By Nicole Lauther, Head of Business Development SIMATIC RTLS, Siemens Industry, Inc.
The complexity of increasingly automated industrial plants and modern supply chains requires intimate knowledge of the operation and location of digitized assets. Questions that must be answered include, “What’s where, when?” and, even more importantly, in terms of worker safety, “Who’s where, when?” Yet precise answers to these questions can be hard to find.
Failure to know this information can be the downfall of many sophisticated systems being incorporated into the industrial landscape. Take the case of digital production twins that use real-time operating data from sensors and machines to reflect the current status of physical plant operations. To be of real value, they need to track the location at any given time of the many physical objects and people on a plant floor. Barcodes, RFID, and video surveillance, of course, can help. But their limitations have inhibited the realization of the smart factory. What is needed is real-time, end-to-end tracking and visibility of raw materials, work-in-progress, finished goods, tools, and the people involved throughout the entire production cycle.
This lack of visibility can have serious consequences. A feedstock assignment error, for example, can compromise output quality, reduce machine utilization, and stop production. This can force large amounts of work-in-progress to be scrapped and production lines restarted at enormous costs. Misplaced tools, for example, until they are found, searching for them can waste expensive plant labor and consequently hold up production. The level of automation on the plant floor has reached the point where it is no longer acceptable to have a rough idea where things may be. After all, life safety can be at stake if automated guided vehicles (AGVs) or other mobile robots end up in the wrong place at the wrong time. Workers need to feel confident that their safety won’t be compromised due to material movement in work areas.
The intelligent factory, then, calls for complete synchronization of everything and everyone in real-time. Control systems must be able to autonomously sense and respond to the changing dynamics on plant floors. These capabilities are especially needed for the self-organizing factories of the future.
Fortunately, the tools now exist to realize this vision. It incorporates technology that can complete a digital production twin’s picture by providing full tracking capabilities for physical objects and personnel anywhere in a plant or its surrounding premises at all times.
Known as SIMATIC Real-Time Locating System (RTLS) solutions from Siemens, it harnesses ultra-wideband (UWB) wireless and triangulation techniques to enable full location awareness. UWB transponders can locate objects and people equipped within inches with latencies of less than 1 second. Higher-level systems such as MES and ERP are fed a stream of ever changing data points related to motion, acceleration, elevation, and orientation from the RTLS system. This enables factory automation systems to make the right decisions about operations as the who, what, where, and when are known with precision. The result is a substantial boost in plant efficiency while maintaining personnel safety.
How does it work? The SIMATIC Locating Manager software is able to calculate the position of each transponder by a method called Time Difference of Arrival (TDOA). Accuracy is further increased using flanking measures such as automatic correlation of position data with the 3D model of the product and production environment stored in the digital twin. TDOA also helps extend the life of transponder batteries, ensuring reliable function over several years.
With a frequency range of 3–7 GHz, UWB uses a bandwidth of at least 500 MHz to transmit low-energy wireless signals that can still provide short-range communications for location purposes. This is achieved without interference with other wireless systems in plants, warehouses, or operating yards. Little or no RF engineering is required during installation. The RTLS solution can be integrated into IT and Automation Systems.
The SIMATIC RTLS portfolio features four interworking components:
- Transponders act as active UWB transmitters that are fitted to material containers, workpieces, robots, AGVs, forklifts, work badges, or attire.
- Anchors are usually wall-mounted and record transponder signals They serve as reference points for the localization calculations. At least four anchors are used to mark the transponders’ UWB signals with a fixed position and time stamp.
- Gateways collect the recorded data and transmit it to the Locating Manager server. They feature an interface for IT network connection. Localization data and optionally application-specific data can be exchanged between the wireless localization network and the localization server via the IT infrastructure
- The Locating Manager is server-based software that calculates the real-time position of individual transponders and relays the data to higher-level systems. A rules engine defines specific events and locations and configures higher-level system responses, such as alerts and action commands.
Extensibility to cloud-based platforms such as the Siemens MindSphere open IoT operating system can be rapidly implemented and tailored to specific industries. A complete enterprise-wide view across multiple plants and continents can be achieved via MindSphere.
This changes the game on plant floor operations and logistics. Location data can be used by a MES to trigger a production step or execute an order to deliver more feedstock to production, while notifying the ERP system to decrement inventory numbers and if levels have fallen below par stocks, to order more from the supplier. RTLS data can be used for fleet management of moving vehicles, such as forklifts, AGVs, and other mobile robots. Engineers can utilize this information to improve the availability and utilization of assets. Continuous monitoring of goods reduces waste and improves traceability. Container utilization rates are improved due to the accurate management of their location, availability, and assignment. Reduced costs, more efficient processes, improved productivity, higher quality, and optimized maintenance are among the many other benefits.
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