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The purpose of this study is to present the state of the art for fiber Bragg grating (FBG) acceleration sensing technologies from two aspects: the principle of the measurement dimension and the principle of the sensing configuration. Some commercial sensors have also been introduced and future work in this field has also been discussed. This paper could provide an important reference for the research community.

This review is to present the state of the art for FBG acceleration sensing technologies from two aspects: the principle of the measurement dimension (one-dimension and multi-dimension) and the principle of the sensing configuration (beam type, radial vibration type, axial vibration type and other composite structures).

The current research on developing FBG acceleration sensors is mainly focused on the sensing method, the construction and design of the elastic structure and the design of a new information detection method. This paper hypothesizes that in the future, the following research trends will be strengthened: common single-mode fiber grating of the low cost and high utilization rate; high sensitivity and strength special fiber grating; multi-core fiber grating for measuring single-parameter multi-dimensional information or multi-parameter information; demodulating equipment of low cost, small volume and high sampling frequency.

The principle of the measurement dimension and principle of the sensing configuration for FBG acceleration sensors have been introduced, which could provide an important reference for the research community.

In response to the common low sensitivity of fiber Bragg grating (FBG) temperature sensors in measurement, an FBG temperature sensor sensitized in a substrate-type package structure is proposed.

The sensitivity of sensors is analyzed theoretically; aluminum alloys with large coefficient of thermal expansion are used; the ANSYS software is used for simulation analysis and optimization design of sensors; real sensors are developed based on simulation results; in this study, a test system was built to test the performance of the proposed sensor.

The results suggested that the sensitivity of encapsulated FBG temperature sensor is 27.3 pm/°C in the range of −20 °C to 40 °C, which is 2.7 times that of bare FBG sensor, while the linearity is up to more than 0.99.

The sensitivity of FBG temperature sensor is greatly improved by the design of the structure.

This study innovatively proposes substrate-type sensitized FBG temperature sensor. The temperature sensitivity of fiber grating can be improved by single metal structure, and the effect of structural strain can be reduced by a tab structure. The study results provide a reference for the development of like sensors and the further improvement in the sensitivity of FBG temperature sensors.

The purpose of this paper is to present the latest sensing structure designs and principles of information detection of fiber Bragg grating (FBG) displacement sensors. Research advance and the future work in this field have been described, with the background that displacement and deformation measurements are universal and crucial for structural health monitoring.

This paper analyzes and summarizes the existing FBG displacement sensing technologies from two aspects principle of information detection (wavelength detection, spectral bandwidth detection, light intensity detection, among others) and principle of the sensing elastomer structure design (cantilever beam type, spring type, elastic ring type and other composite structures).

The current research on developing FBG displacement sensors is mainly focused on the sensing method, the construction and design of the elastic structure and the design of new information detection method. The authors hypothesize that the following research trends will be strengthened in future: temperature compensation technology for FBG displacement sensors based on wavelength detection; a study of more diverse elastic structures; and fiber gratings manufactured with special fibers will greatly improve the performance of sensors.

The latest sensing structure designs and principles of information detection of FBG displacement sensors have been proposed, which could provide important reference for research group.

Structural health monitoring (SHM) has become an attractive subject in aerospace engineering field considering the opportunity to avoid catastrophic failures by detecting damage in advance and to reduce maintenance costs. Fibre Bragg Grating (FBG) sensors are denoted as one of the most promising sensors for SHM applications as they are lightweight, immune to electromagnetic effects and able to be embedded between the layers of composite structures. The purpose of this paper is to research on and demonstrate the feasibility of FBG sensors for SHM of composite structures.

Applications on thin composite beams intended for SHM studies are presented. The sensor system, which includes FBG sensors and related interrogator system, and manufacturing of the beams with embedded sensors, are detailed. Static tension and torsion tests are conducted to verify the effectiveness of the system. Strain analysis results obtained from the tests are compared with the ones obtained from the finite element analyses conducted using ABAQUS® software. In addition, the comparison between the data obtained from the FBG sensors and from the strain gauges is made by also considering the noise content. Finally, fatigue test under torsion load is conducted to observe the durability of FBG sensors.

The results demonstrated that FBG sensors are feasible for SHM of composite structures as the strain data are accurate and less noisy compared to that obtained from the strain gauges. Furthermore, the convenience of obtaining reliable data between the layers of a composite structure using embedded FBG sensors is observed.

Observing the advantages of the FBG sensors for strain measurement will promote using FBG sensors for damage detection related to the SHM applications.

This paper presents applications of FBG sensors on thin composite beams, which reveal the suitability of FBG sensors for SHM of lightweight composite structures.

Centrifugal model tests can accelerate the characterization of landslides and demonstrate the form of slope failure, which is an important measure to research its instability mechanisms. Simply observing the slope landslide before and after a centrifugal model test cannot reveal the processes involved in real-time deformation. Electromagnetic sensors have severed as an existing method for real-time measurement, however, this approach has significant challenges, including poor signal quality, interference, and complex implementation and wiring schemes. This paper aims to overcome the shortcomings of the existing measurement methods.

This work uses the advantages of fiber Bragg grating (FBG) sensors with their small form-factor and potential for series multiplexing in a single fiber to demonstrate a monitoring strategy for model centrifugal tests. A slope surface deformation displacement sensor, FBG anchor sensor and FBG anti-slide piling sensor have been designed. These sensors are installed in the slope models, while centrifugal acceleration tests under 100 g are carried out.

FBG sensors obtain three types of deformation information, demonstrating the feasibility and validity of this measurement strategy.

The experimental results provide important details about instability mechanisms of a slope, which has great significance in research on slope model monitoring techniques and slope stability.

The purpose of this paper is to compare the sensing characteristics of uniform fiber Bragg grating (FBG) and tilted fiber Bragg grating (TFBG) by presenting a detailed research review. Temperature, axial strain, bending, vibration and refractive index measurands of FBG and TFBG sensor are presented and some significant differences are found.

Theoretical analysis and practical application in engineering are investigated and compared from other authors' research papers and self analysis. Spectra behavior of both FBG and TFBG are discussed.

There are found to be significant differences in temperature, axial strain, bending, vibration and refractive index sensing characteristics of FBG and TFBG.

The paper's analysis is comprehensive and clear and provides readers with the sensing characteristics of FBG and TFBG in detail.

With the increasing development of the surgical robots, the opto-mechatronic technologies are more potential in the robotics system optimization. The optic signal plays an important role in opto-mechatronic systems. This paper aims to present a review of the research status on fiber-optic-based force and shape sensors in surgical robots.

Advances of fiber-optic-based force and shape sensing techniques in the past 20 years are investigated and summarized according to different surgical requirement and technical characteristics. The research status analysis and development prospects are discussed.

Compared with traditional electrical signal conduction, the phototransduction provides higher speed transmission, lower signal loss and the immunity to electromagnetic interference in robot perception. Most importantly, more and more advanced optic-based sensing technologies are applied to medical robots in the past two decades because the prominence is magnetic resonance imaging compatibility. For medical robots especially, fiber-optic sensing technologies can improve working security, manipulating accuracy and provide force and shape feedback to surgeon.

This is a new perspective. This paper mainly researches the application of optical fiber sensor according to different surgeries which is beneficial to learn the great potential of optical fiber sensor in surgical robots. By enumerating the research progress of medical robots in optimization design, multimode sensing and advanced materials, the development tendency of fiber-optic-based force and shape sensing technologies in surgical robots is prospected.

The purpose of this paper is to investigate an online monitoring strategy that incorporates fiber Bragg gratings (FBGs) for deformation displacement detection, with the background that slope deformation monitoring is crucial to engineering safety supervision and disaster prevention.

A “beam element” method has been proposed, introduced and experimentally verified in detail. The deformation displacement along a flexible bar can be obtained based on this method, using the distributed strain detected by the FBGs embedded in the bar. A novel sensor structure containing inclinometer casings and a series of connected flexible pipes with FBGs embedded has been proposed. Based on the features of this structure, two FBG deformation sensors have been manufactured and installed into a slope. A matched monitoring station which permits real-time supervision, warning and remote access across the Internet was established and operated.

Displacement data from September 2013 to August 2014 are obtained, which is basically consistent with the practical situation.

The FBG deformation sensors demonstrated a robust and reliable measurement performance, which is promising for real-time disaster warning in slope engineering.

At present, one of the key equipment in pillar industries is a large rotating machinery. Conducting regular health monitoring is important for ensuring safe operation of the large rotating machinery. Because vibrations sensors play an important role in the workings of the rotating machinery, measuring its vibration signal is an important task in health monitoring. This paper aims to present these.

In this work, the contact vibration sensor and the non-contact vibration sensor have been discussed. These sensors consist of two types: the electric vibration sensor and the optical fiber vibration sensor. Their applications in the large rotating machinery for the purpose of health monitoring are summarized, and their advantages and disadvantages are also presented.

Compared with the electric vibration sensor, the optical fiber vibration sensor of large rotating machinery has unique advantages in health monitoring, such as provision of immunity against electromagnetic interference, requirement of less insulation and provision of long-distance signal transmission.

Both contact vibration sensor and non-contact vibration sensor have been discussed. Among them, the electric vibration sensor and the optical fiber vibration sensor are compared. Future research direction of the vibration sensors is presented.

Crack damage detection for aluminum alloy materials using fiber Bragg Grating (FBG) sensor is a kind of structure health monitoring. In this paper, the damage index of full width at half maximum (FWHM) was extracted from the distorted reflection spectra caused by the crack-tip inhomogeneous strain field, so as to explain the crack propagation behaviors.

The FWHM variations were also investigated through combining the theoretical calculations with simulation and experimental analyses. The transfer matrix algorithm was developed to explore the mechanism by which FWHM changed with the linear and quadratic strain. Moreover, the crack-tip inhomogeneous strain field on the specimen surface was computed according to the digital image correlation measurement during the experiments.

The experimental results demonstrated that the saltation points in FWHM curve accorded with the moments of crack propagation to FBG sensors.

The interpretation of reflected spectrum deformation mechanism with crack propagation was analyzed based on both simulations and experiments, and then the performance of potential damage features – FWHM were proposed and evaluated. According to the correlation between the damage characteristic and the crack-tip location, the crack-tip of the specimen could be measured rapidly and accurately with this technique.