Fiber Bragg grating sensor, system and method capable of self-diagnosis

Abstract

The present invention discloses a fiber grating (FBG) sensor, system, and method capable of self-diagnosis. The sensor base is provided with an emergency stop mechanism and a reset mechanism for self-diagnosis. A first fiber grating (FBG) is connected to a groove in the upper portion of the base via a first fiber collimator, and a second fiber grating (FBG) is connected to the groove in the upper portion of the base via a second fiber collimator. The emergency stop mechanism and the reset mechanism are both fixed to the base. The emergency stop mechanism enables the FBG sensor to detect the wavelength of the first fiber grating and / or the second fiber grating, and then self-diagnose and determine the operating state of the FBG sensor. The reset mechanism places the FBG sensor in an inactive state. The sensing system of the present invention detects light by itself, eliminating the problems of sensitive elements in conventional sensors, such as their fragility, short lifespan, and unreliability. Self-diagnosis is achieved by providing an emergency stop button.

Description

Technical Field

[0001] The present invention relates to the field of sensor measurement technology, and in particular to a fiber grating sensor capable of self-diagnosis, a system and a method. Background Art

[0002] Fiber optic sensing technology, which has rapidly developed in recent decades, uses passive fiber optic sensors as sensing elements. Due to its unique advantages of non-powered monitoring, long-distance transmission, intrinsic safety, and large system capacity, it has played a significant role in monitoring and early warning of flammable and explosive locations, mine safety, perimeter security, and military defense. The unique characteristics of fiber optic sensing technology have made it extremely useful in certain specialized applications, offering unique advantages unmatched by traditional electronic sensors.

[0003] When the optical cable of a conventional system or sensor breaks, the optical fiber transmission is interrupted, causing the system to be unable to detect the return signal. The system then interprets it as a switch sensor action, causing system misjudgment, bringing inconvenience, affecting production, and even leading to accidents.

[0004] Furthermore, in monitoring systems, fast demodulators are generally only capable of dynamic detection, such as vibration monitoring. To achieve rapid demodulation, limitations in hardware and software result in poor wavelength demodulation accuracy, making precise demodulation impossible. This can lead to data fluctuations when demodulating sensors with high precision requirements. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the present invention provides a fiber Bragg grating sensor capable of self-diagnosis, which combines the characteristics of the fiber Bragg grating and has a self-diagnosis function to realize the location function of the damaged optical cable.

[0006] A fiber grating sensor capable of self-diagnosis, wherein the base of the sensor is provided with an emergency stop mechanism and a reset mechanism for self-diagnosis;

[0007] The first fiber Bragg grating is connected to the groove on the upper part of the base through a first fiber collimator, and the second fiber Bragg grating is connected to the groove on the upper part of the base through a second fiber collimator. The emergency stop mechanism and the reset mechanism are both fixed on the base;

[0008] The emergency stop mechanism enables the fiber Bragg grating sensor to detect the first fiber Bragg grating and / or the wavelength of the first fiber Bragg grating and then self-diagnose to determine the working state of the fiber Bragg grating sensor, and the reset mechanism enables the fiber Bragg grating sensor to be in an inactive state.

[0009] A further preferred technical solution is that the emergency stop mechanism includes a spring guide groove and a guide groove of the emergency stop button connecting rod opened in the base, an emergency stop button is provided on the emergency stop button connecting rod, the emergency stop button connecting rod is connected to the emergency stop button through a thread, and the emergency stop button connecting rod structure is a stepped cylindrical structure.

[0010] A further preferred technical solution is that a cylindrical groove is provided inside the large diameter of the emergency stop button connecting rod and a light-through groove is opened around the large diameter cylinder. Protrusions for locking the emergency stop button connecting rod are also symmetrically arranged around the large diameter cylinder. A sealing ring groove is provided on the upper part of the emergency stop button connecting rod; the emergency stop button connecting rod is wrapped by the upper cover and the base and can slide.

[0011] A further preferred technical solution is that a first spring is provided in the spring guide groove, which is located below the upper cover and inside the base. The lower part of the first spring contacts the lower part of the spring guide groove inside the base, so as to provide rebound elastic force between the emergency stop button and the emergency stop button connecting rod.

[0012] According to a further preferred technical solution, reset mechanisms are symmetrically provided on both sides of the base, and the reset mechanisms include a reset button and a reset button connecting rod connected thereto, and the reset button connecting rod is fixed to the side of the base through a fixing seat.

[0013] According to a further preferred technical solution, the reset button connecting rod and the emergency stop button connecting rod are vertically distributed in space.

[0014] According to a further preferred technical solution, a second spring is provided between the reset button connecting rod and the fixing seat, and the second spring maintains the reset button connecting rod with pressure to press the emergency stop button connecting rod.

[0015] In a further preferred technical solution, one end of the second fiber grating is directly suspended in the air or packaged on a sensitivity enhancement platform.

[0016] A method for operating a fiber grating sensor capable of self-diagnosis, comprising:

[0017] The emergency stop button is subjected to downward pressure, at which time the first spring is compressed, and the emergency stop button connecting rod moves in the direction of spring compression, blocking the first fiber collimator during the movement and eventually completely blocking it.

[0018] After the first fiber collimator is completely blocked, if the emergency stop button continues to be stressed, the second spring inside the fixing seat, which is itself compressed, will move in the direction of restoring its own state, and at the same time drive the reset button connecting rod to move and slide from the large diameter outside the emergency stop button connecting rod to the small diameter, thereby locking the emergency stop button connecting rod;

[0019] In the locked state, pull out both reset buttons at the same time. The reset button connecting rod that plays the locking function moves outward, compressing the second spring. The first spring itself is in a compressed state and will deform in the direction of restoring itself. If the reset button connecting rod continues to move outward, the locking effect will be lost. Driven by the first spring, the emergency stop button and the emergency stop button connecting rod return to the state when the sensor is not actuated.

[0020] A second object of the present invention is to disclose a fiber Bragg grating sensor system capable of self-diagnosis, comprising a plurality of sensor groups, each sensor group being connected to a fiber Bragg grating demodulator via a splitter, the fiber Bragg grating demodulator communicating with a PLC controller, and each sensor in each sensor group being a fiber Bragg grating sensor capable of self-diagnosis;

[0021] When the sensor is not in action, the fiber Bragg grating demodulator demodulates the information of the first fiber Bragg grating and the second fiber Bragg grating wavelengths;

[0022] When the sensor is activated, the emergency stop button is subjected to downward pressure, and the emergency stop button connecting rod moves in the direction of spring compression, blocking the first optical fiber collimator during the movement until it is completely blocked;

[0023] The emergency stop button continues to be stressed, and the reset button connecting rod moves and slides from the external protrusion of the emergency stop button connecting rod to the large diameter, locking the emergency stop button connecting rod. At this time, the fiber Bragg grating demodulator can only receive the wavelength of the first fiber Bragg grating.

[0024] When the sensor is locked, pull out both reset buttons at the same time. The reset button connecting rod, which plays a locking role, moves outward, compressing the second spring. The first spring itself is in a compressed state and will deform in the direction of restoring itself. If the reset button connecting rod continues to move outward, it will lose its locking effect. Driven by the first spring, the emergency stop button and the emergency stop button connecting rod return to the state when the sensor is not actuated.

[0025] A further preferred technical solution is that when the sensor is not in operation, after the light source inside the fiber grating demodulator emits a broadband laser, the laser passes through the optical cable and the optical fiber splitter to reach the transmission optical cable and the first fiber grating. The light that meets the wavelength of the first fiber grating is reflected and returns to the demodulator along the original path. The light of the remaining wavelength continues to be transmitted to the first fiber collimator and passes through the groove of the emergency stop button connecting rod to reach the second fiber collimator and the second fiber grating. At this time, the light that meets the wavelength of the second fiber grating will be reflected and returned to the demodulator along the original path.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The sensing system of the present invention detects by the presence or absence of light, and does not have the problems of ordinary sensors such as sensitive elements that are easily damaged, have a short lifespan, and are unreliable. Self-diagnosis can be achieved by setting an emergency stop button.

[0028] The present invention combines the characteristics of fiber Bragg grating to propose a self-diagnostic fiber Bragg grating multi-parameter sensing system. The system can perform multi-parameter, large-capacity, quasi-distributed monitoring and can be applied in various environments such as oil storage tanks and coal mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0030] Figure 1(a) is a front view of the sensor of this application;

[0031] Figure 1(b) is a side view of the sensor of this application;

[0032] Figure 2(a) is a top view of the sensor of the present application;

[0033] Figure 2(b) is a cross-sectional view of the sensor of the present application taken along the direction B;

[0034] Figure 2(c) is a cross-sectional view of the sensor of the present application taken along the direction A;

[0035] Figure 3 This is a schematic diagram of the three-dimensional structure of the sensor for this application;

[0036] Figure 4(a)-Figure 4(c) Three views of the sensor for this application;

[0037] Figure 5 A schematic diagram of a system using the sensor of this application;

[0038] Figure 6(a)-Figure 6(c) This is a side sectional view of the sensor in different states when the emergency stop button of this application is pressed;

[0039] Figure 7(a)-Figure 7(c) This is a front sectional view of the different states of the sensor when the emergency stop button of this application is pressed;

[0040] Figure 8 Schematic diagram of the connector structure;

[0041] Figure 9 Schematic diagram of the upper cover structure;

[0042] Figure 10 This is a schematic diagram of the emergency stop button connecting rod structure;

[0043] Figure 11(a)-Figure 11(c) Schematic diagram of the base structure;

[0044] Figure 12(a)-Figure 12(c) Schematic diagram of the protective cover structure;

[0045] Figure 13(a)-Figure 13(c)Schematic diagram of the reset button connecting rod structure;

[0046] Figure 14(a)-Figure 14(c) Schematic diagram of the fixed seat structure;

[0047] Figure 15 Working status diagram when two sensors are arranged;

[0048] In the figure, 1 is a transmission optical fiber, 2 is an optical cable (excluding optical fiber), 3 is an optical cable fixing joint, 4 is a connecting part, 5 is an upper cover, 6 is an emergency stop button, 7 is an emergency stop button connecting rod, 8 is a base, 9 is a protective cover, 10 is a cushioning rubber pad, 11 is a flat pad, 12 is an installation fixing bolt, 13 is a reset button, 14 is a reset button connecting rod, 15 is a fixing seat, 16 is a fixing seat bolt, 17 is a first spring, 18 is a first sealing ring, 19 is a second spring, 20 is a first optical fiber Bragg grating, 21 is a first optical fiber collimator, 22 is a second sealing ring, 23 is a second optical fiber collimator, 24 is a fixing bolt of a sensitivity enhancement platform, 25 is a second optical fiber Bragg grating, and 26 is a sensitivity enhancement platform. DETAILED DESCRIPTION

[0049] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0050] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0051] In a typical embodiment of the present application, the embodiment discloses a fiber Bragg grating sensor capable of self-diagnosis, such as Figure 1(a)-Figure 1(b) As shown, the sensor includes a transmission optical fiber 1, an optical cable (excluding optical fiber) 2, an optical cable fixing joint 3, a connector 4, an upper cover 5, an emergency stop button 6, an emergency stop button connecting rod 7, a base 8, a protective cover 9, a cushioning rubber pad 10, a flat pad 11, a mounting fixing bolt 12, a reset button 13, a reset button connecting rod 14, a fixing seat 15, a fixing seat bolt 16, a first spring 17, a first sealing ring 18, and a second spring 19. Figure 2(a)-Figure 2(c) As shown, it also includes: a first fiber grating 20, a first fiber collimator 21, a second sealing ring 22, a second fiber collimator 23, a sensitivity enhancement platform fixing bolt 24, a second fiber grating 25, and a sensitivity enhancement platform 26.

[0052] The overall three-dimensional view is as follows Figure 3As shown, the overall three-view drawing is as follows Figure 4(a)-Figure 4(c) shown.

[0053] The transmission fiber 1 is a single-mode fiber. One end of the transmission fiber 1 is connected to the demodulator, and the other end is provided with a first fiber grating 20. The other end of the first fiber grating 20 is welded to a first fiber collimator 21. The first fiber collimator 21 and the second fiber collimator 23 are set in the groove of the base 8.

[0054] There is one optical cable 2 for protecting the transmission optical fiber 1 ; there is one optical cable fixing joint 3 for locking the optical cable and connecting to the connector 4 .

[0055] like Figure 8 As shown, there are two connectors 4, one on each side, with threads on the upper part for fixing the optical cable fixing joint 3, and two holes on the lower part for fixing to the base 8 by bolts.

[0056] like Figure 9 As shown, the upper cover 5 is a single piece and is provided with two types of holes. The middle hole is used to pass the emergency stop button connecting rod 7, and the other four small holes are used to fix it to the base 8 by installing fixing bolts 12.

[0057] The emergency stop button 6 is connected to the emergency stop button connecting rod 7 by a thread. Pressing it can activate the sensor.

[0058] like Figure 10 As shown, the emergency stop button connecting rod 7 is a stepped shaft with unequal diameters. The two shafts are concentric. A cylindrical groove is provided inside the large-diameter cylinder and a light-through groove is opened on the periphery of the large-diameter cylinder to form a guide structure. The outside of the large-diameter cylinder is also symmetrically provided with protrusions that play a locking role when the emergency stop button connecting rod moves downward.

[0059] A sealing ring groove is provided on the upper part of the large diameter cylinder, and the sealing ring groove is used to place the second sealing ring 22, which is used to seal the sliding contact surface between the emergency stop button connecting rod 7 and the base 8. The large diameter cylinder is wrapped by the upper cover 5 base 8 and performs sliding friction.

[0060] As shown in FIG11 , the base 8 is a spring guide groove provided inside for accommodating and stabilizing the first spring 17 . The base is also provided with a guide groove matching the guide structure of the connecting rod of the emergency stop button 7 .

[0061] like Figure 12(a)-Figure 12(c) As shown, the protective cover 9 is a single piece connected to the connector 4 via a thread, and a second fiber grating 25 and a sensitivity enhancement platform 26 are provided inside.

[0062] There are two cushioning pads 10, which are placed on the mounting bolts 12. The material can be rubber or other cushioning materials. While achieving cushioning, the elasticity of the cushioning pads 10 also prevents the mounting bolts 12 from falling off. There are two flat washers 11.

[0063] Install six fixing bolts 12 to fix the buffer pad and the entire sensor to the component to be installed; at the same time, fix the connector 4 and the base 8.

[0064] There are two reset buttons 13, which are connected to the reset button connecting rod 14 through threads. When restoring the sensor state, the two reset buttons need to be pulled out at the same time; the reset button connecting rod and the emergency stop button connecting rod are in a vertical relationship.

[0065] like Figure 13(a)-Figure 13(c) As shown, there are two reset button connecting rods 14 , which are fixed to the base through a fixing seat 15 , and a second spring 19 is provided between the fixing seat 15 and the reset button connecting rod 14 .

[0066] like Figure 14(a)-Figure 14(c) As shown, there are two fixing seats 15 located on both sides of the base 8 and fixed to both sides of the base 8 by fixing seat bolts 16; there are 8 fixing seat bolts 16 used to fix the fixing seats 15.

[0067] There are two first springs 17, located below the upper cover 5 and inside the base 8. The lower part is at the bottom of the spring guide groove inside the base 8, and the upper part contacts the bottom of the emergency stop button connecting rod 7. The first spring 17 provides the rebound elastic force between the emergency stop button 6 and the emergency stop button connecting rod 7;

[0068] There are two first sealing rings 18, which slide between the reset button connecting rod 14 and the fixing seat 15 to provide sealing;

[0069] There are two second springs 19, located inside the reset button connecting rod 14 and the fixing seat 15, to keep the reset button connecting rod 14 with the pressure to press the emergency stop button connecting rod 7;

[0070] There is one first fiber Bragg grating 20, which is located in the transmission optical fiber 1; there is one first optical fiber collimator 21, which is welded to the transmission optical fiber 1; there is one second sealing ring 22, which is sleeved on the outside of the lower part of the emergency stop button connecting rod 7 and seals when the emergency stop button connecting rod 7 and the upper cover 5 slide. A good seal can ensure that dust cannot enter the interior of the sensor, avoiding contamination of the mirror surfaces of the first optical fiber collimator 21 and the second optical fiber collimator 23.

[0071] There is one second fiber collimator 23, and the other end of the second fiber Bragg grating 25 is welded; there are two ways to install the second fiber Bragg grating 25, either directly suspended in the air or packaged on the sensitivity enhancement platform 26. If packaged on the sensitivity enhancement platform 26, it needs to be fixed with the sensitivity enhancement platform fixing bolts 24.

[0072] In a typical embodiment of the present application, the embodiment discloses a fiber Bragg grating sensing system capable of self-diagnosis, such as Figure 5 As shown, it consists of a fiber Bragg grating demodulator, a sensor, a transmission optical cable, a communication cable, an optical fiber splitter, etc.

[0073] The sensor is connected to the splitter via an optical cable. Multiple sensors are gathered at the splitter and connected to the FBG interrogator via an optical cable. The FBG interrogator communicates with the PLC via a communication line.

[0074] Functions of each part:

[0075] The sensor senses information and converts it into information such as the change in fiber Bragg grating wavelength and the on-off state of light. The fiber Bragg grating demodulator detects the sensor status and makes judgments and analyses. The monitoring information can be displayed and transmitted to the PLC control system at the same time, thereby realizing functions such as equipment control.

[0076] System Features: Utilizing the characteristics of fiber optic sensing technology and fiber Bragg grating wavelength division multiplexing, and adopting a broadband light source plus fiber Bragg grating structure, the detection capacity of the monitoring system is greatly improved compared to electronic sensors. Each channel only requires one fiber optic cable from the demodulator to the splitter. Compared with electronic sensors, each sensor requires at least two power or signal cables, so this system saves a lot of communication cables. The sensor is non-electrical and is a passive sensor, suitable for use in flammable and explosive places. Through reasonable configuration, the system has a self-diagnosis function and can locate fiber optic cable damage.

[0077] The working principle of the above system is:

[0078] When the sensor is not in operation, as shown in Figure 6(a) and Figure 7(a):

[0079] According to the characteristics of the fiber grating, the light of its own characteristic wavelength is reflected, and the light of other wavelengths continues to propagate. When the light source inside the fiber grating demodulator emits a broadband laser, the laser passes through the optical cable and the optical fiber splitter to reach the transmission optical fiber 1 and the first fiber grating 20. The light that meets the wavelength of the first fiber grating 20 is reflected and returns to the demodulator along the original path. The light of the remaining wavelengths continues to be transmitted to the first fiber collimator 21, and passes through the groove of the emergency stop button connecting rod 7, and passes through the second fiber collimator 23 to reach the second fiber grating 25. At this time, the wavelength that meets the second fiber grating 25 will be reflected and returned to the demodulator along the original path. This is state one. At this time, the demodulator will demodulate the information of the wavelengths of the first fiber grating 20 and the second fiber grating 25.

[0080] The sensor is in action, as shown in Figure 6(b) and Figure 7(b):

[0081] The emergency stop button 6 is subjected to downward pressure, compressing the first spring 17. The emergency stop button connecting rod 7 moves in the direction of the spring compression, blocking the first fiber collimator 21 during this movement, ultimately completely blocking it. The state from when the emergency stop button connecting rod 7 is forced to move until it completely blocks the first fiber collimator 21 is recorded as state two.

[0082] The sensor is locked, as shown in Figure 6(c) and Figure 7(c):

[0083] If the emergency stop button 6 continues to be stressed, the compressed second spring 19 inside the mounting base 15 will move toward its original position, simultaneously driving the reset button connecting rod 14 to move. The reset button connecting rod 14 then slides from the external projection of the emergency stop button connecting rod 7 to its larger diameter, locking the emergency stop button connecting rod 7. This is referred to as state three. At this point, the light emitted from the first fiber collimator 21 cannot reach the second fiber collimator 23. This is reflected on the demodulator as only the wavelength of the first fiber Bragg grating 20 is being received.

[0084] Sensor Recovery

[0085] In the locked state, the two reset buttons 13 are pulled outward at the same time. At this time, the reset button connecting rod 14, which plays the locking function, moves outward, compressing the second spring 19. The first spring 17 itself is in a compressed state and will deform in the direction of restoring itself. If the reset button connecting rod 14 continues to move outward, the locking effect will be lost. Driven by the first spring 17, the emergency stop button 6 and the emergency stop button connecting rod 7 return to the state when the sensor is not actuated.

[0086] In another typical embodiment of the present application, in practical applications, a multi-parameter sensor is used to realize switch quantity measurement and temperature measurement:

[0087] System algorithm design:

[0088] 1. Software design sensor types, such as 01, 02, 03, etc. Each sensor type corresponds to the corresponding sensor algorithm. Example 01 is a multi-parameter sensor.

[0089] Multi-parameter sensor algorithm design:

[0090] The first fiber Bragg grating inside the sensor is a state judgment grating; the second fiber Bragg grating is a switch quantity monitoring grating, which can also monitor temperature. Because it is not affected by external interference except by temperature, it can also serve as a temperature monitoring grating.

[0091] When the sensor is in the inactive state, the system detects two fiber Bragg grating wavelengths, which is recorded as working state 1; when the sensor is in operation, since the first fiber collimator is blocked by the emergency stop button connecting rod 7, the system can only detect the first fiber Bragg grating 20, which is defined as working state 2.

[0092] When both fiber Bragg gratings cannot be detected, the working state is 3.

[0093] Since the sensor grating and collimator components are protected by the housing during sensor design, and a shockproof cushion 10 is provided at the bottom, the fiber Bragg grating at the second collimator will not be damaged unless actively shielded during normal use.

[0094] Therefore, when the system is working normally, the device sensor normally switches between state 1 and state 2.

[0095] When the optical cable is damaged, the demodulator cannot detect the grating signal and the working state is 3. It can be determined that the optical cable is damaged or there is excessive loss in the optical cable.

[0096] Example:

[0097] For 40nm broadband lasers, the wavelength division multiplexing function can be used by setting fiber gratings of different wavelengths to connect multiple sensors to each channel, thus achieving multi-point and large-scale measurement.

[0098] The ambient temperature variation range of the fiber Bragg grating is 100 degrees Celsius, and the wavelength variation range of the fiber Bragg grating is 1 nm. Each sensor is equipped with two gratings, and each channel can connect to at least 19 sensors. Based on a 16-channel demodulation device, one device can carry 304 sensors, realize 304 switch quantity monitoring, and realize 304-point temperature detection at the same time.

[0099] During monitoring, the sensor wavelength is numbered and limited. For example, the sensor working range is -20 to 80 degrees Celsius. At 30 degrees Celsius, the sensor in a certain channel is numbered A1B1. The center wavelength of fiber Bragg grating 1 is 1529nm and the center wavelength of fiber Bragg grating 2 is 1530nm. When setting the software, the wavelength is defined as A001 between 1528.5 and 1529.5nm; B001 between 1529.5 and 1530.5nm. Similarly, at 30 degrees Celsius, the sensor is numbered A2B2. The center wavelength of fiber Bragg grating 1 is 1531 The wavelength of the second fiber Bragg grating is 1532nm. When setting the software, the wavelength is defined as A002 between 1530.5 and 1531.5nm; the wavelength is defined as B002 between 1531.5 and 1532.5nm. At 30 degrees Celsius, the sensor numbers are A19 and B19. The central wavelength of the first fiber Bragg grating is 1565nm. The wavelength of the second fiber Bragg grating is 1566nm. When setting the software, the wavelength is defined as A019 between 1564.5 and 1565.5nm; the wavelength is defined as B019 between 1565.5 and 1566.5nm.

[0100] The channel number is 01 to 16, 01A1B1 represents the first channel A1B1 sensor, 16A1B1 represents the 16th channel A1B1 sensor.

[0101] When installing the sensors, pair the 19 sensors (A1B1A2B2…A19B19) with their respective mounting locations. The sensor information bar displays the detection location information to establish a corresponding relationship. During system operation monitoring, sensor A10B10 displays the switch sensor's actuation status and temperature. By using this corresponding position relationship, you can obtain the corresponding information for the corresponding detection location.

[0102] Example:

[0103] In addition, for long optical cables, gratings can be burned at certain intervals along the entire optical fiber to mark them. In applications, it is possible to detect a specific part of the optical cable that is broken or has excessive loss, and the wavelength division multiplexing feature can be used to locate the damaged part of the optical cable.

[0104] The algorithm is as follows: the first fiber Bragg grating, the second fiber Bragg grating, ... fiber Bragg grating n, and define the wavelength. For example, 1528.5-1529nm is the first fiber Bragg grating, 1529-1529.5nm is the second fiber Bragg grating, the interval between the first fiber Bragg grating and the second fiber Bragg grating of 1528.5-1529nm is 100 meters, and there is a fiber Bragg grating 77, with a distance of 78*100=7800 meters, to achieve positioning. The remaining optical fibers are used to realize the switching value of 1558.5-1559nm, 1559-1560.5nm, 1560.5-1561...1567.5

[0105] When the system detects only the first FBG, the second FBG, ... the eighteenth FBG, it determines that there is a problem with the optical cables at the eighteenth and nineteenth FBGs, corresponding to a problem with the optical cables at a distance of 1900 to 2000 meters.

[0106] Example 3

[0107] When used with a high-speed demodulator, high-frequency switching and temperature functions can be realized. When used with a low-speed, high-precision demodulator, low-frequency switching and temperature detection functions can be realized.

[0108] Due to the inherent characteristics of the demodulator, high-speed demodulators have poor demodulation accuracy, typically exhibiting inherent fluctuation errors exceeding 10pm. This results in low temperature sensor accuracy during temperature demodulation. To improve the accuracy of the temperature sensor in this mode, the temperature fiber Bragg grating (FBG) can be enhanced. The bare Bragg grating (FBG) varies by approximately 10pm / °C. This mode requires the FBG to be packaged on a 26° sensitivity enhancement platform.

[0109] Example:

[0110] According to the sensor application range, the sensor is in the working range of -20 to 80 degrees Celsius within 100 degrees Celsius (meeting the use in most environments), and the A grating wavelength in the same channel of the sensitive fiber Bragg grating is enhanced.

[0111] The thermal expansion coefficient of the fiber Bragg grating is 5.5×10-7 / °C; the thermal expansion coefficient of metal brass is 18.9×10-7 / °C. Fixing the fiber Bragg grating on a material with a brass substrate can achieve the function of sensitivity enhancement.

[0112] 18.9 / 5.5≈3.44, a 3.44-fold increase in sensitivity. This means that when the second fiber Bragg grating is suspended, its temperature changes by 10pm per degree Celsius, while after sensitivity enhancement, it changes by 34.4pm per degree Celsius. When the sensor's own temperature fluctuation is 10pm, the error in temperature detection is 1 degree Celsius. After sensitivity enhancement, the error is 10 / 34.4≈0.29 degrees, increasing sensor accuracy by 3.44 times. Consequently, the number of sensors per channel is reduced. Based on a 40nm bandwidth, calculations indicate that a single channel can accommodate nine sensors. Therefore, this design provides the functionality of a high-precision temperature sensor with fast switching requirements.

[0113] In one implementation example, as follows Figure 15 As shown, two sensors are arranged. This structure can be applied in environments where separate control is required at the same monitoring point. This structure will act as a switch regardless of which sensor is actuated, while reducing the number of fiber Bragg gratings, which is conducive to ensuring the large capacity of each channel.

[0114] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A fiber Bragg grating sensor capable of self-diagnosis, characterized in that: The base of the sensor is provided with an emergency stop mechanism and a reset mechanism for self-diagnosis; The first fiber Bragg grating is connected to the groove on the upper part of the base through a first fiber collimator, and the second fiber Bragg grating is connected to the groove on the upper part of the base through a second fiber collimator. The emergency stop mechanism and the reset mechanism are both fixed on the base; The emergency stop mechanism enables the fiber Bragg grating sensor to detect the wavelength of the first fiber Bragg grating and / or the second fiber Bragg grating and then self-diagnose and determine the working state of the fiber Bragg grating sensor, and the reset mechanism enables the fiber Bragg grating sensor to be in an inactive state. The working state includes the non-operation state; Wherein, when the wavelengths of the first fiber Bragg grating and the second fiber Bragg grating are detected simultaneously, and the wavelengths do not change or the wavelength of the second fiber Bragg grating gradually decreases to disappear, the fiber Bragg grating sensor is in the working state; When the wavelengths of the first fiber grating and the second fiber grating are detected simultaneously and the wavelengths do not change, the fiber grating sensor is in the non-actuated state.

2. A fiber Bragg grating sensor capable of self-diagnosis according to claim 1, characterized in that: The emergency stop mechanism includes a spring guide groove and a guide groove of an emergency stop button connecting rod opened in the base. An emergency stop button is set on the emergency stop button connecting rod. The emergency stop button connecting rod is connected to the emergency stop button. The emergency stop button connecting rod structure is a stepped cylindrical structure.

3. A fiber Bragg grating sensor capable of self-diagnosis as claimed in claim 2, characterized in that: A cylindrical groove is provided inside the large-diameter cylinder of the emergency stop button connecting rod and a light-through groove is opened around the large-diameter cylinder. Protrusions for locking the emergency stop button connecting rod are also symmetrically arranged around the large-diameter cylinder. A sealing ring groove is provided on the upper part of the emergency stop button connecting rod; the emergency stop button connecting rod is wrapped by the upper cover and the base and can slide.

4. A fiber Bragg grating sensor capable of self-diagnosis as claimed in claim 2, characterized in that: A first spring is provided in the spring guide groove, located below the upper cover and inside the base. The lower part of the first spring contacts the lower part of the spring guide groove inside the base, and is used to provide rebound elastic force between the emergency stop button and the emergency stop button connecting rod.

5. The fiber Bragg grating sensor capable of self-diagnosis according to claim 2, wherein: Reset mechanisms are symmetrically arranged on both sides of the base. The reset mechanisms include a reset button and a reset button connecting rod connected thereto. The reset button connecting rod is fixed to the side of the base through a fixing seat.

6. A fiber Bragg grating sensor capable of self-diagnosis as claimed in claim 5, characterized in that: The reset button connecting rod and the emergency stop button connecting rod are vertically distributed in space.

7. A fiber Bragg grating sensor capable of self-diagnosis according to claim 6, characterized in that: A second spring is provided between the reset button connecting rod and the fixing seat, and the second spring keeps the reset button connecting rod having a pressure to press the emergency stop button connecting rod.

8. The fiber Bragg grating sensor capable of self-diagnosis according to claim 1, wherein: One end of the second fiber grating is directly suspended in the air or packaged on the sensitivity enhancement platform.

9. A method for operating a fiber Bragg grating sensor capable of self-diagnosis, characterized in that: include The emergency stop button is subjected to downward pressure, at which time the first spring is compressed, and the emergency stop button connecting rod moves in the direction of spring compression, blocking the first fiber collimator during the movement and eventually completely blocking it. After the first fiber collimator is completely blocked, if the emergency stop button continues to be stressed, the second spring inside the fixing seat, which is itself compressed, will move in the direction of restoring its own state, and at the same time drive the reset button connecting rod to move, and slide from the external protrusion of the emergency stop button connecting rod to the large-diameter cylinder of the emergency stop button connecting rod, thereby locking the emergency stop button connecting rod; In the locked state, pull out both reset buttons at the same time. The reset button connecting rod that plays the locking function moves outward, compressing the second spring. The first spring itself is in a compressed state and will deform in the direction of restoring itself. If the reset button connecting rod continues to move outward, the locking effect will be lost. Driven by the first spring, the emergency stop button and the emergency stop button connecting rod return to the state when the sensor is not actuated.

10. A self-diagnostic fiber Bragg grating sensor system, comprising a plurality of sensor groups, each sensor group being connected to a fiber Bragg grating interrogator via a splitter, the fiber Bragg grating interrogator communicating with a PLC controller; each sensor in each sensor group being a self-diagnostic fiber Bragg grating sensor; each sensor in each sensor group being a self-diagnostic fiber Bragg grating sensor according to any one of claims 1 to 8; When the sensor is not in operation, after the light source inside the fiber Bragg grating interrogator emits a broadband laser, the laser passes through the optical cable and the optical fiber splitter to reach the transmission cable and the first fiber Bragg grating. The light that meets the wavelength of the first fiber Bragg grating is reflected and returns to the interrogator along the original path. The light of the remaining wavelength continues to be transmitted to the first fiber collimator and passes through the groove of the emergency stop button connecting rod to reach the second fiber collimator and the second fiber Bragg grating. At this time, the light that meets the wavelength of the second fiber Bragg grating will be reflected and returned to the interrogator along the original path. The fiber Bragg grating interrogator demodulates the information of the wavelengths of the first and second fiber Bragg gratings. When the sensor is activated, the emergency stop button is subjected to downward pressure, and the emergency stop button connecting rod moves in the direction of spring compression, blocking the first optical fiber collimator during the movement until it is completely blocked; The emergency stop button continues to be stressed, and the reset button connecting rod moves and slides from the external protrusion of the emergency stop button connecting rod to the large-diameter cylinder of the emergency stop button connecting rod, locking the emergency stop button connecting rod. At this time, the fiber Bragg grating demodulator can only receive the wavelength of the first fiber Bragg grating. When the sensor is locked, pull out both reset buttons at the same time. The reset button connecting rod, which plays a locking role, moves outward, compressing the second spring. The first spring itself is in a compressed state and will deform in the direction of restoring itself. If the reset button connecting rod continues to move outward, it will lose its locking effect. Driven by the first spring, the emergency stop button and the emergency stop button connecting rod return to the state when the sensor is not actuated.

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