Humans aren't the swiftest creatures on Earth, and most of us are limited in the amount of weight that we can pick up and carry. These weaknesses can be fatal on the battlefield, and that's why the U.S. Defense Advanced Research Projects Agency (DARPA) is investing $50 million to develop an exoskeleton suit for ground troops. This wearable robotic system could give soldiers the ability to run faster, carry heavier weapons and leap over large obstacles.


Photo courtesy DARPA
Exoskeletons will give soldiers the ability to move faster while carrying more weight.

Basically, an exoskeleton is a wearable machine that gives a human enhanced abilities. Imagine a battalion of super soldiers that can lift hundreds of pounds as easily as lifting 10 pounds and can run twice their normal speed. The potential of non-military applications is also phenomenal. In 2000, DARPA requested proposals for human performance augmentation systems, and will soon be signing contracts to begin developing exoskeletons. The military agency said that the testing of this new technology is at least a decade away. It will be much longer before soldiers are donning these body amplification systems for battle.

These exoskeletal systems are expected to give soldiers amplified strength and speed, and will also have built-in computers to aid soldiers in navigating foreign territories. Questions still remain about how these machines will be powered and how they will respond to human motion. In this edition of How Stuff WILL Work, we will take a look at how humans will wear these machines and the challenges that researchers must overcome to make them practical for use on the battlefield and for commercial applications.

Morphing Man and Machine
What the exoskeleton program at DARPA plans to do is turn ordinary soldiers into super-troops who can leap tall objects and run at high speeds. This program is still in the early stages, so details of these wearable machines are still very vague. However, DARPA has set some expectations for these exoskeletal machines. Here's what researchers expect exoskeletons to do for soldiers:

  • Increase strength - Soldiers will be able to carry more weapons and supplies. By increasing strength, soldiers will also be able to remove large obstacles from their path while marching. It will also enable them to wear heavier body armor and other ballistic protection. In the 1960s, General Electric and the U.S. military co-developed an exoskeleton, named Hardiman, that made lifting 250 pounds feel like lifting 10 pounds.
  • Increase speed - An average human walks 4 to 6 mph, but soldiers are often expected to carry up to 150 pounds of supplies in their backpacks. Even the best-conditioned troops cannot go very fast carrying that much weight on their backs. It's not certain how fast DARPA's exoskeleton will be able to move. An independently developed body amplifier, the SpringWalker, has been tested at speeds faster than 10 mph (16 km/h).
  • Leap great heights and distances - It's unclear just how far or high soldiers will be able to jump wearing mechanical suits, but officials would like the machine to give soldiers the ability to leap over obstacles that would ordinarily slow troops down.
Overall, soldiers will benefit from increased endurance when marching long distances over unpredictable terrain. With increased strength, they will also be able to repair heavy equipment that would otherwise be impossible to repair. Experts expect fewer casualties because of increased body armor.


Photo courtesy DARPA
An artist's concept of how future soldiers will look when wearing exoskeletal machines.

These exoskeletal machines would also be equipped with sensors and Global Positioning System (GPS) receivers. Soldiers could use this technology to obtain information about the terrain they are crossing and how to navigate their way to specific locations. DARPA is also developing computerized fabrics that could be used with the exoskeletons to monitor heart and breathing rates.

If the U.S. military has its way, it will have throngs of super soldiers that can jump higher, run faster and lift enormous weight by strapping these exoskeletons to them. However, developing these devices is expected to take years, if not decades. In the next section, you will learn about some of the obstacles that face researchers charged with developing these exoskeletons.

Challenges of Development
DARPA will not be the first to attempt to build an exoskeletal mechanical body suit. As mentioned previously, GE developed the Hardiman hydraulic and electrical body suit in the 1960s. The problem with that suit is that it was so big and heavy (1,500 pounds) that it wasn't practical. Today, there are more advanced materials, such as carbon fiber and other mechanisms available that can be used to build a more streamlined exoskeleton. However, the project is not without its challenges.

Five elements will have to come together to make an exoskeleton machine work, including the structure, power, control, actuation and biomechanics. Each of these elements comes with its own set of challenges. Here's a look at some of the challenges that DARPA has outlined:

  • Structural materials - The exoskeleton will have to be made out of composite materials that are strong, lightweight and flexible. The material must also be capable of protecting itself and its wearer from enemy fire.
  • Power source - The exoskeleton must have enough power to run for at least 24 hours before refueling. Power must also be generated by a pack that can be worn by a person. Creating a machine that makes zero noise could be the most difficult task facing exoskeleton developers. The machine will be powered by some type of engine, so how will they prevent that engine from making noise?
  • Control - Controls for the machine must be seamless. Users must be able to function normally while wearing the device.
  • Actuation - Designers will have to give the machine the ability to move smoothly, so that it's not too awkward for the wearer. Like the engine, actuators must be quiet and efficient.
  • Biomechanics - Will the machines be able to move like a human? Exoskeletons will have to be able to shift from side to side and front to back, just as a person would move in battle. If it lacks that ability, it could be fatal for soldiers wearing the suits. Developers will have to design the frame with joints that can bend like ours.
Military exoskeletons will be some of the most sophisticated machinery ever developed and could also lead to developments in making robots more like humans. Exoskeletons must be able to sense human motion and react to it. They will also need the ability to convert power from an energy source into useable, actuation power to aid its human wearer. The challenges that lay ahead of developers are great, and we will likely see many new devices and innovations developed to make these exoskeletons work.

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