Surveillance robots know when to hide
21 March 2011 by David Hambling
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The creation of robots that can hide from humans while spying on them brings autonomous spy machines one step closer
THE spy approaches the target building under cover of darkness, taking a zigzag path to avoid well-lit areas and sentries. He selects a handy vantage point next to a dumpster, taking cover behind it when he hears the footsteps of an unseen guard. Once the coast is clear, he is on the move again - trundling along on four small wheels.
This is no human spy but a machine, a prototype in the emerging field of covert robotics. It was being put through its paces at a demonstration late last year by Lockheed Martin's Advanced Technology Laboratories at Cherry Hill, New Jersey. With an aerial drone to their credit (see "Unseen watcher in the sky"), the company now wants to design autonomous robots that can operate around humans without being detected.
What makes the robot special is its ability to build a computer model of its surroundings, incorporating information on lines of sight. The robot is fitted with a laser scanner to allow it to covertly map its environment in 3D. It also has a set of acoustic sensors which it uses to distinguish nearby footsteps and their direction.
Lead engineer Brian Satterfield says the robot was designed to operate within four constraints: "Avoiding visible detection by sentries of known locations, avoiding potential detection by sentries whose positions were unknown, avoiding areas in which the robot would have no means of escape, and, as this robot was designed to run at night, avoiding areas that were well lit." To make it hard to spot in the dark, the robot was painted black.
If the robot believes it is in danger of being detected by an approaching sentry, it will try to get to a place where it can hide, Satterfield says. His comment is an example of how natural it is for us to talk about such robots as if they understand how they are perceived and have a "theory of mind".
"Lockheed Martin's approach does include a sort of basic theory of mind, in the sense that the robot makes assumptions about how to act covertly in the presence of humans," says Alan Wagner of the Georgia Institute of Technology in Atlanta, who works on artificial intelligence and robot deception.
But the level at which the robot's software operates is probably limited to task-specific instructions such as, "if you hear a noise, scurry to the nearest dark corner", he says. That's not sophisticated enough to hide from humans in varied environments.
"Significant AI will be needed to develop a robot which can act covertly in a general setting," Wagner says. "The robot will need to consider its own shape and size, to have the ability to navigate potential paths, [to be aware of] each person's individual line of view, the impact that its movement will have on the environment, and so on."
Satterfield's robot was built with off-the-shelf components. Both he and Wagner say that specialised hardware which is more compact and quieter will improve future robots' mobility and their ability to stay hidden. "There are very few fundamental limits that would prevent robots from eventually conducting extended covert missions and evading detection by humans," Satterfield says.
Lockheed Martin's work looks ready to emerge, albeit quietly, into the real world. The US army recently solicited proposals for a "persistent surveillance" robot with concealment capabilities and suited for extended deployments. Later this year, the US Department of Defense is expected to back that up with cash awards for working designs.
Unseen watcher in the sky
In 2006 Lockheed Martin developed a stealthy aerial drone, known as Stalker, for US special forces in Afghanistan. Launched by hand, it weighs 6 kilograms and has a 3-metre wingspan.
The electric-powered drones it replaced are quiet, but Stalker is designed to be even quieter, with a "hush drive" combining a silenced electric motor and a special propeller. Stalker is said to be inaudible beyond 80 metres away, and can fly at night with the aid of infrared sensors and low-light cameras.
Stalker can also accurately deliver a payload weighing up to 1 kilogram, such as remotely operated cameras or microphones for eavesdropping on a target.
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