PLOC2D Frequently Asked Questions

Optical image center should be close to the center pixel in the image, in other words half the x- and y-resolution of the image. If this deviates a lot from the expected values, there may be reasons to question the validity of the calibration.

Yes, all targets can be used interchangeably for calibration and alignment! The alignment target (with the black frame) however needs to be entirely visible to be accepted, while the calibration targets (without the frame) can be accepted even if only partially visible. The main advantage to use the alignment target for alignment is that the coordinate system is printed as an overlay, making it easy to measure with a robot TCP. The main advantage of using the calibration target for calibration is that it is easier to cover the edges of the image, as there is no requirement for all markers to be visible to the camera.

This is likely due to a too large value of the pixel size system parameter. The pixel size parameter is set to 1.5mm by default. This means that in the rectified image, each pixel will be 1.5mm which gives very coarse images when you have a small field of view. Change this parameter under the system settings and perform a new alignment to see the results. Smaller values will result in higher resolution images. If this is changed, the alignment (and everything "downstream" from that, ie job configurations) needs to be updated. A suitable size for this parameter is "as large as possible while still seeing all necessary features of the object to be located".

This is the tranformation between the camera and the alignment coordinate system. No action needs to be taken with these values, but they can be used as a sanity check on the distance between the camera and the alignment plate.

The alignment verification is used to verify whether or not the camera (or alignment target) has moved since the alignment was performed.

 

 

 

This is different from one application to another, but a general rule of thumb is to try to achieve images settings where the object is as distinct as possible. A brightness value over 100 should generally only be used if the exposure time is already at max.

Similar to the alignment verification, the job verification is used to see if the part has moved since the job shape was taught.

 

 

 

If more than one match has been found, the system will calculate the center of gravity of the shape and sort the results by lowest x-coordinate. If a number of matches has similar x-coordinates (within 10mm), these results will be sorted by lowest y-coordinate.