Produktion

“Prediction thanks to real time”

The current and soon-to-be-expected benefits of real time in production control as explained by  Dr. Günther Schuh.
Author: Heinz-Jürgen Köhler
Photos: WZL/Krentz


Prof. Günther Schuh holds the Chair of Production Systematics and Production Management and is Managing Director of the WZL Laboratory for Machine Tools and Production Engineering at RWTH Aachen University. He founded StreetScooter GmbH, which produces e-transporters, and e.GO Mobile AG, for e-cars, where he is still CEO today.

What does real time mean in production control? 

To begin with, we are talking about relative real time. And that depends on the specific requirement. There is an abso lute real time created by the transmission rate of signal processing and that is in the millisecond range; however, in production control we often do not need that at all. For production planning – which is weekly – a delay of 10 to 30 minutes is typically very tolerable. For assembly control, however, it cannot exceed 30 to 120 seconds in order to be able to respond to disruptions accordingly. With cutting machine tools, on the other hand, it would be good even to find out within milliseconds when machining goes off the rails. 

What requirements need to be met for this? 

To start, I need to learn to see digitally. This pertains to the individual sensor: Does it work optically, with a camera using image recognition or even using radar? Then I need to learn how to interpret what is seen. This means how can I combine the sensor data into a single image, a digital shadow of production? To do this, I need to establish networks at various levels. In each machine tool, I combine sensors and actuators; at the shop floor level, I merge the various systems. How quickly I do that is also a question of telecommunication. 5G will certainly make a lot of it go faster.  

What are the advantages of real time production control? 

In the broadest terms, it helps to avoid the two greatest obstacles to productivity: waiting and searching. It allows me to have complete control of the control loops of my production. I know the statuses of my machines and I know where the parts are located. This affects the entire supply chain. It also increases my OEE, or overall equipment effectiveness. Now I only have productive employees and no longer need troubleshooters. When there is no more searching and waiting, the work atmosphere also improves. The employees are no longer interrupted and can work at their own individual pace. Real time capability is also important for making predictions. When I compare the current situation with past experience, I can recognize patterns and make predictions. In this way, you could predict up to 90 percent of all disruptions. 

Is this kind of production control a topic for the future? 

If you want to know whether this kind of control is widespread: no. If you are asking whether it can be now: absolutely! All of the necessary technology is there, it just has to be utilized. In our production of the e.GO, we have real time control with a delay of one to two minutes. And this despite the fact that a lot of assembly is done by hand. There is absolutely no reason not to immediately introduce this kind of control into every type of production. The excuse of waiting for 5G, i.e., that it does not work with 4G, is unacceptable to me.