Powered exoskeleton

U.S. Army conceptual mock-up of an exoskeleton-equipped soldier.

A powered exoskeleton is a powered mobile machine consisting primarily of an exoskeleton-like framework worn by a person and a power supply that supplies at least part of the activation-energy for limb movement.

Powered exoskeletons are designed to assist and protect the wearer. They may be designed, for example, to assist and protect soldiers and construction workers, or to aid the survival of people in other dangerous environments. A wide medical market exists in the future as prosthetics to provide mobility assistance for aged and infirm people. Other possibilities include rescue work, such as in collapsed buildings, in which the device might allow a rescue worker to lift heavy debris, while simultaneously protecting him from falling rubble.

The first exoskeleton was co-developed by General Electric and the United States military in the 1960s, named Hardiman, which made lifting 250 pounds (110 kg) feel like lifting 10 pounds (4.5 kg). It was impractical due to its 1,500 pounds (680 kg) weight. The project was not successful. Any attempt to use the full exoskeleton resulted in a violent uncontrolled motion, and as a result the exoskeleton was never turned on with a person inside. Further research concentrated on one arm. Although it could lift its specified load of 750 pounds (340kg), it weighed three quarters of a ton, just over twice the liftable load. Without getting all the components to work together the practical uses for the Hardiman project were limited.

Working examples of powered exoskeletons have been constructed but are not currently widely deployed . Various problems remain to be solved, including suitable power-supply.

Many variations of exoskeletons can be found in science fiction and gaming. It was first popularized in Robert A. Heinlein's 1959 novel Starship Troopers where powered armor was used by the Mobile Infantry. Powered armor technology grew to serve as the centerpiece for bestselling novels such as Armor (novel) by John Steakley and Dominant Species by Michael E. Marks. While a realistic visual depiction of powered armor had long been a challenge for practical (live actor in a suit) filming, advances in computer animation have opened the door for several powered armor-centric movies including Iron Man (film), Iron Man 2 and G.I. Joe: The Rise of Cobra. Science fiction role playing games such as Warhammer 40,000 focus on elaborate representations of powered armor. While these technologies are clearly over the horizon in terms of current machine and material science, DARPA is actively pursuing a multi-million dollar program "Concepts of Operations for Exoskeletons for Human Performance Augmentation (EHPA)" to develop them.

Research

Los Alamos Laboratories worked on an exoskeleton project in the 1960s called Project Pitman. In 1986, an exoskeleton prototype called the LIFESUIT was created by Monty Reed, a US Army Ranger who had broken his back in a parachute accident. While recovering in the hospital, he read Robert Heinlein's Starship Troopers and from Heinlein's description of Mobile Infantry Power Suits, he designed the LIFESUIT, and wrote letters to the military about his plans for the LIFESUIT. In 2001 LIFESUIT One (LSI) was built. In 2003 LS6 was able to record and play back a human gait. In 2005 LS12 was worn in a foot race known as the Saint Patrick's' Day Dash in Seattle, Washington. Monty Reed and LIFESUIT XII set the Land Speed Distance Record for walking in robot suits. LS12 completed the 3-mile race in 90 minutes. The current LIFESUIT prototype 14 can walk one mile on a full charge and lift 92 kg (203 lbs) for the wearer.

One of the proposed main uses for an exoskeleton would be enabling a soldier to carry heavy objects (80–300 kg) while running or climbing stairs. Not only could a soldier potentially carry more weight, he could presumably wield heavier armor and weapons. Most models use a hydraulic system controlled by an on-board computer. They could be powered by an internal combustion engine, batteries or, potentially, fuel cells. Another area of application could be medical care, nursing in particular. Faced with the impending shortage of medical professionals and the increasing number of people in elderly care, several teams of Japanese engineers have developed exoskeletons designed to help nurses lift and carry patients.

In January 2007, Newsweek magazine reported that the Pentagon had granted development funds to The University of Texas at Dallas' nanotechnologist Ray Baughman to develop military-grade artificial myomer fibers. These electrically-contractive fibers are intended to increase the strength-to-weight ratio of movement systems in military powered armor.

A Hybrid Assistive Limb powered exoskeleton suit, currently in development.

Exoskeletons could also be applied in the area of rehabilitation of stroke or SCI patients. Such exoskeletons are sometimes also called Step Rehabilitation Robots. An exo-skeleton could reduce the number of therapists needed by allowing even the most impaired patient to be trained by one therapist, whereas several are currently needed. Also training could be more uniform, easier to analyze retrospectively and can be specifically customized for each patient. At this time there are several projects designing training aids for rehabilitations centers (LOPES exoskeleton, LOKOMAT, ALTACRO and the gait trainer, Hal 5.)

Exoskeletons could also be regarded as wearable robots: A wearable robot is a mechatronic system that is designed around the shape and function of the human body, with segments and joints corresponding to those of the person it is externally coupled with. Teleoperation and power amplification were said to be the first applications, but after recent technological advances the range of application fields is said to have widened. Increasing recognition from the scientific community means that this technology is now employed in telemanipulation, man-amplification, neuromotor control research and rehabilitation, and to assist with impaired human motor control (Wearable Robots: Biomechatronic Exoskeletons).

Current exoskeletons

• UC Berkeley/Lockheed Martin HULC legs, the primary competitor to Sarcos/Raytheon. Allows the user to carry up to 200 lbs on a backpack attached to the exoskeleton independent of the user.
• Cyberdyne's HAL 5 arms/legs. Allows the wearer to lift 5 times as much as they normally could.
• Honda Exoskeleton Legs. Weighs 14.3 lbs and features a seat for the wearer.
• M.I.T. Media Lab's Biomechatronics Group legs. Weighs 11.7 kilograms (26 lbs).
• Sarcos/Raytheon XOS Exoskeleton arms/legs. For use in the military and to "replace the wheelchair", weighs 150 lbs and allows the wearer to lift 200 lbs with little or no effort.

See also

• Powered exoskeletons in fiction
• Future Force Warrior
• BLEEX
• Hardiman
• T-52 Enryu
• Mecha
• HAL 5
• List of emerging technologies
• Sarcos

External links

• Video, images and articles about the Bleex exoskeleton project
• Berkeley Bleex press release
• Soldier Bionic Exoskeleton
• University of California- Santa Cruz - Exo Arm Project
• Wired Magazine Issue 13.01 | Jan 2005 - Tetsujin, the world's first exoskeleton weight-lifting competition
• Mecha in AK
• SpringWalker Walking Aid
• Japanese nurse assisting skeleton
• Yamamoto, Keijirou. "Wearable Power Assist Suit". Retrieved 2006-10-10. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
• The Rise of the Body Bots, IEEE Spectrum
• CNN video report on a powered exoskeleton made by Sarcos
• Video and abstract about the GAIT Robotic Orthosis (via IEEE Xplore)
• SARCOS Military Humanoid Exoskeleton (Youtube)