ok...been looking around and what is "stepconfig" ?
* skunkworks introduces ken to the docs.. ken meet docs - docs meet ken.. http://linuxcnc.org/docs/
hi doc and thanks skunkworks
ok...i found stepconfig info...but it don't tell me how to get to it(start it)
never mind...found it :)...guess i need to open my eyes :0
SWPadnos_ is now known as SWPadnos
y helo thar
lerman_ is now known as lerman
cradek: you only had 5 levels of pwm when you used pwmgen - right? what kind of following error where you getting? Do you remember?
(for your lathe - before the pluto)
it was probably more like 20 levels -- 1ms/50us
skunkworks_: I don't remember if it was +-5, but it was pretty darn low like that
the FE was a few encoder counts
but I doubt it's a good test bed, considering how light the machine is
still damn cool :)
the pluto setup is so much better!
hmm - I may have upset some engineers.
[13:37:40] <skunkworks_> http://timeguy.com/cradek/cnc/lathe
I mean.. http://www.cnczone.com/forums/showpost.php?p=440411&postcount=147
wow, I got strawmanned in a thread I'm not even participating in? that's amazing.
That happenes a lot ;)
there are probably contracts out on your life.. :)
well.. when you start having hitmans
that Tom guy asked me whether emc would reverse command to the motor in order to decelerate faster than coasting to a stop
then you should be worried
the answer is definitely yes, and I tried to explain why
wee a hornets nest
yes - I had said the same thing when they where worried the h-bridge wouldn't brake fast enough.
kreutz was being sarcastic, but there is a kernel of truth in his sarcasm: pid can probably cover up a lot of crappiness in a drive
Yes, - in the last post I posted - I tried to smooth it over.
some people allways get the wrong end of the stick, cradek's explanation was plain, to the point and correct
the correcting loop in this case just happens to be in software, and not an "engineers" electronic loop
people who have been in motor control for a long time might not believe how well a fast single pid-ff position loop and a high resolution encoder can do
surely velocity mode amps are still king, but you can get by with less if you throw computing power at it
* cradek shrugs
The guys I admire in these threads are the ones like Tom and Sam who want to actually try stuff and they work for it
aww - shucks
* skunkworks_ blushes
it's easy and cheap to sit back instead, and say it won't work because it's not how everyone else does it
that doesn't contribute much to anything
I only read the stuff you lot point at
I'm excited about the low-cost open hardware designs you're trying to make - combined with free software how can you go wrong?
hmm the Canon colour printer had h bridge servo years ago with a 6809 driving it
well we know a very basic motor drive can definitely work, at least for small stuff
on old machines with a 100Hz servo cycle, not so much
just been digging in my archive, cant find the old source for the printer, should be at home somewhere
maybe it's not archived properly
nah archived deeper
many printer motors use a DSP directly controlling several H-bridges
all the new ones I've taken apart do
in fact, we did a board layout (15 years ago) that used a square-wave trace around the motor shaft as the encoder - the magnets would excite the trace, and we got a tach signal from that
only one I've taken apart that DIDN'T use bipolars was an epson dotmatric
the think Kreutz missed is that you still need a good H-bridge design, it doesn't matter if the corrections come from software or hardware
aren't h-bridges like, really really easy?
pretty simple, yes
I think no high-current circuitry is really very easy
we bought in the A1210 and doubled the resolution and speeded it up a bit (burnt a few motors)
but you still have things like dead-time
and switching loss
and nonlinearity near the switch points
I think I want to throw together a few h-bridges to drive the stack of tincans I've got
the guy building tommeleise (sp?) says he's gotten decent results with them
* alex_joni drops a pin
what kind of pin? roll? ;)
a voodoo pin
HAL pin ?
lapel flag pin (very big deal, I hear)
yes, in some states