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Kazuaki SUGIYAMA, Toshiyuki OHTSUKA
2000 Volume 43 Issue 3 Pages
505-512
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper, the disturbance rejection problem of an automotive active suspension is formulated as an l
1 control problem, that is, the minimization of the effects of disturbances in terms of the l
∞-induced norm. Since l
1 control theory minimizes the maximum possible amplification of signal magnitude, the l
1 controller can specify the maximum magnitude of outputs in the time domain, regardless of the frequency of road disturbances. Shamma's l
1 near-optimal control theory is applied with a certain approximation. To design a simple static full state feedback controller, a nonlinear controller is designed for a linear active suspension model of a quarter vehicle. Finally, satisfactory performances are confirmed by numerical analysis.
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Dongchan LEE, Sangho LEE, Changsoo HAN
2000 Volume 43 Issue 3 Pages
513-520
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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This paper presents a numerical corrector method to find feasible state variables of the constrained multibody systems. For correcting state variables, the Lagrange-Newton method, a nonlinear optimization technique, is used. The iteration formulae derived from the quasi-Newton scheme do not update the Lagrange multipliers in the analysis steps and projects the state variables on the constraint manifold. Therefore, the cost due to the updating of Lagrange multipliers decreases. The method is verified through the convergence theorem denoting a convergence order of numerical solutions and as the corrections are performed along the constraint gradients, the system motion is formed in the null space tangent to the constraint manifold. The simulation example uses a three-dimensional full vehicle model, and the obtained numerical solutions are compared with the ADAMS solutions.
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Kunsoo HUH, Jahng-Hyon PARK
2000 Volume 43 Issue 3 Pages
521-527
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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It was shown that the robustness of deterministic observers with respect to modeling errors, measurement bias and round-off errors can be represented by a single performance index, χ2(P), the condition number of the observer eigenvector matrix. In this paper, based on the performance index, a robust observer design method is proposed for two-output systems where the observer gain can not be determined uniquely with respect to the desired observer poles. Utilizing the pole/zero locations of the observer dynamics, a step-by-step design procedure of the well-conditioned observer is developed. In addition, a new scaling method is developed with employing the eigenvector matrix as a scaling matrix. The proposed method is evaluated and compared with the Kalman filter technique in a spindle-drive simulation example where the load speed needs to be estimated based on the measured signals.
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Chao-Peng WEI, Jason Sheng-Hong TSAI
2000 Volume 43 Issue 3 Pages
528-536
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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This paper presents a new approach for digital redesign of the continuous-time state-delayed system with the state-feedback controller. The bilinear approximation method together with the linear interpolation is utilized to approximate some integration functions, and the concept of the Law of Mean from the integral calculus is applied to establish an equivalent state-feedback digital controller from the available statefeedback analog controller. In addition, for practical implementation of the developed digital controller by a microcomputer, the computation time delay of the digitally redesigned control law is considered and equivalently modeled at the input, and then a digital predictor controller is proposed for the sampled-data state-delayed system with the control delay.
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Tzuu-Hseng S. LI, Yi-Pin KUO
2000 Volume 43 Issue 3 Pages
537-544
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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This paper presents the evolutionary algorithms (EAs) to determine a set of optimum system parameters for the passive suspension system (PSS) so that the best performance of the system can be achieved. The selected fitness functions are chosen according to the analysis of desired performance including sprung mass acceleration (SMA), suspension deflection (SD) and tire deflection (TD) in the frequency domain. Besides, we compare the evolution processes and search results of genetic algorithms (GAs) and evolutionary programming (EP), and find that both methods are effective. All the simulation results illustrate that the EAs can provide better ride comfort and road holding ability in comparison with the commonly used PSS.
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Gyu-Sang CHOE, Kwang-Joon KIM
2000 Volume 43 Issue 3 Pages
545-552
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In linear electrodynamic oscillating compressors, gas force has nonlinear characteristics depending on the stroke of piston. Static and dynamic components of the force are coupled to each other. Furthermore, mechanical part is coupled with electromagnetic part. Hence, dynamics analysis of the whole system is very complicated. In this paper, the gas force is represented in terms of equivalent stiffness and equivalent damping by employing the describing function approach so that analysis of steady state response characteristics and jump phenomenon can be done in a way simpler than by the full nonlinear model. In order to illustrate accuracy of the equivalent model, the frequency response characteristics of the proposed model are compared with those of the full nonlinear model. Jump phenomena depending on the amplitude of supply voltage is also investigated by using the equivalent model and the necessary conditions for jump to occur are derived.
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Jung Hun PARK, Hong Hee YOO, Yoha HWANG, Dae Sung BAE
2000 Volume 43 Issue 3 Pages
553-559
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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A method for the inverse dynamic analysis of constrained multibody systems considering friction forces acting on kinematic joints is proposed in this paper. The stiction and the sliding which represent zero and non-zero relative motions are considered during the inverse dynamic analysis. Actuating forces to control the position or the orientation of constrained multibody systems are usually calculated in the inverse dynamic analysis. When the friction is considered, an iterative procedure need to be developed to calculate the actuating forces, which are uniquely determined during the sliding but riot uniquely determined during the stiction. Numerical examples are solved to demonstrate the accuracy and the effectiveness of the proposed method.
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Hiroki TOKASHIKI, Kenji KANEKO, Kazuo TANIE
2000 Volume 43 Issue 3 Pages
560-567
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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Identifying and implementing high-fidelity scaling laws in scaled teleoperated systems remains a challenge. We propose the use of tactile information to complement and supplement the normal visual and force channels and thereby provide sensory enhancement when performing tasks involving delicate motions. We support our proposal by presenting experimental results from tests performed by humans under simulated and experimented conditions. Our results show that integrating tactile feedback improved the performance of the operator.
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Tetsuya OGATA, Shigeki SUGANO
2000 Volume 43 Issue 3 Pages
568-574
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper, we discuss the communication between autonomous robots and humans through the development of a robot which has an emotion model. The model depicts the endocrine system of humans and has four kinds of hormone parameters to adjust various internal conditions such as motor output, cooling fan output and sensor gain. We surveyed 126 visitors at the '97 International Robot Exhibition held in Tokyo, Japan (Oct. 1997) to evaluate their psychological impressions of the robot. As a result. the human friendliness of the robot was confirmed and some factors of human-robot emotional communication were discovered.
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Vedam KRISHNA, Saravanan M. PEELAMEDU, Rahul PHADNIS, Nagi G. NAGANATH ...
2000 Volume 43 Issue 3 Pages
575-585
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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A general equilibrium analysis of automotive drivelines with multiple universal joints and numerous supporting conditions is presented. For the analysis, components of the driveline in terms of their angular rotation, angular velocity and acceleration are defied. Using kinematic conditions and a known torque and speed, the angular speed of the axle output shaft and all intermediate shafts and forces at contact points is computed using a software developed to perform the analysis. To perform a time domain analysis, the quasi-static equilibrium conditions are imposed on the system at an instant The instantaneous behavior of the system is determined as a function of the transmission output shaft rotation. Finally numerical example is provided to illustrate the analysis. Results of the numerical example are plotted with respect to time. The general behavior of the forces is found to be oscillatory and harmonic in nature.
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Manabu GOTOH, Young-Soo KIM, Minoru YAMASHITA
2000 Volume 43 Issue 3 Pages
586-593
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In stretch- and deep-drawing processes, each material element of the sheet changes its moving direction by a right angle once or twice when it passes over the die profile and, in the second stage of double operations, over the blank-holder profile. Thus it was considered very difficult to simulate it by a dynamic code. Therefore, the effectiveness of the dynamic explicit bite element code DYNA-3D for simulation of cup forming by the quasi-static processes of deep- and stretch-drawing both in single and double stages is tested. The numerical results show that the prediction of the cup depth is fairly accurate for almost all cases investigated except for a few cases. The limiting drawing ratio predicted numerically, however, considerably exceeds the corresponding experimental value for all cases tested. Stretch- and deep-drawing accompanied by ironing of a thick sheet is also well simulated with regard to the cup depth, at least in a practical sense. Improvement of simulation will be carried out by elaboration of the constitutive equation.
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Mun-Kyu CHOI, Hun-Mo KIM
2000 Volume 43 Issue 3 Pages
594-602
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper, we present a process analysis system that can analyze causes with expert proficiency for a given result after undergoing various processes. Also, the plasma etching process that affects yield is controlled, using an adaptively trained neural network, to predict an output before the real process. In modeling, a method that utilizes the trend history of input data shows considerable advantage in both learning and prediction. The research regards CD (Critical Dimension), which is crucial in high integrated circuits, as the output variable of the model. Based on the model using this method, we propose an algorithm to analyze and control the effect of input variables for predicted defects. Both the weight of input variables and their trend history are considered in for this algorithm.
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Jahng-Hyon PARK, Se-Hee RYU, Kyoungsu YI
2000 Volume 43 Issue 3 Pages
603-609
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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For an automated transportation system like PRT (Personal Rapid Transit) System or IVHS, an efficient vehicle-merging algorithm is required for smooth operation of the network. For management of merging, collision avoidance between vehicles, ride comfort, and the effect on traffic now should be considered. This paper proposes an unmanned vehicle-merging algorithm that consists of two procedures. First, a longitudinal control algorithm is designed to keep a safe headway between vehicles in a single lane. Secondly, 'vacant slot and ghost vehicle' concept is introduced and a decision algorithm is designed to determine the sequence of vehicles entering a converging section considering total traffic flow. The sequencing algorithm is based on fuzzy rules and the membership functions are determined first by an intuitive method and then trained by a learning method using a neural net. The vehicle-merging algorithm is shown to be effective through simulations based on a PRT model.
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Kazuo YOSHIDA, Keiyo HATANO
2000 Volume 43 Issue 3 Pages
612-617
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper, we discusse an intelligent control method of integrated the cubic neural networks (CNN) proposed by one of the authors proposed. The CNN consists of multilevel parallel processing networks at different degrees of abstraction. By an appropriate qualitative level control, the CNN enables us to realize robust control. In this study we deal with nonlinear or multipurpose control problems via intelligent control of integrated CNNs. As a practical example, the integrated CNN is applied to the swing up and inverted control of pendulum. A neural network integrator is used for integrating swinging up and inverting CNN controls. The genetic algorithm is used for integrating the CNNs for stand up control of the pendulum. As a result of simulation and experiment, it is demonstrated that the integrated CNN controller can perform the stand up control of the pendulum without touching the cart position limit. It is also shown that the integrated CNN controller can perform the stand up control of a pendulum even in the case of sensing failure of the pendulum angle.
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Shinsuke NAKAGAWA, Takashi YAMAGUCHI, Hidehiko NUMASATO, Haruhiko HOSO ...
2000 Volume 43 Issue 3 Pages
618-624
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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We have developed a magnetic head positioning control method of a hard disk drive under conditions of variable parameters and disturbances. It consists of model following control for feed forward compensation and and-windup control for feedback compensation. By using anti-windup control for a feedback controller, slow and large transient responses near the target position are avoided and the actuator settles more quickly on the target position.
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Hidekazu NISHIMURA
2000 Volume 43 Issue 3 Pages
625-631
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper, the author proposes a control method that can bring a system to an arbitrary hal state even if the input is already saturated, by adopting a hyperbolic tangential function that describes the input limitation. Furthermore, by using the derivative of the function, the obtained input becomes continuous at terminal points of an initial time and a hal time. This formulation of the input limitation can be described by a linear parameter-dependent system and the final-state control with error learning can be applied to the system. The effectiveness of this method is verified by carrying out both simulations and experiments of the swing-up motion control of a cart and inverted pendulum system, whose cart displacement is limited. This method does not require precise determination of the hal time and can generate a continuous, smooth, feedforward control input when the output of the actuator is limited.
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Takeshi MIZUNO, Yusuke HARA
2000 Volume 43 Issue 3 Pages
632-637
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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This paper investigated the control system design of a repulsive magnetic bearing using the motion control of permanent magnets. In the repulsive magnetic bearing system, the radial motions of the rotor were passively supported by repulsive forces between ring-shape permanent magnets ; the axial motion was actively controlled by the motion control of the permanent magnets with a pair of voice coil motors. Two control schemes, PD control and state-variable feedback, were applied for the stabilization of the axial motion. The results showed that the dynamic performance of the controlled system could be adjusted more flexibly by state-variable feedback.
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Hirokazu NOBORISAKA, Hiroaki KOBAYASHI
2000 Volume 43 Issue 3 Pages
638-644
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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This paper describes design of a tendon-driven articulated finger hand that has similar properties to those of a Remote Compliance Center (RCC) device, i. e., it generates resolved displacements for disturbance forces applied to a grasped object and it can also adjust the elastic coefficients semiactively using the nonlinear elasticity of tendons. After introducing some basic results with respective to a tendon-driven mechanism, the stiffness matrix which relates the restriction forces applied to a grasped object to the small displacements of the object is derived. It is shown that more than six tendons are necessary, for each finger to adjust all elements of the stiffness matrix using only the nonlinear mechanical elasticity of tendons. After that, the wiring and pulley system is designed that cannot only drive the fingers freely without loosing the tension forces but also can diagonalize the stiffness matrix and adjust the elements. It is also shown that the hand can grasp different sized objects without losing the property using the tendon redundancy.
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Hideyuki SAWADA, Shuji HASHIMOTO
2000 Volume 43 Issue 3 Pages
645-652
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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This paper introduces a mechanical model of human vocal system to realize human-like speech under an auditory feedback control. While various ways of vocal sound production have been actively studied so far, we are constructing a phonetic machine having a vocal chord and a vocal tract with an auditory system. By imitating the human learning procedure of voice acquisition, a mechanical construction of a human vocal system is considered to generate natural voice so that it can be advantageously applied to a singing voice production.
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Qing-jiu HUANG, Kenzo NONAMI, Hiroaki UCHIDA, Yoshihiko IGUCHI, Takaak ...
2000 Volume 43 Issue 3 Pages
653-663
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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It is very difficult to make a mathematical model of the multi-leg locomotion robot and to design a motion control system for it, because of the robot's large-scale nonlinear property. In this paper we propose a new approach for dealing with such a large-scale nonlinear system and realizing the stable walking in various environments by using correction of trajectory planning with recurrent neural network (RNN) based on a CAD model. Firstly, a CAD model of a quadruped locomotion robot was developed using DADS/Plant, which is a software that treats multi-body dynamics. Then, the centralized hierarchical neural network (HNN) controller, which is used to make the robot realize a desired motion, was designed on the basis of this CAD model. Furthermore, on the basis of the same CAD model, the superior RNN controller, which is used to correct the trajectory planning of each joint of the robot, was utilized to solve such problems as the stability of the center of gravity of the robot body and the coordination of each robot foot during walking on an irregular terrain with obstacles and stairs. Consequently, the autonomous locomotion of the robot was realized. Simulations and experiments were performed to verify the effectiveness of the presented approach.
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Kazuo YOSHIDA, Takayuki USUDA
2000 Volume 43 Issue 3 Pages
664-670
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper we present an intelligent control method that uses a cubic neural network (CNN) to improve the stability of a forklift while it is being driven Since the forklift, a kind of human-machine system, has a high center of mass, the human driving safety to prevent it from falling forward is an important problem. Two kinds of controllers for reducing vibration and preventing the forklift from falling forward are designed by the CNN intelligent control method and evaluated by evaluators that can interpret and evaluate human operatiorl in each level of CNN. Finally, these controllers are integrated by an integrator. From numerical simulations and experiments it is shown that the proposed integrated intelligent control method using CNN can reduce vibration and at the same time prevent a forklift from falling forward.
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Chi-Ying LIANG, Huei PENG
2000 Volume 43 Issue 3 Pages
671-677
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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A framework for string-stability analysis is formulated in this paper. First, uniform string will be analyzed. We will then present analysis results on strings of mixed vehicles. A String-Stability Margin (SSM) index is defined in this paper to give a quantitative measurement of any ACC design. Simulation results using MATLAB and a microscopic traffic simulator will also be given to demonstrate the effectiveness of ACC systems on traffic smoothness.
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Peter B. BEDA
2000 Volume 43 Issue 3 Pages
678-683
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In the recent years the use of the space shuttle technology leads to numerous new concepts of space missions and structures. A group of them are the experiments with Tethered Satellite Systems (TSS) consisting of two subsatellites (the shuttle itself and a probe for example). Such flights can be designed for various purposes like the exploration of the upper portion of the atmosphere for planets like Earth, Mars etc., which is impossible with other equipment. When the orbit eccenticity is zero the stationary position of the TSS (its number and location) is determined by distance between the subsatellites l. This paper investigates how attitude dynamics can be controlled for eccentric orbits with a simple feedback of the pitch angle in form l=i(g). The method is partly analytic based on Lagrangian formulation of the equation of motion, nonlinear analysis and nonlinear oscillation theory. Numerical simulations are also performed to study the effect of the control and ) justify the results.
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Itsuro KAJIWARA, Raphael T. HAFTKA
2000 Volume 43 Issue 3 Pages
684-690
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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Technology on Micro Air Vehicles (MAVs) has been attracting the attention for aircraft's researchers. Multidisciplinary optimization is expected to achieve the higher performances and the stability for MAVs. This paper proposes the simultaneous optimization methods of the aerodynamics based on the aircraft shape and the control system. The purpose of the optimization is to reduce the control energy and the roll angle under the constraints with respect to the robust stability. The control system is composed of the H
2 and the mixed H
2/H
∞ controllers. Efficient optimization procedures based on a two step procedure for the H
2 optimization and LMI solver for the H
2/H
∞ control are developed in this study. Both aircraft shape and control design variables are simultaneously optimized by the proposed methods. Effectiveness of the proposed approaches is verified with some numerical applications.
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Bin FENG, Nobuyoshi MORITA, Takao TORII, Shigemi YOSHIDA
2000 Volume 43 Issue 3 Pages
691-696
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper, we propose a new method, the comprehensive mass distribution method, for an optimum balancing of the shaking force and shaking moment of spatial RSSR mechanism (a spatial four-bar mechanism with two Revolute and two Spherical joints). The method consists of two parts:(1) optimizing the mass distribution of the link itself, and (2) adding weights to the end of the link. A genetic algorithm as an optimization technique is used in this study. Some examples are given, and the results show that the balancing effectiveness of the new method is better than that achieved by the conventional method and the weight of the mechanism is decreased. The shapes of optimized links are obtained using the small element superposing method.
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Natsuko HORI, Kazuto SETO
2000 Volume 43 Issue 3 Pages
697-703
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper, we proposes a new control technique for reducing the vibration of a flexible space structure arranged in series, such as a pair of solar paddles of the space station. In this study, the reduced order model for controlling the first and the second bending modes of the structure is derived. For designing the controller, the filtered Linear Quadratic Optimum control theory (LQ control theory) is used. The reduced order model and the controller design are verified by simulations and experiments.
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Jr.Billie F. SPENCER, Erik A. JOHNSON, Juan C. RAMALLO
2000 Volume 43 Issue 3 Pages
704-711
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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Consideration of near-source, high velocity, long-period seismic pulses, as were recorded during the Northridge and Kobe earthquakes, has taught engineers and researchers that ground motions due to such earthquakes can be difficult to accommodate. This paper discusses a base isolation system using "smart" dampers, such as magnetorheological fluid dampers, that can adapt to, and protect against, seismic excitatiorn of different characteristics. A linear, two degree-of-freedom, lumped-mass model of a base-isolated budding is used as the testbed for this study. Linear viscous dampers are shown to have an optimal damping level for several design earthquakes to achieve minimum peak accelerations. A study of a family of controllers for the smart damper is used to find an "optimal" isolation system over the suite of ground motions considered. This "optimal" system further decreases the base drift compared to the "optimal" linear viscous damper without increasing the accelerations imparted into the superstructure. The "smart" damper is shown to be a most effective alternative for a broad class of earthquakes including near-source events.
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Hideki HARAMOTO, Kazuto SETO, Yuji KOIKE
2000 Volume 43 Issue 3 Pages
712-718
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this paper we propose an active vibration control method for multiple high-rise buildings arranged in parallel. According to the proposed method, some flexible buildings connected by control devices called "active control bridges", are controlled through active interactions among them. This method has the merit of achieving sufficient control force under low frequency. Using this method, it is possible to control vibrations of super-tall buildings against strong winds and large earthquakes. In this study, three model buildings are connected with two actuators. The objective of this research is to control the first bending and torsional modes of each building using this method. The control effect is evaluated by exciting the base of the structures by time response and measuring the frequency response of the structures. Both simulation and experimental results show that fairly good control performance has been achieved by this method.
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Zi-he LIU, Kenzo NONAMI
2000 Volume 43 Issue 3 Pages
719-725
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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In this study, we focus on the error of the estimated frequency of disturbance and present a new adaptive multiple frequency tracking and modification law. The relationship between the estimated frequency error and the output level after using a low-pass Alter is discussed in detail. Also an algorithm for multiple frequency estimation is proposed, which is insensitive to observation noise and proves the asymptotic stability of the proposed adaptive nonlinear algorithm and the adaptive multiple frequency tracking method theoretically. The results of simulation show that when the frequency estimated by the difference equation method approaches the true value, the output error converges to zero (or equilibrium point) asymptotically. This corresponds to the asymptotic stability condition. The effectiveness of this method and the theoretical proof are verified by simulation. The experimental results show that the proposed algorithm is effective for suppressing unbalanced vibration.
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Kimihiko NAKANO, Yoshihiro SUDA, Shigeyuki NAKADAI
2000 Volume 43 Issue 3 Pages
726-731
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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A new method to achieve self-powered active vibration control is proposed. The proposed system produces continuous control input using energy absorbed by a damper and does not require external energy. In the previous self-powered system, the actuator was controlled by the on-off controller and could not produce continuous control input. This induces chatter for high frequency motion and degrades its performance. To examine the performance of the new system, the authors fabricated an experimental setup. Energy regenerated by the damper is accumulated in the condenser and the actuator uses it for active control. The variable resistor whose resistance is controlled by a computer is installed in the circuit of the actuator and this produces continuous control input. The experiments Show that the proposed selfpowered active control has better isolation performance than the previous on-off, semiactive and passive systems.
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Matthew DUNBABIN, Andy C.C. TAN
2000 Volume 43 Issue 3 Pages
732-739
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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Tne effect that temperature dependant piezoceramic properties have on the active vibration control of a light flexible structure can be of considerable importance in reallife systems. Piezoelectric properties can vary significantly with moderate changes in temperature, hence affecting their control authority. By varying the operating temperature of a flexible structure (cantilever beam) fitted with piezoceramic actuators, this investigation explores the influence of temperature on the damping and natural frequency of the system using velocity feedback control. Experimental results show the dynamic properties of the system are not only dependent on the piezoceramics variation with temperature, but additionally on the type of adhesive used to bond the ceramics to the structure. This can causes significant nonlinear behaviour in system damping. These results indicate that for systems operating over a large temperature range, unless adequate pre-thought is employed, unanticipated damping and control characteristics may arise.
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Shine-Tzong HO, Hiroshi MATSUHISA, Yoshihisa HONDA
2000 Volume 43 Issue 3 Pages
740-747
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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Electrical circuits with piezoelectric elements were used to suppress the vibration of a beam passively. The system was simplified by modeling an electromechanical circuit containing a transformer with a simple equivalent electrical circuit by using a mathematical equation. The effective mechanical impedance for the piezoelectric element shunted by an arbitrary circuit was also expressed in the mathematical equation. It was found that the effective impedance conversion coefficient must be increased in order to use electric elements of conventional size. To increase the conversion coefficient by connecting piezoelectric elements, an arrangement similar to that of a multilayered ceramic capacitor was suggested. As an application, a resistor shunted by the piezoelectric element could increase the loss factor and change the natural frequency of the beam. The added loss factor depends on the device coupling coefficient, while the frequency of the peak of the loss factor curve depends on the resistor. The device coupling coefficient for a large added loss factor was discussed, in contrast to the material coupling coefficient which is usually discussed. Finally, experiments using resistive shunt circuits were conducted to verify simulation results.
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Shemin ZHANG, Nobuyoshi MORITA, Takao TORII
2000 Volume 43 Issue 3 Pages
748-754
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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We propose a relationship between the response of a forced vibration model having six degrees of freedom for any planar unbalanced linkage and its excitation caused by the shaking force/moment of a linkage. We also present a criterion which expresses the compromised value of response ill terms of counterweight mass parameters used as an objective function in optimum balancing. The effects oil Shaking force/ moment and on vibration response predicted by using the new Criterion are compared with those obtained by a classical method. Results show that the vibration response of the system predicted by the new approach is much smaller than that obtained by the classical method. The measured responses of the system at three points also show that the new method is effective in reducing vibration response.
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Karen E. GROSSER, William E. SINGHOSE
2000 Volume 43 Issue 3 Pages
755-761
Published: September 15, 2000
Released on J-STAGE: February 18, 2008
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Telerobotic arms with flexible dynamics respond to operator commands in a somewhat unpredictable manner. The deflections and oscillations can pose a safety hazard if the arms are operated aggressively. On the other hand, they can decrease productivity if the operator acts in an overly conservative manner to accommodate the behavior. The nexible dynamics can be reduced through the use of input shaping;however, a time lag is introduced in the system response. This paper presents input shaping methods that reduce the apparent lag experienced by the operator.
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