A powered exoskeleton (also known as power armor, powered armor, powered suit, cybernetic suit, robot armor, robot suit, high-tech armor, robotic armor, robot armor suit, cybernetic armor, exosuit, hardsuit, exoframe or augmented mobility) is a mobile machine that is wearable over all or part of the human body, providing ergonomic structural support and powered by a system of electric motors, pneumatics, levers, hydraulics or a combination of cybernetic technologies, while allowing for sufficient limb movement with increased strength and endurance. The exoskeleton is designed to provide better mechanical load tolerance, and its control system aims to sense and synchronize with the user's intended motion and relay the signal to motors which manage the gears. The exoskeleton also protects the user's shoulder, waist, back and thigh against overload, and stabilizes movements when lifting and holding heavy items.
A powered exoskeleton differs from a passive exoskeleton, as the latter has no intrinsic actuator and relies completely on the user's own muscles for movements, adding more stress and making the user more prone to fatigue, although it does provide mechanical benefits and protection to the user. This also explains the difference of an exoskeleton to orthotics, as orthosis mainly aims to promote progressively increased muscle work and, in the best case, regain and improve existing muscle functions. Currently, there are products that can help humans reduce their energy consumption by as much as 60 percent while carrying things.
The earliest-known exoskeleton-like device was an apparatus for assisting movement developed in 1890 by Russian engineer Nicholas Yagin. It used energy stored in compressed gas bags to assist in movement, although it was passive and required human power. In 1917, United States inventor Leslie C. Kelley developed what he called a pedomotor, which operated on steam power with artificial ligaments acting in parallel to the wearer's movements. This system was able to supplement human power with external power.