A theoretical solution to the free vibration of a string, where both ends are moving and the string length is constant such as a belt, has been already obtained. In this paper, a theoretical solution of forced vibration of an axially moving string, whose length is constant, is presented. Finite difference analyses of string vibration are also performed to verify the validity of this solution and to obtain the vibration characteristics of moving string. The calculated results of the finite difference analyses are in fairly good agreement with those of the theoretical solution. The effect of the moving speed on the resonant frequency and the anti-resonant frequency is clarified in the case of both ends are exited sinusoidally: When both ends are excited in same phase, even an asymmetric mode showed the resonance by the effect of moving.

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This paper deals with the collision vibration in continuous system excited by periodic displacement with arbitrary functions. The analytical model is steady collision vibration in simply-supported-beam having an attached mass which collides elastically to symmetric faces with restoring force of hysteresis loops. In order to clarify the main resonance of the system subjected to excitation by displacement, the resulting vibration is analyzed applying the Fourier series method for this system. Following this theoretical analysis, the numerical calculations are also performed, and the resonance curves are constructed using the resulting vibrations. Effects of the stiffness of clamped spring, the ratio of attached mass and the amplitude of excitation on the resonance curves are shown as an example of numerical results.

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This paper presents a response evaluator as a semi-active control method for base isolated building in long-period earthquake response analysis. The absolute acceleration of each story and relative displacement of an isolated layer are the input signals and switching parameter for the damping coefficient is the output signal of the response evaluator. The response evaluator is designed by a multilayered neural network, and a genetic algorithm is used to adjust the neural network parameters which decide the performance of the response evaluator. Four oil dampers are installed at the isolated layer and each damping coefficient of the dampers is set to different value to correspond to various characteristics of earthquake motions, then the total damping force of the isolated layer is multi-step values regardless of using the oil dampers with two-step damping coefficient. By the numerical simulation with the proposed semi-active control method, both the acceleration of each story and the displacement of isolated layer which are trade-off relations with each other are reduced compared with the acceleration in case of all damping coefficient small (soft) and the displacement of isolated layer in case of all damping coefficient large (hard).

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Three-dimensional (3D) seismic isolation devices have been developed for the base isolation system of the Fast Breeder Reactor (FBR) that is an advanced nuclear reactor power plant building. The developed seismic isolation system consists of the hydraulic type vertical springs with rocking suppression mechanism and the laminated rubber bearings for horizontal direction. The isolation performances, i.e. natural period, damping, and rocking-suppression, have already been evaluated by the technical feasibility study and performance tests on a system which consists of down-sized devices on the shaking table, but in the seismic simulation on the real size building with this system, high hydraulic pressure was generated by rocking-suppression device under an extremely large seismic motion. In this paper, it is reported the frictional characteristics on high hydraulic pressure condition from the experiments on the 1/2 size of real device. To improve the damping performance of rocking-suppression, the orifice was added to the cylinder. At first the linear seismic simulation model of the real size system was constructed and damping coefficient was optimized by using that linear model. Finally, the detailed nonlinear simulation model was constructed, and time history analysis under simultaneous horizontal and vertical seismic motion was carried out, and the damping performance of rocking-suppression device was verified.

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This paper proposes a simple but accurate method for calculating the dynamic properties of an air spring employing an orifice to produce a damping force. Air springs are very common in rail, automobile, and vibration isolation applications. However, because this type of air spring has non-linear flow characteristics, an accurate analysis approach is yet to be proposed up to the present day. The restoring and damping force in an air spring with an orifice damper vary with the amplitude of the body. This amplitude dependency has not been considered in previous studies. Proposed herein is a simple model for calculating the air spring constant and damping coefficient. However, iterative calculation is required due to the non-linearity of the spring. The theoretical and experimental results are found to agree well each other. The theoretical equations provide an effective tool for air spring design.

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In this study, the vertical jump is examined as a basic study of jump. And we examine the influence of each muscle of the human body in vertical jump. The human body is modeled as four rigid bodies and analyzed in detail by using the model that includes muscles of the leg. In this research, the mechanism of jump is discussed by using numerical model to which the concept of multibody dynamics and biomechanics is adapted. We performed the experiment of jump and observe the feature behavior of vertical jump. Experimental results show that the angle of each body becomes vertical for ground and the change of the foot angle is small. Then we perform the numerical simulation referring to this experimental data. In order to reduce the amount of calculation, we calculate muscular activity level by correlating it with fewer parameters. We discuss which muscles are necessary for vertical jump. It is found that vasti exerts the biggest power and gluteus maximus has the highest state of normalized muscle activity.

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Recently, the riding comfort of car passengers became as important as the driving performance and the control stability. In order to improve the riding comfort, it is necessary to evaluate comfort quantitatively and take increasing comfort measures. In this study we analyzed the effect of vibration on the riding comfort. This research was conducted using two real cars having different riding comfort. We recognized that there were differences in the acceleration magnitude, frequency, phase, and the acceleration amplitude ratio of the driver's head response for a frequency under 3Hz. Therefore, using these as the input parameters, we investigated the sensibility characteristics in a shaking experiment, with a driving posture, to identify the parameters that affect the sensation during driving. We conducted vibration experiment using ordinary sine waves with two different directions, X (fore and aft)-Z (vertical) and Y (lateral)-Z (vertical). As a result, the riding sensation tends to depend on the frequency and the amplitude ratio. Next, we measured the human body response using input conditions which had shown differences of sensation in the experimental results of sensibility characteristics. Measurement points were pre-head, occipital, chest, pelvis, and ischium. Moreover, we analyzed human vibration responses by observing the relative movements of body parts from side-view and rear-view. We verified correlation between these responses and sensations. As a result, this study shows that riding comfort can be improved by decreasing lateral vibration at chest and pelvis.

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Understanding the generalized mechanism of self-reproduction is considered to be fundamental for application in various fields such as mass-production of molecular machines of nanotechnology. We developed a model for simulating cellular self-reproduction in two-dimensional hybrid cellular automata. To reduce the transition rules number, we considered not only the state transition rules but also the concentration diffusion of the Gray Scott model, which emerges self-reproduction phenomenon with certain parameters. In this hybrid model, information carriers activate the trigger of the self-reproduction phenomenon of the Gray Scott model, and cell membrane was formed by a part of the specific concentration of Gray Scott model. Using this model, we demonstrated that the following 3 functions can be realized. (1) Formation of a border similar to cell membrane. (2) Self-replication is achieved while maintaining a carrier containing information. (3) The division of the cell membrane is achieved while maintaining the total structure.

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In this study, we considered a calculation method to obtain accurately transfer functions employed in running transfer path analysis using principal component regression method. In the running transfer path analysis method, extracting noise components correctly in principal components, which consist of transfer functions, is important. Then, we tried to apply statistical verification method for extracting the noise components in the principal components. In the method, we set probability significance level of each principal component toward output signal as noise reduction standard instead of using the size of principal component that is used in conventional method. Subsequently, we verified the noise reduction performance through simple simulation and compared the performance of the statistical method and that of the conventional method. As results, noise influence was reduced from calculated transfer function by applying the statistical method effectively better than that of the conventional method. From these analytical results, it was clarified that the noise reduction method using statistical verification method has ability to obtain accurately transfer functions and considered that using the new method will increase the accuracy of running transfer path analysis method.

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The compressor which has a concentrated winding motor with the press-fitted segment core was developed for the first time domestically. It was necessary to grasp the dynamic characteristics of the press-fitted segment core to establish the low noise design technique of the developed compressor. This paper proposes a method that matches a calculated natural frequency of (2, 2) mode to the measured natural frequency based on the theoretical formula of the natural frequency of the ring, and presumes the equivalent stiffness coefficient needed for the vibration analysis. Using the method, it was clarified that the equivalent stiffness coefficient of press-fitted segment core changed from 206GPa to 165GPa by shrink-fit. Afterwards, the noise analysis of the remodeled compressor was carried out by using the equivalent stiffness coefficient. The calculated results agree well with the measured results. Therefore, it was clarified that the noise characteristics of a compressor which has a concentrated winding motor with the press-fitted segment core could be predicted.

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This paper presents a method for identifying the input power to structure in machine operation using energy analysis model such as Statistical Energy Analysis (SEA) and Energy Distribution (ED). The basis of the method is that the vibrational energies of the respective subsystems during working can be measured using the velocimeter or accelerometer at the same measuring positions of constructing the SEA and ED model. In this paper, the method is applied to three series coupled plates. It is shown that the accuracy of the identified input power using SEA and ED model are compared by applying two approaches to FEM analysis and a experimental test. The estimated results show that the method has excellent performance to identify the input power during working.

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In this paper, we focus on the ACM2 (Area Contact Model 2) model as a simplified spot weld model for the vibration analysis and reveal its dynamic characteristics. For the ACM2 model, a spot weld is modeled with a single solid element and the upper and lower plates are modeled with shell elements. The solid element and the shell elements are connected using multi-point constraint (MPC). First, the theory of MPC equations used in the ACM2 model is explained. Next, the effects of meshing of the plate surrounding the spot weld on the modal properties (natural frequency and mode shape) are examined in detail. Finally, a proper mesh size in the area of the spot weld is presented. As an example structure, the structure that consists of two steel plates jointed by three spot welds is used. The results show that the size and configuration of the patch (the group of shell elements in the ACM2 model) significantly affect the modal properties. When the centers of solid element and patch are coincident, the natural frequencies monotonically increase with patch size. When the centers of solid element and patch are not coincident and the element size is large, the natural frequencies vary widely. When the shell element size in the patch is equal or less than the solid element size that is determined by the spot weld diameter, the variation in the natural frequencies is small.

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This paper proposes a vibration testing and health monitoring system based on an impulse response excited by a laser ablation. High power YAG pulse laser is used in this system for producing an ideal impulse force on structural surface. It is possible to measure high frequency vibration responses in this system. A health monitoring system is constructed by this vibration testing system and a damage detecting algorithm. A microscopic damage of structures can be extracted by detecting fluctuations of high frequency vibration response with the present health monitoring system. In this study, loosening of bolt tightening torques is defined as the damage of the system. The damage is detected and identified by statistical evaluations of measured frequency response data with Recognition-Taguchi method.

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The contact wire strain is one of the most important indices to evaluate the safety of current collection system in high-speed operations. The authors proposed a new method estimating the contact wire strain based on the measured contact force between pantograph and contact wire, and carried out running tests to verify the utility of the method at current-collection testing equipment. It has been confirmed that the estimated contact wire strain by the method is more accurate than the value derived by the conventional method, and consequent errors are less than approximately 15% in dynamic simulation results of catenary-pantograph system. As the result of running tests, the estimated strain was almost consistent with the measured one. It is highly likely to contribute to the improvement of the diagnosis techniques of overhead equipment.

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Piezoelectric shunt damping is a unique technique, which utilizes a piezoelectric element as both an actuator and a sensor. In this paper, we consider a virtual impedance circuit with a DSP. The analog lowpass filters are necessary for anti-aliasing and smoothing in the use of the digital virtual impedence, however the system becomes unstable due to the filters. Therefore we conduct stability analysis with the open-loop transfer function and propose a simple method for stabilizing the system using a digital band-pass filter. Experimental results show the effectiveness of the proposed method for the shunt damping with the digital virtual impedence.

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Shapes and lay-up configurations of composite laminated shallow shells are optimized simultaneously to maximize the fundamental frequency by a simple genetic algorithm method. The shell shape is defined by a cubic polynomial and this makes it possible to express various shapes of shells with inconstant curvature radii by varying the value of coefficient for each term. The coefficients and the lay-up configuration of the laminated shell are directly employed as design variables, and constraints are imposed on the coefficients and curvature radii to keep shells shallow. The frequencies are calculated by using the Ritz method due to its flexibleness for shell shapes. Results of the present analysis technique agreed well with experimental and finite element analysis results in terms of frequencies and mode shapes. Obtained optimum solutions resulted in higher fundamental frequencies than the shells with general shapes and lay-up configurations.

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A kind of an air cushion vehicle (ACV) is known as a hovercraft which carries out a cruise by blowing off the air from the bottom of the body. The ACV has many advantages, such as amphibian vehicle, large payload, and so on. However, the ACV has drawbacks such as its drivability and controllability are bad. An improvement of the drivability is effective for the control of the ACV and the disturbance rejection performance of the controller is very significant. In this research, the position of the ACV is estimated with the image information of two cameras. When the ACV runs on the straight line, the ACV is kept on the line by the designed controller. The usefulness of the designed controller is confirmed through the simulation and an experiment.

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The critical steering angle that the self-centering of the steering wheel occurs is one of the important measures for steering maneuverability. It is shown that this critical angle is influenced by the damping coefficient of the torsion bar if slight steering torque is applied just before releasing the steering wheel. Meanwhile, torque assistance device equipped vehicle generates assistance torque based on the deflection angle of torsion bar. Hence, the exceedingly high damping coefficient may cause deterioration of the assistance torque. Analytical results on the adequate range of the damping coefficient in view of both assistance torque and self-centering is shown.

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In this paper, the steering performance of a human-powered dynamically stabilized vehicle is investigated as one of the forms of Personal Mobility Vehicles (PMV). The produced prototype vehicle has the reaction force actuator and it reacts according to the handle steering input. The turning is realized by the differential of the rotation of the right and left wheels. The steering system is designed by the steering dynamics of the bicycle. In the experiment, the errors from the target trajectory were measured and the maneuverability was evaluated by the subjects. It was shown that setting the driving torque of the wheels using the gain proportional to the handle steering angle and its rate had high performance.

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Recent light-weighted and structurally-simplified railway vehicle carbodies tend to have complicated three dimensional elastic vibration modes and such vibration modes affect riding quality. In particular, it is known that the mode similar to the first mode of free supported elastic beam (“B mode”) and diagonal distortion mode (“D mode”) whose natural frequencies are around 10Hz are important because 10Hz is known to be a sensitive frequency range for human. In this paper, a method aiming at reducing the two modes (B mode and D mode) simultaneously by using two active mass dampers (AMDs) is suggested, and its feasibility is examined numerically and experimentally. A simple analytical model which can express complicated 3D elastic vibrations of carbody is introduced, and the way to obtain appropriate model parameters is proposed employing genetic algorithm (GA). Using the analytical model including bogies and AMD models, the capability to reduce those two target elastic modes is investigated. A stationary excitation test for a commuter type test vehicle is then carried out using an electro-dynamic exciter. The peaks corresponding to those two target modes are reduced successfully when AMDs are applied in the excitation test.

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Mobile inverted pendulums are expected to be applied to personal mobility and robots which are used in human living space. Although this mobility always needs to be stabilized, previous approaches were based on a linearized model or feedback linearization. In this study, interconnection and damping assignment passivity-based control (IDA-PBC) is applied. The IDA-PBC is a nonlinear control method which has been shown to be powerful to stabilize underactuated mechanical systems. Although partial differential equation (PDE) must be solved to derive the IDA-PBC controller and it is a difficult task in general, we show that the controller for the mobile inverted pendulum can be constructed. A systematic graphical method to select controller parameters which guarantee asymptotic stability and estimate the domain of attraction is also proposed. Simulation results show that the IDA-PBC controller performs fast responses theoretically ensuring sufficient domain of attraction. The effectiveness of the IDA-PBC controller is also verified in experiments. Especially control performance under an impulsive disturbance on the mobile inverted pendulum is verified. The IDA-PBC achieves as fast transient performance as a linear-quadratic regulator (LQR). In addition, we show that when the pendulum inclines quickly and largely due to the disturbance, the IDA-PBC controller can stabilize it whereas the LQR can not.

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Bump foil journal bearings are prospective applicants that can support small-sized high-speed rotating machinery. In the previous report, the maximum load carrying capacity of the bearing was predicted, considering the detachment of top foil and the style of attachment of its trailing edge to the bearing housing, and these effects on the capacity were shown to be small. However, the result was obtained only from a base case of the bearing design variables. In this report, the capacity is presented extensively in other cases of the bearing design variables. It is found that the result is applicable to the capacity of the bearing where an excessive static friction acts between the top and the bump foils. On the other hand, the effects of the detachment and the attachment on the capacity of the bearing without the friction between the two foils could be large in the cases of larger values of rigidity of top foil, preload factor, attached angle of top foil, width diameter ratio and pitch angle of bump-equivalent springs.

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A tripod constant velocity joint is used in the driveshaft of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. In this paper, in order to reduce the thrust force, some reduction methods are surveyed based on mechanisms inducing the thrust force. In these methods, the dual-contact method between a roller and a groove is focused. This method has the advantage of only a few design modifications, but reduction mechanisms have not been clarified. Therefore, a theory inducing the thrust force in this method is constructed by applying sliding velocities caused between the roller and this dual-contact groove, and the effectiveness of the thrust force reduction is studied. This paper also describes the appropriateness of this theory. It is verified by comparing these theoretical results with computational results by utilizing multibody dynamics approach and experimental results by using a prototype joint equipped with the dual-contact grooves.

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In this investigation, a numerical procedure that can be effectively used for modeling sliding joint constraints for the absolute nodal coordinate formulation is developed. To this end, the arc-length coordinates are introduced to define the time-variant location of the constraint definition point on flexible bodies, while the intermediate coordinates are introduced to derive a mapping between the generalized gradient coordinates and the rotational coordinates. With this mapping, sliding joint constraints can be efficiently formulated for a flexible body modeled using the absolute nodal coordinate formulation. Furthermore, existing constraint libraries formulated for rigid bodies can be employed for the absolute nodal coordinate formulation without modifications. It is also demonstrated that the arc-length coordinates and intermediate coordinates used for formulating sliding joint constraints can be systematically eliminated from the equations of motion and standard differential algebraic equations used for general multibody dynamics computer algorithms can be obtained.

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The dynamic property and behavior of the soft ground are greatly affected by the constituent grains' shape. The consideration of the elastic-plastic property of the soft ground is also important for the multipass calculation of the tire on the soft ground. We developed the efficient interactive model of the tire and the soft ground that were composed of the distributed lumped mass-spring model as the tire, Discrete Element (DE) model as the upper soft ground, and the mass-spring model as the lower soft ground. In the present study, we have improved the previous soft ground model by considering the grains' shape and the elastic-plastic property of the soft ground, and have confirmed these effects through several numerical simulations.

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We study grazing impact of some specific globally coupled multi-vibro-impact oscillators which is inherent Grover wave algorithm. Periodic energy transfer is caused from an internal resonance between a globally coupled small impact oscillator and a small non-impact one. Decrease of kinetic energy from the small impact oscillator by the energy transfer can cause periodic grazing impacts of the oscillator near zero velocity. We derived the condition of perfect zero-velocity graze impact from the wave algorithm. Trace of impact map in Bloch sphere shows figure-of-eight orbit, which corresponds to the shift of two different impact modes at the graze impact. In addition, we found the case of clearance vibration under low velocity. The clearance vibration is achieved by controlling external impact.

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A pressure wave propagating in a tube often changes to a shock wave because of the nonlinear effects in the propagation medium. The purpose of this study is to establish a practical analytical model to analyze this phenomenon. In the first report, a concentrated mass model was proposed to analyze a nonlinear pressure wave phenomenon in a rigid straight cylindrical tube. In this paper, we apply the model to an elastic pipe. The model in the elastic pipe consists of masses, nonlinear connecting springs, base support dampers, base support springs, and connecting dampers. The effect that the cross-sectional area of the elastic pipe changes is considered by the nonlinear connecting spring. To confirm the validity of the proposed elastic pipe model, we perform experiments on a silicone tube, and the experimental results are compared with the numerical results obtained by the concentrated mass model. The numerical computational results agree well with the experimental results. Therefore, it is concluded that the proposed elastic pipe model is valid for the numerical analysis of nonlinear pressure wave problem in an elastic pipe.

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The evaluation methodologies for the flow-induced vibration instability of a long flexible beam due to an axial flow confined in a narrow passage have been reported. In this paper, by using this proposed analytical method, the parameter-studies are performed on the dynamic stability of an elastic beam subjected to axial flow confined a narrow passage. The effects of support conditions of structures, structural damping, and fluid characteristics on the dynamic stability are clarified for the safety of dynamic design in industries. Especially, paying an attention on the vicinity of critical velocity, the effects as for stabilization or destabilization effect on flutter and divergence phenomena is investigated by changing fluid viscosity and structural damping.

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A 5-DOF self-bearing motor has been proposed to achieve a compact active magnetic bearing (AMB) system. The 5-DOF self-bearing motor possesses the functions of a motor, two radial AMBs, and an axial AMB. Therefore, it is possible to downsize the AMB system drastically with maintaining high performance. In this paper, outer rotor type 5-DOF self-bearing motor is proposed for the application of an artificial heart pump. The analytical condition is set that the required motor torque is 0.03Nm and the control force is quintuple of the rotor gravity. The performance of the inner rotor type and outer rotor type 5-DOF self-bearing motor is analyzed using three dimensional finite element method. The downsized outer rotor type 5-DOF self-bearing motor shows sufficiently applicable for an artificial heart pump.

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This paper deals with the aerodynamic interference between two vehicles which are running in close proximity and are subjected to crosswind. Measurements of the aerodynamic drag, side force and yawing moment were performed at different wind angles and longitudinal and lateral distances between two vehicles. In crosswind, extreme proximity between the vehicles ahead and behind provides several peaks of aerodynamic drag, side force and yawing moment acting on the vehicles. When one vehicle passes the other one in crosswind, the large variation in these forces and moment leads to the danger of driving. Numerical results by the CFD show a good agreement with experimental ones. They reveal that the aerodynamic drag is influenced by airflow behind the other vehicle, and that the side force and the yawing moment are also influenced by complicated airflow structure due to the aerodynamic interference between two vehicles.

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The mechanism of fluctuating vibration in engine accessory drive belts is studied. It was clarified that the fluctuating belt vibration has multiple spectral lines centering around natural frequency. Some spectral lines fold back at 0 Hz when they have negative frequency. And it is assumed that the belt vibration will maximize when the folding spectral lines cross the natural frequency. In this report, by the multi-body-dynamics simulation, that assumption was verified. And we found that the belt vibration will maximize because of parametric vibration rather than the folding negative frequency element.

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Recently, bladed disks with the continuous ring type structure have been used in many kinds of turbomachinery due to its high reliability. The vibration characteristics of the bladed disk with continuous ring type structure have been studied extensively, and the effect of the friction damping on the forced vibration is almost clarified. On the other hand, few studies have been done on the effect of the friction damping on the blade flutter. In this paper, the stability analysis of the bladed disk with the continuous ring type structure is carried out using the equivalent spring mass model, and the effect of the friction damping on the blade flutter is clarified. From the results of analysis, it is concluded that the stable steady vibration or the flutter occurs when the aerodynamic damping of the blade becomes negative. Whether the blade vibration is stable or unstable depends on the magnitude of the aerodynamic damping and the initial condition. In other words, when the friction damping can not suppress the self-excited vibration due to the large aerodynamic damping and the large initial amplitude, the amplitude of the blade vibration becomes larger and the flutter occurs.

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This paper proposes a new technique to improve the current collection performance of pantographs. For this purpose, the pan springs, which are usually coil springs, are replaced with variable stiffness device. When the stiffness of the variable stiffness device is controlled in such a way that the peak frequency of the compliance characteristics is consistent with the dominant disturbance frequency from the catenary to the pantograph, the contact force fluctuation can be reduced. From the numerical simulation results, we confirm that it is possible to reduce the contact force fluctuation by using the proposed technique.

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A large number of wheeled casters have been used around the world so that we can push wagons easily. These days, the specifications of casters tend to become severe to keep the wagon vibration lower. Especially, it is very important for patients, medicines and small precision parts to be carried softly and stably. On the other hand, the good design of wheeled casters depends on skills of the engineers who have produced them for years, and the details of the good design are not clarified. In this paper, the mechanics of the wagon caster is discussed to obtain the better design standards. First, we focus on the center of percussion of the wheeled caster to reduce the impulsive force to the wagon. Next, the two-dimensional dynamical model of the wagon is derived to study the reduction effect dependent on the center of percussion. Then, the experimental results are minutely compared to the simulation results using the derived model. From these results, it is clarified that the position of the center of percussion on the caster achieves the reduction of the impulsive force to the wagon when the wagon wheel runs over small bumps. The simulation results based on the dynamical modeling are also verified to have good agreements with experimental results.

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When carrying out seismic performance examination on a structure by using a shaking table, it is important to reproduce the acceleration faithfully. In the conventional method, we transformed the acceleration wave into a displacement wave and used a hydraulic actuator for displacement control. However, this method had several disadvantages related to disturbance rejection, tracking performance, and stability. In this study, we have developed a full-closed compensation, in which the shaking-table acceleration is assumed the feedback signal for the acceleration wave of the reference signal. Also we adopt the dual model matching (DMM) control technique in order to design a controller. To confirm the disturbance rejection performance and to investigate the effect of enhancing the reproducibility of the shaking-target waveform by DMM control, we perform an experiment using a one-degree-of-freedom specimen placed on a shaking table driven by a hydraulic actuator.

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Structure borne noise is dominant in vehicle interior noise as frequencies below approximately 300Hz. Spindle force is a critical factor in structure borne noise for vehicle interior noise. To research the vibration characteristic of a rolling tire is essential for prediction of spindle force. This paper describes vibration analysis of a tire on the static and operational condition. Firstly, the surface vibration velocities are measured in the operational condition to comprehend the vibration behavior of a rolling tire using the scanning Laser Doppler Vibrometers. Secondly, the tire vibration model based on the cylindrical shell theory is build up. The basic equation, including the effects of the initial tension and the Coriolis force due to rotation, is derived by thin rotating cylindrical shell model and Hamilton principal. The results of the experiment and the theoretical analysis for a rolling tire are presented. Consequently, it is found that same shape of traveling-wave modes occur for a rolling tire, and the excited frequency of forward wave is different from that of backward wave. Finally, it is revealed that whether the rotation effect have affect on the vibration characteristics of a rolling tire.

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The importance of the in-flow oscillation of a single cylinder in cross-flow has been in the spotlight since an accident in a FBR-type reactor. However, in-flow oscillations can also be observed in heat exchanger tube arrays. Previous reports show some interesting phenomena on the oscillation of cylinder arrays. In this paper, detailed observation on the effect of the pitch ratio for pairs of cylinders, in parallel and in tandem, is highlighted in the range of low flow velocities, where each cylinder can move only in a given direction. The motion of the cylinders is measured by attached strain gages and by a high-speed digital video camera. As a result, it is found that the response of cylinders is greatly affected by their pitch ratio due to the separated vortex, and that the symmetric vortex is restricted when the motion of cylinder is restricted.

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In this paper, we propose a passive gravity compensation mechanism for carrying load with two springs and switching mechanism, which named “Weight Switching Mechanical Gravity Canceller (WS-MGC).” The WS-MGC has following advantages with the original MGC in load compensation. The original MGC required to determine the compensation weight from the beginning and to make actuator bear the load when end-effector has new luggage and carries it. In this case, it is effective to switching the compensation weight from the weight of the machine to the total weight of both machine and luggage, without power supply. WS-MGC can switch the compensation weight by the weight of luggage. From development and experiments of a link model equipped with WS-MGC, it is clarified that the versatile device is succeed to step up from weight compensation to load compensation.

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This paper presents a control method to achieve stable landing to rough and unknown terrain. Landing control is one of the important issues for biped walking robot, because robots are expected to walk on not only flat known surfaces but also unknown and uneven terrain to contribute to human society. A point-contact type foot with spring is employed in this control method, and it realizes stable contact with rough terrain and suppression of impact force. The proposed controller can adjust the foot position and posture without excessive impact by using the reaction force and torque estimated from the spring displacement, and guarantee the robust stability of control system with respect to terrain variance. The effectiveness of the proposed controller is demonstrated by experimental results.

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Driver safety is an important and often sensitive issue for seniors. Statistics show that the elderly are more likely than other drivers to receive traffic citations for failing to yield, turning improperly, and running red lights and stop signs all indications of decreased driving ability. Currently in Japan, half of the deceased in traffic accidents are elderly people. In present study, we focused on how the pedal placement affect on braking action in emergency. First, ten healthy young and ten elderly individuals were asked to perform a simple reaction experiment by foot. Then, the same subjects were instructed to complete a braking action experiment with different pedal placement condition. The results suggested that both simple reaction time and foot movement time of elderly subjects were significantly longer than that of young subjects. Moreover, the brake pedal force of elderly subjects was lower than that of young subjects. Thus, aging influenced both of simple reaction time and braking action in emergency. In addition, even the pedal placement changed characteristics of braking action of both young and elderly subjects, the most comfortable pedal placement of elderly subjects differed from young subjects.

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Particle swarm optimization (PSO) is a population based stochastic optimization algorithm inspired by social behavior of bird flocking and fish schooling. PSO has proven to be implementable with ease, stable, scalable, and capable of yielding good results in a faster, cheaper way. However, it has been also reported that premature convergence to suboptima often occurs particularly in large scaled multimodal problems. This paper proposes two extensions for avoiding the premature convergence in standard PSO algorithms. Firstly, the partial initialization is applied in a small probability for keeping global search. Secondly, PSO is extended so as to have a function of local search intensively around the best solution. The second extension is designed as a mechanism that can prevent the partial initialization from expanding divergence and loss of the best solution. We conduct computer simulations and analyze searching behavior of the PSOs using a set of standard benchmark functions. The results show the PSO with our extensions surpass a standard technique particularly on large scaled multimodal functions.

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This paper investigates a particle swarm optimization (PSO) approach to a multi-robot system. PSO is known to be relatively implementable with ease, and efficient for solving various optimization problems. However, the inefficiency for large scaled multimodal problems has also been reported. In order to overcome this unwanted characteristics of PSO, we have been developing a noble method that performs the partial initialization in a small probability and demonstrating its basic effectiveness to benchmark functions. Further discussion on a real world problem is conducted in this paper. We tackle the control of autonomous mobile robots by PSO. Similar to typical methods of evolutionary robotics, artificial neural networks (ANN) is employed as a controller of each robot. PSO is utilized as a methodology for designing ANNs. To examine our approach, computer simulations are conducted using a cooperative box-pushing task. The results obtained are compared with a standard PSO results. It is found that our proposed approach outperforms a conventional one.

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In this paper, the problem in the CO2 infrared laser medical operation device that propagates the laser in the hollow optical fiber was dealt. There is risk of the accident of damaging by a fire when leak is opened in the hollow optical fiber, and the laser light is discharged outside. This study is the detecting method for the leak on hollow optical fiber by using the sound. A basic experiment concerning this method and comparison result between the theoretical analysis and the experiment are reported. The leakage of the narrow tube with large attenuation can be detected. The experiment was corresponding to the tendency to the theoretical analysis for the presence of the leakage and the change in the hole diameter. This method is inexpensive than the method of adding the optical device, it makes small hand peace, and doesn't ruin handling that is the advantage of the hollow optical fiber.

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Space structures encounter various special environments in space. One of these environments is severe thermal condition. Difference of temperature of space structures during day-time and night-time is about 200 kelvin. These severe thermal conditions cause thermal deformation of the structures. In fact, we observed the signal level of radio wave from the LDR (Large Deployable Reflector) of the ETS-VIII (Engineering Test Satellite -VIII) changing during the Earth eclipse. This phenomenon may be caused by thermal deformation of the LDR. This thermal deformation is a key issue to maintain the accuracy of communication beams reflected by the space antenna. Analysis of thermal deformation of the LDR is carried out, and a new suppression scheme for thermal deformation is proposed in this paper.

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In many industrial products there is saturation of technical issues, and customers have already satisfied with the most of them. Now, they would like to choose one which has their needs within their budgets. In that sense, it becomes more and more important to meet their various satisfactions. In order to find good aims for designing next products, it might be important to know the trend of the products. In this study, we basically use Total Technical Evaluation (TTE), which we have proposed in the previous study. We prepare time series data and evaluate TTE for each year, and also for whole data, and show the growth of technical frontier by using TTE. We also evaluate difference between whole frontier and each category's frontier, and evaluate originality of each category. With time series data, we also can evaluate growth of them. And we also evaluate characteristic analysis in time series to show that each category has been matured or still moving to meet customer's satisfaction. In this paper, we demonstrate the proposed method in automobile data from 1995 to 2002 and show the effectiveness of the method.

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This paper describes the system that can efficiently control Automated Guided Vehicles (AGVs) movings for Decentralized Autonomous Flexible Manufacturing Systems (DA-FMS). Especially, the paper proposes the mind model called Minimum Unit of Mind (MUM). Because of the characteristics of MUM, that is a mind change, AGVs can efficiently avoid the route interferences even if many AGVs are operating in DA-FMS. The components of MUM are two stimulation cells, a box and an arrow. After some application simulations, it is ascertained that MUM is useful for avoiding AGV route interferences.

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Cooperative positioning is a positioning technique in which long stroke paths and ultraprecision positioning are combined. These are achieved simultaneously in a single apparatus using extended displacement positioning (EDP) and reduced displacement positioning (RDP), respectively. In the present study, we developed a new control program for a 2-stage hinged cooperative positioning device. RDP is first carried out by a series of step motions of the fine positioning stage. The extended displacement stage is then moved using EDP by an amount equal to the total displacement achieved by RDP. Simultaneously, the fine positioning stage is returned to its initial position using RDP. Continuous step positioning then becomes possible by repeating these operations. The maximum stroke was 67.1 μm and a settling range of less than the EDP displacement resolution (27 nm) was achieved. Some positioning errors were found to occur due to switching between the two types of operation. However, these could be reduced by increasing the EDP control coefficient to improve synchronization, or by decreasing the number of positioning steps. In this way, the amount of overshoot and the settling time could be effectively controlled. Using this apparatus, it was shown that continuous positioning with 25 nm steps was possible.

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Patterning vast numbers of micro lenses on a surface increases technical importance to improve characteristics of optical parts such as liquid crystal displays. A cutting method using a diamond bite is examined to make a molding die by which array patterns of many micro lenses are molded. Realizing the cutting procedure, the developed machining system employs a cutting unit actuated by PZT and a synchronous control system of the cutting unit with a NC controller. Through experiments using this developed system, it is confirmed that machining a lot of micro lenses on a molding die with high precision is possible. And we confirmed that a high-speed cutting of micro lens array for roll die which is used for manufacturing plastic films is possible.

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