In this study, the effect of parameters such as the clearance between the bearing inner diameter and the shaft diameter, and the clearance of the water supply slot on the load capacity was investigated using both experimental and CAE analysis approaches with a small-diameter hydrostatic water lubricated bearing. It was found that a specific slot clearance maximizes the load capacity for a certain radial clearance, the flow rate increases as the slot clearance increases, the load capacity is proportional to the eccentricity ratio and pressure, and the flow rate is proportional to the pressure.

Silver plating is characterized by high wear resistance, lubricity, and conductivity, and is used for plug components. However, considering the use of silver plating laminated with other materials, it is necessary to evaluate and study the wear resistance of these materials in combination. In particular, if wear occurs in plug parts, it could lead to equipment failure. In addition, since silver is expensive, wear needs to be reduced, and it is predicted that the demand for components such as terminals will increase in the future due to the recent trend toward EVs. These factors make it necessary to develop a test method for the wear mechanism of silver plating. Therefore, the purpose of this study is to examine whether it is possible to evaluate the plating film from acoustic emission (AE) signals and in situ observations during wear by attaching an AE sensor to both test specimens and observing the moment of wear with a friction surface microscope.

For the purpose of decommissioning the Fukushima Daiichi Nuclear Power Station, a technology was developed to survey the inside of the reactor pressure vessel using existing piping. Since there is a check valve on the piping route that obstructs the progress of the survey equipment, a check valve processing equipment was prototyped to secure the flow line by processing the valve body. The equipment travels inside the pipe by pressing the crawler module against the inner surface of the pipe with a spring and uses an abrasive water jet cutting method to process the valve body. A movement test in the pipe and a check valve cutting test were performed on the prototype device. In the movement test in the pipe, a stuck occurred due to interference with the pipe weld marks and jamming caused by the abrasive sub-tank being towed occurred. Therefore, measures such as controlling the inner wheel difference and devising the towing direction are necessary. In the check valve cutting test, it was found that the sticking of the sliding parts due to the entry of abrasives and the accumulation of abrasive inside the valve box hindered the operation of the equipment and securing the flow line. Therefore, it is necessary to strengthen dustproof measures of the equipment and to clean the abrasive during cutting. Various measures will be implemented to address the issues identified in these evaluations, and development will continue towards practical application.

The equation of motion for an undamped, coupled free oscillation is a set of second-order ordinary differential equations (ODEs). A well-known technique to obtain the general solution of the equation involves transforming the original second-order ODEs into a set of first-order ODEs and using a corresponding resolvent matrix that has twice the order of the number of the original ODEs. In this study, we propose two new resolvent matrices, each of which has the same order as the original second-order ODEs, thereby reduces the computational cost compared to handling the conventional resolvent matrix. Moreover, the solution, expressed using these matrices, is in the form of a superposition of oscillation modes, and becomes more physically comprehensible.

An underwater laser scanner is installed on an underwater vehicle, which irradiates lasers to the seabed while the vehicle is traveling and detects and processes the optical reflection from the seabed, thereby the deep seabed is visualized in detail. This method is one of most effective to understand the seabed condition including seabed topography. Therefore, two types of underwater laser scanners equipped with difference wavelength of laser sources, for visible wavelength and for invisible wavelength, were newly developed. The seabed reflections for different laser wavelength of each scanner might be able to visualize different seabed image which express different condition and phenomena even though a visualization target is completely same. Moreover, those scanners generate two kinds of seabed images at the same time using the round-trip propagation time of the laser and the seabed reflection. This paper describes the configuration and elemental technologies of the underwater laser scanners, and shows performance tests in actual deep-sea areas.

While axial piston pumps are broadly used in hydraulic systems, radial piston pumps are also employed in suitable applications. Due to their configuration, radial piston pumps can offer advantages for generating high hydraulic pressure. They are particularly valued for their ability to generate high pressure. In this study, a preliminary experiment was conducted to study the behavior of the bearings of the radial piston pumps of a specific configuration. The experimental apparatus was created as a simplified pump, constituted with one piston-cylinder pair and crankshaft. Various sensors are prepared to measure the necessary physical values of the bearings during operation. In this report, the crankshaft has no eccentricity as an initial step. With this experimental setup, supply pressure and shaft rotation speed were varied to acquire data. As an illustrative example of the analysis findings, the obtained clearance distribution in the bearing confirmed the presence of both static pressure effects, and dynamic pressure effects corresponding to the shaft's rotation speed. The average clearance in the bearing correlates to the lubricant flow rate in the bearing.

A decline in walking function causes great inconvenience in daily life. Walking function is essential to maintain quality of life. Walking is made possible by the coordinated movements of various parts of the body, including the leg joints. In particular, the movements between the joints of the legs are directly related to each other. In this study, the authors have been developing a walking assistance device that focuses on the coordinated movements of the legs. It is considered that a functional relationship exists between the angular displacements of the hip joint and the knee joint is established during walking, and the function generating mechanism using a planar six-link mechanism is synthesized. A specific rotation axis of the mechanism is attached so that it is coaxial with the center of rotation of the hip joint and the knee joint, and the functional relationship generated by the mechanism promotes the coordinated movement between the joints of the human leg. It is verified whether the device enables mutual assistance between the human legs is possible during walking. From the data provided by National Institute of Advanced Industrial Science and Technology (AIST), the functional relationship between the angular displacement of the hip joint and the angular displacement of the knee joint is obtained, which is referred to during design. The function generator using a planar six-link mechanism is synthesized while comparing the generated data with the reference data. The device is prototyped and the effect of the device is verified using the subject's myoelectric potential. In some muscles, changes such as increases and decreases in myoelectric potential are observed when the device is used, which is suggesting the possibility of mutual support.

The purpose of this research is to develop a device that can continuously supply PTFE fine powder. Although PTFE is used in a wide range of fields due to its excellent chemical, mechanical and electrical properties, it is difficult to continuously feed non-granulated PTFE powder due to its low flowability. Some of the authors had developed a device that enables highly accurate automatic quantitative feeding of PTFE fine powder in the previous paper. In the present report, the authors have developed a device for supplemental feeding to the hopper of the highly accurate automatic feeding device. The new feeding device is designed so as to lift powder by a movable bottom plate of a straight hopper and to push out the lifted powder by scraping. By adjusting the lifting height based on the difference in bulk density by position of the powder from the top to the bottom in the hopper, the system is able to continuously feed the powder with an accuracy of ±1 g. The proposed method which is composed of lifting up and scraping motions works well for initial feed of 15g and 33 times feeds of 3g. No agglomeration is observed in the supplied powder by the feeder.

Mechanical components that are subjected to repeated temperature changes are often required to evaluate thermal fatigue causing initiation and propagation of cracks. However, because the procedure for evaluating thermal fatigue is complicated and because thermal fatigue tests are expensive to conduct, there are very few examples of experimental verification of thermal fatigue evaluations based on finite element analysis. In this study, we have tried verification and validation of thermal fatigue analysis by evaluating previously conducted structural model thermal fatigue tests. A simplified method based on the stress relaxation locus method and elastic FEA was compared with the previously performed elastic-plastic FEA.

We propose a robot that meets the requirements of flexibility and scalability to handle a variety of tasks, and the ability to work effectively in constrained environments. In this study, we describe a framework for a multi-degree-of-freedom, multi-functional modular robot, focusing in particular on the development of a differential module, an actuator module that generates force and motion. The proposed modular robot is realized by directly connecting each module, with a flexible, slender snake-like body and a string-like structure with expandable joints, taking into account environmental adaptability. The string-like robot has high running performance and can handle not only narrow spaces but also gaps such as rubble. The specific tasks of this robot are "3D movement, monitoring, and measurement," and since it is expected that the robot cannot be seen directly, it is operated in real time using a remote control interface. In this paper, we describe the results of fabricating the differential module. We briefly summarize the characteristics and functions of the fabricated module, and also mention how it can be used and applied in future research. Our goal is to show the first step toward realizing the modular robot we propose.

We developed a module that can be used as a leg for an uneven terrain mobile robot, and the 4-axis differential module consists of two types of differential mechanisms.This configuration made it possible to concentrate and distribute power to four output shafts with a limited number of actuators, saving space in the module and enabling high output at each output shaft.In addition, since this module can perform four operations of driving, steering, linear motion, and tilt at the same time, it is possible to generate different vectors in the same direction between the x-axis vector generated by driving and steering, and the x-axis vector generated by linear motion and tilt, creating redundancy in the movement.The four operations of drive, steering, linear motion, and tilt were performed with the created 4-axis differential module, and the operation was confirmed from the output power of the motor. The operation of the drive and steering was confirmed as expected, but it was found that there is room for improvement in the linear motion and tilt. From the above results, it was possible to use it as a leg module for an uneven terrain mobile robot.

Tribological properties of soft metal thin film containing fine zinc oxide (ZnO) powder coated on pure aluminum (A1070) disc was evaluated with a ring on disc type testing method mated with a quenched carbon steel ring in lubricated condition. The soft metal film consisted of zinc (Zn) and tin (Sn) coated on the aligned bump textured disc surface to obtain heterogeneous film structure. ZnO powder was penetrated to soft metal film using a powder deposition process. Results of the friction and wear showed that a significant decrease of the friction resistance was found in the bump textured disc without soft metal film. Further reduction of the friction resistance was obtained in the soft metal film and ZnO penetrated soft metal film. Effects of the soft metal film including ZnO powder on the decrease of the friction coefficient and the wear loss was discussed based on the restriction of the junction growth at the interface.

We have developed a telepresence robot that is designed for use in exhibition halls that are expected to be crowded. In addition to video chat functionality, the robot is equipped with a soft arm capable of replicating tactile gestures such as handshakes and operator movements, thereby facilitating smooth communication even in remote locations. This paper describes the conceptual design of the robot, the structural framework of the arm and the theoretical equations underlying its functionality. In the arm motion analysis test conducted to evaluate the validity of the theoretical model, the theoretical position of the arm's tip closely matched the measured values, confirming the accuracy of the model given the intended use of the arm.

In recent years, technological developments have been progressing to utilize ammonia as a carbon-free fuel. Ammonia has the advantage of being able to use existing infrastructure technologies for storage and transportation, but it is a corrosive substance. Therefore, materials used in the operational environment of ammonia fuel require corrosion and wear resistance. The application of DLC (diamond-like-carbon) coating, which exhibit excellent chemical stability and wear resistance, is highly anticipated in this context. In this study, friction tests were conducted on a-C:H coating in high-temperature, high-pressure ammonia water using an autoclave-type high-temperature, high-pressure friction test machine that can simulate the operational environment of the fuel. The results showed that the wear amount of the a-C:H coating increased with the concentration of ammonia water. To clarify the cause, AES analysis and AFM nano-scratch tests were conducted. The results suggested that the increased wear was likely due to softening caused by oxidation of the film's outermost surface.

In this study, I investigated the mechanisms for improving the seizure resistance of nitrocarburizing, sulphonitriding, and oxynitriding steels, which are known for their excellent seizure resistance. The aim was to derive design guidelines for further seizure-resistant surface treated steel materials. A roller-on-disk friction test and surface analysis of wear scars using SEM/EDS were conducted to evaluate seizure resistance from the perspectives of friction coefficient, surface pressure, adhesion resistance, and frictional heat generation. As a result, it was revealed that sulphonitriding steel showed the most significant friction reduction effect, reducing friction by 23% compared to carburizing steel under ATF lubrication. EDS analysis revealed that sulphonitriding and oxynitriding steels exhibited superior adhesion resistance compared to nitrocarburizing and carburizing steels. Additionally, the frictional heat generation was calculated from the friction coefficient and surface pressure. This revealed that sulphonitriding steel generated less frictional heat compared to other surface treated steels, suggesting that sulphonitriding steel has superior seizure resistance compared to other surface treated steels.

To achieve further improvement in EV energy efficiency, the size and weight of E-axle is being promoted to decrease. For the trial of decreasing the size and weight of E-axle while maintaining the conventional power of transmission, higher rotation speeds of gear are necessary. However, the number of contacts between gear tooth flanks increases; therefore, in the E-axle, fatigue wear, such as pitting, will increase. As a conventional method to improve fatigue wear resistance, heat treatment has been widely used for a long time. Especially, carburizing is the mainstream heat treatment for gear surfaces. Carburizing is the main heat treatment for tooth surfaces, but it is known that as the sliding speed increases and the frictional heat increases, the amount of wear increases because the base material is softened by tempering. Therefore, gas nitrocarburizing treatment, which shows excellent wear resistance even in the high sliding speed range, is attracting attention. In this study, rolling fatigue friction tests were performed under different conditions of slide-roll-ratio (SRR) load and specimen heat treatment to evaluate fatigue wear resistance and investigate its mechanism. The damaged area percentage (DAP) of carburizing and nitrocarburizing specimens increased and decreased as SRR increased, respectively. Cross-sectional observation showed that in the case of gas nitrocarburizing, crack propagation stopped in the middle of the compound layer. The mechanism improving fatigue wear resistance is considered to be the effects of the compound layer produced by the nitrocarburizing. We considered that the soft surface layer decreased the contact pressure and the compound layer protected against the crack propagation due to the high hardness on the improvement of fatigue wear by nitrocarburizing.

In this study, we focused on the shape of the indoor space point cloud and extracted spatial features as the first step to automatically construct a virtual space where the surrounding environment can be confirmed and the degree of freedom of expression is high, using point cloud data and a generative AI. Specifically, we created an autoencoder using PointNet and evaluated it by restoring missing features. Feature extraction was performed using two types of data: the rectangular parallelepiped point cloud data created virtually and indoor space point cloud data in real space. Spatial feature extraction was evaluated by comparing the shape of the output point cloud with and without missing points and by the distance error between the input point cloud and the restored output point cloud. The results suggest that it may have been possible to extract the spatial features of the general shape of the room, but it was not possible to reproduce the detailed shape of the indoor of the room.

This paper describes the wear properties of high speed steel (SKH51) in the lubricant with molybdenum phosphate additive under high contact pressure conditions. In the wear tests, the reciprocating sliding tests were conducted, and molybdenum phosphate (MoP) and zinc dialkyldithiophosphate (ZnDTP) were used as additives. It was shown from the results that the wear depth per unit cutting volume in MoP was 1.7 times smaller than that in ZnDTP, and that the chemical reaction film was formed on the contact area after the test. Moreover, the wear depth in SKH51 was almost same as that in alloy tool steel (SKD11). This result suggest that the film formation derived from MoP is affected by the concentration of alloying element, in particular the group 6 in the periodic table.

In recent years, several gait support and training devices have been developed to enhance the walking ability of elderly individuals. However, most of these devices are only intended for straight walking on flat surfaces and do not support turning or acceleration/deceleration. This study aimed to investigate the possibility of predicting changes in velocity from surface Electromyography (sEMG) using machine learning methods. The ultimate goal was to develop walking support and training devices that can assist with turning and acceleration/deceleration movements. The R2 Score of the true value and the predicted value was 0.630±0.107, indicating a moderate level of accuracy, and the trend of the time series was successfully captured. It is possible to predict velocity from the sEMG potentials of the Medial Hamstrings and Medial Head of Gastrocnemius through feature selection.

Rolling bearings are one of the most important machine elements, known as the "rice of industry". They are widely used in a variety of rotating machines and are indispensable for them. Despite the large amounts of rolling bearings used, it is still difficult to accurately calculate the service life of rolling bearings in advance theoretically, and it is also not easy to calculate the support stiffness, contact pressure, and internal stress of rolling bearings. In this study, we focus on the contact problem of four-point contact ball bearings, which have not been studied much. The commercial software SolidWorks and Hertz theory are used to analyze contact problems of the four-point contact ball bearings. In these analyses, a numerical analysis method is proposed to calculate the contact pressure and support stiffness of bearing. The comparison between the calculation results obtained by SolidWorks software and Hertz theory shows that both the contact pressure and support stiffness are almost the same when one-ball contact model is used, but there is a little difference between the two methods when the eight-ball contact model is used. So, it is necessary to improve the accuracy of the analysis by optimizing the eight-ball contact model.

Global environmental and energy issues require reduction of carbon dioxide emissions. In machine elements, there is also a need to reduce friction and create lubrication systems suitable for frictional environments. In this study, we focused on ionic liquids, which are expected to be a novel lubricant. Ionic liquids have various characteristics, and we conducted experiments focusing especially on their electrical properties. Since ionic liquids are composed solely of ions, they are susceptible to electrical effects. It is known that the solid-liquid interface structure of ionic liquids changes depending on the surface potential. Therefore, we attempted to manipulate the frictional behavior of ionic liquids by changing the adsorption structure by applying electric potential to the friction surface. The applied potential was determined by measuring the potential window using a cyclic voltammetry test. Then, a constant surface potential was continuously applied, and friction tests were conducted under each condition. This investigation shows that the use of ionic liquids to provide electrical potential reduced the coefficient of friction.

In recent years, workers' long working hours have become an issue, and there is a need to improve work efficiency. In order to improve work efficiency, it is necessary to enable workers to understand their work efficiency. In this study, four subjects were subjected to a continuous addition task with the aim of creating a model to estimate work efficiency during computational work using electrocardiograms and relative concentration changes of oxy-Hb and deoxy-Hb in cerebral blood flow, and their biological information was measured during the task. The model was created using a convolutional neural network, a machine learning technique. As a result of the training, the model using only electrocardiograms was not sufficient for estimation, while the oxy-Hb and deoxy-Hb in cerebral blood flow in the prefrontal cortex were able to provide highly accurate estimation. The PFI values suggested that the dorsomedial prefrontal cortex and the left dorsolateral prefrontal cortex were relatively important.

A mechanical tensioner system for a timing chain of an internal combustion engine consists of the leaf spring coiled on the backup spring and requires a stable friction resistance despite operating a starved lubricated condition. An effectiveness of the surface texturing to the leaf spring surface on stabilizing the friction resistance has been found. The present study describes a selection of the manufacturing process for the surface texturing consisting of aligned bumps. Electrochemical polishing, a laser abrasion and a micro milling using various cutting edges processes were applied. The residual stress and the hardness distribution measurement were connected to the endurance experiment. Results showed that the large tensile residual stress was distributed accompanied with excess hardening after the laser abrasion and that it was difficult to assemble the tensioner system. A small compressive residual stress accompanying without the excess hardening was found on textured surface using the micro milling with a ball end mill.

For gait guidance to elderly, previous studies have compared the gait of young adults and elderly, but only discrete assessments such as averages, and representative values have been carried out. To address this issue, evaluations have been carried out using principal component analysis on time series data from a certain gait cycle, but it is difficult to specify specific differences in joint angles. Furthermore, most of these studies assume that the walking ability of elderly is lower than that of young adults, and few studies have focused on the gait of active seniors, who can still walk briskly. Therefore, in this study, we focused on a technique called CycleGAN, a type of adversarial generative network, to visualize the time-series differences between the gait features of young adults and active seniors to support elderly in walking. As a result, the proposed method successfully generated and visualized reasonable gait feature generation for both gait types.

This study aimed to reduce friction of the internal parts of an engine such as a vehicle by using fullerene (FLN) -added lubrication oil. We investigated the friction characteristics of it with the change of surface roughness under boundary lubrication to improve fuel efficiency. We produced the test specimens with plateau structure and surface roughness Ra=0.1~2.6 with various roughness parameters using sandpaper and used a ball on plate tester. The specimens is SUJ2 and the used oil is PAO4 and PAO4 added 1000 ppm mix-fullerene. We measured fifteen roughness parameters (Rp, Rv, Rz, Ra, Rq, Rsk, Rku, Rsm, RΔq, R𝛿c, Rk, Rpk, Rvk, Mr1, Mr2) of the specimen surfaces and elucidated the relation between these parameters and the friction coefficients for fullerene-added oil. The results showed that the relation between three parameters (Rsk, Rp, RΔq) and them can be approximated by quadratic function and all the determination coefficients are more than 0.8. PLS regression analysis revealed a linear relationship (R²=0.72) between these 15 roughness parameters and the friction coefficient in the fullerene-added oil, which means that the friction coefficient can be controlled by manipulating the surface profiles by adding fullerenes. The difference in friction properties between the base oil and the fullerene-added oil was suggested to be the effect of spinnability.

Fruit farmers often need to keep their arms raised continuously when cultivating or harvesting fruits such as grapes. This paper describes the design and development of a non-powered arm support suit with drum-type mechanical brakes (DTMBs) to reduce their burden. This support suit supports keeping their arms raised continuously by using the DTMBs. Activating the DTMBs is easy. Also, releasing the DTMBs is easy. This arm support suit requires no power source and is essentially safe because it consists of passive mechanical components such as springs. To reduce the suit’s weight, many parts of the suit were made using carbon fiber reinforced plastics (CFRP) by using the 3D printer. First, the features and structure of this support suit are introduced. Second, the structure and mechanism of the DTMB is explained. Third, the developed arm support suit with the DTMBs is introduced. Finally, experimental results to consider the effectiveness of the developed arm support suit with the DTMBs are presented.

In industry, the demand for knowledge about contact conditions is quite significant. There are conventional methods called statistical methods to analyze contact conditions. Another relativery new method is direct simulation. However, there are still problems to be solved in terms of analysis accuracy and calculation cost. Therefore, in this study, we proposed simplified rough surface contact analysis using Herzian contact and interface betweeen asperities, and verified the validity of this method. As a result, numerical experimental evaluations confirmed that in a small number of asperities, the change trend is relatively close to that of Hertzian elastic contact theory.

In this study, we aimed to clarify how the frictional properties of EPDM changed after water immersion by treating it with plasma to promote decrosslinking. Three types of rubber were prepared as rubber test pieces for friction tests: untreated vulcanized EPDM rubber, vulcanized EPDM rubber plasma-treated with argon gas only, and vulcanized EPDM rubber plasma-treated with a mixture of hydrogen and argon gas. Ball-on-disk friction tests were performed against a SUJ-2 ball after and without water immersion . As a result, the friction coefficients of all EPDM test pieces after water immersion were lower than those without immersion. However, the friction coefficients of the two test pieces, which showed almost no change in swelling ratio due to plasma treatment, changed significantly after waterimmersion . Specifically, the swelling ratios of untreated EPDM and EPDM treated with argon plasma were not significantly different at 210% and 214%, respectively, but the friction coefficients of the two test pieces after water immersion were significantly different at 1.23 and 0.35, respectively. Because the friction coefficient changes significantly depending on whether or not plasma treatment is performed, it is difficult to draw quantitative conclusions from the results of this experiment alone about how the degree of decrosslinking of EPDM affects the friction coefficient after immersing EPDM in water.

In recent years, emotional value has been emphasized in products and services, and an understanding of emotions, which are closely related to emotional value, is required for this evaluation. However, subjective evaluation requires interruption of work during the evaluation process and is not real-time. In this study, we conducted experiments in which biometric information, emotion, and their intensity were acquired in real time, constructed a machine learning model from the acquired data with biometric information as the explanatory variable and emotion and its intensity as the objective variables, and evaluated the model. The results showed the effectiveness of the emotion/intensity estimation model, and suggested that the accuracy could be improved by capturing pleasantness/unpleasantness feature values. In addition, the importance of explanatory variables was confirmed, and it was suggested that cerebral blood flow was important for the estimation, and that the estimation of emotion using cerebral blood flow depended on the method of evoking emotion.

To improve the tribological performance of a ductile cast iron, a combined surface modification process consisting of a roller burnishing and a laser irradiation were applied. The former and the later process is for extruding the graphite and for surface hardening. It was found that the maximum height of the extruded graphite was several microns depending on the roller burnishing condition including the lubricants. Since the matrix surface was hardened and included the tensile residual stress after the laser irradiation, the excess laser treatment resulted in the embrittlement of the surface layer. Tribological properties evaluated with a quenched steel ring as a counter specimen in dry condition showed that a low and stable friction coefficient about 0.05 was maintained from the beginning of the experiment. The graphite film was formed on the treated surface and damage of the mated ring surface was small after the experiment. Preferable treatment conditions of the roller burnishing and the laser irradiation for the ductile cast iron (FCD450) were proposed.

In this research, a compact jumping type lunar rover was developed using a shape memory alloy (SMA) actuator and a spring. The SMA actuator was used as the driving source to reduce the vehicle's weight. The legs of jumping rover was modified to improve jumping capabilities, though these capabilities have yet to be quantified. Therefore, we conducted a jumping test using an infrared high-speed camera on sand with a grain size analogous to regolith to evaluate the jumping behavior. During the test, the device's center of gravity was adjusted from the front of the center axis to align with the device's axis in the jumping direction. The results indicated that the rover jumped with a forward-titled center of gravity, resulting in a shorter jumping distance.Conversely, the robot achieved a longer jumping distance when the center of gravity was aligned closer to the central axis. This paper describes the outline of the prototype and compares the results of jumping tests conducted on sand by changing the center of gravity position.

Reflectance spectroscopy is an effective method for in-situ analysis of friction surfaces during friction tests. Reflectance spectroscopy has been used to elucidate the mechanism of friction reduction by the structural change layer formed on the topmost surface of DLC coatings. However, because reflectance spectroscopy requires transmission of the measurement light, the friction partner material has conventionally been limited to sapphire. Therefore, no method has been proposed that can be used for friction tests between DLC coatings and arbitrary counterpart materials. In this study, we investigated the feasibility of reflectance spectroscopy when a ta-C is coated on a sapphire hemisphere surface. First, the optical properties of the ta-C were measured. Then, an optical model was set up after the optical properties are obtained, and an in-situ sliding surface analysis was conducted. The results suggest that reflectance spectroscopy using a ta-C coated sapphire hemisphere can be performed with the same accuracy for measurement of lubricant oil film thickness as that using a sapphire hemisphere.

In electric vehicles (EVs), the trend toward reducing viscosity in lubricants aims to improve transmission efficiency. In this study, the mechanisms of reaction film formation and performance of P-based and S-based additives used to enhance the wear and damage resistance of low-viscosity lubricants were elucidated. This was achieved through fatigue friction testing using MTM, and by analyzing chemical composition with XPS, tribofilm thickness with STEM-EDS and MTM-SLIM, as well as physical properties with Nano-indenter. The S-based additives demonstrated high wear and damage resistance by forming a thicker and harder reaction film compared to P-based additives. Additionally, while P/S-based additives, which combine both P and S components, showed the best wear resistance, it was confirmed that surface damage became more likely due to the influence of the reaction film derived from the P-based component. This study investigated the formation process and structural characteristics of tribofilms from P-based and S-based additives under high-speed, high-pressure conditions, and analyzed their chemical composition and physical properties to evaluate their impact on steel surface wear and fatigue resistance.

The society is quickly aging. In Japan, the elderly people will be 40% of the whole populaition in Japan. Although Kansei is getting very popular these days, the current Kansei just enjoy the stimulus from outside. But to cope with the quickly aging society, we need to design and develop the society where elderly people can entertain themselves and make their life happy and fulfilling. This paper points out that although elderly people are very forgetful, they remember their good days as images. Atlhough we cannot detect these images directly from their brain right now, we can search similar images using such tools as Generative AI. Then, the elderly people can revive their good days. This paper points out that Kansei plays an important role in the aging society, but to achieve this goal, Kansei should consider how it can enhance the self-efficacy of the old people and let them dream their future.

Currently, many technologies have been proposed to identify speakers and transcribe speech from multi-person conversation data, such as meetings, and multiple services are commercially available from various companies. These services are continuously being improved, and the accuracy of speaker identification and transcription is also improving. Furthermore, some services attempt to estimate the emotions of individual speakers. However, such emotion estimation is limited to scenarios involving one-on-one audio data, such as call centers, and does not extend to estimating emotions from multi-person conversation data. Understanding whether a conversation was heated or not from multi-person conversation data remains limited to textual information, making it difficult to accurately infer the emotional context. Therefore, this study attempts to identify speakers from multi-person conversation data, separate or capture the audio data, and estimate the emotions of the identified speakers. As a result, it was possible to identify sections where any given speaker spoke alone and to estimate the emotions in those identified sections.

It is known that human affects and emotions are reflected in own eyes. Especially, the eyes with strong affects and emotions such as interest or motivation look like twinkling. People are fascinated and attracted by these twinkling eyes. Therefore, it is expected to examine the elements that fascinate humans and develop social robots for attracting humans by recreating these twinkling eyes using engineering technology. We focused on the reflection of the eyeball surface and developed a twinkling eyes interface by superimposing self-shadow on dilated pupils. This interface can express the pupil response and the shade of self-shadow depending on the distance. In this study, an evaluation experiment that combines self-shadow with dilated pupil was conducted. The effectiveness of the developed interface was demonstrated by sensory evaluations.

People who live alone often feel loneliness when they return home. Previous research has been conducted to reduce loneliness using social robots. However, there is little previous research on how to reduce loneliness in returning home. Therefore, it is expected to develop a social robot that creates warm atmosphere in returning home with non-verbal greeting, as if it is formed in welcoming by the family. In this study, we focused on the returning home when people tend to feel loneliness and designed an eye greeting expression using the pupil response robot. In addition, we investigated impression of these designed expressions, and indicated that the pupil dilation response may be effective in reducing loneliness.

The development of product design and interface design requires creative thinking by designers. This creative thinking generates new concepts by externalizing and reinterpreting images through sketching or verbalization. In other words, creative thinking can be viewed as an insight problem. Therefore, it is considered that the cognitive load will differ between solving geometric order such as sketching and solving order such as verbalization. By clarifying this difference, it is expected to obtain guidelines for externalization in creative thinking. In this study, the difference between geometric order and linguistic order in insight problem solving was analyzed by pupil variability. Specifically, we adopted a nine dots issue as a geometric order and a crossword puzzle as a linguistic order. As a result of the analysis, it was confirmed that pupils before solving the insight problem tended to be larger in the linguistic order than in the geometric order.

Contamination of metallic foreign particles in membrane electrode assembly (MEA) reduces the performance of the fuel cell used as in power generation devices. In the production line of the MEA, X-ray inspection has been employed to detect the contamination, but it has problems in the cost and the inspection speed. To address these problems, we have developed an automatic inspection system using deep learning into PFPIA-LDS. PFPIA-LDS is a system combining laser displacement sensors (LDS) and a pore fluid pressure impact generator (PFPIG) consisted of a piezoelectric diaphragm and permanent magnets. In PFPA-LDS, an MEA is placed in a static magnetic field and vibrated by the PFPIG. The vibration of MEA elicits eddy currents, and the magnetic force and the Lorentz force due to the interaction between the eddy current and the static magnetic field change the oscillation properties according to the contamination of metallic foreign bodies. In this study, we investigate the factors affecting the oscillation change and the system design of PFPA-LDS through numerical experiments based on the finite element method.

In recent years, studies have been conducted on the realization of sustainable production and consumption in the supply chain, and efforts are being made to collect parts supplied to the market and reuse them according to demand. In this study, we examined a method for adjusting supply and demand in a multi-generational, multi-product circular supply chain in which parts are repeatedly circulated across multiple products, considering the circulation of multiple products assuming multiple product categories as the target of the collected parts.

In recent years, for improving production efficiency, digital technologies such as cyber-physical production systems and digital twins are applied. While the mechanization and automation of manufacturing process is accelerated by such technologies, it is also important to use the manufacturing skills of craftsmen. Because some skills of craftsmen cannot be replaced by machines. Slow manufacturing is one of the manufacturing concepts focusing on craftsmanship for increasing added-value. Improved efficiency is not achieved through cost saving, but also through increased added-value. Manufacturing companies should focus on integration of automation technologies and skills of craftsmen, to save the cost and to increase added-value. This study proposes a method for classifying manufacturing processes into those should utilize craftsmanship or those should be automated. This proposed method evaluates the manufacturing process and calculates the centroid to use for classifying. Case studies show the applicability of the proposed method.

Contamination of metallic foreign particles in membrane electrode assembly (MEA) reduces the performance of the fuel cell used as in power generation devices and fuel cell vehicles. In this study, we propose a real -time diagnosing system of Fe particles buried into MEA, namely PFPA-LDS. PFPA-LDS is composed of multiple units of pore fluid pressure impact generator and permanent magnet, i.e. PFPIG, to excite the natural oscillation as well as the modulation by the magnetic force and the Lorentz force according to the contamination of metallic foreign particles. The excited oscillation is measured by laser displacement sensors, from which the contamination probability is further estimated using a proposed deep learning system based on Convolutional Neural Network and Attention-LSTM. PFPA-LDS was experimentally applied to both samples of MEA with the presence or absence of Fe micro-particles. As a result, the contaminated MEA were estimated to have a higher contamination probability than the normal one. In conclusions, the proposed method can distinguish the existence of Fe micro-particles, so has an effective potential as a diagnosing system of Fe micro-particles into MEA.

The gap adjustment process is very difficult for novice engineers and require high skills cultivated over many years. A suitable hitting method of a hammer for a gap adjustment process of a mold is analyzed theoretically in this paper. The mold consists of a base material, slide core and two guide rails. The mold and hammer are modeled and the transient response analysis is carried out by using FEM(Finite Element Method). A suitable hitting velocity and angle are obtained with consideration of both duration time and impulse of the hammer. As a result, it is revealed the suitable hitting velocity and angle can be determined when a natural frequency of mold is obtained.

Material extrusion-based additive manufacturing can fabricate lightweight, high-strength three-dimensional shapes using continuous carbon fiber composite materials. Conventional fabrication machines alternate between nozzles that extrude only polymer and nozzles that extrude a composite of continuous carbon fiber and polymer material. This method requires frequent nozzle changes, which reduces productivity. In this study, we developed a machine that can switch between composite and non-composite extrusion of continuous carbon fiber with a single nozzle and evaluated the accuracy of the extrusion process. In the proposed extrusion method, the polymer material is extruded while the carbon fiber is inserted into the heat block to prevent polymer leakage in polymer-only fabrication. The results of fabrication experiments using only polymer material in the developed AM machine confirmed that polymer leakage was suppressed by inserting carbon fibers. However, it was also found that even in this case, only about 60% of the inserted polymer was extruded. To solve this problem, the feed path inside the heat block needs to be improved.

In this study, we developed a production process education method that incorporates both learning and review processes. First, the necessary knowledge of production processes was extracted and systematized. Next, we proposed a learning process for this essential knowledge and a method for evaluating learning effectiveness. Then, a review process to ensure the retention of learning was considered. To evaluate the proposed educational method, a case study involving the assembly of a jigsaw puzzle through group learning was conducted.

When laser welding is used in the manufacture of parts, various welding defects rarely occur. Although the laser welding detection methods commonly used are manual detection, there is a possibility that the operator may make a mistake in judging the welding point due to inconsistency in judgments or physical fatigue of the operator. In such cases, an anomaly detection method based on images using machine learning is effective. Therefore, this study examined the feasibility of using machine learning to judge the welding point from weld images. Specifically, the welding part of the terminal connecting the coil and the circuit of an electric relay was selected as the target of quality evaluation, and Efficient GAN, one of the machine learning algorithms, was applied to configure the computer vision system. It is shown that the computer vision system used in this study precisely identifies welding defects. Next, we plan to implement the computer vision system at an actual production site and verify its performance under actual operating conditions.

At present, the pass/fail judgment of mechanical parts commonly used are manual detection. However, human inspection is expensive and not suitable all times. On the other hand, it is expected that computer vision systems will enable long-term detection and accurate judgment. The computer vision systems using mechanical learning have been investigated experimentally and numerically. Their investigation has primarily focused on image recognition. Since some mechanical parts have complicated shapes, they are sometimes conveyed in a state where they are partially overlapping with the preceding parts. In this paper, an actual alignment system for image recognition was proposed. In this paper, we propose a feeding device for image recognition. This device consists of a drum-type parts feeder and a linear feeder with a rail that has a hole. Any parts that are not in the correct position are dropped through the hole and returned to the original feeding area. This feeding device was tested to determine how the distance between parts that can be successfully recognized by the image recognition system changes with the number of drum rotations.

In recent years, advancements in Additive Manufacturing technology have led to extensive research on fabrication using devices with high degrees of freedom. Among these, methods have been proposed that utilize robots to directly embed Continuous filament-type object into grooves. However, if the robot has a low degree of freedom, twists can occur during embedding when the groove path is complex. Therefore, this study aims to perform embedding of Continuous filament-type object using 6-axis articulated robot with high degrees of freedom. Specifically, the objective is to propose a method for controlling the position and orientation of the end effector according to the groove path to eliminate twists during embedding. As a result, succeeded in eliminating the twist and embedding the tube.

Films are used in various products such as liquid crystal displays and flexible printed circuits. In the film production processes, the film is eventually wound to form a roll, but in the film winding process, defects such as wrinkles and scratches may occur. Although defects make the film roll worthless, resulting in a large manufacturing loss, conventional inspection methods cannot inspect them inside the film roll due to mostly the surface measurement. Therefore, we proposed a three-dimensional imaging inspection for film rolls using optical coherence tomography (OCT), which is a three-dimensional imaging modality with high spatial resolution mainly used in clinical diagnosis. Our previous study demonstrated that the occurrence of defects and types of defects can be inspected from tomographic images of film rolls visualized by OCT. In the case that OCT is employed in the film winding process in the production line, however, it is difficult to inspect the images visually since films are wound at high speed. To address this issue, this study proposes an automatic inspection for the occurrence of defects by using OCT tomographic images of film rolls and an unsupervised machine learning technique. In the presentation, we will show the results where the defect detection accuracy of the proposed method was investigated against the film thickness, the film material, and the defect type.

A web is a thin, flexible, continuous medium, and there are high-performance flexible products such as lithium-ion batteries and organic thin-film solar cells that use webs. There is a roll-to-roll production method, which is a production method in which the web is unwound and processes such as stretching, coating, drying, and lamination are performed continuously. This carry made it possible to reduce production costs and mass production. In the conventional conveyance process, various defects occur on the web, and expander rolls are used as a countermeasure for these defects. This is the name of a curved roller that has the property of spreading the web in the width direction. When the curved roller passes through the web, it disperses compressive stress and suppresses conveyance defects such as troughs. However, as the experimental evaluation and mechanism of the expander roll have not been clarified, in this study, we used a simulated conveyance device to evaluate the film widening performance. When evaluating the width widening performance, the amount of width widening was confirmed using a slit conveying device. As a result, it was confirmed that if the conveyance conditions other than the speed were the same, the conveyance speed had no effect on the amount of width expansion. In addition, it was confirmed that the compressive force in the width direction due to the web Poisson effect caused by excessive tension suppressed the web widening effect due to Expander roll, and the amount of widening at each contact angle uniformly decreased under high tension.