Possible to automatically compensate for irreguarities on the XY plane?

Hey, does LinuxCNC have the functionality to correct for irregularities on an axis surface plane like the XY on a gantry/router CNC? If I make a surface map file of offsets in the Z direction of the XY plane is it possible to have LinuxCNC automatically compensate for them? I’ve been doing a project involving a laser line projection onto a webcam sensor that is attached to a W axis and spring loaded so it can touch a surface It acts kinda like a CMM but only gives me about 2.5mm of range in Z to work with but does allow me to get down to a couple microns of measurement. I’ve still got some problems with it to work out but here a recent video on it’s progress

 And here is how it operates www.youtube.com/shorts/vuXR8RIW44o  What I’d like to do is generate an offset map of the XY plane by taking a grid of measurements with the sensor in the air (not touching anything) and then feed that data back into LinuxCNC to automatically compensate when running gcode. 

Have a look at this:
forum.linuxcnc.org/10-advanced-configura...nting?start=0#167181

I think this is still python 2 which runs on linuxcnc version 2.8.x while version 2.9 and higher would require updating the code to python 3.

I wonder if somehow a hal_port could be used to pass a point array, much like a survey grid format
The component could extrapolate the height at a given point as you would plot a contour line and adjust the height using external offsets in real time.

Yeah if the hardware exists. In python I store the numpy data array in a python pickle file and 10,000 (100x100 grid) sample points is less than 100kb. It’d be good to have no constraints on grid size. Keeping things in python to extrapolate a given height position allows you to leverage scipy and all the many interpolation options it has.

I’m running a build of LinuxCNC that got pushed to the Debian packages and it’s running python3. I wouldn’t be caught dead writing python2 these days.

I’m really interested in trying to get this working in LinuxCNC because it would allow you through software to improve the capabilities of a machine through further calibration. You could run it like the 3d printers do with automatic bed leveling for engraving or you could give it a calibration map with more points and that would be used for more conventional cnc machining.

If such a thing were to be integrated into linuxcnc, it would be good if it could be overwritten easily as to how the data acquisition works. For instance I use a second computer running windows and a python tool that solely is made to read the webcam sensor values of the laser position. That way I don’t overload the processing power on the linuxcnc machine. The tool driving linuxcnc remotely really just wraps gcode in python with some extra steps where it requests sample data from the other computer over a socket connection. Then it controls LinuxCNC with MDI commands.


I’ll have to sit down and read through what scotta got working with the code on github. I’ve never tried python component in linuxcnc but it looks like it could be a good starting off point.

I’ve got a bunch of changes (software and hardware) that should improve the way I’m taking samples. I also think adding a sensitive temp sensor and including those data points with time could allow me to correct for thermal expansion drift that I find happens. The machine takes 2-3 hours to take 100x100 samples and that is enough time to warm up the garage and all the metal parts.

I’m not sure how out-of-flat my XY plan of my cnc machine is. I’ll probably run a high number of samples over the entire work area just to get a clearer picture of it and reduce the numpy array size after if necessary.