Sample ROS2 project

An simple ROS2 node example with message generation in C++. Following topics are covered in this project:

• Node implementation in C++ with publisher/subscriber
• Message generation
• Use of own message within the project
• Unit testing with gtest
• Github action for building and testing the project

Build and run

In the root of your workspace, dev_ws, build your new package:

colcon build --packages-select sample

Now run the sample node:

ros2 run sample sample_node

Or run the provided launch file:

ros2 launch sample sample.launch.py

Run tests

Still in the root of your workspace, dev_ws, run the tests:

colcon test --packages-select sample --event-handlers console_direct+

Create messages

For message generation the following files should contain the content below:

CMakeLists.txt

find_package(rosidl_default_generators REQUIRED)

rosidl_generate_interfaces(${PROJECT_NAME} "msg/MyMessage.msg" "srv/MyService.srv")

package.xml

<build_depend>rosidl_default_generators</build_depend>

<exec_depend>rosidl_default_runtime</exec_depend>

<member_of_group>rosidl_interface_packages</member_of_group>

Create components

For creating a component in ROS the following files should add the content below:

Source file

#include "rclcpp_components/register_node_macro.hpp"

RCLCPP_COMPONENTS_REGISTER_NODE(MyNamespace::MyClassNode)

CMakeLists.txt

find_package(rclcpp REQUIRED)

find_package(rclcpp_components REQUIRED)

set(node_plugins "")

add_library(MyComponent SHARED src/my_component.cpp)

rclcpp_components_register_nodes(MyComponent "MyNamespace::MyClassNode")

target_compile_definitions(MyComponent PRIVATE "COMPOSITION_BUILDING_DLL")

ament_target_dependencies(MyComponent "rclcpp" "rclcpp_components")

set(node_plugins "${node_plugins}MyNamespace::MyClassNode;$<TARGET_FILE:MyComponent>\n")

install(TARGETS MyComponent ARCHIVE DESTINATION lib LIBRARY DESTINATION lib RUNTIME DESTINATION bin)

package.xml

<depend>rclcpp</depend>

<depend>rclcpp_components</depend>

Usage

Start component container on a terminal:

ros2 run rclcpp_components components_container

Next, load on a second terminal:

ros2 component load /ComponentManager MyNodeName MyNamespace::MyClassNode

Licence

This project is licensed under MIT. See LICENSE file for details.

Copyright © 2023 nfiniity GmbH.