DVL A50 Serial ROS 2 Driver

A modern, high-performance ROS 2 Lifecycle Node driver for the Water Linked DVL-A50 over serial. This module reads directly from the RS232/USB serial port rather than an Ethernet socket, eliminating network overhead and enabling tightly synchronized timestamps (this->now()) to prevent TF extrapolation failures typical of raw TCP/IP DVL configurations.

Setup & Udev Rules

To allow ROS to access the serial port (e.g. /dev/ttyUSB0) without requiring sudo privileges, you must add your user to the dialout group:

sudo usermod -a -G dialout $USER

Note: A system reboot or re-login is required for the group change to take effect.

Launching

The driver uses the standard ROS 2 component layout and lifecycle protocols. Launching will automatically trigger the node to configure and then activate.

source install/setup.bash
ros2 launch dvl_a50_serial dvl_a50_serial.launch.py

Configuration Parameters

Parameters can be configured in /config/dvl_a50_serial.yaml or over the ros2 param interface. Setting runtime parameters like speed_of_sound will automatically sync with the DVL directly.

Parameter	Type	Default	Description
port	string	/dev/ttyUSB0	The device file for the serial port.
baud_rate	int	115200	Baud rate for the serial interface.
frame	string	dvl_a50_link	The TF2 frame ID affixed to the DVL headers.
rate	double	30.0	Publishing frequency (Hz) for decoupled ROS 2 reports.
enable_on_activate	bool	false	Whether to automatically enable acoustic pings on lifecycle activation.
speed_of_sound	int	1500	Speed of sound in m/s used by the sensor.
led_enabled	bool	true	Toggles the internal DVL illumination LED.
mounting_rotation_offset	int	0	Hardware mounting offset in degrees.
range_mode	string	auto	Operating mode (auto, =3, 1<=3, etc).
timeout_configure_ms	int	3000	Serial command wait limit for configure frames.
timeout_calibrate_gyro_ms	int	15000	Gyro calibration can take up to 15 seconds.

(Also seamlessly supports standard ping timeouts timeout_reset_dead_reckoning_ms, timeout_trigger_ping_ms, timeout_set_protocol_ms)

Topics

Publishers

• dvl/velocity (marine_acoustic_msgs/msg/Dvl) - Core parsed velocities mapping standard acoustic speeds, covariance arrays, active transducer metrics, and altitude boundaries. Quality of Service is set to SensorDataQoS to prevent latency blocking.
• dvl/dead_reckoning (geometry_msgs/msg/PoseWithCovarianceStamped) - Positional drift mapped natively across DVL frames.
• dvl/odometry (nav_msgs/msg/Odometry) - Unified Odometry representing twist velocities combined seamlessly when dead reckoning tracks merge.

Services

The driver maps state operations down safely to the DVL backend using short timeouts to avoid stalling other executor nodes:

• enable (std_srvs/srv/Trigger) -> Turns precisely on acoustic transmission.
• disable (std_srvs/srv/Trigger) -> Secures acoustic noise output mode off.
• calibrate_gyro (std_srvs/srv/Trigger) -> Queues a fresh hardware gyro calibration. Takes up to 15 seconds.
• reset_dead_reckoning (std_srvs/srv/Trigger) -> zeroes DVL dead reckoning internal maps.
• trigger_ping (std_srvs/srv/Trigger) -> Mutes persistent ping mode and issues one standalone transducer pulse.

Usage Examples

Here are some standard ROS 2 CLI commands you can run in your terminal to easily interact with the module on the AUV:

Listening to Topics

# Listen to the raw velocity reports at full frequency
ros2 topic echo /dvl/velocity

# Monitor the integrated odometry containing twist & pose data
ros2 topic echo /dvl/odometry

# Check the DVL publication rate for performance tracking
ros2 topic hz /dvl/velocity

Calling Services

# Enable acoustics (turns on the DVL pings)
ros2 service call /enable std_srvs/srv/Trigger

# Disable acoustics (securely mutes the DVL pings)
ros2 service call /disable std_srvs/srv/Trigger

# Trigger the hardware gyro calibration routine (takes up to ~15 seconds)
ros2 service call /calibrate_gyro std_srvs/srv/Trigger

# Reset the internal dead reckoning positional tracks back to (0, 0, 0)
ros2 service call /reset_dead_reckoning std_srvs/srv/Trigger

# Fire a single ping manually (requires acoustics to be disabled first)
ros2 service call /trigger_ping std_srvs/srv/Trigger

Changing Parameters Dynamically

Because of the param_sub_ implementation, you can safely hot-swap core limits at runtime without restarting the lifecycle node!

# Change the speed of sound safely at runtime
ros2 param set /dvl_a50_serial speed_of_sound 1520

# Disable the internal LED
ros2 param set /dvl_a50_serial led_enabled false

# Switch range mode tracking to exclusively track 7.7m to 36m (mode 3)
ros2 param set /dvl_a50_serial range_mode "=3"

# Switch range mode tracking to search dynamically between 0.3m (1) and 36m (3)
ros2 param set /dvl_a50_serial range_mode "1<=3"

Manual Lifecycle Management

If you disable the auto-startup parameter in the launch file (autostart:=false), you must manually step the driver through its lifecycle states:

# Check the current lifecycle state of the node (e.g. 'unconfigured', 'inactive', 'active')
ros2 lifecycle get /dvl_a50_serial

# Configure the node (Attempts to connect to the serial port and configure the DVL)
ros2 lifecycle set /dvl_a50_serial configure

# Activate the node (Starts publishing ROS messages and enables acoustics if enable_on_activate is true)
ros2 lifecycle set /dvl_a50_serial activate

# Deactivate the node (Stops publishing and disables acoustics)
ros2 lifecycle set /dvl_a50_serial deactivate

# Clean up (Closes the serial port and unloads memory boundaries)
ros2 lifecycle set /dvl_a50_serial cleanup