Passive locating system and method for trapped personnel based on digital marking of airships

Abstract

The application discloses a trapped personnel passive positioning system and method based on a digital marker of a flying boat, and the system comprises an aerial reference end, a search verification end and a ground command end. The aerial reference end comprises a flying boat, a direction sensor and a flying boat terminal are arranged in the flying boat, the direction sensor is connected with the flying boat terminal, and the outer wall of the flying boat is provided with annular areas of different colors. The ground command end comprises a ground resolving terminal and a communication receiving terminal, the flying boat terminal is signal-connected with the ground resolving terminal, the search verification end comprises a unmanned aerial vehicle, the unmanned aerial vehicle is provided with a multispectral imaging device, a unmanned aerial vehicle control terminal and a remote data transmission device, the multispectral imaging device is connected with the unmanned aerial vehicle control terminal, and the unmanned aerial vehicle control terminal is signal-connected with the ground resolving terminal through the remote data transmission device. The application can realize the rapid and accurate positioning of trapped personnel in a 'three-break' (circuit break, power failure and network break) disaster environment through the digital marker of the flying boat and a computer vision fusion positioning technology.

Description

Technical Field

[0001] This invention belongs to the field of intelligent emergency rescue technology, specifically involving a passive positioning system and method for trapped personnel based on tethered airship digital tagging, UAV swarm collaboration, and YOLOv8 deep learning model. It is particularly suitable for extreme environments of "three disconnections" (road disconnection, power disconnection, and network disconnection) caused by disasters such as earthquakes and floods. Background Technology

[0002] With the development of human society and the intensification of climate change, natural disasters (such as earthquakes, floods, and landslides) are becoming more frequent and destructive, placing higher demands on emergency rescue technologies. Especially in extreme disaster environments involving "three disruptions" (road outages, power outages, and internet outages), existing passive positioning technologies have serious limitations:

[0003] 1. Satellite remote sensing technology relies on periodic overflights, resulting in long revisit cycles and susceptibility to cloud cover. Its positioning accuracy is only 5-10 meters, which cannot meet the timeliness requirements of the "golden 72 hours" for rescue operations. For example, in the 2023 earthquake in Turkey, satellite imagery was obscured by clouds, preventing timely assessment of 30% of the disaster area.

[0004] 2. Full-area scanning by drones relies on preset routes or pilot operation. The single-drone endurance is insufficient, requiring 45-90 minutes to search 1 square kilometer. Furthermore, the recognition rate of distress calls from trapped individuals is low.

[0005] 3. Existing passive positioning technologies such as GNSS, UWB, and cellular positioning technologies all require the trapped person to carry terminal equipment or pre-deployed base station networks.

[0006] 4. Shortcomings in multi-platform collaboration: Existing airship and UAV systems are data-isolated. For example, airships only serve as communication relays and do not take full advantage of their long endurance and strong visibility. Meanwhile, UAV swarms lack efficient energy supply and are difficult to operate continuously.

[0007] Search results:

[0008] Chinese invention patent CN109451580B discloses a method for locating trapped individuals in a three-dimensional scene after an earthquake. This method addresses situations where, after an earthquake, some people are trapped in buildings or other structures, and their mobile phones cannot receive GPS signals for positioning. It utilizes mobile communication base stations to provide communication signals to the trapped individuals' mobile phones, and uses a built-in application on the phone and signal strength values ​​to perform spatial positioning. The method uses the collected signal strength from the trapped individuals' mobile phones and converts the signal strength into the distance between the mobile communication base station and the trapped individuals' mobile phones using a log-normal shading model. The position of the mobile communication base station is regularly changed to obtain multiple sets of data, and the three-dimensional position of the trapped individuals in the test site is calculated using spatial geometric formulas. The outstanding advantages of this positioning method are: it can handle sudden situations such as earthquakes; it does not require the individuals being located to carry other equipment beforehand; it requires minimal equipment; the positioning process is computationally simple; and it can meet the needs for rapid and accurate positioning after an earthquake.

[0009] Chinese utility model patent CN207488769U discloses an aerial vehicle for collecting information on trapped personnel. The vehicle includes an outer shell housing a hollow cup motor module, a motor drive module, and an ultrasonic ranging module. Inside the outer shell are an STM32 microcontroller module, a sound acquisition module, a speech synthesis module, a speech recognition module, a satellite positioning module, a communication module, a nine-axis motion sensor module, a power supply module, and a clock module. This utility model combines wireless sensor network technology and sound processing technology to automatically collect information and assess the health of trapped personnel during the critical rescue window when rescuers cannot reach the site. This provides relevant data for future rescue personnel entering the disaster area, thus compensating for the shortcomings of existing auxiliary rescue systems, maximizing rescue efficiency, reducing the mortality rate of trapped personnel, and preventing further family tragedies.

[0010] Chinese invention patent CN108169816A discloses a disaster relief personnel and trapped personnel positioning system, including a rescue positioning controller, a disaster relief platform main controller connected to at least one rescue personnel positioning device, a rescue positioning controller connected to at least one life detection device, and a rescue positioning controller connected to at least one display device. The rescue positioning controller receives personnel positioning signals from the rescue personnel positioning device and the life detection device, processes the signals, converts different types of signals into location information for rescue personnel and trapped personnel, and transmits this location information to the display device. When a disaster occurs, the system switches to emergency mode, simultaneously activating the personnel positioning and life detection systems. It can display the current location of rescue personnel on site, as well as the location of trapped personnel who cannot escape, increasing the chances of successful rescue.

[0011] The technical comparison between this application and the aforementioned patent is as follows:

[0012] The invention patent with publication number CN109451580B proposes a method for locating trapped personnel in a three-dimensional scene after an earthquake. This method utilizes a mobile communication base station moving along a right-angle path at the edge of the disaster area. By collecting the signal strength of the trapped personnel's mobile phones and converting it into distance data, and combining a log-normal shading model and spatial geometric algorithms, it achieves precise three-dimensional positioning of the trapped personnel. This method does not rely on GPS signals, requires only a small amount of equipment to quickly complete the positioning, and is suitable for sudden disaster scenarios such as earthquakes. It features simple calculation, rapid response, and significantly improves rescue efficiency.

[0013] Utility model patent CN207488769U discloses an aerial vehicle for collecting information on trapped personnel. This vehicle integrates a hollow cup motor module, an ultrasonic ranging module, an STM32 microcontroller control system, and multimodal sensors. It achieves rapid location and information acquisition of trapped personnel after disasters through sound acquisition and voice interaction technology. Its innovation lies in the integration of nine-axis motion sensor precision navigation, ZigBee wireless networking communication, and satellite positioning technology. It can autonomously perform three-dimensional spatial searches in complex environments inaccessible to rescue personnel, transmitting real-time data on the location, physiological status, and environment of trapped individuals. Compared to traditional life detection equipment, this design achieves a breakthrough in non-contact human-machine dialogue functionality. Through the collaborative work of the LD3320 voice recognition chip and the XFS5152 voice synthesis chip, it significantly improves the proactive response rate of trapped personnel in confined spaces, providing an intelligent solution for the critical 72-hour rescue operation.

[0014] The invention patent CN108169816A discloses a collaborative positioning system for disaster relief personnel and trapped individuals. This system integrates multi-source positioning data through a rescue positioning controller, enabling two-way visualization of personnel at the rescue site. Its innovation lies in combining RFID / 2.4G wireless barrier communication for rescue personnel positioning with infrared / radar wave life detection technology. Through an RS-485 / TCP-IP / ZigBee multi-mode communication architecture, a real-time dynamic positioning network is constructed. The system is equipped with a three-level fault-tolerant mechanism: a power management module ensures continuous power supply, a fault detection module enables device self-diagnosis, and the main control module employs redundant data processing algorithms to ensure stable output of rescue personnel movement trajectories and trapped individuals' vital sign coordinates even in complex environments such as building collapses. Compared to traditional single-positioning solutions, this system achieves a breakthrough in realizing the spatiotemporal correlation mapping between rescue forces and targets to be rescued. Through the battlefield situation visualization function of the display device, rescue efficiency is improved by more than 40%, making it particularly suitable for disaster scenarios where every second counts, such as earthquakes and fires.

[0015] This invention addresses the limitations of traditional disaster-related personnel location technologies, which rely on GNSS terminals and UWB tags, and struggle to function effectively under extreme conditions of "three disruptions" (circuit, power, and network outages). It proposes a rapid and accurate location solution that eliminates the need for trapped individuals to carry any electronic devices. This solution innovatively utilizes a tethered helium airship as a visual positioning reference, combined with a multi-level response mechanism involving UAVs and ground stations, enabling precise location of trapped individuals in any complex environment. In the event of low-voltage faults or severe weather conditions, the system can dynamically adjust the airship's altitude and brightness mode to maintain stable operation of the marking system, significantly improving the reliability and efficiency of location tracking during disaster relief.

[0016] The invention patent with publication number CN109451580B focuses on three-dimensional scene positioning by measuring distance through signal strength. The utility model patent with publication number CN108169816A focuses on non-contact human-computer dialogue function of sound acquisition and voice interaction technology. The invention patent with publication number CN108169816A focuses on realizing two-way personnel visualization by building a real-time dynamic positioning network through a multi-mode communication architecture. This invention uses a tethered airship equipped with a large LED digital marker as an aerial reference, combined with a drone swarm and YOLOv8 model to achieve passive positioning. It is suitable for extreme environments with "three disconnections". The trapped person only needs to visually report the airship code without electronic devices, filling the gap of existing technology that relies on electronic devices or infrastructure. At the same time, it achieves fast and accurate passive positioning through a collaborative architecture and efficient algorithms, which is an important innovation in the field of emergency rescue. Summary of the Invention

[0017] To address the aforementioned technical problems, this invention proposes a passive positioning system and method for trapped personnel based on airship digital tags. This application enables rapid and accurate positioning of trapped personnel in "three-disruption" (circuit, power, and internet outage) disaster environments by using airship digital tags and computer vision fusion positioning technology.

[0018] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0019] A passive positioning system for trapped personnel based on airship digital tagging is characterized by comprising an airborne reference terminal, a search and verification terminal, and a ground command terminal. The airborne reference terminal includes an airship equipped with a direction sensor and an airship terminal. The direction sensor connects to the airship terminal and transmits the airship's real-time attitude data to it. The airship's outer wall is decorated with annular zones of different colors, each zone having three layers: an outer layer representing a zone, a middle layer representing altitude, and an inner layer containing a QR code verification bit. The ground command terminal includes a ground-based calculation terminal and a communication receiving terminal for receiving communications from the trapped personnel. The airship terminal is signal-connected to the ground-based calculation terminal and uploads the airship's attitude data to it in real time. The search and verification terminal includes a drone equipped with a multispectral imaging system. The system includes an imaging device, a drone control terminal, and a remote data transmission device. The multispectral imaging device is connected to the drone control terminal, which is connected to a ground-based calculation terminal via the remote data transmission device. The drone control terminal has built-in water search and rescue models and land search and rescue models. When a trapped person reports information about a sighted airship to the communication receiving terminal, the ground-based calculation terminal calculates the initial location area of ​​the trapped person based on the reported information and the spacecraft's attitude data, plans the drone's flight path, and uploads the drone's flight path to the drone control terminal. When the initial location area is within a water area, the drone control terminal activates the water search and rescue model and proceeds there; when the initial location area is within a land area, the drone control terminal activates the land search and rescue model and proceeds there.

[0020] As a preferred technical solution of the present invention: the air reference end further includes a winch device, the winch device includes a tether cable and a fixed seat, the fixed seat is fixed on the ground, the tether cable is stored on the fixed seat, and the airship is pulled up to a predetermined height by the tether cable.

[0021] As a preferred technical solution of the present invention: the annular area is provided with eight rings, and each annular area is provided with three layers of digital rings. The outer layer is the letters AH, the middle layer is the numbers 1-8, and the inner layer is the QR code verification position. The digital ring is a large LED digital code of 2m×2m.

[0022] As a preferred technical solution of the present invention: the ground calculation terminal is equipped with a position calculation engine. When the trapped personnel report the airship data they see, the airship terminal uploads the real-time yaw angle θ of the airship to the position calculation engine. The position calculation engine calculates the azimuth ring area through a geometric projection algorithm: α=θ+(S_id×45°)±22.5°.

[0023] As a preferred technical solution of the present invention: the water search and rescue model has a built-in database of features of people who have fallen into the water. When the UAV flies to the target water area, it uses a multispectral imaging device to identify and search based on the data in the database of features of people who have fallen into the water. The land search and rescue model has a built-in database of human activity features. When the UAV flies to the target land area, it uses a multispectral imaging device to identify and search based on the data in the database of human activity features.

[0024] As a preferred technical solution of the present invention: when the UAV searches along its flight path, it adopts a water mode, i.e., spiral expansion search, when searching for a water area, and adopts a land mode, i.e., flying along a street topology path, when searching for a landing area. When there is land in the water area or water in the land area, it adopts a hybrid mode, i.e., prioritizing scanning areas with abnormal water surface reflection.

[0025] As a preferred technical solution of the present invention: the multispectral imaging device includes a visible infrared detector, an infrared thermal imager, and a lidar rangefinder for identifying human characteristics and distress signals.

[0026] As a preferred technical solution of the present invention: the remote data transmission device carried by the UAV is a local area network, a hotspot network, or a LoRa gateway.

[0027] In the above structure: the passive positioning system for trapped personnel based on airship digital tagging proposed in this invention includes an airborne reference terminal, a search and verification terminal, and a ground command terminal. The airborne reference terminal is used for patrolling and serving as a positioning reference for trapped personnel. The search and verification terminal is used for precise searching and location confirmation of trapped personnel. The ground command terminal is used for information processing and rescue plan formulation.

[0028] The airborne reference unit includes an airship, which houses a direction sensor and an airship terminal. The direction sensor connects to the airship terminal and transmits the airship's real-time attitude data to the terminal. The outer wall of the airship is decorated with annular zones of different colors. Each annular zone has three layers: an outer layer representing the zone, a middle layer representing altitude, and an inner layer containing a QR code verification bit.

[0029] The airship is a tethered helium-filled airship that ascends to a predetermined altitude of 300 meters via a winch fixed to the ground. The tether cable also serves as a power transmission and communication relay. After takeoff, the airship activates a self-stabilizing system to maintain stability in the air. A MEMS inertial measurement unit measures the direction sensor to monitor the airship's attitude in real time, maintaining hovering stability in wind speeds ≤8. Ducted thrusters automatically adjust thrust according to wind conditions to counteract sudden gusts.

[0030] The airship unfolds into 8 circular sections, each displaying a 2m x 2m LED code (e.g., "A1"-"D2"), with brightness automatically adjusted according to ambient light.

[0031] Daytime mode: 1000 cd / m² (visible in strong light)

[0032] Night mode: 500 cd / m² (with orange-red backlight on)

[0033] After the airship takes off, calibration is completed using a direction sensor, as detailed below:

[0034] Fiber optic gyroscope initialization

[0035] Synchronize with BeiDou differential positioning data from ground stations to eliminate accumulated errors.

[0036] When using:

[0037] When the trapped personnel spotted the airship in the air, a communication channel was established via the airship:

[0038] The airship displays emergency contact numbers via LED codes (e.g., flashing "Dial 189-XXXX-099").

[0039] Simultaneous broadcast voice prompt (5G broadcast channel, content: "Please dial the number displayed on the screen")

[0040] The ground command terminal includes a ground calculation terminal and a communication receiving terminal for receiving calls from trapped personnel. The airship terminal is connected to the ground calculation terminal and uploads the airship's position and attitude data to the ground calculation terminal in real time.

[0041] The basic interaction for those trapped is as follows:

[0042] After the stranded person dials the rescue number on the airship, the ground command center communicates with them through a communication receiving terminal. Example of the conversation:

[0043] Rescuer: "Please describe the code of the airship you saw, such as the brightest combination of letters and numbers."

[0044] Trapped person: "I see B and 3 glowing directly in front of me, B is brighter than 3" → Identified as zone B3.

[0045] Direction determination logic:

[0046] If the trapped person says "B is on the left" → the airship is on the starboard side (this needs to be calculated in conjunction with the airship's real-time yaw angle θ).

[0047] If it is stated that "the number is above the luminous object" → the elevation angle φ is approximately 20°-30° (empirical value).

[0048] Rescuers used a ground-based calculation terminal to combine the descriptions from the trapped individuals with the real-time position and attitude data transmitted by the airship. Through a geometric projection model, they converted the airship codes and observation angles reported by the trapped individuals into specific coordinates and generated an EPSO optimized path. This path was then transmitted to the drone control terminal, which controlled the drone to travel to the specific coordinates for a precise search.

[0049] The search verification terminal includes a drone, which is equipped with a multispectral imaging device, a drone control terminal, and a remote data transmission device. The multispectral imaging device is connected to the drone control terminal, and the drone control terminal is connected to the ground calculation terminal via the remote data transmission device.

[0050] The drone travels along its flight path to conduct reconnaissance and transmits information in real time to the ground-based processing terminal via a remote data transmission device.

[0051] The ground command terminal generates the drone search path:

[0052] The drone is equipped with a land search and rescue model, adopts a spiral expansion search mode, and avoids known obstacles (collapsed buildings are marked as no-fly zones).

[0053] The drone took off with its payload:

[0054] Flight speed 8m / s, search altitude 30 meters (balancing field of view and resolution)

[0055] A 1080p video stream is transmitted in real time to the ground command center via a remote data transmission device.

[0056] Once the drone reaches the designated area, it begins precise searching and location determination using a multispectral imaging device.

[0057] Visible infrared detector:

[0058] Based on the improved YOLOv8 model

[0059] Identify human body features (head, limb outlines) and distress signals (waving, flashing lights).

[0060] Infrared thermal imager:

[0061] Thermal imaging detects body temperature, eliminating false alarms from rubble and debris.

[0062] Dynamic threshold segmentation technology eliminates sunlight reflection interference

[0063] LiDAR rangefinder:

[0064] After detecting the trapped person, their spatial location was confirmed using a lidar rangefinder.

[0065] Geographic coordinate system conversion (WGS84 to UTM grid)

[0066] And push the geographic coordinates to the ground-based calculation terminal:

[0067] 3D coordinates: X=125.7m, Y=88.3m, Z=1.2m (relative to ground station)

[0068] Confidence level: 98.4% (visible light + infrared dual verification).

[0069] This invention can also be used for nighttime flood disaster location and search, as detailed below:

[0070] Special environmental adaptation measures:

[0071] Airship Adjustment

[0072] LED backlight switched to night mode (strong ability to penetrate rain and fog)

[0073] The airship descends to an altitude of 200 meters (to improve the visibility of the markers and compensate for nighttime visibility).

[0074] Drone sensor configuration:

[0075] Infrared thermal imager set to high sensitivity mode

[0076] Load the water search and rescue model:

[0077] A database of characteristics of people who have fallen into the water (including head exposure and detection of floating objects).

[0078] Location process optimization:

[0079] After the trapped person dialed the rescue hotline, the rescue team received the signal through the LoRa gateway (a frequency band with strong water penetration capability).

[0080] Multi-source data fusion positioning:

[0081] Collaboration between airship orientation calculation and UAV thermal imaging detection:

[0082] Heat source clustering analysis (excluding areas with abnormal water temperature)

[0083] Motion trajectory tracking (continuous frame displacement vector verification)

[0084] The final positioning error is less than 1.5 meters (slightly higher than that of land scenes due to water surface fluctuations).

[0085] UAV adaptive scanning strategy

[0086] Water area mode: Spiral expansion search

[0087] City mode: Fly along street topology paths

[0088] Hybrid mode: Prioritize scanning areas with abnormal water surface reflection.

[0089] Multispectral verification

[0090] Thermal imaging detection

[0091] LiDAR water surface ripple compensation

[0092] Identification of drowning victims using visible light + YOLOv8.

[0093] The passive positioning method for trapped personnel based on airship digital markers is characterized by the following steps:

[0094] S1. The stranded person observes the airship's code and elevation angle φ, and reports to the ground command via communication equipment by dialing a rescue call; S2. The ground command, based on the reported information and the airship's real-time yaw angle θ, calculates the azimuth sector α=θ+(S_id×45°)±22.5°, determines the area where the stranded person is located, generates an EPSO optimized path based on the area, and transmits the optimized path to the UAV control terminal; S3. The UAV control terminal controls the UAV to approach the area where the stranded person is located according to the EPSO optimized path and conducts a detailed search using a multispectral imaging device to determine the stranded person's status and precise location, and transmits video and the stranded person's location back to the ground command in real time via a remote data transmission device; S4. After receiving the video and location transmitted by the UAV, the ground command generates a rescue plan based on the situation.

[0095] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0096] I. Passive positioning without equipment dependence: The trapped personnel can report their location autonomously through large visual digital markers (2m×2m LED coding) on ​​the airship, completely eliminating the dependence on equipment such as GNSS terminals and UWB tags, and can still work stably in the extreme environment of "three interruptions".

[0097] II. Rapid Response Capability: Adopting a two-level mode of "airship coarse positioning + UAV fine search", the positioning process that traditional technology requires 45-90 minutes per square kilometer is shortened to within 10 minutes.

[0098] III. High-precision positioning: By integrating geometric projection algorithm (error < 25°) and multispectral computer vision verification (visible light + infrared + lidar), the final positioning accuracy reaches 0.5 meters.

[0099] IV. Excellent environmental adaptability: The airship marking system supports an operating temperature range of -30℃ to 60℃, and the LED backlight ensures a visibility distance of 500 meters in nighttime / rainy / foggy environments; the drone is equipped with IP67 protection and can operate normally in winds of up to level 7 and in moderate rain.

[0100] V. Long-term continuous operation capability: The airship achieves energy self-sufficiency through flexible photovoltaic (conversion efficiency 28%) and ducted wind turbine (300W), and with the help of wireless charging for drones (efficiency > 85%), it supports the system to operate continuously for 30 days.

[0101] VI. Intelligent Collaborative Architecture: Establish an integrated air-space-ground network of "airship-UAV-ground station", realize multi-device data synchronization through TDMA communication protocol, and achieve a positioning success rate of 98% in actual tests.

[0102] VII. Versatility across multiple disaster scenarios: It has been verified in scenarios such as earthquake ruins, floods, and mountainous areas, and is particularly suitable for complex environments such as building collapses and water inundation. Its technical adaptability is more than 3 times higher than that of single sensor solutions. Attached Figure Description

[0103] Figure 1 This is a flowchart of a passive positioning method for trapped personnel based on airship digital tagging;

[0104] Figure 2 It is a flowchart of the airship's hull color and numerical marking system;

[0105] Figure 3 It is the location process in an earthquake rubble environment;

[0106] Figure 4 It is an identification marker map in the earthquake ruins environment;

[0107] Figure 5 This is a flowchart of the nighttime flood disaster location application. Detailed Implementation

[0108] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0109] like Figure 1-2As shown, the passive positioning system for trapped personnel based on airship digital marking proposed in this invention is characterized by: an airborne reference terminal, a search and verification terminal, and a ground command terminal. The airborne reference terminal includes an airship, which is equipped with a direction sensor and an airship terminal. The direction sensor is connected to the airship terminal and transmits the airship's real-time attitude data to the airship terminal. The outer wall of the airship is provided with annular areas of different colors. Each annular area has three layers: an outer layer representing the zone, a middle layer representing the altitude, and an inner layer containing a QR code verification bit. The ground command terminal includes a ground calculation terminal and a communication receiving terminal for receiving communications from the trapped personnel. The airship terminal is signal-connected to the ground calculation terminal and uploads the airship's attitude data to the ground calculation terminal in real time. The search and verification terminal includes a drone, on which is equipped with... The system includes a multispectral imaging device, a drone control terminal, and a remote data transmission device. The multispectral imaging device is connected to the drone control terminal, which is connected to a ground-based calculation terminal via the remote data transmission device. The drone control terminal has built-in water search and rescue models and land search and rescue models. When a stranded person reports information about an airship they have seen to the communication receiving terminal, the ground-based calculation terminal calculates the initial location area of ​​the stranded person based on the reported information and the spacecraft's attitude data, plans the drone's flight path, and uploads the drone's flight path to the drone control terminal. When the initial location area is within a water area, the drone control terminal activates the water search and rescue model and proceeds there; when the initial location area is within a land area, the drone control terminal activates the land search and rescue model and proceeds there. The airborne reference terminal also includes a winch device, which includes a tether cable and a fixed base. The fixed base is fixed to the ground, and the tether cable is stored in the fixed base. The airship is pulled up to a predetermined altitude by the tether cable. The system comprises eight annular zones, each containing three layers of digital rings: an outer layer of letters AH, a middle layer of numbers 1-8, and an inner layer of a QR code verification digit. Each digital ring is a large 2m x 2m LED digital code. The ground-based calculation terminal is equipped with a position calculation engine. When a stranded person reports the airship data they see, the airship terminal uploads the airship's real-time yaw angle θ to the position calculation engine. The position calculation engine calculates the azimuth annular zone using a geometric projection algorithm: α = θ + (S_id × 45°) ± 22.5°. The water rescue model has a built-in database of drowning personnel characteristics. When the UAV reaches the target water area, it uses a multispectral imaging device to identify and search based on data from this database. The land search and rescue model has a built-in database of human activity characteristics. When the UAV reaches the target land area, it uses a multispectral imaging device to identify and search based on data from this database.When the UAV searches along its flight path, it uses a water mode (spiral expansion search) when searching water areas, a land mode (flying along street topology paths) when searching landing areas, and a hybrid mode (prioritizing scanning areas with abnormal water surface reflections) when searching water areas containing land or land areas containing water. The multispectral imaging device includes a visible infrared detector, an infrared thermal imager, and a lidar rangefinder for identifying human features and distress signals. The UAV's remote data transmission device is a local area network, a hotspot network, or a LoRa gateway.

[0110] The passive positioning method for trapped personnel based on airship digital markers proposed in this invention includes the following steps:

[0111] S1. The trapped person observes the airship's code and elevation angle φ, and reports to the ground command center by making a rescue call through communication equipment;

[0112] S2. The ground command terminal calculates the azimuth sector α=θ+(S_id×45°)±22.5° by combining the reported information with the real-time yaw angle θ of the airship, determines the area where the trapped personnel are located, generates an EPSO optimized path based on the area, and transmits the optimization to the UAV control terminal.

[0113] S3. The UAV control terminal controls the UAV to approach the area where the trapped personnel are located according to the EPSO optimized path and conducts a fine search through the multispectral imaging device to determine the trapped personnel's trapped status and precise trapped location. The terminal then transmits the video and the trapped personnel's trapped location back to the ground command terminal in real time through the remote data transmission device.

[0114] S4. After receiving the video and location of the stranded area transmitted by the drone, the ground command terminal generates a rescue plan based on the situation.

[0115] Example 1:

[0116] like Figure 3-4 As shown, the passive positioning system for trapped personnel based on airship digital markers proposed in this invention includes an airborne reference terminal, a search and verification terminal, and a ground command terminal. The airborne reference terminal is used for patrolling and serving as a positioning reference for trapped personnel. The search and verification terminal is used for precise searching and location confirmation of trapped personnel. The ground command terminal is used for information processing and rescue plan formulation.

[0117] The airborne reference unit includes an airship, which houses a direction sensor and an airship terminal. The direction sensor connects to the airship terminal and transmits the airship's real-time attitude data to the terminal. The outer wall of the airship is decorated with annular zones of different colors. Each annular zone has three layers: an outer layer representing the zone, a middle layer representing altitude, and an inner layer containing a QR code verification bit.

[0118] The airship is a tethered helium-filled airship that ascends to a predetermined altitude of 300 meters via a winch fixed to the ground. The tether cable also serves as a power transmission and communication relay. After takeoff, the airship activates a self-stabilizing system to maintain stability in the air. A MEMS inertial measurement unit measures the direction sensor to monitor the airship's attitude in real time, maintaining hovering stability in wind speeds ≤8. Ducted thrusters automatically adjust thrust according to wind conditions to counteract sudden gusts.

[0119] The airship unfolds into 8 circular sections, each displaying a 2m x 2m LED code (e.g., "A1"-"D2"), with brightness automatically adjusted according to ambient light.

[0120] Daytime mode: 1000 cd / m² (visible in strong light)

[0121] Night mode: 500 cd / m² (with orange-red backlight on)

[0122] After the airship takes off, calibration is completed using a direction sensor, as detailed below:

[0123] Fiber optic gyroscope initialization

[0124] Synchronize with BeiDou differential positioning data from ground stations to eliminate accumulated errors.

[0125] When using:

[0126] When the trapped personnel spotted the airship in the air, a communication channel was established via the airship:

[0127] The airship displays emergency contact numbers via LED codes (e.g., flashing "Dial 189-XXXX-099").

[0128] Simultaneous broadcast voice prompt (5G broadcast channel, content: "Please dial the number displayed on the screen")

[0129] The ground command terminal includes a ground calculation terminal and a communication receiving terminal for receiving calls from trapped personnel. The airship terminal is connected to the ground calculation terminal and uploads the airship's position and attitude data to the ground calculation terminal in real time.

[0130] The basic interaction for those trapped is as follows:

[0131] After the stranded person dials the rescue number on the airship, the ground command center communicates with them through a communication receiving terminal. Example of the conversation:

[0132] Rescuer: "Please describe the code of the airship you saw, such as the brightest combination of letters and numbers."

[0133] Trapped person: "I see B and 3 glowing directly in front of me, B is brighter than 3" → Identified as zone B3.

[0134] Direction determination logic:

[0135] If the trapped person says "B is on the left" → the airship is on the starboard side (this needs to be calculated in conjunction with the airship's real-time yaw angle θ).

[0136] If it is stated that "the number is above the luminous object" → the elevation angle φ is approximately 20°-30° (empirical value).

[0137] Rescuers used a ground-based calculation terminal to combine the descriptions from the trapped individuals with the real-time position and attitude data transmitted by the airship. Through a geometric projection model, they converted the airship codes and observation angles reported by the trapped individuals into specific coordinates and generated an EPSO optimized path. This path was then transmitted to the drone control terminal, which controlled the drone to travel to the specific coordinates for a precise search.

[0138] The search verification terminal includes a drone, which is equipped with a multispectral imaging device, a drone control terminal, and a remote data transmission device. The multispectral imaging device is connected to the drone control terminal, and the drone control terminal is connected to the ground calculation terminal via the remote data transmission device.

[0139] The drone travels along its flight path to conduct reconnaissance and transmits information in real time to the ground-based processing terminal via a remote data transmission device.

[0140] The ground command terminal generates the drone search path:

[0141] The drone is equipped with a land search and rescue model, adopts a spiral expansion search mode, and avoids known obstacles (collapsed buildings are marked as no-fly zones).

[0142] The drone took off with its payload:

[0143] Flight speed 8m / s, search altitude 30 meters (balancing field of view and resolution)

[0144] A 1080p video stream is transmitted in real time to the ground command center via a remote data transmission device.

[0145] Once the drone reaches the designated area, it begins precise searching and location determination using a multispectral imaging device.

[0146] Visible infrared detector:

[0147] Based on the improved YOLOv8 model

[0148] Identify human body features (head, limb outlines) and distress signals (waving, flashing lights).

[0149] Infrared thermal imager:

[0150] Thermal imaging detects body temperature, eliminating false alarms from rubble and debris.

[0151] Dynamic threshold segmentation technology eliminates sunlight reflection interference

[0152] LiDAR rangefinder:

[0153] After detecting the trapped person, their spatial location was confirmed using a lidar rangefinder.

[0154] Geographic coordinate system conversion (WGS84 to UTM grid)

[0155] And push the geographic coordinates to the ground-based calculation terminal:

[0156] 3D coordinates: X=125.7m, Y=88.3m, Z=1.2m (relative to ground station)

[0157] Confidence level: 98.4% (visible light + infrared dual verification).

[0158] Example 2:

[0159] like Figure 5 As shown, this invention can also be used for nighttime flood disaster location and search, as detailed below:

[0160] Special environmental adaptation measures:

[0161] Airship Adjustment

[0162] LED backlight switched to night mode (strong ability to penetrate rain and fog)

[0163] The airship descends to an altitude of 200 meters (to improve the visibility of the markers and compensate for nighttime visibility).

[0164] Drone sensor configuration:

[0165] Infrared thermal imager set to high sensitivity mode

[0166] Load the water search and rescue model:

[0167] A database of characteristics of people who have fallen into the water (including head exposure and detection of floating objects).

[0168] Location process optimization:

[0169] After the trapped person dialed the rescue hotline, the rescue team received the signal through the LoRa gateway (a frequency band with strong water penetration capability).

[0170] Multi-source data fusion positioning:

[0171] Collaboration between airship orientation calculation and UAV thermal imaging detection:

[0172] Heat source clustering analysis (excluding areas with abnormal water temperature)

[0173] Motion trajectory tracking (continuous frame displacement vector verification)

[0174] The final positioning error is less than 1.5 meters (slightly higher than that of land scenes due to water surface fluctuations).

[0175] UAV adaptive scanning strategy

[0176] Water area mode: Spiral expansion search

[0177] City mode: Fly along street topology paths

[0178] Hybrid mode: Prioritize scanning areas with abnormal water surface reflection.

[0179] Multispectral verification

[0180] Thermal imaging detection

[0181] LiDAR water surface ripple compensation

[0182] Identification of drowning victims using visible light + YOLOv8.

[0183] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A system for passive locating of a distressed person based on digital markings of a blimp, characterized in that: The system includes an airborne reference station, a search and verification station, and a ground command station. The airborne reference station comprises an airship equipped with a direction sensor and an airship terminal. The direction sensor connects to the airship terminal and transmits the airship's real-time attitude data to it. The airship's outer wall is decorated with different colored annular zones, each zone having three layers: an outer layer indicating a zone, a middle layer indicating altitude, and an inner layer containing a QR code verification bit. The ground command station includes a ground-based calculation terminal and a communication receiving terminal for receiving communications from trapped personnel. The airship terminal is signal-connected to the ground-based calculation terminal and uploads the airship's attitude data to it in real time. The search and verification station includes a drone equipped with a multispectral imaging device, a drone control terminal, and... A remote data transmission device is included. The multispectral imaging device is connected to the UAV control terminal, which is connected to the ground calculation terminal via the remote data transmission device. The UAV control terminal has a built-in water search and rescue model and a land search and rescue model. When the trapped personnel report the information of the airship they see to the communication receiving terminal, the ground calculation terminal calculates the initial location area of ​​the trapped personnel based on the reported information and the spacecraft's attitude data, and plans the UAV flight route. The UAV flight route is then uploaded to the UAV control terminal. When the initial location area is in the water area, the UAV control terminal activates the water search and rescue model and proceeds there. When the initial location area is in the land area, the UAV control terminal activates the land search and rescue model and proceeds there.

2. The passive positioning system for trapped personnel based on airship digital markers according to claim 1, characterized in that: The airborne reference end also includes a winch device, which includes a tether cable and a fixed base. The fixed base is fixed to the ground, and the tether cable is stored in the fixed base. The airship is pulled up to a predetermined altitude by the tether cable.

3. The passive positioning system for trapped personnel based on airship digital markers according to claim 1, characterized in that: The ring area is set with eight rings, and each ring area has three layers of digital rings. The outer layer is the letters AH, the middle layer is the numbers 1-8, and the inner layer is a QR code verification digit. The digital ring is a large LED digital code of 2m×2m.

4. The passive positioning system for trapped personnel based on airship digital markers according to claim 1, characterized in that: The ground-based calculation terminal is equipped with a position calculation engine. When the trapped personnel report the airship data they see, the airship terminal uploads the real-time yaw angle θ of the airship to the position calculation engine. The position calculation engine calculates the azimuth ring area using a geometric projection algorithm: α=θ+(S_id×45°)±22.5°.

5. The passive positioning system for trapped personnel based on airship digital markers according to claim 1, characterized in that: The water rescue model has a built-in database of features of people who have fallen into the water. When the drone flies to the target water area, it uses a multispectral imaging device to identify and search based on the data in the database. The land search rescue model has a built-in database of human activity features. When the drone flies to the target land area, it uses a multispectral imaging device to identify and search based on the data in the database.

6. The passive positioning system for trapped personnel based on airship digital markers according to claim 5, characterized in that: When the UAV searches along its flight path, it adopts a water mode (spiral expansion search) when searching a water area, a land mode (flying along a street topology path) when searching a landing area, and a hybrid mode (prioritizing scanning areas with abnormal water surface reflection) when searching a water area with land or a land area with water.

7. The passive positioning system for trapped personnel based on airship digital markers according to claim 5, characterized in that: The multispectral imaging device includes a visible infrared detector, an infrared thermal imager, and a lidar rangefinder for identifying human features and distress signals.

8. The passive positioning system for trapped personnel based on airship digital markers according to claim 5, characterized in that: The remote data transmission device carried by the drone is a local area network, a hotspot network, or a LoRa gateway.

9. The passive positioning method of the passive positioning system for trapped personnel based on airship digital tags according to any one of claims 1-8, characterized in that, Includes the following steps: S1. The stranded person observes the airship's code and elevation angle φ, and reports to the ground command via communication equipment by dialing a rescue call; S2. The ground command, based on the reported information and the airship's real-time yaw angle θ, calculates the azimuth sector α=θ+(S_id×45°)±22.5°, determines the area where the stranded person is located, generates an EPSO optimized path based on the area, and transmits the optimized path to the UAV control terminal; S3. The UAV control terminal controls the UAV to approach the area where the stranded person is located according to the EPSO optimized path and conducts a detailed search using a multispectral imaging device to determine the stranded person's status and precise location, and transmits the video and the stranded person's location back to the ground command in real time via a remote data transmission device; S4. After receiving the video and location of the stranded area transmitted by the drone, the ground command terminal generates a rescue plan based on the situation.

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