Another Jerk (and more!) controlled controller

[Mooselake]

I stumbled across recent TinyG item today discussing their approach to jerk (along with snap, crackle, pop, and an as yet unnamed 7th order property) controlled motion.

TinyG is software for a juiced up (double clock rate) arduino type usb cnc controller.  They also have a port to an ARM based Arduino Due called TinyG2.

I don't know enough to tell if the extra orders are significant or just marketing, but it sounds interesting.

Kirk
. 

[ArtF]

Thanks Kirk:

  I enjoyed that. Written by someone that knows the math by the sound of it. As to marketing or not?
Marketing!. lol, even Auggie with 6th order is too high according to some conversations Ive had.
Greg, from Tormac once told me he figured anything above 4th order would be unnecessary on
most machines, and he may have been right, but over the years I had many responses to Tempest, so
I know it helped out quite a few.  3rd order is jerky, snap order removes 90%, crackle another
8% , pop another 1.5%..by the time you get to the unnamed 7th order (Crispie?), I doubt
one could see it in any realistic sense. Seems a waste or processing time as it raises the
complexity of the calculations. But then..if you have the CPU time.. :) , never say never. I suspect
its like 1 million count encoders, more marketing than useful.

  I say congrats to them, nice to see the field progressing.

Art

[Mooselake]

So snap, crackle, and pop aren't just something that Synthetos developed, then?  I was wondering if they were still around, they haven't released any hardware or done any Github updates for a couple years.

Crispie, crunchy, creepy for the next 3?

I don't remember if it was here or another forum, but I clicked and watched a link to an hour long Youtube video by the developer of LinuxCNC's latest planner.  It sort of indirectly suggests that a gcode preprocessor could do at least some optimization and reduce the burden on real time code, but I haven't really found any.  Is there some reason they haven't caught on, at least for 2.5D code?

Kirk

[ArtF]

That video is pretty much how Auggie works, but Auggie's planner does go further to snap, crackle and pop correction.

  Im in the middle of the module that processes Gcode into shapes for reprocessing, so we'll see
over time how much sense that makes.. :)

Art

[chicoxiba]

TinyG's planner is Exact Stop AFAIK. There is no constantVelocity or segment blending.. so speed would be handicapped highly if I'm not mistaken. But here is a very impressive video of tinyG running a bit of 3d printing gear..https://www.youtube.com/watch?v=Om0wTqFA-Dw

Regards,
F

[ArtF]

Thx for the update.. I was wondering how they crammed all that in a small cpu.. makes much better sense now.

(Thats thing screams.. :) )
Art

[chicoxiba]

just found this and thought it would be worth sharing..

cheers, F

[ArtF]

Hi:

Thx for the paper, in a nutshell, its basically how Auggie works..

Art

[chicoxiba]

Hi Art

Just found another cool paper...  http://research.engr.oregonstate.edu/mp ... alCopy.pdf

have fun

cheers,
c.

[ArtF]

Hi:

  Interesting paper. Its basically Auggies planner again in almost every way, the single exception being the blend formulas,
in that I use a hermite curve rather than a bezier. The two share the most important qualities though. Im quite happy
with Auggies motion generally, though I have tweaked a few things recently in acceleration computations. I will be doing
more work on it this winter as I burn more with my laser and I'll see what improvements I can make. Auggie has few users for
motion, of course lasers via windows isnt a large field of people, and cnc is now a very different animal than when I wrote
Mach3, so I dont suspect Auggie's motion controller will ever grow to a large enough community to expand it too much. I
do have a galvo scanner Id like to add to it soon though so you never know what capabilities will show up in there. I add
anything I write to the release of course, so anything could show up. If you find motion bad in any particular way always let me
know so I keep it back of mind for when I open that code next.
  I know your troubles are usually surfboard related if I recall right, so speed at small segment is  the type of trouble you
hit.  Thats a very typical result on that type of work, I think a more bezier motion may help , some sort of nurbs capability to get rid
of all the small line segments.. or elliptical motion capability rather than arc.  Anyway, keep sending such papers,I do like to
keep up ono current thinking..

Thx
Art

[Mooselake]

Printrbot now has a TinyG2 (ARM based) printer controller board that replaces their AVR Printrboard.  They're shipping it in their $1000 entry level new Simple.  While I think they're pricing themselves out of the market, Moose have been wrong before, and it has the potential to become a widely distributed product.  Since it's "open source hardware" it might even make it into the far east manufacturing megalith and make higher order acceleration available from the usual sources in high volumes.

They aren't selling the controller separately yet so there's no pricing, but it could be interesting.  If it's close to the current $69 pricing I might even go for it.

Separately, Smoothieware has 7th order acceleration under development, and a pre-order Smoothie based controller has just arrived  in the Moosecave (a Coherent3D Mini).  It drops into the cheap K40 laser using the same connectors and pinouts as the factory shipped controllers.  It's waiting on a few parts from the aforementioned megalith sources, stepper drivers and an (optional) graphics LCD display.  Now I need to buy another laser (not to mention Mooseshop expansion) to compare Smoothie with Auggie; the no-snow work outside season is rapidly coming to a belated end with 3" planned for today, and there should be more time for the interesting stuff...

Kirk

[ArtF]

Kirk:

Cool, I was curious about those. Let me know how it works out. Hardware is fast becoming amazing..

Art

[Mooselake]

Cool, I was curious about those. Let me know how it works out. Hardware is fast becoming amazing..

Me, too :)  It's a purchased hand assembled pre-order, cost around a hundred bucks with cables and glcd adapter.  Iirc the target production price is around $70 (just like an AVR based Printrboard these days).

Hardware has been amazing since a 360/44 cost under a million dollars...

Just got an 8 port gigabyte ethernet smart switch for $25.  I can remember when a thousand dollars a port was cheap for ethernet, and I passed on pulling network wire in the mooselake manor after stripping the lath and plaster, since it was just too expensive to afford.  Think that was still in the coax days.  Whoops.

Kirk

[chicoxiba]

Hi:

  Interesting paper. Its basically Auggies planner again in almost every way, the single exception being the blend formulas,
in that I use a hermite curve rather than a bezier. The two share the most important qualities though. Im quite happy
with Auggies motion generally, though I have tweaked a few things recently in acceleration computations. I will be doing
more work on it this winter as I burn more with my laser and I'll see what improvements I can make. Auggie has few users for
motion, of course lasers via windows isnt a large field of people, and cnc is now a very different animal than when I wrote
Mach3, so I dont suspect Auggie's motion controller will ever grow to a large enough community to expand it too much. I
do have a galvo scanner Id like to add to it soon though so you never know what capabilities will show up in there. I add
anything I write to the release of course, so anything could show up. If you find motion bad in any particular way always let me
know so I keep it back of mind for when I open that code next.
 I know your troubles are usually surfboard related if I recall right, so speed at small segment is  the type of trouble you
hit.  Thats a very typical result on that type of work, I think a more bezier motion may help , some sort of nurbs capability to get rid
of all the small line segments.. or elliptical motion capability rather than arc.  Anyway, keep sending such papers,I do like to
keep up ono current thinking..

Thx
Art

Yes Art. I'm in the need for a bit more speed and smoothness. At the moment LCNC is leading the charge of PC based motion quality i think.... Tried many pc based.. most rubbish for 3D freeform G1.. Tried Mach3 tempest (the Sep29 last upload to the forum) too.. there something a little funny.. It is very interesting and almost there it just stutters in a smooth manner at decel and its enough to get things into a swingy vibration...  Its like a Wowowowowow just before X reversing direction.. It moves quick.. speed is not a real big issue with it.. If I set the Jerk high it moves its arse quite well. Bloody chinese pendants are good but are not as good Look and Feel as a PC so I don't want them. Any chance you want to develop Mach3 a bit more? I wouldn't mind using tempest in Mach3 but Need the ESS and Pause. LOL

regards,
F

[ArtF]

lol..never happen.

Art