Analysis and optimization of communication delay in multi-subscriber environments of ROS 2

ROS 2 is one of the most popular robotic software development frameworks. ROS 2 employs a publish–subscribe paradigm for data exchanges, which can effectively address the diverse real-time requirements from the publisher side by various policies provided in the underlying communication layer. However, it remains unclear whether it adequately meets the various real-time requirements of subscribers. In this paper, we formally analyze the communication delay where a single message is published to multiple subscribers. In particular, we have identified a problem in the transmission of a message to multiple subscribers, where a subscriber with the highest priority may receive its message as late as the subscriber with the lowest priority. We propose policies to solve this problem and optimize the communication delay. Comprehensive experiments are conducted to validate and evaluate the proposed methods.