Building the faster, safer AGV

I won’t say that your typical AGV moves at a snail’s pace. But, at 60 meters per minute – about 2.2 miles per hour - you don’t implement AGVs for speed. You implement them to automate predictable movements from point to point that add little or no value to an operation. Safety is a big reason they don’t move faster: since AGVs often share the road with lift trucks and workers on foot, it’s important to limit their speed. “That also limits productivity,” says Toshisada Mariyama, an assistant manager with Daifuku in Japan.

But what if an AGV could safely travel at three times or more the usual speed limit, say 200 meters per minute, or 7.5 miles per hour, and still operate in the same space as people and lift trucks? What if the AGV could stop on a dime? Could we see something akin to the Ferrari of AGVs? 

That’s a question that was posed to a group at Daifuku and UBIsense, a maker of active RFID technology, by NEDO, Japan’s largest public research and development management organization. Can you create a high speed AGV with safety technology?

Daifuku joined the project in 2011, according to Mariyama. The challenge, he says, wasn’t developing an AGV that could travel at higher speeds. That was the easy part. Rather, it was developing a traffic monitoring system that could track the real-time location of everyone sharing the space inside a designated work area – including people and lift trucks on the move – and then stop the AGVs before any collisions take place

The solution, which is referred to as an area management system for a smart warehouse, brings together several components and technologies. First, the AGVs can only operate at high speeds within a defined work area. Workers, for instance, have to pass through a portal to enter or leave the area. The AGVs are equipped with a 3D laser sensor in front of the AGV running direction that can detect an obstacle 65 feet away and 6.5 feet above by 3D scanning an area. Lift trucks are tracked in real time by ultra wide band (UWB) sensors. Workers were special vests with two UWB active RFID tags. Unlike the RFID technology used for most asset management tasks, which might be accurate to within say 10 feet, UWB tags are accurate to within 30 centimeters, or just under a foot. The tracking system is sensitive enough that it can detect the location of an individual or lift truck based on shadows. The result is that the system controlling the AGV can bring the vehicle to an immediate halt, even when a lift truck comes from seemingly out of nowhere into the automatic vehicle’s path.

“If the AGV can safely operate at higher speeds, we can significantly increase the throughput per vehicle,” says Mariyama. “That may allow an existing application to operate with fewer vehicles or open up new markets for AGVs.” According to Mariyama, the system was tested in a real DC operated by the Ajinomoto Company in Tatebayashi. The company limited the maximum speed of a vehicle to 130 meters per minute, or just under 5 miles per hour. The test, he says, showed that throughput would double at the higher speed.

In February, the system achieved ISO certification and is now available on the market. The next step is to see if the market is ready for the Ferrari of AGVs.