Line-of-sight such as gaze and eye-contract plays an important role to enhance the embodied interaction and communication through avatars. In addition, many eyeball movement models and communication systems using avatars with the line-of-sight have been proposed and developed. However, these eyeball movements by generating the above-mentioned models were not considered to enhance the embodied interaction such as activated communication, because the models stochastically generate the eyeball movements based on the human gaze behavior. Therefore, in order to enhance and promote the embodied interaction from the view point of line-of-sight, it is desired to design a line-of-sight interaction which relates to the interaction-activated communication. In this study, we analyze the interaction between human gaze behavior and the interaction-activated communication by using an embodied communication system with line-of-sight measurement devices. Then, we propose a line-of-sight model based on the above-mentioned analysis, and develop an advanced embodied communication system by applying the proposed model to the speech-driven embodied entrainment character. This system generates the eyeball movements such as gaze and looking away based on the proposed model, and provides a communication environment wherein the embodied interaction is promoted. The effectiveness of the system is demonstrated by means of sensory evaluations of 15 pairs of subjects involved in avatar-mediated communication.
Recently, variety of products and services has become diverse, and it is getting more difficult to produce innovative product which matches user needs. For the reason, idea generation which is expected to produce methods of generating creative idea is getting more necessary. In idea generation, numeral methods of generating idea are proposed, some of which are brainstorming, KJ method, user observation and design ethnography. However, most of the processes are dependent on designers themselves, and this is because most part of idea generation process is still remained to be unexplained. We propose idea generation model from the cognitive psychological point of view. With the model, we propose that by activating nonverbal memory which is abundant information resource compared to verbal memory, creative idea is expected to be generated. On the other hand, there is attention: the system which controls the visual information processing is suppressing nonverbal memory activation. In this paper, we propose that dispersing attention makes nonverbal memory system more activated. We created attention dispersion system using eye tracker, and attempted an experiment to access effect on idea processing. From the experiment, participants gave more terms when their attention was dispersed, compared to trail without support on attention dispersion.
The rocket engine turbopump is the high-rotational speed and high-power turbomachinery to feed the propellant from the tank to the combustion chamber. Lateral vibration of turbopump rotor is a very serious problem and it has brought about the unplanned reworks in the development phase. In order to avoid these rework process, we have proposed the morphological design method in the upstream design phase. This design method is characterized by considering the layout and permutation of the turbopump rotor components (inducer, impeller, turbine, bearing, seal, etc.) as design parameter. In this paper, the adopting results to the liquid hydrogen turbopump by using the morphological design method are presented. It is possible for this design method to evaluate and compare the rotor vibration characteristics according to the layout and permutation quantitatively. Furthermore, pattern of superior morphologies was organized on the basis of overhang of turbopump rotor and the vibration characteristics of superior layouts and permutations were indicated. By the trial results, it is shown that the morphological design method is usable for rotating machinery to reduce the reworks.
Intensive knowledge sharing among multiple experts with different disciplines is a key success factor for designing complex engineered systems, especially in their early design stage. Graph-based knowledge representation models such as topic map and mind map are quite useful for such knowledge sharing and are widely used for collaborative design in various industries. However, it is not sufficient for collaborative design to share a graph model, which describes an agreed result of collaborative design process. The experts with different disciplines are incapable of understanding each other because each has different process knowledge for identifying and solving design problems, which isn’t wholly based on scientific rationality. Thus, such process knowledge should also be explicitly described and shared among these experts. To this end, the paper proposes a method for recording design thought process focusing on design parameter network. The paper first explained how to represent design thought in terms of variations on parameter networks in time. To record the design thought process, the authors have developed a parameter network model editor that stores every editing operation from the beginning. By storing the parameter network model evolution process as a series of individual editing operations such as addition/deletion of nodes, addition/deletion of arcs, changing contents of nodes, moving/resizing of nodes, design thought process of each individual designer can be analyzed. A simplified case study of machining process design for a bulb component has revealed obstacles for such an attempt as well as its feasibility.
This study tried optimization of design parameter of an ultra-thin flat plate dynamic speaker unit as an example of high flexibility of the products design. We derived the regression formula of the sound quality effect of each design parameter by the design of experiments and the multiple linear regression analysis, and the evaluation criteria was decided by the Analytic Hierarchy Process (AHP). The optimal combination was searched using the regression formula and the evaluation criteria from the combination of 4800 kinds of design parameters which can be manufactured. As a result, the combination of these higher ranks satisfied simultaneously some sound quality characteristics required for a speaker. Further, we made the prototype of the same specification as them, and they were compared with the predicted value. They had high accuracy to the predicted value. These results suggests that, though the optimum design is difficult by experience and intuition, it can be performed comparatively easily using the regression formula from the design of experiments and the evaluation criteria by the AHP.
In this paper, we analyze the relationship between brain activity and accuracy of replicating actions in the process of embodied knowledge acquisition. Subjects learned a series of actions as fundamental embodied knowledge as a experiment. Remembering and executing the actions, oxy hemoglobin increase in dorsolateral prefrontal area and decrease in frontal pole. Subjects watched a video crip of a working procedure, and executed the same series of actions as another experiment.. We conducted this experiment twice. After the first experiment, we set up three practice terms. In the observation task, oxy hemoglobin stabilize at a low level in dorsolateral prefrontal area and frontal pole with elevation of accuracy of replicating actions. In the execution task, oxy hemoglobin increase in dorsolateral prefrontal area and decrease in frontal pole with elevation of accuracy of replicating actions. These results suggest frontal pole relate self body imaging and dorsolateral prefrontal area relate working memory, and activity in these areas changes during the process of embodied knowledge acquisition.
Product-Service-Systems (PSS), systems which forces on generating higher value by integrating physical products and services have been attracting much attention in manufacturing. To design PSS business model, it is important to select best business model for your company after reviewing many business model in conceptual design stage. However, our business model design workshop has revealed that it is difficult for traditional product-selling manufacturing that inventing PSS business model which includes much service element. This is because PSS business model is far from their traditional business model. Thus, it is necessary to support contriving multiple business model options on the conceptual design stage. Therefore, this study supports manufacturing to design PSS business model and proposes a task management framework for reviewing PSS business model from their product-selling business model. The proposed framework provides the designers with viewpoints and checklists for PSS business model design. The effectiveness of the framework is demonstrated by an application to example case.
It is desired the method to analyze ordinary citizen's mental state and transition at social various situations, and the business applicability using that is expected. In Europe, the FilmStim database which can arouse specific emotion was edited. In this study, we examined whether the FilmStim can be applied to Japanese. And we investigated the relationship between brain activity and positive and negative emotion by using NIRS. It was indicated the possibility that the emotional score of European can apply to Japanese by explaining contents of film. When arousing positive and negative emotion, it was indicated that oxy-Hb was changed at outer part of right brain. This result suggests that measuring brain activities can be used to distinguish whether positive or negative emotion is experienced.
This paper proposes a dynamic table assignment method for a restaurant to reduce customer waiting time and inequality of lengths of waiting among customers. It develops a simulation model to estimate the remaining time until departure of each customer and evaluates effective sequences of table assignment in terms of waiting times and availability of tables using the model virtually. Gini coefficient value is used as an evaluation index for measuring inequality. In this paper, two conventional table assignment rules and the proposed method are described. Computer experiments demonstrate that the proposed method is superior to the conventional rules which assign in First In First Out (FIFO) way or assign smaller customer groups before larger ones.
Any engineering design project faces various types of uncertainties. They cause risk that a project goal cannot be accomplished within lead time. A design project manager should identify potential risk factors and causal relations among them in a project. Although it is worthwhile to spend much time on a workshop for project members to understand unnoticed risks, it is often a hard job to identify risk factors and causal relations in a mutually exclusive and collectively exhaustive way. This paper proposes a risk identification method based on a framework schematizing a fundamental model of a risk chain mechanism in an engineering design project in order to support a project manager and project members to systematically identify potential risk factors and causal relations among them. A proposed method provides categories of typical risk factors in an engineering design project. A typical chain mechanism among those categories is also defined. Those elements in a fundamental model can facilitate a project manager and project members to find unnoticed factors in a project. A case study of a risk workshop for a student formula car design project is demonstrated to show that the proposed method facilitates project members to understand potential risk factors and to build a comprehensive risk chain model.
Evaluation of ductile crack initiation limit without depending on materials was investigated. Ductile crack initiation behaviors were experimentally and analytically comprehended using Al alloy as non-ferrous metal in addition to two different steels. It was found that their limit characteristics were different between materials in the case of using conventional method based on stress triaxiality factor and equivalent plastic strain. It is considered that from cross section observations, ductile crack initiation for steels is caused by shear fracture between voids and the mechanism is different from Al alloy. Therefore, Mohr-Coulomb fracture criterion, which is related to normal stress and shear stress, was applied to the evaluation of steels. As a result, it was found that strain hardening exponent of the materials could be a new parameter. Using strain hardening exponent in addition to stress triaxiality factor and equivalent plastic strain, ductile crack initiation limit of different steels whose mechanism of ductile fracture is similar, can be evaluated with a master curve.
In order to demonstrate the effect of cavitation peening on crack initiation stage of hydrogen-charged materials with the objective of industrial application, and suppression of the delayed fracture of bolt, the delayed fracture test was conducted under constant load after hydrogen charging. The obtained results show that fracture surface at an origination of the delayed fracture took on intergranular fracture, and fracture occurred in a moment after crack initiate from stress concentration portion such as root of thread potion and incomplete thread. That is to say, evaluation of crack initiation stage of hydrogen-charged materials can be achieved by the delayed fracture test. Threshold stress σth of the delayed fracture was increased by cavitation peening and kept on increasing with processing time of cavitation peening. σth increased from 327 ± 22 MPa to 505 ± 42 MPa due to cavitation peening with tp = 6 s/mm. This effect was caused by introduction of compressive residual stress at root of thread potion, where subject to be fracture origin.
The aerogel composite insulation sheet which is complexed with fibers such as non-woven fabric and aerogel has been launched. However, it is one of the biggest problems for practical use that the insulation material has low strength and low rigidity because the main material is a fragile silica aerogel. Therefore, its durability as a structural material is a concern to use in various situations. So, in this study, for the five models modelled on the basis of the actual structure of non-woven fabric, which have respectively characteristic orientation distributions, it was examined whether the rigidity of the insulation material was improved by the design of the orientation of the non-woven fabric by using a structural analysis about the deflection evaluation due to its own weight of the insulation material. Consequently, it was confirmed that the rigidity of the material can be improved by aligning the non-woven fabric along the direction of deflection at the time of bending loads. In addition, for the non-woven fabric model that was targeted in this study, the distribution of orientation of the non-woven fabric doesn't affect increasing in the thermal conductivity (the deterioration of the thermal insulation properties) of the insulation by using a heat transfer analysis.
The objective of the present study is to investigate a factor on luminescence of rock induced by mechanical action such as fracture and/or sliding. The luminescence was caused by 3-points destructive test and sliding slip test. It was observed by an electron multiplication cooled charged-coupled device camera, i.e., EM-CCD camera. The intensity of the luminescence was also detected by a luminescence analyzer employing a photomultiplier tube. In order to reveal the role of SiO2 as a factor of piezoelectric effect, tensile strength and ambient gas plasma, SiO2 amount was measured using X-ray diffraction analysis. The test was carried out in air, nitrogen or oxygen. In addition, a spectrum analysis was done during slide slip test to verify the role of ambient gas on the luminescence. From the obtained results, it was revealed that the luminescence appears by fracture loaded by the 3-points bending and also the sliding slip test. The spot-like luminescence can be observed by the EM-CCD camera. The luminescence intensity depends on SiO2 amount in rocks and its tensile strength. When nitrogen is used as ambient gas, the luminescence becomes stronger. The luminescence of rock can be generated by plasma of ambient gas induced by piezoelectric effect in mechanical action, i.e., fracture and/or sliding.
Increasing of Si wafer diameter from φ300 mm to φ450 mm is required to enhance productivity of semiconductor devices. The authors developed a high stiff rotary grinding machine, which consists of a rotary table system and a wheel spindle system. These system are rigidly clamped using three ball screws and kinematic couplings. This paper investigates a basic design and the performances of the rotary table system equipped with constant flow water hydrostatic bearings. A fluid analysis around bearing pad was attempted by using the finite volume method in order to enhance a static stiffness of water hydrostatic thrust bearing. Performances of the developed rotary table was evaluated experimentally and compared with the analyzed value. The measured static stiffness and the numerical analyzed static stiffness ware 1.96 kN/μm and 1.97 kN/μm, respectively under the flow rate of each bearing pads Q=30 mL/min.
Rotary bending fatigue tests using magnesium alloy AZ61 treated by double ultrasonic shot peening (USP) and peening under other conditions were performed to investigate the effect of shot peening (SP) on the fatigue behavior and to obtain high and stable improvement in fatigue strength. The single USP treatment was conducted under the condition of the shot diameter of 0.6 mm, 1.0 mm and 2.0 mm and the coverage of 80 %, 200 % and 300 %. The air blast SP was conducted using Zirblast B120 shot and under the coverage of 300 %. The first treatment of the double USP was conducted under the condition of the shot diameter of 1.0 mm and the coverage of 300 %, and then the second treatment was conducted under the condition of the shot diameter of 0.6 mm and the coverage of 300 %. Microstructures, hardness, residual stress and surface roughness of each specimen were investigated and compared. The fatigue strength of USP specimens which were treated under the low coverage and the high coverage with the large shot diameter was decreased, while that of the other USP and the air SP specimens was improved. High fatigue strength improvement was achieved by the double USP compared with the base metal and the other single USP and air SP specimens. It is considered that the improvement of fatigue strength of double USP specimen is attributed to the enough increase in hardness and compressive residual stress in the first treatment and the decrease of surface roughness and the removal or the modification of the thin work-softened layer in the second treatment.
In this paper, the stress field at the interface corner edge of a bonded cylinder under bending is discussed by comparing with that under tension. Asymptotic description of the stress field under the bending consists of the singular stress term and the non-singular stress term as well as that under the tension. The similarity relation between the singular stresses under the tension and the bending is confirmed by performing 3D FE analyses on the bonded cylinders under the tension and the bending which are subdivided by the same mesh pattern. The ratios of the intensity of the singular stress field under the bending to that under the tension are computed changing material combinations variously, the maximum and minimum values of the ratios are shown in the table and the chart according to Dundurs' parameter (α,β). The intensity of singular stress field for the bonded cylinder cannot be controlled by Dundurs' parameter uniquely. However, because the differences between the maximum and minimum values are small, the ratios can be controlled by Dundurs' parameter. Then, the ratios are larger than 0.7 and smaller than 1.0 in almost all material combinations with α(α-2β) < 0.
In this study, we estimate supply potential of carbon-free hydrogen from wind power in Japan using spatial information such as wind speed and the land use. Then, hydrogen supply cost is revealed for every municipality in the Tohoku districts considering hydrogen production to distribution. The estimation indicates that the supply potential of carbon-free hydrogen in Japan is as much as 205 billion Nm3/year. With that amount of hydrogen a fuel cell vehicle can drive 3,030 billion km. When a high-pressure gas transport system is used for delivery of carbon-free hydrogen from each municipalities to Sendai city, the hydrogen supply cost ranges from 159.8 to 257.0 JPY/Nm3, and the average cost is 180.6 JPY/Nm3. If all cost component of carbon-free hydrogen supply system are replaced by the future cost target, the supply cost range decreases to 82.4~137.3 JPY/Nm3 and the average cost is 99.4 JPY/Nm3. The driving cost of fuel cell vehicle by this future hydrogen supply cost ranges 5.60~9.31 JPY/km and the average cost is 6.72 JPY/km. This cost is cheaper than 7.01 JPY/km of the internal combustion engine vehicle fueled with gasoline.
Ozone is almost exclusively generated by dielectric barrier discharge (DBD). The presence of the dielectric layer between the discharge gap leads to the formation of a large number of micro-discharges of nanosecond duration, and a thermal nonequilibrium plasma condition in atmospheric pressure is formed by this phenomenon. In this study, the reaction field by packed particle bed with titanium oxide was formed in a traditional ozone generator. Titanium oxide can generate active oxygen spices by the photocatalytic reaction (the internal photoelectric effect) using ultraviolet rays emitted from DBD and assist ozone generation by DBD only. As a result, high ozone yield and high ozone concentration have been obtained by using this ozone generation system and using pure oxygen as source gas, especially high ozone yield has been obtained by using low discharge power. These effects of packed bed with titanium oxide on ozone generation characteristics has been clarified by comparison with packed bed by aluminum oxide.
Lean flammability limits of PMMA dusts with diameters of 5, 15, 30, 50, 80 and 100 μm were measured by using a closed vessel method. The results showed that the limits for the dusts with a certain diameter or higher were affected by the dust size, and the PMMA concentration at the limit increased with the diameter. A simple model for the gasification of PMMA in the preheat and the reaction zone of flame was clarified that the change of the limit was caused by insufficient gasification. It showed that the particle with a certain diameter or higher could not be gasified perfectly in the flame and passed through the flame. This caused heat loss to the outside of the flame. Thus, the limit concentration became higher than the gasified fuels. Heterogeneous blended fuels with methane and PMMA dust showed that the lean flammable limit changed under the Le Chatelier method when the dust size was small enough, but the limit increased when the dust size was large.
Leg/Wheel mobile robots can achieve adaptive motions for various environments using legs or wheels. However, computational complexity of optimization like model predictive control (MPC) is increased with the number of degree of freedom on joints and wheels. In this research, we propose to partition a model of a leg/wheel mobile robot to decrease computational complexity. A model of leg/wheel mobile robot is represented by plural symmetric model for a leg composed of joints and a wheel. The robot is controlled by optimizing each leg sequentially using partitioned model at every control cycle. Partitioned models are connected by constraints to maintain body shape. While the configuration of a single leg is optimized, the robot can achieve concerted motion using predicted state of the other legs in the constraint. In this paper, we conduct tracking trajectory control of wheel position using partitioned model. We choose a difficult trajectory for the robot which includes rotational and translational motion to verify the performance of tracking trajectory. We confirm that the tracking performance is not deteriorated by experiment verification using an actual robot, while the concerted motion is achieved even if the behavior of each leg is optimized sequentially. Moreover, we verify that the computational complexity is decreased by the proposed method.
Various vibration attenuation methods such as a base isolation and a vibration control are suggested as seismic safety technique for large scale architectural and civil structure, and these methods have been practical used now. In recent years, these vibration reduction technologies begin to be applied to a small-scale structure. Application of seismic safety technology for a small-scale structure, however, is still remained a lot of developmental element yet. The enormous damage of overturning has been occurred in recent huge earthquakes including Great East Japan Earthquake. Therefore, the countermeasure technique should be an urgent task for huge earthquakes which are expected the occurrence in near future. In this study, a vibration attenuation system for light-weight structure with simple mechanism, good performance and low construction cost. This paper describes the fundamental design index of the overturning prevention mechanism for vending machine with a friction sliding from preliminary seismic response analysis, and new type simple mechanism using rotational support satisfied the specifications is examined from experimental and analytical verification.
This paper proposes a design and control method of a supporting arm which reduces a factory worker load. The supporting arm is a robot manipulator, which is driven by pneumatic cylinders, and it is attached to the worker's hip. In some situations, the factory worker will be forced to work with an uncomfortable posture, for example, a half-sitting posture, etc.. By using the supporting arm proposed in this paper, the worker leg loads are relaxed, and the worker posture is stabilized. To support 50 % weight of the worker body, the link system of the supporting arm is designed, and the pneumatic cylinders for actuation are selected. There are two required specifications: (i) support force is sufficient for supporting a target load, and (ii) desired stiffness characteristics (soft or hard stiffness) in the hip height direction can be obtained in each situation. The support force is controlled by a two degrees of freedom control system to satisfy the required specifications. The target load is supported by an output force of a feedforward controller. The desired stiffness characteristics are given by adjusting a proportional gain of a feedback controller. An experimental system of the supporting arm was developed, and its performance was evaluated by experiments. As a result, the experimental system shows capability of supporting the target weight and controllability of stiffness.
A way of deriving the fastest walk pattern of quadruped robots for trot gait is developed and installed into a practical robot system. Two support legs and the body are modeled as a five-link manipulator and each swinging leg is modeled as a two link manipulator respectively. As a first step, the fastest walk pattern of support legs is designed under the constraints of torque limits of leg joints and friction forces at the support leg tips. Then, the time optimal motion pattern of each swing leg is designed under the boundary conditions given by the obtained walk pattern of the support legs. The fastest walk patterns of support legs and swinging legs are designed respectively. Therefore, if the time optimal motion pattern of swinging legs doesn't satisfy the boundary conditions given by support legs, the same procedures are iterated by modifying a velocity parameter of the support legs until the boundary conditions are satisfied. SONY ERS-7 is used as a quadruped walking robot and some fundamental experiments are done to verify the effectiveness of the developed control algorithm. From the results, it is revealed that the proposed method is particularly effective on the ground with large friction coefficients.
Forklift trucks, a typical distribution vehicle, have a vibration problem in the vertical direction between 2 and 3 Hz, which is induced by surface roughness of the road. This vibration reduces not only the comfort of the operator, but also the distribution efficiency due to load collapse during travelling. Mainly because this type of vehicle deals with heavy loads, conventional elastic suspension cannot be adopted on these vehicles. Therefore, effective design improvement could not be proposed and applied to the whole-body vibration of the vehicle. Recently, with a view to improving working conditions and reducing the environmental impact from exhaust gas, many battery-powered electric forklift vehicles are replacing conventional diesel engine ones. This allows for larger scope to suggest design improvements that could reduce vibration by using some electric devices. In this paper, we propose a new type of control system using the induction motor which drives front tire to reduce pitching vibration by observing the pressure of the lift cylinder. In order to develop this system, we built a fundamental mathematical model to investigate the control rule, and then verified the performance of the controller on both system design and computer simulation of multibody dynamics. Finally, we measured a large increase in damping for an actual vehicle with a prototype of the control system.
Anti-vibration effects in tennis rackets with some gum pieces are analyzed by numerical simulations using the finite difference method. The simulated results of the string vibrations show the existence of wave propagations parallel to the two-dimensional rectangle boundaries. These results are confirmed with the experimental data of the sound specter analysis in good agreements. The anti-vibration effects of dampers are measured with changing the gum piece weights using an acceleration sensor and microphones. These fitted weights are investigated for general tennis racket at 55~60 pound tensions. The string sound damping is precisely investigated using these results. The gum piece structures are discussed for searching the efficient anti-vibration effects. It is found that popular gum pieces have fairly good ability of the damping effects.
As the globalization of various industries continues, the achievement of more sophisticated functions, improved safety, and lower costs is required, particularly in the automobile industry, which is a representative manufacturing industry that has been the driving force behind the economic growth of Japan. Under such circumstances, there is much hope for the reduction of cost from defective work, achieved by implementing preventive measures for the recurrence of defects as a means for improving earnings. Although every company has been conducting various activities intended to reduce costs, not much progress has been made with the reduction of defects for molds because of various reasons. The cost of defective work associated with a defective mold, however, comprises 3% to 10% of the earnings, and is therefore, considered an important management issue. This paper proposes a highly accurate method for collecting information in real time, and it is intended for the collection of defect-information. This paper also proposes a method for deriving trend values by conducting comparative analyses using the matrix method on results reflecting indicated matters selected from the perspective of mold requirements (requirements of product design for the purpose of mold manufacture intended at creating simple mold structures; this makes it possible to create molds that can be manufactured with shortened manufacturing period, and it is used to process work in a short period of time and still satisfy quality requirements while holding down the cost) on product design and the mold trial results. The information is systematically converted into know-how based on this method, to contribute towards the prevention of recurring defects. It is applied to the external appearance components of audio panels to verify its effectiveness. It is possible to select indicated matters pertaining to slides of mold structures and the effectiveness is verified as a result.
The action of standing up is a starting point when we move to the next actions, and that is performed frequently in daily life. This action induces the pain in joints as people age. Supporting to the action of standing up is important to prevent the nursing care level from advancing. In this research, we develop the mechanism for assisting standing movement from the low position that can set on the floor in the japanese-style room. Double pantagraph jacks are used to expand the operating range of seat plate. We design linkage to follow two postures of legs. Namely, these are starting posture, and ending posture of the standing up motion. Generally, it is difficult to raise the heavy body with the jack in the lowest position because the motion transmissibility can't be gained sufficiently. The mechanism to drive the seat plate is installed under the armrest in order to make the start position of standing lower enough. The length of the link composing the jack is determined to get the height of the seat plate enough to assist the ending posture of the standing up motion. The position where the two links are connected to make them intersecting is indicated as an internally dividing point. This intersecting position of links is determined to make the seat plate follow the attitude of human leg. There are five choices of length of link, and there are four choices of the intersecting position of links, so it is possible to make twenty combinations. From twenty combinations, the best combination is determined by the method of considering the space occupied by the mechanism and the output height and the attitude of the seat plate. The gas spring is used as the power source, the specification of the power source is gained by the static analysis. The experimental device is manufactured using the parameter determined from twenty combinations. It is verified that the seat plate of the experimental device follow the two posture. We evaluate this device's supporting performance by the floor reaction force and the electromyogram of the leg. From the result of measurement of the floor reaction force, the reduction of the physical load is verified. From the result of surface myogenic potential, the muscle activities of the anterior tibial muscle and the gastrocnemius muscle are reduced by using the assist device. On the other hand, the muscle activities of the rectus femoris muscle and the semitendinous aren't reduced very much. It is seemed that the power unit is needed to improve to support in the lower position sufficiently. Points to be noted so as to design the driving source using linear springs are shown.
Diamond wire saws are widely used in slicing various kinds of hard and brittle materials, such as silicon, sapphire, etc. Electroplated diamond wire tools are used for high-efficiency slicing process, because of high abrasion resistance. However, low production efficiency of diamond wire tools causes high cost in the production process, because the electroplating rate is low. To solve the problems, a drum-type manufacturing method for electroplated diamond wire tools was developed in this study. Multiple diamond wire tools could be manufactured simultaneously at high speed in one machine. The mechanism of drum type electroplating unit was introduced, firstly. Then the electroplating characteristics, such as maximum current density, Ni deposition rate and uniformity of electroplated wires, were evaluated. Composite electroplating experiments using diamond abrasive were carried out and the effect of electroplating factors on the amount of electrodeposited diamond grains was discussed, too. It was found that turbulence flow of electroplating solution could improve amount of deposited diamond grains. Long diamond wire tools were manufactured and used to slice Si ingot, it was confirmed that the developed wire tools have high slicing performance equal to the commercially available diamond wire tool.
It is of practical importance to accurately evaluate the influence of tooth surface deviation and modification on the tooth surface strength of transmission gears. In this study, gear surface fatigue endurance tests were carried out with pairs of helical gears having various helix deviation, crowning and tip relief. The results showed that some damages on the tooth surface occurred unexpectedly earlier under certain conditions of these tooth flanks than the fatigue life predicted with a conventional design method based on Herzian pressure on the tooth surface. After observations of the tooth surfaces, it was found that the damages were caused by trochoidal interference, and the influence of the trochoidal interference on the occurrence of the damage was different in the meshing position, namely, the beginning of meshing and the end of meshing. The trochoidal interference in the beginning of meshing was much injurious to the occurrence of the damage. The tooth surface strength of transmission gears needs to be evaluated taking into consideration the occurrence of the damage caused by the trochoidal interference, because the conventional design method of tooth surface strength has a risk to overestimate the tooth surface strength. Therefore, the author discusses a new method combining the tooth surface temperature with the Herzian pressure to predict the occurrence of the damage caused by the trochoidal interference for a practical gear design.
When railway vehicles pass through a sharp curve, yaw moment is generated at the bogie. This condition affects the increase of the lateral force of the outside wheel of the front axle of the leading bogie, which is important factor for assessing the running safety of railway vehicles. A Lateral-force/Wheel-load estimation equation has been developed as a method to calculate the lateral force and the wheel load during the curve passage of railway vehicles taking into account the yaw moment of the bogie. This equation is useful to estimate the risk of flange-climb derailment. The authors have newly suggested a more versatile Lateral-force/Wheel-load estimation equation with a focus on the improvement of the estimation of yaw moment of the bogie. Running tests using test track which has sharp curves were carried out to measure the generated forces of several components of the bogie, which are the sources of the yaw moment of the bogie. New equations were produced based on the test results, and compared with the measured lateral forces and wheel loads.
This paper studies model predictive control (MPC) for spacecraft nonlinear attitude control with actuator input nonlinearities. This technology is important to achieve high-rate large angle attitude maneuver problems of recent spacecraft missions. To this end, we first derive linear matrix inequality (LMI) conditions to ensure input-to-state stability (ISS) or asymptotic stability (AS) of MPC closed-loop systems for standard actuators such as reaction control systems (RCS) and reaction wheels (RW). After providing optimization algorithms based on branch and bound methods, we evaluate and compare the control performance of each case using RW, RCS and both RCS and RW in combination through numerical simulations for astronomical observation satellite.
In this paper, Technology Circulation Model is proposed as a new management method for companies with existing business domains that plan and execute industry-university collaborations to make innovations. Based on this model, we discuss concepts for effective planning and execution of industry-university collaborations through real cases. Technology Circulation means a flow of Science - Technology - Engineering - Manufacturing & Services, then to Science again. We show the effectiveness of the framework of industry-university collaborations, in which; empirically used techniques are visualized, complicated phenomena are explained simply, new sciences are established, and current industrial technologies are made more sophisticated. By starting from visualization of currently used technologies, it becomes possible to execute efficient industry-university collaborations matching the directions of business needs and academic seeds.