Thanks for taking the time to reply Alex, Re Q3 and using HAL to control the stepper motor. Is there some example you know of that I could review? If not, does this approach employ some sort of Trajectory Planner API, or would this approach require implementing a TP from scratch.
If I understand correctly, that understanding comes mostly from reviewing some of the issues in GRBL, a TP is a non-trivial undertaking. Best wishes Hedge On Monday, May 1, 2017 at 2:47:22 PM UTC+10, Alexander Rössler wrote: > > I can answer Q3: > You can protect your stepper motor spec on the HAL level. To ensure the > acceleration and maximum velocity values are never violated one could drive > the stepper via PID loop tuned with the correct parameters. If you want to > ensure the user cannot edit or override the values you can compile them > into a HAL component. > > Am Samstag, 15. April 2017 07:49:33 UTC-5 schrieb Hedge Hog: >> >> Hi, >> I am considering a 3D printing use case, which is likely different from >> most CNC use cases in that the bed load/inertia is relatively >> constant/stable. >> That's a generalization, but probably reasonable to say that in 80% of >> cases the mass and forces will be within a very narrow range. >> Compared to say a CNC machine carving a cubic foot of wood then a cubic >> foot of steel. >> >> I have read [1]-[8] and have three questions. >> From [1]-[8] I can't see that the pull-in/pull-out envelope (or slew >> range) is identified for a stepper motor. Nor does it appear that inputs >> are sought that would allow them to be guesstimated. >> >> Q1) Am I wrong (and there is a set of approximations used to define the >> slew range given the inputs sought)? >> >> AFAICT: >> a) the trajectory planner might be working with a single point on the >> pull-out curve of a motor, so you can expect the TP to try change direction >> in the slew-range of a stepper motor. >> b) The TP does not consider/use the stop-start range where direction can >> be reversed without deceleration. >> >> Q2) Which of the above possibilities is applicable? >> >> Q3) Is there a way to ensure that an end user cannot get the trajectory >> planner to violate a stepper motors specs? >> I suppose these settings would have to be a compiled, or set by >> privileged user access, and can't be overridden by a configure file >> settings. >> >> Thanks again for all the effort that has gone into MachineKit >> >> Best wishes >> Hedgehog >> >> [1]: http://www.machinekit.io/docs/quickstart/stepper_quickstart/ >> [2]: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Stepper_Formulas >> [3]: >> http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Stepper_Motor_Speed_Limitations >> [4]: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Mechanical_Spreadsheet >> [5]: http://www.soundproofingforum.co.uk/halitosis/ >> [6]*: http://www.machinekit.io/docs/config/stepconf/ >> [7]: http://www.machinekit.io/docs/common/Stepper_Diagnostics/ >> [8]: http://www.machinekit.io/docs/motion/tweaking_steppers/ >> >> -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. To unsubscribe from this group and stop receiving emails from it, send an email to machinekit+unsubscr...@googlegroups.com. Visit this group at https://groups.google.com/group/machinekit. For more options, visit https://groups.google.com/d/optout.
