Materials Science and Technology
Any enquiries regarding this project should be directed to e-mail: kisoO@me1.go.jp
Current research in the Division of Materials Science and Technology is mainly concerned with the design and evaluation of materials which are durable，reliable，have useful properties in hostile environments，and are compatible with natural ecological systems．
Some current research topics are described below．
Materials Properties
Research on materials properties is focused on damage mechanics and damage mechanisms in advanced structural materials such as composites，ceramics，and functionally graded materials (FGMs）．Topics of interest are as follows：
1）Long term durability of advanced thermoplastic matrix composites
2）Fracture mechanics of advanced titanium alloys and titanium aluminide matrix composites
3）Evaluation of damage tolerance behavior of high performance materials such as intermetallic compounds and advanced carbon/carbon composites
4）Ductile metallic phase toughening mechanisms for brittle materials and their application to ceramic/metal system FGMs
5）Feasibility studies of melt growth composites
（in−situ single crystal eutectic A1203/YAG and Al2O3/GdAlO3 composites）
6）Advanced SQUID and magnetic force microscope（MFM）applications−Characterisation of cryogenic fatigue damage under a high magnetic field 12）
Fig.1 Improvement of fracture toughness for titanium aluminide by high temperature melting point ductile metallic fibers8） Materials Design
Research in materials design has worked towards the improvement of microstructure and properties，and the design of new metallic materials such as intermetallic compounds，titanium alloys for biomechanical applications，superplastic single phase stainless steels，nickel base superalloys，and nanostructured alloys．
In one of these projects，homogenisation of the microstructure of intermetallic TiAl alloy composites by rheocasting was investigated．The solidifying alloy was vigorously agitated by a stirrer rotating at2000−3600 rpm under an argon atmosphere，while ceramic particles were added．Zirconium-rich lamellar grains and titanium-rich and carbon-rich precipitates were formed in rheocast Ti-44wt％Al alloys which included greater than 5vol％ZrC．In rheocast Ti-44％Al-10vol％ZrC alloy，the elongation was 4％ and the tensile strength was 280MPa at 1373K，as shown in the figure．6,7）In other work，We recrystallised a single phase stainless steel （AISI304）and found that the elongation to failure exceeded 600％，and superplasticity was observed．Advanced techniques were also developed to pro duce filaments of the intermeta11ic compound Ni3A1.
Fig.2 The relation between the tensile elongation at room temperature and the ultimate tensile strength at 1373K on the rheocast intermetallic TiAl alloy composites in the present work．
Tribology
The main thrust of the work in the Tribology Division has been the study of eco-tribology, development of new tribomaterials, and novel materials processing using laser technology.
The use of new refrigerants brings with it several important tribological problems, and our research has therefore included extensive investigation of the effects of refrigerants on lubrication. We are currently developing methods to measure the dissolution and diffusion constants of refrigerants in lubricating oils so that estimation of the concentrations of refrigerants in lubricants becomes possible under dynamic conditions. Motivated by the need to protect the environment, we have investigated sliding systems using methanol, ethanol, and water as lubricants. We found that, despite its low viscosity, alcohol is a good lubricant for Silicon Nitride.
Self lubricating composites operating from room temperature up to 1000℃ have been developed. Aluminium Oxide (Al2O3) and Barium Chromate (BaCrO4, BaCr2O4) composites were found to have low friction over this temperature range. Diamond-like carbon (DLC) films have many potential applications and their tribological properties were investigated. It was found that although the friction and wear rates are strongly dependant on environment, DLC films can have low friction and very low wear rate under appropriate conditions.l3)
Fig.3 Effect of temperature on friction coefficient of Al2O3 + 50 vol % BaCrO4 composite
Laser assisted plasma spray techniques and laser assisted gas deposition techniques are under development for the synthesis of high-performance tribo-materials and novel allotrope films. Novel laser technology for the preparation of well-controlled ultra-fine particles using DMA (Differential Mobility Analysis) is also under development. In order to better understand the phenomena associated with laser gas deposition, laser induced ion emission from MgO single crystals was analysed using time resolved mass spectroscopy. We found that ions are emitted from the crystal surface at low laser intensities, before a laser plume develops. As this field develops, technology for assembling the ultra-fine particles into new microscopic structures which have useful optical and electrical properties will be required. Work has therefore also been done on measurement of the state of the plasma field using modified advanced spectroscopic analysis and monitoring techniques.
Experimental work on the fracture and frictional behaviour of rocks under extreme conditions has been carried out to investigate the deformation mechanisms and associated electrical phenomena found in rocks at depth. A series of uniaxial compression tests on granite showed that the temperature dependence of charged particle emission intensity before main failure is consistent with fluctuations in ESR signal intensity from the rock at each preconditioned temperature. The release of electrons from intrinsic trapped centres in minerals in the rock has been suggested as a mechanism for the observed charged particle emission.
Fig.4 Friction coefficient of DLC films in various environments List of Publications(1998) Materials Science and Technology
1) S. Sasaki，Capability of process lubrication for ceramic materials, Proc. 11th Int. Colloquim on Tribology 3 (Jan.1998), pp.1867-1874
2) K. Mizuhara, S. Takahashi, J. Kurokawa, N. Morita and Y. Yoshida, Evaluation of Residual Stresses in Thin Films by Means of micro-Raman Spectroscopy, MRS Symp. Proc. 505(Jan.1998), pp.501-506
3) S. Kano, H. Shimura, Y. Enomoto, N. Aya, N. Ichikawa and H. Iwamoto, Measurement of Transient Electric Charge Signals Induced by a Laser Plasma Plume, Proc. of JCALEO 97 83-1 (Apr. 1998), pp.112-121
4) A. Tanaka, M. Ko, S. Kim, S. Lee and Y. Kumagai, Friction and Wear of Diamond-Like Carbon Films Deposited Using Different Methods under Different Conditions, Diamond Films and Tech. 8-1 (May 1998), pp.51-64
5) Y. Enomoto, K. Ichikawa, M. Tokita, S. J. Dapkunas and D. T. Smith, Precompetitive Processing and Characterization of Functionally Gradient Materials, Cooperating Int.: The U.S.-Japan Civil Industrial Tech. (CIT) Arrangement (May 1998), pp.8-1 〜 8-18
6) K. Ichikawa and Y. Kinoshita, Rheocasting Techniques Applied to Intermetallic TiAl Alloys and Composites, Mater. Science and Engineering A229-240,(Jun.1998), pp.493-502
7) K. Ichikawa, Production and Properties of Copper-Matrix and Intermetallic-Matrix Composite Materials by Rheocasting, Proc. of 5th Int. Conf. on Semi-Solid Processing of Alloys and Composites (Jun.1998), pp.565-572
8) K. Hirano, Improvement of Fracture Toughness for Titanium Aluminide Intermetallic by High Temperature Melting Point Ductile Metallic Fibers, Proc. CIMTFC'98 (Jun.1998) (in press)
9) F. Tamai and K. Hirano, Cyclic Fatigue Crack Growth Characteristics for SiC Whisker-reinforced Alumina Matrix Composite, Danvage and Fracture Mechanics-Computer Aided Assessment and Control-Computational Mech. Pub. (Jun.1998), pp.257-266
10) Y. Kawakami, S. Sasaki and H. Shimura, Synthesis of diamond film by DC plasma coating using ultra-fine carbon particles as an original source material, Surface Modification Tech. 11-11 (Aug.1998), pp.196-202
11) T. Ikeno, S. Sasaki, S. Kano, H. Shimura, Y. Kawakami and Y. Higashiguchi, Coating of molybdenum on C/C composite using laser-plasma hybrid spray, Surface Modification Tech. 11-11 (Aug.1998), pp.403-410
12) T. Suzuki and K. Hirano, Fatigue Damage Analysis of Austenitic Stainless Steel by Magnetic Force Microscope, Proc. of the 12th European Conf. on Fracture I (Sep.1998), pp.97-102
13) A. Tanaka, S. Ogura and R. Murata, Friction and Wear of Plastics Sliding against Diamond-Like Carbon Films, Proc. the First Asia Int. Conf. on Tribology 2 (Oct.1998), pp.569-573
14) A. Tanaka, H. Shimura, A. Yabe and H. Niinou, Excimer Laser Irradiation Effect on Polymer Friction, Proc. Symp. on Lubricating Mater. and Tribochemistry (Oct.1998), pp.119-125
15) S. Sasaki and J. B. Pethica, Effect of surrounding atmosphere on tribological properties of ceramics using nano-indentation method, Proc. of Int. Tribology Conf., AUSTRIB98 (Dec.1998), pp.513-517
Bioengineering
Any enquiries regarding this project should be directed to e-mail: kiso0@mel.go.jp
Bioengineering is concerned with the application of engineering to the biological sciences and medicine. Research in this field at MEL aims to improve our basic knowledge of living beings and apply that knowledge to the development of health care systems. An advanced understanding of biomechanics is a prerequisite for successful research in bioengineering. Mel's research includes the following topics :
1) The biomechanics of bone and muscle
2) Biocompatibility evaluation techniques
3) Development and standardisation of advanced biomaterials
4) Artificial heart development
5) Optical tomography
6) Non-invasive measurement of brain function
7) Novel MRI/S techniques
8) Development of laser ablation techniques
9) Computer aided surgery
Some of these are described below.
Development and standardisation of advanced biomaterials
Several different materials are currently used for body implants. The use of Ti-6%Al-4%V ELI alloy is currently increasing. The biological effects of various metallic ions on the cell growth ratio of fibroplasts L929 and osteoblast-like MC3T3-El cells were investigated using various different metallic powders (Fig.1). It was found that tough Ti, Zr, Sn, Nb, and Ta appear to have no effect, but Al and V ions exhibit cytotoxicity at high concentrations. A newly developed Ti-15%Zr-4%Nb-4%Ta-0.2%Pd alloy was found to have improved corrosion resistance in physiological saline solution. By adding 0.2%O and 0.05%N and applying heat treatment, the ultimate tensile strength was improved to 1OOOMPa, the total elongation improved to more than 10%, and the fatigue strength was found to be 95OMPa after 108 cycles. Cell growth ratios were found to be almost normal up to 105 cycles, but a sharp decrease was observed when V ions were released into Eagle's MEM solution.18,26,27,28,29) Work has also been done on the transport properties of biomembranes, and the structures of films of polymers such as polyvinyl alcohol gel, and the interactions between the film and transporting material in a hydrophobic environment have been investigated.
Fig.1 Relative cell growth ratio for various metallic concentration in the medium.
Artificial heart development
A centrifugal blood pump incorporating a permanent magnet and ceramic mono-pivot bearing is under development for application as an implantable artificial heart. Satisfactory pump performance was obtained from a recently developed model (Fig.2) with an impeller 50 mm in diameter and a drive unit 8 mm thick. By improving the impeller geometry, the required pressure (lOO mmHg) and flow rate (5L/min) were obtained at reasonable speed (1,900 rpm) and total efficiency (13%). The secondary and boundary layer flows - which are important in thrombus formation and haemolysis are currently under investigation using flow visualisation techniques with a high speed video camera and laser light sheet.20,21,22,28) Haemolysis tests using animal blood and equivalent slurries showed that mechanical cell damage was at a similar level to that found in commercial centrifugal blood pumps.17,19)
Fig.2 A newly developed momonopivot magnetic suspension blood pump for an implantable artificial heart.
Optical tomography
Optical tomographic imaging using near infrared light has potential as a non-invasive measurement technique for determining the oxygenation state of living tissue. Unfortunately, light is strongly scattered by tissue and an understanding of photon migration in living organisms is necessary. Computer codes have been developed to simulate photon migration, and a new algorithm based on inversion techniques has been devised for optical tomography. Solid phantoms simulating the human head have been designed and fabricated using an optical rapid prototyping technique. These will be used to validate the photon migration model and the new algorithm. 16,24,30)
Fig.3 Optical human head phantom (white matter of a brain taken from MRI head image) for validation of photon migration model and new algorithm.
Fig.4 Metabolic Measurements by MRI(a) with Microdialysis(b)
Novel MRI/S techniques
Magnetic Resonance Imaging and Spectroscopy (MRI/S) techniques can be used to measure the concentration of nuclei such as hydrogen and phosphoric acid in biological tissue, and give images of their concentration distribution in two- or three-dimensions. We have developed several novel MRI/S techniques including: Fast three-dimensional T2 weighted imaging with high S/N ratio, and two-dimensional perfusion imaging with chemical selection. These techniques are useful as diagnostic techniques in medicine and biology.
Computer aided surgery
Computer Aided Surgery (CAS) uses techniques from both clinical medicine and engineering, for example, mechatronics, optics, and information technology. Demand for intra-operative simulation, registration, and navigation is driving the development of techniques for handling soft organs such as: non-rigid registration, interventional imaging, and surgical robots. This work requires mechanical models of the soft organs such as the brain and the liver. We have proposed new equations for modelling the properties of brain tissue which use a single-phase non-linear visco-elastic model derived from in-vitro examination25). The model has been validated by comparison with in-vivo indentation tests on pig brain tissue.
The combination of interventional MRI and surgical robots is a promising but challenging project. We are developing MRI-compatible machines for biomechanical studies, and one of these, a MRI-compatible surgical manipulator which uses no ferromagnetic materials, is shown in the Fig.5 below.
Fig.5 MR compatible stress/extension machine, which can locate inside the imaging region. List of Publications(1998) Bioengineering
16) Y. Tanikawa, D. Imai, H. Maki, S. Takahashi and Y. Yamada, Fabrication of dynamic optical head phantoms from an MRI head model, SPIE Proc. 3194(Jan. 1998), pp.512-521
17) T. Yamane, M. Nishida, T. Orita, T. Kijima and J. Maekawa, Improvements in the design of the Monopivot Magnetic-Suspension Blood Pump, Heart Replacement-Artif. Heart 6 (Jan.1998), pp.401-405
18) Y. Okazaki, S. Rao, T. Tateishi and Y. Ito, Cytocompatibility of various metal and development of new titanium alloys for medical implants, Mater. Sci. and Eng. A A243 (Feb.1998), pp.250-256
19) T. Yamane, A new technology trend of artificial organs Now and Future, JITA 13-43 (Apr.1998), pp.2-4
20) T. Yamane, B. Asztalos, M. Nishida, T. Masuzawa, K. Takiura, Y. Taenaka, Y. Konishi and Y. Miyazoe, Flow visualization as a complimentary tool to hemolysis testing in the development of centrifugal blood pumps, Artif. Organs 22-5 (May 1998), pp.375-380
21) Y. Miyazoe, T. Sawairi, K. Ito, Y. Konishi, T. Yamane, M. Nishida, T. Masuzawa and K. Takiura and Y. Taenaka, Computational Fluid Dynamic Analyses to Establish Design Process of Centrifugal Blood Pumps, Artif. Organs 22-5(May 1998), pp.381-385
22) M. Nishida, T. Yamane and B. Asztalos, Washout hole flow measurement for the development of a centrifugal blood pump, Artif. Organs 22-5 (May 1998), pp.386-392
23) K. Takiura, S. Endo, Y. Wakisaka, E. Tatsumi, Y. Taenaka, H. Takano, T. Yamane, M. Nishida, B. Asztalos and Y. Konishi, Y. Miyazoe and K. Ito, Development of Design Methods of a Centrifugal Blood Pump with In Vitro Tests, Flow Visualization, and Computational fluid Dynamics: Results in Hemolysis Tests, Artif. Organs 22-5 (May 1998), pp.393-398
24) M. R. Jones and Y. Yamada, Determination of the Asymmetry Parameter and Scattering Coefficient of Turbid Media from Spatially Resolved Reflectance Measurements, Opt. Rev. 5-2 (May 1998), pp.72-76
25) K. Miller and K. Chinzei, Simple Validation of Biomechanical Models of Brain Tissue, J. Biomechanics 31-Suppl. 1(Jul. 1998), pp.104-
26) Y. Okazaki, S. Rao, Y. Ito and T. Tateishi, Corrosion resistance, mechanical properties, corrosion fatigue strength and cytocompatibility of new Ti alloys without Al and V, Biomaterials 19 (Aug.1998), pp.1197-1215
27) Y. Okazaki, S. Rao, S. Asao, T. Tateishi, S. Katsuda and Y. Furuki, Effects of Ti,Al and V Concentrations on Cell Viability, Mater. Trans., JIM 39-10 (Oct.1998), pp.1053-1062
28) Y. Okazaki, S. Katsuda, Y. Furuki and T. Tateishi, Effects of Aluminium Oxide Film on Fibroblast L929 and V79 Cell Viabilities, Mater. Trans., JIM 39-10 (Oct. 1998), pp.1063-1069
29) Y. Okazaki, S. Rao, 5. Asao and T. Tateishi, Effects of Metallic Concentrations Other Than Ti, Al and V on Cell Viability, Mater. Trans., JIM 39-10 (Oct.1998), pp.1070-1079
30) S. Takahashi and Y. Yamada, Simulation of 3D light propagation in a layered head model including a clear CSF layer OSA TOPS, Adv. In Opt. Imaging and Photon, Migration 21(Nov.1998), pp.2-6
Information and Systems Science
Any enquiries regarding this project should be directed to e-mail: butsuri0@mel.go.jp
Topics in optical engineering
Research has been done on the optical radiation pressure exerted on metallic particles towards developing optical tweezers. It was found that attractive forces may be produced because of inter-action between the incident light and electrons on the metal surface. In another project, lens aberrations of up to 50 wavelengths have been measured to an accuracy of 1/70th of a wavelength using a Ronchi test with a phase-shifted sinusoidal grating. Techniques for measuring large deformations and large amplitude vibrations using holographic interferometry are also under development.63) Other investigations include: Control of the statistical properties of light,35) electro-holography using liquid crystal devices, and testing techniques for large surfaces using shearing interferometry.
Fig.1 Microscopic images of trapped gold particles.
(a)aggregated and (b)circularly arranged particles.
Stratospheric unmanned lighter-than-air platform
Stratospheric lighter-than-air (LTA) vehicles (eg. the airship) have potential as observation and communications relay platforms. It has been proposed that these vehicles fly at altitudes of 20km or so, where winds are relatively weak, powered by solar energy or surface-to-air wireless power transmission techniques using microwaves or laser radiation. Preliminary experiments have been made off-shore of the city of Hitachi, towards developing launch and recovery techniques and shuttle flight control technologies.49) The vehicle encounters severe conditions before reaching final working altitude. For example, it must pass through the jet stream where wind speeds can be greater than lOO m/s, and at an altitude of 17 km the atmospheric temperature can be less than -80℃. The situation is compounded by the fact that powered flight to gain or lose height rapidly at low altitudes is not possible because of the large thruster system required to cope with the higher air density low in the atmosphere. The photo shows the launch scene for a high-speed climb experiment with a stream-line shaped 25m balloon.
Fig.2 Launch of high-speed climbing balloon
Constraint-based preliminary design support system
Engineering design is defined as the process of generating all necessary information to produce a final physical product which satisfies given requirements. By regarding the requirements as constraints, the engineering design problem can be formulated as a problem in satisfying a set of constraints.64) We have developed a preliminary design support system based on this concept, consisting of the following subsystems: (1) A product manager which holds the conceptual structure of the product to help the designer explore a generated design solution, (2) A design constraint manager which shows the process by which a design plan expressed as a set of constraints evolves from an abstract idea to a concrete plan, (3) A design constraint interface which is used to define and modify the constraints of each design plan, and (4) An algebraic constraint so1ver52,53) which evaluates the algebraic constraints.
Intelligent Transport Systems
MEL has a long history of research on Intelligent Transport Systems (ITS) and Advanced Vehicle Control and Safety Systems (AVCS S). This has included work on automated driving systems, measurement and analysis of automobile traffic flow and investigations into human factors influencing driving phenomena.43,58,59) A vision based automated vehicle is the current main research theme in this area. This vehicle uses the coefficients of a cubic curve, fitted to the required future path of the vehicle as detected by a CCD camera, to provide steering control. The lateral control algorithm has also been applied to detection of lane departure, where comparison of the control signals from a human driver and an automatic vision-based steering system provide an indication that the vehicle has left (or is about to leave) the current lane. The lane departure algorithm has been shown to be feasible by experiments with a vision-based vehicle on a test track.44,60) Figure 4 shows the vision-based vehicle used in the experiments.
Fig.3 Constraint-Based Preliminary Design Support System
Fig.4 The vision-based vehicle: it is also equipped with laser radar and DGPS.
Adaptive space-time finite element methods
It is well known that the skew-symmetric term in the weak form of the advection-diffusion equations sometimes causes numerical instability in finite element solutions. Stabilised finite element methods and space-time schemes are usually used to reduce the instability within a reasonable mesh. Mesh adaptation is another way to reduce the discritization error, and this has been the subject of research in our group over the past several years. By coupling adaptive mesh control in space with both the GLS (Galerkin/Least Squares) stabilisation scheme and the space-time formula in finite element analysis, we have been able to obtain acceptable results in two-dimensional unsteady advection diffusion equations within reasonable computation time.34) We are in the process of extending these methods to the Navier-Stokes equations.
Fig.5 （１）Rotating cone problem in advection-diffusion equations
Fig.5 （２）Elevation of φ after one rotation (w/h-adap. +direct projection) List of Publications(1998) Information and Systems Science
31) J. Rasanen, K. E. Peiponen, K. M. Abedin, K. Tenjimbayashi, T. Eiju and K. Matsuda, Integrated scatter plate and projection lens for scatter plate interferometer, Rev. of Scientific Instruments 69-4 (Jan.1998), pp.1587-1590
32) K. M. Abedin, J. Rasanen, M. Kawazoe, K. Tenjimbayashi, T. Eiju, K. Matsuda and K. E. Peiponen, Experimental verification of computer simulation of the scatter plate interferometer, Optik 108-1(Jan. 1998), pp.27-31
33) T. Nakada and Y. Morikawa, Optical Actuator (Attuatori Ottici), Oleodinamica Pneumatica Lubrificazione (in Italian) 39-3 (Mar.1998), pp.226-232
34) A. Tezuka, Adaptive Space-Time GLS FEM for 2D Advection-Diffusion Problem, Proc. of Fourth Japan-US Symp. on Finite Element Methods in Large - Scale, Computational Fluid Dynamics (Apr.1998), pp.115-118
35) T. Shirai, E. Wolf, H. Chen and W. Wang, Coherence Filters and Their Uses II: One-dimensional Realizations, J. Mod. Opt. 45-4 (Apr.1998), pp. 799-8]6
36) K. Hibino, B. F. Oreb, D. I. Farrant and K. G. Larkin, Reply to Comment : Phase-shifting algorithms for nonlinear and spatially nonuniform phase shifts, J. Opt. Soc. of America A 15-5 (May 1998), pp.1234-1235
37) K. M. Abedin, M. Kawazoc, K. Tenjimbayashi, T. Eiju and K. Matsuda, Electronic speckle pattern interferometry using compressed images from a digital still camera, Opt. Eng. 37-5 (May 1998), pp.1599-1601
38) N. Ichikawa, M. Misawa, S. Kano, N. Aya, H. Iwamoto and Y. Enomoto, Numerical Analysis of Transient Heat Transfer and Temperature Response in a Metal during a Laser Irradiation, Proc. of ICALEO 97 83-1 (May 1998), pp.216-225
39) M. Misawa, N. Ichikawa, M. Akai, K. Hon, K. Tamura and K. Matsui, Development of fast X-ray CT system for transient two-phase flow measurement, Proc. 6th Int. Conf on Nuclear Eng, San Diego, USA CD-ROM-6383 (May 1998), pp.1-18
40) S. Murata, H. Kurokawa, E. Yoshida, K. Tomita and S. Kokaji, A 3-D Self-Reconfigurable Structure, Proc. IEEE Int. Conf. on Robotics and Automation (May 1998), pp.432-439
41) E. Yoshida, T. Arai and J. Ota, Local Communication of Multiple Mobile Robots: Design of Group Behavior for Efficient Communication, Adv. Robotics 11-8 (May 1998), pp.759-779
42) E. Yoshida, S. Murata, K. Tomita, H. Kurokawa and S. Kokaji, Experiment of Self - repairing Modular Machine Distributed Autonomous Robotic Systems 3, T. Lueth, R. Dillmann, P. Dario, H. Worn, editors, Springer (May 1998), pp.119-128
43) T. Sakaguchi, A. Uno and S. Tsugawa, An Algorithm for Merging Control of Vehicles on Highways, 1998 JSAE Spring Convention Proc. 984 (May1998), pp.85-88
44) S. Kato, K. Tomita and S. Tsugawa, Appilcation. of a Vision-Based Lateral Control Algorithm to Lane Departure Detection, JSAE Spring Convention Proc. 984-9831568 (May 1998), pp.77-80
45) A. J. van der Linden, M. Misawa, M. Akai, H. Monji and K. Matsui, Fast X-ray CT measurement of cell and shroud taylor bubbles in rod bundles, Proc. 1st European-Japanese two-phase flow groip meeting, Portoroz, Slovenia (Jun.1998), pp.1-9
46) N. Ichikawa, M. Misawa, M. L. Ford, T. Tada and M. Kawaji, Dynamic Behavior of Gas-Liquid Interface in Capillary Flow under Reduced-Gravity Conditions, Proc. 3rd Int. Conf on Multiphase Flow CD-ROM-430(Jun. 1998), pp.1-8
47) A. Kanyasaki, M. Kawaji, M. Misawa and N. Ichikawa, Bubble detachment and motion in a flowing liquid, Proc. 3rd Int. Conf on Multiphase Flow, Lyon,France CD-ROM-609(Jun.1998), pp.1-7
48) M. Misawa and N. Ichikawa, PIV measurement and analysis of flow patterns around moving bubbles in vertical channels, Proc. 3rd Int. Conf on Multiphase Flow, Lyon,Frnnce CD-ROM-291(Jun.1998), pp.1-8
49) M. Onda, High altitude powered balloon for strato-spheric shuttling test, Proc. Int. Airship Conv. and Exhibition, Bedford, UK (Jun.1998), pp.117-126
50) K. Hibino and M. Yamauchi, Phase determination algorithms compensating for spatially nonuniform phase modulation in phase shifting interferometry, SPIE Proc. 1998 Int. Symp. on Opt. Sic., Eng. and Instrumentation 3478 (Jul. 1998), pp.110-120
51) E. Yoshida, M. Yamamoto, T. Arai and J. Ota, Local Communicaton of Multiple Mobile Robots:Design of Optimal Communication Area for Cooperative Task, J. Robotic Systems 15-7(Jul. 1998), pp.407-419
52) H. Sawada, The Algebraic Under Constraint Solver as a Design Tool, Proc. 1998 IMACS Conf. on Appl. of Computer Algebra http:// math.unm.deu/A CA/1998/sessions/industr/sawada/index.html (Aug.1998).
53) H. Sawada and X.T. Yan, Qualitative Reasoning at the Early Design Stage, Proc. the 13th Biennial European Conf on Artif. Intellignece, Workshop WS: Model based systems and qualitative reasoning (Aug.1998), pp. 7-11
54) K. Hibino, Suppression of Spatial Nonuniformity and Nonlinearity in Phase Modulation in Phase Shifting Interferometry, Proc. SPIE 3573 (Sep.1998), pp.482-485
55) A. Suzuki and M. Kuroda, A Chaotic Oscillator using a Shape Memory Alloy Actuator, Int. Symp. on Nonlinear Theory and its Appl.s (NOLTA'98) NOLTA98-2 (Sep.1998), pp.607-610
56) T. Ohashi, S. Imamura, T. Shimizu and M. Motomura, Computer Aided Process Planning for Axis-symmetric Cold Forging Products by Feature Elimination, Proc. 14th Int. Conf. on CAPE (Sep.1998), pp.313-318
57) H. Masaki and S. Imamura, CAD based Multi Agent Machine Assembly/Disassembly Planning, 11th Int. Conf. on Appl. of Prolog (Sep.1998), pp.130-135
58) S. Tsugawa, M. Yanagiya and K. Tomita, Optimal Design of Vision System for Lateral Control of Autonomous Vehicle, Proc. 4th Int. Symp. on Adv. Vehicle Control 1998 (Sep.1998), pp.369-374
59) S. Tsugawa, H. Mon and S. Kato, A Lateral Control Algorithm for Vision-Based Vehicles with a Moving Target in the Field of View, Proc. IEEE Intelligent Vehicles Symp. '98 (Oct.1998), pp.41-45
60) S. Kato, K. Tomita and S. Tsugawa, Lane Departure Detection with an Onboard Vision System, Proc. IEEE Intelligent Vehicles Symp. '98 (Oct.1998), pp.74-79
61) S. Kobayashi, K. Shimazaki, A. Fujitani, A. Okuno and S. Tsugawa, Evaluation of Lane Marking Detection with Machine Vision under Poor Visibility, Proc. 5th ITS World Cong. (Oct.1998), CD-ROM
62) E. Yoshida, S. Murata, H. Kurokawa, K. Tomita and S. Kokaji, A Distributed Reconfiguration Method for 3-D Homogeneous Structure, Proc. Int. Conf. on Intelligent Robots and Systems (IROS98) (Oct.1998), pp.852-859
63) K. Tenjimbayashi, Vibration mode analysis by two stroboscopic holographic interferograms, Proc. SPIE 3550 (Oct.1998), pp.399-408
64) H. Sawada, Constraint-Based Design, Tech. Report, CAD Centre, University of Strathclyde CADC/98 -11/R/04 (Nov.1998)
65) Y. Morikawa and T. Nakada, Bimorph-Type Optical Actuator Using PLZT Elements (Position Control of Optical Actuator by On-Off Control), JSME Int. J. Series C 41-4 (Dec.1998), pp.860-866
66) S. Imamura, Machine Assembly/Disassmbiy Planning Cooperatire Agents, JSME Int. J.41-4 (Dec. 1998), pp.947-952
Advanced Machine Technology
Any enquiries regarding this project should be directed to e-mail: kyoku0@mel.go.jp
Conductive cantilever fabrication using focused ion beam technology
Conductive cantilevers are required in atomic force microscopy in order to obtain both electronic and topographical information. Unfortunately, the performance of commercial conductive cantilevers is not yet good enough for this application as the metal coatings on the tip are easily eroded. Doped silicon cantilevers are not suitable for measuring the electronic properties of the surface as the measured current is strongly affected by the properties of the cantilever itself - for example Shottky junctions may be inadvertently formed in the system. We have therefore proposed a new cantilever fabrication method which uses a focused ion beam, and has the advantage of allowing considerably more flexibility in the tip design. The figure shows a cantilever made using this method. The cantilever has a tall conductive tip which has both metallic conductivity and high sensitivity for detection of lateral force.
Fig.1 Conductive cantilever fabricated by FIB(Focused Ion Beam)
Microscale friction control using applied electric potential
A microfriction tester has been used to investigate the effect of an applied electric potential on the microscale friction between dielectric materials such as mica, SiC, and Si3N4. When DC or AC potential were applied to the friction surfaces, an appreciable change in microfriction occurred, depending on the applied voltage and frequency. The microfriction was found to become nearly zero (to within the measurement capability of the microfriction tester) when a voltage of １３０Vpp was applied at frequency of 19kHz. These experiments suggest that control of microfriction by applying electrical potential is possible.82)
Fig.2 Frictional force as a function of AC voltage at 100 kHz.
Wing characteristics at low Reynolds numbers (10-2 < Re < 104)
The hydrodynamic characteristics of both membrane and bristled wings at low Reynolds numbers have been investigated. It was found that the characteristics of membrane wings depend strongly on the airfoil cross-sectional shape - for example, wings with a thin airfoil and corrugation or a sharp leading edge tend to have good hydrodynamic characteristics (a high lift/drag ratio). These characteristics can be observed in insect or model aircraft wings. By contrast, a bristled wing has a higher wing loading (higher hydrodynamic force per unit area, and higher lift and drag coefficients) than a membrane wing. In order to generate the same hydrodynamic force the wing area or mass of a bristled wing can be smaller than that of a membrane wing. These results are useful in the design of small-scale fluid handling machinery.
Fig.3 Airfoil shapes having maximum lift-drag ratio at Re≒1O3. Maximum lift-drag ratios of Airfoil (b) and (d) are larger than those of Airfoil (a) and (c), respectively.
Elastohydrodynamic lubrication characteristics of electrorheological fluids
Electrorheological fluids (ER fluids) are new materials which undergo fast reversible changes in viscosity on application of an external electric field (electro-rheology). They have potential application in industrial tribology problems - particularly those where control of tribological characteristics is desirable.
A ball-on-disk tribo-testing machine was made to observe the thickness and shape of an ElastoHydrodynamic Lubrication (EHL) film, and to investigate the possibility of control of triboelement performance using ER fluids. A liquid crystal was used as the lubricant and the Figure shows results obtained during the experiment which confirm that an applied electric field causes changes in the tribological conditions. These results indicate that there is potential for control of triboperformance using ER fluids.
Fig.4 Interference Fringe of EHL Film.
Smart structures for active noise control
Work is in progress to develop novel active noise control systems for sound fields carried by three-dimensional structures. This project began with the introduction of a new parameter: the acoustic power mode , initially intended for application to flat planar strctures, and obtained by grouping structural vibration modes in order of acoustic radiation efficiency. The parameter allows the noisiest modes to be targeted for suppression, and will theoretically make it possible to guarantee that overall suppression in the spectrum of interest will be optimum. A new type of distributed parameter sensor using a PVDF film with an optimised shape has been developed, which gives an output voltage proportional to the acoustic power mode amplitude, together with a compact actuator incorporating PZT ceramic stacks and steel columns which is capable of applying bending moments. Because the structure condition may change with time, an adaptive controller which minimises sensor output using DSP techniques with a filtered-x LMS algorithm has also been devised.
This project is one stage in the development of smart structures incorporating distributed parameter sensors, bending moment actuators, and adaptive control algorithms. Although the development of smart structures initially began with work on large space structures, we anticipate these ideas will find new application in achieving a quiet every day environments.
Fig.5 Smart sensors and bending moment-type actuators for active noise control. List of Publications(1998) Advanced Machine Technology
67) H. Tsushiro, A. Yabe, Y. Yoshizawa, A. Sasamoto, B. Burtsitsig and K. Kieda, Mechanism of Cut and Connection Phenomenon of Two Vortex Rings, Nagare 17 (J. Japan Socity of Fruid Mechanics)(1998)(Apr.1998), pp.279-287
68) D. Nelias and T. Yoshioka, Location of an acoustic emission source in a radially loaded deep groove ball-bearing, Proc. the Institution of Mech. Eng. Part J : J. Eng. Tribology, London 212(Apr.1998), pp.33-45
69) Y. Enomoto and T. Yamamoto, New materials in automotive tribology, Tribology Letters 5 (May 1998), pp.13-24
70) H. Sato, H. Nishino, H. Choh, H. Ogiso and K. Yamanaka, Estimation of Elastic Constants from Surface Acoustic Wave Velocity by Inverse Analysis using the Downhill Simplex Method, Jpn. J. Appl. Phys. -37(May 1998), pp.3116-3119
71) N. Tanaka and Y. Kikushima, One-dimensional distributed modal sansors and the active modal control for planar structures, The J. the Acoustical Soc. of America 104-1(Jun. 1998), pp.217-225
72) M. Kuroda and M. Nakai, Chaos and its control in an asymmetrical piec-ewise-linear mechanical vibratory system, Proc. (CD-ROM) 4th World Cong. on Computational Mech. Pt. Il-Sec. 5, No.8 (Jun.1998), pp.1-18
73) Y. Enomoto and Z. Zheng, Possible Evidences of Earthquake Lightning Accompanying the 1995 Kobe Earthquake Inferred from the Nojima Fault Gouge, Geophysical Research Letters, 25 - 14 (Jul.1998), pp.2721-2724
74) S. Fujisawa K. Yokoyama, Y. Sugawara and S. Morita, Analysis of Experimental Load Dependence of Two-dimensional Atomic-scale Friction, Phys. Rev. B 58-8(Aug. 1998), pp.4909-4916
75) T. Yoshioka and H. Mano, Relationship between Acoustic Emission Source Position and Spalling Position in Radial Rolling Bearings, Tribology for Energy Conservation -- Proc. of 24th Leeds-Lyon Symp. on Tribology (Aug.1998), pp.413-422
76) S. Sivrioglu and K. Nonami, An experimental evaluation of robust gain scheduled controllers for AMB system with gyroscopic rotor, Proc. the 6th Int. Symp. on Magnetic Bearings (Aug.1998), pp.352-361
77) T. Yajima, A. Yabe, K. Takahashi and H. Maki, Time Variation of the Thin Liquid Film Thickness Under the Boiling Bubbles in Saturated Pool Boiling Heat Transfer, Heat Transfer 1998, 2(Sep. 1998), Taylor & Francis, pp.425-430
78) H. Kurokawa, S. Murata, E. Yoshida, K. Tomita and S. Kokaji, A 3-D Self-Reconfigurable Structure and Experiments, Proc. Int. Conf on Intelligent Robots and Systems (1R0598) 2(Oct. 1998), pp.860-865
79) Y. Enomoto and H. Ohuchi, Electron emission and electrification of ceramics during sliding, Proc. the First Asia Int. Conf. on Tribology 2 (Oct.1998), pp.669-672
80) L. Scudiero, J.T. Dickinson and Y. Enomoto, The electrification of flowing gases by mechanical abrasion of mineral surfaces, Phys. and Chem. of Minerals 25 (Dec.1998), pp.566-573
81) S. Sunada, L. Zeng and K. Kawachi, The relationship between dragonfly wing structure and torsional deformation, J. Theoretical Biology 193 (Aug.1998), pp.39-45
82) S. Fujisawa and Y. Enomoto, Effect of Electric Potential to Micro-Scale Friction between Muscovite Mica and Silicon Nitride, Proc. 5th Int. Tribology Conf. in Australia 1-1(Dec.1998), pp.497-499
Energy and Environmental Technology
Any enquiries regarding this project should be directed to e-mail: energy0@mel.go.jp
The Energy Engineering Department works on technologies related to new energy sources, energy conservation, and environmental protection. Some of the latest research topics are described below.
Development of a high efficiency liquid phase reactor (Eco Energy City Project)
We are developing a high efficiency liquid phase reactor as part of the Broad Area Energy Utilisation System Project (Eco Energy City Project) promoted by AIST, MITI. In this reactor, micro bubbles with diameter smaller than 1 mm are used to improve the dissolution rate of the reactive gases, because of their large surface area. We have investigated the gas dissolution processes in a spherical gas bubble rising through liquid both experimentally and using numerical simulations. In our apparatus, a microscope equipped with a CCD camera follows the rising bubble, and precisely measures changes in the bubble size and rate of ascent. We have done this experiment with both Oxygen bubbles in Silicone oil, and Carbon Dioxide bubbles in water. We estimate the Sherwood number as a function of the Schmidt number and the Reynolds number from the changes in the bubble size and ascent rate. We also numerically estimate the Sherwood number for the dissolution of a spherical bubble in an infinite liquid by directly solving the Navier Stokes and diffusion equations. Comparison of the experimental and numerical results shows that the drag coefficient and Sherwood number for an Oxygen bubble in Silicone oil agrees well with those expected for a fluid sphere, while the same parameters for a Carbon Dioxide bubble in water agree with those expected for a solid particle. By correlating the experimental and numerical results we have also been able to find an equation for estimating the Sherwood number of a fluid sphere for Reynolds numbers less than 100 and Peclet numbers greater than 1.107)
Fig.1 Dissolution of a rising 02 bubble in Silicone oil.
Low Reynolds number flows in ceramic gas turbines
The Agency of Industrial Science and Technology is involved in a project to develop 300kW ceramic gas turbines with target thermal efficiencies of up to 42% and turbine inlet temperatures of 1350 ℃. However, the high inlet temperature causes low Reynolds number flows. The fundamental aerodynamic characteristics of annular turbine cascades at low Re have been investigated towards improving turbine performance. Hot wire and five-hole pressure probes were used to measure wakes from the cascade for Re in the range 2x104 to 12x104 and inlet turbulence intensity (Tu) in the range 0.4% to 8.7%. Figure 2 shows the distribution of total pressure loss at the stator exit. The total pressure loss increases dramatically as Re falls, while the effect of variations in Tu is relatively insignificant. These results highlight the importance of correct design analysis for turbine blades operating at low Re.98)
Fig.2 Total pressure loss at turbine stator exit (Re=2x104, Tu=O.4%)
Laser guided discharge in a vacuum
A new method of guiding low pressure discharge using a laser beam has been developed. The discharge path is guided by the flight path of thermoelectrons and so the discharge can be made to follow both straight and curved paths. The incident laser beam generates a metal plasma which emits the thermoelectrons. Using this technique it is possible to guide a discharge from the anode, through a hole in the cathode, to the back surface of the cathode as shown in the figure 3. 84)
Fig.3 Example of guided discharge through a electrode hole.
Observation of flame propagation in a lean burn LPG SI engine
An extended bottom view piston equipped with a quartz window has been used in a heavy duty lean burn LPG engine to observe flame propagation and flame contours. The swirl ratio and piston cavity configuration were varied to determine their effect on combustion and engine performance. It was found that NOx decreased gradually but hydrocarbon emissions increased as the mixture was made leaner than stoichiometric. High swirl appeared to accelerate development of the initial flame kernel, as evidenced by a shorter crank interval between the spark and maximum cylinder pressure. A 'D' type cavity, with an increased squish area below the intake valve, was shown to have the shortest burn duration among the piston cavities tested. The flame propagation observation technique used in these experiments was shown to be useful for the study of combustion processes in engines.
Ignition control of rapidly compressed H2-02-Ar mixtures using a UV laser (WE-NET Research)
Fundamental technologies for clean and efficient power generation systems are under development at MEL as part of WE-NET, which is a large scale project that it is hoped will provide simultaneous solution of global energy and environmental problems. As part of this work, new technologies using photochemical reactions for combustion initiation are under development. It was found that the minimum incident UV laser energy required to ignite a rapidly compressed H2-02-Ar mixture is much less than that required at atmospheric conditions. These results show that this method will a realize non-intrusive ignition inside the combustion chamber of an engine easily.
Fig.4 Ignition process of rapidly compressed H2-02-Ar mixture by UV laser H2:16%, O2:16%, Ar:68%, Frame speed l0,OOOf/s, Incident laser energy 4.0 mJ, Temperature and pressure of rapidly compressed mixture: 568K, 0.31MPa
Thermally regenerative fuel cell
A thermally regenerative fuel cell (TRFC) is a fuel cell which uses Hydrogen and Lithium and is equipped with a thermal regenerator that decomposes the reaction products as shown in the figure. TRFC has potential for direct conversion of thermal energy into electricity and is expected to achieve higher efficiency when combined with gas turbine system. The rate-determining process in this system is Hydrogen reduction in molten alkali halide. This process involves many different sub-processes including the penetration of Hydrogen through the cathode, decomposition of Hydrogen molecules, the reaction of Hydrogen atoms with electrons, and diffusion processes of Hydride ions. It is important to understand the reaction process as part of developing TRFC systems. In our research, a LiCl-KCl eutectic melt was chosen as the molten electrolyte and we examined hydrogen reduction in the melt using the single scan potential sweep method. Analysis of the voltammograms showed that: (1) The electrode reaction is a single electron reversible reaction, (2) The reaction goes to 0.5 order of the gas pressures, and (3) The hydrogen reduction process is a two-step process: 1/2 H2 → H, H + e - → H - . It was also found that the voltammogram varies in shape depending on the electrode material. A new reaction model was proposed which takes into account the effect of hydrogen absorbed into the electrode, and the differences in peak current and potential between different electrode materials were successfully explained from the differences in solubility and diffusivity of hydrogen in each metal. The Henry and diffusion constants of hydrogen in the LiCl-KCl melt were also determined.
Fig.5 Principle of TRFC operation
Battery monitoring system for electric vehicles
The capacity and service life of electric vehicle battery packs is limited by the non-uniformity of cells in the pack. If the cells are not identical, conventional series charge/discharge methods exacerbate the non-uniformities with consequent detrimental effects on lifetime and capacity. It is essential that the battery controller operates so that non-uniformities are prevented.
In order to better understand the parameters limiting the performance of conventional EV battery packs in service, the effective capacities of individual cells in representative packs were measured. It was found that each pack usually contains one or two cells with significantly reduced capacity, highlighting the importance of preventing non-uniformities. The effects of cell-based management systems have been investigated by charge/discharge tests performed on 6-cell test battery packs in which the effective capacity variation in each cell was measured.
Following on from this work, we proposed a cell based monitoring system for EV battery packs which is effective during both driving and charging. Prototype cell monitoring devices were made and tested as part of development of the cell-based battery management system. As shown in the schematic diagram of the system, each cell is equipped with a monitoring device which simultaneously measures cell voltage and temperature on command from the controller. The controller can then estimate the state of charge of each cell using simultaneous measurements of the current and the cell terminal voltage obtained under dynamic operating conditions. This work was supported by the Original Industrial Technology R&D Program of NEDO, Japan.117)
Fig.6 Schematic diagram of the cell based monitoring system for EVs
DeNOx catalysts for diesel engines
Studies of selective deoxidisation catalysts (DeNOx catalysts) are in progress towards development of techniques to control Nitrogen oxides in diesel exhaust emissions. Ag/Alumina catalytic converters with trap oxidisers have been tested in an attempt to simultaneously reduce NOx and particulate emissions. Figure 7 shows the surface profile of an Ag/Alumina catalytic converter obtained with a STM. The performance of selective catalysts was examined by experimentally analysing the catalyst characteristics under actual exhaust conditions. With Ethyl Alcohol as a reducing agent, it was found that the conversion rate was better than 20% at a space velocity of 24,500h -1 and reaction temperature greater than 300 ℃. These conditions are typical of those found in actual vehicles.
Fig.7 STM surface profile of Ag/Alumina catalytic converter List of Publications(1998) Energy and Environmental Technology
83) T. Segawa, A. Naert and M. Sano, Boundary layers of Turbulent Rayleigh -Benard convection in mercury, Phys. Rev. E 57(Jan.1998), pp.557-560
84) Y. Hoshi and H. Yoshida, Non-straight Discharge Path Guided by a Laser Beam, J. Vac. Sci. Tech. B 16-1(Jan.1998), pp.247-249
85) Y. Okuno, T. Okamura, K. Yosikawa, S. Kabashima, H. Yamasaki, S. Shiota and Y. Hasegawa, Recent Power Generation Experiment with Fuji-1 CCMHD Blow-Down Facility, Proc. 1998 Int. Symp. on Adv. Energy. Tech. 1(Feb.1998), pp.277-284
86) T. Murakami, Y. Okuno, H. Yamasaki, S. Kabashima and Y. Hasegawa, Optical Measurements of MHD Power generation Plasma in Fuji-1 Disk Generator, Proc. 1998 Int. Symp. on Adv. Energy. Tech. 1(Feb.1998), pp.301-308
87) T. M. Marinchenko, V. M. Zubtsov, Y. Hasegawa, K. Tsuji, K. Yoshikawa, H. Yamasaki and S. Shiota, Seed Fraction Measurement in Closed Cycle MHD Power Conversion, Proc.1998 Int. Symp. on Adv. Energy. Tech. 1 (Feb.1998), pp.581-588
88) 0. Kurata, S. Takahashi and Y. Uchiyama, Calculation of Methane-Air Burning Velocity at High Temperatures, Bulletin of GISJ 1998 (Mar.1998), pp.29-29
89) N. Iki, H. Furutani, J. Hama, H. Ryu, S. Takahashi and 0. Kurata, Burning Velocity of Stoichiometric Hydrogen-Oxygen-Steam Mixture, Bullentin of GTSJ 1998 (Mar.1998), pp.32-32
90) T. Seto, K. Okuyama and K. Takeuchi, Differential mobility analyzer (DMA) for the measurement and sizing of nano-particles, clusters and ions, Riken rev. 17-4 (Apr.1998), pp.5-6
91) H. Iwamoto, N. Aya, S. Kano, H. Shimura, N. Ichikawa and Y. Enomoto, Temperature Measurements of a Laser Induced Plume by Emission Spectroscopy, Proc. ICALEO 97 83-1 (May 1998), pp.103-111
92) S. Takahashi, J. Hama, H. Furutani, N. Iki and I. Yamashita, Hydrogen Internal Combustion Stirling Engine, 12th Hydrogen Energy Conf. (Jun. 1998), pp.1473-1445
93) A. Nakano, M. Shiraishi, M. Nishio, F. Takemura and M. Murakami, Numerical analysis of heat transport mechanism in nitrogen near the critical point, Adv. in Cryogenic Eng., Plenum Publishing Corporation 43-B (Jun.1998), pp.1297-1304
94) T. Munakata and I. Tanasawa, A Study of Surface Tension Effect on Double-Diffusive Rollover, Proc. 7th AIAA/ASME Joint Thermophysics and Heat Transfer Conf. 2(Jun.1998), pp.39-46
95) F. Takemura and A. Yabe, Gas Dissolution Process of Shpherical Rising Gas Bubbles in Liquid, Proc. ASME Fluids Eng. Division Summer Meeting (Jun. 1998), CD-ROM
96) H. Yoshida, H. Nakajima , M. Yoshida, Y. Hara and T. Shimamori, Experiment on foreign object damage of gas turbine-grade silicon nitride ceramic, ASME Paper 98-GT-399(Jun.1998)
97) Y. Hara, K. Matsubara, K. Mizuno, T. Shimamori and H. Yoshida, Development and evaluation of silicon nitride components for ceramic gas turbine, ASME Paper 98-GT-498Q Jun.1998)
98) T. Matsunuma, H. Abe, Y. Tsutsui and K. Murata, Characteristics of an Annular Turbine Cascade at Low Reynolds Numbers, ASME Paper 98-GT-518(Jun.1998)
99) P. W. Li, H. Daisaka, Y. Kawaguchi, A. Yabe, K. Hishida and M. Maeda, Experimental investigation of heat transfer enhancement for turbulence drag-reducing flow in a two-dimensional channel, Proc. 2nd EF conf. on Turbulent Heat Transfer 2(Jun. 1998), pp.P-21〜P-29
100) N. Iki, H. Furutani, J. Hama and S. Takahashi, Combustion Properties of Stoichiometric Hydrogen-Oxygen-Steam Mixture in Steam Environment, Proc. 12th World Hydrogen Energy Conf 2(Jun. 1998), pp.1479-1488
101) H. Furutani, H. Ryu, N. Iki, J. Hama and S. Takahashi, The ignition of H2-02-Ar mixture flows with ArF excimer laser - The influence of the flow speed, temperature and adding of ozone -, Proc. 12th World Hydrogen Energy Conf. 2-1(Jun.1998), pp.1489-1496
102) Y. Satoh, E. Deutsch and 0. Simonin, Direct Numerical Simulations of Heat Transfer by Solid Particles Suspended in Homogeneous Isotropic Turbulence, Int. J. Heat and Fluid Flow 19 (Jul.1998) pp.187-192
103) Y. Okuno, T. Okamura, K. Yoshikawa, H. Yamasaki, S. Kabashima, S. Shiota and Y. Hasegawa, High Enthalpy Extraction Experiments with CCMHD Fuji-1 Blow-down Facility, Proc. 29th Plasmadynamics and Lasers Conf. AIAA-98-2921(Jul. 1998), pp.1-8
104) M. Shiraishi, K. Seo, N. Nakamura and M. Murakami, Oscillating flow behavior in a pulse tube refrigerator under optimized conditions, Adv. in Cryogenic Eng. 43 (Jul. 1998), pp.2015-2021
105) N. Nakamura, M. Shiraishi, K. Seo and M. Murakami, Visualization study of oscillating flow inside a pulse tube refrigerator, Adv. in Cryogenic Eng. 43 (Jul. 1998), pp.2023-2030
106) N. Aya and T. Seto, Aerosol Particle Measurement by Photon Correlation Spectroscopy;Evaluation with using Differencial Mobility Analyzer, Proc. 5th Int. Cong. on opt. Particle sizing 1(Aug.1998), pp.19-20
107) F. Takemura and A. Yabe, Gas dissolution process of spherical rising gas bubbles, Chem. Eng. Sci. 53-15 (Aug.1998), pp.2691-2699
108) T. Munakata and I. Tanasawa, Study of Silicon Melt Convection during the RF-FZ Single Crystal Growth Process, Proc. llth Int. Heat Transfer Conf. 7 (Aug.1998), pp.223-228
109) E. Adams, M. Akai, L. Golmen, P. Haugan, H. Herzog, S. Masuda, S. Masutani and T. Osumi, An International Experiment on C02 Ocean Sequestration, Proc. Fourth Int. Conf on Greenhouse Gas Control Tech. (Aug.1998), p.46
110) T. Seto and K. Okuyama, Size and sign effect on the ion induced nucleation, J. Aerosol Sci. 29-51 (Sep.1998), pp.141-142
111) K. Okuyama, M. Shimada, T. Fujimoto, T. Maekawa, K. Nakaso and T. Seto, Effects of preparation conditions on the characteristics of titanium dioxide particles produced by CVD method, J. Aerosol Sci. 29-S1(Sep. 1998), pp.907-908
112) J. S. Shakal, S. S. Hwang, S. T. Hong, J. Y. Koo and S. Goto, A Comparison of Measured and Calculated Transient Injection Characteristics of a Pint-letype Injector for Direct Injection of LPG, 1998 FISITA World Automotive Cong., The Second Century of the Automobile -F98P502(Oct.1998), CD-ROM
113) D. Lee, J. Shakal, S. Goto and H. Ishikawa, Flame Speed Measurements and Predictions of Propane, Butane and Autogas at High Pressures, 1998 SAE Int. Fall Fuels & Lubricants Meeting & Exposition -982448 (Oct.1998), pp.1-7
114) J. S. Shakal, D. Lee, H. Ishikawa and S. Goto, Flame Front Speed of a Decane Fuel Cloud Under Microgravity Conditions, 1998 SAE Int. Fall Fuels & Lubricants Meeting & Exposition -982566(Oct.1998), pp.209-213
115) H. Ishikawa, J. Shakal, S. Goto and D. Lee, Investigation of the Combustion Mechanism of Fuel Droplets Under Microgravity Conditions by Numerical Simulation, 1998 SAE Int. Fall Fuels & Lubricants Meeting & Exposition -982615 (Oct.1998), pp.1-5
116) H. Ryu, H. Furutani, J. Hama and S. Takahashi, The Ignition of H2-02-03/H2-02-03-Ar Mixture Induced by the Photolysis of Ozone, JASME Int. J. B 41-4 (Nov.1998), pp.951-958
117) K. Shimizu, N. Shirai and A. Abudula, Monitoring System for VRLA Battery - Verification of Cell Base Monitoring Effectiveness and Outline of Prototype System -, Rroc. of the 15th International Electric Vehicle Symposium (EVS15) Sept. 29-Oct. 3, 1998, Brussels, Belgium Paper No. 169 (on CD-ROM)
Manufacturing Technology
Any enquiries regarding this project should be directed to e-mail: seisan0@mel.go.jp
Nano - fabrication based on Scanning Force Microscopy
The Scanning force Microscope (SFM) has proven to be a versatile instrument. Developed originally as a tool to map nano-scale surface structure, the SFM has recently attracted much attention for its potential in applications such as nano-lithography and super high density data storage. Various nano-lithography techniques have already been demonstrated, including electron beam lithography, x-ray lithography, and nano-imprint lithography. Although 10 nm scale fabrication has been demonstrated with both e-beam lithography and nano-imprint lithography, these methods are still under development and are very expensive. SFM provides a promising simple alter-native for nano-fabrication with potential resolution that may exceed that of other lithography processes.
We have begun a programme of research into nano-fabrication using a micromachined SFM cantilever, 147) for super high density data storage. Our device has unique features including self-scanning, excitation, and detection with piezoelectric film layers, as shown in figure 1. These characteristics make it possible for the device to both read and write at high scanning speeds without an external detection system. Figure 2 shows a SFM image of a nano-lithography pattern which was both written and read with the same device.
Fig.1 A self scanning excitation and detection AFM cantilever with piezoelectric thin film layers.
Fig.2 SPM image of nano lithography pattern written and read both by the same cantilever.
Nano - scale measurement technologies for dynamic surfaces
Various interesting phenomena occur at the points of contact between sliding surfaces, for example: tribocharging, changes in work function, formation of triboplasmas, and emission of electrons, ions, and electromagnetic waves.135) These phenomena are known collectively as triboelectromagnetic phenomena and surfaces at which these phenomena occur are known as dynamic surfaces. As the scale of the mechanical system reduces, the importance of these phenomena increases and we expect them to be significant in in-contact magnetic recording systems and micromachining applications. Nano-scale measurement technologies for investigating dynamic surfaces are under development and are already being used to improve our understanding of triboelectromagnetic phenomena. The figure shows: (A) a topographic image, (B) a cross-section of the topographic image, (C) a work function image (not absolute value) and (D) a cross-section of the work function image of a Si (111) surface scratched by Si trip in ultrahigh vacuum. The increase in work function occurring at the plastically deformed scratched surface can clearly be seen.
Fig.3 The topographic image (A) and its profile (B), and work function (not absolute value) image (C) and its profile (D) of the scratched Si (111) surface by Si in UHV, showing the increase of work function at the plastically deformed scrached surface.
Research into powder metallurgy
Power Metallurgy (P/M) techniques are capable of producing engineering components with good dimensional tolerances and attractive properties. P/M provides a highly efficient way to produce new materials with fine microstructure or composite structure. The application of P/M processes to Magnesium alloys results in refinement of the grain and intermetallic particle size, leading to improved mechanical strength. AZ91 alloys produced by the hot extrusion of gas atomized powders have a tensile strength of 36O MPa, which is about 3 times that of alloys produced by ingot metallurgy. Optimization of the production process should lead to further improvements in mechanical properties.
P/M methods also make it possible to fabricate high performance metal matrix composites. In our work, cluster diamond (CD) with good lubrication properties, was mixed with Al-Si-Cu-Mg or Cu-Sn alloy powders and hot-pressed to form composite materials. 129,130,144) The figure shows that the addition of only l vol% CD reduces the coefficient of friction. An especially large reduction in friction (42%) can be obtained in a matrix of Al-Si-Cu-Mg alloy. Wear characteristics are also improved. Although the addition of l vol% CD to Aluminium has almost no effect on wear, an improvement of 44% in wear was found when CD as added to the Al-Si-Cu-Mg system. The amount of added CD and the preparation process are currently being optimized to further improve friction and wear properties.
Fig.4 Friction coefficient of CD-dispersed composites.
Electrochemical Micromachining
Although electrodischarge machining (EDM) has potential application to the micromachining of metals, it suffers from tool wear which is a problem when three-dimensional shapes are to be manufactured. Electrochemical machining (ECM) has the advantage that there is no tool wear, but would not appear to be useful for micromachining because the electrode gap is greater than in EDM, making it difficult to produce fine details of machiming shape. We have worked on improving the accuracy of ECM by reducing the electrode gap with a novel electrode gap control system and varying the machining conditions. 151) We found that the electrode gap could be reduced to a few μm by lowering the machining voltage and electrolyte concentration. An experimental machine was also made to produce micro-components by ECM, and the photograph (Figure 5) shows a machined sample. It took about 10 minutes to machine one side of the square. Each side was machined in turn, rotating the work by 90゜ between each machining run.
Fig.5 An example of machined sample
Product End-of-life Strategies
Environmental consciousness is rapidly becoming a fundamental product design focus in a variety of industries. There is currently much work in the manufacturing sector to reduce energy consumption and emissions, and to eliminate hazardous materials from commercial products. Companies must now also assume that they will be responsible for retiring their products at end-of-life, in addition to taking some responsibility for environmental effects during manufacture and use. 124） To avoid costly product retirement, designers must identify ideal end-of-life strategies before specifying the structural attributes of the product.
This study seeks to identify relevant factors through a survey of current products and end-of-life strategieｓ. l25,l32) The study then aims to focus on key significant product characteristics and develop a methodology to guide product developers to an optimal end-of-life strategy.
Different products have different end-of-life strategies, depending on characteristics such as wear-out life, the technology cycle, the reasons for obsolescence, the number of different materials used, product cleanliness, and the number of modules in the product. Case studies and discussions with recycling organizations indicate that wear-out life and the technology cycle are two of the most important factors for the prediction of end-of-life paths. The categorization of products shown in the Figure 6 can help in the development of basic guidelines for product designers and developers of recycling technology (Table 1).
Fig.6 Product End-of-life strategy plot
Table 1 Guidelines for Product Designers and Recycling Technology Developers
Machining center with tool re-sharpening system
Run-out of the cutting edge of an endmill has an adverse effect on machining accuracy and surface roughness. The radius of gyration of the cutting edge is best evened up by re-sharpening the endmill when it is installed in the main spindle of the machining center. As part of a joint research programme, MEL and the Takashima Company have developed a machining center controlled by personal computer which has a built-in tool re-sharpening system.143) The system consists of a tool measurement unit, a grinding unit, and a control unit. Runout, which is typically 10-20 μm for a No.30 7/24 taper spindle, is reduced to less than 2 μm by on-machine re-sharpening. Cutting tests have shown that a better finish is obtained with an endmill re-sharpened using this system.
Fig.7 Machining Center with Tool Re-sharpening system List of Publications(1998) Manufacturing Technology
118) J. Akedo, M. Ichiki, K. Kikuchi and R. Maeda, Jet molding system for realization of three dimensional micro-structure, Sensors and Actuators A69 (Jun. 1998), pp.106-112
119) K. Miyazawa, R. Maeda and K. Itoh, Structure and expected piezoelectric propertes of sol-gel derived multilayer PZT films, Solid State lonics 108 (Jan. 1998), pp.85-90
120) A. Schroth, C. Lee, S. Matsumoto and R. Maeda, Appl. of sol gel deposited thin PZT film for actuation of Development of TD and 2D scanners, Proc. MEMS (Jan.1998), pp.402-407
121) T. R. Chung, N. Hosoda, T. Suga and H. Takagi, InGaAsP lasers on GaAs fabricated by the surface activated wafer direct bonding method at room temperature, Jpn. J. Appl. Phys. 37B (Mar.1998), pp.1405-1406
122) T. R. Chung, N. Hosoda, T. Suga and H. Takagi, 1.3 μm InGaAsP/InP lasers on GaAs substrate fabricated by the surface activated wafer bonding method at room temperature, Appl. Phys. Lett. 72 (Mar.1998), pp.1565-1566
123) I. Goncharenko, F. Kimura and K. Mon, Web-Based User Interfaces for Machine Tool Monitoring and Control, Proc. 31st CIRP Int. Seminar on Manuf. Systems (May 1998), pp.448-453
124) C. Boks, J. Nusson, K. Masui, K. Suzuki, C. Rose and B. H. Lee, An International Comparison of Product End-of-Life Scenarios and Legislation for Consumer Electronics, 1998 IEEE Int. Symp. for Elec. and the Environment Conf. (May 1998), pp.19-24
125) C. M. Rose, K. Ishii and K. Masui, How Product Characteristics Determine End-of-Life Strategies, 1998 IEEE Int. Symp. for Elec. and the Environment Conf. (May 1998), pp.322-327
126) N. Minami, T. Hongawa, Y. Nojiri, M. Nishida, T. Araki and M. Katsumura, Study on underwater thermal spraying, Thermal Spray 2-0 (May 1998), pp.1381-1386
127) S. Matsumoto, Molecular Dynamics Study of Diffusion of Liquid Molecules near the Three-Phase Contact, Proc. 7th AIAA/ASME Joint Thermo-phys. and Heat Transfer Conf. 3 (Jun.1998), pp.179-184
128) N. Kasashima, K. Mon, J. C. Fu and C. Troy, Prediction of Small Drill Bit Breakage Using Discrete Wavelet Transform and Discriminant Functions, Proc. 1998 Japan- USA Symp. on Flexible Automation 2(Jul. 1998), pp.749-753
129) K. Hanada, K. Nakayama, T. Sano and M. Mayuzumi, Development of Lubricative Al Alloy Based Matrix Composite with Cluster Diamond, Proc. 4th Int. Conf. on Adv. in Mater. And Processing Tech. 1 (Aug 1998), pp.483-489
130) K. Hanada, K. Nakayama, T. Sano, M. Mayuzumi and H. Negishi, Fabrication and Lubrication of Cluster Diamond Dispersed Cu Matrix Composite, Proc. 4th Int. Conf. on Adv. Mater. and Processing Tech. 1(Aug. 1998), pp.490-496
131) A. Schroth, R. Maeda, J. Akedo and M. Ichiki, Appl. of Gas Jet Deposition Method to Piezoelectric Thick Film Miniature Actuator, Jap. J. Appl. Phys. 37-9B (Sep.1998), pp.5342-5344
132) C. M. Rose, K. A. Beiter, K. Ishii and K. Masui, Characterization of Product End-of-Life Strategies to Enhance Recyclability, 1998 ASME Design for Manuf. Symp.DETC98/DFM-5742 (Sep.1998), pp.1-9
133) I. Alexanin, M. Alexanina, E. Herbek and 0. Ryabov, Scaling Property Estimation of Thermal Sea Surface Turbulent Structures on NOAA-Imagery, IEEE/OES Conf. Proc. 2(Sep. 1998), pp.1000-1005
134) M. Hattori, C. Tsutsumi, M. Dietzsch and C. Pertuch, Compatibility Studies of Different Methods of Measurement in the Nonometer Range, Proc. the Fourth Int. Symp. on Measurement Tech. and Intelligent Instruments (Sep.1998), pp.26-34
135) K. Nakayama, Triboelectromagnetic phenoma for various solids and tribosystems of head/disk sliding contacts in magnetic recording apparatus, Proc. NORDTRIB ,98, the 8th Int. Conf on Tribology (Sep.1998), pp.139-146
136) Y. Murakoshi, M. Takahashi, T. Sano, K. Hanada and H. Nagishi, Inside Bead Forming of Aluminium Tube by Electro-Magnetic Forming, 7th Int. Conf. Metal Forming 98 80-81 (Sep.1998), pp.695-699
137) K. Nakayama, Triboelectromagnetic phenomena, Proc. 2nd Symp. on Tribochemistry, 15-17, September 1997, Janowice, Poland (Sep.1998), pp.7-11
138) K. Nakayama, Triboelectromagnetism in the atmospheres of air and hydrocarbon gases and liquids, Proc. 12th Int. Symp. of Exoemission and its Appl. (Oct.1998), pp.227-232
139) K. Hatsukano, K. Shinozaki, H. Sawabe and K. Kuribayashi, Study of Carburizing of Cold Forged Parts Made of Chromium Steel, 6 th -China Symp. (Oct.1998), pp.167-179
140) Y. Okazaki, Fast tool servo system and its Appl. to three-dimensional fine surface figures, Proc. 98 ASPE Annual meeting (Oct. 1998), pp.100-103
141) K. Mizuhara and N. Ozawa, Experimental analysis of friction and wear characteristics of cermices under no lubrication plane-plane contact conditions, Proc. ASPE 1998 Annual Meeting 18(Oct.1998), pp.399-402
142) 0. Ryabov, K. Mon and J. Akedo, A Sensor-integrated Cutting Insert for On-line Tool Wear, Proc. 4th Japan/France/2nd Asia - Europe Cong. on Mech. (Oct.1998), pp.743-745
143) Y. Usui, S. Miyazawa, J.H. Lee, C. Endo, H. Akematsu and Y. Sakurai, Re-Sharpening End mill Sise-edge on a Maching Center, Proc. ASPE 1998 Annual Meeting 18 (Oct.1998), pp.124-127
144) K. Hanada, K. Imahori, K. Nakayama, T. Sano, M. Mayuzumi and H. Nagishi, Tribological Properties of Self-lubricative Cu composite with Cluster Diamond, Proc. 7th Int. Conf. on Processing and Fabrication of Adv. Mater. (Oct.1998), pp.369-380
145) S. Hirose, M. Yamaura, A. Yoshida, H. Ibuka, K. Hara and H. Munakata, Mechanism of Atomic Layer Epitaxy of AlAs, J. Crystal Growth 194 (Nov.1998), pp.16-24
146) N. Ozawa, K. Mizuhara, J. Akedo and K. Seimiya, Non-contact Air Holding Mechanism for Inspection of Pipe Inner Walls, J. Nuclear Sci. and Tech. 35-12 (Dec.1998),pp.952-957
147) J. Chu, R. Maeda, T. Itoh, K. Kataoka, T. Suga, A self scanning micro-SFM device using double PZT films, Proc. China-Japan Bilateral Symp. on Advanced Manufacturing Engineering (Oct.1998), pp.256-262.
148) T. Shimizu, Y. Murakoshi, T. Sano, R. Maeda and M. Yamaguchi, Fabrication of micro-parts by high aspect ratio straucturing and metal injection molding using the supercritical debinding method, Microsystem Tech. 1(Jan.1998), pp.1-3
149) S. Sugiyama, Y. Zhang, M. Hosoda, H. Ueno, 0. Tabata, S. Konishi and R. Maeda, Study on fabrication of high aspect ratio MEMS microparts using a compact SR beam-line, Microsystem Tech. 4(Jan. 1998), pp.61-63
150) N. Sasaki, M. Tsukada, S. Fujisawa, Y. Sugawara, S. Morita and K. Kobayashi, Load dependence of the frictional - force microscopy image pattern of the graphite surface, Phys. Rev. B 57-7(Feb. 1998), pp.3785-3786
151) K. Chikamori, Possibilities of Electrochemical Micromachining, Int. J. Japan Soc. Prec. Eng. 32-1 (Mar.1998), pp.37-38
152) R. Maeda, A. Schroth, T. Imai and C. Lee, Micro scanner actuated by PZT thin film, Proc. China-Japan Birateral Symp. on Adv. Manuf (Oct.1998), pp.226-231
153) J. Akedo, Deposition Method using Ultratime Particle Beam and its Applications, Proc. Int. Symp. on ECOMAP'98 (Nov.1998) pp.178-185
154) R. Maeda, Z. Wang, J. Chu, J. Akedo, M. Ichiki and S. Yonekubo, Deposition and patterning technique for realization of Pb (ZrO.52,TiO.48) thick film micro actuator, Jpn. J. Appl. Phys. 37-12B(Dec.1998), pp.1566-1569
Robotics
Any enquiries regarding this project should be directed to e-mail: robot0@mel.go.jp
The aim of robotics research at MEL is to develop advanced robotics technology using knowledge obtained by analysing the way in which tasks are performed by living beings. Current work includes the engineering implementation of skills found in humans and animals such as dynamic walking and manipulation, behaviour development by learning, virtual reality, tele-robotics, and human-friendly machines. A selection of robotics topics is introduced in more detail below.
Mobile robots with dynamic behaviour
We have proposed a new method for achieving autonomy in mobile robots. We define robustness to a changing environment (robust behaviour) and various dynamic skills (skill behaviour) in terms of Dynamic Behaviour Modules and aim to achieve autonomy in mobile robots by non-hierarchical combination of these modules. A wheeled inverted pendulum robot known as the Biped Leg-Wheeled Robot has been developed and used in experiments where it negotiated stairs with short treads. We have proposed a new dynamic trajectory planning method to shorten the staggering distance and improve landing stability, and this robot is now successfully able to rapidly climb and descend stairs.
We have developed a two-dimensional biped MELTRAN II and a simple stepping walker MELTRAN III in research towards developing practical biped robots which can negotiate rugged terrain. After theoretical studies, supported by experimental results from these two robots, we are now developing a three-dimensional biped MELTRAN V and have completed the basic mechanical design.
Legged mechanisms have high adaptability which helps when negotiating rough terrain, whereas wheeled mechanisms enable fast, efficient, movement over flat surfaces. A leg-wheel hybrid mobile robot which combines the advantages of the two types of locomotion has been developed. This robot is called: Walk'n Roll and has two front legs each equipped with three joints and a passive wheel, and two active rear wheels mounted on links with one degree of freedom.177)
A quadruped robot with coordinated leg movement, known as MELHORSE has been developed. The front and rear legs of the robot perform different functions in that the front legs mainly support the body against gravity while the rear legs provide forward thrust.
Fig.1 Successive motion of biped leg-wheeled robot
Fig.2 Leg-wheel hybrid mobile robot:Walk'n Roll
Dynamic control of robot systems
We are investigating control of 2-axis and 3-axis horizontal underactuated manipulators which have non-holonomic constraint at the passive joint. We have successfully achieved motion planning and feedback stabilisation.164,165,167,174,175,180)
A casting manipulator is a simple new type of manipulator which includes flexible elements, for example this kind of manipulator might include a flexible cord. Distant targets are reached by changing the length of the cord appropriately. A casting manipulator with two links has been constructed. Methods for controlling the swing of the arm and planning motion for throwing a gripper have been proposed and demonstrated experimentally.
A vibration-free robot crane has been developed by applying wave theory. In this system, both load transfer and vibration control are achieved by lateral motion of the load-support point. Experiments have proved the viability of this system in practical applications.158)
Fig.3 Overview of casting manipulator system
Skill-based control
A general framework for supporting skill discovery during the execution of robotic tasks has been developed. We define skill as a time-varying function which generates control information from sensory information so that skills cover dynamics as well as kinematics and statics. Skill functions have been approximated with polynomial expressions and skill discovery reduced to a combinatorial optimisation of the polynomial coefficients. This technique was demonstrated using the visual servo problem of a robot baseball player catching a flying ball.
Robot Devices
A stepping motor with three degrees of freedom has been tested for application of shoulder joints and robot eyes. Experimental results show that this novel motor is capable of achieving precise positioning with good control characteristics.
Virtual reality has attracted considerable attention as a new human interface technology. A new head mounted display is under development in which a small high resolution image is displayed in the center of the operator's field of vision, on top of a wide-angle low resolution image which fills the periphery. A wide angle image capture and display system has been developed and evaluated experimentally.
Learning and multi-agent systems
A mathematical model of the learning processes going on in human hand-eye coordination is under investigation. The coordinate transformation gain of a feedback controller is set by a novel learning model which uses the variations in the square of the hand position error norm.181) A parallel link manipulator system is under development in order to analyse human hand control and evaluate the learning model using virtual reality technologies.
A cooperative multiple robot system is under development. In this work, a human operator gives simple instructions to the system. Each robot refers to the instructions and generates an evaluation function to realise overall cooperation which is achieved by learning appropriate behaviour.159,179,185,188)
Pet robots are artificial creatures which appear to display emotion. The robot derives its motivation from its internal state and the stimulation it gets from physical interaction with a human, and seems to have emotion.
Integration of locomotion and manipulation
Integration of locomotion and manipulation is important for the general task of carrying an unknown object in an unknown environment. The basic concepts of locomotive manipulation, for manipulating a general unknown object, have been analysed using an integrated limb mechanism.
Tele-robotics and the human interface
Smooth communication between humans via a robotic system, rather than just between humans and robots, is necessary for successful tele-robotics. A new communication system has been developed to improve the human interface. A novel feature of the system is that it uses non-verbal visual information such as facial expression and gesture. Remarkable advances have recently been made in the synthesis of facial expression to much higher level than that found in common cartoons. This system can drastically reduce the volume of information that it is necessary to transmit from the original image sequence, and has potential for real-time application to the transmission of visual information via standard network image transmission systems.155,157,171,184,186)
The rapid advance of communication and information technologies has lead to the possibility of a practically useful teleoperation system which can be easily used by large numbers of people. In this kind of system, one of the most strict limitations is the information carrying capacity of conventional communication systems-for example an ordinary telephone line. We have proposed a new task-based data exchange method where the ratio between the volumes of control information and visual monitoring information is changed according to the task characteristics, to most effectively use the limited capacity of the communication link.169,178)
Fig.4 Tele-operation tasks using ISDN
Human support machines
Human friendly machines which are physiologically and psychologically friendly to human beings are required to help people who are disabled and unable to lead a full life.
A new type of stair lift for wheelchair users has been developed with the aim of providing a system which is inexpensive, quiet, and practical. A crawl type mechanism has been developed for this purpose, in which the rotational motion of a disk is converted to linear motion of the hoist carrier plate. A prototype model was fabricated to demonstrate the characteristics of this mechanism which can go up and down the inner side of a half-turn staircase.170) This technology has been transferred to the private sector.
Arm disabilities prevent full participation in everyday activities, and an upper limb motion assist system has been proposed which uses flexible cords to provide assisted movement. The arm is suspended on a parallel arrangement of cords, and is moved by changing the length of the cords in sequence. An experimental prototype has been built and is currently being tested using a model arm.
A new, efficient, power assist system has been proposed which uses two different assist ratios for static and dynamic loads. This technique has proven very effective in avoiding actuator saturation and achieving stable power control.176) A mobile power assist system is under development which will be capable of operating over a wide area.
Humanoid robot project
Humanoid robots should move in a similar fashion to human beings and should be able to assist humans in our normal living environment. A comprehensive simulator, which is equivalent to a real humanoid robot, and incorporates modelling dynamics, geometry, actuators, sensors, a controller, and environmental factors, is under development towards realising an actual humanoid robot. Various control methods and experiments incorporating reversible tasks are under investigation with the simulator. Work is also in progress to estimate the characteristics required of components for the robot (such as actuators) and to predict the movement capability of a humanoid robot using existing components.
Fig.5 Evaluation of a robust control method against environmental disturbances by using humanoid robot simulator List of Publications(1998) Robotics
155) K. Ohba, Y. Satoh and K. Ikeuchi, Appearance Based Visual Learning and Object Recognition with Illumination Invariance, Proc. Third Asian Conf. on Computer Vision (ACCV'98) 2(Jan.1998), pp.424-431
156) T. Takatsuji, M. Goto, T. Kurokawa, Y. Tanimura and Y. Koseki, The first measurement of a three-dimensional coordinate by use of a laser tracking interfer-ometer system based on trilateration, Measurement Sci. Tech. Institute of Phys., UK 1-0(Jan. 1998), pp.38-41
157) K. Ohba, T. Tsukada, T. Kohtoku and K. Tanie, Facial Expression Space for Smooth Tele-Communications, Proc. Third IEEE Int. Conf. on Automatic Face and Gesture Recognition (FG'98) (Apr.1998), pp.378-383
158) M. Saigo, N. Tanaka and K. Tani, An Approach to Vibration Control of Multiple-Pendulum System by Wave Absorption, Trans. of the ASME, J. Vibration and Acoustics 120-April(Apr. 1998), pp.524-533
159) K. Ohkawa, T. Shibata and K. Tanie, A Method for Controlling a Group of Robots by an Operator, Proc. 4th Int. Symp. on Distributed Autonomous Robotic Systems (May 1998), pp.309-318
160) H. Maekawa and J. M. Hollerbach, Haptic Display for Object Grasping and Manipulating in Virtual Environment, Proc. Int. Conf. on Robotics and Automation (ICRA'98) (May 1998), pp.2566-2573
161) Y. Koseki, T. Arai, K. Sugimoto, K. Takatsuji and M. Goto, Design and Accuracy Evaluation of High Speed and High Precision Parallel Mechanism, Proc. Int. Conf. on Robotics and Automation 1998, (ICRA'98) 2(May 1998), pp.1340-1345
162) H. Arisumi, T. Kohtoku and K. Komoriya, Swing Motion Control of Casting Manipulation (Experiment of Swing Motion Control), IEEE Int. Conf. on Robotics and Automation (ICRA'98) 4(May 1998), pp.3522-3527
163) H. 0. Lim, K. Yokoi, Q. Huang, S. R. Oh, A. Takanishi and K. Tanie Collision - tolerant Control algorithm for Mobile Manipulator with Viscoelastic Passive Trunk, Proc. 1998 IEEE Int. Conf. on Robotics and Automation (May 1998), pp.13-20
164) K. Lynch, N. Shiroma, H. Arai and K. Tanie, Motion Planning for a 3-DOF Robot with a Passive Joint, Proc. 1998 IEEE Int. Conf. on Robotics and Automation (ICRA'98) (May 1998), pp.927-932
165) K. Lynch, N. Shiroma, H. Arai and K. Tanie, The Roles of Shape and Motion in Dynamic Manipulation: the Butterfly Example, Proc.1998 IEEE Int. Conf. on Robotics and Automation (ICRA'98) (May 1998), pp.1958-1963
166) Q. Huang, S. Sugano and K. Tanie, Motion Planning for a Mobile Manipulator Considering Stability and Task Constraints, Proc. 1998 IEEE Jnt. Conf. on Robotics and Automation (ICRA '98) (May 1998), pp.2192-2198
167) H. Arai, K. Tanie and N. Shiroma, Time-scaling Control of an Underactuated Manipulator, Proc. 1998 JEFF Int. Conf. on Robotics and Automation (JCRA'98) (May 1998), pp.2619-2626
168) A. Kheddar, K. Tanie and P. Coiffet, Detection of Discrepancies and Sensory-Based Recovery for Virtual Reality Based Teleoperation Systems, Proc. IEEE Int. Conf. on Robotics and Automation (May 1998), pp.2877-2883
169) A. Kheddar, C. Tzafestas, P. Coiffet, T. Kohtoku and K. Tanie, Multi-robot teleoperation using direct human hand actions, Advanced Robotics 11-8(Jun. 1998), pp.799-826
170) S. Hashino, Development of crawl-type stairlift for half-turn staircase, Proc. 1998 Japan- USA Symp. on Flexible Automation (Jul. 1998), pp.23-26
171) K. Ohba, G. Clary, T. Tsukada, T. Kohtoku and K. Tanie, Facial Expression Transportation with FES, Proc. Int. Conf. on Pattern Recognition (JCPR'98) 2(Aug. 1998), pp.1376-1378
172) K. Tanie, Force Display and Its Appl. to Telerobotics, Proc. Fourth ECPD Int. Conf. on Adv. Robotics, Intelligent Automation and Active Systems (Aug.1998), pp.26-31
173) T. Takatsuji, Y. Koseki, M. Goto and T. Kurosawa, Restriction on the arrangement of laser trackers in laser trilateration, Measurement Sci. and Tech. 9 (Aug.1998) pp.1357-1359
174) N. Shiroma, H. Arai and K. Tanie, Nonholonomic Motion Planning for Coupled Planar Rigid Bodies, Proc. 3rd Int. Conf. on Adv. Mechatronics (JCAM'98) (Aug. 1998), pp.173-178
175) H. Arai, K. Tanie and N. Shiroma, Time-scaling Control of an Underactuated Manipulator, J. Robotic Systems 15-9 (Sep.1998), pp.525-536
176) Y. Hayashibara, K. Tanie, H. Arai and H. Tokashiki, Evaluation of Compensation Ratios in a Power Assist System Based on Operational Sensation, Elec. Eng. in Japan 124-3 (Sep.1998), pp.57-63
177) H. Adachi, N. Koyachi, T. Arai and A. Halme, Development of a Leg-Wheel Hybrid Mobile Robot, Proc. the 2nd Tampere Int. Conf. on Machine Automation (Sep.1998), pp. 145-154
178) A. Kheddar, P. Coiffet, T. Kohtoku and K. Tanie, Multi-Robots Teleoperation - Analysis and Prognosis, Proc. IEEE Int. Workshop on Robot and Human Communication (Sep. 1998), pp.166-171
179) K. Ohkawa, T. Shibata and T. Tanie, Method for Generating of Global Cooperation Based on Local Communication, Proc. IEEE/RSJ. Int. Conf. on Intelligent Robots and Systems (Sep.1998), pp.108-113
180) H. Arai, K. Tanie and N. Shiroma, Nonholonomic Control of a Three-DOF Planar Underactuated Manipulator, IEEE Trans. on Robotics and Automation 14-5(Oct. 1998), pp. 681-695
181) E. Ohyama and S. Tachi, Coordinate Transformation Learning of Hand Position Feedback Controller by Using Change of Hand Position Error Norm, Proc. 20th Annual Int. Conf. of the IEEE Eng. in Medicine and Biology Soc. 1998 (Oct.1998), pp.2358-2361
182) T. Yano, S. Numao and Y. Kitamura, Development of a Self-Contained Wall Climbing Robot with Scanning Type Suction Cups, 11th Int. Conf. on Intelligent Robots and Systems (IROS98) (Oct.1998), pp.249-254
183) H. Arisumi, T. Kohtoku and K. Komoriya, Study on Casting Manipulation (Experiment of Swing Control and Throwing), IEEE/RSJ. Int. Conf. on Intelligent Robots and Systems (IROS98) 1(Oct.1998), pp.494-501
184) K. Ohba and K. Ikeuchi, Stable Recognition of Specular Objects by the Eigenwindow Method, Systems and Computers in Japan, 29-7 (Nov.1998), pp. 12-20
185) K. Ohkawa, T. Shibata and K. Tanie, Generation Method of Evaluation for a Robot Considering Relations with Other Robots, J. Robotics and Mechatronics 10 - 4 (Nov.1998), pp.284-288
186) S. Hiratsuka, K. Ohba, S. KaJ. ikawa, H. Inooka and K. Tanie, Stable Gesture Verification in Eigen Space, Proc. IAPR Workshop on Machine Vision Appl. (Nov.1998), pp.119-122
187) S. Hashino and K. Homma, Human Support Technology Division, J. Robotics and Mechatronics 10 - 6 (Dec.1998), pp.542-543
188) K. Ohkawa, T. Shibata and K. Tanie, Self-generating Algorithm of Evaluation for Cooperative Behavior, Artif. Life Robotics 2 (1998), pp. 138-143
Micromachines
Any enquiries regarding this project should be directed to e-mail: kyoku0@mel.go.jp
Micromachines ( that is, machines which are very much smaller than conventional machines ) are expected to bring many dramatic technological innovations in applications such as plant maintenance and medical science. Recognising the importance and potential of micromachines, the Agency of Industrial Science and Technology began research early on in the development of the field in 1991, with a 10-year Industrial Science and Technology Programme entitled: Research and Development Project on Micromachine Technology . MELs work in this project includes studies of technologies for evaluating micromachines and their components, and the micro-factory.
Evaluation technology Tensile testing of thin films
A novel tensile testing machine has been used to study the effect of sputtering gas (Ar) pressure on the mechanical properties of thin films of Titanium, about 0.4 μm thick. The Ti films were deposited on to Polyimide films 5 μm thick by magnetron sputtering. The Polyimide films were on Silicon wafers.
The sputtering gas pressure was varied from 1.5mT to 8mT, and stress-strain characteristics of the films were measured in the atmosphere at room temperature. It was found that both tensile strength and breaking elongation were affected by the sputtering gas pressure, with tensile strength increasing as the pressure was reduced. Youngs modulus was found to be independent of the pressure.
Fig.1 Effect of Sputtering Gas (Ar) Pressure on Tensile Strength of Ti Thin Films
Micro asperity for reduction of frictional forces
The friction and pull-off forces between an Atomic Force Microscope (AFM) probe and sub-micron size asperities on a silicon wafer have been measured in experiments to find a way to reduce frictional forces in micromachines. A focused ion beam was used to produce both two-dimensional arrays of asperities and single features. The radii of curvature of the asperities varied from 7l nm to 941 nm and the tip of the AFM had a flat, square surface measuring 0.7x0.7 μm. It was found that both the friction and pull-off forces were proportional to the radius of curvature of the tip of the asperity, independent of the asperity surface microroughness. The friction force was proportional to the pull-off force.197)
Fig.2 Relation between friction and pull-off forces and radius of curvature on asperity array
Room temperature direct bonding of Si and LiNbO3
Bonding technology is important in the fabrication of three-dimensional microstructures and in realising flexible fabrication processes using various combinations of materials. The applications of bonding have been limited until now because conventional methods require heat and/or high voltage, both of which may damage materials and microstructures. A new method of bonding Silicon and LiNbO3 wafers at room temperature has been developed. As shown in the figure, the surfaces to be bonded are first etched by Ar beam sputtering which creates clean surfaces with high bonding capability. The surfaces are then brought together in a vacuum, and bond. Experiments have shown that both Si-to-Si and Si-to-LiNbO3 bonds prepared in this way at room temperature have strengths equivalent to those of the bulk materials. In addition, it is not always necessary to load the specimens to force them together to create a bond. This method has significant advantages over conventional techniques.l93,l94,l98)
Fig.3 Bonding in a vacuum using Ar beam etching
Functional fabrication
We used ion implantation techniques in the fabrication of microstructures by implanting Silicon with ions and then etching through a micropatterned mask, making use of the difference in etch rates between implanted and non-implanted silicon. The figure shows two examples of our work: a micromesh and a microcantilever, which were fabricated by etching with KOH solution after implantation with Gold, Carbon, or Titanium. Distinctive three-dimensional structures can be made by creating different implantation profiles with depth. Although these structures have some distortion due to residual stress, they are sufficiently good for practical applications. We expect this problem to be overcome by optimising the fabrication conditions. In addition, modified structures like this have controlled properties which are useful for practical micro-devices.189,190,191,196)
Fig.4 SEM image of a microcantilever structure. Gold implanted into silicon using a micropatterned mask and etched with KOH solution
Microfactory Robustness evaluation of micro-lathe design
Machine tools currently used to produce miniature components are usually very large compared to the components they are used to make. There has as yet been inadequate research into whether these very large tools are actually necessary to achieve the required tolerances. We have proposed a design evaluation method which uses the form-shaping function of the machine tool combined with the Taguchi method to determine which design parameters have significant influence on machining tolerances. This year, we used this procedure to analyse the design of a micro-lathe in the context of miniature machine tools, to demonstrate the importance of the different design parameters. The results, shown in the figure, demonstrate that the method is useful for the evaluation of existing micro-lathe designs.
Fig.5 Effect of design parameters on machining tolerance
Micro-manipulators for microfabrication
Micro-manipulation technology has been developed for assembling complete micromachines from miniature components, as part of our work on the micro-factory. This technology has many potential applications, including microscopic surgery and cell manipulation. We have developed a two-fingered micro hand with six degrees of freedom, based on sequentially arranged parallel mechanisms. Precise manipulation of microscopic objects has been achieved using tele-operation control and an auto-focus microscope. A micro-scarecrow just 25 μm in height was made using this system in conjunction with an adhesive bonding device.201,202)
Fig.6 Micro scarecrow List of Publications(1998) Micromachines
189) H. Ogiso, W. Mizutani, S. Nakano, H. Tokumoto and K. Yamanaka, Lattice disorder and density of states change of graphite surface by single ion impact, Appl. Phys. A 66-2 (Mar.1998), pp.S1155-S1158
190) H. Ogiso, W. Mizutani, S. Nakano, H. Tokumoto and K. Yamanaka, Lattice disorder and density change of graphite surface by single ion impact, Appl. Phys. A 66(Mar.1998), pp.S1158
191) H. Ogiso, H. Tokumoto, S. Nakano and K. Yamanaka, Widely changing probability of surface damage creation induced by a single ion in the MeV ion energy range, J. Vacuum Sci. and Tech. B 16-4(Jul. 1998), pp.1914-
192) M. Kuroda, Y. Ishikawa, H. Aramaki and T. Kitahara, Control of Nonlinear Dynamics for Realization of Downsized Machine Tools (1st Report; Mathematical Modeling and Fundamental Experiments on Metal Cutting Process), Proc. 1998 Int. Symp. on Nonlinear Theory and its Appl. S (NOLTA '98) 2(Sep. 1998), pp. 539-542
193) H. Takagi, R. Maeda, T. R. Chung, N. Hosoda and T. Suga, Effect of Surface Roughness on Room Temperature Wafer Bonding by Ar Beam Surface Activation, Jpn. J. Appl. Phys. 37 (Jul. 1998), pp.4197-4203
194) H. Takagi, R. Maeda, T. R. Chung and T. Suga, Low-temperature direct bonding of silicon and silicon dioxide by the surface activation method, Sensors and Actuators A 70 (Oct. 1998), pp.164-170
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Quantum and Molecular Mechanical Engineering
Any enquiries regarding this project should be directed to e-mail : kyokuo@mel.go.jp
Special Research Group for Quantum and Molecular Engineering
The Special Research Group for Quantum and Molecular Mechanical Engineering was established in the Mechanical Engineering Laboratory in July 1997, and received formal recognition from the Agency of Industrial Science and Technology in April 1998. The group includes scientists from several different departments of the laboratory and is an interdisciplinary team working on advanced mechanical engineering based on nano-scale effects.
The objectives of the group are to use nano-scale effects to open new frontiers in mechanical engineering, and to create a new field of academic and engineering endeavor in quantum and molecular mechanical engineering. Current research topics are described below.
Advanced Chemo-mechanical Engineering
Fundamental studies have been made of the mechanisms involved in the production of glass and ceramics in environments containing water or materials capable of providing copious amounts of hydrogen bonding. These conditions facilitate the production of glass and ceramics, and the effects occurring during this process (which have been known for over one hundred years) are known as chemo-mechanical effects. Nonetheless, these phenomena are not yet understood at the microscale level, and our objective is to investigate dynamic mechanisms at the molecular level and develop advanced technology for ultra-fine machining of glass and ceramics which uses them and will produce devices useful in the optical and energy industries.
Fig.1 Concept of boundary slip
Advanced Energy Conservation Technology
Advanced technologies based on microscale phenomena have been studied in order to further develop energy conservation technology. Novel ice slurries which use microscale interaction between molecules and surfaces have been realized, and we have been able to obtain the first STM (Scanning Tunn&ing Microscope) images of the ice surfaces on which molecules are adsorbed.
Micromachining technologies have been used to produce microscale surface structures for reducing surface drag in liquid flow. Drag reduction has also been reported when water-repellent paint is used as a surface coating, but the microscale mechanisms behind this phenomenon are not yet understood. MEMS techniques can be used to produce water repellent surfaces which are have small-scale con-cave/convex structures together with certain chemical properties, and so various different kinds of small-scale concave/convex structures have been investigated in this project. Several possible mechanisms for the drag reduction have been proposed, including the presence of residual air entrapped in the cavities (shown in figure 1), and slip close to the surface arising from reduced molecular interaction between the liquid and solid due to the low surface energy of the water repellent material.
One of the surface structures produced in the project by micromachining techniques gave a drag reduction of 10% compared to a smooth surface as shown in Figure 2. This technique is useful for reducing drag in the laminar flow region and has potential for application to hydrodynamic pumps and piping systems.
Fig.2 Friction coefficient results for a micromachined surface.
