Engineers have equipped a robot with the one social skill essential to British society - the ability to queue politely, writes Steve Farrar.
The droid uses stereo vision, a sophisticated navigation system and an appreciation of the concept of personal space to detect, join and maintain its position in line.
Yasushi Nakauchi, associate professor at the National Defence Academy in Yokosuka, Japan, and Reid Simmons, senior research scientist at Carnegie Mellon University in Pittsburgh, US, believe that if they are to operate in public, robots will have to conform to accepted social mores.
"Robots have to interact with humans, whether they like it or not. Standing in line is one of the most highly socialised and crucial skills required for robots that operate in peopled environments," they said.
To test the concept, the scientists created Xavier, a four-wheeled cylindrical droid controlled by two onboard computers, and sent him to buy a cup of coffee in the canteen of the scientists' Pittsburgh laboratory.
After reaching the kiosk, the robot picked out nearby objects using stereo vision from his two top-mounted cameras. He analysed this data to identify telltale shapes of people and then determine their orientation.
Armed with a knowledge of personal space, Xavier tracked back along the line until he found its end.
He used a combination of laser sensors and sonar to maintain a comfortable distance from the person in front until he reached the kiosk.
In a synthesised voice, Xavier asked for a cup of coffee. Once he saw this had been placed in his holder, the robot trundled away back to the lab.
In 14 of 20 trials, detailed in the Journal of Autonomous Robots , the robot had no problems. But he blew it when it came to paying his way. Unable to hand over necessary cash, the scientists programmed Xavier to bleat: "Thank you. Put it on my tab."