We propose a method based on genetic algorithm to automatically design planar link mechanisms that satisfies inputted purpose. Link mechanisms are a type of mechanical element that connects multiple parts in relative motion, and show a useful feature of extracting complex motion from a simple structure. Because it is not easy to design link mechanisms that performs the desired motion, many methods have been proposed to design link mechanisms to achieve the desired motion. However, it is still hard to know what kind of motion is required for the desired purpose in advance. Thus, we propose a design method using genetic algorithm with “purpose” as an input. Genetic algorithm is meta-heuristic methods that searches for optimal solution based on algorithms inspired by biological evolution. We show the modification of genetic algorithm to design planar link mechanisms and its application to the actual design attempts, and discuss further improvement of the model.

With the aging of the population becoming a social issue, power-assistive suits to reduce the burden of caregiving for the elderly are attracting attention, development, and research. The objective of this study is to experimentally determine the optimal graphene content of graphene composite natural rubber used for sensing in these power-assistive suits. Graphene is a sheet-like material consisting of carbon atoms connected in a hexagonal network and has attracted much attention in recent years because of its high electrical conductivity and strength. Previous studies have shown that the optimal graphene content is between 8.05 wt% and 8.10 wt%. Therefore, to investigate the optimal graphene content, five types of graphene composite natural rubbers (8.06 wt%, 8.07 wt%, 8.08 wt%, and 8.09 wt%) were prepared and their electrical properties were investigated. Methods to facilitate the fabrication of graphene composite natural rubber were also investigated. Furthermore, the microstructure of graphene-composited natural rubber was observed. The results showed that graphene-composited natural rubber prepared at 8.06 wt% had the best electrical conductivity in this study. The use of pure water was also found to be effective in the preparation of graphene-composited natural rubber. However, due to the presence of pure water, comparison with previous studies is not possible. Therefore, graphene composite resin with less than 8.06 wt% should be studied again using pure water. In the future, the shape of graphene composite natural rubber should be investigated for practical use in assistive suits.

In this research, new space structures are developed to develop space exploration. We believe that precise shape control of tensegrity structures, one of the modular structures, may lead to the development of new space structures. The advantage of using tensegrity structures is that they require less material because they consist only of compression and tension materials, and they do not need to consider bending loads because they only use tension and compression forces. However, although tensegrity structures have been used in many works of art, they have not been put to practical use due to the difficulties of design and fabrication. Therefore, we thought it would be possible to develop an actuator with a self-detecting function, which would enable precise shape control of tensegrity structures. This is made possible by a magnetostrictive element, which is a metallic material consisting mainly of iron. Magnetostrictive elements are characterized by the fact that they distort when a magnetic field is applied, and when they distort, a magnetic field is generated around them. The ability to precisely control the shape of the device would reduce the cost of transporting it into space by reducing the number of different materials used, and simplify the assembly of space structures.

In this study, we aim at the development of a robotic hand with thin fingers and in-hand rotation function. To achieve the in-hand rotation function, we evaluated the performance of several kinds of sponges as fingertips, and introduced a mechanism that can rotate objects even if the rotation axis was shifted. To evaluate the performance of the robot hand, we conducted the pick & place experiments on objects with various features.

Dynamical analysis of Double-H SMG, a novel Cartesian four-dof parallel robot driven by differential belts and differential screws is discussed in this paper. The Double-H SMG is planned to be applied to a haptic device that is manipulated by gripping the tip. A dynamical decoupling design is favorable for the impedance control of the robot. A dynamic simulator was developed using Simscape Multibody. The efficiency of the design for the small decoupling in the inertia matrix was confirmed by using the simulator.

The purpose of this research is to develop a device that can continuously supply PTFE fine powder with high accuracy. PTFE is used in a wide range of fields due to its excellent chemical properties, but it is difficult to continuously supply non-granulated PTFE powder due to its poor fluidity. In this research, in order to solve this problem, the hopper containing PTFE is vibrated in the horizontal direction, and the PTFE in the hopper is agitated. In addition, it is continuously supplied by introducing a crushing mechanism so that the PTFE does not solidify significantly. The experiment was conducted under three targets: supply value set to 0.8g ± 0.02g, target time set to within 40s, and target number of continuous supplies set to 100 times. As a result, in environment temperature of 21℃, it became possible to supply 100 times continuously while achieving the target accuracy of 90% or more. However, in environment temperature of 25℃, the supply was limited to about 45 times in a row. The crushing mechanism works effectively, but more effective control strategy is required in order to achieve all three targets at environment temperature of 25℃.

In Japan today, the aging of the population is progressing, and there is a concern that the number of elderly people who will have a trouble walking will increase. Rehabilitation of medical and welfare services are required to solve this problem, but it will be concerned to be difficult to deal with this problem due to a shortage of human resources and an increase in the number of elderly people. Therefore, there is a need to develop a walking rehabilitation device that can be handled by the elderly alone. Authors has been developing walking aids and rehabilitation devices using linkages. These devices do not require a control system or an external power source, and are designed with an emphasis on simplification and cost reduction of the devices. However, if it is designed with only a mechanism, the operation of the device may become unstable, which has been a problem. Therefore, authors aim to improve the stability of the device by newly using a pneumatic rubber artificial muscle as an actuator and assisting the operation of the mechanism. In this research, on the premise that a pneumatic rubber artificial muscle is used as an actuator, authors will develop a device that rehabilitates the interlocking movement of three leg joints with a one degree-of-freedom link mechanism. The aim of this study is to verify whether the characteristics of artificial muscles such as flexibility, high output density, and contractile movement are suitable for walking rehabilitation equipment.

In today's aging society, a variety of walking aids have been developed for the elderly or those who have difficulty walking due to injury. The main type of walking aids used in daily life are inexpensive simple walking aids such as canes, etc. Simple walking aids are used to reduce the load on the legs by placing a part of the body weight on the cane or walker. If the user relies on these devices, the user's posture when walking may become unsteady, and a load different from the original walking may be applied to the user. For the reason, the development of products with simple structures is desired to reduce the cost of equipment for the widespread use of welfare machines. Therefore, in this research, authors developed an inexpensive and lightweight walking aid using a link mechanism that does not require electronic control. The purpose of this research is to develop a walking aid for dynamic gait that can be used by more people. The device does not require electronic control, and the user drives the device with his/her own arm movements. The device is a planar four-bar mechanism that converts rotational motion into oscillatory motion to improve the transmission of force. The mechanism constants of a device with a planar six-bar mechanism, which was the subject of a previous study, were changed, and the auxiliary effects were compared with those of a planar four-bar mechanism.

A mechanism converting straight to cycle motion, for example a slider-crank mechanism is used for internal combustion engine. The research group suggested the Rotational-to-Linear motion Transformer using a Double eccentric Crank (RLTDC) as new mechanism convert straight to cycle motion. This mechanism is developed based on Oldham coupling (double-slider mechanism) and slider-crank mechanism, which can be expect for size down machines using a mechanism convert straight to cycle motion because stroke is double comparing a slider-crank mechanism on equal crank length. But, from the experimental measured value of the kinetic load in the preceding study, the matter that the durability of a slider guide would be concerned is revealed. So，the relationship between the peak value of load acting on the slider guide and the slider position is needed to be clarified. In this study, the process making the mechanical model for this relationship is shown.

As the number of elderly people in Japan increases, the number of people who have difficulty in daily walking is increasing. In order to solve this problem, it is required to develop a walking assist device that encourages the user to walk properly. Therefore, by using a link mechanism to mutually assist the torque generated in the knee and ankle to the other, it is possible to realize an auxiliary device that is completed only by the user without using actuators. This can be expected to improve the muscle strength and walking motivation of the user. The equipment manufactured in the previous research had three problems. The first was the heavy weight of the device, the second was the huge size of the device, and the third was that it could not be adapted to the wearer's physique. Therefore, in this research, linkages are made of resin, and the Parallel four-bar linkage mechanism is used to make the device smaller, lighter, and adaptable to the wearer's physique. The ratio of the torque of the hip joint and the knee joint of the manufactured device was investigated by simulation and the mechanical characteristics were verified.

It has been reported that ta-CNx coatings deposited by the IBA-FAD method show excellent low friction and wear properties, however the hardness decreases with the N/C ratio in the coating. Although, using an ion gun to mix nitrogen in the coating gives several pros to the coating, however, it rises initial cost of equipment. To overcome this situation, nitrogen ion generation by just supplying nitrogen gas close to an arc discharge area which is used in the FAD carbon ion generation was suggested by authors. The supplied nitrogen gas is ionized by the high voltage arc which is supplied to a graphite target. The effects on the N/C ratio was measured by AES, hardness was measured by nano-indentation tester, and tribological properties of the deposited ta-CNx coatings were examined. The results showed that ta-CNx coatings deposited by nitrogen gas supply method showed higher hardness than ordinally nitrogen ion beam deposition method.

Friction stir welding (FSW) is a joining method which uses the frictional heat generation between a rotating tool and joining metals. Furthermore, cracks, residual stresses and distortions which are the problems of the conventional welding do not occur because FSW works in the solid state ¹⁾. Cobalt alloys which have high durability in high temperature are used for the FSW tool material when it is predicted breaking. However, Cobalt alloy tools were worn compared with steel tools in our previous study. Then we carried out reciprocating wear test as first stage and observed the under structure of wear scar using TEM to clear the wear mechanism of FSW tool alloy.

In the real contact measurement by ellipsometry, there is a problem that the measured complex refractive index changes gently at the contact/non-contact boundaries. In this report, the multiple reflection in the gap between contact surfaces was considered in the optical model which was used to estimate complex refractive index. The sample measured result for a glass plane pressed by a glass lens in the air was successfully accounted for by the estimation by the optical model which considered the gap of layered structure. Thereby, it could be possible to improve the accuracy of real contact judgement by excluding the influence of multiple reflection in the gap on the estimation of complex refractive index.

Water-lubricated hydrostatic bearings, a type of plain bearings, achieve smooth rotation by forming a fluid film. While oil and air are commonly used as the working fluid in sliding bearings, water-lubricated bearings use water, which has lower viscosity than oil, as the working fluid, resulting in lower friction and enabling use in a clean environment. Most water-lubricated bearings have been developed for large bore sizes, and there are few examples of bearings for small bore sizes. Therefore, we developed a static characteristic tester that can evaluate the basic characteristics of water-lubricated hydrostatic bearings with slot restrictors. The static tester measures the displacement and load of the bearing casing, and the bearing is held in the casing by an O-ring. Because of the large load capacity and deformation of the O-ring in this test, care must be taken when calculating the eccentricity. Therefore, a torque meter was used to determine the contact between the shaft and bearing, and the eccentricity was calculated. In addition, a test machine was used to determine the load capacity from the load acting on the casing. Using this testing machine, the load capacities were measured for different slot clearances and bearing radius clearances, and the trends were investigated.

Contact Lens (CL) causes eye damage and discomfort by increasing friction with upper eyelids. To improve the safety and wearing comfort of CL, eye drop has an important role in reducing friction on CL. Therefore, it is essential to understand the friction mechanism between a CL and an upper eyelid in eye drop. In a previous study, we investigated the relationship between the hydration layer thickness and frictional properties of CL surfaces in a saline solution. We used a high-resolution tribometer and frequency-modulation atomic force microscopy (FM-AFM) to observe the hydration layer. The hydration layer of the CL in a saline solution was found to increase or decrease in thickness because of micro abrasion However, the effects of eye drops on friction mechanism of CL have not yet been investigated. In this study, we investigated the effects of hyaluronic acid on CL surface friction and hydration layer thickness. In friction tests, the coefficient of friction of hyaluronic acid solution was higher than that of saline solution, regardless of the amount of hyaluronic acid added. In addition, FM-AFM observations indicated that the hydration layer thickness on the CL surface increased in PBS with hyaluronic acid solution compared to that in saline solution. Therefore, the frictional properties of the CL in PBS with hyaluronic acid solution were not determined by the hydration layer thickness.

The friction and wear process of the reciprocating sliding surface is different from that of the sliding condition that continuously rotates in one direction. Also, the sliding state changes suddenly due to poor lubrication and progress of surface damage, which not only leads to vibration and abnormal noise, but also seizure in the worst case. Especially when sliding at a high speed, the sliding state changes quickly. Therefore, in order to extend the lifetime of mechanical system, it is desirable to be able to detect and evaluate even slight changes in the sliding state at an early stage. In this study, the evaluation of the sliding state of high-speed reciprocating rotating parts by acoustic emission (AE) sensing which has excellent detection sensitivity was attempted. A comparative experiment under different lubricated conditions and an experiment to verify the effect of fine particle peening treatment for different sliding speeds were conducted. As a result of the experiment, it was found that the lubrication conditions and the effect of surface treatment can be evaluated with higher sensitivity than the rotational deviation of the drive motor by AE sensing.

The formation of tribofilm by lubricant additives plays an important role in improving the performance of boundary lubrication. In previous studies, it has been discussed that the frictional force due to adhesion can be expressed as a product of the real contact area and the shear strength of the contact junction. Therefore, to evaluate the friction mechanism dominated by the tribofilm in detail, it is important to divide and identify the effects of the shear strength and real contact area. However, there are few studies that have verified the relationship between shear strength and macro friction coefficient with experimental data. In this study, nanofrictional property and real contact area of tribofilm was investigated using nanoindentation equipment and contact analysis. The results show that the shear strength of base material and tribofilms are correlated with the macro friction coefficients. In addition, the friction coefficients are calculated by applying the shear strength to the basic friction equation. The result shows that the friction coefficients calculated from the basic friction equation coincide with those measured by the macro friction test at a certain contact ratio of tribofilms formed in Tricresyl phosphate and over based calcium sulfonate.

The reserve actuators used in the Residual Reduction Algorithm of the musculoskeletal software OpenSim generate forces instead of muscles. In this study, we verified range of reserve actuator settings that can appropriately estimate muscle forces. A healthy adult man walked during the experiment. The results of the estimated lower limb muscle forces during walking indicated that the biarticular muscles, including rectus femoris and biceps femoris LH, and the monoarticular muscles which have many muscle attachment points, including gluteus maximus and psoas muscles, were not affected by the reserve actuators. While the monoarticular muscles, including soleus muscle, gastrocnemius muscle, tibialis anterior muscle, and biceps femoris SH, which have few muscle attachment points were easily affected by the reserve actuators.

Our present work is to elucidate the mechanism by which fullerenes inhibit the autoxidation reaction of lubricating oil to achieve the development of new multifunctional additives to replace ZnDTP. In this study, we generated discharge in lubricating oils with different amounts of fullerenes to investigate the radical trapping effect of fullerenes and the structural changes of fullerenes associated with radical trapping. The lubricating oils with fullerenes were found to exhibit a radical trapping effect depending on the amounts of fullerenes. Additionally, the lubricating oils with fullerenes were discoloration with radical trapping reaction, and the absorbance at a wavelength of 330 nm decreased in response to radical trapping. These consequences reveal that the structure of radical trapped fullerene was changed. Thus, the consumption of fullerenes can be detected by the decrease in absorbance near 330 nm.

Recently, with the aging of the population in Japan, the number of older people who require long-term care and arc forced to be bedridden is increasing. To improve their quality of life, we have designed a remote-controlled drone system using only eye movements. This system consists of a control screen, an eye-tracking device, a computer, the Internet, a joystick control device, a controller, a drone, a smartphone, and the web meeting service Zoom. This research aims to improve the design method of the joystick control device in order to develop the system using various drones. Experimental results to verify the effectiveness of the system with the joystick control device developed using the improved design method are presented.

In general, sliding parts of machines should avoid wear particles entering into a contact area to enlongen lifetime of those parts. To observe wear particles which entering into a contact point by using optical microscope and high speed camera is thought to be one of the potential candidate to elcidate life of the parts. However, it is challenging to see those particles of sub-micrometer diameter because of diffraction limit. The authors have been trying to develop iFLAT (intelligent Fluorescent Light Assisted Tribometer) to orvercome this diffraction limit. It can observe fluorescent stained particles which emits fluorescent light by 532 nm laser. The laser irradiates the friction surface through the objective lens, and the reflected light passes through the filter and enters the camera. The reflected laser light is blocked by a filter, and the imitated wear particles that emit fluorescence are selectively observed.

In this study, we clarified the effect of outside oil film thickness on the number of particles entering under poor lubrication conditions and the mechanism of this effect. In-situ observation of the contact area using 0.8 μm and 0.02 μm particles revealed four behaviors: backflow, lateral flow, incoming flow, and accumulation of particles.

In recent years, high-speed motors combined with traction-type reduction reducers have been considered to reduce the size and weight of electric vehicle power systems and increase their efficiency. A traction drive is a device that applies a strong load to two rolling elements and transmits power through the resulting EHL contact point. However, there is a concern that the increase in peripheral speed causes an increase in the thickness of the oil film in the contact point, resulting in a decrease in the transmission of power. In this study, the GMFT method, which enables one-shot measurement, was combined with a high-speed color camera to successfully capture the outline of the contact point under higher speed conditions than in existing studies.

This paper describes the effect of MoP lubricant additive on the wear properties of cemented carbide. In the wear tests, the reciprocating sliding tests were conducted under about 7 GPa of maximum Hertzian contact pressure, and MoP, MoA, MoDTC and ZnDTP were used as additives. The results showed that in tests using Mo type additives the amount of wear in MoP was smaller than that in MoA and MoDTC, and that the film was formed on the contact surface of cemented carbide after the tests. In addition, the wear in ZnDTP was greater than that in MoP, implying that Mo and P elements in the additive affect the formation of anti-wear film on the cemented carbide surface. Moreover, it was also shown by EDX analysis that in the rubbed surface of cemented carbide in the test using MoP, Mo, P, O was detected respectively, and that the concentration of Mo was greater than that in the test using MoA. These results suggest that in the test using MoP the molybdenum trioxide and the phosphorus film were formed o the cemented carbide, resulting that the film formed by MoP should prevent the decohesion of WC grains.

The symptoms of joint range of motion limitation make life difficult and aggravate quality of life. Usually, physical therapists provide rehabilitation training to prevent it. In this study, we have developed a passive motion device for pronation and supination of the forearm. This paper describes the prototype and the evaluation test of the device. We used a pneumatic soft actuator that can press directly on the affected area to develop the device. The pneumatic soft actuator consists of aluminum laminate films and an air supply tube. The device performs these motions for the forearm by the actuator directly pushing the wrist. In the evaluation test, the force generated by the pneumatic soft actuator was measured and we had a questionnaire about performance of the device from 10 subjects. The all subjects were able to perform passive movements of internal and external rotation of the arms. The tests also revealed that the device could allow the subjects to move otherwise from 60% to 80% of their reference range of motion.

Visual information is the most important information that humans use to perceive their own movements. In this study, we investigated how the perception of our own movement changes when we walk with a more expanded field-of-view (FOV). To expand the visual field, we constructed an FOV expansion system using a wide-field head-mounted display (HMD), two omnidirectional cameras, and a control PC. Using this system, the human FOV could be freely expanded from 160 to 360° in real-time. The results of the experiment indicated that the greater the expansion of the FOV, the faster the subject perceived their own walking speed. In addition, there was one case wherein the faster the perceived walking speed was, the shorter the perceived walking distance was. These results suggested that FOV expansion could create the illusion of increased athletic performance.

Mechanical properties of plastics greatly depend on temperature, which follows that the temperature rise in meshing gear teeth must be crucial to the load capacity of a gear pair. The present study will provide a method for estimating it. For this purpose, twin-disc tests with plastic test roller and steel roller allowed temperature-rise in test rollers to be measured. The twin-disc tests under the various applied loads and surface sliding velocities defined the change in the surface temperature of test rollers. The measured surface temperature gradually increased during the twin-disc test and converged to a certain level after some minutes. The difference between the initial temperature and the converged one is temperature-rise. The temperature rise depended on contact stress and sliding velocity. As a result, the temperature rise in test rollers has an approximately linear relationship with the PV value, which is the product of the maximum contact pressure (P) and the sliding velocity (V) between roller surfaces. This result could be fundamental data for estimating the temperature rise in meshing gear teeth.

Currently, environmentally friendly mechanical products are required, and energy saving is recommended．In order to save energy in mechanical products, it is necessary to reduce the torque of bearings used in mechanical parts．In this experiment, bearing life tests were conducted without lubricating oil, which is a bearing torque factor, inside bearing 51105, but with Ni-P-PTFE plating and Ni-P-B plating on the bearing raceways．As a result, the average life of the bearings without plating was about 100 hours, and the average life of the bearings with Ni-P-PTFE plating and Ni-P-B plating was 150 hours each．

When hydraulic fluid flows through a valve made of SUJ2 at high speed, the valve sometimes wear abnormally.

Since valves with abnormal wear lose their functions, it is necessary to elucidate the causes of abnormal wear. The purpose of this study was to clarify the effects of corrosivity and cavitation of the hydraulic fluid on abnormal wear.

Wear groove volume measurements, detailed surface observations, and surface component analysis were conducted at the abnormal wear locations. The results suggest that the area near the chrome carbide is eroded by corrosion and cavitation, and pits are generated in the abnormal wear area. It was also suggested that the brittle fracture near the edge of the pit was caused by cavitation, resulting in the expansion of the fracture surface and abnormal wear.

In recent years, the demand for virtual reality has been increasing due to the expansion of the virtual reality market, but because of the high degree of freedom, there is a possibility that the direction of attention may be dispersed. This study evaluates the attention inducing effect of a visual subthreshold stimulus inserted with brief darkening as a masking stimulus that does not impair the sense of immersion. We hypothesize that the location, duration, and size of the stimulus, as well as the contrast ratio of the brightness between the stimulus and masked stimulus, are factors that contribute to the cognition of the stimulus and aim to investigate effective attention guidance through a visual subthreshold stimulus. We use the reaction time of a visual search task and the presence absence of cognition of the stimulus to evaluate the attention guidance effect and analyze the factors for stimulus cognition. Experiment’s results demonstrate that the visual subthreshold stimulus induces gaze. In addition, the stimulus presentation time, contrast ratio of the brightness between the stimulus and masked stimulus, and the size of the stimulus have significant effect on stimulus cognition.

MEMS sensors have come to be used for various functions of smartphones and automatic driving system. The 9-axis motion sensor, which is one of the sensor modules, includes a three-axis gyro sensor, a three-axis acceleration sensor, and a three-axis geomagnetic sensor. The geomagnetic sensors which enable to measure the absolute direction are often used to estimate human posture. However, since the magnetic field is easily affected by the outside, it’s necessary to correct the sensor output. In this research, the geomagnetic sensor output is corrected using the gyro sensor output. The proposed method does not need complicated procedures. We verify the effectiveness of the proposed method even in environments where magnetic field disturbance generated, such as underground and high-rise buildings made of reinforced concrete. Furthermore, the knee joint angle during walking is estimated using the two 9-axis motion sensors by the proposed method.

DLC coatings have been applied to many automotive parts. This is because they have excellent properties such as low friction, high hardness, high wear resistance and chemical stability. Recently, bioethanol fuel has been attracting attention as a carbon-neutral fuel. However, the wear characteristics of DLC coatings under high-temperature and high-pressure environments, such as automobile engine environments, have not yet been clarified. In this study, friction and wear tests were conducted on Si-containing DLC coatings in ethanol containing high-temperature, high-pressure water. After friction test, we performed elemental analysis by Auger electron spectroscopy and AFM nano-scratch testing of wear scar of DLC coatings. As a result, it was found that the Si content suppressed the wear of DLC as the ethanol concentration increased, that the wear increased due to the effect of water, and that the wear increased due to the removal of the soft layer formed on the wear scar surface.

Centipede-type multi-legged robots can traverse rough terrain and are expected for disaster rescue operations. However, too many actuators make robots large and heavy, and make their control systems complicated. To solve these problems, the authors have developed a centipede-type robot which is composed of many leg mechanism units with a planar 4-bar link mechanism connected with passive revolute joints and have proposed a new control scheme to steer the robot with only phase difference between units. However, quantitative experimental validation has not been carried out. Thus, in this paper, the turning motion of the robot is accurately measured with an angular velocity sensor and an optical motion capture system. The measured results reveal that the proposed control scheme is correct on the turning direction while the measured turning radius is larger than that calculated with the proposed control scheme. Resultantly, this error of turning radius is caused by the variation of leg contact position and static friction due to the rolling motion of units.

Foil bearings are a type of gas bearing consisting of a thin metal top foil supported from behind by an elastic body. Therefore, the bearing characteristics of a foil bearing are highly dependent on the support structure, and there is a need to improve the damping and lifting performance. In this study, a new support structure, bump mesh foil, was proposed to achieve both damping and lifting performance, and its elastic properties at rest and lifting properties during shaft rotation were experimentally evaluated. The experimental results showed that the damping performance of bump mesh foil bearing was improved while having enough the same lifting performance as bump foil bearing.

In recent years, the demand for lubrication in the atmosphere has been increasing, and carbon-based hard coatings Diamond-like Carbon (DLC) have been attracted attention. A tetrahedral type of DLC with tantalum (ta-C:Ta) has been exhibited ultra-low friction approximately 0.07 in the atmosphere. The friction coefficient is thought to decrease due to an increase in the graphite structure at the topmost surface which was formed by desorption of oxygen from carbon or tantalum and restructuring of carbon structure. Which is assumed to be driven by energy from the application of frictional heat or shearing. If the oxygen desorption phenomenon described above can be realized by applying energy other than friction, low friction can be obtained without friction beforehand. It has been reported that irradiating CNx coatings with ultraviolet light desorbs nitrogen atoms from the surface of the CNx coating, reducing the initial friction period by 91 %.

In this study, we clarified the effect of UV irradiation on the oxygen desorption in the ta-C:Ta0.024 coating (Ta content was 0.024) . AES and XPS revealed that UV irradiation caused C-O bond cleavage and oxygen desorption.

The objective of this study was to elucidate the effect of lubricant additives on the tribological properties of poly-acetal (POM) and steel materials under boundary lubrication. To investigate the effects of lubricant additives on the tribological properties of POM and structural changes at the friction interface, friction tests and surface analyses were conducted using friction modifiers and anti-wear additives among the lubricant additives under uniform atmosphere conditions other than the additives. The test materials used were POM ring specimens and S45C discs as mating materials. This test was conducted using a ring-on-disk friction test configuration in which the POM ring was rotated by a motor while the POM ring was pressed against the S45C disc at a constant load. As a result, it was found that lubricant additives inhibited the friction-reducing effect of POM regardless of the type of additives. In addition, it was inferred that the friction-reducing effect of POM was due to the POM transfer film formed on the steel material.

Magnetorheological fluid (MRF) is functional fluid whose viscosity changes under magnetic field. It is used in applications such as dampers and brakes. In this research, permanent magnets are used to hold MRF between two rotating bodies. Traction force generated by MRF under magnetic field used to transmit power between the rotating bodies without vibration and noise. In this paper, we research the arrangement of permanent magnets and the configuration of magnetic circuits that hold MRF in the gap between rotating bodies and transmit rotational power without supplying additional MRF, and report on the improvement of power transmission efficiency. In this research, three models are assembled. Nonmagnetic rollers are used as the rotating body in Model 1, nonmagnetic disks are used in Model 2, and ferromagnetic disks are used in Model 3. The results showed that Model 3 was superior in both power transmission efficiency (74.6 [%]) and maximum transmission torque (0.55 [N∙m]). This is due to the fact that the use of a disk as the rotating body enables power transmission through the MRF over a wider area than with a roller type, and that a ferromagnetic disk can hold the MRF strongly.

Cold spraying is a surface coating technique in which a powder material is impacted on a base material at high speed without melting to form a dense coating layer. However, the stress-strain relationship in the strain rate range of 5 × 10³ to 2 × 10⁴/ss , which is required for Cold spraying, has not yet been sufficiently obtained. In this study, stress-strain relationships of pure nickel and Inconel 718 as target materials in a wide range of strain rates from quasi-static strain rate (10⁻³/ss) to ultra-high strain rate up to 10⁴/ss were investigated by means of a Split Hopkinson bar method and a high-speed material testing machine (TS2000 Saginomiya co. Ltd.). From the experimental results, the stress-strain relationships of pure nickel and Inconel 718 in the wide strain rate range were clarified and a strain rate sensitive constitutive model was formulated by referring the Tanimura-Mimura (2009) model.

Additive Manufacturing has an advantage in manufacturing monolithic fabrication. In this paper, a motion device by monolithic fabrication using Nichrome wire and Shape Memory Polymer (SMP) is proposed. The device is fabricated with Fused Filament Fabrication (FFF) using the wire-included filament, which was originally developed in author’s laboratory. The motion tests of device were conducted and the results showed that the device can be used to handle a soft object.

In the Additive Manufacturing (AM) method of Fused Filament Fabrication (FFF), thermoplastic resin is extruded from a nozzle along a forming path generated from a 3D geometric model of the object. FFF software slices the object in a horizontal plane, and arranges support material during the fabrication process if needed. To reduce the support material, Robotic AM using a vertically articulated robot has been studied. Although Robotic AM realizes multi-directional access, its’ motion is affected by singularities. Since most cases of singularities can be avoided by changing the starting point of the work, in this study, a dual-arm robotic AM is proposed to increase possibility. An extrusion nozzle is attached to one arm, and a bed is attached to another arm. The position and orientation of the extrusion nozzle and the bed can have enough degrees of freedom. The best starting position and orientation will be optimized by simulations according to design of experiments. The behavior was confirmed by running the simulation and the actual machine.

There is a great demand for multi-objective optimization of production plans at the high-mix low-volume production of the manufacturing industry, and the importance of multi-objective numerical optimization technology will increase more and more in the future. In this research, we have developed a control method that can realize a wide range of Pareto solution at high speed for two object functions; cost and productivity, which are important in manufacturing fields but have a trade-off relationship. The key of present technique is a technology that can obtain a wide range of Pareto solutions, which are difficult to solve by each technology alone, by appropriately controlling a technology that has high search performance but is single objective optimization and a technology that can perform multi-objective optimization but has low search performance. This paper presents an example of solving a standard multi-objective optimization problem and the results of applying it to setup optimization problems which are often found in actual manufacturing fields.

In the manufacturing industry, efforts have been made to reduce the waste of resources with the aim of effective utilization of limited resources. The recycle supply chain that collects and reuses the products put on the market has been modeled so far, but many of the previous models have decided to reuse the collected parts for the same purpose. In this report, we propose a model that reduces the waste of parts by converting the recovered parts to different uses according to the deterioration rank. We constructed discrete-event simulation model and evaluated lifetime value and various costs.

Environmental testing apparatuses are widely used in production sites for quality assurance of manufactured products. They can simultaneously control both temperature and humidity inside the apparatus. However, the preinstalled controllers are traditional PID feedback control systems, and they cannot control both physical values, temperature and humidity, effectively because a PID cannot be designed for a MIMO (Multiple-Input Multiple-Output) system. Moreover, when the control input signals for the heater and humidifier reach either the upper or lower limit, the PID controller can no longer control the temperature and humidity effectively, because of the nonlinearity of the saturations. Recently, MPC (Model Predictive Control) is becoming widely used in industrial manufacturing systems because it can take into account the limitation of the control input signal, and can be applied to a MIMO system. Simulation results show the effectiveness of the MPC system which is intended to implement in the PLC (Programmable Logic Controller).

Non-contact conveyance control system essentially should be ensured that the levitation object remains stable at a specific location below the electromagnet. In that case, it is important to keep the levitation object at a target position and suppress vibration caused by the conveyance motion. The lavitation control system is designed to equalize the closed-loop system to a second-order lag element to stabilize and ensure the appropriate response. However, the design criterion of the natural angular frequency of the closed-loop system, which is one of the design parameters, has not been clarified, therefore it was determined as an empirical value so far. In this study, investigations of the criterion of the design parameter were conducted through experiments. They show that the stability margin, which can be obtained by the self-identification experiment, can be applied directly to the design of the control feedback system. Consequently, it is expected that the performance of the non-contact conveyance improved for any kind of levitation object.

As the EC markets are expanding, customers are increasingly demanding small lots and short delivery times. The need for efficient, fast, and convenient last mile delivery will likely continue to grow. One of the problems with the last mile delivery in supply chain management is the frequent redelivery of parcels due to the absence of consumers. Therefore, the use of parcel lockers can be expected to be significantly effective in reducing redeliveries. This research proposes a method for deciding parcel locker locations, which highly convenient not only for consumers but also for delivery companies from the viewpoint of minimizing both the detour distance from consumers’ travelling routes and the delivery distance of delivery companies. Numerical experiments are carried out by using road information obtained from detailed map data in order to evaluate the effectiveness of the proposed method.

While the competitive advantage of Japanese companies in the semiconductor industry has declined significantly, the competitive advantage of Japanese companies in the power semiconductor field is still maintained. Based on the architectural theory that Japanese companies have strengths in industries that require matching, this study analyzed the factors of matching in the field of power semiconductors. As a result of comparing the relationship between the functional design, structural design and process design of logic ICs and power semiconductors, which are typical products of the semiconductor industry, there was a strong dependency between the functional design of power semiconductors and the process design. It was shown that the strong dependence between functional design and process design is one of the competitive advantage factors of Japanese companies in the field of power semiconductors.

Simulation of the surface force apparatus (SFA: ESF-5000K, Elionix, Inc.) using elastic contact theory was performed to calculate the surface force and approach distance between sphere and plane. A series of experimental processes from contact to pull-off between a spherical probe and a plane sample was targeted in the simulation, and the mutual displacement of the sphere was calculated using JKR elastic contact theory and the van der Waals interaction force. In this study, the glass (BK7) was used for the spherical probe, while Si and Pt were used for the plane samples. Comparison of the theoretical calculation results with the experimental results confirmed the validity of the simulations and clarified the contact properties between the sphere and plane sample. The difference between the refractive index of the actual material and the ideal value may cause the theoretical curve to deviate from the experimental results.

This paper examines the application of the sheet stacking technology by impellers to stack sheets like electrodes at a high speed without damage. We aim to develop a new simulation model for electrodes and to establish a method to design impellers. Stacking method by impellers is a way to stack sheets by inserting sheets in between impeller blades. Three-dimensional model of impellers was created by mechanism analysis software RecurDyn. We have calculated the effect of deceleration as an evaluation index of damage-less impeller-stacking by simulating distance traveled along impeller and collision velocity. These distance and velocity could be roughly estimated from the regression equation by sheet parameters and the effect of deceleration.

Research on outdoor work robots is in progress in the field of such as agriculture, forestry, civil engineering, construction, and space. One of the characteristics required in such a work environment is to have a large working space. Therefore, a manipulator that is not only small and lightweight but also has a large working space is required. The study proposes a casting manipulator with a flexible rod. Analysis of such systems generally requires a large computational cost. Thus, a computationally efficient formulation method is necessary for advanced design and control, and this study proposes a formulation method based on ANCF and LCP. For the flexible rod part, the Absolute Nodal Coordinate Formulation (ANCF) is applied, and for the relationship between the tip of rod, wire, and hand, the linear complementarity problem (LCP) is applied. A model that combines these methods is constructed and perform numerical analysis. In addition, validation experiments are conducted to evaluate the validity of the model. Finally, the effectiveness and problems of the proposed method are demonstrated by comparing the numerical analysis and experimental results.

Behavior Based Safety (BBS) is an effective and efficient way of influencing workers behavior with respect to workplace safety, regularly resulting in substantial reductions of workplace accident rates. This has been documented in thousands of companies worldwide and in several hundred studies. However, Behavior Based Safety isn’t only about changing overt behavior like holding to a handrail and putting on Personal Protective Equipment (PPE). With its integral understanding of behavior as everything a person does, thinks, feels etc., Behavior Based Safety is also changing the so-called safety culture towards a more positive, proactive, and humane environment for all employees.

Behavior Based Safety (BBS) is a collection of methods that all have the purpose of achieving safe work habits and reinforcing safe behaviors. It is known to be the most effective tool in occupational health and safety for changing behavior and reducing accident rates at work. Although proven in various studies amongst different work environments, e.g., medical surgery, mining, factories etc. its adaption in Germany is very poor. In fact, many employers seem to feel resentful against the concept of BBS and base their occupational health and safety program around instructions and control mechanisms for their workers. Reasons for this remain speculative: Is it because of the insurance policy in Germany that does not directly reward employers for sustaining a safe work environment? Or is it more cultural driven – especially regarding giving positive feedback for behaving safely as something excessive? The presentation will discuss possible reasons and takes a comparative approach regarding occupational health and safety in Germany and Japan.