A Hybrid Add-on Damping Strategy for Self-Stabilization Nanopositioning System With High-Static-Low-Dynamic Stiffness Property

The inspection of micro/mini light-emitting diode (LED) display panels using industrial-level atomic force microscopes (AFM scanning head) demands a vibration isolator with high-ratio vibration reduction and high-precision positioning, in the presence of complex environmental disturbances. The motivation of this article is to combine the ability of passive and active damping methods to enhance the vibration isolation performance of the developed compliant self-stabilization system to further improve the inspection performance. This objective is achieved by modifying the system with a hybrid add-on damping (HAD) strategy that improves the vibration isolation in the resonant region. First, based on the analysis of the system, a HAD strategy is proposed to address the limitations of the passive-active vibration isolation strategy. Then, the design, modeling, and optimization of a flexure-based high-static-low-dynamics stiffness mechanism (FHSM) are demonstrated, which dampens the system without deteriorating the high-frequency transmissibility. Besides, an active bandwidth-limited damper (ABD) is developed to further enhance damping in the desired frequency range. Finally, a series of verification tests were conducted, including performance tests of vibration isolation and closed-loop positioning. The experimental results indicate that from 1 to 500 Hz, the vibration reduction ratio is achieved as 91% in the resonant region and over 94.5% in other frequencies. Besides, the steady-state positioning error is within <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\pm}$</tex-math></inline-formula>0.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\mu}$</tex-math></inline-formula>m with a 2.5 kg load capacity. All the results uniformly confirm that the proposed HAD has successfully damped the system to achieve a higher vibration reduction ratio.