An updated version of a battle-tested nano-UAV stole the show at an annual trial of military gadgets at Fort Benning, Georgia, last month. Tech readers may be nearing peak-UAV, but this autonomous bug-like vehicle is worth paying attention to.

The PD-100 Black Hornet, manufactured by Prox Dynamics, is an air vehicle about the size of a man's finger. The UAV weighs 18 grams and now contains day and night-vision cameras that send still images or video back to an operator via a data-link. Designed for reconnaissance, the vehicle is incapable of attack or defense. But its size and ability to fly autonomously or semi-autonomously make it a clear precursor to the next generation of swarm robots. Welcome to the future of warfare.

According to a recent report by the Center for New American Security titled "The Coming Swarm: The Quality of Quantity," the military is going miniature. Here's why:

Today the U.S. military faces a pernicious cycle of ever rising platform costs and shrinking quantities. As a result, the number of combat ships and aircraft in the U.S. inventory has steadily declined, even during periods of significant growth in defense spending.

Photo courtesy of Prox Dynamics

That's problematic, according to the report, because the proliferation among adversaries of smart munitions and increasingly accurate weapons makes the decreasing numbers of ships and aircraft more vulnerable than ever. Our very expensive war machines will soon become very big strategic liabilities. So what are U.S. military planners to do?

Emerging robotic technologies will allow tomorrow's forces to fight as a swarm, with greater mass, coordination, intelligence and speed than today's networked forces. Low-cost uninhabited systems can be built in large numbers, 'flooding the zone' and overwhelming enemy defenses by their sheer numbers.

In other words, swarm robots, which are relatively inexpensive and, from the standpoint of force planners, essentially disposable, will soon play a central role in military strategy. Efforts to guide the shift to Micro Autonomous Systems and Technology (MAST) are well underway. The U.S. Army Research Laboratory is working with both industry and academia under a collaborative technology alliance that includes defense contractor BAE Systems and UPenn's Processing for Autonomous Operation Center, among other partners.

The collaboration has already sprouted one company. KMel Robotics, founded by two UPenn students, developed a small, agile quad copter that's well-suited to swarm behavior. The company garnered some internet fame after its involvement with the Lexus campaign "Amazing In Motion" and with a clever video in which several synchronized bots play musical instruments.

The company's hardware is nifty, but the algorithms and control mechanisms are what mark the tech as potentially game-changing. KMel was acquired by Qualcomm this past February.

The PD-100 Black Hornet has seen real use in the field by the UK's Brigade Reconnaissance Force. Britain has spent about $31M on the UAVs to date, and the U.S. Army recently signed a $2.5M contract with Prox Dynamics, which is a Norwegian company.

A complete PD-100 system includes two UAVs and a control station, all of which fit inside a small pack that a soldier or first responder can wear unobtrusively over their clothes. Altogether, the rig weighs less than three pounds.