Switching Control in Vibration Isolation Systems

Abstract

In this paper, a switching control approach for active vibration isolation systems is proposed. The switching involves two regimes. In the first regime, no feedback control is applied thereby giving a low sensitivity to noise. In the second regime, active control induces improved disturbance rejection properties, but at the cost of increased noise sensitivity. Conditions for the stability of the switching closed-loop system are formulated whereas the stability analysis provides design rules for tuning the switching controller. Given this novel active vibration isolation approach, improved isolation performance is obtained with substantially less control authority in comparison to the case of linear (or non-switching) feedback control. Performance analysis is based on multi-resolution time-frequency analysis using measurements taken from a commercial vibration isolation system. Index Terms-Absolute stability, discontinuous variable gains, input-to-state stability, switching systems, vibration isolation, wavelet analysis.

Experimental estimation of transmissibility matrices for industrial multi-axis vibration isolation systems

“…Band-pass filters are applied in the signal conditioners to prevent aliasing and to suppress sensor noise. The transformed signals u, y represent base frame and payload motion, respectively, expressed in the same Cartesian coordinate frame, see (1).…”

“…Vibration isolators are widely used in high-precision systems, such as wafer scanners [1], scanning tunneling microscopes [2,3], and measurement systems in general [4,5]. These isolators are used to isolate machinery from floor and base frame vibrations.…”

“…Bode magnitude plot of the compliance matrix C. solid gray: measured FRF, dashed black: fitted parametric model.coordinates from the CoG, see(1). Furthermore, each air mount is modeled as a combination of three springs k x,i , k y,i , k z,i and three dampers (d x,i , d y,i , d z,i ), with i ∈ {1, 2, 3, 4}, see Figure 1b.…”

Desired Compensation Adaptive Robust Control of an Active Vibration Isolation System

“…The modal damping can be realized under the mild condition by using piezoelectric Smart Discs made by piezoelectric material [22], and the robust stability can be retained based on a simple kinematic model rather than a complex dynamic model with specific parameters of the system. Heertjes et al proposed a switching control method with two regimes to enhance both the steady-state noise properties of the passive isolation system and disturbance rejection properties of transients [23]. The transient oscillations can be removed from the velocity response, and the steady-state noise can be avoided at small velocity by sky-hook damping.…”

Evaluating performance of multivariable vibration isolators: A frequency domain identification approach applied to an industrial AVIS

“…Vibration isolators are widely used in high-precision systems (e.g. wafer scanners [1], scanning tunneling microscopes [2], [3], measurement systems [4], [5]) to isolate machinery from disturbances otherwise entering from the supporting structure or floor [6]. A well-known performance indicator for such isolators is the transmissibility function.…”