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Compass-gait Walker 의 역학적 모델 및 제어 방법: 학부생들을 위한 운동방정식 유도, 시뮬레이션 방법 소개
차명주,문선웅,조권승,허필원 제어로봇시스템학회 2021 제어로봇시스템학회 국내학술대회 논문집 Vol.2021 No.6
Student majoring in engineering are interested in bipedal robot research. However, it is not easy to know what they need to study or understand, at first. For them we present contents by taking compass-gait walker as an example. To control the compass walker, we have to construct dynamic model using kinematics and kinetics. It is important to take a closer look at the event of a heal strike in detail. When a heel strike occurs, the walker gets the impulsive force from the ground that causes abrupt velocity changes. After constructing dynamic model, we make the trajectories for the walker to follow. We can use a PD controller for the tracking control. The results show that the compass-gait walker can walk resembling human walking.
학부생들을 위한 최적 제어 방법 소개: Direct Collocation 방법을 이용한 Compass-gait Walker 최적 제어
문선웅,차명주,조권승,허필원 제어로봇시스템학회 2021 제어로봇시스템학회 국내학술대회 논문집 Vol.2021 No.6
To control bipedal robots, trajectories are needed. To find to optimal trajectory, direct collocation method can be used. Direct collocation discretizes the continuous-time dynamics and uses nonlinear programming. Compass-gait Walker (CGW) are used as an example. Given the robotic equations and impact dynamics from [1], an interior point algorithm is applied to solve the nonlinear programming. Optimal trajectory and optimal control were computed and applied to control CGW. The results along with phase portrait are presented.
Effects of Bat Type on the Swing Motion of High School Baseball Athletes
최민라,송성우,차명주,신민영,이기광 한국운동역학회 2018 한국운동역학회지 Vol.28 No.2
Objective: The purpose of this study was to investigate the factors affecting two kinds of bat swing behavior through kinematic analysis. Method: A total of 32 high school baseball players participated in this study. The ball was placed on the tee-ball in a position where the subject could easily swing and the standard bat swing was performed as quickly and as accurately as possible using aluminum bats and wooden bats. Results: The aluminum bat showed a rapid swing speed of about 1.79 m/sec compared to the wooden bat. The speed of the batted ball was found to be significantly greater for the aluminum bat than for the wooden bat. In addition, although the difference between the shoulder-pelvis rotation angle according to the type of bat was not indicated, there was a statistically significant difference between the aluminum bat and the wooden bat in terms of the rotational angular velocity. Conclusion: Even though the results can explain the difference between the bat swing speed and the speed of the batted ball depending on the bat's material, it is difficult to explain the difference depending on the type of bat at the shoulder-pelvis rotation angle. However, shoulder-pelvic rotation angular velocity appears to be higher for the aluminum bat, and the differences in the type of bat is considered to be related to the batting swing factor.
홍선미,Anil Kumar Mutyala,차명주,서정화,강영아,박종승 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.10
This study includes the synthesis and application of unsymmetrical zinc phthalocyanines (ZnPcs) 1 and 2 with three tertiary-butylated (tBu) and hexyl-tridecafluoro (C6F13) groups that are further connected with carbon nanotubes (CNTs) through an amide bonding to yield Pc-functionalized CNTs 3 and 4, respectively. The properties of the resulting Pc-CNT complexes are thoroughly investigated using various analytical techniques, revealing that 3 and 4 enhanced the dispersion and adhesion properties of the CNTs to poly(vinylidene fluoride) (PVDF) matrix, and thereby improved the electrical and dielectric properties. Particularly, the presence of long and fluorinated substituents in 4 allowed for better interfacial compatibility compared to alkylated Pc-CNT 3, leading to more stable dielectric behaviors. Our work has demonstrated that perfluorinated and alkylated Pc-CNT complex could be facile and effective approach toward high-performance polymer-based dielectrics.