Testing fiducial alignment on my homemade pick and place machine and paste dispenser named 'PP4'.
More details on my website: www.vbesmens.de
The vision system uses OpenCV:
It uses the Hough circle algorithm to detect the 1.5mm diameter fiducials within an area of interest. The fiducials are located on two opposite sides of the PCB. After detecting them, it checks if their distance is as expected. It then calculates the angle of the PCB on the machine using trigonometric functions.
The resolution of the camera is 67µm per pixel.