OpenCV vision with EMC/linuxcnc

Ed, On my PnP, the fudical camera is also used to set the location of the components in the machine. I have 2 options to get parts from, 1 is a feeder - using reels, the other is a tray.
The feeders are all mounted such that the parts are presented to the pickup in the Y axis of the machine travel. So for each feeder, I move the camera over the part and adjust the Y (controlled by the machine movement) and the X of the feeder (controlled by the feeder itself) until the part is centered. This information is then saved for each feeder in use. So again, output to control would just need to be X,Y position data. BTW, that is all done manually - go figure.

The trays - which would lend itself better to the DIY commuity IMHO, just get stuck to a fixed bed in the PCB area. In my case I use double sidded tape to hold them down. Keep in mind, anything can be a tray to include short pieces of tape. To set up the tray position, I just jog the same fudical camera over to the center of the first part to find the reference for the "tray".This plus tray dims are saved for each tray.

Seems like the vision system really just needs to be able to spit out position datd for whatever it is looking at. I would guess there needs to be a signal from the control to say "take a picture", then the VS will send back data in some form such as X,Y,Theta. From there LinuxCNC will need to use this depending on what task is needed to be done.

I am not at all sure here, but this may be a job for a "somethingKIN"?

So far I have not done a project that requires absolute (machine-relative) positioning. I therefore use part-relative manual touch-off in the G54 reference frame. The limit switches are there to stop the machine if a software error (or operator error) causes it to go out of range, so they act just like the e-stop.

Yes, I did do one project that required working very close to the limit. For that project, I did manually use the limit switch for (effectively) homing.

I must emphasize that I am a newbie with no real experience. I just think it is a good idea to have a feedback system that tells me that the machine is approximately where it is supposed to be, and stepper-based systems do not intrinsically have such a system.

Thanks Andy,

Will be sure to keep you posted!

Hi Andy and everyone else,

I've got started with using python for the userspace hal module. So far opencv is happy alongside the hal, it appears to be capturing images in the loop in python. I say this because no errors are reported and cpu load increases, however the highgui window to display the frame will not show. Is this a limitation of the userspace hal components? I'm directly testing python opencv routines side by side, both in and out of linux cnc hal. What works and displays an image outside of linuxcnc does not work inside the python hal module.

Here is the pyhton script (sorry for the noise, it's only short) - I named this hal1:
If you're going to try this out, the dependencies are satisfied on ubuntu 10.04 with linuxcnc already instaled with the following:also, having a webcam/video grabber plugged in would help.

Do you know of a way to write an image into a part of axis instead? Would that be a part of pyVCP or the other VCP?

Any ideas greatly appreciated,

Cheers,
Ed

-- edited code, grr - indentation... mumble mumble

Another question that has arisen...

I'm a c++ man at heart. Would I be better off working in my native language with a hal component that's not userspace?

Does this have implications with the real time parts of linuxcnc?

Thanks!


Ed

Lol - ok!!

Ahh - if c++ is an option - where do I look?

I'm not loving the python-ness with opencv - c++ would be infinitely preferable!

Don't suppose you've got a link to a starting point for c++ userspace hal modules?

Thanks!

-- edit - found a sensible place to start - www.linuxcnc.org/docs/2.4/html/hal_comp.html#r1_13