The authors applied the three conditions for desirable structures by a load transfer index Ustar (U*) to the objective function of the topology optimization (method: level set method) of the structure, and examined fundamental studies on optimum structure design for the load transfer path. We performed a topology optimization calculation on a square flat plate structure and confirmed an increase in specific stiffness of the optimized structure. We showed that the topology optimization of the structure using the load transfer path is effective against the stiffness, also showed difference of optimization results by application of load transfer path.

The authors have previously proposed a load transfer index U* (Ustar) and developed a structure optimization method based on three conditions of U* for desirable structures. In the present study, as a fourth condition, we required clarification or intensification of load paths in order to realize a sufficiently large load transfer in structure optimization. We introduced the concept of the U* entropy, similar to the information entropy. The intensification of load paths is expressed by the inverse process of the U* entropy increase law. It seems to virtualize the life phenomenon of structures that occurs in optimization. We applied the fourth condition of the U* entropy reduction to structural optimization calculation of simple spring models and showed the effectiveness of the introduction of the new condition.

A data collection unit is developed to increase the productivity of manufacturing facilities and the quality of products. The unit can be attached to an existing facility easily. It tracks each workpiece in the facility by using virtual workpiece which is modelled by state machine. It can attach ID of the workpiece to process data easily. Further, a modeling tools for setting up virtual workpieces and data collection flow is developed, to apply the data collection unit to various facilities in a short lead time.

The tribocharge rotational speed sensor for ball bearings was developed. The tribocharge sensor having a rotor and a stator with each segmented electrodes, which sandwich a PTFE film, was attached a ball bearing. The ball bearing used in this study is the bearing number of 6201DDU. The thickness of this sensor is less than 0.5 mm. When the bearing rotates, the PTFE film on a segmented electrode of rotor rotationally slides in contact with other electrode on stator. Each segmented electrode has four segments, positively charged by sliding with the PTFE, and the PTFE film is negatively charged. Output sensor voltage is obtained from the segmented electrode of the stator attached on a fixed ring of ball bearing. The rotor is attached on a rotating ring of ball bearing. This bearing with the tribocharge sensor was evaluated using our trust type bearing tester. The output voltage from this tribocharge sensor was proportional to the rotational speed and that was about 1.5 V0p at 2000 rpm. In addition, the generated power was 0.2 μW at 2000 rpm.

In recent years, the increasing of aging infrastructures such as bridges and tunnels has been one of the most particular concerns in the world. For this reason, low-cost, low-power and wireless monitoring technologies are required. Acoustic Emission (AE) techniques have the potential to detect initial deterioration of structures. We have been developed an original AE sensor system integrating an event-driven, energy-harvesting and edge computing system. This paper presents the result of the long-term demonstration by AE sensor system on reinforced concrete slab.

For the purpose of realizing flexible and lightweight battery-less systems, we are developing piezoelectric vibration energy harvesters (PVEHs) with piezoelectric thin-films. We have optimized structures of PVEHs by theoretical models of equivalent circuit based on the lumped parameter model and the piezoelectric constitutive equations. The mechanical systems consist of a metallic cantilever beam with piezoelectric films, while the electrical ones are composed of electrode capacitances and a transformer connecting these two systems. Based on these equations, we have made an equivalent circuit model of the PVEH with trapezoidal cantilevers. We can calculate not only sine wave responses but also impulse ones. We have calculated formula Pout and shows electrode length and substrate SUS thickness-dependences of output power. We can maximize the output power by making the electrode length to 2/3 of cantilever length, and also by the substrate thickness thicker, where we have to balance with the substrate rigidity.

We evaluate the piezoelectric vibration energy power generator that is developed by us in this paper. In the technology of piezoelectric vibration energy harvesting, it is well known that the harvesting efficiency can be enhanced by changing the circuit state suitably. The power generator realizes the controlling the circuit state without external power sources and external sensors. Consequently, the power generator can be driven independent from the external environments completely. The power generator is evaluated in three respects, the amount of harvesting energy, the charging time, and the electric power consumption. We confirm that the power generator is efficient based on experiment results.

Lithium ion batteries are widely used in various kinds of portable devices because of their high voltage and energy density. Recently all-solid lithium ion batteries have been studied to solve the problems of liquid electrolyte. In order to fabricate all-solid thin-film battery composed of V₂O₅ cathode, we fabricated V₂O₅ thin film on Pt/Ti/glass substrate by RF-magnetron sputtering and evaluated electrochemical properties of V₂O₅. As a result, the specific capacity of V₂O₅ with thickness of 0.5 μm is higher than 100 mAh/g at 1C rate and the cycle performance of V₂O₅ with thickness of 2.5 μm kept more than 90% capacity over 30cycles. Therefore we confirmed that V₂O₅ works well as cathode material of lithium ion battery. Subsequently we fabricated all-solid thin-film battery composed of V₂O₅ cathode and Si anode and LiPON electrolyte. It worked as thin-film battery and the capacity was about 50 nAh / (cm²∙μm) over 100 cycles.

This paper proposes a novel design of a magnetically-sprung mechanical oscillator using ring magnets for use in electromagnetic wideband vibration energy harvesters. In the proposed design, two fixed ring magnets are placed to hold a moving cylindrical magnet in the middle whose diameter is smaller than the bore of the ring magnet, guided to smoothly move along the axis direction. Thanks to the offset magnetic pole of the ring magnet from that of the moving magnet, the repulsive force acting between one ring magnet and the moving magnet has a stable equilibrium and a minimal point. This enables the proposed magnetic spring to have significant nonlinearity in a short stroke, with a variety of tunability of the restoring force with different linear stiffness, even including essential nonlinearity and bistability, by changing the distance between the ring magnets.

This paper presents an experimental verification of a wideband vibration energy harvester with a nonlinear oscillator using leaf springs and stoppers in terms of the frequency response and power generation performance through steady-state excitation tests. A response stabilization control using negative impedance converter (NIC) has been successfully introduced to destabilize the undesirable low-energy response in the resonance band and make the high-energy response globally stable. However, since the response stabilization control requires electric energy to give a self-excitation capability to the nonlinear oscillator, the energy consumption by the control circuit is a critical problem. In this study, the energy consumption by the control circuit has been experimentally evaluated while it is activated in response to impulsive disturbances, and compared with the power generation capacity of the harvester. Is has been concluded that most of the energy consumption in the circuit comes from the energy loss in the operational amplifier in the NIC circuit, and the total energy consumption can be retrieved by the energy harvesting for 20 seconds.

Many patients who require heart transplantation use an auxiliary artificial heart during waiting period until a real heart transplant is performed. During waiting period, high risk of blood clotting due to nonphysiological contact and cerebral infarction complications occurs. Therefore, it is necessary to create technology to prevent blood clotting without intervention of artifacts. Herein, we propose a micropump technology to overcome the complications. In this research, we focus on the Finite Element Method (FEM) to evaluate the behavior of the mechanical element theoretically to characterize the liquid transportation rate. Then, analyze C shaped PZT on blood vessel and investigate in fluid behavior. Finally, we confirm the principle of micropump by experiment.

In this paper, method to estimate fingertip force with ring-type wearable sensor is proposed. To select effective exercises, it is important to accurately measure motion of patient, such as postures and force. Especially, fingers perform complicated movements, loss of function significantly adverse effects on active of living. Measurement of fingertip force is relatively difficult, because it is necessary to use load cells in the target object or between finger and object. Therefore, in previous study, we focused on the relationship between tension of tendon and fingertip force, and proposed ring-type wearable sensor to estimate the fingertip force. First, we investigate the relationship between finger joint angle and sensor output at the condition that the fingertip force is zero. Next, the relationship at the condition that fingertip force is applied is investigated too. Finally, on the basis of above investigations, the relational expression between the joint angle, the ring-type sensor output, and the fingertip force was derived as new calibration formula for estimating fingertip force.

In order to estimate the position of the tumor in an organ, we propose a method to estimate the relative direction of the tumor with respect to the grasping position by the developed grasping forceps with sensors. The relative direction is calculated using the two directional shear forces obtained by sensors attached to the grasping forceps. In this paper, we confirmed the principle of the proposed method by targeting a tissue model consisting of silicone rubber (hard object) and gelatin. We observed the two directional shear forces toward the hard object when the grasping forceps grasped the model within 8 mm from the center of the hard object. This result indicates that the proposed method can be applicable to the relative direction estimation of tumors to the grasped position.

In resent year, many people are diabetes. In order to maintain their blood glucose level they need to get insulin injections every day, which is very painful and fearful. Therefore, we aimed to develop painless microneedle by mimicking the mosquito labium. The painless microneedle was fabricated by sputtering method followed by wet etching. Initially, the copper wire was coated with biocompatible material like titanium by RF magnetron sputtering method. In the previous study, attention was paid to a needle with a square cross section and it was made. In this research we will use the finite element method (FEM) and simulate a puncture in the skin and evaluate it.

An osteosynthesis plate consists of a plate and screws. It is a medical instrument for repositioning the broken parts of bones to their appropriate positions. There are two types of screws used with the osteosynthesis plates. The one is a monoaxial screw and the other is a polyaxial one. The latter can be fixed at within a certain angle with the plate. By these screws, one can reposition the pieces of a broken bone to a mechanically and anatomically right position. However, the polyaxial screws usually have problems of reduced fixing force when used with thin plates. Thus, we devised a plate with small fins inside of the holes so that the screws cut into the inner surface of the hole easily and fixed strongly by thread tapping. First, we found the optimum combination of plate and screw materials. Next, we investigated the effect of the widths of fins and inner diameters for the purpose of optimizing the tightening torque. In addition, we clarified the process of plastic deformation during destructive fixation test. As a result, we could propose a new polyaxial locking system with performance equivalent to existing products. Furthermore, we considered an optimum screw shape that can disperse stress using FEM analysis..

The measurement system of gait parameters during fastest gait using inertial sensor is proposed for large scale health checkup. During fastest gait, acceleration and angular velocity of the toe exceed the measuring range of high-sensitivity sensor. To estimate gait parameters, inertial sensor system that is composed of two triaxial accelerometer and two triaxial gyroscope with different measuring range is developed. Also, since the swing phase was manually selected in current analysis program, the burden was large. Therefore, a new algorithm for automatically determining the swing period is developed. In the health checkup, subjects are asked to walk at their fastest speed while the inertial sensor measures the acceleration and angular velocity of the toe. To evaluate the effect of the proposed method, gait parameters are estimated using the previous method and proposed one. As a result, using proposed method improves the accuracy of gait analysis compared with the previous method and shows almost same results compared with the method of manually determining the swing phase.

The rehabilitation of flexor tendon have to do each three hours after the operation. This rehabilitation work is very hard for therapist. Then the rehabilitation device is required for him. In this report, we discuss the rehabilitation mechanism for flexor tendon. We consider that the effect of tension by a string. Then we divided into the three sentences our discussion. At first, we discuss the module of fingertip to pull. The second discussion is about the fixing device on the base of finger. And finally, a mechanism of wind-up gear. We propose the rehabilitation device for flexor tendon.

Gelatin gel is an essential material in medical and food processing fields. However, since gelatin gel is a soft material, microfabrication by cut processing is difficult. Therefore, in this study, processing of gelatin gel is carried out by using Micro-Electrical Discharge Machining (micro-EDM). In medical research field, 3D cell culture attracts attention. Some cells are oriented in vivo, and when cells are cultured in a groove having a width of several tens of micrometers, the cells can be oriented. In this study, groove having a processing width of several micrometers was produced utilizing micro-EDM. Furthermore, control of the processing width of grooves and fabrication of circular grooves were carried out.

3D bioprinting is one of methods for creating cellular tissue substitute. In order to create scaffold by 3D bioprinting, it is necessary to print high viscosity biomaterial with high accuracy. Alginate hydrogel, it is one of biomaterials, can produce high strength gel by mixing low viscosity two liquids, and highly accurate printing is reported by 3D bioprinting. However, it is usually not possible to print with alginate hydrogel structure print thinner than the nozzle inner diameter. Therefore, we considered printing alginate hydrogel utilizing ultrasonic vibration. By this method, we success in creating alginate hydrogel structure thinner than the nozzle inner diameter.

This study proposes a method of measurement and control in micro cutting process with rotary cutting tools of 30-100μm in diameter using a electromagnetically levitated stage. Because the magnetic levitation can support a stage with work by non-contact, disturbance such as frictional force does not occur and it can measure force produced by micro cutting. Furthermore, the force applied to the cutting tool can be controlled by adjusting the position of the stage depending on the measured force. In this study, an experiment of measurement of the force in micro cutting process using tool of 30μm in diameter are reported.

Friction force microscopes (FFMs) are widely used for measuring lubrication properties on the nanometer scale. In measurement of lubrication in nanometer gaps, control of the gap between the sliding probe and the sample surface is essential since lubrication properties significantly depends on the size of the gap. In this report, with the aim of realizing FFMs capable of accurate control of sliding gap, we tried to develop a probe with an actuator that utilizes electrostatic and elastic forces.

In order to ensure the performance and durability of highly accurate mechanical systems, it is urgent to establish lubrication technology realized in minute gaps. It has been reported that the mechanical properties of lubricating oil in minute gaps narrowed down to nanometer order are completely different from those in the bulk state, and elucidation and quantification of these phenomena are indispensable for lubrication design. In this research, in order to elucidate the temperature dependency of lubricant viscosity in nanogaps, we proposed laser heating of lubricating oil in high precision viscosity measurement method developed in our previous research.

When liquid is in a small gap between edge faces, liquid forms a liquid bridge that connects each of the edge faces. When this liquid bridge breaks up by stretching, a micro droplet is generated near the center of the gap. We investigated the effect of liquid bridge volume on the size of the generated droplet, aiming to apply this phenomenon to new dispensing method which can dispense a picoliter droplet. Consequently, we find the fact that the diameter of the generated droplets is in proportional to the liquid bridge volume. That results in the volume range of generated droplets is approximately from 30[pL] to 4000[pL].

We report on the performance of a measurement system based on laser Doppler principle using an interference of evanescent waves generated at total internal reflections of incident lasers at a solid wall. The system was developed for the velocity measurement of colloidal particles at an interfacial boundary of colloidal liquid and a solid wall. The system has a unique advantage of a high spatial resolution in the direction perpendicular to the boundary due to the short penetration depth of an evanescent wave in the range of a few hundred nanometers. The measurement performance of the system was investigated using a scanning probe in the measurement volume. The result quantitatively confirmed the measurement feasibility of the system. The system was further applied to the velocity measurement of the aqueous solution of alumina particles filled in a square cell induced with electric fields. The measurement result demonstrated the applicability of the measurement system for average velocity of colloidal particles in the vicinity of a solid wall.

Frost generation onto heat exchangers’ surface is generally presumed to cause reduction of heat exchange efficiency, therefore the surface with some texturing to reduce adhesion between frost and the surface is required from the industrial field. To reduce the contact area between frost and metal surface, lines and spaces or dot pillars are thought to have powerful potential to eliminate frost. In this study, we investigated to observe the surface which has line and space on it by ESEM (Environmental Scanning Microscope). The equipment gives us to make better to understand the initial frost growth in the micro scale.

A new objective lens actuator for an ultra-slim type Blu-ray Disc drive was developed. The actuator has a configuration in which two objective lenses mounted on a holder of the moving part are aligned in the radial direction of the disc. This radial direction layout of two lenses reduces the distance in the tangential direction between each objective lens center and the gravity center of the moving part. Therefore, the amplitude at the pitching mode resonance frequency can be decreased. Calculated pitching phase deviation of the developed actuator is under 15° in the conditions of driving force center displacement of 0.3 mm, gravity center displacement of 0.05 mm, and objective lens center displacement of 0.1 mm.

Adhesively bonding structure for a beam splitter was proposed to offset effects of other optical elements on the position deviation of a beam spot on a photodetector with change in ambient temperature. The proposed structure has four slopes circumferentially by 90° along the upper edge of pedestal part. The thickness of outer circumferential part of the adhesive layer, which is applied between the beam splitter and the pedestal part, varies 4-fold symmetrically. This structure generates interfacial thermal stress at boundary of slopes in the tangential direction with ambient temperature change and results in tilting the beam splitter in the yaw direction. Measured results showed that a cubic glass, which was adhesively bonded to 4-fold symmetrical pedestal part of an aluminum block, was tilted as predicted. Calculated results identified that the tilt amount and direction of the beam splitter can be arranged by tuning the depth and direction of slopes.

Recently, an ultra-compact piezoelectric micro-blower has been developed to use for general purpose. The example of application includes a cooling of electronic device using the forced convection heat transfer. In this report, piezoelectric micro-blowers are controlled by a microcomputer to force a vibration. The basic characteristics such as frequency and PWM performances have been studied to control the blower. The flow rate exhausted through the blower was estimated by using the velocity obtained from a MEMS flow sensor. A three-terminal regulator is introduced as the example of heated electronic device. The temperature on the surface of device was measured by a radiation thermometer. It was confirmed that the temperature on device can be apparently controlled by the flow from the blower.

We report on an attempt to realize direct visualization of the secondary flow in the planes parallel to the disks in a rotating flow driven by corotating disks mounted in a non-axisymmetric enclosure. The flow is based on the geometry of a hard disk drive used as information storage device. We developed a flow visualization system based on refractive index matching and Sheimpflug principle. The former allows undisturbed transparent view of whole the flow field without reflection and diffraction, while the latter provides sharply focused images at a tilted observation angle. The combination of these two techniques realized a direct visualization of the flow in the vertical planes for the first time. They allows in investigation of the secondary flow. We examined the secondary flow observed on two measurement planes vertical to the disk surfaces in the flow. The resulting behavior was consistent to the one reported in the past studies by other researchers. Further improvement of the image quality is required toward quantitative analysis of the flow.

In the hard disk drive (HDD), the high-speed rotation of the disk generate turbulent air flow. The turbulent flow causes vibration of the disks and RW arm. The flow induced vibration (FIV) is a major obstacle in improving the performance and reliability of the HDD. Therefore, the investigation on the details of the flow structures and its relationship with FIV are of great engineering importance. In this research, fluctuating pressure measurement on the inner wall of simplified HDD model was performed changing arm insertion angle. Accompanying changes in the arm insertion angle, changes in the flow structure and in the frequency of the pressure fluctuation spectrum were confirmed.

In this study, we applied the Hilbert-Huang transform (HHT) to the time series of the torque exerted on the carriage arm, which is calculated using finite element analysis. Then, a frequency analysis using FFT was conducted and compared with the HHT results. Comparing the both spectra, the results confirmed that, in the Fourier spectra, the energy of the non-stationary phenomenon, whose frequency and amplitude are fluctuating at a specific frequency, diffuses over a wide frequency-band, and that forms the broadly expanded spectra, especially at low frequencies. Therefore, it is necessary for more precise head positioning to decrease torque-fluctuations due to non-stationary phenomena, such as a vortex shedding around an arm, which are not always observed in the power spectrum obtained by the FFT analysis.

Because hard-disks rotate at high rotational speed inside hard-disk drives, air flow causes flow-induced vibration to of carriage, which causes a head-positioning error. Therefore, it is necessary to suppress the flow-induced vibration to improve the positioning error. In a previous study, it is reported that a linear protrusion structure put on the leading edge of the carriage arm was improved by approximately 10%. However, its mechanism is unknown. In this study, we considered the effect of the linear protrusion on a disturbance torque of the carriage using Hilbert-Huang transform (HHT).

This paper deals with the influence of surface contamination on the friction of rubber rollers. The powder or lint of paper which adhered onto the rollers after paper feed is one of the predominant causes of paper jams but the mechanism has not been understood. The purpose of this paper is to clarify the relationships between the friction force and the real contact area of papers and contaminated rubber rollers. Carrying out paper feeding tests by using a commercial multifunction peripheral, we tested different types of papers produced by different manufacturers. The tests have been done with combinations of different manufacturer's papers and different kinds of roller materials. Observations of the real contact area clarified that the roller surfaces covered with paper powders reduces the friction coefficient. Finally, we proposed a mechanism of paper jams caused by paper powders.

This report describes basic study of paper attitude during conveyance between rollers with unequal speed. The nip transport mechanism with a pair of rollers is widely used in many devices, such as automated teller machines (ATMs), printing machine, and so on. In such machines, a paper is sometimes nipped by two pairs of rollers of the unequal rotary speed. In such cases the paper attitude during conveyance is likely to change. In this report, the parameters that affect the paper attitude during conveyance between rollers with unequal speed are found. And the influence are found by the observation of the paper attitude in actual transport.

We developed equipment for direct measurement of viscoelastic characteristics in high-frequency range without applying the time temperature superposition principle. We proposed the first resonance compensation method to know viscoelastic characteristics in the high-frequency range. The result confirmed that the directly measurement obtained using the proposed equipment and compensation method reflect accurate viscoelastic characteristics up to 6.5kHz with less than 8.2% error.

In recent years, attention has been paid to a polymer ultra-thin film having a film thickness controlled to several tens of nanometers or less. Nanosheets have various excellent characteristics such as high adhesiveness and high flexibility, and they are expected to be applied to medical fields and the like. In the future, mass production and high functionality of nanosheets are indispensable for developing in various fields. First, in mass production of nanosheets, we examined the use of water-soluble film as a substrate. By using the water-soluble film, it is possible to omit one step from the conventional manufacturing method in the process of manufacturing the nanosheets. We also studied the use of mesoporous silica in enhancing the functionality of nanosheets. Mesoporous silica has various functions and can be expected to exert a large effect by combining with nanosheets. In this study, mass production of nanosheets using water-soluble film and high functionalization by mesoporous silica were investigated.

This paper deals with an active feedback control of leakage flow induced sheet flutter using VCM (Voice Coil Motor) control devices. The active feedback control is conducted by using VCM with plate as control actuators for changing inlet width of the passage. As a result, it is indicated experimentally that the leakage flow induced sheet flutter is suppressed by the proposed active control technique.

This paper presents an active control to suppress a flow-induced sheet flutter in a rectangle passage using fluid suction and blowing. A flexible sheet as a controlled object is supported at only one end in the passage. The sheet flutter is suppressed by the active control using fluid suction and blowing from a loudspeaker. The loud speaker is driven with changing a gain and a phase-shift between the displacement of the sheet and the pressure by fluid suction and blowing. It is indicated experimentally that the proposed control technique suppresses the sheet flutter effectively and increases the critical flow velocity by about 50%.

In recent years, as a manufacturing technology of a flexible device, a print electronics technology attracts attention. However, mass production of flexible devices is required, and improvement of mass productivity is required. Therefore, it is expected to introduce a roll-to-roll production system which carries out processing while supporting and conveying a web using a frictional force with a roller. In the past research, we improved the trouble during transportation, so we tried to fabricate a flexible pressure sensor using the printing method that can be introduced into this method. First, attempts were made to fabricate a flexible pressure sensor by printing and firing a piezoelectric element or a conductive ink using an inkjet apparatus or a gravure printing apparatus. In addition, printing accuracy was measured according to conveyance conditions by printing on a mat coated paper conveyed with an ink jet device attached to a conveying device.

In this study, we examined the fabrication of polymer ultra-thin films(nanosheets) using a micro gravure printing method. Conveying speed of the plastic film substrate, the concentration of solution, rotating speed of the micro gravure roll ware investigated experimentally for effects on the film thickness of the nanosheets. And, we evaluated the Young's modulus of the nanosheets were fabricated, also investigated in detail the physical properties such as flexibility and surface roughness, futheremore, We measured the frictional force between the nanosheet and the skin. As a result, it was found that the frictional force increases as loading load increases. Moreover, it was found that the present nanosheet has sliding property.

To examine thermo-molecular gas film lubrication (t-MGL: thermo-Molecular Gas-film Lubrication) characteristics with nonuniform temperature distributions at the disk or slider surfaces at flying height less than several tens nanometers, we proposed the quasi-free-molecular t-MGL (t-MGLqfm) equation, which has the gas temperature in the free molecular limit defined by temperatures and accommodation coefficients of the disk and slider. Moreover, the influence of accommodation coefficients of the proposed t-MGLqfm equation was analyzed i) by comparing with the free molecular t-MGL (t-MGLfm) equation, ii) by introducing the Green function method and iii) by analyzing dynamic characteristics in an infinite bearing number approximation.

Recently small devices are developed due to the development of mechanical technology. The head/disk interface (HDI) in hard disk drives is one example of the small device. In recently developed magnetic storage systems, the spacing between the flying head and the disk has been drastically reduced to less than a few nm to facilitate ultra-high density recording. Furthermore, magnetic interference between adjacent data tracks is becoming significant by reducing the spacing between the flying head and the disk. For that reason recording media with grooves such as discrete track media (DTM) and bit-patterned media (BPM) are considered to be some of the most promising media for achieving ultra-high densities. The stresses in elastic body are changed due to the distribution of materials on the disk surface. In this paper, we established an analysis method of stresses in elastic body due to molecular interaction with periodic distribution based on Mindlin solutions.

Measurements of surface energy are very important for surface science and engineering, and therefore have been studied by many researchers. Though the effects of surface roughness on reduction of surface energy have been discussed statistically by Greenwood, Persson et al., few deterministic researches can be found. In this study, we developed an experimental system that can measure the surface force and the surface roughness at the same position. The effects of the surface roughness on the reduction of the surface energy were clarified deterministically using the newly developed system.

This paper describes various important findings of surface force between head and disk calculated from adhesion asperity contact theory. The theoretical formulation of surface pressure and surface force applied to thermal-flying-height-control slider is first explained briefly. From calculated results, it was found that adhesive surface force becomes insensitive to the change of lubricant thickness at a bond ratio of 0.85 and that the maximum adhesion force becomes minimum at 0.6 nm lubricant thickness. This suggests the next target of lubricant thickness for higher density magnetic disk. The surface energy versus lubricant thickness obtained from the surface pressure equation shows good compatibility with experimental results. It is also found that static instability of pico-slider due to vdW adhesion force and dynamic instability due to meniscus force can be consistently understood from this surface force theory.

We constructed coarse-grained (CG) models for hematite surfaces, dodecane lubricating oil, and stearic acid additive. Compared with all-atom models, these CG models allow for molecular dynamics (MD) simulations with comparable accuracy and 40 times faster speed. Using the CG models, we performed MD simulations for confined shear of lubricating oil by solid surfaces bearing physically adsorbed additive films. In contrast to the case of smooth sliding surfaces, desorption and re-adsorption of additive molecules were observed at the convex portions of corrugated sliding surfaces. This demonstrates that roughness of sliding surfaces largely influences the dynamic behavior of additives in lubricating oil.

Hard disk lubricant plays an important role in the head-disk interface and has a great influence on the reliability of the hard disk. And, heat assisted magnetic recording (HAMR) was established to obtain higher recording density. The lubricating film on the hard disk should be stable all tribological properties in order to establish HAMR. However, there are problems that laser irradiation evaporates the lubrication film and transfers it to the magnetic head. In this paper, we analyzed the head smear that transfers from tha lubricant film by TOF - SIMS and investigated the mechanism of lubricant decomposition and transfer to the head.

We have developed a controller design method for dual-stage actuator systems in hard disk drives with Robust Bode (RBode) plot. The RBode plot represents robust performance criterion with gray area on the Bode plot. By using the RBode plot, control engineers can easily design a controller which satisfy a robust performance with visualized guidelines. In this study, we designed an H controller for the dual-stage actuator system, and an improved H controller with RBode plot. Simulation results for a track-control in HDD show the validity of the proposed method.

In this paper, an experimental system is developed to analyze external forces in precision rotating machineries. Dynamics of the rotating machineries depends on the external forces synchronous with rotating speed of a rotating shaft such as unbalanced forces, oil film forces at a journal bearing, and seal contact forces. Moreover, characteristics of the external forces are dependent on rotating orbit of the rotating shaft. Therefore, analyzing the characteristics is required on the various rotating orbits for developing the rotating machinery. The proposed system can realize the various rotating orbits and analyze the external forces by using the adaptive feed-forward cancellation. Experimental results indicate the effectiveness of the proposed system.

P-PI controller is often used for motor positioning system. It composes a cascade control system, which has inner velocity loop and outer position loop. P-PI controller is analyzed to have a Proportional element, Integral element and Differentiation element, and it can be classified a kind of a PID controller. We compare P-PI controller with PID controller in a practical condition in which the system has a calculation delay, using limited pole placement method which the author proposed. It becomes clear that P-PI control system has a constrain of pole assign of the closed loop. Improved system with feedforward controller is investigated to have no constrain of pole zero assign.

Recently, service robots are introduced at commercial facility and office. When those wheel type mobile robot moves each floor of the building, elevator is effective mean. Research has been proposed to operating elevator button for autonomous mobile robot. Most researches use robot with multiple degrees of freedom, and the robot's system is complicated. In this paper, we propose method which autonomous mobile robot operate the elevator button with minimum degree of freedom.