An underground rescue monitoring system and method based on distributed optical fiber sensing system

Abstract

The present invention discloses an underground rescue monitoring system based on a distributed fiber optic sensing system. The system comprises a distributed fiber optic sensing system, a multiplexed optical switch, a sensing optical cable, and a vibration encoding device. The vibration encoding device is activated after being placed in close proximity to the sensing optical cable, encoding a user's distress message into a corresponding vibration signal. The encoded vibration signal is automatically transmitted to the distributed fiber optic sensing system using parallel transmission via the sensing optical cable. The distributed fiber optic sensing system decodes the vibration encoding device's underground three-dimensional spatial coordinates and the user's distress message. The present invention fully utilizes existing facilities to achieve large-scale, long-distance, multi-point distributed sensing. It is suitable for providing timely warnings of abnormal signals before underground accidents occur. During the rescue process, trapped personnel underground can send distress messages to personnel on the ground, effectively improving rescue efficiency and reducing casualties.

Description

Technical Field

[0001] The present invention belongs to the field of sensor communication technology, and in particular relates to an underground rescue monitoring system and method based on a distributed optical fiber sensing system. Background Art

[0002] Distributed fiber-optic sensing systems use optical fibers as both sensing elements and transmission media, leveraging Rayleigh scattering signals to achieve distributed measurement of vibration signals along the fiber. These systems offer advantages such as strong anti-interference capabilities, a wide monitoring range, high sensitivity, quantitative analysis capabilities, and resistance to electromagnetic interference. Currently, an underground fiber-optic vibration distress call system based on this distributed fiber-optic sensing system has been developed. This system uses cries for help as the sound source. Once detected by the optical fiber, it is demodulated and amplified on the surface, combining positioning and communication. Furthermore, this system can utilize existing underground optical cables, offering significant advantages in rescue operations. However, due to the complex underground environment and the extensive filling and reinforcement layers of laid optical cables, the vibration intensity generated by using cries for help as the sound source is low, resulting in a low signal-to-noise ratio (SNR). This often makes it difficult to demodulate the acoustic signal content, and continuous calls for help underground consume significant energy, hindering rescue efforts.

[0003] The invention with publication number CN112857555A discloses a device for collecting underground sensors, including a vibration generator, an underground communication optical cable, and an optical fiber distributed vibration sensor. After the vibration generator receives data transmitted from sensors at different locations underground, it performs vibration encoding and converts it into a vibration signal, and acts on the underground communication optical cable. The light distributed vibration sensor on the ground detects and locates the vibration of the underground communication optical cable, obtains the vibration code of the sensor at the corresponding position, and decodes it to obtain the data output by the underground sensor at the corresponding position. However, this invention cannot realize the active input of information by personnel, is not suitable for underground rescue scenarios, and does not involve technical issues such as the frame format of vibration coding, the simultaneous transmission of information at multiple points, and early warning of abnormal signals.

[0004] Patent application CN114263502A discloses a post-disaster emergency communication method for mines based on fiber optic sensing. A vibrator consisting of a motor and an elastic rod generates vibration signals of varying frequencies. The semantic information represented by each fixed-frequency vibration signal is pre-encoded and determined. The vibration signal and its associated semantics are then demodulated using fiber optic sensing. However, this invention does not address the digitization of semantic information. Using only frequency-corresponding semantics, the information that can be transmitted is very limited. It also does not address technical issues such as simultaneous multi-point information transmission and early warning of abnormal signals.

[0005] This invention combines vibration encoding equipment with a distributed fiber optic sensing system to create a novel underground rescue monitoring technology. This technology can provide rapid location and early warning before an accident occurs, prompting underground personnel to evacuate quickly. After an accident occurs, trapped personnel can simply transmit key information to the surface, including their location, number of trapped individuals, oxygen and gas levels, and food and water reserves, facilitating subsequent rescue efforts. Summary of the Invention

[0006] Technical problem solved: In response to the shortcomings of existing underground rescue monitoring methods after an accident, the present invention combines vibration encoding equipment with a distributed fiber optic sensing system to propose an underground rescue monitoring system and method based on a distributed fiber optic sensing system. The system can quickly locate and warn in advance before an accident occurs, prompting underground personnel to quickly take emergency shelter. After an accident occurs, trapped personnel only need to perform simple operations to transmit key information such as location, number of trapped people, oxygen content, gas content, food and water storage to the ground, facilitating subsequent rescue.

[0007] An underground rescue monitoring system based on a distributed optical fiber sensing system, the underground rescue monitoring system comprising a distributed optical fiber sensing system, a multiplex optical switch, a sensing optical cable and a vibration encoding device;

[0008] The distributed optical fiber sensing system is installed in a ground-based machine room and is connected to a single-end underground sensing optical cable network via a multiplex optical switch. A database of mapping relationships between one-dimensional optical cable sheath length and underground three-dimensional spatial coordinates is constructed in the distributed optical fiber sensing system.

[0009] The vibration encoding device is started after being closely attached to the sensor optical cable, and encodes the distress information input by the user into a corresponding vibration signal. The encoded vibration signal is automatically sent to the distributed optical fiber sensing system using parallel transmission of the sensor optical cable. The distributed optical fiber sensing system collects the backscattered Rayleigh scattering signal along the sensor optical cable, subtracts it from the background noise, records the location where the vibration signal occurs, and decodes the demodulated vibration signal to obtain the three-dimensional spatial coordinates of the underground location of the vibration encoding device and the distress information input by the user.

[0010] Furthermore, the distributed optical fiber sensing system is equipped with an abnormal vibration signal recognition unit and an early warning unit;

[0011] The abnormal vibration signal identification unit is used to identify abnormal vibration signals on the sensor optical cable. When an abnormal vibration signal is identified, the early warning unit is activated to alarm underground personnel; the abnormal vibration signal includes but is not limited to transient strong vibration, abnormal low-frequency deformation and high-frequency vibration signals.

[0012] Furthermore, the early warning unit includes an underground broadcasting system and a wireless communication system.

[0013] Furthermore, each underground passage branch is provided with at least three calibration points, which are respectively located at the underground passage branch head, the underground passage branch midpoint, and the underground passage branch tail.

[0014] Furthermore, the distress information includes the number of trapped people, the number of injured people, oxygen content, gas concentration, remaining food and remaining water.

[0015] Furthermore, the vibration encoding device uses serial communication encoding with a baud rate of 10 to distinguish 0 and 1 by the presence or absence of vibration.

[0016] Furthermore, one of the encoded vibration signals includes a guide word, multiple data words and a check word; each word contains 10 bits, namely a start bit, 8 valid data bits and a stop bit, the start bit is fixed to 1, the stop bit is fixed to 0, and the data bits are corresponding data in the range of 0~255; among which, the valid data bits of the guide word are fixed to 10100101, and the valid data bits of the check word are the sum check of the valid data bits of all data words.

[0017] Further, the vibration encoding device includes a dial;

[0018] The dial includes a processor, a display screen and multiple input buttons, and different input buttons correspond to different emergency parameters; an encoding module is installed in the processor, which integrates the emergency parameters input by different input buttons and encodes them to obtain corresponding vibration signals; the display screen is used to display the emergency parameter column, the input information of all emergency parameter columns and the working status of the dial.

[0019] Furthermore, the vibration encoding device also includes two fixing straps, which are respectively connected to both sides of the dial; one of the fixing straps is provided with a buckle, and the other fixing strap passes through the buckle to wrap around and fix the dial to the sensor optical cable or wear it on the user.

[0020] The present invention also provides an underground rescue monitoring method based on a distributed optical fiber sensing system, the underground rescue monitoring method comprising the following steps:

[0021] Tap the optical cable at different locations underground to calibrate the position and establish a mapping relationship between the one-dimensional optical cable sheath length and the three-dimensional underground spatial coordinates;

[0022] Long-term monitoring of vibration signals on the sensor optical cable allows for rapid identification of abnormal vibration signals. When an abnormal vibration signal is identified, the broadcasting system and wireless communication system are linked to issue an alarm, allowing underground personnel to evacuate to nearby safe areas after receiving the alarm.

[0023] After an underground accident occurs, trapped people use vibration encoding equipment to input distress signals, and the vibration signals are transmitted to the sensing optical cables by placing the vibration encoding equipment close to the sensing optical cables. The distributed optical fiber sensing system monitors the vibration signals, records the locations where the vibration signals occur, and demodulates the vibration signals. The demodulated vibration signals are decoded into distress signals, and the positioning is performed based on the mapping relationship between the one-dimensional optical cable sheath length and the three-dimensional spatial coordinates of the underground space, completing the survey of underground environmental information to carry out rescue work.

[0024] The beneficial effects of the present invention are:

[0025] First, the underground rescue monitoring system and method based on the distributed fiber optic sensing system of the present invention monitors vibration signals over a long period of time. When an abnormal signal is identified that may lead to an accident, a rapid warning is issued, and the broadcast system and wireless communication system are linked to issue an alarm, thereby buying emergency evacuation time for underground personnel.

[0026] Second, the underground rescue monitoring system and method of the present invention is based on a distributed fiber optic sensing system. After an accident occurs, the trapped personnel send encoded vibration signals to the optical cable through a vibration encoding device, and the ground personnel monitor and decode the vibration signals through the distributed fiber optic sensing system, thereby realizing information transmission from underground to ground.

[0027] Third, the underground rescue monitoring system and method based on the distributed fiber optic sensing system of the present invention can utilize the existing underground optical cable network to achieve long-distance, large-scale distributed monitoring at a relatively low cost, and quickly and accurately locate the position of trapped persons in the first time after an accident occurs. At the same time, optical fiber is a passive device, does not require power supply and is not affected by electromagnetic interference, and has high reliability.

[0028] Fourth, the underground rescue monitoring system and method based on the distributed optical fiber sensing system of the present invention does not rely on electricity. It can realize the accurate transmission of information from people trapped underground to the ground without the need for power supply. It can be used as a supplementary means for underground emergency rescue and provides great help for rescue work.

[0029] Fourth, the underground rescue monitoring system and method based on a distributed fiber optic sensing system can transmit a wide range of information. Traditional methods that rely on vibration signals to transmit information typically only send location information. However, using vibration encoding equipment can transmit a large amount of vital and environmental information about trapped individuals to personnel on the ground, providing high signal strength and a high signal-to-noise ratio, making it less susceptible to coherent fading noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a signal processing flow chart of an underground rescue monitoring system based on a distributed optical fiber sensing system according to an embodiment of the present invention.

[0031] Figure 21 is a schematic diagram of the overall structure of an underground rescue monitoring system based on a distributed optical fiber sensing system according to an embodiment of the present invention;

[0032] Figure 3 This is a diagram of the simulated interface of the vibration encoding device;

[0033] Figure 4 This is a schematic diagram of a fixed belt for a vibration encoding device;

[0034] Figure 5 It is a side view of another type of vibration encoding device fixed with a belt;

[0035] Figure 6 is the format of the data frame;

[0036] Figure 7 It is the waterfall diagram and demodulation result of the coded vibration signal sent at 22375m and 22475m. Implementation Method

[0037] The following examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0038] This embodiment discloses an underground rescue monitoring system based on a distributed optical fiber sensing system, which includes a distributed optical fiber sensing system, a multiplex optical switch, a sensing optical cable, and a vibration encoding device;

[0039] The distributed optical fiber sensing system is installed in a ground-based machine room and is connected to a single-end underground sensing optical cable network via a multiplex optical switch. A database of mapping relationships between one-dimensional optical cable sheath length and underground three-dimensional spatial coordinates is constructed in the distributed optical fiber sensing system.

[0040] The vibration encoding device is started after being closely attached to the sensor optical cable, and encodes the distress information input by the user into a corresponding vibration signal. The encoded vibration signal is automatically sent to the distributed optical fiber sensing system using parallel transmission of the sensor optical cable. The distributed optical fiber sensing system collects the backscattered Rayleigh scattering signal along the sensor optical cable, subtracts it from the background noise, records the location where the vibration signal occurs, and decodes the demodulated vibration signal to obtain the three-dimensional spatial coordinates of the underground location of the vibration encoding device and the distress information input by the user.

[0041] The signal processing flow of the underground rescue monitoring system based on the distributed optical fiber sensing system of this embodiment is as follows: Figure 1As shown, the optical cable is connected to the distributed fiber optic sensing system through a multiplexed optical switch. The distributed fiber optic sensing system uses a phase-sensitive optical time domain reflectometer. The system sampling rate is set to 500Hz, the pulse width is 50ns, and the spatial resolution is 5m. Calibration signals are applied at different locations to establish a mapping relationship between the one-dimensional optical cable sheath length and the underground three-dimensional spatial coordinates. Vibration signals are monitored over a long period of time. When abnormal signals are identified that may lead to mining accidents, a rapid warning can be issued, and the broadcast system and wireless communication system can be linked to issue an alarm. When a mining accident occurs, the trapped personnel send the encoded vibration signal to the optical cable through the vibration encoding device. The ground personnel monitor and decode the vibration signal through the distributed fiber optic sensing system to restore the distress message. The specific process is as follows:

[0042] Step 1, such as Figure 2 As shown in the figure, a fiber optic cable with a total length of 23,000 m is connected to a distributed fiber optic sensing system through a multiplex optical switch to obtain the backscattered Rayleigh signal along the line and monitor the background noise.

[0043] Step 2: Apply vibration signals at different locations and intersections in each mine tunnel, demodulate them using a distributed fiber optic sensing system, calibrate the positions of the vibration points, and establish a mapping relationship between the one-dimensional cable sheath length and the three-dimensional spatial coordinates of the underground space;

[0044] Step 3: Monitor vibration signals over a long period of time to quickly identify transient strong vibrations, abnormal low-frequency deformations, and high-frequency vibrations;

[0045] Step 4: When an abnormal signal is identified that may lead to a mining accident, a rapid warning is issued, and the broadcasting system and wireless communication system are linked to issue an alarm. When underground miners receive the alarm, they quickly take refuge in a nearby underground emergency shelter or other safe area;

[0046] Step 5: After the mining accident occurs, the trapped underground personnel input the distress information into the vibration encoding device. The distress information includes the number of trapped people, the number of injured people, the oxygen content, the gas concentration, the remaining food and water, such as Figure 3 The figure below is a schematic diagram of the simulated vibration encoding device interface. Enter the number in each item and press the "Next" button after completion until all the information is entered. Figure 3 For example, the button sequence is "On / Off", "1", "0", "Next", "3", "Next", "2", "1", "Next", "1", "5", "Next", "2", "4", "Next", "2", "4", which means 10 people are trapped, 3 people are injured, the oxygen content is 21%VOL, the gas concentration is 12%LEL, the food remaining is 24 hours, and the water remaining is 24 hours;

[0047] The format of the data frame is Figure 6As shown in the figure, a data frame contains 8 words, namely 1 guide word, 6 data words and 1 check word. Each word contains 10 bits, namely 1 start bit, 8 valid data bits and 1 stop bit. The start bit is fixed to "1", the stop bit is fixed to "0", and the data bits are the corresponding data, ranging from 0 to 255. Among them, the valid data bits of the guide word are fixed to "10100101" (hexadecimal A5), and the valid data bits of the check word are the sum of the valid data bits of all data words.

[0048] Taking the above distress message as an example, its hexadecimal code is "A5 0A 03 15 0C 18 18 5E";

[0049] Step 6: After the distress message is input, fix the vibration encoding device to the optical cable using a fixing belt. The fixing belt structure is as follows: Figure 4 As shown in the figure, make sure that the vibration signal can be transmitted to the optical cable, then press the "Start" button, and the vibration encoding device will automatically and continuously send vibration signals according to the input information. The operation is simple, which can save the trapped people's physical strength and improve the efficiency of rescue; Figure 5 This is a side view of another type of vibration encoding device fixing belt. The longer fixing belt makes it easier to fix the vibration encoding device to the waist of underground personnel.

[0050] In this implementation, the "A5 0A 03 15 0C 18 18 5E" signal is sent at 22375m, and the "A5 07 02 15 09 14 14 4F" signal is sent at 22475m. The signal baud rate is 5, that is, each signal will last for 16 seconds, and the start time difference between the two signals is 1 second;

[0051] In step 7, the ground rescuers collect the backscattered Rayleigh signal along the optical cable through the distributed optical fiber sensing system host, subtract it from the background noise in step 1, record the location where the vibration signal occurs, and quickly demodulate the vibration signal;

[0052] like Figure 7 The figure shows the waterfall diagram and demodulation results of the encoded vibration signal sent at 22375m and 22475m, indicating that at 22375m, 10 people were trapped, 3 were injured, the oxygen content was 21%VOL, the gas concentration was 12%LEL, there were 24 hours of food left, and 24 hours of water left; at 22475m, 7 people were trapped, 2 were injured, the oxygen content was 21%VOL, the gas concentration was 9%LEL, there were 20 hours of food left, and 20 hours of water left;

[0053] Step 8: Decode the demodulated vibration signal into a distress signal, and quickly locate it by combining the mapping relationship between the one-dimensional optical cable sheath length and the underground three-dimensional space coordinates to complete the survey of underground environmental information and immediately carry out further rescue work.

[0054] It should be pointed out that the description of the above embodiments is only used to help understand the method of this application and its core idea. For ordinary technicians in this technical field, without departing from the principles of this application, several improvements and modifications can be made to this application, and these improvements and modifications are also within the scope of protection of the claims of this application.

Claims

1. An underground rescue monitoring system based on a distributed optical fiber sensing system, characterized in that: The underground rescue monitoring system includes a distributed optical fiber sensing system, a multiplex optical switch, a sensor optical cable and a vibration encoding device; The distributed optical fiber sensing system is installed in a ground-based machine room and is connected to a single-end underground sensing optical cable network via a multiplex optical switch. A database of mapping relationships between one-dimensional optical cable sheath length and underground three-dimensional spatial coordinates is constructed in the distributed optical fiber sensing system. The vibration encoding device is activated after being placed in close contact with the optical sensing cable, and encodes the distress message input by the user into a corresponding vibration signal. The encoded vibration signal is automatically sent to the distributed optical fiber sensing system by parallel transmission of the optical sensing cable. The distributed optical fiber sensing system collects the backscattered Rayleigh signal along the optical sensing cable, subtracts it from the background noise, records the location where the vibration signal occurs, and decodes the demodulated vibration signal to obtain the three-dimensional spatial coordinates of the underground location of the vibration encoding device and the distress message input by the user. The vibration encoding device includes a dial; The dial includes a processor, a display screen and multiple input buttons, and different input buttons correspond to different emergency parameters; an encoding module is installed in the processor, which integrates the emergency parameters input by different input buttons and encodes them to obtain corresponding vibration signals; the display screen is used to display the emergency parameter column, the input information of all emergency parameter columns and the working status of the dial.

2. The underground rescue monitoring system based on the distributed optical fiber sensing system according to claim 1, characterized in that: The distributed optical fiber sensing system is equipped with an abnormal vibration signal recognition unit and an early warning unit; The abnormal vibration signal identification unit is used to identify abnormal vibration signals on the sensor optical cable. When an abnormal vibration signal is identified, the early warning unit is activated to alarm underground personnel; the abnormal vibration signal includes but is not limited to transient strong vibration, abnormal low-frequency deformation and high-frequency vibration signals.

3. The underground rescue monitoring system based on the distributed optical fiber sensing system according to claim 2, characterized in that: The early warning unit includes an underground broadcasting system and a wireless communication system.

4. The underground rescue monitoring system based on a distributed optical fiber sensing system according to claim 1, characterized in that: Each underground passage branch is provided with at least three calibration points, which are located at the underground passage branch head, the underground passage branch midpoint, and the underground passage branch tail respectively.

5. The underground rescue monitoring system based on the distributed optical fiber sensing system according to claim 1, characterized in that: The distress call information includes the number of trapped people, the number of injured people, oxygen content, gas concentration, remaining food and remaining water.

6. The underground rescue monitoring system based on a distributed optical fiber sensing system according to claim 1, characterized in that: The vibration encoding device uses serial communication encoding with a baud rate of 10 to distinguish 0 and 1 by the presence or absence of vibration.

7. The underground rescue monitoring system based on a distributed optical fiber sensing system according to claim 1, characterized in that: The encoded vibration signal includes a guide word, multiple data words and a check word; each word contains 10 bits, namely a start bit, 8 valid data bits and a stop bit, the start bit is fixed to 1, the stop bit is fixed to 0, and the data bits are corresponding data in the range of 0 to 255; among which, the valid data bits of the guide word are fixed to 10100101, and the valid data bits of the check word are the sum check of the valid data bits of all data words.

8. The underground rescue monitoring system based on a distributed optical fiber sensing system according to claim 1, characterized in that: The vibration encoding device also includes two fixing straps, which are respectively connected to both sides of the dial; one of the fixing straps is provided with a buckle, and the other fixing strap passes through the buckle to wrap around and fix the dial to the sensor cable or wear it on the user.

9. An underground rescue monitoring method based on a distributed optical fiber sensing system based on the underground rescue monitoring system according to any one of claims 1 to 8, characterized in that: The underground rescue monitoring method comprises the following steps: Tap the optical cable at different locations underground to calibrate the position and establish a mapping relationship between the one-dimensional optical cable sheath length and the three-dimensional underground spatial coordinates; Long-term monitoring of vibration signals on the sensor optical cable allows for rapid identification of abnormal vibration signals. When an abnormal vibration signal is identified, the broadcasting system and wireless communication system are linked to issue an alarm, allowing underground personnel to evacuate to nearby safe areas after receiving the alarm. After an underground accident occurs, trapped people use vibration encoding equipment to input distress signals, and the vibration signals are transmitted to the sensing optical cables by placing the vibration encoding equipment close to the sensing optical cables. The distributed optical fiber sensing system monitors the vibration signals, records the locations where the vibration signals occur, and demodulates the vibration signals. The demodulated vibration signals are decoded into distress signals, and the positioning is performed based on the mapping relationship between the one-dimensional optical cable sheath length and the three-dimensional spatial coordinates of the underground space, completing the survey of underground environmental information to carry out rescue work.

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