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Add Demos for SDF #427

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Dec 4, 2024
Merged

Add Demos for SDF #427

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cd8ebcf
Add demo for diff_drive
Amronos Oct 17, 2024
ea5a737
Merge branch 'rolling' into sdf-demos
Amronos Oct 30, 2024
8bd9152
Merge branch 'rolling' into sdf-demos
ahcorde Nov 8, 2024
ed7f047
Add an argument for specifying description format
Amronos Nov 30, 2024
ebd0e09
Add SDF demo for ackermann_drive
Amronos Nov 30, 2024
c82f846
Merge branch 'rolling' into sdf-demos
Amronos Dec 2, 2024
d47195d
Fix whitespace
Amronos Dec 2, 2024
8297b3d
Update documentation
Amronos Dec 2, 2024
352cd12
Apply suggestions from code review
Amronos Dec 2, 2024
38b6dc1
Fix formatting errors
Amronos Dec 3, 2024
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70 changes: 63 additions & 7 deletions doc/index.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -61,13 +61,13 @@ To run the demo
ros2 run gz_ros2_control_demos example_position


Add ros2_control tag to a URDF
Add ros2_control tag to a URDF or SDF
==========================================

Simple setup
-----------------------------------------------------------

To use *ros2_control* with your robot, you need to add some additional elements to your URDF.
To use *ros2_control* with your robot, you need to add some additional elements to your URDF or SDF.
You should include the tag ``<ros2_control>`` to access and control the robot interfaces. We should
include:

Expand Down Expand Up @@ -96,7 +96,7 @@ include:
Using mimic joints in simulation
-----------------------------------------------------------

To use ``mimic`` joints in *gz_ros2_control* you should define its parameters in your URDF, i.e, set the ``<mimic>`` tag to the mimicked joint (see the `URDF specification <https://wiki.ros.org/urdf/XML/joint>`__)
To use ``mimic`` joints in *gz_ros2_control* you should define its parameters in your URDF or SDF, i.e, set the ``<mimic>`` tag to the mimicked joint (see the `URDF specification <https://wiki.ros.org/urdf/XML/joint>`__ or the `SDF specification <http://sdformat.org/spec?ver=1.11&elem=joint#axis_mimic>`__)

.. code-block:: xml

Expand All @@ -122,12 +122,14 @@ The mimic joint must not have command interfaces configured in the ``<ros2_contr
Add the gz_ros2_control plugin
==========================================

In addition to the *ros2_control* tags, a Gazebo plugin needs to be added to your URDF that
In addition to the *ros2_control* tags, a Gazebo plugin needs to be added to your URDF or SDF that
actually parses the *ros2_control* tags and loads the appropriate hardware interfaces and
controller manager. By default the *gz_ros2_control* plugin is very simple, though it is also
extensible via an additional plugin architecture to allow power users to create their own custom
robot hardware interfaces between *ros2_control* and Gazebo.

URDF:
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.. code-block:: xml

<gazebo>
Expand All @@ -136,12 +138,20 @@ robot hardware interfaces between *ros2_control* and Gazebo.
</plugin>
</gazebo>

SDF:

.. code-block:: xml

<plugin filename="libgz_ros2_control-system.so" name="gz_ros2_control::GazeboSimROS2ControlPlugin">
<parameters>$(find gz_ros2_control_demos)/config/cart_controller.yaml</parameters>
</plugin>

The *gz_ros2_control* ``<plugin>`` tag also has the following optional child elements:

* ``<parameters>``: A YAML file with the configuration of the controllers. This element can be given multiple times to load multiple files.
* ``<controller_manager_name>``: Set controller manager name (default: ``controller_manager``)

The following additional parameters can be set via child elements in the URDF or via ROS parameters in the YAML file above:
The following additional parameters can be set via child elements in the URDF/SDF or via ROS parameters in the YAML file above:

* ``<hold_joints>``: if set to true (default), it will hold the joints' position if their interface was not claimed, e.g., the controller hasn't been activated yet.
* ``<position_proportional_gain>``: Set the proportional gain. (default: 0.1) This determines the setpoint for a position-controlled joint ``joint_velocity = joint_position_error * position_proportional_gain``.
Expand All @@ -157,6 +167,8 @@ or via ROS parameters:

Additionally, one can specify a namespace and remapping rules, which will be forwarded to the controller_manager and loaded controllers. Add the following ``<ros>`` section:

URDF:

.. code-block:: xml

<gazebo>
Expand All @@ -169,10 +181,23 @@ Additionally, one can specify a namespace and remapping rules, which will be for
</plugin>
</gazebo>

SDF:

.. code-block:: xml


<plugin filename="libgz_ros2_control-system.so" name="gz_ros2_control::GazeboSimROS2ControlPlugin">
...
<ros>
<namespace>my_namespace</namespace>
<remapping>/robot_description:=/robot_description_full</remapping>
</ros>
</plugin>

Default gz_ros2_control Behavior
-----------------------------------------------------------

By default, without a ``<plugin>`` tag, *gz_ros2_control* will attempt to get all of the information it needs to interface with a ros2_control-based controller out of the URDF. This is sufficient for most cases, and good for at least getting started.
By default, without a ``<plugin>`` tag, *gz_ros2_control* will attempt to get all of the information it needs to interface with a ros2_control-based controller out of the URDF or SDF. This is sufficient for most cases, and good for at least getting started.

The default behavior provides the following ros2_control interfaces:

Expand All @@ -188,9 +213,11 @@ The *gz_ros2_control* Gazebo plugin also provides a pluginlib-based interface to
These plugins must inherit the ``gz_ros2_control::GazeboSimSystemInterface``, which implements a simulated *ros2_control*
``hardware_interface::SystemInterface``. SystemInterface provides API-level access to read and command joint properties.

The respective GazeboSimSystemInterface sub-class is specified in a URDF model and is loaded when the
The respective GazeboSimSystemInterface sub-class is specified in a URDF or SDF model and is loaded when the
robot model is loaded. For example, the following XML will load the default plugin:

URDF:

.. code-block:: xml

<ros2_control name="GazeboSimSystem" type="system">
Expand All @@ -205,12 +232,28 @@ robot model is loaded. For example, the following XML will load the default plug
</plugin>
</gazebo>

SDF:

.. code-block:: xml

<ros2_control name="GazeboSimSystem" type="system">
<hardware>
<plugin>gz_ros2_control/GazeboSimSystem</plugin>
</hardware>
...
<ros2_control>
<plugin name="gz_ros2_control::GazeboSimROS2ControlPlugin" filename="libgz_ros2_control-system">
...
</plugin>

Set up controllers
-----------------------------------------------------------

Use the tag ``<parameters>`` inside ``<plugin>`` to set the YAML file with the controller configuration
and use the tag ``<controller_manager_prefix_node_name>`` to set the controller manager node name.

URDF:

.. code-block:: xml

<gazebo>
Expand All @@ -220,6 +263,15 @@ and use the tag ``<controller_manager_prefix_node_name>`` to set the controller
</plugin>
<gazebo>

SDF:

.. code-block:: xml

<plugin name="gz_ros2_control::GazeboSimROS2ControlPlugin" filename="libgz_ros2_control-system">
<parameters>$(find gz_ros2_control_demos)/config/cart_controller.yaml</parameters>
<controller_manager_prefix_node_name>controller_manager</controller_manager_prefix_node_name>
</plugin>

The following is a basic configuration of the controllers:

- ``joint_state_broadcaster``: This controller publishes the state of all resources registered to a ``hardware_interface::StateInterface`` to a topic of type ``sensor_msgs/msg/JointState``.
Expand All @@ -233,6 +285,10 @@ gz_ros2_control_demos
==========================================

There are some examples in the *gz_ros2_control_demos* package.
To specify whether to use URDF or SDF, you can launch the demo in the following way (the default is URDF):
.. code-block:: shell

ros2 launch gz_ros2_control_demos <launch file> description_format:=sdf

Cart on rail
-----------------------------------------------------------
Expand Down
1 change: 1 addition & 0 deletions gz_ros2_control_demos/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ find_package(geometry_msgs REQUIRED)
install(DIRECTORY
launch
config
sdf
urdf
DESTINATION share/${PROJECT_NAME}/
)
Expand Down
53 changes: 31 additions & 22 deletions gz_ros2_control_demos/launch/ackermann_drive_example.launch.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@
# limitations under the License.

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription
from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription, OpaqueFunction
from launch.actions import RegisterEventHandler
from launch.event_handlers import OnProcessExit
from launch.launch_description_sources import PythonLaunchDescriptionSource
Expand All @@ -27,18 +27,29 @@ def generate_launch_description():
# Launch Arguments
use_sim_time = LaunchConfiguration('use_sim_time', default=True)

# Get URDF via xacro
robot_description_content = Command(
[
PathJoinSubstitution([FindExecutable(name='xacro')]),
' ',
PathJoinSubstitution(
[FindPackageShare('gz_ros2_control_demos'),
'urdf', 'test_ackermann_drive.xacro.urdf']
),
]
)
robot_description = {'robot_description': robot_description_content}
def robot_state_publisher(context):
performed_description_format = LaunchConfiguration('description_format').perform(context)
# Get URDF or SDF via xacro
robot_description_content = Command(
[
PathJoinSubstitution([FindExecutable(name='xacro')]),
' ',
PathJoinSubstitution([
FindPackageShare('gz_ros2_control_demos'),
performed_description_format,
f'test_ackermann_drive.xacro.{performed_description_format}'
]),
]
)
robot_description = {'robot_description': robot_description_content}
node_robot_state_publisher = Node(
package='robot_state_publisher',
executable='robot_state_publisher',
output='screen',
parameters=[robot_description]
)
return [node_robot_state_publisher]

robot_controllers = PathJoinSubstitution(
[
FindPackageShare('gz_ros2_control_demos'),
Expand All @@ -47,13 +58,6 @@ def generate_launch_description():
]
)

node_robot_state_publisher = Node(
package='robot_state_publisher',
executable='robot_state_publisher',
output='screen',
parameters=[robot_description]
)

gz_spawn_entity = Node(
package='ros_gz_sim',
executable='create',
Expand Down Expand Up @@ -84,7 +88,7 @@ def generate_launch_description():
output='screen'
)

return LaunchDescription([
ld = LaunchDescription([
bridge,
# Launch gazebo environment
IncludeLaunchDescription(
Expand All @@ -105,11 +109,16 @@ def generate_launch_description():
on_exit=[ackermann_steering_controller_spawner],
)
),
node_robot_state_publisher,
gz_spawn_entity,
# Launch Arguments
DeclareLaunchArgument(
'use_sim_time',
default_value=use_sim_time,
description='If true, use simulated clock'),
DeclareLaunchArgument(
'description_format',
default_value='urdf',
description='Robot description format to use, urdf or sdf'),
])
ld.add_action(OpaqueFunction(function=robot_state_publisher))
return ld
53 changes: 31 additions & 22 deletions gz_ros2_control_demos/launch/diff_drive_example.launch.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@
# limitations under the License.

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription
from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription, OpaqueFunction
from launch.actions import RegisterEventHandler
from launch.event_handlers import OnProcessExit
from launch.launch_description_sources import PythonLaunchDescriptionSource
Expand All @@ -27,18 +27,29 @@ def generate_launch_description():
# Launch Arguments
use_sim_time = LaunchConfiguration('use_sim_time', default=True)

# Get URDF via xacro
robot_description_content = Command(
[
PathJoinSubstitution([FindExecutable(name='xacro')]),
' ',
PathJoinSubstitution(
[FindPackageShare('gz_ros2_control_demos'),
'urdf', 'test_diff_drive.xacro.urdf']
),
]
)
robot_description = {'robot_description': robot_description_content}
def robot_state_publisher(context):
performed_description_format = LaunchConfiguration('description_format').perform(context)
# Get URDF or SDF via xacro
robot_description_content = Command(
[
PathJoinSubstitution([FindExecutable(name='xacro')]),
' ',
PathJoinSubstitution([
FindPackageShare('gz_ros2_control_demos'),
performed_description_format,
f'test_diff_drive.xacro.{performed_description_format}'
]),
]
)
robot_description = {'robot_description': robot_description_content}
node_robot_state_publisher = Node(
package='robot_state_publisher',
executable='robot_state_publisher',
output='screen',
parameters=[robot_description]
)
return [node_robot_state_publisher]

robot_controllers = PathJoinSubstitution(
[
FindPackageShare('gz_ros2_control_demos'),
Expand All @@ -47,13 +58,6 @@ def generate_launch_description():
]
)

node_robot_state_publisher = Node(
package='robot_state_publisher',
executable='robot_state_publisher',
output='screen',
parameters=[robot_description]
)

gz_spawn_entity = Node(
package='ros_gz_sim',
executable='create',
Expand Down Expand Up @@ -85,7 +89,7 @@ def generate_launch_description():
output='screen'
)

return LaunchDescription([
ld = LaunchDescription([
# Launch gazebo environment
IncludeLaunchDescription(
PythonLaunchDescriptionSource(
Expand All @@ -106,11 +110,16 @@ def generate_launch_description():
)
),
bridge,
node_robot_state_publisher,
gz_spawn_entity,
# Launch Arguments
DeclareLaunchArgument(
'use_sim_time',
default_value=use_sim_time,
description='If true, use simulated clock'),
DeclareLaunchArgument(
'description_format',
default_value='urdf',
description='Robot description format to use, urdf or sdf'),
])
ld.add_action(OpaqueFunction(function=robot_state_publisher))
return ld
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