For a small axial-flow fan installed in a duct, the effects of the acoustic resonance occurring in the duct on the flow field and aerodynamic characteristic were investigated. The measurements of the sound pressure level around the fan installed in two ducts with different widths showed that more intense acoustic resonance occurs for the narrower duct at the blade passing frequency for a specific rotational speed. Moreover, the static pressure coefficient of the fan was found to drop at the specific rotational speed where the intense acoustic resonance occurs (resonance condition). To clarify the effects of the acoustic resonance on the immediately downstream wake flow of the fan, velocity measurements were conducted by a hot-wire anemometer. As a result, the time average velocity became lowest at the resonance condition for the narrower duct. This is possibly because the circumferential velocity became low due to a decrease in pressure load causing the curvature of the flow by the fan blade. Moreover, the power of velocity fluctuations around the blade tip in the frequency range lower than the blade passing frequency became largest at the resonance condition, which indicates the intensification of disturbances in the tip leakage vortices. The decreased pressure load and increased turbulence lead to the deterioration of the fan pressure coefficient.

Acoustic resistance of the rectangular orifice of a resonator attached on a duct was measured. Four types of resonator orifices with different corner shapes were used. To express acoustic resistance as a linear sum of bias flow velocity, grazing flow velocity, and particle velocity in the neck of the resonator, we classified the measured resistance data in two regions dominated by sound pressure and grazing flow velocity, respectively. The acoustic resistance is approximated by the larger value of the linear sum in good agreement with experimental results. The dependence of the acoustic resistance on the Strouhal number was also examined. The variation in acoustic resistance due to vortex shedding at similar orifice corner shape shown by Moers was clearly reproduced.

This paper presents a stability analysis and exciting mechanism of coupled vibration of translation and rotation of a plate supported by air pressure. In recent years, air floating systems are used in a manufacturing floor to transport a glass plate. The plate is supported by air pressure and the system has characteristics such as low noise and low power. However, a self-excited vibration occurs under specific conditions. The purpose of this study is to clarify the stability conditions and exciting mechanism of two degree-of-freedom coupled system of translational and rotational motions. Characteristic equations of the system are obtained by arranging the basic equation of gap flow and the equation of motion. Unstable conditions are obtained by using Routh-Hurwitz stability criterion to characteristic equations. Furthermore, exciting mechanism of rotational vibration are obtained by calculating work acting on the plate. Finally, critical flow rates were compared for analytical models of only rotational vibration and coupled system of translational and rotational vibration.

Ni-Co-Mn-Sn metamagnetic shape memory alloys are known to show drastic change of magnetization upon martensitic transformation. For a selected composition, a steep magnetization change occurs slightly above room temperature. In this paper, we propose a structure which generates change of magnetic force by temperature difference between the room temperature and heat source using the alloy and two permanent magnets. By combining the structure and a magnetostrictive vibrational power generator consisting of Fe-Ga alloy plate, U-shaped frame, coil, and magnet, electrical energy can be taken out from a heat source of about 50°C. As this principle demonstration, the prototype using plate of Ni-Mn-Co-Sn alloy of 10×10×1.5 mm was confirmed that adsorption (heating of the alloy) and desorption (cooling) were repeated in about 200 seconds, and power generation by free vibration was carried out every time. It will be possible to extract energy necessary for radio communication from a low temperature heat source.

For power microrobots that perform power-needed tasks in narrow spaces, we have proposed an alternating pressure system using ER valves. The ER valve controls an ERF (electro-rheological fluid) flow with its increased viscosity due to an applied electric field. In the alternating pressure system, an alternating flow is rectified with synchronously switching ER valves and supplied to a soft actuator, which realizes smaller piping space for multiple actuators. In the conventional system, liquid crystal type ERF was used, however, the ER valve cannot be shut off, which caused internal leakage. In this study, we proposed an advanced alternating pressure system using particle type ERF that can shut off the ER valves rapidly. We investigated the characteristics through numerical simulations. Then we fabricated the advanced alternating pressure system and clarified its characteristics and effectiveness experimentally.

Force-display devices can be classified into two types according to the difference in the method of force generation: active type and passive type. Active type devices use actuators such as motors and pneumatic artificial muscles, and are capable of active force presentation. However, pneumatic artificial muscles have limitations of pressure propagation speed due to air compressibility, and so have difficulty to present force sensation at high speed. Passive devices cannot present the force sensation acting during stoppage. The purpose of this study is to develop a hybrid force-display glove with a balloon actuator as an active element and an electro adhesive gel (EAG) brake as a passive element, which compensates for the shortcomings of both mechanisms, and to construct a force presentation system integrating the above two to realize effective rehabilitation for hemiplegia of the fingers, a typical sequela of rheumatism and stroke. This paper describes the overall concept of a hybrid force-display system for a glove with excellent real-time performance, and the determination of grasping VR objects using the measured voltage of bending sensors attached to each finger and the bending angle of the finger model.

Recently, soft material structures, in which liquids and droplets are introduced into solids in various shapes, have been attracting attention. These structures can be used in the fields of soft electronics, soft robotics, and wearable devices, etc. In this study, we focus on the auxetic structures, which are patterned structures with negative Poisson's ratio. Herein, we fabricated an auxetic channel structure in elastomer using 3D printer and aimed to develop a novel wearable device with liquid metal inflow. This room-temperature liquid metal has been widely used in flexible and stretchable sensors, focusing on embedding liquid metal in microchannels, liquid metal microdroplets formation, captive sensors, and liquid metal nanoparticles, etc.

In order to achieve higher performance in spark-ignition engines, it is required to control the intake and exhaust valves in stepless manner according to the engine speed. Our research group has been continuously studying the electromagnetic drive valve system using a linear actuator. In this report, we have designed a linear actuator with a dual Halbach array of permanent magnets in the stator to further increase the thrust of the linear actuator. The thrust characteristics of the proposed model were investigated using electromagnetic field analysis based on the finite element method. The analysis confirmed that the Halbach array concentrates the magnetic flux on the coil side, which generates Lorentz force.

Soft robots employing soft polymer materials such as gels and elastomers have various advantages such as compact, lightweight, and silent motion. Recently, biomimetic structures driven by pneumatic control have been attracting attention though various driving sources have been proposed. In this study, we have fabricated cylinder-shaped soft robot with an armored (exoskeleton-like) auxetic structure with a negative poisson's ratio that placed around bellows-typed tube. We have investigated the structural variability and walking performance of the armored cylinder structure.

In this study, we designed the multiple semi-bellows type arms driven by pneumatic contoroll, and attempted post-functional operation after pre-fixation in order to utilize the three-dimensional deformation of their actuator functions. In addition, we paid attention to the chiral structure of the auxetic rotation mechanism and studied the 3D deformation synchronized with the mechanical 2D manipulation.

In this study, we evaluated a variable-stiffness and deformable link using shape-memory alloys (SMAs) and the jamming transition phenomenon. For the SMA, the austenite and martensite structures are stable at high and low temperatures, respectively. When an SMA is heated, it transforms from the martensite to the austenite phase and recovers its original shape. During the cooling process, it transforms to revert to the martensite phase. During each heating and cooling cycle, the transformation starts when it reaches the austenite-start temperature and the martensite-start temperature. The stiffness of SMA is high at the austenitic phase and low at the martensite phase. The jamming transition phenomenon for granular material has been widely used as a method to change the stiffness of robots. This phenomenon is the change from fluid-like to solid-like conditions by removing air from a space containing particles. In our previous study, we exploited the characteristics of SMAs and the jamming transition phenomenon to develop robot components with variable stiffness and sensitivity. In this study, we evaluated the variable-stiffness and shape-fixity properties through the experiments using the prototype link.

In the manufacture of thin steel plate, which are widely used in industrial products such as automobiles, contact transportation by rollers is performed. However, deterioration of surface quality due to contact with rollers has become a problem in steel sheet production lines. Therefore, a non-contact magnetic levitation transfer of thin steel plates using the attractive force of an electromagnet has been proposed. So far, we have investigated the levitation performance of a magnetic levitation system that uses both a horizontal positioning control system and a curved magnetic levitation system. In this report, we conducted a basic study on the non-contact transfer of thin steel plates from the shape analysis by the finite difference method on the effect of the tension application position in the magnetic field of the magnetic levitation transfer system on the vibration characteristics of the steel plate.

The suspension for automobiles reduces the vibrations transmitted from the road surface to the vehicle body, which improves vehicle dynamic performance and ride comfort, springs to the shock absorber as the main structure, and oil damper is widely employed in the vibration damping portion. In recent years, in response to the problem of reducing the noise in the car which is called rattle noise, evaluation is required including transient attenuation characteristics of the damper. We construct a damping force characteristic analysis model which considers the transient response of a damper in the car noise prediction system using the 1D model, and the evaluation of transient damping force response near the open operation using this model was obtained.

During the drying process of paints, the solvent contained in the paint volatilizes and the film thickness decreases. Since this property is highly dependent on the drying temperature and can affect the quality of the paint, appropriate temperature conditions and film thickness control are required. In this study, a model based on mass transfer theory was developed to calculate the paint film thickness at an arbitrary elapsed time. As a validation test, wet film thickness was measured by a non-contact film thickness gauge and compared with the analytical results. As a result, accurate paint film thickness prediction was achieved by setting appropriate parameters for different drying conditions.

In recent years, manufacturing has focused on the combination of “Real (Measurement)” and “Virtual (Simulation)” such as Digital Twin. Data assimilation is one of the methods to realize the Digital Twin. On the other hand, “Physical modeling” is often used for complex plant models because of high readability, modifiability, and multi-domain support. In our privious work we developed Data assimilation library using Modelica Language. We extended this library to Particle Filter and apply to inverted pendulum and assimilated measurement data to simulation.

Generally, 80% of a product's environmental requirements are determined at the design stage, and material selection at the design stage for environmental considerations is said to be of utmost importance (1). Material design through material selection requires the embodiment of knowledge about various materials. This report describes a methodology for environmentally friendly product design at all stages of product development. First, the need for environmentally friendly product design throughout the entire process was confirmed, and the product design process is divided into seven phases, with necessary actions for each step. Next, specific measures for material design for environmentally friendly product design are presented, and the design of the wall of an energy-efficient house using solar energy is used as an example of material design. Based on the "1DCAE" concept, design conditions and goals are determined, and materials are designed to achieve the goals. The material design results obtained are discussed from the viewpoint of environmental evaluation. It is shown that ideas generated by environmental considerations can create even more significant business opportunities.

After the huge earthquake many steel structures were constructed using frame welded joints of welded construction and welded base. Steel structures are considered earthquake resistance structures however, many steel structures are constructed using frame-welded joints of fillet welded construction and welded column bases. These weld joints could result to have low capacity to absorb energy during earthquakes. In this paper, we have proposed the development method for sensor measuring displacement by using composite piezoelectric film and glass. We are investigated relationship between the displacement of the structure and the output voltage from the piezoelectric joint sensor to recorded the sensor characteristics.

Battery energy storage systems (BESS) using lithium-ion batteries (LIB) are required for storing electric power derived from renewable energy sources. The system consists of many components such as cells with thermal runaway (TR) risk, parameter sensors, and cooling units. In addition, these components have relations with each other. Therefore, the system can cause a large-scale fire or explosion due to failures of the relation between system components including the TR propagation through cells. For the safe design and operation of BESS, international safety standards recommend a system-level risk analysis that considers these characteristics and hazards of BESS. However, the system-level risk analysis is difficult by using document-based qualitative methods described in the standards because the methods can’t consider the characteristics of BESS well. Therefore, this study focused on development of a risk analysis method using 1D model, which can model relations between system components, and aimed to identify system-level risk scenarios caused by combined failures. To identify the risk scenarios by combined failures, we constructed a battery module model and failure models using the 1D model. From the calculation result of the cell temperature profile, we determined whether to occur TR in the case of assuming combined failures. In conclusion, the developed method can identify risk scenarios and combined failures that cause TR.

Battery energy storage systems (BESSs) consisting of lithium-ion batteries (LIBs) are being increasingly used to supplement the unstable electrical power derived from renewable energy sources. As stipulated by the International Electrotechnical Commission, BESSs must be assessed for any risks, including thermal runaway (TR) and thermal runaway propagation (TRP), at the module level as well as the final system level. Several studies have focused on the hazards and risk assessments (RAs) of BESSs; however, the assessment of system-level risks is challenging due to complex system-level interactions in BESSs, which involve multiphysics and dynamic phenomena. Therefore, we have focused on using 1D model, which can model multiphysics system-level interactions between system components in multiple physical domains. This study aims at a quantitative analysis of the effectiveness of thermal insulations for the prevention of the TRP scenario that a TR of a LIB propagates to other adjacent batteries as one of the high-risk scenarios in a battery module. To estimate the frequency of the scenarios, we applied the model which was able to predict the temperature profile of individual batteries in a battery module. The probability of TRP occurred in a battery module was estimated via the TRP occurrence rate by Monte Carlo simulations using the 1D model, which considers the probability distribution of the design parameters of individual LIBs or the components of a BESS. As a result, it was possible to conduct a quantitative analysis of the effectiveness on reducing the probability of a TRP scenario due to model changes.

In this study an oscillating water column device utilizing a double slit breakwater is focused. Former research clarified that the oscillating water-column wave generator installed in a double-slit breakwater has qualitative characteristics similar to those of a two-degree-of-freedom vibration system in which the water column in the slit playroom is considered the mass point. In order to simulate these characteristics as a superposition of modes, the modal damping ratio, eigenangular frequency, and mode amplitude ratio are obtained. For this purpose, free vibration experiments were conducted on a power generation system, parameters were identified using variational mode decomposition, and simulations were performed from these parameters to reproduce waveforms similar to the experimental results.

Breakwaters protect beaches by absorbing wave energy. Double-slit breakwaters can be used as air chambers for oscillating water column wave energy converters. In this study, the oscillating water column-type wave power generator using the double-slit breakwater was treated as a two-degree-of-freedom oscillating system model. The differential equations of motion were derived from Newton's second law, and the frequency response characteristics of the vibration of the oscillating water column- type wave energy converter using the double-slit breakwater were investigated using Simulink in MATLAB.

Purpose of this study is to establish a technology for machining cemented carbide with high efficiency and high precision with vertical face grinding using a cup type electroplated diamond grinding wheel. Face grinding experiments were conducted on workpieces using two types pf grinding wheels which have different grinding fluid supply methods, and the grinding force distribution was obtained to evaluate the grinding performance. The grinding force distribution is obtained by the successive differentiation of the grinding force, in a rising up section, when the grinding wheel momentarily starts to interfere with spark-out surface, which has the pressure dimension. As the grinding length increases, both the amount of workpiece adheres to the grinding wheel surface and the grinding force increases, while the surface roughness becomes smoother. As the grinding progress, peak position of the grinding force distributions are almost the same. Both the workpiece adherence and grinding force are smaller and the surface roughness is better with the working surface spouting wheel, indicating that this is an appropriate grinding fluid supply method.

Online monitoring of tool and chip removal conditions during cutting operations is required to improve productivity at the production site. This paper proposes a low-cost and highly reliable cutting force measurement method using a semiconductor strain sensor mounted on a rotary tool holder. In a previous study, it was shown that an abnormality such as tool breakage can be detected from the output of a strain sensor attached to a tool fixed on a lathe. In this study, two wireless systems were developed for supplying power to the sensor and communicating with it, and was applied to monitoring the drilling process. The experimental results showed good agreement between the strain sensor output and the output of a commercial cutting dynamometer in the drilling process. FFT analysis of the sensor output showed that chipping and breakage of the drill could be detected.

This study presents a novel method for estimating the surface integrity in end-milling. The mechanical properties of the machined surfaces in cutting affect the quality of the final product. In particular, hardness and residual stress often require strict control, but nondestructive inspection is not easy. This study proposes a method to estimate the hardness and residual stress of end-milled surfaces by analyzing the cutting forces measured on the machine and the tool image. The measured cutting force is analyzed to estimate the specific cutting forces and edge force coefficients. The flank wear width is measured using an on-machine measuring device installed in the machine tool. From this information, the average stresses at the primary and tertiary cutting zones are estimated. The cutting temperature in the primary cutting zone is roughly estimated by considering the shear angle theory. These state quantities are highly correlated with the dislocation density and its change on the machined surface. Therefore, hardness and residual stress are estimated based on a simple linear regression model. Parameter identification was performed based on measured hardness and residual stress in end milling experiments. The experimental results validated that the proposed method can accurately estimate hardness and residual stress.

Additive manufacturing (AM) is a technology that enables the molding of complex shapes from 3D data. Laser powder bed fusion (L-PBF) is one of the AM techniques for manufacturing metal parts. The purpose of this study is to investigate how varying the particle diameter of the material powder affects the surface roughness of the side skins of parts produced by L-PBF. Specimens of different materials were incorporated using stainless steel and maraging steel. The specimens were conducted with twice contour passes. The surface roughness of the specimen side skin was measured in the laser energy density on 1.0, 1.5, 2.0 and 2.5 J / mm2 of the second offset contour path. Results showed that average roughness tended to decrease with contour energy density for both specimens of different species. There was no difference in the average surface roughness for both specimens of different species. However, the specimens made of stainless steel had fewer voids observed in the contours of the specimens than the specimens made of maraging steel.

Light absorption depth of glasses in a mid-infrared wavelength of 2.8 μm is the same scale as thickness of glass plates used in flat panel displays. Such an absorption property allows relatively uniform heating in the thickness direction of glass plates when a mid-infrared laser is irradiated vertically to the glass plate surface. Therefore, the mid-infrared laser is convenient for edge rounding of complex shape glass plates. Application of the mid-infrared laser to the edge finishing process has been developed. However, residual tensile stress in rounded edges which weakens final products has been a problem to be solved. Simultaneous assist laser irradiation with the mid-infrared laser rounding is a candidate solution because of its controllability of residual stress. In this study, residual stress control has been examined by high-frequency reciprocal scanning assist laser irradiation. In addition, relationship between residual stress and assist heating width has been investigated by numerically and experimentally. Existence of an optimum assist heating width which minimize residual stress was confirmed. Both increase and decrease in assist heating width from the optimum width increased residual stress.

Spiral groove shape machining is possible by wire electric discharge machining with the addition of a rotary axis. Furthermore, by adding a two-axis rotary axis that can rotate and tilt, we have performed spiral groove machining that changes the groove width. The combination of the rotation direction and the tilt direction determines whether the groove width becomes narrower or wider. The previous report was a process in which the groove width was widened by forward rotation and downward tilt. At that time, we compared and examined the machining accuracy of the NC program generation method. In this report, machining was performed with the remaining three types of combinations of rotation and tilt, and the shape accuracy was compared along with the difference in NC program. In all the results, it was found that the groove width tends to be widened on the entrance side of the groove machining, and the groove width becomes closer to the design shape as the machining progresses.

One of aims in our laboratory is to develop a curved hole electrical discharge machining (EDM) system by means of a microrobot. Three units constitutes the microrobot, i.e., autonomous EDM unit, machining direction steering unit, and in-pipe self-mobile unit. These units have been developed separately in our previous studies. These respective studies have developed the autonomous EDM unit which employs shape memory alloy (SMA) as its actuator and the machining direction steering unit which consists of a helical compression spring and wires whose respective posture and feeds are controlled by linear actuators. So, this study has developed the device combining these two units which makes the device fabricate a curved hole. The experiment result shows that the developed device has the ability to fabricate a curved hole.

Deep drawing, which is one of the pressing processes, is a processing method suitable for mass production because there are few manufacturing processes. Therefore, it is used in industrial products such as motor cases and fuel tanks, and daily necessities such as aluminum beverage cans and cooking pots. In recent years, there has been a demand for improved functionality of the cup itself in products made by deep drawing. The development of new processing methods and the establishment of processing using alternative materials are progressing. On the other hand, titanium, which is a kind of light metal, is expected as a next-generation material because it has excellent properties. Pure titanium is relatively ductile at room temperature and has excellent corrosion resistance, so it is used in heat exchangers and chemical plant components that come into contact with corrosion media. In the present study, to make a lightweight and functional cup, we tried to form the titanium clad cup with voids like the cross section of corrugated paper. The unique die with a steel ball attached to the shoulder of the die was combined with a normal die for deep drawing. The formability of the clad cup and the adhesiveness of the clad cup were investigated. By properly adopting the gap between the die and the blank with respect to the thickness of the blank sheet, it was possible to form the titanium paperboard cups with excellent stretchability.

Metal matrix composites (MMCs) show a unique improvement in metal materials properties such as high specific strength enabling their use in various applications. Additive manufacturing (AM) allows production of complex or customized parts directly from the design without the need for expensive tooling or forms such metal molds and reduces the need for traditional MMCs processing method. Uniform mixed powder is important for producing MMCs. Although ball mills have been used in previous studies, there are problems with the length of the mixing time and the uniformity of the powder, and it is necessary to study the mixing method. Therefore, this study investigated the production of SUS316L/Al2O3 mixed powder for L-PBF using the dry impact blending method that is a method in which material powder is dispersed in a high-speed air flow and the powder is mixed by mechanical impact force. A composite powder was produced with a mixing time of 60-900 seconds for SUS316L powder weight : Al2O3 powder weight were 1 : 0.4 as a theoretical compounding weight and 1 : 0.4 as a theoretical compounding weight of 25%. As a result, it was found that a powder suitable for L-PBF with a single peak particle size distribution was produced in performed for 300 seconds or more with a theoretical composition of 25%.

Plastic is a material for which resource circulation should be strongly required, and the replacement of virgin materials with recycled materials is accelerating. Controlling the viscosity of molten resin is important during material changes in the injection molding process. In this study, the technology to extract the feature quantities that correlate with resin viscosity by using an in-mold sensor has been developed to expand the application of recycled materials. Several feature quantities were extracted from pressure sensor data. By evaluating the response of those features to changes in the temperature of the molten resin, the integral value of the pressure from the start of injection to the peak time was clarified to have the highest validity. It was confirmed that there was a positive correlation between the selected feature quantity and measured viscosity by a capillary rheometer, and that it represents differences in intrinsic viscosity between resins.

Magnesium alloys are increasingly being used in the field of transportation equipment, such as automobiles and aircraft, where energy saving is being promoted. However, the problem with magnesium alloys is that they have lower corrosion and wear resistance than steel materials. Therefore, a lot of research on alloy development and surface modification has been attempted. In the present study, to improve the corrosion resistance and wear resistance of magnesium alloys, dissimilar materials were joined using shot peening. Using a cast steel projection material having a diameter of 1 mm, the projection was performed at a projection speed of 60 m / s and a processing temperature of 300 ° C. The base alloys are AZ31, AZ61, AZX611, and AZ91D. The dissimilar material was an aluminum laminated material containing ceramic powders and a heat-resistant resin sheet. The ceramic powders were alumina and zirconia, with a particle size of 0.1 to 0.3 mm. Resin was a sheet of polyimide, with a thickness of 0.025 mm. The joinability was determined by microstructure observation and bending test. The three-point bending test destroyed the joint surface, but did not cause peeling of dissimilar materials from the substrate. It was also found that wear resistance was improved by joining hard dissimilar materials.

Tricalcium phosphate/poly(lactic acid) (TCP/PLA) composite is attracted the attention as a material of bone fixation device because it doesn’t require removal by reoperation after healing bone fracture. However, mechanical properties of TCP/PLA composite were low. In this study, effect of draw ratio (DR) on mechanical properties of drawn TCP/PLA composite was investigated to improve the mechanical properties. Orientation function of drawn TCP/PLA composite was investigated to clarify mechanism of changing mechanical properties by drawing. As a result, tensile strength was improved with draw ratio up to DR 2.5. Tensile strengths of drawn TCP/PLA composite up to DR 2.5 were higher than that of PLA. Elastic modulus was improved with draw ratio up to 2.0. Orientation function of α form crystal was improved with draw ratio up to 2.0. From these results, it was suggested that increase mechanical properties of drawn TCP/PLA composite due to orientation of α form crystals.

The texture of springs is related to fatigue, creep, and especially strength. We investigated the microstructure in order to clarify the changes of the texture during the manufacturing process of the springs, and to contribute to further strengthening of springs. In this study, we simulate the texture produced by drawing and coiling wires in the spring manufacturing according to the predictive theory of crystal rotation based on Katoh's theory, which is based on the theory of Taylor et al. Also, we observed the crystal structure of the drawn and oil-tempered wires by electron backscattering diffraction (EBSD), and it was observed that the axial direction of crystal orientation rotates toward <110>. This result follows the predicted ones. Next, in order to predict the crystal direction rotated by coiling, we used finite element analysis (FEM) to identify the plastic strain generated during the coiling process, and input them to that theory for crystal rotation. The results show that the axial crystallographic orientation <110> relaxes on the outside of the wire cross section and also, while on the inside, the orientation accumulated around the crystallographic orientation <110> on the inside during the coiling process.

Metal bone fixation devices are used in the treatment of bone fractures. However, metallic materials cause inflammation in the body. In this study, we focused on bioabsorbable composite material of poly(lactic acid) (PLA) and tricalcium phosphate (TCP). However, the mechanical properties of TCP/PLA composites are lower than those of metal materials. In order to improve the mechanical properties of TCP/PLA bone fixation screws, molecular orientation by extrusion die forging was focused under various extrusion ratios (ER) and TCP contents. The orientation of molecular chains depends on the forging conditions. The purpus of this study is investigation effect of forging condition on mechanical properties of TCP/PLA scres. Then, screws were formed by extrusion die forging at ER 1.3, 4 and 8, and shear strengthe of the screws was measured. As a result, the shear strength increased with ER, and the maximum shear strength was observed at ER 4.

As the next generation of smart devices, many stretchable devices with have been developed. In this process, it is necessary to fabricate stretchable substrates and electrodes. However, in many studies, stretchable devices are currently manufactured by hand. Considering future social implementation, it is important to realize a mass production process for substrates and wiring. In this study, we conducted a PoC of a mass production process for stretchable devices by combining a substrate fabrication process by Roll-to-Roll (R2R) and a liquid metal wiring fabrication process by dispensing. To realize this process, we assembled a new R2R system by incorporating a slot die coater and applicator, which is the R2R coating process, and a corona treatment system to improve the wettability of polymeric materials into the R2R process equipment. Using this equipment, we evaluated the device at 50% elongation and fabricated a large scale stretch device.

Magnesium and aluminum alloys are widely used in various industries owing to several attractive properties such as low density, high strength to weight ratio and reusability. However, magnesium alloys and high-strength aluminum alloys have undesirable properties including poor corrosion resistance and wear resistance. Therefore, surface modification is necessary to improve such properties of those alloys. In the present study, the high-corrosion resistance foil was joined to the surface of alloys using shot peening. The base materials were a commercially available magnesium alloy and aluminum alloy, and the high-corrosion resistance foils were pure aluminum, pure titanium, pure copper, pure nickel, pure iron and austenite stainless steel. The thickness of foils range from 0.02 to 0.06 mm. Shot peening was performed with a centrifuge equipment. The shots had an average diameter of 1.0 mm and were made of cast steel. The peening velocity was 60 m/s, and the peening time was 10 s. The processing temperature was 300 and 350 ℃ to facilitate plastic deformation. No voids and cracks were observed at the bonding interface. In bending test, the metal foil did not peel off even when the substrate was broken, and the metal foil was tightly bonded.

Stainless steel is known as material with high corrosion resistance, and has excellent mechanical properties, workability, heat resistance. Therefore, it is used in a very wide range of fields such as mechanical parts, building materials, chemical parts, aviation parts, medical equipment, and food supplies. On the other hand, along with stainless steel, pure titanium is also known as material showing extremely high corrosion resistance. It has been used for a long time together with titanium alloys as chemical plant and heat exchanger. Pure titanium, which is widely used as a product, is JIS2 type. However, the problem is that the strength of pure titanium is lower than that of titanium alloys. Therefore, it is expected to use pure titanium having high strength while maintaining purity. Generally, cold working and heat treatment methods are used to increase strength. In the present study, the material properties of pure titanium were improved by a combination of cold rolling and heat treatment. Mechanical properties were examined by tensile testing. The test material was a commercially available pure titanium JIS2 sheet. The thickness of the tensile test workpiece was 0.4 to 0.7 mm. The rolling reduction ranged from 75 to 93 %. An increase in tensile strength was obtained in the heat treatment from 400 to 500 oC while maintaining the ductility. Tensile strength was greatly improved under the condition of 93 % of rolling reduction and heat treatment temperature of 400 oC.

Warm processing was performed by frictional heat generation between different materials installed inside the punch. Forming with press machine is a technology for processing materials by applying heat and force, and is an important technology for industrial machines such as automobiles and electronic devices. For light metals such as aluminum alloys and magnesium alloys, it may be difficult to form depending on the type of alloy in cold deep drawing. As a method of improving formability, warm working is performed in which the metal die heated and deep drawing is performed. However, warm working requires many control devices such as heating and cooling for the mold. Using a prototype punch with a built-in friction heat generation jig, friction heat was generated by combining several types of steel materials. The changes in the exothermic temperature were mainly investigated in the combination of different materials. The test materials were carbon steel, tool steel, and stainless steel. The heat generation temperature generated by friction was measured by a thermocouple installed inside the heat generation jig. The friction surface of the jig after frictional heat generation was observed by a microscope. In frictional heating, the temperature of the processed area reached more than 350 °C in a few minutes. The proposed method was able to heat the punch. After frictional heating, the load of deep drawing of pure aluminum sheet decreased. It was found that there is a possibility of improving workability by warm deep drawing.

Most of the previous studies on waterjet cutting have been limited to abrasive waterjet cutting, which can cut even hard materials such as metals using water mixed with abrasive. In this study, experiment to cut soft materials such as PVF, EVA using low-pressure water without abrasive was conducted. A desktop waterjet cutting machine was fabricated and a circular sample was cut out. To improve the kerf quality, roller jigs which hold a workpiece was attached to the nozzle section. The stronger the rollers are pressed against the material, the more accurate the cut-out of material becomes. This is because the undesirable material deformation caused by traverse of the jet was suppressed by pressing the rollers against the material.

The thermal deformation of machine tools often reduces their accuracy. Therefore, we have been trying to compensate for the thermal deformation by predicting their variations and adjusting the position of the tool according to predicted values. The prediction equation of the thermal deformation in the CNC lathe is determined by measuring the temperature variations at a few specific points of the machine. In order to obtain such coefficients with a few experiments, the previous study has used an orthogonal array to determine the experimental condition. However, orthogonal arrays have specific patterns, so it cannot create the flexible condition. This study attempts to use All pair method for determining the prediction equation more efficiently, which is normally used in software testing, it can make testing patterns have all combinations of all parameters in a few experiments. Although all pair method is not widely used in the mechanical experiment, its effectiveness is confirmed.

In the manufacturing field, various types of machine tools are widely spread and used. However, machine tools have mechanisms that rotate at high speed, generate heat, large forces which can be dangerous for inexperienced users. Therefore, safe training system is required. Virtual reality (VR) is inexpensive compared to machine tools and can provide an immersive training environment for a large number of trainee. In this study, we developed a training system for machining in a virtual space for a desktop machine tool. Furthermore, in order to realize the digital twin, the behavior of the actual machine and that of the virtual machine can be synchronized using TCP/IP, and the behavior of the table of the actual machine can be monitored.

In order to add a palpation function to a surgical robot, we developed a micro forceps mechanism driven by hydraulic pressure. Therefore, viscoelasticity modeling of the measurement target was investigated using the micro-forceps mechanism, and viscoelasticity measurements of an arteriosclerosis model were performed. Arteriosclerosis can be roughly divided into arterial narrowing, lipid content, and arterial stiffening. Plaque composed of fat causes narrowing of blood vessels, and the amount of lipid in the plaque determines whether the plaque fails or not. Therefore, we created a model that varies the degree of stenosis and the amount of lipid with reference to the characteristics of atherosclerosis, and measured the viscoelasticity of changes in arterial stiffness. As a result, the superiority of the three-element Maxwell model and the difference in viscoelasticity in each experiment of the arteriosclerosis model were measured.

In recent years, demand for UAVs has been increasing in various situations such as aerial photography, infrastructure inspections of bridges, and logistics. In this study, we focus on bridge inspections in non-GPS environments and propose a measurement method using a projected marker and camera that enables self-position estimation. This measurement method aims to solve the problem of the large measurement error of position and posture as the shooting distance increases by using "laser parallelism correction". Experiments were conducted using a measurement unit consisting of a laser pointer, a camera, and a projection plane, and image processing software was used to analyze the captured images. The experiment was conducted by measuring the position of the projection plane at several shooting distances and changing the posture of the projection plane at each shooting distance to measure the posture. As a result, we succeeded in reducing the measurement error, which had been a problem in previous studies, by using laser parallelism correction, and confirmed the effectiveness of this method.

Swarm robotics is one of the research field that uses a large number of simple autonomous robots and is expected to be applied to various operations in uncertain environment such as exploration activities at disaster sites. In this research, the task is to search a larger area along the way while the Boid-based swarms move together in an environment with obstacles. In a homogeneous swarm, all individuals move in a similar manner, often resulting in low exploring performance. Therefore, we generate a swarm by setting the collision avoidance distance of each robot from other robots to be heterogeneous with different advantages of following, spreading, and examine the effect of individual differences on the search performance. The results show that swarms with larger differences among individuals can improve search performance.

Bin picking is a parts handling process in factory production lines. There are various challenges in automating bin picking. In particular, the more complex the object shape is, the more difficult it becomes to recognize the position and posture of the object using a camera and to determine the appropriate position and posture of the end-effector. Using a Convolutional Neural Network (CNN), a deep learning technique for image recognition, the characteristics of the grasping objects, and grasping with a high success rate would expected. However, due to the limited number of simulation trial, the estimated position and posture is not always the optimal grasping posture. In this study, we modify the position and posture of the end-effector for handling robots using deep learning. Several candidates for position and posture of the end-effector are estimated using three types of CNNs. For each candidate for position and posture of the end-effector, the actual grasping position is determined using the balance between the estimated grasping possibility and the posture of the end-effector. Experimental results showed that integration of the CNN result and posture of the end-effector improved grasp success rate.

Life support robots are expected to reduce the physical burden on caregivers. By synchronizing the physical rhythm of the caregiver and assisted person, the caregiver gives the assisted person a sense of safety and security. It has also been reported that physical rhythm is also important in embodied interaction between humans and robots. Therefore, we propose a human-like sit-up motion model based on the analysis of human movements. In the experiment, we measure the sit-up motion of the caregiver and assisted person. Optical and magnetic motion capture and microphones were used during the measurements. Then we formulate the neck position and the shoulder posture of the assisted person. During the formulation, two types of waveform patterns were observed. Therefore, the waveform patterns were classified as mountainous-shaped and s-shaped, and applied to the motion model. In addition, we verified that the upper limb movements by the proposed model are similar to those of a caregiver.

In recent years, it is expected to use robots that support humans in medical care and living support. In places where robots and humans live together, there are situations where robots have to contact humans. In this cases, it is necessary to clarify how humans feel and what kind of movement characteristics they prefer due to the movement of robots, Therefore, in previous studies, it was shown that the movement characteristics that humans prefer differ in contact and non -contact movements. In this study, the development of a high five motion model, which is the base for robot movements, was developed. In order to develop a motion model, we first analyzed the movement of the elbow joint at the swinging when humans high five. The obtained elbow joint velocity pattern suggested that the mini mum jerk models could be used. Then, the starting angle, end angle, motion time, and peak position required for the minimum jerk model were analyzed. As a result, the distribution of parameters required for movement generation was analyzed. In addition, it was shown that the movement of the elbow joint has a significant effect by distance.

Human tears have an effect as an empathic signal that visually conveys evoked strong affects or emotions to them. We focused on human tears as an expression method with strong affects or emotions and developed a teary-eyed robot called Tearoid. Tearoid has the structure of mimicking human lacrimal apparatus and generates the teardrops by controlling the inflow of tears. However, the affect displays of the kinds for the teardrops with various affects or emotions were not examined so far. Therefore, if the robot’s affects or emotions can be inferred from various teardrops, it becomes a new empathic expression for humanoid robots. In this study, we proposed new affect displays that enhance affective expressions by adding color to the teardrops that flow into the Tearoid. It was confirmed that the colored teardrops express various affects or emotions even if the facial expressions do not change.

Infrastructure facilities have been deteriorating and require a vast number of inspections conducted by skilled engineers. Inspection robots are required because of a shortage of skilled engineers. In order to improve the inspection efficiency of outdoor infrastructure facilities, an omni-directional mobile robot that can move freely in all directions has been investigated. However, it is necessary to design a vibration isolation mechanism because the accuracy of the positional inspection of underground objects is adversely affected by vibration in an outdoor environment. We have constructed an experimental setup to evaluate the vibration properties of the wheel. The acceleration characteristics due to the difference between the direction of movement and the speed of the omni-wheel have been evaluated. It was confirmed that periodic vibration occurred by each moving direction of the Omni wheel.