How to simulate the soft and rigid body togather in isaac gym

I wanna control a robotic arm (rigid body) on which there is a silicone gel tactile sensor (soft body) mounted at the end of it in Isaac Gym. The main task is to drive the robotic arm making the tactile sensor contact with the ground or other rigid body. And what I wanna collect is the deformation information and stress distribution on the soft tactile sensor. My question is how to define the relationship “mounted” between the soft tactile sensor and the robotic arm. I guess I have to attach the soft tactile sensor to the rigid robotic arm end, but I don’t know how to achieve that in Isaac Gym or Urdf file.

here is a similar scene:
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