that the compensation is added to coarse-pos-cmd on the first > period value and hal displays it on the second period? > >> Additionally, the ferror is computed from the *prior* commanded position >> and the *current* motor position, but halscope captures after commanded >> position is updated. On the other hand, PID error is the difference >> from the *current* motor position and *current* commanded position; this >> is why PID error and ferror are not equal either. >> >> > > So in other words, the f-error at 'B' is equal the difference at 'C'? > However, if the motor-pos-cmd at 'C' is derived from coarse-pos-cmd two > periods earlier, it seems to me that the f-error at 'B' is really around > half of that displayed - I must be wrong, I would be delighted if you > would put me right :-) > > Thanks, > > Richard > > ------------------------------------------------------------------------------ > Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day > trial. Simplify your report design, integration and deployment - and focus on > what you do best, core application coding. Discover what's new with > Crystal Reports now. http://p.sf.net/sfu/bobj-july > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > > ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
