Exoskeletons have the potential to improve the current physical capabilities of a warfighter, allowing them to run faster, lift heavier objects and relieve strain on the body during physically demanding operations.

The US Army Natick Soldier Research, Development and Engineering Center (NSRDEC/Soldier Center) is currently exploring how commercially developed exoskeletons could be used for military purposes. To this end, the Soldier Center has initiated a 48-month long other transaction agreement (OTA) worth $6.9m in total, in order to develop enough exoskeleton systems to conduct a comprehensive operational evaluation.

"As we explore the more mature exoskeleton options available to us and engage users, the more we learn about where the possible value of these systems is to army operations,” said David Audet, chief of the mission equipment and systems branch in the soldier performance optimisation directorate at the Soldier Center.

"Before the army can consider investing in any development above what industry has done on their own, we need to make sure that users are on board with human augmentation concepts and that the systems are worth investing in.”

Lockheed Martin’s HULC exoskeleton. Image: Lockheed Martin

The biggest defence firm involved in the project is Lockheed Martin. Of the Soldier Center’s $6.9m budget, around $680,000 has been put aside for Lockheed Martin’s OTA for the Onyx lower-body exoskeleton suit, which won a Popular Science award in 2018. It has performed well in initial testing, but has yet to be put through more rigorous operational exercise.

Lockheed Martin Missiles and Fire Control exoskeleton technologies programme manager Keith Maxwell said: “Innovative human/machine technologies like ONYX can improve human performance, decrease injury and reduce fatigue to help soldiers accomplish physically demanding tasks.”

The Onyx system combines mechanical knee actuators with multiple sensors and artificial intelligence software to improve strength and endurance. Currently, the advised weight of a US soldier’s backpack is 50lbs, while in practice, kits can weight up to 140lbs when including body armour, night vision goggles and radio systems.

Therefore, any relief that the exoskeleton can provide will very appealing to today’s warfighters.

Another company involved in the exoskeleton programme is US tech start-up Dephy, founded in 2016. The company’s Exo-boot is designed not as a full-body concept, but to provide localised support for the foot and ankle.

Dephy’s co-founders researched initial designs for the ankle exoskeleton at the Massachusetts Institute of Technology in collaboration with the US Army. While Dephy’s design is under consideration for evaluation in the second half of 2019, some members of the US Army have already tested the exoskeleton at the Soldier Center.

The Exo-boot uses flexible, scalable electronics architecture, or FlexSEA technology, which aims to speed up and simplify the electronics behind wearable robotics designs. The FlexSEA system helps with motion control; includes tools for data acquisition, and provides the networking infrastructure for multi-axis and multi-joint exoskeletons.

Ideally, the army is looking for exoskeletons with full-body capabilities. However, the Soldier Center is considering the Exo-boot because it is a mature piece of equipment that, if successful, could be integrated into army operations more quickly than a full-body suit in its conceptual stage.

"Under ideal conditions, we would favour a full development effort," said Audet. "However, given the push for rapid transition and innovation, we can save the army a lot of time and money by identifying and vetting mature technologies, consistent with the vision of the Army Futures Command.”

Aside from these two designs currently involved in the Soldier Center evaluation, a number of other exoskeleton technologies in development by various private sector companies could also have potential for future military applications. Here we take a look at some of them.