Hello dear colleagues! I was wondering if someone ever experienced the following situation: I am dealing with a high-precision pick and place application and I noticed that the accuracy on the robot is changing according to the rotation of my part. If the part is sitting "straight", close to 0º in reference to the UF, my accuracy is lower than compared when the part is rotated at around 40º.
My setup is:
LR-Mate 200 iD 14L with 2 GigE cameras, one mounted on the robot's EoA and another one fixed to get the part offset after picked-up.
Since this is a high-precision application I do the picking using FOUND POSITION type of offset and I use WINDOW SHIFT TOOL + COMBINATION TOOL to get the exact coordinates of the part's feature and then I move the robot to those coordinates with the camera as the TCP so I can image the part once more but now having the feature aligned with the center-point of the camera's FoV, only after doing this I move the robot with the gripper to perform the picking. After I pick up I move over to the Fixed camera and I get the Tool Offset of that same feature. I noticed that if the part is picked when is sitting at close to 0º the offsets are around 300 microns but if the part is picked a little bit rotated, around 30º the offset is 50 microns, sometimes even less.
The UF was created using AGFS (Automatic Grid Frame Set) and I set the camera TCP as well and the camera was calibrated using Perspective 2 Plane Calibration.
To keep things even more accurate I am keeping the the standoff distance the same throughout the process, so if the part is 1.5mm higher than the calibration plate, I move the robot up that same 1.5mm to keep the distance consistent.
The part Z Height was also entered, but seems to have little to no effect on the feature coordinates.
I am struggling with it for quite a while, so any tips would help! Next Monday I will be able to post pictures or the program...
Thanks a lot guys!