TCP 5-axis kinematics on real machine

30 Dec 2019 09:44 - 30 Dec 2019 10:36 #153544 by jsskangas

I got my core2 duo dumpster find working and linuxcnc installed.

I took look into vismach sim xyzbc kinematics and there are some problems.
B and C axis rotations are incorrect.

CAM software's output toolpath as tool tip location + IJK vectors.
This is called CLD (cutter location data).
Post-processor take this data in and translates it to NC-code and calculates rotary axis position from tool orientation.

In general all CAM outputted nc-code is tooltip data and tool orientation.
It is a machine position where tool is located and oriented as it is in CAM.

All machines I have seen until now has followed this same rule.
To layman's therms, you don't move machine axis you move tool, this applies to rotary axes as well.

If you have machine like xyzbc vismach sim example, X axis is table and moves part.
To move tool X+ direction , part and table needs to move X- direction.
Like it does, and it is correct.

But same rule applies to rotary axes.
When you look trough axis to its positive direction, CW rotation is positive rotation.
When you rotate tool positive direction it would be CW.
But in this case positive rotation of B and C axis would be CCW, cause we are rotating part.
Then tool moves CW relative to part.

Current vismach xyzbc sim example kinematics does not behave this way.
Both B and C axis rotation is incorrect.
I assume that xyzac kinematics have same issue.

Do we change these?
Last edit: 30 Dec 2019 10:36 by jsskangas.

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30 Dec 2019 22:12 #153567 by plopes9000

andypugh wrote:

plopes9000 wrote: Finally, see attached test gcode file and video.

I thought that your video was very instructive about what TCP is, and the Linuxcnc home page needed a new Showcase.

So your video is now on the front page of LinuxCNC :-)

Andy, could you please update the TCP feature video on the home page with this new video link?

Had to create a new version - thank you !

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06 Jan 2020 07:22 #154129 by MDM3D
Hello All, This is a really neat feature!
I am still reading through this thread and I read a lot on AC and BC configurations is it possible to use this "switchkins branch" on an AB configured machine. I have a rotary table for the A axis and the spindle rotates in the B axis. I have attached a picture for clarity.
I guess I am confused as to how I would go about handling the changing offsets between A and B. I hope I am over thinking it.

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21 Jan 2020 18:13 #155341 by bbsr_5a
How do i compile this switchkinetics.c file to get this action

is the Joint numbering open from 0 to max joints e.g 0=x 1=Y 2=z 3=A 4=C ?
or is it fixed as in AXIS_0=X 1=Y 2=Z 3=A 4=B 5=C

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