231 Study On Super-long-period Active Isolation System

2003 ◽  
Vol 2003 (0) ◽  
pp. _231-1_-_231-6_
Author(s):  
Keisuke Minagawa ◽  
Hironori Hamazaki ◽  
Satoshi Fujita ◽  
Takafumi Fujita ◽  
Osamu Takahashi
Keyword(s):  
Isolation System ◽  
Long Period ◽  
Active Isolation

Study on Super-Long-Period Active Isolation System Considering Relatively Long Period Seismic Wave

2004 ◽  
Vol 2004.5 (0) ◽  
pp. 269-270
Author(s):  
Tomo Sasaki ◽  
Satoshi Fujita ◽  
Minagawa Keisuke ◽  
Takafumi Fujita ◽  
osamu Takahashi
Keyword(s):  
Seismic Wave ◽  
Isolation System ◽  
Long Period ◽  
Active Isolation

Fundamental Study on the Super-Long-Period Active Isolation System

2005 ◽  
Vol 128 (4) ◽  
pp. 502-507
Author(s):  
Keisuke Minagawa ◽  
Satoshi Fujita
Keyword(s):  
Control System ◽  
Seismic Isolation ◽  
Seismic Waves ◽  
Control Force ◽  
Natural Period ◽  
Isolation System ◽  
Hydraulic Actuators ◽  
Long Period ◽  
Active Isolation ◽  
Rubber Bearings

Background: Since the Hanshin-Awaji Earthquake Disaster, the number of isolated structures has been greatly increased. The natural period of the isolation system is designed around 3s, because the predominate period of observed seismic waves is usually 0.1 to 1s. However, relatively long period seismic waves have been observed in various earthquakes, and the resonances of long-period structures, such as high-rise buildings, during earthquakes have been reported at the same time. Therefore the natural period needs to be extended. When extending the natural period of the isolated structure using rubber bearings, its stiffness needs to be reduced. It is more difficult to extend the natural period of the isolation system than the conventional system because of a buckling problem. Therefore we propose a super-long-period active seismic isolation system as a new method for extending the natural period of the isolated structure. This system consists of rubber bearings and hydraulic actuators. Method of approach: In this study, we designed a control system by using the model matching method. This is one of the classical control system design methods. Additionally we applied a genetic algorithm (GA) to select parameters of a transfer function. Results: The system designed by applying the GA could reduce response acceleration sufficiently compared with the input acceleration. Further waveforms of the response acceleration retain almost straight forwardly, so this indicates good performance of isolation. Therefore, application of super-long-period active isolation is an effective technique to improve the performance of isolation. However, the control forces are big, and the system needs 95.5×106N for the El Centro NS wave as control force. This force is equivalent to 21 actuators that are used in a large shake table, so there are few possibilities to realize active isolation. Conclusion: The required control force of hydraulic actuators is big, although the super-long-period active isolation system possesses good performance of isolation compared with the conventional isolation system. Therefore it is difficult to apply this isolation system to the real structure. However, the problem regarding requirements of the actuator should be solved because of the realization of an active seismic isolation system. Therefore, we will examine for the parameters of the system and semi-active isolation system.

Isolation Performance of Intelligent Seismic Isolation System Using Air Bearing

2009 ◽  
Author(s):  
Satoshi Fujita ◽  
Keisuke Minagawa ◽  
Mitsuru Miyazaki ◽  
Go Tanaka ◽  
Toshio Omi ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Air Bearings ◽  
Natural Period ◽  
Isolation System ◽  
Vertical Excitation ◽  
Long Period ◽  
Isolation Performance

This paper describes three-dimensional isolation performance of seismic isolation system using air bearings. Long period seismic waves having predominant period of from a few seconds to a few ten seconds have recently been observed in various earthquakes. Also resonances of high-rise buildings and sloshing of petroleum tanks in consequence of long period seismic waves have been reported. Therefore the isolation systems having very long natural period or no natural period are required. In a previous paper [1], we proposed an isolation system having no natural period by using air bearings. Additionally we have already reported an introduction of the system, and have investigated horizontal motion during earthquake in the previous paper. It was confirmed by horizontal vibration experiment and simulation in the previous paper that the proposed system had good performance of isolation. However vertical motion should be investigated, because vertical motion varies horizontal frictional force. Therefore this paper describes investigation regarding vertical motion of the proposed system by experiment. At first, a vertical excitation test of the system is carried out so as to investigate vertical dynamic property. Then a three-dimensional vibration test using seismic waves is carried out so as to investigate performance of isolation against three-dimensional seismic waves.

scholarly journals Study of Active Isolation System with Feedforward Control.

1992 ◽  
Vol 58 (552) ◽  
pp. 2381-2387 ◽  
Author(s):  
Masashi YASUDA ◽  
Takahide OSAKA ◽  
Masao IKEDA
Keyword(s):  
Feedforward Control ◽  
Isolation System ◽  
Active Isolation

Dynamic Analysis of an Active Flexible Isolation System

2003 ◽  
Author(s):  
Kongjie Song ◽  
Lingling Sun ◽  
Yuguo Sun ◽  
Bing Zhang
Keyword(s):  
Active Control ◽  
Power Flow ◽  
Low Frequency ◽  
Coupled System ◽  
Isolation System ◽  
Active Isolation ◽  
Dynamic Modification ◽  
Mobility Method ◽  
Feed Forward Controller ◽  
Flexible Foundation

This paper is dedicated to the structure dynamic modification in an active isolation system supported by a flexible foundation, in order to improve the effectiveness of the active control strategy. The coupled vibration between machine-sprung and flexible foundation substructure is examined, using the subsystem mobility method. The vibration transmission in this coupled system is presented in terms of power flow. The interaction between structure controlled and the adaptive feed-forward controller is investigated theoretically. The numerical results show that: the location of the active mounts and the first mode frequency of the flexible foundation have evident influence on the effect of active control, especially at low-frequency band.

Fundamental Study on the Super-Long-Period Active Isolation System

2004 ◽  
Author(s):  
Keisuke Minagawa ◽  
Satoshi Fujita
Keyword(s):  
Control System ◽  
Seismic Isolation ◽  
Seismic Waves ◽  
Model Matching ◽  
Fundamental Study ◽  
Natural Period ◽  
Isolation System ◽  
Long Period ◽  
Rubber Bearings ◽  
Classical Control

Since the Hanshin-Awaji Earthquake Disaster, the number of isolated structures has been greatly increased. The natural period of the isolation system is designed around 3 seconds, because predominate period of observed seismic waves is usually 0.1 to 1 second. However, relatively long period seismic waves have been observed in various earthquakes, and the resonance of long-period structures, such as high-rise buildings, during earthquakes have been reported at the same time. Therefore the natural period needs to be extended. When extending the natural period of the isolated structure using rubber bearings, its stiffness needs to be reduced. It is more difficult to extend the natural period of the isolation system than the conventional system because of its buckling problem. Therefore we propose a super-long-period active seismic isolation system as a new method for extending the natural period of the isolated structure. This system consists of rubber bearings and actuators. In this study, we designed a control system by using the model-matching-method. This is one of the classical control system design methods. We investigated the isolation performance by numerical analysis. In addition, we selected the optimal variables of transfer function using genetic algorithm.

Effects of Damper Force Ranges and Ground Motion Pulse Periods on the Performance of Semi-Active Isolation Systems

2003 ◽  
Author(s):  
Henri Gavin ◽  
Julie Thurston ◽  
Chicahiro Minowa ◽  
Hideo Fujitani
Keyword(s):  
Ground Motion ◽  
Large Scale ◽  
Base Isolation ◽  
Near Field ◽  
Shaking Table ◽  
Isolation System ◽  
Active Isolation ◽  
Isolation Systems ◽  
Fail Safe ◽  
Strong Ground

A large-scale base-isolated steel structural frame was tested at the shaking table laboratory of the National Research Institute for Earth Sciences and Disaster Prevention. These collaborative experiments featured auto-adaptive media and devices to enhance the performance of passive base isolation systems. The planning of these experiments involved determining appropriate device control methods, the development of a controllable damping device with fail-safe characteristics, and the evaluation of the performance of the controlled isolation system subjected to strong ground motion with pronounced near-field effects. The results of the planning study and their large-scale experimental confirmation provide guidelines for the development and implementation of auto-adaptive damping devices for full scale structures.

A Study of Active Vibration Isolation

1985 ◽  
Vol 107 (4) ◽  
pp. 392-397 ◽  
Author(s):  
N. Tanaka ◽  
Y. Kikushima
Keyword(s):  
Vibration Isolation ◽  
Control Method ◽  
Feedforward Control ◽  
Ground Vibration ◽  
Design Parameters ◽  
Isolation Method ◽  
Isolation System ◽  
Active Isolation ◽  
Active Vibration ◽  
Active Vibration Isolation

For the purpose of suppressing ground vibration produced by vibrating machines, such as forging hammers, press machines, etc., this paper presents an active vibration isolation method. Unlike conventional isolators, the active isolator proposed in this paper permits rigid support of the machines. First, the principle of the active isolation method is shown, and the system equations are derived. Secondly, the characteristics and the design parameters of the active isolation system are presented. Thirdly, from the point of view of the feedforward control method, the dynamic compensators are designed so as to sufficiently suppress the exciting force. Finally, an experiment is carried out to demonstrate that the active isolator is applicable for suppressing the ground vibration.

Sliding-Mode Control Algorithm for a Hard-Mounted Isolation System

2007 ◽  
Author(s):  
Yung-Peng Wang ◽  
Jen-Chieh Tsao
Keyword(s):  
Sliding Mode Control ◽  
Control Algorithm ◽  
Sliding Mode ◽  
Isolation System ◽  
Mode Control ◽  
Active Isolation ◽  
Ultra Precision ◽  
Passive Isolation ◽  
Isolation Systems ◽  
Isolation Performance

It is well known that the trend of current technology development is microscopic and ultra-precision, especially in the areas of semiconductor manufacturing, ultra-precision machining, MEMS, microbiology and nanotechnology. Hence, vibration becomes a significant problem in those fields. There are two types of vibration control techniques. One is passive isolation system; the other is active isolation system. Passive isolation system can provide better performance for higher frequencies. Active isolation system is used to improve the isolation performance for lower frequencies. However, passive isolation system has bad performance around the natural frequency. In addition, it cannot eliminate the effects of onboard disturbances. Therefore, active isolation system becomes the major technology in the applications of microvibration control for precision equipment. In practice, all active isolation systems are based upon a hybrid concept, combining a passive isolator for higher frequencies and a servo control system for lower frequencies. This combination allows for two significantly different configurations, which can be categorized as: soft-mounted isolation systems and hard-mounted isolation systems. The soft-mounted systems are inherently insensitive to resonance in the main structure below the isolators. Yet, they are sensitive to resonances in the isolated platform. The hard-mounted systems are extremely stiff and allows for large onboard disturbance forces without excessive motion. However, the major drawback with a hard-mounted system is that vibration isolation performance suffers from the passive-active compromise and is unable to come up to the optimal performance. In this paper, a sliding-mode control algorithm is developed for a hard-mounted isolation system with a piezoactuator. Based on the bounds of environmental vibrations and onboard disturbances, the sliding-mode control algorithm can make the hard-mounted isolation system achieve the optimal and robust performance of low vibration transmissibility and high stiffness. The results are verified by the numerical simulations.

Sign in / Sign up

Export Citation Format

Share Document