Modeling and Robust Active Control of a Pneumatic Vibration Isolator

Abstract

The accelerated development of precision technology has spurred an increasing requirement for vibration isolation equipment in recent years. Passive pneumatic vibration isolators are popular for avoiding vibration disturbance from the floor. However, the low-frequency resonance (13 Hz) is an unavoidable disadvantage when employing this approach. Therefore, this investigation develops an active pneumatic isolator with an active control method to suppress the resonant peak of the passive isolator. The linearized mathematical model is derived to obtain the nominal model of the isolation system in the beginning. Then, through the comparison between experiment and simulation, the unknown parameters of the rubber diaphragm can be identified. The active controller is designed to suppress the vibration disturbance based on the robust H 1 control theory. Hence, the weighting functions are selected appropriately according to desired specifications and taken into consideration during controller design procedures. Finally, the controller is obtained with off-line calculation, and the closed-loop system is achieved using the velocity feedback. The experimental results clearly reveal that the active control method improves the performance in the low frequency range and the resonant peak of passive isolator is reduced effectively.

Robust control of a novel active pneumatic vibration isolator through floor vibration observer

“…For this reason, researchers proposed many active control schemes to improve the passive pneumatic isolation performance. Several actuators are applied for the active vibration isolators, including electro-magnetic (Yoshioka et al, 2001;Zhang et al, 2002;Abakumov and Miatov, 2006), piezoelectric (El-Sinawi and Kashani, 2001;Pasco and Berry, 2006), and pneumatic actuators (Chen and Shih, 2007;Kato et al, 2007;Maekawa et al, 2007). These contributions demonstrate the feasibility of enhancing isolation performance when using active control techniques.…”

Mechanical design of buckled beams for low-stiffness elastic suspensions: Theory and application

“…A distinctive advantage of the gas spring concept is in the possibility to use these devices as actuators for the active control of the vibrations. 12,13 However, gas springs have marked disadvantages in their inherent complexity and the overall cost of the system, which limits their widespread application. Another family of solutions encompasses the wealth of mechanisms based on the superposition of two elastic springs, one with positive and the other with negative spring rate so as to produce a nearly zero result.…”

Control of input delayed pneumatic vibration isolation table using adaptive fuzzy sliding mode

“…PVI control by combining feedback linearization with a linear loop-shaping controller is adopted (Heertjes and van de Wouw, 2006). The mentioned active control techniques need the measurement of acceleration and not the pressure or mass flow rate (Chen and Shih, 2007). The compensation of the pneumatic isolation table fluctuation which is caused by switching of the feedforward compensator was considered (Shirani et al, 2012).…”