scholarly journals A Time Division Multiplexing Inspired Lightweight Soft Exoskeleton for Hip and Ankle Joint Assistance

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1150
Author(s):  
Xin Ye ◽  
Chunjie Chen ◽  
Yanguo Shi ◽  
Lingxing Chen ◽  
Zhuo Wang ◽  
...  
Keyword(s):  
Gait Cycle ◽  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Rectus Femoris ◽  
Loading Path ◽  
Time Division Multiplexing ◽  
Natural Motion ◽  
Actuation Scheme ◽  
Hip Flexion ◽  
Time Division

Exoskeleton robots are frequently applied to augment or assist the user’s natural motion. Generally, each assisted joint corresponds to at least one specific motor to ensure the independence of movement between joints. This means that as there are more joints to be assisted, more motors are required, resulting in increasing robot weight, decreasing motor utilization, and weakening exoskeleton robot assistance efficiency. To solve this problem, the design and control of a lightweight soft exoskeleton that assists hip-plantar flexion of both legs in different phases during a gait cycle with only one motor is presented in this paper. Inspired by time-division multiplexing and the symmetry of walking motion, an actuation scheme that uses different time-periods of the same motor to transfer different forces to different joints is formulated. An automatic winding device is designed to dynamically change the loading path of the assistive force at different phases of the gait cycle. The system is designed to assist hip flexion and plantar flexion of both legs with only one motor, since there is no overlap between the hip flexion movement and the toe-offs movement of the separate legs during walking. The weight of the whole system is only 2.24 kg. PD iterative control is accomplished by an algorithm that utilizes IMUs attached on the thigh recognizing the maximum hip extension angle to characterize toe-offs indirectly, and two load cells to monitor the cable tension. In the study of six subjects, muscle fatigue of the rectus femoris, vastus lateralis, gastrocnemius and soleus decreased by an average of 14.69%, 6.66%, 17.71%, and 8.15%, respectively, compared to scenarios without an exoskeleton.

scholarly journals Characterization of kinesiological patterns of the frontal kick, mae-geri, in karate experts and non-karate practitioners

2014 ◽  
Vol 9 (1) ◽  
pp. 20 ◽  
Author(s):  
António M. VencesBrito ◽  
Marco A. Colaço Branco ◽  
Renato M. Cordeiro Fernandes ◽  
Mário A. Rodrigues Ferreira ◽  
Orlando J. S. M. Fernandes ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Neuromuscular Control ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Maximum Speed ◽  
Ballistic Performance ◽  
The Impact

Presently, coaches and researchers need to have a better comprehension of the kinesiological parameters that should be an important tool to support teaching methodologies and to improve skills performance in sports. The aim of this study was to (i) identify the kinematic and neuromuscular control patterns of the front kick (<em>mae-geri</em>) to a fixed target performed by 14 experienced karate practitioners, and (ii) compare it with the execution of 16 participants without any karate experience, allowing the use of those references in the analysis of the training and learning process. Results showed that the kinematic and neuromuscular activity during the kick performance occurs within 600 ms. Muscle activity and kinematic analysis demonstrated a sequence of activation bracing a proximal-to-distal direction, with the muscles presenting two distinct periods of activity (1, 2), where the karateka group has a greater intensity of activation – root mean square (RMS) and electromyography (EMG) peak – in the first period on <em>Rectus Femoris</em> (RF1) and  <em>Vastus Lateralis</em> (VL1) and a lower duration of co-contraction in both periods on <em>Rectus Femoris</em>-<em>Biceps Femoris</em> and <em>Vastus Lateralis</em>-<em>Biceps Femoris</em> (RF-BF; VL-BF). In the skill performance, the hip flexion, the knee extension and the ankle plantar flexion movements were executed with smaller difference in the range of action (ROA) in the karateka group, reflecting different positions of the segments. In conclusion, it was observed a general kinesiological pattern, which was similar in karateka and non-karateka practitioners. However, in the karateka group, the training induces a specialization in the muscle activity reflected in EMG and kinematic data, which leads to a better ballistic performance in the execution of the <em>mae-geri</em> kick, associated with a maximum speed of the distal segments, reached closer to the impact moment, possibly representing more power in the contact.

scholarly journals Modelling of Muscle Force Distributions During Barefoot and Shod Running

2015 ◽  
Vol 47 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Jonathan Sinclair ◽  
Stephen Atkins ◽  
Jim Richards ◽  
Hayley Vincent
Keyword(s):  
Repeated Measures ◽  
Sagittal Plane ◽  
Vastus Lateralis ◽  
Reaction Force ◽  
Rectus Femoris ◽  
Camera Motion ◽  
Barefoot Running ◽  
Chronic Injuries ◽  
Analysis System ◽  
Hip Flexion

Abstract Research interest in barefoot running has expanded considerably in recent years, based around the notion that running without shoes is associated with a reduced incidence of chronic injuries. The aim of the current investigation was to examine the differences in the forces produced by different skeletal muscles during barefoot and shod running. Fifteen male participants ran at 4.0 m·s-1 (± 5%). Kinematics were measured using an eight camera motion analysis system alongside ground reaction force parameters. Differences in sagittal plane kinematics and muscle forces between footwear conditions were examined using repeated measures or Freidman’s ANOVA. The kinematic analysis showed that the shod condition was associated with significantly more hip flexion, whilst barefoot running was linked with significantly more flexion at the knee and plantarflexion at the ankle. The examination of muscle kinetics indicated that peak forces from Rectus femoris, Vastus medialis, Vastus lateralis, Tibialis anterior were significantly larger in the shod condition whereas Gastrocnemius forces were significantly larger during barefoot running. These observations provide further insight into the mechanical alterations that runners make when running without shoes. Such findings may also deliver important information to runners regarding their susceptibility to chronic injuries in different footwear conditions.

scholarly journals Effect of acute noxious stimulation to the leg or back on muscle synergies during walking

2015 ◽  
Vol 113 (1) ◽  
pp. 244-254 ◽  
Author(s):  
Wolbert van den Hoorn ◽  
Paul W. Hodges ◽  
Jaap H. van Dieën ◽  
François Hug
Keyword(s):  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Rectus Femoris ◽  
Muscle Synergy ◽  
Noxious Stimulation ◽  
Muscle Synergies ◽  
Muscle Coordination ◽  
Painful Condition ◽  
Leg Muscles ◽  
Pain Location

This study aimed to examine how acute muscle pain affects muscle coordination during gait with consideration of muscle synergies (i.e., group of muscles activated in synchrony), amplitude of muscle activity and kinematics. A secondary aim was to determine whether any adaptation was specific to pain location. Sixteen participants walked on a treadmill during 5 conditions [control, low back pain (LBP), washout LBP, calf pain (CalfP), and washout CalfP]. Five muscle synergies were identified for all of the conditions. Cross-validation analysis showed that muscle synergy vectors extracted for the control condition accounted for >81% of variance accounted for from the other conditions. Muscle synergies were altered very little in some participants ( n = 7 for LBP; n = 10 for CalfP), but were more affected in the others ( n = 9 for LBP; n = 6 for CalfP). No systematic differences between pain locations were observed. Considering all participants, synergies related to propulsion and weight acceptance were largely unaffected by pain, whereas synergies related to other functions (trunk control and leg deceleration) were more affected. Gastrocnemii activity was less during both CalfP and LBP than control. Soleus activity was further reduced during CalfP, and this was associated with reduced plantar flexion. Some lower leg muscles exhibited adaptations depending on pain location (e.g., greater vastus lateralis and rectus femoris activity during CalfP than LBP). Overall, these changes in muscle coordination involve a participant-specific strategy that is important to further explore, as it may explain why some people are more likely to develop persistence of a painful condition.

The Effects of Ankle Position on Torque and Muscle Activity of the Knee Extensor During Maximal Isometric Contraction

2020 ◽  
Vol 29 (1) ◽  
pp. 37-42
Author(s):  
Dae-Hyun Kim ◽  
Jin-Hee Lee ◽  
Seul-Min Yu ◽  
Chang-Man An
Keyword(s):  
Isometric Contraction ◽  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Isometric Exercise ◽  
Rectus Femoris ◽  
Peak Torque ◽  
Emg Activity ◽  
Neutral Position ◽  
Vastus Medialis ◽  
Maximal Voluntary Isometric Contraction

Context: It is very important to empirically determine the optimal ankle position for the quadriceps femoris (QF) strengthening during isometric exercises. Objective: To examine the effect of different ankle positions on torque and electromyography (EMG) activity of QF during maximal isometric contraction. Study Design: Within-subject repeated measures. Setting: University laboratory. Participants: Thirty-six healthy volunteers (15 males and 21 females). Main Outcome Measures: The isometric strength of the QF was measured at 3 different ankle positions: active dorsiflexion (AD), active plantar flexion (AP), and neutral position (NP). Simultaneously, 3 different ankle positions were assessed for EMG activity of the vastus medialis, vastus lateralis, and rectus femoris muscles during maximal voluntary isometric contraction. Results: The peak torque per body weight and average peak torque were significantly higher in AD than in AP and NP (P < .01). The vastus medialis and rectus femoris maximal voluntary isometric contraction EMG activity were significantly higher in AD than in AP and NP (P < .01). The vastus lateralis maximal voluntary isometric contraction EMG activity was significantly higher in AD than in AP and NP (P < .01), and was significantly higher in AP than in NP (P < .05). Conclusions: These results indicate that the 3 different ankle positions affect the QF torque and EMG activity. In particular, AD position may be more efficient for improving QF strength than AP and NP position. Future studies should prove whether long-term duration QF isometric exercise effects muscle strength and functional performance in different ankle positions.

scholarly journals A Novel Lightweight Wearable Soft Exosuit for Reducing the Metabolic Rate and Muscle Fatigue

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 215
Author(s):  
Lingxing Chen ◽  
Chunjie Chen ◽  
Zhuo Wang ◽  
Xin Ye ◽  
Yida Liu ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
The Novel ◽  
Robotic Devices ◽  
Extra Weight ◽  
Hip Flexion ◽  
Rehabilitation Exercises ◽  
Hip Extension ◽  
Soft Exosuit

Wearable robotic devices have been proved to considerably reduce the energy expenditure of human walking. It is not only suitable for healthy people, but also for some patients who require rehabilitation exercises. However, in many cases, the weight of soft exosuits are relatively large, which makes it difficult for the assistant effect of the system to offset the metabolic consumption caused by the extra weight, and the heavy weight will make people uncomfortable. Therefore, reducing the weight of the whole system as much as possible and keeping the soft exosuit output power unchanged, may improve the comfort of users and further reduce the metabolic consumption. In this paper, we show that a novel lightweight soft exosuit which is currently the lightest among all known powered exoskeletons, which assists hip flexion. Indicated from the result of experiment, the novel lightweight soft exosuit reduces the metabolic consumption rate of wearers when walking on the treadmill at 5 km per hour by 11.52% compared with locomotion without the exosuit. Additionally, it can reduce more metabolic consumption than the hip extension assisted (HEA) and hip flexion assisted (HFA) soft exosuit which our team designed previously, which has a large weight. The muscle fatigue experiments show that using the lightweight soft exosuit can also reduce muscle fatigue by about 10.7%, 40.5% and 5.9% for rectus femoris, vastus lateralis and gastrocnemius respectively compared with locomotion without the exosuit. It is demonstrated that decreasing the weight of soft exosuit while maintaining the output almost unchanged can further reduce metabolic consumption and muscle fatigue, and appropriately improve the users’ comfort.

Form Switching During Human Locomotion: Traversing Wedges in a Single Step

2000 ◽  
Vol 84 (2) ◽  
pp. 605-615 ◽  
Author(s):  
Gammon M. Earhart ◽  
Amy J. Bastian
Keyword(s):  
Neural Control ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Single Step ◽  
Level Surface ◽  
Heel Strike ◽  
Joint Angles ◽  
Hip Flexion ◽  
Anterior Tibialis

We examined the neural control strategies used to accommodate discrete alterations in walking surface inclination. Normal subjects were tested walking on a level surface and on different wedges (10°, 15°, 20°, and 30°) presented in the context of level walking. On a given trial, a subject walked on a level surface in approach to a wedge, took a single step on the wedge, and continued walking on an elevated level surface beyond the wedge. As wedge inclination increased, subjects linearly increased peak joint angles. Changes in timing of peak joint angles and electromyograms were not linear. Subjects used two distinct temporal strategies, or forms, to traverse the wedges. One form was used for walking on a level surface and on the 10° wedge, another form for walking on the 20° and 30° wedges. In the level/10° form, peak hip flexion occurred well before heel strike (HS) and peak dorsiflexion occurred in late stance. In the 20°/30° form, peak hip flexion was delayed by 12% of the stride cycle and peak dorsiflexion was reached 12% earlier. For the level/10° form, onsets of the rectus femoris, gluteus maximus, and vastus lateralis muscles were well before HS and offset of the anterior tibialis was at HS. For the 20°/30° form, onsets of the rectus femoris, gluteus maximus, and vastus lateralis and offset of the anterior tibialis were all delayed by 12% of the stride cycle. Muscles shifted as a group, rather than individually, between the forms. Subjects traversing a 15° wedge switched back and forth between the two forms in consecutive trials, suggesting the presence of a transition zone. Differences between the forms can be explained by the differing biomechanical constraints imposed by the wedges. Steeper wedges necessitate changes in limb orientation to accommodate the surface, altering limb orientation with respect to gravity and making it necessary to pull the body forward over the foot. The use of different forms of behavior is a common theme in neural control and represents an efficient means of coordinating and adapting movement to meet changing environmental demands. The forms of locomotion reported here are likely used on a regular basis in real-world settings.

Characteristics of Contact Force and Muscle Activation During Choreographed Falls With 2 Common Landing Techniques in Contemporary Dance

2019 ◽  
Vol 35 (4) ◽  
pp. 256-262
Author(s):  
Chad Van Ramshorst ◽  
Woochol Joseph Choi
Keyword(s):  
Muscle Activation ◽  
Plantar Flexion ◽  
Knee Injuries ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Contact Forces ◽  
Contemporary Dance ◽  
Maximal Voluntary Isometric Contraction ◽  
Collegiate Level ◽  
Hip Flexion

This study investigated the contact forces and muscle activation during 2 choreographed fall techniques in contemporary dancers and how these were affected by the fall technique. Ten collegiate-level dancers were instructed in 2 choreographed falls: (1) an anteriorly focused fall involving ankle plantar flexion, knee flexion, and hip flexion with dispersion of forces up the anterior surface of the shank (technique 1) and (2) a laterally focused fall involving inversion at the ankle with dispersion of forces up the lateral aspect of the shank (technique 2). The knee and hip contact forces were 26.3% smaller (technique 1: 1743 N vs technique 2: 1284 N) and 24.1% greater (technique 1: 1334 N vs technique 2: 1656 N), respectively, in technique 2 (P < .03). At the time of knee contact, percentage of maximal voluntary isometric contraction (%MVIC) was 45.8% greater for rectus femoris muscle (technique 1: 7.2% vs technique 2: 10.5%) and 96.9% greater for gluteus medius muscle (technique 1: 3.2% vs technique 2: 6.3%) (P < .01) in technique 2. The results provide insight into determining safer landing strategies to avoid knee injuries in individuals who experience a fall (ie, dancers, athletes, and older adults).

scholarly journals Klasifikasi Sinyal Emg Pada Otot Tungkai Selama Berjalan Menggunakan Random Forest

2017 ◽  
Vol 1 (1) ◽  
pp. 51
Author(s):  
Darma Setiawan Putra ◽  
Adhi Dharma Wibawa ◽  
Mauridhi Hery Purnomo
Keyword(s):  
Principal Component Analysis ◽  
Feature Extraction ◽  
Random Forest ◽  
Gait Cycle ◽  
Cross Validation ◽  
Vastus Lateralis ◽  
Principal Component ◽  
Rectus Femoris ◽  
Component Analysis ◽  
Gastrocnemius Lateralis

Sinyal electromyography (EMG) merupakan suatu sinyal elektrik yang terdapat dalam lapisan otot selama gerakan aktif. Cara orang berjalan ditentukan oleh struktur otot dan tulang sehingga cara berjalan ini adalah unik dan dapat digunakan sebagai data biometrik. Pada penelitian ini, kami mengklasifikasi data EMG dari delapan jenis otot tungkai selama percobaan berjalan normal: Rectus Femoris, Vastus Lateralis, Vastus Medialis, Bicep Femoris, Semitendinosus, Gastrocnemius Lateralis, Gastrocnemius Medialis, dan Tibialis Anterior. Enam orang subyek diminta untuk berjalan di laboratorium GaitLab dengan 8 buah elektroda EMG ditempel pada otot mereka. Subyek diminta untuk berjalan sebanyak 1 gait cycle dengan 3 kali pengambilan data. Total dataset EMG untuk klasifikasi adalah sebanyak 18 buah. Metode graph feature extraction dan principal component analysis digunakan untuk ekstraksi fitur data EMG. Metode Random Forest digunakan untuk mengklasifikasi data EMG berdasarkan subyek. Metode pelatihan dan pengujian data EMG menggunakan cross validation (CV). Akurasi klasifikasi yang dihasilkan dengan menggunakan metode graph feature extraction adalah sebesar 88.88% dan metode principal component analysis adalah sebesar 72.22%. Hasil ini menunjukkan bahwa data EMG ketika berjalan dari 8 jenis otot tungkai dapat digunakan untuk identitas biometrik gaya berjalan (gait).

Full-parallax 3D display using time-multiplexing projection technology

2020 ◽  
Vol 2020 (2) ◽  
pp. 100-1-100-6
Author(s):  
Takuya Omura ◽  
Hayato Watanabe ◽  
Naoto Okaichi ◽  
Hisayuki Sasaki ◽  
Masahiro Kawakita
Keyword(s):  
Incident Light ◽  
Polarization State ◽  
3D Image ◽  
3D Display ◽  
Time Division Multiplexing ◽  
3D Images ◽  
Polarization Gratings ◽  
Light Rays ◽  
Time Division

We enhanced the resolution characteristics of a threedimensional (3D) image using time-division multiplexing methods in a full-parallax multi-view 3D display. A time-division light-ray shifting (TDLS) method is proposed that uses two polarization gratings (PGs). As PG changes the diffraction direction of light rays according to the polarization state of the incident light, this method can shift light rays approximately 7 mm in a diagonal direction by switching the polarization state of incident light and adjusting the distance between the PGs. We verified the effect on the characteristics of 3D images based on the extent of the shift. As a result, the resolution of a 3D image with depth is improved by shifting half a pitch of a multi-view image using the TDLS method, and the resolution of the image displayed near the screen is improved by shifting half a pixel of each viewpoint image with a wobbling method. These methods can easily enhance 3D characteristics with a small number of projectors.

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