API

The communication with the LRAUV is done using Gazebo transport. It provides message passing, services, and data logging. It can use either topics or services. To have a look at what are the main ones that will be used in an LRAUV simulation here is a snapshot of the common ones when running something like gz sim buoyant_tethys.sdf.

Topics

Here are the topics clasified by the Plugin or Entity responsible of them.

Acoustic Comms Plugin

Topic	Message	Usage
/comms/internal	lrauv_gazebo_plugins::msgs:: LRAUVInternalComms	Default topic on which to send and listen for internal packets. A prefix can be set through conifiguration.
/comms/external/<address>/rx	lrauv_gazebo_plugins::msgs:: LRAUVAcousticMessage	Topic on which this plugin will publish received messages.
/comms/external/<address>/tx	lrauv_gazebo_plugins::msgs:: LRAUVAcousticMessage	This is where the plugin receives the data.

Science Sensors System

Topic	Message	Usage
/chlorophyll	gz::msgs::Float_V	Sensor readings for chlorophyll based on data loaded through csv.
/temperature	gz::msgs::Float_V	Sensor readings for temperature based on data loaded through csv.
/salinity	gz::msgs::Float_V	Sensor readings for salinity based on data loaded through csv.
/current	gz::msgs::Vector3d	Sensor readings for current based on data loaded through csv.
/science_data	gz::msgs::PointCloudPacked	Topic to publish the science data point cloud.
/model/tethys/chlorophyll	gz::msgs::Float_V	Sensor readings for chlorophyll based on data loaded through csv.
/model/tethys/current	gz::msgs::Float_V	Sensor readings for temperature based on data loaded through csv.
/model/tethys/salinity	gz::msgs::Float_V	Sensor readings for salinity based on data loaded through csv.
/model/tethys/temperature	gz::msgs::Float_V	Sensor readings for temperature based on data loaded through csv.
/world/science_sensor/environment_data_path	gz::msgs::StringMsg	Subscribes to this topic for updates on new environment data files.

Linear Battery Plugin

Topic	Message	Usage
/model/tethys/battery/linear_battery/state	gz::msgs.BatteryState	State of the linear battery. This plugin may publish other topics if enabled through the SDF configuration.

Buoyancy Engine

Topic	Message	Usage
/model/tethys/buoyancy_engine	gz::msgs::Double	Subscribes to this topic. This is the set point for the engine. Defaults to /buoyancy_engine if no <namespace> was defined.
/model/tethys/buoyancy_engine/current_volume	gz::msgs::Double	Publishes the current volume. Defaults to /buoyancy_engine if no <namespace> was defined.

Deatachable Joint

Topic	Message	Usage
/model/tethys/drop_weight	gz::msgs::Empty	Listens on this topic for deattaching connections. Topic defined through <topic>.

Joint Position Controller

Topic	Message	Usage
/model/tethys/joint/battery_joint/0/cmd_pos	gz::msgs::Double	Joint position controller for the battery joint, defaults to "/model/<model_name>/joint/<joint_name>/<joint_index>/cmd_pos" if no <topic> is provided.
/model/tethys/joint/horizontal_fins_joint/0/cmd_pos	gz::msgs::Double	Joint position controller for the horizontal fins joint, defaults to "/model/<model_name>/joint/<joint_name>/<joint_index>/cmd_pos" if no <topic> is provided.
/model/tethys/joint/vertical_fins_joint/0/cmd_pos	gz::msgs::Double	Joint position controller for the vertical fins joint, defaults to "/model/<model_name>/joint/<joint_name>/<joint_index>/cmd_pos" if no <topic> is provided.

Thruster

Topic	Message	Usage
/model/tethys/joint/propeller_joint/cmd_vel	gz::msgs::Double	Topic to receive joint velocity commands. The plugin will listen on the topic /model/{namespace}/joint/{joint_name}/cmd_thrustor /model/{namespace}/joint/{joint_name}/cmd_vel depending on the mode of operation (see <velocity_control>).
/model/tethys/joint/propeller_joint/force	gz::msgs::Double	If <use_angvel_cmd> is set to true it publishes force in Newtons instead to /model/{ns}/joint/{joint_name}/force.

IMU

Topic	Message	Usage
/tethys/ahrs/imu	gz::msgs::IMU	Topic to publish IMU vertical position, angular velocity and lienar acceleration readings.

Magnetometer

Topic	Message	Usage
/tethys/ahrs/magnetometer	gz::msgs::Magnetometer	Topic to report the magnetic field in its current location.

Thethys Comm Plugin

Topic	Message	Usage
/tethys/command_topic	lrauv_gazebo_plugins::msgs:: LRAUVCommand	Topic on which robot commands are received.
/tethys/state_topic	lrauv_gazebo_plugins::msgs:: LRAUVState	Topic on which robot state is published.
/tethys/navsat	gz::msgs::NavSat	Topic where NavSat reports position and velocity in spherical coordinates (latitude / longitude). Defined by <topic>.

World Comm Plugin

Topic	Message	Usage
/lrauv/init	lrauv_gazebo_plugins::msgs::LRAUVInit	Listens here to spawn new vehicles.

Range Bearing Plugin

Topic	Message	Usage
/tethys/range_bearing/requests	lrauv_gazebo_plugins::msgs:: LRAUVRangeBearingRequest	Topic where the plugin listens for range bearing requests.
/tethys/range_bearing/responses	lrauv_gazebo_plugins::msgs:: LRAUVRangeBearingResponse	Topic where the range bearing responses are published.

Scene Broadcaster Plugin

Topic	Message	Usage
/world/buoyant_tethys/dynamic_pose/info	gz::msgs::Pose_V	Dynamic pose publisher, for non-static model poses.
/world/buoyant_tethys/pose/info	gz::msgs::Pose_V	Pose publisher.
/world/buoyant_tethys/scene/deletion	gz::msgs::UInt32_V	Topic used by the scene broadcaster to request entities to be removed.
/world/buoyant_tethys/state	gz::msgs::SerializedSetpMap	Topic where state is published
/world/buoyant_tethys/scene/info	gz::msgs::Scene	Topic where scene are published.

World Config Plugin

Topic	Message	Usage
/world/science_sensor/environment_data_path	gz::msgs::StringMsg	This plugin will publish the data file path here when loaded through the GUI.

Gazebo Server

Topic	Message	Usage
/world/buoyant_tethys/clock	gz::msgs::Clock	Server world clock.
/world/buoyant_tethys/stats	gz::msgs::Clock	Provides statistics about the world, such as the time elapsed and the paused state.

Gazebo Simulation Runner

Topic	Message	Usage
/clock	gz::msgs::Clock	Publishes Gazebo simulation time.
/stats	gz::msgs::Clock	Provides statistics about the simulation, such as the time elapsed and the paused state.

Services

Most of the services that appear when running gz sim buoyant_tethys.sdf belong to gazebo plugins so please refer to the [official Gazebo documentation] for more info. The services more closely related to LRAUV, clasified by their plugin or entity responsible are:

Science Sensors System

Message to receive	Message sent	Usage
/model/tethys/chlorophyll/set_rate	gz::msgs::Double	gz::msgs::Empty
/model/tethys/current/set_rate	gz::msgs::Double	gz::msgs::Empty
/model/tethys/salinity/set_rate	gz::msgs::Double	gz::msgs::Empty
/model/tethys/temperature/set_rate	gz::msgs::Double	gz::msgs::Empty
/science_data	gz::msgs::Empty	gz::msgs::PointCloudPacked

Linear Battery Plugin

Message to receive	Message sent	Usage
/model/tethys/battery/linear_battery/recharge/start	gz::msgs::Boolean	gz::msgs::Empty
/model/tethys/battery/linear_battery/recharge/stop	gz::msgs::Boolean	gz::msgs::Empty

IMU

Message to receive	Message sent	Usage
/tethys/ahrs/imu/set_rate	gz::msgs::IMU	gz::msgs::Double

Magnetometer

Message to receive	Message sent	Usage
/tethys/ahrs/magnetometer/set_rate	gz::msgs::Double	gz::msgs::Empty