Three-dimensional nonlinear liquid motion in a rigid rectangular tank partially filled with liquid, in response to pitching excitation, is investigated. In the case that asymmetric modes are dominant, the nonlinear ordinary differential equations governing the liquid surface oscillation are derived by applying Galerkin's method to the basic equations. It is confirmed that vertical excitation causes parametric excitation. In addition, it is noted that pitching excitation also causes parametric excitation when the pitching axis does not intersect the vertical line passing the center of the tank bottom. An experiment was conducted using a model tank. Good agreement was found between the theoretical and experimental results.

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In this paper, a method of using the Rayleigh-Ritz approach is presented for the free vibratioilal frequency parameters and mode shapes for twisted and laminated thick cantilever plates. The method is based on the three-dimensional elasticity theory taking into account rotating inertia and shear deformation. The results show the effects of fiber orientation angle and thickness ratio on the free vibratory characteristics of the three-layered graphite/epoxy angle-ply plates, and these effects are discussed. The effects of the pre-twisted angle are also discussed.

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The equation of motion for the forced harmonic vibration of a viscoelastic oscillator is formulat-ed in terms of a fractional derivative in addition to ordinary derivatives. This equation of motion is exactly solved using the theory of fractional differential equations. An equivalent model of the viscoelastic oscillator is derived and used to estimate the responses of the oscillator. The validity of the equivalent model is proved by comparing the solutions of the exact model and the equivalent model for harmonic excitation. Damping property of the vibration of the viscoelastic oscillator is elucidated by the obtained responses.

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In this paper we present some results of a theoretical study of stationary random oscillations of an engine mounting system with motion-limiting stops. The dynamic model of the vehicle is reduced to a two degree-of-freedom system with stops which limits the relative motion of the engine body to the vehicle. The nonlinear impact force model is statistically reduced to a spring-damper model with equivalent linear coefficient of stiffness and damping between two masses. The response of the system to a roughness input of a roadway with Gaussian probability distribution is determined from the Fokker-Planck equation. Results are given for mean-squared level of the response. The accuracy of the theoretical approach is investigated by means of numerical simulations.

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Recently, microvibration control technology is rapidly becoming important in a number of fields including superfine technology in semiconductor manufacturing. In this study, we use an active 6 degrees of freedom (6-DOF) microvibration control device with 8 actuators and 6 sensors, with both feedforward control and model matching feedback control. Digital signal processors (DSPs) are used for effective MIMO control. In this paper, some experimental results of the system are shown to verify the control performance. We found that we could get much better vibration isolation perfor-mance and damping performance against impulse disturbances of floor than a sky-hook system by using absolute accelerations of the isolation table and the floor.

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Structural intensity measurement of a two-dimensional vibrational field is investigated numeri-cally and experimentally. A method that uses five accelerometers (5-point method) and a wave decomposition method are discussed. First, the error of the intensity measurement using the 5-point method is numerically discussed. Second, the wave decomposition method in atwo-dimensional field is applied to determine the vibrational field. The effectiveness of the wave decomposition method is numerically presented. Furthermore, these two methods are investigated experimentally. As a result, the structural intensity can be measured practically with high precision and the localization of source is possible using these methods. A technique for estimating the propagating power by measuring at a few points is also shown.

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Algebraic vector representation is in a broad sense a description system for the kinematics and kinetics of multirigid-body systems. This description system is extended to include geometric vectors using "coordinate unit vector matrices". Coordinate unit vector matrices are fundamental quantities used to connect geometric vectors and algebraic vectors. They are also used to define coordinate transformation matrices (rotation matrices) . The basis of this new description system is explained here. Practical examples on how to construct the constrained connections in Order-N-Algorithm are given.

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A systematic approach to analyze the deformation of a bendable thin object during its manipula-tion is presented. First, the manipulation process of a deformable object is analyzed with regard to how the object interacts with other objects around it. Secondly, deformation of the object is formulated based on the principle that the potential energy of the object reaches the minimum when its shape is stable under geometric and static constraints imposed on it. Thirdly, an algorithm to compute the shape of the deformed object is developed by applying a nonlinear programming technique. Some numerical examples are given which demonstrate the effectiveness of the computational algorithm. Finally, the results of simple experiments are reported, which show the validity of the proposed approach.

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A mathematical method of complex modal analysis and an experimental identification procedure of modal parameters for nonproportionally damped mechanical systems have been established thus far. However, the physical structure of complex modes of nonproportionally damped systems has not been thoroughly understood. This paper deals with a physical and graphical interpretation of complex modes in comparison with real modes of proportionally damped systems using the complex plane and the complex vector space. It is explained why the resonance vibration of nonproportional-ly damped systems does not exhibit the natural mode shape which appears in the free vibration of the same system. The condition that makes the resonance vibration mode approximately coincide with the natural mode shape of the free vibration is discussed.

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We present a characteristic improvement method for time historical analysis of stiff piecewise-linear system by adding mass. Hydraulic power lines with check valves and control valves for construction machinery exhibit piecewise-linear characteristics for hydraulic flow rate and spool stroke. The proposed method involves no time delay in determining the mass by considering both eigenvalue distortion of the system and time response. This method is useful for time historical analysis of hydraulic power lines including stiff piecewise-linear elements such as check valves, relief valves and control valves.

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We present a simple numerical method for minimizing the maximum eigenvalues of real-valued symmetric matrices, based on nonlinear differential equation solvers. First, we convert the minimiza-tion problem for the maximum eigenvalues, which is nondifferentiable, into a differentiable optimiza-tion problem by means of interior point methods. Second, making use of differential equation solvers, we present a simple method for solving the optimization problem. Our method does not require optimization techniques such as the Newton method. Lastly, we demonstrate the effectiveness of the algorithm through some simulation experiments.

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This paper concerns a stabilizing method for nonlinear time-delay systems. Generally, hunting frequently occurs in a system with a time-delay, and is difficult to prevent. The Smith compensator is well known as a method for stabilizing such systems. However, it is fairly difficult to apply this method in practice because of both the existence of nonlinearity and the difficulty of modelling for a real system. In particular, the identified error between controlled object and controller causes instability of the system. In this research, to prevent hunting, a new stabilization method is proposed. This method can prevent hunting, and reduce the steady-state error to zero by parameter adjustment. First, the stability analysis of nonlinear time-delay system is clarified using the circle theorem. Second, in order to analyze the robustness of the new compensator, its robust stability condition is derived for such control systems with a dead time and a saturated-type nonlinearity, and the stability margins under the identified errors of time lag are evaluated. Third, the new compensator is directly represented by a z transform, and its stabilization and dynamical characteristics are analyzed using the root locus method. From these studies, it is verified that the new stabilization method can be useful for general nonlinear time-delay control systems.

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The aim of the present study is to improve the dynamic behavior of the adaptive truss by considering the redundant kinematical degrees of freedom (DOFs) . It is assumed that the truss follows the prescribed path in its workspace. The motion planning problem with respect to vibration is formulated in a discrete form with a criterion function based on the strain energy of the adaptive truss. It is also shown that the proposed approach is applicable to a real model of the adaptive truss which takes account of the nodal offset, as well as an ideal model which is based on the ideal truss node assumption. Simulation studies are carried out for both ideal and real models of the adaptive truss. The effectiveness of the proposed approach on the vibration reduction is demonstrated.

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This paper extends the genetic algorithm with neutral mutations in oder to trace the complex optimal path in dynamic combinatorial optimization problems, by utilizing the unique characteristics of the method. That is to say, ( 1 ) the search performance does not deteriorate seriously if the population converges, and ( 2 ) directed evolution is observed after sufficient generations have passed. Considering the second characteristic to be crucial to these problems, we extend the GA to emphasize the development of the directions, by adding the temporal phenotype into the genotype as fixation operation and applying a stochastic learning automaton (SLA) on these fixed points to select one of them as the phenotype. To ensure the effectiveness of the proposed method, computer simulations are conducted. The results show that the proposed method generates appropriate automata and traces complex optimal paths of dynamic problems.

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In order to minimize the estimation error of the component mode synthesis, a method to amend the identified mode shape error is investigated. The method uses, (1) natural frequencies and mode shapes of the assembled structure, (2) an FEM model of parts which going to be modified. The results show that ( 1 ) lower mode seems to be more sensitive to the adjacent error of mode shapes, ( 2 ) the error is sufficientry corrected by this method, ( 3 ) simultaneously the joint forces are calculated.

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In this paper, we discuss simultaneous optimization of the configuration and assembly process of a bridge structure using a genetic algorithm. The fitness function used to optimize the structure has many local minima. We propose a hybrid GA based on the "local reproduction method". We examine the performance and characteristics of the simultaneous optimization by studying three cases: ( 1 ) optimization of final structural configuration without considering assembly process, ( 2 ) optimization of the assembly process only and ( 3 ) simultaneous optimization of the final structural configuration and the assembly process. We demonstrate the effect of the assembly process on the optimum topology of the bridge structure and the applicability of this GA to multi dimensional optimization problems.

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A system used to reconstruct 3D human movement from a stream of 2D input images is devel-oped. The system determines the 3D shape and motion of the human body by fitting a simple skeleton model to markers in the 2D image. The fitting is carried out using a nonlinear optimization approach. This optimization is essentially ill-conditioned because depth information cannot be obtained from the 2D image. In order to overcome this problem, the inverse analysis technique, which used the following four a priori information is applied. I Human body can be represented by versatile skeleton model. 2 Joint angles are limited. 3 Human motion is smooth. 4 Humans maintain balance in slow motion. We reconstructed human movement from real video images using this method in order to demonstrate its applicability.

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In this paper, we describe a procedure for estimating the impact force acting on a structural model of a space vehicle based on an inverse analysis techinique and experimental results obtained using this procedure. It is shown that the impact force can be determined by solving linear simultane-ous equations Ax= b, where A and b are given by the deconvolution procedure for Laplace transfor-mations of accelerometer and calibration data. Since the coefficient matrix A is ill-conditioned due to linear approximation error and measurement noise, tailoring of the singular value decomposition method (SVD) is necessary. For this purpose, two evaluation criteria are applied: the Akaike information criterion (AIC) and the penalty quadratic form. Using this evaluation, the effective rank of the matrix that gives the optimal estimate of the input has been determined.

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Tires do not generate side forces instantaneously upon slipping. Although the lag time strongly affects vehicle dynamic behavior, the effects of lag on yawing natural frequency and its damping ratio have not been expressd in formulas. To formulate that, we use two methods. One takes account of the lag by treating a first-order lag system, as a first-order lead system. The other is a method of eliminating high-order terms of s in the equation of motion. Comparison the two methods shows that the former method has better accuracy. Therefore we propose the former for modeling the behavior of automobiles taking account of the tire dynamic property.

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This paper concerns the process of selecting control characteristics such as reference models and control patterns in vehicle control systems. Signals may be received from many different sensors, including a video camera, laser radar and other devices, in the process of executing vehicle control. With conventional control methods, it is not easy to integrate signals from so many sensors. The program routine becomes extremely complicated in terms of the procedural representation. A new method for integrating the signals from many sensors is proposed here with the aim of resolving this structural problem. This method is analogous to the analytic hierarchy process (AHP). In this approach, AHP is regarded as a mapping function from the space of sensor signals to the space of system variables such as evaluation values and control patterns. Declarative knowledge based on pairwise comparisons of two signals is prepared for use in integrating sensor information. The results of a simulation analysis are presented to validate the effectiveness of the proposed system in generating the control targets of a vehicle control system.

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Using ER fluids, it is possible to directly interface electric signals and fluid power without the need for mechanical moving parts. This study is aimed at achieving practical applications of ER fluids to micro fluid power systems, in particular to micro control valves (micro ER valves). In this paper, a three-port micro ER valve (12 x 12 x 12 mm) is proposed and devised, which has two pairs of electrodes connected in series. Static and dynamic characteristics of the micro ER valve are examined. The valve can control a load pressure change of 0.35 MPa at an electric field strength of 5 kV/mm. Using the micro ER valve, a small-sized one link manipulator is driven. Also two types of three-port ER valves such as electrode-electrode type and orifice-electrode type are discussed with mathematical models.

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The purpose of this work is to develop a new automatic combustion control (ACC) system that increases the stability of steam flow from an associated boiler and reduces both CO and NOx concentrations in the exhaust gas discharged from a municipal refuse incinerator. A simulation model based on heat and material balances of the refuse material and exhaust gas was developed in order to design the control system for stabilizing steam flow rate. It was found that manipulation of the cooling air flow rate is important because it affects the gas mixing temperature and the 02, NO, and CO concentrations in the exhaust gas. The control system consists of a controller that stabilizes steam flow rate and inner temperature based on a simulation model, and a controller that uses fuzzy logic to regulate cooling air to reduce CO and NOx concentrations. This system was applied to an incineration plant in actual service. The results indicated good control performance because the CO and NOx concentrations were kept low, and fluctuations of the steam flow rate were reduced.

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Many active noise control (ANC) systems are based on feedforward (FF) control. However, recently, research on feedback (FB) ANC and two-degree-of-freedom (2DOF) ANC (hybrid ANC of FF and FB) has been conducted, because the importance of FB control has been recognized. We report 2DOF ANC aimed at improving control performance and focus on FB control. Since the system between a loudspeaker and an error microphone has a time-delay, we propose 2DOF-ANC with internal model control (IMC) in FB control. This IMC is known as a robust control design method especially for dead-time systems such that process control systems. Also, we discuss FB-ANC from the control theory point of view. It is shown that a howling canceller in ANC is equivalent to IMC, that the zeros which lie in the right half-plane in FB-ANC are closely related to the attenuation performance, and that the performance of FB-ANC can be predicted by investigating the sensitivity function. Moreover, a robust FB-ANC design method based on IMC is described and its effectiveness is demonstrated through a numerical example.

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Most of the studies on active noise control systems have used an open-loop feed-forward (FF) control system for the past several years. The FF control system requires a reference signal of a noise. Unless the reference signal has good coherence with a noise, the FF control system cannot achieve good control performance. In such a case, however, the closed-loop FB control system requiring no reference signal is effective. Although the key factor of the closed-loop control system is stability, the conventional adaptive algorithm cannot always assure the stability for systems the characteristics of which change. In fact several studies have been done on the FB control system in the last few years. However, little attention has been given to the robust stability. In this study we proposes a 2-degree-of-freedom (2DF) control system consisting of a FF compensator and a robust FB compensator. The FF compensator is designed using the conventional Filtered-X LMS algorithm and the robust FB compensator is designed using a new adaptive algorithm that is based on the LMS method. The advantage of this new algorithm is that it ensures the robust stability of a closed loop by adjusting the step size that corrects the weight of a FIR adaptive filter. This study confirms the validity of this 2DF control system by applying it to an experimental system that cannot be controlled well with the conventional FF control system.

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An optimal capacity planning method is proposed for energy supply systems including thermal storage tanks. Equipment capacities and utility maximum demands are determined so as to minimize the annual total cost in consideration of the system's operational strategy for energy demand varying hourly over a year. This optimization problem is a large-scale and complex one, and it is solved by a hierarchical optimization method on the basis of a penalty method. At the operational planning stage, an approximate method is applied since the problem includes a great number of unknown variables. The effectiveness of the proposed method is ascertained through a numerical study.

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A probabilistic approach to evaluating the performance of a stand-alone photovoltaic system with a storage battery is proposed. In consideration of probabilistic characteristics of insolation and electricity demand, the loss-of-load probability as well as the expected values of electric power generated by an auxiliary diesel generator and electric power disposed of are evaluated in relation to the surface area of the photovoltaic array, the capacity of the storage battery, and the capacity of the diesel generator. The probability density function of insolation for each hour is expressed using beta distributions. Instead of considering the hourly change in insolation as a stochastic process, we adopted two simplified models : in one the hourly insolation changes randomly, and in the other it changes deterministically. These models give extreme cases for the hourly change in insolation, from which the system performance for an actual change in insolation can be estimated by interpolation. A case study is carried out using measured data on insolation. The results obtained using this probabilistic approach are compared with those obtained using a deterministic approach, and the usefulness of the proposed approach is ascertained.

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An in-process milling tool monitoring system has been developed using a laser displacement sensor. The system reconstructs and displays the 3-D image of a milling tool and evaluates tool geometric failures via a hybrid laser sensor measurement method which uses displacement and intensity techniques simultaneously. The system is designed to compensate interruptions in the laser path brought about by chips and coolant drops present under actual cutting conditions. In experimen-tal tests, reconstructed 3-D geometrical tool images and intensity measurements enabled us to detect the size and the location of the chipped part and to determine the length of flank wear to an accuracy of 40 um.

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Various types of visual substitutes have been developed to support visually impaired people. However, no practical device which can obtain and transmit scenery information to users has been developed to date. We propose a method of transmitting three-dimensional scenery information such as height, width and distance of objects in a scene. The distance to an object is indicated by the volume of sounds. The horizontal position is indicated by stereo sounds. The vertical position is indicated by delivering frequency-modulated sounds corresponding to the vertical position in a time-divided scanning method. A compact device applying this transmitting method is developed. The device is composed of stereo cameras, a compact range finder for obtaining spatial information in real time, a compact scenery information transmitter, and a headphone. The validity of the device is confirmed by several basic scene recognition and walking experiments.

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We study Japanese words used in mimesis (onomatopoeia) to express movement. We explain movement or behavior of objects using the mode, speed, intensity, power, sound, condition, and continuation. In order to understand and explain the phenomena quantitatively, mimesis is used with movement verbs. We classify words that express movement and clarify that their usage is related to breathing and utterance.

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The natural color of five representative areas of the human face, the lip, brow, nose, left cheek and right cheek, is analyzed using HSV (hue, saturation, value) color space which is fitted with human color sense. From the relationships among the HSV parameters of these areas, it is found that the hue of the lip is not correlated with that of the other areas. This suggests that the hue of the lip in a virtual face image can be treated independently from other facial colors. Then a virtual facial color image is synthesized using the average of facial colors in HSV color space, determined from 64 males. On the basis of the difference in color of each pixel between the averaged face image and an individual one, a method for emphasizing the individual characteristics in facial color is proposed and the effectiveness of the method is demonstrated through sensory evaluation by paired comparison of enhanced virtual face images.

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Recently, fuzzy systems have been applied to various systems. However, due to lack of learning ability, the determination of most fuzzy rules and membership functions was made by human experts. In this paper, we propose a self-tuning fuzzy controller with a virus-evolutionary genetic algorithm (VEGA). This learning algorithm is based on the virus theory of evolution. VEGA realizes horizontal propagation and vertical inheritance of genetic information in a population. The main operator of VEGA is a reverse transcription operator which plays the roles of crossover and selection simultaneously. Furthermore, a transduction operator generates a substring to be transmitted. VEGA can reduce the number of fuzzy rules using the reverse transcription operator and the transduction operator. The effectiveness of the proposed method is demonstrated through the simulation of a cart-pole problem.

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In this paper we describe a distributed approach to the block stacking problem. Each block is assumed to be an autonomous mobile agent. Motion conflicts among the agents are resolved by means of ( 1 ) motivation calculation which is based on individual goal attainment request, and ( 2 ) promising destination determination by ANN-based behavior function which is trained using an evolutionary programming technique. The proposed method eliminates the necessity for a central planner and exhibits good scalability. Some experiments are carried out and the mechanism for cooperative goal attainment by multiagents is examined.

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Manipulation of micro objects has been studied experimentally using radiation force of ultra-sound. Alumina particles 16μm in diameter and suspended in water were trapped and agglomerated at every half wavelength in a standing wave field of 1.75 MHz. Slight changes in frequency brought about a lateral shift in the column of agglomerated particles. An L-shaped standing wave field agglomerated the particles at intersection points of grids which were the nodes of the sound pressure. Using orthogonal standing wave fields, the agglomerated particle changed its shape depending on the relative force ratio. Since the acoustic radiation force differs depending on the size, shape, density and compressibility of the particle, selective manipulation is possible. Alumina particles and nylon particles are separated by agglomerating them at nodes and antinodes, respectively. By applying focused traveling ultrasound on the trapped particles, only limited clusters of particles were transpor-ted, which demonstrated spatially selective manipulation.

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We discuss automation of a small-scale hydraulic shovel and its trajectory control. To move an end effector (grinder) along a desired trajectory, the flow rate of hydraulic oil to a cylinder of the shovel is controlled by a PID controller. To apply PID control in the present hydraulic system, the characteristics of this system have been analyzed and a simulation of this system has been designed. An actual system is devised and its system parameters are obtained by actual measurement. To show the effectiveness of the PID controller and the propriety of the system model, computer simulations and experiments are performed. These results of the simulations and experiments indicate that the PID trajectory control of robotic deburring using a hydraulic shovel is effective.

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A master-slave system is a tele-operating system consisting of a master manipulator which is directly manipulated by an operator, and a slave manipulator which tracks the master manipulator and actually works with objects. This system enables one to work in a severe environment, or to do large-/small-scale manipulation by enlargement/scalingdown of force or position. Recently, design methods based on advanced control theory are proposed in order to improve operation. However, in many cases, the controller does not guarantee stability of the system when communication between master and slave is disrupted. In this research, we try to stabilize the master and slave manipulators independently by controlling mechanical impedance of manipulators. Simultaneously, linearization and decoupling of manipulator dynamics can be achieved. Then we design a main controller, which allows the system to work as a master-slave system, by using μ-synthesis. The stability of the system and the control performance are guaranteed even under the existence of modeling error.

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In order to realize a self-standing walking robot, it is necessary to reduce the degree of freedom of the locomotive mechanism, because the total weight of the walking robot is proportional to the number of control devices. The author proposes the one-degree-of-freedom mechanism which is called the YT mechanism, and applies the mechanism to a quadrupedal robot which realizes one-directional walking by the trot gait. This paper presents a self-standing quadrupedal robot equipped with the YT mechanism and the omnidirectional mechanism which changes the stepping forward position and is similar to the steering wheel of an automobile. Experimental results show the advantages of the system.

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This paper describes the development of an explosion-proof pneumatic robot for use in the chemical or oil industry. For such a robot, the electric part must be completely separated from the combustible gas. In our study, a pneumatic robot is designed in which the robot controller is linked with an actuator by a long pneumatic tube in order to prevent explosion. Then, the robot system is modeled as a nonlinear time-delay system as used in the aerodynamic analyses, and the validity of this model is confirmed through simulation and experimental studies. However, the robot manipula-tor will generate hunting due to the time lag of pneumatic pressure signals. Thus, a two-step PID controller is proposed, which not only prevents hunting but also reduces the steady-state error to zero. The effectiveness of this PID controller has been verified through simulation and experiments.
Moreover, the stability margins for the pneumatic tube length are evaluated.

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In this paper, we describe a robot system which can track a given path on a 3D terrain using the inclination of the robot in real time. We designed a model of 3D terrain between two ridges based on some measured shape, and made a desired path on the lowest portion of the field furrow. We newly designed a mobile robot system which can track the path using the a method proposed in the second report. The path tracking control of this robot system is carried out using a rolling angle and change of a rolling angle of the robot. The rolling angle is measured using an inclination sensor installed on the robot when pitching angle is controlled at zero. The pitching angle control is carried out by controlling a linear actuator installed in the robot. Path tracking by the newly designed robot system was shown together with some experimental results.

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The aim of the present study is to develop a new structure of a mechanical seal under high-speed and low-temperature conditions. The existing seal is a floating-ring seal for use in low-temperature compressors or turbines such as liquid natural gas. However, this seal requires expensive supporting equipment in order to maintain differential pressure between seal fluid and carrying gas. We present a new structure of a mechanical seal and confirm by experiments that this seal has acceptable seal-performance at high speed and can be use when the differential pressure loaded a seal face repeats under positive and negative value, and this seal keeps reliability under emergency conditions of low temperature turbo-machinerys.

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The aim of this research is to establish a method for calculating the rotational transmission error of Rzeppa constant-velocity universal joints used in automotive drive shafts. We had already analyzed constant-velocity joint with one ball, and had calculated the phase deviation at the point of contact between the ball and each groove of the input and output shafts. In this paper, actual constant-velocity joint with plural balls is discussed. Due to the thrust force from input to output shaft grooves through the balls, the ball-cage is forced to incline. The cage inclination angle is limited by the condition that the ball with the most advanced phase contacts the driving groove surface and simultaneously the most delayed ball contacts the coasting groove surface. Under this condition, the phase deviation of the most advanced ball groove coincides with the transmission error. The accuracy of this procedure is confirmed by comparison of the calculated values and the result of an experimental evaluation of transmission error.

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In order to clarify the microscopic wear mechanism of CVD TiN coatings, the wear process was observed in-situ during sliding in a SEM tribosystem. Four wear modes were observed for CVD TiN coatings with the thickness of 1.6 : ploughing, powder formation, flake formation and coating delamination. On the other hand, only two wear modes were observed for CVD TiN coatings with the thicknesses of 7.5 and 12 1.tm : powder formation and flake formation. Wear modes varied from ploughing to powder formation and coating delamination to flake formation for CVD TiN coatings with the thickness of 1.6 ;.tm with increasing number of friction cycles. The number of transition friction cycles of the wear mode decreased with the increase of load. It was considered that powder formation occurred due to the chipping of the asperity tips on the surface, and that flake formation occurred due to the surface cracks which were generated by large tensile stress at the tail region of the contact area.

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In this study, we propose a new design method for maximizing the dynamic stiffness of a hydrostatic air bearing spindle. In order to decrease the rms value of dynamic displacement of the spindle against external disturbance forces, we design a hydrostatic air bearing spindle using the following procedure. First, we determine the basic dimension and supply pressure. Next, we determine the radius of radial bearing so as to minimize the static displacement at the point where the external force is imposed. Then, the non-dimensional static stiffness is determined so as to minimize the rms value of the response when the dynamic external force is applied. Finally, we determine the inside groove configuration which provides the static stiffness and the maximum damping ratio at the spindle natural frequency.

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Fundamental concepts for analyzing the characteristics of slipper bearings operating in swash plate type axial piston pumps and motors are developed. On the basis of the calculated bearing characteristics, the generation mechanism of load-carrying capacity of the overclamped slipper bearing is clarified. The attitudes, i. e. floating height and tilt angle, of the slipper bearing are calculated under the quasi-static condition, assuming that the contributions of hydrodynamic oil film force and oil shearing force due to relative sliding motion of the slipper bearing can be neglected. It is also suggested that wear at the periphery of the bearing surface, which may be due to contacts of the bearing with the swash plate, is essential for successful bearing operation.

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The performance of slipper bearings in the swash plate type axial piston pump/motor is analyzed theoretically under quasi-static operation conditions. The effect of the nonflatness of the bearing surface due to wear at the bearing periphery, which may be caused by contact of the bearing with swash plate during operation of the device, is taken into account as an essential factor for successful bearing operation. The attitudes, such as floating height and tilt angle, of the slipper bearing are calculated for given operation conditions, and the results obtained are presented in a characteristic diagram for bearing operation. It is also shown that thermal distortion of the bearing pad may possibly be a key factor for stable bearing operation.

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With the background that plastic waste disposal is causing a great environmental problem, a biodegradable plastic was developed, and a gear was manufactured using this plastic. The strength and rigidity of the plastic were improved by adding 30% talc to an aliphatic polyester which was chemically synthesized from a glycol and an aliphatic dicarboxylic acid. Then, with the operation tests carried out for the plastic gears, characteristics such as operating life, tooth wear, and change in tooth profile were investigated. Furthermore, in order to compare this gear with a polyacetal gear with a lot of practical results, investigations were carried out for the practical application of this plastic gear.

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This study describes the relation between cutting force and surface roughness of a drilled hole wall in small-diameter drilling of GFRP for a printed wiring board. The surface of the drilled hole wall is observed by SEM, and the surface roughness along the feed direction is measured at various rotation angles of the drilled hole. Moreover, the thrust force is measured in order to investigate the characteristics of small-diameter drilling of GFRP. It is found that there are static components and dynamic components in the thrust force. It is shown that the dynamic components are related to the surface roughness of the drilled hole wall.

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A CAM system which is based on simulating the servo data generation method of a copy milling machine was developed. In this system, the tool path data can be directly calculated using the coordinates of the contact point between the defined shape and the imaginary stylus, without preceding processes of offset surface generation and tool interference checking. For application of this algorithm to the model which is expressed by the boundary representation method, the algorithm has been modified slightly. As the contact point is regarded as the nearest point to the center of the imaginary stylus, and which is on the model surface, all intervals between the center of the imaginary stylus and the constructing surfaces which are close to it are calculated. The point which has the shortest interval is the representative nearest point of the model data and the contact point in the case that the interval is equal to the radius of the tool. A roughing tool path which is constituted with imaginary block and a spiral finishing tool path which tool feed with smoothly cutting have been developed using the algorithm. Tool path simulations and cutting tests show that the developed CAM system was able to generate appropriate CL data with high accuracy and reliability.

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This paper presents a new method of milling tool path generation for the shortest and least directional change. In this study a path is regarded as a string of successive passing points distributed on the surfaces of a workpiece to be machined. The problem definition is how to get the optimal path and the solver mechanism is developed based on a new algorithm similar to the Partially Mapped Crossover method in Genetic Algorithm. The experiments have been applied to the tool path generation of a telephone model. The experimental results support the validity and the efficiency of the method developed.

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One of the machining errors is caused by thermal deformation of a machine tool. Thermal deformation is caused not only by inner heat sources such as bearings, motors and so on, but also by outer heat sources such as the room temperature variation in a machine shop. In general, when a unit power at the inner heat source is generated pulsewise or stepwise, the basic thermal deformation can be obtained analytically and experimentally. When the heating power in the source could be measured, it seems that the thermal deformation can be estimated using the basic deformation and the measured power. Therefore, the equivalent position of the inner heat source, the power generated at the source, the thermal deformation caused by the power, and so on are investigated in this study. As the results of this study, it is clarified that the thermal deformation can be estimated by measuring the temperature of the machine tool structure and that around it.

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