Use the gazebo-yarp-plugins in Gazebo Models

To understand the structure of gazebo-yarp-plugins, it is useful to understand what Gazebo plugins and Yarp device drivers are.

In a nutshell, Gazebo plugins are C++ classes that extend the functionalities of the Gazebo simulator, while Yarp device drivers are classes used in Yarp for abstracting the functionality of devices used in robots.

For additional information it is possible to access the official documentation for both Gazebo plugins and YARP Device Drivers.

The gazebo-yarp-plugins consists of:

gazebo plugins that instantiate yarp device drivers and
yarp device drivers that wrap gazebo functionalities inside the yarp device interfaces .

Furthermore, in gazebo-yarp-plugins there are several plugins that do not mimic any interface or capability present in real robots, but are nevertheless useful for simulating complex scenarios.

Plugins exposing functionalities available on real robots

Functionality	Plugin Name	Plugin Type	Gazebo Plugin class	YARP Device class (if any)
Control Board (encoder readings, motor control, ...)	`gazebo_yarp_controlboard`	Model	gazebo::GazeboYarpControlBoard	yarp::dev::GazeboYarpControlBoardDriver
6-Axis Force Torque sensor	`gazebo_yarp_forcetorque`	Sensor	gazebo::GazeboYarpForceTorque	yarp::dev::GazeboYarpForceTorqueDriver
Inertial Measurement Unit	`gazebo_yarp_imu`	Sensor	gazebo::GazeboYarpIMU	yarp::dev::GazeboYarpIMUDriver
Camera	`gazebo_yarp_camera`	Sensor	gazebo::GazeboYarpCamera	yarp::dev::GazeboYarpCameraDriver
Depth Camera	`gazebo_yarp_depthCamera`	Sensor	gazebo::GazeboYarpDepthCamera	yarp::dev::GazeboYarpDepthCameraDriver
Fake Control Board (the same interface of the Control Board, but over non-existing joints)	`gazebo_yarp_fakecontrolboard`	Model	gazebo::GazeboYarpFakeControlBoard	yarp::dev::GazeboYarpFakeControlBoardDriver
Lidar Sensor	`gazebo_yarp_lasersensor`	Sensor	gazebo::GazeboYarpLaserSensor	yarp::dev::GazeboYarpLaserSensorDriver
Coupled Joint Encoders	`gazebo_yarp_maissensor`	Model	gazebo::GazeboYarpMaisSensor	yarp::dev::GazeboYarpMaisSensorDriver
Stereo Cameras	`gazebo_yarp_multicamera`	Sensor	gazebo::GazeboYarpMultiCamera	yarp::dev::GazeboYarpMultiCameraDriver
Contact Load Cell Array	`gazebo_contactloadcellarray`	Model	gazebo::GazeboYarpContactLoadCellArray	yarp::dev::GazeboYarpContactLoadCellArrayDriver

Plugins exposing simulation-specific functionalities

Functionality	Plugin Name	Plugin Type	Gazebo Plugin class	YARP Device class (if any)
Clock synchronization	`gazebo_yarp_clock`	System	gazebo::GazeboYarpClock
Apply external force/torque via YARP facilities	`gazebo_yarp_externalwrench`	Model	gazebo::ApplyExternalWrench
Display the Center of Mass of a model	`gazebo_yarp_showmodelcom`	Model	gazebo::ShowModelCoM
Project an image stream on a simulated surface	`gazebo_yarp_videotexture`	Visual	gazebo::VideoTexture
Expose a YARP RPC interface to create/manipulate objects programatically.	`gazebo_yarp_worldinterface`	Model	gazebo::WorldInterface
Publish the absolute pose of the root link of a model.	`gazebo_yarp_modelposepublisher`	Model	gazebo::GazeboYarpModelPosePublisher
Expose a YARP RPC interface to attach/detach links of the models spawned to the links of the robot using a fixed joint.	`gazebo_yarp_rpc_linkattacher`	Model	gazebo::GazeboYarpLinkAttacher
Exposes the absolute pose, velocity and acceleration of a desired link through YARP analog server device	`gazebo_basestate`	Model	gazebo::GazeboYarpBaseState	yarp::dev::GazeboYarpBaseStateDriver
Changes the value of the property of a specific plugin attached to the model (if not present, the configuration is created)	`gazebo_yarp_configurationoverride`	Model	gazebo::GazeboYarpConfigurationOverride

Using the plugins in Gazebo Models

In Gazebo, the simulated models are described using the [SDF (simulation description format)]((http://gazebosim.org/sdf.html), an XML-based file format. Depending on the Gazebo Plugin Type, the way of loading or adding a plugin to a model changes, and the complete documentation is available at http://gazebosim.org/tutorials?cat=write_plugin .

For model plugins such as the gazebo_yarp_controlboard, a plugin can be loaded by adding a <plugin> SDF tag as a child of the <model> SDF tag that describes the model.

<plugin name="example_controlboard" filename="libgazebo_yarp_controlboard.so">
    <yarpConfigurationFile>model://example/example_controlboard.ini</yarpConfigurationFile>
</plugin>

Most Model and Sensor plugins present in gazebo-yarp-plugins read their configuration from the file referenced in the yarpConfigurationFile tag. The location of the file is defined by using a Gazebo URI, while the file is a .ini YARP configuration file. Alternatively, parameters can be passed directly in the sdf with the Bottle format using the yarpConfigurationString tag (e.g. <yarpConfigurationString>(name /iCub/linkattacher/rpc:i)</yarpConfigurationString>). When using yarpConfigurationString, it is important to remember that:

only one yarpConfigurationString can be defined for each plugin.
the tags <yarpConfigurationFile> and <yarpConfigurationString> can coexist, but if a parameter is defined in both the value in <yarpConfigurationString> will always be used.

For specific information consumed by each plugin, please refer to the doxygen documentation of the specific plugin class.

System plugins instead need to be loaded at the beginning of the simulation, and hence they are passed as command line arguments when launching gazebo (or gzserver). For using the YARP clock plugin, for example:

gazebo -s libgazebo_yarp_clock.so

Example models

A collection of example model showcasing the capabilities of the gazebo-yarp-plugins are available in the tutorial/model subfolder of this repository. To spawn this models in Gazebo, add the tutorial/model directory to the GAZEBO_MODEL_PATH enviromental variable, or load it from the Gazebo GUI.