In a continuation of our research on resonant response characteristics of a group of blades, other aspects of which were reported by sister papers (1), (2) and (3), coupled vibrations of axial deflection and torsion of a group of blades are thoroughly investigated in the present work. From the results, we explicity and quantitatively determine the resonant stress increasing and decreasing effects in such coupled vibrations and we provide a theoretical explanation of the cause of those effects. Our whole research, consisting of two series of studies, that is, the former study^(1)∼(3)on uncoupled ibration of only tangential deflection and the present on coupled vibration of axial deflection and torsion, is aimed at elucidating the essence of resonant stress increasing and decreasing effects in a group of turbine blades; it should be a contribution to rotating machine's dynamics. In this paper, the first of the new series, methodologies are presented for the investigation on the resonant response characteristics of such coupled vibration, comparing with the methodologies adopted in sister papers(1), (2)and(3).

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This paper describes the shear coefficient K of transverse vibration for trigonal crystals such as quartz crystal, lithium tantalate and lithium niobate which are anisotropic materials. In this paper, we derive the shear coefficient K for rectangular cross section of the trigonal crystals in Timoshenko's beam theory of three-dimensional elasticity. The theoretical result gives K as a function of the transformed elastic stiffness constants c'₂₂, c^^^(SUB)44, c'₆₆. In addition, A value of K for quartz crystal, lithium tantalate and lithium niobate versus a cut angle is calculated so that K has a value of 0. 796-0. 867 for quartz crystal, 0. 834-0. 857 for lithium tantalate and 0. 831-0. 863 for lithium niobate, respectively, when a Z-plate of the crystals is rotated with a cut angleθof 0-180°about the x-axis. The values of K for quartz crystal are then compared with those for an isotropic material obtained by other authors.

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This experiment using a relatively simple apparatus shows how the method of averaging can be used to calculate different self-excited vibrations of a bowed string, if a certain number of modes and a special restriction in the phase differences for each mode are taken into account. First, the coefficient of friction as a function of the relative velocity is incorporated into a nonlinear analysis of the self-excited vibrations of a bowed string. Next, using Galerkin's procedure, the equation of motion for the bowed string is reduced to the nonlinear ordinary differential equations. Finally, the solutions for these equations, which are determined using the method of averaging, are compared with the computed results using the Runge-Kutta-Gill method and the experimental results.

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This study aims to clarify deformation and stress generation mechanisms in a multiblade fan under static and dynamic torsional moments, and to establish a simple lumped inertia model for the dynamic analysis. Static and dynamic torsional tests were carried out to investigate the deformation and stress of the blades. Numerical calculations of the deformation and stress using the finite element method were also carried out under the same loading conditions. By comparing the experimental results with the numerical ones, the generation mechanisms of the deformation and stress of the blade were clarified. The results of these investigations are as follows. The relative displacement between the main and side plates causes the bending deformation in the flatwise and edgewise directions and the torsional deformation of the blade under the static and dynamic torsional moments. The stress caused by the deformation in the flatwise direction mainly governs the strength of the blade. Good coincidence is found between the static stress distribution and the dynamic one in the first mode. This means that the simple lumped inertia model is suitable for further dynamic analysis of the rotating fan shaft system.

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An optimum design technique for the purpose of aseismic design of complex plant structures, such as piping and boiler structures is proposed. Particular attention is focused on the evaluation of the optimum damping and stiffness of the structures and components. A pseudo-least-squares algorithm is introduced to determine the optimum design parameters. Under the requirement of certain allowable maximum response to a given earthquake excitation, optimum stiffness and damping values of the structure can be simultaneously calculated by this proposed method. The applicability of the method is demonstrated through three structural models: (1) linear multi storied building model in which stiffness and damping constant of each floor are optimized; (2) nonlinear multi storied building model having an isolated floor in which the hysteretic energy absorber of the isolator is optimized; (3) combined boiler-supporting structure model connected to each other by the inelastic "seismic ties" is optimized. In this model, optimum values of the damping characteristic of the seismic ties are evaluated.

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The FFLM vehicle system, in which a flip-flop linear motor with permanent magnets is used for propulsion, has been investigated. In this system, trucks are to be coupled as in a train and the basic function of a conventional railway wheelset is separated into 3 functions of support, guidance and propulsion. The running wheel, which is an independently rotating one, functions for support, the guide wheel for guidance and the FFLM for propulsion. Up to now, there have been no conventional railway vehicles employing coupled trucks. Thus, the effects of couplig trucks on train vibration have not becn examined. This paper concerns numerical analysis of the effects of coupling trucks on the lateral vehicle vibration, which is induced by lateral irregularities of the guide rail. The main results obtained are as follows. The lateral stiffness of the coupling at a position lower than the truck's center of gravity can reduce the lateral vehicle accelerations and the guide-spring distortion. The longitudinal stiffness between trucks has almost no influence on the lateral vibrations. The coupling of trucks has little influence on the vibration excited by cross-level irregularities of the running rail.

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A new method for enhancing riding comfort by reducing vertical flexural vibration of a carbody is studied in this paper. In order to dissipate the energy of flexural vibration while minimizing the weight to be added, viscoelastic layers and constraint layers are stuck partially onto the outside sheathing of the carbody. Riding comfort, including the flexural vibration of the carbody excited by vertical track irregularities, is analyzed theoretically assuming that the carbody is a partially multilayered beam. As a result of the analysis it is revealed that there exists an optimum length of the damping layers which leads to the maximum damping. It is found that damping of the vibration can be maximized by choosing appropriate characteristics of the damping layers. It is concluded that this method can contribute to better riding comfort of a lightweight carbody of a high-speed train.

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The driving system of a vibratory machine with self-excited vibration follows the resonance frequency change automatically, and reduces electric power consumption. Self-excited vibration is generated by the positive feedback of vibration velocity or the phase delay control of vibration displacement deviation on a mechanical resonance system. The self-excited vibration whose amplitude is limited by saturation of a power amplifier output contains many higher-harmonic components. On the other hand, the self-excited vibration whose amplitude is limited by variable feedback gain becomes a pure sine wave. The feedback gain is controlled by amplitude deviation. The controller consists of a constant term, which is equal to the critical gain on the stability of the feedback system, a linear term and a third-power term of amplitude deviation. The constant term and the linear term influence the steady-state vibration, and the third-power term influences the rising characteristics of vibration.

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In a previous paper, we proposed a new identification technique for a nonlinear rotating shaft system, the applicability of which was confirmed by numerical simulation. In this paper, the applicability of the technique is reexamined experimentally. For this purpose, a rotating shaft system consisting of an elastic shaft with a disk mounted at its midspan is constructed. Then, the system is identified by the proposed technique. To evaluate the results of identification, the predicted responses using the identified results are compared with those obtained by the experiments. For further evaluation, the responses of the system after it is balanced using the identified results are compared with those of the experiments. In this way, the technique is found to be applicable in a real system.

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In this paper, a new type of elastoplastic damper utilizing continuous plastic bending of thin metal rods is proposed in order to obtain an elastoplastic damper which yields damping even for a small displacement. The seismic responses of a piping system supported by the elastoplastic damper were calculated using a continuous system simulation language and the effects of the damper on the deflection of the piping system are discussed. The trial damper was made using a thin copper rod, and the resisting force characteristics and fatigue strength of the damper were measured. The seismic responses of an L-shaped pipe supported by the trial elastoplastic damper were measured using an electrohydraulic shaking table. The experimental results were compared with the calculated results.

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It is wellknown that the stability of nonlinear feedback systems depends considerably on their nonlinearities. The stability of a Lure-type nonlinear system with a pattern in which the nonlinearities lie on the first and third quadrants is studied. Identifying such patterns is important to enable system engineers to design stable nonlinear feedback systems. This paper presents a pattern classification method for systenms with arbitrary nonlinear feedback. Classification is carried out using the robust nonlinear-perturbation technique, in which nonlinearities are regarded as the nonlinear perturbations of linear stable systems. Stability theorems for the pattern classification of several types of nonlinear feedback are derived. In these theorems, the positive realness of the transfer function and the quadratic Lyapunov function are utilized.

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Theoretical analyses of impact phenomena in a ball-racket system in tennis are performed using a ball-string system modeled by a spring mass system with few d. o. f., the spring constants of which are identified from the experiment. It is impossible for such a simple model to express exactly the complex behaviour of the impact between ball and racket. Therefore, finite element analysis using a realistic model is desired and we intend to establish the technique for this analysis. In the present paper a finite element analysis system was developed in order to analyse the impact behaviour between the ball and the strings of a clamped racket head. The results obtained using the developed system are compared with experimental data and good agreement is observed. Moreover, through these investigations, it is found that the coefficient of restitution of a ball rebounding from clamped strings depends on the initial string tension and the incident velocity.

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This paper addresses the issue of parking motion planning and control of motor vehicles with front steering. Because of the non holonomic constraints on kinematics of the vehicles, parking motion control is a difficult problem. A neural network control system is proposed for such problems. The system learns parking control strategy using good human driving data of parking. The perfect learning of neural networks using actual driving data is not so easy. Therefore, some additional rules are also proposed to refine the parking motion for the control system by the neural network. The resulting control system consists of a neural network and additional rules. The system is tested in a restricted area surrounded by walls as a motion planner and a motion controller. The simulation results show that the system works well for the learned wall shapes and for another wall shapes slightly different from learned ones. An experimental result also shows the effectiveness of the system.

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This paper presents a new methodology for controlling a vehicular powertrain system such as an automatic transmission. The driver's acceleration/deceleration intentions are critical factors in controlling systems such as the automatic transmission or the engine. Fuzzy inductive knowledge and vehicle mechanical models are proposed here as tools for inferring the driver's intentions. By using this knowledge, the driver's intentions can be inferred from driving characteristics. The road grade resistance is needed to determine both the driver's intentions and a suitable vehicle control strategy. Grade resistance is estimated using a mechanical model. A comparison is made with a conventional control system to show the performance improvements obtained with the proposed control methodology. The results verify the effectiveness of factoring the driver's intentions into powertrain control systems.

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In pneumatic servo systems, the adaptive pole-placement control is applied to improve the control performance. However disturbances are not considered in the conventional design scheme of the adaptive control. Thus, an improved design schemes is proposed for a pneumatic servo system with disturbances. However, since the design scheme of the adaptive control is complicated, much time is required for calculating all kinds of parameters, especially for identifying plant parameters. Therefore, we propose a multirate method for the improved adaptive pole-placement control to solve the above problem. In this design scheme, a controller in equipped with a faculty for elimination the influence of disturbances and an identification-time of plant parameters is chosen integer multiple of the sampling-interval T. The effectiveness of the proposed design scheme is confirmed by experiments using the existent pneumatic servo system.

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A method for optimal synchronous position control of a multiservo system is proposed. Synchronous position control is required in many engineering applications such as a two-wheel-drive vehicle and a large rotary machine. Synchronous position control using inverse dynamics of slave systems has already been proposed. However, it is not applicable when disturbance is added to the slave system. A cross-coupled biaxial system with a symmetrical structure has also been proposed. However, this system isn't stable when an inappropriate value of the weighting factor is chosen. In this paper, an optimal synchronous position control system for a multiservo system is proposed, where both position errors and a synchronous error are included in a performance index. The control system is always stable and synchronous position control is realized by decreasing the synchronous error. It is applied to a linear X-Y table and its effectiveness is confirmed by experiment.

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In this report, the position control method using a two-phase induction motor is investigated. The position control system consists of neuro-adaptive control and slip frequency control type vector control. The vector control was implemented with an electric current control type PWM inverter and the vector computation algorithm. The experiments were carried out, and the usefulness of the present control method was confirmed. Furthermore, the experimental results by the neuro-adaptive control and the vector control was compared to the experimental results by the two-degree-of-freedom control and the vector control.

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With the increasing use of high-pressure flexible hose in hydraulic equipment, the accurate knowledge of its dynamic response is required over a wide frequency range. We derive an analytical model for the wave propagation characteristics in a flexible hose with finite length by considering the coupled vibration of the hose wall and fluid in the hose, as well as the effect of the possible longitudinal resonance of the hose wall, where the hose wall is assumed to be linear, compressible and anisotropic viscoelastic with respect to the longitudinal and circumferential directions, while the fluid is assumed to be compressible and viscous and its motion to be laminar and axisymmetric. The membrane shell theory neglecting the radial inertial force is applied to the motion of the hose wall while taking into consideration the fluid pressure, and the Navier-Stokes equations and continuity equation which are simplified for an incompressible fluid are applied to the motion of the fluid after the fluid compressibility is equivalently converted into the compliance of the hose wall. A model is obtained in a transfer matrix representation which relates the pressure and flow ripples at two crosssections of a straight hose with fixed end support under constant fluid temperature and average pressure. In addition, the existing models for flexible, elastic and rigid lines may be considered as special cases of the model developed here.

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With the increasing use of high-pressure flexible hose in hydraulic equipment, the accurate knowledge of its dynamic response is required over a wide frequency range. We investigate the validity of a new model for the wave propagation characteristics in a flexible hose with finite length, which has been developed by us previously, using thick-wire reinforced hydraulic hoses over a wide frequency range. As the model parameters, the normal Young's modulus and Poisson's ratio representing the static mechanical properties of the hose wall are determined in a specially designed static expansion experiment, and the time constants representing the frequency-dependent mechanical properties of the hose wall are determined using an optimization method on the basis of the measured results of transfer matrix parameters of the hose. The model is applied for the prediction of the transfer matrix parameters of hoses with different lengths. By comparing the theoretical results with the experimental results, it is shown that the model gives satisfactory results within the frequency range of around 0∼3 kHz. Also given is a comparison of the theoretical results of the new model with those of two existing models.

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In order to prevent the expansion of tube damage and to maintain structural safety in steam generators(SG) of a liquid metal fast breeder reactor (LMFBR), it is necessary to detect precisely and immediately the leakage of water from tubes of heat exchangers. The active acoustic detection method, which detects the sound attenuation due to bubbles generated by the sodium-water reactions, has attracted interest owing to its short response time and being least affected by background noise. Sound attenuation is also subjected to structures such as heat transfer tubes and shrouds. Accordingly, it is necessary to evaluate the sound attenuation due to structures. However, studies concerning these aspects are very few. In this paper, using the water bath, the attenuation characteristics of sounds due to flat plates are investigated and discussed under various conditions such as thickness, location, and number of flat plates.

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A new active noise control system forair-conditioning ducts is presented, together with computer simulations and experimental results. The system feed forwardly controls the second source using the signal of the progressive wave conmponent of fluid-borne noise detected upstream of the duct, and has the capability to change system parameters owing to a programmable digital signal processor. The adaptive feed-forward control structure is based on the "filtered-X" LMS algorithm. It is established through testing of a small model apparatus that pressure pulsation (noise) in a duct downstream of the second source can be reduced by at least 20 dB for almost all harmonics of around 40 Hz to 1000 Hz, while maintaining stability, even in the case where uncontrolled system parameters such as acoustic properties and dynamic characteristics of the second source change with time. It is also shown that the computer simulations agree well quantitatively with the experimental results and can be applied successfuly to system design.

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In this paper, we propose a stroboscopic interferometric method to measure small vibrations of an ultrasonic motor. The Fizeau interferometer in the optical microscope is used to obtain stroboscopic interference images of a vibrating surface. The measured interferograms are analyzed by the fringe scanning method. The stator of an ultrasonic motor is excited at a resonant frequency of 30 kHz. As the laser irradiation time is sufficiently short compared with the vibration period of the sample, interferometric images with a high contrast are obtained. By changing the delay time of the laser irradiation, vibrations of the surface at different phases are obtained. The distribution of the vibration is visualized sequentially. The stator is vibrated at an amplitude of 3. 7μm peak to peak, so the measurement error is evaluated to be 1/20 of the laser wavelength approximately. This method is useful for designing an optimal ultrasonic motor.

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A piezoelectric bimorph element is useful for a slip sensor for robots because it is sensitive to dynamic stress, can be made small and its signal circuit is simple. A slip sensor using a piezoelectric bimorph element presented in this paper detects the first large pulse caused by frictional slip and also detects the instants of both contact with and release from an object. However, since it is easily influenced by vibrations transmitted from robot actuators and other sources, this slip sensor requires a vibration absorber at its supporting point. Therefore, experiments on motions of touch, slip and release were performed after reducing vibratory noise by means of an absorber at a foot of the device. It was found that the slip sensor reliably produces one pulse at the instant of first slip, and also produces one pulse at the instant of contact with or release from an object. The release signal is opposite to the touch one.

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The present paper describes the implementation of and experiments on a three-axis tactile sensor applying an optical wave guide plate. The sensor is comprised of a sparse array of columnar feelers and a dense array of conical feelers, which are formed on opposite sides of a silicon rubber sheet. The columnar feelers contact objects while the conical feelers contact the acrylic optical waveguide plate. Three components of a force vector applied to the columnar feeler are identified from contact areas of four conical feelers which are covered by one columnar feeler. Contact points of conical feelers photographed using a CCD camera are transferred into a frame memory board installed in a personal computer and they are memorized as 8-bit patterns. A one-bit pattern is quantized from the 8-bit pattern by utilizing a suitable threshold value; the contact areas of conical feelers are obtained from the total number of picture cells of the one-bit pattern. In evaluation experiments, several combinations of vertical and horizontal forces are applied to the columnar feeler through a probe attached to a three-axis force sensor. The experimental results show that the three components of the force vector can be calculated from the four contact areas, and that hard material is not favorable for the conical feelers but is suitable for columnar feelers.

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This paper describes a compact video-rate range finder to be used in autonomous vehicles and intelligent robots, and as a vision substitutes for visually impaired people. The device, being composed of binocular CCD color cameras and a simplified electric circuit, can efficiently extract only the colors of red and blue from a scene, and can provide 3-D distance information continuously within object contours. This device was applied to the measurement of motion of a human body and the estimation of rotation diameter, rotation plane, trajectory, and fluctuation of a rotating body. It was confirmed that this device can be applied to real-time measurements of 3-D spatial positions and motion of objects.

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We are aiming to develop an inexpensive high-performance 3D measurement system using a camera. For this purpose, camera calibration is crucial because it determines the precise position and orientation of the camera in the wrork coordinate. In the previous experiment, our calibration technique including distortion correction proved an excellent performance but only in specific equipment. However, for some applications calibration must be easily and flexibility repeated for various situations. Fortunately our technique looks suitable for this, since the camera should perform in a manner similar to an ideal pin-hole camera once it obtains the information of the distortion to be corrected. In this paper, in order to verify the usefulness for the above requirement, we propose a method for assessing the accuracy of calibration which is based on inverse transformation from an image to the real world. The experiment shows the utility of the method.

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In active noise control, the transfer characteristic of an acoustic feedback path has a considerable influence on the stability of the control system. When the acoustic system has a feedback path, the control system often causes unstable behavior called howling. An adaptive howling canceler designed to prevent thin howling is studied in this paper. This adaptive howling canceler estimates the acoustic feedback path and acts to suppress the howling. In this paper, the effect of this adaptive howling canceler was considered for two different adaptive noise control algorithms. One was the conventional filtered-x LMS (least mean squares) algorithm and the other was the frequency-domain adaptive algorithm proposed by the authors. From computer simulations, it was shown that the howling canceler works effectively with the filtered-x LMS algorithm. On the other hand, the control system became unstable with the frequency-domain adaptive algorithm. To alleviate this unstable behavior, variable output gain was considered. A good result was obtained with this variable gain.

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The dynamics of a speaker and microphone play important roles in active noise control. In this paper, we investigate the dynamics of a speaker and microphone by means of theoretical modelling and experiments. From the model identified using frequency-domain test data, it is clear that the speaker and microphone and a free sound field system comprise a time delay system with nonminimum phase. We discuss the effects on active noise control performance of unstable zeros through simulations. It is clear that in order to obtain the effect of noise reduction, the dynamics of speaker and microphone must be improved.

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When intense sound is transmitted to the ear, stapedial muscle contraction in the middle ear occurs in order to protect the inner ear from overstimulation. This phenomenon is termed acoustic stapedial reflex (SR). Tympanic volume displacement during SR reverses occasionally in direction wrhen posture changes. However, the generation mechanism of this displacement reverse is unclear. Therefore, in this study, an attempt is made to clarify this mechanism by means of theoretical analysis.

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Tympanometry has been widely used to aid in the differential diagnosis of middle-ear diseases. However, the measurement results are greatly affected by the condition of the tympanic membrane, due to the measurement method of this device. Therefore, it is important to understand the condition of the tympanic membrane before taking this measurement. In this paper, an attempt is first made to measure sound velocities in tympanic membranes of guinea pigs, normal subjects and patients by the supersonic wave method. Then, Young's modulus of the tympanic membrane calculated from the measured velocities are compared with those obtained by the microtension test and from other data. Comparison shows good agreement. Therefore, It is concluded that Young's modulus of the tympanic membrane is obtainable by the supersonic wave method.

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The conventional sound recognition methods pursue the understanding of meaning of a sound by analytical approach. But a human can recognize the emotional feelings of a speaker no matter what language he or she may use. There seems to be two kinds of such expressions. One is truly emotional at heart and the other is to convey how he or she feels as messages. This work is aimed at understanding such messages of the emotional feelings of a speaker. Therefore, we paid more attention to the variation in time series. Our preliminary work demonstrated that anger can be extracted from human sound and characterized the sound time series by noting the pitch frequency and amplitude variation using cepstrum method.

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An ionic conducting polymer gel film (ICPF) atuator is a composite of a perfluoro-sulfonic acid membrane sandwiched between platinum layers. Bending motion is induced by applying voltage between the surfaces in water or in wet conditions. This phenomenon was discovered in 1992. After reaching the maximum displacement toward the anode immediately, the actuator bent back to the cathode side, and approached the initial position gradually when a step voltage was applied. Current through the actuator decreased exponentially. The maximum displacement was proportional to the magnitude of the step voltage. Motion induced by a step current was almost the same as that induced by a step voltage but was slower. Voltage induced by the current increased gradually and reached a certain value, then increased once more to a steady voltage. The motion did not depend on the direction on the surface. The bending occured in all directions. Larger displacement was observed near the electrode. Dynamics of the actuator was expressed in terms of a 4th-degree transfer function by black-box linear modeling. Simulation results were in good agrrement with the experimental results.

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A quarter of a century has passed since adaptive control methods were first proposed, but their applications to real robot manipulators have not necessarily been successful. Some reasons are the lack of time for calculation of the adaptive law because of their complexity and the lack of the guidelines for the regulation of the design parameters of the controller. Therefore the evaluation of the methods using real industrial robot manipulators is required in order to confirm the merits and demerits of the adaptive algorithm. In this paper, we consider the motion control problem of robot manipulators with simple adaptive control (SAC) systems and discuss time for calculation and parameter regulation of the method. We used decentralized SAC as an adaptive control algorithm. The simplicity of the adaptive algorithm means that we must regulate a small number of design parameters, and the simplicity of the controller alleviates the shortage of time for calculation. The effectiveness of the method is confirmed through an experiment using a six-degree-of-freedom industrial robot manipulator.

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In this paper, a design concept of a micro object manipulation system with concentrated motion is proposed. Based on this concept, a "micro-handling system" is realized, and evaluated by means of some micro-object handling operations. This system consists of a concentrated motion manipulator, a worktable and optical microscopes. In micro-object handling, it is most important that alloperations are always executed within the visual field of a microscope. To enable task execution within the visual field, a tool tip must always remain within the visual field, i. e., D. O. F. of the manipulator must essentially be configured so that all rotational centers of D. O. F. coincide with each other at the tool tip. Using this system, we succeeded in several micro-object handling operations such as assembly of a "micro-torii" (shinto shrine gate) and a micro-air turbine (dia. 500μm) as examples of assembly of small mechanical parts, and folding of a micro-"origami (paper folding)airplane" as examples of handling flexible objects. The capability and effectiveness of this system configuration are confirmed by these experimental operations.

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Recently, in artificial intelligence technology, much attention has been focused on the approaches based on behavior (behavior-based AI) that demonstrate robustness and flexibility to dynamically changing environments. On the other hand, the immune system plays important roles in maintaining its own system in dynamically changing environments. Therefore, we believe that the immune system can provide a new paradigm suitable for dynamic problems dealing with unknown environments rather than static problems. We propose a new approach to behavior-based AI by focusing our attention to the biological immune system. The basic principle of our proposed method is that the immune system equipped with the robot selects the simple action (antibody) which is suitable for the current situation(antigen). We confirm the feasibility of our proposed method by applying it to the behavior control of an autonomous mobile robot in a cluttered environment as an example.

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This paper proposes a control model for safety of human cooperative robots. Human motion is stochastically predicted by a Markov process model. Simulation results of the prediction corresponded to real human motion. Future dangerousness is estimated by using the predicted motion. Robot speed is changed in order to minimize the danger. Simulation results of the avoidance revealed that this control model is effective especially because prediction errors cannot cause extremely dangerous condition unlike by algorithms based on deterministic prediction.

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A braking material for an emergency stop device for a super high speed elevator (810 m/min)was developed. The material is a special cast iron containing Cr, Ni and P. Its structure is a pearlitic matrix of flaky graphite, steadite and cementite, and its wear resistance is about lO times that of FC250. Its coefficient of friction is about 1. 5 times that of FC250. A new emergency stop device made of the material was proven to conform to Japanese standards and ANSI (American National Standards Institute) standards for stopping-distance and car inclination criteria in tests conducted by dropping actual-scale equipment.

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Friction and wear characteristics of artificial cartilage materials sliding on a smooth metal counterface have been studied in a pin-on-disk apparatus. In this study, polyurethane and polyvinylalcohol (PVA) hydrogel were used as artificial cartilage materials. Synovia constituents, such as hyaluronic acid (HA) and serum proteins (albumin and γ-globulin) were added to saline and their effects on the tribological behavior were examined. As a result, HA and serum proteins exerted a great influence on the friction and wear of artificial cartilage materials. Friction and wear were reduced by HA solution, but were enhanced when serum proteins were added to the HA solution. AFM images showed that a layer of synovia constituents was adsorbed on the counterface, which changed the behavior of material transfer and the wear mechanism of artificial cartilages.

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In repetitive impacting of SUH 36 rings against rotating disks of two Fe-base sintered- alloys (PM A, PM B) in air, the effect of sliding speed, temperature and face shape on their wear rate was experimentally investigated. Very low wear rate was observed for all the materials subjected to impacts without sliding regardless the test conditions. The variation of the wear rate in oblique impacts with sliding speed and temperature was similer to that in plane impacts but the wear rate was slightly higher. The wear of rings against PM A was severe in some test conditions, but the wear of rings against PM B, which contains porosity and molybdenum acting as a lubricant, was always mild.

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The effects of an electric field on lubricating ability of sodium hyaluronate solution was examined using a reciprocating friction tester for a sliding pair of a conductive silicone rubber cylindrical surface and a stainless steel plate. Lubricants were water or saline solutions with different concentrations of sodium hyaluronate (HA). Remarked decrease in friction was observed with externally applied low-frequency alternating current (AC3V, f=10 Hz, sinusoidal wave) in comparison with high-frequency alternating current. The changes in tangential force showed that the externally rapplied voltage in the mixed lubrication region was capable of shifting the lubrication mode to a milder condition. Under the same applied voltage condition, water-solution lubricants were more sensitive to an electric field than saline-solution lubricants. These results suggest that adsorption to friction surfaces and movement of HA dissociated in a lubricant between surfaces appear to be controlled by an electric field.

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Cast iron is used as a sliding material for machine tools such as a lathe. To improve the tribological properties of the cast iron, we applied a plasma spray coating to the cast iron. In this study, the cast iron was coated with films of Al₂O₃ powder and a mixture of Al₂O₃ powder and Pb, Sn or Pb-Sn alloy powders. The softer metallic powders were expected to act as solid lubricans on the film surface. The frictional and were properties of the films were examined using a reciprocating tribometer. In the case of the Al₂O₃ film coating, it was found that the initial wear was influenced by surface roughness under both dry and grease-lubricated conditions; that is, the rougher the surface, the greater was the wear. For smoother specimens the wear was negligible under the grease-lubricated condition. The tribological properties in the case of the Al₂O₃ mixture film coatings were not as good as expected because the films were not strong enough.

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A hydrostatic bearing with pressurized oil supplied through an inner shaft was applied as a stern bearing of a 258 000 DWT tanker equipped with a contra-rotating propeller system. This paper presents the design method of this stern bearing and measurement results of oil film thickness, inner shaft center locus, inclination angle of inner shaft and temperature of the stern bearing during sea trial. It is confirmed that the stern bearing operates under full film lubrication in various operation mode, including high-speed straight run, high-speed turn, blackout and emergency sailing, and that estimated results of bearing performance, taking account of propeller forces, are in good agreement with measured ones.

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We analyzed the timing belt tension fluctuation of a V-6 engine and found that nonlinear resonance, which is not present in in-line engines, existed. In the study of thin phenomenon, we analyzed, through simulation, exactly how the belt tension fluctuated. This resulted in computed reproduction of subharmonic resonance, a kind of nonlinear resonance. In this paper, the generation mechanism of subharmonic resonance due to the tension in a V-6 engine belt is simulated, the belt spring which causes the subharmonic resonance is analyzed, and some cases of nonlinear resonance are presented.

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This paper describes an investigation of radial vibration caused by the outer ring waviness of a ball bearing. The analytical model is constructed with the following assumptions: Inner rotor is a single-degree-of-freedom vibrating system. The outer ring of bearing is supported by a soft rubber to insulate it from noise. A radial gap between the inner and outer races and a constant force caused by gravity (shaft and inner race) are assumed. The waviness function that generates a vibration is calculated. Each ball is assumed to move along this waviness function. From the analysis, the following results are obtained. The frequency of vibration is dependent on the rotational speed of a cage and the number of balls. The spectrum of each frequency is related with the number of waviness. The calculated results relatively well agree with the experiments.

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The more quickly robots move, the more frequently impact is applied to their mechanisms. Such impact makes control of robots difficult, and may even damage their driving systems. Therefore it is required to clarify the behavior of impact torque occurring at the input shafts of robotic mechanisms subjected to impact, and to establish evaluation methods of such behavior. We have already reported that the static characteristics of the representative robotic mechanisms change with the mechanism configurations. Therefore it is presumed that the impact characteristics of robotic mechanisms will also change with their configurations. We analyze the impact behavior of the representative open-loop and closed-loop robotic mechanisms subjected to impact load using a dynamic finite-element method to clarify the impact characteristics of several configurations of these robotic mechanisms. Based on the results, we describe the relation between the impact torque behavior and attitudes of each robotic mechanism. Furthermore, this paper proposes an evaluation method of the impact characteristics of the robotic mechanisms from their static characteristics.

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To handle a micromachine element and/or its parts, a micromechanical system is suitable. Thus, a pantograph mechanism is made from a plastic resin and superelastic hinges simultaneously by using a small injection molding machine. Superelastic hinges made of shape memory alloy have an effect of super-elasticity. Therefore it is possible for superelatsic hinges to have great bending displacements. The input and output displacements of the pantograph mechanism with superelastic hinges are measured and their linear relationship is confirmed. Then a micromechanical system for microbonding by adhesives is made from piezoelectric actuators, the pantograph mechanism and a needle. We confirmed that the proposed mechanical system performs well for microbonding by adhesives.

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The fixturing process for holding and locating workpieces on machine tools is essential in manufacturing systems. This process is one of the important factors affecting machining accuracy and has sofar been carried out manually by skilled workers. In order to realize fully automated manufacturing systems in the near future, particularly in small-batch machining and assembly, it is necessary to automate the fixturing process. One of the key factors in realizing an automatic fixturing process is to develop a fixturing support system. This system provides several important items of information for fixturing such as positions of fixtures and fixturing forces. In this study, a new fixturing support system is proposed. The elastic deformation of the workpiece caused by the fixturing force is analyzed by the finite element method, and the optimum fixturing position which gives the minimum form error of the surface to be machined is determined. The genetic algorithm is applied to the optimization process of the fixturing condition.

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The thickness of the oil film formed between two meshing gear teeth can be calculated on the basis of the elastohydrodynamic lubrication (EHL) theory developed by Dowson. The calculation of the EHL film thickness between meshing gear teeth is based on isothermal and steady-state conditions; in reality, non-isothermal and transient conditions predominate. Thus it is necessary that the film thickness calculated by the EHL theory be compared with the measured value. In this study, the elastohydrodynamic oil films formed between a gear tooth and a sapphire plate were measured by an optical interference method. The agreement between the calculated film thickness and the measured value is recognized under the condition of low velocity.

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Laser interferometry using the CCD image sensor is applied for the purpose of measuring form deviation of a gear tooth flank. The interference fringe pattern on the CCD image sensor for the target curved surface involves a thick density of fringes in the region outside of the optical axis, and it also contains a considerable amount of noise. It is therefore difficult to convert discontinuous phase data corresponding to the interference fringe into continuous phase data by direct application of the conventional data processing method. In this report, a new digital data processing method is introduced to develop a method for obtaining form deviation of the gear tooth flank. Tooth flank form deviations with longitudinal tooth lead crowning, helix angle deviation and pressure angle deviation were measured by this new method. The results are compared with those of the conventional method using a contacting stylus, and the accuracy of the new measuring method is discussed.

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This paper describes a new method for hourglass worm tooth modification using a CNC-hobbing machine. In the hourglass worm gear modified by this method, the worm tooth surface never contacts the mating wheel tooth surface at the end of worm tooth thread when the wheel tooth surface becomes worn. This modification method was applied to the design of an hourglass worm gear with arcuate tooth profile. In the case of tooth surface generation, the hobbing machine was controlled with an external control unit connected to a personal computer by using a manual handle interrupter attached to the hobbing machine.

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