The study explores various fiber-optic sensing approaches, focusing on their application, implementation, and performance assessment for monitoring the structural health of concrete frameworks. It emphasizes the use of single-mode optical fibers due to their effectiveness in detecting microcracks, deformations, and temperature shifts in reinforced concrete. The investigation involved analyzing changes in optical characteristics through tests utilizing fiber Bragg grating (FBG) sensors embedded within concrete specimens exposed to mechanical loads and temperature fluctuations. Both graphical and quantitative analyses demonstrate that fiber-optic sensors enable real-time monitoring of stress and strain in concrete with high microstrain-level accuracy. Simulation work conducted using MATLAB confirmed the sensors’ responsiveness and long-term stability, particularly in detecting structural changes resulting from thermal effects and mechanical stress. Additionally, the thermal behavior of the sensors was examined using laser-based measurement systems in conjunction with Peltier modules. The research contributes to the advancement of intelligent SHM systems, aiming to enhance the durability and safety of civil infrastructure, especially in seismically active regions.

The object of this study is the deformation process in reinforced-concrete structural elements equipped with embedded fiber-optic sensors. The problem addressed corresponds to unresolved issues identified in previous studies – namely, the lack of standardized quantitative evaluation of accuracy and stability in fiber-optic deformation measurement. Despite high laboratory precision, existing methods show reduced long-term reliability, temperature-strain cross-sensitivity, and calibration inconsistency when applied to real structures. The main results show that fiber Bragg grating (FBG) and interferometric sensors achieved sub-micrometer deformation resolution with deviations below 2–3 με and long-term drift under 0.5%. Measurements remained stable under variable loading and temperature, confirming high reproducibility and electromagnetic immunity. These findings validate the hypothesis that optical wavelength shifts directly correspond to mechanical strain, ensuring reliable strain detection without recalibration. This effectiveness stems from the intrinsic photoelastic coupling and refractive-index sensitivity of the optical fiber, which provide nanometric resolution, corrosion resistance, and long-term operational stability. The proposed method is applicable for long-term monitoring of bridges, tunnels, and high-rise facilities exposed to environmental and cyclic stresses. Therefore, research on high-precision fiber-optic deformation measurement remains scientifically relevant for improving the safety and durability of modern civil engineering structures.

This paper provides a comprehensive overview of the progress in fiber-optic gyroscope technology, covering 260 key studies of the last ten years. A critical comparative analysis of fiber-optic gyroscope with alternative inertial sensors (Micro-Electro-Mechanical Systems, Hemispherical Resonator Gyroscope, Ring Laser Gyroscope) has been carried out. Confirming the unique advantages of fiber-optic gyroscope for autonomous navigation. Fundamental limitations of accuracy are considered in detail: temperature drifts, polarization noise, and Rayleigh backscattering. Modern hardware methods for suppressing these errors, including the use of photonic crystal and hollow fibers (Air-Core/Hollow-Core), are also considered in this work. The central place in the review is occupied by the analysis of the technological paradigm shift from bulky discrete circuits to hybrid integrated photonics (Indium Phosphide, Silicon Nitride, Lithium Niobate) and hybrid architectures to reduce weight and size characteristics. The role of artificial intelligence (Deep Learning, Long Short-Term Memory) methods in nonlinear drift compensation and calibration is discussed. The usage of the Brillouin effect and optomechanics promising areas are outlined, necessary to create a new generation of navigation systems operating in the absence of Global Navigation Satellite Systems signals.

Fibre-optic gyroscope (FOG) navigation systems are widely used in autonomous, aerospace, and terrestrial applications due to their high stability and independence from external navigation signals. While significant progress has been made in improving FOG performance at the sensor level, fewer studies have investigated the system-level impact of residual gyroscope errors, particularly during periods of GNSS unavailability. This study addresses that gap by analysing the accuracy and reliability of navigation in FOG-based inertial navigation systems under various operational modes: GNSS-aided, unaided, and intermittently aided. A mathematical model of navigation is implemented in a MATLAB/Simulink environment to assess error propagation. Performance is evaluated using practical metrics such as heading drift, position error accumulation, and recovery efficiency after GNSS signal restoration. Simulation results show that during unaided navigation, heading errors reach approximately 2–3 degrees over 600–900 seconds, while position errors grow to 40–80 meters during 300–600 seconds of GNSS outage. Upon GNSS reacquisition, error reduction of 80–90% is observed within 30–60 seconds. These results demonstrate that system-level modelling can significantly enhance navigation reliability without requiring modifications to the FOG hardware.

Fiber-optic gyroscopes (FOGs) are widely used in inertial navigation systems, but their accuracy can be significantly affected by temperature fluctuations and mechanical vibrations, leading to bias drift and long-term instability. This study presents experimental verification of a comprehensive structural error compensation approach for navigation-grade interferometric FOGs operating under semi-realistic environmental conditions. A custom-designed test bench was developed to simulate synchronized thermal and vibrational disturbances, reflecting those found in actual navigation scenarios. The effectiveness of the compensation method was assessed using key performance indicators, including bias drift, bias instability, angle random walk, and sensitivity to temperature variations. Experimental findings indicate notable improvements in gyroscope performance after applying the compensation strategy: bias drift and bias instability were reduced by approximately 66% and 61%, respectively, while angle random walk decreased by over 50%. Temperature sensitivity was also significantly minimized. These results demonstrate the practical value of the proposed compensation method, especially for applications in autonomous systems and environments where GNSS signals are unreliable or unavailable.

Comparative evaluation of commercially available fiber-optic gyroscopes (FOGs) is complicated by heterogeneous technical specifications and the methodological assumptions underlying multi-criteria ranking. This study develops and systematically evaluates the Fiber Optic Gyroscope Performance Index (FOGPI), a six-criterion, specification-based framework integrating Bias Stability, Angle Random Walk, Maximum Input Rate, Bandwidth, Operating Temperature Range Width, and Power Consumption. The framework employs normalized technical characteristics and explicitly defined engineering preference weights and is applied to eleven commercial FOG models. Its methodological sensitivity is examined through linear, logarithmic, and fixed-reference normalization; local and global weight sensitivity analyses; mission-oriented Analytic Hierarchy Process (AHP) scenarios; intercriterion correlation and CRITIC weighting; leave-one-out analysis; hypothetical Monte Carlo input perturbations; and comparison with TOPSIS and VIKOR. Under baseline linear Min–Max normalization, DSP-1760 achieved the highest FOGPI score (0.816965). However, logarithmic normalization of accuracy-related criteria changed the highest-ranked device to S-F120HA, while increasing the Accuracy group weight beyond approximately 0.592 produced a similar rank reversal. Global weight-space analysis showed that DSP-1760 occupied first place in 50.72% of uniformly sampled configurations, compared with 87.39% under baseline-centered sampling. FOGPI and VIKOR produced identical rankings, although their agreement does not constitute independent validation because of their mathematical relationship. Application-specific screening further demonstrated that aggregate rankings cannot replace mandatory technical requirements. The findings establish FOGPI as a transparent decision-support framework whose rankings depend on normalization, weighting assumptions, comparison-set composition, and the comparability of manufacturer-reported specifications, rather than as an absolute measure of gyroscope performance.