The noise generating mechanism of reciprocating air compressor for heavy duty vehicles at idling was analyzed. It was realized that the gear rattling noise of the engine gear train caused by the negative value of the air compressor drive torque was a major noise source. For reducing the gear rattling noise, a loading apparatus with an air cylinder that cancels the negative value of the air compressor drive torque was newly made. As the gear rattling disappeared when the loading apparatus operated, the impulsive sound level was reduced about 10dB(A).

View full abstract

A rational reduction method using real constrained mode is developed in order to analyze accurately a nonlinear vibration and stability generated in a large-scale system with locally strong nonlinearity. In the present method, the state variables of linear nodes are transformed into the modal coordinates, and the modes with significant effect on the computation accuracy of the solution are extracted. On the other hand, the remaining modes with small effect are appropriately approximated and are eliminated. The very accurate low-dimensional model is constructed by these procedures. The effectiveness of the present method is verified from the computational results for the straight-line nonlinear structure as a fundamental example.

View full abstract

In this paper, an analytical approach for nonlinear forced vibration of a multi-degree-of-freedom system is proposed using the component mode synthesis method. The whole system is divided into some components and a nonlinear modal equation of each component is derived using the unconstrained vibration modes. Finally, the dynamic responses of the whole system can be obtained. As a numerical example, a simple five-degree-of-freedom system is considered, in which all spring have cubic type nonlinearity. As a result, it is shown that even if the lower vibration modes of each component are only adopted, the accurate dynamic response near the first resonance can be obtained.

View full abstract

In order to obtain a highly accurate periodic solution for systems based on a Duffing equation with snap-through spring, an averaging method, which has been improved through the use of the Jacobian elliptic function, is proposed. Solution by combined Jacobian elliptic delta and zeta function are used as the generating solution of this averaging method. The proposed method is applicable to periodic solution of half swing mode of snap-through spring system. The method's validity is verified by comparing the results obtained by applying the proposed method to typical nonlinear oscillators with the very accurate numerical solutions computed by the shooting method.

View full abstract

In this paper, vibration in wet friction systems with paper-based materials as seen in wet clutches in automatic transmissions was investigated experimentally. The experiment was conducted on the condition using two types of lubricants. It was shown that the vibration phenomena depended greatly on the relationship of the friction force to the relative velocity on friction plate that characterize lubricating oils. On one lubricant condition, these characteristics limited the minimum relative velocity during vibration. On another condition, the difference between kinetic and static friction limited the minimum relative velocity. This limit determined the steady-state amplitude.

View full abstract

This investigation deals with the rocking response of a rigid block subjected to 1-dimensional harmonic excitations with minute changes of the system parameters, such as the frictional coefficient, and the excitation parameters. The numerical analysis program is developed to solve the nonlinear equations of motion governing the rocking motion of a rigid block subjected to horizontal base excitation. Natural change of the frictional coefficient is realized by the random numbers with normal probability distribution. The analytical results showed that the response of the block is very sensitive to small changes of the friction condition between the block and the base and their effect is also large. The minute change of the friction coefficients makes the rocking response unstable and the distribution shape of rocking response change massively. Those effects by the dynamic change of the friction coefficients should be considered when seismic stable condition of block structures.

View full abstract

This paper describes vibration analysis using finite element method for two viscoelastic blocks connected by a nonlinear concentrated spring. One of the blocks is supported by another linear concentrated spring. The restoring force of the nonlinear concentrated spring has cubic nonlinearity and linear hysterisis damping. Finite element for the nonlinear spring is expressed and is connected to the viscoelastic block modeled by linear solid finite elements in consideration with complex modulus of elasticity. Further, the discretized equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. This transformation yields computation efficiency. Influences of share of dissipated energy on nonlinear frequency responses for the viscoelastic blocks are clarified.

View full abstract

Auto parametric damper of a pendulum in which a rotational spring and damper are used as restoring force is reported in this paper. An initial displacement and/or an initial velocity are needed for parametric resonance of such a pendulum type damper. It is confirmed in the experiment that the damper is automatically resonant due to offset angle of the pendulum position independent of initial conditions.

View full abstract

In this study, the occurrence of subharmonic tone in a nonlinear beam supported elastically subjected to a harmonic excitation is investigated. When the values of the spring constants in the springs supported at both ends have particular ones, a beam may have its natural frequencies in a ratio of prime integer. To analyze the problem in the above case, the purturbation method of multiple scales is used. The analysis shows that subharmonic tone of multimode type can occur. The occurrence of the subharmonic tone predicted theoretically is confirmed by numerical simulation.

View full abstract

Resonance responses for two dimensional beam structures were investigated under gravity. When the beam structures are consisted of extremely thin flexible components, the shapes of the structures are changed due to their self-weight. And then, their resonance response affected by the deflections. To analyze these phenomena, discrete equations using finite element in consideration with geometrical nonlinearity were derived as cubic simultaneous nonlinear differential equations. Linear natural frequencies and nonlinear resonance response for the deformed structures were calculated using proposed FEM. In the numerical analysis, both ends of the beam structures were assumed to be clamped. The calculated results for straight beams using FEM were consistent with the theoretical results carried previously by authors. Further, influences of self-weight on resonance response of a structure, which was comprised of three straight beams, were clarified.

View full abstract

Several papers are treating problems of vibration analysis of a beam with breathing cracks. However, those papers are regarding the change in the stiffness due to the opening and closing of the crack as prescribed periodical change. The opening and closing of the breathing crack depends on the curvature, or the bending moment, of the beam. Thus in order to grasp the effect of the breathing crack on the vibration characteristics accurately, a breathing crack model which opens and closes depending on the bending moment should be used. In this paper, a procedure of analysis for steady-state vibration of a beam with brteathing cracks is presented. In the presented procedure, the finite element method based on the mixed variational principle is used to derive the governing equations of motion. Then, the governing equations are solved by the harmonic balance method. An example of the analysis by the presented procedure is given.

View full abstract

Experimental and analytical results are presented on chaotic oscillations of a shallow double-curved shell-panel with initial imperfection. At the boundary, the shell-panel is simply supported. The shell-panel is excited by lateral periodic acceleration. Chaotic responses are generated in two specific regions of the exciting frequency. The chaotic responses are examined by the Poincare projections, the Fourier spectra and the maximum Lyapunov exponents. Contribution of modes of vibration to the chaotic responses is analyzed by the principal component analysis. The chaotic oscillations are generated by the sub-harmonic resonances of 2/3 and 1/2 orders. The chaotic oscillations involve the dynamic snap-through transition. From the results of the principal component analysis, it is found that experimental results of the vibration modes that contribute to the chaotic oscillation agree well with the analytical ones.

View full abstract

This paper deals with experimental results of countermeasure against the polygonal deformation phenomena accompanied by wear. The authors made an experimental equipment which has a single degree-of-freedom polygonal deformation system and a dynamic absorber. According to the results of the experiments using and not-using dynamic absorber, it is confirmed that dynamic absorber has the delaying effect of polygonal deformation phenomena accompanied by wear. and influence of parameters of dynamic absorber on the delaying effect of polygonal deformation phenomena accompanied by wear.

View full abstract

This paper deals with a countermeasure against pattern formation phenomena generated on thin sheet winder using dynamic absorbers. The thin sheet is widely used as paper, aluminum, etc. Pattern formation phenomena of the wound sheet sometimes occur in operation because of the viscoelastic characteristics of the sheet. The pattern formation phenomena lead to a fatal damage on the thin sheet. The authors conducted experiment to generate the pattern formation using experimental apparatus, and theoretically analyzed to clarify the mechanism of the pattern formation phenomena considering the elastic deformation of the rolls. They also theoretically examined the countermeasure to suppress the phenomena by attaching some dynamic absorbers.

View full abstract

While the contact rotating systems are operating, the periodic polygonal deformation patterns are often formed on the peripheral surfaces of rolls. Such phenomena are called pattern formation phenomena. In the previous report, the authors introduced an optimum design method of dynamic absorber for one or two degree-of-freedom systems by using a new stability analysis method to prevent the pattern formation phenomena and the effectiveness of the method was confirmed. In this report, an efficient design of dynamic absorbers is proposed for multi DOF systems. This method is one of designing each dynamic absorber one by one for each mode. This design method results in an efficient and effective design of dynamic absorbers for multi DOF systems.

View full abstract

There is a neocortex in human brains which may give us important functions. In this study, we suggested a neural network which had the structural characteristics of the neocortex and might have the functional characteristics of it. The present neural network had hierarchical network system consisting of many auto-associative neural networks. The performance of this network was compared with that of the conventional auto-associative neural network for pattern recognition of alphabets. As a result, some performance of the suggested one was higher than the conventional.

View full abstract

To achieve the movement of the multidegree-of-freedom system by the distributed control, the synchronization phenomenon of the self-excitation oscillator of two mass connected by spring that was a basic element was examined in this paper. when two oscillators connected by a damper, they are the asynchronize in the range that the coefficient of viscous damping is small. In the viscous attenuation coefficient is some size, they synchronize . both two oscillator are oscillation. In the viscous attenuation coefficient growing, they synchronize . one is oscillation and the other hand is damping.

View full abstract

This paper describes a transitional wave phenomenon in synchronous flashing of fireflies. We used self-excited oscillator, consists of amplification element, saturation element and phase delay element. To simulate a transitional wave phenomenon, the self-excited oscillator simulated the firefly shouldn't be late from the detection of the flashing of other self-excited oscillator. The period of self-excited oscillator in the transient state depends on strength of own flashing and changes. Strengthening strength of own flashing, perceived the flashing of other self-excited oscillators, the timing of flashing shifts and withdraws by correcting it at a constant period. This is a transitional wave phenomenon.

View full abstract

This paper describes a numerical study of Belousov-Zhabotinsky(BZ) reaction as a pattern formation phenomenon. BZ reaction is known as a chemical reaction colored chemical wave expanded from several points on the surface of the medium and produces a special geometric pattern. The purpose of this research is to simulate the process that the chemical wave generated periodically falls into disorder as the reaction proceeds, and finally the chemical reaction is completed. To simulate these processes, numerical simulations using Cellular Automata(CA) were performed.

View full abstract

In the present study, acoustic wave propagation in an enclosure surrounded by fractal walls is simulated and studied using Cellular Automata(CA). CA is a discrete system which consists of finite state variables, arranged on a uniform grid (cell). CA dynamics is described by a local interaction rule, which is used for computation of new state of each cells from the present state at every time step. In this paper, the influence of fractal shaped boundary structure on resonance and sound absorption characteristics is investigated for two dimensional acoustic wave propagation model using CA. Local rules are provided for construction of fractal patterns as well as representation of wave propagation phenomena. Direct numerical simulations are performed and sound pressure distribution and resonance characteristics are obtained for evaluating fractal level influence on sound attenuation.

View full abstract

Experimental studies have been conducted to clarify the influence of horizontal harmonic excitation on the dynamic stability of a slender beam under vertical harmonic excitation. Three kinds of aluminum test beams with rectangular cross section have been used. The test beam was vertically stood clamping at one end and free at the other end. And it was harmonically excited to both vertical and horizontal directions simultaneously. The direction of the horizontal excitation was taken parallel to one of beam side faces. By varying the horizontal excitation amplitude, keeping the excitation amplitude in the vertical direction, the influence of the horizontal excitation has been investigated on the principal instability regions in which unstable vibrations occur..

View full abstract

Experimental and analytical results are presented on chaotic oscillations of a suspended curved panel with square boundary. The configuration of the curved panel is deformed by initial deflection and static deformation due to the gravity force and to in-plane elastic constrait. In the analysis, the initial configuration of the panel is assumed as a suspended curved form with double arc along each edge, because mainly the gravity force affects the static deformation of the curved panel. The chaotic responses of the curved panel are examined with the Poincare projection, the Fourier spectrum and the maximum Lyapunov exponent. The chaotic oscillations are generated by the sub-harmonic resonance of 1/2 order with the lowest mode. Experimental and analytical results of the chaotic responses agree well with each other.

View full abstract

This paper presents the damping vibration analysis of fiber reinforced plastic composite plates. For this purpose, the governing equations are formulated for a cross-ply laminated, simply-supported rectangular plate based on Classical Lamination Theory(CLT), First-order Shear Deformation Theory(FSDT), Higher-order Shear Deformation Theory(HSDT) and Discrete-Layer Theory(DLT), respectively. In the numerical examples, natural frequencies and specific damping capacities of the plates with different stacking sequences and dimensions are calculated numerically by assuming complex elastic modulus. Finally the applicability of each analytical model for damping analysis is studied by comparing with numerical results obtained respectively.

View full abstract

An analysis for damping of laminated beam with partially covered viscoelastic layer is presented. In this paper, vibration damping properties of three layered beam are analyzed by CEM(Complex Eigenvalue Method). Eigenvalue and eigenvector (displacement functions) are analyzed based on the Ritz method, when natural frequency, modal loss factor are obtained. The modal loss factor is defined as a ratio of imaginary part and real part for complex eigenvalues. Numerical results are presented for parameters, such as location and length for the viscoelastic layer.

View full abstract

Lightweight railway vehicle carbodies have complex flexural vibration characteristics. Simple structure model is necessary to investigate the vibration characteristics of the carbody. The transfer matrix method is used to analyze bending vibrations of the railway vehicle carbody. The carbody is modeled as a simply-supported cylindrical shell without end plates. The cylindrical shell consists of several cylindrical panels that are uniform in the axial direction. Effects of each panel property on the vibration are numerically investigated in detail and the effect of the end plates are also discussed by comparing with the results of finite element analysis.

View full abstract

The objective of this research is to investigate the vibration characteristic of the blade of a camera shutter unit. The shutter blade is a thin platy part which is combined four different shape narrow plates and two different length support arms. Measurements are carried out by the forced vibration testing method on different component parts of shutter blade. The results show that the shutter blade has two resonance frequencies in variable frequency range. And it is clear that these peak frequencies are different from that of the unit plate test. But one of them is agree with the resonant frequency of the single arm. In addition, the center of gravity position of the shutter blade has an effect on the resonance frequency.

View full abstract

A piezoelectric speaker has some strong points compared with a dynamic speaker. It is easily made small and light due to its simple structure. Also, it is excellent in sound reproduction in the middle and higher frequency ranges. But, the sound pressure level in the lower frequency range is poor because of the amplitude of vibration being small. Up to now a great effort has been made to improve the performance of the piezoelectric speaker, but no definite solution has been found yet. In this paper, the vibration and acoustic characteristics of piezoelectric vibrator unit with conical shell structure are investigated through F.E.M. and B.E.M. analyses and experiments. Based on the investigations, a new cone type piezoelectric speaker system is designed and manufactured, and its characteristics are discussed.

View full abstract

The laser ultrasonic method is nondestructive evaluation method that uses short, Q-switched,pulse laser to generate and CW(continuous wave) laser to detect ultrasonic waves. It has an advantage that the sensors are no need to be contact with the specimen surface. And it has gotten a lot of attention recently such a new non-destructive inspection. In this paper, laser-generated ultrasonic wave in a carbon steel sheet is received by piezoelective transduser, and we measure board thickness from the experimental results.

View full abstract

This paper studies the topology optimization for inner ribs of aluminum hollow extruded shell structures by using genetic algorithm. In the optimization, total mass of the structure is minimized under the constraint conditions with respect to maximum deformations of the structure. The deformation of the structure is evaluated numerically by using the finite element analysis developed for two-dimensional elasticity in the present study. In numerical calculations optimal design solutions are obtained for the structures by specifying the allowable maximum deflections of the structure, and the effect of topology of the ribs are studied from the numerical results obtained.

View full abstract

This paper presents the optimization for nonlinear vibration of laminated composite, circular cylindrical shells by using Multi-Objective Genetic Algorithm(MOGA). For this purpose, a backbone curve equation for primary resonance of the shell is first derived from nonlinear vibration analysis using the harmonic balance method analytically. In optimization, fiber angles for each lamina of a symmetrically balanced laminated shell are taken as discrete design variables, and then nonlinear natural frequency and linear natural frequency are considered as object functions to be maximized. In numerical calculations Fonseca-type MOGA with sharing is employed for the present problem and parete optimum solutions are obtained. Finally optimal stacking sequence of the shell is studied by considering both of the linear and nonlinear vibration characteristics of the shell.

View full abstract

The effect of plate thickness is studied on the optimum lay-ups of laminated rectangular plates by considering the shear deformation through the thickness. Analytical approach is presented to calculate the natural frequencies and mode shapes of the thick plates. Boundary conditions at the plate edges are arbitrary sets of free, simply supported and clamped edges. The layerwise optimization(LO) approach is used as an optimization tool to make the fundamental frequencies maximized. Numerical results are successfully presented to clarify the thickness shear effect on the optimum lay-up designs of the laminated plates. In general, it is shown that the shear effect causes relatively small changes in the optimum lay-ups while the natural frequency is reduced to a large extent.

View full abstract

This study proposes an optimum design approach for vibration of shallow shells with non-uniform curvature. First, the analytical procedure is explained by introducing an interpolating function for the required surface shape, and the frequency equation is derived by following the Ritz method. Secondly, a layerwise optimization(LO) is used to maximize the fundamental frequency of the shells. In numerical results, the effects of non-uniform curvature on the optimum natural frequencies and lay-ups are discussed.

View full abstract

In this study, an elastic nonlinear Ritz analysis is used to study the buckling behavior of axially loaded imperfect fiber reinforced polymeric cylindrical shells. Parameter studies on the effects of initial geometric imperfections demonstrate the existence of well-defined lower bounds to buckling loads and the dominance of characteristic incremental deformation modes as this lower bound is approached. For the fiber reinforced polymeric composite shells as for the isotropic shells, it is shown that the reduced stiffness method provides reliable estimates of these lower bounds to buckling loads and consequently provides an important basis for design.

View full abstract

The 2003 Tokachi-Oki earthquake caused severe damage to oil storage tanks due to liquid sloshing. Six single-deck floating roofs had experienced structural problems as evidenced by sinking failure in large diameter tanks at the refinery at Tomakomai, Japan. The pontoon of floating roof might be buckled due to circumferential bending moment during the sloshing. The content in the tank was spilled on the floating roof from small failures which were caused in the rap welding joints of pontoon bottom plate by the buckling. Then the floating roof began to lose buoyancy and submerged into the content slowly. The failure of the roof expanded gradually in the sinking process. It is presumed that the initial small failures were caused by the elastic buckling of the pontoon due to circumferential bending moment. This paper presents the buckling strength of the pontoon using axisymmetric shell finite element analysis. Linear elastic bifurcation buckling analysis is carried out and the buckling characteristics of the pontoon with ring stiffeners are investigated.

View full abstract

Internally pressurized torispheical shells can fail either buckling or by plastic collapse. Many design equations for predicting these failure pressures in perfect and fabricated torispherical shells are proposed in the literatures. The predictions of the equations are compared with the experimental results and the validity of the equations is investigated.

View full abstract

A new method to measure the pulse wave velocity in blood vessel was studied because the velocity is one of signs to show arteriosclerotic. Assuming one dimensional wave propagation, the wave velocity can be determined by the pressures measured at three different point along the x-axis. This method is effective even for arbitrary boundary conditions. Fundamental experiments of the wave velocity in silicon rubber tube were executed to certify the new method. Experimental results suggest that the new method might be used to the blood vessel of human body.

View full abstract

The vibration of vocal folds results in the sound source for all voiced sounds in speech. This vibration is induced by the airflow that is expelled through glottis, and causes a series of the pulses of the airflow. These pulses excite vocal tract and bring about the passive resonance of the vocal tract in all voiced sounds. Therefore, detailed study of this airflow is believed to be important to elucidate mechanism of human phonation with the help of simultaneous observation of vocal fold movement, more specifically, glottal opening by means of high-speed digital camera. Thus in the present study experimental analysis of this airflow just above glottis was made to clarify phonation mechanism and seek better modeling of vocal folds, focusing on direct measurement of airflow velocity by means of a tiny hot-wire probe. The experimental results show that the periodic change of the airflow velocity occurs out of the phase of opening of glottis, though both have the same fundamental frequency. This fact is important since it gives a crucial hint for better simulation model of phonation mechanism.

View full abstract

Chaotic analysis of pulse wave is paid attention as one of the sleep prediction technique to prevent traffic accident with drowsy driving. It is necessary for this method to verify assuredness and to reduce calculation time. The purpose of this study is to validate the evidence of this sleep prediction method by comparing the results by wavelet analysis of the heartbeat variation and/or the brain wave. As a result, it is found that the timing of sleep detecting signal obtained by chaotic analysis of pulse wave corresponds well to the emerging timing of HF component of the heartbeat signal.

View full abstract

We developed the device that calculates and displays joint moments at the same time with motion. Joint moments and center of gravity points are calculated with Inverse Dynamic Analysis and Kinematic Analysis. The quality of motion can be objectively judged by displaying those physical parameters. In the application of this real-time device to the education of sit-to-stand motion, we showed that this device is useful for the motion education.

View full abstract

It is known that the ecological signal and the kinematical signal for a healthy person have chaos property while those for a disease person have little chaos property. And there is a central pattern generator in human that controls the kinematical motion and it has a synchronous property to environments. In this study, the influence of sound around a person is investigated on the chaos behavior in the case of gait. As a result, the chaos behavior decreases under the regular sound environment while it increases under the chaos sound environment.

View full abstract

In this paper, the influence of sports equipments on the muscles and skeleton of human arm during impact is focused. A case is considered where a ball strikes against a tennis racket, which is fixed by hand and arm. A multi-degree-of-freedom model of the ball and racket is constructed by finite element method, and human hand, lower arm and upper arm are considered as an individually rigid linked model. The joint moments are calculated when a ball strikes against a racket using modal analysis technique. Then, some muscles are adopted and a musculoskeletal model is constructed. The muscular forces are identified such as to satisfy the joint moments by the optimization method. Finally, the influence of property of racket on the muscles is investigated.

View full abstract

Many hemiplegias use Ankle-foot orthosis to prevent stumble and falling when they walk. In order to support natural walking of hemiplegias, a new self-powered semi-active ankle foot orthosis including a DC motor and step-up chopper circuit used to regenerate energy is developed. The charged voltage is obtained by simulation and the experiment circuit under various conditions. And gait experiment using this ankle foot orthosis are carried out. From the experimental results, it can be seen that this system can generate 80 percent of the consumed electric power.

View full abstract

The dynamic response of a human body excited torsionally is investigated in this paper. The response of human body standing on twisting floor is measured experimentally. It is found from experimental results the response curves have two resonance peaks. Then, human body is modelized by two-degree-of-freedom system, and the parameters of the system are identified experimentally by minimum square method. Measurements of some people are carried out, and difference of dynamic property by age or BMI is considered.

View full abstract

Analysis of coupled vibration of the arm, the tennis racket and the ball is important to understand the performance of the racket and to prevent sports diseases when people play tennis. The human system is modeled as musculo-skeletal model taking activity level into account, and the ball and the racket are modeled by masses, rigid links, respectively, which are connected by springs and dampers. By coupling the dynamics of the ball, the racket, and the human system, the coupled equation of motion is derived. Inverse-dynamics is employed and the torque is derived from the swing behavior. Furthermore, the neural network system is introduced to obtain the value of the muscular activity level. Finally employing the experimental swing data, we show dynamic interaction among the racket, the ball and the human system.

View full abstract

Vibration characteristic of a passenger in a vehicle seat widely differing by seating postures and seat properties. Therefore, to evaluate the comfort factor while riding, it's necessary to evaluate vibration characteristic separately between human and seat itself. Thus, to predict vibration characteristic of passenger on a vehicle seat, initially we disconnectedly model the passenger on rigid seat and the seat cushion and the backrest by using a multi-body model. Finally we combine these models together. In this method, intended frequency range was below 3Hz and input vibration direction was horizontal because of the attention given to seat support.

View full abstract

We developed the method to construct a high shape fidelity multibody model for specific individual by the height and weight only. In the method, individual body shape is created by transforming the basic body shape data, which has average height and weight. The constructed individual body shape can have smooth outer shape by using shape transformation method combining scaling with skinning deformation. Mass distribution of each segment are defined by their body dimensions. Results of falling impact simulations by using both high-shape fidelity and ellipsoidal models showed both the importance of shape fidelity for human model and consideration of individual difference in body shapes.

View full abstract

A lot of handicapped people feel endangered when they travel in the vehicle with them sitting on the wheelchair. But no safety standard is applied to the handicapped people sitting on the in-vehicle wheelchair during driving. The object in this study is to make models to simulate the behavior of handicapped people on the wheelchair. Human body sitting on the wheelchair is expressed by a link segment model of two degrees of the freedom with muscle reflection in which Hills' muscle models are applied and muscle activity is modeled. The carriage on which the wheelchair is fixed and handicapped people sat on the wheelchair was run into the fixed rigid wall through shock absorber. The cervical angle and muscle activity were measured and they are compared with the simulation result.

View full abstract

It is necessary to evaluate the influence of whole body vibration to the spinal column and to make up appropriate guidelines or counter plans. For assessment of the vibration effect, the vibration responses of the spinal column are important. One of the measurement ways of the human response is to use a dynamic dummy that represents the response of vertebrae under whole body vibration environment. The purpose of this study is to construct the vibration dummy that represents the response of the spinal column. This paper presents the outline of our dummy and the current preproduction prototype dummy.

View full abstract

A major cause of the elderly's falling is decent of motor function. However, it is difficult for older people to understand exactly how much they lose the physical and sensoriums functions which play essential roles of posture control. The present study hypothesized that the sequential control of hip plays an important role in the movement of the whole-body center of mass during quiet standing and walking. The hypothesis was investigated using a double-inverted pendulum model and experimental measurement during a postural sway on the frontal plane. The comparison between the proposed model and the data measured from the subjects found importance of performance index based on mechanical energy considering combination of the upper and lower body.

View full abstract

So far, it has been shown that the minimum-torque-change model with fixed boundary conditions is effective in reproducing characteristics for human reaching movements. However, the conventional model had no ability to reproduce the variability of end points of the hand trajectories in human reaching movements. This report focuses on formulating a new human arm control model with free boundary conditions, a modified minimum-torque-change model, to overcome the defect of the conventional model and examining the proposed model's fundamental performance. As a result, it was clarified that the modified model can reproduce the end-point variability of the hand trajectories by changing its weight parameters and the relationship (Fitts' law) between the end-point variability and the movement time. This suggests that the modified model is more effective as a model of the human arm control system.

View full abstract