研究者業績
基本情報
- 所属
- 国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 教授
- 学位
- 工学博士(1991年3月 東京大学)
- J-GLOBAL ID
- 201801002275500853
- researchmap会員ID
- B000340311
研究分野
1論文
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Smart Materials and Structures 30(6) 065014-065014 2021年6月1日Abstract 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 2019年Hitomi (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年<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) 2018年1月1日 査読有り© 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 2017年4月 査読有りThis 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.
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Proceedings of the International Astronautical Congress, IAC 2016年The vibration suppression technique called LR-switching or SSDI (synchronized switch damping on inductor) has attracted considerable interest because of its simplicity, robustness, and high performance. Previously, the authors have experimentally demonstrated that this method can reduce the vibration amplitude of 140kg satellite by 50 percent by using 80grams piezoelectric transducers. This vibration suppression method converts structural vibration energy into electrical energy as a charge in the capacitance of the piezoelectric transducers. Then the polarity of this charge or voltage is inverted according to the phase of structural vibration by a switched inductive shunt circuit, so that the piezoelectric transducer generates the right polarity of force to suppress the structural vibration effectively. Although the loss of the electric energy at this voltage inversion dominates the performance of the technique, it was difficult to estimate this loss from design parameters of the transducer and inductor. Recently, the authors established a mathematical model of this energy loss based on experimental data obtained by using various piezoelectric transducers and inductors (eg. IAC-14 C2.P1X22859). This model enables us to estimate the performance of SSDI technique from design parameters. This paper proposes a method of optimization of SSDI system using this model, and demonstrates the benefit brought by the optimization. The optimization maximizes the energy dissipated by the SSDI technique per a cycle of steady state vibration. As an example, a clamped beam is considered, and a SSDI system is optimized to suppress the vibration of the beam. Results of the optimization demonstrate significant enhancement of the damping of the beam due to this optimization.
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日本物理学会講演概要集 71 369-369 2016年<p>X線天文衛星「ひとみ」には、軟X線望遠鏡(Soft X-ray Telescope: SXT)が二台搭載された。米国のGSFC/NASAが主体で開発されている。SXT-S、SXT-Iと呼ばれ、それぞれの焦点面検出器はX線カロリメーター検出器 SXS、X線CCDカメラ SXI に対応する。どちらの検出器にも天体の像が結ばれていることが確認できた。また、スペクトル中には地上のキャリブレーションで予想していた反射鏡表面に金のMやLの吸収端が見えていた。当講演では、機上で得られた性能及び、地上との予測の比較を報告する。</p>
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Proceedings of the International Astronautical Congress, IAC 8 6422-6428 2015年Many works have been reported on the semi-active vibration suppression technique so called synchronized switch damping on inductor (SSDI). The technique uses a piezoelectric patch attached to a vibrating structure and a switched inductive shunt circuit. At each extermum of the voltage across the piezo patch, SSDI technique turns on the switch of the shunt circuit such that the voltage inverses. When the inversion is completed, the switch is immediately turned off. It is well known that this technique effectively suppresses the vibration of the structure. Previously, the authors have experimentally demonstrated that this method can reduce the vibration amplitude of 140kg satellite by 50% by using 80g piezoelectric patches. In that demonstration, it revealed that multiple piezoelectric patches needed to be attached to the actual satellite structure because of the practical limitation of space where the piezoelectric patches can be attached. It was also shown that the performance in suppressing the vibration heavily depends on the configuration of parallel/series electrical connection of these patches. Therefore, we have studied and shown the optimal parallel/series connection of the patches. This paper shows the optimal configuration of parallel/series connection of not only the piezoelectric patches but also multiple inductors.
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Trans Jpn Soc Aeronaut Space Sci Aerosp Technol Jpn (Web) 12(ists29) PC.29-PC.34 (J-STAGE) 2014年
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Frontiers of Mechanical Engineering 8(3) 276-282 2013年9月Multi-cellular inflatable structures are ultralight and robust against membrane damage such as pinholes caused by space debris. Due to their robustness, inflatable structures supported by inner gases can be applied as space structures. In the present study, shape control for a simple multi-cellular inflatable panel was achieved via a novel diaphragm mechanism. When the bending actuator in a center membrane bends, the inner pressures of sub-cells become different, and the diaphragm mechanism bends as a whole. Because a sliding component is not included, this deformable system is a reliable mechanism. In addition, the proposed mechanism has higher rigidity than that of a bending actuator used alone. In the present paper, we investigate the feasibility of a novel diaphragm mechanism and its characteristics using experimental and numerical results. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.
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Telescope Co-Alignment Design and Its Performance On-Orbit of Solar Observational Satellite "Hinode"TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 56(2) 104-111 2013年3月 査読有り
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Smart Materials Research 2011(Article No. 686289) 1-8 2011年12月30日 査読有り
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Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2011年 査読有りThis paper exhibits a novel invention: "digital self-powered autonomous" vibration-suppressor using a digital micro-processor. The invented unit is a completely self-powered vibration-suppression system that does not require any external power-supply at all. Nevertheless, this digital, self-directive, and self-powered approach enables the system to be programmable and thus versatile in control scheme implementation. The digital-autonomous suppressor is much more advanced and progressive than previously proposed analog-autonomous ones that are clumsy and awkward. This digital system can be implemented in multiple-input multiple-output systems to suppress even complicated structural vibration, such as multi-modal vibration. To our best knowledge, our invention is the first one in the world, and quite useful for various applications to energy-saving or energy-shortage systems, such as large space structures, artificial satellites, and isolated lunar bases, which all are vulnerable to long night-time. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.
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Smart Materials and Structures 19 1-10 2010年8月 査読有り
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61st International Astronautical Congress 2010, IAC 2010 13 10997-11003 2010年This paper demonstrates, from viewpoint of electrical connection, comprehensive investigation of a semi-active vibration suppression method using piezoelectric actuators attached to structures. In our system, piezoelectric actuators are connected to an electric circuit composed of diodes, an inductance, and a selective switch. Our method (LR-Switching) makes better use of counter electromotive force to suppress the vibration, instead of simple dissipation of vibration energy. We use an actual artificial satellite to verify their high damping performance compared to conventional semi-active methods. As a consequence, we demonstrate that our semi-active switching method can suppress the vibration of the real artificial satellite to as much as 50% amplitude reduction. In our experiment, we reveal that the suppression performance depends on how multiple piezoelectric transducers are connected, namely, their series or parallel connection. We draw two major conclusions from theoretical analyses and experiment, for contracting effective semi-active controller using piezoelectric actuators. In this paper clearly proves that the performance of the method is the connection of multiple piezoelectric actuators and the their resistances dependent of frequency. Copyright ©2010 by the International Astronautical Federation. All rights reserved.
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61st International Astronautical Congress 2010, IAC 2010 8 6084-6089 2010年This paper demonstrates an innovative invention: "digital self-powered autonomous" vibration-suppressor using a digital micro-processor. Our invented unit is a completely self-powered vibration-suppression unit that does not require any external power-supply at all. Nevertheless, this digital, self-directive, and self-powered approach enables the vibration suppressor to be programmable and thus versatile in control scheme. The digital-autonomous suppressor is much more advanced and progressive than clumsy analog-autonomous ones. This digital system can be implemented in MIMO (multiple-input multiple-output) systems to suppress even complicated structural vibration. To our best knowledge, this invention is the first one in the world, and quite useful for various applications to energy-saving or energy-shortage systems, such as large space structures, artificial satellites, and isolated lunar bases, which all are subject to long night-time. Copyrihgt©2010 by the International Astronautical Federation. All rights reserved.
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7th Asian-Australasian Conference on Composite Materials 2010, ACCM 2010 2 839-842 2010年 査読有りSandwich structures made of carbon fiber reinforced plastics (CFRPs) have excellent characteristics such as lightweight, high stiffness, and low coefficient of thermal expansion. Therefore, CFRP is one of attractive candidates as structural material in aerospace field. Today, the use of satellite at high temperature environment such as exploration in Venus, etc., is under schedule. However, the heat resistance of resin used for current CFRP sandwich panels is pretty low. The objective of this study is to evaluate high-temperature property of newly developed sandwich panels. In the present study, polyimide and polyamide-imide resins with high thermal resistance were used for the matrix of both skin and core of heat-resistant CFRPs. The polyimide CFRP (PI) and polyamide-imide CFRP (PAI) were used for the skin materials. For core materials, in addition to PI and PAI CFRPs, diffusion-bonded aluminum honeycomb core (AL) was also used; the combinations of skin/core examined here are PAI/PAI, PI /AL and PI/PAI. To evaluate the characteristics of sandwich panels, a flatwise tensile test was performed at both room temperature and high temperature, 200?. At room temperature, an epoxy adhesive was used for the bonding between the specimen and the test fixture, and a polyimide adhesive was used for high temperature test. The highest flatwise tensile strength was realized by PI/ PAI sandwich panels. On the other hand, PI/AL sandwich panel showed the lowest strength. According to microscopic observation, it was confirmed that, for low strength specimens, the bonding between skin and core was insufficient. In addition, it was confirmed that the PI/AL panel could maintain the flatwise tensile strength up to high temperature of 200?.
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ACTIVE AND PASSIVE SMART STRUCTURES AND INTEGRATED SYSTEMS 2010, PTS 1 AND 2 7643 2010年 査読有りWe conducted various investigation of energy recycling semi-active vibration suppression method by using piezoelectric transducers attached to structures. In this method, piezoelectric transducers are connected to a shunt circuit with diodes and an inductance, and it makes better use of counter electromotive force to suppress the vibration. We had proposed some new ideas in order to upgrade this method. And we verified their high performances compared to conventional semi-active method by many experiments. In results of experiment that practically apply this method to an actual satellite structural model using lots of the piezoelectric transducer, it was found that vibration suppression performance depend on how piezoelectric transducers were connected each other. It is because their connection affects a resonance frequency and a total resistance of the shunt circuit. The performance of the method related to the connection of the piezoelectric transducers and their resistances dependent on frequency are described using experimental results in this paper.
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Solar Physics 249(2) 263-279 2008年6月The X-ray Telescope (XRT) aboard the Hinode satellite is a grazing incidence X-ray imager equipped with a 2048×2048 CCD. The XRT has 1 arcsec pixels with a wide field of view of 34×34 arcmin. It is sensitive to plasmas with a wide temperature range from <∈1 to 30 MK, allowing us to obtain TRACE-like low-temperature images as well as Yohkoh/SXT-like high-temperature images. The spacecraft Mission Data Processor (MDP) controls the XRT through sequence tables with versatile autonomous functions such as exposure control, region-of-interest tracking, flare detection, and flare location identification. Data are compressed either with DPCM or JPEG, depending on the purpose. This results in higher cadence and/or wider field of view for a given telemetry bandwidth. With a focus adjust mechanism, a higher resolution of Gaussian focus may be available on-axis. This paper follows the first instrument paper for the XRT (Golub et al., Solar Phys. 243, 63, 2007) and discusses the design and measured performance of the X-ray CCD camera for the XRT and its control system with the MDP. © 2007 Springer Science+Business Media B.V.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 59 S845-S852 2007年11月 査読有りTo understand the physical mechanisms for activity and heating in the solar atmosphere, the magnetic coupling from the photosphere to the corona is an important piece of information from the Hinode observations, and therefore precise positional alignment is required among the data acquired by different telescopes. The Hinode spacecraft and its onboard telescopes were developed to allow us to investigate magnetic coupling with co-alignment accuracy better than 1 ''. Using the Mercury transit observed on 2006 November 8 and co-alignment measurements regularly performed on a weekly basis, we have determined the information necessary for precise image co-alignment, and have confirmed that co-alignment better than 1 '' can be realized between Solar Optical Telescope (SOT) and X-Ray Telescope (XRT) with our baseline co-alignment method. This paper presents results from the calibration for precise co-alignment of CCD images from SOT and XRT.
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Solar Physics 243(1) 3-17 2007年6月The Hinode satellite (formerly Solar-B) of the Japan Aerospace Exploration Agency's Institute of Space and Astronautical Science (ISAS/JAXA) was successfully launched in September 2006. As the successor to the Yohkoh mission, it aims to understand how magnetic energy gets transferred from the photosphere to the upper atmosphere and results in explosive energy releases. Hinode is an observatory style mission, with all the instruments being designed and built to work together to address the science aims. There are three instruments onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer (EIS), and the X-Ray Telescope (XRT). This paper provides an overview of the mission, detailing the satellite, the scientific payload, and operations. It will conclude with discussions on how the international science community can participate in the analysis of the mission data. © 2007 Springer Science+Business Media B.V.
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SMART MATERIALS & STRUCTURES 16(2) 455-461 2007年4月 査読有りThis paper discusses a self-sensing vibration suppression method that measures only the value of the piezoelectric voltage. The method separates the electrical status into two cases concerning electrical current and characterizes each of these to establish a self-sensing system using extended system equations and a Kalman filter. Our self-sensing system can avoid estimation blackout during closed-circuit status and lessen harmful influences from residual modes. Experiments revealed that the self-sensing system suppressed vibrations in cooperation with state-switching and synchronized-switching controls. We confirmed that the self-sensing method is robust against model errors in a vibration suppression experiment in which there are model errors caused by an intentional frequency shift.
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JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME 129(1) 84-93 2007年2月 査読有りThis paper presents an extensive investigation on the LR-switching method (also called the energy-recycling semi-active method). Compared with the energy-dissipative R-switching method, the LR-switching method has been shown to have significantly better vibration suppression performance. However certain essential issues affecting a system employing the LR-switching method remained to, be dealt with. In particular we had to clarify its vibration suppression mechanism from the viewpoint of mechanical and electrical energy exchange. Second, the robustness of the method against model errors and control time delays had to be verified. The experiments and numerical simulations that we conducted on a 10-bay truss structure demonstrate that the LR-switching method outperforms other suppression methods under sinusoidal and random excitations, which are more common in real systems and more difficult to deal with than transient vibrations. This paper provides fundamental insights on the LR-switching method and gives the method a guarantee for actual applications.
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AIAA JOURNAL 45(2) 497-504 2007年2月 査読有りWe enhanced the bang-bang vibration control by using an electrical resonance mechanism. The bang-bang method is used in many engineering applications because of its simplified hardware configuration in which a constant-voltage supplier is shared by multiple actuators. However, its control performance is restricted, because the supplied voltage is constant and the sharp modulation of the control input induces chattering, which wastes a significant amount of energy. Our approach to overcome these problems was to combine the bang-bang method with tuned electrical resonance. Based on an elaborate analysis of phase relations between mechanical and electrical vibrations, three switching. logics were devised for the hybrid method. Experiments on a 10-bay truss structure demonstrated that our hybrid method not only enhanced vibration suppression of the bang-bang method, but also prevented control chattering.
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TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 49(166) 203-210 2007年2月 査読有りThis novel control logic for a shock absorber using particle-dispersion Electro-Rheological (ER) fluid is a powerful means of shock attenuation for satellite instruments that are subjected to lift-off shock or pyrodevice ignition shock. Satellite instruments may be damaged when the acceleration generated by the input shock exceeds their critical acceleration value. The proposed method attenuates the shock so that the instrument's acceleration does not exceed the critical value, even when the shock is too large to be accepted. In contrast to conventional linear shock controls, the proposed shock control does not attempt to attenuate a small shock in order to prepare for attenuating a coming large shock. This innovative nonlinear control enables the absorber to effectively attenuate a powerful shock. Numerical simulations show that the new shock absorber system attenuates shocks better than a passive system or a conventional linear control system.
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IFAC Proceedings Volumes (IFAC-PapersOnline) 17(1) 597-602 2007年We developed the novel control logic for a shock damper using particledispersion Electro-Rheological (ER) fluid. This is a high-powered means of shock attenuation for satellite instruments that are subjected to lift-off shock or pyrodevice ignition shock. The proposed method attenuates the shock so that the instrument's acceleration does not exceed the critical value, even when the shock is too large to be accepted. In contrast to the conventional linear shock controls, the proposed shock control does not attempt to attenuate a small shock in order to prepare for attenuating a coming large shock.
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International Astronautical Federation - 58th International Astronautical Congress 2007 8 5187-5194 2007年Experiments of vibration suppression were executed by implementing the energy-recycling semi-active method using piezoelectric transducers. The purpose of the experiment is to practically apply the method, of which performance has been proved numerically and experimentally using the truss model, to an actual satellite structural model and investigate an effectiveness and problems of the practical application. Although the damping performance in the experiments was not so good in comparison with that in the truss model experiments, it was found that the energy-recycling semi-active method worked on an actual satellite model and showed better performance than the conventional semi-active method. The description of the energy-recycling method, the configuration and the results of the experiments are presented. Copyright IAF/IAA. All rights reserved.
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KSAS, International Journal of Aeronautical and Space Sciences 7(1) 70-85 2006年11月 査読有り
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AIAA JOURNAL 44(7) 1445-1453 2006年7月 査読有りA novel self-sensing method using piezoelectric actuators for semi-active vibration suppression is proposed and investigated. By using extended system equations, this self-sensing method can be implemented with a Kalman filter instead of the conventional bridge circuit technique. The method separates electrical status into two cases concerning electrical current, and characterizes each of these to establish the self-sensing system. This method is applicable to multiple-degree-of-freedom structures with multiple piezoelectric actuators. A numerical vibration suppression simulation demonstrated that the self-sensing method works well on a truss structure and has significant robustness against parameter variations. Experimental results also demonstrated that the self-sensing method suppresses not only single-mode vibration but also multiple-mode vibration.
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Smart Materials and Structures 15 342-350 2006年4月 査読有り
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AIAA Journal 44(2) 411-413 2006年2月 査読有り
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Performance investigation of energy-efficient active vibration control using energy-recycling method16th International Conference on Adaptive Structures and Technologies 125-132 2006年A promising method of hybrid vibration control using piezoelectric transducers and switchable circuits is studied. The hybrid approach improves the control performance of the bang-bang active method, by combining it with energy-recycling approach. A part of the electrical energy needed for vibration control is converted from vibration energy and stored, rather than being provided entirely from external sources. In addition, the method recycles the stored electrical energy many times, by preventing it from being dissipated, thus minimizing energy-consumption. We discuss the spillover energy into uncontrolled vibration modes in the hybrid method. A control-chattering prevention is also presented to avoid unnecessary energy-consumption and to obviate residual mode excitation.
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Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 9 6083-6095 2006年The aim of this research is to attenuate the acoustic noise transmitted into a rocket faring by using a piezoelectric network. The paper makes two assumptions that faring structures can be deformed by actuation forces, or, not be deformed by them (i.e., easy-to-deform or hard-to-deform cases). We characterize both of these and develop acoustic controls for each. Experiments and numerical simulations demonstrated that our methods attenuated the acoustic level generated not only by simple monochromatic noise, but also broadband noise. Unique Issues concerning the acoustic problem were identified that have not been clearly recognized in the vibration suppression problem. Our attenuation method based on an energy-harvesting technique was shown to be effective for the acoustic problem in realistic hard-to-deform faring structures. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
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SMART STRUCTURES AND MATERIALS 2006: DAMPING AND ISOLATION 6169 2006年 査読有りThis paper presents a self-sensing method for semi-active vibration suppression that measures only the value of piezoelectric voltage. This self-sensing method is implemented with a Kalman filter with extended system equations, instead of the conventional bridge-circuit technique. The method has several advantages over the bridge-circuit self-sensing method, such as being applicable to MIMO systems. Experiments showed that our self-sensing system suppressed vibrations by combining the state-switching control and the synchronized-switching control. We confirmed that the self-sensing method is robust against model errors through the experiment with intentional frequency shift.
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AIAA Journal 43(8) 1706-1715 2005年8月 査読有り
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Journal of Vibration and Acoustics, Transaction of the ASME 126 272-277 2004年4月 査読有り
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International Astronautical Federation - 55th International Astronautical Congress 2004 12 8142-8148 2004年M-V is a three-staged solid-propellant satellite launcher developed by the Institute of Space and Astronautical Science (ISAS) of Japan to support various Japanese space science missions. It launches a two-ton class payload into low earth orbit. Although the initial two launches were successful, the third launch of M-V failed to put an X-ray observatory satellite into the orbit because the attitude control was lost for 20 sec in the first-stage flight. From the various data, it turned out that the heat-resistive throat-insert of the nozzle of the first stage fractured and dropped-off, and the hot gas damaged the nozzle throat. And the equipments for attitude control neighboring the nozzle were damaged by the hot gas blew out from the side of the damaged nozzle. After careful review, ISAS and the Space Activity Commission concluded that the fracture of the insert was most likely caused by an embedded or surface crack in the throat insert made of brittle graphite. Because further study came to the conclusion that the performance of up-to-date non-destructive inspection is not enough to surely detect all the detrimental cracks embedded in the graphite billet of the size of this insert, ISAS determined to use inserts made of 3D carbon-carbon composite material. After the redesign and verification by static firing tests, M-V satellite launcher successfully returned to the flight in May 2003, injecting HAYABUSA spacecraft for asteroid sample return mission into a correct orbit.
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OPTICAL, INFRARED, AND MILLIMETER SPACE TELESCOPES, PTS 1-3 5487 1142-1151 2004年 査読有りThe solar optical telescope onboard the Solar-B is aimed to perform a high precision polarization measurements of the solar spectral lines in visible wavelengths to obtain, for the first time, continuous sets of high spatial resolution (similar to0.2arcsec) and high accuracy vector-magnetic-field map of the sun for studying the mechanisms driving the fascinating activity phenomena occurring in the solar atmosphere. The optical telescope assembly (OTA) is a diffraction limited, aplanatic Gregorian telescope with an aperture of phiw500mm. With a collimating lens unit and an active folding mirror, the OTA provides a pointing-stabilized parallel beam to the focal plane package (FPP) with a field of view of about 360x200arcsec. In this paper we identify the key technical issues of OTA for achieving the mission goal and describe the basic concepts in its optical, mechanical and thermal designs. The strategy to verify the in-orbit performance of the telescope is also discussed.
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Proc. 55th Intern. Astronautical Cogress ZARM IAC-04-IAF-V.1.02, 1-7 2004年
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AIAA Journal 41(4) 711-719 2003年4月 査読有り
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54th International Astronautical Congress of the International Astronautical Federation (IAF), the International Academy of Astronautics and the International Institute of Space Law 1 1557-1562 2003年A solar sail is one of propulsion systems for near future interplanetary mission, which uses solar pressure for thrust by reflecting sunlight with very large membrane. We investigate the solar sail as a candidate of engineering test satellite. In order to verify the solar sail design, a deployment experiment is needed, but it is difficult to perform an experiment of large membrane on the ground because of its lower stiffness. To solve this problem, we plan to use a sounding rocket. In this paper we describe our study and plan.
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Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 6 4306-4316 2003年A novel energy-recycling method is studied that enables effective semi-active vibration suppression with piezoelectric transducers embedded or bonded to a structure. In this method, the energy converted from the mechanical energy of a vibrating structure is collected in the capacitor of a piezoelectric transducer as an electric charge, and to suppress vibration, rather than dissipate the energy, the polarity of the charge is changed according to the state of vibration. With this method, no energy is supplied to the total system of the structure and transducers with shunt circuit, which means that the system is stable. A simple electric circuit and a control law for multiple-degree-of-freedom systems with multiple piezoelectric transducers are proposed for this method based on energy recycling. Numerical simulation of vibration suppression of a truss structure shows that this method is more effective in suppressing vibration than both a semi-active method without energy-recycling and that based on the use of an optimally tuned passive system. A preliminary experiment with a truss structure also shows that this method can effectively suppress vibration in an actual structure. However, there was some discrepancy in the experimental results compared to the results of the numerical simulation performed assuming ideal linear characteristics of the piezoelectric transducers estimated from a static test.
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Simultaneous Optimization of Piezoelectric Actuator Placement and Feedback for Vibration SuppressionActa Astronautica 50(6) 335-341 2002年3月 査読有り
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Simultaneous optimization of intelligent structure and feedback gains for flexible structure controlAUTOMATIC CONTROL IN AEROSPACE 2001 471-476 2002年 査読有りA new optimal design methodology is formulated for the placement of piezoelectric actuator and the feedback gains in vibration suppression of flexible structure. For the simultaneously optimal design of the location and sizing of collocated piezoelectric actuator/sensor pairs and the feedback gains, the effect of changes in the mass and the stiffness of the structure by addition of actuator/sensor pairs is considered and combined with control performance index to obtain a composite objective function, and the procedure developed in this paper leads to solutions that are independent of initial conditions of the flexible structure.)Copyright (C) 2001 IFAC.
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Journal of Vibration and Acoustics, Transaction of the ASME 122 412-419 2000年10月 査読有り
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AIAA Journal 38(9) 1736-1741 2000年9月 査読有り2000,
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AIAA Journal, 35(12) 1844-1852 1997年12月 査読有り
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Acta Astronautica 40(11) 771-779 1997年11月 査読有り
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JOURNAL OF SPACECRAFT AND ROCKETS 33(3) 416-421 1996年5月 査読有りA two-dimensionally deployable truss structure is newly proposed for space application, The most significant feature is the small number of mechanisms to be locked when the structure is deployed. its packaging efficiency is shown to be better than that of many known deployable trusses, Several versions of the truss are also proposed. To confirm that the new deployable truss has enough design flexibility, a paraboloidal truss platform is designed fur trial, Furthermore, a numerical investigation shows that the platform is actually deployable and foldable from a practical point of view.
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AIAA JOURNAL 34(2) 355-361 1996年2月 査読有りA semiactive vibration suppression approach Is proposed and investigated. It is to control the damping of viscous dampers installed in structures. By using a single-degree-of-freedom (SDOF) example first, vibration damping is shown to be much enhanced by a suitable variation of the damping of the damper according to the phase of vibration. Next, several types of control logic for this approach are proposed, which are applicable to multiple-degree-of-freedom (MDOF) structures with multiple variable dampers. The performance of these types of control logic are investigated by using an SDOF example and an MDOF truss structure example with three variable damping truss members excited by impulsive and random forces. Numerical investigations demonstrate that the vibration suppression capabilities of most of them are much higher than that of the optimally tuned passive system, keeping the robustness of passive systems.
MISC
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2021年3月第3回観測ロケットシンポジウム（2021年3月24-25日. オンライン開催)著者人数: 14名資料番号: SA6000162017レポート番号: Ⅴ-3
講演・口頭発表等
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33rd International Symposium on Space Technology and Science 2022年3月1日
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2022年10月 - 2023年1月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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2022年8月 - 2022年8月衛星システム設計学特論 (公立大学法人大阪)
共同研究・競争的資金等の研究課題
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日本学術振興会 科学研究費助成事業 2023年4月 - 2027年3月
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日本学術振興会 科学研究費助成事業 基盤研究(C) 2020年4月 - 2023年3月
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日本学術振興会 科学研究費助成事業 基盤研究(C) 2014年4月 - 2018年3月
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日本学術振興会 科学研究費助成事業 基盤研究(B) 2008年 - 2010年
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日本学術振興会 科学研究費助成事業 基盤研究(B) 2007年 - 2008年
