Smart Monitoring of System Thermal Properties Through Optical Fiber Sensors and Augmented Reality

The development of space systems shall satisfy the strict requirement of maintaining high performance while operating in hostile environments. Optical fiber is a technology able to address this demand. Fiber Bragg Grating (FBG) sensors, in particular, provide the optimum balance among simplicity of use, cost and performance. They can guarantee both punctual and distributed measures of several physical parameters, while assuring low invasiveness and immunity to electromagnetic disturbs. In consideration of these unique properties, the article provides an overview about the experimental activities conducted at Politecnico di Torino on FBG applications for thermal monitoring. Indeed, in space systems integration thermal testing, characterization and monitoring are fundamental issues to assure successful missions. Thus, several aspects about optical fibers integration for temperature sensing have been investigated, studied and validated. In particular, the experimental tests analyzed the fiber integration and sensors calibrations methods, the application to thermal characterization, the development of a wireless telemetry system and data visualization through augmented reality. Regarding thermal characterization, FBGs were successfully used for multi-layer insulation testing. Specifically, multiple cycles in vacuum chamber has been conducted to quantify optical sensors advantages compared to traditional thermocouples. A reduced disturbance produced during sensors placement, an higher measurement accuracy and lower power consumption were the main outputs detected. Moreover, their use for temperature monitoring of electric motors and electromechanical actuators was tested. In this case, FBG worked in nominal condition even in presence of great electromagnetic disturbances and without showing any compatibility issues. In addition, the incredibly fiber versatility allowed to be used also for generating a network of surface thermal sensor, as well as to develop smart components by inserting the fiber directly during the manufacturing process. Two case studies were tested on composite structural supports made and on bricks developed through lunar regolith sintering. The sensorized specimens showed an exceptional sensitivity, thus demonstrating the huge potential for complex and remote components monitoring in hostile space environments. Finally, data visualization was verified, both through desktop application and augmented reality visors, for in-situ real time support with wireless connection. In conclusion, the study demonstrated the huge potential regarding FBG use in temperature measuring for space-critical applications, as well as data transmission and innovative visualization. The results described a complete experimental experience about optical sensors, from the hardware integration strategy to data visualization: an innovative source of data for smart and future space systems development.