Real-Time

The H-ROS ecosystem uses an optimized Linux-based Real-Time Operating System (OS), which allows to deploy real-time applications. In order to have a real-time distributed robotic system, we need both real-time computing and deterministic network communications between H-ROS modules.

Real-time is not about how fast tasks or communications are performed, but about determinism. The operating system is critical for real-time robotic control. Having a deterministic behavior through time and in different conditions allows robots (and robot modules) to respond appropriately, always meeting the technical requirements they were designed for.

This Real-Time OS allows our system to execute tasks under timing constraints. Real-time benchmarks show that we are able to execute tasks deterministically, achieving latencies between 10-100 us, even when then system is under heavy load conditions. The following plot shows the results of a 5 hours test under system stress conditions using cyclictest in order to measure the system's response time:

For certain robotic applications, such as motion control, having deterministic communications is critical. H-ROS modules implement IEEE 802.1 Time Sensitive Networking (TSN) Standards which provides deterministic latency for critical traffic in the presence of non-critical traffic. This allows modules with very different network requirements and criticality to coexist in the same network without needing isolated buses.

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Upper communication layers will also introduce latency and jitter in the communications. In the case of H-ROS modules, real-time OS is used and the networking system has been customized in order to improve determinism latencies and in order to prioritize the processing of critical traffic. This allows to achieve bounded end-to-end communication latencies, even when the system is under load or in the presence of lower priority traffic.

Read more about this topic in our related publications: