Yasuhiro Kakinuma

Keio University, Edo, Tōkyō, Japan

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Publications (63)28.75 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To realize ultimately efficient signal processing, it is necessary to replace electrical signal processing circuits with optical ones. The optical micro-resonator, which localizes light at a certain spot, is an essential component in optical signal processing. Single-crystal calcium fluoride (CaF2) is the most suitable material for a highly efficient optical micro-resonator. The CaF2 resonator can only be manufactured by ultra-precision machining processes, because its crystal anisotropy does not allow the application of chemical etching. However, the optical micro-resonator's performance depends definitely on the surface integrity.
    Precision Engineering. 11/2014;
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    ABSTRACT: The suppression of chatter vibration is required to enhance the machined surface quality and to increase tool life. In this study, a new, conceptually active approach for chatter suppression in machining is proposed. The hybrid control method developed by applying sensorless force control with a disturbance observer enables the simultaneous and independent control of the position trajectory and band-limited forces. The proposed method is introduced to the carriage of a prototype desktop-sized turning machine, and the ability to suppress chatter is evaluated by end-face cutting tests. The results demonstrate that actively controlling a band-limited force leads to the avoidance of chatter.
    CIRP Annals - Manufacturing Technology 01/2014; · 2.25 Impact Factor
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    ABSTRACT: To achieve maximally efficient signal processing, an electrical signal processing circuit needs to be replaced withan optical one. Optical micro-resonators, storing light at certain spots, areessential for optical signal processing. Single-crystal Calcium Fluoride (CaF2) is the most suitable materialfor highly efficient optical micro-resonators, and a resonator made of CaF2can be manufactured by ultra-precision machining. However, the performance of such optical micro-resonators depends on its surface integrity. In this study,therelation between the crystal anisotropy and surface integrity after ultra-precision cutting was investigated. The most difficult point in the cylindrical turning of a crystalline material is thatthe crystalline plane and the cutting direction constantly vary. We analyzed crack initiation and surface integrity of the entiremachined surface from the perspective of slip system and cleavage. Subsurface damage was also observed by using the TEM and X-ray analyzersfor more efficient manufacturing of optical micro-resonators.
    Procedia CIRP. 01/2014; 13:225–229.
  • R. Koike, Y. Kakinuma, T. Aoyama
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    ABSTRACT: Tool fracture detection is important to avoid tool breakage and ensure cutting accuracy. However, conventional tool condition monitoring methods use additional sensors that are expensive, increase the failure rate, and reduce the machine-tool stiffness. This study proposes a novel in-process method to detect tool fracture based on disturbance observer theory. It uses only servo information in a ballscrew-driven stage control system. Furthermore, a rotational digital filter is developed and applied to drilling tests to enhance the detection accuracy. Tool fracture is successfully detected without any external sensors by the proposed method.
    CIRP Journal of Manufacturing Science and Technology 01/2014; 7(3):177–184.
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    ABSTRACT: Disturbance observation is a sensorless process monitoring technique that has not yet been applied to the monitoring of tool collision in the use of machine tools. This paper presents a monitoring algorithm that detects collisions that involve the breakage of drills through observation of the disturbance force change rate. A comprehensive experimental study of diverse operator-induced collisions was conducted to analyze the collision detection potential of the disturbance observer. It was found that collision monitoring by the disturbance observer is more sensitive and responsive than that using a sensorless jerk observer.
    CIRP Journal of Manufacturing Science and Technology 01/2014;
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    ABSTRACT: With the development of virtual reality (VR) technology, many applications require force display systems. However, existing products are not widely used owing to their inconvenient fit and the possibility that the devices may inflict injuries on the user. This study aims to develop a VR suit that can display a force to each joint. The force is generated by a functional material, electrorheological (ER) gel. In this paper, we discuss the development of a device that attaches to the arm, and evaluate the usefulness of the ER gel wearable brake.
    2013 IEEE International Conference on Mechatronics and Automation, Takamatsu, Japan; 01/2013
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    ABSTRACT: This investigation reports the physical characteristics of electrorheological (ER) gels, which are a type of functional material having controlled surface friction. We previously developed slip clutches using ER gels sandwiched between electrodes, and verified their responses and controllability. We newly report the temperature and shear rate characteristics of ER gel in this study because the input and output electrodes of the clutch continuously slip past each other. While the temperature of ER gels increased when energized, the shear stress hardly changed. Instead, wearing and adaptation to the electrode affect the property. The shear rate hardly affected the shear stress in the high-shear-rate region. Conversely, the shear stress depended on the shear rate in the lower region.
    Journal of Physics Conference Series 01/2013; 412:012013.
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    ABSTRACT: The three-dimensional CO2 dissolution process through a gas–liquid interface in microfluidic devices was investigated experimentally, for the precise control of CO2 dissolution. The gas dissolution was evaluated by using confocal micron-resolution particle image velocimetry (micro-PIV) combined with laser induced fluorescence (LIF), which has the ability to measure the velocity and dissolved CO2 concentration distribution in a liquid flow field. The measurement system is based on the confocal microscope, which has excellent depth resolution and enables visualization of the three-dimensional distributions of velocity and dissolved CO2 concentration by rendering two-dimensional data. The device is comprised of a polydimethylsiloxane chip, whose microchannels were fabricated by using a cryogenic micromachining system. The width and depth of the liquid flow channel are larger than those of the gas flow channel. This is due to the need for decreasing the width of the gas–liquid interface and increasing the hydraulic diameter of the liquid channel, whose conditions generate a static gas–liquid interface. The experiments were performed for three different liquid flow conditions corresponding to Reynolds numbers of 1.0 × 10−2, 1.2 × 10−2 and 1.7 × 10−2, and the gas flow rate was set to be constant at 150 μL/min. The LIF measurements indicate that an increase in the Reynolds number yields a decrease in dissolved gas in the spanwise directions. Furthermore, molar fluxes by convection and diffusion were evaluated from the experimental data. The molar fluxes in the streamwise direction were at least 20 times as large as those in the spanwise and depthwise directions. This reveals that an increase in momentum transport in the spanwise and depthwise directions is an important factor for enhancing mass transfer in the gas–liquid microchannel flow.
    International Journal of Heat and Mass Transfer 05/2012; 55(s 11–12):2872–2878. · 2.52 Impact Factor
  • S.saito, Y.kakinuma, T.aoyama, K.tanaka, H.anzai
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    ABSTRACT: Electro-rheological Fluid (ERF) is the functional fluid that can change its viscoelastic property by applying electric field. However, ERF shows the sedimentation of the ER particles in long time use, and it caused the unstable ER effect. The Gel-structured ERF (ERG) has been developed to solve this problem. When a metallic flat plate is placed on the ERG sheet, ERG shows the high shear force due to the occurrence of the contact between the gel and the plate in response to the applying electric field (ERG effect). ERG effect can be obtained not only for metallic materials but also non-metallic materials by applying the one-sided electrode, and the ER effect is supposed to be considerably influenced by the material and geometrical properties of flat plate on the ERG sheet. In this study, the influences of the material and geometrical properties of sliding plate are experimentally analyzed from the viewpoint of the relative permittivity, surface roughness and flatness, and the design instruction for the selection of materials and their geometrical issues are proposed.
    International Journal of Modern Physics B 01/2012; 21(28n29). · 0.46 Impact Factor
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    Y. Kakinuma, T. Kamigochi
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    ABSTRACT: Precise tool length measurement and work coordinate setup is technically a difficult operation which generally requires a manual adjustment and takes long time. Contact of cutting edge of a micro tool is conventionally detected by laser, vision sensor, acoustic emission sensor (AE sensor) and so on. However, those techniques are necessary to install additional sensors and equipments to a machine tool. In addition, tool setting technique depends on an engineer's skill. Therefore, skill-independent technology of tool setting is desired. In this study, we propose an automatic detection methodology of the tool contact by cutting force observer. Moreover, applying the developed detecting technique of the tool contact, automatic micro drilling system without tool setting is developed. Its validity is verified through glass micro drilling tests.
    Procedia CIRP. 01/2012; 2:44–48.
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    ABSTRACT: The evaluation technique of gas permeable characterization has been developed for an increased efficiency of gas–liquid chemical reactions and high accuracy of environmental diagnosis. This technique enables us to measure spatial distributions of velocity and dissolved gas concentration by utilizing confocal micron-resolution particle image velocimetry combined with a laser-induced fluorescence technique. Microfluidic devices with gas permeability through polymer membranes are composed of a cover glass and a polydimethylsiloxane (PDMS) chip with the ability to permeate various gases, since PDMS is an elastomeric material. In the chip, microchannels are manufactured using a cryogenic micromachining system. The gas permeation is dominated by several factors, such as the gas and liquid flow rates, the membrane thickness between the gas and liquid flow, and the surface area of the membranes. The advantage of the present device is to realize the control of gas permeability by changing the surface roughness of PDMS, because the cryogenic micromachining enables us to control the surface roughness of microchannels and an increase in roughness yields an increase in the surface area of membranes. The experiments were performed under several conditions with a change in the gas flow rate, the PDMS membrane thickness and the surface roughness, which affect the gas permeation phenomena. The spatial distributions of velocity and dissolved gas concentration were measured in the liquid flow fields. The results indicate that the velocity-vector distributions have similar patterns under all experimental conditions, while the dissolved gas concentration distributions have different patterns. It was observed that the gas permeability through PDMS membranes increased with an increase in gas flow rates and surface roughness and with a decrease in membrane thicknesses, which is in qualitative agreement with membrane theory. The important conclusion is that the proposed technique is suggested to have the possibility of evaluating the characterization of gas permeable microfluidic device through membranes.
    Journal of Micromechanics and Microengineering 01/2012; 22(6). · 1.79 Impact Factor
  • Yasuhiro Kakinuma, Sinya Kidani, Tojiro Aoyama
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    ABSTRACT: Microfluidic chips with micro- or nanoscale channels are currently in great demand. PDMS (polydimethylsiloxane), a viscoelastic polymer, has high transparency and good chemical stability, making it a suitable substrate material for such chips. However, it is difficult to machine PDMS by conventional cutting processes because of its high elasticity and adhesion. We proposed the cryogenic micromachining of PDMS completely immersed in liquid nitrogen as a direct process to fabricate customized 3D nano/microfluidic chips precisely. In this study, the feasibility of ultra-precision cryogenic machining is studied as an extended nanofabrication process.
    CIRP Annals - Manufacturing Technology 01/2012; 61(1):79–82. · 2.25 Impact Factor
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    ABSTRACT: This study is concerned with the development of an Electro-Rheological (ER) Gel Linear Actuator (ERGLA) as the principle component of a high torque controllable clutch that has applications in robots that coexist with humans. Applying the ER gel to clutches in force transmission assembly decreases the inertia and mechanical limit of the maximum speed, enabling keeping high controllability. This paper focuses on enlarging the output torque of the clutch with ER gels, which is a the main part of the ERGLA.
    Mechatronics and Automation (ICMA), 2012 International Conference on; 01/2012
  • Satoshi Ikeda, Yasuhiro Kakinuma
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    ABSTRACT: Plastics are regarded as proper materials for microfluidic chips, and, in particular, biodegradable plastics will be more appropriate from the viewpoint of environmental friendliness. In addition, when they are utilized as chip substrate, biochemical machining can be applied. Biochemical machining is a process, which utilizes enzymatic biodegradation. This paper describes studies on application of biochemical machining to nanofabrication of poly(l-lactic acid) (PLLA), which is one of the most widely used biodegradable plastics industrially. The degradation performance of enzyme (proteinase K) was experimentally evaluated to extrapolate a suitable condition for nanofabrication. Additionally, in order to make arbitrary channels with nano-order depth on PLLA, mask fabrication was proposed. It is a fabrication method to control degraded regions and obtain desired shapes with a mask, which has penetrating grooves. Using this method, we achieved fabrication of straight grooves with nano-scale depth. In conclusion, it is clear that biochemical machining can realize an effective process of arbitrarily shaped nanogrooves on PLLA.
    Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology - PRECIS ENG. 01/2011; 35(3):440-446.
  • Yasuhiro Kakinuma, Yui Sudo, Tojiro Aoyama
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    ABSTRACT: Suppression of chatter vibration is required to improve the machined surface quality and enhance tool life. For monitoring the chatter vibrations, additional sensors such as acceleration sensors are generally used, which results in high costs and low reliability of the machine tools. In this study, a novel in-process method to detect chatter vibrations in end milling is developed on the basis of a disturbance observer theory. The developed system does not require any external sensors because it uses only the servo information of the spindle control system. Self-excited and forced chatter vibrations are successfully detected.
    CIRP Annals - Manufacturing Technology 01/2011; 60(1):109-112. · 2.25 Impact Factor
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    ABSTRACT: ER gel exhibits various adhesive characteristics according to the applied electric field. This characteristic is called the EA effect. The results of a recent study reveal that the EA effect also occurs in a vacuum. Therefore, it is expected that ER gel can be applied to a chucking or damping device in a vacuum process. However, the characteristics of ER gel in a vacuum have not been sufficiently clarified. The purpose of this study is to experimentally evaluate the characteristic of ER gel in a vacuum. The performance of an ERG fixture element used for a silicon wafer in a vacuum is evaluated through shearing tests. The experimental results indicate that the ER gel demonstrates satisfactory performance in a vacuum. Moreover, the outgas released from the ER gel in a vacuum is evaluated, and the influence of the degassing time on the outgas is investigated.
    Journal of Intelligent Material Systems and Structures 01/2011; 22(15):1699-1705. · 1.52 Impact Factor
  • Electro-Rheological Fluids and Magneto-Rheological Suspensions - 12th International Conference; 01/2011
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    Y. Mizumoto, T. Aoyama, Y. Kakinuma
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    ABSTRACT: Calcium fluoride (CaF2) has a wide range of change of refractive index and permeability of wavelength from vacuum ultraviolet range to infrared range so that it is utilized for lenses or prisms. CaF2 has been fabricated using conventionally grinding and polishing combined with interferometry and local surface correction to form the desired flat, sphere or aspherical surface. In this study, the mechanical properties and crack initiation on the (100), (110) and (111) planes of CaF2 are examined by nanoindentation and micro-Vickers hardness tests. In addition, brittle-ductile transition is investigated by performing an orthogonal cutting test with ultraprecision machine tool. The results of these tests show that the critical depth of cut remarkably changes on the basis of the crystal orientation on each plane. We have discussed these changes from the viewpoint of slip system and cleavage.
    Procedia Engineering 01/2011; 19:264–269.
  • Yosuke Naito, Tojiro Aoyama, Yasuhiro Kakinuma
    Electro-Rheological Fluids and Magneto-Rheological Suspensions - 12th International Conference; 01/2011