LinuxCNC S-Curve Accelerations

Hi grotius,

as quoting in this editor really is painful, I try to give some comments without directly quoting context.

How drag/drop can be quicker than using git from the IDE or comand line I don't understand. Definitely no mandatory copy pasting involved. And you would get nice history of what changed when and why.

The G64 stuff is not a theory, it is kind of a standard, and provisions like that exist in other machine controllers too. I have never used nor seen mach3 in action, but AFAIK it is also derived from NISTs enhanced machine controller.

As I mentioned in my post, exact following is not possible, so you have to make some compromises. The trajectory should be modified to keep feedrate near programmed value while obeying G64 tolerance setting, and acceleration/jerk limits of joints.

The rest you describe in "short" already happens in linuxcnc trajectory planning. On youtube you can find a video from Rob Ellenberg that explains how optimization of transitions are done. Don't have the link handy, but it should have already appeared somewhere in this thread.

I am cheering for Grotius. I have seen him transition from Mach3 to Linuxcnc, mastering ethercat to a high level and teaching himself how to program in C from a zero base. In a few short years, he is now  tackling complex problems like trajectory planning and jerk limiting which is nothing short of amazing. What he lacks in knowledge, he more than makes up for in tenacity. I am certain he will achieve his goals and I sincerely hope he can share his success with the Linuxcnc project. 

There has been an awful lot of talk about jerk limiting here, but there is really only one person who has really made progress. Whilst he might be unconventional in his approach, I'm sure he will eventually teach linuxcnc how to limit jerk.

rodw: I didn't intend to sound negative. back to lurk mode for now.

Grotius = T1000 Terminator
He does not give up, ever.

Hi,

Thanks for your kindness. It certainly gives a boost.

The plan for this year is to test the scurve on one of my machines.

Actually i build a new grotius model a year ago in the summer.
Sinds then It's still unused in storage.
It's the fastest ethercat stepper cnc i ever build.

I am tired of welding gantry machines or tube cutters myself over the years now,
In coming year's, we will see what the course will be.

That makes it excited and important to finish this scurve library.
Then the planning is to test the scurve-lib for long periods of time
on that machine, to find and fix any bug's, or improve the library.

After that is done, the planning is to build a special cnc machine,
I have not decided the exact configuration, but could be a 6 axis robot
on top of a 3 axis gantry machine.

Then i could use the kinematic library for this and expand software from there.

@ Rmu,
From now on i will do the git updates trough the command line for this project. Just updated like that.

On youtube you can find a video from Rob Ellenberg
I have seen the video of Rob. It's good this video excists. In the video Rob also referred to mach3, but
he never did a reverse engeneering on mach3. I think back then ghidra was not published yet by nsa.
Rob's position in the technology sector has it's benefits. 

As I mentioned in my post, exact following is not possible, so you have to make some compromises.
I agree with that.




 

Hi, a little project update.

Today i finished the sc_look_ahead. I renamed it to sc_optimizer.

It's now a sort of path-rules module. Wich can add extra path-rules any time.
For now it has a 5 important path-rules under the hood. This will cover the most annoying things.
The code is quite compact. Tested with 2 motion scenario's so far.



We have to decide how to use it. I guess it could be used in 2 way's :
1. Do a optimizer over the gcode when it loads.
2. Do a live optimizer, for example look ahead 20 lines of gcode.
3. Do bot'h 1 & 2.
4. A better idea?

The sc_optimzer_gui is a simple test suite to perform sc_optimizer tasks.
It has also a tiny calculator to see how gforce relates to speed, arc diameter.
I think easyest way is to make a tiny list where some value's are already printed.



To be continued.