How Things Work: Powered exoskeletons

Shown in the picture is a prototype of a powered exoskeleton displayed by the US Army. (credit: Courtesy of Shown in the picture is a prototype of a powered exoskeleton displayed by the US Army. (credit: Courtesy of

Technology has come a long way in a short amount of time. In the 1980s, a movie was produced that warned us about the dangers of robotics: The Terminator. According to the movie, robots from the future were agile, powerful, almost indestructible, and bent on destroying the human race.

Luckily, robotics is not at that stage yet. However, researchers are developing suits that would enable humans to mimic these robots in terms of physical capabilities. These so-called “powered exoskeletons” are exactly as they sound; they are skeletal frames worn by humans that have some power supply for movement. This would enable the wearer to lift objects many times heavier than he or she would be able to without the suit, or they could assist the wearer in other forms of movements. A powered exoskeleton is a simple concept: meld man with machine.

The Defense Advanced Research Projects Agency (DARPA) has outlined five structural challenges to overcome in order to build a useful exoskeleton. It will need to be strong, lightweight, and flexible. A long-lasting power source is necessary for the suit to run; ideally, the power source would be nearly silent. The user must be able to control the suit freely and naturally. Movement of the suit is powered by actuators, which are devices that transform an electrical signal into movement. The movement of the actuators must be smooth and quiet. Finally, the suit must be able to move like a human would. All of these would be requirements for a human to be able to interact with the natural environment.

An article in The Independent describes the first powered exoskeleton, Hardiman, developed in the 1960s by General Electric and the United States military. However, it weighed 1500 pounds, which was much too heavy and bulky for any practical use. Another significant advancement was initiated in 1986 by a U.S. Army Ranger, Monty Reed, who had suffered from a broken back as a result of parachuting. An article on describes how Reed later submitted ideas for the LIFESUIT, a powered exoskeleton that mimicked a human walking motion. It was completed in 2001, and since then different, more advanced versions have been built. Other current models of the powered exoskeleton include the XOS Exoskeleton, built by Sarcos, which mimics human movement and allows the wearer to lift enormous amounts of weight while moving fluidly and quickly, and the ExoHiker suit, which allows wearers to carry heavy weights on their backs while regenerating power through every step the user takes, much like hybrid vehicles regenerate electrical power when driving. A video of the Sarcos-powered exoskeleton can be viewed on

The primary use of an exoskeleton is to enhance the physical abilities of the user. If it were to be used in the military, soldiers would be able to move heavy objects in their paths, carry heavier loads, and wear heavier protective clothing, all without feeling the strain of the additional weight. In addition, walking speed could be increased; carrying over a hundred pounds of supplies would slow the best-conditioned soldiers, but with a powered exoskeleton, researchers are looking at speeds greater than 10 m.p.h. even with heavy loads.

Furthermore, other physical abilities, like jumping, could be improved, all to help soldiers maneuver around their environment more quickly and easily. Of course, these suits would have more functions than just military purposes. This technology is being considered for improved movement for the elderly and rehabilitation purposes. They would also be helpful for rescue work, allowing people to clear heavy debris or protecting them from a dangerous environment. Researchers in Japan are designing suits for nurses to help lift and carry patients.