Signal Processing Technique For Fiber Grating Sensor System

Under the knowledge of interferometric phase demodulation for fiber Bragg grating sensing system, a new continuous distributed strain demodulation system with Michelson interferometer was proposed. It is propitious to measure the dynamic strain and manipulate the sensitivity of the sensing system. The system is controlled based on LabVIEW programming. The sensing signals were captured and processed by the virtual lock-in amplifier. A feedback system for FBG robot-hand controlling based on LabVIEW was developed.The research works are illustrated as follows:Firstly, by using fiber Bragg grating as a mirror of sensing arm of Michelson interferometer, a new sensing demodulation scheme is designed. The optical paths from the different points in the FBG can be determined precisely. The principle of the interferometer is introduced in detail. The relation between the strain and the associated phase is established. The sensitivities related to the different scanning points were analyzed theoretically and observed experimentally.Secondly, aiming at fiber Bragg grating sensor interferometric demodulation technology, a virtual instrument system based on LabVIEW is introduced. The output signal data from the scan interferometer can be processed with the virtual narrow band-pass filter, the lock-in amplifier, and the relative phase can be determined finally. The change of the strain could be displayed on screen and saved into Excel sheet automatically.Thirdly, the feedback control system for FBG manipulator running based on LabVIEW is designed. The system is able to warn and home, or even lock the manipulator when the sensing value close or exceed the set thresholds.