This paper presents a solution algorithm of generalized eigenvalue problem with non-positive definete mass matrix. The accuracy of the natural frequency is much higher using 20-node hexahedral elements than using 8-node elements. However, lumped mass matrix which reduces the computation cost could not be used combined with the 20-node elements, because the mass matrix would be non-positive definite in the case. Applying the proposed algorithm, the generalized eigenvalue problem with non-positive definite mass matrix can be solved with the same computation cost as for the solution of eigenvalue problem with positive difinite mass matrix.

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In this paper, a new vibration method to estimate the tension T and the flexural rigidity EI of the one-dimensional beam is proposed. In this method periodic relation between the natural frequencies and the mode number is analytically derived from the frequency equation of lateral vibration in the beam, clamped at both ends with tension T.T and EI are estimated using least squares for the plural natural frequencies and modal numbers. As the result of numerical simulation of this method T and EI are estimated accurately in case of clamped and simply supported boundary condition at both sides of the beam. In case of unknown boundary condition the precision of T and EI is calculated quantitatively. Experiments using steel rods were achieved to verify the present method. Experiments boundary condition is between clamped and simply supported, and there is a good accuracy between the precision of experiments and the precision of numerical simulation.

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The present paper shows an efficient optimization approach on composite structures for vibration where layer angles in addition to layer thicknesses are used as design variables. A high-quality approximation method of natural frequencies with respect to layer angle and layer thickness is proposed. First in the present paper, several approximate methods of natural frequencies after design variation are compared. Next, an approximation method is then applied to a minimum weight design of cantilevered laminated plates under multiple frequency constraints. The validity of the present approach is verified through the numerical examples of laminated plates.

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A new dynamical simulation algorithm applicable to a very large class of rigid and flexible multibody systems is presented. It is based on a variable-gain penalty method with scaling, and has the following distinctive features : (i) All kinds of holonomic and nonholonomic equality constraints can be treated in a plain and unified manner ; (ii) Stability and specified admissible error of the constraints are always attained ; (iii) The formulation has an order N computational cost in terms of both the constrained and unconstrained degrees of freedom, regardless of the system topology ; (iv) Unlike the traditional recursive order N algorithms, it is quite amenable to parallel computation ; and (v) Since no matrix operations are involved, it can be implemented to very simple general-purpose simulation programs. Versatility, dynamical validity and efficiency of the approach are checked through numerical studies of several particular systems.

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A new formulation applicable to a very large class of rigid and flexible multibody systems subjected to equality and latch-type inequality constraints is presented. It is a natural extension of the variable-gain penalty method for systems with holonomic and nonholonomic equality constraints, developed by the author. This paper focuses on the conversion of the inequality constraints to equalities, though it also summarizes the penalty algorithm. Dynamical validity and efficiency of the approach are checked through numerical study of a flexible link system with a latch joint.

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This paper presents the research on the coupled vibration of the turbine blades grouped by a shroud band. Our first report detailed a theoretical analysis concerning the effect of longitudinal and bending flexibility of shroud band on tangential flexural vibration. In this paper we deal with the interactive between axial flexural vibration and torsional vibration of turbine blade, which is occurred in an actual turbine. We have calculated the effect of the ratio of the lenght of bale to the width of that with constant thickness of shroud band on vibration behavior. In an analytical treatment, a physical model of six blades per shroud is analyzed by using the transfer matrix method. The set of six turbine blades per a shroud band is usually used in an actual turbine design. An analytical treatment for the six blades per a shroud band does not become complex, and the vibration characteristics of it can be seen clearly. The analytical treatment developed in this paper is also applicable for the case of having the other number of blades per a shroud band. It was found that the vibration characteristics of grouped blades of turbine per a shroud band largely depend on the ratio of the length to the width of turbine blade, and there is significant interference between axial flexural vibration and torsional vibration. Some results are presented in the form of parametric plots and tables.

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This paper presents a theoretical global formulation of general response solution for the oscillator system in which the restoring force can be expressed by piecewise linear (PL) function. First, in order to generalize global form of local solution obtained by pseudo-feedback approach proposed in the previous paper, responce difference summation form is defined by introducing a parameter of IRRD (inter region response difference). Secondly, through transformation of this summation form into pseudo-feedback form, a global representation of general solution in terms of local solutions can be obtained for piecewise linear oscillator system. By use of the global representation, all forms of general solutions for the oscillator without "trapping" can be exactly determined. This calculation is carried out by superposition of the system response obtained over standard linear region and the pseudo-feedback response series described by IRRD.

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Both self-centering path and abnormal vibration orbit of a floating sun gear shaft in a star-type planetary gear train are numerically simulated taking account of effects of friction forces acting on gear teeth instead of viscous damping forces. The simulation model is composed of a floating sun gear with three degrees of freedom x, y and θ and six meshing springs with backlash. Equations of motion of the sun gear are solved by the Runge-Kutta method. Firstly, the static friction coefficient was determined by experiments. In the simulation, it is used for obtaining the self-centering path, while the dynamic friction coefficient is assuumed for obtaining the abnormal vibration orbit. The self-centering path depends on the initial position of the sun gear in the experiment. The self-centering simulation considering the friction force gives the same results as the experimental ones. It is also shown that the simulation of abnormal vibration orbit gives the good accordance with the experimental results when the friction forces instead of the damping forces are accounted in the model.

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Generally, in a structural-acoustic analysis of a cabin such as those of super express trains, there are more than a hundred eigen modes. In order to calculate the eigen modes, however, a long computational time and a huge memory are needed. An effective numerical method for simulating large scale structural-acoustics of a real-size cabin (such as super express trains) has been developed. In the analysis, a solution procedure of shifted eigen value is applied. The influence of the number of eigen modes in the vibration response on the accuracy of the simulated vibration and acoustics was determined. Moreover, noise levels corresponding to four kinds of frame structures with or without damping material are calculated and discussed. In the frame structure, extrusion with rib, extrusion with rib and damping layer, hollow extrusion, or hollow extrusion with damping layer are used. As the result of four calculations, frame structure with damping material enables to reduce the noise level.

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This paper describes a new design method for electric fans not only to reduce the blade passing frequency (BPF) noise but also to minimize the unbalanced forces of rotors. For the suppression of BPF level, the fans with unequally spaced blades have been proposed. Such fans, however, are likely to cause unbalanced vibrations by the asymmetric blades. In this paper, the relations between the unbalanced forces of rotors and the blade arrangements are discussed, and the design methods for minimizing the unbalanced forces are proposed. Furthermore, the condition for realizing completely balanced fans is derived.

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In this study, we focus on the error of estimated frequency of disturbance and present a new adaptive multiple frequency tracking and new modification law after examining relation between the error of frequency and output level in detail. We also develop a multiple frequency estimation algorithm, which is insensitive to observation noise and prove the asymptotic stability for adaptive nonlinear algorithm and adaptive frequency tracking method theoretically. The results of simulation show that when entimated frequency by difference equation method approach to the true value, then the output error converges to zero (or equilibrium point) asymptotically. This corresponds to the asymptotic stability condition. The effectiveness of this method and the theoretical proof are verified by simulation. The experimental results show that the proposed algorithm is effective for achieving unbalance vibration suppression.

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In this paper, we design tracking controller for mechanical system with second-order nonholonomic constraints using transformation of the time scale. First, we review the equivalence of trajectry in configuration space under consideration of time scaling and try to introduce a time scaling function for the second-order derivatives. We find that the time scaling function can be treated as a control input. Using linearization theory of nonlinear systems, we design a tracking controller that has one more additive control input and a linear form. Finally, the controller is applied to 3-link mechanism, simulations show that the proposed controller works effectively.

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This paper is concerned with a study of the high performance realization of electronic engrave technology. Using actual piezo actuator for ultra-high speed electronic engrave machine, we designed several control systems to realize a good performance, after the system identification and modeling. The designed control strategies consist of (i) LQI servo control, (ii) Two-degree-of-freedom control system, (iii) Sliding mode control with observer, (iv) Sliding mode control with output feedback. Incidentally, we also find out the compulational speed limit of DSP system via the experiments. We realized the good performance using the two-degree-of-freedom control and the sliding mode control with observer. The most important contribution of this study is that the experimental results can be directly used to commercial machine.

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This paper proposes a control method for a rigid body motion system which has unknown nonlinearities such as variation of inertia, corioli's force, nonlinear driving system, gravity and friction. Sisce feedback control has delay, it is insufficient for precise tracking control in motion system. Then, feed forward control is necessary. In order to execute feed forward control for uncertain of unknown motion systems, the control system to obtain the motion model must be implemented in the control system. In this paper a method of obtaining the motion model is proposed. It gets possible no consitute inverse dynamics of the motion system and feed forward control by this method. In this paper the method of obtaining the motion model is derived by hyper stable theory. Further, this paper shows the effectiveness of the proposed motion control method by demonstrating an experiment of tracking desired trajectory in a 2 Degrees of Freedom link motion system.

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Feasibility for suppressing the structual vibration with Adaptive Gyroscopic System(AGS)is investigated. A concept of the AGS, of which the moment of inertia is controllable, is briefly described as an extension of that of the conventional gyroscopic damper. A general form of dynamic equations of motion for the one-dimensional flexible structure model with the AGS has been derived by utilizing the principle of virtual work. The optimal parameters of the AGS for the frequency response function and the modal damping ratio are obtained to apply the AGS passively/actively to multiple modes vibration suppression. Numerical results show the improvement of the performance for suppressing higher mode vibration of flexible structures with the AGS.

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This paper deals with the design method for a tuned pendulum damper(TPD)to suppress the wind induced coupled flutter of a bridge deck, and deals with the effect of a multiple TPD(MTPD)in order to improve the robustness of the single TPD. The design method for TPD is established using control theory on stability for the coupled flutter which is a self exciting vibration system related to asymmetry of the stiffness and damping matrices. This method is extended to the design for MTPD. Thus, it is confirmed that the robustness against tuning error of TPD's frequency and damping is increased by MTPD because of the decreasing of the response of the deck torsional mode and the changing of the phase of the flutter system compared with the single TPD.

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Robust control based on the H^∞ control theory has been applied to the control of hybrid mass damper system installed on an actual 23-story building known by the name of J-City Tower in Tokyo, with the view of reducing simultaneously bending in two horizontal directions and torsional oscillations induced by strong winds and moderate earthquakes. Identification modal parameters resulted from building excitation tests, conducted by using mass damper system as excitation device, were adopted for the control system design, to ensure both damping effect of the 1st bending/torsional mode and robust stability for higher modes over the 2nd. After installation of the H^∞ controller, excitation test results confirmed that this system has provided control effect satisfying largely what was aimed in design, and that good agreement has been obtained between measured and calculated results. Furthermore, system performance has been recorded continually, and analysis of observation data during earthquake has proved that this system has been actuated effectively.

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This paper describes the attitude control problem of a flexible parameter varying spacecraft. Considered herein is the spacecraft consists of the main rigid body and some flexible solar panels which rotate at the orbital rate in order to generate more electricity. In this case, the interference characteristics of the elastic vibration of the panels and the attitude motion of the body changes depending on the panel angle. Therefore, the attitude control system of such spacecraft becomes parameter varying. This paper is intended to establish the systematic robust controller synthesis procedure for this problem by applying Gain Scheduling framework. This controller is designed by H_∞ sysnthesis via LMI. Capability of the method is investigated by the numerical study using the model of the ETS-VI spacecraft.

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This paper presents a method of robust model following control for nonminimum phase discretetime systems in the presence of unmodeled dynamics. This scheme can robustly control the nominal model in the presence of unmodeled dynamics and achieve the desired model following simultaneously. Furthermore, the sufficient condition for stabilizing the nominal model in the presence of unmodeled dynamics is derived and the existence of bounds for all signals is proved. Finally, computer simulation results are presented to show the effectiveness of the proposed method.

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A feedback gain tuning method is proposed to stabilize an inverted pendulum which has the structure applicable to iterative trial movements. This tuning algorithm is composed of the Complex Method and has the following features: (1)It does not need the dynamic model of controlled system. But if the model is available, the tuning convergence becomes improved. (2)It tunes the feedback gain under an arbitrary performance index and is applicable to both the linear and the nonlinear control law. (3)The algorithm is concise and the number of adjusting parameters to be decided by the operator is least. (4)The tuning convergence is fast and the on-site tuning for real system is possible. It is also effectively confirmed by the experiments using both the simulation and the real system that the proposed tuning method has good features mentioned above.

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Geometric modelling of the environment is important in robot motion planning. Generally, shapes can be stored in a data base, so the elements that need to be decided are positions and orientations. In this paper, surface-based geometric modelling using a teaching tree is proposed. In this modelling, combinations of surfaces are considered in order to decide positions and orientations of objects. The combinations are represented by a depth-first tree, which makes it easy for the operator to select one combination out of several. This method is effective not only in the case when perfect data can be obtained, but also when conditions for measurement of three-dimensional data are unfavorable, which often occur in the environment of a working robot.

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In order to prove the effectivity of the computational scheme described in part 1, the six DOF articulated robot mechanism with a planar loop for driving the arm and the mechanism with two loops having different motion spaces which is equivalent to the Sarrus mechanism are analyzed in this paper. It is shown by these analysis examples, the derermination of joints for loop cut and that of a basis of wrench space for each loop cut joint are essential for the analysis. It is derived that the loop cut joint shall be one of joints which belongs one loop only, or, if such a joint does no exist in the loop, one of joints in the loop which belongs smallest number of loops. The basis of a wrench space of the loop must be determined such that it is composed of the elements of a basis of the reciprocal space of the motion space of the loop and those of a basis of complement space of the reciprocal space.

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This research is concerned with a new technology on image recognition of objects using neural networks. The standard method of pattern recognition is geometrical pattern matching. However, it is generally difficult to recognize figures on frosted glass because the brightness difference is pretty little. In this research, a new image recognition system is proposed by the application of image processing and neural networks. First, the figure pattern has been extracted from the frosted glass by using two kinds of smoothing filters, and transferred to a binary pattern by threshold value. Second, the extracted pattern including plural figures has been separated in single ones respectively through the technique using the labeling processing. This method is based on a combination of the labeling and the center of gravity. Third, a figure pattern with noise and broken form has been transformed into a well-regulated one by pattern exchange system using neural network. Finally, a figure pattern has been divided by neural networks, and the recognition result has been presented. Through experiments, the validity of this method is verified.

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This paper discusses cooperative control of a dual-arm flexible manipulator to handle a rigid object in three dimensional space. The proposed control scheme integrates hybrid position/force control and vibration suppression control. In order to derive the control scheme, kinematics and dynamics of the manipulator when it forms a closed kinematic chain are discussed. Kinematics is described using workspace force, velocity and position vectors, and hybrid position/force control is extended from that on dual-arm rigid manipulators. Dynamics is derived from constraint conditions and the lumped-mass-spring model of the flexible manipulator and an object. The vibration suppression control is calculated from the deflections of the flexible links and the dynamics. Experiments on cooperative control are performed. The absolute positions/orientations and internal forces/moments are controlled using the manipulator, each arm of which have two flexible links, seven joints and a force/torque sensor. The results illustrate that the manipulator handles the rigid object damping links' vibration successfully in three dimensional space.

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In this paper we propose and develop a novel type of manipulator for the minute work. It can be not only independently controlled position and orientation of end-effector, but also controlled translational motion along to the axis of end-effector by only one actuator in any orientation. By this mechanism, it is able to achieve big workspace with high accuracy comparing with traditional proposed manipulator for the minute work. As a result of measurement of accuracy for our prototype manipulator, it achieves that the error of end-effector tip is within 50.0 [μm] and repeat positioning error is within 2.0 [μm] in changing orientation process.

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Piezoelectric ceramic is ferroelectric and is showing a significant hysteretic loop in its displacement response. This paper deals with the development of a linear compensation circuit for piezoelectric ceramic actuators by the self-sensing feedback control technique. In this paper, the concept of self-sensing feedback control technique and the circuit design were presented in detail, and the effect of the electric leakage in the piezoelectric actuator was investigated. A new idea for improvement of the effect of the electric leakage on the displacement drift in piezoactuator has been proposed simply by adding compensatory resistors in the circuit.

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In two-degree-of-freedom (2-DOF) servo positioning control of mechanical structures, the profile of reference trajectories is extremely important. In some cases, taking constraints on control problems into account, these trajectories are designed a priori by off-line calculations. Especially, such trajectories are effective in positioning control of flexible structures. Generally, the number of the profiles is limited such that the profiles comprise only some typical positioning distance cases. Therefore, an adjustment is required for realizing the positioning of an arbitrary distance. For this problem, this study proposes SMART adjustment method based on the idea of "Structural vibration Minimized AcceleRation Trajectory (Mizoshita, et al., 1991)." SMART is an optimal control solution for the motion of the double integrator dynamical model. SMART adjustment maintains the characteristics of off-line designed trajectories. By applying this method to 2-DOF H_∞ servo positioning control of a flexible structure, the effectiveness of it is verified by numerical calculations and experiments.

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To realize practical high power micromachines using fluid power with high power density, microvalves that can be mounted on such micromachines are required. In this study, a new microvalve using homogeneous ER fluids called the micro ER valve is proposed and fabricated. The homogeneous ER (Electro-rheological) fluids such as nematic liquid crystals whose apparent viscosity its controlled by the applied electric field strength are expected to be suitable for micromachines because they have no particles in them. The proposed micro ER valve features simple, compact and reliable structure without moving parts. Firstly, a 2-port valve with a pair of parallel plate electrodes is fabricated and the static and dynamic characteristics are experimentally invstigated. The viscosity change rate of 2.7 and the rise time of about 150 ms are obtained. Secondly, based on the obtained results, a 3-port micro ER valve with 4.5 mm in diameter and 5.2 mm in height is designed and fabricated and the basic characteristics are experimentally investigated. With electric field strength change of 3.0 kV/mm and supply pressure of 0.34 MPa, the controllable pressure of 0.13 MPa and the bandwidth of 0.6 Hz are realized. Also an application to position control of a bellows microactuator is performed.

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Rubber Tire-mounted Gantry (RTG) crances are running on the runways, which are sloped in the transverse direction and waved caused by the bearing of the frequent heavy tire loads. RTG structure has a wide projection area against wind during travelling. The runway unevenness and wind load becomes a disturbance to divert the straight travelling trajectory. And the angular offset of tire supporting plane to the RTG body also becomes a significant factor to affect the straight travelling performance. Herein this paper, the modeling of runway surface and wind load are introduced, and the relation of straight travelling trajectory of RTG with affections of runway unevenness, wind load, and angular offset of tire are studied by analysis with FEM.

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Author successed to make clear the solution of contact condition of skew gears. First, expressions of zone of contact and the opposite tooth surface of the skew gears similar to that of spur gears are derived. Second, the solution of contact condition of the skew gears is derived. This solution is very important in engineering and contribute to high speed calculation of the zone of contact and the opposite tooth surface. Finally, this sulution is applied to the worm gears one of which is a cylindrical screw worm having involute helicoid tooth surface. And examples of the zone of contact and the opposite tooth surface of the worm gears are shown.

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Clear results about the effect of shot peening on tooth surface strength of carburized gears have not been clarified. The author carried out experiments to study the effect of shot peening on tooth surface strength using test gears whose tooth surfaces were finished by grinding, where eight conditions of shot peening were processed. It was shown that the application of some peening conditions increased the tooth surface strength, while the application of other peening conditions decreased the tooth surface strength compared to that of not-peening. Furthermore, the variations in the tooth surface properties, i.e. residual stress, hardness, surface roughness and tooth profile after shot peening were observed and discussed in relation to the tooth surface strength. As a result of experiments, tooth surface strength is improved by the shot peening under the condition which integral value of residual compressive stress and mean value of hardness near the surface are higher. In addition, it was found that tooth surface strength becomes low when the gears are peened by the shot condition which keeps the tooth surface from running-in since shot peening affects the running-in of tooth surface.

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The feasibility of predicting engine bearing durability by means of hydrodynamic lubrication computations was investigated with the aim of improving bearing durability efficiently. Based on a comparison of EHL analyses with experimental analyses, a fatigue mechanism for sliding bearings was hypothesized and confirmed. The possibility of predicting fatigue by calculations was verified. The mechanism hypothesized here assumes that fatigue cracks originating on the surface occur simultaneously with wear destruction and that both are caused by direct contact. Therefore, the frequency of crack occurrence, which is one of parameters controlling the probability of fatigue failure, corresponds to the wear amount.

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We studied the contact characteristics of a positive-pressure step-slider flying over a thin-film disk under two conditions : rotating at a low velocity at normal pressure (LV condition) and rotating at normal velocity at low pressure (LP condition). Drag test revealed head wear on the leading pads of the step-slider tested under the LP condition, while there was no change on the pads of the slider tested under the LV condition. To find the cause of this head wear, we measured acoustic emission (AE) signal, friction force, and head flying characteristics under both conditions. It was thus, (1) that the friction force between the slider and the disk is larger under the LP condition than under the LV condition, and, (2) that the contact angle between the slider and the disk is larger under the LV condition than that under the LP condition. And we think that the low contact angle under the LP condition makes the leading pads contact the disk and, thus, cause the head wear. It is therefore concluded that the slider must fly in a steep attitude to achieve a low flying height.

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The numerical calculation method, previously developed for unsteady elastohydrodynamic lubrication with direct contact, was applied to an anlysis of asperity interaction in line contact. In order to elucidate how the micro-EHL effects are induced by asperity interaction, an analysis for rolling-sliding contact of two cylindrical surfaces with regular sinusoidal micro-geometry was conducted firstly. When a rough surface and a flat surface make rolling contact at a slip ratio, a micro-wedge action typically appears. On the other hand, if both two surfaces have sinusoidal roughness with a same wavelength, a volume of oil which is sandwiched between quickly moving asperity and slowly moving asperity is compressed and a micro-squeeze effect might be caused. It is shown that this micro-squeeze action could cause higher pressure than direct elastic contact even though oil-film exists. Also in the case of random surfaces produced by fractal FFT method, the peak of pressure could rise to very high value without direct contact. The generation of high pressure by micro-squeeze action might become to a cause of rolling fatigue failure.

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A series of experiments was carried out using a strip-ironing-type tribometer to investigate the lubricating effect of phosphorus EP additives in the metal forming processes. Experiments using aluminum alloy (A 6061-T 4) and stainless steel (SUS 304) showed that all kinds of phosphorus EP additives have the lubricating improvement effect and the best is the phosphite diester with the number of carbon less than 12. XPS spectra of ironed surfaces showed that the lubricating improvement effect of phosphite diester is due to the adsorption and that of phosphite triester is due to the chemical reaction.

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As higher precision machining is required, reducing thermal deformation of a machine tool becomes more important. Today, there are much study about the thermal deformation of machine tool ; a compulsory cooling of main spindle or ball screw, a feed back control of thermal expansion, an isolation of heat source and etc. However, it is necessary to used a cooling system, a controller of temperature and a sensor of temperature or heat flux for attaining these countermeasure. After all, many costs become necessary. Therefore, in this report, a self compulsory cooling for reducing thermal deformation was experimentally investigated. This method is the compulsory cooling using evaporation of water ; a cloth is bonded on a machine tool surface, water is supplied in the cloth by capillarity, then heat of the machine tool surface is removed by evaporation of water, and thermal deformation of the machine tool is finally reduced. The best suitable place on a machine tool for using this method is on the front surface of the head stock. Because this place has the strong inner heat source and is given strong wind by the spindle. When the spindle speed is higher and higher, the inner heat source is stronger, however the wind on the front surface of the head stock is also stronger and the surface is cooled down intensely with very large heat transfer coefficient. In the experiment, NC milling machine was used and thermal deformation of the machine with this countermeasure was investigated. It is concluded from the results that the proposed countermeasures are very cheap and effective in order to reduce thermal deformation.

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As higher precision machining is required, reducing thermal deformation of a machine tool becomes more important. And in the 21 st century, as it is also important to produce a product with care for protecting the earth, a producer must be careful on conservation of energy, Therefore, in previous report, a self compulsory cooling for reducing thermal deformation was proposed. This method is the compulsory cooling using water evaporation ; a cloth is bonded on a machine tool surface, water is supplied in the cloth by capillarity and wind is also supplied on the cloth by a fan which is bonded on a spindle of a machine tool, then heat of the machine tool surface is removed by water evaporation, and thermal deformation of the machine tool is finally reduced. The countermeasure were very cheap and effective in order to reduce thermal deformation. Furthermore, property on self control of the proposed countermeasure was evaluated. Property on self control is explained in the following ; it is important to be evaporated a large quantity of water for increasing cooling capacity of this method, on one hand, heavy load of a machine tool means that strength of heat source on spindle bearings becomes large and spindle speed with a fan becomes faster, and at that time, as large heat source and strong wind are supplied on the cloth with water, water evaporation increases very much, then cooling capacity also increases. In the experiment, a lathe with cloth on the front surface of head stock and with a fan on spindle was used for evaluating property of self control. It is concluded from the results that the proposed property of self control are effective toward the various working conditions.

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The workpiece rounding mechanism in centerless grinding is very much complicated compared to that in cylindrical grinding. Even a very small disturbance such as irregularity on the grinding wheel or the regulating wheel circumference, which makes the depth of cut at grinding point to change, may causes significant workpiece roundness deterioration in a centerless grinding operation. To minimize the effect of disturbance on the roundness, this paper investigates the mechanism of roundness deteriorating action analytically and determines the roundness error caused by disturbance quantitatively. It is found that the roundness deterioration can be avoided by controlling the ratio of grinding wheel and workpiece rotational speed.

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Since the solids in the particle dispersion type functional fluid have been found to reciprocate between electrodes under A.C electric field at low frequencies, it can be considered that these particles motion promotes the continued dispersion of the solids and applied field assists the ratainment of the same in the working area. Furthermore, it can be expected that the ground particles are removed from the working area continuosly due to their differences in dielectric constant and conductivity with diamond particles. In this paper, it is elucidated that the effect of electric field on the finishing properties. The optimum finishing conditions of the parameters such as, electric field strength, finishing pressure, applied frequency and processing time under the present experimental set-up were 3.5kV/mm, 24kPa, 0.8Hz and 300s, respectively.

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There has been promoted further high-speed cutting with the recent background of increasing demands for shorter development period in accordance with further complex and varied user needs for products. In order to realize high speed cuting for a lathe, high speed rotation of a spindle should be necessary. In this case, reducing aerodynamic noise caused by a rotating chuck would arise as one of important problems to be solved. This paper investigates a generation mechanism of aerodynamic noise caused by a rotating chuck and also proposes remedies for reduction of aerodynamic noise. Concretely, measuring sound around a lathe machine with a three-jaws scroll chuck makes clear relationships of sound puressure level with jaw shape and rotational speed, sound directivity and resonance tube phoenomenon. Relating sound measurement results with air flow around rotating jaws reported in our previous paper, aerodynamic noise can be classified into three types ; narrow band sound depending on rotation, wide-band sound depending on turbulent air flow around jaws and narrow band sound independent of rotation. Finally, aerodynamic noise reduction remedies corresponding to a characteristic of each sound classified above are proposed. Furthermore, some experiments with jaws improved according to the proposed remedies have shown their validity.

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In an assembling process of semiconductor devices, many kinds of ultrasonic wire bonders are generally used. In these machines, works are usually placed on a plate with small vacuum suction hole(s) to hold the works against ultrasonic bonding vibration. In terms of bonding condition, bonding points are required to be fixed firm enough to avoid miss bonding. This study was carried out to estimate the holding force of the vacuum suction methods. Some equations were derived to calculate the suction force and the friction moment of a work placed on a plate with a circular or rectangular vacuum hole under and assumed linear pressure distribution. Furthermore basing upon the Reynolds equation, some negative pressure distributions and the holding force of a work were calculated by the FEM. These results were compared, and an approximate correction function was found for the expressions derived. These results were proved to be valid from experiments.

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Tilt inspection is getting more and more importat in the replication process of optical disks such as CD-ROMs, DVDs, etc. to ensure high speed disk drives. In this work, a solution of the bending equation for a circular flat plate is applied to the conventional optical disk tilt inspection. The warped shape of an optical disk is expressed well in this solution. This makes the following new applications. (1)The disk shape is expressed in a simple expansion series. This enables to record the shape of every inspected disk by only using several coefficients. (2)Checking a series of coefficients of every disk enables to detect each disk's particular shape in a production lot. (3)Estimation of temperature distribution, axial acceleration and deflection is simple using only a few sensors in fixed radial positions. (4)Detection of imperfectly bonded spots of DVDs is possible, …, and so on.

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New international safety standards, ISO 12100 and International Electrotechnical Commission (IEC) 61508, are based on the concept of risk reduction to an acceptable level. The standards require increasing our capacities for risk management. Fault tree analysis (FTA) is a well-known and widely acceped method for risk analyses. Sequential failure logic (SFL) is essential for the application of FTA to risk analyses of, for example, space satellite systems and safety-related systems for product liability prevention. Algorithm for quantification of SFL has been proposed in the form of multiple integration. The present paper proposes analytical solutions of the multiple integration, given that basic events are characterized with common failure and repair rates. This makes it possible to estimate analysically the probability that an output from a minimal-cut priority-AND structure is in a failed state at time t and the statistically expected number of failures of the output per unit time at time t. Moreover, it is demonstrated how to analyze fault trees with SFL in order to estimate the statistically expected number of occurrences of the top event by use of the algorithms.

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The authors propose "refrigerative stereolithography". In its process, photopolymer resin for a layer is supplied in liquid state and is cooled to become gel state before photopolymerization by laser. After repeating the process for every layer, a fabricated object is obtained by heating, melting and removing only non-photopolymerized resin. Since the object is fabricated in gel resin, support structures are unnecessary and distortion by photopolymerization is reduced. A method of restraining surplus growth caused by over-curing at bottom surface of floating part is also proposed. The effectiveness and possibility of the method are confirmed by fabrication experiments using prototype machine.

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This paper deals with the implicit kansei evaluation of human satisfaction with emphasis on human cognitive information processing. Satisfaction was evaluated using satisfaction measurement system which estimates human satisfaction degree with neural network based on measuring electroencephalogram when subjects were shown three types of video program. It showed that the system was able to successfully evaluate satisfaction degree in real time according to video contents. Also synthesizing artifacts based on the implicit kansei evaluation of satisfaction by the satisfaction measurement system was discussed in terms of kansei information processing. The result demonstrated that the implicit kansei evaluation by the satisfaction measurement system can be applied to the design and development that takes human satisfaction into consideration.

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Design Problems for machine products are generally hirarchically expressed. With conventional produt optimization methods, it is difficult to concurrently optimize all design variables of portions within the hierarchical structure. This paper proposes a design optimization method using genetic algorithms containing hierarchical genotype representations, so that the hierarchical structures of machine system designs are exactly expressed through genotype coding, and optimization can be concurrently conducted for all of the hierarchical structures. Crossover and mutation operations for manipulating the hierarchical genotype representations are also developed. The proposed method is applied to a machine-tool structural design to demonstrate its effectiveness.

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