I have played with mach's trajectory planner when rob started working on
the new TP.  I actually used  linuxcnc to show what mach was doing.  I
used the step/dir output from mach -> mesa 7i80 encoder input ->
linuxcnc.  Not only was there acceleration constraint violations - its
path following shows similar issues.

http://wiki.linuxcnc.org/cgi-bin/wiki.pl?NewTrajectoryControl

It gets worse the faster you go it seems.

I am also surprised that mach didn't perform better.  In most test I
have done mach ran a bit faster.  (because of its acceleration violation
/  path tolerance.)  I believe that CV Dist Tolerance_____Unit is the
distance from the end of the line that it is cutting to where the arc
starts rounding.

It is awesome that we can check the trajectory planning within linuxcnc
using hal. 

sam


On 03/08/2015 06:37 PM, Andrew wrote:
> 2015-03-09 1:11 GMT+02:00 Robert Ellenberg <[email protected]>:
>
>> Nice catch, Sam! those variables definitely should have been doubles, not
>> ints. I'm not sure whether the comparison numbers Andrew posted were for
>> the lines or arcs example, but it looks like 2.7 is at least competitive.
>> 3:04 is second place on that list!
>>
> 3:04 is for P0.1
> But they had 4 units in Mach3, not sure what it actually means
>
> Mach3 performs even worse on the arcs he says.
> Here's the link for the topic, google translate will help with russian
> http://www.cnc-club.ru/forum/viewtopic.php?f=41&t=2558
> And I can ask the author something if nesessary.
>
> It surprises me a little that Mach3 isn't higher on that list. I wonder
>> what lookahead setting they were using?
>>
> He says Mach3 best performs with these settings
> http://www.cnc-club.ru/forum/download/file.php?id=38185&mode=view
>
> Talking about Mach3... interesting trajectory screenshots
> http://www.cnc-club.ru/forum/download/file.php?id=44822&mode=view
> http://www.cnc-club.ru/forum/download/file.php?id=44823&mode=view
> http://www.cnc-club.ru/forum/download/file.php?id=44824&mode=view
> This is for acceleration 100, 500 and 1500 mm/s2 respectively
> Settings http://www.cnc-club.ru/forum/download/file.php?id=44825&mode=view
>
> And voila, the machining results for the same GCode
> Mach3
> http://www.cnc-club.ru/forum/download/file.php?id=44782&mode=view&mt=1
> and NCStudio
> http://www.cnc-club.ru/forum/download/file.php?id=44781&mode=view&mt=1
>
> Mach3 is seriously broken according to this...
>
>
>> @Andrew, I'm taking a look at the current velocity display issue, I think
>> it will be a simple fix.
>
> Great, thanks!
>



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