A distributed optical fiber positioning and navigation method

Abstract

The application provides a kind of distributed optical fiber positioning and navigation method, it is related to wired positioning and navigation technical field. Including: the distributed optical fiber vibration / sound sensor and optical fiber signal demodulator laid along the navigation line. User's real-time vibration event modulates the light phase signal in the sensor;The demodulator collects the phase anomaly data, uses the light propagation time to locate the real-time position of user on the optical fiber, and combines the geographic information system to analyze the real-time geographic coordinate and moving speed of user. With the help of the navigation software of handheld receiving terminal, the system generates navigation path according to real-time position and destination. The system can provide positioning and navigation for multiple users at the same time, and display real-time speed and time to reach the destination. The application effectively solves the problem of providing positioning and navigation services for users in the absence of positioning and navigation system or the failure of existing satellite navigation system.

Description

Technical Field

[0001] This invention relates to the field of wired navigation technology, and in particular to a distributed fiber optic positioning and navigation method. Background Technology

[0002] Existing spatial positioning technologies primarily rely on global navigation satellite systems (GNSS) or wireless radio frequency (RF) base stations. Satellite communication signals experience significant physical attenuation in deep underground structures and enclosed ship cabins. RF base stations must rely on a continuous external power grid to maintain node communication. Distributed fiber optic acoustic sensing technology utilizes the intrinsic Rayleigh scattering effect of single-mode optical fibers. This technology directly transforms conventionally laid communication optical cables into a continuous array of acoustic sensors. For example, the paper "Distributed Fiber Optic Acoustic Sensing Technology Based on Coherent Rayleigh Scattering" (Acta Physica Sinica, 2017) describes a fiber optic disturbance localization scheme. The method disclosed in the aforementioned paper injects coherent probe light pulses into the optical fiber. When the probe light pulses encounter external vibrations during propagation within the fiber, they produce a phase change in the backscattered light. The demodulation equipment can pinpoint the physical coordinates of the vibration source by calculating the spatial delay of the interference signal.

[0003] Deep mines and large ships, among other confined spaces, are high-risk operating environments. The internal passageways of these spaces typically exhibit complex three-dimensional topological networks. Researchers are currently working to completely eliminate the dependence of navigation systems on external radio frequency signals. The technological evolution is gradually shifting towards the fusion of physical environment perception using passive optical fiber networks. Simultaneously meeting the needs of location monitoring and emergency rescue guidance using existing hardware network infrastructure has become a core research direction in the field of confined space safety protection.

[0004] Existing distributed fiber optic sensor networks employ a unidirectional data acquisition architecture. Fiber optic demodulation equipment can only transmit passively sensed acoustic signals back to the control center in one direction. Trapped personnel in a confined space, after sending out distress vibrations, cannot receive any navigational feedback from the control center. Confined spaces are highly susceptible to causing widespread lighting outages during major accidents. A single fiber optic sensor network cannot provide on-site personnel with intuitive escape route guidance. Trapped personnel in communication dead zones and lacking lighting completely lose the ability to discern spatial hierarchy and the correct direction of travel. Conventional fluorescent reflective markers also fail to function properly in the absence of ambient light. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a distributed optical fiber positioning and navigation method. This invention solves the problem of disconnect between target location monitoring and visual escape guidance in extreme environments with no signal or power outages.

[0006] To achieve the above objectives, the present invention provides the following solution: A distributed fiber optic positioning and navigation method, the method comprising: Acquire the initial vibration signal sensed and transmitted by the distributed optical fiber sound / vibration sensor network; The initial vibration signal is demodulated by the fiber optic signal demodulation device, and the real-time physical coordinates of the target object that triggered the initial vibration signal in the target space are obtained. Obtain the destination coordinates corresponding to the target object, and obtain the target navigation path based on the pre-constructed optical cable network topology model, the real-time physical coordinates, and the destination coordinates; The target navigation path is matched with the optical cable network topology model to determine the target distributed optical fiber sound / vibration sensor segment corresponding to the target navigation path; The fiber optic signal demodulation device injects an excitation light source into the target distributed fiber optic sound / vibration sensor segment to excite the corresponding multi-band luminescent coating to release the target light signal. Based on the target light signals with differentiated wavelengths emitted by the target distributed fiber optic sound / vibration sensor segments located at different spatial levels, the target object is indicated to its current spatial level, and visual guidance is provided along the target navigation path.

[0007] The present invention discloses the following technical effects: This invention provides a distributed optical fiber positioning and navigation method. By utilizing distributed optical fiber sound / vibration sensors connected to a distributed optical fiber vibration / sound signal demodulator to construct a positioning system, this invention effectively overcomes the limitations of traditional positioning and navigation technologies that are unusable in enclosed spaces such as underground buildings, mines, or ships due to the failure of wireless and satellite communications. Furthermore, by incorporating different luminescent materials laid in segments on the outer surface of the sensing optical fiber, the system can still classify and indicate its current spatial location using different colored light signals emitted from optical fibers on different floors or in different areas, even in extreme situations involving complete power outages and lack of ambient lighting. This not only achieves real-time and accurate positioning of personnel and vehicles, determining their location and direction of movement, but also provides intuitive visual guidance through light effects, enabling personnel or vehicles to quickly reach their designated destination along the correct route. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1A flowchart of a distributed optical fiber positioning and navigation method provided in an embodiment of the present invention. Detailed Implementation

[0010] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0012] like Figure 1 As shown, this invention provides a distributed optical fiber positioning and navigation method applied to a positioning system. The positioning system includes a distributed optical fiber sound / vibration sensor network and an optical fiber signal demodulation device. The distributed optical fiber sound / vibration sensors in the distributed optical fiber sound / vibration sensor network are deployed along a passageway in the target space. The distributed optical fiber sound / vibration sensor network is used to sense and transmit initial vibration signals generated within the target space. The optical fiber signal demodulation device is used to demodulate the initial vibration signals to resolve real-time physical coordinates and inject excitation light sources into the distributed optical fiber sound / vibration sensors. The outer surface of the distributed optical fiber sound / vibration sensors is segmented with multi-band luminescent coatings. The multi-band luminescent coatings corresponding to the distributed optical fiber sound / vibration sensors located at different spatial levels are configured to release light signals with differentiated wavelengths when excited. The method includes: Step 100: Acquire the initial vibration signal sensed and transmitted by the distributed optical fiber sound / vibration sensor network; Step 200: Demodulate the initial vibration signal using the fiber optic signal demodulation device to obtain the real-time physical coordinates of the target object that triggered the initial vibration signal within the target space; Step 300: Obtain the destination coordinates corresponding to the target object, and obtain the target navigation path based on the pre-constructed optical cable network topology model, the real-time physical coordinates, and the destination coordinates; Step 400: Match the target navigation path with the optical cable network topology model to determine the target distributed optical fiber sound / vibration sensor segment corresponding to the target navigation path; Step 500: Inject an excitation light source into the target distributed optical fiber sound / vibration sensor segment through the optical fiber signal demodulation device to excite the corresponding multi-band luminescent coating to release the target light signal; Step 600: Based on the target light signals with differentiated wavelengths emitted by the target distributed fiber optic sound / vibration sensor segments located at different spatial levels, indicate the current spatial level to the target object and provide visual guidance along the target navigation path.

[0013] Specifically, in one embodiment of the present invention, the positioning system mainly consists of a distributed optical fiber sound / vibration sensor network and an optical fiber signal demodulation device connected by optical paths. It is primarily deployed in target spaces lacking conventional radio signal coverage, such as deep-ground buildings, complex mines, or large ships. Specifically, the distributed optical fiber sound / vibration sensor network serves as the physical sensing base of the entire positioning system. Its distributed optical fiber sound / vibration sensors are continuously deployed along the various passageways (such as main passages, stairwells, and branch corridors) within the target space, either attached to the walls or buried underground. In actual operation, when a target object moves along the passageway, it transmits mechanical vibrations to the structure. The distributed optical fiber sound / vibration sensor network is used to sense these initial vibration signals generated within the target space in real time and, based on the intrinsic Rayleigh backscattering effect of optical fibers, transmits the initial vibration signals carrying vibration characteristics to the control end through a low-loss optical path. The fiber optic signal demodulation device is located in a security control room or power supply node. As the central processing unit of the system, it is used to receive and perform distributed interferometric phase demodulation on the initial vibration signal to accurately resolve the real-time physical coordinates of the target object in the target space. On the other hand, the fiber optic signal demodulation device integrates a programmable excitation light source module, which is used to actively inject an excitation light source with specific power and timing into the distributed fiber optic sound / vibration sensor along a specific fiber optic link after the navigation path is generated.

[0014] To achieve intuitive visual guidance under extreme conditions of complete power outage and no ambient lighting, this embodiment features specific functional modifications to the external structure of the distributed fiber optic sound / vibration sensor. Specifically, the outer surface of the distributed fiber optic sound / vibration sensor is segmented along its length and coated with multi-band luminescent coatings. Within the three-dimensional topological grid of the target space, the multi-band luminescent coatings corresponding to the distributed fiber optic sound / vibration sensors located at different spatial levels (e.g., different deck levels of a ship, or the first and second basement levels of an underground building) are pre-configured to have differentiated photoluminescence spectral properties. When the fiber optic signal demodulation device injects the excitation light source into the distributed fiber optic sound / vibration sensor, the excitation light energy penetrates the fiber cladding through side leakage or evanescent wave coupling mechanisms, thereby precisely exciting the externally covering multi-band luminescent coating. Due to the differences in coating materials, the multi-band luminescent coatings located at different spatial levels will release light signals with different wavelengths when excited (e.g., the coating on the first basement level emits blue light, while the coating on the second basement level emits yellow light). By binding spatial hierarchy depth with emission wavelength in this configuration, a target in a dark, enclosed space can accurately identify its current spatial hierarchy by simply observing the differentiated wavelength light signals emitted by the distributed fiber optic sound / vibration sensors with the naked eye, and complete emergency navigation by following the guidance of the light signals.

[0015] Furthermore, in step 100 of this embodiment, the original optical wave signal sensed and transmitted by the distributed optical fiber sound / vibration sensor network is first acquired. The original optical wave signal is then converted to the frequency domain using a discrete Fourier transform. A bandpass digital filter with a cutoff frequency of 20 Hz to 500 Hz is used for frequency domain filtering to comprehensively filter out environmental noise interference signals in the preset frequency band, outputting a filtered optical wave signal. Next, this embodiment performs full-wave rectification and low-pass smoothing integration on the filtered optical wave signal to extract the time-domain energy envelope feature of the filtered optical wave signal. This feature is used to characterize the real-time energy integral profile of the disturbance signal on the time axis. In this embodiment, the temporal energy envelope feature is compared with a preset signal trigger threshold. The signal trigger threshold is fixed at 15 dB by collecting the average value of the background noise envelope in a non-intrusive state for 24 consecutive hours and adding a 20% safety margin during the initial deployment of the system. In response to the temporal energy envelope feature being greater than 15 dB, this embodiment eliminates transient random jitter and determines the filtered optical wave signal as the initial vibration signal to be used as the subsequent demodulation input.

[0016] It should be further clarified that the initial vibration signal described in this embodiment is not limited to the mechanical vibration signal generated by the direct contact between the target object and the spatial structure in terms of physical sensing dimension; it also includes sound signals propagating in air or fluid media. Based on the Rayleigh backscattering coherent sensing principle of the distributed fiber optic sound / vibration sensor network, the distributed fiber optic sound / vibration sensor is not only sensitive to the mechanical stress generated by solid-phase physical contact, but also possesses extremely high dynamic strain response characteristics to weak sound pressure gradient changes in the air medium. Therefore, when the target object generates a sound signal within a specific frequency range by calling for help or striking within the target space, the microscopic optical phase shift parameter change caused by the sound signal acting on the outer cladding of the distributed fiber optic sound / vibration sensor can also be sensed by the distributed fiber optic sound / vibration sensor network and output as the original light wave signal. That is, the initial vibration signal mentioned in the embodiments of the present invention is a generalized acoustic and mechanical disturbance input parameter. Its specific physical implementation can be the mechanical vibration signal or the sound signal. The two are equivalent in the underlying perception logic and are both controlled by the same frequency domain filtering and energy feature extraction processing steps mentioned above. They together serve as effective pre-trigger conditions for the fiber optic signal demodulation device to perform subsequent coordinate analysis and navigation visual excitation.

[0017] In step 200 of this embodiment, the coherent quadrature demodulation module, which is composed of a dual-wavelength narrow-linewidth laser and an optical 90-degree phase mixer, integrated within the fiber optic signal demodulation device, first extracts the interference phase characteristic parameter of the coherent backscattered light generated when the initial vibration signal propagates in the distributed fiber optic sound / vibration sensor network. This parameter reflects the phase instability modulation depth of the backscattered light when the fiber is subjected to external physical strain. Since the acquired interference phase exhibits a phase entanglement phenomenon with a period of 360 degrees, this embodiment employs a path-tracking phase unwinding algorithm to perform spatial domain phase dewinding processing on the interference phase characteristic parameter. This spatial domain phase dewinding processing involves calculating the phase difference between adjacent spatial sampling points and accumulating an integer multiple of 360 degrees when the absolute value of the phase difference is greater than 180 degrees, thereby eliminating phase step jumps and reconstructing a true phase change curve that extends continuously along the spatial position axis and accurately reflects the strain magnitude.

[0018] This embodiment further extracts broadband high-frequency characteristic signals from the continuous true phase change curves. The specific frequency band of these broadband high-frequency characteristic signals is locked between 100 Hz and 3000 Hz to eliminate low-frequency surface creep interference. This embodiment performs cross-correlation matching operations on the extracted broadband high-frequency characteristic signals and a noiseless environment reference feature map pre-stored in a cache. This noiseless environment reference feature map is constructed from the pure direct wave energy distribution characteristics collected through a standard drop hammer impact test during the acoustic shielding deployment phase in the target space. By calculating the cross-correlation coefficient between the two during the time-domain sliding window process, this embodiment obtains an initial time delay peak sequence composed of multiple correlation coefficient maxima. To address acoustic multipath propagation interference caused by physical constraints in enclosed spaces, this embodiment utilizes a multipath delay Doppler joint identification method. By extracting the energy exponential decay gradient and phase flip count of each peak in the initial time delay peak sequence on the time axis, it identifies acoustic multipath interference false peaks generated by the hysteresis superposition of reflected waves from the wall. False acoustic multipath interference peaks with energy decay gradients greater than a standard threshold are then removed, thereby accurately pinpointing the time delay of the true direct wave excited solely by the direct sound wave.

[0019] The expression for the energy decay gradient is: ; in, The energy decay gradient; The time lag arrival time of the acoustic multipath interference pseudo-peak on the time axis; The arrival time of the first true direct peak in the initial time-delayed peak sequence; The initial energy amplitude of the first true direct peak; The attenuation energy amplitude of the acoustic multipath interference spurious peak; The speed of sound propagation in the target space environment medium; The center frequency of the broadband high-frequency characteristic signal; The total number of phase flips that occur when the acoustic multipath interference spurious peak is acquired; For the first The absolute phase jump angle during the next phase flip.

[0020] This embodiment begins physical distance data processing after obtaining the actual direct-wave time delay. First, it retrieves the core refractive index parameter of the distributed fiber optic sound / vibration sensor directly from the factory calibration descriptor of the optical time-domain reflectometer, and simultaneously obtains the standard propagation speed parameter of light in a vacuum. The core refractive index parameter is specifically set to 1.468. This embodiment divides the standard propagation speed parameter by the core refractive index parameter to determine the optical propagation constant attribute, which characterizes the actual unidirectional transmission speed of light in a specific fiber optic medium. Subsequently, this embodiment multiplies the calculated optical propagation constant attribute with the actual direct-wave time delay value locked in the previous steps, and divides the product by 2 for round-trip path calculation, thus finally calculating the physical distance parameter of the target object relative to the physical port of the fiber optic signal demodulation device.

[0021] This embodiment ultimately maps the calculated physical distance parameters to a pre-constructed optical fiber network topology model. Specifically, the optical fiber network topology model includes a virtual topology network generated by spatial coordinate transformation mapping of the physical deployment three-dimensional trajectory of the distributed optical fiber sound / vibration sensor network. The virtual topology network includes 45 topology nodes and 88 topology connecting edges between adjacent nodes. Each topology connecting edge is configured in the database with a physical segment length parameter, a spatial level identifier parameter, and the corresponding optical attenuation coefficient parameter of the distributed optical fiber sound / vibration sensor. The physical segment length parameter is set to 50 meters, the spatial level identifier parameter corresponding to the test node is set to -3 layers, and the optical attenuation coefficient parameter is set to 0.2 dB per kilometer. This embodiment utilizes a one-dimensional topology distance search algorithm with the physical access coordinates of the optical fiber signal demodulation device as the absolute zero point, strictly accumulating the physical distance parameters along the topology connecting edges in the virtual topology network, thereby ultimately resolving the absolute three-dimensional real-time physical coordinates of the target object triggering the initial vibration signal within the target space.

[0022] To further improve the absolute accuracy of positioning, the system introduces a physical length error compensation mechanism during the process of calculating the physical distance parameter based on the actual direct wave time delay and mapping this distance for positioning. Specifically, when resolving coordinates by combining the physical distance parameter with the correspondence between the distributed fiber optic sensor and the aforementioned geographic information system, the system algorithm automatically subtracts the necessary reserved length inevitably generated during the actual construction and laying of the distributed fiber optic sensor, as well as the invalid length added due to fiber bending. By subtracting the aforementioned invalid length, the system can more accurately resolve the precise position of the navigation user along the fiber optic length, and the geographic information system can calculate more accurate real-time geographic coordinates, thereby eliminating the cumulative positioning error caused by hardware construction.

[0023] Furthermore, the target space in this embodiment not only includes confined spaces such as deep underground buildings or ships, but also extends upwards to cover a wide-area road network on the ground. To achieve unified addressing management of complex composite scenarios on the ground and underground, this embodiment implements hierarchical digital numbering management for the distributed fiber optic sound / vibration sensor network. Specifically, this embodiment introduces a Geographic Information System (GIS) into the fiber optic network topology model and, according to the hierarchical classification standards of national highways, provincial highways, urban main roads, and underground branch corridors, configures digital identification codes with spatial hierarchical attributes for the distributed fiber optic sound / vibration sensors deployed in different areas. When the target object moves in the ground or underground space, its handheld distributed fiber optic vibration signal receiving terminal can synchronously receive the absolute three-dimensional real-time physical coordinates and the global map generated based on the digital identification code from the fiber optic signal demodulation equipment via wireless base station or near-field self-organizing network communication, thereby giving the target object the interactive ability to autonomously confirm its current road segment and prioritize the best route.

[0024] In some preferred embodiments, to further improve the efficiency of human-computer interaction and the intuitiveness of spatial mapping, the pre-constructed optical cable network topology model can be specifically based on or integrated into a Geographic Information System (GIS). By establishing a correspondence between the GIS and the distributed optical fiber sensors (i.e., the distributed optical fiber sound / vibration sensor network in the aforementioned embodiments of the present invention), the system can accurately map real-time physical coordinates. The system can be configured with a handheld navigation terminal (which is a specific embodiment of the aforementioned handheld distributed optical fiber vibration signal receiving terminal) at the hardware end, and the handheld navigation terminal is equipped with dedicated navigation software. With the help of the handheld navigation terminal and navigation software carried by the navigation user (i.e., the target object described in the present invention), the system can directly generate and render a navigation path in the GIS based on real-time geographic coordinates and destination coordinates. This implementation method, in addition to realizing conventional ground navigation, is particularly suitable for positioning and navigation in complex and large enclosed spaces such as underground mining areas like coal mines, underground buildings, and large ships. It can provide services to multiple navigation users simultaneously, displaying movement speed in real time and calculating the time to reach the destination.

[0025] Furthermore, in this embodiment, when executing step 300, the destination coordinates corresponding to the target object are first obtained. Specifically, this embodiment uses three explosion-proof touch-screen interactive terminals pre-deployed at the safety passage entrance and core compartment of the target space to receive semantic spatial addressing commands input by the target object. To convert the semantic commands into precise coordinates, this embodiment calls a spatial location mapping table stored in the terminal memory. This mapping table records the binding relationship between the names of each compartment in the target space and their absolute three-dimensional coordinates, thereby accurately outputting the destination coordinates. After obtaining the coordinates, this embodiment sets the real-time physical coordinates calculated in the aforementioned steps as the starting node and the destination coordinates as the ending node in the optical cable network topology model. Subsequently, this embodiment synchronously extracts the initial topology node matrix and the initial edge connectivity weight matrix pre-statically stored in the optical cable network topology model. The initial edge connectivity weight matrix is ​​used to record the basic travel distance loss value of the physical line segments connecting each node. This basic travel distance loss value is generated by multiplying the absolute physical line segment length parameter between adjacent nodes by the environmental resistance coefficient of the corresponding spatial level. In terms of data structure, it is presented as a static numerical table of 45 by 45 dimensions.

[0026] In the preliminary sensing phase of path planning, this embodiment synchronously extracts the global background acoustic signal sensed in real time by the distributed fiber optic sound / vibration sensor network at a fixed sampling frequency of 2000 Hz. To capture sudden high-risk situations such as fires, explosions, or structural collapses, this embodiment performs a short-time Fourier transform on the global background acoustic signal to analyze abnormal energy mutation characteristics. The energy step judgment criterion set in this embodiment is: when the local acoustic energy experiences an instantaneous jump exceeding 30 dB within a 50-millisecond microscopic time window, the abnormal energy mutation characteristic is determined to have been captured. Based on this characteristic, this embodiment extracts the time difference between the arrival of the abruptly changed sound wave at at least three adjacent fiber optic sensing nodes, and combines this with the preset solidification propagation speed of the sound wave in the target space's main structural medium. Through multi-point collaborative positioning calculations involving the intersection of multiple curved surfaces in space, the coordinates of the dynamic hazard source within the target space that generated the abruptly changed sound wave are accurately calculated.

[0027] The expression for the coordinates of a dynamic hazard source is: ; in, The three-dimensional spatial vector for accurately calculating the coordinates of the dynamic hazard source; The coordinate vector of any search point within the virtual three-dimensional coordinate system of the optical cable network topology model; The total number of fiber optic sensing nodes that captured the anomalous energy mutation feature, and ; For the first The three-dimensional physical coordinate vector of the fiber optic sensing node that captured the abrupt sound wave; The three-dimensional physical coordinate vector of the first fiber optic sensing node to capture the abrupt acoustic wave; For the space Euclidean norm operator; The preset solidification propagation speed of the sound wave in the target space main structure medium; For the first The time difference between each node and the first node capturing the abrupt sound wave; The effective attenuation limit distance for the propagation of the anomalous energy mutation feature in the medium.

[0028] Next, this embodiment initiates a spatial interference assessment procedure to compare the spatial overlap between the dynamic hazard source coordinates and the candidate connected edges in the initial edge connectivity weight matrix. In the specific numerical calculation process, this embodiment uses the dynamic hazard source coordinates as the absolute center to establish a hazard radiation sphere envelope model with a radiation radius of 5 meters in a three-dimensional coordinate system, and uses a spatial analytical geometry algorithm to calculate the spatial vertical distance from the center of this sphere envelope model to the candidate connected edge. If the spatial vertical distance is less than the radiation radius, this embodiment determines that the dynamic hazard source coordinates and the candidate connected edge substantially overlap in spatial distribution. Once overlap is confirmed, this embodiment forcibly updates the passage weight parameter corresponding to the candidate connected edge that is blocked by the disaster to a blocking threshold. This embodiment sets the blocking threshold to a large number penalty constant of 99999, thereby generating an updated edge connectivity weight matrix that reflects the current real dynamic disaster distribution.

[0029] Furthermore, regarding the analysis of anomalous energy mutation characteristics in the global background acoustic signal, the aforementioned dynamically located hazard source coordinates, in practical applications, encompass a broader range of dynamic anomalous vibration events. For example, when unauthorized destructive construction, abnormal geological activity, or abnormal structural deformation occurs within the target space, resulting in severe vibrations, the system also identifies these events and generates dynamic anomalous vibration coordinates (which are logically equivalent to the dynamic hazard source coordinates described in this invention), triggering the aforementioned blocking threshold update mechanism to replan the optimal navigation path for the navigation user. This design expands the system's ability to generalize monitoring and path avoidance of unknown hazard events.

[0030] Subsequently, this embodiment performs addressing calculations based on the starting node, the ending node, the initial topology node matrix, and the updated edge connectivity weight matrix using a path optimization algorithm. The path optimization algorithm introduces a goal-oriented heuristic search factor, specifically defined as the Euclidean distance between the currently traversed node and the ending node, to guide the grid search direction towards the destination. This embodiment performs up to 100 iterations of graph network topology calculations, completely avoiding dangerous paths with a blocking threshold of 99999, and calculates three safe candidate paths connecting the starting and ending nodes. This embodiment further sums the weights of all segments of these three safe candidate paths sequentially to calculate their total travel cost values, and strictly selects the path with the minimum total travel cost value as the optimal output result, i.e., generating the target navigation path.

[0031] In step 400, this embodiment needs to transform the calculated abstract navigation path into a control target at the underlying physical hardware dimension. This embodiment first parses the target navigation path, breaking it down along its spatial trajectory to generate a sequence of path segments containing interconnected line segments. This embodiment uniformly divides the physical length of each minimum independent control line segment into 10 meters. Subsequently, this embodiment maps the endpoint coordinates of the path segment sequence to the optical fiber network topology model. By strictly matching the consistency between the endpoint coordinates of the path segment sequence and the start and end coordinates of the physical line segments in the optical fiber network topology, it extracts the identifiers of distributed optical fiber sound / vibration sensor segments that completely overlap with the spatial distribution of the path segment sequence. These identifiers are unique digital addresses written into the system during the deployment of the optical fiber communication network. In this embodiment, the identifiers of 12 distributed optical fiber sound / vibration sensor segments constituting the navigation path are extracted at once. The actual physical optical cable segments corresponding to these 12 extracted distributed optical fiber sound / vibration sensor segment identifiers are identified as the target distributed optical fiber sound / vibration sensor segments corresponding to the target navigation path, thereby providing a bias-free hardware addressing basis for subsequent accurate injection of light sources.

[0032] Furthermore, in step 500 of this embodiment, firstly, based on the three-dimensional physical spatial extension trajectory of the target distributed fiber optic sound / vibration sensor segment within the target space, the target distributed fiber optic sound / vibration sensor segment, with a total length limited to 120 meters, is proportionally divided into 60 independently connected light-emitting sub-segments along the physical laying direction. The physical length of each light-emitting sub-segment is strictly fixed at 2 meters. Subsequently, this embodiment initiates a spatial dynamic tracking program, using the coordinate data demodulated from the underlying layer to continuously track and accurately calculate the real-time movement speed parameter of the target object on the target navigation path. The specific calculation process is as follows: This embodiment uses a sampling time window fixed at 100 milliseconds as the time reference, extracts the absolute physical displacement difference of the target object within two adjacent sampling time windows, divides the absolute physical displacement difference by the time value of the sampling time window, and continuously outputs the real-time movement speed parameter accurate to two decimal places.

[0033] During the operation of the positioning system, the fiber optic signal demodulation device is equipped with a parallel computing scheduling module, supporting a multi-target concurrent processing mechanism. This enables the simultaneous provision of independent positioning and navigation services for multiple different target objects moving within the target space. For each target object, this embodiment calculates and dynamically updates the predicted arrival time parameter based on the extracted real-time movement speed parameter and the remaining physical line segment length along the target navigation path from the target object's current coordinates to the destination coordinates using a distance-by-speed smoothing filtering algorithm. The calculated predicted arrival time parameter, along with the real-time physical coordinates and real-time movement speed parameter of each target object, is packaged into a structured data stream and displayed in real-time on the central monitoring center screen of the positioning system and on the handheld distributed fiber optic vibration signal receiving terminal corresponding to each target object, achieving precise control of the overall situation.

[0034] After obtaining the real-time movement speed parameter, this embodiment proceeds to the pulse timing matching stage. This embodiment retrieves a pre-stored dynamic correlation matrix, a two-dimensional reference table generated before the system leaves the factory based on extensive ergonomic calibration experiments using the persistence of vision (typically 0.1 to 0.4 seconds). Based on this matrix, this embodiment dynamically matches the pulse excitation time interval that is strictly negatively correlated with the real-time movement speed parameter. Specifically, when the real-time movement speed parameter increases from 1 m / s to 3 m / s, the pulse excitation time interval linearly decreases from 800 milliseconds to 300 milliseconds, thereby ensuring that the guiding speed of the optical stream is always faster than the target movement speed. Simultaneously, this embodiment extracts the node topology transformation attribute in the target navigation path. This attribute is generated by calculating the angle between the spatial direction vectors of the line connecting the center points of two adjacent luminous sub-segments in the three-dimensional coordinate system. In this embodiment, the angle of this vector is compared with the warning judgment threshold of 45 degrees fixed by the system. When the angle of this vector is greater than or equal to 45 degrees, the area extending 4 meters before and after the specific physical coordinate point where the direction deflection occurs is forcibly marked as a path turning point sub-segment with the risk of blind spot.

[0035] After completing parameter matching and inflection point identification, this embodiment performs physical injection of the downlink optical signal. To overcome the total internal reflection limitation of conventional optical fibers, the distributed optical fiber sound / vibration sensor used in this embodiment has undergone femtosecond laser micro-etching cladding destruction treatment with 1 mm intervals along the axial direction at the factory, i.e., side-emitting treatment. For the conventional emitting sub-segments among the aforementioned 60 sub-segments, this embodiment strictly follows the calculated pulse excitation time interval, sequentially injecting the excitation source of conventional intensity into each of the conventional emitting sub-segments. Specifically, the excitation source uses a near-infrared communication continuous laser with a center wavelength of 980 nm, and the injection power is precisely calibrated to 50 milliwatts. Meanwhile, this embodiment monitors the coordinates of the target object in real time. When the straight-line spatial distance between the real-time physical coordinates of the target object and the starting point of the path inflection sub-segment is reduced to an approach threshold of 3 meters, a visual early warning intervention mechanism is immediately triggered. A high-frequency stroboscopic excitation light source with a higher intensity than the conventional intensity is injected into the path inflection sub-segment located at the inflection point. The peak injection power of the stroboscopic light source jumps to 150 milliwatts, and the stroboscopic period is fixed at 10 Hz.

[0036] In this embodiment, the core of step 600 is to transform the underlying luminescent physical phenomena into intuitive spatial depth visual indications. This embodiment extracts spatial layer depth information, including the current altitude of the target object and the horizontal extension direction of the target navigation path, from a virtual 3D topological network. To achieve cross-band conversion from near-infrared light to visible light, the target distributed fiber optic sound / vibration sensor segment configured in this embodiment is pre-coated with upconversion fluorescent resin material doped with different rare-earth ions, i.e., the multi-band luminescent coating. When a 980 nm near-infrared excitation source overflows the fiber cladding through the aforementioned side micro-etched area, the multi-band luminescent coating located at different spatial layers is directionally excited by absorbing two-photon energy, thereby releasing the target light signal with a stepped distribution of center wavelength. Specifically, in this embodiment, during the physical coating stage, the stimulated center wavelength of the coating (doped with thulium ions) in the first underground layer is solidified to the blue light band of 450 nm, the stimulated center wavelength of the coating (doped with erbium ions) in the second underground layer is solidified to the green light band of 530 nm, and the stimulated center wavelength of the coating in the third underground layer is solidified to the red light band of 620 nm, thereby forming an immutable spectral physical bond between the coating material and the spatial depth.

[0037] Ultimately, this embodiment achieves a deep physical coupling between temporal-dimensional injection control and spatial-dimensional coating luminescence. Through the alternating excitation process of the aforementioned conventional luminescent sub-segments receiving 50 milliwatts of continuous light and the path inflection point sub-segments receiving 150 milliwatts of 10 Hz flashes, the corresponding upconversion coating is not only fully illuminated but also releases the target light signal, exhibiting a dynamic speed-following and inflection point direction warning visual effect. A target object in a dark, enclosed space can instinctively and instantly determine the absolute depth of its current spatial level by directly observing the stepwise color transitions of the light signal's center wavelength between 450 nm, 530 nm, or 620 nm with the naked eye. Simultaneously, by observing the visual flowing effect of the light signal sequentially lighting up and flashing along the extended direction according to the strictly negatively correlated pulse excitation time interval, a dynamic visual guidance with no delay and clear direction can be obtained, enabling precise escape to a safe area even in extreme environments where external lighting and radio frequency communication are completely lost.

[0038] Considering that in extremely large and complex spaces (such as mines or ships with numerous branch corridors or multiple subspaces), the color indication capacity of a single distributed fiber optic sensor may be limited when using different colors to indicate the current location to the navigation user. In a further extended embodiment, three-dimensional visual navigation is achieved by setting different colored light signals at different spatial levels. If there are many spatial levels or sections, two or more fibers of different colors can be used in different color combinations for differentiation. Specifically, the system can inject laser light sources (which serve as customized light signals representing the excitation light source) into multiple distributed fiber optic sensors (i.e., the target distributed fiber optic sound / vibration sensor sections mentioned above) that are segmented and coated with luminescent materials through fiber optic signal demodulation equipment. The system can then define a certain color combination of light signals to correspond to a certain spatial level or region (e.g., a "red-blue" combination of light effects indicates a specific safe zone). Through this combination of colors of multiple fibers, the spatial identification capacity of the three-dimensional visual navigation system is multiplied, providing navigation users with more accurate visual guidance.

[0039] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0040] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A distributed optical fiber positioning and navigation method, applied to a positioning system, the positioning system comprising a distributed optical fiber sound / vibration sensor network and an optical fiber signal demodulation device, wherein the distributed optical fiber sound / vibration sensors in the distributed optical fiber sound / vibration sensor network are deployed along a passageway in a target space, the distributed optical fiber sound / vibration sensor network is used to sense and transmit initial vibration signals generated in the target space, the optical fiber signal demodulation device is used to demodulate the initial vibration signals to resolve real-time physical coordinates and inject excitation light sources into the distributed optical fiber sound / vibration sensors, the outer surface of the distributed optical fiber sound / vibration sensors is segmented with multi-band luminescent coatings, and the multi-band luminescent coatings corresponding to the distributed optical fiber sound / vibration sensors located at different spatial levels are configured to release light signals with differentiated wavelengths when excited, characterized in that... The method includes: Acquire the initial vibration signal sensed and transmitted by the distributed optical fiber sound / vibration sensor network; The initial vibration signal is demodulated by the fiber optic signal demodulation device, and the real-time physical coordinates of the target object that triggered the initial vibration signal in the target space are obtained. Obtain the destination coordinates corresponding to the target object, and obtain the target navigation path based on the pre-constructed optical cable network topology model, the real-time physical coordinates, and the destination coordinates; The target navigation path is matched with the optical cable network topology model to determine the target distributed optical fiber sound / vibration sensor segment corresponding to the target navigation path; The fiber optic signal demodulation device injects an excitation light source into the target distributed fiber optic sound / vibration sensor segment to excite the corresponding multi-band luminescent coating to release the target light signal. Based on the target light signals with differentiated wavelengths emitted by the target distributed fiber optic sound / vibration sensor segments located at different spatial levels, the target object is indicated to its current spatial level, and visual guidance is provided along the target navigation path.

2. The distributed optical fiber positioning and navigation method according to claim 1, characterized in that, The acquisition of the initial vibration signal sensed and transmitted by the distributed fiber optic sound / vibration sensor network includes: Acquire the raw optical wave signal sensed and transmitted by the distributed optical fiber sound / vibration sensor network; The original optical signal is subjected to frequency domain filtering to remove environmental noise interference signals in a preset frequency band, resulting in a filtered optical signal. The time-domain energy envelope feature of the filtered optical signal is extracted, and in response to the time-domain energy envelope feature being greater than a preset signal trigger threshold, the filtered optical signal is determined as the initial vibration signal.

3. The distributed optical fiber positioning and navigation method according to claim 1, characterized in that, The step of demodulating the initial vibration signal using the fiber optic signal demodulation device and resolving the real-time physical coordinates of the target object that triggered the initial vibration signal within the target space includes: The interference phase characteristic parameters of the coherent backscattered light generated when the initial vibration signal propagates in the distributed optical fiber sound / vibration sensor network are extracted by the optical fiber signal demodulation device. The interference phase characteristic parameters are subjected to spatial domain phase dewinding processing to reconstruct a continuous true phase change curve; Extract broadband high-frequency characteristic signals from the continuous true phase change curves; The broadband high-frequency characteristic signal is cross-correlation matched with a preset noiseless environment reference characteristic map to obtain the initial time delay peak sequence. Identify false acoustic multipath interference peaks in the initial time delay peak sequence caused by the physical constraints of the target space, and remove the false acoustic multipath interference peaks to lock the true direct wave time delay. Based on the optical propagation constant properties of the distributed fiber optic sound / vibration sensor and the actual direct wave time delay, the physical distance parameter of the target object relative to the fiber optic signal demodulation device is calculated. The physical distance parameter is mapped to a pre-constructed optical fiber network topology model, and the real-time physical coordinates of the target object that triggered the initial vibration signal within the target space are parsed.

4. The distributed optical fiber positioning and navigation method according to claim 3, characterized in that, The optical fiber network topology model includes: A virtual topology network generated by the three-dimensional trajectory mapping of the physical deployment of the distributed fiber optic sound / vibration sensor network; The virtual topology network includes: multiple topology nodes and topology connectivity edges connecting two adjacent topology nodes; Each of the topological connected edges is configured with a physical line segment length parameter, a spatial hierarchy identifier parameter, and a corresponding optical attenuation coefficient parameter of the distributed optical fiber sound / vibration sensor.

5. A distributed optical fiber positioning and navigation method according to claim 3, characterized in that, The step of calculating the physical distance parameter of the target object relative to the fiber optic signal demodulation device based on the optical propagation constant property of the distributed fiber optic sound / vibration sensor and the actual direct wave time delay includes: The core refractive index parameter and the standard propagation speed of light in a vacuum parameter of the distributed optical fiber sound / vibration sensor are obtained. The optical propagation constant attribute is determined based on the fiber core refractive index parameter and the standard propagation speed parameter. The optical propagation constant property is multiplied by the actual direct wave time delay, and round-trip path calculation is performed to obtain the physical distance parameter of the target object relative to the fiber optic signal demodulation device.

6. The distributed optical fiber positioning and navigation method according to claim 1, characterized in that, The step of obtaining the destination coordinates corresponding to the target object and, based on the pre-constructed optical fiber network topology model, the real-time physical coordinates, and the destination coordinates, obtaining the target navigation path includes: Obtain the destination coordinates corresponding to the target object, and set the real-time physical coordinates as the starting node and the destination coordinates as the ending node in the optical cable network topology model; Extract the pre-stored initial topology node matrix and initial edge connectivity weight matrix from the optical cable network topology model; Simultaneously extract global background acoustic signals sensed in real time by the distributed fiber optic sound / vibration sensor network; The abnormal energy mutation characteristics in the global background acoustic signal are analyzed, and the coordinates of the dynamic hazard source in the target space are located based on the abnormal energy mutation characteristics. Compare the spatial distribution of the coordinates of the dynamic hazard source with the candidate connected edges in the initial edge connectivity weight matrix; In response to the spatial distribution of the dynamic hazard source coordinates and the candidate connected edges, the passage weight parameters corresponding to the candidate connected edges are updated to the blocking threshold, and an updated edge connectivity weight matrix is ​​generated. Based on the starting node, the ending node, the initial topology node matrix, and the updated edge connectivity weight matrix, a path optimization algorithm is used to solve the problem, and the path with the minimum travel cost is selected as the target navigation path.

7. The distributed optical fiber positioning and navigation method according to claim 1, characterized in that, The step of matching the target navigation path with the optical cable network topology model to determine the target distributed optical fiber sound / vibration sensor segment corresponding to the target navigation path includes: Parse the sequence of path segments contained in the target navigation path; The path segment sequence is mapped to the optical cable network topology model, and the distributed optical fiber sound / vibration sensor segment identifiers that overlap with the spatial distribution of the path segment sequence are extracted. The physical optical cable segment corresponding to the extracted distributed optical fiber sound / vibration sensor segment identifier is determined as the target distributed optical fiber sound / vibration sensor segment corresponding to the target navigation path.

8. A distributed optical fiber positioning and navigation method according to claim 1, characterized in that, The step of injecting an excitation light source into the target distributed fiber optic sound / vibration sensor segment through the fiber optic signal demodulation device to excite the corresponding multi-band luminescent coating to release the target light signal includes: Based on the spatial extension trajectory of the target distributed optical fiber sound / vibration sensor segment, the target distributed optical fiber sound / vibration sensor segment is divided into multiple light-emitting sub-segments that are connected end to end. Continuously track and calculate the real-time movement speed parameter of the target object on the target navigation path; Based on the real-time movement speed parameter, a pulse excitation time interval that is positively correlated with the real-time movement speed parameter is dynamically matched; Extract the node topology transformation attributes in the target navigation path, and identify the path inflection point sub-segments based on the node topology transformation attributes; For the conventional light-emitting sub-segments that are not path inflection points in the plurality of sequentially connected light-emitting sub-segments, the excitation light source of conventional intensity is injected sequentially according to the pulse excitation time interval; In response to the target object approaching the path inflection point sub-segment, a high-frequency stroboscopic excitation light source with an intensity greater than the conventional intensity is injected into the path inflection point sub-segment; By alternating stimulation of the conventional luminescent sub-segments and the path inflection point sub-segments, the corresponding multi-band luminescent coating releases the target light signal, which exhibits a dynamic speed tracking and inflection point direction warning visual effect.

9. A distributed optical fiber positioning and navigation method according to claim 1, characterized in that, The method of using target light signals with differentiated wavelengths emitted by the target distributed fiber optic sound / vibration sensor segments located at different spatial levels to indicate the current spatial level of the target object and provide visual guidance along the target navigation path includes: Obtain the depth information of the current spatial layer of the target object, as well as the extension direction of the target navigation path; In response to the excitation of the multi-band luminescent coating corresponding to the target distributed optical fiber sound / vibration sensor segments located at different spatial levels, the target light signal with a stepped distribution of center wavelength is released. The depth information of the current spatial level is identified by the stepped distribution of the center wavelength of the target light signal, and the visual guidance is provided by the sequential flashing of the target light signal along the extension direction.

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