Enhancing Mobility With Quasi-Passive Variable Stiffness Exoskeletons

Sutrisno, Amanda; Braun, David J.

doi:10.1109/tnsre.2019.2899753

Cited by 37 publications

(24 citation statements)

References 60 publications

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“…A final scenario is that the power from the negative phase could be temporarily stored via battery or clutch and returned at a later time–an approach that has been used within a single gait cycle in foot-ankle prosthesis designs [ 73 , 74 ]. This last approach, extraction, storage, and then delayed release ( Fig 4F ) opens up the possibility to store energy over multiple cycles, perhaps accumulating it, and then returning it in a single large burst over a shorter time period to achieve power amplification that may be necessary for on-off accelerations or maximum effort jumps [ 75 ].…”

Section: Discussionmentioning

confidence: 99%

Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons

et al. 2020

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Lower-limb wearable robotic devices can improve clinical gait and reduce energetic demand in healthy populations. To help enable real-world use, we sought to examine how assistance should be applied in variable gait conditions and suggest an approach derived from knowledge of human locomotion mechanics to establish a 'roadmap' for wearable robot design. We characterized the changes in joint mechanics during walking and running across a range of incline/decline grades and then provide an analysis that informs the development of lowerlimb exoskeletons capable of operating across a range of mechanical demands. We hypothesized that the distribution of limb-joint positive mechanical power would shift to the hip for incline walking and running and that the distribution of limb-joint negative mechanical power would shift to the knee for decline walking and running. Eight subjects (6M,2F) completed five walking (1.25 m s-1) trials at-8.53˚,-5.71˚, 0˚, 5.71˚, and 8.53˚grade and five running (2.25 m s-1) trials at-5.71˚,-2.86˚, 0˚, 2.86˚, and 5.71˚grade on a treadmill. We calculated time-varying joint moment and power output for the ankle, knee, and hip. For each gait, we examined how individual limb-joints contributed to total limb positive, negative and net power across grades. For both walking and running, changes in grade caused a redistribution of joint mechanical power generation and absorption. From level to incline walking, the ankle's contribution to limb positive power decreased from 44% on the level to 28% at 8.53˚uphill grade (p < 0.0001) while the hip's contribution increased from 27% to 52% (p < 0.0001). In running, regardless of the surface gradient, the ankle was consistently the dominant source of lower-limb positive mechanical power (47-55%). In the context of our results, we outline three distinct use-modes that could be emphasized in future lower-limb exoskeleton designs 1) Energy injection: adding positive work into the gait cycle, 2) Energy extraction: removing negative work from the gait cycle, and 3) Energy transfer: extracting energy in one gait phase and then injecting it in another phase (i.e., regenerative braking).

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Section: Discussionmentioning

confidence: 99%

Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons

et al. 2020

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“…• More robust by dissipating mechanical energy to prevent injury during high impact activities like rapid cutting maneuvers or falling from extreme heights [87].…”

Section: Conclusion Closing Remarks and Vision For The Future Of Exosmentioning

confidence: 99%

The exoskeleton expansion: improving walking and running economy

Sawicki

Beck

Kang

et al. 2020

J NeuroEngineering Rehabil

311

201

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Since the early 2000s, researchers have been trying to develop lower-limb exoskeletons that augment human mobility by reducing the metabolic cost of walking and running versus without a device. In 2013, researchers finally broke this 'metabolic cost barrier'. We analyzed the literature through December 2019, and identified 23 studies that demonstrate exoskeleton designs that improved human walking and running economy beyond capable without a device. Here, we reviewed these studies and highlighted key innovations and techniques that enabled these devices to surpass the metabolic cost barrier and steadily improve user walking and running economy from 2013 to nearly 2020. These studies include, physiologically-informed targeting of lower-limb joints; use of off-board actuators to rapidly prototype exoskeleton controllers; mechatronic designs of both active and passive systems; and a renewed focus on human-exoskeleton interface design. Lastly, we highlight emerging trends that we anticipate will further augment wearable-device performance and pose the next grand challenges facing exoskeleton technology for augmenting human mobility.

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“…Building exoskeleton devices (8) and performing human-in-the-loop experimental exploration (9,21) are the mainstream and state-of-the-art approaches to develop novel human augmentation paradigms, although theoretical investigations may also be useful to uncover the benefits of previously unexplored augmentation methods (22). Simple spring-mass models (18,19) have been previously used to provide useful theoretical predictions of the biomechanics of natural running (23,24).…”

Section: Resultsmentioning

confidence: 99%

How to run 50% faster without external energy

Sutrisno

Braun

2020

Sci. Adv.

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Technological innovations may enable next-generation running shoes to provide unprecedented mobility. But how could a running shoe increase the speed of motion without providing external energy? We found that the top speed of running may be increased more than 50% using a catapult-like exoskeleton device, which does not provide external energy. Our finding uncovers the hidden potential of human performance augmentation via unpowered robotic exoskeletons. Our result may lead to a new-generation of augmentation devices developed for sports, rescue operations, and law enforcement, where humans could benefit from increased speed of motion.

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Enhancing Mobility With Quasi-Passive Variable Stiffness Exoskeletons

Cited by 37 publications

References 60 publications

Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons

Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons

The exoskeleton expansion: improving walking and running economy

How to run 50% faster without external energy

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