GZ Migration Notes (#42)

* Added first version of migration notes

ur_simulation_gz/doc/migration/jazzy.rst

@@ -0,0 +1,35 @@
+ur_simulation_gz
+^^^^^^^^^^^^^^^^
+
+Updated argument name for tf_prefix
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To have coherency between the driver and the GZ simulation, the launch argument to use tf_prefix has been changed from ``prefix`` to ``tf_prefix``. Moreover, differently from the driver, using such argument for this package requires the user to also provide their own controllers file, as explained in :ref:`tf_prefix for GZ <tf_prefix_gz>`.
+
+Update arguments for MoveIt!
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+As part of the restructuring of the ``ur_moveit_config`` pkg, all the arguments that were previously passed to ``ur_moveit.launch.py`` (e.g. ``description_file``, ``safety_limits`` or ``prefix``) have been removed, in favor of the only ``moveit_launch_file`` argument.
+
+This is due to the underlying assumption for the specified launch file to be part of a custom moveit_config pkg that already contains the correct references to a custom description pkg and related parameters.
+
+In particular, the
+option of specifying a ``tf_prefix`` for the ``ur_moveit_config`` has been removed, hence if it is needed in a GZ simulation with MoveIt!, it is expected to be handled by the user through a proper definition for it in a custom moveit_config.
+
+Enforce absolute paths in launchfiles
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+All launchfiles now expect an absolute path for files that should be used to alter the launch
+process (e.g. description file, controllers file). Before it was expecting e.g. a
+``description_package`` and a ``description_file`` argument with a relative path to the package.
+
+The default files have not been changed, so unless you specified your custom package / file
+combinations, you won't need to update that to an absolute path.
+
+Absolute paths can still be generated dynamically using a package + relative path structure inside
+other launchfiles or by using ``ros2 pkg prefix`` on the command line. For example, you can do
+
+.. code-block:: console
+
+   $ ros2 launch ur_gz_simulation ur_sim_control.launch.py ur_type:=ur20 \
+     controllers_file:=$(ros2 pkg prefix my_robot_cell_control)/share/my_robot_cell_control/config/ros2_controllers.yaml

ur_simulation_gz/doc/usage.rst

@@ -51,6 +51,8 @@ To use a custom robot / scene description, the launch argument ``description_fil
 
    $ ros2 launch ur_simulation_gz ur_sim_control.launch.py ur_type:=ur10e description_file:="/home/ubuntu/ur_gz_test.urdf.xacro" rviz_config_file:="/home/ubuntu/rviz_test.rviz"
 
+.. _tf_prefix_gz:
+
 tf_prefix
 ^^^^^^^^^