Active Vibration Isolation of Metrology Frames; A Modal Decoupled Control Design

2005 ◽  
Vol 127 (3) ◽  
pp. 223-233 ◽  
Author(s):  
Marcel Heertjes ◽  
Koen de Graaff ◽  
Jan-Gerard van der Toorn
Keyword(s):  
Vibration Isolation ◽  
Isolation System ◽  
Single Input Single Output ◽  
Single Output ◽  
System A ◽  
Active Vibration ◽  
Single Input ◽  
And Performance ◽  
Six Degree Of Freedom ◽  
Active Vibration Isolation

For a six degree-of-freedom active vibration isolation system, a control strategy based on modal decoupling is proposed. This has the advantage of controlling the modal directions on a centralized single-input single-output basis. As a consequence, stability and performance can be imposed in each of the modal directions separately. An experimental demonstration is given using a dummy metrology frame. That is, a 1600 kg payload mass supported by three combined pneumatic and Lorentz controlled isolators. With this setup, two unstable modal directions resulting from a high center of gravity are stabilized without compromising performance in any of the remaining directions. In fact, performance in the remaining directions is enhanced using manual loop shaping.

Design of a VCM Actuator Using Halbach Magnet Array for Active Vibration Isolation System

2014 ◽  
Vol 945-949 ◽  
pp. 1465-1469 ◽  
Author(s):  
Myeong Hyeon Kim ◽  
Hyun Chang Kim ◽  
Dong Pyo Hong ◽  
Dae Gab Gweon
Keyword(s):  
Vibration Isolation ◽  
Voice Coil Motor ◽  
Force Density ◽  
Maximum Output ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Design Variables ◽  
Active Vibration ◽  
Six Degree Of Freedom ◽  
Active Vibration Isolation

This paper proposes the concept development and design of a VCM actuator for Active Vibration Isolation System (AVIS). Active vibration isolating method was constructed passive isolator and active isolator. Spring was used for isolating passively and actuator like voice coil motor was used for active isolating. The proposed active vibration isolating system could isolate a six degree-of-freedom disturbance effectively. In case of AVIS, payload is variable according to the type of instruments. Therefore, actuator should maintain uniform performance with payload change. The proposed VCM actuator satisfied this performance through relative relation between magnet array and coils. In addition, for maximizing actuator performance, actuator should generate large force density. Therefore, we apply the Halbach magnet array to proposed actuator. The Halbach magnet array helps with reinforcing magnetic flux field. The reinforced magnetic field takes a role to generate more powerful Lorentz force to isolate disturbance. Finally, in this paper, we propose the actuator that novel type using voice coil motor with the Halbach magnet array and optimize each design variables to generate maximum output. These AVIS can use to eliminate disturbance in Maglev stage. Maglev stage need AVIS to increase its performance is necessary. In the future, AVIS and Maglev system will be integrated.

System Identification and Multivariate Controller Design for a Satellite Ultraquiet Isolation Technology Experiment (SUITE)

2002 ◽  
Author(s):  
Alok A. Joshi ◽  
Won-jong Kim
Keyword(s):  
Vibration Isolation ◽  
Transfer Functions ◽  
Controller Design ◽  
Input Output ◽  
Linear Quadratic ◽  
Linear Quadratic Gaussian ◽  
Single Input Single Output ◽  
Single Output ◽  
Single Input ◽  
Six Degree Of Freedom

A mathematical model of a six-degree-of-freedom hexapod system for vibration isolation was derived in the discrete-time domain on the basis of the experimental data obtained from a satellite. Using Box-Jenkins model structure, the transfer functions between six piezoelectric actuator input voltages and six geophone sensor output voltages are identified empirically. The 6×6 transfer function matrix is symmetric, and its off-diagonal terms indicate the coupling among different input/output channels. Though the coupling was observed among various input/output channels up to 10 Hz, the single-input single-output (SISO) controllers were designed neglecting the effect of coupling. The SISO controllers demonstrated limited performance in vibration attenuation. Using multi-input multi-output (MIMO) control techniques such as Linear Quadratic Gaussian (LQG) and H∞, high-order controllers were developed. The simulation results using these controllers obtain 33 dB, and 12 dB attenuation at 5, and 25 Hz corner frequencies, respectively.

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