Updated on 2024/03/29

写真a

 
YAMAGUCHI Kohei
 
Organization
Graduate School of Engineering Aerospace Engineering 3 Assistant Professor
Graduate School
Graduate School of Engineering
Undergraduate School
School of Engineering Mechanical and Aerospace Engineering
Title
Assistant Professor

Degree 1

  1. 博士(工学) ( 2017.3   京都大学 ) 

Education 2

  1. Kyoto University   Graduate School, Division of Engineering   Department of Electrical Engineering

    2014.4 - 2017.3

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    Country: Japan

  2. Kyoto University   Faculty of Engineering   Electric and Electronic Engineering

    2008.4 - 2012.3

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    Country: Japan

Professional Memberships 2

  1. 日本航空宇宙学会   中部支部幹事,会計

    2020.4 - 2022.3

  2. 日本機械学会

Awards 8

  1. 計測自動制御学会中部支部大五十三期支部研究賞

    2023.1   計測自動制御学会   吸引領域の高速推定手法に基づく非線形システムの構造・制御準同時最適化手法

    山口皓平,原進

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    Country:Japan

    中部支部では,計測制御関連分野のおける教育活動の活性化を目的に,中部支部管轄地域内における関連 分野の教育機関優秀卒業者に対して,支部長名で表彰を行います.

  2. 工学教育賞(論文・論説部門)

    2021.3   日本工学教育協会   2スケールの実験を組み合わせる体験型教育の提案と実践:実際の免振建築物を用 いた自由振動実験と模型装置を用いた振動のアクティブ制御実験による振動と制御 の工学教育

    山口皓平,原進,岡本正吾,井上剛志,宮田喜久子,福和伸夫,飛田潤

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    Country:Japan

    日本工学教育協会では,わが国の工学教育ならびに技術者教育等に対する先導的,革新的な試みによって,その発展に多大の影響と貢献を与えた業績を表彰するために,工学教育賞を制定している.

  3. 日本機械学会東海支部特別功労賞

    2021.3   日本機械学会  

    山口皓平

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    Country:Japan

  4. 日本機械学会東海支部 奨励賞

    2019.2   日本機械学会   宇宙プラズマ環境を利用した地球接近小天体の軌道変更手法に関する研究

    山口皓平

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    Country:Japan

  5. 第62回 宇宙科学技術連合講演会 若手奨励賞 最優秀論文

    2019.1   日本航空宇宙学会   小天体衝突機の軌道変更効果を可視化するImpact Geometry Mapの提案

    山口皓平

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    Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

  6. 第58回 宇宙科学技術連合講演会 若手奨励賞 優秀論文

    2015.1   日本航空宇宙学会  

    山口皓平

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    Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

  7. 京都大学工学研究科 馬詰研究奨励賞

    2014.6   京都大学 大学院工学研究科  

    山口皓平

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    Country:Japan

  8. 京都大学工学研究科 馬詰研究奨励賞

    2014.6   京都大学 大学院工学研究科  

    山口皓平

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    Country:Japan

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Papers 47

  1. 小天体の軌道変更ミッションによる地球衝突の回避 Invited Reviewed

    山口皓平

    日本航空宇宙学会論文集   Vol. 72 ( 7 )   2024

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

  2. Analysis on Enhancement of Control Moments Using Control Surfaces and Multiple Propellers Reviewed

    Okada Yudai, Yonezawa Koichi, Sunada Shigeru, Yamaguchi Kohei

    JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES   Vol. 72 ( 1 ) page: 1 - 10   2024

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

    <p>The lateral/directional attitudes of small airplanes are easily disturbed by crosswind in take-off or landing operations, because the flight velocities and moments of inertia are smaller than those of large airplanes. Although conventional airplanes mainly control their lateral/directional attitudes by using the control surfaces such as an aileron and a rudder, the moments generated by the control surfaces are not enough in low-flight-velocity conditions such as in take-off or landing operations. The present paper focuses on a control strategy using multiple tractor propellers for small airplanes to generate sufficient moments in the low-flight-velocity conditions. This method utilizes the thrusts of propellers and the effect of interaction between the propellers and the main wing in addition to control surfaces. The present paper confirmed this method approximately achieves to double the control moments compared with those just by the control surfaces and showed the relationship between the number of propellers and the control moments in this method. </p>

    DOI: 10.2322/jjsass.72.1

    CiNii Research

  3. High Crosswind-Tolerance Airplane by Adjusting Dihedral Angle and Vertical Tail Volume

    Watanabe, S; Sunada, S; Yamaguchi, K

    JOURNAL OF AIRCRAFT   Vol. 60 ( 2 ) page: 423 - 436   2023.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2514/1.C036649

    Web of Science

  4. Geometric-Parameter and Controller Optimization of Hovering Multirotor Aircraft by Expanding the Size of the Domain of Attraction Reviewed

    Yamaguchi Kohei, Hara Susumu

    Technical Journal of Advanced Mobility   Vol. 4 ( 2 ) page: 11 - 19   2023

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Japan UAS Industrial Development Association  

    A multirotor aircraft is a rotorcraft with more than two rotors. Owing to its relatively simple mechanisms for flight control, it has been widely used in various fields, such as aerial photography and disaster management. To determine an optimal design for a multirotor aircraft, the geometric parameters and controllers are quasisimultaneously optimized. The domain of attraction, which defines the stable region around an equilibrium point for a nonlinear system, was used as an objective function for optimization. By finding geometric parameters and the controller that expands the size of the attraction domain, a multirotor aircraft can be optimized. The visualization of the domains shows that the optimized aircraft can deal with a larger deviation from an equilibrium point compared with the original aircraft.

    DOI: 10.34590/tjam.4.2_11

    DOI: 10.34590/tjam.4.2_11

    CiNii Research

    Other Link: https://doi.org/10.34590/tjam.4.2_11

  5. Optimization of High-Crosswind-Tolerant Airplane Based on Double-Hinged-Wing and No-Vertical-Tail Configuration

    WATANABE Shun, SUNADA Shigeru, YAMAGUCHI Kohei

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES   Vol. 66 ( 3 ) page: 70 - 82   2023

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

    Crosswind gusts can easily disturb the attitude of a small fixed-wing aircraft, potentially causing a serious accident during landing or take-off operations. An airplane with a high tolerance to crosswind gusts owing to quite small <i>C</i><sub><i>l</i><sub>β</sub></sub> and <i>C</i><sub><i>n</i><sub>β</sub></sub> values, called a Quasi-Neutral Dihedral-effect and Directional-stability (QNDD) airplane, was previously proposed. Although the design of a QNDD airplane is more practical than that of a Neutral Dihedral-effect and Directional-stability (NDD) airplane, a QNDD airplane’s robustness to errors in <i>C</i><sub><i>l</i><sub>β</sub></sub> and <i>C</i><sub><i>n</i><sub>β</sub></sub> should be comparatively higher. In the present study, the QNDD airplane’s robustness is optimized using Sequential Least-Squares Quadratic Programming (SLSQP). The optimized QNDD airplane has a unique configuration: a highly deflected swept-forward main wing. It is confirmed that the optimized design is much more robust than the original. To evaluate the performance of the optimized QNDD airplane, airplane plunging into a discrete crosswind gust is numerically simulated, and the results confirm that the airplane’s change in attitude is still quite small compared with that of a conventional airplane.

    DOI: 10.2322/tjsass.66.70

    Web of Science

    CiNii Research

  6. High Crosswind-Tolerance Airplane by Adjusting Dihedral Angle and Vertical Tail Volume Reviewed

    Shun Watanabe, Shigeru Sunada, Kohei Yamaguchi

    Journal of Aircraft   Vol. 60 ( 2 ) page: 423 - 436   2022.12

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2514/1.C036649

  7. Orbital Dynamics of Gravity Tractor Spacecraft Employing Artificial Halo Orbit Reviewed International coauthorship International journal

    [1] K. Yamaguchi, J. Park, X. Gu, T. Inamori

    Acta Astronautica   Vol. 198   page: 376 - 387   2022.9

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.actaastro.2022.06.009

    DOI: 10.1016/j.actaastro.2022.06.009

    Web of Science

  8. Attitude control of spin-type space membrane structures using electromagnetic force in earth orbit

    Y. Yamada, T. Inamori, J. H. Park, Y. Sugawara, K. Yamaguchi

    Advances in space research   Vol. 69 ( 10 ) page: 3864 - 3879   2022.5

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.asr.2022.02.050

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  9. On Structural Parameter Optimization Method for Quad Tilt-Wing UAV Based on Indirect Size Estimation of Domain of Attraction Reviewed

    Kohei Yamaguchi, Susumu Hara

    IEEE Access   Vol. 10   page: 1678 - 1687   2022

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Institute of Electrical and Electronics Engineers (IEEE)  

    DOI: 10.1109/ACCESS.2021.3139156

    Web of Science

  10. Quasi-Simultaneous Optimization of Structural Parameters and Controller for Non-Linear Systems Using Indirect Size Estimation of Domain of Attraction Reviewed

    Yamaguchi, K; Hara, S

    2022 61ST ANNUAL CONFERENCE OF THE SOCIETY OF INSTRUMENT AND CONTROL ENGINEERS (SICE)     page: 568 - 573   2022

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)  

    Web of Science

  11. Vertical Autorotation Strategies for a Quadrotor with a Collective Pitch Control Mechanism Reviewed

    Shibata Kota, Maeda Yosuke, Yamaguchi Kohei, Watanabe Shun, Sunada Shigeru, Tanabe Yasutada, Sugawara Hideaki, Tokutake Hiroshi, Yonezawa Koichi

    Technical Journal of Advanced Mobility   Vol. 3 ( 7 ) page: 91 - 106   2022

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Japan UAS Industrial Development Association  

    Vertical autorotation is proposed and investigated as an emergency landing technique for a multirotor drone suffering a total loss of one motor. A quadrotor with collective pitch control mechanisms is assumed. The blades have no twist because the rotors operate in windmill and propeller modes. The vertical autorotation consists of two phases. In phase 1, all rotors operate in windmill mode and the collective pitch for no attitude control is determined so as to minimize the terminal descending velocity. The quadrotor attitude in phase 1 is adjusted by varying the collective pitch. Flight control in this phase will be a research theme in future. In phase 2, two rotors, including a damaged one, operate in windmill mode while the other two operate in propeller mode. The collective pitch is determined so that the terminal descending velocity at landing is close to 0. Each multirotor has a particular critical altitude value, which relates to the specifics of this vertical autorotation. Critical altitude is the altitude for the case in which phases 1 and 2 are switched just when the descending velocity converges to the terminal velocity during phase 1. The detailed autorotation process depends on the magnitude relationship between the quadrotorʼs critical and initial altitudes.

    DOI: 10.34590/tjam.3.7_91

    CiNii Research

  12. Study on ballistic kinetic impactor mission design and evaluation using impact-geometry maps

    Kohei Yamaguchi, Xinbo Gu, Takaya Inamori, Kahaku Kimura, Yuto Sakurai

    Acta Astronautica   Vol. 181 ( 4448 ) page: 336 - 351   2021.4

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    Language:English   Publishing type:Research paper (scientific journal)  

    This paper aims to investigate the ballistic kinetic impactor (B-KI) in order to mitigate the risks posed by a potential asteroid collision on Earth in the future.
    The B-KI is a spacecraft that employs a single impulsive thrust to put the spacecraft into an orbit, which, in turn, impacts the target asteroid to deflect it from the collision route of Earth.
    To evaluate the effectiveness of the B-KI, we introduce impact-geometry maps (IGMs), which visualize the achievable change in the orbital energy of the asteroid as a function of the spacecraft's semi-major axis and eccentricity. The achievable performance of the B-KI is investigated in the form of its mobility capability on the IGM.
    In addition, parameters that govern the mission's feasibility, such as the spacecraft's relative impact speed and phase angle, are discussed.
    We conducted a parametric study on the asteroid's orbital elements and found that the B-KI is, in fact, a better option for deflecting asteroids belonging to the Aten family at the intersection point where the radial velocity component is positive.
    We also designed several fictional B-KI missions to achieve a more realistic asteroid mitigation campaign scenario.
    The obtained results are compared with those of previous kinetic impactor studies that employ low-continuous-propulsion systems.
    The study finally highlights that the B-KI can efficiently increase the impact efficiency and deflection distance for a part of the target asteroids.

    DOI: 10.1016/j.actaastro.2021.01.027

    Web of Science

  13. Conceptual Study on Robust Rebound Suppression Mechanism for Small-Body Landing Reviewed

    Kikuko Miyata, Manato Nozaki, Susumu Hara, Kohei Yamaguchi, Masatsugu Otsuki

    Journal of Spacecraft and Rockets   Vol. 58 ( 2 ) page: 456 - 471   2021.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Institute of Aeronautics and Astronautics (AIAA)  

    DOI: 10.2514/1.A34817

    Web of Science

  14. Proposal of a Crosswind-Tolerant Small Airplane with All Inherent Subsiding Modes by Adjusting Dihedral Angle and Vertical Tail Volume Reviewed

    Watanabe Shun, Sunada Shigeru, Katayanagi Ryoji, Yamaguchi Kohei

    JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES   Vol. 69 ( 1 ) page: 24 - 34   2021

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

    <p>A small airplane is strongly affected by crosswind in take-off and landing phases, because the flight velocity and gravitational force acting on it are not much larger than the crosswind velocity and aerodynamic force due to crosswind, respectively. A vertical tail volume can be decreased dramatically for a smaller airplane for the stability of lateral/directional motions. The NDD (Neutral Dihedral effect and Directional stability) airplane defined as <i>C</i><sub>l<sub>β</sub></sub> = <i>C</i><sub>n<sub>β</sub></sub> = 0 was conceived so that it has a tolerance to crosswind. An airplane without a dihedral effect and directional stability is not accepted in the current regulation for airplane design. Then, an airplane with small values of <i>C</i><sub>l<sub>β</sub></sub> and <i>C</i><sub>n<sub>β</sub></sub> has been newly proposed. All of the modes in the lateral/directional motions can converge without oscillating in the proposed airplane, named ``QNDD'' airplane, which is not observed in the NDD airplane. </p>

    DOI: 10.2322/jjsass.69.24

    CiNii Research

  15. Evaluation of Two-Hinged Wings

    WATANABE Shun, SUNADA Shigeru, YAMAGUCHI Kohei

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES   Vol. 64 ( 5 ) page: 267 - 272   2021

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

    <p>Two types of wing geometries imitating wings of birds in gliding flight are analyzed with the vortex lattice method in terms of lift-drag ratio and root bending moment while varying the joint positions and joint angles under the constant lift coefficient and constant flight velocity conditions. One geometry is, what is sometimes called, a gull wing which has a dihedral inner wing and horizontal outer wing, named “DH wing.” On the contrary, the other geometry is a drooped wing which has a horizontal inner wing and anhedral outer wing, named “HA wing.” The lift-drag ratio of the HA wing becomes larger when the joint of the anhedral outer wing is closer to the wing tip with a larger anhedral angle, while the root bending moment of the HA wing becomes smaller when the joint of the anhedral outer wing is closer to the wing root with a larger anhedral angle. In contrast, the DH wing has no combination of a joint position and joint angle to improve the lift-drag ratio, and it is found that the HA wing effectively contributes to the reduction of the root bending moment and the lift-drag ratio compared with the DH wing.</p>

    DOI: 10.2322/tjsass.64.267

    Web of Science

    CiNii Research

  16. A Study on Improvement of Performance of a Multiple Rotor Drone Reviewed

    Sunada Shigeru, Tanabe Yasutada, Yonezawa Koichi, Tokutake Hiroshi, Umezaki Shuichi, Yamaguchi Kohei, Sugawara Hideaki

    Journal of the Robotics Society of Japan   Vol. 39 ( 4 ) page: 357 - 362   2021

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Robotics Society of Japan  

    <p>The following three points have been investigated for improving the flight performance of a multiple rotor drone. The first one is `collective pitch control', which enables rotors to change the thrust much quicker than the rotor speed control method.Furthermore, a negative thrust can be generated by the rotors with a negative collective pitch. The negative thrust can cause a large control moment for controlling the attitude. Then, the drone has high maneuverability thanks to the quick thrust change due to the collective pitch control. The second one is `decreases of the moments of inertia', which can enhance the maneuverability of the drone. The variation of moments of inertia has also possibility to decrease a motion of the drone due to a disturbance moment when a feedback control is adopted. The third one is `a rotor with small aspect ratio rotor blades', which generates a larger thrust caused by the larger chord length and the larger thrust coefficient. </p>

    DOI: 10.7210/jrsj.39.357

    CiNii Research

  17. Highly Effective Kinetic Impact Design for Asteroid Deflection Missions Exploiting Impact-Geometry Maps Reviewed

    Kohei Yamaguchi, Ryo Hayama, Kikuko Miyata, Susumu Hara

    Journal of Guidance, Control, and Dynamics   Vol. 43 ( 6 ) page: 1082 - 1098   2020.6

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2514/1.G004867

    Web of Science

    J-GLOBAL

  18. Orbital Maneuvering of Electric Solar Wind Sail Based on an Advanced Solar Wind Force Model Reviewed

    Kohei Yamaguchi, Kikuko Miyata

    Acta Astronautica   Vol. 166   page: 417 - 430   2020.1

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.actaastro.2019.10.001

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    J-GLOBAL

  19. Experience-Based Lecture for Vibration Engineering Using Dual-Scale Experiments: Free Vibration of an Actual Seismic Building and Controlling the Vibration of Scale-Down Experimental Model Reviewed

    Yamaguchi Kohei, Hara Susumu, Okamoto Shogo, Inoue Tsuyoshi, Miyata Kikuko, Fukuwa Nobuo, Tobita Jun

    IEEE ACCESS   Vol. 8   page: 94767 - 94779   2020

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/ACCESS.2020.2994329

    Web of Science

    J-GLOBAL

  20. Development of Carry-On Data Logging Systems to Improve Real Flight Education Program Reviewed

    Kohei Yamaguchi, Shigeru Sunada, Norihiko Itoda, Kuniyuki Tsujimoto, Tatsuo Saeki

      Vol. 67 ( 4 ) page: 50-56   2019.7

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)  

  21. Note on a Method for Simulating Rotor Motion when Accelerating During Descent

    NISHIO Takuzumi, SUNADA Shigeru, YAMAGUCHI Kohei, TANABE Yasutada, YONEZAWA Koichi, TOKUTAKE Hiroshi

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN   Vol. 17 ( 5 ) page: 577 - 581   2019

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

    <p>To simulate the motion of a rotor while accelerating during slow descent, a simulation model that corrects errors in data obtained experimentally is developed in this paper. The effect caused by acceleration is expressed as errors in induced velocity and external thrust force, and defined by two correction factors. Best-fit correction factors that provide good approximations for experimental flight data of a bamboo dragonfly are searched and the effectiveness of the method proposed is shown.</p>

    DOI: 10.2322/tastj.17.577

    CiNii Research

  22. Visualization of Kinetic-Impact Effectiveness for Asteroid Deflection Using Impact-Geometry Maps Reviewed

    Kohei Yamaguchi, Hiroshi Yamakawa

    JOURNAL OF SPACECRAFT AND ROCKETS   Vol. 55 ( 5 ) page: 1181 - 1197   2018.9

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER INST AERONAUTICS ASTRONAUTICS  

    To investigate the effectiveness of a kinetic impactor that accelerates a spacecraft to impact and deflect an Earth-threatening asteroid, a graphical representation, called an impact-geometry map, is proposed in this study. Impact-geometry values that account for changes in asteroid orbital energy at an ideal orbital intersection point for the spacecraft and asteroid were investigated. The impact-geometry map is defined as a contour plot of the impact geometry as a function of the semimajor axis and eccentricity of the spacecraft. The ideal impact of the spacecraft on the asteroid depends on the shape of the injected orbit, and this is well visualized by the impact-geometry map. In addition, the trajectory optimization of photonic solar sails for fictional kinetic-impactor-mission scenarios was performed and the results with an impact-geometry map were investigated. The results were plotted on the impact-geometry map and well reflect the relationship between achievable deflection distance and impact geometry. This paper also highlights the differences between the impact geometry achieved by the mission and the ideal value obtained by the impact-geometry map.

    DOI: 10.2514/1.A33985

    Web of Science

  23. What Should be After "Maybe the World's First Attempt on Vibration Engineering Lecture (Experience-Based Program: Building to Perform a Lecture Vibrated Freely)"

    S. Hara, K. Yamaguchi

        page: 1-2   2018

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    Language:Japanese  

  24. 1B02 V-shaped Education of Vibration and Control Engineering Starting from Experiential Learning on Free Vibration of a Building

    HARA Susumu, YAMAGUCHI Kohei

    Proceedings of Annual Conference of Japanese Society for Engineering Education   Vol. 2018 ( 0 ) page: 26 - 27   2018

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    Language:Japanese   Publishing type:Research paper (other academic)   Publisher:Japanese Society for Engineering Education  

    DOI: 10.20549/jseeja.2018.0_26

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  25. Study on Shortening a Take-off Distance of a Flying Car Reviewed

    Matsui Emi, Yamaguchi Kohei, Sunada Shigeru, Okamoto Ryota, Tanaka Riku, Nishio Takuzumi, Arai Takakage

    JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES   Vol. 66 ( 6 ) page: 167 - 173   2018

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

    <p>Flying cars have been developed as next generation vehicles that enable high speed and flexible door-to-door transportations. A short take-off distance is expected to contribute to increase the possibility that flying cars will be used in our daily life. The purpose of the present study is to investigate to shorten a take-off distance of a flying car by using a wheels' driving force, propeller thrust and lift of main wings. This paper shows that accelerating the car by using wheels is efficient when the velocity is low. On the other hand, using propellers is more efficient when the car approaches to the take-off velocity. As a practical way to shorten the take-off distance, we propose a law to determine the power consumed by propellers and wheels as a function of the velocity of the flying car. Computation results show that the performance of the take-off phase of the flying car can be improved by using a high running ability of the car with wheels. </p>

    DOI: 10.2322/jjsass.66.167

    CiNii Research

  26. An Experimental System for Control Engineering Lecture Following Experiential Lecture on Vibration Engineering Using Real Building Shaking

    Hara Susumu, Yamaguchi Kohei

    Proceedings of the Japan Joint Automatic Control Conference   Vol. 61 ( 0 ) page: 1568 - 1571   2018

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    Language:Japanese   Publishing type:Research paper (other academic)   Publisher:The Japan Joint Automatic Control Conference  

    DOI: 10.11511/jacc.61.0_1568

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  27. Development of Effective Vibration Control Experimental System for Undergraduate Lecture on Modern Control Engineering

    Hara Susumu, Yamaguchi Kohei

    2018 AUSTRALIAN & NEW ZEALAND CONTROL CONFERENCE (ANZCC)     page: 136 - 140   2018

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    Language:English   Publishing type:Research paper (international conference proceedings)  

    Web of Science

  28. Development of Effective Vibration Control Experimental System for Undergraduate Lecture on Modern Control Engineering

    Hara Susumu, Yamaguchi Kohei

    2018 AUSTRALIAN & NEW ZEALAND CONTROL CONFERENCE (ANZCC)     page: 136-140   2018

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    Language:English   Publishing type:Research paper (international conference proceedings)  

  29. What Should be After “Maybe the World’s First Attempt on Vibration Engineering Lecture (Experience-Based Program: Building to Perform a Lecture Vibrated Freely)”?

    HARA Susumu, YAMAGUCHI Kohei

    The Proceedings of Conference of Tokai Branch   Vol. 2018.67 ( 0 ) page: 126   2018

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Japan Society of Mechanical Engineers  

    DOI: 10.1299/jsmetokai.2018.67.126

    CiNii Research

  30. What Should be After "Maybe the World's First Attempt on Vibration Engineering Lecture (Experience-Based Program: Building to Perform a Lecture Vibrated Freely)"

    S. Hara, K. Yamaguchi

        page: 1-2   2018

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    Language:Japanese   Publishing type:Research paper (other academic)  

  31. Experience-Based Lecture of Vibration Engineering Using Dual Scale Experiments: Feeling the Free Vibration of 5,600-ton Seismic Building and Controlling the Vibration of Scale-Down Experimental Model

    Yamaguchi, K; Hara, S

    2018 IEEE FRONTIERS IN EDUCATION CONFERENCE (FIE)     2018

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    Language:English   Publishing type:Research paper (international conference proceedings)  

    Web of Science

  32. Near Earth Asteroid Deflection Mission Using Electric Solar Wind Sail Kinetic Impactor

    K. Yamaguchi, H. Yamakawa

    In proceedings of 5th IAA Planetary Defense Conference     page: 1-2   2017.5

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    Authorship:Lead author   Language:English  

  33. Near Earth Asteroid Deflection Mission Using Electric Solar Wind Sail Kinetic Impactor

    K. Yamaguchi, H. Yamakawa

    In proceedings of 5th IAA Planetary Defense Conference     page: 1-2   2017.5

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    Language:English   Publishing type:Research paper (international conference proceedings)  

  34. 天体の地球衝突回避方法 Invited

    山口皓平

    日本天文学会 天文月報   Vol. 110 ( 2 ) page: 124-130   2017.2

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  35. 天体の地球衝突回避方法 Invited

    山口皓平

    日本天文学会 天文月報   Vol. 110 ( 2 ) page: 124-130   2017.2

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    Language:Japanese   Publishing type:Research paper (other academic)  

  36. Quantitative Evaluation of Quad Tilt-Wing Aircraft's Attitude Stability Using Region of Attraction Estimation via Sum of Square

    J. Nakamura, T. Horibe, S. Hara, D. Tsubakino, K. Yamaguchi, and H. Nagamatsu

        page: 1-8   2017

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  37. Study on Trajectory Optimization Method of Spacecraft as an Impactor for Asteroid Deflection Exploiting Impact Geometry Analysis

    HAYAMA Ryo, YAMAGUCHI Kohei, HARA Susumu

    The Proceedings of the Space Engineering Conference   Vol. 2017.26 ( 0 ) page: 1A2   2017

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    Language:Japanese   Publishing type:Research paper (conference, symposium, etc.)   Publisher:The Japan Society of Mechanical Engineers  

    Collisions between Asteroids and Earth sometimes occur and bring severe damage to human society. Some asteroid deflection techniques to avoid the collisions have been suggested by astronomers and scientists. We discuss these techniques, especially kinetic impactor. In this paper, we think about the improvement of the kinetic impactor by using the concept of Impact Geometry Map which visualizes the maximum change of the asteroid’s orbital energy by an impact. This report suggests a method to increase the change in the orbital energy of the asteroid by using locally optimal thrust vectoring and the Impact Geometry Map. We also use time differentiation of Impact Geometry to make an efficient spacecraft orbit. Additionally, we describe a global trajectory optimization method of spacecraft to increase Impact Geometry.

    DOI: 10.1299/jsmesec.2017.26.1a2

    CiNii Research

  38. Quantitative Evaluation of Quad Tilt-Wing Aircraft's Attitude Stability Using Region of Attraction Estimation via Sum of Square

    J. Nakamura, T. Horibe, S. Hara, D. Tsubakino, K. Yamaguchi, H. Nagamatsu

    In proceedings of 2017 Asia-Pacific International Symposium on Aerospace Technology     page: 1-8   2017

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  39. Electric Solar Wind Sail Kinetic Energy Impactor for Asteroid Deflection Missions Reviewed

    Kouhei Yamaguchi, Hiroshi Yamakawa

    JOURNAL OF THE ASTRONAUTICAL SCIENCES   Vol. 63 ( 1 ) page: 1 - 22   2016.3

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    An electric solar wind sail uses the natural solar wind stream to produce low but continuous thrust by interacting with a number of long thin charged tethers. It allows a spacecraft to generate a thrust without consuming any reaction mass. The aim of this paper is to investigate the use of a spacecraft with such a propulsion system to deflect an asteroid with a high relative velocity away from an Earth collision trajectory. To this end, we formulate a simulation model for the electric solar wind sail. By summing thrust vectors exerted on each tether, a dynamic model which gives the relation between the thrust and sail attitude is proposed. Orbital maneuvering by fixing the sail's attitude and changing tether voltage is considered. A detailed study of the deflection of fictional asteroids, which are assumed to be identified 15 years before Earth impact, is also presented. Assuming a spacecraft characteristic acceleration of 0.5 mm/s (2), and a projectile mass of 1,000 kg, we show that the trajectory of asteroids with one million tons can be changed enough to avoid a collision with the Earth. Finally, the effectiveness of using this method of propulsion in an asteroid deflection mission is evaluated in comparison with using flat photonic solar sails.

    DOI: 10.1007/s40295-015-0081-x

    Web of Science

  40. Near-Earth Asteroid Deflection Mission Using Coulomb Force Attractor Reviewed

    K. Yamaguchi, H. Yamakawa

    The 30th ISTS Special Issue of Transactions of JSASS, Aerospace Technology Japan   Vol. 14 ( 30 ) page: 119-126   2016

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    DOI: 10.2322/tastj.14.Pd_119

  41. Development of an asteroid charging model based on the three dimensional mesh model for the electrostatic tractor Reviewed

    K. Yamaguchi, N. Thiry, M. Vasile, H. Yamakawa

    Proceedings of the International Astronautical Congress, IAC     2016

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    Several mitigation methods have been studied to various degree of accuracy in the literature to deflect an asteroid from its collision course with the Earth. With the gravity tractor method, the gravitational attraction between the asteroid and a massive spacecraft is used to exert a small force remotely to tow the asteroid in the required direction to avoid an impact. One of the drawbacks of this method is the lack of control over the force produced as it only depends on the mass of the spacecraft and its distance from the asteroid. To overcome this, a new method was introduced: the electrostatic tractor. With this strategy, the deflection force is exerted by means of the electrostatic force produced by artificially charging both a spacecraft and the asteroid, which allows improving the achievable deflection. Our paper discusses a new computation model to investigate the asteroid charging mechanism produced by a plasma contactor placed on the surface of the asteroid. Unlike a simple estimation assuming a cohesive, conductive, and spherical asteroid, our model can handle the case of asteroids with an arbitrary complex shape by solving the Maxwell equations on a 3D mesh. Assuming a quasi-steady condition and an asteroid composed of an Ohmic material, it can be shown that solving the Maxwell equations on the 3D domain is equivalent to solving a Laplace equation for the potential field inside the asteroid. The boundary conditions are introduced by considering the interaction between the charged asteroid and the ambient plasma. This interaction is modeled by equivalent current sources into the surface elements, accounting for the contribution of free electrons, protons, secondary electrons, and photoelectrons, and constitutes a non-linear function of the potential V of the surface elements. Using a finite element approach provides a way to discretize this problem and reformulate it as an equivalent electric network. In this network, adjacent vertices in the mesh are connected via equivalent resistances, which depend on the geometry and the local material properties. Finally, a Newton method is employed to solve the non-linear boundary problem. Analysis for several asteroids are performed with our model and the results of the parametric study about the material, shape, and ambient plasma conditions are provided in the paper.

    Scopus

  42. B01 Study on the Kinetic Energy Impactor for Asteroid Deflection Using Electric Solar Wind Sail Reviewed

    Yamaguchi Kouhei, Yamakawa Hiroshi

    The Proceedings of the Space Engineering Conference   Vol. 2015 ( 0 ) page: _B01 - 1_-_B01-6_   2015

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    Language:Japanese   Publishing type:Research paper (conference, symposium, etc.)   Publisher:The Japan Society of Mechanical Engineers  

    Electric sail uses natural solar wind plasma stream to generate a propulsive force and it allows a spacecraft to perform orbit transfer with small reaction mass. The aim of this paper is to investigate the performance and feasibility of electric sail kinetic impactor for asteroid deflection missions. Asteroid mitigation scenario and simulation model for electric sail are given. Through detailed studies using numerical simulations, performance of electric sail kinetic impactor is emphasized.

    DOI: 10.1299/jsmesec.2015.24._B01-1_

    CiNii Books

  43. STUDY ON THE REQUIRED ELECTRIC SAIL PROPERTIES FOR KINETIC IMPACTOR TO DEFLECT NEAR-EARTH ASTEROIDS

    Kouhei Yamaguchi, Hiroshi Yamakawa

    SPACEFLIGHT MECHANICS 2015, PTS I-III   Vol. 155   page: 835 - 853   2015

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    Authorship:Lead author   Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:UNIVELT INC  

    The electric sail is a next-generation propulsion system which enables a spacecraft to produce thrust without consuming any reaction mass. It uses a interaction between many charged long thin tethers and the solar wind to produce the propulsive force. This paper discussed the required propertied of the electric sail for kinetic impactor to deflect the near earth asteroids. As fundamental contents, solar wind force model, equations of motion, and orbital maneuvering technique are provided. In addition, more practical theory as the way to calculate the optimal mass model of electric sail and terminal guidance technique are also provided. Those contents are combined into one simulation tool to investigate the efficiency of the electric sail kinetic impactor and required electric sail properties. Through the case study based on real parameters of a near Earth asteroid, required properties of the electric sail and the usability of the developed tool are shown. The relation between the achievable deflection distance and resources of the electric sail are also provided.

    Web of Science

  44. Orbital Deflection of Potentially Hazardous Asteroids Using a Coulomb Force Attractor Reviewed

    K. Yamaguchi, H. Yamakawa

      Vol. 12 ( 29 ) page: 27-33   2014

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  45. Orbital Deflection of Potentially Hazardous Asteroids Using a Coulomb Force Attractor Reviewed

    K. Yamaguchi, H. Yamakawa

    The 29th ISTS Special Issue of Transactions of JSASS, Aerospace Technology Japan   Vol. 12 ( 29 ) page: 27-33   2014

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  46. Ray Tracing of Whistler-Mode Chorus Elements: Implications for Generation Mechanisms of Rising and Falling Tone Emissions Reviewed

    K. Yamaguchi, T. Matsumuro, Y. Omura, and D. Nunn

      Vol. 31   page: 665-673   2013

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    DOI: 10.5194/angeo-31-665-2013

  47. Orbital Maneuver of Electric Sail using ON/OFF Thrust Control Reviewed

    Kohei Yamaguchi, Hiroshi Yamakawa

      Vol. 12   page: 79-88   2013

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)  

    DOI: 10.2322/astj.12.79

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MISC 4

  1. On Trajectory Optimization Method for Kinetic Impactor to Deflect Earth Threatening Asteroids Using Impact-Geometry Maps

    山口皓平, 羽山諒, 宮田喜久子, 原進

    宇宙科学技術連合講演会講演集(CD-ROM)   Vol. 63rd   2019

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  2. Study on Emergency Landing Method for a Collective Pitch Controllable Quadrotor UAV Suffering a Loss of One Motor

    Kohei Yamaguchi, Yosuke Maeda, Shun Watanabe, Kota Shibata, Shigeru Sunada, Yasutada Tanabe, Koichi Yonezawa, Hiroshi Tokutake

    7th Asian/Australian Rotorcraft Forum     2018.10

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    Emergency maneuvering technique for a multirotor UAV suffering a total loss of one motor is studied. Unlike a traditional fault tolerant control law that stabilizes the UAV using healthy rotors, an autorotation for a multirotor UAV employing a variable pitch control mechanism is proposed. The autorotation in which a rotor turn by air rather than by a motor is achieved by changing the pitch angle of rotor blades. The variable pitch mechanism is introduced for a quick change in thrust force, the proposed technique does not require any additional equipment like a parachute. When all the motors are stopped, around 10 m/s of descending velocity for the 4.2 kg-quadrotor UAV is achieved. Moreover, by using the thrust of two healthy motors, the descending velocity becomes 8.4 m/s. The simulation results also show that we need to care for the rotation of the fuselage of the UAV.

    Scopus

  3. Study on a Trajectory Optimization Method of Spacecraft for Asteroid Deflection Exploiting Impact Geometry Map

    羽山諒, 山口皓平, 宮田喜久子, 原進

    宇宙科学技術連合講演会講演集(CD-ROM)   Vol. 62nd   2018

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  4. A Landing Shock Response Control Method Coexisting the Advantages of Mechanical Energy and Momentum Exchange

    宮田喜久子, 野崎愛斗, 山口皓平, 原進

    宇宙科学技術連合講演会講演集(CD-ROM)   Vol. 61st   2017

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Presentations 32

  1. Impact-Geometry解析に基づく小惑星衝突機の最適軌道設計手法の提案 Invited

    山口皓平,Gu Xinbo,田口真也,稲守孝哉

    第66回 宇宙科学技術連合講演会  2022.11.2  日本航空宇宙学会

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    Event date: 2022.11

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:熊本県   Country:Japan  

  2. 地球接近⼩天体の地球近傍拘束軌道への投⼊の可能性検討

    山口皓平

    天体力学N体力学研究会  2024.3.27 

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    Event date: 2024.3

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:秋葉原,東京   Country:Japan  

  3. 衝突機を用いた小天体の地球近傍拘束軌道への投入の可能性検討

    山口皓平

    2023年度プラネタリーディフェンス・シンポジウム  2024.2.20 

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    Event date: 2024.2

    Language:Japanese   Presentation type:Oral presentation (general)  

  4. 吸引領域の拡大を目的関数とした航空宇宙機の構造・制御の準同時 最適化手法に関する研究

    山口皓平

    第59回日本航空宇宙学会中部・関西支部合同秋期大会  日本航空宇宙学会

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    Event date: 2023.11

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:オンライン開催   Country:Japan  

  5. カオス性を考慮した安定周期軌道への投入による小天体の地球近傍拘束 International coauthorship

    山口皓平,顧 新博,稲守孝哉,田口真也,Ji Hyun Park

    第67回宇宙科学技術連合講演会  2023.10.20 

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    Event date: 2023.10

    Language:Japanese   Presentation type:Oral presentation (general)  

  6. On Geometric Parameter Optimization for Multirotor-type Aircraft based on the Indirect Size Estimation of the Domain of Attraction

    K. Yamaguchi and S. Hara

    Japan Drone  2023.6.26  JUIDA

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    Event date: 2023.6

    Language:Japanese   Presentation type:Poster presentation  

    Venue:Makuhari Messe, Chiba   Country:Japan  

  7. Practical Asteroid Retrieval Mission Design Method Based on The Capture Dynamics in the Planar Circular Restricted Three-body Problem International coauthorship International conference

    K. Yamaguchi, X.Gu, T. Inamori, J. H. Park, M. Taguchi

    34th International Symposium on Space Technology and Science  2023.6.9 

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    Event date: 2023.6

    Language:English   Presentation type:Oral presentation (general)  

  8. On Trajectory Optimization for Kinetic Impactor to Deflect Earth-threatening Asteroids International coauthorship

    Japan Geoscience Union Meeting  2023.5.21 

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    Event date: 2023.5

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  9. 小天体の軌道形状がImpact-Geometry Mapを用いた衝突機の軌道設計手法の効果に与える影響

    山口皓平

    2022年度 プラネタリーディフェンス・シンポジウム(第14回 スペースガード研究会)  JAXA/ISAS,日本スペースガード協会

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    Event date: 2023.2

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:JAXA宇宙科学研究所 研究・管理棟(新A棟)2階会議室A 及び Zoom(ハイブリッド開催)   Country:Japan  

  10. Quasi-Simultaneous Optimization of Structural Parameters and Controller for Non-Linear Systems Using Indirect Size Estimation of Domain of Attraction International conference

    K. Yamaguchi, S. Hara

    SICE Annual Conference 2022  2022.9.7 

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    Event date: 2022.9

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Kumamoto   Country:Japan  

  11. On Orbital Dynamics of Gravity Tractor Spacecraft Exploiting Artificial Halo Orbit International conference

    [1] K. Yamaguchi, X. Gu, T. Inamori, J. Park

    33rd International Symposium on Space Technology and Science  2022.3.2 

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    Event date: 2022.2 - 2022.3

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Online  

  12. Impact-Geometry Mapを利用した小惑星衝突機の軌道設計に関する研究 Invited

    山口皓平

    プラネタリーディフェンス・シンポジウム  2022.2.15 

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    Event date: 2022.2

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:オンライン   Country:Japan  

  13. Effective Trajectory Optimization Method for Kinetic Impactor for Asteroid Deflection Missions International conference

    K. Yamaguchi, X. Gu, T. Inamori, K. Miyata

    71th International Astronautical Congress, Cyberspace Edition  2020.10 

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    Event date: 2020.10

    Language:English   Presentation type:Oral presentation (general)  

    Venue:On line  

  14. Impact-Geometry Maps; Visualization of Kinetic Impact Effectiveness for Asteroid Deflection Missions International conference

    K. Yamaguchi, R. Hayama, K. Miyata and S. Hara

    2020 SciTech Forum  2020.1  AIAA

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    Event date: 2020.1

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Orlando, Florida   Country:United States  

  15. Enhancement of an Effectiveness of a Boarding Study on Flight Dynamics by using an Equipment Such as Smartphones

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    Event date: 2018.11

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  16. Study on Emergency Landing Method for a Collective Pitch Controllable Quadrotor UAV Suffering a Loss of One Motor International conference

    Kohei Yamaguchi, Yosuke Maeda, Shun Watanabe, Shigeru Sunada, Yasutada Tanabe, Koichi Yonezawa, Hiroshi Tokutake

    7th Asian/Australian Rotorcraft Forum 

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    Event date: 2018.10 - 2018.11

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Jeju Island, Korea   Country:Korea, Republic of  

  17. Visalization of Kinetic Impact Effectiveness Using Impact Geometry Map for Asteroid Deflection Missions Invited

    Kohei Yamaguchi and Hiroshi Yamakawa

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    Event date: 2018.10

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Country:Japan  

  18. Experience-Based Lecture of Vibration Engineering Using Dual Scale Experiments: Feeling the Free Vibration of 5,600-ton Seismic Building and Controlling the Vibration of Scale-Down Experimental Model International conference

    Kohei Yamaguchi, Susumu Hara

    Frontiers In Education  

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    Event date: 2018.10

    Language:English   Presentation type:Oral presentation (general)  

    Venue:San Jose, CA, U.S.   Country:United States  

  19. Experience-Based Lecture of Vibration Engineering Using Dual Scale Experiments: Feeling the Free Vibration of 5,600-ton Seismic Building and Controlling the Vibration of Scale-Down Experimental Model International conference

    Kohei Yamaguchi, Susumu Hara

    Frontiers In Education  

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    Event date: 2018.10

    Language:English   Presentation type:Oral presentation (general)  

    Venue:San Jose, CA, U.S.  

  20. インパクトジオメトリ解析を用いた小惑星衝突機の軌道最適化手法に関する研究

    羽山諒,山口皓平,原進

    日本機械学会第26回スペース・エンジニアリング・コンファレンス 

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    Event date: 2017.12

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:三浦,マホロバマインズ三浦   Country:Japan  

  21. Orbital Maneuvering of Electric Solar Wind Sail Using Advanced Thrust Model

    K. Yamaguchi

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    Event date: 2017.11

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  22. Near Earth Asteroids Deflection Mission Using Electric Solar Wind Sail Kinetic Impactor International conference

    K. Yamaguchi, H. Yamakawa

    IAA 5th Planetary Defense Conference 

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    Event date: 2017.5

    Language:English   Presentation type:Poster presentation  

    Venue:Tokyo, Japan   Country:Japan  

  23. 宇宙プラズマ環境を利用した地球接近小天体の軌道変更手法の提案と検証 Invited

    山口皓平,山川宏

    シンポジウム:天体の地球衝突問題にどう取り組むか 

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    Event date: 2017.2

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:東京,一橋大学   Country:Japan  

  24. Experience-Based Lecture of Vibration Engineering Using Dual Scale Experiments: Feeling the Free Vibration of 5,600-ton Seismic Building and Controlling the Vibration of Scale-Down Experimental Model

    Kohei Yamaguchi, Susumu Hara

    Frontiers In Education  2018.10.3 

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    Language:English   Presentation type:Oral presentation (general)  

    Venue:San Jose, CA, U.S.  

  25. Experience-Based Lecture of Vibration Engineering Using Dual Scale Experiments: Feeling the Free Vibration of 5,600-ton Seismic Building and Controlling the Vibration of Scale-Down Experimental Model

    Kohei Yamaguchi, Susumu Hara

    Frontiers In Education  2018.10.3 

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    Language:English   Presentation type:Oral presentation (general)  

    Venue:San Jose, CA, U.S.  

  26. Orbital Maneuvering of Electric Solar Wind Sail Using Advanced Thrust Model International conference

    K. Yamaguchi

    2017.11.11 

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    Language:Japanese   Presentation type:Oral presentation (general)  

  27. Visalization of Kinetic Impact Effectiveness Using Impact Geometry Map for Asteroid Deflection Missions Invited International conference

    Kohei Yamaguchi, Hiroshi Yamakawa

    2018.10.24  JSASS

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    Language:Japanese   Presentation type:Oral presentation (invited, special)  

  28. 宇宙プラズマ環境を利用した地球接近小天体の軌道変更手法の提案と検証 Invited International conference

    山口皓平, 山川宏

    シンポジウム:天体の地球衝突問題にどう取り組むか  2017.2.27  日本スペースガード協会

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    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:東京,一橋大学  

  29. Enhancement of an Effectiveness of a Boarding Study on Flight Dynamics by using an Equipment Such as Smartphones International conference

    2018.11.14 

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    Language:Japanese   Presentation type:Oral presentation (general)  

  30. インパクトジオメトリ解析を用いた小惑星衝突機の軌道最適化手法に関する研究 International conference

    羽山諒, 山口皓平, 原進

    日本機械学会第26回スペース・エンジニアリング・コンファレンス  2017.12.17  日本機械学会

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    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:三浦,マホロバマインズ三浦  

  31. Study on Emergency Landing Method for a Collective Pitch Controllable Quadrotor UAV Suffering a Loss of One Motor

    Kohei Yamaguchi, Yosuke Maeda, Shun Watanabe, Shigeru Sunada, Yasutada Tanabe, Koichi Yonezawa, Hiroshi Tokutake

    7th Asian/Australian Rotorcraft Forum  2018.10.30 

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    Language:English   Presentation type:Oral presentation (general)  

    Venue:Jeju Island, Korea  

  32. Near Earth Asteroids Deflection Mission Using Electric Solar Wind Sail Kinetic Impactor

    K. Yamaguchi, H. Yamakawa

    IAA 5th Planetary Defense Conference  2017.5.14 

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    Language:English   Presentation type:Poster presentation  

    Venue:Tokyo, Japan  

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Works 1

  1. 名古屋大学減災センター 夏期集中セミナーにおける発表

    2017.8

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    減災センター主催の夏期集中セミナーにおける発表.

KAKENHI (Grants-in-Aid for Scientific Research) 4

  1. 小惑星軌道の地球近傍におけるカオス性・安定性の解明と長期拘束軌道投入理論の確立

    Grant number:22K14420  2022.4 - 2025.3

    日本学術振興会  科学研究費助成事業  若手研究

    山口 皓平

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount:\4550000 ( Direct Cost: \3500000 、 Indirect Cost:\1050000 )

    本研究では,地球に接近する小惑星の軌道を衝突機によって変更し,地球近傍に長時間安定に拘束する軌道へとトラップする手法を確立する.小惑星の詳細な探査,または資源としての有用性は近年特に認識されつつあり,本研究は小惑星への物理的アクセス性を向上させることで当該分野の発展に資する成果を生み出す.
    本研究では特に,地球近傍における複雑な軌道ダイナミクスに対して,軌道の持つカオス性と安定性に着目した解析を行う.また,平面円制限三体問題唯一の第一積分量であるJacobi積分量の変化とカオス性・安定性との関係を解明した上で,Jacobi積分の操作による拘束軌道投入の可能性を示す.
    本研究は,地球に接近する軌道を持つ小惑星(地球接近小惑星)の速度を変更し,地球近傍に長期間にわたって拘束される軌道(拘束軌道)へと遷移させる手法を検討するものである.小惑星を地球付近に留めることで物理的なアクセス性が向上し,探査やサンプルリターンなどの科学ミッション,ひいては資源探査,採掘といった将来の産業への貢献が期待できる.
    初年度は計画に従い,地球接近小惑星速度の変化量と地球近傍における軌道の関係の定式化を行った.特に,小惑星軌道のカオス性・安定性の関係に注目した.軌道変更後の小惑星軌道がカオス性を有する場合,軌道の予測が困難となり,近傍からの早期脱出や地球への衝突の可能性を持つことになる.本研究では,小惑星自身,地球,太陽の三体の影響を考慮し,小惑星の速度変化をJacobi積分という1つのスカラ量の変化に置き換えた.Jacobi積分はこの系の保存量であり,軌道変更によって生じるJacobi積分の人工的な変化と変更後の軌道がもつカオス性の関係を明らかにした.本検討により,地球近傍の小惑星軌道がカオス性を有することを回避するのに必要なJacobi積分の変化量を計算することが可能となった.また,拘束軌道の安定性をフロケ理論によって判定するシステムも開発し,拘束軌道が周期軌道となる条件を解明することが可能となった.なお,以上の検討に伴って,シンプレクティック積分法を用いた高精度な軌道シミュレータを開発した.
    今後は,初年度で検討した内容を応用して研究を進めるとともに,国内外における研究成果の発信を加速させる.現在,第34回International Symposium on Space Technology and Scienceでの発表が決定しており,今後も積極的な情報発信を行っていく.
    初年度の予定とした「小惑星の地球近傍における軌道のカオス性と安定性の解明・理論構築」がおおむね達成されたことから,本課題は現時点においておおむね順調に進展していると判断する.
    本研究では地球近傍における軌道を制限三体問題として取り扱い,更に小惑星速度の変化をJacobi積分の変化に置き換える手法を採用している.本アプローチにはJacobi積分の計算に高い精度が求められることから,検討の根幹をなすシステムとしてシンプレクティック積分を用いた軌道シミュレータを作成した.また小惑星速度の変更後に軌道が有するカオス性を調査するため,軌道がもつカオスの度合いを判別する指標であるSALIの計算システムを開発した.最後に,速度変更後の軌道の安定性をフロケ理論により判定するシステムを開発した.加えて,以上3つを組み合わせることで小惑星の地球近傍拘束の可否を判断するシステムを開発した.更に,公開されている地球接近小惑星のデータを用いた検討も行った.現在,この検討の対象とした小惑星の数は限られているものの,次年度以降の研究につながる重要な成果が得られたと考えている.
    当初の計画に従い,2年目に予定していた「拘束軌道へ投入するための小惑星の効率的な軌道変更手法の構築」に進む.また,初年度のシステムのブラッシュアップも同時に進める.
    初年度の検討では,小惑星速度の変化をJacobi積分というスカラ量に置き換えるという問題の定式化に適した取り扱いを行った.2年目は,軌道変更に必要となるJacobi積分の変化を達成する手法を検討していく.Jacobi積分の変化が小惑星に発生する速度の変化と結びつくことで,本研究内容の実現可能性を高めることが期待できる.具体的な手法としては,小惑星衝突機を用いた速度変更について検討する.小惑星衝突機の軌道形状は,長半径と離心率で特徴づけることが可能である.またJacob積分は軌道長半径と離心率の関数として近似可能であることから,衝突によって発生するJacobi積分の変化を,宇宙機を投入する軌道形状の関数として定式化する.また,定式化した結果からJacobi積分の変化量を最大化するための宇宙機の小惑星に対する衝突軌道の最適制御則を構築する.検討には申請者がこれまで整備してきた軌道計算用の数値計算ライブラリを用い,効率的に推進する.
    研究内容の発信にも積極的に取り組む.初年度に構築したツールを積極的に活用することで,学会発表や論文投稿を行う.既に第34回International Symposium on Space Technology and Scienceでの発表が決定しており,今後も発表の機会を積極的に獲得していく.

  2. Development of High Reliable Optimization System for Asteroid Deflection Missions

    Grant number:19K15210  2019.4 - 2023.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Early-Career Scientists

    Yamaguchi Kohei

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    Authorship:Principal investigator 

    Grant amount:\3640000 ( Direct Cost: \2800000 、 Indirect Cost:\840000 )

    Methods to deflect Earth-threatening asteroids from Earth collision routes were investigated. For a kinetic impactor that impacts the asteroid with hypervelocity, a trajectory optimization method that effectively increases the impact-geometry was proposed. The impact-geometry is defined by the velocity vectors at the impact and the achievable deflection distance is proportional to the impact-geometry. The proposed method can increase the deflection distance without increasing the impact speed.
    For the gravity tractor which tows the asteroid by using the gravitational interaction between the asteroid and spacecraft, putting the spacecraft into an artificial halo orbit (AHO) was proposed. Since a spacecraft in an AHO moves circularly in a plane that is perpendicular to the towing direction of the asteroid, multiple spacecraft can be used for towing. Equations of motion and laws to control the spacecraft in AHOs were proposed. The effectiveness of the proposed law was numerically shown.

  3. 宇宙電磁環境を利用した地球衝突小惑星の軌道変更に関する研究

    2015.4 - 2017.3

    科学研究費補助金 

    山口皓平

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    Authorship:Principal investigator 

  4. 宇宙電磁環境を利用した地球衝突小惑星の軌道変更に関する研究

    2015.4 - 2017.3

    日本学術振興会  科学研究費助成事業  特別研究員奨励費

    山口皓平

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    Authorship:Principal investigator  Grant type:Competitive

 

Teaching Experience (On-campus) 9

  1. 機械・航空宇宙工学実験第1

    2021

  2. 機械・航空宇宙工学実験第2

    2021

  3. 解析力学及び演習(演習パート)

    2020

  4. 機械航空宇宙工学実験第1,第2

    2020

  5. 自動車工学実験1

    2020

  6. 解析力学及び演習(演習パート)

    2019

  7. 機械航空宇宙工学実験第1,第2

    2019

  8. 自動車工学実験1

    2019

  9. 解析力学及び演習(演習パート)

    2018

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