differential transmission URDF, How to?

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Hello ROS Community,

I am reading on the wiki that differential transmission type is also supported, however i could not find any URDF example of how to implement it.

The only thing i found is the example given here, but i still find it difficult to figure out how should i use the given code?

In my system i have five joints (joint1-joint5), and i control them with position_controllers/JointTrajectoryController, however the last two joints (joint4 and joint5) requires differential transmission.

Where should i start the elaboration on this problem? Do i need to write an own specific JointTrajectory controller? Is it possible to use differential transmission in the URDF under the type tag?

Thanks in advance!

Best regards