Real-time Location at Your Service
Location data has its place: Helping virtualize process control in high-mix, high-volume assembly operations.
Manufacturing is an exercise in controlling movement. Materials, parts and assemblies. Equipment. People. Equipment can transmit digital signals to update where they are in a process and people can log in to a facility and an operation. But those first three items?
“There is a direct correlation between where you are on the production line and where you are in a process,” explains Adrian Jennings, vice president of technology for Ubisense Inc. (ubisense.net). This is one of the bases for real-time location systems (RTLS): Knowing where, for example, a car assembly is in the production line tells the liveware (workers and management) and the software (the manufacturing execution system, MES) where that assembly is in production.
However, RTLS is hardware-intensive. Rebalancing a production line to accommodate new vehicles, new processes or new efficiencies is often a hassle. “By doing away with fixed ID infrastructure,” continues Jennings, “customers can significantly reduce the cost of line rebalancing—the continual process-shuffling burden that always has engineers working weekends.”
How to do away with hardware infrastructure? Virtualize it!
Manufacturing’s Game of Tag
Ubisense Smart Factory combines radio frequency (RF) tags and advanced sensors with manufacturing-oriented software. The system gathers location and other process data from around the plant, then it correlates real-time process interactions with operational details. Smart Factory can accurately identify and locate in real-time materials, parts and assemblies, tools and other process-related assets. It can also provide adaptive process control by downloading work instructions, alerts, triggers and other data to production machines, tools and other devices. These capabilities, says Jennings, “help manufacturers sustain continuous flow, optimize efficiency and reduce errors in manual assembly processes.”
In a way, Smart Factory is much like an MES. It monitors processes, triggers alerts, controls tools and machinery and analyzes data that lead to process improvements. What’s different is the emphasis on RTLS: Smart Factory focuses on location data to trigger process control.
“It’s all in the angles,” quips Jennings. Ubisense RF sensors measure not only the time for a pulse to return from a tag (time being a function of distance), but also the angle of arrival. Two angles, in fact: up and down (elevation) and left and right (azimuth). The resulting location data are precise: Ubisense claims it can track and locate tagged assets to within 6 inches. Such accuracy lets customers significantly reduce the number of sensors required to capture RTLS data, which in turn significantly reduces the cost of the product identification infrastructure.
Smart Factory includes several modules. Explorer allows people to find and identify any product or asset throughout the plant using a web-based, interactive and graphical map. Operations Center is a process monitoring and reporting tool. Process Improvement applies real-time location data to reporting, analytics, and process performance metrics.
Regarding virtualization, Ubisense Smart Factory Assembly consists of Smart Device for error proofing and adaptive control, and Virtual Station for flexible identification. The latter module uses “virtualized vehicle identification triggers” to initiate new tasks, processes and workstations, or move, even remove, existing tasks, processes and workstations during line rebalancing. In other words, software is used to define work zones around an assembly moving through production. This virtualization decouples processes from a fixed work area and helps in managing the complexity in high-mix, high-volume assembly.
For example, many car assembly plants tether their tools so they operate within a specific workstation. The tether ensures the tool can’t be physically moved outside the workstation. One large U.S. automaker uses Ubisense Smart Factory Assembly to control wireless tools: not only their location, but also how they operate. By knowing the location of tools and assemblies, Smart Factory ensures the right tools operate on the right car body coming down the line.
Get Real with Virtualization
Virtualization also simplifies, if not eliminates, the cost and management associated with relocating and rebalancing process identification points, tool use and traditional fixed workstations. “Once virtualized, the workstation can vary in real time to product variation, task overrun, and many more plant variables,” says Jennings.
Consider, for example, the varying times to perform a certain task on different car models moving through a work area. In a conventional assembly operation, the line is stopped if a task is not completed before the assembly leaves the appropriate workstation. Says Jennings, “It’s very difficult to jam tons of variations into the notion of an assembly line, that notion being every workstation is a fixed entity, has a fixed and physical start and end, and the line runs at a fixed speed.”
Smart Factory Assembly blows that all away by allowing “a degree of flexibility in order to manage the degree of variability,” continues Jennings. Different cars coming down a single assembly line may have a slightly different “bubble” zone in Smart Factory—a zone that “knows” about the variances in assemblies, work instructions, material requirements, tooling and so forth. The system detects the status of the work being done and the position of tools, then it makes simple but intelligent decisions about whether more time is needed to do the work.
This level of flexibility can’t be done mechanically—at least not in an affordable way. This is where digital technology comes into play. “The magic is that the variability is completely adaptable on-the-fly,” says Jennings.
Imagine having an idea that is transformed without a whole lot of modification into a series of cars rolling off the assembly line. BMW's Anders Warming is one of the few who have had that experience.
Although “Detroit” is synonymous with “automotive production,” the only major OEM that actually manufactures vehicles within the city limits is Fiat Chrysler Automobiles, as it runs the Jefferson North Assembly plant in Detroit, where the Jeep Grand Cherokee and the Dodge Durango are built.
Several years back, one of the authors visited a major North American assembly plant engaged in the launch of a new vehicle program. A "ramp-up" schedule was prominently displayed on a bulletin board deep in the heart of the plant. The schedule indicated that the day of the visit was the same day the plant was originally planned to achieve full capacity production of its new product. Yet the plant was actually producing only a few units an hour! The assembly plant's tardiness is certainly not uncommon, but did contribute to our interest in the wide range in vehicle launch performance across major vehicle firms.