Improving Communication Efficiency and Anti-interference Measures in ROS2 for Unmanned Systems

Introduction: In order to successfully compete in the Ugvc (Unmanned Systems Innovation Competition), a strong communication system is essential as support. Additionally, the ground unmanned platform Kirin fighter must complete autonomous navigation tasks under refusal conditions. It is unclear whether tools that affect GPS in the competition will also affect other systems, so research on the impact of analog signals that interfere with GPS on other systems is necessary. The Ugvc team has chosen to use Ubuntu operating system and ROS2 for the entire platform, with communication inside the robot based on DDS and communication between the unmanned platform and the operating station relying on the antenna and data radio rocket M2. The key problem is reducing delay while ensuring communication quality and improving the anti-interference ability of the system. Through literature review, the team has gained understanding of the communication system at the bottom of ROS2 and some common anti-interference methods, providing information for future design of the communication system and anti-interference module.

Text: ROS is the most widely used and marketable middleware in the field of robotics, but has two major defects: high latency of communication and difficulty of framework expansion. ROS2 provides a scalable framework, but brings higher communication delay. Therefore, the urgent problem to be solved is how to reduce time delay. Common GPS signal jammers on the market shield GPS signals in the specified electromagnetic band by releasing radio interference waves, which may cause failure or damage of other electronic components. Research on electromagnetic compatibility involving the influence of GPS jammer radio interference on the electrical and control system of unmanned platforms is necessary.

Research status of communication scheme based on ROS2: ROS2 provides a flexible and modular architecture that allows for easy integration of different components and algorithms. Its communication scheme enables efficient and reliable data exchange between nodes. DDS middleware is a key component of the ROS2 communication scheme, providing a standardized protocol for data exchange between nodes. Interoperability and security overhead of the ROS2 DDS middleware have been analyzed, with minimal overhead found. Performance of the ROS2 communication scheme has also been explored, with communication speed of Micro-ROS found to be much faster than that of ROS1 under the same hardware conditions. An adaptive two-level serialization algorithm (ATSA) has also been developed to reduce overhead and improve efficiency of the system.

Research status of anti-interference technology and electromagnetic compatibility: Electromagnetic waves from electronic products may cause harm to other electronic products, making it necessary to study electromagnetic compatibility for anti-interference function on the system. Methods to suppress mutual interference of electronic components inside unmanned platforms include shielding components generating electromagnetic radiation interference on the PCB board, installing the entire PCB board and all connecting cables in a shielding chamber, and shielding the periphery of the shielding cavity or its own shielding. The use of composite materials in electromagnetic shielding is increasing, with composites fabricated using 3D printing technology exhibiting excellent EMS performances.

Summary: The research topic should focus on improving communication efficiency of ROS2 and making corresponding protection measures for possible electromagnetic interference. The team plans to conduct actual tests and comparisons between the omnidirectional antenna with the highest cost performance ratio and the original directional antenna on the market, and use metal shields to protect important components or parts with high radiation power. Testing the working ability of the unmanned platform under the influence of common GPS jammers on the market will help identify the most affected part and modify it. Finally, overall testing will be conducted to find and fill in gaps in the design of the communication link.