Abstract
With the improvement of performance in the ultra-precision manufacturing engineering, the requirements for vibration isolation have become more stringent. In order to obtain a wider effective bandwidth and a higher performance of a multi-DOFs active vibration isolation system (AVIS), active hybrid control (AHC) technology is applied in this paper. AHC technology comprises a feedback active control (FBAC) technology and a feedforward active control (FFAC) technology. Absolute velocity feedback is employed to establish a sky-hook damping technology in FBAC technology. Velocity feedforward of base platform is adopted to build a lead-lag phase compensation (LLPC) technology in FFAC technology. Further, a coordinate vector conversion from unit level to system level is mentioned to describe the dynamic characteristic of the six DOFs AVIS applied in the ultra-precision field. And with the assistance of the transformed coordinate vector, the dynamic model of system level is built. Based on the establishment of the dynamic model and the research of AHC, an experimental platform which constitutes three vibration isolators and a real-time active control system is set up. The experimental results indicate that the amplitude of the resonant peak is further reduced significantly, compared to the general feedback control. And simultaneously active effective bandwidth is extended. AHC technology with sky-hook damping algorithm and LLPC control algorithm is verified to be more effective.
Highlights
Vibration isolation device is used to realize high isolation performance of multi-DOFs and broad frequency band in precision equipment, such as wafer stepper lithography machines, atomic force microscopes (AFM), space telescopes and interferometers, and laser communication system [1]
According to the control structure, active control strategy can be classified into feedback control and feedforward control
To describe the dynamic characteristic of the six DOFs active vibration isolation system (AVIS) applied in the ultra-precision field more clearly, a coordinate vector conversion from unit level to system level is mentioned firstly according to the layout of the ultra-precision AVIS
Summary
Vibration isolation device is used to realize high isolation performance of multi-DOFs and broad frequency band in precision equipment, such as wafer stepper lithography machines, atomic force microscopes (AFM), space telescopes and interferometers, and laser communication system [1]. A passive isolation system offers a simple and reliable means of protecting precision equipment from a vibration environment, it has performance limitations since its controllable frequency range is limited [2]. With the continuous improvement of the ultra-precision machining and manufacturing equipment, the performance requirement for low frequency and ultra-low frequency vibration isolation is more stringent. According to the control structure, active control strategy can be classified into feedback control and feedforward control. If we try a high-gain feedback for position control, the control system
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