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Biomimetic Human - Exoskeleton Interface


TECHNOLOGY AREA(S): Human Systems 

OBJECTIVE: The objective of this effort is to demonstrate an interface that can safely join an exoskeleton (which is potentially rigid and/or heavy) to a human being (which is fleshy and load-limited) while simultaneously optimizing the mobility of and minimizing the injury to a dismounted Soldier 

DESCRIPTION: Exoskeletons offer a great deal of potential with regard to added protection, off-loading, extended endurance and increased mobility as described in the U.S. Army’s recent Request for Information (1). The US Army has invested in a number of exoskeleton approaches (2,3) for these very reasons. Some are full-body systems (e.g., SARCOS) focused on logistics applications, while others focus on the lower limbs for mobility augmentation (e.g., Lockheed Martin’s KSRD). Each approach is different because they serve different purposes. But what is common about each approach is that they must interface with the human body in order to function. The human-exoskeleton interface raises a number of potential issues. Most exoskeletons contain rigid elements that can restrict natural movement. Non-rigid approaches exist (4) but must still be strapped to the body. In most cases, the weight of the exoskeleton is borne by the wearer through the body interfaces. These systems have the potential to increase the risk for injury unless some key questions are addressed. Does the exoskeleton modify natural human movement? Does the exoskeleton cause additional stresses on the body either due to its load or due to attachment points? How much exoskeleton load can a body manage? In nature there are many examples of creatures with a hard protective exoskeleton (e.g., insects, crustaceans and spiders). Some exoskeletons are hair-based and flexible (i.e., armadillo). Some animals have both an endoskeleton and an exoskeleton (e.g., tortoise). In all cases, there is an interface between the “harder” protective portion and the “softer” fleshy portion of the animal. The two are designed to work as one unit. The design of these types of creatures offer biomimetic and bio-inspired approaches (5,6) toward an effective human-exoskeleton interface. An effective interface is one that considers natural human movement, minimizes the forces exerted on or carried by the body and results in negligible long-term injury to the wearer. 

PHASE I: Conceptualize a suite of bioinspired human - exoskeleton interface concepts for exoskeletons that interface with the lower leg, full leg and upper body. Bioinspired concepts should aim to achieve the following desired outcomes: • Have a low profile when integrated with the exoskeleton. • Have the potential to exert very low shear and/or compressive forces on the body. • Consider Soldier-to-Soldier anthropometric variation. • Enable rapid don and rapid doff. • Provide easy access for medical treatment. • Address user comfort. • Address user acceptance (e.g., needs to “look cool”). • Consider physical changes to the wearer due to weight loss or muscle gain. • Consider load tailoring (i.e., approach load ~100 lbs and assault load ~35 lbs) and its effects. • Account for natural human movement and Soldier tasks. • Capable of being applied to a range of lower leg, full leg and upper body exoskeletons to optimize their existing interfaces. Required Phase I deliverables will include: • Written guidelines for human-exoskeleton interface design in order to further optimize the interfaces of promising candidate systems and other high TRL systems for long-duration operational use. • Documentation of the research findings, including the exoskeleton-to-animal weight ratio (e.g., tortoise shell-to-tortoise weight ratio) and the anticipated interface forces (i.e., direction and magnitude) acting on the animal. • An illustrated suite of bioinspired human - exoskeleton interface concepts and the accompanying documentation that addresses: the inspiration behind each concept, the forces (i.e., direction and magnitude) anticipated to act on the user, and the ease of integration. 

PHASE II: Integrate the top 3-5 Phase I interface concepts into three promising candidate systems (e.g., the Dephy Bionic Boot, the Lockheed Martin ONYX, and one upper body exoskeleton yet to be identified via the active Army RFI). The working prototypes should be evaluated to assess their ability to minimize interface forces on the body, to retain natural movement, and to achieve the desired outcomes listed in Phase I. The Government may provide equipment and/or design drawings of the selected exoskeletons. Required Phase II deliverables will include: • Demonstrate interface performance improvement, user performance improvement and achievement of the desired Phase I outcomes when static, in motion, when carrying load and when unloaded. The criteria or metrics for demonstrating interface performance improvement include: o A reduction in shear and compressive forces on the body o Maintenance or reduction in interface profile o Accommodates anthropometric variation o Enables rapid don and rapid doff o Provides easy access for medical treatment o Is comfortable after extended wear times o Does not interfere with natural human movement during exoskeleton use. • Cost-performance trade-off analysis of the interface concepts. • For each Government-selected exoskeleton, three working exoskeletons with the down selected interface design integrated into them. • Detailed design drawings and complete technical data package of the down selected interface and exoskeleton integration points, including documentation identifying all of the exoskeleton modifications required to integrate the down selected interface. • Updated guidelines for human-exoskeleton interface design based on lessons learned. 

PHASE III: The initial use for this solution will be to improve current and guide future physical interfaces between humans and equipment, namely the exoskeleton. Learnings could be applied to other human-equipment interfaces found in industry. Potential applications include firefighter equipment and rehabilitation exoskeletons. 


1: Request For Concept Papers On Exoskeleton Technologies For The Warfighter

2:  Solicitation Number: W911QY-15-R-0016-C16


4:  Search Results for Exoskeleton


6:  Exoskeleton Report

7:  19 Military Exoskeletons into 5 categories

8:  July 5th, 2016

9:  Bobby Marinov


11:  Wyss Institute, Soft Exosuits

12: "An exosuit does not contain any rigid elements, so the wearer’s bone structure must sustain all the compressive forces normally encountered by the body - plus the forces generated by the exosuit."

13:  Biomimicry Institute

14:  Solutions to global challenges are all around us


16:  14 Smart Inventions Inspired by Nature: Biomimicry

17:  Amelia Hennighausen and Eric Rosten

18:  Feb 23 2015


KEYWORDS: Interface, Exoskeleton, Biomimicry, Wearable, Equipment, Human Performance 


Kristine Isherwood 

(508) 233-4924 

Gregory Kanagaki 

(508) 233-6060 

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