Possible ways of using a real-time image of a flat object in the process of painting that object with a robot.

Quote from Gocea

Hello friends,

if I want to paint a certain flat rectangular object, is there a way to use a captured photo of that object as the basis for the robot's movement during the painting process?

Thanks in advance.

Yes, with caveats. You would need a calibrated vision system that could measure the position of the object in 2D space. This requires high contrast and easily identifiable features. One corner of the object would be configured as a reference frame, and the robot program could follow that frame in X, Y, and Rz coordinates.

This generally works by setting up your program and the vision system with a part in the "perfect" position. Then when a duplicate object is placed in the vision system's FOV at a different location (within limits), the vision system could generate a relative offset that the robot could use to offset the reference frame.

Another approach, one I've used many times.

It requires use of a simulator or other program that can do CAD-to-Path functionality (e.g., RoboDK or similar).

As a guide, this is what I've done in SolidWorks and various simulators:

1. create a 3D CAD model of your workpiece
2. insert a JPEG of your photo as a Sketch on the desired surface
3. scale the image to match reality (test to be certain)
4. build another Sketch on the surface that describes the robot path(s) to be taken...you should be able to see the path(s) overlaid on the image overlaid on the workpiece
5. assign three "feasible, touchable, and repeatable" physical point locations on your workpiece and CAD model that will be used to construct an arbitrary coordinate system ("Frame") for "calibration" of your CAD model to an acceptable approximate location of your path in real space (Origin point, X-Axis point, Y-Axis direction point). Construct any type of "appliance" or "location aid" needed to help you get a good point and add that to the CAD model
6. create a simulated workcell with your workpiece
7. use the simulator's path development functionality to develop a program to move the EOAT along the path(s) relative to the part frame
8. teach the as-installed three points in the physical workcell to establish the Frame (you'll need an accurate pointer & tool transform for your robot). This will be used in your functional robot program.
9. make your program run the series of path points relative to the Frame
10. tweak & adjust

Accuracy required depends upon the requirements of your process. Spray painting can generally have sloppy tolerances. Precision pin striping requires tight tolerances.