A new design method of functional fiber reinforced plastics (FRP) which imitate micro structures of natural materials such as bones and shells is proposed in this work. The material has local anisotropy induced by optimally distributed short fibers which are defined in each element of the finite element method. To design such locally anisotropic thin plates, the present optimum design method combines a genetic algorithm method (GA) with layerwise optimization (LO) concept. The LO concept reduces multi-layer optimization into iterations of single-layer optimizations and the GA is used for a single-layer optimization to decide the fiber orientation angle in each element. The lowest natural frequency of the plates is chosen as an objective function to be maximized and it is found out that the present plates always give higher natural frequencies than conventional plates which are reinforced by parallel straight fibers. Moreover, it is revealed that optimally distributed short fibers tend to be allocated with certain tendency.

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Recently, the use of the wind turbine generator has rapidly spread as the one of the clean energy sources, and its size is becoming larger. Because of the difficulty of the maintenance of such a large wind turbine generator, the vibration analysis and clarification of the dynamical characteristics of the wind turbine generator are important. However, the conventional researches aimed at the fluid engineering in order to gain higher efficiency, and only few investigations have been reported in the area of the vibration analysis and its suppression. The wind turbine is a special type of rotating machinery : It has a long heavy blade which rotates in the vertical plane under the action of the gravitational force, and the wind power acting on the wind turbine blade changes periodically because, for example, the wind power increases as the function of the height. Therefore, it requires the original point of view in the dynamical analysis. This paper investigates the fundamental vibration characteristic of the wind turbine blade by using a rigid blade model. The gravitational force causes the effect of parametric excitation on the blade system. The interaction effect of the gravitational force and wind force on the vibration of the turbine blade is investigated, and the occurrence of super-harmonic resonances due to it is clarified. Also, the occurrences of the unstable vibration ranges are indicated. Furthermore, these results are validated experimentally.

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This paper deals with the response analysis of nonlinear vibration in continuous system excited by periodic displacement with arbitrary functions. A system of steady state forced vibration in a simply supported beam connected with a nonlinear spring at midpoint of span is considered. The restoring force is assumed to be a piecewise-linear system. For such a system, the beam undergoes a nonlinear vibration when the amplitude is large. In order to analyze the main resonance for the system, the Fourier series method is applied to obtain an exact solution for response vibration. The numerical calculation is performed to obtain the resonance curves. The numerical results show effects of the stiffness of attached spring and the amplitude of excitation on the resonance curves. The experiments are also performed to verify the numerical results.

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Experimental results and analytical results are presented on the effects of axial compressive load on chaotic vibrations of a clamped-supported beam subjected to periodic lateral acceleration. The beam is elastically compressed by an axial spring at the simply supported end. In the experiment, nonlinear and chaotic responses are detected under various compressions. In the analysis, the governing equation is reduced to nonlinear differential equations of a multiple-degree-of-freedom system by the Galerkin procedure. The nonlinear periodic responses are calculated by the harmonic balance method. The chaotic responses are numerically integrated by the Runge-Kutta-Gill method. The chaotic responses of the beam under axial compression are examined with the Fourier spectra, the Poincare projections, the maximum Lyapunov exponents and the principal components by the Karhunen-Loéve transformation. Both results of the experiment and the analysis coincide fairly well in detail. The frequency region of the chaos spread with the increment of the axial compressive force. The chaotic responses are generated within the axial compression range of the same ratio to the each buckling load. Distinct fractal pattern can be observed in the attractors of Poincare projections. The number of modes generated in the chaos is counted as three by the maximum Lyapunov exponent and the Lyapunov dimension.

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Analytical results are presented on nonlinear vibrations of a cantilevered beam constrained by a stretched string at the tip end. The beam is subjected to periodic lateral acceleration. Governing equations of motion and boundary condition, which have nonlinear geometrical coupling with an axial force, are derived by the Hamilton's principle. The mode shape function proposed by the senior author is introduced to reduce the governing equations to the nonlinear differential equation by the modified Galerkin method. The mode shape function is expressed with the product of the trigonometrical function and the finite power series truncated with the fourth order. The coefficients of the power series are determined by solving the homogeneous equation for the boundary condition at the buckling state of the beam. The trigonometrical function can express the form of higher mode of vibration. Nonlinear periodic responses are calculated by the harmonic balance method. Nonlinear non-periodic responses are obtained by the numerical integration. Comparing the non-linear responses by the analyses with the approaches of single-degree-of-freedom and of multiple-degree-of-freedom, higher mode of vibration play important roles both in the periodic response and in the chaotic response. It is shown that the analysis based on the approach of the mode shape function makes fairly good prediction to the nonlinear phenomena of the cantilevered beam constrained by the stretched string.

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Parametric resonance occurring in many mechanical systems has special resonance mechanism compared with the usual external resonance, and the resonance is produced under the excitation direction normal to the velocity of the system and the excitation frequency is in the neighborhood of twice the natural frequency of the system. In this paper, we clarify that the parametric resonance can be induced under the excitation direction parallel to the velocity of the system by asymmetric nonlinear restoring force and examine the steady states and their stability theoretically and experimentally. We indicate the dependency of the unstable region on the magnitude of the asymmetric component and analyze the steady state amplitude of the parametric resonance in order to clarify the nonlinear characteristics of the parametric resonance induced by asymmetric nonlinear component. Furthermore, we use a simple experimental apparatus with magnetic asymmetric nonlinear restoring force and discuss the validity of the theoretical results.

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In nuclear power stations, the storage of a lot of spent fuels is becoming impossible because of the shortage of the residual space of the spent fuel pool. It is planned to construct an another plant where the spent fuels are temporarily stored. In that plant, the spent fuels are installed in a container which is called canister, and the canister is stored in a free-standing cylindrycal container which is called cask. The cask is freely standing on a horizontal floor in general. In this sense, the cask-canister system is considered as a two-degree-of-freedom coupled system which is freely standing on the floor. Thus, it is very important to evaluate the rocking motion of a cask-canister system due to seismic excitation. In an analytical model, the canister and the cask are treated as rigid bodies which are connected by spring. The equations of motion are derived for rocking motion when the floor is subjected to the horizontal earthquake excitation. The rocking angle of the cask and the relative displacement of the canister against the cask are evaluated by numerical simulation, and the effects of the canister vibration on the cask motion are discussed.

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The collision vibration is widely applied to the impact machining device since accurately large energy is comparatively obtained. It is necessary to quantitatively analyze response vibration and restitution force by collision for design of the impact machining device. As an example of basic investigation, this paper deals with impact vibration in a spring-mass system for two-degree of freedom excited by periodic force with arbitrary functions. The analytical model is steady impact vibration for two-degree of freedom having two masses subjected to an exciting vibration. Then the restitution force, which has characteristics of an unsymmetric piecewise-linear system with hysteresis loop, collides elastically with another mass when amptitude of the mass exceeds than the clearance. In order to analyze the resulting vibration for the main resonance, the Fourier series method is applied to obtain an exact solution for response vibration. The numerical calculation is performed to obtain the resonance curves. The numerical results show effects of the stiffness of the clampted spring and the amplitude of excitation on the resonance curves.

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This study deals with nonlinear dynamics of a horizontally supported Jeffcott rotor. The equations of motion are derived by considering the effects of gravity and the cubic nonlinearity of restoring force by the support condition. These effects produce the difference between the linear natural frequencies in the vertical and horizontal directions and make the stiffness in the vertical direction unsymmetric. It is also theoretically clarified that as the mass increases, the hardening spring characteristic becomes stronger in the horizontal direction and the spring characteristic in the vertical direction changes from the hardening-type to the softening-type. Therefore, in a relatively heavey rotor, the frequency response curve of the primary resonance in the horizontal direction exhibits hardening-type response and in the vertical direction, the frequency response curve has the softening-type nonlinearity. The experimental results by a simple apparatus qualitatively confirm the theoretically predicted nonlinear dynamics of the horizontally supported rotor.

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The regulatory guide for seismic design of nuclear power plant has been vastly revised at several fields. Main items under revision are observed such as the requirement of making appropriate concern for the dynamic coupling effects of horizontal and vertical components of earthquake, and the consideration of probabilistic risk assessment against the uncertainty of earthquake. The purpose of this paper, therefore, is to estimate the stochastic responses of multi-degree-of-freedom structure with closely spaced natural frequencies under the consideration of the correlations between multi components of earthquake. For this target, one mathematical model is developed in order to analytically evaluate the effects of correlation between components of input, and the stochastic vibration analysis is executed based on FEM-based eigen mode analysis and transition matrix method. The analytical results are compared with those by Monte Carlo simulation. Failure probability of structure is also explained as a typical example applying the proposed technique to the probabilistic seismic design.

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The identification of external force acting on a machine or a structure is important for the diagnosis. One of the force identification methods is based on the frequency response function. The method is very useful although it requires the information of location of force acting. In this study, an identification method is proposed for the case of unknown excitation points. The method is firstly the external forces, whose amount is same as the one of sensors, are assumed at every candidate location, and the amplitudes of forces are identified. Then the exact location of external force is determined by the classification of all identified results. The method is numerically checked and it was shown that the method was useful using the data with noise. Moreover the experimental results showed that the method was feasible when the location and amplitude are separately identified.

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In this study we propose a design procedure of two degree of freedom system supported with air suspensions with viscous restrictions and a reservoir tanks. We use two design concepts of minimizing resonance amplitude and minimizing standard deviation of amplitude against external disturbance random vibrations of foundation. To minimize resonance amplitude, the damping ratio, which corresponds to the restriction coefficient of viscous restriction, has to be chosen in order to equalize the resonance amplitude under the condition of parallel oscillating to that under the condition of rotating oscillating. To minimize standard deviation of amplitude of the system, the optimum damping ratio which minimize the standard deviation of amplitude of the system under the condition of rotating oscillating has to be chosen when the natural frequency of the parallel mode is lower than that of the rotating mode. The optimum damping ratio which minimize the standard deviation of amplitude of the system under the condition of parallel oscillating has to be chosen when the natural frequency of the rotating mode is lower than that of the parallel mode.

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Use of genetic algorithms as an effective tool for searching sets of Pareto-optimal solutions in the context of multi-objective optimization problems has attracted considerable attention in various engineering fields. This paper presents a topology optimization method of framed structures using a genetic algorithm and the generalized transfer stiffness coefficient method (GTSCM). The GTSCM is well suited for the computation of constraint and the objective function values since stress and vibration analysis can easily be conducted by simply providing the structural data corresponding to the genotype of the individual. Two-objective optimization problems that minimize the total weight and maximize the first natural frequency under the displacement and the stress constraint are formulated, and a genetic algorithm based on the ground structure approach is developed. The present algorithm fully utilizes the benefits of the GTSCM in order to efficiently improve computation. Effective methods of genetic operations for the optimization of topology problems are also proposed.

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Estimation of time-varying vibration parameters, that is, instantaneous damping and frequencies by the wavelet transform is based on the ridge identification and the phase extraction in the time-frequency map. However, there are some problems in easiness to operate the technique. The process of the ridge identification is rather complicated, and the most suitable mother wavelet to yield a time-frequency map for the efficient identification is not determinately chosen. In this paper, we propose a segmental use of the harmonic wavelet in order to estimate the time-varying vibration parameters. The segmental harmonic wavelet is implemented in combination with the Fourier transform, which is utilized to set bounds to frequency range. It shows significantly good results compared with the simple application of the Hilbert transform. The time-varying parameters pertaining to nonlinearities are successfully estimated by the proposed method. A possibility of the proposed method to a diagnosis of a mechanical element is also demonstrated.

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Hydrodynamically air-lubricated foil journal bearings are prospective applicants for machine elements that can support a small-sized rotor of high-speed rotary machinery, such as a micro gas turbine. The smooth surface of the bearing deforms elastically, depending on an applied bearing load, since it is a flexible foil that is supported elastically. Bump foil journal bearing is a kind of the bearings. The bearing consists of two foils. One is cylindrical and named as a top foil. The other is corrugated and named as a bump foil. The top foil is supported elastically by the bump foil. As the foils are forced into the bearing sleeve in assembling the bearing, the top foil deforms due to the assembly preload from the bump foil. The previous prediction was conducted without the preload being considered. This study aims at predicting the maximum load capacity of the bearing with the preload, by using two models. One corresponds to the bearing with an infinitely static friction between the two foils and the other to the bearing without the friction. It is found that each of the bearing design variables has an effect on the capacity obtained with the preload being considered.

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Vibration behavior and unstable phenomena of multi-connected bodies supported by damper-spring elements moving in a narrow flow passage are reported. These vibration phenomena have been often observed in high-speed trains running in tunnels, cleaning robots going through pipings and so on. The fluid forces acting on the multi-connected rigid bodies are obtained analytically on the basis of the Navier-Stokes equations applied to a narrow flow passage. The equations of coupled motion of the multi-connected bodies and fluid are derived. Using coupled equation, a stability analysis is performed. The effect of the flow velocity and number of bodies on the coupled mode is investigated. The influence of the boundary conditions of fluid pressure at connecting points is also investigated.

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Differential pressure transmitter with an orifice is widely used as a major field flowmeter. Most of the trouble of this flowmeter on the operation site is blockage of impulse line, which connects an orifice tap with a differential pressure transmitter. In this paper, firstly, the relation between the pressure fluctuation in the impulse line to oil flow and kinetic viscosity (1.0x10^-5 to 3.0 x 10^-5 [m²/s]) is investigated as well as the relation between the pressure fluctuation and operating condition. Then, our method of the impulse line blockage developed through experiments in a water line is applied to an oil line. The effectiveness of our detection method with multi-sensing differential pressure transmitter to the oil line is shown. As a result, following facts are clarified : 1) High viscous fluid contained in impulse line does not reduce each pressure fluctuation at the differential pressure transmitter. 2) High viscous flow has small pressure fluctuation, however, this fluctuation has the same characteristics of impulse line blockage as that in a water line. Therefore, our method can detect impulse line blockage at any operating points in high viscous fluid line as well as in a water line.

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This paper deals with nonlinear liquid surface and interfacial wave motions in a tank containing two incompressible irrotational fluids of different densities. In theoretical analysis, we employ Hamiltonian formulation to derive a canonical equation of this system. The time histories and the transitions of surface and interfacial wave motions in a rectangular tank and circular cylindrical tank are given by solving the canonical equation of this system. Moreover, we have focused in particular on the N-Wave Resonant Interaction (NWRI) and investigated occurrence conditions of the NWRI. On the other hand, The validly of the theoretical analysis is verified through the experiments. These results are in good agreement with each other.

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In the flux-path control magnetic suspension system, the force acting on the floator is controlled by moving a control plate made of ferromagnetic material, which is located between the permanent magnet and the floator. In this paper, the three-dimensional attractive forces acting on the floator were measured with a manufactured load cell and two sets of plate springs with strain gauges. The force actuating in the vertical direction is measured with the load cell. The force actuating in the horizontal direction is measured with the plate springs with strain gauges. These measurements clarify the relations between the positions of the control plates and the three-dimensional attractive forces. In addition, stable three-dimensional positioning was achieved by applying PD control. PD control is also applied to the flux path control modules to provide them sufficient stiffness and damping property to suspend the floator. In addition, several dynamic characteristics were measured in each direction.

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The authors are developing a vibration simulator, which consists of field-portable exciters (actuators) and data processing software, to estimate vertical vibration and riding quality of railway vehicles. One of the main characteristics of the vibration simulator is that the acceleration power spectral density (PSD) at arbitrary point on the carbody while running is synthesized numerically from measured data obtained when each axle box or each wheelset is excited individually. This paper focuses upon the data processing method of the simulator. A series of excitation tests for a commuter vehicle was carried out to confirm the basic concept to estimate the PSD by using the rolling stock testing plant as exciters. Some excitation methodologies and data processing formulae are compared among each other in this paper. It is clearly shown that the estimated PSDs well agree with actual PSDs. It is found out that the estimation gives high accurate results when acceleration values at only excited axle boxes are used in estimation analysis.

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Bending vibration characteristics of railway vehicles have been investigated in general under excitation tests, in which a carbody was directly excited by a shaker. It is however very difficult with their results to evaluate the ride comfort of passengers under a condition that the vehicle runs on a certain track. The authors are therefore developing a “vertical vibration simulator” for railway vehicles. The simulator consists of a excitation system equipped with linear actuators, the elastic supporting device installed between wheels and rails, and analytical techniques to estimate the power spectral density (PSD) and the ride comfort level (L_r) which feature the ride comfort. In this paper, we describe the excitation tests performed using an actual commuter car and the estimated PSD and LT are compared with what substantially measured under the running conditions.

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The overturning possibility for the vehicle running at very high speed subjected to the base excitation is investigated. One-half of the whole vehicle is analytically modeled. The vehicle consists of the body and the truck. The body and the truck have 3 degrees of freedom (horizontal, vertical and rolling direction) respectively, and the wheel has 1 degree of freedom (horizontal direction). Considering the stoppers, the springs between the body and the truck, and that between the truck and the wheel are treated by the nonlinear springs. The creep force and the contact between the flange of the wheel and the rail are considered. The vibrational behavior of the vehicle is calculated when the vehicle is subjected to the actual seismic input in horizontal and vertical directions simultaneously. The possibility of rollover of the vehicle is evaluated by “risk rate of rollover”. The risk rate of rollover of the running vehicle is investigated both in a straight track and a curve track.

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The decrease of wheel load variation is one of the most important issues which must be solved in railway dynamics. The purpose of this study is to make clear the mechanism of wheel load variation by the numerical simulation by the analytical model which is based on the concept of the multibody dynamics. In this study, we were able to figure out the in-depth mechanism of the wheel load variation, particularly, concerning the phenomenon that the wheel load variation suddenly decreases with more than wheel velocity at which the 1st natural frequency of system consists with the irregularity passing frequency.

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Suppression of the vertical bending vibration of carbodies has recently become an essential issue to improve the ride comfort of railway vehicles. For suppressing this vibration, the primary suspension damping force control system with variable axle damper is being developed, which can control its damping force continuously by command current to the damping force control valve. This paper reports the results of numerical simulations for running test applying this system to Shinkansen vehicle, and the results of the running test on Sanyo-Shinkansen line using an actual Shinkansen vehicle fitted with newly-developed variable axle dampers. The control algorithm which controls axle dampers is based on skyhook control theory in one case and LQG control theory in another case. The results of both the simulations and the running tests demonstrate that the vertical vibration of the trucks and the carbody decreased. In the running tests in particular, the system reduced the vertical vibration acceleration PSD peak value due to the natural vibration in the first bending mode by almost 20% compared with the case of using conventional passive axle dampers. As the result, the value of ride quality level (L_r) was reduced by about 3 dB or more.

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The vibration suppression of a helicopter is very important to ensure the comfort and the safety. In some kind of helicopters, the pendulum absorbers are adopted for the purposes to reduce vibrations. Present pendulum absorbers are designed based on the anti-resonance concept in the linear theory. However, since the vibration amplitudes of the pendulum are not small, it is considered that the nonlinearity has influence on the vibration characteristics and the best suppression cannot be attained by the linear theory. Also, the characteristics of the pendulum absorbers are not well analyzed even in the linear theory. In a helicopter, periodic forces act on the blades due to the influences of the air thrust. These periodic forces act on the blades with the frequency which is the integer multiple of the rotational speed of the rotor. In our previous report, we proposed a 2-degree-of-freedom model of the rotor blade and the pendulum absorber. The blade is considered as a rigid body and it is excited by giving a sinusoidal deflection at its end. In this paper, we proposed a 3-degree-of-freedom model which is more similar to the real helicopter since the freedom of the fuselage is added and the periodic forces are applied to the blade by air force. The vibration is analyzed considering the nonlinear characteristics. The resonance curves of rotor blades with pendulum absorbers are obtained analytically and experimentally. It is clarified that the most efficient condition is not the exact tuning to the frequency of the external force but slight detuning to it. Various unique nonlinear characteristics, such as bifurcations, are also shown.

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In order to investigate the effects of individual body shape differences on brain injury occurring in traffic accidents, we created hybrid-models for representative bodies or head shapes in Japanese male, which consist of multi-body models for full-body and head FE models. Firstly, traffic accident simulations were carried out by using five multi-body models of the full-body, which are average, small, large, skinny and fat body shapes in Japanese male. The multi-body models were constructed using only body height and weight data, which can be easily measured and obtained. The constructed individual body shape can have smooth outer shape by using shape transformation method combining scaling with skinning deformation. The simulation results showed that individual differences in full-body affect the occupant dynamics, compared to other factors such as seat position, belt position and body posture. Next, the rigid body motions of the heads obtained in the simulations were applied to the head FE models having boundary shapes in distribution of head shapes in Japanese male. The head FE models were created using Multi Dimensional Scaling (MDS) and Free Form Deformation (FFD). The results showed that individual differences in head shape influence stress distribution in the intracranial space greatly.

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Biomass resource draws more and more attentions as an alternative fuel for energy crisis and atmospheric environment protection. The small size gas engine in a distributed power generation system is an efficient system to use it because biomass resource is stored in large area and its energy density is low. However, calorie of gas fuel converted from biomass is low, and gas composition is affected by resource, gasification method, furthermore, gasifying condition changes its composition momentarily during engine operation. So, gas engine needs to be operated stably and with high thermal efficiency under these fuel fluctuations. This study aims to develop a small size gas engine system with biomass gas by modifying the control system of a conventional spark ignition engine. The engine control system for biomass gas was developed, which could analyze fuel component in real time by measuring in-cylinder gas pressure. With this control system, automatic engine operation was succeeded to be operated stably under different fuel composition percentage changing from methane to the simulated biomass gas.

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This paper discusses the seek control for head positioning mechanism with a contact slider in hard disk drives (HDDs).In General, to increase the control force is the most popular step used to decrease the seek time; it often results however in transient vibration of HDDs that has start and stop motion. For high-speed, high-precision seeking mechanisms, it is necessary to apply control methods which induce no residual vibration at a target track even with a large control force. The proposed positioning control system consists of two-degrees-of-freedom controller. The optimal point-to-point (PTP) control with a frequency-shaped weighting function is employed in feedfoward input design to eliminate vibratory responses due to mechanical vibration modes. To estimate and compensate the friction force of the contact slider generated by the contact of a disk and a slider, a equivalent disturbance estimate observer is designed. The validity of the proposed approach has been verified by long span seek simulation trials in the benchmark problems for HDDs.

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This paper proposes a control method for the crank-slider mechanism as the active mass damper (AMD). Vibration isolation systems with spring support cause an increase in oscillating displacement at a natural frequency. Crank-slider mechanisms have been used for many kinds of industrial machines. A system of elastic supported machine frame with crank-slider mechanism can be expressed as time-varying system depends on crank angle.A state equation which contained variable parameters in coefficient matrices is derived from non-linear equations of motion. A controller is adapted the gain-scheduled control method for frame vibration reduction, and the linear velocity control method for crank motion control. State feedback gains are calculated by the linear quadratic regulator (LQR). The proposed method is confirmed by analysis and experiment. As results, the system is reduced disturbance vibration by using the slider as active mass. Furthermore, the system can consist of low costs since the existing mechanisms are used.

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Recently, research and development has focused on robots that work in place of people. It is necessary for robots to perform the same flexible motions as people. Additionally, such robots need to incorporate high-level safety features in order not to injure people. For realization of such robots, we need to develop a robot hand that functions like a human hand. At the same time, this type of robot hand can be used as an artificial hand. Here, we present artificial muscle-type pneumatic actuators as the driving source of a robot hand that is both safe and flexible. Some development of robot hands using pneumatic actuators has already taken place. But, until now, when a pneumatic actuator is used, a big compressor is needed. So, the driving system also needs to be big; enlargement of the driving system is a major problem. Consequently, in this research, we develop a low-pressure, low-volume pneumatic actuator for driving a robot hand that works flexibly and safely on the assumption that it will be in contact with people. We develop a five-fingered robot hand with pneumatic actuators. And, we construct a master-slave system to enable the robot hand to perform the same operations as a human hand. We make a 1-link arm that has one degree of freedom using a pneumatic actuator, and construct a control system for the 1-link arm and verify its control performance.

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Active noise control (ANC) in 3-dimensional sound field, e.g. an office room, is investigated in this paper. Since the size of the controlled area normally depends on the wave length of the target noise, it is difficult to control in the whole room using ANC technique. Instead, around-head-control is investigated in this paper. To realize the around-head-control, an evaluation point is required to correspond with the head movement while controlling. However, the evaluation point movement while controlling has not been considered in a conventional ANC. Against this problem, the new algorithm is proposed in this paper. The algorithm calculates filters as function of position by using a Time-Delay filter and a Distance-Attenuation coefficient. The Time-Delay filter and the Distance-Attenuation coefficient are calculated from the position of the evaluation point. Computer simulations with acoustic characteristics in an anechoic chamber and an ordinary room are carried out. The validity of the proposed algorithm is shown from these simulations.

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The purpose of this study is to apply Active noise control (ANC) to 3-dimensional space. Direct Adaptive Algorithm (DAA) proposed by Sano et al. is an effective algorithm because pre-identification of the secondary path, the path from a control source to an error microphone, property is unnecessary for this algorithm. However DAA has a problem that the control effect is affected by input noise level. Against this problem, we propose DAA with Step Size Auto Adjusting Method (DAA-SAM). This method normalizes signals into adaptive filters by reference signal. The normalized signals are used in updating adaptive filters. The validity of DAA-SAM against different input levels of white noise or unsteady noise is shown through computer simulations and experiments.

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This paper deals with active control of transmitted sound power of a panel subjected to an incident sound wave. Based upon modal actuation reported in previous works, this paper presents modal actuation-based control for the purpose of reducing transmitted sound power of a panel. From a viewpoint of acoustic power modes, a dominant factor in structure-borne sound, a fundamental mechanism of sound transmission power of a panel is clarified, followed by a numerical analysis. It is shown that the (1, 3) structural mode (one of the elements of the first acoustic power mode) plays an important role in the sound transmission mechanism, and hence the (1, 3) mode needs to be extracted and suppressed. For this end, three cases of actuation method are presented, control effect in terms of each control strategy being discussed. Finally, an experiment is conducted, demonstrating the significant control effect achieved by suppressing the transmitted sound power at low frequencies using the proposed method in this work.

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System control and identification often require accurate estimations of velocity and acceleration with a reduced group delay and lowpass property to attenuate high-frequency noise. This paper proposes a novel design method of FIR filter for estimating velocity and acceleration from sampled displacement data, where the filter coefficients are derived by piecewise Radial Basis Function Network (RBFN). The proposed FIR filter not only provides more accurate estimates in comparison with a conventional method, but also achieves the prescribed lowpass property and the specified group delay in the passband. The theoretical analysis of RBFN in the frequency domain derives the relationship between the frequency response of the FIR filter and width/regularization parameters in RBFN. Finally, the procedures for designing the filter are summarized with a design example.

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We propose a new collaborative control framework between the time varying design parameter in the control object and the feedback controller. The framework can be regarded as an extension of the integrated design of structural and control systems to time varying systems. The control design problem is formulated as the simultaneous optimization problem that seeks the optimal time varying design parameters of a plant with an LPV system representation, and the feedback controller for the LPV plant. As the control law we adopt the LMI based gain scheduling control that satisfies the closed-loop Y₂ gain constraint against the variation of the time varying design parameter of the control object. After the gain scheduling controller is obtained the tuning rule of the time varying design parameter of the plant is determined to improve closed-loop performance. We refer to the present control strategy as Active Gain Scheduling Control (AGSC) because the scheduling parameter in the gain scheduling control system is actively changed by control designers. Under the AGSC framework we can apply various methods to obtain the optimal time varying design parameter in the plant if the time varying design parameter stays in the class that is assumed in the gain scheduling controller design. An example of the AGSC method for a mechanical system with a time varying structural design parameter is presented.

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A coupled inverted pendula model of competition and cooperation is proposed to obtain a purely mechanical implementation of dynamics comparable with the lotka-Volterra competition dynamics. It is shown numerically that the proposed model can describe the desired dynamics, that the equilibrium points can be compared to ecological coexistence, dominance, and scramble, and that there are initial conditions neighboring all the equilibrium points. It is also shown that the proposed model can produce competitive dynamics comparable to martial arts tricks.

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This paper proposes a new method of handling microchips. The process of handling is as follow. First, a water drop is made at the head of the nozzle. Second, the nozzle downs so that the water drop touches the chip. Third, the nozzle is lifted up. Then the chip comes to the bottom of the water drop automatically due to the gravitational force, which is called self-centering effect. Then the water drop is suctioned for the chip to be held at the head of the nozzle. This method has an advantage of catching up and positioning a chip displaced from the center of the nozzle due to the self-centering effect. Fundamental performances of this method are studied experimentally.

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In vehicle systems occupational drivers might expose themselves to vibration for a long time. This may cause illness of the spinal column such as low back pain. Therefore, it is necessary to evaluate the influence of vibration to the spinal column. Thus the modeling of seated human body is conducted in order to evaluate the effect of whole body vibration to the spinal column. This model has the spinal column and the support structures such as the muscles of the back and the abdomen. The spinal column is made by the vertebrae and the intervertebral disks that are considered the rigid body and the rotational spring and damper respectively. The parameter of this model is decided by the literature and the body type of the subject with respect to the mass and the model structure. And stiffness and damping parameters are searched by fitting the model simulation results to the experimental measured data with respect to the vibration transmissibilities from the seat surface to the spinal column and the head and with respect to the apparent mass. In addition, the natural modes of the model compare with the result of experimental modal analysis. The influence of the abdomen and the muscles of the back are investigated by comparing three models with respect to above vibration characteristics. Three model are the proposed model, the model that has the spinal column and the model that has the muscles of the back in addition to the spinal column.

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Quadruped animals switch gait patterns with walking frequency for energy-effective walking. This is similar to the phenomenon that excited natural vibration modes are switched with vibration frequency in a MDOFs system. Therefore, in this paper, it is assumed that quadruped animals walk by using the natural vibration of their own musculoskeletal systems. In the simplest rigid-body-link model consisting of a body and four legs, there are the natural vibration modes similar to the gait patterns (trot, pace and gallop) of quadruped animals. However, all the natural frequencies in the model exist near the natural frequency in the free leg, and are accordingly different from the walking frequencies of actual quadruped animals. In the rigid-body-link model added a scapular and a pelvic on observations of quadrupted walking, the natural frequency of the gallop mode corresponding to high speed walking raises greatly and approaches the walking frequency. If the physical characteristics of horses were applied to the rigid-body-link model added the leg's joints, the natural vibration in the model is close to the gait patterns of horses.

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In this paper, we propose the touch panel's operation by using human fingernail and finger. And we developed the control circuit that measured X, Y coordinates and the electrostatic capacity in the resistive type of touch panel for this realization. In this research, the size of the touch panel is 213 x 160 mm, and the LED indicator is set up on the reverse side. In this device, the measurement of the coordinates and the electrostatic capacity was possible. Moreover, the input of human fingernail and finger was able to be judged according to the electrostatic capacity. The operation test presenting human the instruction by LED's lighting was executed. In this test, the input of fingernail was a tendency to distribute downward from the input of finger, and the deviation of these inputs was almost equal. Moreover, the inside success area of 90% was about 12 mm according to the relative frequency. The operation of these inputs has suited the Fitts' law because the contribution rate is above 0.8 in the operation time and the index of difficulty.

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This paper describes the classification algorithm of the driving steering intention based on brain-computer interface (BCI) using electroencephalogram (EEG). The classification algorithm of the driving steering intention was examined and developed. Experiments were conducted with 5 able-bodied subjects using driving simulator (DS). The drivers were instructed to operate the vehicle according to the series of three kinds of instructions (right steer, left steer, straight running, and stand by). Those instructions were given to the subject with random order, after the operation trigger had been signaled. The off-line analytical result shows that the driver's steering intention can be classified.

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It seems that the emergence of intelligence in an autonomous robot exists in the dexterity of human or creatures as complex systems and the research style and the development procedure along this approach should be necessary for realization of a real intelligent robot. On the other hand, since the severe judgment of situation is required during stabilizing control of an unstable system like an inverted pendulum on a cart by human operators, it can be expected that human operators exhibit a complex behavior occasionally. The previous paper acquired the skill of human operator and investigated the possibility of the formation of complex system in the learning process of human operators with difficult control objects. It also considered the mechanism of robustness of human operator against the disturbance. The identified neural network controller from time series data of each trial of each operator showed well the human-generated decision-making characteristics with the chaos and the large amount of disorder. This paper showed that the estimated degree of freedom of motion increases and the estimated amount of disorder decreases with an increase of proficiency. It also showed that the agreement between simulated and experimental values for the degree of freedom of motion and the entropy ratio is particularly good when the simulated wave form and the measured wave form resemble in appearance

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