Hello everybody.

First: Sorry for my poor English.

Context: I have a URDF model with three links (A --> B --> C) in Gazebo. A is a controlled movil robot and C is a manipulator arm controlled (PIDs,IK_solvers). B-C have a joint with a PID controller and A-B a joint. The mass of link C is center and it doesnt't affect to A. I want that the efforts applied in C doesn't affect to A (To eliminate the reactions)

Question: Is there any way to the applied efforts in link C don't affect to the link A? Any kind of Joint (A-->B) that doesn't transmit the efforts applied in the link C to the link A ? Any ODE coefficient that eliminate that transmission?

Thank you very much for your advices