This paper describes a finite element method (FEM) analysis for cold burring process of large diameter SGP pipe. The large diameter pipes such as Φ89.1 mm are used for a plant as a flow channel of gas and liquid. A burring process of pipe is generally for forming the branch. The burring process is achieved by drawing of die from prepared hole. And the branch pipe is welded to the formed pipe. This process has some problem. One is the forming limit of pipe, and the other is needed to machining the end surface to be welded. Each problems are depend on the prepared hole shape, thus the optimum prepared hole shape is required. In this study, FEM analysis was operated to estimate the optimum prepared hole shape. Prepared hole has two dimensions because of ellipse. At first, the length of longitudinal and circumferential direction of ellipse was estimated. Secondly, the measurement of the other point that was effected on the end surface shape was estimated.

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This paper describes a commercial scale twin roll strip casting process for producing aluminum alloy strip of A3003. Twin roll casting process is able to produce a strip from molten metal directly. Thus this process has a possibility to reduce total cost of sheet making. However strip casting process has some disadvantages. Casting speed depends on the material properties. It is difficult to decide the casting conditions. Aluminum alloy A3003 improves workability and corrosion resistance comparing to pure aluminum, and aluminum can and roof board is made of it. Many paper on the strip casting are reported. However, there are few reports on the commercial scale machine. In this study, the effect of roll speed on the strip casting was investigated. Castability, surface conditions and strip thickness were investigated. It was possible to produce strip at 10 m/min and 20 m/min roll speed, but it wasn’t able to produce sheet at 5m/min perfectly by the commercial scale twin roll strip casting process. Each surfaces of produced strips were transcribed form the roll surface, and the surfaces had a metallic luster. The faster the roll speed, the thinner the strip thickness.

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Materials used for transportation equipment such as automobiles and electric trains are required to have low density and high strength. It is well known that magnesium alloys are the lightest material in practical metals. Weight reduction is possible by using magnesium alloys for transportation equipment instead of steels or aluminum alloys. However, magnesium alloys have several disadvantages; low strength, poor corrosion resistance and low ignition temperature. The strength of the magnesium alloys can be increased by grain refinement. Friction stir processing (FSP) is one of typical methods for grain refinement of metallic materials that enables microstructures with fine grains. Regarding ignition temperature, calcium addition has been known to solve the problem. In this study, we investigate the effect of crystal grain size on strength in FSPed specimens of flame-resistant AZX 611 magnesium alloy.

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Recently, research and development of high strength steel sheets for weight reduction of vehicles have been continuing. High-strength TRIP-aided steel using the transformation induced plasticity of the retained austenite has high strength and ductility. However there is an issue of hydrogen embrittlement as well as conventional high strength steel. Although retained austenite present in TRIP-aided steel has been reported to improve the hydrogen embrittlement properties, detailed relationship with the shape and volume ratio of the retained austenite is not clear. In this study, TRIPaided steel with various amount of retained austenite is prepared, and the effect of retained austenite on the hydrogen embrittlement properties is investigated.

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Gum Metal is a β-type titanium alloy having properties far apart from ordinary metal materials, and it has been known that low Young’s modulus with high strength and other various properties are exhibited by applying strong cold working. It has been considered to be attributed to a special deformation mechanism of Gum Metal, which has not been elucidated yet. In this research, to study its special deformation mechanism, Gum Metal specimens with different crystal grain size were prepared by changing solution treatment temperature ranging from 800 to 1000 degree C. Nanoindentation test is conducted on these specimens to compare the deformation mechanism with one in Ti-18Mo alloy.

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This paper describes the basic characteristics of semi-solid forging of aluminum alloy A7075. Semi-solid forging has some advantages, such as better dimensional accuracy than casting and smaller molding load than cold forging. And semi-solid materials can be expected to have improved mechanical properties compared with ordinary materials. Forging was carried out simulating semi-solidified die casting of A7075, which is difficult to process compared with other wrought materials, and the influence of manufacturing conditions on porosity, impurities, surface texture and microstructure was investigated. Using a servo press (by AMADA Co.,Ltd.) and a die cushion, a test piece without cracks was produced by applying a load of 40 tons to a semi-solidified slurry at 525 ° C for 10 seconds. When the test piece was visually confirmed, the impurity was 0.02 pieces /mm² , and porosity cavity was 0.0086 pieces /mm² . Spherical equiaxed primary alpha aluminum was observed in the punch side, the center side and the die side.

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This paper describes basic property in semi-solid forging method of magnesium alloy AZX1311. In the semi-solid forging process, an arbitrary fraction of solid is selected at a temperature between the liquidus and the solidus line and rapidly cooled and coagulated simultaneously with deformation of the material in a die to obtain a product. In addition, the magnesium alloy AZX1311 has excellent castability and mechanical properties. In recent years, the use of magnesium alloys for home electric appliances and automotive parts has been increasing because weight reduction can be achieved. These main manufacturing methods are casting and forging. However, these manufacturing methods have disadvantages such as large forming load and poor dimensional accuracy. Therefore, the semi-solidification forging method can improve these disadvantages. In this study, a forged semi-solid material and air cooled semi-solid material were produced using a servo press machine. Focused on impurities, porosity and microstructure. A forged semi-solid material could be produced. A semi-solid structure could be observed.

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Weight reduction of car bodies is a serious environmental issue, since the large amount of carbon dioxide is generated by transportation equipments. Currently, aluminum alloys are expected to be used for a car body for weight reduction, and further weight reduction will be achieved, if magnesium alloys can be applied. But magnesium alloys have several practical disadvantages; lower strength, poor corrosion resistance, etc. It has been known that strength of metallic materials can be improved by grain refinement, and recent reports revealed severe plastic deformation like high pressure torsion (HPT) or friction stir process (FSP) is very effective to reduce grain size. In the present study, the effect of grain size on the strength in FSPed Mg-Al-Zn alloys is investigated. The conditions for FSP and subsequent heat treatment are changed to obtain the specimens with different grain size.

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From the viewpoint of measures against global warming and environmental protection, improvement of fuel economy of transportation machines is required, and weight reduction of a vehicle is cited as a solution means. Currently, the high-speed railway vehicle body is predominantly made of aluminum alloys, but by substituting magnesium alloys that are lightest among the commercially available metallic materials, it is possible to reduce the weight of the railway vehicle body. In order to realize this, flame-retardant magnesium alloys with calcium addition attract attention. Although fatigue crack propagation behavior parallel to the rolling (T-L) direction of the newly developed AZX 811 was previously investigated in comparison with that of a commercially available AZX611 (both alloys are flame-resistant), no investigation has been made in the direction perpendicular to the rolling (L-T) direction. Therefore, in this research, as a basic research to elucidate the fatigue characteristics of the developed AZX 811 magnesium alloy, evaluation of fatigue crack propagation behavior in L-T direction of the alloy is performed in comparison with commercially available AZX 611 and AZ 31 alloys.

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In 7000 series alloys, hydrogen embrittlement (HE) tends to occur when the density of grain boundary precipitates is high such as in T6 (peak-aged) condition. The overaging treatments such as T73 can coarsen the grain boundary precipitates but they also coarsen the intragranular precipitates resulting in the decrease in strength. Reversion and reaging (RRA) treatment was once developed as an ideal process to achive coarse grain boundary precipitates together with fine intragranular precipitates, but was found to have a drawback that uniform precipitate microstructure cannot be obtained thoughout a whole member of the structure, arising from the processing difficulty in the reversion. On the other hand, it is assumed that quenching condition can control and roughen the grain boundary precipitate with alomost no effect on the intragranular precipitates, leading to an improved resistance to HE without any loss in strength. As a fundamental study to find this kind of ideal heat treatment, we performed step quenching followed by peak aging to obtain a coarse grain boundary precipitates together with fine intragranular precipitates. In the present study, we carried out SSRT tensile tests in humid air and dry nitrogen gas environments to assess the resistance to HE on an Al−Zn−Mg−Cu alloy step quenched and peak-aged and heat-treated in the other conditions.

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Recentry, boriding has attracted extensive attention as surface stiffening processing. Boriding is a method of diffusing and permeating boron on the surface of a metal material. In this research, the influence of processing time on the formation layer of Inconel 600 by Al added fused salt bath was examined. In addition, in order to improve the surface hardness and abrasion resistance of Inconel 600, the effect of the treatment of boriding on the formation layer has been investigated. Boriding were performed in molten borax which contained about 10 mass% Al at processing time of 0.5 ~ 2.0 h (processing temperature of 950℃). As a result of the examination, the hardness of the boriding layer becomes about 2000 HV in any times and the boriding layer becomes thicker with processing time. Also the abrasion resistance has improved remarkably. Furthermore, it was revealed that the formation layer was boronized Ni from the Vickers hardness and analysis of the X-ray diffraction measurement.

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The effect of the sand materials on the appearance and dimensional accuracy of the casting in the expendable pattern casting (EPC) process was investigated experimentally. The aluminum alloy casting of the simple shape with the rib was cast by EPC process, and the dimensional change of the casting from the expendable polystyrene (EPS) pattern was measured. When the natural silica sand was filled loosely, the positive different dimension of casting from the EPS pattern was caused, and the leaching of the molten metal due to cracks in the coat wall was observed. However, when the artificial sand was filled, even with loose filling, the different dimensions of the casting were small.

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It is known that intergranular corrosion and stress corrosion cracking due to hydrogen embrittlement occur in the 5000 series aluminum alloys when the Mg concentration exceeds 5%. Therefore, the Mg content of the commercially available alloys is limited up to 5%. However, when a 5000 series alloy is welded, solidification segregation occurs, resulting in a possibility that local Mg concentration exceeds 5%. In the present study, humid gas stress corrosion cracking (HG-SCC) test was applied to evaluate the resistance to hydrogen embrittlement of base metal of a 5083 aluminum alloy O-tempered, as the first step of the fundamental study on the resistance to hydrogen embrittlement of weld joint. Also, hardness test of the welded O-tempered 5083 material was carried out and hardness distribution in the weld joint portion was investigated.

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As a problem of the Hall-Heroult process, which is the most widely accepted smelting method of aluminum, it is mentioned that the smelting cost is higher than that of other metals because it consumes a large amount of electric power. For this reason, several other methods were targeted and as a new smelting method to replace the Hall-Heroult process, but it has not been industrialized yet. We have used plasma that can be expected to generate non-equilibrium reaction at low temperature. In the previous research, Inoue and his co-workers attempted the reduction of aluminum oxide by hydrogen plasma. After the plasma irradiation, it was confirmed that the aluminum oxide was reduced since the electric resistance of the specimen surface was markedly decreased, and the research is still underway. In the present research, we have adopted hydrocarbon, acetylene, as plasma to irradiate, and as fundamental study to develop another smelting method that is lower in cost than the Hall-Heroult process, we have tried to reduce aluminum oxide to aluminum with hydrocarbon plasma.

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Light weight and high-strength, aluminum alloys are widely used as structural components of transportation equipment such as aircraft, railway cars and automobiles. Recently, weight reduction and improvement of driving performance is required and increasing strength of light metallic materials has been expected in the near future. The 7000 series aluminum has the highest strength among practical aluminum alloys, which have been originally designed as precipitation-hardness alloys. However, environmental embrittlement of these high-strength alloys is a practical problem which is often related to their precipitated structure. In this study, we investigated the effect of cold rolling on mechanical properties and hydrogen embrittlement behavior in an Al-10%Zn-2.6%Mg-1.6%Cu-0.2%Cr alloy by Vickers hardness test and SSRT tensile test. As a result, the cold rolled specimen was stronger than the specimen generally heat-treated to T6 condition.

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The divertor material which receive the highest heat flux load in the next large nuclear fusion experimental devices are considered to use carbon fiber reinforced carbon composites (C/C composites, tungsten and beryllium). C/C composites have the highest heat resistance (sublimation at 3,650K) and the highest thermal shock resistance in material, and are considered to be the only material which can bear up against the highest heat flux load such as a plasma disruption. In this research, isotropic graphites, a pyrolytic carbon and a C/C composite were irradiated by neutron with a low temperature and a high neutron flux in the research reactor (BR2) of Belgium. The fundamental knowledges about the neutron irradiation effects on mechanical properties and microstructures of carbon materials were obtained.

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It is crucial to understand the hydrogen embrittlement behavior when steels become high strength, since hydrogen which invaded the materials often reduces their strength and ductility. The phenomenon that materials under the static load fail after a certain period of time is called delayed fracture, which has been also considered to be caused by hydrogen. The influence of hydrogen on the mechanical property of high-strength austenititic steels has been investigated, and it has been reported that hydrogen sometimes does not cause brittle fracture. In the present study, the slow strain rate technique is made to investigate the hydrogen embrittlement behavior in cold-rolled high-strength Fe-Ni-Al-C alloy specimens.

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In this paper, we consider a control method of standing stabilization for people with disability in lower limbs. There is a problem that people with paralysis in lower limbs can not maintain standing stabilization condition, and do not have sense of sole. Human body posture is modeled as a double inverted pendlum with a foot. Using that model, we design the optimal regulator controller for stabilizing the standing posture by automatic control.

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In this paper, we consider the identification of stabilization control law of human standing. Recently, exoskeletal leg support systems for people with paralyzed lower limb are studied extensively. We consider development of a control law for the leg support system to enhance standing stability is required. For this purpose, standing motion of a healthy subject is measured by a motion capture system and a force plate. Then the feedback control law is estimated from the measured data.

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In this paper, we combined with manual and automatic control on a wearable leg support system for lower limb disabilities. The system has actuators at lower limb joints, and has a special control lever mounted on the unaffected shoulder. This system operates by lever operation of the wearer. Therefore, it is possible to realize an operation reflecting the intention of the operator, but there is a danger of falling due to disturbance or the like. In order to solve the problem, we additionally implement a control method that automatically stabilizes the posture against disturbance in the support system. The control law is identified from the lever operation of experts, and the effectiveness is confirmed by experiments. In addition, we evaluate manual operability when implementing automatic control, through experiment.

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This paper is concerned with the application of bilateral control for the operation of the leg support system for people with hemiplegia. We developed a wearable leg support system Manipuleg-2 with actuators on the hip, knee and ankle. In that system, the control lever only detects the posture of the wearer’s arm, which is transformed to command signals for the leg actuators but could not produce forces for the wearer ’s hand. We have developed a mew control lever driven by two motors for the bilateral control so that the wearer can sense the movement of the leg by hand while walking．Ascent and descent experiments on a step were conducted for an able-bodied subject with a mock prosthesis, which simulates hemiplegia who has no leg and foot sensations. The effectiveness of the proposed bilateral control method is shown by these experiments．

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This paper is concerned with the dynamics of mobile robots with a three-wheel cluster. The mobile robot with three-wheel cluster can travel on flat floor by rotating each wheel, and can ascend and descend stairs by rotating a wheel cluster hub. This makes the robot to be able to move around in various environment, and the control strategy would be applicable to powered wheel chairs which can ascend and descend stairs. In this paper, we consider only the dynamics of the robot in the sagittal plane. The dynamics of the mobile robot has the single-wheel mode in which the robot should be dynamically stabilized, and the double-wheel mode in which the robot is statically stable. Furthermore, switching between these modes involves collisions of a wheel and a stairstep, and the velocity jump in motion of the robot occurs. We have derived the dynamics and the switching conditions of the mobile robot with a three-wheel cluster. Furthermore, we propose a control strategy for the robot ascending and descending.

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This paper proposes a wheeled walking assistive apparatus that assists a person with hemiparesis not only for rehabilitation but for supporting his/her daily life. This apparatus has high stability comparing with leg types because its wheels always contact on the ground. In addition, the user does not need to support the weight of it. This system comprises two units: a driving unit and a sensing unit. The user wears the driving unit under the bending hemiplegic knee. Differential gears provided between front wheels enable the user to rotate in the horizontal direction. The driving unit is controlled based on the angle between both legs measured with the sensor unit. Results obtained from experiments demonstrate that non-disabled persons can travel indoors stably.

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One of the most general snake's locomotion patterns is lateral undulation. Its important characteristic is sinus-lifting. It has an effect of improving propulsion efficiency. We made a hypothesis that sinus-lifting occurs due to geometrical and physical characteristics of the musculoskeletal system based on the anatomical findings. We investigate it by using snake-like robot PAS-2. PAS-2 is based on anatomical knowledge. In our former study, we measure only reaction force. However, it is necessary to simultaneously measure three-dimensional kinematics and reaction force from the ground. In this report, we simultaneously measure reaction force and three-dimensional kinematics. In the experiment, we gave PAS-2 two kinds of muscle drive patterns of EMG and simple pattern. There was no significant difference between these two kinds of muscle drive pattern and the results partly vouches the hypothesis. However, we found some problems in the mechanisms and the electric systems of the robot, which are our future works.

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This paper proposes an electric wheelchair that realized traveling on uneven environments and standing. This wheelchair allows a caregiver to reduce burdens and a user to improve QOL. Conventional electric wheelchairs have mainly four problems: medical problems due to sit for a long time, a psychological problem caused by the low position of eyes, problems that the user needs some assistance when transferring, and low traveling performances on uneven environments. The proposed wheelchair comprises two mechanisms: a link mechanism supported by a gas spring for changing its posture and a traveling mechanism with a part of crawlers and a flipper arm for getting over steps. This paper discusses the autonomous stair climbing for the proposed high-performance wheelchair. The autonomous stair climbing are demonstrated using a 1/3 scale model.

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Currently, various traveling robots for irregular ground, e.g. crawler type, multi-legged type, and snake-like robots have been developed. While the crawler type and multi-legged type robots have high ability for traveling on irregular grounds, they can not move such environments as underwater, in narrow spaces, on sands and on a wall. On the other hand, the snake-like robots have extremely high potential for traveling on irregular grounds including in narrow spaces, on the wall and so forth. We have been developing a snake-like robot that can travel not only on a flat rough surface but on a tree. We demonstrate that the prototype snake-like robot can travel on a linoleum floor and on an artificial turf. We also discuss a strategy of traveling on a terrain with several pegs.

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Vascular smooth muscle cells (VSMCs) are representative cells that respond to force and are important cells that constitute the blood vessel wall and regulate the vessel diameter by relaxation and contraction. VSMCs change their phenotype from contractile to synthetic under pathological conditions. A similar change is observed when VSMCs are isolated from the native tissue and placed in culture conditions. To understand smooth muscle pathophysiology, it is important to understand the mechanism of their phenotypic change. However, previous studies including ours only used cultured synthetic VSMCs on the dishes, which is quite different from VSMCs in vascular tissues in vivo. To overcome this problem, we developed a novel micro-grooved collagen substrate to control cell orientation similar to in vivo vascular tissue, and cultured VSMCs on this substrate to induce their contractile differentiation. Then we investigated the changes in the mechanical properties of VSMCs using an atomic force microscopy, and assessed the changes in the nuclear-cytoskeletal interactions during smooth muscle differentiation.

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Cells grow in accordance with the cell cycle, preparing it for cell division and duplicating their DNA. Since these preparations are mainly performed inside the nucleus, it is considered that the morphology and shape of nuclei change during cell cycle progression. Previous studies have reported that the nucleus morphology passively be involved with cell disease, such as carcinogenesis or senescence of the cell leading the nucleus to a heterozygote. Thus, the quantitative data of the morphological changes of the cell nucleus have a potential for becoming a powerful tool to forecast cell fate. Therefore, in this study, we observed the living cells whose nuclei were fluorescently visualized, and analyzed the nuclear morphology and shape change in the cell cycle.

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Proliferation and motility of cells may be closely related to cell shape and intracellular tension developed with actinmyosin contractile proteins, but details are not clear at this stage. Therefore, in this study, we investigated the intercellular tension by the traction force microscopy. We analyzed traction force of vascular smooth muscle cells in which existence of two phenotypes, "contractile type" which is a spindle shape and high contractile ability and "synthetic type" which is irregularly spread shape and low contractile ability are reported. Fluorescent beads were embedded in a polyacrylamide gel whose elastic modulus can be easily adjusted. After coating the adhesive protein on the gel substrate and seeding the cells, the cell shape was visualized by fluorescent staining of the cell membrane. Then, the displacement distribution of the beads on the surface of the gel substrate by the cellular tension was obtained by the image correlation method, and the cell tension distribution was measured from the obtained displacement distribution and the elastic properties of the gel substrate obtained by the atomic force microscope. We found a significant correlation between cell area and intercellular tension and a tendency that there was no significant difference in intercellular tension as the cell shape changed. Furthermore, the relationship between cell shape and intercellular tension was discussed.

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Improvement of blood compatibility inside rotary blood pumps is an important issue in development of ventricular assist devices (VADs) and total artificial hearts (TAHs). Couette-type blood shearing devices are often used to evaluate hemolysis property with respect to various shear stress. Quantitative evaluation of amount of hemolysis is an important in investigating effect of surface properties inside rotary blood pumps on hemolytic properties. However, the amount of hemolysis possibly changes depending on condition of the blood and experimental environment. In this study, a concentric rotational shear stressor that can simulate shear rate generated inside the VADs and TAHs has been developed. This paper investigated reproducibility of hemolysis amount with three types of shearing cylinders. Two of these cylinders have different mean surface roughness of Ra0.7μm and Ra 0.2μm, and another has hydrophilization treatment. Although, rough surfaced cylinders did not indicate sufficient reproducibility, the smaller surface roughness reduced standard deviation of the hemolysis amount. In contrast, the smallest standard deviation was achieved with the hydrophilized cylinder, and indicated well reproducibility of the hemolysis amount. The results indicate that elimination of factors causing the large standard deviation of the hemolysis amount should be required to obtain reliable relationship between the surface roughness and hemolytic property.

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A compact maglev motor has been developed for use in implantable ventricular assist devices. The maglev motor consists of a homopolar type radial magnetic bearing (MB) and a radial flux permanent magnet synchronous motor (PMSM). A rotor is magnetically suspended with the inner MB and is driven by the outer PMSM. The maglev motor has an external diameter of 60 mm and a height of 20 mm. In this research, torque and energy efficiency characteristics of the developed PMSM were evaluated. In addition, magnetic levitation and rotation performance was then investigated. Maximum rotational torque of the PMSM is 26 mNm. Maximum energy efficiency of the PMSM is 58% at a rotating speed of 5000 rpm and rotating torque of 11 mNm. Power consumption of the PMSM is less than 8 W at required toque for circulatory support. Oscillation amplitude of the levitated impeller in radial direction is around 0.06 mm, except maximum oscillation amplitude of 0.17 mm at the resonance rotating speed of 3800 rpm. Power consumption of the MB is less than 2 W at an operational speed range of the VAD. The developed maglev motor indicated the better rotation performance and the sufficient magnetic levitation stability.

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An extracorporeal magnetically levitated blood pump, which consists of an axial magnetic bearing, a levitated impeller and an axial flux motor, has been developed to recover cardiac function of acute heart failure patients. Rotating speed of a levitated impeller is changed in synchronization with heart beat to increase coronary flow of a natural heart or reduce load of the natural heart. The transient change in the rotating speed of the impeller causes a detection error of rotating angle, which prevents maintaining constant phase difference between rotor flux and control flux. Increase/decrease in axial attractive force produced by the motor due to the variation of phase difference deteriorates suspension stability of the maglev motor. In this study, a magnetic coupling mechanism which can reduce the variation of phase difference was employed to transfer torque to the levitated impeller. Dynamic characteristics of the maglev motor with the developed magnetic coupling mechanism were then evaluated. The rotating speed of the levitated impeller was transiently changed from 1200 rpm to 2400 rpm in physiological saline medium. Maximum oscillation amplitude of 0.13 mm in the previous maglev motor was successfully decreased to 0.05 mm by utilizing the magnetic coupling mechanism. In contrast, there was no significant change in radial displacement of the levitated impeller according to the motor drive mechanism. In the future, magnetic levitation stability will be improved by optimizing the size and arrangement of the rotor permanent magnets for magnetic coupling motor.

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The carpometacarpal joint (CMC joint) is a joint constituted of distal carpal row and metacarpal base. The second and third CMC joints have complicated joints and can hardly exercise due to the jagged articulation surface. The fourth and fifth CMC joints are slightly motile at the saddle joint. This mobility makes it possible to deepen the concavity of the palm. The metacarpophalangeal joint (MCP joint) is a joint that enables flexion and extension, abduction and inversion and rotation of the proximal phalangeal base on the metacarpal head. In order to understand the contact area of the joint, it is necessary to investigate the relative contact area of the joint with the movement to the object. In this study, we used magnetic resonance imaging (MRI) to investigate the variation in the three-dimensional contact area and contact distribution of the in vivo CMC joint and MCP joint associated with flexion angle in the state of grasping four kinds of sphere. They displayed mean fifth CMC joint of the little finger contact areas of 78.8±18.4, 87.2±3.3, 84.6±6.3 and 80.0±7.8 mm² in a neutral position, a soft ball grasping position, a tennis ball grasping position, and a ping-pong ball grasping position, respectively. They displayed mean second MCP joint contact areas of 61.6±4.1, 48.9±15.6, 55.8±3.1 and 74.3±3.7 mm² in a neutral position, a soft ball grasping position, when grasping a tennis ball, and when grasping a ping-pong ball, respectively.

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Up to now, many studies have simplified the foot mechanism as plate-like parts. However, it is considered that this plate-like foot can not keep sufficient supporting area on uneven terrains, which makes stable walking difficult. In this research, we propose a foot mechanism that connects multiple spikes with a wire pulley mechanism. Each spike of this foot mechanism can expand and contract, making the foot mechanism deform according to the uneven terrain to obtain a larger support area. Moreover, it is thought that not only the actual support area but also the pressure center (ZMP) can be measured by having each spike a three-dimensional force sensor. At the present stage, we created a one-row foot mechanism with seven spikes and realized deformation function according to uneven terrains. In the future, we will try to realize the function to measure the support area and ZMP by using this one row foot mechanism.

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There are still many barriers for the visually impaired. Regarding the tactile map that can be read by touching, there are problems that the installation location is not enough, the details are hard to understand, and the cost is high. These problems can be solved by using virtual reality technology. Solve these problems by creating virtual walls in the virtual space and creating touch maps using them. In this research, we aim to realize virtual wall using haptic glove and describe fundamental research aimed at reducing barrier of visually handicapped person.

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In designing sports compression tights, to acquire accurate strain distributions of sports compression tights during exercise is important in order to control its pressure properly. In this study, the strain distribution of sports compression tights during exercise was acquired based on image correlation method. An artificial leg jig made of polymer foam was prepared. The artificial leg jig reproduced the shape of the leg of the CG model of the human body. The strain distributions of sports compression tights worn by the leg jig were measured by image correlation method. From the experiment, large strain was measured on the side surface of lower leg and the front surface of knee joint. From this result, design method of sports compression tights was evaluated.

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This study proposes the autonomous driving programs at a signalized intersection. The programs are two types. The first type is amber detection type. This type detects the amber by the camera and makes a judgment of stopping before the intersection or entering the intersection. As a prerequisite traffic rule, when the amber is displayed, the vehicle must not enter the intersection. However, it is excluded when the vehicle can not be stopped safely. More than 60% of the incident cases verified by this type were avoidable. Another type is amber preview type. This type based on vehicle-to-infrastructure cooperative system. This type obtains signal information previously and makes a judgment of stopping before the intersection or entering the intersection. As a programmed rule, if the vehicle can not enter the intersection during amber, or if the vehicle can not pass through the intersection while all the signals are red, even if the signal is green signal, the vehicle stops before the intersection. Approximately 90% of the incident cases verified by this type were avoidable.

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It is important for light rail vehicles (LRVs) to have bogies that smoothly pass sharp curves. In order to increase self-steering ability of independently rotating wheelset (IRW), the new-type of IRW with negative tread conicity has been proposed. In previous study, it is shown from numerical simulation that the new-type wheelset have enough self-steering ability than the conventional wheelset．However, running performance in extremely sharp curve with a radius of 15 meters assuming LRV is insufficient only with numerical simulation, and it is necessary to understand the phenomena by experiments. In this paper, 1/10 scaled experimental model with rigid wheelset and negative tread IRW are developed. By running tests, the curving performance of two type of wheelset is compared in terms of attack angle. As a result of running tests, the negative tread IRW has smaller attack angle in the constant curve than the conventional wheelset and has higher self-steering ability.

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Curving performance is important for railway vehicle. In a railway bogie, a wheelset in which the right and left wheels are rigidly coupled with the wheel-axle is generally used. The wheelset causes noise and wear due to insufficient wheel diameter difference in a sharp curve with a radius of about 10 meters existing in a tram. Using independently rotating wheels gives potential effectiveness, and authors proposed a self-steering bogie with independently rotating wheels which makes the most of gravity restoring force. However, a steering bogie with independently rotating wheels for a driving bogie has not been considered in our research. Even though some researches regarding active steering bogies exist, active steering bogie with traction which enables ideal curving is not realized on service operation. In this paper, we propose an active steering bogie with traction which measuring the wheel lateral displacement and the angle of attack with displacement sensors. As a result of numerical simulation with SIMPACK, proposed bogie and its control strategy are confirmed that the bogie has excellent steering performance on a sharp curve.

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The purpose of this study is to develop a two-joint musculoskeletal robot incorporating a joint drive mechanism that mimics biarticular muscles of humans. Musculoskeletal robots are assumed to be suitable to perform interactive tasks with environments and humans because they can adjust the joint stiffness. In order to develop the biarticular mechanism, the biarticular actuator should be connected to the two joints to provide actuator force to them simultaneously, which prevents the two joints from moving separately. In this study, we propose a novel biarticular mechanism that drives both joints and allows the joints to move separately by using a biarticular actuator consisting of two motors.

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The aquatic propulsion mechanism by using wedge-shaped vibrating elastic plate obtains propulsion force from traveling waves on the plate generated by vibrating a leading edge on the plate. But reduction of the propulsion force is caused by generating standing waves. The standing waves are generated by superposition of the traveling waves and the reflected waves generated at the rear end. In order to improve the propulsion force, suppression of the reflected waves by adding translational control and rotating control on the rear end is considered. The above plan is validated by using Finite Element Analysis.

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Mono-crystal sapphire is widely used for smartphone cover glasses, blue LED substrates and other optical and electronic applications. Sapphire crystal is extremely high in both in strength and toughness. Also, mono-crystal sapphire takes a hexagonal structure with C- (0001), A- (112̅0), M- (101̅0) and R-(11̅02) planes, but lack of clear cleavage or slip/twin plane. Such kind of material commonly falls in a category of difficult to cut material. Its material removal mechanism in grinding is insufficiently elucidated. Rotary infeed surface grinding by diamond wheel is an alternative used for wafering of sapphire crystal. In this study, the removal mechanism of rotary infeed surface grinding is investigated, via grinding power and cross-section of individual chip, under different grinding conditions and wheel specifications. It was found that specific grinding energy Cp increases with a decreasing in chip cross-section and the coefficient C is important parameter for determining material removal mode.

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The purpose of this research is to increase the processing efficiency by performing ELID grinding using fixed abrasive grains for brittle material of high hardness such as sapphire. Grinding of sapphire involves problems of falling off and burying of abrasive grains. As a solution, use a high hardness iron bonded diamond wheel made by electroplating method. Moreover, in order to obtain good surface roughness for sapphire, it is considered effective to increase the processing pressure applied to the abrasive grains. Therefore, we developed a grinding stone with the concentration degree set to 50. This grinding wheel and sapphire were attached to a triaxial processing machine, and ELID grinding processing was performed on the A side of sapphire by a traverse method. As a result of experiments, it was confirmed that the developed grinding wheel has removal ability against sapphire. In addition, good surface roughness could be confirmed at more places than the processing result of concentration degree 100.

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Sapphire is used as a growth substrate of GaN for blue LEDs. It’s necessary for the substrate to obtain a smooth surface by CMP polishing, however it takes a lot of time and cost to create a mirror surface without damage, because sapphire is high hardness and has chemical stability. In this study, a newly mechano chemical composite abrasive (MeCCA) was developed for polishing of sapphire C face. We investigated polishing characteristics of MeCCA and the possibility of a grindstone with MeCCA as a component.

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This study is mainly focused on the selection of grinding conditions for mirror finish of CVD-SiC work piece. Because surface roughness affects products quality when CVD-SiC is used as a molding die. In addition, since this material has a wide range of other uses, many precise processing techniques are required. As a result, it was possible to get a required surface by choosing a grinding wheel with a fine grain size, shortening the feed pitch, and performing truing before grinding. In this study, it was possible to select the reasonable grinding condition with the help of grinding principle and method shown in the paper.

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The CMP mechanism of SiC can be explained by removing the layer after formation of oxide layer. Nomally, the oxide layer is formed by UV light or oxidezing agent, and its removal is generally performed with abrasive grains. In this report, we proposed a newly polishing process which is not used strong oxidizing agent and abrasive grains but used only PVA pad.

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A gyro, which is a detector sensitive to angular velocities, can detect angles without any angle references, where no other detector can perform as a gyro. This feature makes it possible to evaluate angles consequently profiles and positions with no restriction in their directions nor ranges. However, errors caused by a gyro represented by a rate offset, which is a change in the gyro’s angular signal with time, should be eliminated for improving their evaluation accuracy. This is the major issue to be resolved. We had adopted a periodical reversal measurement with rotating a gyro around an axis perpendicular to its sensitive axis for eliminating fluctuations in the detected angular signals and derived angles without affected by the fluctuations, aiming to adopt it for evaluating alignment of large (longer than 100 m) object such as particle accelerators accurately (better than 1 mm). In this study, a new method, which derives angles from angular velocity signals of the rotating gyro for our new system to be developed, is considered. The simulation results show that the method based on lock-in detection can improve accuracy comparing to our conventional method based on FFT.

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In Small-hole EDM, it is known that the machining speed declined while machining deep hole because of deteriorating discharge state due to insufficient removal of machining debris. Some experiments have shown that the machining speed improved by adding grooves to electrode in the forming process. Furthermore, giving ultrasonic vibration into deep hole machining by EDM can improve the machining efficiency. Therefore, the authors have produced Straight groove electrode for improving removal of debris in order to reduce deteriorating discharge state during deep hole machining. The grooves were cutting to normal pipe electrodes by metal die. Electrode diameter are 1mm and 3mm. The machining speed decline in Normal pipe electrode machining, but the reduction of the machining speed could be suppressed in the Straight groove electrode machining. Therefore, the Spiral groove at aim for further improvement of machining speed electrode was conceived. But it is impossible for cutting to make spiral groove. Therefore, a special EDM-machine forming groove has been conceived and designed. This report explains groove forming method and developing a special EDM machine.

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For improving the efficiency of the Nano-scale machining, we propose a vibration cutting method by using a microcantilever as a cutting tool instead of the usually used scratch cutting method. We optimize the microcantilever in shape so that the excitation force could be efficiently transferred to the tip and load a diamond ground by FIB (Focused Ion Beam) on it. In a series of machining experiment, we employ two kinds of excitation methods based on sinusoidal excitation and feedback control. Under the former and latter excitations, the microcantilever is externally excited and self-excited, respectively. By analyzing and contrasting experimental results with two kinds of vibration cutting methods, we demonstrated the machining product is improved by using the self-excited vibration cutting method because the microcantilever could keep in the resonant state regardless of the change of the natural frequency during machining.

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In this study, we devised a method of printing gellan gum solution and forming gellan gum gel using electrostatic inkjet method. Electrostatic ink jet is capable of printing highly viscous liquid with high resolution because liquid is ejected from the tip of the nozzle by electrostatic force, so that liquid smaller than the nozzle tip is ejected. Gellan gum is a polysaccharide and gellan gum solution turns into gels when it reacts cations contained in the culture solution. Therefore, it is low in toxicity. In addition, gellan gum gels are capable of cell culture thereby modifying the cell adhesion factor. From this fact, it was thought that it is possible to fabricate precise gellan gum gel biodevice. From the characteristics of gellan gum, it is possible to fabricate a gel having a unique shape by printing gellan gum solution of using an electrostatic ink jet. In this research, we investigated its characteristics and report it.

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