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Gazebo Scene Randomiser Plugin

A plugin to randomise objects in the world on a given surface. Objects that have the static attribute enabled in Gazebo are unaffected, you can determine this by selecting a model and checking the left-side panel for the static attribute.

This plugin was developed while working on a 3rd Year Project at the University of Leeds for manipulation planning in cluttered environments.

User's interface with the plugin is through a ROS service. The plugin takes in the name of a collision link (the surface) and randomises the pose of all the objects in the world on that surface. For position, the x and y values are changed, and for rotation, the z-axis rotation (yaw) is changed.
The plugin will return the number of objects in the scene and the free space left on the surface.

The robot name must be set as a parameter on /robot_name so that the plugin can avoid changing the robot pose.

To include this plugin in a Gazebo world, you will need to include it in the .world file inside the <world> tag.
As an example:

<world>
    <plugin name='libgazebo_scene_randomiser_plugin' filename='libgazebo_scene_randomiser_plugin.so'/>
</world>

Limitations

  • The plugin only supports box and cylinder shaped surfaces.
  • The object areas are calculated using their shapes if they have one collision link named collision and are box or cylinder shapes, otherwise an Axis-Aligned Bounding Box is used.
  • Surface parent models must use _link_ to indicate child links.
  • Make the surface has its z-axis aligned with the world z-axis and has the same direction. The surface yaw can be changed, but roll and pitch must be zero.
  • The plugin was only tested with small objects. Larger objects may not be correctly placed on surfaces, especially surfaces with inner walls.

The Randomise Service

Input

  • string surface - surface name

Output

  • bool success - boolean indicating success/failure to randomise scene.
  • string message - output message.
  • int8 num_objects - number of objects in scene.
  • float64 surface_area - area of the surface, regardless of what is on it.
  • float64 free_area - free area left on the surface.

Usage

The plugin service is advertised on /gazebo/randomise_scene and it takes one parameter, surface, which is the name of the surface.

If using through the command line, simply use:

$ rosservice call /gazebo/randomise_scene "surface: 'name'"

Replace name with the name of a surface. For example, the table model in Gazebo would be table_link_surface or for one of the shelves on a bookshelf model, bookshelf_link_low_shelf.

To get the name from Gazebo, select the model then in the left side panel, expand the tree and click on "link". In the bottom menu, expand the links tree and search for the desired link.

As an example, the image below shows the required z-axis orientation and objects placed on the "low_shelf" collision link.

Gazebo Example

Demo

A demo is shown below of how the plugin works.

Randomiser Demo