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I'm simulating a robot with 4 omnidirectional wheels and I'm using the planar move plugin in the gazebo to simulate the behavior of the omnidirectional wheels.

To simulate the wheels I was using continuous joints however with this plugin in rviz2 and with the fixed frame in odom, the wheels do not move with the robot. Although if I'm using a fixed joint and controlling the robot with teleop_twist_keyboard the wheels move together with the robot.

Is this a plugin problem or am I missing something to declare?

Follows URDF code to create the robot.

robot_core:

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

    <xacro:include filename="inertial_macros.xacro"/>
    <xacro:include filename="gazebo_control.xacro" />

    <material name="white">
        <color rgba="1 1 1 1"/>
    </material>
    <material name="blue">
        <color rgba="0.2 0.2 1 1"/>
    </material>
    <material name="black">
        <color rgba="0 0 0 1"/>
    </material>
    <material name="red">
        <color rgba="1 0 0 1"/>
    </material>

    <!--BASE LINK-->
    <link name="base_link">
    </link>

    <!--CHASSI-->
    <joint name="chassi_joint" type="fixed">
        <parent link="base_link"/>
        <child link="chassi_link"/>
        <origin xyz="0 0 0"/> <!--VIRADO PARA X-->
        <!--<origin xyz="0 0 0" rpy="0 0 ${pi/2}"/> VIRADO PARA Y-->
    </joint>

    <link name="chassi_link">
        <visual>
            <origin xyz="0 0 0.085"/>
            <geometry>
                <cylinder radius="0.275" length="0.17"/>
            </geometry>
            <material name="white"/>
        </visual>
        <collision>
            <origin xyz="0 0 0.085"/>
            <geometry>
                <cylinder radius="0.275" length="0.17"/>
            </geometry>
        </collision>
        <xacro:inertial_cylinder mass="0.1" length="0.17" radius="0.275">
            <origin xyz="0 0 0.085" rpy="0 0 0"/>
        </xacro:inertial_cylinder>
    </link>

    <gazebo reference="chassi_link">
        <material>Gazebo/White</material>
    </gazebo>

    <!--BODY-->
    <joint name="body_joint" type="fixed">
        <parent link="chassi_link"/>
        <child link="body_link"/>
        <origin xyz="-0.1 0 0.18" rpy="0 0 0"/>
    </joint>

    <link name="body_link">
        <visual>
            <origin xyz="0 0 0.55" rpy="0 0 ${pi/2}"/>
        <geometry>
            <box size="0.2 0.05 1.1"/>
        </geometry>
        <material name="white"/>
    </visual>
    <collision>
        <origin xyz="0 0 0.55" rpy="0 0 ${pi/2}"/>
            <geometry>
                <box size="0.2 0.05 1.1"/>
            </geometry>
        </collision>
        <xacro:inertial_box mass="0.1" x="0.2" y="0.05" z="1.1">
            <origin xyz="0 0 0.55" rpy="0 0 0"/>
        </xacro:inertial_box>
    </link>

    <gazebo reference="body_link">
        <material>Gazebo/White</material>
    </gazebo>

    <!--WHEELS-->

    <!--LEFT FRONT-->
    <joint name="left_front_joint" type="fixed">
        <parent link="chassi_link"/>
        <child link="left_front_link"/>
        <origin xyz="0.2 0.2 0" rpy="-${pi/2} 0 -${pi/4}"/>
        <!--<axis xyz="0 0 1"/>-->
    </joint>

    <link name="left_front_link">
        <visual>
            <geometry>
                <cylinder radius="0.1" length="0.04"/>
            </geometry>
            <material name="blue"/>
        </visual>
        <collision>
            <geometry>
                <cylinder radius="0.1" length="0.04"/>
            </geometry>
        </collision>
        <xacro:inertial_cylinder mass="0.1" length="0.04" radius="0.1">
            <origin xyz="0 0 0" rpy="0 0 0"/>
        </xacro:inertial_cylinder>
    </link>

    <gazebo reference="left_front_link">
        <material>Gazebo/Blue</material>
        <mu1 value="0.001"/>
        <mu2 value="0.001"/>
    </gazebo>

    <!--LEFT BACK-->
    <joint name="left_back_joint" type="fixed">
        <parent link="chassi_link"/>
        <child link="left_back_link"/>
        <origin xyz="-0.2 0.2 0" rpy="0 -${pi/2} -${pi/4}"/>
        <!--<axis xyz="0 0 1"/>-->
    </joint>

    <link name="left_back_link">
        <visual>
            <geometry>
                <cylinder radius="0.1" length="0.04"/>
            </geometry>
            <material name="black"/>
        </visual>
        <collision>
            <geometry>
                <cylinder radius="0.1" length="0.04"/>
            </geometry>
        </collision>
        <xacro:inertial_cylinder mass="0.1" length="0.04" radius="0.1">
            <origin xyz="0 0 0" rpy="0 0 0"/>
        </xacro:inertial_cylinder>
    </link>

    <gazebo reference="left_back_link">
        <material>Gazebo/Black</material>
        <mu1 value="0.001"/>
        <mu2 value="0.001"/>
    </gazebo>

    <!--RIGHT FRONT-->
    <joint name="right_front_joint" type="fixed">
        <parent link="chassi_link"/>
        <child link="right_front_link"/>
        <origin xyz="0.2 -0.2 0" rpy="0 ${pi/2} -${pi/4}"/>
        <!--<axis xyz="0 0 -1"/>-->
    </joint>

    <link name="right_front_link">
        <visual>
            <geometry>
                <cylinder radius="0.1" length="0.04"/>
            </geometry>
            <material name="blue"/>
        </visual>
        <collision>
            <geometry>
                <cylinder radius="0.1" length="0.04"/>
            </geometry>
        </collision>
        <xacro:inertial_cylinder mass="0.1" length="0.04" radius="0.1">
            <origin xyz="0 0 0" rpy="0 0 0"/>
        </xacro:inertial_cylinder>
    </link>

    <gazebo reference="right_front_link">
        <material>Gazebo/Blue</material>
        <mu1 value="0.001"/>
        <mu2 value="0.001"/>
    </gazebo>

    <!--RIGHT BACK-->
    <joint name="right_back_joint" type="fixed">
        <parent link="chassi_link"/>
        <child link="right_back_link"/>
        <origin xyz="-0.2 -0.2 0" rpy="${pi/2} 0 -${pi/4}"/>
        <!--<axis xyz="0 0 -1"/>-->
    </joint>

    <link name="right_back_link">
        <visual>
            <geometry>
                <cylinder radius="0.1" length="0.04"/>
            </geometry>
            <material name="black"/>
        </visual>
        <collision>
            <geometry>
                <cylinder radius="0.1" length="0.04"/>
            </geometry>
        </collision>
        <xacro:inertial_cylinder mass="0.1" length="0.04" radius="0.1">
            <origin xyz="0 0 0" rpy="0 0 0"/>
        </xacro:inertial_cylinder>
    </link>

    <gazebo reference="right_back_link">
        <material>Gazebo/Black</material>
        <mu1 value="0.001"/>
        <mu2 value="0.001"/>
    </gazebo>
    
    <xacro:omni_steering/>

</robot>

gazebo_control:

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

    <xacro:macro name="omni_steering" params="">
        <gazebo>

             <plugin name="omni_steering" filename="libgazebo_ros_planar_move.so">
                <commandTopic>cmd_vel</commandTopic>
                <odometry_rate>50.0</odometry_rate>                
                <odometry_frame>odom</odometry_frame>
                <robot_base_frame>base_link</robot_base_frame>

                <publish_odom>true</publish_odom>
                <publish_odom_tf>true</publish_odom_tf>
                <publish_wheel_tf>true</publish_wheel_tf>
            </plugin>

        </gazebo>
  </xacro:macro>

</robot>

robot_xacro:

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

    <xacro:include filename="robot_core.xacro" />

</robot>

rsp.launch.py:

import os

from ament_index_python.packages import get_package_share_directory

from launch import LaunchDescription from launch.substitutions import LaunchConfiguration from launch.actions import DeclareLaunchArgument from launch_ros.actions import Node

import xacro

def generate_launch_description():

# Check if we're told to use sim time
use_sim_time = LaunchConfiguration('use_sim_time')

# Process the URDF file
pkg_path = os.path.join(get_package_share_directory('charmie_bot'))
xacro_file = os.path.join(pkg_path,'description','robot.urdf.xacro')
robot_description_config = xacro.process_file(xacro_file)
    
# Create a robot_state_publisher node
params = {'robot_description': robot_description_config.toxml(), 'use_sim_time': use_sim_time}
node_robot_state_publisher = Node(
    package='robot_state_publisher',
    executable='robot_state_publisher',
    output='screen',
    parameters=[params]
)

# Launch!
return LaunchDescription([
    DeclareLaunchArgument(
        'use_sim_time',
        default_value='false',
        description='Use sim time if true'),
    node_robot_state_publisher
])

launch_sim.launch.py:

import os

from ament_index_python.packages import get_package_share_directory

from launch import LaunchDescription from launch.actions import IncludeLaunchDescription from launch.launch_description_sources import PythonLaunchDescriptionSource

from launch_ros.actions import Node

def generate_launch_description():

package_name='charmie_bot' #<--- CHANGE ME

rsp = IncludeLaunchDescription(
            PythonLaunchDescriptionSource([os.path.join(
                get_package_share_directory(package_name),'launch','rsp.launch.py'
            )]), launch_arguments={'use_sim_time': 'true'}.items()
)

 # Include the Gazebo launch file, provided by the gazebo_ros package
gazebo = IncludeLaunchDescription(
            PythonLaunchDescriptionSource([os.path.join(
                get_package_share_directory('gazebo_ros'), 'launch', 'gazebo.launch.py')]),
        )

# Run the spawner node from the gazebo_ros package. The entity name doesn't really matter if you only have a single robot.
spawn_entity = Node(package='gazebo_ros', executable='spawn_entity.py',
                    arguments=['-topic', 'robot_description',
                               '-entity', 'my_bot'],
                    output='screen')


# Launch them all!
return LaunchDescription([
    rsp,
    gazebo,
    spawn_entity
])
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1 Answer 1

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This usually happens when you do not set the use_sim_time parameter as True in the simulation.
Attached below is the launch file I used to run rviz2 with your robot with the set parameters: ​

#! /usr/bin/env python3
"""Spawn Robot in RViz2."""
​
import os
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.substitutions import LaunchConfiguration, Command
from launch.actions import DeclareLaunchArgument
from launch_ros.actions import Node
​
​
def generate_launch_description():
    """Launch Function."""
    pkg_dir = get_package_share_directory('your_ros2_pkg')
    rviz_config = os.path.join(pkg_dir, 'config', 'rviz', 'urdf.rviz')
​
    return LaunchDescription([
        # Launch Arguments
        DeclareLaunchArgument("rviz_config",
                              default_value=rviz_config,
                              description="RViz Config"),
​
        # Nodes
        Node(
            package='joint_state_publisher',
            executable='joint_state_publisher',
            name='joint_state_publisher',
            output='screen',
            parameters=[{'use_sim_time': True}],
        ),
​
        Node(
            package='robot_state_publisher',
            executable='robot_state_publisher',
            parameters=[
                {'use_sim_time': True},
                {'robot_description': Command(
                    ['xacro ', os.path.join(pkg_dir, 'urdf/robot.xacro')])}
                ]
        ),
​
        Node(
            package='rviz2',
            executable='rviz2',
            output='screen',
            arguments=['-d', LaunchConfiguration("rviz_config")],
        ),
    ])
  • Below is the run of the planar move plugin with continuous joints enabled: ​
  • Additionally, your plugin definition has incorrect XML header tags. Refer to the official gazebo_ros_pkgs migration doc to get the updated plugin definition.

Edit:

It seems that you have not included joint_state_publisher in the rsp.launch.py script.
Modify the launch file to add the node:

node_joint_state_publisher = Node(
    package='joint_state_publisher',
    executable='joint_state_publisher',
    name='joint_state_publisher',
    output='screen',
    parameters=[{'use_sim_time': use_sim_time}],
)
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3
  • $\begingroup$ thanks for your help. iust edit my post i and attached my 2 launch files in there i use_sim_time as true and i have the same issue what i need to change in my launch files thanks $\endgroup$
    – Rui Silva
    May 25, 2023 at 9:38
  • $\begingroup$ Refer to the edited answer to match the launch files you've sent. $\endgroup$ May 26, 2023 at 7:24
  • $\begingroup$ The missing joint state publisher in the edited answer sounds correct. $\endgroup$
    – Tully
    May 27, 2023 at 12:25

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