Re: Newbie Q, tuning for max speed

[Damon Gentile <dgentile-at-spf.fairchildsemi.com>]

Jon, 
 I thought that MIN & MAX_OUTPUT were only used for servos ? I'm 
running some (puny?) 116 oz/in steppers, no feedback.
 Good insight on what happens by decreasing period, I'll really 
try and crunch that down so there is less delta.  With 20uS, the
PC is noticeably slower. Maybe if I kill the nescape widows...
Step resolution is 0.0000625 (200 step motor, 1/8th step, 10TPI 
leadscrew)
 I dont care so much for flat out speed (G00) but ability to move
and not error out will be nice. I can typically get about 30IPM
on any axis at a time, coordinated 2-ax moves seem a little more
problematic. I'll try and tweak the PID and get a better grasp on
where it falls apart. 

Thanks,
-Damon (Hoping the 116oz/in is enough to cut butter)



> 
> Depending on your step resolution and desired max_velocity, you may need
> to cut PERIOD
> to allow more steps/second.  I think you can go down a bit, but you are
> already at 20 uS,
> I don't know how much more you can get out of a 333 MHz Pentium.  20 uS
> allows
> a step pulse to be output every 40 uS, which is 25 KHz.  But, this means
> the last speed
> jump is from a step pulse every third PERIOD tick,  or 16.67 KHz, to
> every other at
> 25 KHz.  That's a jump of 33%, no motor could follow that.  Your
> acceleration of
> 5.0 may also be too high.  I usually use 2.0 on my systems.
> 
> Jon
> 
> >To judge lost steps, I have it make a 200" move in one direction and
> >see if the shaft ends up in the same rotation that it started at.
> >
> >Thanks,
> >-Damon
> >
> >[TASK]
> >CYCLE_TIME = 0.004
> >
> >[EMCMOT]
> >EMCMOT = freqmod.o
> >COMM_WAIT = 0.010
> >PERIOD = 0.00002
> >
> >[TRAJ]
> >CYCLE_TIME = 0.010
> >DEFAULT_VELOCITY = 0.0167
> >MAX_VELOCITY = 1
> >DEFAULT_ACCELERATION = 5.0
> >MAX_ACCELERATION = 5.0
> >
> >[AXIS_0]
> >P=1000
> >I=0
> >D=0
> >FF0=0
> >FF1=0
> >FF2=0
> >FERROR = 1.000
> >MIN_FERROR = 0.010
> >
> >
> >
> >