better_launch.gazebo module

Additional functions for working with Gazebo, taking inspiration from simple_launch.

class better_launch.gazebo.GazeboBridge(topic: str, ros2_type: str = None, direction: Literal['ros2gz', 'gz2ros', 'bidirectional', '[', ']', '@'] = 'bidirectional', gazebo_type: str = None, *, remaps: dict[str, str] = None)

Bases: object

classmethod clock_bridge() → GazeboBridge

Creates a GazeboBridge instance for bridging the /clock topic from Gazebo to ROS.

Returns

GazeboBridge

An instance of the GazeboBridge for the clock topic.

classmethod from_string(bridge: str, remaps: dict[str, str] = None) → GazeboBridge

Extract the topic, ROS2 message type, direction, and gazebo message type from a bridge definition string.

Parameters

bridgestr

A bridge definition following the pattern <topic>@<ros2_type><direction><gazebo_type>.

remapsstr, optional

Topic remaps the bridge should use once it is started.

Returns

GazeboBridge

An instance with the aforementionend parameters.

Raises

ValueError

If the bridge string doesn’t match the expected pattern.

gazebo_message_types = {'actuator_msgs/msg/Actuators': 'gz.msgs.Actuators', 'builtin_interfaces/msg/Time': 'gz.msgs.Time', 'geometry_msgs/msg/Point': 'gz.msgs.Vector3d', 'geometry_msgs/msg/Pose': 'gz.msgs.Pose', 'geometry_msgs/msg/PoseArray': 'gz.msgs.Pose_V', 'geometry_msgs/msg/PoseStamped': 'gz.msgs.Pose', 'geometry_msgs/msg/PoseWithCovariance': 'gz.msgs.PoseWithCovariance', 'geometry_msgs/msg/PoseWithCovarianceStamped': 'gz.msgs.PoseWithCovariance', 'geometry_msgs/msg/Quaternion': 'gz.msgs.Quaternion', 'geometry_msgs/msg/Transform': 'gz.msgs.Pose', 'geometry_msgs/msg/TransformStamped': 'gz.msgs.Pose', 'geometry_msgs/msg/Twist': 'gz.msgs.Twist', 'geometry_msgs/msg/TwistStamped': 'gz.msgs.Twist', 'geometry_msgs/msg/TwistWithCovariance': 'gz.msgs.TwistWithCovariance', 'geometry_msgs/msg/TwistWithCovarianceStamped': 'gz.msgs.TwistWithCovariance', 'geometry_msgs/msg/Vector3': 'gz.msgs.Vector3d', 'geometry_msgs/msg/Wrench': 'gz.msgs.Wrench', 'geometry_msgs/msg/WrenchStamped': 'gz.msgs.Wrench', 'gps_msgs/msg/GPSFix': 'gz.msgs.NavSat', 'nav_msgs/msg/Odometry': 'gz.msgs.OdometryWithCovariance', 'rcl_interfaces/msg/ParameterValue': 'gz.msgs.Any', 'ros_gz_interfaces/msg/Altimeter': 'gz.msgs.Altimeter', 'ros_gz_interfaces/msg/Contact': 'gz.msgs.Contact', 'ros_gz_interfaces/msg/Contacts': 'gz.msgs.Contacts', 'ros_gz_interfaces/msg/Dataframe': 'gz.msgs.Dataframe', 'ros_gz_interfaces/msg/Entity': 'gz.msgs.Entity', 'ros_gz_interfaces/msg/Float32Array': 'gz.msgs.Float_V', 'ros_gz_interfaces/msg/GuiCamera': 'gz.msgs.GUICamera', 'ros_gz_interfaces/msg/JointWrench': 'gz.msgs.JointWrench', 'ros_gz_interfaces/msg/Light': 'gz.msgs.Light', 'ros_gz_interfaces/msg/ParamVec': 'gz.msgs.Param', 'ros_gz_interfaces/msg/SensorNoise': 'gz.msgs.SensorNoise', 'ros_gz_interfaces/msg/StringVec': 'gz.msgs.StringMsg_V', 'ros_gz_interfaces/msg/TrackVisual': 'gz.msgs.TrackVisual', 'ros_gz_interfaces/msg/VideoRecord': 'gz.msgs.VideoRecord', 'rosgraph_msgs/msg/Clock': 'gz.msgs.Clock', 'sensor_msgs/msg/BatteryState': 'gz.msgs.BatteryState', 'sensor_msgs/msg/CameraInfo': 'gz.msgs.CameraInfo', 'sensor_msgs/msg/FluidPressure': 'gz.msgs.FluidPressure', 'sensor_msgs/msg/Image': 'gz.msgs.Image', 'sensor_msgs/msg/Imu': 'gz.msgs.IMU', 'sensor_msgs/msg/JointState': 'gz.msgs.Model', 'sensor_msgs/msg/Joy': 'gz.msgs.Joy', 'sensor_msgs/msg/LaserScan': 'gz.msgs.LaserScan', 'sensor_msgs/msg/MagneticField': 'gz.msgs.Magnetometer', 'sensor_msgs/msg/NavSatFix': 'gz.msgs.NavSat', 'sensor_msgs/msg/PointCloud2': 'gz.msgs.PointCloudPacked', 'std_msgs/msg/Bool': 'gz.msgs.Boolean', 'std_msgs/msg/ColorRGBA': 'gz.msgs.Color', 'std_msgs/msg/Empty': 'gz.msgs.Empty', 'std_msgs/msg/Float32': 'gz.msgs.Float', 'std_msgs/msg/Float64': 'gz.msgs.Double', 'std_msgs/msg/Header': 'gz.msgs.Header', 'std_msgs/msg/Int32': 'gz.msgs.Int32', 'std_msgs/msg/String': 'gz.msgs.StringMsg', 'std_msgs/msg/UInt32': 'gz.msgs.UInt32', 'tf2_msgs/msg/TFMessage': 'gz.msgs.Pose_V', 'trajectory_msgs/msg/JointTrajectory': 'gz.msgs.JointTrajectory', 'vision_msgs/msg/Detection2D': 'gz.msgs.AnnotatedAxisAligned2DBox', 'vision_msgs/msg/Detection2DArray': 'gz.msgs.AnnotatedAxisAligned2DBox_V'}

Map from ROS2 message types to Gazebo message types.

classmethod joint_state_bridge(model: str) → GazeboBridge

Creates a GazeboBridge instance for the bridging the joint states of a given model to ROS.

Parameters

modelstr

The model name to associate with the joint state topic.

Returns

GazeboBridge

An instance of the GazeboBridge for the joint state topic.

better_launch.gazebo.gazebo_launch(package: str, world_file: str, gz_args: list[str] = None, world_save_file: str = None, save_after: float = 10.0) → None

Starts a Gazebo simulation with the specified world. If world_save_file is specified, the world will be saved as an SDF to that file after save_after seconds, including base world and spawned entities.

Parameters

packagestr,

A package to locate the world_file in. May be None (see [BetterLaunch.find][]).

world_filestr

Path to the primary world file for the simulation.

gz_args_type_, optional

Optional arguments to pass to the Gazebo simulator.

world_save_file_type_, optional

Path where the resulting SDF should be saved.

save_afterfloat, optional

Time in seconds after which the world SDF should be saved.

better_launch.gazebo.get_gazebo_axes_args(x: float = 0.0, y: float = 0.0, z: float = 0.0, yaw: float = 0.0, pitch: float = 0.0, roll: float = 0.0) → dict[str, float]

Constructs a list of command-line arguments that can be used e.g. when spawning a new model.

Parameters

xfloat, optional

translation x component

yfloat, optional

translation y component

zfloat, optional

translation z component

yawfloat, optional

rotation yaw component

pitchfloat, optional

rotation pitch component

rollfloat, optional

rotation roll component

Returns

dict[str, float]

A dictionary containing the axes names and values. The axes names correspond to what Gazebo expects on the command line and so can be passed to e.g. [spawn_model][].

better_launch.gazebo.get_gazebo_version() → str

For a short time, Gazebo rebranded to “Ignition” before returning to Gazebo again. This function returns the associated prefix.

Returns

str

The prefix indicating the type of Gazebo: “ign” for Ignition Gazebo or “gz” for Gazebo Classic.

better_launch.gazebo.save_world(filepath: str, after: float = 5.0) → None

Saves the current gazebo world to a file. Resolves any spawned URDF through their description parameter and converts to SDF.

Parameters

filepathstr

Path to the file to save the gazebo world to.

afterfloat, optional

How long to wait before saving.

better_launch.gazebo.spawn_image_bridge(*bridges: str | GazeboBridge, node_name: str = None, remaps: dict[str, str] = None, cmd_args: list[str] = None, qos: str = None, **kwargs) → Node

Spawn a bridge to efficiently relay images from Gazebo to ROS2 (one direction only).

Parameters

bridgeslist[str | GazeboBridge]

The image topics to bridge. These can be specified as either Gazebo bridge definitions, [GazeboBridge][] instances. Also accepts regular topics, in which case the type is assumed to be sensor_msgs/Image.

node_namestr, optional

The name of the node running the bridge.

remapsdict[str, str], optional

How topics should be remapped in ROS2.

cmd_argslist[str], optional

Additional commandline arguments to the bridge executable.

qosstr, optional

The ROS2 quality of service definition to use. Note that this is not supported in all versions of ros-gz-image and may cause the bridge to terminate.

kwargsdict[str, Any]

Additional node arguments.

Returns

Node

The node running the bridge process.

Raises

ValueError

If a topic is passed which is not an image topic.

better_launch.gazebo.spawn_model(model_name: str, model: str, model_source: Literal['topic', 'file', 'string', 'param', 'auto'] = 'auto', spawn_args: dict[str, Any] = None) → Node

Spawns a model into Gazebo under the given name from the specified topic or file.

The spawn_args dictionary can include additional options, such as the initial pose of the model.

Note that when spawning robot models this way, they typically also need a [convenience.joint_state_publisher][].

Parameters

model_namestr

The name of the model to spawn in the Gazebo environment.

modelstr

The model to spawn. The contents of this string depend on the model_source, but should ultimately lead to a full XML description.

model_sourcestr

Where to read the model from. Auto will try to guess the source based on the content of model: does it look like XML, is it a file, is it an existing topic? Otherwise assume it’s a ROS2 parameter.

spawn_argsdict[str, Any], optional

Additional arguments for spawning the model, such as pose and other options. See [get_gazebo_axes_args][] for defining the model’s orientation.

Returns

Node

The spawned node instance.

better_launch.gazebo.spawn_topic_bridge(*bridges: str | GazeboBridge, node_name: str = 'gz_bridge', remaps: dict[str, str] = None, cmd_args: list[str] = None, **kwargs) → Node

Start a Gazebo topic bridge to relay messages between ROS2 and Gazebo.

Note that there is a separate function for bridging image topics more efficiently. See [spawn_image_bridge][].

Parameters

bridgeslist[str | GazeboBridge]

Definitions of topic bridges. This can be either a typical string (<topic>@<ros2_type><direction><gazebo_type>) or a [GazeboBridge][] instance. Note that in order to bridge services you will have to specify them as strings for now.

node_namestr, optional

The name of the bridge node.

remapsdict[str, str], optional

Any topic remaps you wish to apply to the bridge.

cmd_argslist[str], optional

Additional command line arguments to the gazebo bridge executable.

kwargsdict[str, Any]

Additional node arguments.

Returns

Node

The node running the bridge process.

better_launch.gazebo.spawn_world_transform(gazebo_world_frame: str = None) → Node

Runs a static_transform_publisher to connect the ROS world frame and a Gazebo world frame, if the Gazebo world frame is specified and different from ‘world’.

Parameters

gazebo_world_framestr, optional

The name of the Gazebo world frame. Uses [get_active_world_name][] if None.

Returns

Node

The spawned node instance.