To regulate traffic at the intersections in the factory, a system had to be designed so that the AGVs could "see" traffic lights in the same way as the drivers of tugger trains. © Siemens

Diogo Graça, logistics planning specialist at Volkswagen Autoeuropa: "The focus was not so much on increasing efficiency or productivity. It was mainly about creating a safe flow with manually operated vehicles (tugger trains) and autonomous vehicles (AGVs). Long before the introduction of AGVs, the area was already known for its limited visibility and narrow corridors. The responsiveness of our tugger train drivers has often prevented accidents. However, since we started using AGVs, it has become impossible to ensure smooth operations between our logistics systems. It was clear that we had to find a solution that would allow both tugger trains and AGVs to cross safely." The system had to be designed to stop vehicles at any time when others crossed their path.

A profitable partnership despite the pandemic

Based on the requirements of Volkswagen Autoeuropa, Siemens teamed up with Introsys S.A. to develop a system that represents the most secure, highly available and reliable production network possible. The result is an international collaboration between Portuguese and German engineers and technicians from Volkswagen Autoeuropa, Siemens and Introsys.

Siemens provided hardware, software and expertise in the field of real-time location systems. Introsys built on this with its know-how in development and programming and ultimately implemented the system. Throughout the process, COVID-19 was a constant challenge. Most of the development and implementation work was done under the pandemic-related restrictions. Diogo Graça says: "Everything was implemented during the 2021 summer lockdown. And in addition to the restrictions imposed by the pandemic, getting the technicians from Germany to Portugal was also a challenge."

© Siemens

"The work during the pandemic was particularly difficult, especially in the early stages of the implementation phase when the majority of the workforce was working from home - you had to remotely control the installation of the hardware (gateways, transponders, etc.) on site and also obtain all approvals and signatures to keep the project moving forward."

The game-changing combination: ultra-broadband gateways and real-time tracking software

Nelson Alves, automation engineer at Introsys, was one of the engineers tasked with integrating the system into the factory. He particularly emphasizes the importance of the specific choice of gateways: "The wireless positioning network had to be placed on the factory floor and in the production area, where countless WLAN networks and automated machines are working in parallel. The reason why ultra-wideband gateways (UWB) from Siemens were chosen is that they can be operated without interference in the given environment. The gateways operate in a completely different frequency range. This is important because any disruption to the traffic of tugger trains or the AGVs would result in a production stop."

So the UWB technology was the crucial point in this project. But what about the rest? How did you teach an AGV to "cross the road"? At this particular intersection at Volkswagen Autoeuropa, where this software solution was first tested, there are currently around 15 AGVs in operation - and the number is growing.

The hardware from Siemens, i.e. the RTLS4030G gateways and the RTLS4030T and RTLS4060T transponders on the vehicles, was the most important part of the solution alongside the location intelligence software. This made it possible to install geofences that track the movements of various vehicles in real time and optimize the processes and routes in plant logistics. © Siemens

According to Nelson Alves and António Ascenção Castro, Digital Connectivity Engineer at Siemens, everything depends on continuous commands as to whether the AGV should move or not. They have neither optical sensors nor optical detection of traffic lights. They are guided solely by the geofences, which act as an alarm when an object crosses the area. The data is read by the system and a command to stop is sent to the AGV.

The gateways had to work perfectly and the software had to be extremely reliable. The hardware from Siemens, i.e. the RTLS4030G gateways, as well as the RTLS4030T and RTLS4060T transponders on the vehicles, was one of the most important aspects of the project, alongside the location intelligence software. This made it possible to install geofences that track the movements of various vehicles in real time and optimize the processes and routes in plant logistics.

What had to be developed from scratch? According to Nelson Alves, all the necessary tracking and communication technology had already been developed by Siemens. However, the programming for all the specific systems at Volkswagen Autoeuropa had to be developed from scratch. Every second, around ten status messages were exchanged between all controllers and platforms, which were integrated into the real-time tracking system. António Ascenção Castro sees the result of this project as a prime example of cooperation between local and international partners: "The cooperation between Volkswagen Autoeuropa, our customer, and Introsys, who worked together on the solution, has shown how well it can work. Without a doubt, our i-Experience Center partner network was essential for the successful implementation."

How quickly did the staff get used to the new solution?

A good solution is one that everyone understands quickly. And according to Diogo Graça, that is exactly what was achieved: "Within half an hour, every movement at this junction was orderly. As soon as the workers understood that the traffic lights worked, traffic was efficiently regulated. In fact, the innovations made more sense than expected: The workers were pleasantly surprised and welcomed the traffic management system as a new entity to control vehicle movements - immediately noticing the increased safety when passing through this area."

A virtual map and data analysis can be used to optimize routes and control traffic lights. © Siemens

Employees at the plant confirm that the situation has improved noticeably. Before the real-time location system, crossing lanes here was disorganized and predestined for accidents. In the meantime, however, the general opinion has changed to the effect that it is now safe to cross the same spot. In addition, it was immediately possible to control the quality of all movements on the routes. All in all, the collaboration between Volkswagen Autoeuropa, Siemens and Introsys was a far-reaching success.

Ultimately, Volkswagen Autoeuropa has gained a new solution to make production processes more efficient, safer and, in future, faster. From now on, there will be significantly fewer, if not no, accidents at this junction. Introsys says: "The feedback from our customer has been excellent and they plan to expand this solution even further." In fact, requests have already been made to implement this system in other logistics areas of Volkswagen Autoeuropa, such as the automatic unloading machines in the warehouse.

Future developments: the direct route to data analysis

The greatest potential for further development that this solution with Simatic RTLS brings with it lies in the data it produces. This raw data can be evaluated and interpreted by many different analysis tools, making it possible to monitor and control the system. In addition to testing simulations, routes can be planned, rerouted and changed - virtually instantly and with just one tool.

António Ascenção Castro and Nelson Alves say: "The analysis of the data collected in the system can be applied to all types of vehicles: Cleaning trolleys, support vehicles - even bicycles used inside the factory. The tracking tools on these vehicles continuously collect simple but very valuable data." A speed limit has also been introduced on the factory site thanks to the real-time tracking system.

The assembly line works according to the just-in-time principle, so it is extremely helpful to know which parts are where at what time. The ability to suggest alternative routes to vehicles if necessary can also have a positive impact on the flow of materials. As long as the necessary ethical issues relating to the use of the data are clarified, the potential of this data analysis for management purposes is unlimited.

Author: António Ascenção Castro, Digital Connectivity Engineer, Siemens

www.siemens.de/rtls