Driving torque of rotating machinery, such as automobile engines, changes periorically. As a result, torsional vibrations occur and cause serious noise and vibration problems. In this study, the dynamic characterisitics of centrifugal pendulum vibration absorbers restraining torsional vibration is investigated both theoretically and experimentally. In the theoretical analysis, the nonlinear characteristics are taken into consideration under the assumption of large amplitude vibration of pendulum. It is clarified that the centrifugal pendulum, although it has remarkable effects on suppressing harmonic vibration, induces large amplitude harmonic vibrations, second and third superharmonic resonances, and unstable vibrations of harmonic type. We propose various methods to suppress these secondarily induced vibrations and show that it is possible to suppress torisional vibrations to substantially zero amplitude in all through the rotational speed ranges.

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Vibration characteristics of a structure on which unbalanced rigid rotors are operated are investigated experimentally and analytically. Rotor speeds cannot exceed a critical speed when drive power to each rotor is not enough. Further running speeds of rotors are entrained into a single speed just below the critical speed and phases of rotor unbalance are locked so as to excite the structure violently. On the other hand, two or three rotors operated by sufficient power supplies can run above the critical speed and unbalance forces cancel each other, that is, vibration is very small. When four rotors are operated with enough power supplies, the phases of rotor unbalance are not locked for speeds above a critical speed.

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Knowing the vibrational behaviour of tractors is necessary to modify driving safety and comfort. The purpose of this paper is to understand vibration phenomena using simulation models, which include the peculiar characters of tractors. By the experimental results from static tests, the model of the isolation rubber is obtained. The tire lugs, which are taken as the excitation source, excite the tractor at specific frequencies due to their profiles. Using a quarter and a half-size model about the body, we determine the model parameters based on the commercial lists. We calculate the acceleration responses accelerating from zero to 16 m/s and decelerating inversely. From calculations about accelerating, it is found that the resonance phenomena continue. Because the stopper part of the rubber, where the cabin connects to the frame, has higher stiffness than isolation part, so the resonance frequency increases following the increase of the excitation frequency. We could show that unstable vibration may occur in the accelerating state of tractors by nonlinear characteristics of the isolation rubber.

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Control algorithm based on semi-active dynamic absorber for aseismic design is investigated. The structure with joint elements is simplified by dual mass model and they are regarded as main and sub structure. Considering the sub structure and a joint element as a semi-active dynamic damper, control algorithm to reduce the seismic response of main structure is studied. This algorithm demands a damper to act as a spring which has various spring constants and the stiffness is shifted real time based on the information for the dominant frequency of input earthquakes, so as to avoid the resonance between the boiler structure and the ever-changing dominant frequencies of input earthquakes. Numerical simulation showed that the proposed method is superior to the optimally tuned passive dynamic absorber.

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This paper concerns modal control of a rectangular panel using smart actuators that enable the actuation of a target mode without causing any effect on other structural modes. Compared to conventional point-based actuators, distributed parameter actuators presented in the work possess significant benefits provided that they are properly designed. First, a background of modal control based upon the distributed actuators as well as a combination of distributed actuator and a point sensor is outlined. Three dimensional modal actuation using PVDF film is, then, presented. Furthermore, taking into consideration a practicability of the actuator, a two-dimensional smart modal actuator is presented, the number, locations and shaping function for the optimality of the actuator being clarified. Moreover, an experiment is conducted, showing the capability of the distributed parameter modal actuator. Finally, a feedback control system is constructed utilizing the smart actuators, demonstrating the effectiveness for suppressing the particular structural mode of interest without causing any spillover problems.

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In previous papers, as a basic study for reducing booming noise of a wagon-type vehicle, the authors analyzed the sound field of a rectangular space with flexible panels at some of its surface planes, regarding the space as a structural-acoustic coupling system. As a continuation to previous papers, the authors consider use of a dynamic damper. It is found that dynamic dampers designed following the usual guidance for structures are not satisfactory for the present purpose. So, in this study, optimum designing of a dynamic damper for structural-acoustic coupling systems is examined. For this purpose, first, guidance for optimum designing is proposed based on a one dimensional structural-acoustic coupling system. Then, the effectiveness of the proposed guidance is examined experimentally in a rectangular space. Finally, the effectiveness of the proposed guidance is examined in an actual car. It is shown that the proposed guidance is shown to be satisfactory.

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A numerical method is proposed to calculate dynamic dissipated energy for mixed structures including elastic body, viscoelastic body and porous body. A expression to calculate share of dissipated energy for an each element in mixed structures is derived. Using this expression, vibration transmition properties are analyzed for mixed structures composed of porous media sandwiched between steel beam and plastic sheet. Further, a spacer is installed between the steel beam and the plastic sheet in the structures, to analyze deterioration of vibration by the sound bridge phenomena.

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In spacecraft system acoustic tests, one often sees local pressure increase in the narrow gap between spacecraft primal structures and components facing toward the fairing wall. This acoustical environment load to the components differs from that the components are tested alone and the flight acoustic environment may not be actually simulated in the ground testing. In this paper, in order to clarify the mechanism and evaluate this pressure increase, basic experiment including acoustic testing and vibration modal survey are employed. It is found that the main reason of the phenomenon is dominated by the acoustic cavity on the appropriate boundary condition rather than structure vibration. Boundary element method is used to analize the phenomenon and comparison of analysis and experiment results are carried out. The analytical and experimental results agree well. Furthermore, it is understood that the phenomenon of local sound pressure level increase is dominated by the acoustical standing wave mode (1, 1) which can be predicted by the presented methods.

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We propose a method of optimization for a new type of shock absorber. This shock absorber includes MR fluid that is material that responds to an applied magnetic field with a change in its apparent viscosity. We suppose that the MR shock absorber is applied to landing gears of aircrafts for cope with the problem that the vertical acceleration of aircrafts during landing varies due to variation of their masses. The maximum vertical acceleration of an aircraft is set as an objective function to be minimized. In this optimization method, we propose design variables that consist of orifice areas, a MR resisting force and a piston tube position at which the MR resisting force is changed to zero value. As a result of the optimizations, the optimum orifice areas, MR resisting force and piston tube position of the shock absorber are obtained. Furthermore, it is clarified that the MR shock absorber can cope with the mass variation of the aircraft as much better as optimum passive shock absorbers via simulation.

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Flexible rotors supported by Active Magnetic Bearings (AMBs) are subject to the ISO 14839-3 concerning the evaluation of stability margin. In this study, we prepared PID AMB controllers in conjunction with several filters : notch filter (NF), phase bump filter (PBF) and phase shifting filter (PSF). Our AMB system is controlled by mode regulators : parallel mode and tilting mode. According to the ISO instruction, we measured the sensitivity function and evaluated the stability margins by the peak values. In our test, the combination of PSF for parallel mode and NF for tilting mode best meets the ISO standard. Corresponding to these test results, we developed a simulation method to calculate the sensitivity function. This rigid-bending combined model involves a mass matrix obtained by mode synthesis and a stiffness matrix tuned by anti-resonance frequencies of measured plant transfer function data. Consequently, the precise prediction of the sensitivity peak is completed by this modeling.

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This paper dews with H_∞ DIA control of a magnetic suspension system using μ-synthesis. H_∞ DIA control is a H∞ control problem which treats a mixed Disturbance and an Initial-state uncertainty Attenuation (DIA) and supplies H_∞ controls with good transients. H_∞ DIA controller has a good initial response property, however its robust performance can be improved. We propose a novel control problem which is to find a multi-objective controller to achieve H_∞ DIA condition for good initial responses/transient responses and the structured singular value μ condition for robust performance. We apply this proposed approach to a magnetic suspension system, and design a robust controller which has both good transient and robust performance properties. Finally, experimental results show effectiveness of the proposed control system design framework.

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This paper describes the phenomenon of the flow-induced vibration in a shell&tube type heat exchanger. This type heat exchanger has often been used in the LPG gas carrier ship and has sometimes caused a fretting and finally comes to a fatigue failure. In flow-induced vibration, there are a vortex-induced vibration, a fluid elastic instability and a buffeting. Experiments are carried out by use of an actual heat exchanger in order to clarify the cause of tube vibration. The vibration of a lot of tubes is measured for various flow rates and the natural frequency and its damping ratio are also measured. As a result, the cause of the vibration of tubes is not the fluid elastic instability and the vortex-induced vibration but the buffeting due to the turbulence of upstream flow. The main reason is that these tubes are supported by many baffle plates with clearance and then the vibration system becomes the nonlinear.

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This paper describes the confirmation of countermeasure's effect for flow-induced vibration in a shell & tube type heat exchanger. This type heat exchanger has often used in the LPG gas carrier ship and has sometimes caused a fretting and finally comes to a fatigue failure. In flow-induced vibration, there are a vortex-induced vibration, a fluid elastic instability and a buffeting. In this paper, the clip is adopted as the countermeasure and it is clarified that the clip can suppress the tube vibration drastically. In this experiment, another countermeasure, that is to say, the dummy tube array is also examined. However the fluid elastic instability occurs by use of dummy tube array. The reason is that the dummy tube was supported by baffle plate without clearance. Therefore the damping ability becomes very small and the natural frequency of the tube appears very clearly.

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Sliding mode control realizes desired dynamics of an object system by constraining its states on switching hyperplane designed in phase space. Besides, for control problems of a time-varying system, the controller considering its nonstationary characteristic is effective for its motion and vibration control. Therefore, this paper presents a synshesis method of nonstationary sliding mode control using a time-varying hyperplane. In the proposed method, a time-varying feedback gain derived from the nonstationary control method is adopted as a gradient of time-varying switching hyperplane, and the hyperplane is designed as a continuous function with time. The controller constructed by the time-varying hyperplane and its differential term is suitable for the control of time-varying system, and then the controller shortens the term of reaching mode. Furthermore, this paper gives the proof of stability of closed-loop system including the proposed controller, and examines its performance and the special feature through the numerical calculation for a wire changing its length.

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In this paper, we propose a sensor that detects both pressure and shear informations by a helical spring and strain gages. The stresses working on the wire of spring are analyzed. The way to attach strain gages on the spring is discussed and the calibration procedure is shown. Finally, experiments are carried out and the effectiveness of the sensor is shown.

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Power assist system technology and its applications to manufacturing systems have attracted special interest recently. However, many power assist systems for industrial uses possess simple power assisting function only. This study takes account of the case that a positioning pattern appears repeatedly. We discuss the combination of an automatic access motion and a manual delicate adjustment for the case. This paper proposes a positioning control method by means of a switching from an automatic traveling mode (ATM) to a semi automatic settling mode (SASM). SASM provides the nominal motion (NM) based on an optimal control method and realizes the power-assist for the manual adjustment of NM. To obtain a smooth switching, this method utilizes a two-degree-of-freedom control system structure which consists of two parts. The first part is the on-line simulator including the nominal motion generator and a nonstationary impedance controller. The other one is an LQI servo controller. The effectiveness of the method is verified experimentally.

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The paper presents a design and characteristics of a new holonomic omnidirectional moving vehicle, which simultaneous and independently controlled translational and rotational motions. The moving vehicle has four rubber balls instead of wheels. Each ball is driven by two rotating rollers. But the system has only four actuators. The kinematics of the moving vehicle is analyzed and the control algorithms are derived for the holonomic and omnidirectional moving vehicle. The experimental results show that the proposed new type of moving mechanism has good characteristics and the sensor on board is useful for autonomous moving under relatively large disturbance.

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This paper considers parameter identification of a 2 link underactuated Acrobat robot called Acrobot. According to parameter identification studies, the method using Extended Kalman Filter (EKF) has been proposed. The Acrobot considers here is assumed to be influenced kinematic and viscouse friction, and it's equation of motion includes discontinuous terms. Unfortunately, EKF can't be executed such an indifferentiable nonlinear systems. Then we proposed a new method using the Unscented Kalman Filter (UKF) for parameter identification of the Acrobot. UKF is the state estimation method for nonlinear systems developed in recent years, and this method is applicable even when there is a discontinuity in nonlinear systems. The proposed method's effectiveness has been clarified through computer simulation and experiment.

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Soft mechanics inspired from natural systems is one of keywords in the robotic field in last decate. Accordingly, artificial muscles were widely investigated due to their potentials in soft machines or soft robots. There developed many types of artificial muscles including pneumatic ones, ion-exchange polymer composite ones, polymer gels, shape memory alloys, and so on, however, they are not used as a practical actuator. In this study, the authors propose a new type of micro artificial muscle actuator (<1 cm³) utilizing the electro-conjugate fluid (ECF) which generates powerful jet flow (ECF jet) with high voltage supply (-kV). The actuator is mainly composed of a fiber-reinforced silicone rubber tube and a micro pressure source using the ECF. The inner pressure of the silicone rubber tube is increased by the ECF jet generated at the pressure source. The silicone rubber tube contracts along the actuator axis with the increasing pressure. The driving characteristics of the micro artificial muscle actuator were experimentally investigated. The experimental results confirm the effectiveness of the proposed actuator.

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This paper describes a torque control servomechanism for small size robots. As a well known actuator for small size robot, a radio-control servomechanism has been used recently. These radio-control servomechanisms on the market has its position-controller inside. Robot system can use these servomechanisms as the open-loop type position servo system. Though, the controller has not the torque control ability which is essential function for robot system. Thus, we made a motor driver for the radio-control servomechanism which can control output torque by controlling current supplied to motor. In this paper, we confirm torque control function of the motor driver. Then, a small size humanoid was made up by use of the motor controller and radio-control servomechanisms, which has the torque control function. Experimental results show that smart compliance control can be realized. It gives softness of the robot movement, which such a small humanoid has not obtained yet.

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This research is concerned with shape and attitude control of nonholonomic space robot. An integrator backstepping method with neural network is applied to the kinematics control of 2-dimensional free-flying space robot to expand it into dynamics control. The stability of control method is guaranteed by Lyapunov theory, even if there are some unstructured dynamics and/or unmodeled bounded disturbance. Therefore the controller does not have to know about the strict dynamical parameters of the robot. The effectiveness of proposed controller is confirmed through numerical simulations.

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This paper describes the overview of ETC system in Japan, and focuses on the issue of traffic jams, which occurs around toll plaza of expressway even after the introduction of ETC system. For a solution to this issue, this study proposes a process simulation-based approach to study and evaluate the layout design of toll plaza. The paper presents process simulation model which has been implemented in this study, and evaluates the quality of the model. Then, several layout design examples were proposed and studied based on the model, and the validity of our approach will be discussed.

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A technique for generating a medial surface model-that is used to transform a thin structure into a medial surface model for FEM-was developed. This technique can reduce the workload in generating a medial surface model for a thin structure model. The technique has two features. First, the medial surface model can he generated from a solid model including rib because the rib faces can be recognized by adjacency-relation graph of solid-model. Second, the shape of the medial-surface model can he controlled according to the analysis type because the shape of medial-surface model can be controlled by user interactive operations. Furthermore, the developed technique was applied to the generation of medial surface models of bracket and cellular phone cover and the effectiveness of this technique was confirmed.

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A simple series hybrid power system composed of passive-type polymer electrolyte fuel cells (PEFCs) and electric double-layer capacitors was adapted to a lightweight electric vehicle. In order to numerically simulate the behavior of the hybrid system, a fuel cell equivalent circuit model was applied and the model parameters were determined using an electrochemical theory and experimental results. Including this PEFC equivalent circuit model, a simulation model of the power train system (PEFCs, capacitors, motor, power controller, inertia, etc) of a lightweight electric vehicle was composed. It has been confirmed that this simulation model can represent reasonably well the dynamic behavior and energy transmission of the system in the experiment on a fixed apparatus constructed as a model of the vehicle.

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Although services are getting more and more focus in industries, very few researches on dealing with services from the viewpoint of design have been achieved. This paper aims at proposing a service design method based on the scheme of Service Engineering, which the authors have been researching. First, problems of “decoupling” in traditional service development processes are pointed out. Decoupling in this case exists between a marketing section and a design section, and also between products and services. Second, the proposed design method is explained after briefing an adopted model of service, which the authors have already proposed. The design method contains detailed procedures to complete the service model. Through applying the method to a hotel service in real operation in Italy, it was proved that the method has a potential to help service designers effectively.

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The objective of the present research is to develop a systematic method for planning and analysis of kinematic motion deviations of machine tools based on geometric tolerances of three-dimensional components. This paper deals with the modeling and analysis of the geometric deviations of the toleranced components. The tolerance zones of the geometric features of the components are investigated and classified based on the definitions of the geometric tolerances. The parameters are defined to describe the deviations of the geometric features within the tolerance zones. An analytical method is proposed to estimate the statistic deviations of the positions and the orientations of the geometric features, based on the deviation parameters and the relationships between the datum features and the toleranced features.

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Demands for accuracy and downsizing of industrial products have been escalating recently. And it is difficult to meet such demands only with conventional technologies. Therefore, the process technologies with fields, e. g. an electric field or a magnetic field, are remarked. “ER slurry” that we named is a composition of ER fluid and abrasive grains. Using this slurry under the electric field, we can control polishing conditions. In this report, we propose one-sided pattern electrodes that are arranged on one-side. And we also propose to use them for ER polishing which is the polishing with the ER slurry. At first, ER effects of the ER slurry which was composed of a liquid crystalline polymer (LCP) and diamond grains were investigated. These characteristics depend on a pattern type of electrodes and density of the grains. In addition, we tried the polishing with the ER slurry and confirmed that the electric field accelerated the polishing.

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A new-type tire is presented, in which there is no air leakage when nails break the tire. The broken part is repaired automatically by its self-repairing mechanism. The self-repairing unit is consisting of two rubber sheets with lattices inside. Polymer particles, which expand their volume with water, are kneaded by bond, and inserted in the lattices. The unit is pasted to the inside wall of the tire. Coolant fluid diluted with water is inserted in the polymers uniformly. In this system, the polymer particles expand with water diluted coolant fluid, and become gel. Hence, they stop air leakages in the tire. Fundamental experiments are performed, and optimum conditions are found. This technique is also applied to real tires.

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Traction perpendicular to rolling direction based on spin and side-slip was determined with a disk-on-roller machine. The measurements for di-octyl phthalate showed that the traction based on only spin was due to the elasticity of an EHL oil film from the viewpoint of rheological properties. Then, the influence of some parameters on the traction was examined for the synthetic naphthenes. The traction increased with increasing contact pressure and decreasing temperature. On the other hand, decrease in the radius of curvature of transverse direction increased traction because of increase in the elastic strain through decrease in the film thickness. Effective shear modulus derived from the traction measurements was an order of 0.1 GPa at 30°C for the synthetic naphthenes, which slightly decreased as the contact pressure was increased.

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Recently, in the various industry fields, TAGUCHI Method is used for quality control. On the other hand, Neural Network is used to find the optimum condition because it has learning ability for non-liner phenomenon. In this study, these quality control methods are compared. At first, the minimum value of the output in mathematical models is found by using TAGUCHI Method and Neural Network. And the advantage and fault of each method are explained from the result. In addition, both methods were improved in order to correct itself faults. Finally, the friction of sliding surface was used for practical evaluation regarding both methods. As that result, the condition for reducing coefficient of friction could be estimated with both methods. It is concluded from the result that (1) TAGUCHI Method was mighter than Neural Network when input data was discontinuance such as physical value using only integral number, (2) The optimum condition of the high precision in TAGUCHI Method can be found by approximation between the levels of control factor, (3) TAGUCHI Method is particularly effective when there are a little measurement data and when high reappearance is required, and (4) Neural Network is effective in founding the optimal condition of high precision from sufficient measurement data.

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The scoring-load capacities of the vegetable oils with anti-wear additive of Dibutyl Phosphonate (DBPo) were studied by using a power-circulating gear test rig. The tests were carried out under a slash-pan lubrication. From the tests, the following results were obtained. (1) The scoring-load capacities of the vegetable oils increased in following order : Turbine oil<Corn Oil<Soybean oil<Rapeseed oil. The normal load per unit face width, P_n, at the incipient stage of scoring when lubricated with the rapeseed oil was approximately 1.7 times as large as that when lubricated with a turbine oil. (2) With respect to the vegetable oils with DBPo additive, surface failure by scoring didn't occur at the final load range in tests. The increases in the scoring-load capacities of rapeseed oil, corn oil and soybean oil with DBPo additive were over 78 N/mm, over 378 N/mm and over 449 N/mm, respectively. (3) The critical temperature at a risk for scoring with the rapeseed oil was about 400°C, and was the highest of all test oils. On contrast, the critical temperature with the vegetable oils with DBPo additive exceeded about 400°C.

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