Multi-stage safety protection control method for fire extinguishing bomb of unmanned aerial vehicle

Abstract

The invention relates to the technical field of fire-fighting and unmanned system safety control, discloses a multistage safety protection control method and system for a fire extinguishing bomb of an unmanned aerial vehicle, and aims to solve the potential safety hazards of false triggering, early explosion, unauthorized detonation and the like of the fire extinguishing bomb in the prior art. According to the method, a five-stage progressive safety mechanism is constructed; physical locking is realized through a mechanical limiting device; an ignition circuit is isolated by adopting a dual-channel redundant electronic locking module; based on the historical flight state, the real-time environment data and the task planning information, executing three-level dynamic verification of airspace compliance, environment adaptability and flight stability; introducing a manual confirmation instruction of two-factor authentication and national secret encryption; and continuously monitoring the safety condition during the detonation countdown. The system comprises a mechanical locking unit, an electronic locking unit, a multi-source data acquisition unit, a dynamic safety verification unit, an instruction interaction unit and a detonation control unit. The safety, reliability and practical applicability of fire extinguishing operation of the unmanned aerial vehicle are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of fire protection and unmanned system safety control technology, specifically relating to a multi-level safety protection control method for unmanned aerial vehicle (UAV) fire extinguishing projectiles. Background Technology

[0002] With the continuous increase in the density of high-rise buildings in cities and the frequent occurrence of sudden disasters such as forest fires, traditional ground firefighting methods face bottlenecks such as delayed response and limited coverage in complex terrain or high-altitude scenarios. Unmanned aerial vehicle (UAV) firefighting systems, due to their mobility, flexibility, and rapid deployment, have become an important development direction in the field of emergency rescue. Currently, UAV-based fire extinguishing bomb delivery technology mainly relies on preset trigger logic or single sensor signals for detonation control, and its safety mechanisms generally employ fixed threshold judgments or simple status checks. However, multiple dynamic risk factors exist during firefighting missions: the UAV's flight attitude is easily affected by wind disturbances, target positioning accuracy may decrease due to smoke obscuring or GPS signal drift, and the fire extinguishing bomb's own fuse system may also experience false triggering hazards due to transportation vibrations or changes in environmental temperature and humidity. Single-level safety checks are insufficient to effectively distinguish between genuine delivery commands and abnormal interference signals, which, while ensuring rapid response, can easily lead to premature detonation, accidental detonation, and other safety accidents, seriously threatening the safety of personnel and equipment in the operational area.

[0003] Among them, the multi-level safety protection control of the drone fire extinguishing projectile focuses on suppressing unintended detonation behavior to the greatest extent possible while ensuring the timeliness of mission execution through a phased, multi-condition collaborative verification mechanism. This control strategy aims to build a full-link safety barrier from takeoff preparation and flight path to target lock and final delivery. It achieves the step-by-step release of detonation authority through real-time fusion judgment of multi-dimensional parameters such as flight status, environmental perception, command legality, and projectile health.

[0004] In existing technologies, fire extinguishing grenades often employ a dual-safety structure combining mechanical safety pins and electronic switches, or rely on single IMU data to determine delivery timing, lacking the ability to dynamically assess risks throughout the entire mission. Typical shortcomings include: the inability to adaptively adjust safety thresholds according to flight phases; difficulty in cross-validating visual recognition results with inertial navigation data; and a lack of redundant decision-making mechanisms in the event of communication interruptions or command anomalies. Especially in densely populated high-rise building areas or environments with strong electromagnetic interference, these deficiencies can easily lead to safety mechanism failure or excessive conservatism, resulting in missed optimal fire extinguishing windows. Therefore, there is an urgent need for a multi-level safety protection control method for UAV fire extinguishing grenades that can achieve multi-source information fusion, hierarchical authorization, and dynamic fault tolerance, to balance high safety with mission reliability. Summary of the Invention

[0005] This invention provides a multi-level safety protection control method for UAV fire extinguishing grenades. It constructs a five-level progressive safety control system consisting of physical isolation, electronic locking, environmental perception, mission status verification, and detonation command verification mechanisms. This system ensures high reliability and safety throughout the entire fire extinguishing operation, guaranteeing that the grenades cannot be triggered under unauthorized, non-target, or unsafe conditions. Based on dual constraints of hardware redundancy and software logic, this method performs dynamic risk assessment by combining real-time flight status, environmental parameters, and mission planning information. Restrictions are gradually lifted only when all safety conditions are met, ultimately allowing the detonation operation.

[0006] According to one aspect of the present invention, a multi-level safety protection control method for unmanned aerial vehicle (UAV) fire extinguishing projectiles is provided, comprising: During the loading stage of the fire extinguishing bomb, the fuse mechanism of the fire extinguishing bomb is physically locked by a mechanical limiting device. The mechanical limiting device consists of a retractable pin installed on the UAV mounting frame. The pin remains extended until a pre-unlocking command is received from the ground control station, preventing the fuse firing mechanism from moving. Before the drone takes off, the ignition circuit of the fire extinguishing bomb is disconnected and isolated by an electronic locking module. The electronic locking module includes a normally open solid-state relay, whose control terminal is connected to the safety enable output interface of the flight control computer. Only after the flight control computer completes the self-test and passes the mission legality verification will it output a high-level signal to drive the relay to close. During flight, the UAV continuously collects historical flight status sequences, real-time environmental perception data, and current mission planning information. The historical flight status sequences include position coordinates, velocity vectors, attitude angles, and acceleration data recorded every 100 milliseconds over the past 30 seconds. The real-time environmental perception data includes air pressure, temperature, humidity, wind speed and direction, and information on the distribution of surrounding obstacles. The current mission planning information includes the geographic coordinates of the target ignition point, the predetermined bombing altitude, the permitted detonation airspace boundaries, and a list of no-fly zones. Based on the historical flight status sequence, real-time environmental perception data, and current mission planning information, a three-level dynamic safety check is performed: the first level check determines whether the UAV has entered the permitted detonation airspace defined in the mission plan and has not deviated from the predetermined route by more than the preset threshold; the second level check determines whether the current environmental parameters are within the safe working range of the fire extinguishing bomb; and the third level check determines whether the current flight status of the UAV is stable and no emergency obstacle avoidance or return-to-home command is activated. The flight control computer sends a final enable signal to the electronic lock-up module and simultaneously sends a readiness status confirmation message back to the ground control station only after all three levels of dynamic safety checks have passed. After receiving the manual confirmation detonation command from the ground control station, the flight control computer starts the detonation countdown program. During the countdown, it continuously monitors the above three levels of safety verification conditions. If any condition fails, the detonation process is immediately terminated and the electronic locking module is relocked. If all safety conditions are still met after the countdown ends, the flight control computer outputs an ignition pulse signal to the fire extinguishing bomb ignition circuit to trigger the fire extinguishing bomb to detonate.

[0007] In one embodiment of the present invention, the retractable pin of the mechanical limiting device is driven by a stepper motor. The power supply circuit of the stepper motor is connected in series with an independent fuse and a manual reset switch to ensure that the locked state can be forcibly maintained under abnormal power supply or human intervention.

[0008] As one embodiment of the present invention, the normally open solid-state relay of the electronic locking module adopts a dual-channel redundant design. The two channels are controlled by two independent processing cores of the flight control computer. The relay can only close when both processing cores output high-level signals.

[0009] In one embodiment of the present invention, the historical flight status sequence is collected at a frequency of 10 Hz, and the data is stored using a circular buffer structure with a buffer capacity of 300 sampling points, covering the flight data of the most recent 30 seconds.

[0010] As one embodiment of the present invention, the permitted detonation airspace is a cylindrical space with a radius of 500 meters centered on the target ignition point, and its height ranges from 50 meters to 200 meters above the ground. The UAV's position coordinates are obtained through a global positioning system module, and the coordinate deviation compensation adopts a differential positioning correction algorithm.

[0011] As one embodiment of the present invention, the safe operating range of the fire extinguishing bomb is defined as an ambient temperature between -20 degrees Celsius and 60 degrees Celsius, a relative humidity of less than 90%, and a wind speed of less than 12 meters per second. The above parameters are measured in real time by an atmospheric data sensor module.

[0012] As one embodiment of the present invention, the criteria for judging the stability of the flight state are: the absolute value of the roll angle is less than 15 degrees, the absolute value of the pitch angle is less than 20 degrees, the rate of change of the yaw angle is less than 5 degrees per second, and all three-axis acceleration components are within the range of positive and negative twice the gravitational acceleration.

[0013] As one embodiment of the present invention, the detonation countdown program lasts for three seconds, and a complete three-level security check is performed every 100 milliseconds during the countdown.

[0014] As one embodiment of the present invention, the manual confirmation detonation command of the ground control station needs to pass two-factor authentication, including operator biometric identification and one-time dynamic password verification, and the command transmission adopts the national cryptographic SM four-encryption algorithm for end-to-end encryption.

[0015] As one embodiment of the present invention, after the fire extinguishing bomb is detonated, the flight control computer immediately cuts off the power to the ignition circuit and uploads the mission completion status to the ground control station. At the same time, it starts the fire extinguishing effect evaluation subroutine and uses the airborne visual sensor to perform image acquisition and thermal imaging analysis of the fire area.

[0016] According to another aspect of the present invention, a multi-level safety protection control system for unmanned aerial vehicle (UAV) fire extinguishing projectiles is provided, comprising: A mechanical locking unit is used to physically limit the fuse mechanism during the loading stage of the fire extinguishing bomb. The unit includes a retractable pin and a stepper motor that drives the pin. The electronic locking unit is used to disconnect and isolate the ignition circuit before takeoff and during flight. The unit includes a normally open solid-state relay and its dual-channel control circuit. The multi-source data acquisition unit is used to acquire historical flight status sequences, real-time environmental perception data, and current mission planning information. This unit includes a global positioning system module, an inertial measurement unit module, an atmospheric data sensor module, an airborne vision or lidar sensor, and a mission planning interface. The dynamic safety verification unit is used to perform three-level dynamic safety verification based on the multi-source data. This unit is integrated into the flight control computer and includes an airspace compliance judgment module, an environmental adaptability judgment module, and a flight stability judgment module. The command interaction unit is used to communicate with the ground control station to confirm the readiness status and exchange manual detonation commands. This unit includes an encrypted communication module and a two-factor authentication module. The detonation control unit is used to execute the detonation countdown and ignition pulse output after all safety conditions are met. This unit includes a countdown timer and an ignition drive circuit.

[0017] In one embodiment of the present invention, the output frequency of the global positioning system module in the multi-source data acquisition unit is 20 Hz, the output frequency of the inertial measurement unit module is 200 Hz, and the output frequency of the atmospheric data sensor module is 5 Hz. All sensor data have precise timestamps and are uniformly scheduled through a time synchronization bus.

[0018] As one embodiment of the present invention, the airspace compliance judgment module in the dynamic safety verification unit uses the ray projection method to calculate the shortest distance between the current position of the UAV and the boundary of the allowed detonation airspace in real time. If the distance is less than the preset safety margin, it is judged as non-compliant.

[0019] As one embodiment of the present invention, the flight stability judgment module has a built-in state observer. This observer fuses data from the inertial measurement unit and the global positioning system based on the Kalman filter algorithm, and outputs noise-suppressed attitude and acceleration estimates for stability criterion calculation.

[0020] As one embodiment of the present invention, the solid-state relay of the electronic locking unit has a rated voltage of 24 volts, a rated current of 5 amps, a response time of less than 10 microseconds, and an electrical isolation withstand voltage of not less than 2,500 volts.

[0021] In one embodiment of the present invention, the retractable pin of the mechanical locking unit is made of stainless steel, has a diameter of eight millimeters, a stroke of fifteen millimeters, a stepper motor step angle of 1.8 degrees, and a holding torque of 0.5 Nm.

[0022] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This invention fundamentally solves the major safety hazards of existing UAV firefighting systems, such as accidental triggering, premature detonation, and unauthorized detonation, by constructing a five-level progressive safety protection mechanism encompassing physical, electronic, environmental, task, and command aspects. A mechanical limit device ensures the fuse mechanism is physically locked during ground operations, preventing accidents caused by human error. The electronic locking module employs a dual-channel redundant design, achieving highly reliable electrical isolation of the ignition circuit. A three-level dynamic safety verification mechanism comprehensively considers airspace compliance, environmental adaptability, and flight stability, ensuring that the detonation preparation state is only permitted when all safe operating conditions are met. The manual confirmation of the detonation command incorporates two-factor authentication and national cryptographic encryption, effectively preventing command hijacking or forgery. Continuous safety monitoring during the detonation countdown provides a final dynamic protective barrier. These measures work together to ensure the high efficiency of firefighting operations while reducing safety risks to a theoretically minimum, significantly improving the reliability, controllability, and practical applicability of the UAV firefighting system. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall technical solution architecture of a multi-level safety protection control method for UAV fire extinguishing bombs proposed in this invention; Figure 2 This is a schematic diagram of the core principle framework of the five-level progressive safety control system in this invention; Figure 3 This is a logical flow diagram of the interaction between the three-level dynamic security verification and the detonation command in this invention. Detailed Implementation Example 1

[0024] This invention provides a multi-level safety protection control method for unmanned aerial vehicle (UAV) fire extinguishing grenades. Its core lies in constructing a five-level progressive safety control system consisting of physical isolation, electronic locking, environmental perception, mission status verification, and a multi-verification mechanism for detonation commands. This method is based on dual constraints of hardware redundancy and software logic, combining real-time flight status, environmental parameters, and mission planning information for dynamic risk assessment. Restrictions are gradually lifted only when all safety conditions are met, ultimately allowing the detonation operation. The specific implementation of this method will be described in detail below.

[0025] During the fire extinguishing bomb loading phase, a mechanical limiting device physically locks the fire extinguishing bomb's fuse mechanism. This device consists of a retractable pin mounted on the UAV's mounting frame. This pin remains extended until a pre-unlock command is received from the ground control station, preventing movement of the fuse firing mechanism. The retractable pin is driven by a stepper motor, whose power supply circuit is connected in series with an independent fuse and a manual reset switch to ensure that the locked state is maintained even in the event of a power failure or human intervention. The retractable pin is made of stainless steel, has a diameter of 8 mm, a stroke of 15 mm, a stepper motor step angle of 1.8 degrees, and a holding torque of 0.5 Nm. During the UAV's ground preparation phase, after the operator loads the fire extinguishing bomb, the system automatically checks whether the pin is in the fully extended position. If the check fails, subsequent procedures are prohibited, and an alarm signal is triggered. Only after the ground control station confirms mission authorization and sends a pre-unlock command does the flight control computer output a pulse sequence to the stepper motor, driving the pin to retract to the fully released position, thereby releasing the physical constraint on the fuse mechanism.

[0026] Before takeoff, the ignition circuit of the fire extinguishing bomb is isolated by an electronic locking module. This electronic locking module includes a normally open solid-state relay, whose control terminal is connected to the safety enable output interface of the flight control computer. Only after the flight control computer completes its self-test and passes mission legitimacy verification will it output a high-level signal to drive the relay to close. The normally open solid-state relay employs a dual-channel redundant design, with each channel controlled by one of the flight control computer's two independent processing cores. The relay closes only when both processing cores output high-level signals. The solid-state relay has a rated voltage of 24 volts, a rated current of 5 amps, a response time of less than 10 microseconds, and an electrical isolation withstand voltage of not less than 2500 volts. During the pre-takeoff self-test process, the flight control computer first performs integrity checks on its various functional modules, including sensor communication links, navigation and positioning accuracy, and power management system status. Then, it reads the current mission planning information and verifies the validity of its digital signature and the legitimacy of its geographic coordinates. If both checks pass, the two independent processing cores synchronously generate enable signals, which, after optocoupler isolation, drive the two control channels of the relay respectively. If any channel fails or the signal is inconsistent, the relay remains open, and the ignition circuit remains physically open, unable to form a complete circuit.

[0027] During flight, the system continuously collects historical flight status sequences, real-time environmental perception data, and current mission planning information for the UAV. The historical flight status sequences include position coordinates, velocity vectors, attitude angles, and acceleration data recorded every 100 milliseconds over the past 30 seconds, with a collection frequency of 10 Hz. Data storage employs a circular buffer structure with a buffer capacity of 300 sampling points, covering the flight data of the most recent 30 seconds. The real-time environmental perception data includes air pressure, temperature, humidity, wind speed and direction, and the distribution of surrounding obstacles, acquired in real-time by the atmospheric data sensor module, airborne vision, or lidar sensors. The current mission planning information includes the geographic coordinates of the target ignition point, the predetermined bombing altitude, the permitted detonation airspace boundaries, and a list of no-fly zones. This information is loaded from the ground control station via the mission planning interface and cached in the flight control computer's non-volatile memory. All sensor data is precisely timestamped and uniformly scheduled via a time synchronization bus to ensure strict alignment of multi-source data in the time dimension. The GPS module outputs at a frequency of 20 Hz, the inertial measurement unit module at 200 Hz, and the atmospheric data sensor module at 5 Hz. The flight control computer is equipped with a high-precision real-time clock, which is used to add nanosecond-level time stamps to all acquired data and build a unified time reference system based on this.

[0028] Based on the historical flight status sequence, real-time environmental perception data, and current mission planning information, a three-level dynamic safety check is performed. The first level check determines whether the UAV has entered the permitted detonation airspace defined in the mission plan and has not deviated from the predetermined flight path by more than a preset threshold. The permitted detonation airspace is a cylindrical space with a radius of 500 meters centered on the target ignition point, and its height ranges from 50 meters to 200 meters above the ground. The UAV's position coordinates are obtained through a Global Positioning System (GPS) module, and differential positioning correction algorithms are used for coordinate deviation compensation. The airspace compliance judgment module uses a ray casting method to calculate the shortest distance between the UAV's current position and the boundary of the permitted detonation airspace in real time. If this distance is less than a preset safety margin, it is considered non-compliant. The safety margin is set at 10 meters to compensate for positioning errors and flight disturbances. Simultaneously, the system compares the current flight path with the planned mission flight path and calculates the lateral offset. If the offset exceeds 30 meters, it is considered an excessive deviation from the flight path, and the first level check fails.

[0029] The second-level verification determines whether the current environmental parameters are within the safe operating range of the fire extinguishing bomb. The safe operating range is defined as an ambient temperature between -20°C and 60°C, relative humidity below 90%, and wind speed less than 12 meters per second. These parameters are measured in real-time by an atmospheric data sensor module and processed using a moving average filter to suppress transient noise. The system compares the filtered environmental parameters with preset thresholds item by item; if any parameter exceeds the range, the second-level verification is deemed a failure. For example, if the temperature sensor reading is 61°C, even if other parameters are normal, it is determined that the environment is unsuitable for detonation, and the subsequent process is immediately terminated.

[0030] The third-level verification determines whether the UAV's current flight state is stable and whether there are no emergency obstacle avoidance or return-to-home commands activated. The flight stability judgment criteria are: roll angle absolute value less than 15 degrees, pitch angle absolute value less than 20 degrees, yaw rate of change less than 5 degrees per second, and all three-axis acceleration components within ±2 times the gravitational acceleration range. The flight stability judgment module has a built-in state observer, which uses a Kalman filter algorithm to fuse data from the inertial measurement unit and the global positioning system, outputting noise-suppressed attitude and acceleration estimates for stability criterion calculation. The Kalman filter state vector includes position, velocity, attitude angles, and their first derivatives, and the process noise covariance matrix is ​​dynamically adjusted according to the flight mode. Furthermore, the system monitors the flight control command queue in real time. If an emergency obstacle avoidance, low battery return-to-home, or autonomous return-to-home command triggered by communication interruption is detected as active, the third-level verification is considered a failure regardless of the flight attitude.

[0031] Only after all three levels of dynamic safety checks have passed will the flight control computer send a final enable signal to the electronic interlock module and simultaneously send a readiness status confirmation message back to the ground control station. The final enable signal is a continuous high-level pulse with a width of 500 milliseconds, used to ensure reliable relay engagement. The readiness status confirmation message includes the current UAV position, altitude, remaining battery power, environmental parameter summary, and a timestamp indicating successful checks. It is encrypted end-to-end using the national cryptographic SM quad encryption algorithm and then uploaded via wireless data link.

[0032] Upon receiving the manual confirmation detonation command from the ground control station, the flight control computer initiates the detonation countdown program. This manual confirmation detonation command requires two-factor authentication, including operator biometric identification and a one-time dynamic password verification. Biometric identification uses fingerprint or iris recognition, with a matching threshold set at 95 points. The one-time dynamic password is generated by a dedicated token and is valid for 30 seconds. The entire command transmission uses the national cryptographic standard SM4 encryption algorithm, with the key negotiated and generated by the flight control computer and the ground control station through a pre-shared key mechanism. The detonation countdown program lasts for three seconds, during which a complete three-level security check is performed every 100 milliseconds. If any check fails during the countdown, the detonation process is immediately aborted, the final enable signal is cut off, the electronic locking module is relocked, and an abort reason code is sent to the ground control station.

[0033] After the countdown ends, if all safety conditions remain met, the flight control computer outputs an ignition pulse signal to the fire extinguishing grenade ignition circuit, triggering the detonation of the fire extinguishing grenade. The ignition pulse signal is a single pulse with a width of 500 microseconds and an amplitude of 24 volts, which is amplified to drive the ignition bridge wire. Before outputting the ignition pulse, the system re-verifies the closed state of the electronic locking module; if an open relay contact is detected, the pulse output is rejected. After detonation, the flight control computer immediately cuts off the power to the ignition circuit and uploads the mission completion status to the ground control station, simultaneously initiating the fire extinguishing effect evaluation subroutine. This subroutine uses airborne visual sensors to acquire images and perform thermal imaging analysis of the fire area, extracting the flame area change rate, temperature gradient distribution, and smoke concentration decay curve to generate a fire extinguishing effectiveness evaluation report.

[0034] Throughout the control process, all critical decision-making nodes are equipped with a logging mechanism. Log content includes timestamps, input data snapshots, verification results, instruction source, and execution status, stored in a tamper-proof read-only storage area. The log employs a cyclic overwrite strategy, retaining complete records of the most recent one hundred tasks. Furthermore, the system has a self-diagnostic function, capable of real-time monitoring of mechanical limit device position feedback, electronic locking module contact status, sensor health, and communication link quality. Upon detecting any anomalies, it enters a safety lockout mode, prohibiting any operations that could potentially trigger an explosion.

[0035] The aforementioned method achieves rigorous control over the entire detonation process of the fire extinguishing bomb through a five-level progressive safety mechanism. Physical locking ensures absolute safety on the ground, electronic locking provides electrical isolation redundancy, three-level dynamic verification enables real-time risk assessment during flight, manual confirmation introduces final human decision-making, and countdown monitoring constructs the last dynamic line of defense. Logical dependencies are formed between each level; the next level cannot be activated until the previous level is released, ensuring that safety constraints cannot be circumvented. This method, while ensuring the high efficiency of firefighting operations, reduces the risks of accidental triggering, premature detonation, and unauthorized detonation to the theoretical minimum, significantly improving the practical reliability and operational safety of the UAV firefighting system.

Claims

1. A multi-level safety protection control method for unmanned aerial vehicle (UAV) fire extinguishing projectiles, characterized in that, include: During the loading stage of the fire extinguishing bomb, the fuse mechanism of the fire extinguishing bomb is physically locked by a mechanical limiting device. The mechanical limiting device consists of a retractable pin installed on the UAV mounting frame. The pin remains extended until a pre-unlocking command is received from the ground control station, preventing the fuse firing mechanism from moving. Before the drone takes off, the ignition circuit of the fire extinguishing bomb is disconnected and isolated by an electronic locking module. The electronic locking module includes a normally open solid-state relay, whose control terminal is connected to the safety enable output interface of the flight control computer. Only after the flight control computer completes the self-test and passes the mission legality verification will it output a high-level signal to drive the relay to close. During flight, the UAV continuously collects historical flight status sequences, real-time environmental perception data, and current mission planning information. The historical flight status sequences include position coordinates, velocity vectors, attitude angles, and acceleration data recorded every 100 milliseconds over the past 30 seconds. The real-time environmental perception data includes air pressure, temperature, humidity, wind speed and direction, and information on the distribution of surrounding obstacles. The current mission planning information includes the geographic coordinates of the target ignition point, the predetermined bombing altitude, the permitted detonation airspace boundaries, and a list of no-fly zones. Based on the historical flight status sequence, real-time environmental perception data, and current mission planning information, a three-level dynamic safety check is performed: the first level check determines whether the UAV has entered the permitted detonation airspace defined in the mission plan and has not deviated from the predetermined route by more than the preset threshold; the second level check determines whether the current environmental parameters are within the safe working range of the fire extinguishing bomb; and the third level check determines whether the current flight status of the UAV is stable and no emergency obstacle avoidance or return-to-home command is activated. The flight control computer sends a final enable signal to the electronic lock-up module and simultaneously sends a readiness status confirmation message back to the ground control station only after all three levels of dynamic safety checks have passed. After receiving the manual confirmation detonation command from the ground control station, the flight control computer starts the detonation countdown program. During the countdown, it continuously monitors the above three levels of safety verification conditions. If any condition fails, the detonation process is immediately terminated and the electronic locking module is relocked. If all safety conditions are still met after the countdown ends, the flight control computer outputs an ignition pulse signal to the fire extinguishing bomb ignition circuit to trigger the fire extinguishing bomb to detonate.

2. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 1, characterized in that, The retractable pin of the mechanical limiting device is driven by a stepper motor. The power supply circuit of the stepper motor is connected in series with an independent fuse and a manual reset switch to ensure that the locked state can be forcibly maintained under abnormal power supply or human intervention.

3. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 2, characterized in that, The normally open solid-state relay of the electronic locking module adopts a dual-channel redundant design. The two channels are controlled by two independent processing cores of the flight control computer. The relay can only close when both processing cores output high-level signals.

4. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 3, characterized in that, The historical flight status sequence is collected at a frequency of 10 Hz, and the data is stored using a circular buffer structure with a buffer capacity of 300 sampling points, covering the flight data of the most recent 30 seconds.

5. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 4, characterized in that, The permitted detonation airspace is a cylindrical space with a radius of 500 meters centered on the target ignition point, and its height ranges from 50 meters to 200 meters above the ground. The UAV's position coordinates are obtained through a global positioning system module, and the coordinate deviation compensation adopts a differential positioning correction algorithm.

6. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 5, characterized in that, The safe operating range of the fire extinguishing bomb is defined as an ambient temperature between -20°C and 60°C, a relative humidity below 90%, and a wind speed of less than 12 meters per second. These parameters are measured in real time by an atmospheric data sensor module.

7. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 6, characterized in that, The criteria for judging flight stability are: the absolute value of the roll angle is less than 15 degrees, the absolute value of the pitch angle is less than 20 degrees, the rate of change of the yaw angle is less than 5 degrees per second, and all three-axis acceleration components are within the range of positive and negative twice the gravitational acceleration.

8. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 7, characterized in that, The detonation countdown program lasts for three seconds, and a complete three-level security check is performed every 100 milliseconds during the countdown.

9. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 8, characterized in that, The manual confirmation of the detonation command at the ground control station requires two-factor authentication, including operator biometric identification and one-time dynamic password verification. The command transmission uses the national cryptographic SM four-encryption algorithm for end-to-end encryption.

10. The multi-level safety protection control method for UAV fire extinguishing projectiles according to claim 9, characterized in that, After the fire extinguishing bomb detonates, the flight control computer immediately cuts off the power to the ignition circuit and uploads the mission completion status to the ground control station. At the same time, it starts the fire extinguishing effect evaluation subroutine and uses the airborne visual sensor to acquire images and perform thermal imaging analysis of the fire area.

11. A multi-level safety protection control system for unmanned aerial vehicle (UAV) fire extinguishing projectiles, characterized in that, include: A mechanical locking unit is used to physically limit the fuse mechanism during the loading stage of the fire extinguishing bomb. The unit includes a retractable pin and a stepper motor that drives the pin. The electronic locking unit is used to disconnect and isolate the ignition circuit before takeoff and during flight. The unit includes a normally open solid-state relay and its dual-channel control circuit. The multi-source data acquisition unit is used to acquire historical flight status sequences, real-time environmental perception data, and current mission planning information. This unit includes a global positioning system module, an inertial measurement unit module, an atmospheric data sensor module, an airborne vision or lidar sensor, and a mission planning interface. The dynamic safety verification unit is used to perform three-level dynamic safety verification based on the multi-source data. This unit is integrated into the flight control computer and includes an airspace compliance judgment module, an environmental adaptability judgment module, and a flight stability judgment module. The command interaction unit is used to communicate with the ground control station to confirm the readiness status and exchange manual detonation commands. This unit includes an encrypted communication module and a two-factor authentication module. The detonation control unit is used to execute the detonation countdown and ignition pulse output after all safety conditions are met. This unit includes a countdown timer and an ignition drive circuit.

12. The multi-level safety protection control system for UAV fire extinguishing projectiles according to claim 11, characterized in that, The output frequency of the global positioning system module in the multi-source data acquisition unit is 20 Hz, the output frequency of the inertial measurement unit module is 200 Hz, and the output frequency of the atmospheric data sensor module is 5 Hz. All sensor data have precise timestamps and are uniformly scheduled through a time synchronization bus.

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