multi axis motion control

Hi.
I'm trying to work out how this program functions.
I'm writing a machine simulator in c++.
i have the graphics engine running and have started to set up basic axis blocks for x, y and z.
I have not made any further progress due to my limited knowledge on how to get the axis
to coordinate to reach a position in say x and y.
I have searched for ages and found this program. it says its open source.
I've found some docs talking about trajectory and kinematics.
can any one point me to the source code or explain how this controls multiple axis.
I want to make my program available for all and would appreciate some help to get it moving again.
I know some will say you should have worked on the motion controller first, but this is about learning
i did all the hard graphics stuff one step at a time. Now its time to learn the next step.
thanks

In linuxcnc's case the screen plotter IIRC uses linuxcnc's trajectory planner to supply it motion commands.
Gremlin and AXIS are the two examples of this (both use the same underlying code) but be warned they are difficult to decipher.

As far as the trajectory planner there is some basic info on th wiki eg:
wiki.linuxcnc.org/cgi-bin/wiki.pl?Trapez...e_Trajectory_Planner
Surely out of date as the current trajectory planner has been enhanced - but gets you started.
There may be more hidden on the wiki.

Unfortunately there is little documentation on the internals of linuxcnc.
Machinekit does have some videos that describe how the internals of linuxcnc work.
Machinekit and linuxcnc have a lot of code in common.

Sorry I can't help more.
Good luck with your project, i'd often thought it would be nice to have linuxcnc's graphics plotter run as a pre-run simulator.

Chris M

Hi.
Thanks for the info.
I have found some info after further google searches - most of it is from research papers that are just basic abstracts.
i have to say for some thing this important there's not much to go on with. Its like a big secret if you want to know more you have to join the club. Looks like i will have to work it out myself.

Many thanks

Hi,

Found this excellent resource for a multi axis trajectory generator in C
www.atwillys.de/content/cc/trajectory-generator-in-c/

Hopefully you can use it.

-automata

Wow wish we had docs like that for linuxcnc!

Hi Automata.

Many thanks not seen that one before.
I found some fpga control schemes which are helping a lot.
I think this is not as complicated as i first thought.
Maybe i was overthinking it - not the first time to be sure.
I got the blocks for a simple lathe positioned in 3D one above the other.
Im going to try and move the saddle along the bed first using software buttons
then the saddle across the spindle face. once i have those working i will upload a video to youtube
if anyone is interested.

Many thanks

Hi Andypugh

That looks real nice. Thanks for the post.

Im not looking for a built to run system. Im trying to learn the whole process for myself.

Write the full graphics engine. Then get it to function as a machine.

Its about learning the entire system first hand. I have all the hardware and the software for

a real machine. I just want to get the hang of how the entire chain works by building it up bit by bit.

Thanks