layered_hardware_gz

A ros2_control layer implementation for joints of a virtual robot in the Ignition Gazebo simulator. See layered_hardware to understand the layered scheme.

Hardware Plugin: layered_hardware_gz/LayeredHardwareGazeboSim

Hardware parameters

layers (yaml, required)

• sequence of layers to be loaded by this ros2_control hardware

layers[*].name (string, required)

• arbitary name of the layer

layers[*].type (string, required)

• valid type name of the layer
• the type must be exported to the layered_hardware package if its base class is layered_hardware::LayerInterface, or to the layered_hardware_gz package if its base class is layered_hardware_gz::GazeboSimLayerInterface

Example of ros2_control tag in your robot description

<ros2_control name="LayeredHardwareGazeboSim" type="system">
    <hardware>
        <plugin>layered_hardware_gz/LayeredHardwareGazeboSim</plugin>
        <param name="layers">
            - name: example_layer_1
              type: layered_hardware/ExampleLayer
            - name: example_layer_2
              type: layered_hardware_gz/GzExampleLayer
            - name: example_layer_3
              ...
            ...
        </param>
        ...
    </hardware>
    ...
</ros2_control>

Layer plugin: layered_hardware_gz/GazeboJointLayer

• sends commands to joints in the Gazebo simulator within write() function
• fetches joints' states within read() function
• switches joints' operating modes within perform_command_mode_swtich() function when controllers using associated interfaces activate

Hardware parameters

<layer_name> (yaml, required)

• map of parameter names and values for this layer

<layer_name>.joints (map<string, map>, required)

• map of parameters for each joint

<layer_name>.joints.<joint_name>.initial_position (double, default: 0.0)

• joint position is initialized with this value by the layer

<layer_name>.joints.<joint_name>.operation_mode_map (map<string, string>, required)

• map to joint's operating mode names from associated interface names (typically joint interfaces)
• possible operating mode names are 'effort', 'position', & 'velocity'

Example of parameter description

<param name="example_gazebo_sim_joint_layer">
    joints:
        example_joint_1:
            initial_position: 0.5
            operation_mode_map:
                example_joint_1/position: position
                ...
        example_joint_2:
            ...
</param>

Example

• single joint