Curriculum Vitaes
Profile Information
- Affiliation
- Professor, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
- Degree
- Ph.D. in Engineering(Mar, 1991, The University of Tokyo)
- J-GLOBAL ID
- 201801002275500853
- researchmap Member ID
- B000340311
Papers
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Smart Materials and Structures, 30(6) 065014-065014, Jun 1, 2021Abstract We propose and demonstrate a novel method to enhance vibration harvesting based on surge-induced synchronized switch harvesting on inductor (S3HI). S3HI allows harvesting of a large amount of energy even from low-amplitude vibrations by inducing a surge voltage during the voltage inversion of a synchronized switch harvesting on inductor (SSHI). The surge voltage and the voltage amplification from the conventional voltage inversion improve energy harvesting. S3HI modifies SSHI by both rewiring the circuit without adding components and using a novel switching pattern for voltage inversion, thus maintaining the simplicity of SSHI. We propose a novel switching strategy and circuit topology and analyze six methods that constitute the S3HI family, which includes traditional S3HI and high-frequency S3HI. We demonstrate that the six methods suitably harvest energy even from low-amplitude vibrations. Nevertheless, the harvestable energy per vibration cycle depends on the switching pattern and storage-capacitor voltage. The use of the proposed switching strategy, which allows energy harvesting before energy-dissipative voltage inversion, substantially increases the harvestable energy per vibration cycle. In the typical case considered in this study, the said increase is on the order of 11%–31% and 15%–450% compared to the traditional and existing high-frequency S3HI methods, respectively, depending on the storage-capacitor voltage. Additionally, the proposed circuit can be used as a traditional circuit. It could be considered a promising alternative to S3HI methods owing to its potential auto-reboot capability, which is not found in traditional S3HI circuit.
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AIAA Scitech 2019 Forum, 2019Hitomi (ASTRO-H) was an X-ray astronomical satellite launched on Feb. 17, 2016. The Hitomi satellite had both two soft X-ray telescopes with a focal length of 5.6 m and two hard X-ray telescopes with a focal length of 12 m for observation with a wide energy range. In this paper, the structural performance of Hitomi satellite on orbit was reported. On Feb.28, 2016, a 6m Extensible Optical Bench (EOB) was successfully deployed. During the deployment, the induced vibration of EOB was observed. One of the major causes was estimated to be periodic constraint changes of the EOB’s root. After the deployment, the established stiffness and alignment performance of the EOB agreed well with the predicted values. Furthermore, high shape stability of the structure could be obtained on orbit.
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TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN, 16(2) 181-187, 2018<p>An Extensible Optical Bench (EOB) for a X-ray satellite (ASTRO-H) had a length of 6.4m in extended configuration. Although the same type of extensible mast was used in Space Radio Telescope (Halca) in 1997, the tip mass was quite different in the case of ASTRO-H. Due to the tip mass of 150 kg, the natural frequency of EOB was less than 1Hz in the extended configuration. ASTRO-H was launched on Feb. 17, 2016, and the EOB was extended on Feb. 28, 2016, successfully. However, because the vibration of EOB occurred during the extension, the extension operation was carried out over four passes intermittently. When the amplitude of induced vibration excessed the predefined threshold, we stopped the extension, then stayed until the vibration was damped. In this paper, the induced vibration during extension and its mechanism are reported. Through simulations, it is confirmed that one of the major causes of the vibration is a periodic change of gap between mast and canister at the root of EOB.</p>
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Journal of Astronomical Telescopes, Instruments, and Systems, 4(1), Jan 1, 2018 Peer-reviewed© The Authors 2018. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. The soft x-ray spectrometer (SXS) onboard ASTRO-H (named Hitomi after launch) is a microcalorimeter-type spectrometer, installed in a dewar to be cooled at 50 mK. The energy resolution of the SXS engineering model suffered from microvibration from cryocoolers mounted on the dewar. This is mitigated for the flight model (FM) by introducing vibration isolation systems between the cryocoolers and the dewar. The detector performance of the FM was verified before launch of the spacecraft in both ambient condition and thermal-vacuum condition, showing no detectable degradation in energy resolution. The in-orbit detector spectral performance and cryocooler cooling performance were also consistent with that on ground, indicating that the cryocoolers were not damaged by launch environment. The design and performance of the vibration isolation system along with the mechanism of how the microvibration could degrade the cryogenic detector is shown. Lessons learned from the development to mitigate unexpected issues are also described.
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JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES, 28(7) 888-906, Apr, 2017 Peer-reviewedThis article describes the optimal configuration and combination of piezoelectric transducers and inductors for the synchronized-switch-damping-on-an-inductor technique. The technique suppresses structural vibrations by inverting the polarity of the electric voltage in a piezoelectric transducer using a switched inductive shunt circuit at each displacement extremum. The energy dissipation rate of synchronized switch damping on an inductor depends on the impedances of the transducer and the inductor in the circuit, especially the resistive component, in this inversion. For this study, mathematical models of the equivalent resistances of transducers and inductors for this inversion phenomenon were formulated based on experiments with various transducers and inductors. Using these models, the optimal ratio of the thickness-area of patch-type piezoelectric transducers and that of the length-cross-sectional area of the lead of the inductors were analytically obtained. The optimization of series-parallel connections of multiple transducers and inductors was also shown to be equivalent to this one. The optimal mass budget allocation for the transducers and inductors was also formulated. Two examples of optimization, involving an increase in energy dissipation rates by a factor of 4, were presented. The examples showed that the time taken to suppress free vibrations in a clamped beam was reduced to half through the optimization.
Misc.
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観測ロケットシンポジウム2020 講演集 = Proceedings of Sounding Rocket Symposium 2020, Mar, 20213rd Sounding Rocket Symposium (March 24-25, 2021. Online Meeting)
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宇宙科学技術連合講演会講演集(CD-ROM), 63rd, 2019
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宇宙科学技術連合講演会講演集(CD-ROM), 63rd, 2019
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宇宙科学技術連合講演会講演集(CD-ROM), 62nd, 2018
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宇宙科学技術連合講演会講演集, 60 6p, Sep 6, 2016
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宇宙科学技術連合講演会講演集, 60 6p, Sep 6, 2016
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宇宙科学技術連合講演会講演集, 59 5p, Oct 7, 2015
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56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, Jan 1, 2015© 2015, American Institute of Aeronautics and Astronautics Inc. All rights Reserved. ASTRO-H is a next-generation X-ray observatory satellite planned for launch in fiscal 2015. Because ASTRO-H is a large structure and requires precise and accurate pointing, an understanding of on-orbit thermal deformation behavior is particularly important to the success of the ASTRO-H mission. In the conventional technique for predicting thermal deformation, testing is performed in a thermal vacuum chamber so asto simulate the temperature distribution on orbit. However, when using this conventional technique it is difficult to observe the detailed characteristics of the tested structures due to the limits of the applied temperature distribution cases. To overcome this problem, we propose a new evaluation technique for ASTRO-H. In our technique, on-orbit prediction of thermal deformation is performed thorough numerical simulation using a finite element (FE) model. The validation and correlation of the FE model are carried out by comparing results with thermal deformation test data collected in advance. This technique is especially suitable for satellites that are exposed to various thermal conditions on orbit. Using this technique, we confirmed all of the requirements for on-orbit pointing accuracy and precision in ASTRO-H.
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宇宙科学技術連合講演会講演集, 58, Nov 12, 2014
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Aeronautical and Space Sciences Japan, 60(1) 8-14, 2012イプシロンロケットは,段階的な開発を実施する計画であり,第1ステップではM-VロケットおよびH-IIAロケットで培った技術を最大限に活用し,平成25年度に打ち上げる.この方針に従い,構造系開発も第1ステップでは短期間で確実な開発(効率的開発)のため,多くの既開発コンポーネントを流用または改修流用する.本稿では,まず第1ステップ構造系全体の概要を述べ,次に新規開発コンポーネントである第2,3段固体モータケース(軽量・低コスト化),衛星分離部(衛星振動環境緩和),第3段機器搭載構造,フェアリング(水没機能付加)について説明する.衛星機械環境としては,乗り心地向上のため音響環境を世界標準レベル(OASPL 140dB程度)まで緩和することを目的とした射座煙道の設計解析と地上燃焼試験の概要を示す.最後に,第2ステップに向けた構造系抜本的低コスト化研究の概要について述べる.
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JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 59(686) 55-60, Mar 5, 2011Passive damping augmentation is one of attractive methods for vibration suppression to various kinds of structures because it is definitely stable and generally simple. Using viscous adhesive indicated a remarkable effect to the vibration suppression in the practical application to a satellite. In this paper, mathematical model of thin viscous adhesive layer using non-linear elements has been proposed. In this model, the characteristics of elements are correlated with non-linear internal phenomena of polymer. The simulation results using this proposal model are good agreement with experimental ones.
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Research bulletin of Iwaki Meisei University College of Science and Engineering, (24) 16-20, Mar, 2011
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The Proceedings of the Space Engineering Conference, 2010 _J4-1_-_J4-4_, 2011To meet advanced science missions, large and precise support structures such as truss structures are needed. In this paper, pointing control of a truss structure is discussed. To control the truss structure, thermal expansion of truss members is utilized instead of mechanical actuators. Heaters are equipped to truss members so that the thermal expansion of the members is controlled by heaters. PI control is applied to an experimental model which is box truss with 1.9m height. Through experiments, it is shown that the truss structure can be controlled with good accuracy, for example, within 3 arcsec error.
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Proceedings of SPIE - The International Society for Optical Engineering, 7732, 2010© 2010 SPIE. The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV) provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray detector (40-600 keV). The micro-calorimeter system is developed by an international collaboration led by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of ΔE ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be pursued.
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Abstracts Fall Meeting of the Japanese Society for Planetary Sciences, 2009, Sep 28, 2009
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The Proceedings of the Materials and processing conference, 2009 _244-1_-_244-2_, 2009
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構造強度に関する講演会講演集, 49th 178-180, 2007
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宇宙科学技術連合講演会講演集(CD-ROM), 50th, 2006
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2006/12/21-22,相模原, 2006,, 2006 Peer-reviewed
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自動制御連合講演会(CD-ROM), 48th H1-26, Nov 25, 2005
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JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 53(613) 43-50, Feb 5, 2005Passive damping augmentation is one of attractive methods for vibration suppression to various kinds of structures because it is definitely stable and generally simple. The system using thin film with viscous adhesive indicated a remarkable effect to the vibration suppression in the practical application to a satellite. To investigate its damping characteristic, several kinds of experiments have been performed. The results show that the non-linear behavior cause of non-Newtonian flow between shear load and shear deformation velocity in the viscous lamina of the thin film contributes to the damping capability. A mathematical model which consists of spring elements as film and friction elements as viscous lamina has been proposed from experiments. The simulational results with this present model are in good agreement with experimental ones.
Presentations
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33rd International Symposium on Space Technology and Science, Mar 1, 2022
Teaching Experience
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Oct, 2022 - Jan, 2023飛翔体構造工学概論 (東京大学大学院工学系研究科航空宇宙工学専攻)
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Aug, 2022 - Aug, 2022衛星システム設計学特論 (公立大学法人大阪)
Research Projects
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科学研究費助成事業, 日本学術振興会, Apr, 2023 - Mar, 2027
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科学研究費助成事業 基盤研究(C), 日本学術振興会, Apr, 2020 - Mar, 2023
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Japan Society for the Promotion of Science, Apr, 2014 - Mar, 2018
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, 2008 - 2010
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, 2007 - 2008
