Submerged long-span gates which dam wide rivers can undergo violent streamwise vibrations caused by vortex shedding beneath the gate. This study presents flow-induced vibration characteristics which were obtained in a model gate test. From the measured vibration frequencies and damping ratios in air and water, the level of fluid excitation and the added mass for small-amplitude gate vibrations are calculated and reduced to a dimensionless form. Thus, the vibration criteria are obtained. In addition, the average values of the maximum amplitudes of gate vibration were measured. The results of these experiments, taken as a whole, suggest that the flow-induced vibration characteristics of the long-span gates are well predicted by dimensionless parameters, such as the reduced gate opening and the reduced velocity.

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A new method of measuring displacement by means of variations of sound frequency and length of an air column in a stopped resonant pipe has been investigated. In this study, a speaker was used as the sound-generating source instead of the air jet, which was used for the feedback excitation mechanism on the edge instrument. This paper deals with a new kind of displacement sensor using an electric feedback circuit. A sweep signal is radiated from the speaker through the small hole which is opened on one end of the closed resonant pipe, toward the inside of the air column. The sound pressure takes the largest value at the resonant frequency. The displacement of the plunger which is inserted from the other end of the pipe corresponds to the length of the air column. Thus; the displacement of the plunger corresponds well to the resonant frequency of the air column. The phase-locked loop device is adopted for stability of the resonance and frequency

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The previous reports by the authors presented analytical methods for determining the sensitivities of the eigenvalues and eigenvectors and the sensitivity of the direct frequency response (DFR) of coupled acoustic-structural systems, with the aim of reducing vehicle interior noise levels. As a continuation of the previous studies, this paper deals with an investigation of the modal frequency response (MFR) of coupled systems and proposes methods for analyzing their MFR sensitivities. Two types of analytical methods are derived for determining the MFR sensitivities ; one is based on the eigenpair sensitivities of a coupled system and the other on the direct differentiation of the modal frequency response. It is shown that the latter method can also be derived from the DFR sensitivity and that it is a more effective method in terms of calculation accuracy and efficiency. A coupled acoustic-box model and a coupled acoustic-vehicle model are analyzed to confirm the applicability of the proposed methods to actual noise analysis problems.

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The authors apply the transfer influence coefticient method to a two-dimensional tree structure, and formulate a general algorithm to analyse in-plane longitudinal and flexural coupled free vibration. The tree structure, which is mainly found in the F-shaped structure of machine tools, pipeline systems and so on, has some crooked parts and subsystems but has no closed loop in the system. It is modeled as a distributed mass system in the present algorithm. It is theoretically confirmed that some merits of the transfer influence coefficient method also hold for the two-dimensional tree structure; that is, boundary conditions are easily controlled by the spring constants, and false roots in the use of the bisection method as a solution to the frequency equation can readily be eliminated by using the values obtained in the computational process. The occurrence mechanism of false roots is discussed in detail.

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An algorithm for a two-dimensional tree structure formulated in the previous report by applying the transfer influence coefficient method is extended in order to analyse the longitudinal, flexural and torsional coupled free vibration of a three-dimensional tree structure. Moreover, adequate selection of a nonzero state variable as an initial standard value in the computation of characteristic modes and the problem of false roots which occur in the analysis for a structure with subsystems by applying the transfer matrix method are also discussed. The superiority of the present method over the transfer matrix method in the computational accuracy and the computation speed is confirmed by the numerical computation for typical models of both two-and three-dimensional tree structures.

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This paper describes the vibration control of a rotating disk to which some dynamic absorbers are attached in several arrangements for the case that the rotating disk is subjected to an axial external force fixed in space at a point on the outer circumference of the disk. The effects of the rotation of disk and of the coupling among characteristic modes are taken into account in the theoretical analysis. From the numerical computational results, the authors clarified the relationship between arrangement of dynamic absorbers in the circumferential direction and vibration control of disk and so on, and suggested the possibility of the optimal arrangement of the dynamic absorbers. The analytical results were qualitatively verified through experiment.

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Damping mechanisms based on gyroscopic moments are studied and their characteristics are compared with conventional mechanisms. A generalized form of Schlick's gyroscope is theoretically analyzed, and an optimal design method is derived. The stabilizing effect is compared with the rotational dynamic vibration absorber. It turns out that the effect of the passive gyroscopic stabilizer depends on the rotating speed of the gyroscope; thus the stabilizer has no essential limitation by the inertial moment such as there is with the rotational dynamic vibration absorber. The gimbal movement of the CMG (control moment gyroscope) is directly controlled with an actuator, thus it can be used as a fully active vibration control mechanism. The single-gimbal CMG is compared with the RW (reaction wheel) with respect to the damping efficiency for impulsive disturbances. Experiments with a single-gimbal CMG for a Pendulum are carried out and the results prove the efficiency.

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An analytical investigation is presented on leakage-flow-induced vibrations of an axisymmetric body. In the case of a narrow annular passage between a tapered outer cylinder and a tapered axisymmetric body, the fluid-dynamic forces acting on the body have been divided into the fluid-dynamic mass, damping and stiffness. The following conclusions were obtained through research on those coefficients. The dynamic instability of the systems is due to fhe phade lag of the fluid-dynamic force for displacement of the body caused by harmonic vibration. The fluid-dynamic damping is obtained in two parts: one is independent of the frequency and the other is a function of the frequency, and the negative damping is caused by the fluid-dynamic damping which is a function of the frequency. When the frequency is very large, the fluid-dynamic mass agrees with added mass within the fluid at rest.

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Flexibility of driving systems produces robot arm vibration. Since vibration decreases the operation efficiency and quality, the prevention of such vibration becomed an important consideration in robot arm control. High-gain feedback of disortion in driving systems at each joint improves the oscillatory behavior of the robot system. By using a theory of multivariable root loci, we present two propositions on the behavior of the closed-loop eigenvalues when the high-gain feedback of distortion is implemented.

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Although there is a large demand for wire-mobile robots, it is very difficult to design a mobile robot that both avoids obstacles and transfers to a branch wire. This paper describes methods of obstacle avoidance and transferral to branch wires for a wire-mobile robot with a multiunit structure. Basic analysis, synthesis, and experimental results clarify the kinematics of and control method for this mobile robot. We also demonstrate an ultrasonic sensing system for environmental recognition, which is necessary for autonomous robot motion. The multiunit structure avoids obstacles, but it uses many actuators. We therefore propose a compact wire-mobile robot with a balancer that transfers the center of gravity.

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A holonic manipulator has many electronic devices such as control computers and sensors among its local mechanical components. This kind of manipulator design has three major advantages: reduction of wire harness between devices, high software productivity, and fault tolerability of the system. In this paper, we first represent two actually developed holonic manipulators. Then we compose a simple structural model of the manipulator focusing particularly on the constituent component mass so that the efficiency ratio of payload mass to total manipulator mass can be analyzed. This efficiency ratio exhibits a saturated increase consistent with the payload mass, which is due to DC servomotor mass/power characteristics and mechanical structure mass/stress characteristics. For the improvement of the efficiency ratio, the fused structure design has been employed mainly between heat sinks or support members of the computer and mechanical structure. The achieved improvement is estimated with the model using a mass fusion function.

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A new control method for the truss-type parallel manipulator is proposed by a neural network approach. The proposed method solves the inverse kinematic problem involving kinematic redundancy with the multilayered neural network model. This neural network model is prepared to provide the kinematic relation of the manipulator as well as the criterion function for the configuration and/or motion control. A concept of the modular neural network is employed to cope with the immensity of the network, in which a neural network module is constructed separately for each kinematic module. This modular neural network approach enables the network system for the configuration control to be adopted for various combinations of truss modules. Some simulation studies demonstrate the effectiveness and the potential capability of the proposed method.

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Large space structures (LSS) will be constructed by linking flexible structures and so will easily undergo bending vibrations while being moved by rocket engines. In this paper, mobile control and vibration control methods are newly proposed for such a mobile linked flexible system which is composed of joints, flexible links and floating pads, by allocating 4 compressed-air jet nozzles on each floating pad, and a DC motor at the joint of the linkage between the adjacent flexible link. With control of these actuators, the flexible system should go along the supplied trajectory and the bending vibrations should be decreased. In order to derive the dynamics of such a linked system, the system is modelled by a lumped parameter system. Then the proposed control method is applied to a flexible system for the experiment which is totally floated by air bearings at the joints, so that there is no reaction force from the ground to the floating flexible system. Some experimental results are shown to demonstrate the effect of the proposed mobile control and vibration control methods.

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Repulsive magnetic levitation systems for vehicle suspensions are statically stable but dynamically of zero or low damping characteristics. In paticular, it is reported that electrodynamic suspensions have negative damping in some operating conditions. In this paper, an active suspension is applied to the secondary suspension of the zero-damping magnetic levitation system in order to improve the dynamic stability of both the car body and truck. The active suspension with a pneumatic actuator is designed by optimal regulator theory. The kinetic energy and the potential energy of both the car body and truck are evaluated according to an evaluation criterion. The two-degrees-of-freedom suspension model of this MAGLEV system is analyzed theoretically and compared with the experimental results. The theoretical analysis and experimental results show that the dynamic stability is much improved by the active secondary suspension.

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A method of magnetic levitation control of a traveling steel belt is presented. A traveling steel belt is supported in a contactless manner by attractive forces of electromagnetic actuators which are controlled by feedback signals from gap sensors to stabilize the levitation behavior. A suboptimal control theory is applied to minimize effects of spillover of residual vibration modes of the belt. To verify the usefulness of the method, a digital control experiment was performed using a SUS430 steel belt.

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The conventional traction control system has only a slip control feature which prevents wheel spin when starting or accelerating on a slippery road surface. This paper describes the unique safety technology of an ddvanced traction control system which enables the driver to trace corners on a paved road smoothly and safely by preventing excessive lateral acceleration.

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In this paper, the effect of inlet pressure at the bearing entrance on the static and dynamic characteristics of finite-width tilting-pad journal bearings is investigated theoretically. The inlet pressure for a finite-width pad is obtained by assuming the conservation of mechanical energy in the midplane in front of the bearing inlet and a proper polynomial expression as an inlet pressure distribution in the lateral direction. The film pressure is numerically calculated using the inlet pressure as the pressure boundary condition at the leading edge of each pad. Numerical results with or without inlet pressure for a wide range of eccentricity ratios or Sommerfeld numbers are compared. The analysis shows that there is a significant influence of the inlet pressure on the dynamic characteristics of tilting-pad journal bearings, especially on the stiffness coefficient.

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Rippling failure occurring on rollers and gears is well known as one of the phenomena resulting from plastic flow of the surface layer caused by repeated sliding-rolling contact. We previously investigated rippling failure occurring on gears and rollers by using only turbine oil as lubricant. The rippling failure which occurs due to the repeated higher contact stress is closely related to lubricant. In this paper, we considered how lubricants influence the rippling failure. In particular, the effects of additives and viscosity of lubricants were investigated in detail.

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In this study, carburized gears of m=1.0-1.5 with various effective case depths are put to bending fatigue tests, and the fatigue strength is obtained. The test results verify that the effective case depth recommended in the AGMA standard is appropriate for the enhancement of bending strength. 0n the basis of results, S-N curves are determined and illustrated. The fatigue strength of the gears is about 1100 MPa. The fatigue strength is compared and illustrated with the strength of the gear teeth of m=5, and the effect of the tooth size on the fatigue strength is estimated quantitatively. The estimated size factor of the carburized gears is 1.0-1.3.

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Gear designing is traditionally based on the factor of safety, and the possibility of failure is quite often arbitrary. Fatigue failure is a random variable for which knowledge of the distribution functions of life and strength is essential in the estimation of bending fatigue failure and in reliability analysis. In this paper, to obtain the basic data for gear bending fatigue strength design, stationary bending fatigue testing of super-carburized steel gears with two different case depths was performed under a constant load range condition by using an electrohydraulic servo-controlled pulsating bending testing machine. The result obtained shows that the fatigue life distribution and the fatigue strength distribution are well represented by a three-parameter Weibull distribution. Reliabilities based on safety design criteria for constant stress and random stress fatigue are talculated from available fatigue data. The relationship between the deterministic central factor of safety and reliability is also discussed.

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To examine the effects of contact pressure and relative slip displacement on flattening conditions of surface asperities with no bulk plastic deformation of the workmetal, disk specimens were compressed by a punch in a closed die and rotated with the die. Slight relative slip displacement under the contact pressure remarkably accelerated the flattening of the surface asperites and thereby the workmetal surfaces could be smoothed completely to the same surface roughness as the tool. The changes in surface roughness of the workmetal could be approximated by the experimental equations expressed as a function of contact pressure and relative slip displacement. On the basis of these results, the flattening conditions of surface asperities accompanied by bulk plastic deformation of the workmetal were investigated by the free upsetting of a disk specimen and the upsetting of a ring specimen in a closed die. Consequently, the smoothing conditions of the workmetal surface in these forming processes could also be approximated by the same equations as the above experimental equations.

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An investigation was done using workpieces with an inclined front face drilled by a gun drill and long drill (with a diameter of l0 mm). The inclination angles are 0°, 15°, 30°and 45°. Another investigation was made for workpieces with a prebored hole, next to which was drilled a parallel hole by a gun drill. The wall thickness between the two holes and the diameters of the prebored hole and of the parallel hole were varied. As a result, the following are clarified. The direction of the cutting force during the cutting of an inclined front face influences the hole deviation. Regarding the gun drill, the hole deviates toward the positive direction of the X-axis, i. e., in the same direction as the front work face. Regarding the long drill, the hole deviates toward the negative direction. Parallel hole deviation increases with prebored hole diameter. Hole deviation sharply increases when the wall thickness between two holes reaches a certain value.

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It has been noted that the deflection of the end mill and workpiece produced by the cutting force is a main cause of surface error in the end milling process. Because of the deflection, the surface error becomes even worse in the case of inside cornering cut. To improve machining accuracy, a predictive analysis on the behavior of the cutting force is performed indirectly by means of chip area. Based on the analysis, cutting methods with decreased axial depth of cut and improved shape of the machined surface in the preceding cut are proposed. Also, constraint adaptive control is considered against the rapid variance of cutting force. Through machining experiments, the effectiveness of the cutting methods and the adaptive control in decreasing the surface error in the corner is ascertained.

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A method for measuring the form error of spherical parts, for example, the steel ball used in a bearing assembly, was developed in the previous paper. The measured result showed that the steel balls usually had a form error with three or four undulations. In the present report, a harmonic analysis by the spherical function is introduced to evaluate the sphericities of the steel balls. The "spherical spectrum" defined in this paper has invariant values for each ball, even if the measuring coordinate axes are changed. Steel balls which are sampled in various stages of different finishing processes are measured and the spherical spectrum is calculated.

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Cutting temperature and forces are two dominant parameters that influence finish quality and tool life in machining. This paper undertakes the evaluation of these two factors in relation to machining by a self-propelled rotary tool, an efficient cutter recently reported to be superior in cutting some new materials. Temperature analysis is based on a model of a heat source movind cyclically along the cutting edge. Both analytical and experimental rtsults indicate that the rotating motion of the cutting edge transfers heat away from the cutting zone with the result being a reduced cutting temperature. Temperature of the cutting edge drops to the neighborhood of the ambient value after it passes the cutting zone. Cutting forces of the rotary tool are found to be smaller, especially the radial thrust component, which is 30-40 % lower, than those of the fixed circular tool.

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