How Fiber Bragg Grating (FBG) Sensors Measure Up with Integrated Vehicle Health Management (IVHM) Systems
Fiber Bragg Grating (FBG) Sensors are photonics-based sensors that provide a unique application for the measurement of structural health and usage monitoring that is designed to measure strain. This revolutionary evolution of machine quality measurement is fast becoming the alternative and powerful enhancement compared to the conventional electrical strain gauges that the industry still rely upon.
Structure longevity and operational safety and efficiency of any aircraft component, such as propeller blades, are determined by the stress and strain accumulated through usage, damage, age, and neglect. These types of machine degradation require up-to-date strain measurement techniques that are imperative for the success of machine lifetime maintenance costs from prototype design and testing to mission critical functionality and dependability.
What is the Fiber Bragg Grating Sensor Solution?
By utilizing FBG sensors, manufacturers and aircraft operators can more efficiently monitor the systems and subsystems within aircraft — or other systems — in order to determine State-of-Health (SoH) and Remaining Useful Life (RUL) to significantly lower operating and implementation costs for all types of aircraft.
- Proper fiber connection is supported by available connector types that are compliant to rigorous aerospace applications.
Aside from the obvious advantages of optical fibers, the following factors speak in favor of opting for an optical strain gauge:
- Measurement at high numbers of load cycles: Optical strain gauges allow stress tests at high numbers to load cycles (fatigue behavior) even with materials with high strains.
- Suited even to difficult operating and ambient conditions: Optical strain gauges ensure reduced wiring effort. Several optical strain gauges can be integrated in a single fiber. The optical measurement chain thus adapts to the individual requirements of a specific application. In addition, fiber multiplexing techniques through optical switching allow a next step in multiplying the number of sensors to be interrogated by a single system.
- Low weight of connection leads: Multiplexing and light-weight fiberglass of optical strain gauges reduce the weight of the connections. The effect of the intrinsic weight of the connections on the test results is only very small (in comparison to electrical strain gauges).
Additional Design Considerations for FBG Sensor Usage:
Mechanical:
- Affixing Fiber Optic (FO) cables on the structure being monitored.
- Ruggedization of the electronic components.
Electrical:
- Impressing FBG patterns on the FO cables
- Interfacing FBG sensors to a harness or via an Internet of Things (IoT) wireless transmitter, such as Ridgetop Group’s Sentinel IoT Wireless Module, for real-time data transmission of diagnostic readings
System-Level:
- Integration into a broad-based Integrated Vehicle Health Management (IVHM) System
Ridgetop Group’s Answer to Advanced Prognostic and Diagnostic FBG Sensor Possibilities
Sentinel Suite is a family of advanced modular prognostic and health management solutions for critical systems and can be coupled effortlessly with FBG sensor measurement devices. These solutions offer end-to-end monitoring of systems and comprise sensors, anomaly detection, prognostic reasoners, and graphical visualization tools.
Sentinel Suite IVHM functionality diagram
Ridgetop is certified as category 1A under the Defense Microelectronics Activity (DMEA) as part of the Trusted Supplier Program. Ridgetop has history of designing analog and mixed signal ICs for demanding applications in space satellites that are subjected to extreme temperatures and radiation. Our designs have utilized bulk CMOS, CMOS-SOI, and SiGe at process geometries down to 28 nm channel lengths. Radiation hardness is also a concern, and Ridgetop has addressed those requirements as well. A recent Ridgetop design was delivered to ON Semiconductor for the U.S. Air Force STELLAR Star Tracker.
Under contract to NASA, Ridgetop designed an effective 3-axis wireless rotational sensor. The RotoSense™ sensor has been tested on fast-spinning pinion gears on helicopter gear boxes, and also rolling stock for railroad safety improvements.