Collisions processing

We are using xArm for making “build a tower” attraction at our planetarium. Motion control part is ready and works alright now. There is just one more thing left to do: collisions processing.
The only possible collision is a collision with an upper surface of cubes or a partly done tower, when the tool is moving downwards. But that will definitely happen quite often. Each time a buzzer will sound and xArm will get into zero position.
What is the best and safest way to process the collisions here?

Could you show the issue with a video? Thanks

Probably you got my description wrong, sorry for my english.
I just tried to explain how our attraction will work. There is no any issue. Yet, at least)

The question is: What is the best way to handle the collisions within our code? We have tried to analyze the torques, but found it hard to process even light collision (5N) before system initiates emergency state.

There a Level0-Level5 of collision sensitivity for the system, if you want handle the torques by yourself, you’d adjust the collision sensitivity to a low level for example Level2 to avoid frequent collision error report.