Fraunhofer Institute for Integrated Circuits IIS, Division Engineering of Adaptive Systems EASNewsletter 03/2021
Modern production lines often include mobile systems or numerous mobile subsystems that are equipped with sensors and actuators. In general, both of these applications require a low-latency data connection to the higher-level control system or other subsystems. The regulation of highly dynamic processes in particular calls for isochronous cycle times in the sub-millisecond range in conjunction with extremely high transmission reliability. At present, this is achieved exclusively using wired real-time bus systems – but these installations severely limit the mobility of system components, take up a relatively large amount of space, and are costly and time-consuming to retrofit to existing systems. Although these obstacles can be overcome using wireless transmission systems, the wireless technologies available today are not fast enough to support cycle times of less than 1 millisecond in automation applications. It’s for this reason that researchers at Fraunhofer IIS and its EAS branch developed an innovative real-time wireless technology in the form of the Ultra-reliable Wireless Industrial Network (UWIN).
UWIN was designed as a wireless extension of real-time fieldbus systems for short-range isochronous data transmission and can be used in applications such as production cells. At the same time, it meets the most demanding requirements in terms of transmission latencies and transmission reliability. What’s so special about UWIN is that it can operate in unlicensed frequency bands such as 5 GHz U-NII and is therefore suitable for use around the globe. Integrated monitoring allows UWIN to identify and evade neighboring wireless systems.
The dependable fulfilment of demanding reliability requirements at such low cycle times represents a major challenge. In the event of a transmission failure, the additional delay means it is not possible to request the repetition of data packets. For UWIN technology, researchers are therefore developing a network-based coding technique in combination with cooperative communication by multiple radio nodes. This “network-coded cooperation” brings significant advantages in terms of reliability and transmission efficiency and is particularly beneficial for single transmission pathways that are subject to considerable interference.
Now, we have developed an evaluation kit for UWIN wireless technology. The kit consists of two field devices and a base station, which monitors the performance parameters of the individual connections. The system operates in the license-free 5 GHz U-NII frequency band, but operators can determine for themselves which frequency channels are used. An Ethernet interface allows the user to access the evaluation kit’s dashboard, which displays various performance parameters and metrics relating to the transmission reliability of the individual connections over time, as well as long-term statistics. Thanks to the kit, interested partners from the machinery and equipment industry, for example, can test UWIN real-time wireless technology in their own application environments and discover its capabilities.
More information on UWIN is available at: https://www.iis.fraunhofer.de/de/ff/kom/iot/low-latency/uwin.html.