Journal of Biomechanical Science and Engineering
Online ISSN : 1880-9863
ISSN-L : 1880-9863
Volume 8, Issue 1
Displaying 1-8 of 8 articles from this issue
  • Toshikazu MATSUI, Keisuke HAGIWARA, Kazunori WADA
    2013 Volume 8 Issue 1 Pages 1-16
    Published: 2013
    Released on J-STAGE: February 04, 2013
    This research formulates an optimal control model that reproduces human rising movements from a chair (sit-to-stand movements). The model switches its dynamics from a one-link and one-joint structure to a three-link and three-joint one at the time (switching time) when its body moves away from a chair and optimizes its criterion function composed of three kinds of energy costs, a center-of-gravity cost, and an input cost. The research clarifies the model's performance in reproducing human sit-to-stand movements and discusses factors indispensable for rising from a chair. The following results are derived: (1) the model has the ability to produce various kinds of sit-to-stand movements by adjusting the weight of the input cost (input weight) and the switching time; (2) the input cost during sitting on the chair strongly affects the model's performance, whereas the energy costs and the center-of-gravity cost hardly do so; (3) there exists the optimal relation between the input weight and the switching time, and the sit-to-stand movements predicted according to the optimal relation agree well with the measured ones. These results suggest that the proposed model can be a plausible and effective model of the human sit-to-stand mechanism and that the input weight and the switching time can be factors indispensable for rising from a chair.
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  • Keiichi NAKAGAWA, Akira TSUKAMOTO, Tatsuhiko ARAFUNE, Hongen LIAO, Ets ...
    2013 Volume 8 Issue 1 Pages 17-26
    Published: 2013
    Released on J-STAGE: March 15, 2013
    To provide shock-wave exposure with high accuracy and widen the application area of shock-wave therapy, a miniaturized shock-wave device for endoscopic surgery was developed. The shock-wave device applies an electrohydraulic mechanism for generating shock waves in light of device miniaturization and suitability for standard clinical practice. The outer diameter of the shock-wave generator is 11 mm, so it can be inserted in the body through a trocar used in endoscopic surgery or a natural orifice in the case of natural-orifice translumenal endoscopic surgery (NOTES). The distance between the shock-wave focal point and the front of the device is 10 mm. The focused shock wave was observed at the focal point by visualization with the schlieren imaging technique. The pressure at the focal point was measured, and the measurement revealed that the device can produce a peak pressure of 2.32±0.81 MPa at 2-kV discharge voltage, 3.69±1.06 MPa at 3 kV, 5.67±2.44 MPa at 4 kV, and 7.27±2.33 MPa at 5 kV.
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  • Shunji HIROKAWA, Michihiko FUKUNAGA
    2013 Volume 8 Issue 1 Pages 27-39
    Published: 2013
    Released on J-STAGE: March 28, 2013
    Knee joint forces are determined either through mathematical modeling or by in vivo measurement using an instrumented knee prosthesis. In the model studies, significant differences exist among the results and the data for high knee flexion are few. The in vivo measurement data are available for small to moderate flexion but not for high flexion yet. We created a 2D mathematical model of the lower limb incorporating several new features such as a patello-femoral mechanism, a thigh-calf contact at high knee flexion and co-contracting muscles' force ratio, then used it to determine knee joint forces arising from high knee flexions in four kneeling conditions: rising with legs in parallel, with one foot forward, with or without arm use. With arms used, the maximum values of knee joint force decreased to about 60% of those with arms not used. When rising with one foot forward, if arms are not used, the forward leg sustains a force as large as that sustained when rising with legs parallel. By comparing our modeling methodology and results with those in the literature, we determined some of the causes of the differences in the results, thereby providing creditable data especially during high flexion of the knee.
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  • Kiyoshi BANDO
    2013 Volume 8 Issue 1 Pages 40-48
    Published: 2013
    Released on J-STAGE: April 15, 2013
    An analysis of the compressive deformation of alginate-poly(L)lysine-alginate (APA) microcapsules by two rigid parallel plates was performed under the assumptions that the bending stiffness and permeability of the membrane were negligible. The static equilibrium equations of force for axisymmetric elastic deformation were solved using the Runge-Kutta method with the constraint of constant microcapsule volume during deformation. The constitutive laws of a neo-Hookean material and that proposed by Evans and Skalak(1) were used. The Young's modulus of the membrane was determined by an atomic force microscopy (AFM)-based technique, and a comparison with a semianalytical solution neglecting the shear stiffness of the membrane validated the present analysis method. The force-displacement curve for the compressive deformation of an APA microcapsule is calculated and compared with the experimentally measured result. A nonlinear increase in the transmural pressure with increasing displacement and the meridional and circumferential stress resultant distributions near rupture of the membrane are also shown.
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  • Akira IWAMA, Kozue ISHIBASHI, Aya AMAMORI, Kazuhiro OURA, Yu TANAKA, T ...
    2013 Volume 8 Issue 1 Pages 49-62
    Published: 2013
    Released on J-STAGE: April 16, 2013
    The effects of temperature dependency of cooling rate arising in the thickness direction during freezing on post-thaw cell viability in oriented cell monolayers simulating thick tissue implants of about 20 mm in thickness was investigated. Human dermal fibroblasts were cultured on a grooved substrate of 24 × 24 mm for 24 hours; a test sample of an oriented cell monolayer was prepared. This sample was placed perpendicularly in an experimental container, frozen from the bottom at 0.2, 0.3 or 0.5°C/min from 4 to -40°C, cooled to below -180°C, and then thawed. Post-thaw cell viability was evaluated. These conditions were designated as variation conditions. To determine the cooling rate in each part, temperature was measured during freezing in three regions corresponding to the thickness direction; 4, 12 and 20 mm from the lower end of the substrate. Furthermore, post-thaw cell viability of samples frozen with level placement and constant cooling rates was evaluated for comparison; these conditions were known as constant conditions. As a result, the cooling rate of each part had a convex curve as a function of temperature, and maximum deviation of the cooling rate between each region and the control region increased with distance from the lower end of the sample. Cell viability, in contrast to the decline in average cooling rate from -7 to -40°C under variation conditions, was much lower than that under constant conditions. Thus, the temperature dependency of cooling rate arising in the thickness direction affected post-thaw cell viability in thick tissue implants.
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  • Enguo CAO, Yoshio INOUE, Tao LIU, Kyoko SHIBATA
    2013 Volume 8 Issue 1 Pages 63-78
    Published: 2013
    Released on J-STAGE: April 24, 2013
    As it is inconvenient to directly measure tension forces of muscles attaching on limbs, an inverse dynamic approach for quantitative muscle force estimation during human standing-up process was developed. In the standing-up experiment, a rehabilitation robot was used for offering assistance and measuring dynamic parameters of body segments. Ground reaction force (GRF) and center of pressure (COP) of human body, rotational motions of trunk, thigh and shank were real-time measured by the sensors of the robot system. Meanwhile, the AnyBody Modeling System was adopted for calculating muscle forces of lower limbs. In AnyBody Modeling System, a musculoskeletal model composed of thigh, shank, foot, four joints and fifteen muscles was developed. The GRF, COP and motion data measured with sensors were imported into the model, and then the tension forces of muscles of lower limb were calculated through an inverse dynamics method. Furthermore for the validation of the rehabilitation experiment, the activation levels of muscles were also directly measured by an electromyography (EMG) system, and the calculated AnyBody results matched the measured EMG results. Therefore, this muscle force estimation approach appears to be practical for determining muscle forces in the musculoskeletal analysis of human limbs.
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  • Motomu NAKASHIMA, Shingo SUZUKI, Ayako ONO, Takashi NAKAMURA
    2013 Volume 8 Issue 1 Pages 79-93
    Published: 2013
    Released on J-STAGE: May 02, 2013
    The objective of this study was to develop a prototype of transfemoral prosthesis for swimming focused on the ankle joint motion. This prosthesis has (i) an ankle joint which provides appropriate foot motion, (ii) the capability of walking on land by the poolside, (iii) and a foot whose appearance is sufficiently similar to an actual one. In order to confirm the validity of the developed prosthesis, a swimming experiment, in which a subject swimmer swam in a pool with the developed prosthesis attached, was conducted. The joint angles of the lower limbs were measured and an evaluation with questionnaires was performed. The validity of the proposed prosthesis was experimentally confirmed since the movable ankle joint with an appropriate spring brought a large foot motion, yielding a better swimming performance and more comfort to the swimmer. In addition to the experiment, the simulation of the swimming movement with the prosthesis was conducted. Through the simulation, the general validity of the developed prosthesis was confirmed since the simulation's result exhibited the same tendency as the experiment, in which a spring constant that was too large for the extension spring brought worse swimming performance.
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  • Tatsushi TOKUYASU, Shimpei MATSUMOTO
    2013 Volume 8 Issue 1 Pages 94-103
    Published: 2013
    Released on J-STAGE: June 06, 2013
    The saddle height of a cycle road racer influences the competitive performance of the cyclist. Cyclists can adjust the saddle height carefully according to their kinesthetic sense while riding a bicycle. The saddle height control system we have developed consists of a saddle height control device and a measurement instrument for a surface electromyogram (SEMG). The evaluation criteria for the saddle height based on SEMG signals, which are measured from the leg muscles during pedaling exercise, are established. Our experiments indicate that the saddle height was controlled at a relatively low level regardless of the cycling level of the subjects. The effects of muscle fatigue due to pedaling exercise are suspected to affect these experimental results.
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