Transactions of the Japan Society of Mechanical Engineers Series C
Online ISSN : 1884-8354
Print ISSN : 0387-5024
Volume 66, Issue 650
Displaying 1-41 of 41 articles from this issue
  • Toshihiko HORIUCHI, Takao KONNO
    2000 Volume 66 Issue 650 Pages 3225-3232
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    We developed an on-line experimental system for conducting hybrid experiments in real time that combine a computer conducting vibration simulation and generation of control-signal, and an actuator conducting a vibration experiment driven by the control signal. This system compensates for actuator delay, which enables experiments to be carried out in real time. For the real-time hybrid experiments, however, a large time step for simulation is required when the number of degrees of freedom of numerical model is large. On the other hand, a smaller time step for generating the control signal is desirable to improve the accuracy of the experiments. To solve this problem, we propose a new method for generating the control signal. The method is divided into two parts, a simulation part for simulating vibration response, and a control part for generating a control signal. The time step of the control part is set to be smaller than that of the simulation part. The control part calculates the control signal smooth enough for the compensation so that the actuator is driven as calculated at the time when the calculated value is provided. In addition, the validity of this method is verified by experiments.
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  • Yutaka YOSHITAKE, Atsuo SUEOKA, Akizumi FUKUSHIMA, Katsuya YAMAWAKI, H ...
    2000 Volume 66 Issue 650 Pages 3233-3241
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    This paper deals with the vibration control device that simultaneously generates electricity by using absorbed vibration energy. This device is composed of a generator and a Hula-Hoop that is fixed on the shaft of the generator. As the conditions which have some effect on the vibration control performance and electric power, power of D.C. motor that is the substitute of generator, weight of Hula-Hoop, distance between the center of rotation and center of gravity, external frequency, and initial condition are examined. As a result, the followings were made clear. (1)Hula-Hoop rotates synchronously with the vibration of main system. (2)The resonance amplitude of main system is quenched up to about 1/3 and D.C. motor generates electricity as generator. (3)Appropriate weight of Hula-Hoop and initial condition are necessary to rotate Hula-Hoop, control vibration and generate electricity. (4)Generating electric power is proportional to the second power of external frequency. The experimental and the anlytical results were in good qualitative agreement with each other.
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  • Tetsuro TOKOYODA, Teruki KIDO, Kazushige SATO, Masatsugu YOSHIZAWA
    2000 Volume 66 Issue 650 Pages 3242-3249
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    The concept of modal analysis is well developed for linear systems. However, we are not aware of the way of dealing with nonlinear dynamical problems along this method. The basic idea underlying the method of normal forms is the use of local coordinate transformations so that the dynamical system can take the "simplest form". For nonlinear systems, the coordinate transformation will generally be nonlinear. This technique is demanded for us to find application in engineering, but most of the previous works on normal forms deal exclusively with simple dynamical systems such as autonomous systems. In this paper, we examine more practical systems. As an example of these systems we give an elastic mounting of four-stroke engine for marine use at low speed ; consequently we consider the problem of an elastically mounted rigid body having three degrees of freedom which can include a rotating oscillator.
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  • Kazuyuki YAMAGUCHI, Hiroshi ISHII, Yasuhiro KATOH
    2000 Volume 66 Issue 650 Pages 3250-3257
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    The characteristics of dynamic pressure and blade vibration during rotating stall are summarized by tests of a 17-stage compressor, and a simple analytical method for evaluating fluid exciting force and predicting blade vibration stress in presented. The blade exciting force model is derived by using the unstable characteristics of compressors. The blade vibration stress is numerically simulated and compared with the measured stress. The results can be summarized as follows. First, the simulated time history of blade vibration agrees well with the measured one. Second, in resonance where the natural frequency of blade vibration coincides with multiples of the exciting frequency of rotating stall, the amplitude of blade vibration becomes about two times larger than that except resonance, even if the multiples are five to seven. Third, the change in stall cell width causes the change in blade vibration amplitude.
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  • Peng CHEN, Fang FENG, Toshio TOYOTA, Xinfang LIU, Hiroshi SHIMAZU, Tat ...
    2000 Volume 66 Issue 650 Pages 3258-3263
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    Gear drive is one of important parts on plant machinery. However, up to now, the method of failure diagnosis of gear drive has not been clarified theoretically, and the condition monitoring of gear drive has been carried out mainly by statistical way and experience. So the main problems are : (1)the failure signal is hardly extracted from measured signal for early diagnoisis, (2)the failure type can not been easily recognized. In onder to overcome the difficulties, in this study we develop the diagnosis theory for gear drive by clarifying the change of dynamic characteristics between normal and abnormal states, and using theories of signal processing, fuzzy and neural network etc. In the 1st report, we point out the problems of the traditional diagnosis method using only the dynamic model of normal state, and clarify the dynamic characteristics on failure gears by the locus analysis of the meshing contact point, and show the results of analysis and experiment on eccentric gear to verify the efficiency of the method proposed in this paper.
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  • Tadao KAWAI, Masami ITO, Hisanori OKURA
    2000 Volume 66 Issue 650 Pages 3264-3269
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    In this paper, we intend to identify the density of a small element of a film. The interference fringes on the film were measured by a CCD camera and were processed to estimate the deflection of the film. Then, the density distribution was identified. Because the gray level quantization and the resolution of the CCD degraded the accuracy of the estimated deflection and the identified density, we reduced the noise in the image data by the Wavelet denoising technique. Also, since the identification process was very sensitive to the noise, we applied the Tikhonov regularization technique to regulate the identification process. Finally, the Tikhonov regularization technique gave the precise density distribution by using well denoised image data.
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  • Kazuhide OHTA, Yoshihiko IRIE, Iwao HONDA, Keiichi KATAYAMA, Toshiki M ...
    2000 Volume 66 Issue 650 Pages 3270-3276
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    This paper presents the theoretical method to evaluate the amplitude of flow-induced acoustic resonance of tube banks in the heat exchanger. This method, based on the forced oscillation model, employs the acoustic characteristics of the chamber containing tube banks and vortex-induced exciting forces with particular Strouhal number which changes with pitch to diameter ratio of tube array. Experimental results on acoustic resonance in transverse and flow direction agree well with the calculated results. Furthermore, the availability of the sound absorbing materials and the baffle plate with clearanceto reduce the acoustic resonance are discussed.
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  • Ryuichi TANIMOTO, Hideyuki HAYASI, Moriyuki IMAI
    2000 Volume 66 Issue 650 Pages 3277-3282
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    To reduce noises in vehicles, various means such as (1) improvement of engine-driving system, (2) reinforcement of body-frames, (3) increase of floor-panel's sound-insulation, and (4) increase of interior sound absorption are adopted. In this paper, we consider increase of interior sound absorption to reduce noises in a one-box-car. For this purpose, we first examine the contribution of the interior trim materials to the absorption. We find that the trim materials on the seats have the greatest contribution than those on the other interior parts. We then examine the effects of the seat-cover mocket covering the seat made of urethane-foam. We find that the mocket decreases the absorption. To compensate this decrease, we attempt to develop a new type of mocket. We finally ascertain that using this type of mocket in fact reduces noises.
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  • Akira SADAMOTO, Yasuji TSUBAKISHITA, Yoshinori MURAKAMI
    2000 Volume 66 Issue 650 Pages 3283-3288
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    A slit, which is a duct expansion with very short axial length, acts as a resonator muffler with resonant frequency almost depended on the slit depth. Hence, using some slits with different diameter one another, placed side by side in the axial direction, it is expected that the superposed effect of each slit is obtained. In this study, transmission coefficients of such slits were measured with various slit's size and with the plane wave or the (1, 1) mode wave incidence. Also the structures of sound fields in a duct with such slits were numerically analyzed with the finite differece method. As a general result, superposed effects were obtained, but in the case that each slit's reasonance effect was strong and each resonant frequency was close to some extent, interaction between one and next slit occurred. In this case, effective frequency range on sound attenuation became somewhat narrow, but attenuation effect was enough strong in this range. As the case may be, such slits seem to be useful as a sound attenuator.
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  • Michihiro KAWANISHI, Hiroshi KANKI, Koji EDO
    2000 Volume 66 Issue 650 Pages 3289-3296
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    This paper describes an active jiggle control of hung structure using a control moment gyro (CMG) which has two gimbals for one flywheel. The double gimbal CMG enables us to simultaneously control the vibrations for two different dirctions by only one flywheel. Due to the nonlinearlity and interference, it is however difficult to construct the control system for the double gimbal CMG. First, we propose a simple control system design method for the double gimbal CMG based on H2 optimal control theory. In order to improve the gimbal stability, which is necessary for avoiding the interference, we then propose an another design method based on H2/H control using LMI optimization. The performance of all designed control system are evaluated by simulations and experiments.
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  • Bunta OKAMOTO, Kazuo YOSHIDA
    2000 Volume 66 Issue 650 Pages 3297-3304
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The design of suspension very important for ride-comfort and driving stability of automobiles. A lot of active and semi-active suspensions have been studied. In recent years, the cars with active or semi-active suspension have been put into practice. Since an active suspension needs large power and space, a semi-active suspension have recently received attention because of less power consumption. In this study, the bilinear disturbance accommodating optimal control method is established and it is applied to the semi-active control of suspension for automobiles. A half car body model with 4-DOF is used in order to examine the performance of this mothod. In this model, bounce, pitch and hop mode are considered. In the simulation, performance of the proposed bilinear disturbance accommodating optimal control to the semi-active suspension is examined by comparing it with passive control, skyhook control and Karnopp's control method. As a result, the proposed method showed better performance for ride-comfort and driving stability than the other control methods.
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  • Joe IMAE, Kazuhiro INOUE
    2000 Volume 66 Issue 650 Pages 3305-3312
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    In this paper, we deal with non-standard optimal control problems, where the performance index and/or the right hand side of the state equation can be non-differentiable. Such non-standard problems are extremely difficult to solve numerically, because the solution of the state equation may escape to the infinity. Based on the continuation methods, we present two computational methods for obtaining the solutions of the non-standard optimal control problems. One is to approximate non-differentiable functions by differentiable ones, and the other is to adjust the control-time-interval so that the resulting control problems can be solvable. Moreover, we demonstrate the effectiveness of those two methods by numerical simulations.
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  • Kengo INOUE, Nobuyuki KOBAYASHI
    2000 Volume 66 Issue 650 Pages 3313-3319
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    A reduced order output feedback control algorithm based on a low order modeling methodology for suppressing the vibration and obtaining the high speed, high precision positioning of flexible robot arm is proposed and discussed. The proposed low order modeling methodology gives no modal truncation error and makes it possible to vary the mode shapes of the link according to the change of the boundary conditions due to the feedback gains and the payload at the tip of the arm. Furthermore, this methodology can take into account not only the flexibility of links but also the flexibility of joints. The reduced order output feedback control algorithm is designed by the combination of sliding mode controller and suboptimal output feedback controller so as to achieve both the damping of the system vibration and the stabilization at the same time. The results of numerical simulation and of experiment for a two-link robot arm model are compared. And they prove that the proposed modeling methodology is able to describe the dynamic behaviors of the arm, and the controller designed applying the suboptimal output feedback sliding mode control is able to control the arm quite well.
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  • Noriyasu MASUMOTO, Hiroshi YAMAKAWA
    2000 Volume 66 Issue 650 Pages 3320-3327
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    When we want to determine control forces using predicted disturbance values near future, the number of predicted values, in other words the limit of prediction, and the form of control force function composed of the predicted values need to be determined. In this paper, the authors define the limit of prediction considering control as the forward horizon, and the limit of reference toward the past to calculate predicted values as the backward horizon. The methods to determine the forward and the backward horizons, to calculate several predicted disturbances near future and to determine control forces using the predicted values are presented. The predictive control method proposed in ths paper is applied to a numerical example of a suspension model for vehicles with two degrees of freedom. The results show that the forward and the backward horizons are determined clearly and that the forward horizon is very effective to the progress of the control performance.
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  • Makoto SAMESHIMA, Satoshi FUJII, Atsuo SUEOKA
    2000 Volume 66 Issue 650 Pages 3328-3335
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    We have developed a digging controller using fuzzy logic in order to automate digging work using a hydraulic excavator. The controller has a group of boom and bucket control rules according to digging and dipping areas. Boom control rules will maintain stick pressure to the target value. Bucket control rules will operate according to stick and bucket velocitis. And we present an auto tuning function for boom control rules. In this paper, we describe the control details of the digging controller, test results obtained from field machinery, and results of comparison and evaluation of the auto digging with the digging by skilled operators. The use of the controller showed that the automatic digging performance would be able to be realized to be the same as skilled operators in the various soil conditions.
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  • Hiroshi TACHIYA, Seiji KANENO
    2000 Volume 66 Issue 650 Pages 3336-3343
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    This paper presents a new tactile sensors with multi artificial whiskers, which mimic whiskers of animals. The proposed sensor will distinguish the types and detect the attitudes or positions of contact objects from the condition of the deflection direction of each whisker that contacts objects. The sensor consists of plural sensing elements, each of which has a flexible whisker made of Ti-Ni alloy. The whisker is equipped with a plane synthetic rubber board. The recognition by the proposed tactile sensor is performed in the following two steps. First, the sensor will recognize the deflection direction of each whisker by the deformation of the synthetic rubber board. Next, it recognizes the atttitude or position of a contact object with its type from the combination of the deflection direction of each whisker. Both the recognitions were made by the neural network. The presents study examines the ways of the constructions of each neural network for the respective recognition steps, and confirms the effectiveness of constructed each neural network by the experiments and numerical simulations. Furthermore, the experiments verify the validity of the proposed tactile sensor.
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  • Masahiro OHKA, Isamu HIGASHIOKA, Hisanori KABESHITA, Yasunaga MITSUYA
    2000 Volume 66 Issue 650 Pages 3344-3351
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    This paper described a micro optical three-axis tactile sensor capable of sensing not only vertical force but also horizontal force. The vertical force was detected from the integrated gray scale values of bright pixel emitted from the contact area of conical feelers. The conical feelers were formed on the rubber sheet surface keeping contact with an optical waveguide plate. The horizontal force was detected from the horizontal displacement of the conical feelers. In the experiments, a precise multi-axial loading machine was developed to measure sensing characteristics of the present sensor. It was found that the vertical force was specified uniquely under combined force conditions and that the horizontal force was specified by modifying the relationship between the horizontal force and the horizontal displacement on the basis of vertical force. From the experimental results calibration coefficients were identified to transform the integrated of gray scale values into vertical force and to transform the horizontal displacement into the horizontal force.
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  • Hiroshi FUJIMOTO, Tomohiro KIDUKA, Yoshiteru YOKOJI, Takashi YOKOI, Ha ...
    2000 Volume 66 Issue 650 Pages 3352-3358
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    This paper deals with a measuring system and the results of the analysis for the motions such as standing up and sitting down under assistance by a skilled physical therapist (PT). This measuring system is developed to evaluate the efficiency of assistance quantitatively, and is composed of the following two subsystems. One is for the position data of the each lower limbs' joints measured by the optical camera, and the another is for the force vectors acting on the lower limbs measured by the force plates and multi axes force-moment sensor. The experiments with a sound person as a subject assisted by a skilled PT are performed. With these data, the inverse dynamics analysis is done, and the following results are obtained. The torque and power which should be generated on each lower limbs joints of the subject are reduced, when he is assisted by the PT. Especially in the hip joint, the ratio of reduction is remarkable.
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  • Hideo FUJIMOTO, Lian-yi CHEN, Naoki MIZUNO, Kotaro SHIMA, Koji TAMAKOS ...
    2000 Volume 66 Issue 650 Pages 3359-3365
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    In this paper, a method of trace recognition in sign language learning system using virtual reality technology is suggested. Conventionally, if the 3D trace data of sign language with individual difference are to be treated directly, long time is required in the learning process because of the large amount of data. To solve the problem, a method capable of mapping the 3D traces of sign language into the 2D traces is suggested based on the characteristics of the traces, and a convenient method on the trace recognition with individual difference is developed. The effectiveness of the proposed method is confirmed from the result of the trace recognition experiment using neural network.
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  • Tomonori YAMAMOTO, Satoru SHIBATA, Mitsuru JINDAI, Akira SHIMIZU
    2000 Volume 66 Issue 650 Pages 3366-3372
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    For the coexistence of human and robots, it is important for robots to have not only a physical safe but also a psychological safe. When we consider avoidance motion of robots from an unexpected human approach, it is necessary for robots to have comfortable motion that can ease a psychological burden. In this research, we adopt a control strategy in which a robot follows human motion at an interval of desirable distance in front of the human firstly. Next, we evaluate human emotions to the avoidance motion of the robot that follows the strategy using SD method. The results of SD method show that the adopted control strategy is excellent when the distance and motion speed of given task are appropriate simultaneously, and that human emotions to the avoidance motion are represented by the factors of "speed" and "agreeability".
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  • Yasuhisa HASEGAWA, Kenichiro MASE, Toshio FUKUDA
    2000 Volume 66 Issue 650 Pages 3373-3379
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The control of multi-fingered robot hands has been the subject of recent interest. To manipulate some object with rerasping motion, there are many parameters to be determined ; the grasping points, grasping forces, regrasping phases, finger allocation and so on. It is difficult to optimize such manipulation parameters for achieving effective manipulation. In this paper, we propose a generation algorithm of regrasping motion for a four-fingered robot hand using Evolutionary Programming (EP). Evolutionary optimization method is generally able to find optimal solutions without supervisor after much iteration, which makes it almost impractical to apply a real robot in online learning process. Therefore we apply the controller generated in numerical simulations to the real robot hand. We show effectiveness of the proposed generation algorithm for the regrasping motion with experimental results.
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  • Mitsumasa Yoda, Yasuhito Shiota
    2000 Volume 66 Issue 650 Pages 3380-3387
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The purpose of this study was to construct the passing motion algorithm of a mobile robot for a man using subjective evaluation. In order to decide scales to be used in experiments, twenty-nine pairs of adjectives, which related to humanfriendly robot motion, was classified into familiarity, activity and reliability factors using factor analysis. Then a mobilerobot, which referred to a transfer robot in a hospital, was manufactured for experiments. The robot had a distance-measuring system using ultrasonic sensors. Seven parameters of human passing motion were examined in the experiments between man and the robot using subjective evaluation scales. The passing motion algorithm of a robot for a man was constructed by synthesizing the results of evaluations.
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  • Naoki KAWAI, Fumio HARA
    2000 Volume 66 Issue 650 Pages 3388-3395
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    This paper deals with the morphology formation on the locomotion of a linear-cluster robotic system which is composed of linearly connected multi-autonomous mobile modules. The equations of motion of the linear-cluster robotic system are derived under dynamic interaction with its physical environment and computer simulations are performed about its locomotion on two-dimensional friction plane. When the heading module successively changes its own driving force direction sinusoidally and the other modules have simple rules of locomotion determined according to the direction of interaction force acting from a neighboring module, it is found that a certain region, where a linear-cluster robotic system stably forms a progressive wavy line morphology, exists with respect to the amplitude and period of the driving force direction of the heading module. Furthermore, the natural freqencies and modes of the system are calculated by applying eigen value analysis to the linearized equations of motion. It is clarified that frequency response property of the wavy line morphology corresponds to natural vibration of the cluster robotic system.
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  • Mitsuru JINDAI, Hirokazu OSAKI, Satoru SHIBATA, Akira SHIMIZU
    2000 Volume 66 Issue 650 Pages 3396-3405
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    In this paper, we propose a recognition method comparing characteristics of three-dimensional CAD information with those of input images taken by a movable camera. At first, three-dimensional coordinates of vertexes of an object are determined and the existence of curved surfaces and holes are checked by input images, which are taken by a movable camera. Next, the kind and direction of the object are determined by comparing those characteristics with CAD information. In a case of that, the object can't be determined by them, a difference of CAD information is calculated. Then the object is recognized by comparing the CAD information with input image, which includes the different part of the object.
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  • Masafumi ODA, Nozomi SANADA, Yukio SEKIGUCHI, Tsuneshi ISOMURA, Toshia ...
    2000 Volume 66 Issue 650 Pages 3406-3412
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The purpose of this study is to detect eye-gazing points during driving a wheelchair through the image sequence analysis of video frames. The performances can be measured without restrictions of specific devices such as any accesories and sensors, which were put on a body. Images obtained with three video cameras allow the algorithm to extract four feature points on a face and irises. Their three-dimensional positions were estimated through direct linear transformation (DLT) technique with magnification of a facial image through multi resolution analysis. The direction of a face was estimated via three-dimensional positions of the former, and it defined the facial coordinate. On the other hand, the eye-gazing point was evaluated through three-dimensional positions of the latter. Consequently, Some preliminary results were presented to illustrate the difference in variations with the eye-gazing point between driving a wheelchair and walking.
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  • Ryohei YOKOYAMA, Koichi ITO
    2000 Volume 66 Issue 650 Pages 3413-3420
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    A multiobjective robust optimal design method based on the minimax regret criterion is proposed to determine equipment capacities of energy supply systems so that they are robust in economic and energy saving characteristics against the uncertainty in energy demands. Equipment capacities and utility contract demands as well as energy flow rates are determined to minimize a weighted sum of maximum regrets in the annual total cost and primary energy consumption and to satisfy all the possible energy demands. This optimization problem is formulated as a kind of multilevel linear programming problem, and its solution is obtained by repeatedly evaluating lower and upper bounds for the optimal value of the weighted sum of the maximum regrets. Through a numerical case study on a cogeneration system, the trade-off relationship between the robustness of economic and energy saving characteristics is charified.
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  • Ryuji TSUCHIYAMA, Youichi KAWAKUBO, Mieko ISHII, Mikio TOKUYAMA, Hirom ...
    2000 Volume 66 Issue 650 Pages 3421-3425
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    We studied a magnetic recording head of a three-pad step-slider with a stepped air bearing surface (ABS). The contact force of the three-pad step-slider of positive pressure is smaller than that of conventinal negative pressure sliders when it contacts the disk surface. The smaller contact force is because of the smaller stiffness of air film of positive pressure sliders. We found that velocity of the slider slightly depends on the flying height. We optimized the design of the ABS and showed that the uniform flying height profile at the trailing edge was achieved quite well within two nanometers. We produced many three-pad step-sliders by micromaching silicon, re-calculated and measured the flying height as a function of velocity and found that the difference between the calculations and the measurements was within three nanometers. These results confirm the effectiveness of the three-pad step-slider.
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  • Dong Hui GONG, Ichiro MORIWAKI, Fumio OSHINO
    2000 Volume 66 Issue 650 Pages 3426-3432
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The present paper describes the fatigue tests of Thermoplastic Poly-Imide (TPI) gears, especially carbon fiber reinforced (CFR) TPI gears, at high temperature. The TPI is one of the super engineering plastics, and has good performance even at high temperature. Futhermore, the CFR-TPI has higher strength ; e.g., its bending strength is 2.4 times higher than that of natural TPI. As a result, the fatigue tests showed that the load capacity of CFR-TPI gears is over 10 times higher than that of natural TPI gears. Natural TPI gears show one of the characteristics of plastic ; i.e., viscoelasticity, so that they have a hysteresis. However, CFR-TPI gears never show such kinds of properties. This means that the CFR-TPI gears have similar characteristics as steel gears.
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  • Katsumi WATANABE, Taku OHARA, Atsushi NAGAOKA, Tsutomu KAWAKATSU
    2000 Volume 66 Issue 650 Pages 3433-3440
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The closed loop equations of three spherical rollers, the tripod and the tripod housing are deduced for a prescribed position of the end point of the tripod shaft. The effective initial condition of the set of these twelve nonlinear equations is found out. Then, it is possible to simulate the relative motion of components of the tripod constant velocity joint with any values of kinematic constants. The output angle error, the fluctuation of the joint angle and the whirling motion of the tripod shaft are made cleare. Moreover, the influence of small changes of kinematic constants on the relative motion of components are evaluated.
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  • Katsumi WATANABE, Tsutomu KAWAKATSU, Shouichi NAKAO, Taku OHARA
    2000 Volume 66 Issue 650 Pages 3441-3448
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    In this paper, a procedure is established for solving simultaneously a set of thirty conditional equations with respect to forces and moments acting on three spherical rollers, the tripod and the housing of tripod constant velocity joints, which are cylindrical-paired and sphere-cylinder-paired respectively, for any values of friction coefficients between spherical rollers and its grooves and axes. Moreover, the rotational velocity of the spherical roller relative to the tripod and the condition for rolling motion of the spherical roller to change into sliding motion on its groove are deduced. The established numerical procedure simulates the normal force of the spherical roller and the groove thrust force with a period of π and the housing thrust force with a period of 2π/3 for given values of the joint angle. These results are inspected by experimental analyses.
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  • Junichiro SHINOZAKI, Yutaka TAKANO
    2000 Volume 66 Issue 650 Pages 3449-3455
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
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    The investigation of flywheel type energy storage system has been brisk in these days after discovered Y-based oxide superconductors according to the high potential fewer rotational loss for magnetic bearing even in the temperature (77K) of liquid nitrogen. Permanent magnet rings are applied to the rotational part, and high speed rotation is required to the magnet. The magnet itself is fragile material in the tensile stress, but it is strong enough in the compressive stress. Then authors designed the pre-compressed magnet rings by the multiple layer CFRP hoops. Three of the manufactured pre-compressed magnet rings rotated at the rotation speed of 33723rpm, 33472rpm and 33506rpm respectively at the rotation tests and the values of them were almost the same as the calculated value of 31300rpm.
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  • Chika SHIRO, Shigeka YOSHIMOTO
    2000 Volume 66 Issue 650 Pages 3456-3461
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    It is well known that aerostatic bearings with compound restrictors tend to cause pneumatic hammer instability at the optimum bearing clearance for the maximum stiffness. In this paper, the improvement of such an instability in the aerostatic thrust bearings are discussed. An orifice restrictor put in series into an air supply line is used as a stabilizer. The static and dynamic characteristics of aerostatic thrust bearings with this stabilizer are investigated experimentally and theoretically, and the usefulness of this method for improving the stability of this kind of bearings is confirmed. It is consequently found that the proposed method is very efficient in avoiding the pneumatic hammer instability.
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  • Akihito KAZATO, Shigeka YOSHIMOTO
    2000 Volume 66 Issue 650 Pages 3462-3468
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    This paper describes the float characteristics of an aerodynamic sliding table which can realize non-contact linear motion guide systems using squeeze-gas film effect. This sliding table uses piezoelectric actuators and elastic hinges in order to vibrate the slider surface and generate squeeze-gas film pressure. In the theoretical analysis, a simple dynamic model of the proposed sliding table is presented. The influences of displacement and vibration frequency of piezoelectric actuators on the float characteristics are investigated theoretically and experimentally. In addition, load capacity at vibration frequency of 2200 Hz is experimentally measured. It was consequently found that the proposed sliding table can realize a non-contact linear motion guide and the dynamic model presented in this paper can predict well the float characteristics of the proposed sliding table.
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  • Nao-Aki NODA, Ken-Ichiro TAKEUCHI, Masato NAGAWA, Fumitaka SHIRAISHI
    2000 Volume 66 Issue 650 Pages 3469-3474
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    This paper deals with a new seal system between two flanges without using gaskets. The system includes a groove and an annular lip that is held by one of the flange with its highest point in contact with the other flange to form a seal line when the flanges are assembled. The critical internal pressure for leak in the sealing performance of this system is investigated through an experiment and FEM analysis with varying flange nominal size. The analysis indicates that the critical pressure is controlled by the maximum contact stress appearing at the highest point of the annular lip when the flanges are assembled even the flange nominal sizes are different.
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  • Toshio JINGU, Jyun-ichi ISHIZAKA, Isao HATORI
    2000 Volume 66 Issue 650 Pages 3475-3482
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    Experience has shown that loosening occurs, when stress wave and vibration are emitted to the screw fastening system, even if the tightening is sufficient. In order to clarify the cause of the looseness, the stress wave emitted from bolt shank which constitutes the screw fastening system is made to impinge to engagement conjunction of screw thread, and the problem of the loseness has been studied experimentally. It was proven that seperating the engagement of screw thread of the bolt and nut by the stress wave was one of the causes of the loseness. This paper studies the looseness by emitting stress wave from both of the bolt and the nut. Noticing that soft materials have buffer effect for the impact, the prevention of the looseness is studied by using the soft washer in the screw fastening system.
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  • Michihiko TANAKA, Nobuhiko HENMI, Hiroyuki ISHIBASHI
    2000 Volume 66 Issue 650 Pages 3483-3488
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The purpose of this report is to discuss the behaviour of bolted joints tightened in plastic region. Although, there have been many reports about plastic region tightening method, their method and discussion were based on the classical criterion derived from the rigid-plastic solution for combined loads of axial tension and torsion. Recently, the finite element method is receiving attention in various fields of engineering because of its diversity and flexibility. In this report, a finite element modeling of bolted joint was performed to confirm the validity of the computer program developed for plastic region tightening analysis. The numerically obtained interaction curves are fairy well agreed with those of experiment. The plastic region is initiated at th root of free thread and it spreads to the inner region of free thread portion of bolt. The elastic zone at the cross section of thread and the partial plastic zone at the thread portion characterize the empirical fact that diameter of circular stress area is the mean of root and pitch diameters.
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  • Tsuneo SOMEYA
    2000 Volume 66 Issue 650 Pages 3489-3496
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    Using a bubble theory which takes into account the surface dilatational viscosity κ, influences of eccentricity ε, 4 bubble and 4 bearing parameters on pressure distribution are studied for the oil film in journal bearing : When κ is neglected, the maximum negative pressure is given by a formula containing only a dimensionless surface tension. For small ε, pressure distribution scarcely depends on bubble parameters, and coincides nearly with that calculated by conventional theory under Reynolds condition. For large ε, it changes also with bubble parament values. Whether ε is small or large, the maximum pressure hardly depends on bubble parameters, but depends only on bearing parameters. It is nearly equal to that calculated by conventional theory under Reynolds condition. For increasing ε, κ and shaft speed, the pressure distribution tends to that of Sommerfeld type.
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  • Tsuneo SOMEYA
    2000 Volume 66 Issue 650 Pages 3497-3503
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    Taking into account the surface dilatational viscosity κ, influences of eccentricity ε and 8 parameters on the limit of development and on the value of negative pressure including tensile stress are studied : When κ is taken into account, negative pressure develops in a wider range of ε and parameters, and its maximum value tends to be larger. Whether κ is taken into account or not, the larger ε is, the greater is the number of parameters, which limit the negative pressure development and therefore the more hardly develops the negative pressure, but the larger is the developed negative pressure. The oil film ruptures then, when the force of κ and surface tension cannot suppress the bubble expansion. When ε, oil viscosity and initial vapor radius are small and κ is large, negative pressure in the oil film can increase with increasing rotational speed, because the effect of κ suppresses the bubble expansion, as long as the assumptions made in the bubble calculation hold.
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  • Yoshio MIZUMOTO, Naoki ASAKAWA, Yoshimi TAKEUCHI
    2000 Volume 66 Issue 650 Pages 3504-3509
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The study deals with the automatic chamfering with an industrial robot. Although the automatic production system with an industrial robot has recently been developed, the chamfering and the deburring are still obstructions of automatic system. When the model coordinate system is matched to the robot coordinate system, the matching error will occur. Tool paths need to be generated, considdering the depth of cut on the basis of cut on the basis of CAD data of workpiece. The aim of the study is to develope an intelligent holder and automatic chamfering system. The intelligent holder can correct position error by perceiving the contact force and comparing it with the theoretical one. This system, TADRPECS(Tool Application Direction Referenced Position Error Compensation System), is experimentally found to be effective in chamfering.
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  • Muneo MIZUMOTO, Yuichi YANAGASE, Shigeru KIMURA, Masanori NAGATOMO, Ka ...
    2000 Volume 66 Issue 650 Pages 3510-3515
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    The structure of a mechanical torque limiter for space manipulators, which is used for tightening and loosening bolts, was studied geometrically, and the design method for obtaining a high reliability was clarified. The results of this study are as follows. 1)A claw made of balls and rollers is the best clutch structure for the torque limiter. 2)The condition for obtaining a difference between the operation torque of loosening and tightening bolts was clarified by introducing a structure factor S. 3)In order to keep a change of the operation torque small over a long period, the contact angle of the ball and the roller when thetorque limiter operates should be made as small as possible, and the friction coefficient between them should be kept small.
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  • Shinichi YOKOTA, Kazuhiro YOSHIDA, Takeshi OKAYASU, Tomohide KAWAUE, Y ...
    2000 Volume 66 Issue 650 Pages 3516-3522
    Published: October 25, 2000
    Released on J-STAGE: February 26, 2008
    JOURNAL FREE ACCESS
    For high power micromachines using fluid power in millimeter size, micropumps are needed as fluid power sources. An SMA or Shape Memory Alloy is one of promising actuators for micropumps, however, the response is very low on the cooling phase. To overcome the problem, the paper proposes an SMA-driven micropump using ECF jet cooling. The ECF or Electro-Conjugate Fluid is a new kind of dielectric functional fluid which produces jet flows between high DC voltage-applied rod electrodes and realizes a simple cooling mechanism. Firstly, the micropump is proposed and characteristics of the actuator using ECF jet cooling are experimentally investigated. Effectiveness of the ECF jet cooling is verified. Secondly, a micropump in 1 cm-cubic size is fabricated and the basic characteristics are experimentally investigated. The optimal parameters are obtained and the maximum output flowrate and pressure of 11 mm3/s and 0.18 MPa are realized. Finally, for an optimal design method a mathe matical model is derived and verified through simulations.
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