This report deals with the experimental study of seismic response behavior of piping systems in the industrial facilities such as petro-chemical plants and nuclear power plants. Special attention is focussed on the nonlinear dynamic response of piping systems due to frictional vibration appeared among piping and supporting devices. 3 dimensional mock-up piping model having 30 m Iength and 8 inches diameter is excited by large scale (15 m x 15 m) shaking table. Power spectra of the response vibration and loading-response relations in the form of hysteresis loop under several excitation levels are calculated. Response reduction effect caused by frictional vibration is evaluated and demonstrated in terms of "response reduction factor". Numerical simulation by use of nonlinear simplified friction model is also performed and calculated piping response is compared with those from vibration tests.

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Self-excited forced vibrations with solid friction of a block lying on a moving surface of nonconstant speed are treated theoretically, using an averaging method, in the case of the cubic friction-velocity characteristic curve. First approximate solutions of the harmonic vibration types of [ I ] and [ II ] can occur in the cubic case, as well as the linear one. In the present report, we studied several features of steady-state vibrations and stabilities of the harmonic solutions of these types. Furthermore, the behavior of a block in the vicinity of singular points is shown, using various trajectories in the R-ε plane, and vibrations of the nonharmonic type, accompanied by the occurrence of limit cycles, are studied. Finally, these first approximate solutions calculated by the averaging method are compared with the ones obtained through the use of the precise piecewise linear approximation method.

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To characterize chaotic oscillations arizing in nonlinear systems, a method of statistical mechanics is applied. As examples, the van der Pol-Mathieu vibration system, the forced pendulum system and the Duffing system are taken up, and their phase plane portrait and Poincare maps are obtained by numerical integration. The Liapunov exponent, the pattern of coarse-grained expansion rate and the temporal scaling exponent are determined. The results indicate that the positive Liapunov exponent is approximated very well by a one dimensional Liapunov exponent and that the characteristics of chaotic attractors are shown by the peak in the above dynamic structure functions.

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The authors propose a method by which to design an optimum vibration control system composed of continuous body structures using modal analysis and sensitivity analysis. The mechanical structures are modeled first by FEM. This spatial model is of such a high degree-of-freedom (DOF) that a control system cannot be designed. This spatial model is transformed into a modal model in order to reduce DOF. The optimum control system is designed by applying the optimum control theory to this reduced model. However, stability of the control system is not always guaranteed because the modal model ignores high-order modes. An optimization method of the control system which guarantees stability of the actual system is proposed in this paper. We propose also an experimental optimization of the control system based on experimental modal analysis. The optimization is performed using sensitivity analysis and nonlinear programming. The effectiveness of the proposed method is verified by both simulation and experiment.

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In optimal vibration control, the control characteristic of vibration depends on the criterion function and the coordinate system in the modelling, since the objective function is not necessarily described by the state variables. In this study, the relationship between the control characteristics and the criterion functions was investigated for the case of adopting the state variables of the absolute coordinate and the relative coordinate in the optimal control and feedforward control. In the feedforward control, two control laws are presented for the cases of assuming and not assuming the dynamics of disturbance. By carrying out numerical calculations, the control characteristics of each case were clarified.

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Active vibration control is important in protecting precision machines from microvibration. However conventional active vibration controllers have only feedback control loops, for example, PID and LQR, thus, it is difficult to completly suppress shock motions. When the control object is excited by shock motions such as X-Y stage movements, it shows instantaneous response because of feedback control delay. This paper suggests a practical method for active control using feedforward control together with conventional feedback control. The authors paid attention that the X-Y stages repeat the identical pattern movements. In this case, it is easy to obtain sample data of the disturbance response, and the feedforward signal is calculated easily and correctly using this sample data and the measured transfer functions. This method is verified experimentally by driving a DC servo -stage on an active isolation system. The data show that this feedforward control method yields good results for self-exciting-type precision machines.

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This paper concerns vibration control for MDOF structures arranged in parallel. Recently, passive or active dynamic absorbers have been used widely in the field of vibration control of flexible structures. The authors proposed the method that both structures are controlled actively at the same time with a single actuator placed between them. However, there is the problem that, in general, the structures have many DOF and hence the reduced-order model is necessary to design the controller. The authors proposed the method in which a MDOF physical model is obtained by modifying the mode shapes. This paper shows the application of the reduced-order model method to 2-l DOF parallel structures. Effectiveness of the vibration control method to the MDOF system using this reduced-order model is demonstrated by simulation and experiment.

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This paper is concerned with an experimental study on optimal trajectory control of a variable geometry truss, which is one of the intelligent truss structures composed of a truss-type mechanism. The intelligent structure considered here is assumed to have many sensors and actuators. Thus, the intelligent structure utilized as a manipulator arm has high redundancy. In the first report, two efficient methods were proposed for manipulation trajectory control under the relaxed conditions of optimality, and the validity of the proposed methods is demonstrated through numerical simulations. In this study, the proposed methods are applied to a hardware experiment. The experimental results confirm the validity of the proposed control methods. Also, it is shown that an optical sensor feedback is effective for the precise control of the position and orientation of the end tip of the trus along the trajectory, even when these controllers have some modeling errors.

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With a view to applying the active wave control method for suppression of all vibration modes of a large scale-structure, a new type of moment-driven actuator using a piezo-electric ceramic is presented. Actuators for this purpose are required to be small and light, and still have enough power to control low-frequency vibration. From the viewpoint of applying moment control, two control laws for the active sink method are derived; one is to eliminate incident waves and the other to suppress transmitted waves. A standing wave suppression type state control method, which makes possible the dormancy of vibration modes, is also presented. Next, the ABC method is presented, by means of which a vibration-free state in a beam is achieved. The control effects due to thess methods are discussed. Experimental results using the moment-driven actuators are also presented, demonstrating the effectiveness of these methods. Finally, the effect of structural damping of a beam on the control effect of the wave control method is discussed, and the relationship between power flow and structural damping clarified.

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The containment vessel of a nuclear power plant, the LMFBR reactor vessel and a tall cylindrical tower are thin cylindrical shell structures of large diameter. Development of an evaluation technology for dynamic buckling of these structures due to wind or seismic loading is becoming very important. Some research works have been conducted recently, but the analysis generally requires unpractically large amount of CPU time. The development and the utility of a practical dynamic buckling analysis code using FEM, in which lumped masses, initial imperfection, and so on, can be taken into account, are reported here.

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A numerical analysis method is developed to investigate the dynamic response of elastic slider-crank mechanism systems. The equation of motion was obtained by means of the finite-element technique, including the nonlinear effects of a centrifugal force and an axial force. The method is applied to a rotating cantilever beam and slider-crank mechanism, and the natural frequencies and the time responses are calculated numerically. The effects of the angular speed and the crank position on the elastic response are also discussed. It is found that the nonlinear effects cannot be ignored for the slider-crank mechanism even at a low angular speed.

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Industrial processes such as thermal, fluidic and chemical systems can be modeled as bilinear systems. These bilinear systems are, in most cases, linearized at one operating state and linear control systems are constructed. When that operating state is shifted to other state, the control performance in degraded and controller parameters are required to be readjusted. This fact is based upon the change of the system dynamic characteristics due to the shift of the operating state. In this paper, we propose a dynamic compensating method using three kinds of nonlinear observers for bilinear systems whose estimated states are fedback for globally linearizing the system dynamics and discuss the reduction of the effects of system characteristic changes. These problems are solved based upon the differential geometric approach. Simulation of simple thermal systems shows that the effects of some changes of operating states are favorably compensated by this compensator.

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Time series, both simulated and measured, are analyzed by auto-Wigner distridution (AWD). In this paper, two main analyses are carried out : ( 1 ) Frequency-responses are derived from discrete -Wigner distribution (DWD), then compared with both those calculated from pseudo-Wigner distribution (PWD), and fast Fourier transform (FFT). ( 2 ) An algorithm on the automatic determination of optimum Lag-window length in RID (reduced interference distribution) is developed. As the result, ( 1 ) the frequency responses calculated from DWD are proved to be the most accurate among all of the methods tested, ( 2 ) it is made clear that for several kinds of signal, the algorithm developed in this study can generate an optimum Lag-window length in RID.

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Nonlinear unbalance response of a flexible rotor supported at one end by a squeeze film damper with a centering spring is studied for various amounts of unbalance. Oil film boundaries of squeeze film are assumed to be π and 2π. For each condition, there exists a critical unbalance above which the vibration becomes extremely large. The occurrence of the large vibration is explained by the fact that the damping force at a high eccentricity ratio becomes infinitely large and the damper acts as a simple support. In order to attain high reliability of rotor systems, the elimination of large vibration is quite important. In this paper, a design guideline of rotor systems is discussed by comparing the vibration characteristics of the rotor in the case of π and 2π film conditions.

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For various amounts of unbalance, damper clearance and damper bearing parameter, nonlinear unbalance responses of a flexible rotor supported at one end by a squeeze film damper (SFD) without a centering spring are studied as a follow-up to the first report, which investigated SFD's with a centering spring. The rotor responses in the case of SFD of either 2π or π film model without a centering spring are found to be quite complicated, and are also recognized to show critical unbalances above which the vibration becomes extremely large. In this paper, through the comparison of the characteristics of the SFD with and without a centering spring, the optimum design of these rotor systems is discussed.

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Moving-bed heat exchangers have been used extensively in many industries, for instance, for waste-heat recovery from hot sintered metal of the steel manufacturing process. It has been reported in the previous paper that if the particle diameters are large, the effect of temperature distribution between surface and center of the particles on the characteristics of these systems is not negligible and has to be taken into account. In addition, three dimensionless parameters (NTU, Cr and Bi) governing the characteristics of these systems are described. In this paper, the effects of these three parameters on transient responses of the gas outlet temperature, subject to step changes of the belt moving speed and the gas fiow rate, are investigated. It has been found that the transient responses are mutually dependent upon these three parameters. Furthermore, the relationship beetween these parameters and the approximated time constant of the transient responses is also described.

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Static and dynamic behaviors of a rotational motion system composed of a prime mover and its load depend upon the relationship of torque-speed characteristics of both. Previous knowledge of the behavior is limited regarding the stability or instability of the system, and no further investigation such as regarding improvement of the system characteristics can be found. However, as computer feedback control of a rotational motion system becomes popular, the improvement of this method becomes very important in order to realize this excellent behavior. From this point of view, our study is concerned with the analysis and synthesis of how to improve the characteristics. The 1st-, 2nd- and 3rd-order systems were treated as object rotational systems on the assumption that these systems were linear and continuous.

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There are a number of unclarified points regarding the impact phenomena and the optimum design of tennis rackets. The present study is based on the idea that the dynamics of a racket consists of the dynamics of a rigid body with an arm swing given at a grip as a boundary condition, an impact between a ball and strings with racket frame as an input force, and the structural vibration of the racket. In this paper, impact force and impact duration are investigated, considering the strong nonlinearity of the restoring force of ball and strings. Furthermore, the coefficient of restitution of the tennis racket is estimated using a personal computer on the basis of the impact phenomena and the experimental modal analysis. In order to predict the contact duration, which has an influence on the racket vibration, a simple impact model has been proposed, i.e., that the contact duration is determined by the natural period of a whole system composed of the mass of the ball, the stiffness of the ball and strings, and the reduced mass of the racket at the impact point on the racket face. The calculated results agree fairly well with the experimental results.

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A new measuring apparatus for color images has been developed in order to distinguish glossy colored objects under fluorescent lamp illumination. The color image appatatus is mainly composed of a zoom lens, a mirror box, MOS cameras, a microcomputer and a color image processor. The zoom lens can automatically blur an image by the microcomputer. It is d very effective method for obtaining a blurred image in detecting glossy colored objects. Gloss can be omitted by blurring an original image of objects. In the blurred image, it is known that tristimulus values are not affected by image restoration if the modified Wiener filter method is employed. The blurred image is restored by the filter and is processed by a new analogical method utilizing a fuzzy set theory based on a visual psychophysical method. As a result of this experiment, it can be concluded that the system demonstrates the possibility of highly accurate distinction of glossy colored objects.

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We propose a microcapsule pump which is one of the realizable and useful micromachines today. We show that the microcapsule pump produces a microflow from the microstorage tank of solution, unlike other pumps, which pumps out the liquid from the inlet to the outlet of the flow. The proposed microcapsule pump has the function of the microflow from the storage tank, depending on the environmental condition. For example, this microactuator system can be applied to drug delivery requiring a long time, such as insulin injection for diabetic patients, and other medical applications. This microcapsule pump structurally consists of an inlet with a semipermeable membrane, an outlet with a one-way valve and a storage tank controlled by osmotic pressure. The outflow side has a one -way valve that prevents backward flow of the solution from the outlet to the inlet. Since this pump is applied to medical science, it is of a very simple structure and easy to handle. It is possible that the outflow volume of internal solution and the rate of osmosis can be changed using semipermeable membranes with different properties. The salient feature of this proposed actuator is that an external driving power supply is not required in this microsystem. The size of the prototype of this microcapsule pump is 5 mm in diameter and 9.8 mm in length. Its weight is 0.7 g.

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Optimal reference trajectories for n-link robot manipulators are planned. They are generated from the performance indices which are the integral of the square of acceleration, jerk, and so on of the trajectory with respect to the control time. The optimal reference trajectories are compared through an experiment in high-speed motion control of a 2-link robot manipulator, and a good control performance is obtained in the case of higher continuity of the trajectory.

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The ROBOT CAT developed in this study is a kind of robot which can move in the air, and control its posture and perform soft landing. In the first report, the concept of the ROBOT CAT and its mechanism, actuator and control method were described. The ROBOT CAT executes so-called cat turning motion to control its posture in the air. The cat turning motion is 3D rotational motion of the kind a live cat perform when she is dropped upside down. The ROBOT CAT consists of a front and rear body and a flexible backbone connecting the two ends. The control method of the ROBOT CAT and the results of the free fall experiment are given in this paper. The cat turning motion was achieved with the robot in free fall. The experimental result indicates that all angular momentum of the robot was conserved throughout a fall.

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In the first paper, control methods and experimental results on postural stability and driving of the parallel bicycle-type mobile robot with controlling arms were reported. Static and dynamic analyses of the postural stability of the robot were described in the third report. Using the compound gravity center feedback control method utilized in the previous papers, high-speed driving of the robot is difficult without losing the postural stability because of the inertial effect of the robot at quick acceleration. In order to attain high-speed driving of the robot, in this paper, a compensating control method considering the inertial influence was proposed. The inertial torque caused by quick acceleration or deceleration of the robot was balanced with the gravity torque generated by displacing the compound gravity center from the contacting point between the ground and the robot. Also, a cycloidal curve was given as a reference path to drive the robot smoothly. Experiments show that high-speed driving of the robot with maximum acceleration of 6.52 m/s² and maximum velocity of 0.415 m/s was achieved without losing the postural stability, and the inertial compensation method proposed here is very useful.

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The development of a backpropagation (BP) algorithm for neuron training has made it possible to use the layered neural network for simulating the nonlinear system. On the other hand, the neuron training algorithm based on the extended Kalman filter algorithm (KNT) has been developed. It is already shown that KNT has high performance compared with the BP. In this report, we show a technique to accelerate the training speed of the KNT. We call this technique the VC (variable covariance) technique. By applying the KNT with the VC technique to an exclusive OR problem, we clarify the performance of the present acceleration technique.

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This paper deals with the design of an electrical model for the photovoltaic effect in a PLZT element to estimate, in advance, the performance of an optical actuator consisting of a PLZT element. The results of the basic experiment on the photovoltaic effect are shown, and they indicate that a parallel circuit including a current source, a resistance and a capacitance may be applicable to an electrical model for the photovoltaic effect, under the consideration of the lumped system. Then, the step response of the photovoltage is obtained theoretically according to the electrical model proposed. Since the theoretical results agree well with the results of the basic experiment, the electrical model proposed can be considered to be valid for practical use. Important aspects of the design of an exact model are also pointed out.

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This paper introduces an inspection system now under development which enables a very large number of manholes to be maintained. The purpose of the system is to make inspection work both safe and efficient. The inspection work is achieved by digital image processing. Images inside a manhole are recorded through a video camera which is attached to the top of a robot and controlled by an operator on the ground. The images are processed in various ways by a computer with the aid of the operator. The facility plan is drawn automatically on the basis of processed results. First, this paper presents high-accuracy edge orientation and curvature measurement methods, and facility recognition algorithms using edge curvature. Next, it describes facility inspection for an actual manhole.

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Laser light scattering data from lubricating oils contain information such as refractive index, sound velocity, density, elasticity and viscosity which are important physical properties under high -pressure EHL conditions. In the present study, an experimental apparatus for laser light scattering at high pressure was designed and set up, employing a Fabry-Perot interferometer and a newly designed diamond-anvil high-pressure cell. Rayleigh and Brillouin scattering spectra and sound velocity were measured at atmospheric pressure for benzene, castor oil, ethanol and BCCM (bicyclohexylcyclohexylmethane) and at high pressure for methanol and ethanol.

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This paper describes the effects of fluid inertial forces on viscoelastic squeeze film chracteristics. In the derivation of the modified Reynolds equation, the nonlinear Maxwell model combining the Rabinowitsch model and Maxwell model is used as a constitutive equation for the viscoelastic lubrication film, and the inertial term in the momentum equation is approximated by the mean value averaged over the film thickness. Applying the modified Reynolds equation to a parallel circular bearing with sinusoidal squeezing motion, the variation of pressure distribution with time is calculated numerically for various kinds of fluids such as Newtonian, pseudoplastic, linear Maxwell and nonlinear Maxwell fluids. Some numerical results are presented in graphic form, and the effects of inertial force on the viscoelastic squeeze film characteristics are discussed.

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In designing an optimum connecting rod, it is necessary to determine the oil film pressure (OFP) distribution at the big end under actual engine operating conditions because these conditions must be used as the boundary conditions of a structural analysis. Since it is very difficult to measure the OFP distribution, a bearing test rig has been developed to simulate the actual load of an operating engine. Measured data obtained with this test rig show a lower maximum oil film pressure and a wider pressure angle than the calculated results.

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This paper investigates the effects of surge wave, giving an exmple of the spring operating mechanism of the SF₆ circuit breaker when the helical spring operates as an actuator at high speed. It is proven by the dynamic analysis on the model of spring-mass system that the force of the helical spring decreases due to surge wave during operation. The force of the spring is a function of time in the model and not of its displacement. As the mass on the spring decreases, the force of the spring decreases. The spring characteristics are similar during surge time even if the turns of the coil are changed. High-speed mechanisms should be designed taking account of these characteristics.

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In establishing an effective method for accurately estimating the frequency spectrum of noise power radiated from gears, a basic theory was proposed in previous papers. The associated equations were derived to apply the theory to a circular plate with a solid shaft chosen as a simple model of gear bodies. Exciting the circular plate in the direction of the shaft, the radiated sound power was estimated. It compared favourably with the measured values. In this paper, the basic theory is extended to estimate the sound power radiated when the circular plate is excited in the direction normal to the tooth surface of helical gears, namely in a spatial, three-dimensional direction. Decomposing the exciting force into the axial force, radial and circumferential bending moments, the natural modes of flexural vibration of the circular plate are theoretically analysed. Using the results, the new equation of driving point mobility, which is one of the three parameters required for estimation, is derived. Also, it is shown that the other two equations of total loss factor and radiation loss factor are applicable in the same from as previously derived.

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The purpose of this study is to investigate the possibility of mirror finishing of ceramics by superfinishing. This report describes superfinishing of silicon nitride ^#(Si₃N₄), which is one kind of ceramics. As a result, mirror finishing by a superfinishing machine was found to be possible, and the result is reported.

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It is possible to incorporate a system which manages a knowledge base into an expert system. Because, by using this system, we can rebuild knowledge bases which have no logical contradictions with knowledge of experts and phenomena which we experience daily. However, it is difficult to build beyond systems in the machining field due to the existence of many kinds of knowledge, if we want to achieve rebuilding of the knowledge bases using current representation language. Thus, we developed a truth maintenance system for knowledge bases by using a new predicate-logic representation language. This paper describes how to manage knowledge bases and how to treat the functions in a truth maintenance system using this system when contradictions occur in the practical machining problem.

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In automatic welding of thin plates, it is well known that the application of an arc sensing system for the recognition of a weld line is relatively difficult. Therefore, an intelligent welding robot with a visual sensing system has been recently sought. However, it is not always easy to recognize the weld line clearly, because the weld line is sometimes very fine and the machined surfaces of steel plates have irregular brightness distribution. Therefore, a basic Cartesian-coordinate welding robot system with a visual sensor was constructed in order to investigate the recognition and automatic tracking of the weld line of machined steel plates. In this study, the effects of surface conditions of plates and the image processing of brightness distributions on the recognition of weld line were discussed, and moreover the effectiveness of the processes was experimentally confirmed.

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The stress intensity factors for surface cracks of work roll in hot strip mills are analyzed by means of the body force method. In the numerical analysis the contact between the crack surfaces is taken into account. The results of analysis show that the crack propagates mainly by means of the shear mode. The stress intensity factors for the shear mode are greatly affected by the friction coefficient between crack surfaces.

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This paper deals with the active vibration control of a flexible beam with various kinds of boundary conditions. It is the purpose of this paper to investigate the relationship between the power flow and the vibrational energy accumulated in the beam. First, from the viewpoint of the conventional feedforward control method, the role of the power flow to suppress the vibrational energy is discussed. Next, by using a transfer matrix method, this paper derives the control law of the active sink method whose principle has been presented in the previous paper. Then, it is shown that all the vibration modes of a beam with arbitrary boundary conditions are suppressed by the active sink method. It is also shown that the power flow due to the active sink method is different from that of an infinite beam. Furthermore, this paper points out that there exist notches in the frequency characteristics of the power flow, and these are independent of vibration modes. Finally, an experiment is carried out to verify the existence of the active sink.

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For a small robot floating in water, it is impossible to position the arm precisely only with the actuator of the arm because the body is moved by the reaction of the fluid drag force and the inertia force acting on the arm. In this study, a position control system for the floating arm in water was developed based on the optimal control theory. Underwater robots generally have some thrusters on the body for movement and attitude control. This system controls the actuator of the arm and three thrusters of the body at the same time for positioning of the arm. The performance of the developed control system was confirmed by the model experiments and computer simulations.

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