Voice coil motor has a property to convert the mechanical energy to electrical energy and vice versa. In this study, an electro-magnetic resonant shunt damper, consists of a voice coil motor with electric resonant shunt circuit, is proposed. The optimal design of the shunt circuit is obtained theoretically for this electro-magnetic resonant shunt damper. Further, the effect of uncertain errors of the different elements of the electro-magnetic resonant shunt damper is also investigated. The applicability of the theoretical findings for the proposed damper is justified by the experimental analysis.

抄録全体を表示

This paper describes the measurement method of dynamic stiffness of subcutaneous tissues. After the ball indenter which is attached to the Voice Coil Motor (VCM) is pressed against body surface with any preload, the mass-spring-damper system is constructed between the subcutaneous tissues and the VCM. When the VCM is controlled with positive feedback of velocity, self-excited vibration is occurred. Spring constant of the subcutaneous tissues is identified with this resonance frequency of the system. Further, the VCM is controlled to realize the constant amplitude of velocity using a variable velocity feedback gain. Damping coefficient of the subcutaneous tissues is identified with velocity feedback gain. This method can be realized as a real time system, and accordingly measures time-varying dynamic stiffness of subcutaneous tissures.

抄録全体を表示

It has been a problem in some hospitals that operations using surgical microscopes of suspension type become more difficult due to microvibrations of the microscopes caused by human walks and building equipment such as air conditioning machines. For a practical solution to it, an active microvibration control system was developed, in which magnetostrictive actuators were used because of their large stiffness. A control law based on a model matching method was used to control of microvibrations of the microscopes having various dynamic characteristics corresponding to their attitudes. Tests showed that the microvibration control system using the control law was effective. Furthermore an active-passive switching law was developed to manage large vibrations of the microscopes due to doctors handling of them. Tests showed that the microvibration control system was effective and reliable enough for real application.

抄録全体を表示

The goal of this research is to analyze vibration response when the main mirror in a Satellite Solar-B optical telescope assembly (OTA) is subjected to acoustic load. First, we determined the maximum frequency for the frequency range in this analysis from the results of vibration tests and acoustic tests. Next, we derived a frequency response analysis method using BEM, and calculated the internal sound pressure in the OTA. We then considered this internal sound pressure as the input, conducted a Power Spectrum Density (PSD) analysis using an FEM model, and analyzed the vibration response of the OTA. Results of these studies indicate good correlation between the results from the proposed simulation and the results of the acoustic test.

抄録全体を表示

In this paper we propose a robust force controller of flexible one-link arms with a linear motor. By using Hamilton's principle, we derive dynamic equations of the motion of the base body that the flexible arm is mounted, and the constraint force. The control synthesis is carried out in the infinite-dimensional setting, mathematical features of which give rise to stabilizing PDSF control algorithm. Experimets have been carried out and results confirm that the controllers perfom.

抄録全体を表示

This paper describes the system for the calibration of accelerometers using a three-dimensional vibration generator and laser interferometers. The vibration generator is an electrodynamic type, IMV TS-1030 S, which can generate motion with the arbitrary direction in the three-dimensional coordinate system under sinusoidal, random and shock operation mode. It has five actuators in total, two actuators each for X-axis and Y-axis and one for Z-axis motion. Motion of the table is monitored during the operation by the three piezoelectric-accelerometers, BK 4393. The signal from them is used for the control of the table, feed forward and feed back. Motion of the table in three-dimensional space is measured by three laser interferometers, Neoark MLD 301 K. The sensitivity of an accelerometer is defined in the form of a matrix including the cross sensitivity. Size of the matrix is 1×3, 2×3 and 3×3 for one-axis accelerometer, two-axis accelerometer and three-axis accelerometer, respectively. Since acceleration is a vector quantity, input signals and output signals of an accelerometer make a vector space. An accelerometer is mathematically a device executing a projection between two vector spaces. This system is the realization of this concept.

抄録全体を表示

In this paper, nonlinear vibration response containing slip, jump and impact behavior was evaluated. Firstly, impact behavior of 2-degrees of freedom system consisting of containment vessel and overhead slewing crane was discussed. Especially, impact force was necessary for design against huge earthquake. Authors evaluated impact force by experimental and numerical analysis. Secondly, whole overhead slewing crane model which was scale of 1/10 was given for verification of numerical results containing slip, jump and impact behavior simultaneously. Numerical analysis gave nonlinear response such as impact force. Numerical approach was possible and useful to be applied for design against huge earthquake.

抄録全体を表示

It is generally well known that the motion of rotating elastic body in collision is complex but interesting. This is due to the deformation of the local contact part, the friction force acting on the contact surface and so on. It is difficult, however, to observe the state of affairs in collision because of instantaneous phenomenon. In this paper, two types of model for the motion of the rotaing elastic ball in planar collision are proposed. One is a simple model which consists of two particles with spring and damper. Another one consists of distributed particles in circumference, spring and dampers. An experiment is also carried out to compare with numerical results and verify their validity, using a high speed camera. The simple model represents some characteristics of the motion. Numerical results using another model agreed with experimental ones both qualitatively and quantitatively.

抄録全体を表示

During a car frontal collision, some part of the occupant's kinetic energy is transferred to the vehicle through the restraint system. The high ratio of the transferred energy has the advantage of protecting the occupant. This phenomenon is called “ride down effect”. It is known from experience that if the deceleration of the automotive body is large in the early stages of a collision, the effect becomes large, provided that the vehicle kinetic energy and the maximum value of the automotive body deformation are same. In order to design an automotive body structure taking into consideration the ride down effect, the dynamic relation between the occupant deceleration, which is one of important injury criteria, and the automotive body structure must be studied. However, there have been few researches to analyze the theoretical mechanism of the ridedown effect in detail. In this paper, we formulated ridedown effect focusing on the protection devices using a two-degree-of-freedom model for a vehicle and an occupant. The relationship between the index of the ride down effect and the occupant deceleration caused by crashing the automotive body structure was theoretically analyzed, and an optimum automotive crash design was examined.

抄録全体を表示

In this paper, we propose the model based control system design for autonomous flight and guidance control of a small-scale unmanned helicopter. A small-scale unmanned helicopter has been studied with fuzzy and neural network theory, but it is not so good performance for unmodel based control to stabilize it. For this reason, we design a mathmetical model (Mettler's model) and a model based controller for a small-scale unmanned helicopter system. In order to realize a full autonomous small-scale unmanned helicopter, we have designed the attitude controller and trajectory controller with kalman filter based LQI for a small-scale unmanned helicopter. The characteristic of the attitude closed loop dynamics is taken into consideration to design a trajectory controller. By way of the simulations and experiments, it has been clarified that the proposed scheme for attitude control and guidance control is very useful.

抄録全体を表示

Formation flight control of two spacecraft is considered in this paper. A trajectory of relative position change of one spacecraft with respect to the other is designed on the basis of the Hill's equation from the viewpoint of the minimum fuel consumption. The total fuel consumed along the trajectory is analytically obtained. Discrete two-degree-of-freedom control law is also proposed in order to realize the designed trajectory. The controller achieves deadbeat property of the closed loop system and guarantees the robustness to the controller gain decrease. Numerical studies are executed in order to verify the trajectory generation and the discrete control.

抄録全体を表示

A sensing and control method inducing a mobile robot to the maximum inclinational direction on slopes is proposed. It is clarified that a roll angle sensor detects a deviation angle to the maximum inclinational direction on slopes. Mobile robot direction control to the maximum inclination direction can be easily achieved by doing feedback this deviational angle information to a servo controller in order to correct the direction. Experimental results show that the proposed control method is feasible not only on flat slopes but also spiral slopes. But in case of spiral slope, the deviational information is not symmetrical, and it requires asymmetrical compensation to servo controller. This compensation control is easily achieved by using the computerized control system. The locus of the mobile robot has followed the center line of the spiral slope exactly.

抄録全体を表示

This paper deals with an experimental study of vortex-induced vibrations of bellows structure subjected to fluid flow. The characteristics of the vortex-induced vibrations and Strouhal number S_tp are examined experimentally with changing the pitch length and number of flexible convolutions. The fluid flow around the vibrating convolutions is visualized and the structure of the vortex street is clarified. As a result, it is found that the lock-in phenomenon occurs to the bellows structure in out-of-phase mode due to the coupling between the vibration of the convolutions and vortex street generated along the convolutions. Strouhal number S_tp based on the convolution width is about 0.18, and is independent of pitch ratio p/D in the range of p/D=2.0-4.0.

抄録全体を表示

In order to evaluate the manipulation ability of the upper limb, we applied the analysis of the mechanism of robot manipulators. The effect of individual's muscular power characteristics on the easiness of hand force manipulation is expressed in the six-dimensional ellipsoid. The spatial characteristic of the manipulation ability of the upper limb in three-dimensional space was clarified by the visualization of the six-dimensional ellipsoid using two projection methods. As examples, we analyzed wheelchair propulsion, then the effectiveness of our evaluation methods were examined. Our evaluation methods will be useful for the development of equipments based on the manipulation ability of the upper limb.

抄録全体を表示

For fluid microactuators and microfactory, the authors have proposed a novel high output micropump using inertia effect of pipeline element which has a pipeline element in place of an outlet check valve and verified the effectiveness with a fabricated micropump. To increase the output power and to miniaturize the size, this paper establishes a simple nonlinear mathematical model with lumped parameters and verifies the effectiveness comparing the simulation results with the experimental results. Then, the optimal structure of the micropump is investigated through the simulation with different sizes of the pipeline element and so on. Lastly, a micropump is fabricated and the load characteristics are experimentally investigated.

抄録全体を表示

In this paper, we will propose integrated optimization system that is composed by RBF network as approximation tool and Genetic Range Genetic Algorithms as optimizer. This system has function of optimizing radius of basis function in optimization, indication of next searching points by using basis function and optimization by using Genetic Range Genetic Algorithms that is a step further of Adaptive Range Genetic Algorithms. Key success in approximation by using RBF network lies in giving good data sets. Here, “good data sets” means that they can update accuracy around local optimum points, and also they can give global information of original function's response surface. In that sense, indication function is quite important in this system. For that purpose, we introduce base function which is composed by approximation RBF network. We demonstrated the proposed system to a bench mark problem to show efficiency of the proposed method. In constraint optimization case, it works something like active set strategy, and we can reduce the number of function calls.

抄録全体を表示

A method of predicting energy demands in consideration of minimizing variations in their predicted values is proposed to rationally determine operational strategies of energy supply systems. The autoregressive integrated moving average model is adopted to express time series data on energy demands. Values of model parameters are identified by minimizing not only the errors between measured and predicted energy demands but also the variations in predicted ones by a global optimization method for nonlinear programming. This method is applied to the prediction of the cooling demand in a building used for a bench mark test of a variety of prediction methods. The results obtained by the proposed method are compared with those by a conventional method by which only the errors are minimized. It turns out that the proposed method can predict energy demands with the variations reduced substantially at the sacrifice of small increases in the errors.

抄録全体を表示

An “Analytical Method of Equivalent Linear System Uning the Restoring Force Model of Power Function Type”, which is used as a non-linear vibration analytical method for vibration systems that shows their characteristics of viscoelasticity, was applied experimentally to vehicle dynamic analysis. This article describes the theory of this analytical method. The analytical method was applied to vehicle dynamic analysis by using it experimentally to analyze vehicle steering force characteristics. We were able to verify the appropriateness and accuracy of this method.

抄録全体を表示

Up to now, there is no good hardware of three-dimension (3D) tactile shape display for virtual reality, because a different object has various shape, therefore, to present the all different 3 D object shape with continuous values is difficult to operator. In the psychophysical studies, human visual and tactile sensations have illusory fusion caracteristics. That is to say, we can recognize an object shape tactually using the vision characteristic even if exact tactile information is not presented. So by utilizing human characteristics of sensory illusory fusion, realization of the tactile shape display can be simplified. Object shape is made from the surface curvature and the distance between any finger touch points. In our previous study, human fusion characteristics of the curvature of the curved surface are measured by psychological experiment. In this study, tactile perceptive characteristics of the distance between the thumb and each fingertip on an object are measured and analyzed. Based on the results, we proposed a three-dimension tactile shape display.

抄録全体を表示

In this paper, we present numerical results of the static contact and flying behavior of a tri-pad head slider in a low disk speed range. In order to analyze the mixed-lubrication characteristics of the head slider, both of Greenwood & Williamson model for rough surface contact problem and the Boltzman-Reynolds equation for ultra-thin air lubrication problem were taken into consideration. From numerical calculation, we found a hysteresis of flying height versus disk speed in the transition between contact and flying, where the tri-pad slider can take three different values of minimum spacing and pitch angel numerically. The flying characteristics of the slider focusing on the hystersis of flying height are examined in relation to the surface roughness, contact stiffness, frictional coefficient, ambient pressure and crownheight.

抄録全体を表示

This paper presents experimental study and numerical simulation of vibration and noise of a speed increaser, which consist of a star type planetary gears and a planetary type epicyclic gear train. The ring mode vibration of internal gear in the star type planetary gears and torsional vibration of planetary gear in the planetary type epicyclic gear train are measured by use of telemetry system. The influence of tooth profile error for the vibration and the noise is clarified. The numerical simulation is also carried out to evaluate the exciting force and it's associated vibration. In this method, the coupled vibration of shaft bending, torsinal and ring mode vibration of the internal gear are taken into account employing modal synthesis method. The simulation results shows a good agreement with the experimental ones. And it is found that the ring mode vibration magnifies the higher order component of gear mating frequency.

抄録全体を表示

The study deals with the manufacture and testing of an arc-shaped and a rectangular fly-eye mirror used in an extreme ultraviolet lithography system. Both mirrors have a complex reflective surface consisting of many mirror elements. The function of the mirrors is that an arc field can be illuminated uniformly by the integration of rays from the mirror elements. In this study, a fabrication method for the mirrors, in which ultraprecision 5-axis control milling was adopted, was discussed. By using this method, the mirrors with sixteen mirror elements ware fabricated. Furthermore, the mirrors were tested by measuring rays reflected from them. As a result, the rays were successfully integrated on the arc field, demonstrating that the mirrors were acurately fabricated. However, the surfaces of the mirror elements had waviness with a height of ten nenometers order, causing uneven illumination on the arc field. This finding indicates that the waviness on the surfaces must be removed to achieve high uniformity of the illumination.

抄録全体を表示

Improvement of scroll compressors for domestic air conditioners has been in progress. Scroll compressors have advantageous characteristics such as high efficiency, low vibration, and low noise. Reducing the surface roughness of the compressor component enables to increase the efficiency of air conditioners by means of decreasing energy loss caused by friction. However, reducing surface roughness in end face machining of endmill operation causes the problem that makes the machining time longer. The aim of this study is satisfying both high machining efficiency and good surface roughness. The sintered carbide tool produces smooth surface at higher cutting speed, but the tool suffers large wear. The cBN tool is better for high speed machining, while the large wear at the corner of the cutting edges still remains as a problem. Our present work focused on the sintered carbide tools employing high feed rate instead of high cutting speed. The factors of the tool geometry that are the width of land, the face angle, the lake angle and the number of teeth were optimized for high feed rate machining. As a result of this study, the machining efficiency increased four times and the tool life was doubled.

抄録全体を表示

In the harmonic generation using nonlinear optical crystals, it is well known that the frequency-conversion efficiency is very sensitive to temperature of the crystal, and its temperature rise is caused by laser absorption. In this study KH₂PO₄ (KDP) was supposed as a nonlinear optical crystal for second harmonic generation (SHG). Temperature dependence of conversion efficiency and output-beam profile were examined theoretically by solving the coupling problem composed of heat conduction equation and complex amplitude equatios. The latter equations have been derived in our previous study, considering laser absorption in the crystal. As a result, we revealed that remarkable inverse-conversion of SHG also appears for the repetitive laser irradiation with high power density, and consequential power density fluctuation in the crystal causes the disordered output-beam profile.

抄録全体を表示

Temperature dependence of second harmonic generation (SHG) was examined theoretically by solving the coupling problem composed of heat conduction equation and complex wave amplitude equations. The latter equations include effect of laser absorption in the crystal. KTiOPO₄ (KTP) crystal was supposed as a nonlinear optical crystal, and its SHG characteristics were compared with KH₂PO₄ (KDP) crystal. Power density distribution in the crystal, time variation of the conversion efficiency and output-beam profile were analyzed quantitatively during repetitive irradiation of pulse laser in Gaussian mode. As a result, it was revealed that there are various mode in output-beam profile, such as ring mode, single mode with one or two rings in the surrounding, depending on incident power density or crystal length. These disorders of transverse mode are caused by the inverse conversion of SHG. It was also concluded that there is an optimum length of crystal to the irradiation conditions, and it can be estimated by the present study.

抄録全体を表示

Frequency conversion technique using nonlinear optical crystals in indispensable to solid-state laser applications. It is well known that the conversion efficiency is very sensitive to temperature change of crystal, which is caused by laser absorption. We have been analyzing problems of second harmonic generation (SHG) by coupling the electric field to the temperature field. In this study, temporal pulse-shape dependence of SHG was investigated theoretically, and Gaussian pulse and rectangular pulse were compared. Main conclusions obtained are as follows : (1) Both conversion efficiencies with Gaussian and rectangular pulses fluctuate with irradiation time, however the former fluctuation is slower and more gentle. (2) Pulse of output second harmonic fluctuates most remarkably at the center, where power density of incident fundamental is highest, in the Gaussian pulse. (3) As a result, pre-pulse and post-pulse are geserated before and after the main pulse. (4) Such distortion of output pulse shape becomes more remarkable as power density increases.

抄録全体を表示

Recent demands of the gear coupling are to reduce gear noise that is supposed to be caused by gear tooth gap for shaft angle fluctuation. In generally, large shaft angle increases tooth gap for shaft angle fluctuation. On the same time, load capacity is supposed to decrease. The tooth gap for shaft angle fluctuation is given by the analysis of tooth contact. The conventional analysis is an approximate one and is limited on its precision. An analysis of higher precision is necessary for recent critical demands on the gear coupling. This paper discusses analysis of clearance of matching tooth surface, where the profile of rack tooth surface has a straight line. Conact bearing pattern spreads in the direction to tooth tip and has edge contact. Those are different from the conventional assumptions.

抄録全体を表示

When a pair of paths of contact intersecting at the design point P₀ are given on the normal plane Sn which is perpendicular to the relative velocity at Po, the conditions for the pair of paths of contact to realize equal strengths of tooth and bearing on both drive and coast sides under the same transmitted torque are discussed. Those conditions are expressed by 5 equations with 7 independent variables, which draw 5 separate reference paths of contact on the plane S_n geometrically. In designing gears, 3 variables (shaft angle, offset and gear ratio) are given, so that the equations have no solutions generally. However, cylindrical, crossed helical (including worm) and straight bevel gears can satisfy those conditions because their 5 reference paths of contact are superimposed and become at most one or two lines rectangular each other. Spiral bevel and hypoid gears with a rectangular shaft angle can not satisfy those conditions and their reference paths of contact vary according to the variables (offset, gear ratio and spiral angle), so that they have been designed as similar gears to ones whose performances are already assured by fixing the variables in some degree.

抄録全体を表示

In order to make power transmission gears smaller and lighter, it is necessary to examine the surface durability of case-carburized gears in detail under the high load condition. In this paper, the influence of hardening profile on changes of rolling-sliding contact surface made of a case-carburized alloy steel was investigated by using a 2-roller-type contact fatigue testing machine. For the rolling-sliding contact surface of the case-carburized test rollers in which the hardening profile increases by changing heat treatment process, the followings were clarified : (1) The occurrences of micro cracks and micro pits can not be prevented. (2) The value of endurance limit assuming no spall is not improved. (3) The changes of surface temperature and surface roughness are influenced by contact stress and stress cycle. (4) The amount of wear increases. (5) The value of hardness near the surface changes significantly and decreases under the high load condition.

抄録全体を表示

Polyvinyl alcohol (PVA) hydrogel is one of prospective artificial cartilage materials. The mechanical property of PVA hydrogel was evaluated in the tensile test. PVA hydrogel was prepared by repeated freezing-thawing method. It is known that the mechanical strength of PVA hydrogel treated by repeated freezing-thawing method depends on the number of freezing-thawing cycles. In this study the number of freezing-thawing cycles were selected form 2, 5 and 10. The mechanical strength was the highest in 5 cycles. The wear property of PVA hydrogel as artificial cartilage was evaluated in a simplified reciprocating test. A sliding pair of an elliptical upper stationary PVA hydrogel specimen and flat reciprocating lower specimen of PVA hydrogel or glass plate was tested at constant load. The lubricant was hyaluronate (HA) solution containing protein of albumin and/or γ-globulin. In the solution containing high concentration of HA, the wear of sliding pair of PVA hydrogel was decreased. Especially wear was decreased in lubricant containing both of proteins. It is supposed that the boundary film of proteins is effective to decrease wear of PVA hydrogel. The boundary film on glass plate was observed in AFM. Albumin adsorbed weakly compared with γ-globulin. Mixed boundary film of both proteins reduced the wear remarkably.

抄録全体を表示