Mobile robot moving around can not visualise in RVIZ, why so?

Question

I have a mobile robot that is able to visualise it in Rviz. But when the robot moves it doesn't show it in rviz, only shows the laser scans, but the robot model is static.The Lidar frame id is laser_link. Here is the URDF file:

<?xml version="1.0"?>
<robot name="sam_bot" xmlns:xacro="http://ros.org/wiki/xacro">

  <!-- Define robot constants -->
  <xacro:property name="base_width" value="0.31"/>
  <xacro:property name="base_length" value="0.42"/>
  <xacro:property name="base_height" value="0.18"/>

  <xacro:property name="wheel_radius" value="0.10"/>
  <xacro:property name="wheel_width" value="0.04"/>
  <xacro:property name="wheel_ygap" value="0.025"/>
  <xacro:property name="wheel_zoff" value="0.05"/>
  <xacro:property name="wheel_xoff" value="0.12"/>

  <xacro:property name="caster_xoff" value="0.14"/>

  <!-- Define some commonly used intertial properties  -->
  <xacro:macro name="box_inertia" params="m w h d">
    <inertial>
      <origin xyz="0 0 0" rpy="${pi/2} 0 ${pi/2}"/>      
      <mass value="${m}"/>
      <inertia ixx="${(m/12) * (h*h + d*d)}" ixy="0.0" ixz="0.0" iyy="${(m/12) * (w*w + d*d)}" iyz="0.0" izz="${(m/12) * (w*w + h*h)}"/>
    </inertial>
  </xacro:macro>

  <xacro:macro name="cylinder_inertia" params="m r h">
    <inertial>
      <origin xyz="0 0 0" rpy="${pi/2} 0 0" />      
      <mass value="${m}"/>
      <inertia ixx="${(m/12) * (3*r*r + h*h)}" ixy = "0" ixz = "0" iyy="${(m/12) * (3*r*r + h*h)}" iyz = "0" izz="${(m/2) * (r*r)}"/> 
    </inertial>
  </xacro:macro>

  <xacro:macro name="sphere_inertia" params="m r">
    <inertial>
      <mass value="${m}"/>
      <inertia ixx="${(2/5) * m * (r*r)}" ixy="0.0" ixz="0.0" iyy="${(2/5) * m * (r*r)}" iyz="0.0" izz="${(2/5) * m * (r*r)}"/>
    </inertial>
  </xacro:macro>
  
  <!-- Robot Base -->
  <link name="base_link">
    <visual>
      <geometry>
        <box size="${base_length} ${base_width} ${base_height}"/>
      </geometry>
      <material name="Cyan">
        <color rgba="0 1.0 1.0 1.0"/>
      </material>
    </visual>

    <collision>
      <geometry>
        <box size="${base_length} ${base_width} ${base_height}"/>
      </geometry>
    </collision>

    <xacro:box_inertia m="15" w="${base_width}" d="${base_length}" h="${base_height}"/>
  </link>
  
   <!-- Robot Footprint -->
  <link name="base_footprint">
    <xacro:box_inertia m="0" w="0" d="0" h="0"/>
  </link>

  <joint name="base_joint" type="fixed">
    <parent link="base_link"/>
    <child link="base_footprint"/>
    <origin xyz="0.0 0.0 ${-(wheel_radius+wheel_zoff)}" rpy="0 0 0"/>
  </joint>

  <!-- Wheels -->
  <xacro:macro name="wheel" params="prefix x_reflect y_reflect">
    <link name="${prefix}_link">
      <visual>
        <origin xyz="0 0 0" rpy="${pi/2} 0 0"/>
        <geometry>
            <cylinder radius="${wheel_radius}" length="${wheel_width}"/>
        </geometry>
        <material name="Gray">
          <color rgba="0.5 0.5 0.5 1.0"/>
        </material>
      </visual>

      <collision>
        <origin xyz="0 0 0" rpy="${pi/2} 0 0"/> 
        <geometry>
          <cylinder radius="${wheel_radius}" length="${wheel_width}"/>
        </geometry>
      </collision>

      <xacro:cylinder_inertia m="0.5" r="${wheel_radius}" h="${wheel_width}"/>
    </link>

    <joint name="${prefix}_joint" type="continuous">
      <parent link="base_link"/>
      <child link="${prefix}_link"/>
      <origin xyz="${x_reflect*wheel_xoff} ${y_reflect*(base_width/2+wheel_ygap)} ${-wheel_zoff}" rpy="0 0 0"/>
      <axis xyz="0 1 0"/>
    </joint>
  </xacro:macro>

  <xacro:wheel prefix="drivewhl_l" x_reflect="-1" y_reflect="1" />
  <xacro:wheel prefix="drivewhl_r" x_reflect="-1" y_reflect="-1" />

  <link name="front_caster">
    <visual>
      <geometry>
        <sphere radius="${(wheel_radius+wheel_zoff-(base_height/2))}"/>
      </geometry>
      <material name="Cyan">
        <color rgba="0 1.0 1.0 1.0"/>
      </material>
    </visual>

    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <sphere radius="${(wheel_radius+wheel_zoff-(base_height/2))}"/>
      </geometry>
    </collision>

    <xacro:sphere_inertia m="0.5" r="${(wheel_radius+wheel_zoff-(base_height/2))}"/>
  </link>

  <joint name="caster_joint" type="fixed">
    <parent link="base_link"/>
    <child link="front_caster"/>
    <origin xyz="${caster_xoff} 0.0 ${-(base_height/2)}" rpy="0 0 0"/>
  </joint>

  
  <gazebo>
    <plugin name='diff_drive' filename='libgazebo_ros_diff_drive.so'>
      <ros>
        <namespace>/demo</namespace>
      </ros>

      <!-- wheels -->
      <left_joint>drivewhl_l_joint</left_joint>
      <right_joint>drivewhl_r_joint</right_joint>

      <!-- kinematics -->
      <wheel_separation>0.4</wheel_separation>
      <wheel_diameter>0.2</wheel_diameter>

      <!-- limits -->   
      <max_wheel_torque>20</max_wheel_torque>
      <max_wheel_acceleration>1.0</max_wheel_acceleration>

      <!-- output -->
      <publish_odom>true</publish_odom>
      <publish_odom_tf>false</publish_odom_tf>
      <publish_wheel_tf>true</publish_wheel_tf>

      <odometry_frame>odom</odometry_frame>
      <robot_base_frame>base_link</robot_base_frame>
    </plugin>
  </gazebo>

 <link name="laser_link">
    <inertial>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <mass value="0.125"/>
      <inertia ixx="0.001"  ixy="0"  ixz="0" iyy="0.001" iyz="0" izz="0.001" />
    </inertial>

    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
         <cylinder radius="0.0508" length="0.055"/>
      </geometry>
    </collision>

    <visual>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
         <cylinder radius="0.0508" length="0.055"/>
      </geometry>
    </visual>
  </link>
    
  <joint name="lidar_joint" type="fixed">
    <parent link="base_link"/>
    <child link="laser_link"/>
    <origin xyz="0 0 0.12" rpy="0 0 0"/>
  </joint>
    
  <gazebo reference="lidar_link">
    <sensor name="lidar" type="ray">
      <always_on>true</always_on>
      <visualize>true</visualize>
      <update_rate>5</update_rate>
      <ray>
        <scan>
          <horizontal>
            <samples>360</samples>
            <resolution>1.000000</resolution>
            <min_angle>0.000000</min_angle>
            <max_angle>6.280000</max_angle>
          </horizontal>
        </scan>
        <range>
          <min>0.120000</min>
          <max>3.5</max>
          <resolution>0.015000</resolution>
        </range>
        <noise>
          <type>gaussian</type>
          <mean>0.0</mean>
          <stddev>0.01</stddev>
        </noise>
      </ray>
      <plugin name="scan" filename="libgazebo_ros_ray_sensor.so">
        <ros>
          <remapping>~/out:=scan</remapping>
        </ros>
        <output_type>sensor_msgs/LaserScan</output_type>
        <frame_name>lidar_link</frame_name>
      </plugin>
    </sensor>
  </gazebo>
  </robot>

And here is the 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='amr_bot').find('amr_bot')
    default_model_path = os.path.join(pkg_share, 'src/description/amr_bot_description.urdf')
    default_rviz_config_path = os.path.join(pkg_share, 'rviz/urdf_config.rviz')
    world_path=os.path.join(pkg_share, 'world/my_world.sdf')
    
    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',
        condition=launch.conditions.UnlessCondition(LaunchConfiguration('gui'))
    )
    rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        name='rviz2',
        output='screen',
        arguments=['-d', LaunchConfiguration('rvizconfig')],
    )
    spawn_entity = launch_ros.actions.Node(
        package='gazebo_ros', 
        executable='spawn_entity.py',
        arguments=['-entity', 'amr_bot', '-topic', 'robot_description'],
        output='screen'
    )
    robot_localization_node = launch_ros.actions.Node(
         package='robot_localization',
         executable='ekf_node',
         name='ekf_filter_node',
         output='screen',
         parameters=[os.path.join(pkg_share, 'config/ekf.yaml'), {'use_sim_time': LaunchConfiguration('use_sim_time')}]
    )

    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'),
        launch.actions.DeclareLaunchArgument(name='use_sim_time', default_value='True',
                                            description='Flag to enable use_sim_time'),
        launch.actions.ExecuteProcess(cmd=['gazebo', '--verbose', '-s', 'libgazebo_ros_init.so', '-s', 'libgazebo_ros_factory.so', world_path], output='screen'),
        joint_state_publisher_node,
        robot_state_publisher_node,
        spawn_entity,
        robot_localization_node,
        rviz_node
    ])

This is the frames three

And this is RVIZ . Can anyone help show the robot moving around in RVIZ?

Answer 1

In RVIZ, you can select the 'fixed_frame', which is the frame that is fixed on the screen. You selected 'laser_link', and by that fixed the robot in the visualization. You should set it to 'odom' in your setup, and later to 'world', if you run slam and have the standard world->odom->base_link.