.. its-customization:

ITS Path Planner Plugin Customization
----------------------------------------

The |ros| navigation bring-up application is started using the TurtleBot* 3 Gazebo*
simulation, and it receives as input parameter its_nav2_params.yaml.

To use the ITS path planner plugin, the following parameters are added in
its_nav2_params.yaml:

.. code-block::

   planner_server:
     ros__parameters:
       expected_planner_frequency: 0.01
       use_sim_time: True
       planner_plugins: ["GridBased"]
       GridBased:
         plugin: "its_planner/ITSPlanner"
         interpolation_resolution: 0.05
         catmull_spline: False
         smoothing_window: 15
         buffer_size: 10
         build_road_map_once: True
         min_samples: 250
         roadmap: "PROBABLISTIC"
         w: 32
         h: 32
         n: 2

ITS Path Planner Plugin Parameters
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. code-block::

   catmull_spline:


If true, the generated path from the ITS is interpolated with the catmull
spline method; otherwise, a smoothing filter is used to smooth the path.

.. code-block::

   smoothing_window:

The window size for the smoothing filter (The unit is the grid size.)

.. code-block::

   buffer_size:

During roadmap generation, the samples are generated away from obstacles. The
buffer size dictates how far away from obstacles the roadmap samples should be.

.. code-block::

   build_road_map_once:

If true, the roadmap is loaded from the saved file; otherwise, a new roadmap
is generated.

.. code-block::

   min_samples:

The minimum number of samples required to generate the roadmap

.. code-block::

   roadmap:

Either PROBABILISTIC or DETERMINISTIC

.. code-block::

   w:

The width of the window for intelligent sampling

.. code-block::

   h:

The height of the window for intelligent sampling

.. code-block::

   n:

The minimum number of samples that is required in an area defined by ``w`` and
``h``


You can modify these values by editing the file below for the default ITS planner, at lines 274-291:

.. code-block::

   /opt/ros/humble/share/its_planner/nav2_params.yaml

You can modify these values by editing the file below for the Ackermann ITS planner, at lines 274-296:

.. code-block::

   /opt/ros/humble/share/its_planner/nav2_params_dubins.yaml