ros_gazebo_gym.core

Contains the core functions and classes that are used to setup the ros_gazebo_gym gymnasium environments. This contains functions for download the required dependencies, starting ROS launch files, connecting to the gazebo simulation and controllers, etc.

Submodules

• ros_gazebo_gym.core.controllers_connection
• ros_gazebo_gym.core.gazebo_connection
• ros_gazebo_gym.core.helpers
• ros_gazebo_gym.core.lazy_importer
• ros_gazebo_gym.core.ros_launcher

Package Contents

Classes

ControllersConnection	Class that contains several methods that can be used to interact with the
GazeboConnection	Class that contains several methods that can be used to interact with the Gazebo
LazyImporter	A class for importing modules lazily.
ROSLauncher	Class used to launch ROS launch files.

class ros_gazebo_gym.core.ControllersConnection(namespace='', controllers_list=None)

Class that contains several methods that can be used to interact with the ros_control controllers.

list_service_name

The name of the controller list service.

Type:

str

list_service

The controller list service.

Type:

rospy.impl.tcpros_service.ServiceProxy

switch_service_name

The name of the controller switch service.

Type:

str

switch_service

The controller switch service.

Type:

rospy.impl.tcpros_service.ServiceProxy

Initialize the ControllersConnection instance.

Parameters:

• namespace (str, optional) – The namespace on which the robot controllers can be found. Defaults to "".

• controllers_list (list, optional) – A list with currently available controllers to look for. Defaults to None, which means that the class will try to retrieve all the running controllers.

property controllers_list

Returns the list of available controllers.

property gazebo

Returns whether a ROS Gazebo simulation is running.

property gazebo_paused

Returns whether the Gazebo simulation is paused.

switch_controllers(controllers_on, controllers_off, strictness=1, timeout=0.0)

Function used to switch controllers on and off.

Parameters:

• controllers_on (list) – The controllers you want to turn on.

• controllers_off (list) – The controllers you want to turn off.

• strictness (int, optional) – Whether the switching will fail if anything goes wrong. Defaults to 1.

• timeout (float) – The timeout before the request is cancelled. Defaults to 0.0 meaning no timeout.

Returns:

Boolean specifying whether the switch was successful.

Return type:

bool

reset_controllers(timeout=1.0)

Resets the currently running controllers by turning them off and on.

Parameters:

timeout (float) – The timeout before the request is cancelled. Defaults to 0.0 meaning no timeout.

pause_controllers(controller_list=None, filter_list=[])

Pauses controllers.

Parameters:

• controller_list (list, optional) – The controllers you want to pause. Defaults to None, which means that the class will pause all the running controllers.

• filter_list (list, optional) – The controllers you want to ignore when pausing. Defaults to [].

unpause_controllers()

Unpauses all the paused controllers.

Returns:

Boolean specifying whether the unpause was successful.

Return type:

bool

class ros_gazebo_gym.core.GazeboConnection(reset_world_or_sim='WORLD', max_retry=20, retry_rate=5, log_reset=True)

Class that contains several methods that can be used to interact with the Gazebo simulation.

pause_proxy

ROS service that pauses the gazebo simulator.

Type:

rospy.impl.tcpros_service.ServiceProxy

unpause_proxy

ROS service that un-pauses the gazebo simulator.

Type:

rospy.impl.tcpros_service.ServiceProxy

reset_simulation_proxy

ROS service that resets the gazebo simulator.

Type:

rospy.impl.tcpros_service.ServiceProxy

reset_world_proxy

ROS service that resets the gazebo world.

Type:

rospy.impl.tcpros_service.ServiceProxy

spawn_sdf_proxy

ROS service that spawns a sdf model.

Type:

rospy.impl.tcpros_service.ServiceProxy

spawn_urdf_proxy

ROS service that spawns a urdf model.

Type:

rospy.impl.tcpros_service.ServiceProxy

get_model_state_proxy

ROS service used to set get model states.

Type:

rospy.impl.tcpros_service.ServiceProxy

set_model_state_proxy

ROS service used to set the model state of a object.

Type:

rospy.impl.tcpros_service.ServiceProxy

set_link_state_proxy

ROS service used to set the link states.

Type:

rospy.impl.tcpros_service.ServiceProxy

get_link_state_proxy

ROS service used to get the link states.

Type:

rospy.impl.tcpros_service.ServiceProxy

set_model_configuration_proxy

ROS service that sets the configuration of a model.

Type:

rospy.impl.tcpros_service.ServiceProxy

get_physics_proxy

ROS service used to retrieve the physics properties.

Type:

rospy.impl.tcpros_service.ServiceProxy

set_physics_proxy

ROS service used to set the physics properties.

Type:

rospy.impl.tcpros_service.ServiceProxy

Initiate the GazeboConnection instance.

Parameters:

• reset_world_or_sim (str, optional) – Whether you want to reset the whole simulation “SIMULATION” at startup or only the world “WORLD” (object positions). Defaults to “WORLD”.

• max_retry (int, optional) – How many times a command to the simulator is retried before giving up. Defaults to 30.

• retry_rate (int, optional) – The rate at which the retry is done. Defaults to 2 (i.e. 0.5 seconds).

• log_reset (bool, optional) – Whether we want to print a log statement when the world/simulation is reset. Defaults to True.

property physics_properties

Retrieves the physics properties from gazebo.

property time

Retrieves the Gazebo time.

pause_sim()

Pause the simulation.

unpause_sim()

Unpauses the simulation.

reset_sim()

Reset the simulation or the world.

Note

Implemented like this since in some simulations, when reset the simulation the systems that work with TF break. In this case we ONLY resets the object position, not the entire simulation.

get_model_state(model_name)

Retrieve the current state of a model.

Parameters:

model_name (str) – The name of the model for which you want to retrieve the state.

Returns:

The pose of the model.

Return type:

numpy.ndarray

Raises:

ros_gazebo_gym.exceptions.GetModelStateError – Thrown when the model state retrieval failed.

set_model_state(model_state)

Sets the state of a model.

Parameters:

model_state (gazebo_msgs.msg.SetModelState) – The model_state object.

Returns:

Boolean specifying whether the model state was set successfully.

Return type:

bool

Raises:

ros_gazebo_gym.exceptions.SetModelStateError – Thrown when the model state could not be set.

get_link_state(link_name)

Retrieve the current state of a model.

Parameters:

link_name (str) – The name of the robot link.

Returns:

The pose of the robot link.

Return type:

numpy.ndarray

Raises:

GetLinkStateError – Thrown when the link state retrieval failed.

set_model_configuration(model_name, joint_names, joint_positions, pause=True)

Sets the configuration of a model.

Parameters:

• model_name (string) – Model to set the configuration for.

• joint_names (list) – The joint names for which you want to set the configuration.

• joint_positions (list) – The joint positions you want to set.

• pause (bool, optional) – Pause the simulation while setting the model pose. Defaults to True.

Returns:

Boolean specifying whether the model configuration was set

successfully.

Return type:

bool

Raises:

ros_gazebo_gym.exceptions.SetModelConfigurationError – Thrown when the model configuration could not be set.

get_physics_properties()

Retrieve physics properties from gazebo.

Returns:

Physics properties

message.

Return type:

gazebo_msgs.srv.GetPhysicsPropertiesResponse

Raises:

ros_gazebo_gym.errors.GetPhysicsPropertiesError – Thrown when something goes wrong while trying to retrieve the physics properties.

set_physics_properties(**kwargs)

Change physics properties of the gazebo physics engine. These properties have to be supplied as a keyword argument.

Tip

You can use the GazeboConnection.set_physics_proxy If you want to send a gazebo_msgs.srv.SetPhysicsProperties message directly.

Parameters:

**kwargs – Keyword arguments specifying the physics properties you want to set.

Raises:

SetPhysicsPropertiesError – Thrown when something goes wrong while setting the physics properties.

change_gravity(x, y, z)

Changes the gravity vector

Parameters:

• x (float) – Gravity vector x coordinate.

• y (float) – Gravity vector y coordinate.

• z (float) – Gravity vector z coordinate.

spawn_object(object_name, model_name, models_folder_path, pose=None)

Spawns a object from the model directory into gazebo.

Parameters:

• object_name (str) – The name you want the model to have.

• model_name (str) – The model type (The name of the xml file you want to use).

• models_folder_path (str) – The folder in which you want to search for the models.

• pose (geometry_msgs.msg.Pose, optional) – The pose of the model, by default geometry_msgs.msg.Pose.

Returns:

A boolean specifying whether the model was successfully spawned.

Return type:

bool

Raises:

ros_gazebo_gym.exceptions.SpawnModelError – When model was not spawned successfully.

class ros_gazebo_gym.core.LazyImporter(module_name)

A class for importing modules lazily.

This class can be used to import modules and module objects lazily. It caches imported modules and module objects to avoid repeated imports.

module_name

The name of the module to import.

Type:

str

Initialize a new LazyImporter object.

Parameters:

module_name (str) – The name of the module to import.

class ros_gazebo_gym.core.ROSLauncher

Bases: object

Class used to launch ROS launch files.

successful

Whether the launch file was successfully launched. This only specifies if the launchfile was successfully executed not if it encountered errors.

Type:

bool

launched

classmethod initialize()

Make sure a ros master is running and ROS is initialized.

classmethod list_processes()

List all launched processes.

classmethod terminate(process_name)

Terminate a launched process.

Parameters:

process_name (str) – The process name.

classmethod terminate_all()

Terminate all launched processes.

classmethod launch(package_name, launch_file_name, workspace_path=None, log_file=None, critical=False, wait_time=2, outdated_warning=False, **kwargs)

Launch a given launchfile while also installing the launchfile package and or dependencies. This is done by using the ros_gazebo_gym dependency index.

Parameters:

• package_name (str) – The package that contains the launchfile.

• launch_file_name (str) – The launchfile name.

• workspace_path (str, optional) – The path of the catkin workspace. Defaults to None meaning the path will be determined.

• log_file (str, optional) – The log file to write the stdout to. Defaults to None meaning the stdout will be written to console.

• critical (bool, optional) – Whether the process is critical and an error message should be shown when the process is no longer running.

• wait_time (int, optional) – The time to wait before checking if the was launched successfully and is still running. Defaults to 2.

• outdated_warning (bool, optional) – Whether to show a update warning when the package is outdated. Defaults to False.

• **kwargs – Keyword arguments you want to pass to the launchfile.

Raises:

Exception – When something went wrong when launching the launchfile.