• 센서학회지
• /
• 제27권2호
• /
• pp.105-111
• /
• 2018

In this paper, a torque sensor is designed and fabricated to measure the knee joint torque of a walking assist robot for stroke patients. The torque sensor sensing part was modeled on the link of the part connected to the knee joint motor. The torque capacity of the knee joint was calculated by simulation and the size of the torque sensor sensing part was designed using the finite element method. The torque sensor was fabricated by attaching a strain gauge to the sensing part. Characteristic experiments were conducted to characterize the torque sensor, and the torque sensor was calibrated to utilize it for the control of the walking assist robot. As a result of the characteristics test, the reproducibility error and the nonlinearity error of the torque sensor were 0.03% and 0.04%, respectively. Therefore, it is considered that the developed torque sensor can be used to measure the torque applied to the knee joint when walking on a walking assist robot.

• 한국운동역학회지
• /
• 제25권3호
• /
• pp.275-281
• /
• 2015

Objective : In order for Taekwondo athletes to perform destructive kicking performance, they are expected to have Taekwondo-specific muscle properties such as high muscle strength and power. The purpose of this study was to investigate the joint angle-dependent force-producing property of Taekwondo athletes' knee extensor muscles, which is one of the primary muscle groups involved in kicking performance. Method : Ten Taekwondo male athletes (age: $19.9{\pm}0.7yrs$, height: $180.6{\pm}6.2cm$, body mass: $75.9{\pm}8.9kg$, career: $9.2{\pm}2.9yrs$.) and 10 healthy male non-athletes (age: $26.3{\pm}2.6yrs$, height: $174.2{\pm}4.8cm$, body mass: $72.8{\pm}7.7kg$) participated in this study. Subjects performed maximum isometric knee extension at knee joint angles of $40^{\circ}$, $60^{\circ}$, $80^{\circ}$, and $100^{\circ}$ (the full knee extension was set to $0^{\circ}$) with the hip joint angles of $0^{\circ}$ and $80^{\circ}$ (the full extension was set to $0^{\circ}$). During the contractions, knee extension torque using an isokinetic dynamometer simultaneously with muscle activities of the rectus femoris (RF), and the vastus lateralis (VL) and vastus medialis (VM) using surface electromyography were recorded. Based on the torque values at systematically different knee-hip joint angles, the joint torque-angle relationships were established and then the optimal joint angle for the knee extensor was estimated. Results : The results of this study showed that the isometric knee extension torque values were greater for the Taekwondo athletes compared with the non-athlete group at all hip-knee joint angle combinations (p<.05). When the hip joint was set at $80^{\circ}$, the peak isometric torque was greater for the Taekwondo athletes compared with the non-athlete group ($313.61{\pm}36.79Nm$ and $221.43{\pm}35.92Nm$, respectively; p<.05) but the estimated optimum knee joint angles were similar ($62.33{\pm}5.71^{\circ}$ and $62.30{\pm}4.67^{\circ}$ for the Taekwondo athletes and non-athlete group, respectively). When the hip joint was set at $0^{\circ}$, the peak isometric torque was greater for the Taekwondo athletes compared with the non-athlete group ($296.29{\pm}45.13Nm$ and $199.58{\pm}25.23Nm$, respectively; p<.05) and the estimated optimum knee joint angle was larger for the Taekwondo athletes compared with the non-athlete group ($78.47{\pm}5.14^{\circ}$ and $67.54{\pm}5.77^{\circ}$, respectively; p<.05). Conclusion : The results of this study suggests that, compared with non-athletes, Taekwondo athletes have stronger knee extensor strength at all hip-knee joint angle combinations as well as longer optimum muscle length, which might be optimized for the event-specific required performance through prolonged training period.

• 한국정밀공학회지
• /
• 제24권8호통권197호
• /
• pp.130-137
• /
• 2007

The optimized prosthetic mass distribution was a controversial problem in the previous studies because they are not supported by empirical evidence. The purpose of the present study was to evaluate the effect of prosthetic mass properties by modeling musculoskeletal system, based on the gait analysis data from two above-knee amputees. The joint torque at hip joint was calculated using inverse dynamic analysis as the mass was changed in knee and foot prosthetic components with the same joint kinematics. The results showed that the peak flexion and abduction torque at the hip joint were 5 Nm and 15 Nm when the mass of the knee component was increased, greater than the peak flexion and abduction torque of the control group at the hip joint, respectively. On the other hand, when the mass of the foot component was increased, the peak flexion and abduction torque at the hip joint were 20 Nm and 15 Nm, greater than the peak flexion and abduction torque of the control, respectively. The hip flexion torque was 4.71-fold greater and 7.92-fold greater than the hip abduction torque for the knee mass increase and the foot mass increase on the average, respectively. Therefore, we could conclude that the effect of foot mass increase was more sensitive than that of knee mass increase for the hip flexion torque. On the contrary, the mass properties of the knee and foot components were not sensitive for the hip abduction torque. In addition, optimized prosthetic mass and appropriate mass distributions were needed to promote efficiency of rehabilitation therapy with consideration of musculoskeletal systems of amputees.

• 대한통합의학회지
• /
• 제1권2호
• /
• pp.47-57
• /
• 2013

Purpose : The purpose of this study was to compare the Effects of Knee Extensor, Flexor Muscle Strength and Joint Position Sense in Squat Exercise on Variety Surface. Method : Subjuects were consisit of 30 male and female who had non disorder knee joint. we had devided 3 group(control group, balance pad group, and togu group) and we measured that knee joint $15^{\circ}/45^{\circ}$proprioception(position sense) and Peak Torque of knee extensor, flexor muslce at $60^{\circ}/sec$, $180^{\circ}/sec$ angular velocity. Result : First, knee joint $15^{\circ}$proprioception(position sense) of balance pad and togu group was significantly different after exercise(p<.05), but only balance pad group was significantly different at knee joint $45^{\circ}$. Second, knee extensor Peak Torque of balance pad and togu group was significantly different at $60^{\circ}/sec$, $180^{\circ}/sec$ angular velocity(p<.05). Third, knee flexor Peak Torque of balance pad and togu group was significantly different at $60^{\circ}/sec$, $180^{\circ}/sec$ angular velocity(p<.05). Conclusion : Squat exercises on the balance pad and togu were affects knee joint proprioception and muscle strength improvement. These results suggest that squat exercise on the unstable surface is effective for prevention of knee joint injury and functional activity.

• 한국전문물리치료학회지
• /
• 제14권3호
• /
• pp.23-31
• /
• 2007

The purpose of this study was to determine the influence of high-heeled shoes on walking of obese women as it was already proven an extrinsic factor of knee osteoarthritis in women with normal weight. In this study the aimed therefore in particular was to utilize high-heeled shoes in proving it's causal influence on knee osteoarthritis by measuring the angle and torque of the knee joint. Fifteen obese women (BMI>25 $kg/m^2$) were measured in their twenties. Each angle and torque of their knee joints during walking on 6.5 cm high-heeled shoes and with a bare feet, were compared with each other and analyzed with a 3D motion analysis system. There was no significant difference in walking speed, cadence and stride length between the two conditions. However, there was a significant increase in a double limb support time and the stance phase when walking on high-heeled shoes as when walking with bare feet. The peak knee flexion angle and peak knee varus torque was higher when walking on high-heeled shoes than with bare feet. On the contrary, the peak knee flexion angle in the swing phase was not statistically different. The prolongation of peak knee varus torque was also proven. There was a significant increase in peak knee varus torque in the initial and last stance phases during walking on high-heeled shoes as compared to walking on bare feet. Through the above results, it was proven that when obese women walked on high-heeled shoes, rather than with bare feet, peak knee flexor and varus torque increased along with the changes of the in knee joint angle. Therefore, the influence of high-heeled shoes might be a significant intrinsic factor in knee osteoarthritis of obese women.

• 한국운동역학회지
• /
• 제27권2호
• /
• pp.83-90
• /
• 2017

Objective: To investigate the effect of short-term vibration frequencies on muscle force generation capabilities. Method: Six healthy participants were recruited for this study and only their dominant leg was tested. The subjects were tested under five conditions of vibration frequencies with constant amplitude: 0 Hz (no vibration), 30 Hz, 60 Hz, and 90 Hz, and the vibration amplitude was 10 mm for all frequency conditions. The vibration was applied to the rectus femoris (RF). The subjects were then instructed to maintain a steady-state isometric knee joint torque (100 Nm) for the first 6 s. After the steady-state torque production, the subjects were required to produce isometric knee joint torque by leg extension as hard as possible with a start signal within the next 3 s. The vibration was applied for ~4 s starting from 1 s before initiation of the change in the steady-state knee joint torque. Results: The results showed that the maximum voluntary torque (MVT) of the knee joint increased with the vibration frequencies. On average, the MVTs were 756.47 Nm for 0 Hz (no vibration) and 809.61 Nm for 90 Hz. There was a significant positive correlation (r = 0.71) between the MVTs and integrated electromyograms (iEMGs). Further, the co-contraction indices (CCIs) were computed, which represent the ratio of the iEMGs of the antagonist muscle to the iEMGs of all involved muscles. There was a significant negative correlation (r = 0.62) between the CCIs and MVTs, which was accompanied by a significant positive correlation (r = 0.69) between the iEMGs of the vibrated muscle (RF). There was no significant correlation between the MVTs and iEMGs of the antagonist muscle. Conclusion: The results of this study suggest that the short-term vibration on the muscle increases the level of muscle activation possibly owing to the increased Ia afferent activities, which enhances the muscle force generation capability.

• 한국운동역학회지
• /
• 제16권4호
• /
• pp.73-81
• /
• 2006

The purpose of this study was to investigate the effects of strength training on knee joint torque during walking in an adolescent with trisomy-21 Down syndrome. One adolescent with Down syndrome and one normal child participated in this study. Strength training consisted of eight exercises: squat, hamstring curl, hip adduction, hip abduction, knee extension, toe raise, sit-ups, and hyperextension of the waist. The participant with Down syndrome was participated in strength training for 12 weeks, three times a week, three sets, 10-15 RM; resistance was adjusted according to the principle of progressive overload. To measure the effect of strength training, isokinetic strength variables and knee joint torques were measured before training and after 12 weeks of training. The participant with Down syndrome had some abnormalities in controlling knee motion during walking due to muscle hypotonia, ligament laxity, and weakness of muscles. Post-training isokinetic strength increased compared to pre-training measurements. Knee range of motion were increased after strength training. Strength training did not affect ad/adduction and in/exteranl moments but did have an effect on flexor/extensor moment and timing.

• 대한의용생체공학회:의공학회지
• /
• 제25권4호
• /
• pp.289-293
• /
• 2004

본 연구에서는 경사각도가 다른 내, 외측 후족 왯지를 착용하고 보행하는 동안 삼차원 동작분석시스템과 무선가속도측정시스템을 이용하여 무릎관절의 내번토크와 내외측 방향 가속도를 측정하였다. 내번토크와 외측 가속도는 하중수용기와 전유각기에서 각각 양의 절정값을 나타내었다. 하중수용기에 내측 왯지의 경우 내번토크와 외측 가속도가 맨발에 비하여 증가되었으며, 외측 왯지의 경우 내번토크와 외측 가속도값이 감소하였다. (p<0.05). 이러한 변화는 왯지의 경사각이 커질수록 더욱 뚜렷한 상관성을 보였다(p<0.05). 그러나 전유각기에서는 왯지의 방향과 경사에 따른 무릎의 내번토크와 내외측 가속도의 상관성을 확인할 수 없었다. 본 연구의 견과를 통하여 외측 왯지 사용 시 무릎관절의 내번토크가 감소되어 퇴행성 무릎관절염의 치료에 도움을 줄 수 있다. 또한, 보행 중 무릎관절의 내번토크 대신에 외측방향 가속도를 측정함으로써 간단히 왯지의 효과를 결정할 수 있을 것이다.

• 제어로봇시스템학회논문지
• /
• 제16권10호
• /
• pp.948-956
• /
• 2010

The purpose of this study was to test the effectiveness of a prototype KAFO (Knee-Ankle-Foot Orthosis) powered by two artificial pneumatic muscles during walking. We had previously built powered AFO (Ankle-Foot Orthosis) and KO (Knee Orthosis) and used it effectively in studies on assistance of plantaflexion and knee extension motion. Extending the previous study to a KAFO presented additional challenges related to the assistance of gait motion for rehabilitation training. Five healthy males were performed gait motion on treadmill wearing KAFO equipped with artificial pneumatic muscles to power ankle plantaflexion and knee extension. Subjects walked on treadmill at 1.5 km/h under four conditions without extensive practice: 1) without wearing KAFO, 2) wearing KAFO with artificial muscles turned off, 3) wearing KAFO powered only in plantaflexion under feedforward control, and 4) wearing KAFO powered both in plantaflexion and knee extension under feedforward control. We collected surface electromyography, foot pressure and kinematics of ankle and knee joint. The experimental result showed that a muscular strength of wearing KAFO powered plnatarfexion and knee extension under feedforward control was measured to be lower due to pneumatic assistance and foot pressure of wearing KAFO powered plnatarfexion and knee extension under feedforward control was measured to be greater due to power assistance. In the result of motion analysis, the ankle angle of powered KAFO in terminal stance phase was found a peak value toward plantaflexion and there were difference of maximum knee flexion range among condition 2, 3 and 4 in mid-swing phase. The current orthosis design provided plantaflexion torque of ankle jonit in terminal stance phase and knee extension torque of knee joint in mid-swing phase.

• Physical Therapy Rehabilitation Science
• /
• 제13권2호
• /
• pp.223-230
• /
• 2024

Objective: In this study, we compared the key indices of isokinetic tests for knee joint extension and flexion according to the presence or absence of pain in elite athletes with past knee and thigh injuries. Design: Crossed-sectional study Methods: This study was conducted on 33 elite athletes. The elite athletes who participated in this study were divided into a group with pain and a group without pain due to past knee and thigh injuries. The subjects in each group performed an isokinetic muscle strength test for knee joint extension and flexion. After the isokinetic muscle strength test, the main indices of the isokinetic test were compared between the pain group and the non-pain group. Results: In the comparison of the pain group and the non-pain group for 60°/s knee flexion and extension in elite athletes, there was a significant difference only in the torque max average/kg for knee extension. However, there was no statistically significant difference in all other variables. The comparison of the pain group and the non-pain group for 240°/s also showed a significant difference in the torque max average/kg for knee extension, and there was no statistically significant difference in all other variables. Conclusions: In subjects who have experienced previous knee or thigh injuries and have mild pain during strong isokinetic strength tests, torque average/kg is affected, but other strength variables are not affected. Therefore, it would be good to consider this aspect and use it as a basis for testing and training elite athletes.