Journal of Biomechanical Science and Engineering
Online ISSN : 1880-9863
ISSN-L : 1880-9863
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Displaying 1-5 of 5 articles from this issue
Papers
  • Tomohito KURODA, Shogo OKAMOTO, Yasuhiro AKIYAMA
    2024 Volume 19 Issue 1 Pages 23-00183
    Published: 2024
    Released on J-STAGE: January 15, 2024
    Advance online publication: July 16, 2023
    JOURNAL OPEN ACCESS

    The margin of stability (MoS) is a gait stability index with good validity. MoS is computed in the anterior and mediolateral directions. However, their relationship has not been well investigated. Furthermore, previous studies have little investigated the differences in MoS between distinct age groups. Inter-age comparisons reveal age-specific walking characteristics and their effects on stability. In this study, we used multiple indicators and multiple causes model, which is a type of structural equation modeling, to investigate the statistical relationships between various types of gait parameters and MoSs for each of the healthy participant groups over 60 and in their 20s. For the analysis, data from 120 individuals were obtained from a gait database. The model for the younger group showed that the MoSs in the anterior and mediolateral directions were mostly separated. The stability in the anterior direction was independent of the stability in the mediolateral direction. In contrast, some gait parameters simultaneously affected the two MoSs in the elderly group. The stability in the anterior and mediolateral directions was interdependent. For example, forward walking speed influenced the anterior and mediolateral MoSs in the elderly group, whereas it influenced only the anterior MoS in the younger group. These findings suggest that the age of people must be considered when discussing gait characteristics that contribute to stability.

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  • Akisue KURAMOTO, Motomu NAKASHIMA
    2024 Volume 19 Issue 1 Pages 22-00469
    Published: 2024
    Released on J-STAGE: January 15, 2024
    Advance online publication: September 01, 2023
    JOURNAL OPEN ACCESS

    This study aims to confirm the effects of a neck pillow on the postural stability of the head and neck and the variance of center of mass in a sitting position. Experiments were conducted on keeping a sitting posture at rest with and without the use of two types of neck pillows; the neck wrap pillow and the front neck pillow. During experiments, whole body posture was recorded by a motion capture system. Differences in head-and-neck postural stability and center of mass variance in the resting sitting position were statistically compared among the neck pillow conditions. As a result, it was confirmed that the front neck pillow increases the postural stability of the head and neck in a resting sitting position and reduces the variation of the center of mass.

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  • Naoto HARAGUCHI, Kazunori HASE
    2024 Volume 19 Issue 1 Pages 23-00130
    Published: 2024
    Released on J-STAGE: January 15, 2024
    Advance online publication: September 15, 2023
    JOURNAL OPEN ACCESS

    Predicting the ground reaction force (GRF) and ground reaction moment (GRM) with a biomechanical model-based approach has an advantage for biomechanical gait analysis in situations where a statistical model cannot be used due to a lack of training data. However, the current prediction methods using a biomechanical model have some issues for clinical application. The present study developed a new inertial measurement unit (IMU)-based method to predict the GRF, the GRM, and the joint kinematics and kinetics with a 3D biomechanical model and simple system. The present method predicts them using a 3D forward dynamics model that computationally generates human movements that minimize the hybrid cost function defined by physical loads and errors between the motion of the model and that of the participants recorded by six IMUs, which allows the prediction system to use only a relatively small number of IMUs. We investigated the prediction accuracy during walking by comparing the new method with a conventional analysis using a force plate and motion capture system. As a result, we observed strong and excellent correlations between the prediction and measurement of the anterior GRF, vertical GRF, sagittal GRM, hip flexion angle, knee flexion angle, hip flexion torque, and ankle dorsiflexion torque. Considering the accuracy of previous studies and that required for gait analysis, the present method could predict them with practical accuracy due to estimated biomechanically valid motions based on optimization using the hybrid cost function that includes a biomechanical evaluation. Moreover, the prediction system has an advantage for clinical applications because the present method observed practical accuracy that has the potential to be applied to some sports analysis and can analyze 3D motion with a simple system consisting of a small number of hardware components and a software.

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  • Toru HAMASAKI, Yuko NAKAHIRA, Daisuke YAMADA
    2024 Volume 19 Issue 1 Pages 23-00102
    Published: 2024
    Released on J-STAGE: January 15, 2024
    Advance online publication: November 09, 2023
    JOURNAL OPEN ACCESS

    The evaluation of tactile sensitivity involving frictional behavior via computational models can further accelerate the development of industrial products in terms of usability. This study aimed to confirm the capability of a previously proposed mechano-neurophysiological model, representing the basic mechanical (i.e., finger skin deformation) and neurophysiological (i.e., neural activities of slowly adapting type-1 (SA1) afferents) functions in the tactile sensation process, for simulating tactile responses during Braille reading under multiple frictional conditions. A previous psychophysical experiment on tactile recognition during Braille reading reported that the misread rate was significantly higher at frictional coefficient (μ) = 2.62 than at μ = 0.56, whereas no significant differences were observed between the misread rates at μ = 0.25 and 0.77. The Braille reading experiment was simulated using the mechano-neurophysiological model to achieve the present aim. The simulation results revealed marginal differences in the SA1 responses between μ = 0.25 and 0.77, and the correlation coefficients between the SA1 responses and Braille patterns were 0.98 at μ = 0.25 and 0.96 at μ = 0.77, suggesting a limited influence of friction on Braille recognition. However, the SA1 responses varied considerably between μ = 0.56 and 2.62, and the correlation coefficients were 0.97 at μ = 0.56 and 0.49 at μ = 2.62, implying a relatively strong influence of friction. The simulation results supported the above-mentioned findings of the previous psychophysical experiment, thereby demonstrating that the mechano-neurophysiological model qualitatively determined the tendency of influence of friction on Braille recognition.

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  • Tsutomu TAJIKAWA, Mitsuru HIRONO, Masayuki TANAKA, Ryosuke YANO, Kyoko ...
    2024 Volume 19 Issue 1 Pages 23-00350
    Published: 2024
    Released on J-STAGE: January 15, 2024
    Advance online publication: November 11, 2023
    JOURNAL OPEN ACCESS

    The thrombus formation process has yet to be fully simulated, which necessitates the design of a novel method for the quantitative assessment of device thrombogenicity that complements animal experiments/ex vivo experiments using animal blood and computational fluid dynamics analysis. This study aimed to develop a model blood capable of simulating the formation of red thrombus owing to stagnation of blood flow by applying the phenomenon of milk clot formation. To render the rheological properties of skim milk solution used as a model blood closer to those of human blood, the ratio of the amounts of casein in skim milk, calcium chloride, and rennet (constituents of the solution of the model blood) was varied and the rheological properties of the clot formation process of human blood and skim milk solution were measured using a cone-plate viscometer. Comparisons of the rheological properties of human blood and skim milk solutions during clotting revealed that during clot formation of human blood, four characteristic quantities of the time-series change in rheological properties were observed: the viscosity before clotting, coagulation start time, viscosity increase rate, and first yield viscosity. Further, hypercoagulable skim milk solutions with rheological properties similar to those of human blood were prepared by adjusting the solution composition ratio. When this model blood was circulated in a closed-loop circuit with a saccular aneurysm model, the growth rate of skim milk clot formation in the aneurysm model was significantly different in a flow diverter stent model and a micro-porous covered stent. The variation in porosity between these two stent models has a direct impact on the rate of embolisation. The proposed blood model can effectively replicate the formation of red thrombus, providing a valuable means to accurately and quantitatively assess the therapeutic efficacy of embolisation devices.

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