Interconnection of mobile CPS and stationary Production Machines trough Real-time Wireless Communication
Final Report Abstract
Wireless communication is indispensable for connected mobile applications. If the application is a production control task, reliable, time-deterministic data transmission is required. In the future, the number of such mobile tasks will grow due to the need for highly flexible production systems. In the intelligent factories of the future, mobile cyber-physical systems (CPS) such as automated guided vehicles or autonomous mobile robots will exchange a wide variety of information wirelessly. In this research project, a real-time wireless communication system for mobile CPS based on LTE was designed and evaluated. In the communication system, the devices have a synchronized local clock to enable time-triggered communication and application execution. The clock synchronization is based on GPS to be independent of the cellular connection. In order to react to the fluctuating bandwidth and signal quality of the wireless connection, the information to be transmitted is classified and assigned to different data traffic classes. The actual transmission of information is based on the mobile communication technology LTE, since it has a dedicated frequency range and is therefore protected. In addition to the time-deterministic data transmission, the transmission latency is decisive for the industrial usability of the communication system. In the first funding period of the research project, it was shown that the transmission latency of LTE is sufficient for many industrial applications, that a synchronized execution of tasks is possible using GPS- based time synchronization, and that a method with multiple traffic classes can be used when fluctuating signal quality is present. During the second funding period, industrial use cases were analyzed and mapped to the wireless communication. Furthermore, different approaches to reduce the transmission latency were evaluated. One approach resulted in a latency reduction of about 60% respective 30%, depending on the direction of the communication. Furthermore, a method for an efficient wireless multi-user communication was designed. In summary, the findings from both funding periods show a great potential for the use of mobile radio technologies for industrial communication. Regardless of the mobile radio technology used in the research project (LTE), the principles and findings investigated with regard to time synchronization, communication schemes, streaming stages, modem setup, etc. are transferable to other wireless communication technologies. However, through the investigations it also became clear that for industrial wireless communication a coordination between industrial control systems and the resource management of the wireless communication system for time-deterministic transmission would be beneficial. For this purpose, suitable interfaces, data models, and common configuration and management interfaces must be developed and investigated.
Publications
- Experimental Evaluation of the Deterministic Wireless Communication System Industrial LTE. In: 2022 8th International Conference on Mechatronics and Robotics Engineering (ICMRE), Institute of Electrical and Electronics Engineers Inc., 2022 — ISBN 9781665483773, S. 157–162
Neher, Philipp; Lechler, Armin; Verl, Alexander
(See online at https://doi.org/10.1109/ICMRE54455.2022.9734108) - Identification and Classification of the Communication Data of Automated Guided Vehicles and Autonomous Mobile Robots. In: 2022 8th International Conference on Automation, Robotics and Applications (ICARA), Institute of Electrical and Electronics Engineers Inc., 2022 — ISBN 9781665483834, S. 68–75
Neher, Philipp; Lechler, Armin; Verl, Alexander
(See online at https://doi.org/10.1109/ICARA55094.2022.9738572)
