Optical phase estimation for a patch-type extrinsic Fabry–Perot interferometer sensorsystem and its application to flutter suppression

Abstract

An optical phase tracking technique for an extrinsic Fabry–Perot interferometer (EFPI)is proposed in order to overcome interferometric non-linearity. The basic ideais utilizing strain rate information, which cannot be easily obtained from theEFPI sensor itself. The proposed phase tracking system consists of a patch-typeEFPI sensor and a simple on-line phase tracking logic. The patch-type EFPIsensor comprises an EFPI and a piezoelectric patch. An EFPI sensor itself hasnon-linear behavior due to the interferometric characteristics, and a piezoelectricmaterial has hysteresis. However, the composed patch-type EFPI sensor systemovercomes the problems that can arise when they are used individually. The proposedsystem can extract vibration information from severely distorted EFPI sensorsignals. The dynamic characteristics of the proposed phase tracking system wereinvestigated, and then the patch-type EFPI sensor system was applied to the activesuppression of flutter, dynamic aeroelastic instability, of a swept-back composite platestructure. The real time neural predictive control algorithm effectively reduces theamplitude of the flutter mode, and 6.5% flutter speed enhancement for the aeroelasticsystem was obtained by integrating smart materials into advanced structures.