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_ignition_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_ignition_plugins::msgs:: LRAUVAcousticMessage	Topic on which this plugin will publish received messages.
/comms/external/<address>/tx	lrauv_ignition_plugins::msgs:: LRAUVAcousticMessage	This is where the plugin receives the data.

| Science Sensors System | /chlorophyll | gz::msgs::Float_V | Sensor readings for chlorophyll based on data loaded through csv. | | Science Sensors System | /temperature | gz::msgs::Float_V | Sensor readings for temperature based on data loaded through csv. | | Science Sensors System | /salinity | gz::msgs::Float_V | Sensor readings for salinity based on data loaded through csv. | | Science Sensors System | /current | gz::msgs::Vector3d | Sensor readings for current based on data loaded through csv. | | Science Sensors System |/science_data| gz::msgs::PointCloudPacked | Topic to publish the science data point cloud.| | Linear Battery Plugin |/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 |/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. | | Buoyancy Engine |/model/tethys/buoyancy_engine/current_volume|gz::msgs::Double| Publishes the current volume. Defaults to /buoyancy_engine if no <namespace> was defined. | | Science Sensors System |/model/tethys/chlorophyll|gz::msgs::Float_V | Sensor readings for chlorophyll based on data loaded through csv. | |Science Sensors System |/model/tethys/current|gz::msgs::Float_V | Sensor readings for temperature based on data loaded through csv. | |Science Sensors System |/model/tethys/salinity| gz::msgs::Float_V | Sensor readings for salinity based on data loaded through csv. | |Science Sensors System |/model/tethys/temperature|gz::msgs::Float_V | Sensor readings for temperature based on data loaded through csv. | | Deatachable Joint |/model/tethys/drop_weight| gz::msgs::Empty| Listens on this topic for deattaching connections. Topic defined through <topic>. | | Joint Position Controller |/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. | | Joint Position Controller |/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. | | Joint Position Controller |/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 |/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>). | | Thruster |/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 |/tethys/ahrs/imu| gz::msgs::IMU | Topic to publish IMU vertical position, angular velocity and lienar acceleration readings.| | Magnetometer |/tethys/ahrs/magnetometer| gz::msgs::Magnetometer | Topic to report the magnetic field in its current location. | | Thethys Comm Plugin |/tethys/command_topic| lrauv_ignition_plugins::msgs:: LRAUVCommand | Topic on which robot commands are received. | | NavSat |/tethys/navsat| gz::msgs::NavSat | Topic where NavSat reports position and velocity in spherical coordinates (latitude / longitude). Defined by <topic>. | | Range Bearing Plugin | /tethys/range_bearing/requests | rauv_ignition_plugins::msgs:: LRAUVRangeBearingRequest | Topic where the plugin listens for range bearing requests. | | Range Bearing Plugin | /tethys/range_bearing/responses | lrauv_ignition_plugins::msgs:: LRAUVRangeBearingResponse | Topic where the range bearing responses are published.| | Thethys Comm Plugin |/tethys/state_topic| lrauv_ignition_plugins::msgs:: LRAUVState | Topic on which robot state is published. | | Scene Broadcaster Plugin |/world/buoyant_tethys/dynamic_pose/info| gz::msgs::Pose_V | Dynamic pose publisher, for non-static model poses. | |Scene Broadcaster Plugin |/world/buoyant_tethys/pose/info| gz::msgs::Pose_V | Pose publisher. | |Scene Broadcaster Plugin |/world/buoyant_tethys/scene/deletion| gz::msgs::UInt32_V | Topic used by the scene broadcaster to request entities to be removed. |Scene Broadcaster Plugin |/world/buoyant_tethys/state| gz::msgs::SerializedSetpMap | Topic where state is published | | World Config Plugin |/world/science_sensor/environment_data_path| gz::msgs::StringMsg | This plugin will publish the data file path here when loaded through the GUI. | |Scene Broadcaster Plugin |/world/buoyant_tethys/scene/info| gz::msgs::Scene | Topic where scene are published. | | Gazebo Server |/world/buoyant_tethys/clock| gz::msgs::Clock | Server world clock.| |Gazebo Server |/world/buoyant_tethys/stats| gz::msgs::Clock | Provides statistics about the world, such as the time elapsed and the paused state.| | Gazebo Simulation Runner |/clock| gz::msgs::Clock | Publishes Gazebo simulation time.| | Gazebo Simulation Runner |/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 are:

Plugin/Entity responsible	Service	Message to recieve	Message sent	Usage
Science Sensors System	/model/tethys/chlorophyll/set_rate	gz::msgs::Double	gz::msgs::Empty	Sets the rate for the chlorophyll sensor.
Science Sensors System	/model/tethys/current/set_rate	gz::msgs::Double	gz::msgs::Empty	Sets the rate for the current sensor.
Science Sensors System	/model/tethys/salinity/set_rate	gz::msgs::Double	gz::msgs::Empty	Sets the rate for the salinity sensor.
Science Sensors System	/model/tethys/temperature/set_rate	gz::msgs::Double	gz::msgs::Empty	Sets the rate for the temperature sensor.
Science Sensors System	/science_data	gz::msgs::Empty	gz::msgs::PointCloudPacked	Service to request the science data point cloud.
Linear Battery Plugin	/model/tethys/battery/linear_battery/recharge/start	gz::msgs::Boolean	gz::msgs::Empty	Start recharging battery.
Linear Battery Plugin	/model/tethys/battery/linear_battery/recharge/stop	gz::msgs::Boolean	gz::msgs::Empty	Stop recharging battery.
IMU	/tethys/ahrs/imu/set_rate	gz::msgs::IMU	gz::msgs::Double	Set IMU sensor rate.
Magnetometer	/tethys/ahrs/magnetometer/set_rate	gz::msgs::Double	gz::msgs::Empty	Set magnetometer sensor rate.