Original guide for reference: https://docs.visualnav2.org/cansetup_guides/urdf/setup_urdf.html

TODO: add rqt graphs for each time we add a node for the Nav2 Stack series

install pkg

creating workspace + package 

  mkdir -p mbot_ws/src
cd mbot_ws/src
ros2 pkg create --build-type ament_python --license Apache-2.0 mbot_pkg

building 

  cd ../../ # you should be in the mbot_ws folder after running this
colcon build --symlink-install  
source install/setup.bash

Download

create rviz and urdf folder in mbot_pkg and download the rviz and urdf file:

image.png

urdf file:

mbot_description.urdf

rviz file:

urdf_config.rviz

Core design

TODO: explain map→odom→base_link→sensor…p

Just robot_state_publisher and joint_state_publisher_gui run the whole show

image.png

(From Articulated Robotics)

creating launch file

make a launch folder called display.launch.py

Nodes we are adding:

  • robot_state_publisher_node (reads the URDF and publishes to /robot_description all non-fixed joints, static joints and links)
  • joint_state_publisher_node (finds all of the non-fixed joints and publishes to /joint_states)
  • joint_state_publisher_gui_node (the same as joint_state_publisher_node but with a gui on top)
  • rviz_node

launch file 

  import launch
from launch.substitutions import Command, LaunchConfiguration
import launch_ros
import os

def generate_launch_description():
    pkg_share = launch_ros.substitutions.FindPackageShare(package='mbot_pkg').find('mbot_pkg')
    default_model_path = os.path.join(pkg_share, 'urdf/mbot_description.urdf')
    default_rviz_config_path = os.path.join(pkg_share, 'rviz/urdf_config.rviz')

    robot_state_publisher_node = launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description': Command(['xacro ', LaunchConfiguration('model')])}]
    )
    joint_state_publisher_node = launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher',
        name='joint_state_publisher',
        parameters=[{'robot_description': Command(['xacro ', default_model_path])}],
        condition=launch.conditions.UnlessCondition(LaunchConfiguration('gui'))
    )
    joint_state_publisher_gui_node = launch_ros.actions.Node(
        package='joint_state_publisher_gui',
        executable='joint_state_publisher_gui',
        name='joint_state_publisher_gui',
        condition=launch.conditions.IfCondition(LaunchConfiguration('gui'))
    )
    rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        name='rviz2',
        output='screen',
        arguments=['-d', LaunchConfiguration('rvizconfig')],
    )

    return launch.LaunchDescription([
        launch.actions.DeclareLaunchArgument(name='gui', default_value='True',
                                            description='Flag to enable joint_state_publisher_gui'),
        launch.actions.DeclareLaunchArgument(name='model', default_value=default_model_path,
                                            description='Absolute path to robot urdf file'),
        launch.actions.DeclareLaunchArgument(name='rvizconfig', default_value=default_rviz_config_path,
                                            description='Absolute path to rviz config file'),
        joint_state_publisher_node,
        joint_state_publisher_gui_node,
        robot_state_publisher_node,
        rviz_node
    ])

add new files to setup.py 

  import os
from glob import glob

from setuptools import find_packages, setup

package_name = 'mbot_code'

setup(
    name=package_name,
    version='0.0.0',
    packages=find_packages(exclude=['test']),
    data_files=[
        ('share/ament_index/resource_index/packages',
            ['resource/' + package_name]),
        ('share/' + package_name, ['package.xml']),
        (os.path.join('share', package_name, 'urdf'), glob('urdf/*.urdf')),
        (os.path.join('share', package_name, 'rviz'), glob('rviz/*.rviz*')),
        (os.path.join('share', package_name), glob('launch/*launch.[pxy][yma]*')),
    ],
    ...

run:

  colcon build --symlink-install
ros2 launch mbot_pkg display.launch.py

image.png

Adding collision

image.png