dvl-a50

Description

This repository contains a plugin for the use of the Water Linked DVL-A50 sensor in ROS2 with the advantage of making use of its new tools such as composition and Lifecycle management.

Requirements

• ROS2 - Galactic or newer
• Ubuntu 20.04 or newer

Dependencies

• dvl_msgs
• JSON for Modern C++

Installation

• Clone the repositories and compile them:

$ source /opt/ros/galactic/setup.bash
$ mkdir -p ~/ros2_ws/src
$ cd ~/ros2_ws/src
$ git clone https://github.com/paagutie/dvl_msgs.git
$ git clone --recurse-submodules https://github.com/paagutie/dvl-a50.git
$ cd ..
$ colcon build

Usage

There are three ways to use this package. The first one uses a python script, the second one a node written in c++, for which the external library Json was used. These versions allow to run a node in a separate process with the benefits of process/fault isolation as well as easier debugging. The latest version uses Lifecycle for node management and composition to increase efficiency. Thus it's possible to have more control over the TCP/IP socket configuration needed for communication.

• First, find and set a static IP address (usually: 192.168.194.90) on your computer.

Python

• To use the python script open a new terminal to run the node:

$ cd ~/ros2_ws
$ source install/setup.bash
$ ros2 run dvl_a50 dvl_a50.py --ros-args -p ip_address:='192.168.194.95'

C++

• To use the C++ node:

$ cd ~/ros2_ws
$ source install/setup.bash
$ ros2 run dvl_a50 dvl_a50_sensor --ros-args -p dvl_ip_address:='192.168.2.95'
or
$ ros2 launch dvl_a50 dvl_a50.launch.py ip_address:='192.168.194.95'

Lifecycle management (deprecated)

ROS 2 introduces the concept of managed nodes, also called LifecycleNodes. Managed nodes contain a state machine with a set of predefined states. These states can be changed by invoking a transition id which indicates the succeeding consecutive state.

• The node must first be launched using composition. This allows multiple nodes to be executed in a single process with lower overhead and, optionally, more efficient communication (see Intra Process Communication). The idea of using composition is to be able to make use of its advantages when integrating more than one node, which is the case of a robotic system.

$ cd ~/ros2_ws
$ source install/setup.bash
$ ros2 launch dvl_a50 dvl_composition.launch.py ip_address:='192.168.194.95'

• Then in a new terminal the initial options can be viewed using Lifecycle. To know the available transitions:

$ source /opt/ros/galactic/setup.bash
$ ros2 lifecycle list /dvl_a50_node

- configure [1]
	Start: unconfigured
	Goal: configuring
- shutdown [5]
	Start: unconfigured
	Goal: shuttingdown

• Now it's possible to configure the node to establish communication with the sensor via TCP/IP socket:

$ ros2 lifecycle set /dvl_a50_node configure

• To know the current transition state use:

$ ros2 lifecycle get /dvl_a50_node

inactive [2]

Available transitions for this node using Lifecycle management

$ ros2 lifecycle set /dvl_a50_node activate
$ ros2 lifecycle set /dvl_a50_node deactivate
$ ros2 lifecycle set /dvl_a50_node cleanup
$ ros2 lifecycle set /dvl_a50_node shutdown

ROS2 Topics

• /dvl/data
• /dvl/position
• dvl/config/status
• dvl/command/response
• dvl/config/command

Lifecycle management

• /dvl_a50_node/transition_event