Food for the Digital Twin

Why do companies continue to move ahead with the digitalization of their processes? The answer is because they want to improve their position in the global competitive field by flexibly adjusting production in line with new customer requirements, implementing a broader-based manufacturing program without increasing costs, and enhancing the quality of the products they manufacture. At the same time, many processes, especially those involved in production, are already highly automated or can hardly be performed by robots alone. The use of an intelligent and effective location system makes it possible to achieve a further competitive edge through digitization in this regard as well.

 

by Markus Weinländer

How can a manufacturing facility be made better and more flexible, yet also less expensive to operate? Production engineers are developing new concepts for more effectively exploiting the possibilities offered by digital twins, which are computer-generated replicas of all processes and production objects. Such an approach calls into question the traditional flow production line – a production method which for many years led to a sharp decline in unit production costs. However, the production line proves to be inflexible and costly when rapid production adjustments need to made or certain variants need to be manufactured at special processing stations. That’s why new concepts focus on automated-guided vehicles (AGV) rather than fixed conveyor technology. In this setup, workpieces are conveyed from one processing station to another by transport vehicles. The advantage here is that specific segments can simply be skipped for simple variants and low-priority manufacturing work can be suspended at any time. If a machine is consistently overloaded, a second machine is simply added to the process and the AGVs then supply it dynamically with workpieces as needed. 

Radio-based location systems that record all object movements in real time and send the corresponding data to a control system and individual AGVs form the foundation for this type of flexible production. Simatic RTLS (Real-Time Locating System) from Siemens is one example of such a location platform. RTLS sends data to AGVs on their own position and also provides destination coordinates, which means it can navigate vehicles to the right processing machines dynamically, taking into account current machine capacity utilization and the priority of specific production jobs. In addition, Simatic RTLS uses a structure in which anchors, or location points, are installed in a factory at regular distances from one another, thus creating something akin to a Wi-Fi network that covers the entire production area. All of these anchors locate the transponders mounted on robots, AGVs, workpieces, and machines. They determine these positions within fractions of a second and use a gateway to send the coordinates to the locating manager, which then forwards the data to the target applications.  

Invisible Support for Workers

Digital concepts can also support what at first appears to be a contradictory objective, namely lowering the degree of automation. Specialized workers are still used in many production steps, especially to mount components, because such operations are too complex for robots to perform. The advantage here is that a human can work on many different components without having to undergo special training each time or be guided by sensors (e.g. cameras). Humans also make mistakes, however. They might mount the wrong component or use the wrong torque to tighten bolts – mistakes that robots are extremely unlikely to make. 

The location system also offers another important benefit: it can be used as infrastructure for a large number of applications.

A location system like Simatic RTLS can provide assistance here as well by comparing processes that are actually being carried out in the factory with the digital twin of the product that’s being manufactured. This makes it possible, for example, to automatically set a torque wrench by means of the three-dimensional location of the tool. This is done by having the wrench control “superimpose” this position over the digital model of the product in question in order to identify the specific bolt that’s being tightened. All of this happens in real time without any intervention by a worker, which means the digital control system accompanies the processes without the processes themselves being altered in any noticeable way. The digital twin thus provides invisible but also extremely helpful support to the worker. In addition, RTLS sends additional data to the production system’s digital twin for purposes of documentation. 

 

The location system from Siemens also offers another important benefit, however, as it can be used as infrastructure for a large number of applications – in the same way as communications networks, which also support many different applications. In this way, Simatic RTLS makes it possible to implement various logistics processes for production facilities. If a worker uses a glove equipped with an RTLS transponder, for example, the RTLS system can monitor the materials used at an assembly station, and if the worker accidentally removes material from the wrong shelf, the system will issue a warning. If mobile production materials such as tools, carriers, or containers are equipped with transponders, data on their actual utilization and turnover rates can be used to optimize inventories by either making additional parts available at neuralgic sections or reducing the number of stored parts that are used infrequently. RTLS can also seamlessly track the progress of a workpiece in order to automatically document individual processing steps and successively add the corresponding data to the digital twin.

 

Whether it’s AGVs and robots, or experienced specialized workers – the real time radiolocation system from Siemens makes it possible to reliably implement new production concepts by having the automatic radiolocation feature establish a bridge between digital twins and the analog products and systems they’re based on. In other words, RTLS and similar systems will pave the way for the dynamic, flexible and, above all, competitive factory of the future. 

2018-11-21

Markus Weinländer

Picture credits: Getty Images

 

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