Video: Lost robot

Robots are getting better at finding their way around unknown areas, and making their own maps as they explore. But robots lost in urban areas don’t need to rely on their own faculties to get from place to place, German roboticists have shown.

Their mobile robot simply rolls up to any humans nearby and asks for directions. By using that strategy, their robot has become one of the first to be properly let loose in the real world, not just carefully controlled environments.

Martin Buss‘s team at the Technical University of Munich dumped their mobile robot outside the university and instructed it to find its way to the Marienplatz in the centre of Munich, some 1.5 kilometres away.

Help and hindrance

The robot – called ACE for Autonomous City Explorer – lacks an inbuilt map of Munich or a GPS system. Like a lost human in a similar situation, all it could do was ask for directions.


ACE uses cameras and software to detect humans nearby, based on their motion and upright posture. As it closes in on a likely helper, ACE’s “head” – bearing a touchscreen and a second screen displaying an animated mouth – turns to face the chosen person.

A speaker working in sync with the animated mouth is used to get the person’s attention and to ask them to touch the screen if they want to help. Willing guides are then asked to point the robot in the correct direction, with the response being analysed by posture recognition software. Direction set, ACE says “thank you” before trundling off.

That way

Pointing, rather than telling the robot where to go, avoids confusion caused by the fact that the robot and the facing pedestrian each have a different sense of left and right.

Although it interacted with 38 people over a period of nearly five hours – ACE did eventually reach its destination. In fact, the team report that the robot was making very good progress until it reached a busy pedestrian area where its own popularity became a problem.

ACE had interacted with just 12 people before that point, but 21 curious passersby stopped to talk to the robot as it crossed the busy pedestrian zone.

Only once was ACE given the wrong directions, eventually having to stop due to obstacles after which it asked someone else for help, who put it back on course.

“In theory the robot has to continue on its incorrect path until it needs new information,” says team member Andrea Bauer, “this is why we are currently working on a system to check the information from humans for plausibility.”

‘Way to go’

Paul Newman, a roboticist at the University of Oxford in the UK, is impressed with the new study. “It’s absolutely the way to go,” he says. Navigating a changing environment can be a complicated cognitive task, and “invoking humans when appropriate” could be a relatively simple way for robots to meet the challenge.

Earlier this year, Newman’s team showed that the sophisticated image recognition system developed for their robots could recognise places it had been before even when a scene changed – when parked cars appeared or disappeared, for example.

The Oxford group has just commenced a European-wide project that will attempt to have robots interact more naturally with populated environments. The Munich study is an example of the kind of solutions they will consider, Newman says.

“Robots use mathematics internally to navigate, but that’s not the way you want them to relate to people cohabiting with a machine,” he says. “If there’s a building on fire you don’t want to give a fireman a robot-drawn map or a mathematical model, you want to say: ‘down the corridor, third door on right’.”

Teaching map-making robots to communicate in human terms will make them ready for use in the real world, he says.

International journal of Social Robotics (pdf format, in press)