Toyota tackles 2nd generation RFID
Some companies are simply exploring radio-frequency identification technology, but Toyota recently replaced 10-year-old Radio-Frequency Identification (RFID) tags and readers and, as a result, it gained a state-of-the-art data acquisition system tied to PLC-5 controllers. Chris Huff, of Encompass Partner, Escort Memory Systems, explains.
RFID isn’t a new concept to the people at Toyota – nor is it new to Rockwell Automation. More than 10 years ago, Allen-Bradley-brand active tags and RFID readers were installed in the paint and production areas of Toyota’s massive Burnaston plant, which is in the British Midlands. This plant, which makes Corolla and Avensis models for sale worldwide, produces 220,000 vehicles a year.
The need to keep the production process on schedule was of utmost concern to Toyota management.
EMS has history with Toyota. Facilities in France and South Africa have implemented EMS RFID systems to track engine/parts production and painting. Such a history, coupled with the fact that an EMS RFID system would interface directly to Allen-Bradley PLC-5s at the plant, made EMS an obvious choice.
The switchover process to the RFID systems had to be seamless because Toyota was in the middle of launching two new Corolla and Avensis models. The need to keep the production process on schedule was of utmost concern to Toyota management, and replacing the whole system in one fell swoop was considered too risky because of the possibility of losing data or impacting the production line. The project team tasked with this job comprised representatives from Toyota, EMS and DataScan Systems, a UK-based systems integrator.
Those first-generation active tags had limitations that newer technology has overcome, such as a data limit of 40 bytes per tag, a maximum operational temperature of 60°C and a life of only 5,000 write cycles. The intense environmental conditions of the paint booth and production line – including heat, dirt, oil and grease – and the tendency for a tag to get scraped or bumped meant durable, high-temperature tags were essential. Five-cent “commercial tags” just would not do. EMS LRP250HT high-temperature tags offer 48 to 112 bytes of memory and support 100,000 read/write cycles over their lifetime. The tags are capable of operating in prolonged exposure to heat in excess of 200°C.
The cylindrical ceramic spacers above the tag (above) reduced Interference by separating the tag from the metal dolly. The antenna mounting bracket (below) accomplished the same thing and held the antenna at the proper angle.
The EMS LRP250HT tags were attached, side by side, with Allen-Bradley active tags on the dollies heading through the paint ovens, and the same information was written to each. This doubling up of technology ensured tag validity while allowing each station to be commissioned independently. This approach also allowed methods to be tried, tested and then reworked if necessary – without having to change up every station after the switch.
Mounting the tags to the metal dollies required a special solution. Like all RFID, metal interferes with the read/write range of the tags. With this in mind, a ceramic spacer – originally co-developed by EMS and US-based General Machine Technologies – was used in conjunction with a small metal bracket to separate the tag from the dolly.
The Reader/Writer conveyer antenna chosen for this application was the EMS LRP820-04. The remote antenna for this reader was designed to fit into tight areas surrounding or within a conveyer line. Using the LRP250HT tags with this antenna, a six inch range is guaranteed– sufficient for this application. Mounting the antenna required some creative thinking, too. Space constraints were a major issue because the amount of room underneath the dollies was minimal. Also, if these extremely heavy dollies ran into a mounted antenna or tag bracket, the RFID technology would be crushed. The solution: a bracket that raised the antenna approximately 2 to 3 inches off of the metal floor to reduce interference.
Toyota is currently using 39 LRP820-04 Reader/Writer controllers and antennas. More than 20 EMS CM52 interface modules are used to link the system to both the PLC 5/25 and the PLC 5/40. The final piece of technology EMS supplied for this application was the LRP7400 Hand-Held Reader/Writer. Vehicles in the early stages of the production line have model, colour and assembly information written to the tags on their dollies using the LRP7400. The tag information is accessed and written to again at each of the stations where it passes over the LRP820-04 antenna.
Encompass Partner Escort Memory Systems, a Datalogic Group Company, is recognised for high performance, highly connected and rugged RFID hardware that sets the standard for industrial RFID.
DataScan Systems Ltd. is a systems integrator in the U.K. focused on solutions using Auto ID technology.
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