Adding mock_hardware to diffbot and update docs for all usages (#357)

* Add mock_hardware to diffbot

* Fix position_state_following_offset and description

example_2/bringup/launch/diffbot.launch.py

@@ -32,9 +32,17 @@ def generate_launch_description():
  description="Start RViz2 automatically with this launch file.",
  )
  )
+ declared_arguments.append(
+ DeclareLaunchArgument(
+ "use_mock_hardware",
+ default_value="false",
+ description="Start robot with mock hardware mirroring command to its states.",
+ )
+ )
 
  # Initialize Arguments
  gui = LaunchConfiguration("gui")
+ use_mock_hardware = LaunchConfiguration("use_mock_hardware")
 
  # Get URDF via xacro
  robot_description_content = Command(
@@ -44,6 +52,9 @@ def generate_launch_description():
  PathJoinSubstitution(
  [FindPackageShare("ros2_control_demo_example_2"), "urdf", "diffbot.urdf.xacro"]
  ),
+ " ",
+ "use_mock_hardware:=",
+ use_mock_hardware,
  ]
  )
  robot_description = {"robot_description": robot_description_content}

example_2/description/ros2_control/diffbot.ros2_control.xacro

@@ -1,14 +1,22 @@
 <?xml version="1.0"?>
 <robot xmlns:xacro="http://www.ros.org/wiki/xacro">
 
- <xacro:macro name="diffbot_ros2_control" params="name prefix">
+ <xacro:macro name="diffbot_ros2_control" params="name prefix use_mock_hardware">
 
  <ros2_control name="${name}" type="system">
- <hardware>
- <plugin>ros2_control_demo_example_2/DiffBotSystemHardware</plugin>
- <param name="example_param_hw_start_duration_sec">0</param>
- <param name="example_param_hw_stop_duration_sec">3.0</param>
- </hardware>
+ <xacro:unless value="${use_mock_hardware}">
+ <hardware>
+ <plugin>ros2_control_demo_example_2/DiffBotSystemHardware</plugin>
+ <param name="example_param_hw_start_duration_sec">0</param>
+ <param name="example_param_hw_stop_duration_sec">3.0</param>
+ </hardware>
+ </xacro:unless>
+ <xacro:if value="${use_mock_hardware}">
+ <hardware>
+ <plugin>mock_components/GenericSystem</plugin>
+ <param name="calculate_dynamics">true</param>
+ </hardware>
+ </xacro:if>
  <joint name="${prefix}left_wheel_joint">
  <command_interface name="velocity"/>
  <state_interface name="position"/>

example_2/description/urdf/diffbot.urdf.xacro

@@ -14,6 +14,6 @@
  <xacro:diffbot prefix="$(arg prefix)" />
 
  <xacro:diffbot_ros2_control
- name="DiffBot" prefix="$(arg prefix)" />
+ name="DiffBot" prefix="$(arg prefix)" use_mock_hardware="$(arg use_mock_hardware)"/>
 
 </robot>

example_2/doc/userdoc.rst

@@ -69,6 +69,8 @@ Tutorial steps
 
  The ``[claimed]`` marker on command interfaces means that a controller has access to command *DiffBot*.
 
+ Furthermore, we can see that the command interface is of type ``velocity``, which is typical for a differential drive robot.
+
 4. Check if controllers are running
 
  .. code-block:: shell
@@ -103,6 +105,69 @@ Tutorial steps
  [DiffBotSystemHardware]: Got command 43.33333 for 'left_wheel_joint'!
  [DiffBotSystemHardware]: Got command 50.00000 for 'right_wheel_joint'!
 
+6. Let's introspect the ros2_control hardware component. Calling
+
+ .. code-block:: shell
+
+ ros2 control list_hardware_components
+
+ should give you
+
+ .. code-block:: shell
+
+ Hardware Component 1
+ name: DiffBot
+ type: system
+ plugin name: ros2_control_demo_example_2/DiffBotSystemHardware
+ state: id=3 label=active
+ command interfaces
+ left_wheel_joint/velocity [available] [claimed]
+ right_wheel_joint/velocity [available] [claimed]
+
+ This shows that the custom hardware interface plugin is loaded and running. If you work on a real
+ robot and don't have a simulator running, it is often faster to use the ``mock_components/GenericSystem``
+ hardware component instead of writing a custom one. Stop the launch file and start it again with
+ an additional parameter
+
+ .. code-block:: shell
+
+ ros2 launch ros2_control_demo_example_2 diffbot.launch.py use_mock_hardware:=True
+
+ Calling
+
+ .. code-block:: shell
+
+ ros2 control list_hardware_components
+
+ now should give you
+
+ .. code-block:: shell
+
+ Hardware Component 1
+ name: DiffBot
+ type: system
+ plugin name: mock_components/GenericSystem
+ state: id=3 label=active
+ command interfaces
+ left_wheel_joint/velocity [available] [claimed]
+ right_wheel_joint/velocity [available] [claimed]
+
+ You see that a different plugin was loaded. Having a look into the `diffbot.ros2_control.xacro <https://github.com/ros-controls/ros2_control_demos/tree/{REPOS_FILE_BRANCH}/example_2/description/ros2_control/diffbot.ros2_control.xacro>`__, one can find the
+ instructions to load this plugin together with the parameter ``calculate_dynamics``.
+
+ .. code-block:: xml
+
+ <hardware>
+ <plugin>mock_components/GenericSystem</plugin>
+ <param name="calculate_dynamics">true</param>
+ </hardware>
+
+ This enables the integration of the velocity commands to the position state interface, which can be
+ checked by means of ``ros2 topic echo /joint_states``: The position values are increasing over time if the robot is moving.
+ You now can test the setup with the commands from above, it should work identically as the custom hardware component plugin.
+
+ More information on mock_components can be found in the :ref:`ros2_control documentation <mock_components_userdoc>`.
+
 Files used for this demos
 --------------------------
 

example_3/bringup/launch/rrbot_system_multi_interface.launch.py

@@ -45,7 +45,7 @@ def generate_launch_description():
  DeclareLaunchArgument(
  "mock_sensor_commands",
  default_value="false",
- description="Enable fake command interfaces for sensors used for simple simulations. \
+ description="Enable mocked command interfaces for sensors used for simple simulations. \
  Used only if 'use_mock_hardware' parameter is true.",
  )
  )

example_3/description/ros2_control/rrbot_system_multi_interface.ros2_control.xacro

@@ -9,7 +9,7 @@
  <xacro:if value="${use_mock_hardware}">
  <plugin>mock_components/GenericSystem</plugin>
  <param name="mock_sensor_commands">${mock_sensor_commands}</param>
- <param name="state_following_offset">0.0</param>
+ <param name="position_state_following_offset">0.0</param>
  </xacro:if>
  <xacro:unless value="${use_mock_hardware}">
  <plugin>ros2_control_demo_example_3/RRBotSystemMultiInterfaceHardware</plugin>

example_4/bringup/launch/rrbot_system_with_sensor.launch.py

@@ -45,7 +45,7 @@ def generate_launch_description():
  DeclareLaunchArgument(
  "mock_sensor_commands",
  default_value="false",
- description="Enable fake command interfaces for sensors used for simple simulations. \
+ description="Enable mocked command interfaces for sensors used for simple simulations. \
  Used only if 'use_mock_hardware' parameter is true.",
  )
  )

example_4/description/ros2_control/rrbot_system_with_sensor.ros2_control.xacro

@@ -9,7 +9,7 @@
  <xacro:if value="${use_mock_hardware}">
  <plugin>mock_components/GenericSystem</plugin>
  <param name="mock_sensor_commands">${mock_sensor_commands}</param>
- <param name="state_following_offset">0.0</param>
+ <param name="position_state_following_offset">0.0</param>
  </xacro:if>
  <xacro:unless value="${use_mock_hardware}">
  <plugin>ros2_control_demo_example_4/RRBotSystemWithSensorHardware</plugin>

example_5/bringup/launch/rrbot_system_with_external_sensor.launch.py

@@ -45,7 +45,7 @@ def generate_launch_description():
  DeclareLaunchArgument(
  "mock_sensor_commands",
  default_value="false",
- description="Enable fake command interfaces for sensors used for simple simulations. \
+ description="Enable mocked command interfaces for sensors used for simple simulations. \
  Used only if 'use_mock_hardware' parameter is true.",
  )
  )

example_5/description/ros2_control/external_rrbot_force_torque_sensor.ros2_control.xacro

@@ -8,7 +8,7 @@
  <xacro:if value="${use_mock_hardware}">
  <plugin>mock_components/GenericSystem</plugin>
  <param name="mock_sensor_commands">${mock_sensor_commands}</param>
- <param name="state_following_offset">0.0</param>
+ <param name="position_state_following_offset">0.0</param>
  </xacro:if>
  <xacro:unless value="${use_mock_hardware}">
  <plugin>ros2_control_demo_example_5/ExternalRRBotForceTorqueSensorHardware</plugin>

example_5/description/ros2_control/rrbot_system_position_only.ros2_control.xacro

@@ -9,7 +9,7 @@
  <xacro:if value="${use_mock_hardware}">
  <plugin>mock_components/GenericSystem</plugin>
  <param name="mock_sensor_commands">${mock_sensor_commands}</param>
- <param name="state_following_offset">0.0</param>
+ <param name="position_state_following_offset">0.0</param>
  </xacro:if>
  <xacro:unless value="${use_mock_hardware}">
  <plugin>ros2_control_demo_example_5/RRBotSystemPositionOnlyHardware</plugin>

example_6/bringup/launch/rrbot_modular_actuators.launch.py

@@ -45,7 +45,7 @@ def generate_launch_description():
  DeclareLaunchArgument(
  "mock_sensor_commands",
  default_value="false",
- description="Enable fake command interfaces for sensors used for simple simulations. \
+ description="Enable mocked command interfaces for sensors used for simple simulations. \
  Used only if 'use_mock_hardware' parameter is true.",
  )
  )