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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.