Yasuhiro Kakinuma

Keio University, Edo, Tōkyō, Japan

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Publications (68)40.62 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; · 1.40 Impact Factor
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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; · 2.54 Impact Factor
  • Ryo Koike, Yasuhiro Kakinuma, Tojiro Aoyama, Kouhei Ohnishi
    Procedia CIRP. 01/2014; 14:478-483.
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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: 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 02/2013; 412:012013.
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    ABSTRACT: The buffing process for finishing an automobile's body is still done manually, and the final surface quality of the body depends on the skill and technique of the worker. To automate buffing, not only tool path control but also precise and fast force control is required. In this study, a novel methodology based on the sensor-less force control technique and the quarry matrix capable of the mode decoupling is proposed for a parallel mechanism polishing machine to control x–y trajectory, tool posture, and polishing force in z-direction, and its validity for automated buffing is verified.
    CIRP Annals - Manufacturing Technology 01/2013; 62(1):379–382. · 2.54 Impact Factor
  • Ken'ichi Koyanagi, Yasuhiro Kakinuma
    Journal of the Robotics Society of Japan. 01/2013; 31(5):465-468.
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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
  • Ryo Koike, Yasuhiro Kakinuma, Tojiro Aoyama
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    ABSTRACT: Detection of a tool fracture is necessary to ensure cutting accuracy and to avoid a tool breakage because tool fracture is one of the significant prediction signals of the tool breakage. For monitoring the tool condition, generally additional sensors are used. However using these sensors causes high cost and increase of failure rate. In this paper, a novel sensor-less detection method of tool fracture in drilling process is proposed on the basis of a disturbance observer theory. It is applied to the x-y stage of the machine tool. The proposed method requires no external sensor because it uses only the servo information of the spindle control system. Since structures of normal drills with two floats are symmetrical with respect to a point, theoretically the cutting force in the x and y directions does not work. When the drill is fractured, its structure becomes asymmetry so that unbalanced forces would exert in the x and y directions at intervals of the spindle speed. Therefore, it is possible to detect a tool fracture by the frequency analysis of estimated disturbance force with a wavelet transform. The experimental results show that the proposed method is available for detection of the small tool fracture effectively.
    Key Engineering Materials 11/2012; 523-524:439-444.
  • Takao Kubo, Yasuhiro Kakinuma
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    ABSTRACT: Smart materials have been developed in many leading technologies. Smart material is a material that gives a specific reaction to the change and stimulus of the external environment such as light, heat and electromagnetic fields. Electro-rheological Gel (ERG) is one smart material. ERG changes its surface adhesive properties rapidly according to the intensity of the applied electrical field. This unique property is named Electro-adhesive effect (EA effect). In this research, as a novel electro-adhesive film which is replaced with ERG, Electro-adhesive film with micro mesh sheets is developed and named EAMS. Furthermore, it is proved that the developed film using the mesh sheet produces the EA effect and that the performance of EAMS is enhanced according to the increase of the open space and the number of layers.
    Key Engineering Materials 06/2012; 516:222-227.
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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 06/2012; 22(6). · 1.73 Impact Factor
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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
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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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    Ryo Koike, Yasuhiro Kakinuma, Tojiro Aoyama
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    ABSTRACT: Detection of tool fracture is important to avoid tool breakage and ensure cutting accuracy. Though additional sensors are generally used for monitoring a tool condition, installing them causes high cost and increase of failure rate. In this study, a novel in- process method to detect a tool fracture is proposed on the basis of a disturbance observer theory. It uses only servo information in a ballscrew driven stage and never requires external sensors. Furthermore, a rotational digital filter is invented and applied to drilling tests to improve the detection accuracy. A tool fracture is successfully detected by the proposed method.
    Procedia CIRP. 01/2012; 4:52–57.
  • 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. · 2.54 Impact Factor
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    ABSTRACT: This paper deals with the use of two types of ultrasonic-assisted micromachining methods for obtaining longer tool life and higher machining efficiency in the micromachining of hard and brittle materials. USV drilling is drilling that is aided by ultrasonic vibration in the direction axial to the tool. Cavitation machining is a method is aided by ultrasonic vibration of the cutting fluid. We investigated the effects of USV, cavitation, and their combination on the micro drilling of SiC. Experimental results clearly showed an improvement in tool life and a reduction in tool wear. Furthermore, the accuracy was improved.
    Procedia CIRP. 01/2012; 1:342–346.
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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
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    ABSTRACT: Chatter vibration can be monitored by using external sensors such as acceleration sensors and dynamometers. However, from the viewpoint of reliability, using external sensors leads to an increase in failure rate. Therefore, we developed a disturbance observer theory–based method for the detection of chatter vibration, and confirmed its validity experimentally. The developed method does not require the use external sensors. In this study, a system for the in-process suppression of chatter vibration is developed by applying the abovementioned detection method. In a milling test, conducted to verify the developed system, it was found that chatter vibration was successfully suppressed by automatic adjustments to the cutting conditions.
    Procedia CIRP. 01/2012; 1:44–49.