Problem or misunderstanding when running the stretch movit2 demo

[FrGe2016]

Hi

I have installed the "Planning For Differential-Drive Mobile Base and an Arm" and also configured it for my linorobot2 with an added robot arm. In both cases i have the same issue. The plan works fine, but i am not able to have the execute running. Unlike other used of moveit2 that i had. the controllers are never started because ( error messages related to the position joint not present in the urdf seems to block the starting of the ros2_controllers).

How will i implement that with a physical robot. The lino robot has an embedded differential drive program that receive twist messages and publish back the raw odom. Any proven recipe ?

When i look at the tutorial i have a missing information, i do not see how the virtual position joint is "passing" commands to the differential drive.

Thanks