Mobile_Robot_URDF_Maker (v3)

Automate the process of making a URDF for your mobile robot using this “Wizard”

• You can now easily choose any controller you want for your selected mobile robot. A new page has been added to the wizard which let’s you choose one of the six available controllers.
• Based on the type of your robot, you may choose one these controllers:
• 2-Wheeled Robot with a Caster Wheel:
  • Differential-Drive Controller
• 3-Wheeled Robot (Tricycle):
  • Tricycle Controller
  • Tricycle-Steering Controller
• 4-Wheeled Robot:
  • Differential-Drive Controller (Skid-Steering)
  • Ackermann-Steering Controller
  • Mecanum-Drive Controller
• After choosing the controller type and setting the parameters of the robot, the corresponding values for the controller will be set in the specific config file of that controller type (config files can be found at: /mobRobURDF_control/config/).

• Other good news is that now you can simulate your robot in Modern Gazebo (since the Gazebo Classic has reached its EOL). In order to do that, a new launch file has been added. By launching this launch file, robot, Gazebo world, and all the controllers will be spawned. Also, Rviz2 window will open up as well; so, please build the workspace, source it, and finally run the following command:

ros2 launch mobRobURDF_launch gazebo_test.launch.py

• It should be mentioned that for now, all the twist commands are unstamped; however, the stamped versions are on the way. For now, in order to control the robot in gazebo teleoperately, please run one of the following lines in another terminal based on your controller type:

Differential-Drive Controller:

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/diffDrive_controller/cmd_vel_unstamped

Tricycle Controller:

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/tricycle_controller/cmd_vel

Tricycle-Steering Controller:

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/triSteer_controller/reference_unstamped

Differential-Drive Controller (Skid-Steering):

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/diffDrive_controller/cmd_vel_unstamped

Ackermann-Steering Controller:

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/ackerSteer_controller/reference_unstamped

Mecanum-Drive Controller:

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/mecDrive_controller/reference_unstamped

• One more thing to mention is that some of the controllers don’t publish odom->base_link tf by themselves. For those ones, you’ll need to run a separate node for publishing odom->base_link tf and odometry topic. Soon, I’ll add those necessary nodes as well, so that you won’t need to do anything at all.

• Finally, you can modify the Gazebo physical properties for your simulation in the following file: /mobRobURDF_description/urdf/gazebo_files/gazebo_properties.xacro. Also, you may add a new world (based on your needs) in the following directory: /mobRobURDF_gazebo/worlds/ (and then modify the launch file).

• I almost forgot it. Another good news is that now, by generating the URDF for your robot, not only a .urdf file is created, also a .urdf.xacro file is created as well (/mobRobURDF_description/urdf/mobRob.urdf and /mobRobURDF_description/urdf/mobRob.urdf.xacro), so that you can easily modify the parameters after closing the wizard.

• Finally, one minor fix is that in this version, the caster wheel (for the 2WC robot type) has 3-DOF for free motion (instead of its previous fixed joint).

Just like the previous version, the path to run the wizard is as simple as you can see:

In order to run the Wizard, first you need to clone the workspace:

git clone https://github.com/ali-pahlevani/Mobile_Robot_URDF_Maker.git
cd Mobile_Robot_URDF_Maker

For the next step, you’ll need to install the dependencies:

sudo apt update
rosdep install --from-paths src --ignore-src -r -y
sudo apt install python3-pyqt5 python3-pyqt5.qtopengl
pip install PyOpenGL PyOpenGL_accelerate
pip install ruamel.yaml

After that, you should build the workspace and source the installation:

colcon build --symlink-install
source install/setup.bash

Finally, you can easily run the following line in your terminal:

ros2 run mobRobURDF_wizard mobRobURDF_wizard

In order to launch the new launch file (Gazebo + Rviz2), you can run the following line in your terminal:

ros2 launch mobRobURDF_launch gazebo_test.launch.py

If you have any questions, please let me know: a.pahlevani1998@gmail.com

• Also, please don’t forget to check out our website at: https://www.SLAMbotics.org

Please stay tuned for the next versions of the app.

Version 2

Automate the process of making a URDF for your mobile robot using this “Wizard”

• Now, you don’t have only 1 option (4-wheeled robot). In version 2, you’ll have 3 options to choose from (in the next version, I’ll introduce specific controllers for each of these types, so that you can make ros2_control config files for each of these types of kinematics):
  • 4-Wheeled Robot
  • 3-Wheeled Robot (Tricycle)
  • 2-Wheeled Robot with a Caster Wheel
• You can easily choose the type of robot you need to work with, build its URDF automatically (based on the parameters you choose), and get your built URDF file.
  • In this version, when you hit the save button, first a copy of the URDF file is saved automatically in a specific place for the launch file; so that launch file will recognize it automatically when you launch it (for testing purposes).
  • Other than that, you can also save another copy of it to any directory you want (or simply close the saving window if you don’t need it!).
• As it be seen, the overall structure of the wizard has been enhanced and organized, so that not only you can navigate to different pages using Navigation Bar, also at the last page of the wizard (in this version), you can see the upcoming updates for the wizard in the next releases (adding Gazebo files, SLAM and Navigation capability, setting up Controllers, etc.).

Just like the previous version, the path to run the wizard is as simple as you can see:

In order to run the Wizard, first you need to clone the workspace:

git clone https://github.com/ali-pahlevani/Mobile_Robot_URDF_Maker.git
cd Mobile_Robot_URDF_Maker

For the next step, you’ll need to install the dependencies:

sudo apt update
rosdep install --from-paths src --ignore-src -r -y
sudo apt install python3-pyqt5 python3-pyqt5.qtopengl

After that, you should build the workspace and source the installation:

colcon build --symlink-install
source install/setup.bash

Finally, you can easily run the following line in your terminal:

ros2 run mobRobURDF_wizard mobRobURDF_wizard

In order to run the launch file, you can run the following line in your terminal:

    ros2 launch mobRobURDF_launch urdf_test.launch.py

If you have any question, please let me know: a.pahlevani1998@gmail.com

Please stay tuned for the next versions of the app.

Version 1

Automate the process of making a URDF for your 4-wheeled mobile robot using this “Wizard”

This workspace has 3 ROS2 packages (up to now. I have plan for adding other packages as well for Gazebo, Control, Navigation, etc.):

1. mobRobURDF_description:

   • This package includes all the template Xacro files necessary for creating the final URDF file. The sub-directories in this directory are:
     • submodules: containing base.xacro (chassis), wheels.xacro (4 wheels), and sensors.xacro (2D-Lidar + RGB Camera) files,
     • macros: containing inertial_macros.xacro, and material.xacro (colors) files,
     • gazebo_files: containing gazebo_sensors.xacro file for now (in the future, when the Gazebo package is added, not only this file will be used in the final URDF file, also other Xacro files for Gazebo will be added as well (e.g., gazebo_properties.xacro file)).
   • Finally, all the Xacro files are imported into the main Xacro file (mobRob.xacro), so that it can be converted to mobRob.urdf file.
   • Good news is that not only you can use the Wizard to make the URDF file you need, but also you have access to all the Xacro files. If you ever wanted to change any of them and adapt them to your specific case, you’re free to go.

1. mobRobURDF_wizard:

   • This is the main package of the workspace. This package contains the source codes of the Wizard. The codebase is composed of different classes and some utility functions, all imported into the main file robot_wizard.py. This package used to be a standalone codebase; however, now its a ROS2 node.
   • In the Wizard window, you can apply your changes step by step, with no pressure. You can even fill only some of the fields and only apply those changes. Finally, you can save your created URDF file to any directory you want. Additionally, for your convenience, you’ll have 3-DOF camera rotation, plus zooming capability in the preview window.

   • Attention: If you want to use the launch file (that is provided for testing purposes (check the next part)), you’ll need to save the created URDF file in the following location: /mobRobURDF_description/urdf/mobRob.urdf

   • In order to run the Wizard, first you need to clone the workspace:

    git clone https://github.com/ali-pahlevani/Mobile_Robot_URDF_Maker.git
    cd Mobile_Robot_URDF_Maker
    

- For the next step, you'll need to install the **dependencies**:

    sudo apt update
    rosdep install --from-paths src --ignore-src -r -y
    sudo apt install python3-pyqt5 python3-pyqt5.qtopengl
    

- After that, you should **build** the workspace and **source** the installation:

    colcon build --symlink-install
    source install/setup.bash
    

- Finally, you can easily run the following line in your **terminal**:

    ros2 run mobRobURDF_wizard mobRobURDF_wizard
    

1. mobRobURDF_launch:

   • This package includes 2 main directories:
     • launch: containing only one launch file (for now) for testing purposes (urdf_test.launch.py). By launching this launch file, 3 nodes will be launched:
       • robot_state_publisher
       • joint_state_publisher_gui
       • rviz2 Using these nodes, everyone would be able to test the performance of the final URDF file (visual check + testing the joints)
     • rviz: containing only one rviz2 config file (rviz_test.rviz). This is the rviz2 config file that is loaded into the discussed launch file.
   • In order to run the launch file, you can run the following line in your terminal:

ros2 launch mobRobURDF_launch urdf_test.launch.py