Robotiq Grip Check not detecting an object

Technical Questions URScript
1

We are using custom fingers with a diameter that grabs hot plastic parts out of a mold. The part is slightly smaller than our other products but the sprues are relatively the same. As it grabs the shot out of the mold and puts it on a support plate to start a Grip Check, it doesn’t detect the sprue and goes back to first position instead of going to a new task.

I programmed it so that when It detects a sprue, the cobot grabs it and sends it to another station, then return to first position. If no object is detected (sometimes a processor will come by and take the part at random times of the day) it will go back to first position. It has been working fine for our other molded parts.

When I manually set the gripper to close 100% with nothing to grab, the actual reading it gives is 97.65%. When I set it to close on the hot sprue, it reads ~96.86% closed. I tried out the “confirm with dimension” feature and it still won’t detect the object.

I then tested to see if the part was actually being gripped tight enough. I manually closed on 90%-100%.
94%-100% closed on hot sprue is tight but 90%-93% is too loose.

Are there script functions that could help with this?

2

Not familiar with the Robotiq grippers, but on one of our OnRobot applications, one of the other engineers created a “teaching” routine where on the first part it closes in steps - each time it checks to see if it’s gripping anything. If nothing is detected, it closes a bit tighter and checks again. Once it finds the part, it stores that dimension and works from there for the rest of the lot.