Vision System: Pantograph
 

This thread is to pursue R&D around the concept of Vision System pantograph on the MechMate

This thread is different to the registration thread because it is about the concept of pantograph cutting.
The idea is to put a printed or hand drawn piece of paper on the table and the vision system traces the pattern and then cuts it. The work material would need to be smaller than the bed to allow space for the pattern to placed on the bed. features could be multi colored patterns to describe different types of cuts or 256 greyscale patterns for different depth cuts.

There's lots of overlap between this project and the registration project in other thread.

Initial topics requiring research:
- Vision software
-- MatLAB - expensive but very capable. A professional tool.
-- OpenCV - opensource, very capable, extensive libraries. requires a steep learning curve and significant development skills to become proficient. may require specific libraries to be custom developed
-- More
- CCTV
-- IP cameras - there is a wide range of IP cameras available for very low prices. The camera probably doesn't require its own gantry. I would put it in the spare payload position on the existing gantry.
- Integration with Mach3 or LinuxCNC
-- Mach3
-- LinuxCNC
- Targets
-- use material itself as target. Vision system can detect edges and depths and other features. I'm not sure what accuracy or resolution.
-- use specific orientation targets. stickers, pen marks, painted corners. This solution is the fallback, it is better if solutions require no specific targets but can orient on material.
-- nested orientation. Is it a requirement that vision system can detect just sheet material edges and orient dimensions or is it a requirement to detect sheet material internal use. ie. Does the vision system system need to analyse a whole sheet and detect previous cuts to find a free space to place the new cut.

Keep the ideas flowing. Add either your wish list or your skills and willingness to contribute to this offshoot project to MechMate.

R Maybe crazy, but if you get a touchscreen and stylus... Or Wacom tablet....Would that not be much easier !? Panthographs were cool before cnc technology was available and still have some use today but this seems overly complex to me ?

What about getting a scanner? You would just scan the artwork and then use software to convert to vector files and then cut it. Thats what most cnc fold are going these days. It has worked for me.
The vision system seems like a lot of hardware, software and work to do the same thing?

I recon a vision system would be best deploy as the means to align the workpiece to the machine. such as something like the followings
clamp a piece of odd shape board (maybe some large off-cut board)on the spoil board.
snap a shot with the cctv camera, load a cutting file & rotate the actual cutting coordinates to fit the cctv image.

Good idea Ken, I would probably do that using the following method:

- machine gantry does rapid search routine something like a spiral or zigzag, the shape doesn't matter so much except for creating a compromise between speed and resolution.
- the search routine detects edges on board, you generally need good contrast for edge detection so I would recommend that the backboard is black if your using mdf or ply. You will have trouble detecting edges on perspex or highly reflective materials but you could have settings that apply different strategies to edge detection on different materials.
- the software maps the positions of the edge dots and then does a second detailed edge detection pass and follows the edge all the way around until it closes the object. Any other edge dots are also mapped with a detailed edge follow to determine internal cuts that already exist in material.
- layout your new cutting file and go.

While researching I saw found a software which offers a vision system....