SPY DUST BALLS AND MECHANICAL DRAGONFLIES

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Now, let’s look at some really “far out” IW arsenals of the future: spy dust and tiny mechanical robots. Let’s look first at spies the size of a mote of dust. This will be followed by tiny robotic insects that may soon serve as military scouts.

Spy Dust Balls

“If only these walls could talk” may not be an idle plea much longer. Kris Pister, expectant father of an invention he calls “smart dust,” thinks that in a few years almost anything, from a wall to a mote floating in the air, may have a story to tell. Thousands of these gossipy particles, each a tiny bundle of electronic brains, laser communications system, power supply, sensors, and even a propulsion system, could lurk all around, almost undetectable. One or more of the remote sensors would fit inside the letter “O.”

Pister exemplifies the surging confidence of the leaders in a new field called “MEMS,” which stands for microelectrical and mechanical systems. The idea is to build complex gadgets so small one needs a microscope to see the parts, using fabrication methods invented by the electronics industry for making silicon chips. He talks big and earnestly, even though the best his prototypes (an undustlike inch or so across) can do is exchange laser signals with a counterpart on a tennis court visible 600 yards away through his fifth-floor office window at the University of California-Berkeley. But that’s enough to show that the components work. Miniaturizing them is well within current technology.

Tracking Tots

Cheap, dispersed sensors may tell farmers the exact condition of their acreage; manufacturers, the precise humidity and temperature history of their raw materials; parents, the locations and conditions of their small children all the time. Climate-control systems in buildings would know exactly where it is too cold, humid, hot, or drafty. In five years, smart dust could be linked by satellite. Eventually, you could log-on to readings from smart dust almost anywhere. One dream of Pister: explore outer space with smart dust. NASA could scatter smart dust sensors into the Martian atmosphere and they’d settle all over the planet (like in the recent movie “Red Planet”).

But they could also be used as tiny spies. In 1992, as a new associate professor at the University of California-Los Angeles, Pister attended a RAND Corp. workshop in Santa Monica sponsored by the Pentagon’s Defense Advanced Research Projects Agency. The topic was miniaturization of novel battlefield surveillance methods. The question was whether tiny electronic sensors could be scattered in contested territory to relay vital information back to commanders. You could find out, say, if a tank had gone by, or whether there was anthrax in the air. The concept sent his imagination racing.

Poppy Seeds

He coined the label “smart dust” in 1996 and expects to produce by mid-2002 the first complete smart-dust particle, about 1 millimeter on a side, or roughly between a poppy seed and a grape seed in size. None of the unit’s components seems to present major fabrication obstacles. Before building the first fully small versions, however, the team wants to be sure it can get oversize prototypes to work. One of the students is working on a variant that will sport a thin, winglike extension, like that of a maple seed, so that a modest breeze will keep it aloft. Another student is designing a solid rocket micromotor, visible with a good magnifying glass, carved out of silicon. If a smart dust particle detects a tank going by, it could hop up and hitch a ride like a little spy. Some smart dust may be equipped with solar cells for power. Others might alight on vibrating machinery to soak up energy from the motion, or charge batteries off electromagnetic pulsations leaking from power lines. Sensors, at first, would be simple (such as for temperature, humidity, a few targeted chemicals, etc.) but eventually microphones and camera systems should be possible.

Pister tells the grad students and postdocs in the engineering school’s smart dust group that above all, they must have a passion for new ideas and teamwork. He warns them against giving in to the “dark side,” (Big Brother) against becoming stealth researchers whose distrust of others makes them, in his words, roach motels for information. Love of freely flowing communication is appropriate from a man who expects a tomorrow suffused with tiny snoops. He knows his ideas may occasionally serve nefarious ends, invading privacy or monitoring citizens of authoritarian governments. His reply to nervous objections is simple. “Information is good, and information flow reinforces democracy and not tyranny.” Well, maybe!

Mechanical Dragonflies

The military calls it “situational awareness”: the ability to detect how many hostile tanks await in the next valley, or if bombed-out buildings are filled with snipers. And it is an advantage that has proved difficult to attain: Spies, satellites, and U-2s have all failed to keep commanders from blundering into ambushes and mismatches. The worst thing is just not knowing where the enemy is. It’s having the sense that somebody’s out there trying to get you but having no idea of where the enemy might be.

Military researchers are working to free future American troops from the terror of the unknown. The researchers envision tomorrow’s soldiers coming to a hill, halting, and reaching into their packs for cigar-shaped tubes. From every tube emerges a robotic spider, or a robotic dragonfly, each no longer than 3 inches. Equipped with cameras or acoustic sensors, the mechanical insects range forward and provide data on the hazards that lie in wait on the other side: the number of machine gun nests and the position of artillery.

Robotic Conundrum

Backed by $4.7 million from the Pentagon’s Defense Advanced Research Projects Agency (DARPA), military researchers are designing such insect-inspired spies. Recently, the researchers built their first crawling bug prototypes, and they aim to perfect the design within two years. Insect-shaped “micro aerial vehicles” are next on the slate. Along with providing the military with state-of-the-art scouts, the researchers hope their project alters the way engineers approach the long-vexing problem of robotic locomotion.

In most robotic systems today, people think that if you want to move one joint, then you need to attach a motor at that joint. That makes for large, bulky, energy-hog robots. It also reduces robots to the ranks of expensive toys. Motors are only about 70% efficient in turning electrical power into movement. So, although robots may impress with their futuristic looks, most motor-driven devices have ranges limited to only a few dozen yards, rendering them useless for practical applications.

In the initial design, piezoelectric ceramics—thin, ceramic-coated metal wafers that bend when an electrical current is applied to their surfaces—were proposed. Such materials already are used commercially to make silent pagers vibrate or to make zoom lenses move strips (built from lead, zirconium, and titanium) that are sandwiched together, a structure known as a bimorph actuator. When charged, one half of the actuator expands while the other contracts, causing it to curve. When the brief energy pulse ends, the structure snaps back to its original form and then can begin the cycle anew. The researchers attached titanium legs to these vibrating strips. Vibration is translated into motion, as the crawler takes 2-millimeter-long forward strides in response to each oscillation.

Because piezoelectrics require only occasional energy boosts to keep up the vibration, the bugs promise to be up to 60% more energy efficient than traditional robots. If you’re in a weight room and you lift 100 pounds up and down 10 times, that takes a lot of energy from a person (illustrating the principle behind the design). The same work could more easily be accomplished by hooking that weight to a spring on the ceiling, then displacing it a bit and letting it bounce up and down by itself. Another common analogy is a child on a swing set; once in motion, very little pumping action is required to keep moving. The bugs’ energy efficiency should give them ranges of almost 600 yards, and allow them enough juice to carry such intelligence-oriented payloads as chip-size infrared detectors and quarter-size video cameras.

Natural Efficiency

The engineers’ decision to model their robots after bugs was a natural choice: Biological systems are far more energy efficient than anything cooked up in the laboratory. Most things biological sort of oscillate as they walk. If you look at humans walking and the way our legs act as pendulums off our hips and swing back and forth, that’s a cyclic motion. They were also impressed by the shape of daddy longlegs, whose low-slung bodies and inverted-V legs create a stable configuration—important for robots that will have to scamper across uneven, sometimes treacherous terrain. Additional hardiness comes from the solid-state legs, which are free of bearings, rods, or shafts that could get jammed by pebbles or dust. They probably won’t survive being stomped on, but short of that they’re pretty tough—they could actually survive four-story falls.

Before the bugs can be unleashed on the battlefield, however, a few major hurdles remain. Chief among them is a power problem; though the robots will require around 60 volts to start vibrating, the watch-size batteries being considered can provide only 3 to 6 volts. To get the bugs moving without the aid of chargers, circuitry must be developed to amplify the current, and it must be small enough to fit the 2-by-?-inch bugs. Still, the design’s voltage requirement is impressively low; rival efforts to create locomotive robots of comparable size have needed well over 1,000 volts.

Another lingering question is how a robotic swarm can be controlled. With thousands of bugs roving at once, commanding each individual unit would be close to impossible. So, a battalion leader, outfitted with a remote control, would only have to control a “mother ship,” an insect at the fore that would then relay instructions to other members of the swarm. In the event of the mother ship’s destruction, the leadership role could be shifted to a surviving robot. The exact details of this control, however, have yet to be worked out.

Nevertheless, DARPA officials and the researchers are optimistic that the kinks can be worked out and that assembly-line production of the bugs is nearing. Along with the crawling prototype, the researchers have already managed to construct a piezoelectrically actuated thorax for the flier. Once all design issues are resolved, the researchers believe, the insects could cost as little as $10 per unit. The required metals are readily available, and the bimorph strips and legs can be cheaply pressed from large sheets.

The low price makes the insects potential candidates for a variety of uses, including delivering lethal toxins on the battlefield or aiding police SWAT teams. Or perhaps 40,000 of the mechanical creatures could be dropped on the Martian surface to probe the nooks and crannies Pathfinder missed. But those missions are far distant; the bugs’ first and foremost duty will be to give American troops an upper hand and to save them from stumbling into situations too perilous to survive.

Finally, let’s look at how machines the size of molecules are creating the next industrial revolution in information warfare.

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