Automobile manufacturer Volkswagen Slovakia is tracking its assembled vehicles as they undergo final servicing and inspection processes at its plant in Bratislava, using a real-time location system (RTLS) provided by Identec Solutions. The RTLS solution makes it possible for the company to improve efficiency during the cars’ final production stages, by knowing where individual vehicles are located, as well as preventing bottlenecks at specific service sites. The system enables the company to locate parked vehicles, in addition to identifying when a car enters and exits each of many processes.
The Bratislava facility produces more than 1,400 cars daily, with 400,000 automobiles planned for this year, including several Volkswagen models, as well as Audis, the Skoda Citigo and the SEAT Mii. The plant, which has experienced an increase in production demand during recent years, determined that improving its finishing area’s efficiency would help manage that growth.
After completing assembly, a vehicle is moved to the finishing area, where it travels through a number of stations while undergoing final quality inspections, as well as possibly spot repairs or other servicing. The precise order or sequence of those processes varies per vehicle. As such, locating particular cars when needed—as well as routing them to the proper area based on prior servicing, and ensuring that the vehicles remain on schedule for shipping—can be a time-consuming process. The RFID system was intended to resolve that problem, by tracking the processes that each vehicle has completed, as well as its specific location as it waits within parking areas between processes. The solution would not only help staff members locate vehicles in real time, but also improve capacity planning for each section of the finishing area.
“Because of the topology of the hall,” says Jens Wieland, Volkswagen Slovakia’s chief process officer (CPO), the company determined that it would be impossible to implement a solution based on passive RFID tags and readers consisting of gates through which the cars had to pass. The Volkswagen plant required a system that would track every vehicle’s entrances and exits at any of the processing zones and parking lots. For that reason, the company deployed a solution employing active RFID technology.
The installation of the RFID infrastructure commenced in May 2011, Wieland says, and was completed in approximately two months. The firm then began testing the technology in October, before transitioning to a full installation.
When a vehicle leaves the production line, it enters the finishing area, where it comes off the conveyor track and can be driven independently to as many as 15 different zones, in order to undergo various procedures or tests prior to shipment to a customer. At a section of the assembly area known as the “cloning station,” a worker affixes an Identec i-Q350 tag to the inside of the vehicle’s windshield, near the rear-view mirror. The car already has a passive RFID attached to it that is used during assembly, and the i-Q350 tag is read at the cloning station, along with the passive one, to link the new tag with the car’s details in the software residing in Volkswagen Slovakia’s CrossTalk management software, supplied by noFilis. Within CrossTalk, the tag ID is linked to the car’s vehicle identification number (VIN), along with any other details, such as its color and make. The CrossTalk system then enables the company’s management to track a particular automobile’s location, search for a specific vehicle or type of vehicle, and receive an alert to prevent a tag from inadvertently leaving the facility.
The i-Q350 tag, powered by a lithium battery, transmits an ultrahigh-frequency (UHF) signal that can be received by Identec i-Port M350 readers located up to 500 meters (1,640 feet) away, thereby providing 100 percent coverage of the plant’s finishing area. The tags also receive active RFID-based location data via a 2.45 GHz signal from i-SAT reference nodes situated in the parking area, as well as 125 kHz signals from i-Mark position markers, indicating when they enter and exit a location.
As the vehicle enters a servicing area, such as a tunnel location where paint is tested, it first passes an i-Mark 2 or i-Mark 3 position marker, which is typically integrated into the floor over which the car travels, or affixed to a wall or overhang. As the tag passes an antenna wired to a position marker and detects the 125 kHz signal transmitted by that marker, it awakens and then receives and stores the marker’s ID number. The tag forwards that number, along with its own ID and a timestamp, to the closest i-Port readers, thereby indicating its whereabouts. While departing a specific servicing location, the vehicle passes another i-Mark position marker and captures its ID, forwarding that number to the system.
At the open parking area, the tags also receive 2.45 GHz signals emitted by i-SAT 300 RTLS reference nodes up to 100 meters (328 feet) away. The nodes and the tags measure the distance between them, and the tags then send that information to the back-end system, where Identec’s i-Share software employs a triangulation algorithm to calculate the vehicle’s exact position within a few meters. That data is then updated in the CrossTalk software.
Before a vehicle exits the facility, its i-Q350 tag is removed. If staff members forget to detach it, the tag is activated by an i-Mark position marker and transmits a signal that is interrogated by an i-Port M350 reader portal at the exit, at which time the Identec software triggers the illumination of a warning light that prompts employees to stop the car and remove the tag.
The software enables Volkswagen Slovakia to locate a specific type of car when it is needed, as well as track the quantity of vehicles within specific service zones. In that way, the company can better manage the flow of automobiles through the servicing zones, thereby increasing operational efficiency.
Part of the process of testing the system involved determining the tag’s proper positioning on a vehicle in order to ensure accurate reads. Volkswagen Slovakia ascertained that mounting the tag on the upper middle portion of the windshield resulted in the longest read range.
The environment posed several challenges, Wieland reports. The company strives for a location accuracy of 2 meters (6.6 feet). “Since we have a lot of steel in the hall, and modernization work on facilities is almost ongoing business, we are facing issues based on signal reflection, which resulted in non-accurate location measurement,” he states. “Luckily, a car is big enough to find, even if the accuracy goal of 2 meters is not reached in some cases.”