Go with the flow

Just days before I'll Have Another won the Kentucky Derby, I visited the 20-year-old Toyota Motor Manufacturing Kentucky (TMMK) plant in Georgetown for a firsthand look at the buzz about a vehicle-mount AGV control system.

Toyota industrial tow tractors outfitted with AutoGuide AGV systems (www.autoguideagvs.com) had taken over parts conveyance in the body weld department at TMMK, supporting the facility's long-running track record for superior quality, flexibility and annual cost reductions.

To see some video footage of Toyota's AGVs at work in the plant, check these out:

Now, onto the story. Kaizen is a constant at any Toyota plant, and TMMK is the North American mecca for kaizen, a key element of the Toyota Production System (TPS). It is a philosophy demanding nonstop productivity improvements and cost reductions.

TMMK employs more than 6,600 people.  “We have to remain competitive in a global market,” says Paul Stafford, TMMK production engineer and automated guided vehicles (AGV) project lead. Production processes had been kaizened and were nearly as efficient as they could be, but conveyance of parts and subassemblies had not been as closely scrutinized. AGVs in the TMMK body weld department have provided fertile ground for cost savings.”

To realize such savings on one project Stafford’s team worked with several technology and equipment partners on the processes for transporting stamped parts to the robotic welding stations. AutoGuide Systems retrofitted 22 Toyota 24-V, AC-drive industrial tow tractors, in effect converting a standard industrial truck into an AGV.

“Adding automation to an industrial truck provides built-in durability and readily available replacement parts,” says Tim Meyer, AGV product manager for Toyota Material Handling U.S.A. “The setup generally gets away from black box technology and allows users to take ownership and manage the AGVs much more cost-effectively.” The vehicles also can be run manually when the automation and control need to be overridden.

AutoGuide equipped the 10,000 lb-capacity tow tractors with obstacle sensors, guidance sensors, radio frequency modems, and RFID tag readers. A touchscreen PLC interface was included for programming on the plant floor during installation. AutoGuide used the same off-the-shelf sensors and devices installed on other AGVs in the TMMK plant. These units share the same magnetic guide pathway. Standard hardware made it possible for the installation team to use common control methods when setting up and testing the new system.

Industrial Concepts (ICI, www.ici-ky.com) worked with the TMMK AGV implementation team to develop custom traffic control technology. The automated vehicle intersection navigational utility (AVINU) system monitors the activity of each AGV and reports its location and performance, which can be checked on any authorized PC in the facility. The system also monitors battery charge, assigns available AGVs to loads, and regulates traffic at AGV intersections.

“Spaghetti junction is what we call it,” says Stafford. “There’s a 300-ft main highway with nine different routes branching off and merging into it. In some places the Toyota AutoGuide AGVs are clearing the back end of a dolly or snaking around equipment with 6 in. of clearance or less.”

The AGVs tow up to five racks of parts stretching 45 ft long to the robotic welding cells, a 1,900-ft round trip. Because the Georgetown plant has been in operation for more than 20 years, the distances between manufacturing processes aren’t as close as they are in newer Toyota facilities. In addition to the longer travel distances, the interaction between AGVs and other traffic can be high. In the past, these challenges sometimes contributed to issues. When Toyota associates delivered the parts using manned tow tractors, the parts in the cassettes and racks would bang up against each other. The use of automated Toyota tow tractors has eliminated those issues.

And there’s more to the story. Stay tuned for Part II, where I’ll explain some of the positive effects the system has had at TMMK.