Unit 3: Warning: Invalid frame ID "right_wheel" passed to canTransform argument source_frame - frame does not exist

[neilthomas110]

I keep getting this error

[rviz2-2] Warning: Invalid frame ID "left_wheel" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "right_wheel" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "back_pitch_link" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "back_roll_link" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "back_yaw_link" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "front_pitch_link" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "front_roll_link" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "front_yaw_link" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "left_wheel" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "right_wheel" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "back_pitch_link" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "back_roll_link" passed to canTransform argument source_frame - frame does not exist
[rviz2-2]          at line 156 in /tmp/binarydeb/ros-galactic-tf2-0.17.2/src/buffer_core.cpp
[rviz2-2] Warning: Invalid frame ID "back_yaw_link" passed to canTransform argument source_frame - frame does not exist

this is my box_bot_geometric.urdf

<?xml version="1.0"?>
<robot name="box_bot">

  <material name="red">
      <color rgba="1.0 0.0 0.0 1"/>
  </material>

  <material name="green_light">
      <color rgba="0.0 1.0 0.0 1"/>
  </material>

  <material name="green_dark">
    <color rgba="0.0 0.5 0.0 1"/>
  </material>

  <material name="blue">
      <color rgba="0.0 0.0 1.0 1"/>
  </material>

  <material name="black">
      <color rgba="0.0 0.0 0.0 1"/>
  </material>

  <material name="white">
      <color rgba="1.0 1.0 1.0 1"/>
  </material>

  <material name="box_bot_blue">
      <color rgba="0.088656 0.428691 0.491021 1"/>
  </material>

  <link name="base_link">
  </link>


  <!-- Body -->
  <link name="chassis">
    <visual>
      <geometry>
        <box size="0.1 0.1 0.1"/>
      </geometry>
      <material name="box_bot_blue"/>
    </visual>
  </link>

  <joint name="base_link_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0 0 0" />
    <parent link="base_link" />
    <child link="chassis" />
  </joint>

  <!-- Wheel Left -->
  <link name="left_wheel">      
      <visual>
        <origin rpy="0 1.5707 1.5707" xyz="0 0 0"/>
        <geometry>
          <cylinder length="0.001" radius="0.035"/>
        </geometry>
        <material name="black"/>
      </visual>
  </link>

  <joint name="joint_left_wheel" type="continuous">
    <origin rpy="0 0 0" xyz="0 0.05 -0.025"/>
    <parent link="chassis"/>
    <child link="left_wheel"/>
    <axis rpy="0 0 0" xyz="0 1 0"/>
    <limit effort="10000" velocity="1000"/>
    <joint_properties damping="1.0" friction="1.0"/>
  </joint>

  <!-- Wheel Right -->
  <link name="right_wheel">      
      <visual>
        <origin rpy="0 1.5707 1.5707" xyz="0 0 0"/>
        <geometry>
          <cylinder length="0.001" radius="0.035"/>
        </geometry>
        <material name="white"/>
      </visual>
  </link>

  <joint name="joint_right_wheel" type="continuous">  
    <origin rpy="0 0 0" xyz="0 -0.05 -0.025"/>
    <parent link="chassis"/>
    <child link="right_wheel"/>
    <axis rpy="0 0 0" xyz="0 1 0"/>
    <limit effort="10000" velocity="1000"/>
    <joint_properties damping="1.0" friction="1.0"/>
  </joint>


  <!-- Caster Wheel Front -->
  <link name="front_yaw_link">
    <visual>
        <origin rpy="0 1.5707 1.5707" xyz="0 0 0"/>
        <geometry>
          <cylinder length="0.005" radius="0.010"/>
        </geometry>
        <material name="blue"/>
      </visual>
  </link>

  <joint name="front_yaw_joint" type="continuous">
    <origin rpy="0 0 0" xyz="0.04 0 -0.05" />
    <parent link="chassis" />
    <child link="front_yaw_link" />
    <axis xyz="0 0 1" />
    <limit effort="1000.0" velocity="100.0" />
    <dynamics damping="0.0" friction="0.1"/>
  </joint>



  <link name="front_roll_link">
      <visual>
        <origin rpy="0 1.5707 1.5707" xyz="0 0 0"/>
        <geometry>
          <cylinder length="0.005" radius="0.010"/>
        </geometry>
        <material name="red"/>
      </visual>
  </link>

  <joint name="front_roll_joint" type="continuous">
    <origin rpy="0 0 0" xyz="0 0 0" />
    <parent link="front_yaw_link" />
    <child link="front_roll_link" />
    <axis xyz="1 0 0" />
    <limit effort="1000.0" velocity="100.0" />
    <dynamics damping="0.0" friction="0.1"/>
  </joint>



  <link name="front_pitch_link">
    <visual>
      <origin rpy="0 1.5707 1.5707" xyz="0 0 0"/>
      <geometry>
        <sphere radius="0.010"/>
      </geometry>
      <material name="green_dark"/>
    </visual>
  </link>

  <joint name="front_pitch_joint" type="continuous">
    <origin rpy="0 0 0" xyz="0 0 0" />
    <parent link="front_roll_link" />
    <child link="front_pitch_link" />
    <axis xyz="0 1 0" />
    <limit effort="1000.0" velocity="100.0" />
    <dynamics damping="0.0" friction="0.1"/>
  </joint>

<!-- Caster Wheel Back -->
  <link name="back_yaw_link">
    <visual>
        <origin rpy="0 1.5707 1.5707" xyz="0 0 0"/>
        <geometry>
          <cylinder length="0.005" radius="0.010"/>
        </geometry>
        <material name="blue"/>
      </visual>
  </link>

  <joint name="back_yaw_joint" type="continuous">
    <origin rpy="0 0 0" xyz="-0.04 0 -0.05" />
    <parent link="chassis" />
    <child link="back_yaw_link" />
    <axis xyz="0 0 1" />
    <limit effort="1000.0" velocity="100.0" />
    <dynamics damping="0.0" friction="0.1"/>
  </joint>



  <link name="back_roll_link">
      <visual>
        <origin rpy="0 1.5707 1.5707" xyz="0 0 0"/>
        <geometry>
          <cylinder length="0.005" radius="0.010"/>
        </geometry>
        <material name="red"/>
      </visual>
  </link>

  <joint name="back_roll_joint" type="continuous">
    <origin rpy="0 0 0" xyz="0 0 0" />
    <parent link="back_yaw_link" />
    <child link="back_roll_link" />
    <axis xyz="1 0 0" />
    <limit effort="1000.0" velocity="100.0" />
    <dynamics damping="0.0" friction="0.1"/>
  </joint>



  <link name="back_pitch_link">
    <visual>
      <origin rpy="0 1.5707 1.5707" xyz="0 0 0"/>
      <geometry>
        <sphere radius="0.010"/>
      </geometry>
      <material name="green_light"/>
    </visual>
  </link>

  <joint name="back_pitch_joint" type="continuous">
    <origin rpy="0 0 0" xyz="0 0 0" />
    <parent link="back_roll_link" />
    <child link="back_pitch_link" />
    <axis xyz="0 1 0" />
    <limit effort="1000.0" velocity="100.0" />
    <dynamics damping="0.0" friction="0.1"/>
  </joint>
</robot>

my launch file

import os

from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.substitutions import Command
from launch_ros.actions import Node

# this is the function launch  system will look for
def generate_launch_description():

    ####### DATA INPUT ##########
    urdf_file = 'box_bot_geometric.urdf'
    #xacro_file = "box_bot.xacro"
    package_description = "my_box_bot_description"

    ####### DATA INPUT END ##########
    print("Fetching URDF ==>")
    robot_desc_path = os.path.join(get_package_share_directory(package_description), "urdf", urdf_file)

    # Robot State Publisher

    robot_state_publisher_node = Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        name='robot_state_publisher_node',
        emulate_tty=True,
        parameters=[{'use_sim_time': True, 'robot_description': Command(['xacro ', robot_desc_path])}],
        output="screen"
    )

    # RVIZ Configuration
    rviz_config_dir = os.path.join(get_package_share_directory(package_description), 'rviz', 'urdf_vis.rviz')


    rviz_node = Node(
            package='rviz2',
            executable='rviz2',
            output='screen',
            name='rviz_node',
            parameters=[{'use_sim_time': True}],
            arguments=['-d', rviz_config_dir])

    # create and return launch description object
    return LaunchDescription(
        [            
            robot_state_publisher_node,
            rviz_node
        ]
    )

I even checked rqt_tf_tree and all I could see was base_link being connected to chassis. I am unable to understand why other components are not showing up. I have checked parent and child names but still couldn’t solve this error.

[roalgoal]

Hi @neilthomas110 this is probably because the robot_state_publisher isn’t parsing your URDF correctly.

I think the issue is that you are trying to use the command xacro to parse a URDF file, which is redundant (i.e. your file is box_bot_geometric.urdf instead of box_bot_geometric.xacro).

So instead of

parameters=[{'use_sim_time': True, 'robot_description': Command(['xacro ', robot_desc_path])}],

try

parameters=[{'use_sim_time': True, 'robot_description': robot_desc_path}],

[neilthomas110]

I did make the suggested change to my launch file and this time it is even unable to find a base_link. Nothing shows up on rqt_tf_tree.

Below is the change I made.

import os
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.substitutions import Command
from launch_ros.actions import Node

# this is the function launch  system will look for
def generate_launch_description():

    ####### DATA INPUT ##########
    urdf_file = 'box_bot_geometric.urdf'
    #xacro_file = "box_bot.xacro"
    package_description = "my_box_bot_description"

    ####### DATA INPUT END ##########
    print("Fetching URDF ==>")
    robot_desc_path = os.path.join(get_package_share_directory(package_description), "urdf", urdf_file)

    # Robot State Publisher

    robot_state_publisher_node = Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        name='robot_state_publisher_node',
        emulate_tty=True,
        parameters=[{'use_sim_time': True, 'robot_description': robot_desc_path}],
        output="screen"
    )

    # RVIZ Configuration
    rviz_config_dir = os.path.join(get_package_share_directory(package_description), 'rviz', 'urdf_vis.rviz')


    rviz_node = Node(
            package='rviz2',
            executable='rviz2',
            output='screen',
            name='rviz_node',
            parameters=[{'use_sim_time': True}],
            arguments=['-d', rviz_config_dir])

    # create and return launch description object
    return LaunchDescription(
        [            
            robot_state_publisher_node,
            rviz_node
        ]
    )

[duckfrost2]

Hi,

I just tested your code, the first one you placed in this issue and it works.
The only thing is that you have to launch in a second terminal the

ros2 run joint_state_publisher_gui joint_state_publisher_gui

The reason is what we explained in the course that the joints that are NOT fixed, because their transform depends on the value of the angle of the joint that moves them, until the system has a value of that joint, NO transform will be published, because its impossible to generate a TF without knowing that.

So when you launch the rviz, we are only publishing the robot description with the robot_state publisher and opening RVIZ2. You need something that publishes at least fake values of those joints to trigger the publishing of the TFs of all the links connected to mobile joints (non-fixed joints ).

When you start the simulation in the gazebo this will not be necessary because you have controllers that publish the values of those joints, the real values.

I hope this clears things up