Some conventional railway tracks are subject to lower maintenance criteria, unlike Shinkansen lines. This usually implies large vertical irregularities and/or depressions at the rail joints, which are a known cause of vertical rigid-body-mode vibration of the car body. Since suppressing such vibration is necessary for improving ride comfort, a secondary suspension damping force control system with variable vertical dampers (a vibration control system) is being developed. For improving the performance of vibration suppression of the system, a control technique taking into account forced vibration caused by running through depressions at the rail joints was proposed. While the vehicle runs at a constant speed, the frequency of the forced vibration stays constant. Therefore, the weighting functions for controlled variables are set with a large value at the frequency so as to reduce the forced vibration selectively. This paper reports the results of the running test using an actual meter-gauged railway vehicle applyed the proposed technique, and the technique can effectively suppress vertical rigid-body-mode vibration of the car body.

In this work the dynamic characteristics of a double-cone, self-propelled on a straight V-shape horizontal rail, are evaluated. Such simple mechanism can be regarded as a gravitational motor, which transforms the input potential energy into kinetic energy, of rotation and translation. Movies of the freely rolling double-cones, made of carbon steel and wood, against V-shape horizontal rails, made of aluminum alloy, were taken for various opening angles of the rails. Number of rotations, the variable rotation period, and the total traveling times of the double-cones were determined through the slow motion processing of taken movies. Several theoretical models were proposed and validated against the experimental results. One proved that the Hertzian contact point moves on the conical surface along a logarithmic spiral. Based on the proposed dynamical model, the traction force and the traction torque acting on the double-cone were identified. One proved that the traction force is always smaller than the translation friction force. However, the double-cone is able to self-propel on the rails if the traction torque exceeds the rolling friction torque. Results obtained in this work can be used to achieve the proper design of such gravitational motor.

This paper proposed a topology optimization method to realize acoustic cloaking by minimizing scattering waves around a cloaked cylindrical obstacle placed in unbounded air medium. In this study, we develop a two-phase material model mixed with a solid and fluid phases to express an elastic material and an acoustic material in a unified represenation. By applying the model, boundary conditions at boundaries between different two-phase materials are satisfied naturally, and are not needed to be imposed. Then, we formulate an optimization problem to realize acoustic cloak utilizing the two-phase material model and a level set method to express boundaries between different two-phase materials. Topological derivative of an objective functional is considered to be proportional to the derivative of the level set functions with respect to time and the values of the level set functions are updated by solving time evolutionary reaction diffusion equation with a regularization term. An approximate method to obtain topological derivative is also developed by applying the variational analysis and the adjoint variable method. Several numerical demonstrations are presented for directional acoustic cloakings.

Improvement of the quiet performance of the car is an important factor for comfortableness during running. In particular, running noise influences ride quality. As a method for reducing noise, paste nonwoven-like sound absorbing material using a resin fiber such as polyester into the passenger compartment, it is contemplated. On the other hand, it is necessary to excessive use of the sound absorbing material is avoided because it is also required weight of the vehicle weight from the viewpoint of environmental performance. Therefore, it is important to use the minimum of the noise absorbing member in proper alignment. By applying the structural optimization techniques, it is possible to solve these problems and to perform a uniform design. Among them, topology optimization is the most design flexibility is high technique, it is applied to many problems as a structure optimization can be simultaneously determine the optimal shape and form. In this study, using the topology optimization method, find the optimal layout of the sound absorbing material to maximize the damping effect. In the input frequency, it was confirmed that there is an effect to maximize the energy dissipation.

Less weight is demanded in the automotive development. However, lightweight facilitates the propagation of vibration. Therefore, less damping material must be used in order to solve the problem. For determining the optimal placement of damping material, this research suggest a optimization method using dynamic compliance. Dynamic compliance expresses vibration energy stored in the structure. Especially the imaginary part shows the magnitude of energy dissipation.

Improvement of the quiet performance of the car is an important factor for comfortableness. In particular, Running vibration influences ride quality. There are two solutions of this kind of vibration. These are vibration damping effect by damping material and vibration suppression because of stiffness enhancement by structural material. On the one hand, reduction in weight of vehicle is also required from the point of view of the environmental performance. For this reason, damping and structural materials shouldn't be used more than necessary. Appropriate material arrangement becomes important. At Mazda Motor Corporation the body structure which makes the vibration attenuation effect maximize has been developed without sacrificing quiet performance and road holding ability by the body weight saving. Propagation of vibration to compartment of the car is suppressed by using damping frame structure which consists of damping and structural materials. The weight saving, usability enhancement, noise and vibration reduction effect are made possible by damping frame structure. The purpose of this study was to build Multi-material topology optimization of damping and structural materials for improvement of vibration suppression effect.

Pattern noise generated at contact surface of rolling tire should be suppressed to secure comfort of passenger in vehicle compartment. Frequency of pattern noise ranges around 1 kHz, therefore quarter wave length side branch is too long to design at tread surface of tire. Recently, Helmholtz resonator has been applied to reduce peak level of pattern noise. However, the neck part of the resonator is considerably narrow, hence acoustic dampings arising on the boundary between air and surrounding structure should be taken into account to predict quantitatively pattern noise level. In this study, air in the neck part of a Helmholtz resonator is considered as compressible viscous fluid and is modeled by Low Reduced Frequency (LRF) method. Analytical solution of a cavity with a small resonator is derived to save computational cost assuming that the neck part is one-dimensional tube and back cavity is rectangular acoustic field, By applying the derived model, the positions attached to the main cavity and the neck dimensions are designed to improve damping characteristics of Helmholtz resonator.

Excellent quietness of passenger compartment of vehicles is demanded for vehicles with low interior noise such as electric and hybrid vehicles. Therefore, the investigation of acoustic transfer function of passenger compartment of vehicles is required to increase these quietness. The coupling effects between passenger compartment and trunk of vehicles affect acoustic response of the passenger compartment at the low frequency in sedan type vehicle. Air leakages and vibration of poroelastic materials of a rear seat between the cavity and the trunk are also known to affect acoustic response of the cavity at the low frequency. However, most studies of the coupling effects between the cavity and the trunk do not consider the influence of poroelastic materials of a rear seat between the cavity and the trunk. In this study, we investigated acoustic transfer function of the cavity of vehicles that is affected by poroelastic materials of a rear seat. The experimental results showed that poroelastic materials reduce the acoustic response of the cavity at low frequencies and change the coupled natural frequencies. The calculated results showed that poroelastic materials of rear seat can be modeled by Biot's theory. The calculated results also showed that poroelastic materials of a rear seat can be modeled by elastic materials if there is no air permeability. Then, theoretical study is made using a one-dimentional mathmatical model. The features of coupled natural frewuencies could be explained by this model.

This paper describes vibration analysis using finite element method with Model Strain Energy Method for elastic frames with a damped panel connected by nonlinear concentrated springs under impact load. The panel is composed of a steel panel with a damping material. Damping material is made of viscoelastic body. And the panel has a curved surface. Finite element for the nonlinear springs are expressed and are connected to the elastic frames with the panel modeled by linear solid finite elements in consideration of complex modulus of elasticity. The restoring force of the spring has cubic nonlinearity and linear hysteresis damping. We calculated Modal loss factors and transient responses including internal resonances in the eigen modes among the non-linear springs, the panel and the frame structure. The non-linear discretization equation is converted from physical coordinate to normal coordinate corresponding to linear natural modes. Using this method, the responses in the large-scale degrees of freedom problems, were analyzed at high speed. And the dominant eigen modes contained in responses are picked up. Calculations were performed on the curved panel and the flat panel. We compared the obtained results. From the dominant eigen modes and the time histories, we clarified effects of the damping materials, the curvature and non-linear springs on the nonlinear damped responses.

This paper proposes a new method to identify the material parameters used in Biot's model for sound-absorbing poroelastic media. In this method, the macroscopic properties for sound-absorbing poroelastic media are calculated by using the homogenization theory based on the method of asymptotic expansions. Then, the material parameters used in Biot's model such as the air flow resistivity, the tortuosity and the characteristic lengths are identified either directly or by using a least square method. In the process to obtain the macroscopic properties, elastic motions of the solid phase, compressible viscous fluid flow and the thermal conductance from fluid phase to solid phase are taken into account. Utilizing several models that have simple microscopic geometry, we demonstrate the method can give the reliable material parameters used in Biot's model.

This report deals with sound absorption coefficient prediction technique of ultrafine fiber. As the sound absorption material used for the interior noise reduction of the automobile, the fiber with a diameter of several μm is considered. When a fiber diameter becomes small, usually a sound absorption coefficient increases. But predictive precision was bad by the conventional performance prediction technique. I developed the technique to predict a sound absorption coefficient from the fiber diameter and the fiber density and the material thickness and the material density. The experiment expression of relations was drawn from the experimental results about the flow resistivity and the thermal characteristic length. And I introduce the technique used Limp frame model to predict a sound absorption coefficient for the ultrafine fiber. There diameters are 1-4μm. This paper shows comparison of the experimental results and the calculation results, and this technique is useful.

This report is about response analysis using Statistical Energy Analysis (SEA) with FEM for two panels connected in L-type shape. We adopt two panels with viscoelastic damping layers and the panel connected in L-type shape as substructures. One of the panels has a curved surface and the other panel is flat. There are viscoelastic layers on the panels. Usually, modal damping is influenced by shape of panels and forms of the connection. Therefore, to consider coupling in damping between substructures, we use FEM and MSE (Modal Strain Energy) method to identify Internal Loss Factors (ILF). We get the Coupling Loss Factors (CLF) using the Element Energy and ILF. For us to verify whether a numerical value of the proposed method is right, we compare the results from this method and those from direct FEM. As a result, we show that this method is able to get SEA parameters (ILF and CLF) of the high precision for the damped panel having curved surface. This method shows that the precision of the response calculation in the low frequency range as well as in the high frequency range could be improved.

Sound-absorbed poroelastic materials are applied on vibrating structures to suppress noise inside a closed compartment. These materials generally reduce transmission of vibration and absorb noise generated in a closed compartment. In this work, we propose new functions by using transmissibility of volume velocity and dissipated power to evaluate performance of sound-absorbed poroelastic materials applied in a closed cavity as alternatives to conventional sound absorption coefficient and transmission loss that may have some difficulties to be adopted in closed environment.

This report shows effect of sound insulation by adhesion of porous materials and film laminated panel. It deals a technique for estimating damped vibration of automotive body panels with sound-proof structures. It calculates damping properties for sound-proof structures involving elastic body, viscoelastic body and Biot type porous materials by three-dimensional finite element method. In this analysis, particle displacement vectors for internal air in the porous materials are adopted as unknowns for the discretized equations for finite element method. And displacement vectors for frame in the porous materials are also selected as the unknowns. A numerical code is developed. For numerical examples, Biot type porous materials are sandwiched between panel and film, and laminated film. Frequency response functions were calculated for panels laminated with porous material (felt) and viscoelastic body (film) and porous material (felt) using this technique, the calculation results almost agreed with the experimental results. And effect of the vibration performance by with/without adhesion is clarified. At with adhesion, the internal air and the frame in the porous material are same vibration. But at without adhesion, the internal air and the frame in the porous material are greatly different vibration. It is thought that change of sound insulation takes place by this.

Dynamic response of standing human body excited torsionally is investigated. A human body standing on a twisting floor is excited torsionally with frequency 0 ～ 4 Hz. The angular displacements of chest and waist of the human body are measured by optical position sensors. It is found from measured results that standing body of human has two resonance points near about 1 Hz and 2 Hz. Standing human body is modelized as a two degree-of-freedom torsional vibratory system, and system parameters are identified by using measured data. In the identification, mass moment of inertia is estimated from mass distribution of human body, and it is assumed that the response of human body has a dead time component. Stiffness and damping coefficients are identified by least-square method. Another experiment in which additional mass is attached to chest and waist is conducted, and influence of change the mass moment of inertia is investigated. It is found from the another experiment that the stiffness of upper and lower parts of human body are changed as the change the mass moment of inertia, and the resonance frequencies are kept almost constant. Damping property of human body has similar tendency to the stiffness.

In order to enhance an additional value of cars, comfort improvement of an occupant is strongly demanded. Evaluation of ride comfort is important for improving quality of comfort, and it is always carried out by an experimental approach. If the dynamic behavior of the occupant can be simulated in a model, the occupant comfort evaluation will probably be carried out more efficiently in numerical calculation in design stage: this leads to shorten the development period. Therefore we attempt to create the driver and the passenger models separately in order to simulate occupant behavior on driving car. In this paper, firstly, the vibration experiments performed to observe differences in vibration response between the driver and the passenger. Subjects sit on a simplified seat with two seated postures (driver and passenger) and are exposed to the composite vibration of lateral and roll sinusoidal waves simulating the slalom running. Translational displacements and roll angles of body parts of them are measured. The experiments showed that characteristics of vibrational response of the driver and passenger are different from each other. Secondly, with focusing on the passenger, on the basis of the characteristics, the passenger is modeled and simulated on equal condition with the experiments. Finally, the driver is modeled and simulated, too. This model is created on the basis of the passenger model by adding some changes to the model. And the simulation results of these models are qualitatively similar to the characteristics of the corresponding situations (driver and passenger) of the experiments.

The purpose of this study was to analyze the influence of racket on human motion in badminton smash motion. To analyze it, we made an experiment using three badminton rackets. The smashes of 14 males were selected for the analysis, and were digitized. Performances were recorded by twelve motion capture cameras. In this study, we analyzed a position in the vertical direction of each marker and angle of joints and considered a characteristic of the smash motion at the time of using each rackets. The results showed that there were characteristics of the smash motion, such as opening the elbow at the time of take-back, turning the wrist and a difference in timing of raising up the badminton rackets. Moreover, it proved that their characteristics differed by the motion experience and skill. And we calculated a standard deviation to analyze a difference in the motion between using the rackets. As a result of this analysis, a difference in dispersion of the smash motion was observed depending on using the rackets by the standard deviation. In addition, some inexperience persons could be close to motions of experience by changing the rackets. Therefore, the result showed that it was very important to select a racket suitable for them.

Previous studies, which calculate dynamic contributions of the whole-body joint torques to the generation of bat head speed by using the equation of motion for whole-body with bat system, showed that the motion-dependent term is the largest contributor to the generation of the bat head speed at the ball impact, and also showed that joint torques of the upper limb joints and the torso joint are the main contributors to the head speed with consideration of the generating factors of the motion-dependent term. These results do not tell us the roles of the lower limb joints in the bat head speed generating mechanism. So in order to quantify the roles of the lower limb joints in the mechanism, we quantify the dynamic contributions of the whole-body joint torques to the generation of forward/backward rotational motion of the lower trunk segment during baseball batting motion. Five collegiate baseball players participated in this experiment. They performed hitting a teed ball as strong as possible. Kinetic data of each hand and each foot were obtained by using an instrumented bat equipped with 28 strain gauges and 3 force platforms, respectively. From the results, the flexion/extension torque of both hip joints showed the largest contribution to the forward angular velocity of the lower trunk segment against the large negative contribution due to the torso joint torque. This result indicates that these hip joint torques play an important role to exert large rotational torque at the torso joint, and these hip joint torques show indirect contributions to the bat head speed.

The collision accident in collegiate football game was simulated based on the game video and the concussive impacts on the head were analyzed. First, the collision motions of players were reproduced based on the video by using MADYMO software, and the translational and rotational velocities, relative position and contact location of the struck and the striking players' heads just before the collision were calculated. Then the data obtained were input to two helmeted finite element head models as the initial condition, and the brain injury risk was evaluated. In the present study, 2 accident cases concussion suspected were analyzed; The results showed that the all peak values belonged to the dangerous range that may cause concussion and were consistent with the diagnosis of the medical team doctor. It means that the brain injury risk can be estimated by the reconstructed simulation of the game video and finite element analysis. To our knowledge, this study is the first attempt in Japan to estimate the brain injury risk systematically by a combination of game video analysis which is originally introduced for the players' health care and finite element analysis by helmeted human head model.

Many women undergo lumbopelvic pain (LPP) during pregnancy. The main factors for LPP are the physical stress related with change of posture and muscle relaxing around pelvis. Also it is thought that movement patterns during daily activity are associated with LPP. Therefore, this paper attempts to investigate the characteristic of movement patterns that have affect LPP during pregnancy. For this purpose, an experiment was conducted to measure standing up and sitting down of pregnant women using inertial sensor unit (IMU), which is simple device and is able to measure motions such as vibration or rotation quantitatively. Then movement evaluation parameters were calculated from measured data of lumber angular velocity. As the movement evaluation parameters, Maximum peak, Minimum peak, Peak to peak (PP: Range between Maximum peak and Minimum peak), Time of PP, PP divided by Time of PP, Root mean square of each parameter, and each parameter divided by BMI were calculated during both of stand up and sit down for each of roll, pitch, and yaw angles. Finally, we consider whether there is any relevance between LPP and movement characteristics by comparing the movement evaluation parameters of LPP group with these of non-LPP group. As a result, it appears that Maximum peak, PP/Time of PP, Maximum peak/BMI, PP/BMI, (PP/Time of PP)/BMI of pitch angle have some relevance to LPP.

This study had been conducted to predict foot temperature and to understand thermal behavior of rubber sole under cyclic compression. Three EVA samples of different compression characteristics were used in this study. In cyclic compression experiment, temperature changes of EVA samples were measured. As a result, temperature elevation of EVA16 was higher than other samples. In the stepping experiment, temperature changes of foot and EVA were measured. As a result, EVA08 and EVA16 showed different temperatures change tendency. Through two experiments, EVA of high tanδ showed high temperature elevation. Numerical simulation for predicting of foot temperature was built by consideration of the internal heat generation of EVA. As a result, numerical simulation qualitatively agreed with the stepping experiment. So numerical simulation in this study could show tendency of foot temperature elevation by EVA of different tanδ. However, temperature in numerical simulation was slightly higher than measured temperature. Result of numerical simulation in this study was indicated the need to consider radiation of foot and EVA.

This study focuses on the balance modeling of human body on frontal plane. For practical use, the model should be effective when its support surface moves to horizontal direction in low frequencies below 1 Hz. The frequency range allows us to regard the mechanism of the model as a single degree of freedom system. Then the balance model can be expressed as a transfer function whose input is acceleration of the support surface and output is moment acted from support surface to hold human body balance. To obtain the transfer function model being stable, three characteristic roots of the model were estimated from impulse response test. Finally, the third-order transfer function model was derived from frequency response test. The results of frequency response test indicated that they are reproduced and acceleration of the support surface and posture of human body become inverted in low frequency range (< 0.2 Hz). To verify the effectiveness of the identified models, state estimation based on full-order state observer and full-state feedback control to keep the subject 's balance easily were applied in experiment. Although it is possible to estimate and control the state variables of human body, the accuracy is insufficient to aid the balance control of human body standing on moving board. The result indicates that dimension of the model should be higher than third order in our future work.

In this study, we logically and scientifically clarify psychological estimations of badminton players on badminton rackets which influence on their performance. Experiments are composed of two parts in this study. Evaluation trees are hierarchical constructions which compose the psychological estimation. At first experiments, we took questionnaires of evaluation grid method to get evaluation trees of badminton rackets. And then we extracted words to make questionnaires of SD method for second experiments. At second experiment, we took questionnaires of SD method and got evaluation indexes of psychology. We took analyses of radar chart, cluster analyses and principal component analyses to clarify psychological estimations. As a result of analysis of radar chart, personal preferences have been charted. As a result of cluster analysis, subjects have been sorted into four groups by their tendencies. And as a result of principal component analysis, subjects have been sorted into four groups from a different perspective with plot of first and second principal component score. In addition, tendency of questionnaires have been shown by plot of first and second principal component loading. Those results have clarified psychological estimations on badminton rackets.

It was appeared that the evaluation of optimum diameter depends on the size of the arch contacting with the cylinder. In this study, the influence of grip position of the cylinder in the hand on the sensory evaluation of the easiness of the grasp with one hand and with both hands was investigated. In case of the cylinder attached on the boundary between the little finger and the palm, i.e., MP grip, the optimum diameter evaluated as the most easiness to grip was around 20mm. On the contrary, in the case that the cylinder is grasped in the arch formed with index finger and the thumb, the evaluated optimum diameter was around 30mm to 40mm, and it was around 40 mm to 50mm, in the case of grip with both hands. It was appeared that the evaluation of optimum diameter depends on the size of the arch contacting with the cylinder. In addition, it was revealed that the sensitivity of the evaluation is higher in the active grasping than in the passive grasping having cylinders from others.

Recently, many studies of rolling resistance of wheelchair tire are being for that rolling resistance of the tire is connected with the burden on wheelchair user. Internal damping of the rubber with the tire deformation account for nearly all dissipation energy during the rotation. Considering the elasticity of the tire, deformation of the tire grounded rugged road surface with a projection differ from that grounded flat road surface so rolling resistance increase depending on road surface profile. Therefore we constructed the mechanical elastic deformation model for calculation of running characteristics and dissipation energy during rolling road surface with a projection. The relation between projection height and dissipation energy can be derived, but the model invalid for quantitative analysis so need to be improved.

Gait measurements and physical fitness tests are carried out in the community health activities for health promotion and care prevention services in the growing elderly population. In particular, the timed up and go test (TUG) is the clinical test most often used to evaluate functional mobility in many clinical institutions or local communities. To evaluate the functional mobility during the TUG, some walking parameters such as stride length, step length and step width have to be measured. A gait measurement system (Laser-TUG system) using a laser range sensor (LRS) for evaluating functional mobility in the TUG has been proposed. The system track both legs and measures the foot contact positions to obtain walking parameters. To reduce the false tracking and improve the measurement accuracy during the turning phase of the TUG, a data association considering gait phase and a spline-based interpolation have been proposed. However, the measurement accuracy during the turning phase is still deteriorated in the TUG turning phase. Therefore, this paper presents a high-accuracy gait measurement system using multiple LRSs. To improve the measurement accuracy of observed leg position, the integrated leg detection method by a weighted mean of the observation candidates observed using each LRS data based on the distance from the LRS because the measurement accuracy is depending on the distance from the sensor. From the experimental results, we confirm that the proposed leg detection method can improve the measurement accuracy of the leg trajectory and walking parameters.

Population of elderly people has been increasing not only in Japan but also in many countries. For the purpose of expanding the active field of them and persons with disabilities, and of improving their quality of life (QOL), the development of an intelligent wheelchair has been intensively studied. In this research, a new maneuver interface of the electric wheelchair instead of the joy-stick is considered. To develop such an interface, this paper deals with a simple non-contact detection method of horizontal head gesture motion using a depth sensor.

Wearable power assist suit which utilized pneumatic bellows actuators is developed. The suit is able to work at low air pressure and is to be slim and lightweight. In addition, the waist unit of this suit has a waist joint and hip joints which are assisted by the actuators independently. The obstruction of walking is canceled by this construction and the suit become able to assist walking. Further, the wearer of this suit is possible to assist patient's transfer from a low-floor bed. In order to increase the assist force to the knee, two kinds of leg units are developed. One uses newly developed lightweight air cylinder actuators to lift up the hip joints and the other uses the newly developed combination mechanism of the bellows actuators and gears. Practical utility of the newly developed power assist suit as an assisting equipment was proved experimentally.

Elderly caregivers are increasing by aging of society in Japan. One of the hardest action for them is to make a wheelchair with a person on climb a step. In order to reduce burdens of the caregivers, assistive products to ease burdens of step-climbing action are desired. The purpose of this study is to devise a mechanism to reduce caregivers' burdens when they make wheelchairs climb steps and to develop casters with the devised mechanism. Prior to the development of the step climbing mechanism, measuring experiments of forces a caregiver apply to a wheelchair in a step-climbing action is conducted using normal casters. In reference to the result of the experiment using the normal casters, the authors devise step-climbing casters with a burden reduction mechanism. It utilizes the reaction force from the step induced by an unnecessary force applied by caregivers in a step-climbing action. Mechanical analysis of a wheelchair with the burden reduction mechanism is carried out numerically to show the effectiveness of the mechanism. The result of the analysis indicates that the burden reduction mechanism reduces the total maximum force necessary to make a wheelchair climb a step, leading to the conclusion that the devised burden reduction mechanism is effective.

Robot hands with multi-degree-of-freedom employing bellows actuators are developed. The robot hands are able to move freely like human hand and are to be slim and lightweight. The robot hands consist of bellows and plates which function as joints and bones. As human fingers the plates sandwich the bellows between them. The thumbs of the robot hands are provided with the function of the saddle joint similar to a human finger. Therefore the thumbs are able to abduction and adduction and they are also possible to flexion and extension. In addition, abduction and adduction between each finger and the curvature of the back of the hand are also enables. Lightweight artificial hand weight of half the human hand is achieved by housing the newly developed very small piezoelectric pump in the portion of the arm of the artificial hand. Practical utility of the hands as an artificial hand and robot hand was proved experimentally.

The purpose of this study is to confirm the effect of the power assisted air pressured bellows experimental device on patient with hemiplegia. We used air pressured bellows as rehabilitation to joint actuator, and it was performed on hands and legs of hemiplegic patients. Moreover, we measured cerebral blood flow using an NIRS device during the rehabilitation. Each patient had individual rehabilitation menu using a power assisted device. As a result, each side has a different effect. Hemiplegia on the right side of the hand influences the left side of the brain. On the other hand, hemiplegia on the left side of the hand affects the right side of the brain. In conclusion, patients with hemiplegia on the opposite side of the paralyzed hand had a larger cerebral blood flow changes during rehabilitation.

The thermomechanical noise of a capacitive MEMS accelerometer array was evaluated by measuring the impedance around the resonant frequency. The unit accelerometer of the array was 80 μm square, designed as a scale-down of a conventional single-axis capacitive accelerometer. Since the size effect shows the capacitance sensitivity per unit volume increases by the proportional downsizing, we made a 10-by-10 array of the unit accelerometer. The accelerometer was fabricated from silicon-on-insulator wafer of 5-μm in device layer thickness. We used electron beam lithography and deep reactive ion etching to pattern 300-nm-wide gaps. We proved that the capacitance sensitivity of the array is 0.99 fF/g, which is as same as that of a single accelerometer of the same device area. By measuring the electrical impedance around the resonant frequency, the damping coefficient was estimated using an electrical equivalent circuit model. The thermomechanical noise of the accelerometer can be reduced below 10 μg/√Hz by the vacuum encapsulation at 100 Pa, which is low enough for instrumentation applications.

This report states that the dynamic sensitivity of multi-axis inertia sensors shall be defined by using matrix in the non-linear region. The previous papers tell the dynamic sensitivity in the linear region under the assumption that non-linearity can be neglected. The subject of the paper on the other hand is to show how to deal with the non-linearity. This report introduces a non-linear conversion called Maclaurin Power Transformation, in short MPT to a vector. It generates another vector with the number of components larger than the original one and with the components expressed by the power of the original components. The MPT provides the solvability condition in the non-linear region. The condition is the extension of the terms in the linear region obtained in the previous analysis and indispensable for the determination of the nonlinearity through experimental procedures. The mathematical interpretation of inertial sensors in the linear region is a mapping between the real vector space and the signal vector space. The concept of mapping holds in the non-linear region and formalized mathematically using MPT and matrix. The theory is applicable to multi-axis vector quantity measurement devices.

One of the authors had proposed a new type of active seismometer measuring such vibration possessing long period and wide dynamic range. In order to lower the natural frequency of the sensor and expand the detectable amplitude, the sensor with the lower natural frequency and lower sensitivity is realized by using feedback control. Based on this idea, authors have been developing an experimental active seismometer with feedback controller. In the previous studies, its performance is reported that the measureable lowest frequency is extended from 4.1 Hz to 0.56 Hz, while the acceptable vibration amplitude is expanded to 141 times bigger than original sensor stroke (or the sensitivity is reduced 43 dB). However, due to the limit of feedback gain, further improvement of the dynamical property solely by using feedback control is not hopeful. In this study, to compensate phase-delay of the sensor output and to expand the dynamic range, third order phase-lag compensator is added to shape physically measured output. Feedback controller and third order phase-lag compensator are designed as analog circuit and built into the sensor. Frequency transfer function of the sensor output is identified through shaking table test. It has been demonstrated that the detectable frequency range of the sensor is extended to 0.15 Hz.

Road profile affects to the vehicle. Vehicle ride comfort and control stability are depending on it. So, the road profile information is available for a vehicle to improve them. The road profile estimation for each vehicle are required form this point. Accelerometer is one of a suitable device for a vehicle to measure its motion. Vehicle motion includes effects of road profile. They also includes another motion effects. Effects caused by road profile should be separated to estimate it. Toward to this problem, Independent Component Analysis (ICA) seems to be available. In this case, ICA can provide estimated road profile displacements from measured acceleration signals. However, estimated road profiles do not include displacement unit since this method is strongly depending on statistic theory. It means estimated signals from ICA should be modified based on mechanical point of view. So, estimated signal should be added mechanical meaning from other signal that are measured in same time. In this paper, the adding method is also introduced as a part in proposed method. Then, shaking table test was carried out to validate proposed methods. In this test, real vehicle was sat on it. The shaking table inputs displacement oscillation to vehicle each tire. And, accelerometer were set on vehicle body and chassis. The proposed methods have estimated shaking table input displacement from acceleration signal measured on a vehicle.

The purpose of this work is to present expanding structures using pairing origami method. Two mirror symmetry crease patterns are bonding in this folding method, so the folding condition at the bonding part is no need to be taken into account. In general, as the folding condition must be considered in drawing the crease pattern of the collapsible three-dimensional structure, it is time-consuming and the crease pattern is complex. In this method, the crease pattern is simple and a complicated work is not needed, then three-dimensional expanding structures that industrialization has been considered difficult would be allowed for industrialization.

Nowadays, self-protection is a very important issue for everyone, and it is an urgent request to invent a helmet which is convenient for storage, for example, the one which is not disturbing to pass through the passages between desks and enough small to put in lockers in class room. There are many foldable helmets in market, but they can be folded in one direction only, so those folded states are not small enough for general request. Therefore, we challenged to invent a helmet which is foldable in two directions. In this competition proposed by NHK program, we should invent a hat which is foldable into compact shape and also strong enough to absorb shock-energy as much as present helmets. Those requests remind us to design energy-absorbing for car collision; decreasing the peak of force for energy-absorbing material and lengthening deformation-stroke as much as possible. It is also necessary to invent a cover of head which is foldable into a box regulated by NHK. Even if we can find a foldable cover small enough, it can absorb small amount of shock-energy, and so we should attach some energy-absorbing materials enough to protect heads. Hence by using Origami technology for development and contraction of material, we found a design of a helmet with corrugated cardboards which suffice absorbing shock-energy, and in the competition we could win the competitor who were also very strong. Anyway, since we realized how much the Origami technology is useful through those experiments, we decided to write those results in a paper.

Two pairing origami structures have been attracting attention as a three-dimensional version of the Miura-Ori. Here, as a typical example, we treat Nojima polyhedron (NP) and Tachi-Miura polyhedron (TMP) to check the validity as an energy-absorbing material. Effectiveness as an energy absorber of reversed spiral cylindrical origami structure (RSC); the amount of energy absorption is 1.7 times the current hollow hat-shaped cross-section structure, no excessive initial peak load by a flat characteristics of relation between load and displacement, to extend the crash time by inverting. Although its effectiveness was shown, it is not always easy to use practically by relying on expensive hydroforming. On the other hand, NP, there is less initial peak load, shows a gentle characteristics of relation between load and displacement, that variation lasts up to 90 per cent of its own length, and the manufacturing costs inexpensive, so it is shown that there is a possibility as an energy absorbing structure.

Creating complex spatial objects from a flat sheet of material using origami-folding techniques has attracted attention in science and engineering. It is extremely difficult to introduce highly versatile automation using machines to handle deformable objects such as a flat sheet of paper. This work proposes two machines for paper manipulations based on Lego NXT technology that use feedback error learning (FEL) with holographic neural networks (HNN) to perform precise and smooth manipulations of the paper. The first machine makes simple zigzag folding and the second machine glues the generated zigzag folded paper to generate complex 3D shapes. A new spring-back compensation algorithm is proposed to deal with paper's thickness increase after multiples folding and the change in gluing positions due to the paper spring-back phenomenon. The results demonstrate that proposed compensation approximates the generated motion trajectories to real paper fluctuations in the machines. Examples of round shapes and honeycomb patterns are shown.

The necessity for the development of micro power supply technologies for mobile phones and portable electronics has increased in recent years. Methods of self power generation using the vibration loads of structures have attracted attention as the power supply technologies. In this study, we focused on lead zirconate titanate (Pb(Zr,Ti)O3, PZT) as the generating piezoelectric element. The purpose of the study is to develop a high-efficiency PZT generator element that utilizes the vibration loads in the support members of a structure. However, piezoelectric elements only generate power in the order of several microwatts, so improving their power generation capacity is of the utmost importance. In this paper, experiments of driving the temperature transmission device using the laminated PZT elements under vibration loads of air compressor are reported. The temperature transmitting device was composed of capacitor, switching circuit, voltage sensor and temperature sensor. The charges generated from the laminated PZT element are charged by the capacitor. And it reaches to the temperature sensor through the switching circuit. As a result, it is possible to obtain the temperature information, and the laminated PZT generated an electric power for driving the temperature transmitting device by using the vibration of the air compressor. In this experiment, Receivable distance of the data has been evaluated. Based on these results, the laminated PZT can be applied to monitoring sensor and other applications.

In this paper, diagnosis technique to estimate a clogging state of the condenser using the dynamic data of the air conditioner was proposed to optimize the cleaning time of the condenser in a data-center. Dynamic model of a condenser was determined based on the heat balance between the refrigerant - air - condenser in the condenser. Input data and output data measured under normal condition was used to determine model parameters. To estimate a clogging state of the condenser, target input data was inputted into the model and compared output data from the model with the measured output data. In the case that difference between model output and measured output was large, clogging occurred. In this paper, dynamic data of an air conditioner was gotten under the condition of outside temperature of 15 degrees Celsius and 35 degrees Celsius. Our proposed technique was checked using measured data and showed good performance regardless of outside temperature.

In recent study, active thermography has reached a high status as an easy and speedy defects inspection method in a NDT field. This paper newly proposes a remote and non-contact NDT method using a sonic-IR for detecting and evaluating of fatigue cracks at runway girder of the overhead crane in the steel making plant. In this method, fatigue cracks are detected as localized high temperature areas caused by friction and collision at crack surfaces with an infrared camera, applying a high-amplitude ultrasonic vibration. In this paper, sonic-IR method is applied to remote and high-efficient crack inspection of the runway girder in the overhead traveling crane. Target crack located in high place can be detected using this method without setting up scaffolding for inspection. And the threshold of vibration amplitude to generate the sufficient heat for crack detection is clarified. Therefore the system to prevent missing the crack by unsuccessful vibration transmission from vibrator is developed applying monitoring the vibration.Time and cost saving inspection method in runway girder of the overhead traveling crane is carried out using this NDT technique.

Crack occurs on machine equipment by the unexpected load, finally machine is damaged. In order to prevent machine damage, there is an effective means to assume remaining life assessment by using the crack information that contains the load history information. In this paper, we propose for the remaining life assessment methods by the crack length information, to report a case study to the spindle of the rolling mill.

Diagnosis of the bolt loosening is important in the industrial field and the medical field such as dental implants. We have proposed a non-destructive testing method for the bolt loosening using an ultrasonic pulse that is projected to the side of the bolt. In the basic experiment, the tightening torque of the bolt can be evaluated via the instantaneous frequency, which varies from hour to hour in the pulse, of the reflected wave or the transmitted wave. The mechanism of the proposed method have been tried to verify through an identification of the transmission paths and a numerical simulation. Our conventional study have assumed that the transmission paths spread on the two-dimensional surface. However, the two-dimensional study have not been able to explain some experimental results perfectly. In this paper, we identified the transmission paths in the three-dimensional space, and tried to simulate the experimental results. For this identification of the three-dimensional paths, surface of the screw thread was divided into many planar rectangular elements. Calculating reflection and refraction of the ultrasonic pulse on each element, many transmission paths were identified. Some transmission paths that reached at the modelled receiving surface were superposed to simulate the experimental result. This simulated result had some reasonable aspects in compared with the result of the two-dimensional study however a few differences with the experimental result remained. Additionally, the three-dimensional simulation is expected to be a supplementary tool of the proposed diagnosis. Especially when the target shape is complex, this technique is helpful to predict the transmission paths and the optimum position of the transducers.

In this paper, a health monitoring methodology for a structure with bolted joints based on nonlinear piezoelectric impedance modulation method is presented. This technique uses a single piezoelectric active sensor bonded on the structure surface, which is driven by a high frequency harmonic voltage source. When the structure including a contact surface such as a bolted joint is subjected to a pump excitation at low frequency, the induced structural vibration causes a fluctuation in the driving point mechanical impedance at high frequency range because of the contact acoustic nonlinearity at the contact surface in the structure. This causes a modulation of the coupled electro-mechanical admittance of the piezoelectric active sensor, which can be observed as the amplitude modulation and the phase modulation of the current. It is known that loosening the bolt causes weakening of the contact pressure on the joint. This may result in more significant fluctuation of the contact conditions under the pump loading, leading to stronger modulation of the admittance. Experiments conducted using a bolted beam specimen showed increasing damage index as the bolt loosed. In addition, to obtain deeper understanding of the relationship between the pump load and the contact stiffness fluctuation we did an experiment measuring piezoelectric admittance when the specimen was subjected to a static load. The result suggests that the load applied to the bolted joint may affect the attenuation of the high frequency elastic wave at the joint.

A simplified screening method for a pole structure such as electric pole, light pole, signal pole, etc., using a modal-based evaluation of structural local flexibility is proposed in this paper. A ratio of the rotational local flexibility of the healthy part to that of the potentially damaged root part is adopted as a damage index, and its approximate calculation scheme is proposed. Using the proposed method, one may quantitatively evaluate the extent of the damages in the root part of the pole by conducting a vibration test identifying the first few modes. Experiments using a scaled pole specimen made of a vinyl chloride pipe shows that a transversal cut in the root of the pole specimen whose depth is 15 % of the diameter can be detected by using the proposed method.

This paper proposes an aerial robot that can land on a steel structure using electro-permanent magnets to behave as a vibration sensor probe for use in vibration-based structural health monitoring. In the last decade, structural health monitoring techniques have been studied intensively to tackle with a serious problem that most of the infrastructures in advanced countries are being deteriorated. In the typical concept of the structural health monitoring, vibration sensors like accelerometers are installed in the structure to continuously collect the dynamical response of the operating structure to find a symptom of the structural damage. It is unreasonable, however, to permanently deploy the sensors to numerous infrastructures because most of the infrastructures except for those of primary importance do not need continuous measurement and evaluation. In this case, they should be checked rather periodically, say, annually, by using mobile detachable sensor units. In this study, the aerial robot plays a role in deploying and retreating the accelerometer that is mounted on the robot body. Experiments to evaluate the frequency response function of the acceleration measured by the robot with respect to the acceleration at the point where the robot adheres are carried out. And the experimental results show that the prototype robot can measure the acceleration of the host structure accurately up to 50 Hz.

Vibration energy harvester has gained attention in accordance with the growth of the demand of wireless sensors used for vibration condition monitoring of machinery. Most conventional vibration energy harvesters consist of a linear oscillator. These devices are designed so as to resonate with the mechanical vibration for the purpose of getting large electricity. However, once the frequency of the input vibration changes, the linear oscillator cannot maintain resonance. As the result, the amount of electricity obtained by the vibration energy harvester decreases considerably. In our laboratory, we devised a test equipment of the vibration system in which resonance automatically follows the fluctuated excitation frequency. This equipment is comprised of sector-like shaped bases and a long and narrow plate spring. Under the excitation, the test equipment automatically tunes its natural frequency in such a way as to match the excitation frequency without any controllers. By applying this automatic tuning mechanism of the test equipment to a vibration energy harvester, it will be able to keep high generating efficiency even when the excitation frequency of the mechanical vibration changes. However, the detailed mechanism that the test equipment automatically tunes its natural frequency into excitation frequency has not been explained. In this paper, we conduct excitation experiments on the proposed equipment and detailed observation of the behavior of the plate spring in the automatic tuning phenomenon. As the result, a part of the mechanism of the automatic tuning phenomenon can be experimentally deduced.

A miniature piezoelectric vibration energy harvester represents one promising power source for IoT (Internet of things) device. Recently, a SSHI (Synchronized Switch Harvesting on Inductor) interface was developed to enhance its output power. However, use of external power source or of complicated circuits for switching On/Off poses a practical problem. To address these issues, we propose a mechanical switch for SSHI interface. We employed ball spring plunger and stainless steel thin plate for the mechanical switch. We demonstrated that the mechanical switch properly works as a SSHI interface. The miniature prototype harvester achieved 1.2 mW at the frequency of 35.6 Hz under the acceleration of 0.55 G, a 1.7-fold increase over the standard circuit.

Vibration energy harvesting extracts electrical energy from vibrating structures. To improve the harvesting efficiency for the electrical energy, some methods were proposed that implements switches to the harvesting circuit and regulates them for controlling the structural vibrations. Self-contained SSHI harvester we proposed was one of them. Those vibration controlling harvesting methods need to measure the vibration state because the switch regulation is based on the vibration state. In our previous studies to develop the self-contained SSHI harvester, we attached a piezoelectric sensor to the vibrating structure in addition to the piezoelectric transducer. Piezoelectric transducer is used for generating electrical energy, and piezoelectric sensor is used for measuring structural displacement. When we install the harvesting device to existing structures, the mounting of those two elements is troublesome. Thus, this paper proposes a sensor-less vibration observation method that measures the voltage of piezoelectric transducer. We develop three observers depending on the three state of harvesting circuits. The observers work alternately and estimate the state values gradually. Using this observation method, the controller of switching energy harvesting can obtain the information of modal displacement, modal velocity, and piezoelectric charge. This paper presents the construction of those three observers, and numerical simulation of them. The simulation reveals that the vibration state can be detected with the proposed observation method by measuring the piezoelectric voltage. It suggests the sensor-less harvesting device can be constructed with this method.