There are three ways to to write a C++ publisher in ROS2, namely: Old-school approach Object-oriented (member-function) approach Local function (lambda) approach Below is an example of each approach to write a C++ node publishing “Hello World”. The code is taken from here: https://github.com/ros2/examples/tree/foxy/rclcpp/topics/minimal_publisher
Creating a C++ package Step 1: Create the package using the following CLI command: cd ~/ros2_ws/srcros2 pkg create [PACKAGE_NAME] –build-type ament_cmake –dependencies rclcpp std_msgs [OTHER_DEPENDENCY_PACKAGES] Step 2: Modify package.xml file for package dependencies of the created node(s). Step 3: Modify CMakeLists.txt.
ROS2 build system is colcon. In ROS1, the build system is catkin. What is the difference between ROS1 and ROS2 packages? In ROS1, you can mix C++ and Python nodes in a single package. In ROS2, as a standard practice, you either make a C++ package or a Python package. [Although as a non-standard practice, …
In ROS1, the structure of an overlay workspace, called the catkin workspace, looks like this: workspace_folder: |–src |–CMakeLists.txt |–package_1_folder |– |–package_n_folder |–devel |–build |–install The catkin workspace is built by running “catkin_make” command. To rebuild a catkin workspace, simply delete all the folders inside the workspace but the “src” folder and subsequently run the “catkin_make” …
The main tutorial page for ROS2 Foxy can be found here: https://docs.ros.org/en/foxy/index.html It is recommended to install a Long-Term Suppport (LTS) ROS2 distro. This tutorial describes the installation of ROS2 Foxy on Ubuntu 20. There are two ways to install ROS2: 1) from source and 2) from binary (Debian installer). Step 1: Make sure you …
ROS launch is a very useful command as it is capable to: run multiple nodes at the same time. set parameters. perform rosparam commands. set execution options. ROS launch file (.launch) is an XML file which looks like below. As it is an XML, indentation matters. An example launch file that sets a parameter: In …
ROS bag is used to record ROS messages and afterwards they can be played. This is very useful to record ROS messages published by robot’s sensors in a real test and later this data can be played without a need to perform another real test. Hence, this is particularly useful when the robot programming needs …
There are three types of messages in ROS: msg : used in topic srv : used in service action : used in action The msg message is defined in an .msg file, which looks like this: data_type variable_1 data_type variable_2 One or more .msg files are typically created inside a folder called “msg”. ROS topic …
ROS parameters are parameters in a node which can be modified from their default values. By this definition, the ROS parameters are very useful to be used when we want to be able to modify them quickly, in real-time. ROS parameters can be, for example, USB port numbers, camera calibration parameters, or minimum and maximum …
Below are the steps to create a ROS1 action: Step 1: Add the following in package.xml roscpp # Use this if the action is in C++ rospy # Use this if the action is in Python actionlib std_msgs message_generation actionlib_msgs roscpp # Use this if the action is in C++ rospy # Use this if …
