Hello,

We are pulling a tube out of a machine and I would like to make sure we actually removed the tube before restarting the machine in case gripper drops the part.  We have the RobotIQ F-85 gripper and the part weights 0.65kg   I've tried using the rq_is_object_detected() but it is unreliable and alarms out frequently when the gripper is still holding the part.  I issue the rq_close_and_wait() then immediately after check the status of rq_is_object_detected().  So I thought perhaps I could check the payload weight?  I've searched the forums but I cannot find an example of this. Can it be done?  Thanks!

It can, just zero the ft sensor before you pick up the part, back out of the machine and stop to measure, just remember to wait a second or two for motion to stabilize then record the forces on the sensor. You can them compare the same motion with an empty gripper and a part and you can set a threshold that it needs to be over to know you have the part. 

Thank you again Matthew.  I've experimented with the Force() function to read the force but I cannot figure out how to zero the force.  Do I need an FT Sensor or is that built into the UR10e? Sorry for these basic questions I do spend hours searching for an answer before I ask.  I'm thinking maybe I should make some custom grippers for the Onrobot Gripper so it grips the part more firmly and then maybe the grip detection would work.

The UR command to zero the sensor is zero_ftsensor(). You will need to have a script node in the program and then just enter that in that script node command.  Just make sure you are holding still when you do this, do not do it under motion as you would not get the best zeroing of the sensor and for weighing you want the most accurate forces you can get.

The E-series from UR do contain an actual FT sensor in the tool flange so this method should be reliable.