Technology has always defined how wars are fought, from swords to bows and arrows through the invention of gunpowder and the dawn of the aircraft and, now, to the presence of laser-guided unmanned aerial drones and bomb-diffusing robots. The U.S. military is now hoping the next decade will see a new class of warrior—a faster, stronger and more durable exoskeleton-empowered infantryman.

Such an "iron man" was unveiled Monday at a demonstration of Raytheon Company's new Exoskeleton (XOS 2) at the company's research facility in Salt Lake City, Utah. XOS 2 was designed to be stronger and allow soldier wearing the exoskeleton to execute movements more fluidly than its XOS 1 predecessor, first unveiled in May 2008 (riding the publicity at the time that led up to the release of the first Iron Man movie).

The 95-kilogram XOS 2 is about 40 percent stronger than its 88-kilogram predecessor—the XOS-1 could lift about 16 kilograms with each arm, XOS-2 can lift about 23 kilograms.

Whereas XOS 2 was designed to use half the amount of power as its predecessor, Raytheon is hoping to ultimately develop a version that uses 20 percent of the power as the XOS 1 to perform the same tasks.

Reduced power consumption is key to making the exoskeleton practical to the military. The system is powered by an internal combustion engine, and its electrical systems are run by a wire that tethers the XOS 2 to a power source. Raytheon decided not to use batteries because the company's engineers didn't trust the safety of Lithium-ion batteries in close proximity to the person wearing the exoskeleton.

The engine, tether and even a battery all pose potential limitations to the exoskeleton's range. (Marvel Comic's Iron Man also had issues with range when the character first appeared in 1963.) In order to increase the amount of time the XOS 2 can remain out in the field, Raytheon's engineers are examining both the exoskeleton's internal combustion engine and the impact of the device's high-pressure hydraulics on power consumption. Raytheon doesn't plan to take on the task of developing a better internal combustion engine because there are already many efforts underway to do this, according to the company. However, the company did develop its own hydraulic components and control strategies for the exoskeleton's movement and will continue to look for ways to optimize the efficient use of high-pressure hydraulic fluid.

When Raytheon's exoskeletons first become available to the military (planned for 2015), they will also likely be tethered by power cables, followed three to five years later by untethered versions. The exoskeletons are expected to be used initially to help soldiers to carry heavier loads farther, whether they are performing combat or logistical operations.

The exoskeleton has been under development since 2000 by a team led by Stephen Jacobsen at Raytheon Sarcos. Raytheon released a video [see below] Monday in which XOS 2 test engineer Rex Jameson breaks wood boards, lifts weights and does push ups without much exertion.

XOS 2 is just the latest in a long history of efforts to develop exoskeletons for military, industrial and medical uses. In 2008, Japan's CYBERDYNE, Inc. introduced a sleek, white exoskeleton called the Hybrid Assistive Limb (HAL) under development to augment the body's own strength or do the work of ailing (or missing) limbs. The company (whose name is taken from the fictional company in the Terminator movies that created the deadly Skynet) claims to have signed an agreement with Denmark's Rehabilitation Center in Odense University Hospital to introduce HAL for clinical trials.

Honda Motor Company and the Massachusetts Institute of Technology's (M.I.T.) Media Lab's Biomechatronics Group are likewise developing exoskeleton technology.

Images and video courtesy of Raytheon Company