7 fresh ways to think about AGVs
Using automatic guided carts (AGCs) as continuously moving assembly lines at an automotive assembly plant offers flexibility in operations.
September 01, 2012 - MMH Editorial
Unfortunately, for the next few decades it was the bane of the materials handling family. It was expensive (costing $100,000+ per unit), inflexible (could only go one fixed path using wires), not very smart (drop a pallet in its path and it stops) and had a bit of a weight problem (heavy batteries with hefty platforms). It was relegated to menial tasks mostly in manufacturing, carrying loads or towing carts from Point A to Point B.
As a value proposition to displace human beings, yesterday’s AGVs had a long way to go. “Human beings are the most sophisticated robots the world has ever seen,” says Bill Torrens, director of ADAM Systems Group for RMT Robotics. “If you really want to displace the labor associated with a human being, you’ve got to mimic its operational capability.”
So AGV suppliers changed their focus, gearing their development emphasis on characteristics of robotics that would best duplicate the functionality of human activity. Over the past decade, everything from batteries, circuit boards, traffic management software and sensors not only became more intelligent and reliable, but also significantly less expensive. The vehicle underwent a few makeovers—and added a few acronyms. (Read story: Equipment 101: AGV Basics)
One version has it stripped down to a light duty platform, guided by more flexible, easy-to-change, magnetic tape on the floor. This version, christened automatic guided carts (AGCs), now costs as low as $15,000 per unit and is able to carry loads up to 6,000 pounds.
There were simultaneous new developments in navigation and guidance. Gone are wires: In their place are lasers, inertial guidance and vision-based systems using everything from reflectors, targets and magnets to bar codes in its immediate environment to keep the vehicle within its designated path. The latest versions are “learning” the natural features of the facility to literally “free” themselves from any fixed path with random origins to random destinations, with no tape or targets required. They’re called autonomous mobile robots (AMRs).
Whether you call it an AGV, AGC, AMR or robot, today’s “driverless vehicle” has been creating quite a buzz in the materials handling industry. The flexibility, affordability and easier-to-use controls has this system venturing beyond simple tow and carry applications to critical tasks in both manufacturing and distribution.
Here’s a look at seven ways AGVs are being deployed today to reduce labor and promote safety and ergonomics, while minimizing product and equipment damage.
1. To replace conveyors in continuously moving assembly lines.
When most people envision assembly lines, they think of conveyors transporting product from station to station. But Palo Alto-based electric car manufacturer Tesla uses tape-guided AGCs (Daifuku Webb) in a continuously moving assembly line in place of traditional conveyors. Low-profile AGCs carrying the main chassis are sequenced so they move at a particular distance apart. Seats, consoles and bumpers are installed as AGCs transport this work-in-process car down the assembly line.
Carts like these are also being used to assemble riding lawn mowers at John Deere. “In John Deere’s case, the AGC is equipped with a scissor lift which it can raise to work underneath or lower to add parts on top,” says Sarah Carlson, Daifuku Webb’s marketing director and this year’s chair of the AGVS Industry Group for the Material Handling Industry of America (MHIA).
According to Carlson, AGCs in assembly lines offer flexibility. “If production needs to increase by 30%, it can simply increase the number of carts by 30%.” Changing an AGC assembly line can be done in a matter of hours as opposed to weeks when revamping a conveyor assembly line. Where do AGCs not make sense? “If the product has to enter harsh environments such as ovens or paint facilities, then you need to use conveyors,” she adds.