This paper describes the modeling and the numerical simulation to investigate the mechanism of the nonlinear vibration responses of the tank when the beam-type and the oval-type vibrations are coupled. The oval-type vibration accompanies the out-of-plane deformation of the tank sidewall under large input acceleration excitations. So, it is considered that the geometrical nonlinearity due to the oval-type vibrations is the main reason why the vibration responses of the tank are nonlinear. Furthermore, an equivalent nonlinear single-degree-of-freedom (SDOF) system model is proposed to understand the nonlinear vibration responses of the tank, assuming that its flexural rigidity depends on the amplitude displacement of the oval-type vibration. The numerical simulation of the frequency sweep test using this model shows that the resonance frequency decreases as the oval-type vibration becomes larger, suggesting that the proposed model can be effective as one of theories to explain the nonlinear vibration responses of a cylindrical water storage tank.

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Eigenvalue analysis is necessary to determine the stability of an axially moving belt. It is, however, complicated and difficult to calculate eigenvalues and eigenmodes analytically. In this report, a finite element eigenvalue analysis is applied to this problem. The axially moving belt is modeled as a tensioned traveling beam. The equation of motion is discretized to a finite element model using the weighted residual method, and cast in first-order form for eigenvalue analysis. Calculated complex eigenvalues are in good agreement with the exact ones for simply supported belt. Critical transport speed, at which zero eigenvalues exist, can be determined as a point where the determinant of the stiffness matrix becomes zero. Furthermore, the effect of damping, which is proportional to transverse velocity of a belt, is examined, and it shows that this damping has no effect on the critical speed.

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This paper addresses to develop a novel strategy to relax the adhesion forces for picking and placing operation in a micro range. In a micro range, the attracting forces such as the van der Waals, capillary, and electrostatic forces become dominating due to a scaling effect. The attractive forces cause the adhesion between the object and the endeffector. Therefore, it is hard to manipulate an object in a micro range. This paper shows that when an oscillating endeffector approaches to an object, the adhesion between the object and the oscillating endeffector can be reduced. Also, based on the experimental analysis, we clarify the relation between the oscillation and the pushing amount of the endeffector on the object, where the adhesion force can be released effectively. Using this relaxation method and the relation, we develop a strategy for picking and placing operation in a micro range. This strategy provides an accurate manipulation. Some experimental results show the effectiveness of this approach.

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An elevator rope for a high-rise building is excited forcibly by the displacement of the building caused by earthquakes and wind forces. In this paper, experiments of free vibration and forced vibration of the rope are presented for obtaining the natural frequency and the damping coefficient of the rope. And experiments of forced vibration of the rope whose length varies with time due to the up-and-down movement of the cage are presented. Finite difference analyses of the rope vibration are also performed by considering the time-varying length of the rope based on the assumption that the movement velocity is constant. The calculated results of the finite difference analyses are in fairly good agreement with that of the experimental results.

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This study employs Linear Quadratic (LQ) control as model-based control theory for a lane tracking controller of a two-wheeled vehicle. By examining simple computer simulation, lane tracking controller by using the LQ control shows a good lane tracking performance. The LQ controller makes it possible to realize stable lane tracking control by evaluating only directional (lateral motion) stability, while conventional model-free control theory for lane tracking control such as Proportional-Derivative (PD) control has to consider not only directional stability, but also trim (rolling motion) stability. In addition, evaluating the lateral displacement at the virtual point ahead of the vehicle, which is defined by synthesizing the lateral displacement at the center of gravity and the yawing angle, copes with both lane tracking performance and convergence. Adding a Kalman filter as a state estimator to the above-mentioned LQ controller, i.e. an LQG controller, the lane tracking performance is also realized using estimated values under the steering torque disturbance.

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This paper proposes a basic method for constructing a formation flight based on Hill's equations of motion. It proposes a trajectory design of minimum fuel consumption for spacecraft relative position change by two impulses. We have already considered the case where the formation size is enlarged. Focusing on the case of reducing the formation size, we consider here a problem to obtain the time and the phase of the second impulse when the phase of the first impulse is given. As is different from the preceding case, the optimality condition becomes more complicated in this case. The procedure to obtain the optimal solution is given, and the results show that the optimality condition in the preceding report covers the large part of the simulation cases, while the new optimality condition is valid in some cases.

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A semi-active sloshing suppression control method for the contained liquid in the closed vessel is presented. The presented method uses the air spring effect of the gas chamber on the liquid surface, when the closed vessel is divided into two sectors with the vertical bulkhead in it so as to allows communication between two sectors at the lower part of the vessel. When the valve that is provided at the bulkhead between two gas chambers closes, the spring effect of the gas chamber arises. On the contrary, when the valve opens, the spring effect of the gas chamber diminishes. Switching algorithm of the valve operation makes sloshing response to decrease. The effectiveness of the presented semi-active sloshing suppression control method is examined with numerical simulations and the scaled model experiment. As the result, the presented method is effective to suppress the sloshing while the consuming energy to control the valve is small.

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This paper describes the motion control techniques of rotary tables for 5-axis machining centers. Especially, in the machining of complex shapes such as impellers, three translational axes and two rotary ones are simultaneously controlled. A tilting rotary table powered by the worm gear is generally applied as the rotary axes for the 5-axis machining centers, and various causes of inaccuracy exist in the rotary axes. In this study, the causes of inaccuracy are investigated by the experiments and simulations. As the result, it is clarified that the main causes of inaccuracy : servo response, fluctuation of rotational velocity, backlash and the signal delay of rotary encoder. Motor torque saturation of the rotary axis also yields a problem. Based upon the investigated results, some compensators for the problems were proposed. In order to confirm the effectiveness of the proposed compensators, the compensators were applied to an experimental set-up including a rotary axis. As the results, it is clarified that the proposed compensators can much improve the synchronous accuracy.

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This paper deals with the study of size segregation of particles where the difference in size causes characteristic movement of particles inner granular media according to the induced vibration. In this study, segregation of particles due to the difference in size is simulated using Cellular Automata. A connected lattice automaton is introduced in the model, so that the variation of particle sizes as well as geometrical arrangement between particles can be represented. The present Cellular Automata model can produce various patterns such as segregation, the heaping and convective pattern of particles which are observed in physical experiments. Furthermore, completion time of segregation is measured in each simulation which depends on the magnitude and frequency of excitation. Experimental investigations depicted that segregation time is reduced according to the increment of excitation amplitude, which correspond well with numerical results by Cellular Automata model.

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Recent advances in digital signal processors have facilitated the development of active noise control (ANC) technology where the various kinds of researches as well as applications have been studied. In general, the sound waves propagate spherically in three dimensional space. Simply constituting SISO system using ordinary loudspeaker as a control source may cause interfered sound field with both attenuated and amplified nodes exist. By placing number of microphones and control sources can improve the range of quiet zone and many researches have been dedicated to this end, yet still limitations on implementation and cost cannot be neglected. On the other hand, the recent development of high-directional loudspeakers based on new sound production theory known as 'parametric array effect' has allowed sound transmission to a narrow range of acoustic space like 'spotlight'. This peculiar characteristic can be implemented as one measure for improving active noise control scheme controlling acoustic field locally without adversely influencing vicinal space. In the present study, a new approach for active control of sound in free space is developed using high directional parametric loudspeaker as a control source. Experiments are performed for the active control of noise generated by single source located in space, where the noise is attenuated by a control source at error microphone which evaluates sound level. Both normal and the parametric loudspeakers are tested as control sources and results are compared based on measurement of interfered sound field around the evaluation point. It is known that the suggested ANC system can mitigate sound locally but cause less influence on sound field in circumferential space.

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Visual acuity is one of the most important functions of human eye. The Kinetic Visual Acuity (KVA) is movement-vision that is important for driving a car safely. Therefore, on the traffic safety education, not only needed to examine static visual acuity, but also checking kinetic visual acuity is required for aged people. Up to now, kinetic visual acuity equipments have some problems : (I) The reaction time related to kinetic visual acuity contains simple reaction time. Therefore, the measured value of kinetic visual acuity is not exact. (2) Mesopic visual acuity cannot be measured. In this study, we redefined the kinetic visual acuity and develop a new visual acuity equipment with multifunction based on the new definition of the kinetic visual acuity.

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Sewer pipes over 380 000 kilometers in total are existed under the ground in Japan. However, worn pipes have been increased and a number of subsidences of a ground caused by the collapse were occurred. Recently, the inspection of the pipe is executed by the moving cart with CCD camera. Currently human inspector judges the condition of the pipe by the images recorded by the CCD camera. It should be noted that the judgment by the human causes the individual variation since it depends on the person's sense. Quantitative measurement is required. In this paper, the 3D quantitative measurement system for a sewer pipe is introduced. Two parallel laser sheets are projected from the inside of the pipe and the two circular laser streaks appeared on the inside surface of the pipe are recorded by the CCD. The measurement of the cross-section is established by analyzing the recorded streaks. Amount of displacement between two circular streaks are used to detect the tilt of the system against the axis of the pipe. The pipe is reconstructed by stacking of the cross-sections on considering the moved distance and the tilt of the robot. The automatic calibration using a liquid crystal display is also introduced in this paper. The calibration method reduces the lens distortion of a wide-angle lens and a high accurate measurement is established. Experimental result shows the feasibility of the system.

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The ultrasonic TOF (Time-of-flight) ranging system is today the most common sensing system employed in indoor mobile robotic systems, primary due to the ready availability of low-cost systems, their small size, simple circuits, and their ease of interfacing with computers. TOF ranging systems measure the round-trip time required for a pulse of emitted energy to travel to a reflecting object, then echo back to a receiver. However, ultrasonic TOF ranging systems tend to neglect minute reflected waves below the threshold level. In this paper, we propose a novel approach to utilize the minute reflected waves by integrating the reflected waves. It is implemented using a transducer with scanning system, and has a great ability of finding the travelable area for a robot in environments in which the distance cannot be obtained precisely. The proposed system is constructed by simple way so as to improve the utility value of sonar. The validity of the proposed method is investigated by applying this method to autonomous mobile robot in various environments such as environment with multiple obstacles, in the end of the hall, and so on.

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A contour following control method based on dynamic parametrization for redundant robots is proposed in this paper. The proposed method makes a redundant robot follow the desired contour in work space with executing a subtask whose objective is to maximize a cost function, such as distance between the robot and an obstacle. The method also guarantees the lower limit of the cost function which implies that the performance of the subtask is able to be evaluated. Results of numerical simulations show the effectiveness of the proposed method.

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In this paper. we propose a robot teaching method for industrial manipulators. It enables novice human operators to teach “good” robot motions in a short period of time. First in this method, a human operator makes a robot manipulator sweep a volume by its bodies. The manipulator is equipped with a force sensor on its wrist and damping-controlled ; the operator can move it freely by grasping its end-effector. The swept volume stands for (a part of) the manipulator's free space, because the manipulator has passed through the volume without collisions. Next, the obtained swept volume is used by a motion planner to generate a well-optimized path of the manipulator automatically. Finally, the planned motion is executed by the manipulator. Even non-skilled operators can generate robot motions with short cycle time by doing the above procedure. The effectiveness of our method was successfully demonstrated in teaching experiments for a comparison with other conventional methods.

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The objective of this study is to analyze contact conditions of the posterior stabilizer (PS) type knee prosthesis at level walking and ascending stairs using a 3D mathematical model. Our 3D model made it possible to reproduce comprehensive knee motion, since it included not only the tibiofemoral joint but also the patellofemoral joint. In the model, the forces of major muscles, ligaments and tendons were all taken into account. If we input the data of muscle forces, floor reaction forces and knee flexion angles into the model, then we could determine such variables as the relative positions between the two components, contact points and stresses between the articulating surfaces and valusvalgus and internal-external rotation angles between the tibio-femoral components. Simulation was conducted and the following results were introduced. On the patellofemoral joint, the maximum contact stress at ascending stairs was 2 times higher that that at level walking. On the tibiofemoral joint, the maximum contact stress at ascending stairs was 1.7 times higher that that at level walking. The post/cam contact occurred only at ascending stairs and the contact stress reached as much as 67.1 MPa.

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The paper presents characteristics of action and reaction force in the chair drive mechanism. When axis of the rotation link approaches horizontally in the legless chair state, tensile force acting in the drive wire increases rapidly. Therefore, big power actuator is required at early lifting stage. A few solutions were considered to reduce the peak necessary drive force. The first, rigidity of wire is sufficiently increased so that there may be completely no elongation. The second, the peak is canceled by addition of boost effect of gas spring. The third, axis of the rotation link is constrained by landing stopper, before the link is achieved in a horizontal position. The actuator with function of irreversible motion must be used the mechanism, because the pullback force is needed near standing position. The experimental results agree approximately with the theoretical analysis, and then theoretical considerations could be proved for its validity.

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Aluminum beverage bottles with a screw top are containers that can be resealed again and again as well as PET bottles. They have the advantage that enables to recycle compared with PET bottles. Two kinds of bottle outlets 28 mm and 38 mm in diameter have been putting on Japanese markets recent years to meet drinking custom trend of consumers. However, some consumers feel that the 28 mm opening is too small and the 38 mm opening is too large. To improve drinking ease of aluminum beverage bottles, three kinds of bottle outlets (28, 33 and 38 mm) have been investigated based on a method of Kansei engineering (semantic differentials method and factor analysis), and on the numerical fluid dynamics analysis. Statistical analysis results of questionnaire have shown that the 33 mm opening is best for examinees. The factor analysis results of questionnaire have shown that drinking feeling is affected by two common factors of the flow amount and the adjustability. In addition, a process that examinees drink beverage from an aluminum bottle is simulated by the fluid dynamics analysis. It is found that examinees usually try to realize the ideal condition of flow rate by adjusting the inclination angle of the bottle.

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In order to develop a better computer simulation program that can predict a shaved form of a work gear after plunge cut shaving, the authors applied an estimation of a transmission error of the gear to be shaved in the process. In the present paper, the transmission error is calculated from forces acts on tooth flanks of the shaved gear and the shaving cutter. The forces are estimated from contact stresses which are calculated with the equation for circular contact in Hertzian contact theory. As a result, calculated shaved forms show better agreement with measured one.

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This study deals with oil film seals (floating bush seals) under high-speed reciprocating motion in hydraulic equipments. Two numerical methods of Elastohydrodynamic lubrication for seal performance are presented. One method is an approximate method on the assumption that profile of seal clearance is straight one. In another method, compliance matrix of floating ring and hydrodynamic analysis based on the finite element method are used. Effects of hydraulic pressure, size of ring, materials of ring and initial clearance on seal performance (minimum oil film thickness and oil leakage rate) are presented. It is shown that the oil leakage rate decrease under high hydraulic pressure owing to contractile displacement of ring. And it is found that seal gap become null in high-speed condition, caused by negative hydrodynamic pressure generated in seal clearance. Also, it is shown that rings with step on inner face are useful to hold clearance under high-speed condition.

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In the 1st report, numerical analysis for oil film seal considering elastic deformation of rings was presented. It was shown that the elastic deformation of ring has an important effect on seal performance under the condition of high hydraulic pressure and large-sized rings. And it was found that seal gap become null in high-speed condition, caused by negative hydrodynamic pressure. In this study, experimental tests have been performed using rings made of polyamid resin in order to examine the validity of the numerical analysis. Measured leakage rates are decreased with the increase of hydraulic pressure in high pressure zone. Measured results of oil leakage rate are confirmed to be in good agreement with predicted ones considering the elastic deformation and thermal expansion of rings Also, it is confirmed that rings with step on inner face have an effect on holding clearance as predicted.

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To ensure the reliability and durability of hard disk drives, molecularly thin polymeric liquid films of perfluoropolyether (PFPE) coated on the disk surfaces possess a mixed structure consisting of molecules bonded to the disk surfaces and non-bonded mobile molecules. Aiming to clarify the influence of film composition (mobile/bonded) on tribological performance, we measured friction properties of two types of 2-nm-thick PFPE films (functional Zdo12000 and nonfunctional Z03) under lightly loaded (loading force : 0-1 mN) and quasi-static (low rotational speed : 2.1 mm/s) conditions as a function of elapsed time. The friction force of Z03 remained unchanged with time and increased linearly with loading force as described by Amontons' law. In contrast, induced by the development of the molecules' bonding in time, the friction force of Zdo12000 increased and exhibited a nonlinear increase with loading force as time proceeded. The nonlinear friction-load relationship of Zdo12000 in the equilibrium state was well characterized by the Johnson-Kendall-Roberts model.

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Diamond-Like Carbon film (DLC film) shows excellent tribological properties. However, due to its brittleness, conventional DLC coating can not be applied to a tribological coating on soft substrates. To overcome this problem, a segment-structured DLC (S-DLC) coating has been suggested. In this technique, DLC film is divided into small segments by grooves. On the other hand, requirement for tribological application of DLC film under lubricant condition. However, sufficient research efforts have not been devoted toward S-DLC under lubricant condition. In this study, lubricated S-DLC film, which composed of S-DLC with grooves filled with grease, was investigated. Tribological properties of lubricated S-DLC were evaluated for various types of grease and segment shapes. It was shown that excellent tribological properties were obtained by combination of low viscosity grease and S-DLC coating with large size segments and narrow grooves.

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This study proposes the combination of some hydrodynamic pressure shapes formed on the end or the annular surface of oil impregnated sintered porous bearing as a DC spindle motor's bearing system. Hydro Wave Bearing or Pump In as a thrust hydrodynamic shape, and Herringbone, Three Lobed Type or Sleeve as a radial hydrodynamic shape were proposed, and the total of six kinds of combinations was produced as thrust-radial coupled bearing. It examines to optimize the hydrodynamic shape combination experimentally as thrust-radial coupled bearing by measuring the lubrication characteristics. Quantitative floatation level of unit time and shaft whirling, such as the lubrication characteristics, were examined experimentally. As experimental results, it was confirmed that quantitative floatation level leading to life-longevity of bearing and low shaft whirling were achieved by hydrodynamic pressure interaction of thrust-radial coupled bearing.

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The theoretical and experimental study is carried out to investigate the squeeze film phenomena between a cylindrical porous block and an impermeable rigid plate. The porous rubber block is rotated and oscillated sinusoidally in the direction perpendicular to its surface, whereas the rigid plate is stationary. The deformation of the porous rubber block is evaluated with an approximate method, in which the cylindrical rubber block is simplified to be a set of concentric rings and each ring is assumed to be deformed only axially and independently from the neighboring ones. The each ring can be replaced a three-element viscoelastic model. The theoretical result agrees approximately with the experimental result and both results show that a rotational motion slightly decreases the squeeze film pressure and force due to a centrifugal force mainly acting on the film. The effects of the permeability of the porous matrix, the velocity slip at the porous surface and the surface deformation of the porous matrix on the squeeze film characteristics are made clear by comparing the results for the squeeze film between the porous rubber surface and the impermeable rigid surface with those between a pair of impermeable rigid plates.

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Rubber products are widely used as a material of various engineering components and many of these products are mass-produced with injection molding or compression molding. In those production methods the peeling property of rubber material from the metal molds after rubber molding affects on the production efficiency. However, the adhesion property which is deeply related with peeling property is not clarified enough. In this study, we performed the adhesion test between rubber plates and steel balls and try to clarify the adhesion property. From the result of experiment, pull-off force between rubber and steel has good correlation with the polar component of the work of adhesion which relates to the functional group on the surface of materials. So it is assumed that the primordial cause of the adhesion between rubber and steel is the electrical interaction between surfaces. Based on this idea, we suggest a technique to decrease the pull-off force between rubber and steel by applying electric field on the rubber. As a result of experiment, the pull-off force between acrylic rubber and stainless steel is decreased by 50%.

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The objective of the research is to establish mathematical models representing the kinematic motion deviations of the machine tools on the basis of the geometric tolerances of the components, and to apply the models to theoretical analysis of the kinematic motion deviations of the machine tools. Mathematical models are proposed to represent the kinematic motion deviations of the linear tables of the machine tools. The proposed models give the relationships between the geometric tolerances of the guide-ways of the components and the kinematic motion deviations of the linear tables. The models of the linear tables are combined to represent the whole machine tools to represent the positional deviations of the tools against the workpieces. The developed models are applied to the analysis of the kinematic motion deviations of the machine tools, aiming at clarifying the effects of the geometric deviations of the components on the kinematic motion deviations between the tools and the workpieces.

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In shearing, the crack occurrence may be controlled by elevating a hydrostatic pressure of a material near tool cutting edges. Since hydrostatic pressure is affected by constraint of material, the influence of constraint on shearing characteristics was investigated by the experiments and FEM analysis. The results of this study clarified the followings. The smooth sheared surface of blanked product is increased by constraint of material. When the material is tightly constrained, crack earlier occurs at the material near punch cutting edge than that of die cutting edge. This tendency agrees with the magnitude of hydrostatic pressure at punch and die cutting edges. It is confirmed that the constraint of material prevents cracks by adequate controlling of material flow aiming the hydrostatic pressure rise. It is also confirmed that the dishing of product is affected by the condition of the constraint.

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The force acting on workpiece surface generated by magnetic particle brush is important factor which affects micro cutting behavior of abrasives as machining characteristics in magnetic abrasive finishing. In this report, the normal force is measured during finishing, and intensity change of the force is found when magnetic particle is used in adsorption at the end of magnetic pole. Measured normal force indicates a little decrease continuously after the drastic increase at the start of finishing motion, although the intensity of magnetic field is constant. The mechanism of normal force intensity change is described as the transmission of compressive force caused by cutting force in the center area of magnetic particle brush. The theory can explain why friction coefficient influences the force intensity change. The intensity increase suggests active cutting of abrasives supported by magnetic particles, and is regarded to make effective results in rough surface finishing.

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Recently, there has been strong demand for replacing the loose-abrasive machining with fixed-abrasive polishing because of the large amount of the waste slurry. However, the conventional fixed-abrasive polishing has the problem such as low finishing efficiency. To overcome the problem, in the previous report, a structure-controlled fixed-abrasive pad which consists of a fixed-abrasive layer and an abrasive holding layer was introduced for finishing optical glass. And then the finishing efficiency of the developed pad was higher than that of the conventional pad, but on the other hand, the factors which effects on the finishing efficiency were not clear. So, this paper deals with the effects of the pad surface condition which was considered as one of the influential factors on the processing properties. As a result, the factors which effects on the finishing efficiency was clarified. In addition, high finishing efficiency was able to be achieved by optimizing the pad surface condition.

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A design navigation system that combines design knowledge and suitable design tool has been developed. The system enables a designer to shorten the design time by guiding the designer through a series of defined design steps. Each step uses five sources of information and know-how : input, output, references, tools and memos. Designers are guided through the entire design process-one step at time. The system has three key features : (1) it uses a clear step-by-step design process combined with design knowledge and design tools, (2) it guides designers by showing the design process in a work breakdown structure (WBS), and (3) the designer can search for necessary knowledge during the design process. The system shortens design time and improves design reliability. The effectiveness of the system was demonstrated by applying it to a piston design process.

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