Imagine walking into a material handling equipment maintenance and repair shop, pulling standard components off the shelf, and—with relatively little time and effort—turning an ordinary industrial tow tractor or forklift into an automatic guided vehicle (AGV).

That day isn't here just yet, but it's closer than you might think. An automation project at a Toyota auto manufacturing plant in Georgetown, Ky., has shown that it's possible to retrofit some types of manual equipment quickly and easily, earning a big return in terms of cost, labor, efficiency, and flexibility. Although the project involved a manufacturing environment, it may well serve as a prototype for bringing more AGVs to material handling environments, where they have yet to make major inroads due to their cost and complexity.

TOW TRACTOR TRANSFORMATION
Toyota Motor Manufacturing Kentucky Inc. (TMMK) makes the Camry, Venza, and Avalon models at the Georgetown facility, a 1,300-acre complex encompassing some 7.5 million square feet of manufacturing and assembly space. Like all Toyota operations, the Georgetown plant adheres to the Toyota Production System, also known as "just-in-time" or "lean" manufacturing.

Over the years, Toyota had honed production at the Georgetown plant to a high level of efficiency. But there was still room for improvement when it came to the internal movement of parts. The factory, built in 1988, is not as compact as newer facilities. As a result, workers delivering materials to the body-weld department had to drive long distances, navigating congested areas to drop flow racks and palletloads of parts at work cells. Sudden stops, complicated workflow paths, and the occasional traffic jam or collision led to product damage and delayed deliveries.

A team assigned to study the problem determined that automating the transportation of parts to the 1 million-square-foot body-weld area—in essence, taking human drivers out of the equation—would eliminate most of the delay and damage problems. Their conclusion may not be very surprising. What is surprising is the way TMMK accomplished that objective: Instead of purchasing new equipment, the factory chose to retrofit 22 of its Toyota 24-volt, AC-drive tow tractors with locally built automation kits that turned them into automatic guided vehicles.

To develop these "home-grown" AGVs, TMMK worked with two local business partners—AutoGuide, an automation specialist led by AGV innovator Paul J. Perry, and Industrial Concepts Inc. (ICI), a developer of custom machinery and control systems whose president, Tim Taylor, is a former TMMK mechanical whiz. (AutoGuide and ICI are closely allied; the two share a facility across the street from TMMK, and ICI's executives have an ownership stake in AutoGuide.)

Utilizing the same off-the-shelf devices already in use for other types of AGVs at TMMK, AutoGuide outfitted the 10,000-pound-capacity tow tractors with obstacle and guidance sensors, radio-frequency modems, RFID tag readers, and a touchscreen programmable logic controller (PLC) interface, among other technologies. All of the components are contained in a removable attachment designed by AutoGuide. Installation is a simple matter of drilling six holes in a tractor's chassis, and is the only physical change required, according to Tim Meyer, Toyota Production System solutions and AGV product manager for Toyota Material Handling U.S.A. Inc.

Flexibility was another reason TMMK chose to convert standard, manual equipment to AGVs. The stand-alone attachments can be installed either at the time of purchase or lease, or after the vehicles go into service, and they can be easily removed and reinstalled on other vehicles, Meyer explained during a tour of TMMK. Drivers can switch the tractors from automatic to manual mode simply by stepping on a pressure-sensitive mat in the driver's compartment.