An exact solution is presented for solving axisymmetric free vibrations of laminated composite conical shells having meridionally varying thickness. Based on the classical lamination theory which neglects shear deformation and rotary inertia, equations of motion and boundary conditions are obtained from the stationary conditions of the Lagrangian. The equations of motion are solved exactly using a power series expansion for symmetrically laminated, cross-ply conical shells. Conical shells having both ends clamped are numerically studied to show the effects of the number of laminae, stacking sequences and other parameters upon the frequencies and mode shapes.

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We present an analysis of nonlinear vibration of simply supported rectangular plates with a point support. Linear free vibrations of a point-supported plate are solved by the Ritz method with Lagrange multipliers prior to the nonlinear analysis. A stress function is introduced to describe governing equations for nonlinear vibration of the plates. Eigenfunctions for the linear free vibration are used to express out-of-plane displacements, approximately, in the nonlinear analysis of the point-supported plate. Applying the Galerkin method to the governing equations, a nonlinear equation for the time function of the out-of-plane displacement is derived. Periods of vibration are calculated using the complete elliptic integral of the first kind. Period-amplitude curves are shown for several positions of the point support and the effects of the position of the point support are studied.

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This paper deals with the experimental and analytical study of the rocking response of a free-standing block subjected to horizontal base excitation. Using blocks and base conditions of a plate without and with a slip-proof sheet, experiments were performed for both the free rocking and harmonic excitation tests. Experimental results of the rocking test are applied for evaluating the coefficient of restitution, which could be used to determine the reduction of angular velocity at the moment of impact between the body and the base. The coefficient of restitution obtained from the results of the free rocking test is used in the simulation. A piecewise-linearized equation is used for the numerical calculation by applying a newly developed algorithm to attain high accuracy. The results of the calculation are compared with those of the harmonic excitation test.

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The coupled vibration of a wheel-railway track system has been considered as that of a mass moving on a beam. In this paper, a model is proposed to analyze the coupled vibration when a wheel travels on a railway track. The railway track supported by sleepers is considered as a beam on Winkler's foundations, and the wheel traveling on the railway track at constant speed is considered as a moving mass. Hertz's contact stiffness is assumed between the wheel and railway track. Numerical results are compared with experimental ones to verify the validity of the numerical method. The numerical method is found to be efficient to analyze this system. Based on the numerical simulation, the appropriate analysis range of the beam model and the characteristics of coupled vibration are discussed.

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The purpose of this study is to investigate the relation between vibration and heat generation in superconducting magnets (SCMs) for magnetically levitated vehicles, and to determine the SCM structure which reduces heat generation. Thus, two experimental SCMs are designed and produced. First, vibration tests are performed, in which electromagnetic forces due to the ripple magnetic fields from ground coils are applied to the outer vessels of these SCMs. These results clarify vibration modes causing high heat generation in SCMs, i. e., a torsion, a bending, a yawing, and a rolling mode. Second, some eigenvalue analyses involving variation of positions of load supports for an inner vessel are performed, using a simple finite element model. These results are used to determine the optimum supporting method of inner vessels which prevents the resonances with the vibration modes causing high heat generation.

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In regard to the failure mode of magnetic disc drives, the offtrack of disc heads in the seek direction was presumed to be a dominant factor in the operation of disc drives during an earthquake. A method for analyzing the offtrack of disc heads in the seek direction was proposed. A magnetic disc drive was sinusoidally excited to investigate its functional capability. The results show that the offtrack of disc heads in the seek direction dominates the functional capability of magnetic disc drives.

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In this paper we present a suspension control method using a dynamic damper that is virtually fixed to an unsprung mass. The current suspension control system achieves ride comfort in the low-frequency range, but not in the high-frequency range. We propose a suspension control method in order to improve ride comfort in the high-frequency range. From simulation results, it was clarified that control based on a combination of a virtual dynamic damper and a sky-hook damper improves ride comfort in a wide frequency range. We also derive applications for semi-active suspension including time delay.

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We discrive a design method for two-degree-of-freedom controller system based on the internal structure. Firstly, we examine the internal structure of the system and derive a condition which clearly demonstrates the equivalence between the disturbance observer based controller and the generalized two-degree-of-freedom controller. Secondly, we propose a design method of two-degree-of-freedom controller using μ-synthesis taking into account the structure of the system. Finally, we present some simulation results of velocity control of a two-mass system and confirm the effectiveness of the proposed method.

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System parameter identification and attitude control experiments (FLEX) have been conducted as one of the bus experiments of Engineering Test Satellite-VI (ETS-VI) launched in August, 1994 by H-II rocket. The objectives of the identification experiment are to evaluate typical identification methods both in the frequency and time domains, to compare the identified parameters with the ones established in the ground test before launch and to construct the standards for designing attitude controller. This paper shows the results of the system parameter identification experiment using impulse excitation by gas jet thrusters for the attitude/orbital control system. Measurement data from attitude control system and paddle mounted accelerometers are down-linked by telemetry and analyzed by the Eigensystem Realization Algorithm (ERA) to identify flexible modal parameters.

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System identification experiments have been performed as one of the on-orbit experiments of ETS-VI which was launched in August, 1994. There are two types of identification experiments: impulse excitation and random excitation. The method and the results of random excitation are summarized in this paper. In the random excitation experiments, thruster injection direction is changed randomly according to the M-sequence. Using the on-orbit data, parameter estimation by the ARX model is executed in order to construct a mathematical model of ETS-VI. The behavior of the mathematical model is compared with that of the on-orbit data in both the frequency and the time domains. The results show that the mathematical model accurately reproduces the on-orbit behavior of ETS-VI.

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An analytical method to predict the natural frequency of deployable antennas for satellite use is proposed. We consider a structural system in which an elastic body is supported by a coil spring. Displacement of the antenna in the system is expressed as the sum of the elastic displacement and rigid-body displacement due to rotation. The system vibration equation is obtained by substituting kinetic energy and potential energy into Lagrange's equation. Numerical examples are based on a deployable antenna for the Japanese Experimental Test Satellite VI (ETS-VI). The antenna natural frequency measured in orbit is compared with the predicted frequency. Results show that the proposed method is effective for natural frequency prediction of satellite antennas.

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This paper presents a procedure to estimate unmeasured rotation mode shapes of a test structure as a linear combination of those of the corresponding finite-element (FE) model. In this procedure, weighting coefficients for each mode shape combined are determined by comparing experimentally measured translation mode shapes with analytical mode shapes of the FE model. Since the accuracy of the estimated strongly depends on the selection of the mode shapes combined, a method based on the modal assurance criterion (MAC) values between experimental and analytical translation mode shapes for assessing the significance of mode shapes to be combined is proposed. The proposed method is shown to be suitable for a proper selection of mode shapes through a numerical example using a frame structure model. In addition, a practical technique to use the MAC values as the mode selection indicator under incomplete conditions of the measurements of translation mode shapes is suggested.

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Rubber track systems have already proved their benefits compared with steel tracks, particularly in terms of weight, vibration, noise, damage to road surface and the ability to be used on-road. Therefore, rubber tracks can be applied to not only agricultural and construction machinery but also the running gears of off-road vehicles at high speed. However, the rolling resistance of rubber track systems is still considerably larger than that of rubber tires. It is very important that rubber track systems with low power loss and reduced vibration and noise are developed, but there has been little study on the theoretical and experimental analysis of the running characteristics at higher speeds. In this paper, the effects of various running conditions such an initial tension, track velocity and temperature of the rubber belt on the rolling resistance are described.

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In this study, we attempt to identify parameters of a beam using an image processing method. The parameter identification is an inverse problem and easy to be influenced by noise. High accuracy of parameter identification requires a high measurement accuracy. Although the image processing method has attractive features, i.e., non contact method and high flexibility of setting, many researchers paid little attention to this method because of its low accuracy. We examined an approach that made up for the disadvantages of image sensing in order to carry out parameter identification.

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We propose an optimum design method for a new of type hydraulic shock absorber in which the resisting force matches that of impacts of various masses using electrorheological (ER) fluid having apparent viscosity that can be modified with an electric field. Comparing the results of the optimally designed ER shock absorber and an existing shock absorber with a metering pin, it is shown that the maximum acceleration of a light body (1250kg) nearly equals that of a heavy body (2250kg) during impact for a system containing the ER shock absorber, while the maximum acceleration of the former is about 2 times that of the latter during impact for a system containing the existing shock absorber. In addition, it is shown that the maximum accelerations obtained using the optimum design method are reduced by 0.9∼8.9% compared with those obtained using a method proposed in a previous paper using a constant resisting force in the shock absorber.

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We present a numerical synthesis of topological and size optimization of lightweight framed structures with consideration of impact load using fuzzy set theory and FEM. The dynamic response of a mechanical system composed of joints, springs, masses and framed structure is analyzed to obtain the loading conditions used for the static finite-element analyses. In the sensitivity analyses of the framed structure, minimum weight, strength and displacements at certain boundaries are considered simultaneously using fuzzy set theory. During optimization, insignificant elements are neglected. This method is applied to a beam structure composed of thin-walled members. The results demonstrate the reliability and efficiency of the proposed method.

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In the present paper, a fish-drying control system based on skilled worker's performance is proposed for reducing human power in the process and for higher quality of products. The function of the system is largely broken down into two procedures: (1) The procedure before drying. (2) The one during drying. The procedure (1) is for setting drying conditions and the prediction of required drying time. A fuzzy linguistic model is built for predicting, before drying, proper dryness to be provided to a particular raw material. The procedure (2) is for more accurate estimation about the drying progress utilizing the observation during drying. Drying temperature is regulated by using fuzzy inference. Experimental results showed the usefulness and the applicability of the present control system.

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In this paper, we propose a new simple design technique for constructing digital PID compensators for the robust control of sampled-data systems, based on a minimax procedure. First, we formulate the robust control problems for sampled-data systems, including digital PID compensators and disturbances of system parameters. Next, we propose the minimax-based design method with the PID compensators for the robust control problems of sampled-data systems, where we develop a new minimax algorithm which is reliable, stable and simple in computation. Finally, we apply the proposed method to a realistic problem in order to demonstrate its effectiveness.

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Recently, noncontact method for measuring cylinder configurations are required in industry. This paper reports the development of a new method for measuring cylinder configurations, using sound signal without contacting the contour surface. This method is based on the fact that the phases of sound waves scattered by a cylinder are delayed according to the diameter of the cylinder. Experiments were performed for various cylinder configurations formed by single and plural periodical deflection, using a loudspeaker, microphone and FFT-analyzer. It was found that the phase delays of sound waves were periodically changed according to the revolution of the cylinder, and the period between the phase delay and cylinder deflection was in good agreement. In addition, the angle of phase delay was linearly proportional to the magnitude of deflection.

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This paper is concerned with biomechanical analysis of the motion characteristics for grasping a solid cylinder. Contact pressure and surface electromyogram (surface EMG) of muscle flexor digitorum superficialis during grip motion were measured using a contact pressure measurement system with pressure-sensitive conductive rubber sensors and an electromyograph, respectively. In addition, direct linear transformation (DLT) technique with a video camera system is used to analyze three-dimensional joint motion of fingers. It was found that the tips of middle finger, ring finger and thumb are mainly used to stably grip the cylinder. The experimental results also showed that grip pressure increased with an increase in the weight of the cylinder with a constant diameter.

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An earthworm moves on the ground by propagating an expansion/contraction wave of its own body. Friction force due to the propagating wave is produced at the contact surface. In this study we measure in detail the locomotion pattern of the earthworm when it moves straight on two plane plates having a different friction coefficient. The amplitude, period, duration, and phase of the propagating wave on the earthworm are measured. Then we calculate numerically the locomotion pattern of the earthworm using a simple model consisting of the body which can expand and contract and normal and tangential contact springs at the surface of the body. It is found that the waveform of the actual earthworm is adequate for producing locomotion with high efficiency and velocity.

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In the present research we aim to verify a newly developed on-line path-planning algorithm that directs a non-holonomic robot to a goal while avoiding obstacles in an uncertain 3-d world easily and reliably. The developed robot runs on two wheels and is equipped with a visual sensor (CCD camera) with a restricted view field, Please clarify, a gyrocompass and a means of measuring and recording wheel running distance to recognize its position. Furthermore, as this robot is controlled by a parallel processor called a transputer, it can perform four types of distributed processing simultaneously: autonomous position inference, image measurement processing, running control, and running algorithm monitoring. In experiments, the robot reached its goal without coming into contact with any obstacles. As a result, it was verified that this developed sensor-based path-planning algorithm was effective for this nonholonomic mobile robot.

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We propose a color signboard for indoor mobile robot (known as AGV in factories) localization. The signboards are placed in the environment as landmarks to locate the position of the robot. They are also attached to each robot for localization relative to other robots. Each signboard consists of highlighted areas illuminated by a back-light and color stripes. When the camera on a robot observes the signboard, the bright information in the image is processed to detect the signboard. The hue information is also used to identify the signboard. Subsequently, the distance and the angle between the camera and the signboard are calculated by triangulation. If other robots or obstacles partially conceal the signboard from view, the camera can still determine the position. Fundamental experiments demonstrate the effectiveness of the proposed method.

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Micromanipulation is required for assembly and maintenance of micromachines and their parts. If the handled objects are miniaturized, interactive forces between microparticles and gripper surface become dominant. Attractive forces such as van der Waals forces, forces caused by liquid bridges and electrostatic forces in the air cannot be neglected. It is necessary to consider the physics of these forces in the micro world in controlling and manipulating micro-objects. We propose a handling strategy for micro-objects based on the physics in the micro world. Attractive forces are modeled and their reduction methods are presented. We show experimental results of reducing these forces. Based on the proposed reduction methods, we present a new micromanipulation strategy.

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In this study, we present the vibration analysis procedure of a hydrostatic gas bearing spindle considering the stiffness and damping of a gas film and the effect of elastic deformation of the components of a rotor. An equation of motion for the elastic vibration of the rotor is formulated using the finite element method and then combined with the rigid-body equation of motion of the housing and the gas film stiffness and damping calculated from the frequency domain analysis of the perturbed Reynolds equation. Since the gas film stiffness and damping are functions of frequency and mode shape, the natural frequency and the damping ratio of each vibration mode are calculated iteratively until both the eigenvalue analysis and gas film analysis are satisfied. The calculated natural frequencies of the gas bearing spindle are found to be in good agreement with the experimental ones. The calculated damping ratios qualitatively agree with the experimental ones with quantitative discrepancy of 30% for the same mode.

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To clarify static and dynamic properties in the circumferential direction of a tapered coupling joint, the relation between loading torque and relative angle of torsion between a taper shank and a taper socket is measured for Morse tapers #3, #4 and #5. Static properties such as torsional stiffness of a tapered coupling joint and maximum loading torque are strongly influenced by the contact state between the taper shank and the taper socket. Dynamic properties such as natural frequency and damping capacity are obtained from an impulsive response test of the tapered coupling joint. These properties are also influencd by the contact state between the taper shank and the taper socket.

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The measurement of transmission error is essential for development work and trouble-shooting in gearing when noise and vibration occur, and is also used for production control. For this reason, measurement and evaluation of the transmission error of hypoid gears are desirable. The authors have already proposed a method for cutting hypoid gears with modified tooth surface in which the transmission error is controllable to some degree. In this study, the static transmission error of the hypoid gears is measured under a lightly loaded condition. Two autocollimators which measure the exact angular positions of the ring gear and pinion are employed. The transmission error is obtained from the measured angular positions. As a result, the transmission errors caused by blade runout during pinion generation and by nonconjugation owing to the tooth surface modification were measured and confirmed clearly. The hypoid gears showed no deterioration of transmission error when misaligned.

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For the purpose of a detailed description of rotational vibratory response of a helical gear pair having tooth surface deviation during light load transmission, we have already developed the numerical calculation method for gear vibration which can take any type of deviation into account. In this paper, we show the 'Performance diagram', in which the acceleration level is shown by contour lines on the contact ratio plane formed by the transverse contact ratio (abscissa) and the overlap ratio (ordinate). With these diagrams, the vibration characteristics of each type of tooth surface deviation become clear. The optimal and worst gear parameters are discussed.

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When we operate a transmission under light load conditions, the contact pattern of the gear pair does not cover the entire tooth surface and the vibratory response varies with transmitting load. To obtain a detailed description of the rotational vibratory response of a helical gear pair having tooth surface deviation during light load transmission, we have already developed a numerical calculation method for gear vibration which can take any type of deviation into account. In this paper, we show the 'performance diagram' for several types of tooth profile deviation and several load conditions. The perfomance diagram indicates the acceleration level using contour lines on the contact ratio plane formed by the transverse contact ratio (abscissa) and the overlap ratio (ordinate). With these diagrams, the vibratory characteristics of each type of tooth profile under light load conditions become clear. The optimal and worst gear parameters are discussed.

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The loaded transmission error is calculated using Hertzian formulas for the approach deformation of a pair of teeth and approximate formulas based on the FEM analysis for the bending deflection. Analysis of the loaded transmission error proved that the actual contact ratio is an effective index of the loaded transmission error of a helical gear pair. The actual contact ratio is the ratio of the rotational angle to the angular pitch during the period in which a tooth pair is actually in contact. The analysis based on the actual contact ratio clarified the following. (1) The actual contact ratio varies between 1.0 and the geometrical contact ratio, depending on the applied load. (2) The loaded transmission error exhibits maxima when the actual contact ratios are integers. (3) The no-load transmission error whose actual contact ratio is 1.0 results in the absolute maximum. (4) A gear pair with low level of no-load transmission error exhibits low level of loaded one.

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Analysis of the transmission error of a helical gear pair proved that the effective contact ratio can be an index of the loaded transmission error. The effective contact ratio is defined as the ratio of the rotational angle of a tooth pair to the angular pitch during the period in which the point of contact is located on the tooth surface. Since tooth pairs in edge contact contribute only slightly, the effective contact ratio neglects the period of edge contact. A gear pair with higher effective contact ratio results in smaller transmission error under applied loads with which the actual contact ratio exceeds the effective contact ratio. Consequently, gear dimensions affect the transmission error in this load range. Since this new index is based on the path of contact, both gear dimensions and tooth surface modifications affect this ratio.

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When the location of gear axes and the constant ratio of angular velocities are given, a pair of tooth profiles having a straight path of contact that coincides with the common contact normal at each point of contact is expressed by algebraic equations. The common perpendicular to the gear axes and the axis of relative rotation which is defined in the static space by the given ratio of angular velocities determine the static coordinate system, in which the design point P₀ and the path of contact are determined as follows. In the case of cylindrical or bevel gears, P₀ is chosen arbitrarily on the axis of relative rotation and the path of contact is chosen as a straight line through P₀. In the case of other kinds of gears, P₀ is chosen arbitrarily on the horizontal plane which includes the axis of relative rotation and is perpendicular to the common perpendicular, and the path of contact is chosen as a straight line through P₀ which lies on the normal plane that is perpendicular to the relative velocity at P₀. When the path of contact and its common contact normals are transformed to the coordinate systems rotating with each gear, a pair of tooth profiles without variation of bearing loads is obtained.

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When the location of gear axes, the ratio of angular velocities and a pair of tooth profiles without variation of bearing loads are given, there is the pair of tooth surfaces without variation of bearing loads which has the involute helicoid including one of the tooth profiles for one member and its conjugate tooth surface for the other, and is modified to make contact along the pair of tooth profiles. The involute helicoid, its conjugate tooth surface and the surface of action are presented by the algebraic equation, which enable to analyze the tooth action of all kinds of gears with the pair of tooth surfaces mentioned above, such as helical gears, crossed helical gears, conical gears, face gears, worm gears, bevel gears and hypoid gears, the last two of which are not developed yet but must be useful for quieter power transmissions between non parallel axes.

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The first report presented a new method for determining tooth profiles on the basis of theoretical analysis of the motion and engagement of wave gears. However, the analyzed tooth profiles encounter difficulty in machining at present from the point of view of accuracy and economic efficiency. This paper presents a method for approximating the theoretical tooth profile by the involute tooth profile for practical design of the wave gear drive. This paper also presents a practical method for determining the position of the unstretchable flexible reference curve which exists at the bottom part of the flexible gear tooth.

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The hourglass worm gearing is widely used because of its high load capacity. We developed an hourglass worm gearing with worm teeth generated by the high-speed screw cutting method. The worm teeth are generated by the inside part of the concave cone. We calculated the contact lines, and estimated the relative curvature. We also determined suitable dimensions of the gearing and the cutter to achieve good gearing performance.

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This paper describes the concept of a new hob for an hourglass worm wheel. The hob can be used repeatedly when the cutting edges become worn. The basic cutter surface of the hob is generated by the relative motion of the tool and the work different from that of the wheel and the worm. This concept was applied to the design of a hob for wheel tooth generation of the hourglass worm gear generated by a tool with a conical surface. Numerical calculations show that the hob has sufficient relief angles and that it generates the principal part of the wheel tooth surface with high accuracy after regrinding its face surface.

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This paper deals with the improvement of gear accuracy which has been obtained through the practical use of a newly developed hobbing machine. The carbide hob for finishing of large hardened gears has recently become very popular. A cutting edge with a rake angle of -30°degrees is fixed slantly to the cutting direction. The hob is characterized by its performance finishing only tooth surface of a gear without chipping of the cutting edge on a universal hobbing machine. However an accuracy of a gear with a higher hardness is poor. Especially, a tooth profile error appears largely. Therefore, the new CNC hobbing machine with the high rigidity and with the backlash elimination has been developed for large gears. From experimental results, the new machine was found to be effective in finishing of hardened gears.

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In this study, which is aimed at understanding machining characteristics and tribological phenomena in vacuum, a machining system in a vacuum chamber which pressure is 6.0×10^-5 Pa, is developed and diamond cutting experiments using aluminum workpieces are carried out. The cutting system is a face turning composed of a high speed spindle with a magnetic bearing, that revolves at 22000rpm in vacuum, and a diamond tool with rake angle 0 deg and flank angle 5 deg. Cutting behaviors in vacuum are similar to those in argon gases, and also those in air and oxygen are in a similar way. For instance, the cutting force in vacuum and in argon gases is larger than that in air and oxygen, and phenomena like a built-up edge generate in air and oxygen, but that is not observed in vacuum and argon gases. The similarity depends on the pressure or absence of oxygen. It is found that those results depend on the pressure or absence of oxygen.

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Angular deformation of a steel frame core welded by a robot is larger than the deformation during manual welding. In this study, several welding condition parameters which seem to influence the angular deformation are discussed. We conclude that the difference in angular deformation between the robot and manual welding was caused by the change of interpass temperature (To). Computer FEM simulation predicted the effects of To; namely, the angular deformation decreased with increasing To. The experimental results supported the results of FEM analysis; actually the angular deformation of the core welded by a robot at high interpass temperature (To=573K) was half of that at low interpass temperature (To=273K).

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Selective growth of aluminum nitride (AIN) has been performed by the Ar ion laser-enhanced reactive vapor deposition method. Si (100) is used as a substrate, and is selectively heated with laser direction. Simultaneously, 99.999% aluminum (AI) is evaporated from a hexagonal boron nitride crucible in a NH₃ atmosphere. The Al reacts with NH₃ on the substrate surface which is heated to more than 450°C by laser scanning, then AlN is formed on the laser-scanned portion. Not only scanning speed but scanning length are required to be appropriate values so that the average thickness of the Al layer deposited during an interval of laser direction is less than 0.2nm. The conditions for selective growth are found to be a scanning speed of 40mm/s, a scanning length of 8.0mm, and a deposition rate of 1.0nm/s. The use of a single-wavelength and single-mode (TEM₀₀) laser beam is found to be effective for depositing a sharp selective growth pattern of AlN.

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In this paper we discuss a method for measuring flatness which allows for accurate control of not only the size but the shape of products on machine tools. Flatness is calculated in the present work, from the displacements on several circumferences, which are measured using a rotary sensors. In this paper we discuss a method for measuring displacement on one circumference, as the first step in measuring flatness. Five sensors are attached to the measuring apparatus. One is rotated and the others detect the rotary errors. The displacement on one circumference is obtained by eliminating the rotary errors from the measured values of the rotary sensor. A summary of the result is as follows below. (1) The automatic measuring method for flatness using the machine tools is shown. (2) The principles of measuring displacement on one circumference are proven to be efficient.

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An atomic force microscope (AFM) can trace surface roughness using a contact probe in a similar manner to a stylus instrument, and the AFM has the advantages of high lateral resolution and low contact force because of its very soft cantilever and a feedback controller that keeps the contact force constant (less than 10^-8N). However, such features can cause measuring errors characteristic of an AFM. In this study, a standard sample was measured using an AFM under certain conditions in order to extract the errors from the results. The distortion of the cantilever was also observed using a microscopic interferometer. As a result, it was clarified that the cantilever was bent unexpectedly by a lateral force which acted on the tip of the probe. The feedback controller could not trace the surface geometry precisely because the precision angle sensor using an optical lever mistook the force which acted on the tip.

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