Zhao, Jieru
(2024)
Compact Real-time Interrogation System for Distributed and Multiplexed Fiber Bragg Grating (FBG) Sensors Demodulation Applied on High Temperature and Vibration Measurements.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Real-time measurements of physical parameters like temperature, strain, and vibration are crucial for industrial, aerospace, and infrastructure monitoring applications. Optical fiber sensors, particularly Fiber Bragg Grating (FBG) sensor arrays, excel in high-spatial resolution measurements across a wide range of environments, from cryogenic to extreme high temperatures. Their stability, mechanical robustness, and immunity to electromagnetic interference make them ideal for these applications.
This dissertation explores the development of low-cost, compact, real-time sensor interrogation systems using tunable lasers and embedded systems for high-temperature sensing. The research focuses on real-time temperature measurement with FBG sensor arrays, controlled by a tunable laser and a heterogeneous FPGA/DSP system. The system incorporates signal conditioning circuits, an embedded microcontroller, and a graphical user interface (GUI), achieving accurate temperature measurements up to 910 °C over three weeks. Machine learning algorithms are used to enhance prediction accuracy, resulting in an average Mean Absolute Error (MAE) of 0.98 °C for temperatures around 810 °C. The FBG sensors demonstrate an average temperature sensitivity of 13.74 pm/°C. This embedded interrogator system offers a reliable and precise solution for real-time temperature measurement in harsh environments, suitable for implementation in microcontrollers or low-complexity field devices.
Additionally, the dissertation details the embedding of FBG sensors in aluminum parts using Ultrasonic Additive Manufacturing (UAM) for high-frequency vibration monitoring. Polyimide-coated optical fibers with FBGs are embedded in the parts, enabling strain measurements under vibration frequencies ranging from 1 kHz to 10 kHz. A high-speed interrogation system using a tunable Vertical-Cavity Surface-Emitting Laser (VCSEL) achieves a sampling rate of 120 kHz, detecting strains as low as 2.5 μɛ. Finite Element Analysis (FEA) is used to simulate strain responses under static and high-frequency vibration conditions, validating the system's performance. This integrated approach provides a robust solution for high-frequency vibration monitoring in aerospace, aeronautics, and energy applications. To further enhance system compactness, VCSEL control is integrated onto the embedded board, with temperature and current control managed through onboard analog circuits. This onboard control adjusts the VCSEL scanning wavelength by varying the voltage, combining optical and electronic components to make the system more compact and portable.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
6 September 2024 |
| Date Type: |
Publication |
| Defense Date: |
9 July 2024 |
| Approval Date: |
6 September 2024 |
| Submission Date: |
4 June 2024 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
93 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Electrical and Computer Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
FBG sensor, embedded system, high temperature measurement, vibration measurement, VCSEL |
| Date Deposited: |
06 Sep 2024 19:55 |
| Last Modified: |
06 Sep 2024 19:55 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/46475 |
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