Hi all, I am a computer science student who recently got my hands on a UR10e.
I am trying to understand how get_tcp_force() is calculated. When the cobot is fixed in a position and I run a program that just reads the value of that function I have noticed that slowly some values go up.
Why does the force used by the robot to remain stationary in a position increase over time?
Does the robot ‘get tired’?
Well. It’s most likely associated with some drifting of the sensor. The joints will not be affected by this measurement unlike the CB series.
The e-series has its force/torque sensor built into the tool mounting flange (silver part after the last joint).
You should no matter what zero the sensor before you use it in your sequence. 
Use the script code zero_ftsensor() with a wait(0.2) or similar beforehand to make sure the tool is completely stationary.