Bobbie 4.0: What is the safety cable for?

The rope is a mandatory safety feature. This is to prevent the robot from falling on someone if it were to come loose.
This is, of course, extra important for windows that are not on the ground floor.

The cable also prevents the robot from hitting the ground if it falls.

The robot will not fall easily.
Firstly, the battery will ensure that the robot remains attached in the event of a power interruption.
Secondly, if the window is too wet, the robot will slide (and squeak) but not immediately fall.