An exact method using power series expansions is presented for solving free vibrations of a rotating thin shell of revolution having meridionally constant curvature. Equations of motion and boundary conditions are derived considering the effect of initial tensions due to the rotation. The equations of motion, which are differential equations with variable coefficients, are solved exactly by power series expansions. Frequencies and mode shapes of the shell with both ends clamped are presented, showing their variations with rotating angular velocity.

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There are many structural vibration problems which include fluid motion, such as an oil-filled power transformer tank. In fluid vibration analysis, the wave equation is commonly solved using the velocity potential or pressures as unknown variables in FEM, FDM and BEM. On the other hand, for structural vibration analysis, displacements are generally used as unknown variables. However, it is difficult to solve problems involving vibration of fluid and structure simultaneously by taking into account fluid-structure interactions, except by using added masses instead of fluid, or Herrmann's special variational principle. These approaches include special and complex techniques which are unfamiliar to most engineers. In this paper, a new vibration calculation method which can treat fluid and structure simultaneously is proposed, using an FEM displacement method which is familiar to most engineers. When the displacement method is applied to two-or three-dimensional fluid vibration, spurious vibration modes caused by excessive degrees of freedom are observed. These modes are not only bothersome but also hinder analysis accuracy. First, the generation process of the spurious modes was clarified. Then a rejection technique for them was developed. Finally, the new calculation method was applied to solve coupled vibrations of fluid and structure. The method was judged to be applicable to actual vibration analysis.

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In this paper, the authors report the development of a database for approximate predictions of the upper limit of frequency ranges up to which the vibration of finite-element models can be analyzed accurately enough and with sufficient confidence. The database with respect to finite-element models constructed with triangular elements is developed. First, the theoretical background of the development is explained. Second, the concise procedure of the development is introduced. Lastly, a practical application of the database to an automotive engine's oil-pan is shown to verify the validity and the usefulness of the database.

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In this paper, the analyses of the averaged equations by using the Grobner basis and Center manifold theory are proposed, and the nonlinear stability of the summed-type combination resonance is practically examined by these analyses. The bifurcation equations are algebraically solved by Grobner basis, so that the steady state amplitude is expressed by the parameters in the equation of motion. Furthermore by introduction the center manifold theory into the analysis of the averaged equation in the vicinity of the bifurcation point, the four dimensional averaged equations are reduced to two dimensional equations on the center manifold, and it is found that in the post-stable region the limit cycle occurs on the center manifold. The state plane is shown and for that limit cycle a more grobally stable analysis than one by using the Routh-Hurwitz criterion is carried out. The above analyses are performed by the use of computer algebra.

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An algorithm for free vibration analysis of a tree structure formulated in the previous reports by applying the transfer influence coefficient method is extended in order to analyze forced vibration of a tree structure which is mainly found in pipeline systems. The tree structure has some crooked parts and subsystems but has no closed loop in the systems. It is modeled as a distributed mass system with consideration of structural damping, and the present algorithm is formulated for both two- and three-dimensional tree structures. It is theoretically confirmed that some merits of the transfer influence coefficient method for free vibration analysis, for example, excellence in both computation accuracy and speed are also realized for the forced vibration analysis. Moreover, the present algorithm enables us to easily analyze a vibrating system excited by forced displacement by changing the corresponding spring constants conveniently.

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In this paper, we first describe the characteristics of engine damping that are necessary for the calculation of torsional vibration. Secondly, we describe an experiment in which two crankshaft pulleys with a torsional rubber damper are fitted to a 6-cylinder, high-speed diesel engine. The torsional waveforms of the damper inertia ring and the pulley are measured by means of phase-shift torsiograph equipment. The measured waveforms are harmonically analyzed and the dynamic characteristics of the stiffness and the damping are investigated from experimental viewpoint. In addition, torsional waveforms are calculated by means of the simulation method of torsional vibration, in which a transition matrix method is adopted. As a result of comparisons with experimental data, certain dynamic characteristics of pulleys with the torsional rubber damper have been made clear.

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In this paper, we propose a new parameter identification method for two inertia resonant systems with unknown Coulomb friction. The proposed method consists of two parts : the rigid model identification of the low-frequency band and the vibration model identification of the high frequency band. In the rigid model identification, we use the disturbance observer to identify the rigid model parameters. On the other hand, in the vibration model identification, fast Fourier transform is used to obtain the gains at the mechanical resonance frequency and at the anti resonance frequency. The gain curve fitting method based on both the rigid model parameters and the vdbration model parameters enables the elimination of the gain distortion caused by Coulomb friction and the estimation of the exact parameters.

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This paper deals with damping characteristics of a laminated cantilever. In order to determine the loss factor of a three-layered cantilever with arbitrary thickness, an analytical method of evaluating the position of the neutral plane is presented when it exists in the middle layer. Using both this method presented here and Ross' method applicable to the case wherein the neutral plane exists in the first layer, it was found that the position of the neutral plane can be obtained accurately. In addition, it is shown that its position leads to the determination of the loss factor of the three-layered cantilever. From experiments, it was ascertained that these theoretical values of the loss factor agreed well with the experimental values. Moreover, it was clarified which cantilever has better damping characteristics between three-layered and two-layered cantilevers.

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In this study, noise sources in a C-frame turret punch press are experimentally analyzed using a scale model. The distribution of sound pressure levels around the C-frame is measured in order to clarify the portion mainly generating the noise. As a result, the sound pressure level is found to become maximum at the open side of the C-frame, in which a punch-die set is usually installed. The result is the same as in previous former research work. However, the noise sources cannot be identified from such distribution. Thus, the sound field, which includes information of both amplitude and phase of sound vibration, is analyzed on planes parallel and perpendicular to the side panel of the C-frame by a modal technique. From the experimental results, it is found that the membranous vibration of the side panel, as well as the first specific vibration mode of the C-frame, must be damped for noise reduction.

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Two types of hybrid mass dampers with convertible active and passive modes were developed, which functioned as active mass dampers against wind and weak earthquakes and, at the same time, as passive dampers against medium and strong earthquakes. One uses a normal AC servomotor with a clutch which switches the operation modes using a control signal. The other uses a linear servomotor which can switch the modes by turning the power off and on. Excitation tests were carried out using an experimental model of each type of mass damper with a 80 kg moving mass and a model of a 5-story building with a 5800 kg total mass and 3.4 m height. The tests showed that both types of mass dampers achieved excellent active control performance, and that the mode switching was very effective against strong excitations.

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H^∞ control theory is currently the most poweful method for robust control theory and is very useful and practical because of the great amount of software related to computer-aided control system design. However, it has some disadvantages in that the H^∞ control system is a conservative system and cannot deal with robut performance. This is due to maximum singular values. Doyle proposed a structured singular value instead of a maximum singular value. This is called the μ synthesis theory and actively deals with robust performance using D-K iteration. This paper is concerned with computer-aided control system design for active vibration control systems using μ synthesis theory. First, the paradigm of μ synthesis theory is described concerning μ, robust performance and D-K iteration. Next, the relationships between the μ controller, robust performance, nominal performance and robust stability are discussed for the vibration control system.

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Frequency responses of stable planar and rotary motions in a partially tilled circular cylindirical tank, subjected to a pitching excitation at a frequency in the neighborhood of the lowest resonant frequency, are investigated. The nonlinearity of the liquid surface oscillation and the nonlinear coupling between the dominant modes and other modes(e.g., an axisymmetric mode) are considered in the response analysis of the sloshing motion. The equations governing the amplitude of those two types of liquid surface motions are derived and the stability analysis of each motion is conducted. An experiment was carried out using a model tank. Good agreement was found between the theoretical and experimental results. It is shown that the nonlinear analysis is important for estimating the sloshing responses.

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A numerical analysis method for acoustic field solutions to fluid-structure interaction problems has been successfully developed and applied to many problems. In the method, the small dynamic motion of compressible fluid can be analyzed by using a structural analysis code based on the finite-element displacement method using an analogy relating the scalar wave equation to elasticity ones, where compressible fluid is represented by using structural finite elements with pressure as the unknown nodal point variable. In this paper, the idea is applied to linear sloshing analysis. Theoretical consideration shows that the present method is equivalent to the conventional finite-element formulation based on the linear potential theory. The results of numerical analysis of liquid sloshing in a cubic tank and of fluid vibration in a U-tube under gravitational force are shown to be in excellent agreement with the theoretical values.

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The offset bearing, although claimed to be low in cost and relatively high in stability, has found limited industrial applications. This is probably because the offset bearing oil film coefficient data have not been provided for general use and also because the study of vibration characteristics involving the offset bearing and the bearing application to practical rotating machines have both been few. Accordingly the authors evaluated the high-pressure turbine shafting stability resulting from selective use of the 2-part, 3-part and 4-part offset bearings.

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Evaluating the rotating shaft stability in the bearing supporting the load applied when changing directions is a very laborious and costly task involving, for a start, the analysis of bearing oil film characteristics. We focused our study on the full-cylindrical, 2-lobe, offset-halves 4-tilting pad, and 5-tilting pad bearings currently in use most prevalently in industrial applications and studied the shafting stability in them. Consequently, we devised a new method capable of determining quantitatively the shafting natural frequency and damping ratio at any point of equilibrium in these typically shaped bearings.

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For their known advantages of low cost and relatively high stability of operation, the multilobe bearings have found prevalent industrial applications. To more clearly define the limit of usability for each of 2-lobe, 3-lobe and 4-lobe bearings, we studied in detail the rotating shaft stability at whole region of equilibrium in these multilobe bearings. Consequently, we found that the angles at which the multilobe bearings were installed could significantly influence the shafting stability. Also, we devised a new method capable of determining quantitatively the shafting natural frequency and damping ratio at any point of equilibrium in the multilobe bearings.

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A digital simulation program of hunting of a vehicle model was developed considering spin and gyroscopic action of wheelsets. Kalker's algorithm 'FASTSIM was introduced for calculations of creep force. Digital simulations for a representative example were made. It was shown that spin had the influence of decreasing creep coefficients equivalently, which decreased the critical speed without yaw dempers and increased that with yaw dempers. On the other hand, gyroscopic action of wheelsets increased criticel speed in all cases considered. It was also shown that spin had slight effect on forced hunting due to rail irregularities at vehicle speed much lower than critical speed, and simulations using Levi-Chartet's equation agreed well with those using 'FASTSIM' when spin was neglected.

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In this paper, we propose a model-based image processing for real-time position estimation of a moving object. Based on the dynamic equation of a moving object, which is usually nonlinear, we construct an extended Kalman filter predicting the position at the next sampling step from a series of image data. The prediction of the position is effectively used to restrict the search area in the image plane, which shortens the image processing time and reduce the effect of background noise. In addition, since the effect of the quantization errors can be reflcted in the Kalman filter algorithm as observation noise, we can achieve near-optimal estimation by the appropriate choice of covariance matrices. To show the effectiveness of the proposed method, we present experimental results for the simple-pendulum motion estimation.

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It has already been verified that the OGY method is useful for confining chaotic motion such as the Henon map or Lorentz attractor to a periodic orbit that is arbitrarily chosen. In this paper, chaos of a forced pendulum and its control by the OGY method are discussed. The forced pendulum has more complicated chaotic motion than the above-mentioned chaos. First, periodic orbits of the forced pendulum are explored in order to find desired periodic orbits and saddles on a Poincare section, the OGY method is applied, and then some aspects of the OGY method on the forced pendulum are presented.

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This paper is concerned with the modelling of dynamic behavior of hydraulic truck cranes in swing operation. A crane model with a hydraulic system is proposed to study control of swaying motion of a suspended load. The booms of the truck crane and a suspended load are approximately expressed by lumped-mass models, and the mechanical system of the truck crane is combined with a hydraulic system containing a swing moter, a hydraulic pump, an operated valve, and pipe lines. The dynamic behavior of the crane model in swing operation is simulated and compared with experimental results.

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This paper is concerned with the modelling of dynamic behavior of hydraulic truck cranes in elevating operation. It is important to analyze the dynamics of hydraulic and mechanical systems to control swaying motion of a suspended load in elevating operation. The booms of the truck crane and a suspended load are approximately expressed by lumped-mass models, and the mechanical system is combined with the hydraulic system containing an elevating cylinder, a hydraulic pump, a counter balance valve, an operated valve, and pipe lines. The dynamic behavior of the crane model in elevating operation is simulated and compared with experimental results. Material Handling Equipment, Dynamics of Machinery, Hydraulic System, Computer Simulation, Truck Crane, Elevating Operation, Sway of Load

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In this paper, an attempt to control a real system by changing LQ-control laws corresponding to the operating regions is reported. The system to be considered has nonlinear characteristics and is described by an inaccurate mathematical model. To develop this control, the method of "multi-sectional control" and the discussion on the robust stability are presented for an original real system, which is described by a first-order differential equation. This proposed method is also applied to the control of a simple hovercraft model which has nonlinear characteristics ; then the effectiveness of the method is demonstrated through several elevation control experiments.

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For speed control of hydraulic elevators, inverter control systems have good characteristics for saving energy and improving efficiency. This paper describes a newly developed special valve for hydraulic elevators controlled by an inverter. This valve has two channels of a pilot circuit with a check valve. One is for normal use, and the other is for backup in case of an emergency such as a blackout. Simulations and experiments were carried out on the effects of the deceleration adjuster in the emergency pilot circuit, and it was confirmed that the car could be safely stopped.

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A neural network was applied to the estimation of vehicle weight for improved power-train control. The change in acceleration response according to vehicle weight was measured and utilized for the estimation. The measured acceleration response was input into the neural network which then output the estimated vehicle weight. The accuracy of the estimation was evaluated by computer simulation and field experiments. Using the throttle valve opening and the time signals of vehicle speed and acceleration, the weight estimation error was reduced to 20 kg, within an acceptable amount for the vehicle control.

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In this paper a synthesis method of the dynamic compensator-type controller is presented, applying the neural network theory. This method consists of an identification mode of a control object and synthesis mode of the controller. In the identification mode the responses to sinusoidal sweep wave are used. In the synthesis mode a quadratic form is adopted for the criterion function to form a dynamic compensator-type controller. In order to investigate the usefulness of the present method, computer simulation and a control experiment of the active suspension model were carried out. As a result it was demonstrated that this application of the neural network is useful.

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Parameters of an internal combustion engine, such as the time constant of an air intake system, dead time of the combustion period, plant gain of throttle valve angle and inertia of moving parts, are variable depending on their point of operation. Parameters also vary due to aging of the plant or change of atmosphere. It is complicated, however, to compensate for the change of parameters, namely nonlinearity, in the control of engines. Recently, the H_∞ controller and Fuzzy controller, which have excellent robustness against nonlinearity, have been applied. In this study, the H_∞controller is adopted for engine torque control and is compared with the fuzzy controller and PID controller in terms of robustness. As a result, it is shown that the H_∞ controller has the best robustness when dead time is varied, but no robustness against variation of plant gain. By contrast, the fuzzy controller has the opposite characteristics.

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This study is concerned with a spillover problem in the magnetic levitation system. First, we show the typical spillover phenomena caused by the interaction between the control system and structure system of the magnetic levitation system. Next, applying the H^∞ control theory as a mixed sensitivity problem to a magnetic levitation system, we design a control system for a system without spillover and show the experimental data obtained when using the H^∞ controller. In this paper, the control performance of the mixed sensitivity problem is compared with the control performance of the robust stability problem through experiments. As a result, it has been clarified that the H^∞ controller as a mixed sensitivity problem is superior to that of a robust stability problem for disturbance attenuation. Next, we show the experimental data of more difficult magnetic levitation problems with a flexible guideway and a flexible slider. In experiments, we obtained good data of the magnetic levitation for such a system without spillover.

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Recently fuzzy control has been recognized to be of great usefulness in many engineering fields. However, the adjustment of fuzzy control parameters such as control rules, membership functions has been carried out by trial and error, and the definite design method of fuzzy control systems has not been established yet. In this paper, the influences of fuzzy inference methods on control performances have been examined by the simulations of a first order lag system with dead time. Moreover, the improvement of control performances in case of low-dimensional number of fuzzy labelings has been tried. Main results are as follows : (1)When the number of fuzzy labelings is low-dimension such as 3×3 divisions, control performances are dependent on fuzzy inference methods. Therefore, in case of low-dimensional number of fuzzy labelings, the selection of fuzzy inference methods is important. (2) Even in case of low-dimensional number of fuzzy labelings such as 3×3 divisions, by using the simple method of changing the height of the consequent membership function ZO, the non-linear characteristic of a fuzzy controller can be tuned and its control performances can be improved.

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PID (Proportional, Integral and Derivative) control is generally used in industrial products today, because of its simple algorithm and good adaptability on the scene. However, the matching of PID control parameters is difficult, thus we are looking forward to the development of auto-tuning of PID control parameters. In this study, we attempted fuzzy auto-tuning for a gasoline engine's electronic speed controller with PID control. Here fuzzy production rules are independently applied, and each rule is weighted by the degree of inputs of assumed parts. This fuzzy reasoning method is useful in simplifying the description of fuzzy production rules and provides a simple means of control similar to that performed by humans.

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The objective of this study is to establish a generic method to solve the minimum-time trajectory planning problem of a manipulator under both the average heat generation restriction and the intermediate-state variable restriction. We have already proposed a numerical method for this problem assuming that all the motors generate their maximum value of the average heat in the minimum-time trajectory. However, this assumption Cannot always be satisfied, especially in manipulators with a small coupling effect among joint coordinates. To remove this assumption, we present a new trajectory planning method and its computing algorithm concerning the Kuhn-Tucker theorem. Applying this method to many trajectory planning problems for both a three-DOF cartesian manipulator and a three-DOF articulated manipulator, it is found that the proposed method is efficient in solving any trajectory planning problem of a manipulator with a small coupling effect among coordinates. The quasi-minimum-time trajectory planning method is also applied comparatively to some problems, and it is found that this method can provide the approximate minimum-time solution with greatly reduced computing time.

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In this paper, we propose an altrenative control algorithm for the man-macine system. The man-machine system consists of a mechanical system and a human to operate the system. The system involves interaction between the environment and mechanical system and the interaction between the human operator and the mechanical system. When we design the controller for a man-machine system, it is desirable that we simultaneously specify human force augmentation ratio and maneuverability of the mechanical system. We design the controller for the man-machine system so that the system mimics the dynamics of the tool. Virtual tool dynamics is used to simulate tool dynamics. Intuitively, we know that the tool can amplify human force and it is stable when humans use it for tasks interacting with the envient. The stability of the system is guaranteed for a environment and a passive operator.

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Equations of motion of a closed-type manipulator are derived in consideration of characteristics of the step motors. Vibration control is achieved using two types of forcing functions. The first is the function of the pulse width modulation to avoid exciting resonance, and the second is the bang-bang control function on each step function. Dynamic characteristics of the system controlled by these method are analyzed theoretically and investigated experimentally.

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This paper proposes a method for designing a control law of providing a robotic manipulator which behaves according to a nominal dynamic model specified in operational space. The proposed control has a simple algorithm and requires no calibration of the mechanical parameters to formulate this control law. Initially, we consider the forces in operational space which will produce the difference between nominal dynamics and real manipulator dynamics. Secondly, introducing an observe to estimate such forces, a control system which can cancel out such forces and render the manipulator dynamics equal to the given nominal dynamic model will be designed. The proposed method was implemented in a real system and experiments were carried out to confirm its effectiveness. Finally, the experimental results are discussed.

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In this paper, optimal torque control of SCARA robot driven by stepping motor is described. Stepping motor is utilized less than the DC or AC servomotor because it has the demerit called the step-out phenomenon. Accordingly, the stepping motor must be controlled by velocity input without step-out. However, the stepping motor has the merit that it does not need a rotary sensor, and its control system is easily formed. For this reason, if optimal torque control becomes possible, in the future, the stepping motor will be utilized more as the actuator of industrial robots. To perform torque optimal control, physical parameters of the SCARA robot are identified step by step, and dynamic characteristics of the stepping motor are approximated with the transfer function of the 2nd-order lag element. Using these values, optimal torques are calculated by applying optimal control theory. Then, using velocity input adapted to the above torques, the stepping motor can be controlled. Since experimental values agreed well with the theoretical results, the applicability of the theory based on the above ideas was verified.

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This paper describes the development of an original tribometer to study the effects of the average speed V, average of friction roll speed and workpiece speed at the entrance of a contact zone, and of the relative sliding speed δV during deformation on frictional behavior in metal forming. The configuration used two rollers and herce rolling may be simulated. Mild steel sheets with a dull surface were used as workpieces. It was revealed that the friction coefficient decreases with an increase of δV or with a decrease of V. It was also confirmed that the increase of δV and the decrease of V promote flattening of the workpiece surface and yieid good performance of the lubrication film.

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New self-lubricating white metal composites containing graphite have been developed by applied powder metallurgy and evaluated with respect to friction and wear properties in air. The main results obtained are as follows : (1) XMA mapping photographs confirm that graphite is dispersed uniformly in white metal base composites. (2) Friction and wear properties on new white metal base composites are much superior to white metals. (3) The new composites give good self-lubricating for dry sliding friction at temperatures under 150°C with the results of low friction coefficient and low specific wear rate. (4) The PV limit is about 1020 N·cm^-2×cm·sec^-1 for composites containing 10 wt% graphite.

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For improving graphitic friction materials used up to now, we have developed and evaluated a new kind of graphitic friction material. The new material has improved properties such as high μ_d, high capacity of energy absorption and low wear. More importantly, the μ_d decreases with the increase of velocity. The new material, produced by powder metallurgy, is composed of NBR, aromatic polyamide fiber, carbon fiber, granulated pulp fiber, graphite, rubber-coated (or rubber-impregnated) exfoliated graphite, CaF₂, SiO₂ and polyimide resin. The results indicate that its μ^- velocity characteristics are similar to that of paper materials ; it possesses porosity as high as 40%, modulus of elasticity as low as 200 MPa and high wear resistance. The capacity of energy absorption is two times higher than that of heavy-duty sintered metallic materials under a wide range of operating conditions.

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The starting curves of rolling friction have been used for study of bifurcation-chaotic characteristics. The curve has the parameters m, A and B, which can change the patterns of the curve. In the case of m=3, the curve is symmetric with respect to a vertical axis, and agrees fundamentally with the logistic equation. For 1<m<3, the peak value of the curve shifts to the left side. On the other hand, for m>3, the peak value shifts to the right side. In the case of m=4, the curve agrees with the equation proposed by Feigenbaum. Thus the equations (curves) shown here are expanded mathematical models which contain the map functions presented previously. The following properties were elucidated after studying simulated results of the bifurcation phenomenon. The vertical distance of bifurcation points decreases uniformly with increase of m. However, the threshold points of bifurcation occur most rapidly in the case of m=2, and move to larger values of A as m increases or decreases. Since parameter m is related to loss energy, it is suggested that the bifurcation phenomena are also closely related to the loss energy of a system.

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Evaluation of the new measurement method of the central position of spindle rotation (CPSR)was carried out. The CPSR was measured after the spindle was shifted in the orthogonal direction with the spindle axis. Measurement results of the CPSR were good agreement with the shift length of the spindle axis. We also investigated the relationship between the CPSR on the oil hydrostatic bearing spindle and rotational speed, rotational direction, mass of the workpiece, axial load to the workpiece and residual unbalance. We found that these factors considerably affect the CPSR.

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This paper deals with effects of surface treatment on the bending fatigue strength of SCM 415 carburized spur gears. The test gears are shot peened, chemical polished and electropolished after carburization. The constant stress amplitude fatigue test is performed by using an electrohydraulic servo-controlled pulsating tester. The SN curves are obtained and the enhancement of fatigue strength due to surface treatment is clarified. The effect of surface conditions on the fatigue strength is evaluated quantitatively, and it is close to the relative surface condition factor used in the ISO strength rating formula.

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In the case of spiral bevel gears, a pair of drive and driven gear teeth meshes on a concave surface and a convex one consequently showing meshing characteristics which differ between the two surfaces used. In this paper, stress distributions at the tooth root of both surfaces (concave and convex) under various loading conditions was examined, and the experimental results were compared with computed ones by F.E.M. and Umezawa equation (Umezawa, JSME, 38-310, 1972, 1602). From the results, a practical formula to determine the stress distributions at the tooth root was introduced.

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Before the calculation of the load distribution on the line of contact and the tooth root stress of a bevel gear under tooth end bearing, the tooth root stress due to the concentrated load was calculated by means of the three-dimensional finite-element method (FEM). With the results by FEM, the approximate equations for the influence functions for bending moment of bevel gear tooth were derived. Furthermore, the effects of the number of teeth and the gear ratio on the characteristics of bending moment were clarified.

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This paper describes a new reduction gear system with a special mechanism. The mechanism is so designed that a pinion having a slight angle of inclination to the input-output axis oscillates while engaged simultaneously with an internal gear having the same number of teeth as the pinion and an internal gear having one tooth less than the pinion. Since this reduction gear system is free from the planetary-motion induced eccentricity of the pinion axis such as that seen in hypocycloid reduction gears, it produces only a small amount of vibration and noise. Moreover, it is highly advantageous in that it can be constructed in compact form with light weight, because it consists of 2 internal gears and 1 pinion.

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This paper describes a new reduction gear system with a special mechanism. The mechanism is so designed that a pinion having a slight angle of inclination to the input-output axis oscillates while engaged simultaneously with an internal gear having the same number of teeth as the pinion and an internal gear having one tooth less than the pinion. In the 1st report of this study, the tooth profiles and contact lines were theoretically analyzed to provide smooth engagement all gears. In the present report, an optimal designing system was developed and programmed to design the complicated structure of this reduction gear system. The designing system was tested by computerized calculations for a large number of designs.

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This paper describes a new reduction gear system with a special mechanism. In the present report, from a number of design examples obtained by the optimized automatic designing system for the reduction gear system with an inclined pinion, a reduction gear set of 1/60 reduction ratio was chosen and experimentally constructed. Its performance was evaluated in test operation. The efficiency and noise level were measured to assess the practical applicability of this gear system.

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With a view to regarding deep drawing as a new process for fabricating bottomless tubular elements, a deep drawing test was conducted with thick aluminum material. For the purpose of making the formed cup as high as possible, a combined-type processing of bore expanding and deep drawing was adopted, and the effects of the blank pre-bore diameter on the deep drawability and the formed cup height were investigated by means of an experimental approach. The deep drawability was improved by the combined processing, and the pre-bore diameter had the optimum value for the best deep drawability. Because of the improvement of deep drawability, the combined processing improved the cup height too.

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Recently magnetic fluid grinding has been developed as a new process which can remove materials in the finishing of ceramic balls fifty to one hundred times more rapidly than the conventional lapping process. The high removal rates occur when skidding motions are generated between balls and driving shaft. This paper offers a first attempt to model the mechanics of the process, to predict the onset of skidding motions. The model considers the force and moment equilibriums of the ball acted on by the forces and moments upon contacts with the driving shaft and other surfaces and by fluid drag moment. The friction coefficients relevant to the process and the viscosities of magnetic fluids containing abrasive grains were measured for use in the theory. As a result, it can be shown clearly that predictions of the skidding agree with measurements.

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A previous report proposed a computer-aided thread grinding method for generating helicoid without form dressing, using a standard-shaped grinding wheel independent of the final helicoid. The method uses a simple conical or plain wheel, without limitations of the diameter and base angle. The wheel axis is set three-dimensionally at the optimum computed angle of inclination. When the wheelthickness is large or the thread pitch is small, there is a risk of interference between the back of the wheel and helical surface opposing the helical surface being ground. When the grinding wheel is fed radially to the thread with a small thread pressure angle, there is also a risk of deformation of the helical surface generated. This report introduces a monitoring system to the original computer-aided thread grinding method, for protection against undesirable wheel interference, considering an axial displacement of the wheel and the maximum allowable displacement. The investigation shows that the monitoring system is effective to determine limits of thread dimensions without undesirable wheelinterference.

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A giant magnetostriction-type ultraprecision positioning device (GMUPD) was manufactured from newly developed giant magnetostriction materials with compositions of Tb_1-xDy_x(Fe_yMn_1-y)_n. The output power of them is several times and the displacement is several ten times that of PZT without a magnifier. An ultraprecision machine tool was developed with the present GMUPD. The workpiece can be fed at a rate of 0.1 mm/min or 600 mm/min and is cut by a turning diamond tool. The hard and brittle materials such as glass and ceramics were finished in the ductile mode, and surface roughness was obtained within several nanometers.

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A new robust control system of a welding robot equipped with a visual sensor to detect weld line is proposed. By the new method called continuous multivector connecting (CMVC) method, the precision of seam tracking and the robustness of the system against noise in images are markedly improved. Moreover, a new method to set scanning lines in the image, which is called successive scanning line setting method, is proposed in order to make the scanning line used to detect the weld line shorter and to save on the computer calculation time. As the result of seam-tracking experiments, the effectiveness of the proposed system was confirmed.

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