The New Mobile Infantry (continued 3/4)

Tactical robot efforts at other R&D centers are no less impressive. Since 2000, scientists at Draper Laboratory, in Cambridge, Massachusetts, have been working on a series of throwable robots - small, lightweight rovers that can be tossed into hostile settings. "Let's say I'm trying to see who's inside a building before I enter," says Rob Larsen, a program manager at Draper. "I can pitch the robot like a baseball through a window. As soon as it hits the ground, it begins relaying video and audio." Essentially, a throwable bot gives a soldier X-ray vision and superhuman hearing. Says Larsen: "Troops now in the jungles of the Philippines would be able to know what's ahead of them with this technology."

The first throwable robot effort, funded by Blitch's TMR program, culminated in Spike - a grapefruit-sized bot that slides open and extends spiked wheels on command. Spike had no onboard sensors or processor and had to be tele-operated by a soldier using a wireless joystick.

Now, with funding from a different Darpa program, Draper is working on a more intelligent device called the high-mobility tactical microrobot, or HMTM. Larsen plans to have a prototype ready for Darpa in December and aims to supply a $5,000 battle-ready model within three years. But first, his team must devise a way for the HMTM to handle conditions as varied as mud, gravel, and water. One possible solution uses a hybrid motion system that switches between tanklike treads and wheels depending on the terrain. Larsen also needs to ensure that the device will be able to withstand repeated drops onto pavement. To that end, he's developing special impact-resistant materials to fortify the housing, wheels, chassis, and drivetrain.

In the meantime, the Draper group has written custom software that can compress video in real time. This feature will be particularly important when Larsen converts the communications system from its current 802.11b protocol to cellular, which can cover a broader geographical area (and is more suitable in remote locations) but operates over a narrower slice of bandwidth. No wireless system is 100 percent dependable, though, so Larsen is developing a homing instinct that he calls automatic retrotraverse. An onboard sensor tracks the HMTM's heading and wheel rotation. If the network fails, the robot can play back its movements in reverse, retracing its steps until communication is reestablished. "This will save the robot if the communication link with the operator drops out or is jammed," says Larsen. "It could spell the difference between mission success and failure."

A few miles from Draper Lab, at an MIT spinoff called iRobot, researchers are developing another promising TMR: the PackBot. It looks like a miniature tank stripped of its gun turret and stands out for both its agility and versatility. The general-purpose TMR can be used as a workhorse vehicle for hauling ordnance or as a mobile first-aid station, dashing into battle with a cartload of medical supplies. In one video demo, the PackBot rescues an injured soldier lying between two buildings as bullets whiz overhead. The PackBot zips to his side, dragging a stretcher. The soldier rolls onto it. Medics, holed up in a nearby bunker, grab a tether attached to the stretcher and pull it to safety. In another clip, the PackBot ascends a flight of stairs in a couple of seconds. The iRobot engineers are working on teaching the PackBot to ford a river after looking for shallow water or protruding stones.

The robot is also wired for reconnaissance missions. "It has six payload sockets," says project manager Tom Frost. Each robot can handle 12 video sources, six Ethernet connections, eight USB ports, digital signal processing, and eight power supplies. A 700-MHz Pentium III with 256 Mbytes of memory, 300 Mbytes of storage, and two video cards crunches incoming sensor data. Finally, a digital compass and a GPS receiver keep the PackBot on course when it's in the field.

This summer, iRobot will deliver up to 15 PackBots - running $20,000 to $50,000 each - to the Department of Defense, which will distribute the machines for testing by various groups within the military.

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