A shaking table experiment for the piping system with a friction support has been conducted to investigate the reduction characteristics of vibration responses of the piping system due to frictional effect against earthquake type excitations. The piping system has been so designed that the contact point of the piping moves in-plane 2 dimensional motion on the teflon bearing plate supported by the shaking table. The experimental results were well explained by a proposed deterministic approximate modal analysis theory which were already reported in the separate paper. Here, we try to evaluate the seismic responses by means of the non-deterministic method, i. e. the statistical equivalent linearization method, for friction forces at the friction support of the piping. It has been found that the calculated responses by the linearization method show in good agreement with the experimental ones. The equivalent modal damping is also estimated in this process. From the above results, seismic performance of the frictional effect is discussed.

抄録全体を表示

This paper proposes vibration suppression design for adaptive truss structures which deform to achieve given tasks. The cross-sectional areas of members in the structure are optimized under a constraint of the total mass so that the vibration transmission from disturbance sources to specified points is suppressed. To measure the vibration transmission property, the H_∞ norm of the transfer function is adopted. The dynamics of the adaptive structure changes following the deformation, which is described by a nominal model and a perturbation term. For optimization, the simulated annealing is employed.

抄録全体を表示

Feedback active noise control (FB-ANC) systems need no reference signal sensors and their implementation cost is therefore attractive due to the relatively simple configuration. This paper reports the design of an FB-ANC system for free sound fields by H_∞ control theory based on a lower-order infinite impulse response (IIR) model of the acoustic plant. The acoustic plant, which is an acoustic transmission system from a loudspeaker (i. e. the actuator) to an error microphone (i. e. the sensor), is first devised by using the physical modeling method in conjunction with a system identification result. The feedback controller is next designed to attenuate the noise level in the vicinity of the error sensor by reducing the sensitivity function over the frequency range of interest. H_∞ control theory is applied to achieve the control objective, because it can formulate the control specifications in terms of the frequency weighting functions in the frequency domain. Finally, the effectiveness of the proposed design procedure is demonstrated by experimental tests.

抄録全体を表示

Acoustic analysis of a simple expansion chamber using a three dimensional finite element model is time consuming because of enormous computation. Numerical collocation method utilizing boundary conditions of acoustic pressure and particle velocity, has been developed for an efficient alternative. However, this conventional method cannot be generally applied to a simple expansion chamber with arbitrary inlet/outlet. This paper introduces a general collocation method without any limitation on inlet/outlet, to calculate four-pole parameters of the simple expansion chamber. Acoustic characteristics of simple expansion chamber with rectangular and circular cross section is analyzed using the suggested method and compared with that of conventional collocation method. Results of finite element method reveals that the suggested method has better accuracy compared with the conventional method

抄録全体を表示

This paper is based on the two-degree-of-freedom nonlinear model for brake squeal. The phase space analysis is performed to understand complicated dynamics of the nonlinear model. Attractors in the phase space are examined for various conditions of the parameters of the model especially by emphasizing on the damping parameters. In certain conditions, the attractor becomes a limit cycle showing the stick-slip phenomena. In this paper, not only the existence of limit cycle but also the size of limit cycles is examined to demonstrate the nonlinear dynamics that leads the squeal state. The results not only describe the existence of limit cycle, but also show an additional important fact that it may make the system worse when too much damping is added in only the pad or the disc.

抄録全体を表示

The authors present a new step-by-step integration scheme by utilizing the cardinal B-splines. The new method organizes conventional implicit methods such as Newmark-β method and Wilson-θ method and so on, and provides a simple computation procedure so that the step-by-step integration can be carried out efficiently. In addition, when we analyze a nonlinear system with discontinuity the computational accuracy can be improved by the approximate detection of the discontinuous points by making good use of the two-scale relation. In this paper, we formulate an algorithm of a time historical response analysis of a straight-line beam structure as an elementary example of multi-degree of freedom system besides a simple single degree of freedom system. The cardinal B-splines used here are only the ones of orders 3 and 4 but the other cardinal B-splines are also available for the step-by-step integration in the same way.

抄録全体を表示

A flexible beam model with bonded piezo-patches is taken as the study object. In order to suppress the disturbance vibration of the beam, the imposed voltage to the bonded piezoelectric elements is controlled. After the theoretical analysis for piezoelectric patches and beam structure, a bilinear form of the state space equation is derived. In this electromechanically coupled model, the imposed voltage control is related to the beam deformation state. Therefore, it is possible to realize the proposed semi-active control through a low cost approach. The concept of semi-active control comes from the fact of that only the gain of the imposed voltage is adjusted and the voltage direction is reverse to the deformation sensing. As a result, the control voltage is controlled only in two-phase planes. Here, nonlinear state feedback control theory is applied to design a controller and the proposed control approach is testified by numerical simulation.

抄録全体を表示

A learning method for acquiring the appropriate fuzzy rules using error back propagation to improve the control performance of the pneumatic servo system is presented in this paper. In the proposed method, two criteria are defined and are adjusted so as to minimize them using error back propagation. These criteria are defined on the fuzzy rules, that is, shapes of membership functions of antecedent clause and real values of consequent clause in the fuzzy controller. Two differentiating coefficients of the plant, used in error back propagation with respect to those criteria, are estimated by the newly established neural network. Moreover, sigmoid function is introduced for the connection of the neural network to compensate for the effect of non-linearity of the system. The method was applied to an existent vertical type pneumatic servo system and proved its effectiveness for practical use.

抄録全体を表示

This paper considers robust control of an active vibration isolation system which is composed of a rigid platform and supporting air springs. The objective of control is to realize low compliance in the low frequency range for accurate position and attitude control, and to preserve high compliance in the high frequency range for good vibration isolation properties. The system is modeled by identification theory, and four subsystems describing strongly coupled dynamics are extracted from the six degrees of freedom of the motion. The weak coupling between subsystems as well as modeling errors in subsystems are treated as uncertainty of the system. A decentralized controller compatible with the subsystems is proposed, which achieves robust performance.

抄録全体を表示

In this paper, a robust controller based on the variable structure control technique for the output tracking of a class of discrete-time uncertain nonlinear systems is developed. An upper bound on the uncertainties is derived to ensure the existence of a quasi-sliding mode in these uncertain systems. Analysis results indicate that the output of the closed-loop system tracks a desired output trajectory and, simultaneously, all signals inside the loop are bounded. Furthermore, the tracking error depends on the proposed controller's parameters. Two examples are given to demonstrate the effectiveness of the proposed control scheme.

抄録全体を表示

The geometric errors and structural thermal deformation are factors that influence the machining accuracy of Computer Numerical Control (CNC) machining center. Therefore, researchers pay attention to thermal error compensation technologies on CNC machine tools. Some real-time error compensation techniques have been successfully demonstrated in both laboratories and industrial sites. The compensation results still need to be enhanced. In this research, the neural-fuzzy theory has been conducted to derive a thermal prediction model. An IC-type thermometer has been used to detect the heat sources temperature variation. The thermal drifts are online measured by a touch-triggered probe with a standard bar. A thermal prediction model is then derived by neural-fuzzy theory based on the temperature variation and the thermal drifts. A Graphic User Interface (GUI) system is also built to conduct the user friendly operation interface with Insprise C++ Builder. The experimental results show that the thermal prediction model developed by neural-fuzzy theory methodology can improve machining accuracy from 80µm to 3µm. Comparison with the multi-variable linear regression analysis the compensation accuracy is increased from ±10µm to ±3µm.

抄録全体を表示

A bang-bang control law is used to provide guidance for a car's steering system. The control law uses a proportional plus derivative error function which operates on the output of an observer and is suitable for embedded control of a car. The observer fuses sensor data from sensors whose reliability is inversely related to their availability. An erroneous plant model is present and is subject to nonholonomic and kinematic constraints. The sensors measure the plant with 25% systematic error at 100hertz. Internal sensors are sampled at 20hertz and have 10% error. External sensors are sampled at 5hertz and have no error. The observer performs dead reckoning during the intervals of time when the external sensors are not available. There are two internal sensors, an odometer and a steering-wheel angle meter. The odometer is used to compute a linear approximation to the speed of the plant. The steering-wheel angle meter measures the steering-wheel deflection relative to the longitudinal centerline of the plant. There are three external sensors which are used to measure the pose of the plant.

抄録全体を表示

This paper introduces the development of a motion cueing algorithm which produces motion cues from vehicle motion signals. The simulator, a parallel manipulator, has the limitation on the workspace. In order to overcome this problem, the motion cueing algorithm is needed. Here, we suggest a new optimal motion cueing algorithm where the human body model (ISO 2631-1) as well as the human perception model are incorporated. And we show the performance of this algorithm using the computer simulation. In simulation, we produce motion cues from vehicle motion signals through the proposed algorithm and show sensation errors which the human feel between vehicle signals and the simulator motions subjected to motion cues.

抄録全体を表示

This paper describes the development of the modified resistance network method (RNM) for analyzing the dynamic behaviors of X-shaped grooves aerostatic bearing with a passive disk-spring compensator. The Newmark integration method and the modified RNM, which takes into account on the equilibrium of the mass flow rate and the squeeze film effect, are used to analyze the time-dependent dynamic behaviors. Results show that after impulse most of the vibrations are absorbed by the disk-spring compensator and the table can maintain a small vibration around the equilibrium position.

抄録全体を表示

As fluid power sources mounted on practical and powerful micromachines such as in-pipe working micromachines using fluid power, micropumps having high power density are required. A piezoelectric micropump using resonance drive is proposed and developed. First, a large model of the proposed micropump is fabricated and the effectiveness of resonance drive is confirmed through basic experiments. Second, a micropump having the size of 9mm diameter and 10mm length for practical applications is fabricated. Next, frequency characteristics and load characteristics of the pressure-dependent flow rate are experimentally investigated with various structural parameters for the optimal design. Through those experiments, the optimal amounts of additional mass and valve thickness are experimentally obtained for stable and high performance of the micropump. The maximum flow rate of 80mm³/s, maximum pumping pressure of 0.32MPa and maximum power of 8.7mW are obtained at the driving frequency of 2.0kHz. Finally, the feasibility of developing the piezoelectric micropump using resonance drive is confirmed through comparisons of maximum power density among conventional micropumps.

抄録全体を表示

In the near future many aspects of our lives will be encompassed by tasks performed in cooperation with robots. The application of robots in home automation, agricultural production and medical operations etc. will be indispensable. As a result robots need to be made human-friendly and to execute tasks in cooperation with humans. Control systems for such robots should be designed to work imitating human characteristics. In this study, we have tried to achieve these goals by means of controlling a simple one degree-of-freedom cooperative robot. Firstly, the impedance characteristic of the human arm in a cooperative task is investigated. Then, this characteristic is implemented to control a robot in order to perform cooperative task with humans. A human followed the motion of an object, which is moved through desired trajectories. The motion is actuated by the linear motor of the one degree-of-freedom robot system. Trajectories used in the experiments of this method were minimum jerk (the rate of change of acceleration) trajectory, which was found during human and human cooperative task and optimum for muscle movement. As the muscle is mechanically analogous to a spring-damper system, a simple second-order equation is used as models for the arm dynamics. In the model, we considered mass, stiffness and damping factor. Impedance parameter is calculated from the position and force data obtained from the experiments and based on the “Estimation of Parametric Model”. Investigated impedance characteristic of human arm is then implemented to control a robot, which performed cooperative task with human. It is observed that the proposed control methodology has given human like movements to the robot for cooperating with human.

抄録全体を表示

This research proposes an organized process to analyze the transmission error and to synthesize the tolerances for globoidal cam mechanisms. First, the geometric mathematical models of the cam surface are determined by the conjugating theory. Based on these models and Taylor series, the output variable is expressed by sensitivity factors about design variables and the differences from the random and the mean of them respectively. And, the transmission error is also calculated according to the practical coordinate data on the manufactured cam surface and misalignments. By applying statistics and cost-tolerance function, the objective function subjected to the variance of the tolerances is established. The Lagrange multiplier is then involved to synthesize the optimum tolerances with minimizing manufacturing cost. This process is verified in an industrial example finally.

抄録全体を表示

New architectures of manufacturing systems have been proposed aiming at realizing more flexible control structures of manufacturing systems which can cope with dynamic changes in volume and variety of products. They are so called as holonic manufacturing systems, autonomous distributed manufacturing systems, random manufacturing systems and biological manufacturing systems. The objective of the present research is to develop an integrated process planning and scheduling system which is applicable to the holonic manufacturing systems. In the previous paper, procedures were proposed to recognize the machining features from the product model. A systematic method is proposed, in this paper, to select suitable machining sequences and sequences of machining equipment, by applying the genetic algorithm (GA) and the dynamic programming (DP) methods.

抄録全体を表示

Several types of non-destructive testing methods are used for detecting weld defects. Because the X-ray radiographic testing method is particularly useful in inspecting the inside of a weld metal, it is often used in industry. However, since the number of skilled inspectors for X-ray radiographic testing has been gradually decreasing, recently, several methods to detect weld defects from films automatically have been investigated to improve the quality of the detection results. However, X-ray film images contain much noise, and defect images show very low contrast and various shapes in spite of the same kind of defect. Moreover, boundaries between a defect image and the background are unclear, making it difficult to automate the inspection of X-ray films. If the type of defect image were to be judged by an expert system or a neural network which learns the rules of professional inspectors, the boundaries of the defect image would have to be detected in a manner similar to recognition by a human's (or an inspector's) sense of vision. Therefore, in this study, a new image processing method applied genetic algorithms that were a method of optimization, was constructed and applied to the detection of defect boundaries in detail.

抄録全体を表示

In the first report, the method of generating Concave conical gears was presented. In this paper, first the principal normal radii of the tooth surface generated by this method are expressed theoretically in terms of the basic dimensions of the gear and the tool. The principal normal radii of test gears are measured and found to be in good agreement with the theoretical values. Secondly, the allowable normal load of a pair of Concave conical gears is obtained. Tooth bearing tests prove that the Hertzian contact ellipse is larger than that of the conventional conical gear. Thus it is proven that the method of designing a pair of Concave conical gears is of practical use.

抄録全体を表示

A new information exchange method named recursive propagation is proposed in order to solve job shop scheduling problems in decentralized manufacturing systems. Each machine only has to notify the change of its plan to other machines which are directly influenced by the change. The effect of the change in the plan is directly fed back to the machine which notified the change. The change in the plan is notified to all the machines concerned by simple one-to-one communication among the machines, and the influence of the change caused by its action can be reported to the initiator through the same communication path. The proposed method is applied to a 20×10 job shop scheduling problem, and the feasibility of this approach is verified by simulations.

抄録全体を表示

Bone tissue stresses in mechanically loaded vertebrae were computationally investigated in order to reveal the influences of adaptive remodeling/modeling on stress distribution. Morphological alteration of the rat fifth caudal vertebrae was periodically and non-invasively measured with a microcomputed tomography (micro-CT). Von Mises stresses were calculated by using a finite element analysis (FEA) together with rigid-body spring models based on the consecutive micro-CT images. Median cross-sectional area periodically increased in the loaded rats depending on the duration of stimuli, which was caused by periosteal woven bone formation. FEA including the newly formed bone demonstrated that the loaded vertebrae showed the lower stress levels compared with non-loaded one. Averaged stress of the offset-loaded rat was markedly symmetry between ventral and dorsal sides under offset loading condition, while that of the non-loaded rat indicated asymmetry. Stress analyses suggested that the loaded vertebrae would adapt to the daily mechanical loading by depositing and calcifying woven bone over periosteum.

抄録全体を表示

The Assemblability Evaluation Method (AEM) is an effective tool developed by Hitachi, Ltd. to improve design quality for better assembly producibility. The AEM has been widely used by the Hitachi Group as well as by more than 20 other well-known companies around the world. Using this method, in the early design stage, product design quality is analyzed quantitatively and weaknesses in the design's assembly producibility are highlighted. In addition, the effects of design improvements are confirmed with respect to assembly cost. Through these activities, design improvement is realized. In order to improve the functionality and the accuracy of the method to allow a wide variety of use, the extended AEM has been developed. Based on a constructed product and process model, a new evaluation system has been developed and part-based cost estimation has been realized. In this paper, the concept, theory, evaluation procedure, and accuracy of the extended method are described.

抄録全体を表示

Global competition forces industrial companies to reduce cost and time to develop new manufacturing systems. To achieve this goal, collaborative design projects will be more popular among different companies or divisions. The design knowledge, however, is usually not well organized or archived in a digital form. This paper proposes a design agent system to navigate engineers in the design process of manufacturing systems. The design agents digitally model design processes itself, parameters for each design activity, engineering tools and rational logic rules. The design agents communicate with each other to help manufacturing system designers on distributed sites in the collaborative design processes online. In this paper, the structure, roles, and functions of the design agents are discussed. The proposed design agent system is implemented using JAVA programming language.

抄録全体を表示

Focusing our attention mainly on the shape quality of formed cups, the conventional cylindrical cup-drawing and the stretch-drawing processes with or without ironing are carried out. Four materials including titanium are tested. The shape quality of the products is represented by the uniformity of the wall thickness and the roundness of the cup cross-section. A new index, the distortion index, is introduced to evaluate the lack of roundness. Comparing with the cups formed by the conventional deep-drawing, the effects of the stretching and ironing on the shape quality are investigated in detail. As a rule, the stretching as well as the ironing makes the wall thickness to distribute more uniformly. Broadly speaking, the roundness of the cup is improved by the accompanied ironing with the reduction in thickness. This is not necessarily true for the stretching. However, the complete ironing does not improve the roundness of the copper cup. Typical shapes of the distorted cup cross-section are demonstrated, such as are oval, square, cross and others. For the deep- and stretch-drawing, the cup distortion pattern is related to the planar anisotropy of the tensile material properties. This is not the case for the ironing.

抄録全体を表示

This paper deals with the development of a micro ultrasonic abrasive machining system. The size of every component for opto-electrical devices or micro electro-mechanical systems (MEMS) has been reduced in recent years due to progress in opto-digital communications technology. The demands for micro-sized holes, slits and 3D structures of hard brittle materials such as ceramics and glass are considerable. In this study, a micro ultrasonic abrasive machining system was developed, which has an aerostatic ultrasonic vibration spindle, 3-axis NC sliding tables, dynamometer for machining pressure control and on-machine shaping system for small-diameter tools. The tools (0.03-1.0mm in diameter) and ultra-fine SiC slurry are used in the micro ultrasonic machining, and basic characteristics in micro-hole machining of glass are investigated. As the tool diameter becomes smaller, the machining speed and tool wear become the worse. However, rotating the tool doubled the machining speed, and decreased a protrusion left in the center of the machined hole due to cavitation.

抄録全体を表示

In this paper, the robust D-stability problem for a class of nominally stable linear uncertain discrete systems with multiple time delays is considered. A delay-dependent criterion is first proposed to guarantee the D-stability of the uncertain system subject to structured perturbations. A criterion deduced from the robust D-stability criterion is then proposed to ensure the robust asymptotic stability of the uncertain system. It is shown that our results are less conservative than some other results in recent literature.

抄録全体を表示

Recursive algorithms for parameter estimation of Wiener-Hammerstein (W-H) models are developed. These algorithms are derived on the basis of minimizing cost functions of the output errors, the equation errors, and the prediction errors. Convergence conditions of the developed algorithms are established. Numerical results, to test the algorithms and illustrate their estimation accuracy, are given.

抄録全体を表示

Geometric constraints and formation of general-type Goldberg five-revolute mechanism are outlined through the analytical geometry and its general analytical kinematic closed-form solutions are derived based on matrix algebra. Applying the concept of relative motion and using the coordinate-transformation matrices, we not only present the parametric formulas of its coupler link and coupler point but also provide a procedure for the higher-order analysis of coupler curve. Moreover, this mechanism is used for the dimensional synthesis, function, path and motion generation by the nonlinear programming algorithm. Finally, three numerical examples are given for illustrations and their results of synthesis are separately verified by computer animation with 3D computer graphics.

抄録全体を表示

In this paper we present a remeshing algorithm for irregular meshes with boundaries. The irregular meshes are approximated by regular meshes that have topological regularity, which is essential for the multiresolution analysis of the given irregular meshes. Normal meshes are used to reduce the necessary data size at each resolution level of the regularized meshes. The normal mesh uses one scalar value, i. e., normal offset value that is calculated by the regular rule of a uniform subdivision and normal sampling, while other remeshing schemes use one 3D vector at each vertex. Since the normal offset cannot be adopted for the boundaries of meshes, we use a combined subdivision scheme that resolves the problem of the proposed normal offset method at the boundaries. Lastly, an example showing the effectiveness of the proposed scheme to reduce the data size of a mesh model is included.

抄録全体を表示

This paper presents two types of the dual mode transmission for use in a motorcycle. A motorcycle transmission typically using the discrete speed ratio transmission that works by alternating the gear drive, and the continuously variable transmission (CVT) that transmits power by using the rubber V-belt. The dual mode transmission described in this paper, utilizing a V-belt drive, a fixed ratio mechanism, and a planetary gear train, can provide two operation regimes over the full speed ratio range by means engaged clutches. One is the fixed gear ratio and differential transmission system; the other is the differential and continuously variable transmission system. The kinematics, power flow, and mechanical efficiency of each transmission system are analyzed. An example is employed to illustrate the design procedure. Furthermore, several available design concepts of the dual mode transmissions for motorcycle applications are proposed.

抄録全体を表示

Coordinates measuring machines (CMMs) are commonly utilized to take measurement data from manufactured surfaces for inspection purposes. The measurement data are then used to evaluate the geometric form errors associated with the surface. Traditionally, the evaluation of spherical form errors involves an optimization process of fitting a substitute sphere to the sampled points. This paper proposes the computational strategies for sphericity with respect to ASME Y14.5M-1994 standard. The proposed methods consider the trade-off between the accuracy of sphericity and the efficiency of inspection. Two approaches of computational metrology based on genetic algorithms (GAs) are proposed to explore the optimality of sphericity measurements and the sphericity feasibility analysis, respectively. The proposed algorithms are verified by using several CMM data sets. Observing from the computational results, the proposed algorithms are practical for on-line implementation to the sphericity evaluation. Using the GA-based computational techniques, the accuracy of sphericity assessment and the efficiency of sphericity feasibility analysis are agreeable.

抄録全体を表示