Stability and performance limits for active vibration isolation using blended velocity feedback

2011 ◽  
Vol 330 (21) ◽  
pp. 4981-4997 ◽  
Author(s):  
N. Alujević ◽  
H. Wolf ◽  
P. Gardonio ◽  
I. Tomac
Keyword(s):  
Vibration Isolation ◽  
Performance Limits ◽  
Velocity Feedback ◽  
Active Vibration ◽  
And Performance ◽  
Active Vibration Isolation

Gain-Scheduled ℋ∞-Control for Active Vibration Isolation of a Gyroscopic Rotor

2015 ◽  
Author(s):  
Fabian B. Becker ◽  
Martin A. Sehr ◽  
Stephan Rinderknecht
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Linear Time ◽  
Displacement Sensors ◽  
Active Vibration ◽  
And Performance ◽  
Gyroscopic Effects ◽  
Gain Scheduled ◽  
Active Vibration Isolation

This paper deals with active vibration isolation of unbalance-induced oscillations in rotors using gain-scheduled H∞-controller via active bearings. Rotating machines are often exposed to gyroscopic effects, which occur due to bending deformations of rotors and the consequent tilting of rotor disks. The underlying gyroscopic moments are proportional to the rotational speed and couple the rotor’s radial degrees of freedom. Accordingly, linear time-varying models are well suited to describe the system dynamics in dependence on changing rotational speeds. In this paper, we design gain-scheduled H∞-controllers guaranteeing both robust stability and performance within a predefined range of operating speeds. The paper is based on a rotor test rig with two unbalance-induced resonances in its operating range. The rotor has two discs and is supported by one active and one passive bearing. The active support consists of two piezoelectric stack actuators and two collocated piezoelectric load washers. In addition, the rig is equipped with four inductive displacement sensors located at the discs. Closed-loop performance is assessed via isolation of unbalance-induced vibrations using both simulation and experimental data. This contribution is the next step on our path to achieving the long-term objective of combined vibration attenuation and isolation.

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.

scholarly journals Tilt Active Vibration Isolation Using Vertical Pendulum and Piezoelectric Transducer with Parallel Controller

2021 ◽  
Vol 11 (10) ◽  
pp. 4526
Author(s):  
Lihua Wu ◽  
Yu Huang ◽  
Dequan Li
Keyword(s):  
Piezoelectric Transducer ◽  
Vibration Isolation ◽  
Vertical Vibration ◽  
Open Loop ◽  
Negative Effects ◽  
Voltage Controller ◽  
Hysteresis Nonlinearity ◽  
Passive Vibration Isolation ◽  
Active Vibration ◽  
Active Vibration Isolation

Tilt vibrations inevitably have negative effects on some precise engineering even after applying horizontal and vertical vibration isolations. It is difficult to adopt a traditional passive vibration isolation (PVI) scheme to realize tilt vibration isolation. In this paper, we present and develop a tilt active vibration isolation (AVI) device using a vertical pendulum (VP) tiltmeter and a piezoelectric transducer (PZT). The potential resolution of the VP is dependent on the mechanical thermal noise in the frequency bandwidth of about 0.0265 nrad, which need not be considered because it is far below the ground tilt of the laboratory. The tilt sensitivity of the device in an open-loop mode, investigated experimentally using a voltage controller, is found to be (1.63±0.11)×105 V/rad. To compensate for the hysteresis nonlinearity of the PZT, we experimentally established the multi-loop mathematical model of hysteresis, and designed a parallel controller consisting of both a hysteresis inverse model predictor and a digital proportional–integral–differential (PID) adjuster. Finally, the response of the device working in close-loop mode to the tilt vibration was tested experimentally, and the tilt AVI device showed a good vibration isolation performance, which can remarkably reduce the tilt vibration, for example, from 6.0131 μrad to below 0.0103 μrad.

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