This paper describes a control method of magnetic levitation system which uses actuators and permanent magnets. The control method is pseudo zero power control, in which there is a little power loss during the system is operated near the equilibrium. As the adjustment of the air gap length varies the suspension force and stabilizes the system, the zero power control can be achieved by such as a spring force. First an experimental device is introduced and the principle of levitation is explained. Numerical simulations for the zero power control are carried out based on the model of the device, and some experimental examinations are shown.

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In recent years, many approaches for zero power control of magnetic bearing system have been proposed. However, these methods are complicated and difficult because most of the methods based on nonlinear control theory. In this paper, we propose a new simple design method using linear H_∞ control theory for magnetic bearing systems. The H_∞ controller is designed regarding the electromagnetic forces as the control input, and the coil currents are calculated using nonlinear equation in real-time so that the magnetic bearings can generate the forces correspond to the output of the H_∞ controller. The effectiveness of the method is shown by experiment.

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Vibration isolation system using zero-power magnetic suspension is modified. A suspension spring is introduced in parallel with a series connection of a zero-power-controlled magnetic suspension and a normal spring that were used in the previous works. It can reduce the lord force that the zero-power magnetic suspension has to bear. A basic configuration of the modified vibration isolation system is shown. An analytical study demonstrates that the modified system maintains infinite stiffness against direct disturbance even if such spring is added.

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Canned motor pump can treat various liquid. We have to design the control system in response to kinds of liquid at thrust magnetic bearing. Therefore, it takes much time for people who has little experience of designing control system, to design. In this study, we developed computer aided design of thrust magnetic bearing which hardly needed experience. At our developed CAD, identification method is Ljung's method and designing controller is coefficient diagram method. We apply our developed CAD to experimental setup, and test the effectiveness of it.

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This study aims at establishing a robust intelligent control method with higher control performance and wider applicable region. In particular, this study deals with a nonlinear control problem. In this study, the dynamical energy principle is embedded into the integrator of Cubic Neural Network (CNN). The proposed CNN is applied to a control problem of a swung up and inverted pendulum. The performance of the proposed CNN are verified theoretically and experimentally compared with the sliding mode control techniques.

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This paper presents a method of simple adaptive control for nonlinear systems using neural networks. The control input is given by the sum of the output of the simple adaptive controller and the output of the neural network. The neural network is used to compensate the nonlinearity of plant dynamics that is not taken into consideration in the usual simple adaptive control. The role of the neural network is to construct a linearized model by minimizing the output error caused by nonlinearities in the control systems.

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The performance of various types of control systems for an electric governor of a diesel engine was examined. The amount of fuel injection of a diesel engine is usually controlled by an electric governor system in these decades, and a PID controller is installed for the electric governor. Even when the optimal parameters for PID controller are well tuned, it is difficult to keep constant rotating speed of the engine, because the applied load to generators may vary according to its running conditions. In this research, a neural network was applied to regulate the parameters in PID controller for the axial-moving DC motor to control the amount of fuel injection. Experimental studies show that the parameter regulation system using neural network presented here had good performance under various running conditions.Furthermore, it was shown that various types of training laws were applied to neural network control systems and their performance was verified.

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Support Vector Machines (SVM) are new machine learning methods, and are studied about many applications. However, a regression method of SVM shows little availability. In this paper, we propose a learning control scheme using Support Vector Regression (SVR). This control system consists a pre-learned SVR, and is applied to a control problem of inverted pendulum. SVR system learned input-output data of state feedback control given an initial condition. The computer simulation results show the availability of the proposed control system.

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This paper presents a development of an autonomous small unmanned helicopter for hobby-class which weigh about 9 kg focusing velocity models and controller design. The simple SISO transfer function models are derived from brief kinematical analysis for each horizontal helicopter dynamics. The independent two controllers are respectively designed based on the derived models by using LQI optimal control theories. The models and control structure are verified by showing successful experimental result. Accurate position control, namely, the hovering control and trajectory following control is achieved by simple control algorism using designed velocity control structure. Robustness of the controller against wind is tested an experiment done on windy day. To verify the robustness against perturbation of physical parameters of helicopter, designed controller is applied to bigger size helicopter. To achieve accurate trajectory following control, optimal preview controller is designed. Finally circular trajectory is drawn by the designed preview controller.

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A laser tracking system and a smart wing are proposed and developed to control the flight of a laser-driven micro-airplane. The lasertracking system is composed of a light source, detector and optical system with a galvano-mirror control mechanism, and used for controllingthe smart wing constituted by a wing, phototransistor, battery and smart material. The light source is installed on the ground and so thissystem is effective for miniaturization and lightening of the micro-airplane. Experiments are carried out to evaluate the performance of thelaser tracking system and the smart wing.

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SSM (Sensor Steering Mechanism) is constructed with the sensor arm and the deceleration gear system of which gear ratio is fixed to two to one. The existence of sensor arm prevents to realize SSM for conventional vehicles. This paper tries to replace the sensor arm with 1kHz Smart Camera which is developed recently. By using of the difference between left and right pixel values over the each edge of the center line, the following control is applied to SSM-vehicle model. The vibration of the control system caused by the long sampling interval is reduced by using the dynamic absorber. Finally, the experimental results show the stable cornering even if the rear part of the vehicle is drifting.

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This paper proposes a norm-type discrete Riccati equation, which is a generalized version of the well-known standard discrete Riccati equation, and has additional norm terms. Under stabilizability and the assumption that the additional terms are not too large, the existence of a positive semi-definite solution is guaranteed. Such an equation appears in the guaranteed cost control based on norm-type upper bound. In this paper, a numerical solution and a numerical example are given about this equation. Moreover, application to guaranteed cost control is also given.

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As a new control technique, rule-based pseudo sliding-mode control system is developed for an inverted pendulum system. In the rule based pseudo sliding-mode control system, the transient solution is constrained on the subspace that is spanned by the corresponding eigenvector with negative eigenvalue of the linearized system, and consequently, the similar motion to the sliding-mode is generated. However, the chattering does not occur at all. The control input is evaluated by applying the concept of fuzzy control. The validity of the present control technique is confirmed from the results of numerical simulation.

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In this paper, the design method of sliding mode control (SMC) system for SISO linear system is discussed. First, we consider the similarity between the design method of sliding mode hyper plane using the strict positive realness and the characteristics of zeros of feedback system and the design method of simple adaptive control. Based on such a consideration, we propose the new design method of SMC system using parallel dynamic compensator. As a result, SMC system can be constructed only with the derivative of output signal for controlled plant. The performance of SMC system designed by proposed method is confirmed through the numerical example.

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This paper gives a design method of discrete-time robust control systems that are subjected to reference inputs restricted in magnitude and rate of change. Based on the principle of matching, we derive a practical necessary and sufficient condition that ensures time-domain specifications in discrete-time. Additionally, we derive a practical robust matching condition based on the practical necessary and sufficient condition under the plant uncertainties in discrete-time. A simple design example of a speed control system of a DC servo motor is also given.

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In this paper, we consider the vibration isolation system using an active damping control. In this system, if frequency of disturbance is known in advance, we can shape the frequency response of the feedback control system by using notch-filters in order to reduce the influence of the disturbance. However, specifying the parameters of the filters is difficult because the control performance changes cause of slight change of the parameters of the controller. In this paper, we show an example of a problem by using conventional design method and provide a method by H-infinity control based on the frequency shaping.

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In this paper we design a gain-scheduled controller for active seismic isolation of a structure taking account of actuator constraints, so that the closed-loop system is stable and has good performance even if saturation phenomena of the actuator occur. We utilize the time derivative of the actuator force to suppress the acceleration response at actuator saturation. By carrying out the experiment it is verified that the our proposed method is effective for actuator saturation problem in active seismic isolation.

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The control system driving the vibration absorber with the force proportional to the velocity of the primary structure are unstable. This paper presents a method for avoiding this problem. Basically, we transform the stiffness term of the equation for the absorber into the inertia term by replacing the eigenfrequency of the absorber by arbitrary frequencies of excitation. The present control method enables us: (a) to achieve effective and robust control performance over a wide frequency range against marked variations in the primary structure to be controlled; and (b) to control many vibration modes excited by broad-band excitations.

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In this paper we treat a collision problem between two objects and apply H_∞ control in order to actively control the shock caused by the collision. The controller is designed so that the shock is transfered as unilaterally as possible. In order to evaluate the shock transfer ratio the deformation ratio between the two objects is introduced. In our experiment the discretized controller is implemented in the digital signal processor used to realize instantaneous cotrol motion. By carrying out the experiment it is verified that active shock control is realizable and the controller we designed is usufull for shock control.

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In this paper, we deal with a three-link space robot moving in planar space without controls for the base attitude. An experimental setup of the three-link space robot can levitate by use of compressed air. Using d'Alembert principle, it is shown that the state equation of the three-link space robot can be reconstructed as a first-order nonholonomic system with the constraint condition that the rotational angle of the base is set to be zero. The feedforward torque inputs can be obtained by the final-state control in order to bring the end effector of the space robot from the initial position to the objective position in the desired time. We designed a two-degree-of-freedom control consisting of feedback control and feedforward control to follow the obtained trajectory. It is verified from simulation and experiment that the proposed method of motion control is useful.

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The purpose of this study is to make a model of two-link flexible robot arms. For this purpose, we used a modeling method called an 'extended reduced-order physical model (extended model)' that is able to express the motion and vibration of flexible structures. The model of the two-link flexible robot arms is made of a combination of the model of each link. The construction of each model is applied to the extended model. To connect each link, the constraint addition method is used, creating method of an equation of motion in multi-body systems. The model of the two-link flexible robot arms agrees qualitatively with the results obtained by the experimental device.

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In this paper, we discuss a posture control problem of a 2-link acrobat robot with nonzero initial angular momentum. First, we derive a strict feedback system by a coordinate transformation. Then the control problem is formulated as designing a control law such that the state variables of the system go to the origin at a given time. Next, the control law of the driving torque is designed by applying a backstepping procedure to the system. It is shown that the control performance and input efficiency are improved by using time-variant gains. Finally, simulation results are presented to show validity of the proposed controller.

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To achieve high-efficiency biped walking, we proposed a self-excited walking of biped mechanism and clarified the characteristics of the self-excited walking by the simulations and experiments. This paper presents a self-exciting walking of a biped mechanism whose stance leg knee is bending. From the simulations of self-excited walking with bending knee, we found that the walking priod becomes shorter than that of the straight knee mode, and that the walking speed become fast. Possibility of the self-excited walking with bending knee was actualized by the experiment.

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This paper deals with the vibration analysis of spatial serial manipulators with elastic links. A manipulator was assumed as an instantaneous Rahmen structure composed of L-shape elastic links and additional rigid bodies. Kinetic energy and potential energy of the L-shape link and the rigid body were formulated in detail. A system of dynamic equations respect to the deformation of nodes in the structure was then derived with Lagrange's Equation. Transient vibration of a 4-link manipulator was analyzed and experimentally measured. The tip acceleration calculated with the proposed method agreed well with that of measured values.

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The buckling analysis method based on Corotational formulated FEM for complex flexible multibody beam structures is proposed. This method makes it possible to analyze light weight deployable beam structures that may be subjected to buckling taking into account the geometric nonlinearity stemming from large rotations. The mechanical motion, elastic deformation and buckling can be handled by the consolidated mathematical treatment and computational algorithm presented in this paper. This paper especially focuses on a buckling mode injection method while a concerned structure undergoes mechanical motion. A buckling mode is estimated even though a bifurcation point is not accurately obtained. The validity of this method is confirmed in a numerical examination.

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A ladder of the ladder truck with lift mechanism often generates a lot of vibrations at the time of the lift operation. The lift operation includes the extending and retracting motions, the ascending and descending motions, and the turning motion. In this paper, the simulation analysis of the dynamic behavior for the 2 sections flexible ladder which can extend and retract each other is described. We make the dynamic analytical model of the 2 sections flexible ladder using multibody dynamics. A coupled equation of motion of the 2 sections flexible ladder is derived using the differential algebraic equation (DAE). Performing the numerical simulation studies taking the dimensions of the 2 sections flexible ladder model parameters.

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CAE technology improves, and a variety of optimization techniques begin to be introduced into the design of the machine structure. One purpose of the optimization techniques is to propose the measures idea against the engineering problem. However, it is difficult to propose the measures idea efficiently in a present optimization technique (for instance, sizing optimization) when thinking about the vibration problem of the structure. Moreover, there were problems in the formulation of the rigidity of the uniting part and the normalization of sensitivity in the sensitivity analysis by the transfer function synthesis method. Therefore, to establish the method of efficiently proposing measures against the vibration problem, it proposed the sensitivity analysis using the eigenvalue and the eigenvector of the stiffness matrix. It is possible to propose the measures idea that the designer understands easily by this method.

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This paper proposes a procedure for predicting the modal data of a thin plate structure with a rib stiffener even when the rib is attached to any location where mode shape data is not defined. This procedure is based on the Structural Dynamics Modification (SDM) method and the mode shape expansion method is incorporated to estimate the mode shape data at the unmeasured points. Numerical results from a thin plate structure with two L-shaped ribs show that the proposed procedure produces the accurate predictions using the estimated mode shape data at the unmeasured points.

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In this research, in order to solve the cause of the impeller for large-sized fan by which the crack entered during actual operation at the joint part of the main board and Blade, vibration and stress analysis using the finite element method were performed. The analysis result showed that the cause of a crack of impeller is for concentration stress to occur in the joint part of the main board and Blade owing to the wave phenomenon of the side board by centrifugal force. Then, the structure optimization by pseudo-inverse method was performed for the purpose of stress reduction. When the design variables were made into the board thickness of an element, design restrictions condition was made into the stress which generates a crack part and repetition calculation was performed, stress was able to be reduced to the target value by calculation of four calculations.

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A steel pan is a percussion instrument that was invented in Trinidad & Tobago in the 1940s. The early stages of a steel pan had been made from the 55gallon oil drum. It has become a popular instrument in Japan, Europe and the United States nowadays. Although a steel pan is a piece of the thin plate structure, it has various musical scales. The thin plate is processed by Panmeker' hand one by one. The radiated sound from a steel pan is included many harmonic overtones. This instrument has been developed after repeated process of trail and error. Therefore the relation between the vibration mechanism of a steel pan and its notes configuration has not elucidated in the analytical process. In this paper the fundamental dynamic characteristics of a steel pan is investigated. Experimental modal analysis is used to identify the vibration mode of a steel pan.

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The modal testings for the real space structure are performed and the correlations with the analytical model are conducted to improve dynamic model. The paper showed an example of the process of the correlation and evaluated the testing frequency error. The evaluation shows the test structure non-linear characteristics and test specimen support structure have significant effects to attain the required accuracy of the test data.

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In order to analyze vibration modes and resonant frequencies of a mechanical structure system in good accuracy, the interface contact stiffness becomes important. In this study, the technique which efficiently calclates the contact stiffness is proposed. Proposing method uses design of experiments and response surface methodology, and furthermore, to improve accuracy of identification , uses sequential linear programming while considering both natural frequencies and vibration modes of a system. In this paper, the effectiveness of proposing method is verified by numerical simulation taking a simple example.

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Statistical energy analysis (SEA) is applied to predict the responses on the printer unit. First, the selection of SEA subsystems is discussed using the initial slope ratio techniques. Then, an SEA model is constructed experimentally. The vibration energy level on each SEA subsystem predicted by the constructed SEA model is compared with the measured levels under impact test. It is shown that the vibration analysis on the printer unit is suitable for SEA. Next, the power input under the operating is identified using the built SEA model. The identified input power is obtained in some small time intervals. It is difficult to identify the power input by the other methods. It is concluded that the product of plastic mold is available to analyze the vibration responses predicted by SEA.

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This paper presents a method for estimating the exciting forces that cause the structure borne sound. First, in order to specify the number of the sources, principal component analysis of the operational responses is carried out. Secondly, the exciting forces are calculated using the frequency response functions measured indirectly and the operational responses. In addition, in order to evaluate the vibration due to estimated forces using the statistical modal analysis, a modeling method of the support structure that is constituted with some components are proposed. In this model, the estimated forces are considered using the shaping filter.

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In this paper, the authors present a method for generating accurate finite element models of complex mechanical structural structures and components using a 3-dimensional digitizer and experimentally obtained modal parameters. The coordinates of many points on the surface of an objective body are accurately acquired using a 3-dimensional digitizer at first. A finite element model is then built up based on a kind of interpolation using the data of the surface. On the other hand, some of the modal parameters of the body are obtained by modal testing. The natural frequencies of interest are tuned with respect to the finite element model by referring the experimental parameters. The structural parameters to be tuned are Young's modulus of individual finite elements in this study.

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For ADE on a ship, it is necessary to perform experimental modal analysis (EMA) by base excitation. Existing EMA tools are designed to perform curve-fitting on the frequency response function of displacement or acceleration at measuring point to an excitation force. However, in case of experiment by base excitation, transmissibility of acceleration, that is, the ratio of accelerations between measuring point and base is to be used for modal analysis. A method, which makes modal analysis for base excitation possible by performing curve-fitting on the transmissibility of acceleration using existing EMA tools, is proposed in this paper.

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In general, Live load on structures is not distributed uniformly. The rotational degree of freedom on a plane in the structure is existed and the torsional vibration is occurred. Many examples of damage by the torsional vibration on the past earthquake are reported. This paper presents the vibration modes and the twist responses of multi storied structures to having translational and torsional degrees of freedom on the planes. At first, it is divided each vibration modes into the translational modes and the rotational ones. Next, the relationships of their modes are indicated with transfer function. And the effects on their modes are examined for earthquake responses.

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This paper deals with the cutting assessment method of machine tool dynamic characteristic. A quantitative method for the limiting cutting width of machine tool by weak mode analysis is proposed. First, shortcomings of the current excitation method and cutting method are discussed. Next, solution of the limiting cutting width is derived from dynamic characteristics of machine tool structure and cutting process. Then, an experiment is carried out and the computational result discussed. The proposed method is robust in theoretical basis and easy for practical use.

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This paper describes the reduction of sound power radiating from a thin plate by adding a hollow. A rectangular plate with the optimum rectangular hollow was made and was examined with FEM modal analysis and experimental modal analysis. The driving point mobility and sound radiation power of the plate were estimated and measured. It was confirmed that the driving point mobility at the 1st natural frequency reduced by 1.19dB while the sound radiation power increased. A new optimization with an objective function of sound radiation power at the 1st natural frequency was carried out. The sound power then reduced by 3.9dB.

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It is now an urgent subject for railway to decrease the vibration and noise of steel bridges. To develop effective countermeasures for this purpose, it is important to study the mechanism of this phenomenon, and establish a method to predict the noise and vibration of bridges, including structure-borne noise, which is characteristic of steel railway bridges. For this reason, the authors studied the method to predict the structure-borne noise of steel railway bridges. Since it is presumed that the structure-borne noise is generated mainly by the sound radiation from flexural vibration of bridge girder plates, an equation to calculate it has been derived based on the analysis of flexural vibration of plate.

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Regarding the prediction of structure-borne sound in large structures consisting of thick plates, there are some difficulties in applying the conventional SEA based on thin plate bending and in-plane waves. This paper examines the applicability of wave intensity analysis to the prediction of the vibration energy level in an L-shaped structure assembled by thick plates. The bending wave in plates is thus expressed by Mindlin's theory. The new model is introduced to improve the accuracy of wave transmission coefficients for line junctions between thick plates. As a result of comparison of the present method with FEM, reasonable results are obtained for the vibration energy level in the L-shaped structure, within approximately 2dB up to 2kHz.

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Sound decreasing effects of sound absorbing material structures installed on the moving rigid surface were verified experimentally for both the stationary and the nonstationary cases by using the one-dimensional acoustic tube. The decreasing effects were evaluated in the frequency spectrum domain by taking the discrete Fourier Transform for the nonstationary case, and almost 70% sound pressure decreasing effect was observed at the maximum in the range of 0.5〜3kHz for the hard porous or fiber alminum sound absorbing material structures with back air space. Then two kinds of quantitative estimation methods of those decreasing effects were examined.

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This paper describes the estimation of sound power radiating from Open type MRI. Gradient coil to generate gradient magnetic field, which was a composite of copper wire and GFRP, was modeled as a material where mechanical properties were distributed. Young's modulus and Poison's ratio of a finite element of the disk was calculated by applying Halpin-Tsai's equation. FEM modal analysis of the disk was carried out and the vibration response against the distributed excitation due to Lorentz force was calculated. The sound radiation power estimated with the vibration response agreed well with the measured one. The suitable arrangement of fixing bolts to reduce sound power was searched with the estimation. It was confirmed that the maximum value of the sound radiation power could be reduced by 0.5dB.

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The attenuation characteristics of a slit resonator that has the adaptive feedback ANC system for leakage noise at a ventilation aperture of the package is investigated. The discrete tones that are radiate from an AC axial fan are controlled by DSP using Filtered-X LMS algorithm. The attenuation level at each discrete tone in using the circular slit resonator is between 4dB and 14dB. Also, the attenuation level between 6dB and 15dB is observed in the ellipse slit resonator. The proposed system, which consists of a slit resonator with control speakers and the adaptive feedback ANC, enable us to reduce discrete tones effectively.

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The concept of the active sound absorption method using thin and membranous piezoelectric film speaker is proposed toward the suppression of aircraft interior noise, especially large turbo-fun jet plane. At first, an active sound absorber unit is constructed with a secondary piezoelectric film speaker and an reference accelerometer, and the controller is designed using Filtered-x LMS adaptive filtering. Then, the active sound absorber unit is applied to the suppression of the transmitted sound through a thin plate, and by observing the sound attenuation at plural points, it is ascertained that the proposed method can actively absorb the transmitted sound, which has the property similar to the aircraft interior noise. Finally, a way of construction of the control system with proposed active sound absorber unit is presented for aircraft interior noise reduction.

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Active control in 3-dimensional sound field against incoming noise from external noise source is considered. Convergence characteristics are investigated with not only conventionally wide-used Filtered-x LMS algorithm, but also FTF (fast transversal filter) and FDA (frequency domain adaptive) algorithms. The advantages and disadvantages of each technique are examined through simulations and experiments using 1/5 scale model. Control results are studied also with both fixed noise source and moving noise source, and the difference in the control performance of each algorithm is compared and considered. As a result of simulations and experiments, it is shown that the control performance of FTF and FDA are better than it of LMS for the fixed noise source. For the moving noise source, each performance of control becomes worse; however, it is shown that control can be continued comparatively stably.

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This paper describes the active control systems for reducing coor impulse noise. The control sysmtem is comprised of actively controlled modular thin plates, which wholly cover the surface of concrete slab structure in the ceiling, and in each of which the mechanical vibration is controlled independently with bimorph type piezoelectric actuators. An active control system of modular plate is presented, where ave actuators and ave sensors are applied to control low frequency modes of bending vibration in the plate. The control system is now under development, where main subjects are, the active control system appropriate to the characteristics.

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In recent years, with the rise of interest in environmental problems, noise reduction in motors has come to be stringently required. There are three kinds of motor acoustic noise: I ventilation noise, II electromagnetic noise and III machine noise. It is assumed that ventilation noise mostly consists of fan noise in high speed machines. As to fan noise, this is produced by the number of rotations and the number of fan blades and by the turbulence sound produced by the disturbed flow of cooling air. Regarding fan blade sound and turbulence sound, many studies on noise reduction have been done by flow analysis using examination of fan blade number and shape. However, papers describing the space resonance frequency of the fan space that is a propagation channel of the fan noise have not been found. Thus, in this paper, space resonance frequency and resonance mode of the fan channel was analyzed by FEM and experiments. These have not yet been studied by research to the present. In addition, the effect of rotational sound and resonance mode on noise is described.

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The Electromagnetic vibration of brushless DC motors was examined. Owing to the inevitable manufacturing tolerances, the level of the electromagnetic vibration in actual motors will exceed design expectation. We measured the electromagnetic vibration with developed experimental equipment that can set the eccentric condition of the rotor to the stator. In this paper, we show the relationship between the electromagnetic vibration and eccentricity or circularity of the stator.

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In the previous paper, an approximate numerical method for three-dimensional problems of Helmholtz Equation is presented. In the method, the collocation method is applied to analytic solutions represented in the polar coordinates. In this paper, the method is applied to not only three-dimensional acoustic problems of free vibration but also those of forced vibration. Numerical results are examined by comparing with experimental results. The calculated natural frequencies of a domain with the shape of a frustum of pyramid agree with measured ones. Furthermore, the distributions of sound pressure calculated on a cross-section of the domain are very like to the measured results. Effects of sound absorption of walls cannot be neglected in actual problems. Therefore, the effects are taken into account in forced vibration problems.

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