• 한국정밀공학회지
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• 제26권2호
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• pp.126-132
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• 2009

This study examined the differences in spatio-temporal parameters, joint angle, ground reaction force (GRF), and joint power according to the changes of gait speed for trans-tibial amputees to investigate the features of the energy-storing foot for sports. The subjects walked at normal speed and at fast speed, wearing a single-axis type foot (Korec) and an energy-storing foot for sports (Renegade) respectively. The results showed that Renegade yielded faster gait speed as well as more symmetric gait pattern, compared to Korec. However, as gait speed was increased, there was no significant difference in kinematics, ground reaction force, and joint power between two artificial foots. This was similar to the results from previous studies regarding the energy-storing foot, where the walking velocity and gait symmetry have been improved. Nevertheless, the result of this study differed from the previous ones which reported that joint angle, joint power, and GRF increased as the gait speed increased except spatio-temporal parameters.

• 대한기계학회논문집A
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• 제38권7호
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• pp.779-784
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• 2014

본 연구에서는 볼 조인트 구조에서 가장자리 하중을 받고 있을 때의 마찰 소음을 이론적으로 연구하였다. 구형 베어링 구조체와 반구 형태의 소켓간 마찰접촉 모델을 수학적으로 유도하여 동역학적 운동방정식을 전개하였다. 그 결과 볼 조인트부 굽힘 모드가 마찰에 의해 불안정할 수 있음을 보였고, 축력 및 접촉강성이 볼 조인트 동적 불안정성에 크게 영향을 주고 있음을 보였다. 반면 소켓의 틸팅 각도는 동적 불안정성에 크게 기여하지 않음을 보였다.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.183-190
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• 2008

This paper deals with the characteristics of idle vibration due to the type of constant velocity joints. Based on the kinematics model of constant velocity joints, a offset between the tripod center and tullip center plays a important role in generating unwelcome forces. Moreover, it induced additional forces in lateral direction of a vehicle movement according to the angle of the spider in idle vibration. The difference of mass for each constant velocity joint types affect the natural frequency of the driveshaft and the powertrain. When the static torque is applied to the constant velocity joints, the natural frequencies of the driveshaft are reduced nearby 50Hz. There will be a big opportunity that the dirveshaft and constant velocity joints would be a transfer path of idle vibration at D or R gear range. Experiments indicate that TJ type is better than SFJ and DOJ in idle vibration.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1995년도 춘계공동학술대회논문집; 전남대학교; 28-29 Apr. 1995
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• pp.629-634
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• 1995

The purpose of this paper is to develop a method of Collision-Free Path Planning (CFPP) for an articulated robot. First, the configuration of the robot is formed by a set of robot joint angles derived fromm robot inverse kinematics. The joint space that is made of the joint angle set, forms a Configuration space (Cspace). Obstacles in the robot workcell are also transformed and mapped into the Cspace, which makes Cobstacles in the Cspace. (The Cobstacles represented in the Cspace is actually the configurations of the robot causing collision.) Secondly, a connected graph, a kind of roadmap, is constructed from the free configurations in the 3 dimensional Cspace, where the configurations are randomly sampled form the free Cspace. Thirdly, robot paths are optimally in order to minimize of the sum of joint angle movements. A path searching algorithm based on A is employed in determining the paths. Finally, the whole procedures for the CFPP method are illustrated with a 3 axis articulated robot. The main characteristics of the method are; 1) it deals with CFPP for an articulated robot in a 3-dimensional workcell, 2) it guarantees finding a collision free path, if such a path exists, 3) it provides distance optimization in terms of joint angle movements. The whole procedures are implemented by C on an IBM compatible 486 PC. GL (Graphic Library) on an IRIS CAD workstation is utilized to produce fine graphic outputs.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.882-887
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• 2003

This paper presented a design and control of a new RGO(reciprocating gait orthosis)and its simulation. The new RGO was distinguished from the other one by which had a very light-weight and a new RGO(reciprocating gait orthosis) system. The vibration evaluation of the hip joint system on the new RGO(reciprocating gait orthosis)was used to access by the 3-axis accelerometer with a low frequency vibration of less than 30 ㎐. The gait of the new RGO depended on the constrains of mechanical kinematics and the initial posture. The stability of dynamic walking was investigated by analyzing the ZMP (zero moment point) of the new RGO. It was designed according to the human wear type and was able to accomodate itself to the environments of S.C.I. Patients. The joints of each leg were adopted with a good kinematic characteristics. To analyse joint kinematic properties, we made the hip joint system of FEM and the hip joint system by 1-axis and 3-axis Accelerometers.

• The Journal of Korean Physical Therapy
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• 제28권1호
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• pp.14-21
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• 2016

Purpose: The purpose of this study was to investigate examine how the kinematics and kinetics of lower limb joints were changed depending on the unstable shoes (US) during sit-to-stand task (SitTS). Methods: Nineteen healthy females were participated in this study. The subjects performed sit-to-stand task with US and barefoot. The experiment was repeated three times for each tasks with conditions. The kinematics and kinetics of lower limb joint were measured and analyzed using a 3-D motion analysis system. A paired t-test was utilised performed for to identificationy of changes in mean of angle, force, and moment between both the two conditions. Results: The results of this study showed kinematic differences in lower limb joints during SitTS based on the US. The hip, knee, and ankle angle showed statistically significant differences during SitTS. At the initial of SitTS, Tthe force and moment of the hip flexor, hip extensor, knee flexor, knee extensor, ankle flexor, and ankle extensor showed statistically significant differences. At the terminal of SitTS, Tthe force and moment of the hip flexor, hip extensor, knee flexor, knee extensor, ankle flexor, and ankle extensor showed statistically significant differences. At the maximum of SitTS, Tthe moment of the hip extensor showed statistically significant differences. The force and moment of the ankle flexor, extensor moment showed statistically significant differences. Conclusion: Therefore, Wwearing US is considered to influence on the lower limb joints kinematics and kinetics during SitTS movements, and thus suggests the possibility that of reducing the risks of pain, and osteoarthritis caused by changes in the loading of lower limb joints.

• 한국운동역학회지
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• 제31권3호
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• pp.205-213
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• 2021

Objective: The aim of this study was to analyze body stability Joint coordination pattern though as bending stiffness of shoes during stance phase of running. Method: 47 male subjects (Age: 26.33 ± 2.11 years, Height: 177.32 ± 4.31 cm, Weight: 65.8 ± 3.87 kg) participated in this study. All subjects tested wearing the same type of running shoes by classifying bending stiffness (A shoes: 3.2~4.1 N, B shoes: 9.25~10.53 N, C shoes: 20.22~21.59 N). They ran 10 m at 3.3 m/s (SD ±3%) speed, and the speed was monitored by installing a speedometer at 3 m intervals between force plate, and the measured data were analyzed five times. During running, ankle joint, MTP joint, coupling angle, inclination angle (anterior-posterior, medial-lateral) was collected and analyzed. Vector coding methods were used to calculate vector angle of 2 joint couples during running: MTP-Ankle joint frontal plane. All analyses were performed with SPSS 21.0 and for repeated measured ANOVA and Post-hoc was Bonferroni. Results: Results indicated that there was an interaction between three shoes and phases for MTP (Metatarsalphalangeal) joint angle (p = .045), the phases in the three shoes showed difference with heel strike~impact peak (p1) (p = .000), impact peak~active peak (p2) (p = .002), from active peak to half the distance to take-off until take-off (p4) (p = .032) except for active peak~from active peak to half the distance to take-off (p3) (p = .155). ML IA (medial-lateral inclination angle) for C shoes was increased than other shoes. The coupling angle of ankle angle and MTP joint showed that there was significantly difference of p2 (p = .005), p4 (p = .045), and the characteristics of C shoes were that single-joint pattern (ankle-phase, MTP-phase) was shown in each phase. Conclusion: In conclusion, by wearing high bending stiffness shoes, their body instability was increased during running.

• Clinics in Shoulder and Elbow
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• 제13권1호
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• pp.141-145
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• 2010

목적: 주관절의 생역학은 주관절 손상의 병인을 이해하고 임상적 치료의 과학적 기초를 제공하는 의학이다. 저자는 생역학적인 관점에서 주관절 손상의 진단과 치료의 개념을 요약하였다. 대상 및 방법: 주관절 역학은 크게 운동학, 동역학 그리고 이를 바탕으로 한 안정성의 분야로 나누어 설명할 수 있다. 이는 주관절을 구성하는 수동적 또는 능동적 구조물로 유지된다. 수동적 구조물은 골성 구조와 관절낭 및 측부인대들이 있으며 능동적 구조물은 주관절을 둘러싼 근육들이 해당된다. 이 구조물들이 유기적으로 작용하여 주관절의 안정성, 힘의 전달 그리고 운동을 유지한다. 결과 및 결론: 주관절의 생역학은 주관절 손상에 대한 수술적 치료에 대한 정보를 제공하며 새로운 주관절 인공대치물에 대한 개선 및 발전을 가져다 주며, 또한 주관절의 기초 연구에 기여 할 수 있는 학문이다.

• 대한인간공학회지
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• 제15권2호
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• pp.15-24
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• 1996

To generate workspace analytically using the robot kinematics, data on range of human joints motion, especially range of two degrees of freedom motion, are needed. However, these data have not been investigated up to now. Therefore, in this research, we are to investigate an interaction effect of motions with two degrees of freedom occurred simultaneously at the shoulder, virtual hip(L5/S1) and hip joints, respectively, for 47 young male students. When motion with two degrees of freedom occurred at a joint such as shoulder, virtual hip and hip joints, it was found from the results of ANOVA that the action of a degree of freedom motion may either decrease or increase the effective functioning of the other degree of freedom motion. In other words, the shoulder flexion was decreased as the shoulder was adducted or abducted to $60^{\circ}C$TEX>or abducted from $60^{\circ}C$TEX>to maximum degree of abduction, while the shoulder flexion increased as the joint was abducted from $60^{\circ}C$TEX> to $60^{\circ}C$TEX> The flexion was decreased as the virtual hip was bent laterally at the virtual hip joint, and also did as the hip was adducted or abducted from the neutral position. It is expected that workspace can be generated more precisely based the data on the range of two degrees of joint motion measured in this study.

• 로봇학회논문지
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• 제13권2호
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• pp.129-141
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• 2018

This paper proposes a unified framework that overcomes four motion constraints including joint limit, kinematic singularity, algorithmic singularity and obstacles. The proposed framework is based on our previous works which can insert or remove tasks continuously using activation parameters and be applied to avoid joint limit and singularity. Additionally, we develop a method for avoiding obstacles and combine it into the framework to consider four motion constraints simultaneously. The performance of the proposed framework was demonstrated by simulation tests with considering four motion constraints. Results of the simulations verified the framework's effectiveness near joint limit, kinematic singularity, algorithmic singularity and obstacles. We also analyzed sensitivity of our algorithm near singularity when using closed loop inverse kinematics depending on magnitude of gain matrix.