Component-Based Programming with ROS2

Introduction

This project explores the advanced programming paradigm introduced in ROS2, focusing on converting traditional ROS2 nodes into components for a more modular and efficient design. The RB1 robot, simulated within a warehouse environment, serves as the platform for this exploration. Through the conversion of previously developed nodes into components, this project not only demonstrates the practicality of component-based programming in ROS2 but also evaluates the advantages and limitations of this approach in comparison to traditional node-based programming.

Objectives

• Convert existing ROS2 nodes into components for the RB1 robot, enhancing modularity and system organization.
• Experience and assess the differences, including the advantages and disadvantages, between traditional node-based programming and component-based programming in ROS2.

Tools and Technologies

• Programming Languages: Python, C++
• Frameworks and Libraries: ROS2, Gazebo
• Robotics Hardware: RB1 Robot by Robotnik
• Version Control: Git

Source Code

• GitHub Repository

Process and Development

The development process is structured around the conversion of existing ROS2 nodes from this previous entry into components, specifically focusing on the tasks of pre-approaching and attaching the RB1 robot to a warehouse shelf.

Node to Component Conversion

The project initiates by creating a new branch named composition in the existing repository and introducing a new ROS2 package called my_components. The first step involves converting the pre_approach.cpp node into a new component named PreApproach, which facilitates the robot’s initial movement towards the shelf.

• Pre-Approach Component: This component replicates the pre-approach behavior with hardcoded values instead of parameters, guiding the robot to face the shelf directly.

Service-Based Components for Shelf Attachment

Following the initial pre-approach phase, two new components, AttachServer and AttachClient, are developed to manage the final attachment process.

• AttachServer Component: Implements a service server for the /approach_shelf service, triggering the robot’s final approach to attach to the shelf using the manual-composition approach.
• AttachClient Component: Contains a service client that calls the /approach_shelf service, enabling the robot to initiate the final approach and attachment using the run-time composition approach.

A launch file, attach_to_shelf.launch.py, is created to facilitate the execution of these components, illustrating the practical deployment of component-based programming in ROS2.

Results

Through the conversion of traditional nodes into ROS2 components, this project showcases a great example of programming modularity and efficiency. The RB1 robot’s successful shelf attachment within the simulated warehouse environment validates the effectiveness of component-based programming in ROS2, highlighting its potential for future robotic applications.

Key Insights

• Component-based programming in ROS2 offers enhanced modularity, allowing for more organized and maintainable codebases.
• The transition from traditional node-based to component-based programming involves a learning curve but results in a more efficient and scalable system architecture.
• This project underscores the importance of embracing new programming paradigms in ROS2 to leverage the full potential of robotics development and deployment.