How to apply a constant force along a path.

Hi everybody, and Happy New Year,

I'm working on an welding application where I have a lot of problem with the geometry of the components to weld.
The parts are not regular, they are sometimes curved instead of being straight.
As the process requires to push the tool against the parts to weld, the solution would be to apply a force on my tool in order to constantly be in contact with the parts. (I'd like to control it in X and Y ; See attached pic)



On the other hand, this is very difficult for me to install a sensor close to the tool, because I have no place available for it.

I was expecting to be able to apply this force directly with the robot, but I haven't found how to do.

Is ther someone who could guide me?


PS: I have an IRB 6700 leased to develop the application for my customer

Thanks a lot.