• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.131-136
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• 1988

In this paper we describe a motion control algorithm for a 4-legged robot over slopped terrain and steps. The new concept of the mechanically constrained angle has been introduced and the algorithm has been developed based on the relationship between the gait stability margin and the slope angle. The result then has been extended to the case where the robot walks over steps.

• 로봇학회논문지
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• 제18권2호
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• pp.172-181
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• 2023

This paper presents research on the stability of control for a quadruped robot with two different leg structure designs. The focus of the research is on the design and analysis of the leg structures in terms of their impact on the stability and robustness of the robot's motion. First, a static analysis was performed in the simulation to compare the structural strength of the legs when the same force was applied. Secondly, two quadruped robots were built, each equipped with differently designed legs, and performed trot gait walking in the real world. And the states of the robots and the torques of each joint were analyzed and compared. In conclusion, based on the results of structural analysis in simulation and the actual walking experiments with the robots, it was demonstrated that the legs designed to be structurally robust improved the control stability of the quadruped robot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2438-2440
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• 2004

This study is concerned with development of 3-Dimensional simulator of a biped robot that has a prismatic balancing weight or a revolute balancing weight. The dynamic stability equation of a biped robot which have a prismatic balancing weight is conditional linear but a walking robot's stability equation with a revolute balancing weight is nonlinear. To get a stable gait of a biped robot, stabilization equations with ZMP (Zero Moment Point) are modeled as non-homogeneous second order differential equations for each balancing weight type. A trajectory of balancing weight can be directly calculated with the FDM (Finite Difference Method) solution of the linearized differential equation. In this paper, the 3-Dimensional graphic simulator is programmed to get and calculate the desired ZMP and the actual ZMP. Walking of 4 steps was simulated and verified. This balancing system will be applied to a biped humanoid robot, which consist Begs and upper body, at future work.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.523-528
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• 2000

In this paper, the new type biped walking robot which is composed of the minimum number or links just for walking and its appropriate gaits are proposed. The proposed new gaits for this robot are four-crossing, crawling, standing and turning gait. In designing the biped robot we propose the Performance Index which means the needed torque per a moving distance and generate foot trajectories by $3^{rd}$ order spline Interpolation. Among those, numerically we find the optimal conditions which minimize the Performance Index. Dynamically stable walking of the biped robot is realized by satisfying the stability condition of ZMP(zero moment point), which is related to maintaining the ZMP within the region of the supporting foot during the s1n91e leg support phase. We determine the region of mass center from the stability condition of ZMP and plan references which track the mass conte. trajectory of constant velocity. Finally we implement the gaits statically tracking the planned trajectories using PD control method.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1011-1015
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• 2005

Fully digital controlled 20-bit magnet power supplies have been developed and successfully tested for closed orbit correction of PLS(Pohang Light Source). The new digital power supply has used fiber optics for 25kHz switching of IGBT drivers, and implemented DSP, ADC, Interlock, DCCT cards in a compact 3U-sized 19" chassis. Input/Output low-pass filters suppress harmonics of 60Hz line frequency and switching frequency noise effectively. Overall performance of the power supplies have been demonstrated as +/- 2ppm short-term stability(<1 min), and +/- 10ppm long-term stability(<36 hours). All the existing 12-bit 70 power supplies for vertical correction magnets will be replaced with new digital power supplies during 2005 summer shutdown period. In this paper, we will describe the hardware structure and control method of the digital power supply and the experimental results will be shown.

• 한국운동역학회지
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• 제19권2호
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• pp.205-215
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• 2009

계단 하강보행에서의 임산부 낙상은 임산부와 태아에게 치명적인 영향을 미친다. 이 연구는 임신기간 중 계단의 단 너비 변화에 따른 임산부 양발 보행의 생체역학적 변화를 구명하는 것이다. 이 실험을 위하여 건강한 임산부 9명이 참가하였고 Qualisys사의 Proreflex MCU-240 카메라 7대와 Kistler사의 Type 9286AA 지면반력기 2대를 설치하여 상호 동조하여 실험하였으며 연구변인은 Visual 3D(C-motion Inc., USA)를 사용하여 인체를 모델링 한 후 산출하였다. 임신기간이 경과됨에 분당 활보장수는 감소한 반면 활보장 주기는 증가하였으며 양발의 슬관절 모멘트 차이가 작아졌다. 그리고 단너비가 넓어질수록 속력과 활보장 길이가 증가하였다. 단너비에 따른 하지 관절모멘트는 각 관절마다 고유한 패턴을 보였으며 고관절 모멘트는 주로 양발의 비대칭성 패턴을 보였고 슬관절 및 족관절은 대칭적인 패턴을 보였다. 그리고 임신기간이 경과됨에 따라 좌 우측의 최대 최소 슬관절 모멘트의 차이가 작아졌다. 이러한 결과들은 임산부가 신체변화에 적응하면서 안전성의 최대화를 위하여 자신의 고유한 보행패턴을 생성하는 자기적응화 과정을 지속적으로 유지하면서 변화한다고 할 수 있다.

• 한국운동역학회지
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• 제20권3호
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• pp.267-275
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• 2010

The purpose of this study was to investigate the effects of balance ability improvement exercise program which applied to the elderly people for increasing balance, stability and range of motion. Ten elderly people and ten university students were recruited as the subjects. Kinematic data were collected by seven real-time infrared cameras while subjects walk stair descent as a pre-test. Korean folk dance exercise program was applied to the elderly for 12 weeks. Same experiment on stair descent walk was performed as post-test. Results indicated that CM movement and selected joint angle patterns of elderly group after treatment changed to the similar patterns of young group. However, ankle joint angle and vertical GRF of elderly group after treatment also increased compared to those of the elderly group before treatment. This might be explained by the fact that elderly used a different walking strategy which maximize support base for increasing stability. Overall, these results indicated that the exercise treatment may affect to adapt and improve the gait pattern of stair descent of elderly people.

• 한국지능시스템학회논문지
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• 제19권4호
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• pp.457-463
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• 2009

본 논문에서는 육족 보행 로봇의 새로운 힘 분배 알고리듬을 제안한다. 본 논문에서 고려하는 육족 보행 로봇은 다리 하나에 관절고착고장이 발생하여 내고장성 정적 세다리 걸음새로 보행한다. 제안되는 힘 분배 알고리듬의 핵심은 내고장성 걸음새가 가지는 안정여유도를 결정하는 지지 다리의 미끄러짐을 최소화시키는 것이다. 불연속적으로 움직이는 내고장성 세다리 걸음새는 정상 걸음새보다 안정도가 떨어진다는 약점이 있다. 본 논문에서 제안하는 힘 분배 알고리듬은 이러한 약점을 고려하여 내고장성 걸음새의 지지 다리가 세 개라는 성질과 Zero-Interaction Force 원리를 이용하여 최적화 기법을 쓰지 않고 대수적으로 모든 다리의 힘 성분을 구한다. 컴퓨터 시뮬레이션 사례 연구를 통해서 제안된 힘 분배 알고리듬과 기존 방법의 비교 분석을 실시하고 제안된 방법의 효용성을 입증한다.

• PNF and Movement
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• 제17권1호
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• pp.31-39
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• 2019

Purpose: Cognitive function is a main concern for rehabilitation progression in individuals who have sustained brain damage, even among those whose motor function has returned after brain damage. The purpose of this study was to investigate how cognitive impairment relates to functional independence in postural stability and gait performance in patients with chronic hemiparetic stroke. Methods: This was an observational design in an outpatient rehabilitation hospital. Twenty-eight adults with chronic hemiparetic stroke, receiving a course in an outpatient rehabilitation program, participated in this study. They were divided into two groups (i.e., non-cognitive impairment and cognitive impairment groups) via a cut-off score of 23 or less on a mini-mental state examination. Functional independence was assessed with the timed up-and-go test (TUG), 10-meter walk test (10mWT), five times sit-to-stand test (FTSST), Berg balance scale (BBS), and modified Barthel index (MBI). The independent t-test was used for statistical analysis when comparing the two groups. Results: The cognitive impairment group had less functional independence, balance, and gait performance than those of the non-cognitive impairment group had. The former also showed a statistically significant decrease in their TUG score, FTSST score, BBS score, and MBI score compared to the latter, but not in their 10mWT score (p<0.05). Although the non-cognitive impairment group walked faster than the cognitive impairment group did, that difference was not statistically significant (p>0.05). Conclusion: The results of this study suggest that cognitive impairment relates to functional independence in postural stability and the activities of daily living. In rehabilitation settings, cognitive impairment would be considered a major component in therapeutic rehabilitation to overcome the patients difficult physical problems and to treat for improving functional independence more after stroke.

• 재활복지공학회논문지
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• 제8권4호
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• pp.283-289
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• 2014

본 논문에서는 능동형 대퇴의지 시스템의 설계 및 최적화에 대한 연구를 진행하였다. 본 연구의 능동형 대퇴의지 시스템은 무릎부의 1 자유도를 통해 슬관절의 움직임을 모사하는데, 실제 다리의 기능을 대체하는 것이므로 사람의 다리 무게와 최대한 유사해야 하며, 경량화가 중요한 요소라고 할 수 있다. 본 연구에서는 기존에 개발된 3-링크 구조의 능동형 의지 시스템의 문제점을 보완하기 위해 기어 구동 방식의 능동형 대퇴의지 시스템을 설계 및 제작하였고, 사용자의 만족감 향상 및 피로도 저감을 위해 최적화를 통한 경량화를 진행하고 유한요소해석을 통해 응력 및 변위 특성을 분석하고 안정성을 검증하였다. 또한 능동형 의지 시스템이 사용자의 보행 의도에 맞추어 작동하기 위해 의지의 인공 발에 스트레인 게이지를 부착하여 보행시 발의 앞, 뒷부분에 각기 다르게 가해지는 하중을 측정, 보행 주기를 판단할 수 있도록 한다. 이 때 스트레인 게이지는 미세한 변형에도 민감하게 반응하므로 유한요소해석을 통해 적절한 부착위치를 결정하고, 실제 제작 및 실험을 통해 안정성 및 보행주기 판단 여부를 검증한다.