A forest fire unmanned plane cooperative extinguishing method and system based on internet of things and 5G communication

Abstract

The application relates to the technical field of forest fire extinguishing, in particular to a forest fire unmanned plane cooperative extinguishing method and system based on Internet of Things and 5G communication, which comprises the following steps: acquiring a horizontal wind speed vector of an unmanned plane in a hovering airspace and a vertical thermal radiation gradient matrix of the hovering airspace and a target area, and acquiring a target center horizontal two-dimensional absolute coordinate by intersection; taking the target center horizontal two-dimensional absolute coordinate as a terminal constraint, combining the horizontal wind speed vector, ground absolute elevation data, a throwing height constraint, a vertical thermal updraft vector, a flat flying initial speed vector, environmental air density, an inherent air resistance coefficient, a reference windward area and a load mass, and reversely solving a three-dimensional throwing advance coordinate and an air flight time; flying to the three-dimensional throwing advance coordinate, and releasing the load when a three-dimensional space straight line distance is less than a preset unhooking radius. The application can solve the problems of hovering instability and landing point deviation, and realizes accurate throwing.

Description

Technical Field

[0001] This application relates to the technical field of forest fire fighting, and in particular to a method and system for forest fire fighting using drones based on the Internet of Things and 5G communication. Background Technology

[0002] In forest fire fighting operations in mountainous areas, drone swarms are often deployed in the airspace above the fire line to precisely drop water bags or fire extinguishing bombs. Due to the intense heat release at the fire site, the low-level atmospheric environment in the operational airspace is extremely complex. Drones not only need to overcome the inherent lateral gusts at high altitudes, but are also constantly disturbed by the high-temperature thermal updrafts from the center of the fire, operating in a three-dimensional turbulent field with multiple superimposed airflow sources. The uneven canopy and significant elevation variations in real forest areas pose stringent physical requirements for the airborne system to maintain spatial coordinates and calculate drop trajectories under extreme hydrodynamic conditions.

[0003] Chinese invention patent application CN108159601A discloses a drone capable of launching intelligent fire extinguishing bombs. The system mounts an anemometer on the top of a multi-rotor fuselage, uses infrared and visible light composite equipment to locate the heating area in a fire, and obtains the unidirectional vertical distance from the fuselage to the burning surface below using an ultrasonic rangefinder. When executing the launching logic, its control module, based on the instantaneous wind direction, wind speed, and vertical height measured at a single point, directly applies the ideal projectile kinematics formula under standard gravitational acceleration to calculate the horizontal launch lead distance and the delayed detonation time of the fire extinguishing bomb. It then sets the parameters and controls the fire extinguishing bomb to be released downwind.

[0004] When the aforementioned UAV enters the airspace directly above the actual fire line, the vertical updraft generated by high-temperature thermal convection continuously produces nonlinear lift disturbances on the aircraft. Limited by the underlying control architecture relying on instantaneous unidirectional ranging and ideal kinematic equations, the onboard system cannot actively counteract this vertical turbulent interference, making it difficult for the aircraft to maintain a stable absolute spatial reference frame before and during release. Simultaneously, the unidirectional ranging module can only obtain the local altitude directly below the fuselage, detached from the overall terrain benchmark of the target drop area. When lateral gusts cause the payload to drift horizontally, the actual ground elevation corresponding to its three-dimensional descent trajectory has already deviated from the vertical distance of the initial detection point. Because the single-point calculation mechanism does not incorporate environmental fluid resistance and the absolute elevation deviation of the landing area into the calculation boundary, the preset throw lead and fixed delay detonation parameters cannot match the uneven physical distribution of the tree canopy along the route, causing the payload to deviate from the expected target center or experience an abnormally high airburst, ultimately resulting in the failure of the precision suppression link in the drop operation. Summary of the Invention

[0005] To address the issues of hovering instability and landing point deviation, and to achieve precise delivery, this application provides a method and system for collaborative firefighting using drones in forest fires, based on the Internet of Things and 5G communication.

[0006] Firstly, this application provides a method for coordinated firefighting of forest fires using drones based on the Internet of Things (IoT) and 5G communication, employing the following technical solution: A method for coordinated firefighting of forest fires using drones based on the Internet of Things (IoT) and 5G communication, comprising:

[0007] The horizontal wind speed vector of the UAV in the hovering airspace and the vertical thermal radiation gradient matrix between the hovering airspace and the target area are obtained by intersection to obtain the horizontal two-dimensional absolute coordinates of the target center.

[0008] When the rate of change of thermal center temperature difference in the hovering airspace continues to exceed the preset anti-disturbance threshold, the UAV takeoff quality generates a reverse compensation duty cycle control word to lock the absolute hovering coordinates; otherwise, the normal lock is maintained.

[0009] After locking, the absolute elevation data of the target area, the vertical thermal updraft vector, and the Z-axis elevation of the absolute hovering coordinates are extracted as the throwing height constraint. The initial velocity vector of level flight, the ambient air density, the inherent air resistance coefficient of the payload, the reference windward area, and the payload mass are also obtained.

[0010] Using the horizontal two-dimensional absolute coordinates of the target center as the endpoint constraint, and combining the horizontal wind speed vector, the absolute elevation data of the ground surface, the throwing height constraint, the vertical thermal updraft vector, the initial velocity vector of level flight, the ambient air density, the inherent air drag coefficient, the reference windward area, and the payload mass, the three-dimensional throwing lead coordinates and the flight time in the air are solved in reverse.

[0011] The payload is launched into the three-dimensional space with a lead time coordinate. When the straight-line distance in the three-dimensional space is less than the preset unhooking radius, the payload is released.

[0012] Optionally, before obtaining the horizontal wind speed vector, the method further includes:

[0013] The positioning coordinates of the UAV are obtained; when the positioning coordinates fall within a preset electronic fence, a local control network is established; airflow acquisition and multi-view thermal radiation scanning are triggered via the local control network to generate the horizontal wind speed vector, the vertical thermal radiation gradient matrix, and the horizontal two-dimensional absolute coordinates of the target center.

[0014] Optionally, the step of locking the absolute hover coordinates includes:

[0015] Using the thermal centroid temperature difference change rate and the UAV takeoff mass as indexes, the compensation duty cycle is extracted from the preset thermal convection-lift mapping table to generate the reverse compensation duty cycle control word, which is then injected into the rotor electronic speed controller to maintain the absolute hovering coordinates.

[0016] Optionally, when the loaded object is determined to be a fire extinguishing bomb, the following steps are included before release:

[0017] The absolute elevation of the airburst is constructed based on the canopy elevation of the target area and the airburst height offset; the absolute elevation of the airburst is used to replace the absolute elevation data of the ground surface, and the three-dimensional lead coordinates and the optimal airburst flight time are solved again in reverse; the optimal airburst flight time is written as a delay parameter into the fire extinguishing projectile.

[0018] Optionally, the following may also be included before release:

[0019] If the thermal radiation value below the fuselage exceeds a preset physical tolerance threshold, the UAV is controlled to vertically pull up and abort the drop. The drop height constraint, the three-dimensional drop lead coordinates, the horizontal two-dimensional absolute coordinates of the target center, the horizontal wind speed vector, the vertical thermal updraft vector, the level flight initial velocity vector, and the pull-up alarm status are sent to the formation wingman. The formation wingman increases the drop height constraint by a preset safety compensation altitude, re-triggers the reverse solution step to obtain updated three-dimensional drop lead coordinates, and controls the flight and release of the backup payload accordingly.

[0020] Optionally, the following may also be included before release:

[0021] When the attenuation parameter of the main link is greater than the preset switching threshold, the drone is controlled to hover, access the backup channel based on the local Mesh self-organizing network, close the video stream uplink port, and exclusively occupy the bandwidth of the backup channel to transmit control messages containing the three-dimensional launch lead coordinates, the flight time in the air, and the initial velocity vector of level flight.

[0022] Optionally, the steps of transmitting the control message include:

[0023] The control message is encapsulated into pure binary byte signaling with the IP header removed but the frame header included; the backup channel is downgraded to an inter-machine relay channel using the media access control layer's time division multiple access time slot reservation strategy, and the pure binary byte signaling is transmitted without fragmentation.

[0024] Optionally, after transparently transmitting the pure binary byte signaling, the method further includes:

[0025] The wingman in the formation receives and decapsulates the three-dimensional drop lead coordinates, the flight time in the air, and the initial velocity vector of level flight via the inter-aircraft relay channel to control the flight; when it reaches the three-dimensional drop lead coordinates and the distance meets the uncoupling requirements, it releases the payload.

[0026] Optionally, the reverse solution steps include:

[0027] The parameters required for the calculation are sent to the three-dimensional visualization command platform. The fluid dynamics equation containing the three-dimensional environmental wind speed vector is substituted into it. The reverse numerical optimization is performed with the horizontal two-dimensional absolute coordinates of the target center as the endpoint constraint. The three-dimensional lead coordinates of the launch and the flight time in the air are calculated and transmitted back.

[0028] Secondly, this application provides a forest fire drone-based collaborative firefighting system based on the Internet of Things (IoT) and 5G communication, employing the following technical solution: A forest fire drone-based collaborative firefighting system based on the Internet of Things (IoT) and 5G communication includes:

[0029] The data acquisition module is used to acquire the horizontal wind speed vector and the vertical thermal radiation gradient matrix, and to obtain the horizontal two-dimensional absolute coordinates of the target center through intersection.

[0030] The coordinate locking module is used to lock the absolute hovering coordinates in conjunction with the UAV takeoff mass when the rate of change of thermal center temperature difference in the hovering airspace continuously exceeds the preset anti-disturbance threshold; otherwise, it maintains the normal lock.

[0031] The parameter extraction module is used to extract the absolute elevation data of the target area surface, the vertical thermal updraft vector, and the Z-axis elevation of the absolute hovering coordinates as the throwing height constraint, and to obtain the initial velocity vector of level flight, ambient air density, and dynamic parameters of the payload.

[0032] The reverse solution module is used to combine the above parameters to reverse solve the three-dimensional launch lead coordinates and flight time in the air;

[0033] The launch execution module is used to launch the payload to the three-dimensional launch lead coordinates and release the payload when the straight-line distance in three-dimensional space is less than the preset unhooking radius.

[0034] In summary, this application includes the following beneficial technical effects:

[0035] 1. By acquiring the rate of change of thermal center temperature difference in the hovering airspace as an indicator of thermal turbulence intensity, and when this rate of change continuously exceeds the anti-disturbance threshold, a reverse compensation duty cycle control word is generated in conjunction with the takeoff mass to lock the absolute hovering coordinates. This eliminates the nonlinear lift disturbance generated by the vertical thermal turbulence on the airframe and maintains a stable spatial reference system before and during the release. Simultaneously, using the horizontal two-dimensional absolute coordinates of the target center as the endpoint constraint, and combining the horizontal wind speed vector, the absolute elevation data of the ground surface, the throwing height constraint, the vertical thermal updraft vector, and the dynamic parameters of the payload, the three-dimensional throwing lead coordinates and the flight time in the air are solved in reverse. The environmental fluid resistance and the absolute elevation deviation of the landing area are incorporated into the ballistic calculation boundary, making the actual landing point of the payload close to the target center and the airburst height match the canopy distribution, thereby effectively improving the hit accuracy of the throwing operation.

[0036] 2. When determining that the payload is a fire extinguishing grenade, the absolute elevation of the airburst is constructed based on the canopy elevation and the airburst height offset of the target area. This replaces the absolute elevation data of the ground surface, and the three-dimensional launch lead coordinates and the optimal airburst flight time are recalculated in reverse. This optimal airburst flight time is written into the fire extinguishing grenade as a delay parameter. This avoids the kinematic spatiotemporal misalignment caused by directly using the hovering coordinates of the launch point to derive the trajectory above the target center. It also corrects the horizontal distance calculation error caused by the truncated detonation, thereby improving the spatiotemporal consistency of the fire extinguishing grenade's airburst above the canopy.

[0037] 3. When the main link attenuation parameter exceeds the switching threshold, the UAV is controlled to hover and access the backup channel based on the local Mesh self-organizing network. The uplink port of the video stream is closed to exclusively occupy the bandwidth of the backup channel. The control message containing the three-dimensional drop lead coordinates, flight time in the air and initial velocity vector of level flight is encapsulated into pure binary byte signaling with the IP header removed but the frame header included. The signaling is transmitted without fragmentation using the time division multiple access time slot reservation strategy of the media access control layer. This avoids the loss of control commands caused by network layer protocol overhead and message fragmentation loss in the weak coverage environment of the fire scene, and ensures the complete reception of control messages and the continuous execution of payload release actions by the wingman in the formation under weak network conditions. Attached Figure Description

[0038] Figure 1 A flowchart illustrating the forest fire fighting method using drones based on IoT and 5G communication, provided in this application embodiment;

[0039] Figure 2 This is a schematic diagram of a drone dropping action scene provided in an embodiment of this application;

[0040] Figure 3 A schematic diagram showing the target location interface of the three-dimensional visualization command platform provided in the embodiments of this application;

[0041] Figure 4 A schematic diagram of the interface for loading a real-world 3D model on the 3D visualization command platform provided in this application embodiment;

[0042] Figure 5 A schematic diagram of a visible light image of the target area provided in an embodiment of this application;

[0043] Figure 6 This is a schematic diagram of the target area thermal infrared image provided in the embodiments of this application. Detailed Implementation

[0044] The following combination Figures 1-6 This application will be described in further detail.

[0045] This application discloses a method for coordinated forest fire suppression using drones based on the Internet of Things (IoT) and 5G communication. For example... Figure 1 As shown, the overall control flow of this method includes the main steps of data acquisition, coordinate locking, parameter extraction, reverse engineering, and deployment execution under normal operating conditions. At the execution level, it incorporates bypass judgment and wingman coordination switching branches for abnormal states such as thermal overload and link attenuation. This method is applied to a collaborative firefighting system consisting of multi-rotor UAV formations, backpack base stations, and a 3D visualization command platform.

[0046] The multi-rotor drone formation includes a lead drone and at least one wingman. The lead drone carries an onboard flight control module, a micro-meteorological sensor array, a dual-spectrum gimbal, a lightweight mesh self-organizing network communication module, a rotor electronic speed controller, a drop device, and a mechanical locking mechanism for mounting water bags or fire extinguishing bombs. The backpack-mounted base station weighs no more than 13kg and integrates a 5G baseband, a 5G NR air interface antenna, a lightweight mesh self-organizing network communication module, and a local routing processing unit, used to establish a local control network in forest fire areas. A 3D visualization command platform is deployed in the command center or forward command vehicle, combined with... Figure 4 The platform interface integrates a resource search tree panel on the left with options for rescue forces, fire locations, and reservoir layers to support the overlay and filtering of various data elements. Meanwhile, the right-hand window preloads a 900km² real-scene 3D model containing an absolute digital elevation model (DEM). The real-scene 3D model uses the CGCS2000 coordinate system or WGS-84 coordinate system to store the 3D grid, surface absolute elevation data, and tree canopy elevation.

[0047] Before the operation begins, the 3D visualization command platform sends the operation area boundary data to the backpack base station, forming a pre-defined electronic fence. This electronic fence uses a GeoJSON Polygon data structure, with latitude and longitude fields using IEEE 754 double-precision floating-point numbers and elevation fields in meters. The airborne flight control module acquires the UAV's positioning coordinates via an RTK positioning receiver. The RTK receiver outputs NMEA-0183 GGA messages, RTCM 3.x differential data, and the 3D coordinate vector used internally by the airborne flight control module. The airborne flight control module uses the positioning coordinates as input and performs spatial inclusion calculations with the pre-defined electronic fence. When the positioning coordinates fall within the pre-defined electronic fence, the airborne flight control module establishes a local area control network via the backpack base station. The local control network uses a 5G NR private network to carry the control plane. On the air interface side, the RRC connection state defined by 3GPP TS 38.331 is used to maintain the control link between the UAV and the backpack base station. The application layer control messages are carried by UDP or QUIC, and the coordinate field in the message uses fixed-length binary encoding to reduce the transmission latency in the weak coverage environment of the fire scene.

[0048] After the local area control network is established, the data acquisition steps are executed solely by the airborne flight control module. The airborne flight control module simultaneously triggers the micro-meteorological sensor array and the dual-spectrum gimbal via CAN bus, UART serial port, or Ethernet bus. The micro-meteorological sensor array generates the horizontal wind speed vector of the UAV in the hovering airspace. The horizontal wind speed vector includes the wind speed component along the geographical east direction, the wind speed component along the geographical north direction, and the sampling timestamp, in m / s. The micro-meteorological sensor array includes an ultrasonic anemometer, a barometer, and a temperature and humidity sensor, with a sampling frequency set from 10Hz to 50Hz. Thermal infrared thermometry follows Planck's radiation law and Stefan-Boltzmann's law, and the radiative exitance satisfies... ,in For ground object emissivity, The Stefan-Boltzmann constant is... The absolute temperature is used; the airborne flight control module schedules the lead aircraft and at least one wingman in formation, using dual-spectral gimbals on multiple aircraft to perform multi-view synchronous thermal radiation scanning. The real-time RTK coordinates between the lead aircraft and the wingman are used as the spatial relative observation baseline. Algebraic reconstruction technology (ART) and a multi-view epipolar geometric intersection algorithm are used to perform three-dimensional spatial tomographic reconstruction of high-temperature smoke and ash particles. Combined with... Figure 5 and Figure 6 The comparison results of visible light topography and thermal infrared scanning images show that the dual-spectrum gimbal can filter out visible light stray obscuring objects on the ground and accurately extract the distribution contours of high-brightness, high-temperature hotspots. This allows for the simultaneous acquisition of the vertical thermal radiation gradient matrix of the hovering airspace and the target area. The horizontal two-dimensional absolute coordinates of the target center are obtained through intersection using the dual-spectrum gimbal. The hovering airspace and target area data are physically sampled and isolated independently to avoid mutual contamination of the control domain space. The vertical thermal radiation gradient matrix is ​​encapsulated as a MAVLink extended message or a custom CAN FD frame. The data field of the custom CAN FD frame includes the matrix row and column numbers, temperature quantization value, timestamp, and CRC check field. The temperature quantization resolution is set to 0.1℃.

[0049] The coordinate locking step is executed solely by the airborne flight control module. The airborne flight control module extracts the rate of change of the thermal centroid temperature difference from the vertical thermal radiation gradient matrix of the hovering airspace. Specifically, the airborne flight control module uses the temperature value of each temperature sampling point in the vertical thermal radiation gradient matrix of the hovering airspace as a weight to calculate the thermal centroid coordinates. ,in For the first Temperature values ​​at each sampling point For the first The spatial location vector corresponding to each sampling point; the temperature difference between the upper and lower layers near the thermal centroid is calculated within a continuous sampling period. and with As the rate of change of thermal centroid temperature difference, this parameter accurately reflects the intensity of the local thermal updraft in the hovering airspace where the UAV is currently located, effectively avoiding interference caused by data from distant target areas flowing back into the local flight control system.

[0050] When the rate of change of thermal center temperature difference continuously exceeds the preset disturbance rejection threshold, the airborne flight control module, in conjunction with the UAV's takeoff mass, generates a reverse compensation duty cycle control word to lock the UAV's absolute hovering coordinates. When the rate of change of thermal center temperature difference does not continuously exceed the preset disturbance rejection threshold, the airborne flight control module maintains normal hovering control to lock the UAV's absolute hovering coordinates. The preset disturbance rejection threshold is set to 8℃ / s to 20℃ / s, requiring it to exceed this value for 3 to 10 consecutive sampling periods. The airborne flight control module uses the rate of change of thermal center temperature difference and takeoff mass as indices to extract the compensation duty cycle from the preset thermal convection-lift mapping table. The preset thermal convection-lift mapping table is pre-constructed based on wind tunnel calibration experiments, and its core compensation logic follows the feedforward compensation formula. ,in For takeoff mass, The rate of change of temperature difference at the thermal center of mass. A pre-calibrated empirical pull coefficient, with corresponding dimensions, is used to balance and eliminate the physical dimensions of the calculation results on the right side of the formula, thus mapping the solution result to a dimensionless control duty cycle value, with a value range set from 5.2 to 8.6. A discretized two-dimensional lookup table matrix is ​​pre-calculated using a feedforward compensation formula. The compensation duty cycle generates a differential form of reverse compensation duty cycle control word based on the fuselage attitude angle and the direction of the thermal updraft, enabling the UAV to counteract uplift disturbances on the Z-axis. The reverse compensation duty cycle control word is injected into the rotor electronic speed controller to adjust lift and maintain absolute hover coordinates. The absolute hover coordinates are obtained by fusing RTK three-dimensional coordinates, barometric altitude, IMU attitude calculation results, and gimbal line-of-sight stabilization results.

[0051] After locking the absolute hovering coordinates, the airborne flight control module first extracts the vertical thermal updraft vector mapped by the vertical thermal radiation gradient matrix of the target area. Specifically, based on the vertical thermal radiation gradient matrix of the target area, it extracts the actual measured absolute temperature values ​​at each discrete grid point on the vertical path along the Z-axis above the target center. and the boundary layer environmental reference absolute temperature Based on the energy conservation criterion of fluid mechanics and the Boussinesq buoyancy approximation model, a discrete numerical integration formula is used. The corresponding vertical thermal updraft velocity is quantitatively calculated and assigned a direction perpendicular to the Z-axis to form a vertical thermal updraft vector, where... Let gravitational acceleration be constant. The elevation step size is the distance between adjacent grid points. This derivation process realizes a rigorous physical mapping from temperature matrix data to hydrodynamic velocity vectors, ensuring that the pre-variables of the inverse approximation algorithm have definite mathematical boundaries.

[0052] Subsequently, parameter extraction and data link transmission are jointly executed by the airborne flight control module and the 3D visualization command platform. The airborne flight control module acquires the preset initial velocity vector for level flight, the ambient air density, and the inherent air drag coefficient, reference windward area, and payload mass of the UAV's payload. The preset initial velocity vector for level flight is read by the airborne flight control module based on the dynamic throwing trajectory parameters. The ambient air density is derived from the atmospheric pressure and absolute temperature measured by the micro-meteorological sensor array, and calculated based on the ideal gas law. The inherent air drag coefficient of the water bag is between 0.7 and 1.3, and its reference windward area is obtained based on the equivalent area of ​​the circumscribed circle under full load, ranging from 0.15 to 0.25 square meters. The inherent air drag coefficient of the fire extinguishing bomb is between 0.25 and 0.6, and its reference windward area is extracted based on the maximum cross-sectional area of ​​the pre-loaded bomb body, ranging from 0.03 to 0.08 square meters. The airborne flight control module transmits parameters such as horizontal wind speed vector, vertical thermal updraft vector, absolute hovering coordinates, and horizontal two-dimensional absolute coordinates of the target center to the three-dimensional visualization command platform via a backpack base station. Figure 3 As shown, the horizontal two-dimensional absolute coordinates of the bullseye are 3D anchored to the corresponding ground grid surface in the form of virtual highlighted flame primitives within the platform. Based on the horizontal two-dimensional absolute coordinates of the bullseye, the 3D visualization command platform extracts the absolute elevation data of the target area from the pre-loaded real-scene 3D model, and extracts the Z-axis elevation of the absolute hovering coordinates as the throwing height constraint.

[0053] The reverse engineering step is executed by a 3D visualization command platform. Using the horizontal two-dimensional absolute coordinates of the target center as the convergence endpoint constraint, and combining absolute ground elevation data, throw height constraints, initial velocity vector during level flight, ambient air density, inherent air drag coefficient, reference windward area, payload mass, horizontal wind speed vector, and vertical thermal updraft vector, a reverse approximation optimization is performed with the horizontal two-dimensional coordinates of the three-dimensional throw lead coordinates to be determined and the flight time in the air as independent variables. Its core lies in the pre-defined three-dimensional fluid dynamics equations. ,in For the mass of the load, The vector of gravitational acceleration. For ambient air density, The inherent air drag coefficient, For reference, windward area For the horizontal wind speed vector With vertical thermal updraft vector The synthesized three-dimensional environmental wind speed vector. Based on the clearly defined convergence boundary of the target center space, the absolute elevation data of the ground surface, the throwing height constraint, the initial velocity vector of level flight, the ambient air density, the inherent air drag coefficient, the reference windward area, and the payload mass are substituted into the preset three-dimensional fluid dynamics equations. The horizontal two-dimensional absolute coordinates of the target center are used as the convergence endpoint constraint, and the horizontal two-dimensional coordinates and the flight time in the air are used as the starting points for reverse numerical optimization. Through the fourth-order Runge-Kutta numerical integration combined with the Levenberg-Marquardt iterative method, the three-dimensional throwing lead coordinates and the flight time in the air after correcting for the three-dimensional turbulent base effect are calculated.

[0054] When the payload is determined to be a fire extinguishing grenade, to avoid kinematic and spatiotemporal misalignment caused by using the hovering coordinates of the launch point to deduce the trajectory above the target center, the 3D visualization command platform, after reverse-engineering the 3D launch lead coordinates and flight time, and before releasing the absolute hovering coordinate lock, actively extracts the canopy elevation of the target area from the real-world 3D model. Based on the canopy elevation plus a preset airburst height offset, it constructs the absolute airburst elevation. The preset airburst height offset is set to 5 to 10 meters, a value calibrated based on the effective umbrella-shaped coverage cone area of ​​the fire extinguishing grenade fragments and extinguishing agent after detonation, to avoid premature obstruction by tree branches. The system replaces the ground absolute elevation data with the absolute airburst elevation as the new terminal rigid constraint, re-triggering the reverse-engineering of the 3D launch lead coordinates and flight time. Therefore, the original three-dimensional launch lead coordinates are replaced by the newly solved three-dimensional launch lead coordinates; the newly solved air flight time is the physically consistent optimal airburst flight time, which is directly used as a delay parameter in the fire extinguishing projectile to correct the horizontal distance calculation error caused by the truncation detonation.

[0055] After completing the above calculation steps, the 3D visualization command platform then sends out the final 3D launch lead coordinates and flight time via the backpack base station.

[0056] During the drop-off execution step, after receiving the coordinates, the onboard flight control module releases the absolute hovering coordinate lock and controls the UAV to fly at a speed based on the three-dimensional drop-off lead coordinates and the initial velocity vector of level flight. This ensures that the UAV's flight speed and heading match the initial velocity vector of level flight when it reaches the three-dimensional drop-off lead coordinates. The three-dimensional straight-line distance between the UAV's current coordinates and the three-dimensional drop-off lead coordinates is calculated; the preset unhooking radius is set to 0.15 meters to 0.35 meters, a value determined based on the nominal spatial tolerance of the RTK positioning module and the action delay of the mechanical locking mechanism of the payload. Figure 2 As shown, when the UAV flies over the target area to a distance of less than the preset unhooking radius in three-dimensional space, it activates the mechanical locking mechanism to release the payload, allowing the payload to fall precisely onto the surface of the target area and generate a physical fire extinguishing coverage.

[0057] After the reverse engineering is completed and before the release, the system executes a thermal overload protection procedure. The airborne flight control module collects the thermal radiation value under the fuselage in real time; the physical dimension of the thermal radiation value is thermal radiation power density, and the preset physical tolerance threshold is set to 3500W / m² to 4500W / m², which is based on the high-temperature damage limit of the carbon fiber composite material of the fuselage. When the thermal radiation value exceeds the preset physical tolerance threshold, the UAV is controlled to vertically pull up along the Z-axis to stop the drop, and the three-dimensional drop lead coordinates, the horizontal two-dimensional absolute coordinates of the target center, the drop height constraint, the horizontal wind speed vector, the vertical thermal updraft vector, the level flight initial velocity vector, and the pull-up alarm status are sent to the wingman carrying the backup payload.

[0058] After receiving the above data and the ascent alarm status, the wingman in the formation will add a safety compensation altitude to the received throwing height constraint to generate an updated throwing height constraint. The safety compensation altitude is set to a height boundary that is increased by 15 to 25 meters in the positive direction. This value is set based on a model that shows the negative correlation between the energy of the thermal updraft in the fire and altitude, so as to ensure that the wingman in the formation can effectively cross the intense turbulence interference zone at the bottom.

[0059] The wingman, using the target's horizontal two-dimensional absolute coordinates, updated throwing altitude constraints, horizontal wind speed vector, vertical thermal updraft vector, and initial flight velocity vector, re-triggers the reverse calculation steps to obtain the three-dimensional throwing lead coordinates and flight time. Specifically, the wingman reports the updated throwing altitude constraints, target's horizontal two-dimensional absolute coordinates, horizontal wind speed vector, vertical thermal updraft vector, and initial flight velocity vector to the three-dimensional visualization command platform via a backpack base station. The three-dimensional visualization command platform replaces the original data with the updated throwing altitude constraints as the new Z-axis elevation constraints, and, together with existing parameters such as the target area's absolute surface elevation data, re-triggers the fourth-order Runge-Kutta numerical optimization step to avoid the solver deadlock due to the lack of elevation convergence boundaries. This allows the platform to obtain the updated three-dimensional throwing lead coordinates and updated flight time, which are then distributed to the wingman via the backpack base station.

[0060] The flight of the formation wingman is controlled based on updated 3D drop lead coordinates and initial flight velocity vectors, ensuring that the wingman's speed and heading match the initial flight velocity vector when reaching the updated 3D drop lead coordinates. The 3D straight-line distance between the wingman's current coordinates and the updated 3D drop lead coordinates is calculated. When the 3D straight-line distance is less than a preset unhooking radius, the wingman releases its reserve payload. Thus, during the handover process between the lead aircraft and the formation wingman after aborting the drop, the shared dynamic boundaries and elevation data of the initial flight velocity compensate for the control blind spots caused by the interruption of the action, ensuring that the system state machine continues to execute precise drops according to coherent fluid dynamics logic.

[0061] Before releasing the payload, the onboard flight control module acquires the attenuation parameters of the main link. These parameters include the reference signal received power and the continuous packet loss rate over the air interface. The preset switching threshold is set as follows: the reference signal received power is below -105 dBm or the continuous packet loss rate over the air interface is greater than 15% within 500 milliseconds. When the attenuation parameters exceed the preset switching threshold, the onboard flight control module controls the UAV to hover to abort the payload release and controls the UAV to connect to a backup channel based on the local mesh self-organizing network. The uplink port of the video stream is closed, and the control message containing the three-dimensional payload lead coordinates, flight time in the air, and initial velocity vector of level flight is encapsulated into a pure binary byte signaling message with the network layer IP header removed but the frame header included. Specifically, the frame structure of pure binary byte signaling is defined as follows: the frame header contains a 1-byte signaling type identifier, a 1-byte payload length identifier, and a 2-byte CRC16 error check code; for the calculated high-precision three-dimensional launch lead coordinates of the X, Y, and Z axes, the flight time in the air, and the X and Y axis velocity components of the level flight initial velocity vector, they are all converted into single-precision floating-point format occupying 4 bytes each according to the IEEE 754 standard, calibrated and segmented according to spatial, temporal, and dynamic order, and mapped and carried in a total of 24 bytes of payload field.

[0062] On the decapsulation side, the communication network card controller directly intercepts low-level packets without IP headers at the Media Access Control (MAC) layer and performs floating-point timing bearing and scaling parsing. Utilizing the MAC layer's time-division multiple access (TDMA) time slot reservation strategy, it exclusively uses the backup channel bandwidth and transmits pure binary byte signaling without fragmentation through the inter-machine relay channel. The wingman receives and decapsulates this signaling to extract the three-dimensional drop lead coordinates, air flight time, and initial level flight velocity vector. Based on the three-dimensional drop lead coordinates and initial level flight velocity vector, the wingman controls its flight to ensure that its speed and heading match the initial level flight velocity vector when it reaches the three-dimensional drop lead coordinates. Then, based on the three-dimensional straight-line distance between the current coordinates and the three-dimensional drop lead coordinates, it determines and releases its own payload. If the payload is determined to be a fire extinguishing bomb, the air flight time is written as a delay parameter to the payload, ensuring control and survival in weak network conditions.

[0063] This application also discloses a forest fire drone-based collaborative firefighting system based on the Internet of Things (IoT) and 5G communication, used to execute a forest fire drone-based collaborative firefighting method based on IoT and 5G communication. The system includes a virtual functional module architecture and a physical hardware architecture.

[0064] The virtual functional module architecture includes a data acquisition module, a coordinate locking module, a parameter extraction module, a reverse solving module, and a throwing execution module.

[0065] The data acquisition module is used to acquire the horizontal wind speed vector of the UAV in the hovering airspace, and simultaneously acquire the vertical thermal radiation gradient matrix of the hovering airspace and the target area based on multi-UAV collaborative three-dimensional tomographic reconstruction, and obtain the horizontal two-dimensional absolute coordinates of the target center through dual-spectral gimbal intersection.

[0066] The coordinate locking module is used to extract the rate of change of thermal center temperature difference of the vertical thermal radiation gradient matrix in the hovering airspace. When the rate of change of thermal center temperature difference is continuously greater than the preset anti-disturbance threshold, it generates a reverse compensation duty cycle control word in conjunction with the UAV takeoff quality to lock the absolute hovering coordinates. When the rate of change of thermal center temperature difference is not continuously greater than the preset anti-disturbance threshold, it maintains normal hovering control to lock the absolute hovering coordinates.

[0067] The parameter extraction module is used to extract the absolute elevation data of the target area from the preloaded real-world 3D model based on the horizontal two-dimensional absolute coordinates of the target center after the absolute hovering coordinates are locked. It also extracts the Z-axis elevation of the absolute hovering coordinates as the throwing height constraint, obtains the preset initial velocity vector of level flight, obtains the ambient air density, and obtains the inherent air resistance coefficient, reference windward area, and payload mass of the UAV's payload.

[0068] The inverse solution module is used to extract the vertical thermal updraft vector mapped from the vertical thermal radiation gradient matrix of the target area. With the horizontal two-dimensional absolute coordinates of the target center as the convergence endpoint constraint, it combines the absolute elevation data of the ground surface, the throwing height constraint, the initial velocity vector of level flight, the ambient air density, the inherent air drag coefficient, the reference windward area, the payload mass, the horizontal wind speed vector, and the vertical thermal updraft vector. It uses the horizontal two-dimensional coordinates of the three-dimensional throwing lead coordinates to be determined and the flight time in the air as independent variables to perform inverse approximation and solve for the three-dimensional throwing lead coordinates and the flight time in the air.

[0069] The drop execution module is used to unlock the absolute hover coordinates and control the UAV's flight based on the three-dimensional drop lead coordinates and the initial velocity vector of level flight, so that the UAV's flight speed and heading match the initial velocity vector of level flight when it reaches the three-dimensional drop lead coordinates; calculate the three-dimensional straight-line distance between the UAV's current coordinates and the three-dimensional drop lead coordinates; when the three-dimensional straight-line distance is less than the preset unhooking radius, release the payload. When the thermal overload pull-up aborts the release, the three-dimensional release lead coordinates, the horizontal two-dimensional absolute coordinates of the target center, the release altitude constraint, the horizontal wind speed vector, the vertical thermal updraft vector, the level flight initial velocity vector, and the pull-up alarm status are sent to the wingman carrying the backup payload. The wingman adds a safety compensation altitude to the received release altitude constraint based on the pull-up alarm status to generate an updated release altitude constraint. It then re-triggers the reverse solution of the three-dimensional release lead coordinates and the flight time in the air, in conjunction with the horizontal two-dimensional absolute coordinates of the target center, the updated release altitude constraint, the horizontal wind speed vector, the vertical thermal updraft vector, and the level flight initial velocity vector, to obtain an updated three-dimensional release lead coordinate and an updated flight time in the air. Based on the updated three-dimensional release lead coordinates and the level flight initial velocity vector, the wingman is controlled to ensure that the flight speed and heading of the wingman when reaching the updated three-dimensional release lead coordinates match the level flight initial velocity vector, and the backup payload is released when the straight-line distance in three-dimensional space is less than the preset unhooking radius. When the attenuation parameter exceeds the preset switching threshold, the drone is controlled to hover to abort the drop flight, access the backup channel based on the local Mesh self-organizing network, close the video stream uplink port, and exclusively use the bandwidth of the backup channel to transmit control messages containing the three-dimensional drop lead coordinates, in-flight flight time and level flight initial velocity vector to the formation wingman, so that the formation wingman controls its flight based on the three-dimensional drop lead coordinates and level flight initial velocity vector, and matches the flight speed and heading with the level flight initial velocity vector when reaching the three-dimensional drop lead coordinates.

[0070] The physical hardware architecture includes multi-rotor drone formations, backpack base stations, and a 3D visualization command platform, while the rest of the hardware topology and connection relationships and methods are completely mapped in the same way.

[0071] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication, characterized in that, include: The horizontal wind speed vector of the UAV in the hovering airspace and the vertical thermal radiation gradient matrix between the hovering airspace and the target area are obtained by intersection to obtain the horizontal two-dimensional absolute coordinates of the target center. When the rate of change of thermal center temperature difference in the hovering airspace continues to exceed the preset anti-disturbance threshold, the UAV takeoff quality generates a reverse compensation duty cycle control word to lock the absolute hovering coordinates; otherwise, the normal lock is maintained. After locking, the absolute elevation data of the target area, the vertical thermal updraft vector, and the Z-axis elevation of the absolute hovering coordinates are extracted as the throwing height constraint. The initial velocity vector of level flight, the ambient air density, the inherent air resistance coefficient of the payload, the reference windward area, and the payload mass are also obtained. Using the horizontal two-dimensional absolute coordinates of the target center as the endpoint constraint, and combining the horizontal wind speed vector, the absolute elevation data of the ground surface, the throwing height constraint, the vertical thermal updraft vector, the initial velocity vector of level flight, the ambient air density, the inherent air drag coefficient, the reference windward area, and the payload mass, the three-dimensional throwing lead coordinates and the flight time in the air are solved in reverse. The payload is launched into the three-dimensional space with a lead time coordinate. When the straight-line distance in the three-dimensional space is less than the preset unhooking radius, the payload is released.

2. The method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication as described in claim 1, characterized in that, Before obtaining the horizontal wind speed vector, the process also includes: The positioning coordinates of the UAV are obtained; when the positioning coordinates fall within a preset electronic fence, a local control network is established; airflow acquisition and multi-view thermal radiation scanning are triggered via the local control network to generate the horizontal wind speed vector, the vertical thermal radiation gradient matrix, and the horizontal two-dimensional absolute coordinates of the target center.

3. A method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication, as described in claim 1, is characterized in that... The step of locking the absolute hovering coordinates includes: Using the thermal centroid temperature difference change rate and the UAV takeoff mass as indexes, the compensation duty cycle is extracted from the preset thermal convection-lift mapping table to generate the reverse compensation duty cycle control word, which is then injected into the rotor electronic speed controller to maintain the absolute hovering coordinates.

4. A method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication, as described in claim 1, is characterized in that... When the payload is determined to be a fire extinguishing bomb, the following steps are also taken before release: The absolute elevation of the airburst is constructed based on the canopy elevation of the target area and the airburst height offset; the absolute elevation of the airburst is used to replace the absolute elevation data of the ground surface, and the three-dimensional lead coordinates and the optimal airburst flight time are solved again in reverse; the optimal airburst flight time is written as a delay parameter into the fire extinguishing projectile.

5. A method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication, as described in claim 1, is characterized in that... The release also included: If the thermal radiation value below the fuselage exceeds a preset physical tolerance threshold, the UAV is controlled to vertically pull up and abort the drop. The drop height constraint, the three-dimensional drop lead coordinates, the horizontal two-dimensional absolute coordinates of the target center, the horizontal wind speed vector, the vertical thermal updraft vector, the level flight initial velocity vector, and the pull-up alarm status are sent to the formation wingman. The formation wingman increases the drop height constraint by a preset safety compensation altitude, re-triggers the reverse solution step to obtain updated three-dimensional drop lead coordinates, and controls the flight and release of the backup payload accordingly.

6. A method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication, as described in claim 1, is characterized in that... The release also included: When the attenuation parameter of the main link is greater than the preset switching threshold, the drone is controlled to hover, access the backup channel based on the local Mesh self-organizing network, close the video stream uplink port, and exclusively occupy the bandwidth of the backup channel to transmit control messages containing the three-dimensional launch lead coordinates, the flight time in the air, and the initial velocity vector of level flight.

7. A method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication, as described in claim 6, is characterized in that... The steps of transmitting the control message include: The control message is encapsulated into pure binary byte signaling with the IP header removed but the frame header included; the backup channel is downgraded to an inter-machine relay channel using the media access control layer's time division multiple access time slot reservation strategy, and the pure binary byte signaling is transmitted without fragmentation.

8. A method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication, as described in claim 7, is characterized in that... After transmitting the pure binary byte signaling, it also includes: The wingman in the formation receives and decapsulates the three-dimensional drop lead coordinates, the flight time in the air, and the initial velocity vector of level flight via the inter-aircraft relay channel to control the flight; when it reaches the three-dimensional drop lead coordinates and the distance meets the uncoupling requirements, it releases the payload.

9. A method for coordinated forest fire suppression using drones based on the Internet of Things and 5G communication, as described in claim 1, is characterized in that... The reverse solution steps include: The parameters required for the calculation are sent to the three-dimensional visualization command platform. The fluid dynamics equation containing the three-dimensional environmental wind speed vector is substituted into it. The reverse numerical optimization is performed with the horizontal two-dimensional absolute coordinates of the target center as the endpoint constraint. The three-dimensional lead coordinates of the launch and the flight time in the air are calculated and transmitted back.

10. A forest fire drone-based collaborative firefighting system based on the Internet of Things and 5G communication, used to execute the method as described in any one of claims 1 to 9, characterized in that, include: The data acquisition module is used to acquire the horizontal wind speed vector and the vertical thermal radiation gradient matrix, and to obtain the horizontal two-dimensional absolute coordinates of the target center through intersection. The coordinate locking module is used to lock the absolute hovering coordinates in conjunction with the UAV takeoff mass when the rate of change of thermal center temperature difference in the hovering airspace continuously exceeds the preset anti-disturbance threshold; otherwise, it maintains the normal lock. The parameter extraction module is used to extract the absolute elevation data of the target area surface, the vertical thermal updraft vector, and the Z-axis elevation of the absolute hovering coordinates as the throwing height constraint, and to obtain the initial velocity vector of level flight, ambient air density, and dynamic parameters of the payload. The reverse solution module is used to combine the above parameters to reverse solve the three-dimensional launch lead coordinates and flight time in the air; The launch execution module is used to launch the payload to the three-dimensional launch lead coordinates and release the payload when the straight-line distance in three-dimensional space is less than the preset unhooking radius.

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