To explain the mechanism of sound generated by flow field, this paper proposes an equation of acoustic energy conservation which consists in general flow field. The equation of conservation expresses law of acoustic energy conversions. From this equation, it bacame clear that following things generate or dissipate sound. (1) propagation (2) work by viscosity (3) interaction between pressure and heat variation (4) work generated by heterogeneous of mean flow velocity (5) high degree action generated by turbulent perturbation (6) dissipation accompanied by thermal expansion (7) dissipation accompanied by pressure loss (8) interaction between pressure loss and propagation of sound (9) action by non linerity of low degree sound. This conversion law and incompressible numerical simulation will make clear mechanism of sound generation.

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This paper presents a high torque ultrasonic motor operated by the traveling wave in a metal ring. Two degenerated elastic flexural modes of vibration, which are temporally and spatially orthogonal to each other to generate the traveling wave, are excited in the ring by the bolt-clamped Langevin transducers for longitudinal vibration. The prototype, composed of the ring, 140 mm in outer diameter, 100 mm in inner diameter, and 12 mm in thickness for the 7th flexural mode of vibration, and four 30-mm diameter Langevin transducers, was designed and tested. The maximum torque of 5 N·m was achieved with the maximum efficiency of 5.5%.

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It's commonly known that a frictional force between two sliding surfaces can be reduced to excite the ultrasonic vibration on the one side of a solid body surface. The low-friction effect due to the application of ultrasonic vibration remains valid for the friction between paper and metal as well as between metals. To make a frictional decrease mechanism clear, we observed the behavior of a solid body on the vibrated surface. In the case of a frictional force is zero, the levitation distance is as the same as theoretical distance. If the amplitude of vibration is decreased, the distance between the solid body and the vibrated surface will be also decrease, and frictional force will be raised.

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Acoustic Inkjet printing uses an acoustic beam focussed on a free liquid surface for drop ejection. This method can eject small drop without precise nozzle fabrication in comparison with thermal inkjet and piezoelectric inkjet. Fresnel lens was selected for focusing acoustic wave because of the precise and easy manufacturing by LSI process. The actual devise was made of Si wafer and characteristics of drop ejection was investigated. Furthermore sound field by fresnel lens was calculated using Rayleigh's Equation to be compared with the experimental results that showed good agreement. Finally it was proved that acoustic inkjet printing with fresnel lens is suitable for drop modulation by utilizing second harmonic focus.

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The purpose of this report is to clarify the behavior of single solid particles falling or rising in liquids with a standing wave field. The behavior of particles in degassed and ion exchanged water in the formation of a standing wave field was studied experimentally using an ultrasonic field of 45 kHz. In the experiment for particles falling in liquids, the decreased velocity of the glass particles in the ultrasonic field exhibited the greater deceleration In the degassed water, since the ultrasonic power effectively acts on a particle as a radiation force. In the case of the rising experiment, however, the greater deceleration of a particle is obtained in the ion exchanged water due to the motion of cavitaion bubbles. On the basis of this study, the falling velocity of a particle was analyzed numerically. The equation for motion of a sphere in a viscous fluid is based on the Basset-Boussinseq-Ossen equation, in addition to which, the acoustic radiation force must be included. The velocity of a particle is periodically changed due to influence of the radiation force of the standing wave. The terminal velocity of a small particle in an ultrasonic field is lower than that for which there is no ultrasonic field.

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By applying ultrasonic vibration, the coefficient of heat transfer on the pyrogen surface in a liquid increases remarkably. This depends on the agitating effect of cavitations and acoustic streaming. Heat transfer enhancement by cavitations is influenced by the bubble nuclei that randomly exist in the water. In this study, the method for controlling the position of the jet by acoustic streaming is proposed. Changing the phase of the applied voltage on the four sheets of ultrasonic vibrators can control the peak position of radiation force. It is shown by the theory that the position of streaming tends to avoid the surface of ultrasonic vibrator the phase of which is later than others. The positioning control on plane normal to the flow direction is possible by using this tendency. And experimental results coincide with the theoretical predictions.

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As a non-contact maicromanipulation technique, it is possible to trap particles in water at nodes of an ultrasonic standing wave field generated between a transducer and a reflector and to transport them using a frequency-shifting operation. Since there are several problems coming from resonance of the sound field with this scheme, the authors proposed a novel manipulation technique for particles using a standing wave field generated by two transducers whose sound beam axes were crossing to each other and accomplished one-dimensional manipulation of a polystyrene particle. The present paper describes an extension of this method adding one more transducer, which realizes two-dimensional manipulation suppressing unstable motion observed in the one-dimensional operation. Experiments in water using polystyrene particles confirmed the principle of the two-dimensional manipulation and agreed well with a numerical analysis of the sound field.

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This paper deals with the development of a new method for detecting the number of cloth without contact. It is necessary to detect one or plural number of sheets to avoid mishandling. This detecting sensor utilizes the variation of the phase of the transfer function within entire acoustic system. The incident impedance of sheets varies with the number of sheets. Characteristic acoustic impedance and complex wave number define peculiar and most fundamental characteristics of the material. It is useful for the detection of the number of cloth to know characteristic impedance of cloth. So that, we tried to measure characteristic impedance and wave number. The measured impedance of sheets by the transfer function method was introduced into theoretical analysis. The results of the experiments and theoretical analysis show fairly good coincidence

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The navigation method of an indoor mobile robot by active ultrasonic beacons is proposed. 2 receivers on a robot measures the time-of-flight of the ultrasonic pulses from 2 beacons on a ceiling to estimate the robot's 2 D position. This is reliable and safe localization system which can be used in human-robot coexisting environment. Since the distances from only 1 beacon can be detected at once, position should be estimated with robot's movement in a measurement interval during navigation. A moving robot should select the pair of beacons used for position estimation among many available beacons. Detection of wrong position sometimes occurs due to the interruption of ultra-sonic pulses by obstacles and humans in the real environment. For solving these problems, the dynamic position estimation, the selection of beacon pair according to position accuracy, and reliable navigation method with dead-reckoning in the real environment are discussed.

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As is well known, the extraction of the extraordinary signal, embedded in high-level white noise, is usually very difficult. In this paper, we suggest a new detection method for extracting such extraordinary signal by using wavelet transform, which we call Wavelet Pattern Matching. Our approach proceeds as 1) transferring signals from one dimension of the time series to two dimensions of the time-frequency plane by using wavelet transform, and analyzing the frequency characteristics of the signals ; then making a template based on the characteristics of the signal. 2) analyzing the objects and extracting the extraordinary signals by using Wavelet Pattern Matching. The method is proved to be effective when a model signal is used to test its effect. The effectiveness of this method becomes clearer when it is applied to extract the braking sound of an automobile embedded in high-level noise and knocking detection.

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To reduce the underwater radiated noise from the ship structure, there is a method to apply damping materials on the hull plate. The problem with damping treatment is that they are relatively heavy and bulky and the amount of the damping materials must be minimized for the application on the ship structure. However there are too many selections to determine the best answer to minimize the amount of damping materials and it is very difficult to find an exact solution for this problem by the traditional algorithm. This paper presents the application of the genetic algorithm for finding the optimal vibration damping on the hull plate of the ship structure.

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In this paper, shoes sounds at walking are investigated. Their sounds may show individual walking characteristics. So we can recognize someone coming and one's physical or psychological condition by the time history pattern of their sound pressures. Their sounds are different by walking style, and there are two strong sound pressure waves at one step. The first one is a wave at heel touching down the ground and the second one is a wave at the front part of shoes getting down the ground. We study on the source of the shoes sound. The vibration generates by a collision of the shoes sole and floor, and transfers to the shoes skin. The sound radiates from the shoes skin parts. And, it is investigated that the shoes sound includes air compressing sound. Using their patterns and frequency characteristics of the sound pressures, we can understand who comes up and what is one's condition.

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In the room where noise exists, we try to employ the masking effect in the sense of hearing to change the sound environment and reduce the stress due to indoor noise in work. Considering 1/f characteristics, we prepare four kinds of maskers and efficiency tests are carried out based on Kraepelin test. The exsitence of the masker increases the work amounts and may reduce the mistakes in work. The results show that the use of the appropriate masker yields the improvement of the work efficiency.

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This paper presents a dynamic model of "Kansei" for musical chord progression using a recurrent neural network. The three-layered network is constructed based on the structure of auditory sense. The input is a time series of musical chord progression and a two-dimensional vector of Kansei information characterized by "cheerfulness-gloominess" and "stability-Instability" is outputted in real-time. After training the network, the analysis of synaptic weights of all the units gives the following results that agree well with the knowledge of psychology and physiology. 1) The "cheerfulness-gloominess" and "stability-instability" are influenced by the units that have acquired the characteristics of critical bandwidth corresponding to musical tone frequencies. Furthermore, the synaptic weights prove that "Tonality" works on the Kansei information. 2) Of six units in the hidden layer, three units are autoregressive, which result agrees well with the knowledge that sustained type and onset type neurons exist behind the cochlear nucleus. 3) In the output layer, the outputted Information is fed back to the non-outputted unit. Such a feedback circuit exists between the medial geniculate body and the auditory cortex.

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Three-dimensional Helmholtz equation is one of the important differential equations in engineering. It appears in problems of acoustics, heat conduction and so on. If a domain has an arbitrary shape, the problems cannot be solved by the usual analytic procedure. On the other hand, approximate methods such as the finite element method are not necessarily sufficient for this purpose. This paper deals with a new method of analysis that is based on analytic solutions. In this method, boundary conditions are satisfied approximately at points located on surface of the domain. Eigenvalues and eigenmodes of some domains of revolution, an ellipsoid, a boxy domain and a frustum of pyramid are calculated as numerical examples. Results have good accuracy.

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The finite element method is used to investigate the steady-state vibration of uniform, slender beam with the geometrical nonlinearity. The nonlinear strain-displacement relations are employed and the in-plane displacement in middle plane is included in the model. The equations of motion are derived by applying the principle of virtual work. Reduced-order model is derived by introducing modal co-ordinates and the modal matrix which consists of eigenvectors of the linear eigenvalue equations. If we use an in-plane mode and an out-of-plane mode, we can obtain single d.o.f. equation of motion by neglecting the in-plane inertia, and the present numerical results are compared with theoretical ones.

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When an asymmetrical shaft is supported by single-row deep groove ball bearings, nonlinear spring characteristics appear due to clearance of bearings and the stiffness of support at the shaft end differs depending on the direction because the equilibrium position of the shaft center line shifts from the center of the clearance due to gravity and misalignment of assembly. Due to the coexistence of the rotating difference in shaft stiffness, the static difference in stiffness at bearing support and the nonlinear spring characteristics, various kinds of nonlinear parametric resonance and nonlinear forced resonance occur. In this paper, we studied vibrations of harmonic type and super-combination type. As a result, we clarified the following phenomena, such as, division of unstable range, convergence of an unstable vibration to a limit cycle, resonance curve of a hard spring type, and coexistence of a forward and a backward frequency components.

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This paper describes a rocking earthquake response analysis method of traveling cranes, which alternates the natural vibration modes in the state of legs lifted and that of all legs contacted with rails. For wheels landing on rails, the method assumes the inelastic collision that satisfies conservation of momentum related to the natural vibration modes in the state of all legs contacted with rails. By this approach, degrees of freedom for analysis become small and we can easily examine the rocking behavior in a design stage by parameter changes. Shake table experiments were carried out with a crane model that has natural frequencies of about 10 times that of actual cranes. The calculations of free rocking response, sine wave response and earthquake wave response for the carne model using the first and second order natural vibration modes were shown to be in good accordance with the experiments.

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This paper describes slippage of power transformers as caused by earthquakes. Some power apparatuses were destroyed by the Great Hanshin Earthquake in 1995. One cause of damage was the failure of anchor bolts which led to slippage of power transformers from their concrete foundations. The forces applied to the anchor bolts and displacements of power transformers by the slippage are affected by not only the horizontal component, but also the vertical component of the earthquake. In this report, vibration analysis was carried out using various earthquake waves. Slipping conditions of a transformer under both horizontal and vertical components of an earthquake movement were clarified. It was found that the effect of the vertical component on slippage of the transformer was not so large.

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At present, we have been studying inclination composition in the 2-component powder for the purpose of the molding of functional gradient material using the powder mixing method. It is a very important objective to quantitatively evaluate the material dispersion state, when the material combination is studied in this condition. Therefore, in this research, quantitative evaluation of mixed state was focused. The photos of the cross section of the test piece were received by vertical vibration. Also, rate of change D of mixing degree was calculated by Fractal technique. Thus, the value D was determined from the photograph. As the result, this technique is effective for the quantitative evaluation of the mixed state of the powder. And it was proven that ratio of change D of the mixing degree would show large value, as the mixed becomes good.

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This paper describes a study on an inverse analysis method to identify the crack parameters of nonuniform beams by the simple genetic algorithm. The crack is simulated by an equivalent rotational spring model. By using this approximate model, a characteristic equation to calculate the natural frequencies of the system are derived employing the Rayleigh-Ritz method. In order to identify the crack location and the depth of the beam from frequency measurements, objective function that consists of the sum of square errors of frequencies is formed. The genetic algorithm is used to search the minimum value of the objective function. The proposed method is verified by the numerical simulation of some sample problems.

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This paper is concerned with a quantitative nondestructive evaluation of using superconducting quantum interference devices (SQUIDs). A mathematical model of the nondestructive evaluation system is described by a three dimensional eddy current model. The forward analyses using the finite element model are implemented for conducting materials with a depth-varying crack. A computational method based on the genetic algorithm is proposed for recovering internal defect profiles with SQUID data.

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There is a possibility that a rotor equipped with slender pendulums and flexible booms exposes a risk of its intense self-excited whirling and its attitude instability in a certain region of rotation speed. In previous paper we analyzed and experimented dynamic stability of a translation whirling motion of a rotor equipped with cantilever beams. We obtained the following conclusions by neglecting of an effect of centrifugal force acting on the beam. The system can become unstable when a rotational speed of an axis is nearly equal to a sum of the critical speed of a rotor without beams and the first mode natural frequency of a beam. Any higher mode vibration of a beam does not cause a self-excited vibration in the system. A mode of vibration of a beam changes under centrifugal force when the rotor is rotating. In this paper we investigated the natural mode under the force and how the change of the mode exert an influence on instability of the system, by using the Galerkin method and the Order N method developed by one of the authors. It was found that even the unstable region of the system, which is simply derived from the neglect of an effect of the centrifugal force, is accurate enough for practical purposes.

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The electrostatic force acting on a pin electrode in a pin-to-plate corona discharge system was measured and numerically calculated by a static unipolar model. The model neglects the effects of diffusion and convection of charged particles. It is assumed that generation of ions takes place on a tip of the pin electrode and that surface electric field is less than the onset field of corona discharge. Numerical calculation, s were conducted using an iterative finite element method. Calculated voltage-current characteristics of the positive corona qualitatively agreed with the measured result that the corona discharge took place over a threshold voltage and the current was in the order of several ten microamperes. Trichel pulse was observed in case of negative corona and the negative corona current was large compared to the positive corona. Vertical electrostatic force was also measured and calculated. Although extremely small electrostatic pull force was induced if discharge did not take place, the force became repulsive and relatively large when the corona discharge took place. Force in negative corona was almost same with that in positive corona. Calculated force without discharge agreed with the measured but the calculation did not simulate repulsive characteristics at corona discharging. Convection of air must be included in the model. Effect of lean of the pin electrode has been also investigated. The present investigation is expected not only to realize a new ozone-free charger but also to clarify quantitative mechanisms of the bead carry-out in the magnetic brush development subsystem of electrophotography.

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The conventional fuel injector for direct-injection gasoline engines is driven by voltage step-up circuitry and current control circuitry. The voltage step-up circuitry boosts the battery voltage to near 100 volts. This conventional system is fairly large and a more compact system is preferable. We have developed a mass producible battery-voltage-driven fuel injector for direct-injection gasoline engines. The injector has a dual-coil structure that enables the injector to operate at the battery voltage, thus eliminating the need for either voltage step-up circuitry or current control circuitry. Deviation in battery voltage and changes in harness resistance are fully compensated through opening-coil energization-time control. In addition, with this control method, the injector can be used with a wide range of fuel pressures. In this paper, the design concept and the dynamic characteristics of the battery-voltage-driven fuel injector with a dual-coil structure and the opening-coil energized-time control method is discussed in detail.

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This paper mainly focused on the control performance and mechanism of the sorting machine which is recycle system equipped with parallel wire driven mechanism. The sorting machine has the nozzle which can rotate around direction of two axes and recycled objects are separated through the moving nozzle. The transition of the Jacobian matrix, centrifugal force and Coriolis force caused by the high speed movement of the nozzle are defined as disturbance to the control system. H_∞ controller is applied to suppress the disturbance and improve the robust stability at the same time. The control performance is verified through experiment using a real model, and the effectiveness of the proposed sorting machine is shown.

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This paper proposes a dynamic vibration absorber with a differential pulley for a shorter elongation of spring. The spring of this dynamic vibration absorber is connected to the inner radius of differential pulley and a rope is wound around the outer radius of it. This mechanism makes the elongation of spring shorter than the stroke of absorber mass. By using this mechanism we can make a compact dynamic vibration absorber, and it is easy to install it to the real system. This dynamic vibration absorber was applied to a pendulum, which was a simple model of a ropeway carrier, and experiments were conducted to validate theoretical results. The optimal damping coefficient and frequency ratio of the dynamic vibration absorber for free vibration were derived analytically and these values were used to computer simulation and experiment. Their agreement of both of them was good in general. Furthermore, power spectrum of wind velocity proposed by Davenport was used to simulate the time history of natural wind velocity and the effect of this new device was evaluated experimentally.

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The optimal placement method or procedure of a storey-installation type damper for the vibration control of structures and buildings has not yet been established though the devices them-selves are developed actively. Therefore, in most cases, these dampers have been installed uniformly in each storey of the building. However, it can be thought that this method is not so much effective in reducing vibrations in the structure because the significant difference in the absorbed between lower and higher storeys is produced. This study attempts to apply the genetic algorithm (GA) to determine the proper distribution for the storey-installation type damper rapidly and easily. In this paper, multiple conditions are satisfied by applying multi-objective optimization theory in the evaluation function of GA. Then, GA also decides the proper number of device to mitigate the vibration considering the economical requirements to cut down the cost of using the dampers.

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This paper deals with suppression characteristics of sloshing in a rectangular vessel by a bulkhead which divides the vessel vertically into two sections. The sloshing mode is separated into two modes by the bulkhead ; the one is the sloshing mode of liquid column in a U-tube, and the other is the sloshing mode in the separated tank. The effect of aperture height of the bulkhead and exciting amplitude on the suppression characteristics of U-tube mode sloshing is examined experimentally. And the flow patterns of the fluid In the vessel are visualized. As a result, following phenomena are clarified. (1) There are three types of flow pattern. The one is the flow pattern (A) with unsteady vortexes, and another is the flow pattern (B) with single swirl and a vortex, and the other is the flow pattern (C) with twin swirls. (2) The flow pattern changes from pattern (A) to (B) or (O with increasing the exciting amplitude. (3) The damping ratio of the sloshing with the bulkhead is much larger than that without the bulkhead. (4) The damping produced by the bulkhead is dependent on the exciting amplitude and it's damping ratio increases with increasing the exciting amplitude. (5) The flow pattern plays an important role for dissipation of the energy of the sloshing. In particular, the vortexes and swirls increase the energy dissipation of the sloshing.

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This paper deals with a theoretical stability analysis of flow-induced waves induced in a flexible circular ring subjected to swirling fluid flow. In the stability analysis, wave equation of the system is derived from the equation of motion of the flexible circular ring coupled with the swirling fluid flow. The equation of motion of the flexible circular ring is based on the Kirchhoff-Love's thin-plate model and the equations of motion of the fluid flow are based on Navier-Stokes equations. The dispersion relation of the waves are calculated as a function of the ring rotational speed. As a result, the analytical results show that unstable wave occurs in the circular ring due to the swirling fluid flow and clarifies the traveling-wave speed and the growth rate of the flow-induced waves.

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The damping effect of an impact damper with granular materials in a vertically vibrating system is studied both experimentally and analytically. The motion of the damper is solved by Discrete Element Method (DEM), which is often used in the investigation of soil mechanics and powder technology. Mechanical elements like springs, dashpots and frictional sliders are used to express the contact force. It is shown that the performance depends on the particle radius and the damper geometry as well as various physical parameters. The validity of the numerical method is examined by comparison with experimental results.

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Bending vibrations of outer shells often cause serious problems. The shells cannot be always reshaped because the product style depends on them, and it is necessary to deal with coupled vibrations with inner structures to eliminate the problems. This paper demonstrates a FEM analysis of adjusting the coupled vibrations. In case of an automotive roof panel, FEM model determined by drawings, welding stiffness rate, and stamping thickness rate are contrived to simulate the roof vibration experiments. The analyses indicate that modifying rear inner structures contributes natural frequency increase more than 10%, and reinforcement and closed section of the rear inner panel and the outer panel is the most effective.

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This paper presents a new sliding mode controller based on the theory of model following control for semi-active suspension systems with Magnetorheological (MR) dampers which have undesirable nonlinear properties. In the proposed controller, a desired semi-active suspension system is chosen as the reference model to be followed, and the control low is determined so that an asymptotically stable sliding mode will occur in the error dynamics between the plant and the reference model states. The advantages of the proposed controller are : (1) measurement of the damping force is not required, (2) the reference model specifies the desired performance considering the passivity constraint of the damper, (3) it is highly possible to maintain the sliding mode and achieve high robustness against the nonlinear properties of the damper. Numerical simulations illustrate the effectiveness of the controller.

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In this paper, we consider a simultaneous optimization problem in which the design parameters of a controller and mechanical structure are simultaneously optimized. This problem is generally formulated as the nonlinear optimization problem for the design parameters of structure and controller. Therefore, it is hard for us to obtain an analytical solution. In this paper, we parameterize all passive parameters of mechanical structure such that the parameters work in the control system like as static output feedback gains. Using this parameterization, we have formulated a simultaneous optimization problem of structure and control systems, and proposed a new performance index. We propose a numerical optimization method to solve the formulated problem, which is based on the necessary condition for controller parameters and the performance sensitivities with respect to passive parameters changes. We can surely obtain a local minimum solution for the defined performance index. A numerical example is given to illustrate the procedure of design and the effectiveness of simultaneous optimization.

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This paper presents control system design for regulating plasma position in Tokamak fusion reactor. The dynamics of plasma position in fusion reactors is essentially unstable ; therefore, the feedback control is required for regulating the plasma position. In the control system, magnetic force is applied to the plasma for regulating when a disturbance comes to sift the plasma position from the equilibrium. The voltage, which is applied to the poloidal coil for producing the magnetic force, is limited to a certain value because of the physical conditions of fusion reactors. The set of disturbances, which are allowed to regulate within the limit of supplied voltage, is clarified in this paper by using the principle of matching. A new method is proposed to obtain a wider class of allowable set of disturbance based on the Youla parameterization of all stabilizing controllers.

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In conventional vibration testing, measurement of frequency response function (FRF) has been limited to translational degrees of freedom (DOF). Rotational DOFs have not been treated in experimental analysis. However, the rotational DOF is indispensable in further analysis, such as substructure synthesis, prediction of structural dynamics modification, etc. FRF measurement on rotational DOF is essential for expanding applicability of experimental modal analysis. This paper proposes a new method for FRF estimation on rotational DOF of structures. The following is the estimation procedure : a rigid block is fixed on the measurement point of structure ; the block is excited by conventional impact hammer, the inner force and the response of the connection point are estimated ; and lastly, the FRF including rotational DOF at the connection point of the structure is obtained. The feasibility of the method is investigated experimentally by applying it to a beam structure. The method is applied to structure synthesis approach by using experimental models.

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The discharge-type blade tip clearance measurement system has a high accuracy and characteristics as a standard reference device. However, this method can not measure the tip clearance of all blades nor the maximum tip clearance. Therefore, such measurements were attempted in this study. The principles for measuring the tip clearance of all 'the blades are as follows. The electrode is brought near to the tip of the blade and discharge occurs at the longest blade, then the movement of the electrode is stopped. Next, the applied voltage is increased until all the blades are in a discharging state. The gap of each blade can be measured by identifying the order of discharge at the blades and the discharge voltage at each blade. The principles for measuring the maximum tip clearance are as follows. In the same manner as the above method, the electrode is brought near to the blade tip and discharge occurs when supplied voltage is increased. Under this condition, the current corresponding to the supplied voltage is measured. The measured current curve has an inflection point. The inflection point corresponds to the minimum current where the discharge of all the blades occurs. The maximum tip clearance is determined by converting the measured voltage of the inflection point into length. The operations of these methods are automated.

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Because of the increased recording density of optical disks, it is widely demanded methods for estimating mechanical characteristics of the optical disk such as displacement and inclination. This study relates to a method for measuring a multi-dimensional displacement that measures not only displacement, but also tangential and radial inclinations of the optical disk transmitting laser light simultaneously. We propose a differential optical detection method using a pair of quadrant opto-electronic detectors placed at the conjugate positions of the focal plane of a detection lens, and an optical system using a spatial filter for splitting reflection from a surface of a recording layer and a surface of a transparent substrate of the optical disk. The optical system is not effected on a defect of the substrate surface. The optical head for an experiment was prepared in a simulation of the optical system with ray tracing. The experiments have shown that the principle of the method is useful for measuring the multi-dimensional displacement of the optical disk.

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Relative position measurement using Differential Global Positioning System (DGPS) and inter-vehicle communication is proposed and evaluated. Relative position information of neighboring vehicles is expected to enhance Advanced Vehicle Control and Safety Systems (AVCSS) and to improve reliability of sensor information such as inter-vehicle distance. This paper proposes a method of acquisition of relative position information accurate and real-time enough to be used for the above application. The proposed method is evaluated by experiments using two vehicles. Experimental results show that the proposed method makes it possible to acquire accurate and latency-compensated information at a short sampling period.

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In order to realize a power assisting suit for assisting a nurse caring a patient is her arm, a hardness sensor of muscle using load cell and a pneumatic rotary actuator utilizing pressure cuffs have been developed. The power assisting suit consists of shoulders, arms waist and legs made of aluminum, and is fitted on the nurse body. The power assisting suit was originated with the concept of a master and slave system in one body. The arms, waist and legs have the pneumatic rotary actuators. The pneumatic rotary actuators construct with pressure cuffs sandwiched between thin plates. The action of the arms, waist and legs of the nurse were sensed with the muscle hardness sensor utilizing load cell with diaphragm mounted a sensing tip. The dent of the sensing tip corresponds to the hardness of the muscle so that exerting muscle force produces electric signal. This paper gives the design and characteristics of the power assisting suit using the cuff type pneumatic rotary actuators and the muscle hardness sensor verifying its practicability.

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On the assumption that the exact model of manipulators is never known and only the estimated model is obtained with some errors, a new robust and a new adaptive robust control schemes are proposed to achieve the specified tracking precision. These schemes are derived based on Lyapunov stability theory. The robust control needs the upper bound of errors between the estimated model and the real one, and then it uses a relatively high gain feedback. The adaptive robust control does not need the error bound, but it makes an on-line estimation for the feedback gain. It is an improvement on traditional methods to relieve a problematical assumption. Comparing with adaptive control scheme, In which all the physical parameters are on-line estimated, the adaptive robust control is robust to unexpected disturbance. The effectiveness is verified by experiments.

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In this paper, we apply the method of a sampled-data H_∞ control to the robust digital control of a magnetic bearing system. At first, we discuss the construction of the generalized plant which achieves the robust stability for the unmodeled dynamics and the nominal performance to the sensitivity function. By using this generalized plant, a digital controller is directly obtained by using the sampled-data H_∞ control theory so as to minimize L₂ induced norm from w(t) to z(t). The obtained performances of the sampled-data H_∞ controller are compared with that of the conventional type controllers by the experimental results, and the effectiveness of our proposed method is shown.

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SCARA robot motions generally consist of the following two motions : One is horizontally transportation of a load by actuating two revolute joints. The other is vertically transportation of a load by actuating a prismatic joint. In our previous paper, we have proposed a new adaptive control method for the former motion with vibration suppression of the prismatic joint. Since the method, however, cannot compensate static friction terms, positioning error of the revolute joints may not be permissible when the effect of the static friction is significant. In this paper, we propose a new adaptive control method with integrator for reducing the positioning error. Since the controlled object is modelled as a double-input quadruple-output system, it is difficult to consider both the introduction of integrator and the robustness with respect to estimation error of the mass of the load. To overcome this difficulty, we apply a coordinate transformation by which the controlled object can be dealt with as two single-input double-output systems. We can separately design robust controllers for the two decoupled systems. The effectiveness of the proposed method is demonstrated through experimental results.

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The previously proposed information-sharing-type interface named the multimedia communication pendant (MC pendant) has been given an improved interface function and has been implemented into a modular system structure. Using the MC pendant, the operator sets the suitable robotic motion as well as the situation-dependent sensor-process parameters by sketching a profile over a graphical display of the shared sensor data. This requires only a simple pattern-recognition ability. The modular structure enables it to be applied to various robot systems. Experiments showed that novice operators with no special task knowledge can set appropriate sensor-process parameters for the given task conditions.

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We applied H_∞ control theory to design a head-positioning servo system of a magnetic disk drive from the point of view of loop shaping. This H_∞ control theory, called "Loop Shaping Design Procedure (LSDP)", was used to shape the transfer function of this closed-loop system. And, to obtain a good transient response characteristics after it switches the servo system to following mode from seek mode, we applied initial value compensation (IVC) to the servo system. We also measured closed-loop frequency characteristics and track seek response experimentally, and these measurements show that LSDP can provide a good system design with adequately balanced robust stability and disturbance suppression characteristics. Moreover, IVC can produce good transient response characteristics with less overshoot after mode switching.

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In recent years, an articulate-type steering mechanism is practically used for off-road vehicles. Articulated vehicles carry advantage of steering characteristics in small area as compared with Ackerman-type steering vehicles. In this papar, we consider articulated vehicles equipped with four triangular track units instead of conventional tire wheels for more trafficability on soft ground. In order to clarify the characteristics of turning motion of the vehicle, the equations of motion have been constructed including the deviation of the mass center from the geometrical center and gravitational terms on sloping ground. Numerical analyses have been conducted for various running conditions solving the equations of motion. For the validity of the mathematical model, the numerical results were compared with scale model experimental data.

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Handling performance of heavy duty vehicles are influenced by bending and torsional motions. The steering frequency responses and sensitivity analysis for an open loop system are discussed. By the closed loop analysis under preview steering model, a handling performance index is proposed and then equivalent body rigidity and tire cornering stiffness, etc, are analyzed to improve stability and handling quality. The index is composed of the mean square values of the course deviation (task performance) and the steering wheel angle (driver's work load). Consequently, arbitrary design parameters can be easily optimized by minimizing the index, i. e. expanding the safety drive zone.

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Kalker's FASTSIM program and variation of contact ellipse were introduced for curving simulation of a non-pendulum rail vehicle. Digital simulations of curving for a representative example were made. It was shown that spin creepage increased steady value of lateral wheel-rail force by 28% and decreased dynamic value when passing random track irregularity by 11%, while variation of contact ellipse decreased steady value by 7% and increased dynamic value by 3%. It was also shown that spin creepage plus variation of contact ellispe increased maximum value (steady value plus dynamic value) by about 10%. A method of curving simulation considering almost all important factors was established by this report and the previous report⁽¹⁾

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