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Mhairi K. MacLean and Daniel P. Ferris

One goal for developing robotic lower limb exoskeletons is human performance augmentation. Robotic exoskeletons that can enhance the performance of able-bodied humans serving as firefighters, military personnel, and/or construction workers could reduce injuries and improve worker efficiency. To be

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Allison J. Nelson, Patrick T. Hall, Katherine R. Saul, and Dustin L. Crouch

shoulder pain among adults is as much as 27%. 9 These facts underscore the need for approaches to prevent and treat shoulder disorders. Exoskeletons that apply forces to the body to assist with motor tasks are one approach that may assist people with shoulder disorders or prevent injury. For example

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Michael S. Cherry, Sridhar Kota, Aaron Young, and Daniel P. Ferris

Although there have been many lower limb robotic exoskeletons that have been tested for human walking, few devices have been tested for assisting running. It is possible that a pseudo-passive elastic exoskeleton could benefit human running without the addition of electrical motors due to the spring-like behavior of the human leg. We developed an elastic lower limb exoskeleton that added stiffness in parallel with the entire lower limb. Six healthy, young subjects ran on a treadmill at 2.3 m/s with and without the exoskeleton. Although the exoskeleton was designed to provide ~50% of normal leg stiffness during running, it only provided 24% of leg stiffness during testing. The difference in added leg stiffness was primarily due to soft tissue compression and harness compliance decreasing exoskeleton displacement during stance. As a result, the exoskeleton only supported about 7% of the peak vertical ground reaction force. There was a significant increase in metabolic cost when running with the exoskeleton compared with running without the exoskeleton (ANOVA, P < .01). We conclude that 2 major roadblocks to designing successful lower limb robotic exoskeletons for human running are human-machine interface compliance and the extra lower limb inertia from the exoskeleton.

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Mikael Scohier, Dominique De Jaeger, and Benedicte Schepens

The purpose of this study was to mechanically evoke a triceps surae stretch reflex during the swing phase of running, to study its within-the-step phase dependency. Seven participants ran on a treadmill at 2.8 m·s−1 wearing an exoskeleton capable of evoking a sudden ankle dorsiflexion. We measured the electromyographic activity of the soleus, medial and lateral gastrocnemii just after the perturbation to evaluate the triceps surae stretch reflex. Similar perturbations were also delivered at rest. Our results showed that the stretch reflex was suppressed during the swing phase of running, except in late swing where a late reflex response was observed. At rest, all triceps surae muscles showed an early reflex response to stretch. Our findings suggest that the triceps surae short/medium-latency stretch reflex cannot be evoked during swing phase and thus cannot contribute to the control of the locomotor pattern after aperturbation during this phase.

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Daniel P. Ferris, Joseph M. Czerniecki, and Blake Hannaford

We developed a pneumatically powered orthosis for the human ankle joint. The orthosis consisted of a carbon fiber shell, hinge joint, and two artificial pneumatic muscles. One artificial pneumatic muscle provided plantar flexion torque and the second one provided dorsiflexion torque. Computer software adjusted air pressure in each artificial muscle independently so that artificial muscle force was proportional to rectified low-pass-filtered electromyography (EMG) amplitude (i.e., proportional myoelectric control). Tibialis anterior EMG activated the artificial dorsiflexor and soleus EMG activated the artificial plantar flexor. We collected joint kinematic and artificial muscle force data as one healthy participant walked on a treadmill with the orthosis. Peak plantar flexor torque provided by the orthosis was 70 Nm, and peak dorsiflexor torque provided by the orthosis was 38 Nm. The orthosis could be useful for basic science studies on human locomotion or possibly for gait rehabilitation after neurological injury.

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Daniel P. Ferris and Bryan R. Schlink

Robotic exoskeletons and bionic prostheses have moved from science fiction to science reality in the last decade. These robotic devices for assisting human movement are now technically feasible given recent advancements in robotic actuators, sensors, and computer processors. However, despite the ability to build robotic hardware that is wearable by humans, we still do not have optimal controllers to allow humans to move with coordination and grace in synergy with the robotic devices. We consider the history of robotic exoskeletons and bionic limb prostheses to provide a better assessment of the roadblocks that have been overcome and to gauge the roadblocks that still remain. There is a strong need for kinesiologists to work with engineers to better assess the performance of robotic movement assistance devices. In addition, the identification of new performance metrics that can objectively assess multiple dimensions of human performance with robotic exoskeletons and bionic prostheses would aid in moving the field forward. We discuss potential control approaches for these robotic devices, with a preference for incorporating feedforward neural signals from human users to provide a wider repertoire of discrete and adaptive rhythmic movements.

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Bart Roelands and Kevin De Pauw

exoskeletons to augment human performance. Many proof-of-concept and proof-of-principle prototypes have been constructed for military and industrial use, but only a handful reach the market. In sports, a skiing exoskeleton has recently been designed, developed, and constructed—the Againer Ski Exoskeleton

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Increase Prosthetic Limb Collision and Push-Off Work During Gait? Matthew J. Major * José L. Zavaleta * Steven A. Gard * 1 10 2019 35 5 312 319 10.1123/jab.2019-0043 jab.2019-0043 Energetics of Walking With a Robotic Knee Exoskeleton Mhairi K. MacLean * Daniel P. Ferris * 1 10 2019 35 5 320 326

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EDITORIAL Lessons Learned Walter Herzog 1 04 2020 15 03 2020 36 2 57 58 10.1123/jab.2020-0035 jab.2020-0035 COMPUTATIONAL MODEL Effect of Mechanically Passive, Wearable Shoulder Exoskeletons on Muscle Output During Dynamic Upper Extremity Movements: A Computational Simulation Study Allison J

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J. Lake * Eric S. Wallace * Tom Feehally * Michael Hanlon * 6 2016 32 3 261 268 10.1123/jab.2015-0125 Running With an Elastic Lower Limb Exoskeleton Michael S. Cherry * Sridhar Kota * Aaron Young * Daniel P. Ferris * 6 2016 32 3 269 277 10.1123/jab.2015-0155 An Examination of the