Robot Operating System 2 (ROS2) targets distributed real-time systems. Especially in tight real-time control loops, latency in data processing and communication can lead to instabilities. As ROS2 encourages splitting of the data-processing pipelines into several modules, it is important to understand the latency implications of such modularization. In this paper, we investigate the end-to-end latency of ROS2 data-processing pipeline with different Data Distribution Service (DDS) middlewares. In addition, we profile the ROS2 stack and point out latency bottlenecks. Our findings indicate that end-to-end latency strongly depends on the used DDS middleware. Moreover, we show that ROS2 can lead to 50 % latency overhead compared to using low-level DDS communications. Our results imply guidelines for designing modular ROS2 architectures and indicate possibilities for reducing the ROS2 overhead.

翻译：机器人操作系统2 (ROS2) 目标分布在实时系统中。 特别是在紧凑的实时控制循环中, 数据处理和通信的延迟可能导致不稳定。 ROS2鼓励将数据处理管道分成几个模块, 重要的是要了解这种模块化的延迟影响。 在本文件中, 我们调查ROS2 数据处理管道与不同数据发布服务( DDS) 中间器件的端到端的延迟。 此外, 我们描述ROS2 堆, 指出长期瓶颈。 我们的调查结果显示, 终端到端的延迟在很大程度上取决于已使用的 DDS 中间器。 此外, 我们显示, ROS2 与使用低水平的 DDS 通信相比, 可能导致50%的延迟间接费用。 我们的结果意味着设计模块式 ROS2 结构的指导方针, 并表明减少 ROS2 间接费用的可能性 。