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Yuya Hamamoto, Shintaro Itoh, Kenji Fukuzawa, Hedong Zhang
Article type: Article
Session ID: 3815
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We achieved a viscoelastic measurement of monolayer lubricant films using the fiber wobbling method, which is the highly sensitive shear force measuring method that we have developed. In order to make the measurement possible, we attained the accurate determination of nanometer-sized gap widths between sliding surfaces. In addition, we developed a new method to align the parallelism between the sliding surfaces. We observed the differences in the mechanical responses of sheared lubricant films due to their adsorptivity to the substrate surfaces.
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Jianhua Li, Junguo Xu
Article type: Article
Session ID: 3816
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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To understand the cause of read/write error due to lube accumulation, a model to simulate the slider's response to "soft contact", which can occur between a lubricant droplet on the disk and a slider, was developed. The contact impact model is based on the water-hammer pressure model with an additional damping force, where the wave-shock pressure is assumed to function as the soft contact pressure, and the damping force defines the damping characteristics of the impact which are due to the lubricant's high viscosity. The typical read/write signal modulation due to slider/droplet contact can be described well with the simulated flying height response to soft contact between a lubricant droplet and a slider.
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Jun-ichi ICHIHARA
Article type: Article
Session ID: 3817
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Finite element method has been successful for analyzing the slider air bearing of hard disk drive (HDD). However, recent low flying height and fast linear velocity of disk surface causes the domination of the first-derivative convection term in Reynolds equation. In the case of convection-dominated Reynolds equation, the conventional Galerkin method leads to incomprehensible wiggles or confusing non-convergence. We introduced the upwind finite element scheme, which can overcome the problem described above, to Reynolds equation and evaluated its effect in the low-flying height and fast linear velocity conditions.
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Tooru FUJIMAKI, Takahiro IMAMURA, Jun-ichi ICHIHARA
Article type: Article
Session ID: 3819
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We numerically investigated the touch down and take off characteristics of a head slider with thermal protrusion. Slider vibrations started to occur before the contact force rose up in the touch down process and sustained even after the contact force went out in the take off process. We proposed a slider with the pitch damping step (PDS). We showed that PDS is effective in lowering the touch down and take off heights with improved damping for the second pitch mode resonance of the slider.
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Norio TAGAWA, Jyun-ichi HATAKEYAMA
Article type: Article
Session ID: 3820
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to achieve a magnetic recording density of 1 Tb/in^2, the spacing is expected to be less than 2-3 nm. However, a critical issue in achieving such an ultra-low spacing is the dynamic instability of the head disk interface (HDI).The goal of this research is to clarify the effects of the lubricant materials on slider hysteresis behavior in detail. In this study, the differences in the touchdown and takeoff velocities were monitored by varying the lubricant film materials of the disks. On the other hand, the differences in the force curves by varying the lubricant materials were investigated simultaneously. By comparing the both obtained experimental results, the fundamental mechanism of slider touchdown-takeoff hysterisis instability was studied and discussed.
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Yoshiyuki ISHIHARA, Shinji TAKAKURA
Article type: Article
Session ID: 3821
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this paper, we propose a track-following control system of Hard Disk Drive using variable state-feedback control. The proposed controller varies between two LTI controllers according to frequency characteristics of the position error signal (PES). By the method, we can improve a trade-off of disturbance rejection performance between high-frequency domain and low-frequency domain, and can achieve more accurate track-following than using conventional LTI controllers. The effectiveness of the proposed method is verified by using HDD benchmark problems.
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Yuudai SATO, Akira SAKURADA, Shigeki MORI, Kazuto MIYAWAKI, Akihiro NA ...
Article type: Article
Session ID: 3822
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A highly precise tracking actuator for a magnetic recording evaluation system was developed. The tracking actuator called the Nano-Motion Actuator (NMA) that was consisted of a displacement amplitude mechanism and a layered piezoelectric element (PZT). In this paper, we propose a new X-Y plane positioning actuator called Nano-Motion Stage (NMS) that was composed of one pair of NMA, positioning stage, parallel link, directional spring and so on. And, the control performance and the plane positioning accuracy were verified. As a result of the experiment, the gain crossover frequency of 2.0kHz could be reached, high-speed and highly precise positioning in same X-Y plane could be realized.
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Katsuki OKUYAMA, Hiroyuki KATSUMATA, Hiroshi SHIINO, Takashi ARAKAWA, ...
Article type: Article
Session ID: 3906
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In recent years, several manufacturers have marketed small one or two-seater electric automobiles. We have examined the improvement of ride quality and the reduction of riding fatigue brought about by the active control of the seat suspension of small vehicles such as one-seater electric automobiles. However, the evaluation of ride comfort while the electric vehicle was running has depended on subjective judgement by drivers. Thus, it is necessary to evaluate the correlation of subjective judgement with objective judgement based on physical values. In this study, we performed a sensory evaluation of riding comfort for a small vehicle. In addition, the psychological factors affecting the sensory evaluation value were examined by multivariate analysis using cluster analysis. As a result, we confirmed personality influenced the quality of riding comfort, and the factor of personality that influenced riding comfort was able to be analyzed.
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Takashi ARAKAWA, Hiroshi SHIINO, Shinya HASEGAWA, Yasuo OSHINOYA, Kazu ...
Article type: Article
Session ID: 3907
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A small active seat suspension has been designed and manufactured for a one-seat electric vehicle. Our aim was to develop a vibration-isolation system for the driver's seat suspension using active control. In an actual driving test, a test road, for which the concavity and convexity of an actual road surface were simulated using hard rubber, was prepared. In this study, we have aimed to develop a vibration isolation system with a high robustness for the driver's seat using is-synthesis, which is resistant to factors such as changes in driver's weight. Experiments were carried out under several conditions, and the obtained results were compared with results of simulation. It was verified that the suppression of vibration by the pt-synthesis of the vibration isolation system occurred.
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Yasumichi HINO
Article type: Article
Session ID: 3908
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In Japan, fatal accidents due to crane works occur frequently every year. It is presumed that the main accident cause is "Use of improper tool for cargo work" and "improper choker hitch methods". As for prevention of fall of the cargo, it is thought that the combination of both of "tool for cargo work" and "choker hitch methods" is also important. However, this seems not to be made clear. Thus, one case study, multiple plywood's hoisting with two belt slings, was carried out by an experiment. As a result of this study, the possibility of falling of no unified multiple cargo was presumed when the cargo was hoisted without "protective equipment for prevention of wear of the belt sling".
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Hiroyuki Igawa, Yohei Michitsuji, Masao Nagai, Raksincharoensak Pongsa ...
Article type: Article
Session ID: 3909
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In Japan, approximately 60% of traffic accidents occur in intersections. Thus, the necessity of countermeasures for safety in intersections becomes evident in reducing traffic accident. Especially, it is thought yellow light in signalized intersection is more dangerous because of dilemma. In order to figure out dilemma, two methods have been tried. One method is measured by using fixed point with camera which is put in intersection. The other is measured by using driving simulator. In our research approach, the study of driver behavior from vehicle on real traffic has been conducted by using continuous recording type drive recorders. As a result of analysis of four driver data, characteristic driving maneuver is observed.
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Shoichiro TAKEHARA, Osamu FUKATA, Osamu SHIMOYAMA, Yoshihiro SUDA
Article type: Article
Session ID: 3910
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper is concerned with a quantitative classification based on driver characteristics of steering maneuvers. The evaluation indexes that can be used for quantifying differences of driver groups such as experimental driver or beginner driver are proposed. The slalom test and the crank course test are performed in order to classify the driver's steering maneuvers using the driving simulator that has 6 degrees of freedom motion base and turntable. It is demonstrated in this investigation that the method can be effectively used for classify an important characteristics of driver's steering maneuvers. The proposed evaluation indexes are verified by experimental test with 24 subjects.
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Shoichiro TAKEHARA, Osamu FUKATA, Osamu SHIMOYAMA, Yoshihiro SUDA
Article type: Article
Session ID: 3911
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper is concerned with a quantitative classification based on driver characteristics of steering maneuvers. The evaluation indexes that can be used for quantifying differences of driver groups such as experimental driver or beginner driver are proposed. The experiment using actual car is performed in order to classify the driver's steering maneuvers. The crank course test and handling course test are performed in order to classify the driver's steering maneuvers. Experimental results show the difference of driver characteristics of steering maneuvers on various courses.
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Hideyuki NAKAMURA, Takeshi KAWASAKI, Toshihiko MOCHIDA, Toshiharu MIYA ...
Article type: Article
Session ID: 3912
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to develop a railway car body shell for U.K., static and fatigue strength evaluation based on British standard was carried out. In the result of numerical analysis, generated stress was below allowable stress under static load cases and damage ratio was less than 1 under fatigue load cases. And deformation showed good agreement with that of load test using a real car body shell, so that accuracy of numerical simulation was proven. In the load test, generated stress was below allowable stress. As a result, it is concluded that the car body shell has sufficient strength reliability under static and fatigue load specified in British standard.
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Junya YAMAKAWA, Taizo KOBAYASHI, Yoichiro FUJIWARA
Article type: Article
Session ID: 3913
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This report describes effects of gravity on traveling performance of wheeled rovers for future lunar exploration. A series of wheel travel tests on flatten dry sand were conducted under several gravity conditions in an aircraft with parabolic flight. In addition to the flight experiments, the same tests were performed on the ground with the same wheel vertical load as the aircraft experiments enabled by counterweights. Those experiments showed that traveling performance of the wheel becomes low for less gravity. On the other hand, low wheel vertical load improves the traveling performance under the same gravity condition.
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Kyohsuke SAKUMURA, Ryohei ISHIDA
Article type: Article
Session ID: 4001
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this report, we deal with a design scheme of belt-like film fragments for gas-inflatable structure to generate a paraboloid. First of all, the outline of earlier methods to generate a paraboloid by using gore films is described. A new scheme to design a belt-like film fragments to generate a paraboloid is proposed. To generate the fragments, a paraboloid is cut by parallel planes perpendicular to the base circle. The fragments are produced and the paraboloid is generated by using the fragments.
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Masayoshi MISAWA, Ayako OHARA
Article type: Article
Session ID: 4002
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper deals with a method to obtain frequencies of large structures by component modal tests. This method determines a coordinate that adds mass and stiffness to a tested component. Additional mass and stiffness are found by considering the effect of untested components. Modal test results significantly depend on a coordinate with additional mass and stiffness. In the proposed method, peak frequencies of two masses give key information to select the optimal coordinate. These masses are found by reducing mass matrices of a tested component and a structure to an arbitrary coordinate. This method selects the coordinate so that peak frequencies of two masses are separated from the target frequency of structures. A numerical example is given to show the effectiveness of the method.
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Yoshitaka TATSUMI, Masayoshi MISAWA, Masatoshi KOIKE
Article type: Article
Session ID: 4003
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper describes analysis of joint displacements of cable network which forms surface of mesh antenna for satellite use. The purpose of this study is to accurately estimate joint displacements when external force is applied. In case where large deformation arises in cable network, it is important to consider nonlinearity of joint displacements. We use nonlinear strain to calculate joint displacements. We show numerical results to demonstrate that joint displacements are accurately estimated.
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Yasutaka SATOU, Hiroshi FURUYA
Article type: Article
Session ID: 4004
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Guided-pin mechanisms are proposed to fold two-dimensional large membrane. The large membrane is folded by adding the tensile forces and the displacement with the guided-pin. Finally, the 5,000mm in diameters large membrane is folded with the appropriate location of the guided-pin.
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Takao Okada, Kazuya Kuwayama, Toshiya Nakamura, Motoo Asakawa, Shigeru ...
Article type: Article
Session ID: 4005
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this study, crack propagation tests were conducted to clarify property for the fatigue crack propagation of friction stir welded 2024-T3 aluminum alloy. The welding line of the specimens inclined 0 and 30 degree to direction of applied stress. Results showed that crack propagation rate was accelerated by the tensile residual stress around the welding line. After the crack tip run thought the welding line, the crack propagation rate was accelerated by tensile stress that was caused by the residual stress redistribution during crack propagation. The crack grew perpendicular to the loading direction regardless of the angle of the welding line. And crack propagation rate was not affected by the angel of FSW joint.
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Shunichi KOBAYASHI, Gakuro AKIYAMA, Hideaki MURAYAMA, Kazuro KAGEYAMA, ...
Article type: Article
Session ID: 4006
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Structural health monitoring (SHM) is an important technology for the next generation aerospace vehicles. The key issue is to determine the operational stress in real time which enables us to manage the structural integrity and air-worthiness. In our previous work, we reported a technique to identify distributed load, such as the aerodynamic load, using real time data provided by strain sensors. This technique is based on an inverse interpolation method using results from a Finite Element Model (FEM) analysis. In this work, features of this method and its behavior of solutions on the error in strain measurement were characterized by simulations based on FEM. In addition, the applicability to plate structures was verified by experiments.
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Koichi Takasaki
Article type: Article
Session ID: 4007
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper presents a thermal p-version multidimensional finite element for ablative materials which can be applied to the simple thermal structural analysis of an atmospheric re-entry vehicle's ablative thermal protection system. As with a general thermal shell element, a user of this element can set the initial thickness of the virgin layer as a parameter instead of by coordinates, allowing parametric studies to be easily conducted. The element can be laminated with other general thermal element models.
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Takeshi TAKATOYA, Hisashi KUMAZAWA, Yutaka SATO
Article type: Article
Session ID: 4008
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to evaluate thermal behaviors of the composite materials for usage to nozzles of solid rocket motor and thermal protection system of re-entry space vehicle, a high power diode laser module system, with two scanning mirrors, was developed for high heat source. As direct measuring of heat flux of laser heating is not effective, a weight loss measurement of PMMA plate method was proposed and evaluated. The scanning patterns of mirrors with galvanometric type scanner were characterized for a uniform heating capability.
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Masahisa HONDA, Takuya MIZUNO
Article type: Article
Session ID: 4009
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper reviews the designs and developments of the recovery system of the experimental airplane called NEXST-1. Since the airplane doesn't have landing gears, the recovery system is utilized for soft landing. The system comprises a pilotchute, a droguechute, three clustered mainchutes and two airbags. In the terminal phase of the experimental flight, the airplane with three mainchutes falls at about 6m/s in a horizontal posture. The landing impact is attenuated by two airbags. In this paper, the results of the development tests and the experimental flight are discussed.
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Kazuhiko YAMADA, Daisuke AKITA, Takashi ABE, Kojiro SUZUKI, Masashi KO ...
Article type: Article
Session ID: 4010
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A Low-ballistic-coefficient atmospheric-entry technology using a flexible aeroshell is promising for a space transportation system in next generation because it can reduce the maximum aerodynamic heating during a re-entry and the terminal velocity dramatically. Its technology will lead to realize a safer, cheaper and more universal space transportation system. Our group has researched various important subjects in order to apply the flexible aeroshell to actual atmospheric-entry missions. In this paper, the innovative re-entry system from LEO which was defined as the nominal mission by our group is introduced and our current research and development are reported.
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Osamu Imamura, Yoshiki Takama, Masashi Koyama, Kojiro Suzuki, Daisuke ...
Article type: Article
Session ID: 4011
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The development of the airtight and heat-resistant membrane is an important factor to realize the low ballistic coefficient reentry spacecraft with flexible aeroshell. The air tightness is necessary for the inflatable structure and the heat-resistance against aerodynamic heating is also demanded. The candidate of the membrane is Zylon[○!R] (Toyobo. Co. Ltd.) and it can endure more than 600 degree Celsius. Authors tried to give Zylon airtight property with coating on it, but the coated sample was not airtight. If polyethylene is used as an inside layer of Zylon, the two layers system have the airtight property. As outer layer should be a heat shield in this case, radiative heat transmission test of membrane is also tested. Thicker Zylon and Zyron with Kapton[○!R] film show less transmission rate than Zylon.
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Hideyuki TANNO, Tomoyuki KOMURO, Kazuo SATO, Katsuhiro ITOH, Tetsuya Y ...
Article type: Article
Session ID: 4012
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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An aerodynamic force measurement technique was applied on the drag force measurement of the aeroshell re-entry configuration with decelerons. In the present technique, aerodynamic force was obtained as products of measured acceleration and mass of the model, which was weakly suspended with thin wires. The unsteady drag force of 230mm length aeroshell model was measured under high enthalpy condition of H_0=4MJ/kg, 12MJ/kg and 20MJ/kg in the free-piston shock tunnel HIEST. Pressure distribution and heat flux distribution around the model were also measured to obtain validation data for numerical simulations. With the present model, natural vibration which often disturbs precise measurement, was sufficiently low.
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Tetsuya YAMADA, Hideyuki Tan'no
Article type: Article
Session ID: 4013
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Reentry flight with super-orbital directly from lunar transfer orbit is investigated here taking account of the safety of the crues even in case of contingency. Issues associated with atmospheric flight under constraints of recovery and flight environment relaxation are addressed and summarized here.
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Kazuhisa FUJITA
Article type: Article
Session ID: 4014
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Preliminary assessment of the planetary aerocapture system is made for a Venus balloon explorer as a reference mission, paying particular attention to aerodynamic characteristics of the vehicle along the flight trajectory. A drag alternation system using retractable decelerons added to the primary aeroshell is examined to broaden a window of successful orbit insertion. Aerodynamic coefficients of the vehicle with and without decelerons in rarefied, transitive, and continuum flows are estimated, and six-degree-of-freedom dynamics of the vehicle is computed along the flight trajectory. The results show that the aerocapture system using the retractable decelerons has a potentiality of considerable mass reduction in comparison to the conventional propulsive system for Venusian orbit insertion.
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Toshiyuki Suzuki, Kazuhisa Fujita, Satoshi Nonaka, Yoshifumi Inatani
Article type: Article
Session ID: 4015
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Computations of unsteady flowfield around the rocket vehicle is performed by using Large Eddy Simulations. The method is applied to the flight environment of Reusable Vehicle Testing with jet ejection. The interaction between freestream and the opposing jet from the vehicle is calculated by varying the angle of attack. Temporal variations of surface pressure acting on the vehicle are obtained. It is found from the calculated results that the frequency of pressure fluctuation for the RVT flight environment becomes shorter than that for the wind tunnel condition by a factor of 10 due to the scale effect.
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Daisuke Akita, Kazuhiko Yamada, Takashi Abe, Masashi Koyama, Osamu Ima ...
Article type: Article
Session ID: 4016
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A low ballistic coefficient vehicle can drastically reduce peak aerodynamic heating during atmospheric entry. We are developing the new atmospheric entry system using an inflatable flexible aeroshell. A fight test of the system, which is aiming to verify the design method of the inflatable flexible aeroshell, is planned for late August, FY2008. The flight test is performed by stratospheric balloon-drop from altitude of about 30 km. In this paper, the system configuration and the operation sequence of this experiment system are overviewed.
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Hajime KONDO, Koju HIRAKI, Masanobu INOUE, Koichiro KAWAZOE
Article type: Article
Session ID: 4017
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The purpose of this study was to demonstrate the self-returning capability from high altitude using amateur rocket. A flier for the rocket experiment was designed with the aid of CATIA and examined by each test. The approach to the destination was divided into 2 phases (approach phase from high altitude and final phase to return to the destination). The flight strategy as approach phase was evaluated by estimations. As a result, flight method was determined and the present parafoil was developed. The deployment sequence using the balloon at an altitude of 30[m] was performed. Final phase navigation system near the target was developed and validated by the flight from over an altitude of 100[m]. The proper functions of the system were confirmed.
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Hiroyuki HOUZU, Norio ARAI, Yoko TAKAKURA
Article type: Article
Session ID: 4018
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this article, dynamics characteristics of a round canopy after inflation process is focused. To clarify the phenomenon, the water tunnel experiment is executed. Parachute models are set in a vertical water tunnel which is driven by Siphon's low. Here, the uniform flow direction is opposed to the gravity direction in order to simulate the real parachute vertical drop. Three types of parachute models are set to clarify the oscillation pattern and two types of supporting systems are applied to investigate the effects of the payload motion. The displacement of the object is measured by using CCD camera motion analyzer. According to the results, the oscillation pattern of the parachute models change by time, those are linear, arc, and circular motions. There are differences about degree of freedom of payload between four type tests.
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Koju HIRAKI, Kiyoho MATSUSHIMA, Takashi NAKADA, Shujiro SAWAI, Kazuhis ...
Article type: Article
Session ID: 4019
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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To achieve the medium-duration and good-quality micro-gravity environment, an experimental system by the free-fall capsule from a high-altitude balloon was developed in JAXA, and it was successfully tested at Sanriku Balloon Center. In order to decelerate from supersonic speeds the three-stage parachute system was employed in the system. It worked properly, though the mainchute caused the pendulum motions with a relatively large amplitude.
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Shin-Ichiro NISHIDA, [in Japanese], [in Japanese]
Article type: Article
Session ID: 4020
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The mobility and control of driving at a mountainous terrain has been one of the main technical issues by the exploration rover. In this paper, navigation and control methods using motion stereo image sensing for a lunar rover are discussed, and the testing results using the method are also described.
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Koki FUJITA, Shinji HOKAMOTO
Article type: Article
Session ID: 4021
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper proposes a simultaneous estimation method for planetary lander's motion parameters and 3-D locations of the scene points on planetary surface using CCD camera and scanning range sensor. First, the relationship between the lander's motion and the scene points' motion in camera and range image sequence is derived, and described as a couple of state and observation equations. Secondly, an estimation scheme utilizing two Extended Kalman Filter (EKF) algorithms is derived for the lnader's 6DOF motion parameters and the scene points' 3D locations. Finally, the effectiveness of the proposed method is demonstrated through numerical simulation.
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Takahide Mizuno, Seisuke Fukuda, Tomohiko Sakai, Teppei Sato, Kenji Ki ...
Article type: Article
Session ID: 4022
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The Institute of Space and Astronautical Science JAXA is developing a landing radar comprising a radio altimeter and a velocity meter, which are two of the mandatory navigation sensors for a planetary lander. A BBM of the landing radar has been evaluated on natural terrains by using a helicopter. This paper introduces the BBM hardware and discusses the dynamic performance in field experiments.
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Yasuhiro KAJIKAWA, Takuya HAYASHI, Makoto MITA, Norihide TAKEYAMA, Tak ...
Article type: Article
Session ID: 4023
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This study proposed an optical scanning system with a MEMS (Micro Electro Mechanical System) technology of a 2D scanning LIDAR for planetary exploration. The transmitting of the 2D scanning LIDAR has a MEMS mirror that driven two axes. The receiver optics has many narrow field of views (FOV) in the scanning angle of φ10°. We introduce the summary of the scanning optics for transmitting and the result of driving experiment in a vacuum condition.
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Tsutomu ICHIKAWA
Article type: Article
Session ID: 4024
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper describe the results of an investigation of the expected navigation ( Orbit estimation ) accuracy during the approach phase of a planet orbiter mission. The target planet is "Venus". This expected accuracy was determined for Earth-based Doppler observation data with the addition of ranging or on-bord optical observation data or Delta-VLBI data. In this paper, we describet he sensitivity of this expected accuracy to errors effecting Delta-VLBI data and optical data also was examined. It was found that unless planetary ephemerisis errors are reduced below their anticipated levels, the addition of ranging data does not significantly improve the estimate of the spacecraft's state near encounter.
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Isao Kawano, Shinji Mitani, Toru Yamamoto, Yoshiyuki Ishijima, Yoshino ...
Article type: Article
Session ID: 4025
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Formation Flying (FF) is a technology that several satellites fly keeping a specific relative position one another. The technology breaks through constraint of dimension of satellites, and enables various missions such as X-ray telescope, infrared interferometer, SAR interferometer, gravity wave detection etc. To realize the missions, high accurate formation flying technology such as navigation and control of relative position and velocity among related spacecraft is necessary. We will develop the FF technology based on ETS-VII which performed in-orbit demonstration of autonomous rendezvous docking (RVD) technology and during three RVD experiment flights flew keeping definite ranges time and again. In this paper we present the FF research and development plan in JAXA, including in-orbit demonstration plan.
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Tsuguo IMAIZUMI, Fuyuto TERUI
Article type: Article
Session ID: 4026
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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For capturing uncooperative objects in space, such as failed satellites and asteroids ("targets"), a space robot ("pursuer") must perform six degrees-of-freedom (position and attitude) maneuvers around the target. This requires measurement/estimation of the target's relative motion as information to the controller. In this paper, a strategy for the approach to the target and subsequent proximity maneuver is proposed as a feedforward control phase (phase 1) followed by a feedback control phase (phase 2). In phase 1, the target's future attitude is predicted from the result of motion estimation using image data, and this result is used by the pursuer's motion controller to determine a destination position and attitude. A feedforward optimal control algorithm using the predicted destination that is suitable for real-time application is developed. In phase 2, feedback control such as Sliding Mode Control is used. The feasibility of the proposed control algorithms is investigated through numerical simulation.
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Shujiro SAWAI, Tatsuaki HASHIMOTO, Hirofumi KAWAI, Seiya UENO
Article type: Article
Session ID: 4027
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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JAXA is developing the balloon-based operation vehicle as a new one of the micro-gravity experimental devices. The vehicle makes relative micro-gravity environment inside the body by free-fall from the stratosphere with the balloon. Now, the vehicle is carried above the sea with balloon and falls straight. Therefore, there is the serious problem that the airflow dominate a go or no-go decision of the experiment. To solve this problem, the optimal control law that maneuver the vehicle to pull-up to fly horizontally after the free-fall and then guides over the sea will be designed. This paper discussed about the difference of the maximum horizontal distance on the timing of pull-up.
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Ikumi MATSUDA, Keita HATASA, Seiya UENO
Article type: Article
Session ID: 4028
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The concepts of solar sail have been proposed for a long time. Solar sail is a propulsion system that changes the sunlight into the thrust of the spaceship. Because solar sail doesn't need fuel consumption and it is very lightweight, it attracts attention widely and some studies have been done. In this study, earth circular trajectories are considered and the number of circulars is used as an independent variable for improving the accuracy of optimization calculation. To be concrete, the issue of the satellite injection into the geostationary orbit is discussed. By using optimal transfer trajectories that maximize semimajor axis in one revolution, a new effective injection method was proposed
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Yoji SHIRASAWA, Fuminori HANAOKA, Yuichi TSUDA, Osamu MORI, Ryu FUNASE ...
Article type: Article
Session ID: 4029
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper describes the attitude dynamics of spacecraft with large flexible structure, such as huge antenna or membrane of solar sail. The coupled motion of the rigid spacecrafts with the flexible structure is complicated, and it is important to predict the motion for the design of configuration or operation planning. It requires a lot of time to calculate the motion of the flexible structure by numerical simulation, and the analysis using simple model is important for exhaustive validation. In this study, a simplified model of the attitude dynamics considering the first vibration mode of flexible structure is introduced. Using this model, the vibration mode of the attitude motion of spacecraft is analyzed. The result of the analysis is confirmed with numerical simulation and compared with the result obtained by use of proven model.
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Tatsuya Endo, Hiroshi Kawai
Article type: Article
Session ID: 4030
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The problem of the attitude control of a recent artificial space satellite is subdivided by the mission of the satellite. The actuator for the attitude control have not changed. The Wheel and the Thruster are basically used. The control demand from the mission has changed into high accuracy and high performance. In this text, the malfunction satellite control problem was introduces.
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Takehiro HIGUCHI
Article type: Article
Session ID: 4031
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Position and attitude of under-actuated satellites is difficult to control because of their unique system called the non-holonomic systems. One of the ways to control the non-holonomic system is to use the holonomy that appears when the periodic input is given to the non-holonomic systems. In this study, the attitude and position of underactuated satellite is controlled using the holonomy. The satellite used in this study is simplified 2-dimensional model with only thrusters to change positions and attitude angle. Various pattern of periodic input gives the different holonomy to the system. In this paper, the input patterns of the holonomy are examined by the numerical optimization to see the effectiveness of the control theory.
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Seiya UENO, Megumi NAMAI
Article type: Article
Session ID: 4032
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Control moment gyro (CMG) generates higher torque than common reaction wheel. Thus it is focused on mounting CMGs on future satellites for agile maneuver of attitude. This paper discusses on the minimum time maneuver. The authors have been studying on optimal maneuver of satellites actuated by CMGs as application of optimal control theory. According to optimal control theory, bang-bang control is optimal in most cases. Intermediate input is call as singular input. The author pointed out that singular inputs are necessary for minimum time maneuver in some cases. This paper discussed on the optimum maneuver of a malfunctioned satellite. The results show that singular input is used in optimal maneuvers when one gimbal of CMGs does not work.
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Hiroki ASHIDA, Junichi NISHIDA, Kota FUJIHASHI, Shinichi INAGAWA, Yosh ...
Article type: Article
Session ID: 4033
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Pico-satellite "Cute-1.7 + APD II" was developed at Tokyo Institute of Technology, Laboratory for Space Systems (LSS), which have developed and launched 3 pico-satellites called CubeSat. Cute-1.7 + APD II is a modified version of Cute-1.7 + APD and is planned to finish all the missions which could not be finished in it. Several improvements were added and evaluation tests have conducted for the satellite in order to make it completely work well in orbit. Cute-1.7 + APD II was successfully launched on April 28, 2008 by Indian PSLV (Polar Satellite Launch Vehicle) with 9 satellites. This paper will briefly explain these improvements and result of launch and initial operation.
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Akito ENOKUCHI, Shinichi Nakasuka
Article type: Article
Session ID: 4034
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Today, space telescopes with flexible structure have been proposed and some of them are ready to be demonstrated in orbit. A serious problem in the imaging system with such a telescope is its bending vibration, inevitably caused by satellite attitude control. This paper proposes a method to compensate vibration of the satellite overall, using only images taken by the telescope. To extend the dynamic range of sensing vibration, the state estimator we propose uses not only image shift information from successive images, but also motion blur information from each image.
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Il-Yun YOO, Yuuki SATO, Casey LAMBERT, Shinichi NAKASUKA
Article type: Article
Session ID: 4035
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Nano-satellite PRISM is being developed at the Intelligence Space System Lab at University of Tokyo. The objective of PRISM mission is to observe earth with 30m resolution. Thus, a novel design of fabricated optics system with the extendable boom structure is required to attain longer focal length. For the purpose of attitude control of PRISM, we need to understand dynamics of the deployable boom, and vibration experiment under micro-gravity was conducted during parabolic flight tests at Nagoya, Japan. Input and output datum of transverse motions of the boom structure under gravity and micro-gravity was measured, and using this datum we report identification of the extendable boom system.
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