How to launch the Nav2 stack

In this article, we will demonstrate how to launch the Nav2 with default setup. To launch the stack, we have the following prerequisites:

• a map: This map is used to construct the static layer of the cost map. We can build and save a map with slam_toolbox package. Note that slam_toolbox support different map format but nav2 uses the yaml file.

• a nav2 parameter file: This is the configuration file of the nav2 stack. It might be overwhelming to create a configuration file from scratch as it contains many parameters. Instead, we can use this file in the navigation2 package as the blueprint.

Param Name	Default Value	Description
namespace	(empty)	Top-level namespace
use_sim_time	false	Use simulation (Gazebo) clock if true
params_file	os.path.join(bringup_dir, 'params', 'nav2_params.yaml')	Full path to the ROS2 parameters file to use for all launched nodes
autostart	true	Automatically startup the nav2 stack
use_composition	False	Use composed bringup if True
container_name	nav2_container	The name of container that nodes will load in if use composition
use_respawn	False	Whether to respawn if a node crashes. Applied when composition is disabled.
log_level	info	Log level

Let's edit the nav2 stack configuration (knowns as params file). Each section in the file corresponds to a component in the nav2 stack. The details of those parameters can be found in the Nav2 Configuration Guide.

We will put some emphasis on the namespae.

The end goal is to have

• topic with proper namespace

• frame with proper namespace

• node with proper namespace

• service with proper namespace