근육 파라미터 최적화를 통한 발목관절 모멘트 추정 모델 개발 및 평가

손종상,황성재,이진섭,김영호,Son, J.,Hwang, S.,Lee, J.,Kim, Y.H. 대한의용생체공학회 2010 의공학회지 Vol.31 No.4

Estimation of muscle forces is important in biomechanics, therefore many researchers have tried to build a muscle model. Recently, optimization techniques for adjusting muscle parameters, i.e. EMG-driven model, have been used to estimate muscle forces and predict joint moments. In this study, an EMG-driven model based on the previous studies has been developed and isometric and isokinetic contraction movements were evaluated to validate the developed model. One healthy male participated in this study. The dynamometer tasks were performed for maximum voluntary isometric contractions (MVIC) for ankle dorsi/plantarflexors, isokinetic contraction at both $30^{\circ}/s$ and $60^{\circ}/s$. EMGs were recorded from the tibialis anterior, gastrocnemius medialis, gastrocnemius lateralis and soleus muscles at the sampling rate of 1000 Hz. The MVIC trial was used to customize the EMG-driven model to the specific subject. Once the subject's own model was developed, the model was used to predict the ankle joint moment for the other two dynamic movements. When no optimization was applied to characterize the muscle parameters, weak correlations were observed between the model prediction and the measured joint moment with large RMS error over 100% (r = 0.468 (123%) and r = 0.060 (159%) in $30^{\circ}/s$ and $60^{\circ}/s$ dynamic movements, respectively). However, once optimization was applied to adjust the muscle parameters, the predicted joint moment was highly similar to the measured joint moment with relatively small RMS error below 40% (r = 0.955 (21%) and r = 0.819 (36%) and in $30^{\circ}/s$ and $60^{\circ}/s$ dynamic movements, respectively). We expect that our EMG-driven model will be employed in our future efforts to estimate muscle forces of the elderly.

MVC 상태에서의 무릎관절 모멘트 추정을 위한 모델 개발

남윤수,이우은,Nam, Yoon-Su,Lee, Woo-Eun 대한의용생체공학회 2008 의공학회지 Vol.29 No.3

This paper introduces a method of estimating the knee joint moment developed during MVC. By combining the Hill-type muscle model and analytic results on moment arm and musculotendon length change as a function of hip and knee joint angle, the knee joint moment at a specific knee joint angle during MVC is determined. Many differences between the estimated results and the experimental data are noted. It is believed that these differences originate from inaccurate information on the muscle-tendon parameters. The establishment of exact values for the subject's muscle parameters is almost impossible task. However, sensitivity analysis shows that the tendon slack length is the most critical parameter when applying the Hill-type muscle model. The effect of a change of this parameter on the muscle length force relationship is analyzed in detail.

최적화기법에 의한 근육-건 모델 파라미터들의 추정

남윤수(Yoonsu Nam) Korean Society for Precision Engineering 2009 한국정밀공학회지 Vol.26 No.6

The analysis of human movement requires the knowledge of the Hill type muscle parameters, the muscle-tendon and moment arm length change as a function of joint angles. However, values of a subject’s muscle parameters are very difficult to identify. It turns out from a sensitivity analysis that the tendon slack length and maximum muscle force are the two critical parameters among the Hill-type muscle model. Therefore, it could be claimed that the variation of the tendon slack length and maximum muscle force from the Delp’s reference data will change the muscle characteristics of a subject remarkably. A numeric optimization method to search these tendon parameters specific to a subject is proposed, and the accuracy of the developed algorithm is evaluated through a numerical simulation.

자연과학편 : 태권도 돌려차기 동작의 동역학적 협응과 제어과정

윤창진(ChangJinYoon),채원식(WoenSikChae) 한국체육학회 2011 한국체육학회지 Vol.50 No.3

본 연구는 남자 중학교 초보피험자 9명을 대상으로 태권도 돌려차기 동작의 숙련정도에 따른 운동역학적 협응 및 제어 과정을 살펴보는 데 목적을 두었다. 자료산출을 위한 실험은 연습전, 1주 연습 후, 2주 연습 후, 3주 연습 후 각각에 대해 운동학(kinematics)과 운동역학(kinetics)적인 자료들을 수집하였다. 분석결과, 엉덩관절에서 운동종속력은 연습전에 양(+)의 방향을 나타내면서 타격이 이루어지고 연습이 이루어지고 난 뒤에는 타격시점 직전에 음(-)의 방향을 나타내면서 대퇴분절의 타격방향에 대한 감속을 도와주어 대퇴분절에서 하퇴분절로의 운동량전이가 효과적으로 이루어졌다. 무릎관절 신전 시 모멘트 최대값은 운동종속력 보다는 근모멘트에 좀 더 의존적인 것으로 나타났다. 그리고 숙련될수록 무릎관절 굴곡 시에는 운동종속력에 의존도가 높은 것으로 나타났다. The purpose of this study was to investigate kinetic coordination and control of lower segment according to the extent of skillfulnessof Dollyochagi motion in Taekwondo. The experiment for the data reduction was performed by collecting and analyzing the results through the kinematics and kinetics method after the 1 week, 2 weeks and 3 weeks of practice respectively. Novice subjects were 9 male middle school students who have never experienced a Taekwondo before. We examined the muscle moment and motion dependent force separately as the analytic variables and analyzed those kinetic variablesof Dollyochagi motions through video graphical analysis. The conclusions were as follows. 1. Before training, in the hip joint the motion dependent force showed the direction of positive(+) and at the end of training showed the direction of negative(-), it made the momentum transfer from the thigh segment to the shank segment effective, helping decrease in velocity of the impact direction of the thigh segment. 2. The maximal knee extension moment value was more dependent on the muscle moment than the motion dependent force moment. In the case of the flexion of the knee joint, the more skilled the subjects become, the more dependent on motion dependent force moment they become.

Effects of Moment Arms on the Internal Spinal Loads during Manual Material Handling

Murali Subramaniyam,Se Jin Park,Sangho Park 대한인간공학회 2013 대한인간공학회 학술대회논문집 Vol.2013 No.10

Objective: Effective estimates of internal spinal loading using biomechanical models are dependent on the accuracy of anatomical inputs, such as a muscle moment arm. In this study, the effects of the moment arms on the internal spinal loads were estimated during manual material handling tasks with a variety of postures. Background: Biomechanical models of the humans have been developed to predict the magnitude and pattern of spine loading during task performance. Accurate anatomical inputs for biomechanical models are necessary for valid estimates of internal spinal loading. Usually the extensor muscular and ligament forces of the lumbar spine are assumed to act 5 cm posterior (i.e., moment arm) to a disc centre of rotation. However, different moment arms (6, 7.5, and 8.5 cm) have been considered in the biomechanical studies. Method: In this study, the lumbar erector spinae moments (L4/L5 moment) during manual material handling with a variety of postures were estimated using a commercially available biomechanical model. Symmetrical hand loads considered for the tasks were 0 – 25 kg with 5 kg increments. Postures considered for the tasks were upright (0 degree) and stooped standing posture (10, 20, and 30 degrees). The muscle forces and disc compression forces about L4/L5 point were calculated from the estimated L4/L5 moment for the different moment arms. Results: When the load increases, flexor moment increases for upright posture and extensor moment decreases for the stooped standing postures. When the stooping angle increases, extensor moment increases to load. When the moment arm was higher (8.5 cm), the muscle forces were lower for the postures comparing with smaller moment arms (5, 6, and 7.5 cm). Similarly, when the moment arm was higher, the disc compression forces were also lower for the postures. Statistically significant difference (p < 0.05) was found in the muscle forces and disc compression forces between the moment arms. Conclusion: With the author’s knowledge to calculate internal spinal loads, there is no standard moment arm available and may need further studies or standard for moment arm. Application: Effective estimates of internal spinal loads would be useful for calculating recommended weights for manual lifting tasks.

무릎 관절각을 이용한 무릎 근육 길이와 모멘트 암 추정

이재강,남윤수 江原大學校 産業技術硏究所 2008 産業技術硏究 Vol.28 No.A

Recently, lots of studies are performed in developing of active orthosis. Exact and simple muscle force estimation is important in developing orthosis which assists muscle force for disabled people or physical laborers. Hill-type muscle model dynamics is common method for estimation of muscle forces, In Hill-type muscle model, we must know muscle length and moment arm which largely affect muscle force. And several methods are proposed to estimate muscle length and moment arm using joint angle. In this study, we compared estimation results of those method with data from body model of opensim to find which method is exact for estimation of muscle length and moment arm.

Identifications of Reflex Muscle Activities and Joint Moments Triggered by Electrical Stimulation to Sole of the Foot during Lokomat Treadmill Walking

Kim, Yong-Chul The Korean Society of Medical and Biological Engin 2010 의공학회지 Vol.31 No.5

The aim of this study was to investigate the characteristics of the flexion withdrawal reflex modulated during Lokomat treadmill walking in people with spinal cord injury. The influence of the limb position and movement were tested in 5 subjects with chronic spinal cord injury. EMG activities from tibialis anterior and moments of the hip joint elicited by the foot stimulation were examined during Lokomat treadmill walking. To trigger the flexion withdrawal reflex during Lokomat treadmill walking, a train of 10 stimulus pulses was applied at the skin of the medial arch. The TA EMG activity was modulated during gait phase and the largest TA reflex was obtained after heel-off and initial swing phase. During swing phase, TA EMG was 40.9% greater for the extended hip position (phase 6), compared with flexed hip position (phase 8). The measured reflex moment of the hip joint was also modulated during gait phase. In order to characterize the neural contribution of flexion reflex at the hip joint, we compared estimated moments consisted of the static and dynamic components with measured moment of the hip joint. The mean static gains of reflex hip moments for swing and stance phase are -0.1, -0.8, respectively. The mean dynamic gains of reflex hip moments are 0.25 for swing, 0.75 for stance phase. From this study, we postulate that the joint moment and muscle response of flexion withdrawal reflex have the phase-dependent modulation and linear relationship with hip angle and angular velocity for swing phase during Lokomat treadmill walking.

낙하 높이와 지면 반발계수가 착지 시 수직지면반력, 관절 각속도, 모멘트 및 근 활성도에 미치는 영향

이진석(Lee, Jin-Seok),김창균(Kim, Chang-Gyun),윤성진(Yoon, Sung-Jin) 대한운동학회 2013 아시아 운동학 학술지 Vol.15 No.2

[서론] 본 연구는 낙하 높이와 지면의 종류가 착지 시 수직지면반력, 관절 각속도, 모멘트 및 근 활성도에 미치는 영향을 규명하는 데 목적이 있다. [방법] 본 연구는 체육을 전공하는 대학생 8명이 참가하여 4주 동안 착지 연습을 실시하였으며, 본 실험 시, 연구대상자는 30 cm와 60 cm 높이에서 각각 세 가지 지면으로 무작위로 착지하였다. 수직지면반력과 관절 각 속도, 모멘트 및 근 활성도는 3차원 동작분석, 지면반력분석, 근활성도 분석을 통하여 측정하였다. 모든 자료는 이원변량 반복측정 분산분석을 이용하여 분석하였으며, 유의 차이에 대한 사후 검증은 Bonferroni’s method로 실시하였고 유의수준은 .05였다. [결과] 60 cm 높이에서 최대 수직지면반력 1정점과 2정점은 각각 지면 반발계수가 높은 순서로 높게 나타났다. 60 cm 높이에서 발목관절 평균 각속도는 30 cm 높이와 비교하여 모든 지면이 유의하게 크게 나타났다. 60 cm 높이에서 발목과 무릎관절의 모멘트는 각각 30 cm 높이보다 모든 지면이 유의하게 크게 나타났으며, 60 cm 높이에서 무릎관절 최대 신전 모멘트는 지면반발계수가 높은 순서에 따라 크게 나타났다. 60 cm 높이에서 대퇴직근, 내측 비복근, 외측 비복근의 근 활성도는 마루가 천연잔디, 매트보다 유의하게 높았으며, 60 cm 높이와 30 cm 높이에서 전경골근의 근 활성도는 각각 마루, 천연잔디가 매트보다 유의하게 높았다. 또한, 60 cm 높이에서 대퇴직근, 대퇴이두근, 내측 비복근, 외측 비복근, 전경골근의 근 활성도는 30 cm 높이와 비교하여 모든 지면이 낙하 높이에 따라 유의하게 높았다. [결론] 60 cm 이상의 낙하 높이에서 착지 시 지면의 반발계수가 높을수록 신체에 작용하는 부하에 영향을 미친다는 것을 알 수 있지만, 낙하 높이가 낮으면 신체에 작용하는 부하에 지면의 반발계수의 차이가 영향을 미치지 않음을 알 수 있다. 따라서 초기 재활 훈련 프로그램에서 박스를 이용한 훈련 또는 비시즌기의 훈련 시 60 cm보다 30 cm 높이가 안전할 것으로 생각되며, 60 cm 높이에서 훈련 시에는 지면 반발계수가 상대적으로 낮은 지면인 태권도매트에서 훈련하는 것이 상해의 위험에 노출될 가능성을 보다 낮출 수 있을 것으로 생각된다. [INTRODUCTION] The purpose of this study was to investigate the effects of different surface coefficient of restitution(SCR) and drop height on ground reaction force, joint angular velocity, moment and muscle activity during drop landing. [METHOD] Eight university students majoring in physical education were performed to landing exercises for four weeks. The participants performed 30 cm and 60 cm height drop landing on three different surface with randomized control and cross-over design. Thee-dimensional motion analysis, surface EMG and force plates were used to measure ground reaction force, joint angular velocity and muscle activity of lower limb. The datas were statically analyzed by two-way ANOVA with repeated measures and Bonferroni’s post-hoc test. All significance level for the analysis was set at .05. [RESULTS] At 60 cm drop height, the maximum vertical ground reaction force was high with surface coefficient of restitution. The average of ankle joint angular velocity was the result from 60 cm drop height was higher than that from 30 cm on every field. In landing from 60 cm height, the maximum extensor muscle moment of the knee joint appeared on floor, natural grass and mat according to ground reaction force. Also the maximum extensor muscle moments of the ankle and knee joint was that the result from 60 cm drop height was higher than that from 30 cm on every field. In landing from 60 cm drop height, muscle activity of rectus femoris, medial gastrocnemius and lateral gastrocnemius had different results which showed that one on floor had higher activity than one on natural grass and a mat depending on surface coefficient of restitution. In landing from 60 cm and 30 cm drop height, muscle activity of tibialis anterior on mat had lower result than that on the floor and natural grass according to surface coefficient of restitution. Also muscle activities of rectus femoris, medial gastrocnemius and lateral gastrocnemius on every ground had higher results when the drop height was 60 cm than it was 30 cm. [CONCLUSION] On this study we leaned that surface of the coefficient of restitution is higher affects loading on body during landing in height of some level, but a low drop height does not affect loading on body with the SCR. Therefore, our study suggest that In landing from 30 cm drop heigh, the initial rehabilitation program based on the box or training during off season can provide a safe drop.

EMG센서를 이용한 실시간 무릎 관절 모멘트 측정 모델 개발

김성남(Seongnam Kim),남윤수(Yoonsu Nam) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5

This paper introduces a real- time calculation model to estimate knee joint moment using EMG sensor. It is possible to estimate knee joint moment combining Hill-type muscle model, analytic results on moment arm, musculotendon length and muscle activation. Muscle activation could be measured by signal processing and activation dynamics.

한발서기 동안 동측, 반대측 방향의 상지부하가 다리근육의 근활성도에 미치는 영향

허재석,이상열 대한물리치료과학회 2020 대한물리치료과학회지 Vol.27 No.1

Background: The purpose of this study was to investigate the effects of ipsilateral and contralateral load changes during single-leg standing on the leg muscle activities of healthy people. Design: Randomized controlled trial. Methods: For all the subjects, a load was randomly applied to the ipsilateral or the contralateral side. While the load was applied, the subject raised a hand and then performed single-leg standing for 10 seconds using the dominant side. Results: During single-leg standing, the muscle activity of the gluteus medius, peroneus longus on the supporting side increased statistically significantly when an upper limb load was applied contralaterally, but no statistically significant differences were detected in the muscle activities of the tibialis anterior and the gastrocnemius using a test of within-subjects effects. Conclusion: It can be seen that muscle activities increase during exercise when the amount and frequency of a load are increased and when the same load is applied to different sides of the body. Such muscle activity increases may be applied to change the intensity of exercise when one is in a static posture, such as during single-leg standing.