GearHeads Corner

Thats ok :'( ;D

Thanks,
F

Dear Art, would it be possible to set jerk limitation individual per axis within Auggie's Trajectory planner?

thanks,
F

F:

Ill look into it, but Im not sure that doable mathematically. While it would be possible for something like Jogging,
Jerk when moving multiple axis is a measure of the accellerative energy of the entire motion. I know this can be hard to tune and will be working on it here to see what improvments I can do. I use a jerk that ranges from 50,000 to 500,000
while I know others use as low as 5000. If I load a vine for example, I can scream through it at a jerk of 500,000 but its slow going on point to point moves if its too much lowr. On a raster scan burnign 3d photo's I use lower at 50,000 to
more greatly smooth out the raster start and end points more as my table can vibrate.
  If I set it too high the autoslow for softlimits kicks in too early for me.. So there is work to do, but too few users of Auggie's motion control to dedicate too much time to that desire. I do continue to work on it though as I have one table completely Auggie driven where I use multiple types of speed strategies.

  As an experimental planner its doing far better than I had hoped, but I know its still a bit limited in some types of work unless jerk is pretty high. I will however, look into a per axis jerk to help when single axis are way off other axis in terms of the jerk they can handle.. Perhaps a dual system where the systemic jerk is respected as it is now, with a further planning per axis jerk for the initial feedrate planning. That would allow a Z for example to self limit itself when it
is involved in a motion..

Thx
Art

F:

In thinking about this in the background, it occurs to me that in Auggie, the jerk is overridden by acceleration.
So my advice would be to set all accelerations very very high, tune jerk for a system that is overall smooth and fast
without regard to any axis that would need to be limited. Then, lower the accel only of the axis your worried about.
This will cause a jerk override on moves with that axis, while leaving the others at as high a jerk as is acceptable.
  Accel will limit jerk and jerk will limit accel, so it should be safe to set very high accel's while tuning jerk.

Art
 

Hi Art

Thanks for ever considering all  these things.

I asked if it was possible after reading about a certain Siemens cnc controller where you have the ability to set jerk limit to each axis.. Then I thought it might bring something interesting to the table here.

Perhaps you could benefit from having this trajectory planner be used in Mach4? I would then be a very active tester as it would make my life a lot easier not having to deal with pokeys... I looked and looked at the  2 pokeys options and got unanimated.

Anyways.. just thoughts.

Thanks
F