Wearable robotics has shown to be effective for assisting in activities of daily living and restoring motor functions. The objective of this research is to develop a soft robotic exosuit for knee flexion assistance during normal walking and validate its ability to reduce the efforts of the knee flexor muscles: biceps femoris (BF) and semitendinosus (SM). The exosuit is powered by an inflatable curved fabric actuator with the capability to generate flexion torques at the knee joint. An analytical model to characterize the torque of the proposed actuator is derived and validated experimentally. It is found that the analytical torque model precisely matches the experimental results such that the highest root mean square error (RMSE) obtained is 1.237 Nm while the lowest is 0.188 Nm. In addition, the derived model outperformed a benchmark torque model such that its minimum and maximum RMSEs are approximately 90% and 70% less than the benchmark model respectively. A prototype of the knee exosuit is fabricated and tested on one healthy subject with different operating conditions to assist knee flexion during normal walking. The results show that by choosing the appropriate timing of inflation, the exosuit can reduce the electromyography activity of the BF and the SM by 32% and 23%, respectively, without impeding the knee extensor muscle or reducing the knee's range of motion.
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Evaluating the Benefits of a Soft Inflatable Knee Exosuit During Squat Lifting
This work aims to investigate the effects of knee extension assistance during squat lifting. We hypothesize that adding an external torque to the knee joint using a soft inflatable exosuit can potentially induce a reduction in the muscular effort that extends to the posterior chain muscles. A total of 8 healthy test participants are recruited and instructed to lift a weight equivalent to 10% of their bodyweight. The muscle activities of the left and right Vastus Lateralis, Biceps Femoris, Gluteus Maximus, Erector Spinae (Iliocostalis and Longissimus) and Multifidus muscle groups were studied for baseline, non-assisted, and assisted conditions. The majority of participants (6 out of 8) demonstrated consistent reduction in the muscular effort of at least one muscle group of the posterior chain. A maximum reduction of 55% in the average muscle activity of the Multifidus muscle group is observed in one participant. Different neuromuscular adaptation mechanisms were observed among subjects that ultimately led to a reduction in lower-limb or back muscles activity. The results reveal that assisting knee extension during a lifting task has significant effects on muscle activity with benefits that extend to the posterior chain muscles. This work provides early evidence that the soft inflatable knee exosuit can be used in material handling tasks to reduce muscle effort and prevent work-related injuries.
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- Award ID(s):
- 1828010
- NSF-PAR ID:
- 10432759
- Date Published:
- Journal Name:
- 2022 9th IEEE RAS/EMBS International Conference for Biomedical Robotics and Biomechatronics (BioRob)
- Page Range / eLocation ID:
- 1 to 7
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Background As the sustainability of the agricultural workforce has been threatened by the high prevalence of back pain, developing effective interventions to reduce its burden within farming will contribute to the long‐term health and productivity of workers. Passive back‐support exoskeletons are being explored as an intervention to reduce the physical demands on the back muscles, and consequently mitigate the risk of back pain, in many industrial sectors.
Methods This study investigated whether exoskeleton use could reduce farmers' low back muscle load. Electromyography was used to evaluate exoskeleton use in field and laboratory settings. A total of 14 farmers (13 males and 1 female) with a mean age of 49 (
SD = 12) years and 6 female nonfarmers (mean age 28,SD = 5 years) performed a standardized set of tasks that included symmetric and asymmetric lifting and sustained trunk flexion. Following the standardized tasks, 14 farmers also performed regular, real‐world, farm tasks with and without use of the exoskeleton at their farms.Results Exoskeleton use decreased back muscular load during farming activities up to 65%, 56%, and 48% in static, median, and peak muscle activity, respectively. This indicates potential benefits of exoskeleton use to help farmers work under less muscular load. Paradoxically, exoskeleton use during standardized tasks increased muscle activity for some participants.
Conclusions This study demonstrates the potential effects of using passive exoskeletons in agriculture through observational and experimental research, and is among the first that explores the potential for using exoskeletons during actual work tasks in farm settings.
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null (Ed.)Abstract—A workplace study was conducted to evaluate user perceptions, acceptance, and muscle activity amongst logistics workers wearing an unmotorized, dual-mode, back-assist exosuit prototype. Eleven workers performed a lifting/lowering task with vs. without the exosuit, while back muscle activity was recorded. They then used the exosuit while performing their actual work tasks in a distribution center before completing a questionnaire about their user experience. Worker perceptions of the exosuit were overwhelmingly positive: 100% felt the exosuit could be useful and fit into their daily job without interfering, >90% felt assisted and that the exosuit made lifting easier, and >80% felt it was comfortable and that they were free to move naturally while wearing the exosuit. Finally, the majority of workers showed reduced back muscle activity while wearing the exosuit during lifting/lowering, consistent with results from prior lab studies. Worker feedback on this prototype was then used to inform design of the HeroWear Apex exosuit.more » « less
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null (Ed.)This study assessed the metabolic energy consumption of walking with the external components of a “Muscle-First” Motor Assisted Hybrid Neuroprosthesis (MAHNP), which combines implanted neuromuscular stimulation with a motorized exoskeleton. The “Muscle-First” approach prioritizes generating motion with the wearer's own muscles via electrical stimulation with the actuators assisting on an as-needed basis. The motorized exoskeleton contributes passive resistance torques at both the hip and knee joints of 6Nm and constrains motions to the sagittal plane. For the muscle contractions elicited by neural stimulation to be most effective, the motorized joints need to move freely when not actively assisting the desired motion. This study isolated the effect of the passive resistance or “friction” added at the joints by the assistive motors and transmissions on the metabolic energy consumption of walking in the device. Oxygen consumption was measured on six able-bodied subjects performing 6 min walk tests at three different speeds (0.4, 0.8, and 1.2 m/s) under two different conditions: one with the motors producing no torque to compensate for friction, and the other having the motors injecting power to overcome passive friction based on a feedforward friction model. Average oxygen consumption in the uncompensated condition across all speeds, measured in Metabolic Equivalent of Task (METs), was statistically different than the friction compensated condition. There was an average decrease of 8.8% for METs and 1.9% for heart rate across all speeds. While oxygen consumption was reduced when the brace performed friction compensation, other factors may have a greater contribution to the metabolic energy consumption when using the device. Future studies will assess the effects of gravity compensation on the muscular effort required to lift the weight of the distal segments of the exoskeleton as well as the sagittal plane constraint on walking motions in individuals with spinal cord injuries (SCI).more » « less
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Abstract Background Soft robotic exosuits can provide partial dorsiflexor and plantarflexor support in parallel with paretic muscles to improve poststroke walking capacity. Previous results indicate that baseline walking ability may impact a user’s ability to leverage the exosuit assistance, while the effects on continuous walking, walking stability, and muscle slacking have not been evaluated. Here we evaluated the effects of a portable ankle exosuit during continuous comfortable overground walking in 19 individuals with chronic hemiparesis. We also compared two speed-based subgroups (threshold: 0.93 m/s) to address poststroke heterogeneity.
Methods We refined a previously developed portable lightweight soft exosuit to support continuous overground walking. We compared five minutes of continuous walking in a laboratory with the exosuit to walking without the exosuit in terms of ground clearance, foot landing and propulsion, as well as the energy cost of transport, walking stability and plantarflexor muscle slacking.
Results Exosuit assistance was associated with improvements in the targeted gait impairments: 22% increase in ground clearance during swing, 5° increase in foot-to-floor angle at initial contact, and 22% increase in the center-of-mass propulsion during push-off. The improvements in propulsion and foot landing contributed to a 6.7% (0.04 m/s) increase in walking speed (
R 2 = 0.82). This enhancement in gait function was achieved without deterioration in muscle effort, stability or cost of transport. Subgroup analyses revealed that all individuals profited from ground clearance support, but slower individuals leveraged plantarflexor assistance to improve propulsion by 35% to walk 13% faster, while faster individuals did not change either.Conclusions The immediate restorative benefits of the exosuit presented here underline its promise for rehabilitative gait training in poststroke individuals.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/BioRob52689.2022.9925290
