Getting ready

Gazebo plugins enable us to develop several robot models, sensors, and world properties using the Gazebo framework. Similar to pluginlib and nodelet, Gazebo plugins are share libraries, which can be dynamically loaded or unloaded from the Gazebo simulator.

However, Gazebo is independent of the ROS framework, and so using plugins, we can access and extend all the components of Gazebo. As usual, we can organize the Gazebo plugins into six types:

• World
• Model
• Sensor
• System
• Visual
• GUI

Each of these plugin types is associated with different components of Gazebo.

For example, a Model plugin is attached to and controls a specific model in Gazebo such as a holonomic or non-holonomic robot model. Similarly, a World plugin is attached to a world such as a structure or unstructured environment, and a Sensor plugin is attached to a specific sensor. Furthermore, the System plugin is specified on the command line, which is loaded first during Gazebo startup and provide users control over the startup process. Moreover, Visual and GUI plugins are related to appearance and are attached to the rendering engine.

A plugin type should be selected based on the desired functionality.

For example, you should use a World plugin to control world properties, such as the physics engine, ambient lighting, and so on. Similarly, you should use a Model plugin to control joints and the state of a model. Furthermore, you should use a Sensor plugin to acquire sensor information and control sensor properties.