3A33 Development of an active isolation system using the reference mass of a two DOF system(The 12th International Conference on Motion and Vibration Control)

It is well known that the trend of current high-tech equipment and processes development is ultra-precision and high-speed. Thus, vibration becomes a significant issue for those high-tech equipment and processes. When the environmental vibration exceeds the requirements of the precision equipment, vibration control techniques should be employed to improve the accuracy and resolution of that equipment. 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 on the equipment. Therefore, active isolation system becomes the major technology in the applications of vibration control for precision equipment. In this paper, a modified hard-mounted isolation system is proposed to improve the performance of hard-mounted systems. In this system, a voice coil motor is placed in parallel with the passive element and used to eliminate the effects of onboard disturbances on the equipment. A piezoactuator is still utilized to isolate the environmental vibration from the equipment. Furthermore, an active control algorithm is developed to achieve the optimal performance of low vibration transmissibility and high stiffness. The results are verified by the numerical simulations.

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Commercialization of Active Isolation for Jet Aircraft

Volume 1A: 16th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc97/vib-4115 ◽

1997 ◽

Author(s):

Steve C. Southward ◽

Douglas E. Ivers ◽

Geoff C. Nicholson

Keyword(s):

Control System ◽

Vibration Control ◽

Acoustic Noise ◽

Development Program ◽

Flight Test ◽

Test Time ◽

Vibration Source ◽

Noise And Vibration ◽

Transmission Path ◽

Active Isolation

Abstract Active Noise and Vibration Control (ANVC) technology is a proven solution for noise and vibration problems in aircraft. The challenges in commercializing this solution range from the development issues of choosing the best actuation, sensor, and control technology to obtaining sufficient flight test time and satisfying FAA requirements. This paper examines significant case histories in the progression of the Lord active vibration control program from conception to market. Throughout the development program, several important discoveries were made regarding the performance, reliability, and economics of Active Isolation Systems (AIS) in jet aircraft. First, practical speaker-based solutions cannot achieve global acoustic noise cancellation for engine tones above about 200 Hz. A comparatively small array of structural actuators placed in the dominant transmission path, such as in or near the engine mounts, are capable of global cancellation in the cabin up to at least 500 Hz. Second, the performance is generally better when cabin microphones are used as error sensor inputs because the AIS control system can compensate for flanking paths better than if accelerometers are used as error sensors. Third, when the actuators are placed in the dominant transmission path and close to the vibration source, the control system will simultaneously achieve global acoustic noise reduction in the cabin and vibration reduction in the aircraft structure without affecting the engine casing vibration levels.

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Study of Active Isolation System with Feedforward Control.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C ◽

10.1299/kikaic.58.2381 ◽

1992 ◽

Vol 58 (552) ◽

pp. 2381-2387 ◽

Cited By ~ 4

Author(s):

Masashi YASUDA ◽

Takahide OSAKA ◽

Masao IKEDA

Keyword(s):

Feedforward Control ◽

Isolation System ◽

Active Isolation

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Dynamic Analysis of an Active Flexible Isolation System

Volume 5: 19th Biennial Conference on Mechanical Vibration and Noise, Parts A, B, and C ◽

10.1115/detc2003/vib-48544 ◽

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.

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

Problems Involving Thermal Hydraulics, Liquid Sloshing, and Extreme Loads on Structures ◽

10.1115/pvp2003-1819 ◽

2003 ◽

Cited By ~ 1

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.

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