The friction coefficient μ on the contact point position between a wheel flange and a rail is said to seriously affect on the occurrence of the wheel-climb derailment. However, the method to quantitatively and exactly evaluate the μ has not suggested until to the present. The authors proposed a method to easily and exactly evaluate the value, and made it clear by an experiment, employing a 1/5 scale model track and model truck. The result obtained through the experiment indicates that the value on dry rails has a similarity with that of the adhesion coefficient, and that the dry rail on the main line keeps the value at high level. Using the μ value obtained by the studies, the risk of the wheel-climb derailment was evaluated. As the result of the evaluation, they found that higher μ value than the conventionally used one should be introduced for the risk evaluation of the derailment, and that very short term lateral force below 60 ms should be observed on the steep curvatures.

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This paper presents experimental results on chaotic vibrations of a thin circular plate with a circular center hole. The plate is clamped around the outer edge by rigid rings. Asymmetric deflection of the plate is induced by initial imperfection and in-plane compressive stress due to thermal elongation of the plate. Two natural modes of vibration with one nodal diameter are generated in each natural frequency. These nodal diameters are perpendicular to each other. Under periodic excitation, a dominant chaotic response generated due to the type of one-to-two internal resonance in a specific frequency range. The chaotic response is inspected by the Fourier spectrum, the Poincare projection and the maximum Lyapunov exponent. The principal component analysis is adapted on the chaotic response to confirm modal contributions. The multiple time responses of the plate are measured at four positions simultaneously for long-time interval. The modes of vibration without nodal diameter and the two modes with one nodal diameter contribute to the chaotic response, predominantly. Furthermore, changing the calculation of principal component with short-time interval, the chaotic response of the plate shows the motion of irregular traveling waves.

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This paper investigates influence of in-plane vibration on building SEA model for flexural vibration on plate structures. This study uses a simple plate system composed of two flat plates connected in an L-shaped configuration. FEM calculation is carried out for the comparison of the SEA loss factors concerning flexural vibration in two SEA models with and without taking the in-plane vibration into consideration. The differences in the SEA loss factors concerning the flexural vibrations occur in frequency bands corresponded in natural frequencies of in-plane vibration on the unconnected plates. The subsystem energy averaged both in frequency and in space also shows the influence of in-plane vibration. As a result, a new method has been developed to evaluate the influence of in-plane vibration on the built SEA model for the flexural vibrations. It is demonstrated that the method is useful to identify the frequency bands affected by the in-plane vibration and how the loss factors are under- or over-estimated.

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This paper verifies the expressions for power input and subsystem energy by modal density of subsystem in Statistical Energy Analysis (SEA) by means of FEM calculation. First, vibration response in the modal form is used to derive their expressions. It is shown that the employment of average in space and frequency for the power input and subsystem energy of the subsystem can be expressed mainly by the modal density. Coupling loss factor between plate subsystems is also analytically estimated by using the wave theory and is determined mainly by the modal density. In order to verify their modal density descriptions, FEM calculations are performed to compare subsystem energies, power inputs and coupling loss factors on three kinds of structures with different subsystem shapes with the same modal densities. The analytical SEA predictions are also compared with the FEM calculation results.

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An improved averaging method is proposed in order to obtain a highly accurate periodic solution composed of only odd order harmonics in a strongly nonlinear dynamical system. In this method, sum of the Jacobian elliptic cosine (cn) and sine (sn) function is incorporated as the generating solution. The proposed method is applicable to relatively general nonlinear systems based on Duffing equation. The stability of the solution is analyzed by obtaining the characteristic multipliers of the variational equation. The numerical results for typical nonlinear oscillators are shown. The effectiveness of the proposed method is verified by comparing the computational results with those obtained by the shooting method.

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Recently, active vibration control devices are widely used in many industrial fields. These are categorized into the following two types with their mechanisms. (A) Vibration is controlled by actuators whose one ends are connected to the controlled object and the other ends are connected to “the fixed floor or reaction walls”. (B) Vibration is controlled by actuators whose one ends are connected to the controlled object and the other ends are connected to “the movable mass”. Typical devices of (A) are active vibration isolation devices. The advantage of type (A) is excellent vibration control performance. However, it is difficult to downsize the devices, because the actuator has to support the controlled object. Meanwhile, typical devices of (B) are active mass dampers (AMD). In type (B), since the actuator doesn't need to support the controlled object, it is possible to realize compact systems. However, the control system design of type (B) tends to be complicated, especially for multi-axis plants. In this paper, we propose a new vibration control system design concept called “Direct Inertia Force Control (DIFC)”. By using the DIFC, we can achieve the advantage of the type (A) and (B) simultaneously. Also the DIFC is able to cover the disadvantage of (A) and (B) cited above. Furthermore, the effectiveness of the DIFC is verified by using a newly designed one-degree of freedom active vibration control device, in experiment.

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Congestion due to an irregular flow of people has been commonly observed at various spots. Congestion increases unpleasantness and may cause trouble. Moreover, it may lead to a serious accident such as a sudden collapse of the overcrowded structure of people. In order to understand the mechanism of congestion due to the irregular flow of people, we performed a multiagent simulation of the flow, which can be used to analyze various systems of complexity. First, we performed simulations between individuals and simulated the crowd as an application. We simulated lane formation that was a characteristic of the flow of people at a congested state. Then, we simulated the flow of people in the catwalk of a station. It was shown that features of congestion were changed by the positions of obstacles such as columns.

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In machine dynamics, impacts may occur by interaction of solid bodies. The method of multibody system is commonly used for the dynamical analysis of the overall motion of bodies. However, energy is lost during impact macro mechanically and it must be measured by the coefficient of restitution. This coefficient has to be estimated from experiments and experience but cannot be derived within the framework of multibody system approach. Experimental works for the impact of two spheres have been treated by many researches so far. Also there are several approaches to extract parameters for impact modeling. Theoretical developments for impacts have started from the methods based on Hertz theory of contact and impact. Then they are applied and extended to non-elastic impacts, such as viscoelastic and elastic-plastic impacts. Detailed impact simulations by using finite element simulation are carried out these days. However, relationship between material properties and the coefficient of restitution has not been understood enough yet. Especially, the effects of strain rate sensitivity of materials have not investigated so much. Therefore, in this paper, the longitudinal impact of elastic sphere against circular rod with strain rate sensitivity was investigated. Then the behaviors of strain rate dependent objects during impact are precisely measured by using Laser Doppler Vibrometer experimentally, and the effects of elastic wave and strain rate sensitivity on the coefficient of restitution are investigated by using finite element simulation.

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This paper presents a new control system based on sliding-mode control (SMC) for large-scale processes with large time delay and nonlinearity. The proposed control system consists of a gain-scheduled sliding-mode controller and a nonlinear state predictor, all predicted states after time delay will be locked in a future sliding-mode after time delay by switching of the controller. A model of complex nonlinear processes is defined as the set of simple linear systems (first order lag and time delay with time-varying parameters) under preset process conditions. The advantages of the proposed method are 1) good transient characteristics by one-degree-of-freedom control system, 2) high robust performance against an unknown disturbance, and 3) simplicity in designing for such processes. The proposed method does not need complex calculation or optimization like nonlinear model predictive control. Experimental results illustrate the effectiveness of the proposed method with applying to a CZ (Czochralski) silicon single crystal puller with large time delay 30 minutes.

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This paper is an analysis of the investigations regarding the responses of the controlled inverted pendulum to vertical oscillations. First, the inverted pendulum is stabilized by the optimal controller. Next, with theoretical analysis and numerical simulations conjoined with experiments using the large scale vibration exciter, the effect of the vertical vibration on the stability of the inverted pendulum is examined. The results show that the system dynamics is governed by the Mathieu equation. This being so, the frequency response reaches its peak when the frequency of the forced vibration is twice as high as the natural frequency of the controlled inverted pendulum system.

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This study aims at achieving simultaneous realization of ride comfort and steering stability in the controller design for semi-active suspension considering the most sensitive frequency range of human body and vehicle behavior at steering. In this study, a method which can improve both the ride comfort and the vehicle stability is proposed by separating the control range in terms of frequency domain, where the frequency weightings on the controlled variables are used. Furthermore, the controller is scheduled in time domain in order to realize the positive pitch angle mode at the slalom. In this study, the dynamics of road disturbance is supposed and is accommodated into that controller to make the control performance more effective. In order to investigate the effectiveness of the proposed control system, the computer simulations are carried out by using a full vehicle model which has variable stiffness and damping semi-active suspension system. As a result, it is demonstrated that the proposed method can realize improving the ride comfort, reducing the vehicle motion, and synchronizing the roll and pitch angles caused by steering.

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A railway is organized by a variety of individual technologies, and functions safely and properly as a system, therefore it is necessary for the system safety to study each potential case of disasters caused by earthquakes. Recent reports imply that railway vehicles could derail solely by the ground motions of earthquakes without fatal damages of vehicles or tracks. Based on the reports and facts, we believe that we should further study the derailment mechanism of a high speed railway vehicle excited by great seismic motions, to pursue to minimize the risk of railway system safety against great earthquakes. At the start of the study, we developed our original vehicle dynamics simulation and then employed it for numerical analyses. At the present stage, through the analyses, we obtained the following major outcomes. (1) Most of derailments are brought as the result of the rocking motion of a vehicle by track excitations underneath. Interestingly, the derailing motions are observed similarly regardless of vehicle speed. (2) By contrast, the excitation amplitudes for derailment are influenced by vehicle speed particularly in lower input frequencies. This can be explained by the sensitivity of the relative wheel/rail slide due to creepage. (3) The excitation amplitudes for 30 mm of wheel lift are relatively independent of vehicle speed. (4) The wheel/rail slide strongly depends on the friction coefficient if a vehicle stationed, being relatively independent of the friction coefficient at higher speeds.

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This paper presents a damping control of a liquid container with an active vibration reducer on a wheeled mobile robot. The active vibration reducer independently tilts the liquid container to running direction and transverse direction. The optimal servo control system is adopted as a damping control of liquid sloshing with the vibration reducer. A Kalman-filter is used to estimate states and remove noise of sensors. An input shaping method is applied to design damping paths of mobile robots. The damping performance is more improved by using the vibration reducer together with the damping path design. The usefulness of the proposed method is demonstrated through simulation and experimental results.

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This paper proposes a kinematic model of the vehicle with low-ground-pressure tire that enables to enter a minefield in order to scan remaining landmines by a ground penetrating radar in level III survey. The low-ground-pressure tire makes low-pressure contact with a ground by deforming its shape of the tire, but the deformation deteriorates position and steering control accuracy. Therefore this paper models the kinematics of the low-ground-pressure vehicle based on experimental results. Besides we experimentally confirmed that the vehicle could precisely trace the target trajectory by considering its kinematics in simulated minefield.

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In the future, it is expected that robots will be able to play an active role in the real life alongside humans. Then, the softness of the robot is enumerated as one of the mechanical performances demanded for robots that coexist and cooperate with humans. Because, in case of a robot receives impact forces from an object, actuators may receive unpredictable damage by the impact forces. If the robot has mechanical softness, it is possible to reduce the impact forces. In such cases it is necessary to adjust the stiffness of the joint. Then, the reaction forces at the time of impact can be passively absorbed by lowering the joint stiffness. On the other hand, when torque requirement is high, a variable stiffness design helps raise the joint stiffness. Design of such a variable stiffness mechanism is proposed in this paper. The stiffness characteristics are evaluated. Analysis is conducted to verify feasibility of mounting it on actual robots.

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This paper presents an adaptive control methodology of shaking table systems for earthquake simulators. In the system, reaction force generated by a specimen on the shaking table generally deteriorates the table motion performance, resulting in the lower control accuracy of seismic tests. In order to compensate for the reaction force and to provide the precise table motion, therefore, an adaptive identifier is introduced, where dynamic characteristics of a nonlinear specimen are adaptively identified and can compensate for the deterioration in the motion performance. The proposed control approach has been verified by experiments using a prototype of shaking table system.

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This paper proposes a method for estimating eccentricity that corresponds to an incident angle to a fovea sensor. The proposed method uses Fourier-Mellin Invariant descriptor to estimate rotation, scale, and translation, by taking both geometrical distortion and non-uniform resolution of a space-variant image from the fovea sensor into account. The following 2 points are focused in this paper. One is to use multi-resolution images by Discrete Wavelet Transform for reducing noise caused by foveation properly. Another is to use a variable window function (although the window function is generally used for reducing DFT leakage caused by both ends of a signal) for changing an effective field of view (FOV) in order not to sacrifice high accuracy. The simulation compares the root mean square (RMS) of the foveation noise between uniform and non-uniform resolutions, when a resolution level and a FOV level are changed, respectively. The result shows the proposed method is suitable for the wide-angle space-variant image by the fovea sensor, and, moreover, it does not sacrifice high accuracy in the central FOV. Another simulation result examines a reliable resolution level.

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Nowadays, it is essential to shorten the production time and to make high quality products at low costs since consumer-needs are becoming diversified. To meet this high requirement, it is expected that 5-axis NURBS (Non-Uniform Rational B-Spline) interpolated machining be put into practical use. 5-axis NURBS interpolated NC data are generally defined by transforming linear interpolated NC data into NURBS interpolated ones. Therefore, the approximation error is consequently included in calculated tool paths due to the use of the linear interpolated data. On the other hand, the main-processors have been developed, which can generate NURBS interpolated CL data directly from CAD modeling data. It is very useful, however there is a problem of taking a long calculation time to generate CL data since the interference avoidance is considered for each tool path. Therefore, the study develops an useful CAM system, which can automatically generate practical 5-axis NURBS interpolated NC data, utilizing the interference-free space. As a result, the effectiveness of the proposed method is demonstrated from the feasibility experiments.

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Ball end milling is widely used in the machining process of sculptured surfaces. Due to the complicated surface geometry, it is difficult to achieve high productivity while maintaining high quality of machined surfaces. In order to meet these functional requirements, the prediction of machining error is indispensable. This study makes efforts on theoretical analysis of machining error in arbitrary tool-feed direction for ball end milling of cylindrical surface. A cutting model is developed to calculate the machining error. The verification experiments are carried out to investigate the theoretical analysis model. Basing on the analyzed and measured values of machining error, the influence of tool-feed direction on machining error is discussed.

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Characteristics of a new laser welding method for transparent thermoplastic resin plates are studied. The absorptivity on the surface is enhanced by pretreatment of sandblasting. It is found that the absorptivity due to roughness increases up to 36% for Polycarbonate and 21% for PMMA by sandblasting of #220. During welding process, the welded portion becomes transparent and the absorptivity due to roughness decreases down to 12% for Polycarbonate and 0% for PMMA. The shearing strength increases with the laser fluence, but it abruptly decreases by the formation of bubbles. The shearing strength also increases with the retaining pressure up to 0.15 MPa and it becomes nearly constant.

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Nanotechnology is based on a combination of many technologies such as high precise positioning and force control, especially magnetic recording, biotechnology and semiconductor industry require the utilization of nanotechnology. Until now there have been various actuator systems proposed, but the structure models have only working distances of either under a millimeter or over ten millimeters. Structure models with working distance ranging several millimeters has been designed a little. Therefore we are proposing a new structure design of actuator that would allow us to build actuator systems with working distances between those parameters. This new actuator consists of a voice coil motor and a new guide with an elastic support mechanism. The elastic support mechanism (ESM) consists of a special spring which is restricted to moving in only one direction. This new ESM does not cause any lost motion, mechanical play or friction with motion. Since characteristically voice coil motor thrusts and displaces the elastic support mechanism linearly, highly precise positioning and force control can be realized using a simple controller. We will evaluate the force control method from the displacement of ESM. This paper will provide basic data for developing future Nano-Actuator systems.

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Using an orthogonal table L₃₆ well-known in the quality engineering, a tolerance design method was previously proposed. In this design procedure, a trial-and-error method was used. To simplify the above complicated procedure, an improved tolerance design method is proposed in this note. In detail, by introducing a weight between two characteristic values, the parameter tolerance for the anti-vibration control system can be straightly derived.

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A new high resolution RBS (HRBS) system consisting of a magnetic spectrometer and a compact vertical small accelerator is developed. A detection angle change mechanism rotating around Y axis combined a spectrometer, a measurement chamber, a goniometer and a detection chamber is newly designed and installed. In order to evaluate stability and repeatability of a detection angle change mechanism, Si element peak edge channel on a position sensitive detector is measured by using ion beam. Edge position repeatability less than 1 channel for atomic level surface characterization has been performed.

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