Study on centrifugal blower used for dust collection, air conditioning and other applications in homes, factories, etc. In this research, turbo type models were targeted. Its characteristic is to send high pressure air with high efficiency. However, its disadvantage is to generate large noises. It aims to elucidate this noise generation mechanism. In recent research, noise generation mechanisms other than the fully closed state have been elucidated. However, the experiment is difficult in the fully closed state, so research has not progressed much. Therefore, in this research, we conducted a visualization experiment in the fully closed state, and clarified the noise generation mechanism. Visualization experiments were carried out by injecting powder from the outer edge of the casing. It was clarified that the noise is generated by collision with the trailing edge of the blade. We also clarified that the collision against the trailing edge is caused by the relative flow caused by the difference between the impeller speed and the circulation flow velocity. In addition, we clarified that the circulation flow velocity decreases the most in the vicinity of the cut-off. As a result, it was found that the noise source in the fully closed state is in the vicinity of the blade trailing edge portion and the cut-off portion. Based on these results, the noise generation mechanism in the fully closed state is shown below. When fully closed, air does not flow between the blades. Therefore, the space between the blades is equivalent to the cavity. As the impeller rotates, the air inside the cavity swirls. Relative flow is involved in this vortex. Thereafter, the relative flow collides with the trailing edge of the blade, causing a pressure rise. This creates a pressure difference across the blades. Noise is generated by rotating the blades with pressure difference.

This paper dealt with a hybrid tilting-pad journal bearing, which can operate as a hydrostatic bearing at low shaft speeds and as a hydrodynamic bearing at high shaft speed. A numerical calculation method for the bearing was proposed and the effects of oil supply pressure and the preload factor on the static and dynamic characteristics of the bearing were examined. The results obtained by using the proposed method demonstrated that the hydrostatic effect of the bearing is dominant when the Sommerfeld number is low, and the hydrodynamic effect is enhanced with the increase of the preload factor.

In order to evaluate soundness of the bearing for the GG-ATR engine, its thermal characteristics were evaluated from the bearing temperature data obtained in the tests, and countermeasures were investigated for a critical situation during rated power operation. For the forward bearing, thermal characteristics evaluation and temperature history prediction had be carried out analytically. The result was showed that the bearing temperature during planned flight time does not greatly exceed the allowable temperature. For the rearward bearings, thermal characteristics could not be evaluated directly. Instead, by clarifying the cause of the bearing temperature behavior based on actual flow calculated by the internal flow network, an effective modification plan to safe operation of the bearing had been found.

As the sealing device for rotary machines such as turbo compressors, labyrinth seals are commonly using as a non-contact seal. Among other things, Step-seals (Labyrinth seal whose shaft has a staircase shape) are used in general because of good assembling and high sealing performance. In recent years, labyrinth seals have been required that further reduction of leakage along with increasing pressure of turbo machineries and for higher efficiency. In this paper, the high performance seal with easy assembling have been proposed which just have protrusions on the stepped parts in the step seal. It is suggested that sealing characteristics of proposed seal was conducted by CFD analysis and experiments. First, optimal proposal structure was shown by study of changing step height and protrusions height on the steps. It became clear that proposal seals have effect of reducing leakage up to over 30 % compared to general step seals. Experiments for confirming performance of the proposed seal were carried out and proved to be effective at any pressure. As a feature of the proposal seal, it was confirmed that this seal exerted high performance with only small protrusions, even if it has a large clearance or a large displacement in the axial direction.

In turbo machinery, bearing support structure with flexible O-rings can reduce the critical speed, and significantly suppress self-excited vibrations, such as whirl and whip. However, the flexibility could cause rigid rotor whip, if it has low damping. In this study, experimental data of rigid rotor whip are presented, which was obtained in an operation of water-lubricated turbo compressor. Numerical calculations were performed for two-dimensional motion equations for both the shaft and bearing, to clarify the influences of dynamic properties of bearing support. As a result, the rigid rotor whip appeared spontaneously, which agreed with the experimental data. The equations of motion were linearized and eigenvalue analysis was performed. The frequency region of rigid rotor whip was the same with Hopf bifurcation region at which the real part of an eigenvalue was positive. The influences of the frequency-dependent viscoelasticity of O-rings on the bifurcation frequencies were discussed.

This paper describes the vibration analyses of a flexible rotor system supported by oil bearings and the simplified prediction method for the rotational speed limits of the self-excited vibration induced by the fluid force in bearings. In the vibration analyses, the equations of motion for the rotor system are simplified and modeled as a two-degree-of-freedom system with parallel and flexural modes and eigenvalue calculations for the stability analyses are conducted. The rotational speed limits for the instability of the system obtained by the present method are compared with the calculation and experimental results in the references to discuss the validity of the present method.

A rocket turbopump is the high-speed and high-power turbomachinery, and one of major vibration sources of the rotor is associated with rotordynamic fluid forces generated by its shaft seals. In this study, we investigate the effect of rotordynamic fluid force of floating ring seal on the rotor dynamic stability up to the rated operating speed. A finite-element model of a liquid oxygen turbopump is used to analyze natural frequencies and damping ratios of the rotor system. Rotordynamic fluid force generated by floating ring seal is modeled using the cross-coupled stiffness. As a result, it was found that the cross-coupled stiffness of floating ring seal with 1/100 to 1/10 absolute value of the support stiffness is effective in improving rotor stability.

To increase rotational speed of brushed motor, it is important thing to reduce motor vibration. In brushed motor case, the rotor vibration affect the contact condition between brush and commutator, and degrade the performance and the life of the motor. To reduce rotor vibration of brushed motor that consists of brush, commutator, core, and fan, we evaluated rotor lateral vibration using linear vibration rotor model and selected arrangements and size of rotor component parts. In this paper, to construct linear vibration rotor model in consideration of casing stiffness, we calculated casing stiffness and mass by the finite element model of casing and connected these parameters with bearing stiffness on rotor model. Using this model, we designed low vibration rotor.

Common turbines have long blades to radial direction and thin to axial side. Then, gyro moment matrix has been approximated as same as a thin disk, whose gyro factor is nearly equal to 2. However, in case of cone type and cylinder type impeller, the approximation does not follow the actual situations. Thus, in this report, fundamental expression of gyro moment matrix in mode synthesis model for rotary machine is discussed. Validity of proposed expression is examined with several types of blade-shaft coupling model by comparing with 3D-FEM model. Further, derivation method of gyro moment matrix with modal participation factor calculated by 3D-FEM software NASTRAN® is discussed.

Although bladed disks are nominally designed to be cyclically symmetric (tuned system), the vibration characteristics of all the blades on a disk are slightly different due to the manufacturing tolerance, deviations in the material properties, and wear during operation. These small variations break the cyclic symmetry and split the eigenvalue pairs. Bladed disks with small variations are referred to as a mistuned system. In the forced response of a mistuned bladed disk, the responses of all the blades become different, and the response of a certain blade may become extremely large due to splitting of the duplicated eigenvalues and distortion of the vibration modes. On the other hand, many researchers suggest that mistuning suppresses blade flutter, because the complete traveling wave mode is not formed in a disk. Although such mistuning phenomena of bladed disks have been studied since 1980s, almost all studies focused on the amplification factor of the displacement response, and few studies researched the amplification factor of the vibratory stress response. Therefore, in the previous paper, authors studied the amplification factor expressed by the vibratory stress for bladed disks with continuous-ring blade structure, using the reduced order model SNM (Subset of Nominal Modes), and pointed out that the amplification factor of the displacement and the vibratory stress is different. This work is a follow-up study on the previous paper. The amplification factor of the vibratory stress for bladed disks with free-standing blade structure is studied, using the reduced order model SNM. Comparing the mistuning phenomena of bladed disks of the continuous-ring blade structure and the freestanding blade structure, the reason why the amplification factor of the displacement and the vibratory stress is different is clarified.

For analysis of dynamic characteristics of bladed disk systems, such as jet engines and turbines, the assumption that all the blades are identical and the system is cyclic symmetric is often used (tuned system). However, in a real system, there are small differences in the individual blades’ structural properties that result from manufacturing tolerance. The system becomes nearly periodic structure (mistuned system). In this paper, we propose an approximation method to analyze the random vibration characteristics of the blade system by combining sensitivity analysis and stochastic method. The proposed method makes it possible to investigate the influence of standard deviation of the mistune value on the statistic of frequency responses. We compared the analysis results with Monte Carlo simulation and examined approximation accuracy. By using the proposed method, we also analyze the case where the configuration of mistuned blades is changed and discuss the configurations of mistuned blades with the smallest three-sigma limit.

In the mechanical design of an impeller for an automotive turbo-charger, it is pointed out that the mistuning effect caused by the difference of the casting condition should be considered. Namely, the difference of the casting condition causes the small variation of Young’s modulus of each blade on an impeller. These small variations break the cyclic symmetry, and split the eigenvalue pairs. In the forced response of a mistuned impeller, the responses of all the blades become different, and the response of a certain blade may become extremely large due to splitting of the duplicated eigenvalues and distortion of the vibration modes. In this study, the reduced order model FMM (Fundamental Mistuning Model) is applied to evaluate the resonant response of mistuned impeller. First, the frequency response analysis of mistuned impellers is carried out, using both of the FMM and the direct FEA, and the calculated results are compared to confirm the validity of the FMM. Second, the frequency response analysis of mistuned impellers is carried out using the FMM, the Monte Carlo simulation and the optimal method, to examine the effect of various parameters on the maximum response of a mistuned impeller. In addition, the effect of the intentional mistuning on the reduction of the maximum response is researched in detail using the genetic algorithm.

Turbine blades are being used under increasingly severe conditions in order to increase the thermal efficiency of the gas turbines in which they run. Friction dampers are often used in order to reduce vibration along the blade and increase the plant reliability. Blades using the friction between platforms and dampers have been widely adopted in gas turbines. Characteristics of dynamical response of blades with friction dampers depend on excitation force. It is well known that there are excitation components corresponding to the number of nozzles and of combustors. Theses excitation forces are synchronous for rotation speed. Therefore, blade vibration is often calculated with single harmonic balance method. However, asynchronous components exist actually in excitation force and make it difficult to predict resonant frequency of the blades. In this study, we have developed a new method for predicting the characteristics of nonlinear vibration under excitation force including synchronous and asynchronous components. In order to investigate the effect of asynchronous components, time history response analysis and experiments using a mock-up blade were conducted. Analytical and experimental result showed dampers were slipped easily under the excitation force including synchronous and asynchronous components. Moreover, it is possible to predict the characteristics of vibration accurately by estimating the ratio of overall excitation force to single harmonic excitation force.

Fast steering mirrors (FSMs), which are mounted on observation satellites, are required to have a large aperture and realize tip-tilt-piston and wide-bandwidth operation for the corrections of broader and high-resolution satellite images. A FSM system having a large-diameter mirror which is supported by magnetic suspension and driven by high response voice coil motors in the tip-tilt angular and out-of-plane directions is proposed. The prototype FSM having a dummy mirror with a diameter of 80 mm was designed and fabricated. In the prototype FSM, a bandwidth of more than 1,000 Hz and a driving range of ±1.1° in the tip-tilt angular directions for image correction and a drive range of ±500 μm in the outof-plane direction for focus correction were experimentally achieved.

The cryogenic liquids such as liquid nitrogen or liquid hydrogen are used in various fields, and the necessities of these liquids will increase in near future. However, mechanical bearings are not useful in the cryogenic temperature environment. Therefore we decided to develop a linear motor using superconducting coil for cryogenic liquid transportation, and it is easier to transfer the cryogenic liquid. At first we have made a superconducting linear motor and carried out some experiments.

This paper presents a radial magnetic bearing with a wide air-gap for improving durability and reducing contamination of a centrifugal blood pump with a disposable pump head. The rotor is magnetically suspended by the radial magnetic bearing and driven by an external motor through a permanent magnetic coupling. The pump housing where an impeller-rotor is encapsulated should be as thick as possible in terms of mechanical strength. Hence, an air-gap between surfaces of the rotor and the stator is designed to be wide. The wide air-gap, however, may cause a reduction in suspension force and torque. This paper considers design and control of a radial magnetic bearing that has wide air-gap of 7 mm for a disposable blood pump application.

Mechanical circulatory support (MCS) devices play a significant role in treatment of heart failure patients. Recently, successful use of rotary MCS devices is leading research interest in this technology for pediatric patients. The pediatric MCS devices require achieving compact size, high mechanical durability and better blood biocompatibility. Magnetic levitation system such as magnetic bearings and self-bearing motor is one of candidates to develop next generation MCS devices which can completely suspend a spinning rotor impeller without mechanical contact. In this study, a ultra-compact magnetically levitated motor with 5-degrees of freedom (-DOF) control is undergoing development. The 5-DOF controlled maglev motor is 22 mm in diameter and 33 mm in height. This paper investigated enhancement of magnetic suspension and rotation characteristics in order to develop a higher performance maglev motor for implantable pediatric MCS device. A magnetic circuit of the 5-DOF controlled maglev motor was optimally modified by using theoretical calculation and finite element method 3-D FEM analysis. The improved motor with modified magnetic circuit indicated higher magnetic suspension force and torque characteristics in numerical simulation compare with a the previously developed prototype maglev motor.

A new type of bearingless motor was developed. The feature of this bearingless motor is that it consists only of electromagnets without using a permanent magnet. The power supply to the rotor is performed by a non-contact power supply including a bridge rectifier circuit and a coil. The power receiving part of the non-contact supply is installed at the center of the rotor, and the power transmission part is installed just under the power receiving part. In the levitation method, the rotor coil is attracted to the stator coil, the rotor floats and suspends the rotor. Adjust the stator coil current to control levitation. The rotation method uses the difference between the number of teeth of the stator and the rotor, and controls the rotation by adjusting the current of the stator coil. In previous studies, bearingless motors consisting only of electromagnets were capable of stable levitation, but could not control rotation. This is believed to be caused by the number of turns of the coil wound on the rotor. In this paper, the rotational torque of a new rotor is determined by using electromagnetic field analysis software, design and fabrication are carried out, and the results of the levitation experiment are described.

In this paper, a new model of homopolar-consequent integrated type 5-DOF self-bearing motor is proposed. It possesses the function of a motor, two radial magnetic bearings, and an axial magnetic bearing. The rotor consists of two reluctance type rotors with consequent pole permanent magnets, two homopolar permanent magnets and a circular disc in the center. The homopolar PMs and the consequent pole PMs generate high bias magnetic fluxes. By the additional consequent PMs, airgap bias fluxes are increased. Therefore it is possible to improve the rotation torque of the proposed motor. The radial direction forces can be controlled without any rotating magnetic field information. Furthermore, in the radial control and the axial control, the fluxes don't interfere at simultaneous control. The proposed motor models are analyzed by three dimensional finite element methods. The experimental setup is made and tested. From the results, the proposed homopolar-consequent integrated type 5-DOF self-bearing motor shows high feasibility for bi-ventricular assist device or total artificial heart.

This paper introduces an axial gap self-bearing motor (ASBM) with two permanent magnet attractive type passive magnetic bearings (PMBs). The axial gap self-bearing motor controls the axial position of the rotor and produces motor torque. The PMBs support the radial posture by using the attractive force between the rotor shaft and stator PM. In this structure, there are no additional parts for the PMB to the rotor shaft, then the structure becomes quite simple. This paper describes the structure of the proposed motor, then introduces an experimental device. Levitation and rotation tests were conducted, and stable levitation and non-contact rotation at 300 rpm were succeeded.

This paper presents an attempt towards the improvement of the lecture on vibration engineering using vibration apparatus as effective tools. Although the lecture emphasizes the finding of equations of motion of mechanical systems and the analysis of the solution of them, it is also important for students to predict the motion behavior. In this paper, some vibration apparatus used in the lecture were introduced. The apparatus were used to make students think about what kinds of motions could occur. According to some questionnaires, it is shown that students prefer receiving information through demonstration. It seems that the uses of the apparatus has a positive influence on student learning.

Institute of Technologists (IOT) conduct classes related to CAE from the second year to the fourth year and at the graduate school. Starting with a lecture on fundamental fields in mechanics of materials, practical training using FEM (Finite Element Method), application of CAE by special lecturers inviting enterprise engineers in each specialized field, and recently, topics also attract attention Exercises such as 1DCAE being done are representative. Also, some courses are also planned as certified workshops of the Japan Society of Mechanical Engineers Computational Mechanics Engineer Test.

Conventionally, dynamic analysis of gear system has been analyzed by three-dimensional analysis such as finite element method and multibody dynamics. However, analysis methods have not been established due to problems such as tooth contact calculation and bearing modeling. In addition, complicated analysis of planetary gear devices and like mechanical systems take time and is not a method that can be easily used. Therefore, in this study, an analytical model based on the gear theory modeled by the spring-mass system is developed by using 1DCAE. By using the developed model, it is possible to analyze the vibration of the gearbox in a short calculation time. Since the shape of the gearbox can not be represented by a spring-mass system, dynamic characteristics are modeled by the finite element and degenerated to be captured in 1DCAE. Besides, since the transmission error as the vibration source is caused by tooth deflection, tooth profile error, assembly error, etc., it is difficult to calculate the transmission error in an actual machine by calculation. Hence, in this study, the transmission error is known and handled as input value. By modeling in this method, it becomes possible to calculate the vibration occurring in the gearbox under operating condition at high speed and with higher accuracy. This makes it easy to search for parameters that contribute to lower vibration of the gearbox. Next, an experimental device corresponding to the analysis model is designed and manufactured, and the effectiveness of the developed model is verified by comparing the experiment result with the analysis result. Furthermore, the influence of the gearbox specification on the gearbox vibration is clarified using the developed model.

This paper proposes the estimation method of distance between joints or specific points using inertial sensors. This method consists of the method for posture estimation using sensor fusion and the forward kinematics. This method estimates the posture of the inertial sensors in local coordinate and distance between specific position. We conducted the measurement experiment using the elastic material attaching on the measurement system. The analytical results indicated the posture in local coordinate and distance between the specific points compensating the accumulative error by integration calculation and the error by dynamic acceleration. This system can be used to evaluate the deformation of body segment and the small translational motion.

Women experience specific anatomical and physiological changes during pregnancy. These changes cause postural and movement instability and impose excessive strain on body muscles, such as erector spinae, contributing to low back pain (LBP). Sit-to-stand motion includes stretching and bending of the trunk and can potentially cause LBP. The association between some particular motion in sit-to-stand motion and LBP was investigated in a motion analysis using an inertial measurement unit. However, the role of other motion characteristics, such as muscle load, as risk factors of LBP remains unclear. Hence, the determination of causative factor of LBP in sit-to-stand motion based on assessments of both motion and muscle activation is required for managing LBP during pregnancy. Therefore, the purpose of this study was to investigate the relationship among motion, muscle load, and severity of LBP during pregnancy. For this, motion analysis was first conducted in pregnant women to obtain motion, force, and electromyogram data by using an inertial measurement unit, a Wii balance board, and surface electromyography, respectively. Subsequently, the relationship among motion evaluation indexes, erector spinae muscle activation was calculated from obtained data, and the intensity of LBP during sit-to-stand motion were investigated. A statistically significant positive correlation was observed between the pitch angular velocity of the trunk movement and the erector spinae muscle activation and between the muscle activation and the intensity of LBP during pregnancy.

Along with the aging of the population in recent years, fall accidents due to declining walking ability of the elderly are increasing. In clinical practice such as medical institutions, people with knowledge of medicine such as physiotherapists and doctors often qualitatively evaluate and judge the individual walking abilities from their experiences and tendencies. However, when the number of subjects is large, or when quantitative evaluations such as joint angle and center of gravity are performed, it is difficult in the current system. In this research, we propose a quantitative measurement system using a skeleton model of a depth sensor (Kinect v2). Kinect can estimate the position of a person's joint using depth information. However, due to the measurement range of the skeleton model and constraints on inaccuracy, correction for 3-D analysis is necessary. In this report, we aim to track data of turning without missing while using two Kinects, while interpolating each other points. We use iterative closest point (ICP) algorithm to calibrate the axis of coordinates of two Kinects. We created an algorithm that switches estimation methods according to observation values. In addition, comparison of precision was made by comparing with Vicon which was measured at the same time.

Analysis of spatiotemporal gait parameters is useful as movement function evaluations for the elderly and patients with gait disorders. A laser range sensor (LRS) has been employed as the leg tracking technique for spatiotemporal gait analysis in the clinical sites. However, previous systems had difficulty tracking legs during walking along a circular trajectory, which was often included in clinical tests, because of frequent overlaps and occlusions of legs. Therefore, this paper presents a spatiotemporal gait analysis system that fuses LRS and kinetic insoles. The system tracks leg motions using LRS, considering gait phase detection and change of the noise covariance for Kalman filter, by using the insoles via force sensing. In addition, the system detects foot contact positions using the center of pressure position measured by the insole. In the experiment participants walked along a circular trajectory, the proposed sensor fusion tracked leg motions in longer distance compared with the previous method. In addition, when compared with a motion capture system, the accuracy of the tracked leg trajectories ranged from 30 to 95 mm and the foot contact position was improved by using the insoles. From the results, the proposed sensor fusion was valid as the spatiotemporal gait analysis system.

Although joint torque about internal-external rotation axis at throwing-ball-side shoulder joint shows large values in magnitude prior to ball release during baseball pitching motion, the dynamic contribution of the axial torque shows small value to the generation of ball speed throughout forward swing motion. The purpose of this study was to make clear this phenomenon through quantification of dynamic contributions of shoulder joint torques to the generation of shoulder joint angular motions which would play crucial roles in generating launched ball speed. Ten male collegiate right-handed baseball pitchers were instructed to pitch a ball as fast as possible to the target. Three-dimensional coordinate data of the pitching motion and ground reaction forces of each leg were captured using a 20-camera motion capture system with two force platforms. Dynamics contributions of joint torque, gravity, motion-dependent term(MDT), and modeling error term to the generation of ball speed were quantified using the equation of whole-body motion for the target system. Furthermore, the generating factor of the MDT was considered using a recurrent formula derived from the equation. The results in this study indicate that 1) the internal rotation torque at the shoulder joint induces angular velocity about not only internal rotation axis but also horizontal abduction axis at the shoulder joint, and 2) the dynamic contribution of the internal rotation torque to the generation of ball speed would become small values because the ball speeds generated via these two angular velocities cancel with each other.

This research formulates a mathematical model that simulates human arm's reaching movements for capturing a uniformly and linearly moving object, and examines the model's effectiveness. Actually, the research measures and analyzes moving-object capturing movements, and then models the human arm's moving-object capturing mechanism as a feedforward control model composed of three links (upper arm, forearm, hand) and three joints (shoulder, elbow, and hand joints) based on a moving-object capturing strategy: the strategy is to optimally predict the capturing point where the human arm's reaching movement duration becomes equal to the object's uniform and linear movement duration. Consequently, the following results are obtained: (1) the measured capturing movements imply the existence of the human learning mechanism of object's motion characteristics and the human arm's feedforward control mechanism; (2) the proposed model can capture the uniformly and linearly moving object; (3) the proposed model can optimize the reaching movement duration to the moving object; (4) the proposed model can basically reproduce the measured capturing trajectories accurately, although it predicts trajectories different from the measured ones as for some measured capturing movements. These results suggest that the proposed feedforward control model can be a more generalized model of the human arm control mechanism as well as an effective model of the human arm's moving-object capturing mechanism.

A flexible string is used at various situations. Especially, there are some products which serves as a purpose by letting them work. Thus, it is necessary to analyze their behavior. In the past studies, dynamic behavior was analyzed when playing fly-fishing. However, the axial elongation is not considered. In fact, the axial elongation affects their behavior such as axial micro vibration or restoring force of the elongation. Therefore, it is necessary to consider the axial elongation to grasp the behavior of the string more exactly. In this study, an accelerated motion of the string such as the casting motion is focused on and analyzed in consideration the axial elongation then appropriateness of the modeling is verified by comparing experimental results and analysis results. Furthermore, relations of the axial elongation and an accelerated motion are investigated. In this report, the behavior is investigated focusing on the speed of the tip of the string. As a result, strain energy is stored and then converted into kinetic energy, thereby increasing the velocity.

Standing balance evaluation of human enables us to predict the risk of falling due to aging and to clarify the effect of balance improvement training. The evaluation needs human posture and joint torques with external stimulus. In general, posture is measured by a motion capture system (MC) or inertia measurement units (IMU). To estimate the joint torques, it is necessary to add force plates to these sensing devices. However, MC and IMU are not practical from the view point of installation and precision. To solve the problem, this study tries to estimate posture on saggital plane and joint torques from only a force plate during standing on a shaking table. For the estimation, we regard human body as two-links (upper body and lower body) model and propose a method composed of three processes. In the first process, we regard the subject as a single link model and estimate its posture. In the second process, accelerations of upper body and lower body are estimated by using posture of the single link model. In the last process, posture of two links is calculated by integration of the accelerations estimated in the second process. This method utilizes Kalman filter in the calculation of all processes. The validity of the present method was verified by posture estimation in floor sway test.

Laser range sensor-based timed up and go (laser-TUG) can evaluate performance in TUG subtasks (sit-to-walk [STW], walking short distance, and turning). This study characterized knee osteoarthritis (OA) patients’ (n = 165 patients; mean age, 68.6 [50–85] years; mean body mass index: 22.8 kg/m2, 70.3% female) laser-TUG subtask performance. Slowed STW time was clinical hallmarks associated with knee OA with severe knee pain. Furthermore, we performed mediation analysis and found that severe knee pain was acting on slowed STW time at least through lower sit-to-stand function. These functional constructs would not be fully captured by total timed score of existing functional measure; therefore, laser-TUG enables us to firstly clarify OA-related functional impairment. Close attention for these tasks might be a key to follow functional decline in knee OA patients who aggravate knee pain.

Along with the aging society in recent years, research and development of devices supporting the actions of elderly people and workers are being conducted. As one of these devices, we develop wire type assist suit that provides assistive torques to the wearer at the hip during walking. A key feature of our assist suit is that it has the cross-wires along the thighs. Conventionally, energy metabolism kinetics by exhalation gas measurement has been used as a method of evaluating assistance effect of the assist suit. This evaluation method, however, can evaluate changes in the metabolism of whole exercise, it is not possible to evaluate the degree of assistance the assist suit performs for each joint. In this research, we analyzed the lower joint angles, step length and the torque given by the assist suit to hip joint with the use of human body simulation software. As a result, it was found that hip joint angle has a greater correlation with the stride compared to knee joint angle and a certain assist effect was observed in the hip joint extension section. It can be expected that increasing the step length applies to rehabilitation and reducing burden on hip joint applies to assist during walking.

Currently, manned space exploration is being promoted actively internationally. In this context, an optimal walking motion control technique in microgravity environment is required. More precisely, it is necessary to clarify the kinematic changes of locomotion under microgravity. On an anti-gravity treadmill using pneumatic pressure, subjects can walk quickly with a relatively light load and a weight bearing condition up to 20% of body weight. Thus, it is considered to be a useful method to compensate for the drawbacks of conventional partial weight bearing methods. However, during walking on the anti-gravity treadmill, ground reaction forces and joint angles cannot be measured by a large force plate and an optical measurement system. Therefore, during this research, a walking simulation in a microgravity environment was realized by using an anti-gravity treadmill, and the walking motion was measured with a wearable motion measurement device. The conditions of the anti-gravity treadmill were set to five conditions of weight rates of 100 %, 80 %, 60 %, 40 % and 20 %. The evolution of ground reaction forces and joint angles during one gait cycle were calculated from each sensor's output, and the influence of partial weight bearing on the gait was examined by comparing the calculated values. As a result, from the changes observed in ground reactions forces and joint angles, it was found out that the gait becomes floating and gets closer to a slow tiptoe walking style as the weight rate is small with the anti-gravity treadmill. Furthermore, from the changes in joint angles, it was found out that the walking behavior characteristics of the lower body greatly change between the weight rate of 40% and 60%.

Falling is a common problem in the growing elderly population and fall-risk assessment systems are needed for community-based fall prevention programs. In particular, the timed up and go test (TUG) is the clinical test most often used to evaluate elderly individual 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. This paper presents a gait measurement system using a laser range sensor (LRS) (Laser-TUG system) for evaluating functional mobility in the TUG. The system tracks both legs and measures the foot contact positions to obtain walking parameters. However, both legs might be close to each other and one leg might be hidden from the sensor. This is especially the case during the turning motion in the TUG, where the time that a leg is hidden from the LRS is longer than that during straight walking and the moving direction rapidly changes. These situations are likely to lead to false tracking and deteriorate the measurement accuracy of the leg positions. To solve these problems, a novel data association method considering gait phase and body direction is proposed. We verify the proposed method for TUG tests with elderly people.

As aged society progressing, these days, the number of elder people who need supports their daily lives are increasing. On the other hand, there aren’t enough number of physical therapists (PT) for the people who need especially a light care. It is reported that approximately 30~40% of the people need TP in their life. To solve this kind of problem, our study group has studied a high performance shoes with IoT technology for improvement of rehabilitation efficiency. The high performance shoes include Sponge Core Silicon Rubber Actuators (SCSRAs) in their insoles. As SCSRAs consists with sponge covered with some sorts of silicon, SCSRA can be used not only for actuators but also pressure sensors. When we use SCSRAs as actuators, we should apply air into them with diaphragm pump. Air make them intumesce so that they can give touching signal to a part of the sole. Otherwise, when we use them as pressure sensors, we measure internal pressure and multiply it by surface area to estimate the external force. In this study we researched and estimated the best composition of silicon for SCSRA as an insole in the term of time responsibility for load to them. Also, since the high performance shoes are heavier than other ordinary shoes, we researched allowable mass of the shoes that the patient could walk smoothly with shoes. We compare the variance to x-axis of the gravity point while they are walking.

The aim of this study is to clarify the effects of the rehabilitation for finger range of motion, strength, and resistance as grade of contracture using power assist-hand in patients with hemiplegia after stroke. Four patients (45-65 yr., two males and two females) with hemiplegia were involved in this study. The range of motion, grasping force, and resistance as the grade of contracture were measured every two or three months. Each patient was installed power assist-hand by themselves, and they performed rehabilitation in their house, fifteen to thirty minute, three times per week, for six months at least. The finger range of motion was not so improved in each patients, but resistance of finger were reduced, and voluntary grasping force was a little increased after six month. These results suggested that rehabilitation using power assist-hand would be helpful for finger contracture in patients with hemiplegia.

Operation sounds for machine products have been designed to transmit or caution correct information to users. The user operation for the machine product has changed from a button operation to a touch or gesture operation according to the evolution of information devices. However, the operation sound for the machine product has not been changing since the button operation has kept a main stream. The purpose of this study is to evaluate for combination between the gesture operation and the operation sound for new information devices. It is clarified that the relationship between the gesture operation and the operation sound by carrying out evaluation experiments using seven types of typical gesture operation and the different dimensional sounds, which are an ON/OFF temporal pattern sound, a pitch variation sound, and a movement of sound image. It is experimentally verified that the pitch variation sound and the movement of sound image are important factors for the gesture operation of the machine product.

The sensory evaluation for the easiness of grasping by young college student and that by senior people were studied. It was appeared that the senior citizen becomes difficult to evaluate rationally compared with young people. This tendency was conspicuous in particular in the evaluations by 2-steps, 5-steps and 7-steps.The senior person needed longer evaluation time, i.e., 120%~150% of that by young people, especially in the evaluations by 3-steps, 5-steps and 7-steps, i.e., odd steps. This result shows that the elderly is difficult to make an ambiguous evaluation such as neither, so that in case of elderly person, the evaluation with the scale of 2-stepsor odd-steps is to be avoided. Optimum diameters evaluated by elderlies were smaller than that by young persons about 5mm.

Human iPS cells were established in 2007, and researches on regenerative medicine using the cells have been conducted around the world. In 2018, clinical studies are planned for transplanting myocardial sheets prepared from iPS cells to heart failure patients. First, it is important to create 3-D structures from iPS cells. There are many tasks. For example, it takes a huge cost to cultivate cells, and it takes a long time to differentiate iPS cells into target cells. On the other hand, cells in the body are subjected to various mechanical stimulation in vivo, and these are thought to affect cell growth. In this study, we cultured the cells in the 3-D gel embedded culture in the differentiation process from iPS cells to neurons, and applied dynamic stimulations. We examined the effects of the differentiation and growth of cells, directionality and extension rate of neurites. To apply dynamic stimulation, we used a vibration stage. Vibration conditions are set us the frequency: 1, 5, 10, 15, 20Hz, the amplitude: 60μm, and the incubation time: 48hours, horizontal direction. As a result, it was suggested that when neurons are applied dynamic stimulation, in all frequency range differentiation and growth rate exceeds static culture. Especially, 10 Hz stimulation case indicated the highest increase rate against the static and significant differences were observed. Regarding to the directionality of the neurites, when neuron is applied dynamic stimulation, there was a tendency to extend in the direction perpendicular to the vibration direction. Regarding to the extensibility of the neurites, there was a tendency to decrease in proportion to frequency increase of the dynamic stimulation.

In this study, the simulated simple transplantation system of the neurons differentiated form of mouse iPS (induced pluripotent stem) cells is investigated. Mouse iPS cells are differentiated into neurons by SFEBq method. Two colonies of neuronal cells are prepared, one is the recipient cells and the other is donor cells. At first, suspension culture of recipient cell is started. Then, in 5 days, suspension culture of donor cell is started with recipient cell shifted to adhesion culture. In 10 days, transplantation of donor cell is conducted next to recipient cell. Neuron networks between the recipient cells and the donor cells are jointed for 5 days of culturing. Then, the dynamic stimulation is applied using the 3-D vibration stage to the neuronal networks to promote formation and merging. The total stimulation time is set as 96 hours, that is the vibratory stimulations are applied to the transplantation system during 4 days from one day after transplantation. As a result, it is suggested that the neuron networks are constructed actively with the dynamic stimulation.

The brain is exposed to light, magnetic field, chemical stimulation, and mechanical stimulation. These stimulations affect neurons constituting the brain. Neurons are known as their stretching axons and the information transmission in the brain is conducted by them. Action potentials generated by the information transmission are measured as brain waves and are used to study brain activity. They are classified according to their frequency range and the frequency range from 26 to 80 Hz is called the gamma wave region. The gamma wave are regarded as coordinating the activity between the nerves. Recently, it had been reported that the visual stimulation of light (60W, 40 Hz) excites the gamma wave region in the brain and that mechanical vibration promotes the proliferation and the differentiation of neural stem cells. We thought there are relationship between vibration in the gamma wave region and neurite outgrowth. Our goal is to verify the effect of mechanical vibration in the gamma wave region on neurite outgrowth. In this study, we used PC-12 which are also used to study signal transduction, differentiation, survival and proliferation mechanisms as they respond to many growth factors. We gave vertical sinusoidal to PC-12 and obtained that mechanical vibrations at 12.5 Hz (outside the gamma region) and 25 Hz (gamma region boundary) significantly enhanced neurite outgrowth compared to the non-vibration group but at 40, 50 Hz (gamma wave region), 100 Hz (outside the gamma wave region) significantly suppressed. We conclude that mechanical vibration in the gamma wave region may suppress neurite outgrowth.

The previous study showed that the mechanical vibrations at 12.5 Hz and 50 Hz promote cell proliferation and differentiation, respectively. If the response of cells to mechanical vibration is linear, the superposed mechanical vibration at 12.5 Hz and 50 Hz would activate both of them. However, we do not fully understand cell systems. It is necessary to conduct experiments to investigate the effects of the superposed vibration. Therefore, the objective of this study is to investigate the effects of superposed mechanical vibration on cell proliferation and differentiation experimentally. Osteoblast-like cells were culture for the non-vibration groups and the vibration groups. The vibration groups were cultured under the vertical superposed vibration for 24h/day. The vibration was made by a shaker which was operated by a signal from a function generator. The vibration consisted of the 12.5 Hz and 0.5 G sine wave and the 50 Hz and 0.5 G sine wave. The number of cells, the area of mineralization, and the ALP gene expression level were obtained by cell counting with a hemocytometer, alizarin red staining, and real time RT-PCR, respectively. As a result, there was no significant difference in the ALP gene expression level, but the maximum value of cell density was 2.8 times larger and the mineralization appeared earlier in the vibration groups. From the above, the superposed vibration has effects of the cell proliferation and there is possibility of the effects of the vibration on cell differentiation.

The effect of long term medium flow on bone cell proliferation was investigated experimentally. Mechanical stimulation is known to increase bone density and strength in our bodies due to the responses of cells inside bones. It is reported that cultured bone cell density is increased by mechanical vibration and its effect is dependent on the frequency. However, how cells respond to mechanical vibration is still unknown. A variety of chemical or physical phenomena should be induced by mechanical vibration. In order to understand the mechanism, we need to find out which of the phenomena largely affects cell proliferation. Previous experiment by our group has indicated that medium sloshing, one of the frequency dependent phenomena, affects bone cell proliferation. In this paper, in order to understand how the sloshing affects cell proliferation, we focused on one of the sloshing-induced phenomena, medium flow. Bone cells were cultured under medium flow which is generated by micro-pumps. Time over change of the cell density was measured and compared with that of controls and vibrations. The obtained result indicates that bone cell proliferation is increased by medium flow and its effect is about a half of that of mechanical vibration.

Diseases occurring near the vocal cords, such as laryngeal cancer, share the initial symptom of hoarseness of voice. The GRBAS (grade, roughness, breathiness, asthenia, strain) scale is used as an acoustic diagnostic method for these diseases, but its objectivity is not well established. Instead, more accurate diagnosis may be possible by capturing the waveform of the flow velocity at the vocal cords. The aim of this study is to enable voice disturbances to be diagnosed by identifying the sound-source waveform from voice measurements. For acoustic analysis of the vocal tract, we modeled the air inside it as concentrated masses connected by linear springs and dampers. We identified the shape of the vocal tract by making the natural frequencies of the analytical model correspond to the measured formant frequencies, and we calculated the sound-source waveform from the measured voice waveform. The validity of the proposed method was confirmed by numerical simulation and an experimental device that simulates the human voice mechanism and comprises an acrylic vocal tract and a piston. We confirmed that the identified sound sources are similar to measured sound sources. We therefore conclude that our proposed methods are valid.

These days, the number of traffic accidents due to drivers' sudden diseases is increasing. Therefore, it is desired to detect sudden diseases by making use of drivers' biological signals measured while driving. To detect such diseases, we need to know how biological signals change with the disorders. However, it is difficult to measure physiological signals at sudden diseases and propose the method for detecting such conditions. In this study, we construct a cardiovascular model which can reproduce mechanism of a cardiovascular system, and calculate biological signals by assuming sudden diseases in the model. In the cardiovascular model, stroke volume, the blood volume pumped by a heart per beat, is determined based on the operating conditions of the system. Besides, we considered positions of baroreceptors and pressure sensors of a cardiac system in blood vessels. Then, we succeed to construct detection method for sudden diseases based on the calculated biological signals. We use K-nearest method and LOF method for a detection algorithm and found that combination of systolic blood pressure and heartbeat interval is adequate for detection, and LOF method is useful for the discrimination of disease.

EEG (Electroencephalogram) which is influenced by various factors such as thought and mental state has very high-order information. However, it is difficult to handle this since the time series waveform of EEG is complicated. Therefore, an analysis method such as mathematically modeling the behavior of the time series waveform and experimentally identifying model parameters is a possible approach. The aim of this study is to exam the optimal model structure for EEG analysis, we compared three different types of equations. Two of them are nonlinear equations, and the other is a linear equation. we considered which model is a suitable for complex EEG signals.

In this study, we examined the suppression effect of brain cooling on the epileptic focus and surrounding area. An epileptic seizure was induced in rats to obtain electrocorticography (ECoG) data when brain cooling was performed on the epileptic focus and its surroundings. Then, the frequency response characteristic was calculated by applying fast Fourier transform (FFT) and band pass filter to the obtained multichannel brain wave data. As a result of comparing the calculated frequency responses for each rat, it was found that at the site where epileptic seizures were observed, power was reduced by cooling and suppressing effect was observed, whereas at the same time, the power increased at the site a few millimeters adjacent to the seizure site was confirmed. This result suggests that epileptic waves suppressed by brain cooling might propagate to the surrounding area by a few millimeters.

In this study, the influence of the direction of the excitation force on the vibration of the cornea is studied by measuring the corneal vibration by changing the installation position of the vibration source of the cornea excitation type tonometer. A cornea excitation type tonometer has been proposed in order to reduce the stress given to a subject. It is a characteristic of this tonometer that the cornea is excited at a frequency below the audible range without contact and the intraocular pressure is estimated from the low-frequency component of the vibration. A point concentration type parametric speaker in which ultrasonic elements are arranged in a curved manner is used as a vibration source, and lowfrequency excitation force is obtained by modulating the carrier wave with a frequency below the audible range. In the results of the previous study, there were some time history response results that the cornea oscillated to pulsate and did not become a steady state. This problem seems to be occurring because the vibration source is installed diagonally with respect to the cornea. Therefore, in this study, we first improved the experimental equipment so that the vibration source and the displacement meter can be placed in front of the cornea. This was realized by performing displacement measurement by OCT. Next, an excitation experiment was carried out when the vibration source was placed in front of the cornea and when the vibration source was arranged diagonally. Experimental results reveal that adequate vibrations cannot be obtained when the vibration source is installed obliquely to the cornea, but good vibration can be obtained when the vibration source is placed in front of the cornea. The results of this study are expected to be useful for improving the accuracy of intraocular pressure estimation of the cornea excitation type tonometer.

When co-culturing cells outside the body, it is necessary to culture in an environment closer to the living body. In this study, we tried to manufacture a culture vessel and generate three-dimensional tissue of cells by acoustic radiation pressure and Ekman transport. As a result of experiments with particles simulating cells, the particles remained outside the culture surface in the case of only using acoustic radiation pressure. However, by combining Ekman transport and acoustic radiation pressure, particles could be aggregated efficiently. Therefore, three-dimensional tissue of cells can be generated using these techniques.