There are many different takes on what a human exoskeleton could look like, and a few have even been put into service to greatly augment the human body. However, most of those have one thing in common — they need power. Lockheed Martin has been experimenting with a more elegant unpowered solution that solves one particularly nasty problem with clever analysis of biomechanics. That problem? Tools are heavy. The Fortis exoskeleton can allow a worker to hold a tool weighing up to 36 pounds indefinitely.

Fortis is being developed with military applications in mind. Not for the battlefield, but for the workers who support the military with their blood and sweat. Many of the tools like grinders and riveters that workers need to use can easily weigh 15-30 pounds (about 7-14 kg). Even a stout working man can only hold something that heavy at arm’s length for a few minutes before he has to rest his muscles. Fortis solves the problem of muscle fatigue by supporting up to 36 pounds of weight so the wearer can move the tool around effortlessly.

Unlike other exoskeletons that increase human strength, Fortis isn’t attached to the arms. There are no hydraulics or motors that augment the way your limbs move. All the magic happens in an articulated swing arm attached to the exoskeleton at the waist (Lockheed Martin calls this the “zeroG” arm). At the end of this arm is a mounting point for the tool. The worker operates the tool normally, but it’s attached to the exoskeleton via the swing arm. Instead of the weight of the tool being transferred to the wearer’s arms, it’s borne entirely by the aluminum/carbon fiber frame of Fortis and transferred to the ground.

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The rest of the exoskeleton is designed with human movement and biomechanics in mind. There are joints at the ankle, knee, and hip to ensure you can actually move while wearing the device. The weight of the payload gets to the ground through the stirrup, which is also attached to the ankle and allows the foot to rest on the ground normally. Lockheed Martin says this design is superior to exoskeletons that attach to the shoes.

Designers tested the exoskeleton with a 16-pound grinder commonly used in industrial settings. A worker was able to hold this tool over his head unaided for only three minutes before needing to rest his arms. Using Fortis, the worker was able to use the grinder continuously for 30 minutes with no problems. Lockheed estimates Fortis can improve productivity by up to 27x, depending on the task. At the same time, it also reduces the risk of injury and makes manual labor much less tiring.

The US Navy has purchased two of the Fortis exoskeletons from Lockheed and will be testing them over the next six months to see if the claimed productivity improvements are legit. Fortis may also see use in civilian applications like mining and construction. Basically, anything where you need to hold heavy things out in front of you for long periods of time can potentially be improved by a Fortis exoskeleton, and it never needs to be plugged in.

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