Goaf slope lattice beam strain monitoring and demodulating system based on MEMS optical fiber sensing

Abstract

The invention provides a goaf slope lattice beam strain monitoring and demodulation system based on MEMS optical fiber sensing, and belongs to the technical field of goaf slope lattice beam strain monitoring and demodulation. In order to solve the technical problems that an existing lattice beam monitoring system can only measure physical quantity in one direction, cannot achieve full-time coverage and cannot monitor dynamic and static strain of a lattice beam at the same time in measurement, the adopted technical scheme is that balls capable of rotating are arranged at the top and the bottom of a first rolling screw and the top and the bottom of a second rolling screw; the first rolling screw and the second rolling screw can roll on a first rolling screw limiting groove formed in the horizontal direction through the balls, and the first rolling screw and the second rolling screw are connected and fixed through a first connecting rod. A first spiral compression spring is arranged in the first spring limiting groove, and a second spiral compression spring is arranged in the second spring limiting groove. The method is applied to goaf slope lattice girder strain monitoring.

Description

Technical Field

[0001] This invention provides a strain monitoring and demodulation system for grid beams on goaf slopes based on MEMS fiber optic sensing, belonging to the field of strain monitoring and demodulation technology for grid beams on goaf slopes. Background Technology

[0002] With the large-scale development of mineral resources, the stability of goaf slopes has become increasingly prominent, posing a significant threat to mine safety and the surrounding environment. Due to disturbances caused by underground mining activities, the stress and displacement fields of goaf slopes change significantly, making them prone to instability and even landslides. While lattice beams, a common slope protection measure, effectively improve slope stability by forming an integrated load-bearing system through the interlacing of longitudinal and transverse beams, their structural performance gradually deteriorates under long-term service conditions due to various external forces and environmental influences. Long-term monitoring is necessary to ensure safety. Current stress-strain monitoring methods for lattice beams suffer from technical defects such as large measurement errors, insufficient real-time performance, and inability to operate stably for extended periods. Furthermore, the complex structure and poor stability of these systems lead to difficulties in later maintenance and testing, resulting in high operating costs. These issues all restrict the safety assurance capabilities of slope protection projects.

[0003] Meanwhile, traditional slope monitoring methods, such as total station measurement and GPS monitoring, have drawbacks such as limited monitoring range, poor real-time performance, and weak anti-interference ability, making it difficult to meet the needs of long-term stable monitoring in complex environments such as mining subsidence areas. In particular, in such harsh environments, conventional electronic sensors are easily affected by electromagnetic interference, moisture and corrosion, making it difficult to guarantee the reliability of monitoring data and the stability of the system.

[0004] In recent years, fiber optic sensors have demonstrated great potential in the field of structural health monitoring due to their advantages of high sensitivity, long-term stability, reliability, multi-point monitoring capability, and adaptability to complex environments. For crack detection and health monitoring of facilities such as lattice beams, fiber optic sensors can provide continuous, efficient, and accurate solutions, effectively improving the accuracy and real-time performance of monitoring. However, current fiber optic grating sensing technology still has some shortcomings in the application of lattice beam structural health monitoring, such as: relatively simple physical quantities being monitored, small measurement range, slow response speed, high false alarm rate, and cross-sensitivity issues related to temperature and strain, which need to be improved. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention adopts the following technical solution: A strain monitoring system for a grid beam in a goaf slope based on MEMS fiber optic sensing is provided, comprising a vertical settlement monitoring component and a horizontal tensile monitoring component. The vertical settlement monitoring component includes: The components include: a first rolling screw limiting groove, a first rolling screw, a first connecting rod, a second rolling screw, a first spring limiting groove, a first helical compression spring, a first FP base, a first movable sensitive element, a first fiber optic collimator, a second spring limiting groove, a second helical compression spring, a fixed wall, a limiting rod, and a T-shaped connecting rod, wherein: The first rolling screw and the second rolling screw are provided with rotatable balls at their top and bottom. The balls enable the first rolling screw and the second rolling screw to roll on the first rolling screw limiting groove set in the horizontal direction. The first rolling screw and the second rolling screw are connected and fixed by a first connecting rod. A first helical compression spring is provided in the first spring limiting groove, and a second helical compression spring is provided in the second spring limiting groove. The T-shaped connecting rod is horizontally installed on the first spring limiting groove and the second spring limiting groove, and can compress the first helical compression spring and the second helical compression spring vertically downward. A first movable sensitive element is also provided on the T-shaped connecting rod. A highly reflective coating is applied to the surface of the first movable sensing element. The first movable sensing element and the first FP base form an FP cavity through a piston-like structure. A first fiber collimator is set on the first movable sensing element to collimate the fiber, so that the incident light can be perpendicularly incident into the FP cavity. A T-shaped vertical groove is provided inside the fixed wall to accommodate the T-shaped connecting rod, so that the T-shaped connecting rod can only move vertically inside the fixed wall. A limit rod is also provided below the T-shaped connecting rod; The horizontal tensile monitoring component includes: The components include: a third rolling screw limiting groove, a third rolling screw, a third helical compression spring, a fourth helical compression spring, a second movable sensitive element, an FP cavity, a high-reflectivity light coating, a second FP base, a second fiber collimator, a second connecting rod, and a fiber optic connector, wherein: Both ends of the third rolling screw are provided with rotatable steel balls. A pair of third rolling screw limiting grooves are also provided on the inner wall of the horizontal tensile monitoring component. The steel balls are installed in the third rolling screw limiting grooves so that the third rolling screw can only move in the vertical direction. The third rolling screw is connected to the second movable sensing element through the second connecting rod. The surface of the second movable sensing element is coated with a high-reflectivity coating. The second movable sensing element and the second FP base form an FP cavity through a piston-like structure. A third helical compression spring and a fourth helical compression spring are also provided between one end of the opening of the second FP base and the second movable sensing element. The second fiber collimator provided on the second movable sensing element collimates the fiber, so that the incident light can be perpendicularly injected into the FP cavity. The fiber optic connector connects the monitoring system and the demodulation system via a transmission fiber.

[0006] A first omnidirectional wheel and a first omnidirectional wheel limit rod are also provided on the outside of the vertical settlement monitoring component; A second omnidirectional wheel and a second omnidirectional wheel limit rod are also provided on the outside of the horizontal tension monitoring component.

[0007] The strain demodulation system of the grid beam of the goaf slope based on MEMS fiber optic sensing includes an MGY type tunable laser, a signal acquisition module, and a computer. The optical signal output end of the MGY type tunable laser is connected to the input end of an optical isolator, and the output end of the optical isolator is connected to the b end of the first one-to-two coupler. The pulse signal output terminal of the MGY-type tunable laser is connected to the a-pulse signal receiving terminal of the signal acquisition module, and the d-output terminal of the signal acquisition module is connected to the a-port of the computer. The C output terminal of the first 1-to-2 coupler is connected to the A input terminal of the second 1-to-2 coupler; The a-end of the first splitter is connected to the a-optical signal input end of the optical switch, and the b-control end of the optical switch is connected to the b-control signal output end of the computer. The optical signal output terminal of the optical switch is connected to multiple transmission optical fibers, which are then connected to the optical fiber connectors of different monitoring systems. The b output terminal of the second one-to-two coupler is connected to the b acquisition terminal of the signal acquisition module via the first optical bandpass filter, the first photoelectric converter, the first signal amplification module, and the first filtering module in sequence. The output terminal C of the second 1-to-2 coupler is connected to the acquisition terminal C of the signal acquisition module via the second optical bandpass filter, the second photoelectric converter, the second signal amplification module, and the second filtering module in sequence.

[0008] The present invention has the following advantages over the prior art: I. In view of the defects of the device for monitoring the strain of the grid beam on the slope of the goaf, which can only monitor a single variable in a certain direction, this invention designs two fiber Fabry-Perot (FP) interferometric MEMS gratings in the horizontal and vertical directions to realize the simultaneous monitoring of the horizontal tensile displacement and vertical settlement of the key parts of the grid beam, and realize the simultaneous monitoring of the multi-directional, static and dynamic strain of the grid beam. 2. To avoid the influence of ambient temperature changes on the measurement results of the monitoring device, this invention adopts a fiber optic Fabry-Perot (FP) interferometric MEMS grating, which monitors displacement based on the principle of two-beam interference. It is not easily affected by ambient temperature, thus improving the stability and accuracy of the monitored values. Third, in terms of fiber optic grating demodulation systems, this invention employs an MGY-type tunable laser with tunable scanning step and scanning frequency, fully leveraging its advantages of high stability and high precision. This effectively reduces system costs while ensuring high-precision, high-resolution, and high-stability demodulation of the reflected signals from sensor monitoring devices. Attached Figure Description

[0009] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the lattice beam strain monitoring system in the goaf slope lattice beam strain monitoring and demodulation system of the present invention; Figure 2 This is a front view of the vertical settlement monitoring component A in the lattice beam strain monitoring system of the present invention; Figure 3 This is a schematic diagram of the fiber optic grating demodulation system in the goaf slope grid beam strain monitoring and demodulation system of the present invention; Figure 4 This is an installation effect diagram of the sensor monitoring device at the grid beam of the goaf slope in an embodiment of the present invention; The meanings of the numbers in the diagram are as follows: 1 is the first omnidirectional wheel, 2 is the first omnidirectional wheel limiting rod, 3 is the first rolling screw limiting groove, 4 is the first rolling screw, 5 is the first connecting rod, 6 is the second rolling screw, 7 is the first spring limiting groove, 8 is the first helical compression spring, 9 is the first FP base, 10 is the first movable sensitive element, 11 is the first fiber collimator, 12 is the second spring limiting groove, 13 is the second helical compression spring, 14 is the fixed wall, 15 is the limiting rod, 16 is the T-shaped connecting rod, 17 is the third rolling screw limiting groove, 18 is the third rolling screw, 19 is the second omnidirectional wheel, 20 is the second omnidirectional wheel limiting rod, 21 is the third helical compression spring, 22 is the fourth helical compression spring, 23 is the second movable sensitive element, 24 is the FP cavity, 25 is the high reflectivity coating, 26 is the second FP base, 27 is the second fiber collimator, 28 is the second connecting rod, and 29 is the fiber connector. 30 is the first transmission fiber, 31 is the second transmission fiber, 32 is the third transmission fiber, 33 is the fourth transmission fiber, 34 is an optical switch, 35 is the first 1-to-2 coupler, 36 is an optical isolator, 37 is an MGY-type tunable laser, 38 is the second 1-to-2 coupler, 39 is the first optical bandpass filter, 40 is the second optical bandpass filter, 41 is the first photoelectric converter, 42 is the second photoelectric converter, 43 is the first signal amplification module, 44 is the second signal amplification module, 45 is the first filtering module, 46 is the second filtering module, 47 is the signal acquisition module, and 48 is a computer. Detailed Implementation

[0010] like Figures 1 to 4 As shown, this invention addresses the numerous limitations of traditional lattice beam monitoring systems in measurement, such as the inability to measure physical quantities unidirectionally, the inability to achieve full-time coverage, and the inability to simultaneously monitor the dynamic and static strain of lattice beams. It provides a MEMS fiber optic sensing-based strain monitoring and demodulation system for lattice beams in goaf slopes. This system leverages the superior sensitivity of fiber optic Fabry-Perot (FP) interferometric MEMS gratings to accurately monitor minute displacements and crack changes in slope lattice beams, exhibiting significant advantages, particularly in the dynamic and static monitoring of strain at key locations in slope lattice beams. This invention designs horizontal and vertical... Two fiber optic Fabry-Perot (FP) interferometric MEMS gratings, based on the principle of two-beam interference, enable simultaneous monitoring of horizontal tensile displacement and vertical settlement of key parts of the lattice beam. This allows for simultaneous monitoring of multi-directional, static, and dynamic strain of the lattice beam. A fiber optic grating demodulation system with high demodulation accuracy, high refresh rate, and high stability is used to accurately demodulate the monitored values. This system enables long-term, stable, and high-precision strain monitoring of slope lattice beams, significantly improving the reliability and accuracy of slope lattice beam health monitoring and providing solid data support for the safety assessment and maintenance of slope lattice beams.

[0011] The goaf slope grid beam strain monitoring and demodulation system provided by this invention consists of two parts: a sensor monitoring system and a fiber optic grating demodulation system. The sensor monitoring system can be further divided into a vertical settlement monitoring component A and a horizontal tensile monitoring component B. The vertical settlement monitoring component A includes: 1. First omnidirectional wheel; 2. First omnidirectional wheel limiting rod; 3. First rolling screw limiting groove; 4. First rolling screw; 5. First connecting rod; 6. Second rolling screw; 7. First spring limiting groove; 8. First helical compression spring; 9. First FP base; 10. First movable sensitive element; 11. First fiber collimator; 12. Second spring limiting groove; 13. Second helical compression spring; 14. Fixed wall; 15. Limiting rod; 16. T-shaped connecting rod, wherein: The first omnidirectional wheel 1 and the first omnidirectional wheel limiting rod 2, and the second omnidirectional wheel 19 and the second omnidirectional wheel limiting rod 20 work together to ensure accurate monitoring of horizontal displacement and vertical settlement by the sensor monitoring device, and also to fix the device. The first rolling screw 4 and the second rolling screw 6 have 360-degree rotating balls at their top and bottom. This design allows the first rolling screw 4 and the second rolling screw 6 to roll smoothly in the horizontal direction, effectively avoiding the influence of horizontal displacement on vertical settlement monitoring. The first rolling screw limiting groove 3 has a groove in the middle that can fit with the steel balls at both ends of the first rolling screw 4 and the second rolling screw 6. This groove allows the first rolling screw 4 and the second rolling screw 6 to move horizontally while restricting their vertical movement. The first connecting rod 5 connects and fixes the first rolling screw 4 and the second rolling screw 6. The first spring limiting groove 7 and the second spring limiting groove 12 have a middle section that allows the T-shaped connecting rod 16 to press vertically downwards. The circular groove of the spiral compression spring, the first spring limiting groove 7 and the second spring limiting groove 12, while restricting the first spiral compression spring 8 and the second spiral compression spring 13, allow the T-shaped connecting rod 16 to drive the first movable sensitive element 10 to compress the spiral compression spring downward when vertical sinking occurs. The first spiral compression spring 8 and the second spiral compression spring 13 support the T-shaped connecting rod 16. The surface of the first movable sensitive element 10 is coated with a high-reflectivity coating, and it and the first FP base 9 form an FP cavity together through a piston-like structure. The first fiber collimator 11 collimates the fiber, so that the incident light enters the FP cavity vertically. There is a T-shaped vertical groove in the wall of the fixed wall 14 that can fit with the T-shaped connecting rod 16. With this design, the T-shaped connecting rod 16 can move smoothly in the vertical direction without moving in the horizontal direction. The limiting rod 15 limits the T-shaped connecting rod 16, and restricts the T-shaped connecting rod 16 from moving downward when it moves to the maximum range.

[0012] The horizontal tension monitoring component B includes: The following components are included: third rolling screw limiting groove 17, third rolling screw 18, second omnidirectional wheel 19, second omnidirectional wheel limiting rod 20, third helical compression spring 21, fourth helical compression spring 22, second movable sensitive element 23, FP cavity 24, high reflectivity coating 25, second FP base 26, second fiber collimator 27, second connecting rod 28, and fiber optic connector 29. The third rolling screw 18 has steel balls at both ends that can rotate 360 ​​degrees. This design allows the third rolling screw 18 to roll smoothly in the vertical direction, effectively avoiding the influence of vertical settlement on horizontal displacement monitoring. The limiting groove 17 of the third rolling screw has a groove in the middle that can fit with the steel balls at both ends of the third rolling screw 18. This groove allows the third rolling screw 18 to move vertically while restricting its horizontal movement. The third rolling screw 18 is connected to the second movable sensing element 23 through the second connecting rod 28. The surface of the second movable sensing element 23 is coated with a high-reflectivity coating 25 to ensure light... Due to the high reflectivity of the signal, the second movable sensing element 23 and the second FP base 26 together form an FP cavity 24 through a piston-like structure. The second fiber collimator 27 collimates the fiber, so that the incident light enters the FP cavity 24 perpendicularly. The fiber connector 29 is connected to the transmission fiber and serves to connect the monitoring device and the fiber optic demodulation system. When the crack in the slope lattice beam expands horizontally, the second connecting rod 28 drives the second movable sensing element 23 to compress the spiral compression spring and change the cavity length of the FP cavity 24. The fiber optic demodulation system monitors the horizontal displacement by demodulating the change in the cavity length of the FP cavity 24.

[0013] The fiber grating demodulation system provided by this invention includes: The system comprises: a first transmission fiber 30, a second transmission fiber 31, a third transmission fiber 32, a fourth transmission fiber 33, an optical switch 34, a first splitter coupler 35, an optical isolator 36, an MGY-type tunable laser 37, a second splitter coupler 38, a first optical bandpass filter 39, a second optical bandpass filter 40, a first photoelectric converter 41, a second photoelectric converter 42, a first signal amplification module 43, a second signal amplification module 44, a first filtering module 45, a second filtering module 46, a signal acquisition module 47, and a computer 48, wherein: The optical signal output terminal of the MGY-type tunable laser 37 is connected to the input terminal of the optical isolator 36. The pulse signal output terminal of the MGY-type tunable laser 37 is connected to the a-pulse signal receiving terminal of the signal acquisition module 47. The output terminal of the optical isolator 36 is connected to the b-terminal of the first 1-to-2 coupler 35. The a-terminal of the first 1-to-2 coupler 35 is connected to the a-optical signal input terminal of the optical switch 34. The c-output terminal of the first 1-to-2 coupler 35 is connected to the a-input terminal of the second 1-to-2 coupler 38. The b-control terminal of the optical switch 34 is connected to the b-control signal output terminal of the computer 48. The c, d, e, and f-optical signal output terminals of the optical switch 34 are each connected to a transmission optical fiber. The transmission fiber 30, the second transmission fiber 31, the third transmission fiber 32, and the fourth transmission fiber 33 are respectively connected to the fiber optic connectors 29 of different sensor monitoring devices. The b output terminal of the second splitter 38 is connected to the b acquisition terminal of the signal acquisition module 47 via the first optical bandpass filter 39, the first photoelectric converter 41, the first signal amplification module 43, and the first filtering module 45. The c output terminal of the second splitter 38 is connected to the c acquisition terminal of the signal acquisition module 47 via the second optical bandpass filter 40, the second photoelectric converter 42, the second signal amplification module 44, and the second filtering module 46. The d output terminal of the signal acquisition module 47 is connected to the a port of the computer 48.

[0014] like Figure 1 The diagram shows the structural schematic of the lattice beam strain monitoring device in the MEMS fiber optic sensing-based lattice beam strain monitoring and demodulation system for goaf slopes. Figure 3 This is a schematic diagram of the fiber Bragg grating demodulation system in a MEMS fiber optic sensing-based strain monitoring and demodulation system for lattice beams in goaf slopes. The following section combines... Figure 1 and Figure 3 The specific implementation method of the present invention is described below: When the monitoring system of the present invention is working, the MGY-type tunable laser 37 periodically emits narrowband light from 1527nm to 1567nm in a constant step and inputs it to the input terminal of the optical isolator 36. At the same time, after the MGY-type tunable laser 37 completes one cycle of narrowband light emission, it inputs a trigger signal to the signal acquisition module 47. After receiving the trigger signal from the MGY-type tunable laser 37, the signal acquisition module 47 begins to acquire the output signals from the output terminals of the first filter module 45 and the second filter module 46. After the acquisition is completed, the signal acquisition module 47 transmits the acquired data to the computer 48 via USB serial communication. The output of the optical isolator 36 transmits the incident light emitted by the MGY-type tunable laser 37 to the b end of the first split-coupler 35, while isolating the reflected light to prevent it from damaging the MGY-type tunable laser 37. The a end of the first split-coupler 35 outputs the laser light input from the b end to the a input end of the optical switch 34. The b control end of the optical switch 34 is connected to the b control signal output end of the computer 48. The computer 48 controls the on / off states of the c, d, e, and f output ends of the optical switch 34, thereby realizing the switching connection of different transmission optical fibers and achieving demodulation of multiple channels and multiple sensors.

[0015] When the sensor detects vertical subsidence, the sensor housing applies this subsidence to the first rolling screw 4 and the second rolling screw 6. The first rolling screw 4 and the second rolling screw 6 drive the T-shaped connecting rod 16 to compress the first helical compression spring 8 and the second helical compression spring 13, causing the first movable sensing element 10 to move downwards and change the cavity length of the FP cavity. By monitoring the change in the cavity length of the FP cavity, the vertical subsidence of the lattice beam can be monitored. In addition, when horizontal displacement occurs, the first rolling screw 4 and the second rolling screw 6 will move horizontally along the first rolling screw limiting groove 3. This design can effectively avoid the influence of horizontal displacement on the monitoring of vertical subsidence. When the monitoring device detects horizontal tension, the second connecting rod 28 drives the second movable sensing element 23 to compress the third helical compression spring 21 and the fourth helical compression spring 22, thereby changing the cavity length of the FP cavity 24. By monitoring the change in the cavity length of the FP cavity, the horizontal tension of the lattice beam can be monitored. In addition, when vertical sinking occurs, the third rolling screw 18 will move vertically along the third rolling screw limiting groove 17. This design can effectively avoid the impact of vertical sinking on horizontal displacement monitoring.Under computer control, optical switch 34 selects a designated transmission fiber optic channel in real time. The reflected light signal from the corresponding monitoring device is transmitted back to optical switch 34 through this channel. Optical switch 34 then transmits the target light signal to the first splitter coupler 35. The reflected light output from the b-end of the first splitter coupler 35 is isolated by optical isolator 36. The c-end of the first splitter coupler 35 transmits the reflected light to the a-end of the second splitter coupler 38. The b-end of the second splitter coupler 38 transmits the reflected light to the input of the first optical bandpass filter 39. The output of the second 1-to-2 coupler 38 transmits the reflected light to the input of the second optical bandpass filter 40. The first optical bandpass filter 39 filters out the light wave corresponding to the vertical fiber Fabry-Perot (FP) interferometer MEMS grating in the reflected light and transmits it to the input of the first photoelectric converter 41. The second optical bandpass filter 40 filters out the light wave corresponding to the horizontal fiber Fabry-Perot (FP) interferometer MEMS grating in the reflected light and transmits it to the input of the second photoelectric converter 42. The first photoelectric converter 41 transmits the reflected light to the input of the second optical bandpass filter 42. After the optical signal is converted into an electrical signal, it is transmitted to the input terminal of the first signal amplification module 43 through the output terminal. The second photoelectric converter 42 converts the input optical signal into an electrical signal and transmits it to the input terminal of the second signal amplification module 44 through the output terminal. The first signal amplification module 43 amplifies the input electrical signal and transmits the amplified signal to the input terminal of the first filtering module 45 through the output terminal. The second signal amplification module 44 amplifies the input electrical signal and transmits the amplified signal to the input terminal of the second filtering module 46 through the output terminal. The first filtering module 45 filters out interference in the electrical signal and transmits the signal to the b acquisition terminal of the signal acquisition module 47 through the output terminal. The second filtering module 46 filters out interference in the electrical signal and transmits the signal to the c acquisition terminal of the signal acquisition module 47 through the output terminal. After acquiring the signals transmitted to it by the first filtering module 45 and the second filtering module 46, the signal acquisition module 47 transmits the acquired data to the a port of the computer 48 in a unified format. After demodulating the data acquired by the signal acquisition module 47, the computer 48 can calculate the magnitude of the strain of the lattice beam.

[0016] Figure 1 The strain monitoring device for the lattice beam shown is arranged at the key nodes of the slope lattice beam, such as... Figure 4 As shown.

[0017] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A strain monitoring system for grid beams in goaf slopes based on MEMS fiber optic sensing, comprising a vertical settlement monitoring component and a horizontal tensile monitoring component, characterized in that: The vertical subsidence monitoring component includes: The components are: first rolling screw limiting groove (3), first rolling screw (4), first connecting rod (5), second rolling screw (6), first spring limiting groove (7), first helical compression spring (8), first FP base (9), first movable sensitive element (10), first fiber collimator (11), second spring limiting groove (12), second helical compression spring (13), fixed wall (14), limiting rod (15), and T-shaped connecting rod (16), wherein: The first rolling screw (4) and the second rolling screw (6) are provided with rotatable balls at their top and bottom. The balls enable the first rolling screw (4) and the second rolling screw (6) to roll on the first rolling screw limiting groove (3) set in the horizontal direction. The first rolling screw (4) and the second rolling screw (6) are connected and fixed by the first connecting rod (5). A first helical compression spring (8) is provided in the first spring limiting groove (7), and a second helical compression spring (13) is provided in the second spring limiting groove (12). The T-shaped connecting rod (16) is horizontally installed on the first spring limiting groove (7) and the second spring limiting groove (12), and can compress the first helical compression spring (8) and the second helical compression spring (13) vertically downward. A first movable sensitive element (10) is also provided on the T-shaped connecting rod (16). A highly reflective coating is applied to the surface of the first movable sensing element (10). The first movable sensing element (10) and the first FP base (9) form an FP cavity through a piston-like structure. The first fiber collimator (11) set on the first movable sensing element (10) collimates the fiber so that the incident light can be perpendicularly injected into the FP cavity. A T-shaped vertical groove is provided inside the fixed wall (14) to accommodate the T-shaped connecting rod (16), so that the T-shaped connecting rod (16) can only move vertically inside the fixed wall (14); A limit rod (15) is also provided below the T-shaped connecting rod (16); The horizontal tensile monitoring component includes: The components include: a third rolling screw limiting groove (17), a third rolling screw (18), a third helical compression spring (21), a fourth helical compression spring (22), a second movable sensitive element (23), an FP cavity (24), a high-reflectivity light coating (25), a second FP base (26), a second fiber collimator (27), a second connecting rod (28), and a fiber optic connector (29). Both ends of the third rolling screw (18) are provided with rotatable steel balls. A pair of third rolling screw limiting grooves (17) are also provided on the inner wall of the horizontal tension monitoring component. The steel balls are installed in the third rolling screw limiting grooves (17) so that the third rolling screw (18) can only move in the vertical direction. The third rolling screw (18) is connected to the second movable sensitive element (23) through the second connecting rod (28). The surface of the second movable sensitive element (23) is coated with a high reflective coating (25). The second movable sensitive element (23) and the second FP base (26) form an FP cavity (24) through a piston-like structure. A third helical compression spring (21) and a fourth helical compression spring (22) are also provided between one end of the opening of the second FP base (26) and the second movable sensitive element (23). The second fiber collimator (27) provided on the second movable sensitive element (23) collimates the fiber so that the incident light can be perpendicularly injected into the FP cavity (24). The fiber optic connector (29) connects the monitoring system and the demodulation system via a transmission fiber.

2. The strain monitoring system for grid beams in goaf slopes based on MEMS fiber optic sensing according to claim 1, characterized in that: A first omnidirectional wheel (1) and a first omnidirectional wheel limiting rod (2) are also provided on the outside of the vertical settlement monitoring component. A second omnidirectional wheel (19) and a second omnidirectional wheel limiting rod (20) are also provided on the outside of the horizontal tension monitoring component.

3. A strain demodulation system for a goaf slope grid beam based on MEMS fiber optic sensing, comprising an MGY-type tunable laser (37), a signal acquisition module (47), and a computer (48), characterized in that: The optical signal output terminal of the MGY type tunable laser (37) is connected to the input terminal of the optical isolator (36), and the output terminal of the optical isolator (36) is connected to the b terminal of the first split-coupler (35). The pulse signal output terminal of the MGY type tunable laser (37) is connected to the a pulse signal receiving terminal of the signal acquisition module (47), and the d output terminal of the signal acquisition module (47) is connected to the a port of the computer (48). The c output terminal of the first split-coupler (35) is connected to the a input terminal of the second split-coupler (38); The a end of the first split-coupler (35) is connected to the a optical signal input end of the optical switch (34), and the b control end of the optical switch (34) is connected to the b control signal output end of the computer (48). The optical signal output terminal of the optical switch (34) is connected to multiple transmission optical fibers, and the optical fiber connectors (29) of different monitoring systems are connected through the multiple transmission optical fibers. The b output terminal of the second one-to-two coupler (38) is connected to the b acquisition terminal of the signal acquisition module (47) in sequence via the first optical bandpass filter (39), the first photoelectric converter (41), the first signal amplification module (43), and the first filtering module (45); The output terminal of the second split-coupler (38) is connected to the acquisition terminal of the signal acquisition module (47) via the second optical bandpass filter (40), the second photoelectric converter (42), the second signal amplification module (44), and the second filtering module (46) in sequence.

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