Kinematic effects of a passive lift assistive exoskeleton

Simon, Athulya A.; Alemi, Mohammad Mehdi; Asbeck, Alan T.

doi:10.1016/j.jbiomech.2021.110317

Cited by 15 publications

(12 citation statements)

References 29 publications

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“…𝐾 𝐶𝐾 where 𝐶 is a coefficient that is the contribution due to inertial effects and is less than one. The specific value of 𝐶 is likely between 0.93-0.97 for normal lifting speeds based on the fraction of total energy caused by the peak kinetic energy, as previously discussed (67,72). With a value of 𝐶 in this range, so that 𝐾 𝐾 , our measured metabolic reductions would correspond even more closely to the predicted value.…”

Section: Discussionsupporting

confidence: 60%

“…This assumption is reasonable, since the kinetic energy of the body is a relatively small fraction of the total energy during lifting. One study (72) found that the kinetic energy of the body's center of mass was only 3.2-6.1% of the total energy of the center of mass (stoop lifting corresponded to 3.2%, and squat lifting to 6.1%), and similar results were found by (22) and (67).…”

Section: Part A: Developing a Prediction Model For The Metabolic Cost...mentioning

confidence: 54%

“…Note that the body COM height changes are slightly larger for a heavy box since people crouch down more to lift heavy loads, as measured by (72). By inserting all of the necessary parameters in the without-exoskeleton metabolic cost model, the model was linearly best fit with our withoutexoskeleton experimental data to calculate the biomechanical efficiency of lifting a box and the body during freestyle lifting.…”

Section: Part C: Fitting the Without-exoskeleton Metabolic Cost Predi...mentioning

confidence: 99%

“…In this paper, the 0% BW equations were used for empty boxes or boxes less than or equal to 2.7kg, the 20% BW equations were used for box masses equal to or greater than 20% BW, and linear interpolation between the 0% BW equations and 20% BW equations was done for masses between 2.7kg and 20% BW. The equations are taken from kinematics data measured in (72).…”

Section: Table Dmentioning

confidence: 99%

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Modeling the metabolic reductions of a passive back-support exoskeleton

Alemi

Simon

Geissinger

et al. 2022

Journal of Applied Physiology

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Despite several attempts to quantify the metabolic savings resulting from the use of passive back-support exoskeletons (BSEs), no study has modeled the metabolic change while wearing an exoskeleton during lifting. The objectives of this study were to: 1) quantify the metabolic reductions due to the VT-Lowe's exoskeleton during lifting; and 2) provide a comprehensive model to estimate the metabolic reductions from using a passive BSE. In this study, 15 healthy adults (13M, 2F) of ages 20 to 34 years (mean=25.33, SD=4.43) performed repeated freestyle lifting and lowering of an empty box and a box with 20% of their bodyweight. Oxygen consumption and metabolic expenditure data were collected. A model for metabolic expenditure was developed and fitted with the experimental data of two prior studies and the without-exoskeleton experimental results. The metabolic cost model was then modified to reflect the effect of the exoskeleton. The experimental results revealed that VT-Lowe's exoskeleton significantly lowered the oxygen consumption by ~9% for an empty box and 8% for a 20% bodyweight box, which corresponds to a net metabolic cost reduction of ~12% and ~9%, respectively. The mean metabolic difference (i.e., without-exo minus with-exo) and the 95% confidence interval were 0.36 and (0.2-0.52) [Watts/kg] for 0% bodyweight, and 0.43 and (0.18-0.69) [Watts/kg] for 20% bodyweight. Our modeling predictions for with-exoskeleton conditions were precise, with absolute freestyle prediction errors of <2.1%. The model developed in this study can be modified based on different study designs, and can assist researchers in enhancing designs of future lifting exoskeletons.

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Section: Discussionsupporting

confidence: 60%

Section: Part A: Developing a Prediction Model For The Metabolic Cost...mentioning

confidence: 54%

Section: Part C: Fitting the Without-exoskeleton Metabolic Cost Predi...mentioning

confidence: 99%

Section: Table Dmentioning

confidence: 99%

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Modeling the metabolic reductions of a passive back-support exoskeleton

Alemi

Simon

Geissinger

et al. 2022

Journal of Applied Physiology

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“…VT-Lowe's utilizes carbon fiber-based flexible beams running in parallel to the spine up to the back of the thigh. It significantly reduced activity in the spinal muscles (29.3%) during symmetric and asymmetric lifting (Alemi et al, 2019;Simon et al, 2021.). However, moderate activity in abdominal muscles was also noticed, which can be beneficial as it stabilizes the trunk.…”

Section: Flexible Beams Actuated Devicesmentioning

confidence: 95%

Systematic Review of Back-Support Exoskeletons and Soft Robotic Suits

Ali

Fontanari

Schmoelz

et al. 2021

Front. Bioeng. Biotechnol.

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Lower back pain and musculoskeletal injuries are serious concerns for workers subjected to physical workload and manual material handling tasks. Spine assistive exoskeletons are being developed to support the spine and distribute the spine load. This article presents a detailed up-to-date review on the back support exoskeletons by discussing their type (Active/Passive), structure (Rigid/Soft), power transmission methods, weight, maximum assistive force, battery technologies, tasks (lifting, bending, stooping work), kinematic compatibility and other important features. This article also assesses the back support exoskeletons in terms of their ability to reduce the physical load on the spine. By reviewing functional and structural characteristics, the goal is to increase communication and realization among ergonomics practitioners, developers, customers, and factory workers. The search resulted in reviewing 34 exoskeletons of which 16 were passive and 18 were active. In conclusion, back support exoskeletons have immense potential to significantly reduce the factors regarding work-related musculoskeletal injuries. However, various technical challenges and a lack of established safety standards limit the wide adaptation of exoskeletons in industry.

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