scholarly journals Mechanical Efficiency Investigation of an Ankle-assisted Robot for Human Walking with a Backpack-Load

2021 ◽  
Author(s):  
Longhan Xie ◽  
Zhihou Wang ◽  
Guowei Huang ◽  
Biao Liu ◽  
Zikang Zhou
Keyword(s):  
Human Body ◽  
Weight Bearing ◽  
Metabolic Cost ◽  
Mechanical Efficiency ◽  
Critical Force ◽  
Mechanical Work ◽  
Experimental Conditions ◽  
Work Input ◽  
Negative Effect ◽  
Metabolic Expenditure

Abstract The purpose of this work is to investigate the efficiency of wearable assistive devices under different load-carried walking. We designed an experimental platform, with a lightweight ankle-assisted robot. Eight subjects were tested in three experimental conditions: free walk with load (FWL), power-off with load (POFL), and power-on with load (PONF) for different levels of force at a walking speed of 3.6 km/h. We recorded the metabolic expenditure and kinematics of the subjects under three levels of load-carried (10%, 20%, and 30% of body mass). We define the critical force, where at a certain load, the robot inputs a certain force to the human body, and with the assistance of this force, the positive effect of the robot on the human body exactly compensates for the negative effect. The critical forces from the fit of the assistive force and metabolic cost curves were 130 N, 160 N and 215 N at three different load levels. The intrinsic weight of our device increases mechanical work at the ankle as the load weight rises, with 2.08 J, 2.43 J and 2.73 J for one leg during a gait cycle. With weight bearing increasing, the ratio of the mechanical work input by the robot to the mechanical work output by the weight of the device decreases (from 0.904, to 0.717 and 0.513), verifying that the walking assistance efficiency of such devices decreases as the weight rises.

scholarly journals Mechanical Efficiency Investigation of an ankle-assisted robot for human walking with a backpack-load

2020 ◽  
Author(s):  
Zhihou Wang ◽  
Guowei Huang ◽  
Biao Liu ◽  
Zikang Zhou ◽  
Binghong Liang ◽  
...  
Keyword(s):  
Lightweight Design ◽  
Weight Bearing ◽  
Mechanical Efficiency ◽  
Mechanical Work ◽  
Medical Rehabilitation ◽  
Walking Robots ◽  
Experimental Conditions ◽  
Assistive Robots ◽  
Wide Range ◽  
Metabolic Expenditure

AbstractLower limb assistive robots have a wide range of applications in medical rehabilitation, hiking, and the military. The purpose of this work is to investigate the efficiency of wearable assistive devices under different weight-bearing walking conditions. We designed an experimental platform, with a lightweight ankle-assisted robot weighing 5.2 kg and carried mainly on the back. Eight subjects were tested in three experimental conditions: free walk with load (FWL), power-off with load (POFL), and power-on with load (PONF) for different levels of force at a walking speed of 3.6 km/h. We recorded the metabolic expenditure and kinematics of the subjects under three levels of weight-bearing (equal to 10%, 20%, and 30% of body mass). The critical forces from the fit of the assistive force and metabolic depletion curves were 130 N, 160 N and 215 N at three different load levels. The intrinsic weight of our device increases mechanical work at the ankle as the load weight rises, with 2.08 J, 2.43 J, 2.73 J for one leg during a gait cycle. The ratio of the mechanical work input by the robot to the mechanical work output by the weight of the device decreases (0.904, 0.717, and 0.513 with different load carriages), verifying that the walking assistance efficiency of such devices decreases as the weight rises. In terms of mechanical work in the ankle joint, our results confirm that the efficiency of the ankle-assisted walking robot decreases as weight bearing increases, which provides important guidance for the lightweight design of portable weight-bearing walking robots.

scholarly journals Gut Microbiota Dynamics in Natural Populations of Pintomyia evansi under Experimental Infection with Leishmania infantum

2021 ◽  
Vol 9 (6) ◽  
pp. 1214
Author(s):  
Rafael José Vivero ◽  
Victor Alfonso Castañeda-Monsalve ◽  
Luis Roberto Romero ◽  
Gregory D. Hurst ◽  
Gloria Cadavid-Restrepo ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Leishmania Infantum ◽  
Natural Populations ◽  
Illumina Miseq ◽  
Urban Environments ◽  
High Load ◽  
Leishmania Infection ◽  
Experimental Conditions ◽  
Rural And Urban ◽  
Negative Effect

Pintomyia evansi is recognized by its vectorial competence in the transmission of parasites that cause fatal visceral leishmaniasis in rural and urban environments of the Caribbean coast of Colombia. The effect on and the variation of the gut microbiota in female P. evansi infected with Leishmania infantum were evaluated under experimental conditions using 16S rRNA Illumina MiSeq sequencing. In the coinfection assay with L. infantum, 96.8% of the midgut microbial population was composed mainly of Proteobacteria (71.0%), followed by Cyanobacteria (20.4%), Actinobacteria (2.7%), and Firmicutes (2.7%). In insect controls (uninfected with L. infantum) that were treated or not with antibiotics, Ralstonia was reported to have high relative abundance (55.1–64.8%), in contrast to guts with a high load of infection from L. infantum (23.4–35.9%). ASVs that moderately increased in guts infected with Leishmania were Bacillus and Aeromonas. Kruskal–Wallis nonparametric variance statistical inference showed statistically significant intergroup differences in the guts of P. evansi infected and uninfected with L. infantum (p < 0.05), suggesting that some individuals of the microbiota could induce or restrict Leishmania infection. This assay also showed a negative effect of the antibiotic treatment and L. infantum infection on the gut microbiota diversity. Endosymbionts, such as Microsporidia infections (<2%), were more often associated with guts without Leishmania infection, whereas Arsenophonus was only found in guts with a high load of Leishmania infection and treated with antibiotics. Finally, this is the first report that showed the potential role of intestinal microbiota in natural populations of P. evansi in susceptibility to L. infantum infection.

Semiconductor nano materials in the reconstruction of wearable human body sensor

2021 ◽  
pp. 1-14
Author(s):  
Junbai Pan ◽  
Yangong Zheng ◽  
Jinkai Jin ◽  
Xiang Cai ◽  
Chencheng Wang
Keyword(s):  
Human Body ◽  
Bp Neural Network ◽  
Zinc Concentration ◽  
Physiological Data ◽  
Processing Unit ◽  
Nano Materials ◽  
Experimental Conditions ◽  
Control Center ◽  
Physiological Signal ◽  
Central Processing

In view of the shortcomings of the current wearable human body sensor, such as poor comfort and low sensing accuracy, the application of semiconductor nano materials in the reconstruction of wearable human body sensor is studied. The best zinc concentration of 10 mm and the best reaction temperature of 75∘C were selected as experimental conditions to prepare the modified silk. The two ends of the silk sensor were connected by silver glue and wire respectively to form a single silk sensor. The sensor is placed in the wearable clothing of the wearable human body sensor, which uses the sensor to sense the physiological signal of human body and sends it to the control center. The central processing unit of the control center uses the data eigenvalue fusion decision-making method of BP neural network to process the physiological data of human body and then transmits it to the display terminal to realize the physiological data induction of human body. The experimental results show that the human body sensor can effectively sense human heart rate, blood oxygen signal, blood pressure and other physiological signals, and the sensing accuracy is above 97%.

scholarly journals Physical Activities and their Characteristics During Pandemic Times

2021 ◽  
Vol 26 (2) ◽  
pp. 156-162
Author(s):  
Fabiana Martinescu-Bădălan
Keyword(s):  
Human Body ◽  
Sedentary Lifestyle ◽  
Family Members ◽  
Physical Activities ◽  
Negative Effect ◽  
The Right ◽  
The Brain ◽  
Sports Activities

Abstract In this paper we wanted to present some aspects and characteristics observed in the specialized works and from the experience gained in performing physical activities during the COVID-19 pandemic. This period was a complicated one both in terms of physical distancing and emotionally. We no longer had the right to leave our houses, except to get what was strictly necessary, not to meet with family members or friends, cultural and sports activities were suspended, and all this caused an increasingly visible state of sedentary lifestyle. All the restrictions of this period had a negative effect mainly on the brain and the dynamics of the human body, and they are detailed in the following pages.

Activity Patterns and Energetics of the Moth, Hyalophora Cecropia

1970 ◽  
Vol 53 (3) ◽  
pp. 611-627
Author(s):  
JAMES L. HANEGAN ◽  
JAMES EDWARD HEATH
Keyword(s):  
Activity Patterns ◽  
Balance Sheet ◽  
Adult Life ◽  
Metabolic Cost ◽  
Hormonal Control ◽  
Energetic Cost ◽  
Air Temperatures ◽  
Hyalophora Cecropia ◽  
Metabolic Expenditure ◽  
Maintenance Metabolism

1. The time of activity and the duration of active periods (flight) of moths of the species Hyalophora cecropia has been determined by monitoring thoracic temperature. 2. The metabolic cost of flight per day and per adult life has been determined directly by measuring O2 consumption and indirectly by analysis of cooling curves of individual moths. 3. An energy balance sheet has been derived which gives the metabolic cost of flight and maintenance (during torpor) over the insect's adult life. 4. The metabolic stores mobilized for daily activity appear to be fixed and independent of air temperature. This mobilization of fat stores may be under hormonal control. 5. It is metabolically more expensive for moths to be active at low air temperatures. The number and duration of active periods at low air temperatures is reduced, but, the metabolic expenditure for activity is equal to that of animals held at higher air temperatures. 6. Females have a smaller total energy reserve than males. The number of active periods per day is not significantly different between the sexes at any given temperature, but in females the active periods are significantly shorter in duration. 7. The flight speed has been determined, and estimates of the flight range per day and per adult life have been calculated. 8. The ecology of H. cecropia has been discussed with respect to the timing and duration of active periods, the range and speed of flight, and the energetic cost of flight and maintenance metabolism.

scholarly journals Bioenergetics and Biomechanics of Handcycling at Submaximal Speeds in Athletes with a Spinal Cord Injury

Sports ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 16 ◽  
Author(s):  
Gabriela Fischer ◽  
Pedro Figueiredo ◽  
Luca Paolo Ardigò
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Rolling Resistance ◽  
Metabolic Cost ◽  
Mechanical Efficiency ◽  
Metabolic Power ◽  
Ecological Conditions ◽  
Air Resistance ◽  
Cord Injury ◽  
Biomechanical Parameters

Background: This study aimed at comparing bioenergetics and biomechanical parameters between athletes with tetraplegia and paraplegia riding race handbikes at submaximal speeds in ecological conditions. Methods: Five athletes with tetraplegia (C6-T1, 43 ± 6 yrs, 63 ± 14 kg) and 12 athletes with paraplegia (T4-S5, 44 ± 7 yrs, 72 ± 12 kg) rode their handbikes at submaximal speeds under metabolic measurements. A deceleration method (coasting down) was applied to calculate the rolling resistance and frontal picture of each participant was taken to calculate air resistance. The net overall Mechanical Efficiency (Eff) was calculated by dividing external mechanical work to the corresponding Metabolic Power. Results: Athletes with tetraplegia reached a lower aerobic speed (4.7 ± 0.6 m s−1 vs. 7.1 ± 0.9 m s−1, P = 0.001) and Mechanical Power (54 ± 15 W vs. 111 ± 25 W, P = 0.001) compared with athletes with paraplegia. The metabolic cost was around 1 J kg−1 m−1 for both groups. The Eff values (17 ± 2% vs. 19 ± 3%, P = 0.262) suggested that the handbike is an efficient assisted locomotion device. Conclusion: Handbikers with tetraplegia showed lower aerobic performances but a similar metabolic cost compared with handbikers with paraplegia at submaximal speeds in ecological conditions.

Develop a Flexible Regenerative Exoskeleton to Assist Walking

2018 ◽  
Author(s):  
Longhan Xie ◽  
Xiaodong Li
Keyword(s):  
Kinetic Energy ◽  
Human Body ◽  
Lower Limb ◽  
Metabolic Cost ◽  
Lower Limbs ◽  
Metabolic Energy ◽  
Lower Limb Exoskeleton ◽  
Negative Work ◽  
Lower Limb Muscles ◽  
Assisting Device

During walking, human lower limbs accelerate and decelerate alternately, during which period the human body does positive and negative work, respectively. Muscles provide power to all motions and cost metabolic energy both in accelerating and decelerating the lower limbs. In this work, the lower-limb biomechanics of walking was analyzed and it revealed that if the negative work performed during deceleration can be harnessed using some assisting device to then assist the acceleration movement of the lower limb, the total metabolic cost of the human body during walking can be reduced. A flexible lower-limb exoskeleton was then proposed; it is worn in parallel to the lower limbs to assist human walking without consuming external power. The flexible exoskeleton consists of elastic and damping components that are similar to physiological structure of a human lower limb. When worn on the lower limb, the exoskeleton can partly replace the function of the lower limb muscles and scavenge kinetic energy during lower limb deceleration to assist the acceleration movement. Besides, the generator in the exoskeleton, serving as a damping component, can harvest kinetic energy to produce electricity. A prototype of the flexible exoskeleton was developed, and experiments were carried out to validate the analysis. The experiments showed that the exoskeleton could reduce the metabolic cost by 3.12% at the walking speed of 4.5 km/h.

scholarly journals The mechanics and energetics of human walking and running: a joint level perspective

2011 ◽  
Vol 9 (66) ◽  
pp. 110-118 ◽  
Author(s):  
Dominic James Farris ◽  
Gregory S. Sawicki
Keyword(s):  
Power Output ◽  
Lower Limb ◽  
Metabolic Cost ◽  
Mechanical Work ◽  
Total Power ◽  
Joint Mechanics ◽  
Metabolic Power ◽  
Cost Of Transport ◽  
Cost Of Locomotion ◽  
Shed Light

Humans walk and run at a range of speeds. While steady locomotion at a given speed requires no net mechanical work, moving faster does demand both more positive and negative mechanical work per stride. Is this increased demand met by increasing power output at all lower limb joints or just some of them? Does running rely on different joints for power output than walking? How does this contribute to the metabolic cost of locomotion? This study examined the effects of walking and running speed on lower limb joint mechanics and metabolic cost of transport in humans. Kinematic and kinetic data for 10 participants were collected for a range of walking (0.75, 1.25, 1.75, 2.0 m s −1 ) and running (2.0, 2.25, 2.75, 3.25 m s −1 ) speeds. Net metabolic power was measured by indirect calorimetry. Within each gait, there was no difference in the proportion of power contributed by each joint (hip, knee, ankle) to total power across speeds. Changing from walking to running resulted in a significant ( p = 0.02) shift in power production from the hip to the ankle which may explain the higher efficiency of running at speeds above 2.0 m s −1 and shed light on a potential mechanism behind the walk–run transition.

Storage of DMFC MEA at Extreme Temperatures

2008 ◽  
Author(s):  
Ulrike Krewer ◽  
Junyoung Park ◽  
Jinhwa Lee ◽  
Hyejung Cho
Keyword(s):  
Reverse Current ◽  
Catalyst Loading ◽  
Membrane Electrode ◽  
Extreme Temperatures ◽  
Original Performance ◽  
Experimental Conditions ◽  
Low Temperature Storage ◽  
Electrode Assemblies ◽  
Negative Effect ◽  
Temperature Storage

This paper investigates the change in performance of DMFC membrane electrode assemblies (MEAs) after storage at −10°C and 60°C under different experimental conditions. It highlights the importance of methanol concentration, an MEA’s material properties such as membrane material and catalyst loading, as well as the reactivation procedure. Storage at 60°C and concentrations below 1M methanol had no negative effect on MEA performance while storage at 60°C in a 4 M methanol solution could cause a severe performance decrease. Application of a reverse current for 10 s to a MEA which was affected by such storage was found to reinstall original performance. The effect of storage at −10°C on MEA performance strongly depends on MEA properties. MEAs are grouped into three different categories with regard to suitability for low temperature storage: not affected, reversibly affected, and irreversibly affected. The reversibly affected MEAs could be instantly and completely reactivated by reverse current. MEA materials such as various hydrocarbon membranes and high catalyst loadings as well as the manufacturing methods CCM (catalyst coated on the membrane) and CCS (catalyst coated on the substrate) were found to be principally suitable to build MEAs tolerant to storage at −10° C.

In Vivo Behavior of Bioactive Glass-Based Hybrids in Animal Models For Bone Regeneration

2020 ◽  
Author(s):  
Shal N
Keyword(s):  
Bioactive Glass ◽  
Bone Regeneration ◽  
Bone Repair ◽  
Weight Bearing ◽  
Chemical Properties ◽  
Experimental Conditions ◽  
Wide Range ◽  
The Matrix ◽  
Hybrid Biomaterials

This review presents the recent advances and the current state-of-the-art of bioactive glass-based hybrid biomaterials for bone regeneration. Hybrid materials comprise two (or more) constituents at the nanometre scale, in which typically, one constituent is organic and functions as the matrix phase and the other constituent is inorganic and behaves as the filler phase. Such materials, thereby, more closely resemble natural bio-nanocomposites such as bone. Various glass compositions in combination with a wide range of natural and synthetic polymers have been evaluated in vivo under experimental conditions ranging from unloaded critical-sized defects to mechanically-loaded, weight-bearing sites with highly favourable outcomes. Additional possibilities include controlled release of anti-osteoporotic drugs, ions, antibiotics, pro-angiogenic substances and pro-osteogenic substances. Histological and morphological evaluations suggest the formation of new, highly vascularised bone that displays signs of remodelling over time. With the possibility to tailor the mechanical and chemical properties through careful selection of individual components, as well as the overall geometry (from mesoporous particles and micro-/nanospheres to 3D scaffolds and coatings) through innovative manufacturing processes, such biomaterials present exciting new avenues for bone repair and regeneration.

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