Y. Takemura

Kitakyushu University, Kitakyūshū, Fukuoka, Japan

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Publications (41)51.42 Total impact

  • Source
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    ABSTRACT: This paper presents some of the technical elements of the "Musashi robot" developed for the RoboCup Middle-Size League. Since there are some solutions that are common to many teams, only the most recent developments and interesting research studies that distinguish our multi-robot system from others and show our contribution to improving Middle-Size League performance are presented. One of our research objectives is to investigate the proper solutions towards realizing the idea of the human-robot interaction in soccer. Three considerable topics that they can play significant role in this content are Robot-Reliability, Robot-Maneuverability and Robot-Human Safety. In the following sections, our approaches to realize this idea, in different and interesting ways, are presented.
    01/2011;
  • Y. Takemura, K. Ishii
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    ABSTRACT: One of important subjects for mobile robots is the vision based decision making system, where the color constancy is big problem for robots which use color property to recognize environments. We have been working on color constancy vision algorithms using bio-inspired information processing as creatures can recognize color and shape of objects even if there exits a large change of light conditions in outdoor environments. We evaluate the performances of color recognition using brain-inspired processing algorithms such as Self-Organizing Map (SOM), modular network SOM (mnSOM) and Neural Gas (NG). In this paper, the experimental results in dynamical conditions are discussed.
    01/2010;
  • Y. Takemura, KAZUO ISHII
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    ABSTRACT: Underwater robots and underwater machines are counted on helping the salvage procedure, escaping prevention of pollution, lifesaving at sea, scientific exploration in the ocean and so on. In the underwater robot, therefore, Autonomous Underwater Vehicles (AUVs) have been developed actively during recent year. However, AUVs have various problems which should be solved such as motion control, acquisition of sensors' information, behavioral decision selflocalization and so on. Regarding to consider about these problems, robot should be learning on selforganizing about relation ship to own status, environment and behaviors. In this paper, a new self-organizing controllers system for AUVs using modular network SOM proposed by Tokunaga et al., is described. The proposed control system is developed using Recurrent Neural Network (RNN) type mnSOM. And, we report that the control system is implemented into the AUV “Twin-Burger”.
    01/2010;
  • Y. Takemura, K. Ishii
    [Show abstract] [Hide abstract]
    ABSTRACT: One of important subjects for mobile robots is the vision based decision-making system with environmental recognition. In order to extract features from obtained images, how to realize color constancy by adjusting color property is the important technical issue. We have been working on color constancy vision algorithms using bio-inspired information processing methods as self-organizing map (SOM), modular network SOM (mnSOM) and neural gas (NG). In this paper, we introduce the color constancy algorithms to a mobile robot platform for RoboCup middle size league and evaluate the performances through a vision based self-localization problem in various light conditions.
    Systems, Man and Cybernetics, 2009. SMC 2009. IEEE International Conference on; 11/2009
  • Yasunori Takemura, Kazuo Ishii
    [Show abstract] [Hide abstract]
    ABSTRACT: One of important subjects for mobile robots is the vision based decision making system, where the color constancy is big problem for robots which use color property to recognize environments. We have been working on color constancy vision algorithms using bio-inspired information processing as creatures can recognize color and shape of objects even if there exits a large change of light conditions in outdoor environments. In this paper, we evaluate the performances of color recognition using bio-inspired processing algorithms such as Self-Organizing Map (SOM), modular network SOM (mnSOM) and Neural Gas (NG). The experimental results in various light conditions are discussed.
    Neural Information Processing, 16th International Conference, ICONIP 2009, Bangkok, Thailand, December 1-5, 2009, Proceedings, Part II; 01/2009
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    ABSTRACT: In this paper, we describe the concept, design and implementation of a series of autonomous mobile soccer robots, named Musashi robots, which are designed referring ISO safety standards and have mechatronics modular architecture. The robots are designed to participate in the RoboCup Middle Size League. Using a modular design philosophy, we show that the selection of a proper moving mechanism, a suitable vision system and a mechatronics modular architecture design can lead to the realization of a reliable, simple, and low cost robot when compared with most car-like robots that include many kinds of sensors and have a complex design structure.
    Journal of Bionic Engineering - J BIONIC ENG. 01/2008; 5:121-129.
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    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we describe the concept, design and implementation of a series of autonomous mobile soccer robots, named ldquoMusashirdquo robot, which have safety design which is based on ISO and a mechatronics modular architecture, to participate in the RoboCup middle-size league. In modularity design methodology, we show that the selection of a proper moving mechanism, a suitable vision system and a mechatronics modular architecture design can lead to realize a reliable, simple, and low cost robot comparing with most of car-like robots including many kinds of sensors and a complex design structure.
    2008 IEEE/RSJ International Conference on Intelligent Robots and Systems, September 22-26, 2008, Acropolis Convention Center, Nice, France; 01/2008
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we describe the concept, design and implementation of a series of autonomous mobile soccer robots, named "Musashi" robot, which have a mechatronics modular architecture, to participate in the RoboCup middle-size league. In this design methodology, we show that the selection of a proper moving mechanism, a suitable vision system and a mechatronics modular architecture design can lead to realize a reliable, simple, and low cost robot comparing with most of car-like robots including many kinds of sensors and a complex design structure.
    Proceedings of the 7th IEEE International Symposium on Computational Intelligence in Robotics and Automation, CIRA 2007, 20-23 June 2007, Jacksonville, Florida, USA; 01/2007
  • Hideki Nakagawa, Yasunori Takemura
    Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology 11/2006; 145(3):412-412. · 2.07 Impact Factor
  • Yasunori Takemura, Masanori Sato, Kazuo Ishii
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    ABSTRACT: The researches on swarm intelligence using many mobile robots have been investigated actively, and the possibilities of cooperative transportation, distributed sensing, survey, collision avoidance, etc., have been discussed. In this research, the concept and specification of a small mobile robot platform “With” aimed at realization of swarm intelligence have been discussed and examined through experiments.
    International Congress Series 01/2006; 1291:273-276.
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    ABSTRACT: Following the 19th IAEA Fusion Energy Conference (Lyon, 2002), (1) three-time progress in the formation of ion-confining potential heights c including a record of 2.1 kV in comparison to those attained 1992–2002 is achieved for tandem-mirror plasmas in the hot-ion mode with ion temperatures of several kiloelectronvolts. (2) The advance in the potential formation gives the bases for finding the remarkable effects of radially produced shear of electric fields Er, or non-uniform sheared plasma rotation on the suppression of intermittent vortex-like turbulent fluctuations. (i) Such a shear effect is visually highlighted by x-ray tomography diagnostics; that is, spatially and temporally intermittent vortex-like fluctuated structures are clearly observed as two-dimensionally reconstructed visual structures for the first time in kiloelectronvolt order ion-cyclotron heated plasmas having a weak shear in GAMMA 10. (ii) However, during the application of plug electron-cyclotron heatings (ECH), the associated potential rise produces a stronger shear (dEr/dr = several 10 kV m−2) resulting in the disappearance of such intermittent turbulent vortices with plasma confinement improvement. X-ray observations also show elongation of a vortex structure from a circular into an ellipsoidal shape, as depicted in H-mode theories, with an outward shift. (3) For the physics interpretations and control of such potential and the associated shear formation, the validity of our proposed theory of the potential formation is extensionally tested under the conditions with auxiliary heating. The data described above fit well to the extended surfaces calculated from our proposed consolidated theory of the strong ECH theory (plateau formation) with Pastukhov's theory on energy confinement.
    Nuclear Fusion 11/2005; 45(12):1650. · 2.73 Impact Factor
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    ABSTRACT: We estimate the influence of the discrepancy of the cross sectional shapes between the magnetic flux tube and the equi-potential surface at the mirror throats of the anchor cell on the radial drift of the plug potential bounce ion. The radial potential profiles are assumed to be Gaussian. It is found that the discrepancy enhances the radial drift of the bounce ion and the spread radial potential profile moderates the enhancement. The radial potential profile of the core plasma is adjusted by controlling the electrostatic potentials of the coaxially separated end plate. It is found that the spread type of radial potential profile is effective for the retardation of the radial transport of the bounce ions.
    Fusion Science and Technology - FUSION SCI TECHNOL. 01/2005; 47:78-83.
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    ABSTRACT: Existence of the bounced ion by the plug potential (PP) bounce ion is essential in order to improve the ion confinement in the tandem mirror. The trajectories of the PP bounce ion were calculated on the assumption that the equipotential surface was slightly deviated from the equilibrium state, and it was found that the radial electric field affected the radial transport of the bounce ion. A charge exchange neutral particle analyzer was located at the inner mirror throat region as a bounce ion measurement device. The energy distribution function of the bounce ion was measured using the device, and compared with the energy distribution function of the end-loss ion.
    Review of Scientific Instruments 10/2004; 75(10):3619-3621. · 1.60 Impact Factor
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    ABSTRACT: An improved gold neutral beam probe system has been developed in order to measure both the potential profile and the electron density profile simultaneously at the central cell of the tandem mirror GAMMA10. A gold film detector was also developed in order to measure the plasma density profile. The yield curves of secondary electrons were measured as a function of the incident angle and electron energy using both the gold neutral beam and ultraviolet ray injection. Time evolution of the plasma line density was measured by adjusting the incident angle and adding a beam chopping method. The result is in good agreement in comparison with the line density measured using a microwave interferometer. It was found that this film detector is very useful for simultaneous measurements of the electrostatic potential and plasma density.
    Review of Scientific Instruments 10/2004; 75(10):3649-3651. · 1.60 Impact Factor
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    ABSTRACT: The beam deflection coefficients to the magnetic field fluctuation using a gold neutral beam probe was examined by numerical simulations. The beam deflection parallel to the magnetic field line was mainly caused by the azimuthal component of the magnetic field fluctuation in a case of the beam passing through the plasma center; on the other hand, the beam passing through the plasma edge was deflected by the radial component of the magnetic field fluctuation because the radial and azimuthal velocity components of the beam depend on the injection angle into the plasma. Then, the coefficients could be described as being the function of the injection angle which indicated the radial position of the ionization point and the measured point. As a result of numerical simulation, the coefficients were estimated to be 0.1 and 1.3 for the radial and the azimuthal components of the magnetic field fluctuation in the case of the beam passing through the plasma center. We also estimated the potential effects on the beam deflection parallel to the magnetic field line by the numerical simulation because the change of the beam energy caused the beam detected point to move. We found the potential effects to be smaller than the sensitivity of the magnetic field fluctuation.
    Review of Scientific Instruments 01/2004; 75(10):3652-3654. · 1.60 Impact Factor
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    ABSTRACT: GAMMA 10 experiments have advanced in high density experiments after the last IAEA fusion energy conference in 2000 where we reported the production of the high density plasma through use of ion cyclotron range of frequency heating at a high harmonic frequency and neutral beam injection in the anchor cells. However, the diamagnetic signal of the plasma decreased when electron cyclotron resonance heating was applied for the potential formation. Recently a high density plasma has been obtained without degradation of the diamagnetic signal and with much improved reproducibility than before. The high density plasma was attained through adjustment of the spacing of the conducting plates installed in the anchor transition regions. The potential confinement of the plasma has been extensively studied. Dependences of the ion confinement time, ion-energy confinement time and plasma confining potential on plasma density were obtained for the first time in the high density region up to a density of 4×1018 m−3.
    Nuclear Fusion 04/2003; 43(5):358. · 2.73 Impact Factor
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    ABSTRACT: A gold film detector was developed in order to measure the plasma density profile by use of the gold neutral beam probe. The detector is a kind of neutral beam detector composed of a rectangular entrance collimator, two sets of grid plates, a gold thin film, a quartz backing, and a microcarbon coated copper plate. The secondary electrons emitted from the gold film were utilized for the neutral beam detection. The yield curves of the secondary electrons were measured as a function of the incident angle and electron energy in both cases of the gold neutral probing beam and ultraviolet ray injection. Time evolution of the plasma line density was measured by adjusting the incident angle and adding a beam chopping method. The result was in good agreement with the line density measured by a microwave interferometer. It was found that this film detector was quite useful in the viewpoint of simultaneous measurements of the electrostatic potential and plasma density profiles. © 2002 American Institute of Physics.
    Review of Scientific Instruments 12/2002; · 1.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: GAMMA 10 experiments have advanced in high density experiments after the last EPS Workshop where we reported high density plasma production by using an ion cyclotron range of frequency heating at a high harmonic frequency and neutral beam injection in the central cell. Recently a high density plasma was obtained with much improved reproducibility than before and without degradation of diamagnetic signal. The high density plasma was attained by adjusting the spacing of the conducting plates installed in the anchor transition regions. Dependencies of particle confinement time, ion energy confinement time and plasma confining potential on plasma density were obtained for the first time in the high density region.
    Czechoslovak Journal of Physics 09/2002; 52(10):1143-1148. · 0.42 Impact Factor
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    ABSTRACT: After the attainment of the density doubling due to the potential confinement, GAMMA 10 experiments have been directed to obtain a high-density plasma with potential confinement and also to study the dependence of the confining potential and confinement time on the plasma density. These problems are important to understand the physics of potential formation in tandem mirrors and also for the development of a tandem mirror reactor. GAMMA 10 experiments have advanced greatly after the Sorrento IAEA Conference, where high-density plasma production by using an ICRF heating at a higher harmonic frequency was reported. Recently, a high-density plasma was attained and the reproducibility of high-density plasma production was much improved by adjusting the spacing of the conducting plates installed in the anchor transition regions. In this paper, we report the production of a high-density plasma and the dependence of the confining potential and confinement time on the density up to a density of 4×1012 cm−3.
    Plasma Physics Reports 01/2002; 28(9):721-726. · 0.66 Impact Factor
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    ABSTRACT: Bouncing ions between the plug potentials play an important role in improvement of the axial confinement in the tandem mirror. We examined the influence of the radial electric field on the trajectories of the ions passed through the anchor cell with nonaxisymmetric magnetic configuration on the assumption that the shape of the magnetic flux tube was shifted from the shape of the equipotential surface of the plasma at the mirror throats of the anchor cells. The discrepancy between the shapes enhanced the radial drift of the bounce ion. Radial potential profile of the core plasma was controlled by adjustment of the radially separated endplate potentials, and it was found that the flattened radial potential profile was effective for the decrease of the radial drift.
    Czechoslovak Journal of Physics 01/2002; 52(10):1135-1142. · 0.42 Impact Factor

Publication Stats

78 Citations
51.42 Total Impact Points

Institutions

  • 2011
    • Kitakyushu University
      Kitakyūshū, Fukuoka, Japan
  • 2006–2011
    • Kyushu Institute of Technology
      • Department of Brain Sciences & Engineering
      Japan
  • 2002–2005
    • University of Tsukuba
      • Applied Physics
      Tsukuba, Ibaraki, Japan
  • 1965–1966
    • Gunma University
      • School of Medicine
      Maebashi, Gunma Prefecture, Japan