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Nav2

What is Nav2

Nav2, or the Navigation 2 Stack, is a powerful and flexible navigation framework for robots in the Robot Operating System 2 (ROS 2). It provides a modular set of tools and algorithms for autonomous robot navigation in complex environments.

Starting Nav2 from the Terminal

Here are the terminal commands for launching the Nav2 toolkit.

# Start robot or robot simulator in this case I wil use the turtlebot3
ros2 launch turtlebot3_gazebo turtlebot3_world.launch.py

ros2 launch nav2_bringup bringup_launch.py use_sim_time:=true map:=Desktop/maps/my_map.yaml
# Launch rviz2 and add the TF visualization and the map visualization
ros2 run rviz2 rviz2

Custom Nav2 Launch File

Here is a custom ROS 2 Launch file

nav2.launch.py
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from launch import LaunchDescription
import os
from ament_index_python import get_package_share_directory
from launch_ros.parameter_descriptions import ParameterValue
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import Node
from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription

def generate_launch_description():

    # Declare the arguments
    use_sim_time = LaunchConfiguration('use_sim_time', default='False')
    map = LaunchConfiguration('map')

    # Define RViz config path
    rviz_config_path = os.path.join(
        get_package_share_directory('locker98_tools_bringup'),
        'rviz', 'nav2_config.rviz'
    )

    # Include the bringup launch file
    bringup_launch_file = os.path.join(
        get_package_share_directory('nav2_bringup'),
        'launch', 'bringup_launch.py'
    )

    # Include the bringup launch file and pass arguments
    include_bringup = IncludeLaunchDescription(
        bringup_launch_file,
        launch_arguments={
            'use_sim_time': use_sim_time,
            'map': map
        }.items()
    )

    # RViz node
    rviz2_node = Node(
        package='rviz2',
        executable='rviz2',
        output='screen',
        arguments=['-d', rviz_config_path]
    )

    # Return LaunchDescription
    return LaunchDescription([
        DeclareLaunchArgument('use_sim_time', default_value='False', description='Use simulation time'),
        DeclareLaunchArgument('map', default_value='', description='Map input'),
        include_bringup,
        rviz2_node
    ])
nav2.launch.xml
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<launch>
    <!-- Declare Launch Arguments -->
    <arg name="use_sim_time" default="false" description="Use simulation time" />
    <arg name="map" default="" description="Map input" />

    <!-- Include bringup launch file -->
    <include file="$(find-pkg-share nav2_bringup)/launch/bringup_launch.py">
        <arg name="use_sim_time" value="$(var use_sim_time)" />
        <arg name="map" value="$(var map)" />
    </include>

    <!-- RViz node -->
    <node pkg="rviz2" exec="rviz2" output="screen">
        <param name="config" value="$(find-pkg-share locker98_tools_bringup)/rviz/nav2_config.rviz" />
    </node>
</launch>