SOMERVILLE, Mass.-- In future wars, robots may drop from the sky by the hundreds from unmanned aircraft, swarming like giant insects over battlefields in coordinated, terrifying assaults.
But that is a decades-away scenario.
For now, military planners and robot designers are simply trying to improve devices -- some of which could see action soon in Iraq -- by incorporating lessons from Afghanistan, where robots saw their first significant military action.
You'd be hard pressed to find anyone in the military who says robots will one day replace soldiers.
Yet the newest robots being developed by companies including iRobot range farther from their "masters" than did their forebears in Afghanistan. They can navigate terrain and obstacles more deftly, lay down a cover of smoke, test for chemical weapons and extend a "neck" that can peer around corners.
The machines are also learning how to right themselves if they flip over as well as how to follow their tracks back home if they lose contact with their base.
The Pentagon has no doubts robots can save lives.
"I don't have any problem writing to iRobot, saying 'I'm sorry your robot died, can we get another?"' said Col. Bruce Jette, the Army's point man on robot deployment, who accompanied the first, $45,000 iRobot "PackBots" into the field in Afghanistan. "That's a lot easier letter to write than to a father or mother."
Prior to Afghanistan, the military was using robots for search-and-rescue and ordnance disposal, but mostly viewed them as long-term research. Airborne drones had proved easier to build than effective land robots.
But the new conflict persuaded the military to move faster. At the time, the state-of-the-art means for clearing a cave was to tie a rope around the waist of an infantryman, who would crawl in and toss ahead a grappling hook to probe for mines or booby traps.
The Pentagon asked iRobot, a startup that emerged out of the Massachusetts Institute of Technology's artificial intelligence program, to rig up its latest prototypes of the 42-pound, remote-controlled PackBot.
Able to ride on tracks like a small tank, climb stairs and work under 3 meters of water or force of up to 400 times gravity, Packbots made their debut just six weeks later at a cave complex outside the village of Nazaraht, near the Pakistani border.
The robots sent video back to the troops, sparing them the risk of being dispatched by booby trap or enemy combatant.
"Their first reaction was, 'Where have you been?"' Jette said.
Later, they offered advice, complaining that the signal wasn't penetrating the walls of deep caves. So Tom Frost, an iRobot engineer at the scene, built a makeshift network of radio repeaters by scavenging old Soviet trucks that littered Bagram Air Base.
Soldiers give input
And when soldiers asked Frost if PackBot could work with the computers integrated into their clothing, he downloaded the necessary code over a satellite.
The soldiers also scribbled a drawing of their idea for an extendable neck. The company was already working on that, but made it a top priority.
Now, in the comparative comfort of its lab back home, iRobot is fine-tuning all those adjustments.
Another lesson from Afghanistan: One size does not fit all.
Sometimes, Jette said, soldiers wanted an 80-pound workhorse like a model built by Foster-Miller of Waltham, which was also tested in Afghanistan. Sometimes, the PackBot was just the right size.
And sometimes, especially in towns, what the soldiers really wanted was a "throw bot" they could toss over a wall or through a window.
"The question is, can you get three-quarters of the capability of those robots at one-tenth the weight," said Robert Larsen, a program manager at Draper Labs, an MIT spinoff that is developing a military robot that resembles the PackBot but weighs less than 5 pounds.
Draper's device, though unlikely to be ready in time for Iraq, is cheap, too. Because it's controlled by an off-the-shelf PDA device, Larsen said, it could cost as little as a few hundred dollars.
The small size has its disadvantages, however.
"When you get small, everything becomes an obstacle," Larsen said, struggling to drive the device over a reporter's crumpled coat at a recent trade show.
The Afghan experience doesn't necessarily mean robots will see widespread action in Iraq.
There are only a handful to go around, and so far U.S. soldiers gathering in Kuwait are not training with them, said John Spiller, a civilian who works with Jette.
"The best I can say at this point is the Army in general is aggressively looking at applying robots in all future operations," said Jette. "I think it would be useful in an open battle."
Planners continue to put a number of robots through their paces at the Army's Military Operations in Urban Terrain center at Fort Benning, Ga., where soldiers train to fight in a mock city.