Person has spent most of the day in a sitting posture. In recent years, there has been a growing attention to the "seating comfort" researches. However, research topics are complicated and vary widely, it is difficult for a designer to use accurately design knowledge during the development of chairs. Therefore, in this study, "seating comfort" researches based on the literatures were systematically analyzed by the elements extracted and classified into spaces of element inter-relationship diagram using Multispace design model. Extracted elements were classified and discussed about change based on timeaxis. And, also the literatures categorized using cluster analysis of the extracted elements. From consideration based on the analysis results, researches about the human mechanism of seating comfort and long-term sitting analysis including the postural change have been proposed as non-research areas for future knowledge expansion.
This paper presents a laser-based tracking (estimation of pose and size) of moving objects using multiple mobile robots in Global-navigation-satellite-system (GNSS)-denied environments. Each robot is equipped with a multilayer laser scanner and detects moving objects, such as people, cars, and bicycles, in its own laser-scanned images by applying an occupancy-grid-based method. It then sends measurement information related to the moving objects to a central server. The central server estimates the objects’ poses (positions and velocities) and sizes from the measurement information using Bayesian filter. In this cooperative-tracking method, the nearby robots always share their tracking information, allowing tracking of invisible or partially visible objects. To perform a reliable cooperative tracking, robots have to correctly identify their relative pose. To do so in GNSS-denied environments, the relative pose is estimated by scan matching using laser measurements captured by both sensor nodes. Such cooperative scan matching is performed by 4-points-congruent-sets (4PCS)-matching-based coarse registration and Iterative-closest-point (ICP)-based fine registration methods. The experimental results of tracking a car, a motorcycle, and a pedestrian with two robots in an outdoor GNSS-denied environment validate the proposed method.
Response spectrum analysis method is widely used for the seismic design of equipment and piping systems of nuclear power plant, or other industrial facilities. Some of the equipment and piping systems are multiply supported with plural floors, or several different points. In these cases, conservative design methods, such as uniform response spectrum (URS) method that envelopes all of the individual response spectra, or independent support motion (ISM) method are commonly accepted. These design methods are not practical, but often mislead to design with unnecessary conservatism. This paper presents the practical seismic analysis methodologies considering the correlation coefficients of seismic responses with multi-directional excitations, which is extended to apply the correlations between modal responses and between support motions, called cross-oscillator, cross-floor response spectrum by Asfura, A. and Kiureghian, A,D., and numerical examples are also presented to examine the validity for the seismic analysis method of multiply supported secondary systems, with simultaneous three directional excitations of each X, Y, Z axis.
In this paper author proposed a unique vibration suppression device that has variable inertia mass using continuously variable transmission (CVT) in order to obtain vibration isolation when a harmonic frequency was coincided with an anti-resonance frequency of 1DOF system. The device complies a ball screw mechanism, a flywheel, servo motors and CVT. The CVT is composed of toroidal wheels and power transmission wheels. The device has a small inertia force when an attitude angle of the power transmission is low by the servo motor as depending on a contact radius between two half toroidal wheels, on the other hand the large inertia force under high angle, so variable inertia force which acts as series inertia mass can be controlled continuously. The trial device was manufactured and the resisting force characteristics were measured. Theory of the variable inertia force was introduced, and compared with the experimental results. In order to confirm vibration control, an optimized inertia mass which always adjusts to anti-resonance frequency was determined in case of 1DOF system with the device, frequency response tests were carried out by using a shaking table, and experimental results were compared with calculated ones. Finally, the theory of resisting force and effects of vibration suppression were confirmed.
Dynamic FEM analysis is valid for designing rotating machinery to reduce its vibration problem when we may ensure enough accuracy of the analysis. Surrogate multiple objective optimization method is one of the most effective methods for structural identification improving the FEM analysis model of a structure to adjust the natural frequency analysis results to the experimental results. In this study the structural identification method is applied to stator end-windings of a turbine generator to determine the Young's modulus of the principal components on the FE model minimizing the analysis errors of the natural frequencies of the 2-lobe and 4-lobe circular modes to the corresponding experimental results. The accurate FE model of the end-windings is obtained by this method.
With recent globalization in industries, the number of failures and troubles of products caused by using them in unexpected ways has increased. In order to avoid such troubles, it is necessary not only to assume various ways of use thoroughly, but also to verify whether the design plan can fulfill required functions when the product is utilized in those ways. From this point of view, the authors proposed a functional verification method considering ways of use based on qualitative modeling of behavior of entities and cause-and-effect relationships among physical phenomena using Petri nets. It is, however, impossible to detect failures concerning to specification which requires dealing with quantitative information. This paper provides a method for quantitative modeling of behavior of entities and cause-and-effect relationships among physical phenomena. Two types of tokens were defined for dealing with positive and negative values and four types of arcs were for controlling changes of those values. These new elements of Petri net made it possible to represent behavior of entities and cause-and-effect relationships quantitatively. Application of this new modeling method to the functional detection method enables automatic detection of failures concerning to both functions and specification. The detection method using this modeling method was applied to an example, and its effectiveness was proven.
This paper proposes an interactive image-based re-modeling system for virtual reshaping of real objects via a video see-through display. The system provides a quasi-realistic design environment in which a designer manipulates the shape and location of real products installed in a real living space. A prototype of the proposed system is developed by integrating two sub-systems for solid modeling based on 3D-CAD and visualization based on image-based rendering. A case study of the virtual redesign of real products illustrates that the proposed system allows designers to examine various design changes on the existing products in an immersive and realistic 3D environment.
Generation of new concepts in product design process serves as driving force of innovation. While many methods have been proposed for supporting design concept generation, it has rarely been supported in a systematic way, because its process is done in designer's implicit thought, and therefore, it is difficult to explicitly formalize the process. This paper proposes a model of designers' thinking process in concept generation called ECF cycle. It consists of three steps, i.e., (1) Externalization: the step for representing design concepts with drawings and language, (2) Classification: the step for classifying concepts with function trees, and (3) Finding voids: the step for finding potentials of new concepts called void, which is a defect of the classification. Then, this research builds a new method of concept generation incorporating the theory of solving inventive problems (TRIZ). The method is based on a quick reference table of TRIZ principles, which helps designers to create a new concept corresponding to a void found by ECF cycle. A case study of concept generation of new running shoes is demonstrated in order to verify the ability of the proposed method.
We propose image processing method for road white-line detection using brightness gradient direction of edges. Many methods for white-line detection have been proposed for standardized roads. These methods use model fitting for the detection of edges on white-line contour. So it is difficult to apply these methods to non-standardized roads for which modeling is difficult. To expand the scope of white-line detection to common roads in the future, it is necessary to achieve processing without models. Clustering based on position proximity of edges is one approach. However, there is concern about degrading noise reduction that has so far been done by model fitting. In this study, we developed an edge clustering method that utilizes the characteristics of edges on white-line contours; proximity of position as well as proximity of brightness gradient direction. In the proposed method, edges are first clustered based on proximity of gradient direction. And for each cluster, edges are again clustered based on proximity of position. Edge filter bank is specially designed for the first clustering and the effectiveness compared to conventional filter bank is explained. By applying the method to the images taken by on-board camera, we demonstrate that white-line detection that can apply to diverse road environments but is hardly affected by noise can be realized.
This paper deals with the vibration quenching problem of the one-degree-of-freedom system with a limited power supply. This system is forced by centrifugal force of rotating unbalance, and the system is quenched using a Hula-Hoop and a motor to assist the rotation of Hula-Hoop. The entrainment region, the amount of vibration quenching, and the energy consumptions of the system are studied from the approximate analysis using the averaging method, the numerical integration analysis, and the experiment. Following was made clear: (1) When the unbalance is large, the entrainment region of the voltage of the assistant motor is large. On the other hand, when the unbalance is small, the entrainment region becomes narrow. (2) When the unbalance is large, by setting the voltage of the assist motor to a value smaller than the optimum value for vibration control, within the range that satisfies the allowable vibration amplitude level, the increase amount of the energy consumption becomes low. (3) The approximate solutions obtained by the averaging method are in good agreement with those obtained by the numerical integration method, and the characteristics of these results coincide with those of the results obtained by experiment.
Pneumatic anti-vibration apparatus (AVA) has been used for suppressing the vibration from the floor. Compressed air produced by the air compressor is supplied to air spring, which is used as an actuator in AVA. This paper considers the suppression of flow disturbance, which is caused by pressure variation of compressed air. Based on the internal model principle, the suppression of vibration of AVA due to flow disturbance has been confirmed by using Central Pattern Generator (CPG) in parallel with a displacement controller. In biological study, CPG in bodies playing a significant role in the walking have been learned. Moreover, mathematical models of CPG have been reported, and some researchers have been studying about walking of biped-robots by using CPG to generate desired value. On the other hand, this paper proposes asymmetric CPG as new model for further vibration suppression, compared with the symmetric CPG which is the conventional model. This new model introduces asymmetry by changing its parameters into different values in order to improve reproducibility of waveform which shows the variation of supplied air pressure. Validity of the proposed model is presented by experimental result of AVA. The effectiveness is shown by analyzing and comparing the results of experiment and simulation of symmetric and asymmetric CPGs.
The product design project includes many uncertainties. It causes risk that a project target cannot be accompolished within lead time. In order to flexibly handle the uncertainty and avoid the risk, adaptive planning that can switch easily to another plan by preparing options for a task is needed. When a challenging design alternative is difficult to be accompolished, a project manager should decide either to continue the design taking a risk or to switch to a conservative alternative disliking a risk. This paper proposes a new optimization-based project planning method that aims at a Pareto-optimal of the potential technical performane of designed product and a project failure risk. A task option model is employed for risk assesment of option-based project management. As its planning includes a number of various design variables and various evaluation indices, in order to solve such a complicated problem with a reasonable computation cost, this research separates the optimization problem into two phases, i.e., (i) defining of process architecture and organization structure and (ii) scheduling of resource allocation into activities. This paper demonstrates its application to a student formula design project. A proposed optimization method facilitates a project manager to explore various process plans with assessing their risks.
This paper addresses a novel lightweight and low starting torque bearing with looped carbon fiber brush (LCFB). LCFB simulates bristle of living being. Moreover, the static friction coefficient is nearly equal to the kinetic friction coefficient. By applying LCFB to a slide bearings, where a shaft is supported by multiple LCFBs, it is realized low starting torque bearings as well as lightness compared to conventional ball bearings. In this paper, we manufacture prototype LCFB slide bearings. With the bearings, we compare friction torque between LCFB slide bearings, slide bearings and deep groove ball bearings. As results, the ratio of starting torque to regular torque of LCFB slide bearing is from 0.93 to 1.07 which is smaller than that of the slide bearing. When micro-spline shaft is used as a mating material of LCFB slide bearing, the torque reduces because of decrease of real contact area between LCFB and mating materials. In addition, since LCFB utilize elastic deformation of fibers, LCFB slide bearings are not endurable in heavy radial load as high as load rating of ball bearing. Therefore, we define the load capacity of LCFB slide bearing from buckling load of a carbon fiber bundle to avoid overload state. We propose the load capacity as a design guideline of LCFB slide bearings.
It is known that the cutting force excites the structural vibration of machine tool. In addition, cutting force acts on feed and spindle drive system as a force disturbance, and feed speed and spindle speed are changed. As the results, cutting force is also changed because the depth of cut and cutting speed are changed due to the machine vibration, feed and spindle speed changes. The purpose of this study is to analyze the coupled vibration between the machine tool behavior and the cutting force. In order to achieve the purpose, in this study, a coupled simulation method of the vibration of machine tool, the dynamic behaviors of feed and spindle drive systems and the cutting force is developed. Cutting force and machined surface geometry is simulated using the voxel simulator in which the workpieces is represented by voxels. Undeformed chip thickness can be calculated based on the relative position between the tool and workpieces, and the tool rotational angle at the each time step based on the voxel model. The cutting force is estimated based on the calculated undeformed chip thickness. The relative position between tool and workpiece at each time step is simulated by the feed drive system and machine tool structural models. The tool rotational angle is simulated by the spindle drive system model. The coupled simulation between the cutting force, structural vibration of machine tool and feed and spindle drive systems is carried out by applying the simulated cutting force and cutting torque as a disturbance to the feed and spindle drive systems and machine tool structure. Cutting tests and simulations are carried out with two kinds of radial depth of cut, 5 mm and 20 mm. It is confirmed that the machine tool dynamic behaviors due to the cutting force and torque which is also influenced by the machine tool behaviors can be simulated by the proposed method. It is also confirmed that the chatter vibration which is observed in case of the 20 mm depth of cut can be simulated by the proposed method.
Navigation systems are nowadays widely used for cars though it is yet to be able to say popularized for motorcycles. While motorcycle navigation systems are not popularized yet, previous research indicates motorcyclist's high demand against a useful navigation system. The absence of useful motorcycle navigation system is an issue of current products not capable of providing navigation information efficiently. To work with the issue, information presentation design is necessary to consider the motorcyclist's characterful viewpoint movement of looking at the road surface carefully in a vertical movement. As a solution to this issue, we propose the use of head-up display for information presentation. Previous studies have revealed the amount and positions suitable to present information for motorcyclist while riding, although the timing of information presentation is yet to be discussed. Thus, in this paper, the information presentation timing to provide navigation information has been evaluated. Experiment using an immersive CAVE motorcycle simulator was conducted with the configuration of five timings between 25 m to 85 m prior to the intersection under conditions of urban street with 30 km/h speed limit. Durations of motorcyclist's viewpoint movement and five scale subjective ratings were used for evaluation. The experimental results from 10 subjects showed a statistically significant difference in subjective ratings. In conclusion, suitable information presentation timing of riding in urban streets with 30 km/h speed limit is around 40 m to 55 m prior to the target intersection.
A fluid temperature measurement technique based on fluorescence polarization is developed and applied to measure the two-dimensional temperature distributions in microchannel. In this measurement method, the fluorescence depolarization due to rotational Brownian motion of the fluorescent molecules in the solution is measured and converted to fluid temperature. Since the fluorescence polarization degree is independent to fluorescence intensity, the measurement is less influenced by the fluorescence quenching effect, which is an issue in laser-induced fluorescence (LIF) method. Experiments were performed using a microchannel with fluorescent molecules solved in water. The effects of the fluorescent molecule concentration, fluid pH and fluid temperature on the fluorescence polarization degree are discussed to evaluate the influence of the quenching effects and to derive the correlation curves. Furthermore, the proposed method was applied to measure the temperature distribution with linear gradient generated in the microchannel. The results showed that the fluorescence polarization is considerably less sensitive to quenching factors compared with the fluorescence intensity measurements. A linear correlation between the polarization degree and the fluid temperature was obtained. This relationship agreed well with the theoretical one. Further, measurement of two-dimensional temperature distribution in the microchannel agreed well with the values obtained by the thermocouple measurements. These results confirmed the validity of the measurements and feasibility of the proposed method.
Considering in design by analysis, four types of tests, slow-strain-rate tensile (SSRT), fatigue life, fatigue crack-growth (FCG), and elasto-plastic fracture toughness (JIC) tests, were conducted with low-alloy steels, JIS-SCM435 and JIS-SNCM439, in 115 MPa hydrogen gas and air at room temperature (RT). In addition to above tests at RT, the SSRT tests were also conducted in 115 MPa hydrogen gas and air at 120 oC and in 106 MPa hydrogen gas and 0.1 MPa nitrogen gas at -45 oC. The low-alloy steels used in this study had tensile strengths (σB) ranging from 824 to 1201 MPa with fine and coarse tempered-martensitic microstructures. In the SSRT and fatigue life tests, the tensile strength and fatigue limit were not degraded in hydrogen gas. The FCG tests revealed that the FCG rate (da/dN) was accelerated in hydrogen gas; however, there existed an upper bound of the FCG acceleration, showing the FCG rate in hydrogen gas was about 30 times larger than that in air, when σB was lower than 900 MPa. The JIC tests demonstrated that the fracture toughness (KIC) in air was 207 MPa·m1/2 at σB = 900 MPa, whereas the hydrogen-induced crack-growth threshold (KI,H) was 57 MPa·m1/2 at σB = 900 MPa. Based on these results, we proposed advanced guidelines on the use and design for SCM435 and SNCM439 on design by analysis in 115 MPa hydrogen gas, which enable to design the storage cylinders used in 70 MPa hydrogen station with lower cost without compromising safety.
In resent year, the demand for the autonomous mobile robots which can navigate indoor environment, such as office room, warehouse, hospital has increased. Autonomous mobile robot needs some information to navigate various environment. Self position is one of the important information since the robots need to determine its any behaviors such as path planning. Unfortunately this information is including some critical error such as odometry error which is caused by wheel slipping and uncertainty of its model parameters. Scan match is one of the method to overcome this problem. By determining two point cloud data measured by sensor (such as LIDAR) mounted on robot at different measurement point, it can estimate such errors. And furthermore, scan match is used to improve the proposal distribution of Rao-Blackwelized Particle filter using grid map. However, the computational cost of scan match is higher because searching nearest neighbor need a large amount of computational resources. To overcome this problem, we propose high efficient scan match method, using likelihood field map and hill-climb approach. And then we also propose efficient likelihood mapping method concurrently. In our experiments, efficiency of our scan match method was higher than two conventional method, ICP and correlative matching. And it verified that our likelihood field mapping method efficiency has been improved.
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. Measuring experiments of forces a caregiver apply to a wheelchair in a step-climbing action is conducted using the developed step-climbing casters. The result of the analysis and the experiment indicate 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.
Because of their superior mechanical, structural, and electronic properties, carbon nanomaterials (CNs) (e.g. graphene sheets and carbon nanotubes) are supposed to be base materials for nanoelectromechanical systems (NEMS). In the present work, we propose a structural optimization method of carbon nanomaterials by introducing topological defects, which consists of the molecular mechanics method, the free-form optimization method, the Phase-Field-Crystal (PFC) method, Voronoi tessellation, and molecular dynamics (MD) simulation. The C-C bonds of CNs are simulated as equivalent continuum beams by a combination of molecular and continuum mechanics, so the atomic structures of CNs can be treated as frame structures. We adopt the free-form optimization method for frames to determine the optimal shapes of CNs in stiffness maximization problem. For obtaining the stable atomic structures of the optimal shapes of CNs, topological defects are introduced in the optimal shapes of CNs using a combination of PFC method, Voronoi tessellation, and MD simulation. The numerical results show that the compliance of CNs can be significantly reduced according to the structural optimization method, which is helpful for designing CNs components in NEMS.
As manufacturing has begun to move from mass production to mass customization, manufacturing industries are currently constructing the architecture to provide wide variety of products in countries around the world. Modular design and standardization is effective for mass customization. In recent years, modular design techniques have been researched in vehicle development. Then, car manufacturers have been announcing their own architecture about the car design. We have focused on pipe-based components as the standardized member of body structure. Since the pipe is a general-purpose member, we can get them easily. In this study, we have developed new design techniques for body structure consist of the pipe-based standardized components. Firstly, we have designed base frame layout by topology optimization formulated Min-Max approach for multiple load cases. Secondly, we have calculated cross-sectional design parameters by discrete design value table and fully stressed design. Using these techniques based on modular design rules, we can obtain body structure consisting of standardized components which are subjected to stress lower than the yield strength. As a case study, we have applied our unique modular design techniques to the rear body structure model.
This paper proposes a two-degree-of-freedom control systems design using a preview feedforward controller called zero phase error tracking controller (ZPETC) to improvethe tracking performanceof the disturbance observer-basedPredictive Functional Control (PFC) systems. To this end, we derive a pulse transfer function representation of the PFC controller, which is used for the design of ZPETC, and show some properties of the PFC controller. Then a disturbance observer-based PFC system combined with ZPETC is designed. Several experiments using a single axis table drive system are conducted to validate the effectiveness of the proposed control method. The experimental results show that the tracking error is dramatically reduced compared to the previously-developeddisturbance observer-based PFC.
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, a gait measurement system (Laser-TUG system) using a laser range sensor (LRS) has been proposed. The system tracks both legs and measures the foot contact positions to obtain walking parameters such as stride length and step length. 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 false tracking is likely to be occurred in the elderly and the measurement accuracy during the turning phase is still deteriorated because of occlusion and inaccurate observation of legs. Therefore, this paper presents a high-accuracy gait measurement system using multiple LRSs. Using multiple LRSs is able to reduce the situation of leg occlusion. However, the measurement accuracy of leg position depends on the distance from the LRS. To improve the measurement accuracy, an integrated leg detection method by a weighted mean of the observation candidates from each LRS data based on the distance from the LRS is proposed. We confirm that the proposed leg detection method can improve the success rate of leg tracking in the elderly and measurement accuracy of the leg trajectory and walking parameters.
Replacement of a damaged pipe is important to prevent an accident caused by the pipe. The major damage of the pipe in long-term use is pipe wall thinning. Thus, identification techniques of the location and the thickness of the pipe wall thinning are necessary to decide the appropriate time to replace the pipe. The ultrasonic testing (UT) and the radiographic testing (RT) are currently mainstreams in nondestructive inspections. However, the UT requires the surface preparation of the pipe, and the RT has the risk of the radiation leakage. This study has developed a novel technique of nondestructive identification of location and thickness of pipe wall thinning by using magnetic sensor. This technique aims at only nonmagnetic pipes, and estimates the location and the thickness of the thinning part in the pipe by using the measurement data of the magnetic flux density when the electric current is applied into the pipe. Furthermore, the measurement sensitivity of the magnetic flux density is improved by setting the high magnetic permeability material around the magnetic sensor. In order to verify the validity of the proposed technique, numerical simulations and actual experiments were performed by using specimens with several patterns of the location and the thickness of the thinning part. The results show that the direct analysis values agreed with the measurement data. The inverse analysis results show that the estimated values of the parameters to evaluate the thinning part successfully agreed with the correct values in most of the cases in this study. It is believed that the proposed technique can be applied to practical situations.
Singular stress and electric displacement fields occur at the vertex of interface in piezoelectric joints under an external loading. It can be expected that concentrated electric displacements causes large electric fields in an adjacent space and electric potential will be induced on the surface of electrode when the electrode approaches to the electric field. In the present paper, a piezoelectric joint which four blocks of piezoelectric material are bonded using a resin is analyzed. In this joint, a singular field occurs at a center gathering four vertexes in blocks and the intensity of singularity in electric displacements around the center of cross section in the joint may be four times larger. The intensity of singularity is numerically investigated using several methods for analysis to pursue the possibility of application of the singular fields. Firstly, three loading conditions, e.g., compression in the poling direction, compression in the vertical direction of side surface and input a voltage, are investigated for increasing a response of electric displacement in the piezoelectric joint. In the case of compression in the vertical direction of side surfaces, the maximum response is obtained. Hereafter, the results in the analyses are obtained for the compression of vertical direction of side surface. It is shown that the intensity of singularity depends on a power law of the thickness of adhesive layer. Influence of material properties of adhesive layer, piezoelectric and dielectric properties in the block of the joint, on singular fields is also investigated. It is shown that when piezoelectric materials with large piezoelectric constant are used, amplified electric displacements are obtained.
Agile manufacturing that can rapidly machine advanced materials or creative shapes is expected as an important key to realize mass customization of industrial products. Most of high-value-added workpieces have three dimensional and complex shapes. Thus, the workpiece shape and stiffness vary greatly according to cutting procedure during a rough machining operation. The induced displacement of workpiece strongly affects machining accuracy and tool life. However, it is difficult to automatically determine the process planning in commercial CAM system because of a large number of combinations. Therefore, the process planning has been designed by skillful experts to achieve complex parts machining. In order to realize future high efficient machining, it is necessary to obtain these tacit knowledges and to formulate the implicit machining know-how owned by skillful experts. As the first step, a method is proposed to decide workpiece shapes during a rough machining operation to ensure the workpiece stiffness based on topology optimization in this study. Topology optimization that is known as one of the highly flexible structure optimization methods enables to deal with the target configuration and shape. By introducing changeable fixed design domain and discretized characteristic function, an optimization problem can be converted to a problem of material distribution. In this study, the topology optimization is applied to decide workpiece shapes during a rough machining operation. As a purpose of minimizing their mean compliance, the optimized workpiece shape is calculated depending on applied loads at each machining step. By using the calculated workpiece shapes, a case study of complex parts machining is conducted. From the result, it is confirmed that a rough machining operation of complex parts can be achieved according to the decided workpiece shapes.
Recently, the diameter of through hole on printed circuit board (PCB) has become smaller with downsizing of electric devices. However, the drilling small diameter through hole includes some problems such as hole position accuracy and hole bending. Entry sheet is used to improve drill centering, drill guidance and reduction of burrs when drilling PCB. Series of drilling tests of PCB are carried out to investigate the effect of entry sheet on hole position accuracy, hole bending and chip-evacuation using three kinds of materials of entry sheet; aluminum, aluminum clad with lubricant and resin. The thrust during drilling entry sheet and the wear of the drill are measured. The hole position accuracy and hole bending examined after the drilling tests. The chips evacuation behavior out of drilled hole with the drill is filmed by a high-speed motion camera and the shape of chips produced is observed by a microscope. The amount of chisel wear and flank wear of the drill is not almost affected by the kinds of sheets. The hole position accuracy of entry side is worse as the maximum thrust during drilling entry sheet is increasing. The rate of increase of the amount of hole bending to the hit number of hole when using high rigid and high lubricant entry sheet decreases rather than that when using low rigid and low lubricant entry sheet. The evacuation out of drilled hole with the drill in case of drilling with aluminum clad with lubricant is better than that in case of drilling with aluminum.
This paper proposes an electrocardiogram (ECG) measuring system which simultaneously enables the reduction of input impedance and low-frequency cutoff through virtual amplification of the coupling capacitance formed by body capacitance and ECG electrode. This virtual amplification of the coupling capacitance is realized by the additional circuit which controls the inflow of external current to create the situation as if the time constant of the capacitance has increased. Moreover, not only this additional function but the amplification circuits commonly used in ECG measuring system has also been perfectly tuned-up. Here, instead of using the MOS-FET which shows bad noise characteristics, the combinations of J-FET differential amplifier and current feedback circuit have been used for stable amplification. In addition, coupling capacitors of the system are removed due to the DC-Coupling enabled by using single operational amplifiers instead of instrumentation operational amplifiers.
This paper describes a modularization method based on the creation of a new layout structure by combining topology optimization using beam elements and clustering analysis. By setting candidates for frame members in smaller units than parts and performing topology optimization using beam elements, a frame structure of new layouts as an aggregate of fine frame members can be created. For each fine frame member, connectivity as a structure in the entire frame structure is expressed as Design Structure Matrix (DSM). By performing hierarchical clustering on this DSM, clusters of fine frame members are formed as parts, and modules as these aggregate can be found out. Since this is hierarchically determined as a dendrogram, it is possible to determine the number of module divisions of the product configuration depending on the granularity of the cluster. Furthermore, by advancing each fine cluster towards the trunk above the tree diagram, an assembly process with less rework is obtained. Unlike the method of deriving the optimal solution for the product with existing structure, this research proposes a method to derive concurrently the new frame structure and construction of parts and module decomposition which minimizes rework. By validation analysis using a simple box structure, the effectiveness of this proposed method has been confirmed.
This paper proposes an advanced mesh generation technique that reuses the proven analysis models by similar sub-part search. The purpose of this development is to reduce interactive mesh improvement work time and to comply with the mesh specifications. The number of product specifications is increasing due to global business development and diversification of needs. Hence, the execution frequency of simulation is increasing. Therefore, it is necessary to reduce the working hours. Furthermore, quality improvement and standardization of analysis models are required because the general designers have learned to manage V&V. This technique consists of two distinctive techniques. First, it is the technique to search the sub-parts from newly design CAD where have similar shape with the archived feature sub-parts contained in the proven CAD models. In this technique, the similar sub-parts are retrieved from a CAD model described by boundary representation and made correspondence relation surface pairs of a retrieval model (proven model) and a target model (CAD of new design). A similarity score is based on the attributed graphs of a retrieval model and a target model. And, this score is calculated by a geometrical similarity and topological similarity. Second, mesh can be generated automatically by arranging and merging the mesh of similar sub-parts. Experimental results show that this technique can efficiency achieve mesh generation without interactive mesh improvement operation.
We have already developed an embodied communication system with the pupil response and demonstrated that the pupil response plays an important role in realizing smooth human interaction and communication. Therefore, the pupil response has possibilities to enhance a sharing of empathy and to convey rich affects such as a pleasure with laugh. Hence, in order to develop communication systems which enhance empathy, it is desired to design the media representation of pupil response. In this paper, focusing on the laugh with pleasure emotion as a typical pleasure affect, we analyzed the relation between laugh and pupil response using a pupil measurement device, and developed a pupil response system for inducing empathy by laugh response based on speech input. In addition, we evaluated the pupil response with the laugh by using the developed system. The results demonstrated that the dilated pupil response with the laugh is effective for enhancing empathy.
In this paper, a mechanism consisted of a double-cone rolling on two divergent-convergent rails is proposed to be used in the construction of a wave-powered electrical generator. Such divergent-convergent rails, attached to a buoy, can be materialized by using either straight V-rails, or eccentric circular rails. Rotational movement of the buoy, induced by the waves, is transformed into the rotational and translational motion of a magnetized double-cone. In this way, a variable magnetic field is extended over several coils, connected in parallel. Power generation is obtained through the electromagnetic induction effect. Firstly, a geometrical model is proposed to determine the length and radii of contact between the double-cone and the circular rails. Variation of the number of rotations, theoretically obtained, versus the rails eccentricity is validated by tests, where a double-cone, made in S45C carbon steel, is rolling on circular rails, made of A5052 aluminum alloy. Then, a model to evaluate the pressure of contact, and the change of potential energy of the double cone, is advanced. Based on such model, variation of the maximal contact pressure versus the rails eccentricity is clarified, for various loading patterns, corresponding to waves of different heights.
This paper discusses a micro manipulation considering that an approach angle on pickup affects adhesion and mechanical balance on release by using two needle-shaped end-effectors. In micro-scale, adhesion is generated by capillary, van der Waals and electrostatic besides gravity. Accurate and repeatable pick-and-release/place of micro sized objects is a long-standing challenge due to the strong adhesion in micro manipulation. We first introduce a strategy of pickup and release of a micro sphere. The strategy features in that the approach angle on pickup decides release by two conditions: one is geometrical condition between the sphere and a tip of end-effector, and the another is mechanical condition by forces (adhesion, gravity and friction) to the sphere from the tip and a substrate. To confirm the efficacy of the strategy, the micromanipulation tests with different approach angles have been conducted. Finally, we show the experimental results by pickup and release of spherical glass beads and not spherical pollens, for confirming the validity of the proposed strategy as a novel manipulation method.
This paper discusses the surface modification processing of kovar alloy (Fe-29.72wt%Ni-16.28wt%Co) by Na2SO4 electrolyzed oxidizing water (hereinafter referred to as EO water). First, the etching effect of Na2SO4 EO water on the surface of kovar alloy was clarified by comparative experiments of chemicals and NaCl EO water. The comparative study showed that as for the etching effect on the surface of kovar alloy, Na2SO4 EO water was superior to H2SO4 solution, but inferior to NaCl EO water. Next, by the observation using SEM image, the influence of Na2SO4 EO water on the surface shape of kovar alloy was clarified. The results indicated that when using Na2SO4 EO water, the surface of polished test pieces which had not been heat-treated becomes smooth, but in the test pieces surface which had been heat-treated, a lot of dimples had occurred. When using the supersonic together with one of Na2SO4 EO water or NaCl EO water, the surface shape became smooth. Lastly, as for the test pieces after heat treatment, the surface oxidation layer removal experiment by the immersion was carried out. The results showed that Na2SO4 EO water could remove the surface oxidation layer like H2SO4 solution approximately. However, thin surface oxidation layer might be formed when using Na2SO4 EO water. By this study, we received the suggestion that Na2SO4 EO water could be applied to the surface treatment such as the etching of kovar alloy.
Peening techniques are used to introduce the compressive residual stress into the surface of metallic materials in order to improve the fatigue properties. The fatigue crack propagation is affected by many factors in surface modification layer, however, the effect of these factors on the fatigue crack propagation is not clarified in detail. In this study, the fatigue crack propagation behavior in surface modification layer of duralumin treated by various peening techniques including shot peening, cavitation peening and laser peening was investigated. The relationship between the fatigue crack propagation behavior and mechanical properties was also evaluated. The fatigue crack propagation behavior varies depending on peening techniques despite the condition of the same peening intensity, since the mechanical properties in surface modification layer are changed with the peening techniques. The compressive residual stress σR and Vickers hardness HV are the important factors about fatigue crack propagation, however they do not show a correlation with the number of cycle to failure of the specimen Nf. Therefore, the new indicator combined with four factors i.e. σR, HV, full-width at half maximum β and maximum height roughness Rz were proposed. It revealed a significant correlation with Nf, and possibility to evaluate the effect of suppression of fatigue crack propagation by peening.
Vibration suppressors are used to change the natural frequency of an elevator rope and prevent resonance. The displacement of the parts of the elevator rope at both the ends is small compared to that of the center part of the rope; therefore, it is not necessary to set the vibration suppressors in the parts on either ends. The elevator rope is generally modeled using a string, and linear string vibration is well researched. However, the vibration of the string equipped with vibration suppressors encounters geometric nonlinearity, and hence, its characteristics have been studied under a few conditions. Furthermore, in the case in which the vibration suppressor is located except for both ends part of the string, no exact solution has yet been obtained for the free vibration of the string. In this paper, an exact solution is presented for the free vibration of a string when the vibration suppressors are located except for both ends part of the string. In the analysis for determining the exact solution, the problem of free vibration with vibration suppressors is transposed to a problem of forced vibration. Further, to verify the validity of the exact solution, a finite difference analysis of the string vibration with vibration suppressors is performed. The calculated results obtained from the finite difference analysis are in good agreement with the results of the exact solution.
Recently, recalls for mass production products such as car components have been frequently reported even for the case that the rate of defects is only of the order of ppm or less. The objective of this paper is to propose the solution to avoid the recall problem of the order of ppm for mass production products. Even if the defect rate is of the order of ppm or less, most of remaining safe products have to be recalled and be replaced by new components. Such a recall causes a great cost deficit if the very rare defect is possibly related to fatal accident. However, it is very difficult by the conventional quality control methods to find the defects of the order of ppm or less at the stage of design and production. This paper proposes a new practical quality control method to avoid the defects of the order of ppm or less for mass production products based on the statistics of extremes which has been successfully applied to fatigue strength evaluation of defective materials. First, several examples of the quality control method to avoid the troubles mainly caused by failures and damages of components will be presented. Next, it will be shown that the same approach also can be applied to other problems such as the optimum control of operational parameters and the selection of optimum materials through the index based on the statistics of extremes. It will be also shown that the same method can be applied not only mass production components but also to avoid the troubles and failure accidents for large machine components of small number production. The stress-strength model approach will be reviewed from the viewpoint of the statistics of extremes.
To explore the behavior of near-extinction flamelets in turbulent premixed flames, emission intensities of OH, CH and C2 radicals of hydrocarbon-air premixed flames have been examined using the newly developed emission spectroscopy system. It has been shown in our previous study that the emission intensity ratio of 515.5 nm/470.5 nm bands of C2 radical uniquely depends on the temperature of unstrained methane/air and propane/air flames. In the present study, to establish the technique that estimates the temperature of the near-extinction flamelet of turbulent premixed flames, the relation between the temperature and the emission intensity ratio of 515.5 nm/470.5 nm bands of C2 radical of strained flames has been sought by using a counter-flow burner. The unique relation between the flame temperature and the emission intensity ratio of 515.5 nm/470.5 nm bands of C2 radical has been found to exist for the Propane-air and the Butane-air strained flames. Therefore, it can be concluded that the temperature of flamelets of the Propane-air and the Butane-air turbulent premixed flames can be estimated by using the relation between the temperature of the strained flame and the emission intensity ratio of 515.5 nm/470.5 nm bands of C2 radical obtained in the present study.
Gyro actuator is often used for the posture control of systems which cannot be supported on a fixed ground. The gyroscopic moment makes preccesion movement of the gimbal mechanism and its effect depends on the rotating speed of the wheel. In this paper, the accurate dynamic model is derived for bicycle with twin gimbal mechanism considering ups and downs of the ground, which causes the disturbance to the bicycle. It turns out that the effect of the undulations of the ground is cancelled if the rotating speed of the wheels of the twin gimbal are exact the same. Then the stability of this model without feedback control is discussed. This model has fourth order characteristic polynomial and the characteristic roots for the first and the second modes are derived through lower order approximation. The first mode is unstable and the second mode is stable if there is a viscous friction in the gimbal rotation axis bearing. Simulation and experimental results show that the parameters should be designed so that the amplitude ratio of the gimbal pitch angle with regard to the cart roll angle for the first mode may become small to keep the posture of the bicycle for a longer time. This analysis method can be used for a simple feedback control system of the bicycle to evaluate the design parameters of the mechanism and control.
The uniformity of deposition thickness in electroplating processes is vital to the realization of desirable surface qualities of many products. The thickness distribution of deposits varies according to numerous factors, such as the arrangement and shapes of auxiliary cathodes, anodes and shields, and the detailed configuration of the plating process. In recent years, computer analyses such as the Finite Element Method (FEM) have become widespread. Such analytical tools can predict thickness distributions, search for optimal process configurations, and avoid production problems, to some extent, but the selection of the most effective analytical conditions still depends on skilled analysts. This study presents a topology optimization method to achieve uniform deposition thickness, applied to the design of the shields placed in an electroplating bath. The proposed method uses level set boundary expressions and the FEM to analyze the electrochemical field. The Kreisselmeier-Steinhauser (KS) function for the current density distribution on a cathode is employed as an objective function, since current density is nearly proportional to the thickness of the resulting electroplating. The magnitude of the current density on the cathode is set as a constraint so that it does not fall below a certain value, to avoid lengthy plating times that would occur if the current density were too low. Numerical examples are presented to confirm the utility of the proposed method and the results demonstrate that the proposed method can obtain appropriate shapes and arrangements of shields.
In recent years, needs for micro drilling are increasing, accompanying the development of higher wiring density of printed circuit board (PCB). When drilling PCB for the purpose of making the electric through holes, it has been said that the drill breakage is caused by being filled the chips of GFRP and copper of PCB in the drill flutes. The aim of this study is to clarify the effect of PCB drilling using DLC coated drill on tool wear, chip evacuation and cutting torque. Series of drilling tests of PCB have been carried out to investigate the amount of drill wear, the chips evacuation behavior out of drilled hole with the drill, the shape of chips produced and the cutting torque using DLC-coated drill and non-coated drill. The chips evacuation behavior out of drilled hole with the drill is filmed by a high-speed motion camera and the shape of chips produced is observed by a microscope. The cutting torque is measured by a dynamometer; Kistler 9329A. The amounts of drill flank wear and margin wear using DLC-coated drill and non-coated drill are almost the same. The chips of GFRP using DLC-coated drill are shorter and smaller than those using non-coated drill. The chips evacuation out of drilled hole with the drill using DLC-coated drill is better than those using non-coated drill, and cutting torque using DLC-coated drill is lower than those using non-coated drill.
Searching an odor source is a challenging task for a distributed autonomous mobile robot due to the complexity of odor formation in the air. Because the shapes of odor plumes highly depend on the environmental conditions including dynamical changes of wind direction, a robust performance of searching is highly demanded. In this paper, we introduced an olfactory active sampling device that was equipped electronic fan to generate air current and suction olfactory information to the sensors. Our main contribution was proposing and evaluating adaptive sampling strategies for appropriate odor-searching behavior in real environments by using the device. The active sampling device was designed after observations of the wing-flapping-effect of a male silkworm moth, which corresponding to‘ sniffing ’of mammals. The device was composed of an electronic fan, two (left and right) gas sensors embedded in air ducts, and was attached to a mobile robot. Each duct had a flange so as to take the air in front of a robot effectively, and the electric fan attached on the end of the duct excluded odors incoming from the rear. We settled different environmental conditions in which the fluctuation of the air flow was changed. We conducted experiments to verify the feasibility of the adaptive sampling system. As a result, under most of the environments, the robot with active sampling showed better performance than that without active sampling. However, the result showed that optimal active sampling has environmental dependency. To realize more adaptive system, we suggested that it is necessary to change the activeness of inspiration depending on the situation.
Since medicine treatment is one of the most major and effective cure methods, many patients take medicine every day. On the other hand, patients sometimes have serious accidents because some of them do not follow correct medicine dosing method (i.e. taking medicine without enough quantity of water). Though it may result serious accidents, in general, their doctors cannot notice the above-mentioned facts. In this paper, we propose a sensor-embedded intelligent cup that provides instructions for correct dosing and a medicine instruction support system using it. The proposed cup is the dual structure of a tumbler equipped with water level and acceleration sensors. The cup can detect if enough quantity of water is in it before a user takes medicine by using the water level sensor. We developed a calibration method for the water level sensor and implement it so that the quantity of water can be measured on any temperature. The cup can also detect if a user has taken medicine with the enough quantity of water from the cup by SVM (Support Vector Machine) using data of the acceleration sensor. Furthermore, the cup can also detect the quantity of water left in the cup using the acceleration sensor. The system will also provide the dosing history (i.e. when the dosing has conducted) to a user's caregivers (care giver and family in distant) through web interface. We conducted experiments and confirmed the positive effect of the proposed intelligent medicine cup.
Lower to middle tier regions of dam reservoirs often fall into the anoxic states in summer. When the anoxic state is reached, living things die, heavy metals such as manganese and iron, hydrogen sulfide and methane are eluted from mud deposited on the lakebed. Since it is not possible to release heavy metals exceeding environmental standards, an improvement of dissolved oxygen concentration in dam lakebed is required. So far, there is no system that can automatically improve the dissolved oxygen, in the lower to middle tier regions of dam lakebed. This study was carried out for developing an automatic system to improve the lakebed dissolved oxygen concentration to 6mg/L or more. The developed oxygen dissolution apparatus can diffuse a high concentration oxygen water horizontally at a rate of 1km per day. Thus, by raising and lowering this oxygen dissolution apparatus in water, a system that creates 3 - dimensional spreading of the dissolved oxygen not only to the lower tier but also to the middle tier regions was developed. The demonstration experiments, reported of the effectiveness of the system that can raise the dissolved oxygen concentration from the low oxygen-free state to the target of 10 mg / L in 5 days. Moreover, the system demonstrated its ability to automatically raise the dissolved oxygen concentration to 10mg/L in the 10m region from the bottom of lakebed.
Taper shaped skiving cutters are commonly used in gear skiving because they provide clearance angles under a simple gear arrangement and they could have lower cutting resistance than cylindrical skiving cutters. Their tooth flanks are generally ground by the same method of generation grinding with a trapezoidal wheel as ones for pinion cutter tooth flanks for gear shaping. In gear skiving, however, the process of tool-face re-grinding could increase profile deviations of cut gears due to the lack of an appropriate change in cutter profiles along the facewidth. In the present paper, computer programs were developed to simulate the generation grinding and the skiving with the cutting edges ground by the method. Skiving with a cutter ground by the method were carried out and skived tooth forms were compared with those calculated by the developed program. As a result, the comparisons could guarantee the reliability of the program. Furthermore, the program has revealed that the increase in a helix angle of a cutter yields the increase in tooth profile deviations of skived gears after regrinding the tool faces. Therefore, taper shaped cutters should be applied to internal gear skiving with extra caution.
Numerical prediction of air-entraining and submerged vortices in pump sumps is important for engineering applications. The validation of pump sump simulations, however, still is not enough, because the simulations is very complicated; for examples, treatment of gas-liquid interface, detection method of the vortices and selection of turbulence model etc. We conducted numerical simulations of the benchmark experiments of the pump sump conducted by Matsui et al. (2006, 2016) and compared the simulation with the experimental data to investigate the effects of turbulence model, grid density and detection method of the vortices. We determined a threshold of the gas-liquid fraction function of VOF method (α) and the second invariant of velocity gradient tensor (Q2) to detect the air-entraining and submerged vortices by using vorticity, respectively. This method well detected the vortices and well reproduced the experiments for the RANS simulation using SST k-ω model. Large eddy simulation using Smagorinsky model, however, was sensitive to the grid system and difficult to reproduce the experimental vortex structures even for the finest grid system having 3.7 million cells.
This paper considers ways to increase stability of wheelset hunting. The aim of this study is to introduce formulas which represent the damped natural frequency and its damping. This has been done by analytical and not by numerical calculation. These formulas are functions of mass, creep coefficient and other wheelset parameters. These formulas are obtained with a 2 degree of freedom wheelset model whose radius of gyration of yaw equals to a half of gauge and whose creep coefficient is isotropic, in the first part of this paper. In the second part, based on one of these formulas, ways to increase damping of wheelset hunting are discussed. First, it is shown that a longer wavelength of geometrical hunting is effective in reducing hunting at all vehicle speeds. Secondly, it is shown that at speeds slower than a certain speed, the damping is increased when the ratio of the wheelset mass to the creep coefficient is larger. Further, a symbolic formula for this boundary speed is obtained. Thirdly, if it is assumed that the wheelset mass is proportional to the square of the wheel radius, then at speeds higher than a certain speed, the damping is increased when the wheel radius is larger. Moreover a symbolic formula for this boundary speed is also obtained.
It is pointed out that the yaw dampers, which are often installed in between carbody and bogie frame of a high-speed railway vehicle, have such unfavorable points that the damping force is generated not only in the yawing direction but also in other direction. As a result the damping force is generated also to the longitudinal or pitching vibration of a bogie, and the excitation force acts in the longitudinal direction of the carbody resulting in the increase of the carbody vibration of the longitudinal or vertical direction. In this research, to enable the reduction of the excitation of the carbody vibration while maintaining the original function of yaw dampers to prevent bogie hunting motion, a new mounting structure of yaw dampers on railway vehicles has been developed. The new mounting structure enables to reduce the excitation force transmitted from a bogie frame to a carbody through yaw dampers. In this paper, the effect of yaw dampers on the carbody vertical vibration is firstly shown based on the results of an excitation test of a full-scale vehicle, then the outline of the new mounting structure for yaw dampers and the design and manufacture of the prototype device are presented. The vehicle dynamics model based on multi body dynamics was constructed and the suppression effect of the yaw damper force generated to movement in the direction other than the yawing direction of a bogie was verified by the numerical simulation. Moreover, the prototype device was installed on a full-scale test vehicle and a bogie hunting motion test was carried out to verify the running stability.
In this study, the relation between the thermal environment and the thermal comfort of occupants in a main line vehicle in the summer was investigated. At first, to understand the characteristics of the thermal environment in a main line vehicle, a field survey was conducted by measuring the temperature and humidity in regular passenger services from the morning to the night. The observation range of the temperature was from 23°C to 28°C, and that of the humidity was from 38%rh to 68%rh. Then, to obtain the fundamental data about the occupants’ thermal comfort, a subjective experiment in which 44 subjects in total participated was carried out. The subjects rode a main line vehicle stationed at a rolling stock center, and they experienced the temperature changing approximately in the range observed in the field survey and answered the questionnaires about their thermal comfort. Furthermore, the relationships between the thermal indices called PMV/PPD and the subjective evaluation values were analyzed. As a result, it was indicated that the error of the PPD in predicting the percentage of dissatisfied subjects became large in the range PMV>0, where the effect of the sweat sensation became significant. However, the PPD agreed well with the actual percentage of people who reported to have the feeling of ‘slightly cold’, ‘cold’ or ‘slightly hot’, ‘hot’. Our results suggest that the PPD can be used as an index of the variability of thermal sensation, but not as an index of thermal comfort in a main line vehicle in the summer; in order to use the PPD as an index of thermal comfort all the year around, it should be corrected taking into account the seasonal characteristics of the relation between the PMV and the actual percentage of dissatisfied occupants.
This paper proposes identification method of excitation force of rigid body vibration source by physical model identification. If the reworking occurs after the assembly of the prototype in mechanical product, the cost increases due to the retrofit countermeasures and development period extension. Pre-prediction of vibration at the design stage is important to avoid these problems. Prior prediction of vibration needs to grasp the excitation force of the vibration source. As conventional methods, the mount stiffness method and the matrix inversion method have been proposed. However, mount stiffness method calculates the mount transmission force. Therefore, if the development machine changes the structure, preliminary evaluation does not apply. The matrix inversion method can solve this problem. However, when the frequency response function contains a measurement error, the error spreading propagates in inverse matrix calculation. Therefore, in order to avoid the inverse matrix calculation, we propose identification method of excitation force of rigid body vibration source by physical model identification. In this paper, it was investigated features of the inverse matrix method and the identification method of excitation force by physical model identification using the basic experiment. As a result of study, the method by physical model identification showed that the influence of measurement error is smaller than the matrix inversion method. In addition, it showed that it is possible to identify the excitation force with fewer excitation points than the matrix inversion method.