The purpose of this study is to develop a procedure for performing a dynamic analysis in the case that a flexible multibody system in three dimensions moves along a nonlinear trajectory at variable velocity. The kinetic energy of a multibody system moving along a nonlinear trajectory and the strain energy due to elastic deformation were derived using a finite element method. Then the equations of motion were derived by applying those energies to Lagrange's equation. The computational codes for an eigen-value analysis and time history responses were developed using the derived equations of motion. Eigen-value analysis on model system comprised of two flexible links and a rigid moving body and time history responses on model system moving along a nonlinear trajectory were calculated using the derived computational codes.

抄録全体を表示

Noise-induced chaotic bifurcations of random attractors arising in a Duffing oscillator and a parametrically exited pendulum with noisy harmonic excitations are investigated. We first follow the standard pullback procedure to obtain random invariant measures and then intuitively construct Poincare maps of them. The results on the stability and fractal analysis show that the noise-induced chaotic behavior which is not strange is generated from strange but non-chaotic invariant measures.

抄録全体を表示

This paper deals with nonlinear forced oscillations in a two-degree-of freedom system in which natural frequencies are comparatively close. Two kinds of approximated differential equations for amplitudes and phase angles of a harmonic oscillation and of a combination resonance are derived. The resonance curves and their stability analyses, and the local bifurcation analysis are made by using these equations. The numerical simulation analyses are performed to obtain time histories, their spectra, Poincare maps and Lyapunov exponents by using the original equations of motion. As a result, it is found that Hopf bifurcations can occur on the branch of the resonance curves for the harmonic oscillation, and that chaotic vibrations may occur after the appearance of a period doubling bifurcation, which are generated from the Hopf bifurcation point. The differences of the accuracy between these two kinds of approximated differential equations are also discussed.

抄録全体を表示

We have developed a simplified analysis method based on equivalent linearizations for calculating inelastic seismic responses of piping systems. The linearizations of inelastic load-deformation relationships make it possible to take advantage of a conventional method for elastic seismic design, such as modeling using elastic beam elements and the modal response spectrum analysis. To linearize the stiffness equivalently, we modified the flexibility factors of the elastic beam elements used in a conventional design. As a result, we can apply the conventional design code in the developed method. By doing so, we found that the calculated seismic responses of a simple piping system agree fairly well with those from nonlinear time-history analysis. This agreement verifies that the simplified analysis method can efficiently evaluate inelastic responses.

抄録全体を表示

The vibrational characteristics of a rotating ring with the inclined rotation axis are examined. The fundamental equations are derived depending on the Hamilton's principle, and the finite strain is used to take into consideration the product terms of steady-state displacements due to rotation and vibrational displacements, in addition to the centrifugal and Corioris forces. The both displacements are expressed by the Fourier series with respect to the circumferential coordinate, and by using orthogonality relations of trigonometric functions, the vibration equations are obtained. The circumferential wave number n are taken from 0 to 2 after confirming the convergence of solution up to n=2. The characteristic roots of those equations are calculated for the inclined angles 0°, 45° and 90°. For the case of the inclined angle 0° and 90°, all the vibrational modes are stable, whereas several modes which are rigid-body modes in the case of no-rotation become unstable for the case of inclined angle 45°.

抄録全体を表示

The location optimizing technique by response surface method with the basis vector of holographic neural network, is applied to effectively reduce the vehicle interior noise by roof rail and dynamic damper, which is influenced by the acoustic-structural coupling between compartment and vehicle body structure. The physical meaning of optimized result is studied about and interpreted as being equivalent with minimizing the spatially integrated volume displacement or volume acceleration of boundary panel over in-phase region of acousic mode. This structural management could be applied to lowering actual vehicle interior noise.

抄録全体を表示

When a high speed train dashes into a tunnel, a compression wave is generated. The compression wave propagates through the tunnel at the sound speed. When it arrives at the exit of the tunnel, a MPW (micro-pressure wave) is emitted outward from the tunnel exit. The MPW has a positive impulsive pressure and the residents around the portal of the tunnel are put to annoyance. Several ways of passive control of micro-pressure wave have been investigated. The typical counter-measures are the installation of a hood at the entrance of a tunnel and side branches in a tunnel. Although they are effective, a quite long hood is required if the train speed is more than 350 km/h and the side branches cause low frequency noise around the portal if the train speed is more than 400 km/h at the Japanese MAGLEV test line. Therefore, an active control method is desired to apply with passive methods. In this paper, two dimensional MOC (Method of Characteristics) is applied and the active control of incident wave front of compression wave in a tunnel is numerically simulated to reduce the level of MPW.

抄録全体を表示

It is known that vertical inertia force of a moving mass has a great effect on track vibration. A flexible beam which is considered as track may has large rotation and deformation during the moving load passage. In order to analyze the motion of the flexible beam with large deformation and rotation, the absolute nodal coordinate formulation was proposed. In this paper, this method is applied to examine the motion and vibration of the moving mass spring system on the flexible beam. First, in order to obtain the fundamental knowledge for the dynamic behavior of this system, eigen values and free vibration are investigated, comparing with the results applied the other method. Moreover, the experimental plant for this system is built. The features of the dynamic behavior of this system concerning with the acceleration, the phase difference between the beam and the mass and so on, are pointed out both numerically and experimentally. It is also shown that the presenting modeling and formulation for this system are valid, confirming that the calculation results agree with the experimental ones qualitatively.

抄録全体を表示

The optimal placement method or procedure of a storey-installation type damper for vibration control of structures and building has not yet been established though the devices themselves are developed actively. Therefore, in almost cases, these dampers have been installed uniformly in each storey of the building. However, it can be thought that this method is not so much efficient in reducing vibrations in the structure because the significant difference in the absorbed energy between lower and higher storeys is produced. This study attempts to apply the genetic algorithm (GA) to determine the proper distribution for the storey-installation type damper rapidly and easily. In this paper, the procedure switching GA (PSGA) that improved the simple GA was applied to DeJong's standard function and the optimum placement problem of damper. Moreover, the PSGA's placement results of damper were confirmed that these have an effect against the traditional arrangement method experimentally by the shaking test.

抄録全体を表示

This paper presents the results of an experimental and analytical study of the performance of particle impact dampers using a cylindrical container. This damping is a form of impact damping in which particles collides with the cylindrical surface of the container. The dynamics of the damper is solved by Discrete Element Method (DEM). The validity of the numerical method is examined by comparison with experimental results. The effect of some of the major system parameters such as the mass ratio, container dimensions and particle radius on the structural damping is studied.

抄録全体を表示

This paper proposes a new modeling method of elastic body to represent the rigid motion and elastic deformation. This model can be used to control flexible multibody systems like flexible manipulators, vehicles, and space structures etc. The model consists of mass particles, springs, and rigid bodies and the behavior of mass particles represents rigid motion and deformation of elastic bodies. The mass and stiffness matrices are calculated using the modal mass, natural frequencies, and mode shapes. The efficacy of the model is verified by considering an example of an elastic car body supported by a rectangular plate. This modeling procedure is also extended to represent the dynamics of flexible multibody systems.

抄録全体を表示

A new vibration isolation system using zero-power magnetic suspension is proposed. Since a zero-power magnetic suspension system behaves as if it has a negative stiffness, infinite stiffness against disturbances on the isolation table can be achieved by combining it with a normal spring. It enables the system to have good characteristics in both the performances of isolation from ground and suppression of direct vibration. An analytical study shows that the proposed system has infinite stiffness against disturbances on the isolation table. Such characteristics are experimentally confirmed with a developed instrument.

抄録全体を表示

Precise fluid force measurement by water tunnel test was conducted to investigate the mechanism of flow-induced vibration of a circular cylinder in in-line direction. Added fluid forces acting on a circular cylinder were measured by forced oscillation tests. As a result, it was confirmed that negative damping force acts on a cylinder in a certain range of reduced flow velocity corresponding to the first in-line oscillation region. The measured added damping force was then reduced to exciting parameter, which denotes nondimensional exciting fluid force. The characteristics of exciting parameter and the effect of mass ratio to the stability criteria were discussed in detail.

抄録全体を表示

Electro Hydro Dynamics (EHD) fluid is a kind of intelligent fluid. The fluid has the property that a fluid jet flow is generated between two electrodes when a high voltage is applied. DBDN (Di n-butyl dodecandioate) is a kind of EHD fluid and a dielectric organic liquid. The main purpose of this study is to develop a lightweight and compact fluid actuator which makes use of such properties of EHD fluid. We think that it is useful to apply EHD actuators to a micro actuating System as a lightweight actuator. In order to develop such an actuator, we first investigated the characteristics, the relation between the generated pressure and applied voltage to DBDN fluid. In this study, we tested two kinds of pumping module ; a direct type and a suction type. The direct type module consists of two doughnut shaped electrodes. The suction type module consists of a flat plate electrode and a cylindrical electrode. We investigated the relation between applied voltage and generated differential pressure using these modules. Further, we investigated the influence of geometric parameters on the characteristics of the module.

抄録全体を表示

The previous report made clear that the gauge widening was still effective for the curving performance of rail vehicles with bolsterless trucks or forced steering ones. Here, the examination was carried out using wheels with conical tread. However, wheels with profiled tread have been employed widely in recent years, because they can secure not only the running stability but also the curving performance. In this paper, the curving performance under the presence of gauge widening is investigated in detail for the trucks with profiled-tread wheels. The wheel lateral forces obtained by the numerical simulation on the curve negotiation are compared among vehicle types classified with truck mechanisms and wheel tread shapes. As a result, it is shown that the availability of gauge widening to the trucks with profiled wheels is little because the change of wheel shape, from conical tread to profiled one, gives much effect on the performance. Then, the modification of tread shape is examined to get further availability of gauge widening. It is shown that the effectiveness of wheel shape modification can be obtained also in a vehicle assumed to negotiate very tight curves at lowspeeds.

抄録全体を表示

Experimental and numerical investigations have been carried out on dynamics of magnetic bead chain in magnetic field. By the observation of vibration of chains formed on a solenoid coil, resonant frequency of the chains and equivalent stiffness were estimated. It was deduced that the resonant frequency was irrelevant to magnetic field, while the equivalent stiffness depended on magnetic field. From the numerical study using Distinct Element Method, it was also shown that the equivalent stiffness increased with the increase in magnetic field and decreased with the increase in chain length. Experimentally observed dependency of stiffness on magnetic field was explained as the combined effect of both magnetic field and chain length.

抄録全体を表示

In the present paper, we consider simultaneous stabilizing problem for multivariable systems. At first we propose a simple state space design procedure of simultaneous stabilizing controller using filtered inverse systems for the system having no zero in the closed right half plane. Next the procedure is expanded for the system having some zeroes in the closed right half plane. Freedom of the simultaneous stabilizing controllers are clarified. The proposed methods are built based on state space description, therefore the proposed methods have many advantages such as easy computation and so no.

抄録全体を表示

In this paper, approximate techniques for dynamically simulating the swimming motion and for planning its optimal motion are proposed. In the simulation technique, the formulation of the dynamic equations subject to the propulsion force under water is presented and the equations are used to find the swimming motion subsequently. As a simple numerical example for the motion of the whole human body, the backstroke was simulated. The results of the simulation show that the technique can improve the reality of motion although this is still the first step for the simulation of swimming of the human body.

抄録全体を表示

This paper describes a temperature analysis of FDB spindle motor carried out to investigate temperature of lubricating oil in FDB. Increases in the oil temperature exert significant influences on the performance and life of an FDB. Therefore it is important to study the oil temperature when the spindle motor runs. Then, we analyzed a temperature of lubricating oil in FDB spindle motor by experimental approach and numerical analysis approach. In experimental approach, the temperature of thrust bearing was measured using infrared micro thermograph. Then temperature of lubricating oil in the rotating spindle motor was measured. On the other hand, in numerical analysis approach, temperature of lubricating oil was calculated through the thermo-fluid analysis of lubricating oil and the heat conduction analysis of FDB spindle motor. The calculated results showed good agreements with the experimental results. It became cleare the temperature of lubricating oil increased exponentially with rotational speed of spindle motor.

抄録全体を表示

In this paper, we propose a flexible structural contact sensor that enables a robot to detect tiny contact force with environment. In order to realize safe and skillful grasping by a robot hand as human does, the flexible structure and sensibility to detect contact force is very important. This sensor consists only of thin elastic metalic plates and strain gages. Contact force can be calculated by measuring deformation of elastic plates with strain gages. And this sensor can also estimate the location of a contact point. The relationship between contact point and strains is obtained theoretically. Compared with theoretical results and experimental results using a prototype sensor, we could obtain an advisable agreement between them. So we confirmed that this sensor could measure tiny contact force and estimate the contact point.

抄録全体を表示

This paper deals with a vibration control of a thin cylindrical shell, which is one of the fundamental elements in machines and structures. Piezoelectric films are used as sensors and actuators in order to obtain high performance vibration control in low order modes. The optimal length for a piezoelectric film is conducted by finite element analyses, to gain efficiency in a vibration control system developed by using the direct output feedback control scheme. The control effect in vibration experiments are estimated by investigating the sensor output, along with the visual confirmation by using a laser-holographic interferometer.

抄録全体を表示

The utilization of a hydraulic system on the friction brake of railway rolling stock permits a small size and fast response of control system. In spite of these advantages, the inner leakage of the conventional control valve for friction brake results in a reliability problem. In this study, a poppet type pressure control valve is developed. The poppet type valve is proposed for preventing inner leakage, and the displacement-pressure characteristic is designed to eliminate the need for a pressure transducer. The compensation methods for the operating force and the change caused by wear of the poppet valve are determined. The experimental results confirm the design constraints, and show that the proposed valve is valid for the specific system.

抄録全体を表示

In this paper, we propose a method to apply a Two-Degree-of-Freedom control with adaptive filter as such attempt of controlling a Multi-Axis Electro-Dynamic shaking system has no requirement for iteration control and has real-time performance. An adaptive filter is inserted in series to a feed-forward block and is structured to compensate difference between a nominal model and an actual plant. We first introduce an ideal mathematical model and uncertainty weighting function for the system, and a feedback controller is designed using μ-synthesis. And we constitute Two-Degree-of-Freedom controller for a purpose to improve transient response. Then, an adaptive filter is added when control performance still can't be satisfied. Lastly, we inspect the performance of the controller by experiment using an actual equipment loaded with a resonant specimen. An experiment without adaptive filter is done to show stability of the system. And the proposed controller is confirmed to have achieved a superior performance by using the adaptive filter.

抄録全体を表示

This paper proposes a new control method of mobile robots based on a model of bacterial chemotaxis including not only intracellular information processing but also motor control on the basis of the molecular evidence. E. coli is chosen as a target bacterium, which has a simple molecular structure and is amenable to biochemical and genetic analysis. First, a computer model of the chmotaxis is developed to simulate its emergence. Parameters included in the model are regulated using the genetic algorithm in such a way that a fitness representing the chemotactic ability is maximized. Then, using a mobile robot incorporated this chemotactic model, experiments of trajectory generation are preformed, and it is confirmed that the mobile robot can be controlled based on the bacterial model.

抄録全体を表示

In this paper, we propose a decentralized control algorithm of multiple mobile robots transporting an object in coordination without using force/torque sensors. In this algorithm, each robot is controlled as if it has a specified impedance dynamics, using the identified parameters of each robot, without using a force/torque sensor. These robots transport a object in coordination using a leader follower type control algorithm. We also consider the effect of parameter identification errors and propose a method to reduce the effect of them. The proposed control algorithm is experimentally applied to two mobile robots, and the experimental results illustrate the validity of the proposed control algorithm.

抄録全体を表示

In this paper, a remote operation system of a moving robot is constructed on Web browsers. This system is simplified by TCP/IP network techniques. CGI, Socket of Java API, etc. transmit data of a CCD camera and sonar sensors on a moving robot to a client PC. Real time performance is improved by such efficient transmissions. This user interface on Web browser doesn't bind the location of the operator, provide the operator simple operation of a moving robot. This interface is developed to express information visually to an operator using the drawing ability of Java applets. Operation is executed in virtual space based on map information of a distant place. In this system, the information of an unknown object and relative distance and direction between robots in remote site is displayed to local Web browser.

抄録全体を表示

In this study, an electromagnetic actuator using rubber film has been developed. The structure of the actuator and the shape of the rubber film are described, and the stroke, the force characteristic and the responsibility of the actuator are experimentally investigated. The experimental results show that although hysteresis existed in the displacement generated from the actuator, this can be compensated by constructing the servomechanism and the positioning performance with a micro meter order can be, realized. Furthermore, although the actuator is inferior by the response or generating power compared with the specifications of the piezoelectric actuator, it has been confirmed that the large operational stroke is acquired even if it drives with low voltage.

抄録全体を表示

Pneumatic servo systems contain non-linear elements caused by compressibility of the air, various frictions and so on. Therefore, it is difficult for ordinary linear control methods to accomplish satisfactory control performance in a pneumatic servo system. In this note, we propose a design scheme which combines a model reference adaptive control (MRAC) with a neural network (NN) for the pneumatic servo system with additive external forces. In this design scheme, NN linearizes a non-linear plant of the electro-pneumatic servo system. Then, MRAC is constructed to the linearized plant. Furthermore, difference process of the signals in the identification mechanism is introduced to eliminate the influence of the constant disturbances caused by the additive external forces. The effectiveness of the proposed design scheme is confirmed by experiments using the existent electro-pneumatic servo system.

抄録全体を表示

This paper presents a self-positioning system for a mobile robot. The proposed positioning system consists of an ODV (Omni Directional Vision) featuring two mirrors with a contrived curvature for obtaining a panoramic image with low aberration. An obtained panoramic image which occupies most of the view field can be processed to recognize the topological position of three landmarks which are placed in the environment. A primary marker and two supplementary markers are used to indicate the correspondence between the real environment and the digital map. The relative self-position can be estimated from three directional angles toward landmarks. The absolute self-position can also be computed by comparing the landmark position on a map. Comparison between the theoretical positioning accuracy based on the Cramer-Rao lower band and the experimental result in the field proves that both the ODV and proposed self-positioning algorithm including sub-pixel level image processing are valid and effective. An outdoor experiment which used a mobile robot shows that the proposed positioning system has high positioning accuracy even in the cluttered outdoor environment.

抄録全体を表示

A spot-type multi-disk brake of small size and light weight has been proposed for improving performances of robots by changing their degrees of freedom. This brake is driven by a piezoelectric (PZT) actuator. In order to design the brake which utilizes the large force of PZT actuator, it is necessary to precisely estimate the brake application force. The variation of distance between the jaws of the caliper due to the deformations of the caliper, irregularities of contacting surfaces and warps of disks, pads and PZT actuator has been analyzed, and it has been clarified that it is important to pre-load the contacting surfaces of jaws, PZT actuator, disks and pads to realize a large brake application force. Two methods for pre-loading the contact surfaces have been proposed. One is to pre-load both end surfaces of the PZT actuator by springs, and the other is to pre-load disks and pads by a wedge mechanism previous to the action of the PZT actuator. This wedge mechanism is driven by solenoids. The amounts of these pre-loads have been concretely determined. A prototype brake developed based on the results mentioned above weighs only 1/4 of the electromagnetic brake on the market.

抄録全体を表示

About the multi-disk brake driven by a piezoelectric actuator and solenoids proposed in the first report, the motion and the acting force of each component of it have been analyzed with consideration of the contact phenomena of stick, slip and separation. The present paper is focused on the wedge mechanism that transforms the kinetic energy of plunger of the solenoid mainly to the elastic energy of the brake pads and disks. Then the relationship between the brake application force and the geometric and dynamic parameters of the wedge mechanism has been investigated both theoretically and experimentally.

抄録全体を表示

The effect of MoDTC with and without ZnDTP on reduction in friction and wear was determined under the partial EHL conditions with a two roller machine, where the experiments were conducted using polyalphaolefin (PAO), polyol ester (POE) and their blended oils as the base fluids. When using PAO as a base fluid, a significant friction and wear reducing effect appeared at a low Mo concentration. On the contrary, the coefficient of friction and the wear amount in POE containing MoDTC with and without ZnDTP increased with increasing Mo concentration. In the blended oils containing MoDTC with a constant Mo concentration the additive effect decreased as the ratio of POE was increased. This indicates that the co-adsorption between POE and MoDTC onto the rubbing surface prevented the formation of an effective boundary lubrication film. The experimental results also showed a friction and wear-reducing effect depends on the ratio of concentration of ZnDTP to that of POE.

抄録全体を表示

Quasi-static pressure-dependence equations of density and elastic modulus for lubricant oils were derived up to 5 GPa based on the experimental data from both quasi-static pressure vessel apparatus up to 1.2 GPa and dynamic sound velocity data by Brillouin light scattering measurements up to 5 GPa. Dynamic data were analyzed by applying a viscoelastic model for volume change and quasi-static data were obtained. Examined lubricant oils were 3 naphthenic oils such as traction oils, 5P4E (five-ring polyphenyl ether) and DOS (dioctylsebacate). Lubricant oils whose solidfied pressure is lower than 1 GPa were resulted to show almost the same pressure-dependence characteristics of density and bulk modulus over solidified pressure. Temperature-dependence of these equations found out to be small up to 155°C.

抄録全体を表示

Laser lap welding of PMMA was numerically simulated on the basis of heat transfer equation. When the laser energy was converted into heat only at the transparent/opaque thermoplastic interface, the energy flux necessary for a fixed temperature increase was proportional to the -0.5 power of the irradiation time of laser. This relation was exactly the same as that predicted by dimensional analysis, while it was different from the experimental results with a power index of -0.7. When the laser energy was absorbed and converted into heat in the opaque thermoplastic plate and radiated from the interface, the energy flux became close to the experimental data and proportional to the -0.7 power of the irradiation time.

抄録全体を表示

For kinematic calibration of robots, we proposed using a low order Fourier series obtained by transforming the data for circular measurement paths. The paths were measured using a Double-Ball-Bar (DBB) system. Two non-dimensional indices were proposed for evaluating the orthogonalities of the measurement paths and calibration parameters. An index was also proposed to evaluate the accuracy of the calibration with regard to measurement error. An algorithm for determining adequate measurement paths and an optimal set of paths using these indices was also proposed. The effectiveness of the proposed method, indices, and algorithm was investigated through simulations of kinematic calibration with an in-parallel actuated mechanism.

抄録全体を表示

This study discusses the finishing mechanism of a magnetic field assisted mechanochemical polishing process using Cr₂O₃ abrasive mixed with iron particles, which was proposed for internal finishing of Si₃N₄ fine ceramic tubes. According to the finishing experiments, the iron particles rotate with the magnetic field and rub against the inner surface of the tube immediately after the finishing process begins. Initially, some of the iron particles adhere to the surface with the rolling nonmagnetic Cr₂O₃ abrasive. The Cr₂O₃ abrasive becomes embedded in the iron particles, which are softened by the friction heat of the finishing process. Relative motion is generated between the Cr₂O₃ abrasive and the finished surface, mechanically removing both the initial deposits of iron particles. This achieves smooth internal finishing of the tube without contaminating constituent components of the tube material.

抄録全体を表示

This paper proposes a new micromachining process featuring ultrasonic cavitation in distilled water as part of the processing principle. The cavitation, varied with the tool geometry and the clearance between the target workpiece surface and the tool connected to the horn, causes erosive action on the workpiece surface, achieving the desired micromachining. An experimental setup was developed to investigate the principle. The machining experiments demonstrated that the propagation of pressure waves generated by the ultrasonic cavitation varies with the tool geometry and clearance. This changes the erosive action, i. e., the machining characteristics, against the workpiece. At small clearances, the machined geometry closely followed the tool's geometry while, at clearances larger than a certain value, the cavitation generated a dent in the area corresponding to the tool center. This study found that the feasibility of applying the process to the form-copying process, such as die-sinking, requires the former conditions.

抄録全体を表示

In order to facilitate the advancement of micro machine technology and to encourage its use across a wider range of industrial fields, measuring technology appears to be essential. For the development of micromachines and microfabrication technologies, it is necessary to devise a technique to measure both profile and dimension of micro-components. Some researches on measuring methods for micro-boreholes in the micrometer range have been reported. However, general-purpose CMM for both form and dimensional metrology on micro-system components has not been realized yet. To this end, one of the authors tried to develop a small three dimensional form measuring apparatus which has non-contact probe detecting proximity to measuring object through tunneling effect, and the results has already been reported. In this paper, measurement not only form but also dimension of micro-components are tried. Modified device and the calibration technique for micro-probes are explained in detail, and then several measuring results are shown.

抄録全体を表示

Grinding performance of fine abrasive grinding wheel to silicon wafer were investigated. In this study, thin-plate silica powder, tens μm in length and 1 μm in width, were applied as a abrasive for grinding wheel. The grinding wheel were fabricated using a electrophoretic deposition phenomenon, it was called "EPD pellet", and thin-plate silica abrasives could be arranged in a one-way direction in the EPD pellet. Grinding efficiency of thin-plate silica EPD pellet was twice as high as a conventional EPD pellet which was consist of spherical silica abrasive. Warp of thin-wafer, 150 μm in thickness ground by diamond wheel, were decreased with the progress of EPD grinding. This result shows that a residual strain by a diamond wheel could be removed by EPD grinding.

抄録全体を表示

For one-piece brake discs, tiny cracks exceptionally occur from holes at the flange due to cyclic thermal stress under an extraordinarily severe condition when discs have a certain number of holes and layout. In order to reveal the mechanism for crack initiation from holes in the flange of one-piece brake discs, braking tests under overloading conditions were conducted using five types of discs whose number of holes and their layout were different. Unsteady heat transfer analyses were also carried out to estimate the temperature distribution and its variation with respect to time by the finite element method. The experimental and calculated results showed that the maximum temperature and the difference between maximum and minimum temperatures increased when the number of holes decreased due to a decrease in heat mass of the flange. Consequently, the stress occurring around the holes slightly increases. However, the hole location has more significant effect on the crack initiation than the number of holes. If holes are located closer to the external edge of the disc, the thermally cyclic stress amplitude around the holes becomes higher as well as its magnitude.

抄録全体を表示

A new machine tool has been developed to produce parts with non-circular cross sections, and especially parts with large radius changes in the workpiece cross sectional profile. Using the machine tool, a workpiece fixed with a spindle chuck is set between two milling cutters so that the workpiece can be machined using both milling cutters simultaneously from opposite sides of the workpiece. The machining time can be cut by half using two cutting tools on one workpiece. It is necessary to control each cutting tool position for cutting directions separately in order to apply the machining method to non-circular workpieces. The machine tool is powered by two linear motor systems. A feature of the linear motor system is that the two linear motors are mounted on a linear rail and can be controlled separately by a machine tool controller. Machining tests are conducted using the developed machine tool system to demonstrate the advantages of the method for non-circular workpieces.

抄録全体を表示

The study deals with the chamfering quality control by an industrial robot. In the study, the "chamfering quality" means the property of the chamfered edge shape for various functions. Especially, a chamfering for safety is discussed in the article. In order to perform chamfering by a robot, a chamfering width control system is developed to compensate positioning errors and to control the width of chamfering part. A tool path is generated on the basis of CAD data followed by conversion to a robot control command. The depth of cut at, each point calculated based on the CAD data is given to chamfering width control unit attached to the robot to realize designated shape of chamfering. From the experimental result, the system is found to have an ability of chamfering for safety.

抄録全体を表示

This study deals with dynamic job shop scheduling problems using a multi-layer feed-forward neural network. In the first report, we showed that the trained neural network outperformed the best dispatching rules under various scheduling conditions. In this second report, we evaluate the significance of input information of the neural network by using mutual information, and then try to eliminate insignificant input units. Numerical experiments show that the information used in the best dispatching rules has high relevance to the output of the trained neural network. However, it is shown that the significance of the input information varies acoording to the scheduling conditions and other information such as machine load level that is not used in the dispatching rules has also high significance. It is also shown that the pruning algorithm of insignificant input units is effective.

抄録全体を表示

In this paper we present a Vehicle Routing Problem (VRP) considering joint distribution, and solving through hybrid heuristic that combines Simulated Annealing with Tabu Search to approach a near optimal solution. As joint distribution is practiced among firms of different categories to avoid information leakage, trucks each firm uses usually differ in size. But none of the papers on joint distribution in the past dealt with different size trucks. So here we propose a joint distribution using existing trucks of multi-fleet -size. We use the total cost of fixed and variable truck cost as the objective function.

抄録全体を表示

This paper discusses a material handling system which we call permutation circulation-type vehicle routing system (denoted PCVRS). The PCVRS consists of a guide path of single loop-type (called the loop), multiple vehicles and multiple stages. Each vehicle unidirectionally and repeatedly circulates on the loop without passing, and processes a job on stages located along the loop. Increasing the number of vehicle for getting higher throughput (i.e., the number of jobs processed per hour), interferences between vehicles occur, which increase travel time of vehicles, resulting in deterioration of system performances. This paper discusses two types of interferences, which may occur when jobs have different processing times, and considers the modification of operation policy consisting of routing and scheduling to decrease the interferences. This paper proposes an operation policy called "order-SPT", and discusses its performances such as mean travel time, throughput and queue length by means of simulation experience, validates superiority of the order-SPT operation policy.

抄録全体を表示