adding auto leveling to linuxCnc

Hi 
 I'm having a problem getting the hal commands right on my 'real' machine.
Using the above I have a sim working fine but my machine already has the motors using net _pos-cmd signals as in‘net xpos-cmd joint.0.motor-pos-cmd => stepgen.0.position-cmd’

net xpos-cmd cannot be used twice as it gives a error ?

I’ve tried ‘net xpos-cmd joint.0.motor-pos-cmd => stepgen.0.position-cmd compensation.x-pos’
but I can’t get the compensation to update.

I’m keen to get milling and cutting Depron planes and having the cutting bit following the table will make it a lot easier and precise. Its currently out by .3mm over a metre area.

Any ideas
srl

Depron plane sounds like a great project!
I don't have a solution in mind right now, but here is my checklist when I was debugging mine:
1. open linuxcnc via commandline by just typing in command `linuxcnc`, you should see some additional details of compensation.py output, anything unusual?
2. before you generate the probe-results.txt, there must be an existing probe-results.txt in the folder, or it will fail to load.
3. Documentation on eoffset -- `External offsets apply to axis coordinate letters (xyzabcuvw). All joints must be homed before external axis offsets are honored.` This had me stuck for a long time because my machine did not have home switches linuxcnc.org/docs/html/motion/external-offsets.html
4. Hal scope might be useful, check if anything under eoffset react to your input

I got it going and it was easy.

Just changed the name of signal line like this-

net xpos2-cmd <= axis.x.pos-cmd => compensation.x-pos

I can see the Z motor moving so its now fine. Now time to scan the table again and get it around the 0 Z level.
Will post again when I cut .1 mm above the glass.

Thanks
srl

The scanning and Z compensation seem to work properly (I check this using a cup, I scan it, remove it and then I see when moving on same 'Z' depth, the tip carves the shape of the cup). The problem I have is that the Z compensation is lagging, when I put the cup back, there are collisions between the tip and the cup, the Z is lagging behind the current XY position.

seems that compensation.py is best for dealing with a flat surface that is tilted or uneven -- you sample surface height at 10 mm X-Y spacing, and then it interpolates a height map with 0.1-1 mm resolution depending on the scaling factor.

Check out Compensation.loadMap() method definition from the compensation.py file. ~ 30 lines of code and this is where things happen. If you provide a much denser probe-results.txt, the code may handle it poorly if without modification.

Essentially what loadMap() does is take X,Y, Z value from probe-results.txt, clean it up a little bit, feed them into scipy.interpolate.griddata(), and returns a value-mapped 2D array with X and Y being the index.

Since array indicies cannot be float, so X and Y must be int() -ed, and this might be a significant source of error (and bug!) if you r application requires a much better resolution than 0.1-1 mm.

ok, will check, thank you for your reply