Gazebo Skeleton Visual Model Plugin

skeleton_visual-2023-06-26_22.35.43.mp4

Overview

This repository contains a Gazebo visual plugin that allows for the visualization of a skeleton model in the Gazebo simulator, while the collision model utilizes primitive models such as spheres or cylinders instead of the skeleton.

The plugin is provided as a ROS package.

This project is based on the "Actor" plugin from Gazebo. You can find the original plugin here.

Installation

To install the Gazebo Skeleton Visual Model Plugin, clone the repository into your catkin workspace and build the package using catkin.

cd ~/catkin_ws/src
git clone https://github.com/groove-x/gazebo_skeleton_visual_model_plugin.git
cd ..
catkin_make

Usage

To apply the plugin, you will need:

• A physical simulation model (links and collisions) in Xacro format.
  • This model should have the same number of links as the skeleton model, but consists of primitive shapes such as spheres or cylinders.
• A skeleton model for visualization in Collada format (optional textures attached to it are also supported).
  • This visual model should have bones attached.
• Extra settings to be made to the Xacro file as shown in the Example section.

Example

See details in the example files:

• xacro/fish.xacro
• meshes/fish.dae
• config/example.yaml
• launch/example.launch

Joints, Links and Collisions in Xacro Format

Joints, links and collision models are defined in Xacro format.

origin in joint element represents the original offset from the parent link to the child link when the joint is in a zero position.

This is obtained directly from design tools like Blender, or is shown in log messages by setting <printTransforms>true</printTransforms> element to plugin's <skin> element.

<joint name="ventral_body_joint" type="revolute">
  <parent link="head_link"/>  <!-- NOTE: parent link of `body` bone -->
  <child link="ventral_body_link" />  <!-- NOTE: child link of `body` bone -->
  <origin xyz="0 0 0" rpy="-1.5708 0 -1.5708"/>
  <axis xyz="0 0 1"/>
  <limit effort="20" velocity="5" lower="-0.5" upper="0.5"/>
  <dynamics damping="0.1"/>
</joint>

<link name="ventral_body_link">
  <!-- inertial and collision description here -->
</link>

<transmission name="ventral_body_trans">
  <!-- transmission description which is optional -->
</transmission>

Skeleton Model in Collada Format

The skeleton model defined in Collada format is exported from design tools with bones attached to the mesh.

Plugin Setting in Xacro Format

Plugin settings are used to map xacro joints to Collada bones.

<gazebo>
  <plugin name="model_visuals" filename="libskeleton_model_plugin.so">
    <skin>
      <filename>/path/to/skeleton_visual.dae</filename>
      <scale>1.0</scale>
      <!-- <printTransforms>true</printTransforms> -->
      <bone name="body" link="ventral_body_link" parent="head_link"/>
      <bone name="fin" link="caudal_fin_link" parent="ventral_body_link"/>
    </skin>
  </plugin>
</gazebo>

In this context, name refers to the name of the bone in the Collada model, link represents the link name in the Xacro model, and parent represents the parent link name in the Xacro model. This configuration correlates the physical simulation (collision) and visualization (skeleton).

When the printTransforms element is set to true, the plugin prints the transform of each bone in the skeleton model to the terminal.

If you need the original offset from the parent link to the child link when the joint is at zero position, you need to remove all bone elements.

Run the example

cd ~/catkin_ws/src
git clone https://github.com/groove-x/gazebo_skeleton_visual_model_plugin.git
cd ..
catkin_make
roslaunch gazebo_skeleton_visual_model_plugin example.launch

Now, you can see a fish swimming.

Support

The Gazebo Skeleton Visual Model Plugin is tested and supported on Gazebo 11 with ROS noetic.

Contributing

Contributions are welcome! Please fork the repository and create a pull request with your changes.

License

This project is licensed under BSD License.