A method and device for starting protection of a loitering attack type unmanned aerial vehicle

Abstract

The application provides a kind of cruising attack type unmanned aerial vehicle starting protection method and device.The method comprises: before box launching, starting engine and maintaining its in idle state, make engine run with preset low power interval;At the same time, drive the engine to drive the generator to continuously output electric energy, charge the energy storage circuit;When the unmanned aerial vehicle reaches the out-of-box time, make the engine speed smoothly rise to the preset target engagement speed interval;When the engine speed is in the target engagement speed interval, make the engine and the propeller shaft power connection, realize clutch engagement;In the clutch engagement process, switch the energy storage circuit from charging mode to discharging mode;After the clutch engagement is completed, switch the energy storage circuit from discharging mode to charging mode.The application realizes high reliability starting control of cruising unmanned aerial vehicle in box launching scene, significantly improves the task success rate and operation stability of the system under complex working conditions.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle power system control technology, and in particular to a method and device for protecting the start-up of a loitering attack unmanned aerial vehicle. Background Technology

[0002] Currently, loitering attack drones generally adopt a box-type launch method, such as... Figure 1 As shown, the core control system of a loitering attack UAV includes: a main control computer, an engine, an electronic throttle controller, a Hall effect speed sensor, and a clutch. Before launch, the engine is already running but the propeller is stationary, in an idle standby mode. After launch, the clutch connects the engine and propeller, completing the system startup. However, at the moment the clutch engages, the propeller, acting as a large inertial load, is suddenly applied to the engine output, causing a sharp drop in engine speed, which in turn causes a sudden drop in generator output voltage.

[0003] Because these drones are designed for lightweight and high safety, they are generally not equipped with onboard batteries, and the system power supply relies entirely on the generator driven by the engine to generate electricity in real time. Without the support of energy storage devices, voltage drops can easily lead to insufficient power supply to critical equipment such as flight control systems, communication modules, and sensors, causing malfunctions such as control failures, communication interruptions, or system restarts, and in severe cases, mission failure or flight accidents.

[0004] Therefore, how to achieve safe startup while addressing voltage instability during the transient startup process of drones in the absence of a battery platform has become an urgent problem to be solved. Summary of the Invention

[0005] This invention provides a method and apparatus for protecting the startup of a loitering attack drone, which solves the safety and voltage instability problems of drones under transient startup conditions in the prior art.

[0006] A startup protection method for a loitering attack drone is disclosed, applied to the startup system of the loitering attack drone. The startup system includes: a main control computer, an electronic throttle controller, a Hall effect speed sensor, a triaxial acceleration sensor, an engine, a clutch, a propeller, a generator, an onboard electrical grid, and an energy storage circuit connected in parallel to the onboard electrical grid. The Hall effect speed sensor is mounted on the crankshaft end of the engine, and the triaxial acceleration sensor is mounted on the front of the fuselage to detect acceleration in the launch direction. The startup protection method includes: Before the box-type launch, the engine is started and kept in an idling state, and the engine is operated in a preset low-power range through the electro-electronic throttle controller; at the same time, the engine drives the generator to continuously output electrical energy to charge the energy storage circuit; The system determines whether the drone has reached the ejection point. Once the ejection point is reached, the electronic throttle controller initiates a speed regulation process to quickly and smoothly increase the engine speed to the preset target engagement speed range. When the engine speed is within the target engagement speed range, the clutch is driven to connect the engine to the propeller shaft and achieve clutch engagement. During clutch engagement, the energy storage circuit is switched from charging mode to discharging mode; After the clutch is engaged, the energy storage circuit is switched from discharge mode to charging mode.

[0007] Furthermore, in the above-described method for protecting loitering attack drones upon startup, the energy storage circuit includes: A supercapacitor and a current-limiting resistor are connected in series, and a unidirectional diode is connected in parallel across the current-limiting resistor.

[0008] Furthermore, in the above-described method for protecting loitering attack drones, the capacity of the supercapacitor... ; in, The system's rated voltage. P is the minimum operating voltage of the system, T is the system power, and T is the clutch engagement duration.

[0009] Furthermore, in the above-described method for protecting loitering attack drones, determining whether the drone has reached the exit time includes: The engine speed signal is acquired in real time using a Hall effect speed sensor and obtained after filtering. The engine speed is also acquired along the launch direction using a triaxial accelerometer at a preset frequency and obtained after low-pass filtering. When the engine speed is ≥ the first speed threshold and the fluctuation range is ≤ ±100RPM within N consecutive sampling points, the engine start state is determined to be established. When the X-axis acceleration value is greater than or equal to the acceleration threshold within N consecutive sampling points, the engine launch status is determined to be valid. When the engine start-up state and the engine launch-out-of-box state are both established simultaneously and the duration is greater than or equal to the first preset time, the time when the UAV arrives at the launch-out-of-box is determined.

[0010] Furthermore, in the above-described method for protecting the loitering attack UAV upon startup, the step of dynamically adjusting the throttle opening using a closed-loop control algorithm via an electronic throttle controller after reaching the launch point, so that the engine speed is smoothly increased to the preset target engagement speed range, includes: Based on the time of exiting the box, determine whether the delay time of exiting the box is greater than the preset delay time; If the delay time is greater than the preset delay time, a closed-loop control algorithm is used to dynamically adjust the throttle opening so that the engine speed can be smoothly increased to the preset target engagement speed range.

[0011] Furthermore, in the above-described method for protecting loitering attack drones, the preset delay time is preset according to the launch method, housing structure, and flight mission requirements, and supports ground debugging parameter configuration.

[0012] Furthermore, in the above-described method for protecting the start-up of a loitering attack UAV, the step of driving the clutch to connect the engine to the propeller shaft and engage the clutch when the engine speed is within the target engagement speed range includes: Based on the start time of the speed regulation process, the engine speed is collected in real time. If the engine speed is within the detection time window... If the engine speed smoothly increases to the preset target engagement speed range, then the clutch engages; if the engine speed is within the detection time window... If the speed does not smoothly increase to the preset target engagement speed range, the clutch will be forcibly engaged.

[0013] This application also provides a start-up protection device for a loitering attack drone, applied to the start-up system of a loitering attack drone; the start-up system of the loitering attack drone includes: a main control computer, an electronic throttle controller, a Hall effect speed sensor, a three-axis accelerometer, an engine, a clutch, a propeller, a generator, an onboard electrical grid, and an energy storage circuit connected in parallel to the onboard electrical grid; the Hall effect speed sensor is installed at the crankshaft end of the engine, and the three-axis accelerometer is installed at the front of the fuselage for detecting acceleration in the launch direction; The start-up protection device includes: The starting unit is used to start the engine and maintain it in an idling state before the box launch, and to make the engine run in a preset low power range through the electro-electronic throttle controller; A charging unit is used to drive the engine to continuously output electrical energy to charge the energy storage circuit; The judgment unit is used to determine whether the drone has reached the time to leave the box; The regulating unit, upon reaching the engagement point, initiates a speed regulation process via the electronic throttle controller to smoothly increase the engine speed to the preset target engagement speed range. The engagement unit is used to drive the clutch when the engine speed is within the target engagement speed range, so as to connect the engine and the propeller shaft to power and realize clutch engagement. A switching unit is used to switch the energy storage circuit from charging mode to discharging mode during clutch engagement. The switching unit is also used to switch the energy storage circuit from the discharge mode to the charging mode after the clutch engagement is completed.

[0014] The method for determining the ejection time proposed in this invention uses a continuous determination of engine speed and UAV forward acceleration, which effectively avoids control malfunctions caused by misjudgments from a single sensor (such as vibration interference or start-up delay), and ensures the timing accuracy of the start-up control process.

[0015] The method proposed in this invention effectively avoids the phenomenon of engine stalling caused by individual differences in engine speed adjustment during fixed-time engagement control mode, which can lead to some engines not reaching the optimal engagement speed and thus experiencing a drop in speed to an abnormal operating level after engagement.

[0016] The supercapacitor energy storage method proposed in this invention effectively solves the problem of potential voltage instability when the rotational speed decreases during the meshing process. At the same time, it avoids the long-term presence of electrical energy during system preparation or maintenance and withdrawal phases, effectively ensuring the safety of attack drones.

[0017] This invention achieves highly reliable start-up control for loitering drones in box-launch scenarios through a triple collaborative mechanism of precise release timing, rotational speed control, and capacitor energy storage to prevent voltage drops. This significantly improves the mission success rate and operational stability of the system under complex operating conditions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the startup system structure for a loitering attack drone in the prior art; Figure 2 This is a schematic diagram of the launch system structure for the loitering attack UAV provided in this application; Figure 3 This is a schematic diagram of the startup protection method for loitering attack UAVs provided in this application. Figure 4 A schematic diagram of the energy storage circuit structure provided in this application; Figure 5 A schematic diagram illustrating the process for determining whether the drone provided in this application has reached the unpacking time. Figure 6 A schematic diagram of the meshing control process based on rotational speed coordination provided in this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] Although some technologies have attempted to mitigate the start-up shock through structural optimization, none have fundamentally solved the triple coupling problem of sudden speed drop, voltage sag, and lack of energy storage. Patent CN111216884B, entitled "An Automatic Control Device for the Engagement of Engine and Propeller in a Box-Type Launched UAV," only designs a control device, controlling the engagement timing by setting a time interval. It fails to consider individual engine differences, cannot avoid the impact of sudden load increases, and lacks an active support mechanism for generator output voltage, thus lacking the ability to actively compensate for grid voltage fluctuations. In battery-free systems, it is difficult to ensure stable system operation.

[0022] This invention aims to overcome the problems of sudden engine speed drop, voltage drop, and system instability caused by the sudden increase of large propeller load during the box launch process of existing battery-free loitering attack UAVs. It provides a startup protection method based on the synergistic effect of speed cooperative control and supercapacitor energy storage, so as to achieve a smooth increase of engine speed to the target engagement range; precise and reliable clutch engagement; stable onboard power grid voltage and continuous operation of key equipment; and significantly improved system startup reliability and mission safety.

[0023] Figure 2 This is a schematic diagram of the launch system structure for the loitering attack UAV provided in this application, such as... Figure 2 As shown, the system's loitering attack UAV start-up system includes: a main control computer, an electronic throttle controller, a Hall speed sensor, a three-axis acceleration sensor, an engine, a clutch (electro-explosive tube clutch), a propeller, a generator, an onboard power grid, and an energy storage circuit connected in parallel to the onboard power grid; the Hall speed sensor is installed at the crankshaft end of the engine, and the three-axis acceleration sensor is installed at the front of the fuselage to detect acceleration in the launch direction.

[0024] Figure 3 This is a schematic diagram of the activation protection method for the loitering attack UAV provided in this application, such as... Figure 3 As shown, the method includes the following steps: Step 301: Before the box-type launch, start the engine and maintain it in an idling state, and use the electro-electronic throttle controller to make the engine run in a preset low-power range; at the same time, drive the engine to drive the generator to continuously output electrical energy to charge the energy storage circuit; Step 302: Determine if the drone has reached the unpacking time; Step 303: After reaching the exit point, the speed regulation process is initiated via the electronic throttle controller to smoothly increase the engine speed to the preset target engagement speed range; Step 304: When the engine speed is within the target engagement speed range, drive the clutch to connect the engine and the propeller shaft, thereby engaging the clutch. Step 305: During clutch engagement, switch the energy storage circuit from charging mode to discharging mode; Step 306: After the clutch is engaged, switch the energy storage circuit from discharge mode to charging mode.

[0025] Specifically, the loitering attack UAV provided in this application is a box-launch type, using an internal combustion engine to drive the propeller, and connecting the power output and transmission system through a clutch. Its core control system includes: a main control computer, an engine and its electronic throttle controller, a Hall effect speed sensor (mounted at the engine crankshaft end), a three-axis acceleration sensor (mounted at the front of the fuselage to detect acceleration in the launch direction), a supercapacitor energy storage unit (connected in parallel to the main power bus), and a clutch actuator (electro-explosive type, driven by control signals). All the above modules interact with each other through a high-speed serial communication interface, and the system operates under the unified scheduling of the main control computer.

[0026] In this embodiment, the above function is implemented as follows: (1) Pre-launch initiation phase: Before launch, the engine is started and kept idling. The throttle opening is adjusted to a preset low-power range (preferably 5%–15% of rated power) via the electronic throttle controller to ensure stable engine operation and complete self-checks (such as oil pressure, ignition, and speed feedback), preparing for rapid response after launch. Simultaneously, the engine drives a generator to continuously output electrical energy, which charges the supercapacitor through a charging circuit.

[0027] (2) Dynamic speed adjustment stage: The UAV control system collects engine speed signals in real time through high-precision speed sensors (such as Hall effect speed sensors) and continuously judges the UAV's exit status. After the UAV leaves the launch box, the control system starts to dynamically adjust the throttle opening based on a preset engagement speed threshold and a closed-loop control algorithm, so that the engine speed can be smoothly and quickly increased to the target engagement speed range.

[0028] (3) Clutch precise engagement stage: When the engine speed stabilizes and enters the target engagement speed range, the control system issues a command to trigger the electric detonating tube clutch. The electric detonating tube detonates instantly, driving the inner sleeve of the clutch to rigidly engage with the flywheel, thus realizing the power connection between the engine and the propeller shaft.

[0029] (4) Instantaneous power support stage: At the moment the clutch engages, the propeller load suddenly increases, causing the onboard power grid voltage to drop instantaneously. At this time, the supercapacitor energy storage circuit integrated in the onboard power grid immediately switches to discharge mode, providing instantaneous power support to critical loads such as the flight control system, navigation module, communication equipment, and attitude sensors through millisecond-level rapid discharge. This effectively prevents the system voltage from dropping below the equipment's operating threshold, avoiding equipment restarts or communication interruptions.

[0030] (5) Energy recovery and continuous power supply stage: After the clutch engages, the control system automatically switches the supercapacitor energy storage circuit to charging mode; the engine drives the generator to continuously output electrical energy, which is used to charge the supercapacitor through the charging circuit; the supercapacitor can be used as a backup energy storage unit in subsequent tasks to cope with sudden loads or short-term power outages, thereby improving the system's redundancy.

[0031] Even with optimized engine speed, a brief drop in speed is unavoidable during engagement, causing a momentary dip in generator output voltage. To maintain power supply to critical equipment, an independent energy source, separate from the generator, must replenish the grid during this voltage drop. This application addresses this issue by connecting a supercapacitor energy storage circuit in parallel with the airborne grid and pre-charging it before launch. During clutch engagement, the capacitor automatically switches to discharge mode, injecting a large current into the grid at millisecond speeds, maintaining the bus voltage above the minimum operating voltage of critical equipment until engine speed recovers and generator output voltage rebounds, thus effectively solving the voltage drop problem.

[0032] In addition, this application does not use fixed-time engagement. Instead, it determines whether the UAV has reached the exit time and only drives the clutch after the exit time has been reached, allowing the engine speed to be steadily increased to the preset target engagement speed range. This ensures that the engine has a sufficiently high mechanical inertia at the moment of engagement, so that even if the load is suddenly increased, the speed can still be maintained within the normal operating range and will not drop to the shutdown threshold. This solves the defect of the prior art that uses fixed-time engagement without considering individual differences, which causes the speed to drop when the engine speed is too low due to forced engagement.

[0033] Furthermore, because traditional fixed-time engagement control does not consider the actual engine speed, some engines may stall due to excessively low speed during engagement, or experience accelerated wear due to prolonged high-speed idling. This application only initiates the speed regulation process after the release time is reached, ensuring the engine speed smoothly increases to the preset target engagement speed range before engagement. This ensures the engine has sufficient mechanical inertia to cope with sudden load increases, effectively preventing stalling, while avoiding unnecessary high-speed operation and extending engine life.

[0034] The system provided in this application eliminates the need for bulky onboard batteries in the drone, relying solely on a small supercapacitor energy storage unit to provide voltage support during startup, thus meeting lightweight design requirements. Furthermore, the capacitor remains charged during the non-engaging phase, not continuously storing hazardous energy, facilitating maintenance and retraction. After engagement, the capacitor can still serve as a backup energy storage unit, providing additional redundancy for subsequent emergencies and enhancing the system's robustness throughout the entire mission lifecycle.

[0035] Furthermore, the energy storage circuit provided in this application includes: a supercapacitor and a current-limiting resistor connected in series, with a unidirectional diode connected in parallel across the current-limiting resistor.

[0036] Specifically, please refer to Figure 4 The supercapacitor, acting as an energy storage element, releases electrical energy the instant the clutch engages. A current-limiting resistor is connected in series in the supercapacitor's charging circuit to limit the peak current during initial power-on or charging. The diode is designed to conduct in the discharge direction and cut off in the charging direction. Specifically, the diode's anode is connected to the supercapacitor side, and the cathode is connected to the grid side (or vice versa, depending on the current direction design). This ensures that during charging, the current must flow through the current-limiting resistor, charging the supercapacitor at a slower rate and preventing large current surges to the grid. During discharge, the current output from the supercapacitor flows rapidly to the grid through the forward-biased diode, providing instantaneous energy support for critical loads.

[0037] This application presents an airborne power grid anti-sudden voltage drop design based on capacitor energy storage. A supercapacitor energy storage unit is connected in parallel to the airborne DC power supply main circuit to construct an instantaneous energy support system, effectively suppressing voltage drops during clutch engagement. The application selects the supercapacitor capacity based on the total power of the UAV's critical loads and the duration of the voltage drop during engagement, and designs a charging current-limiting circuit and a unidirectional discharge path for the energy storage supercapacitor. A current-limiting resistor is connected in series in the capacitor charging circuit to prevent a large current from impacting the power grid at power-on. A unidirectional diode is connected in parallel across the current-limiting resistor to form a low-impedance discharge path. When the UAV is initially powered on, the power grid charges the supercapacitor through the current-limiting resistor. At the moment of clutch engagement, the propeller load suddenly increases, causing a sharp drop in rotational speed, which in turn leads to a decrease in grid voltage. The supercapacitor rapidly discharges through the diode path, providing instantaneous energy replenishment to critical loads such as the flight control system, navigation module, communication equipment, and attitude sensors, effectively maintaining grid voltage stability and preventing abnormal system restarts.

[0038] The airborne power grid energy storage circuit includes a supercapacitor and its charging and discharging system. The energy storage capacitor capacity is calculated, assuming the system power is P and the rated voltage is designed to be... (Typically 28V), the minimum operating voltage is designed to be (Typically 18V), with a engagement duration of T, the supercapacitor capacitance is determined as follows: Choose a power resistor (50Ω 25W recommended) as the charging current limiting resistor to avoid heat buildup and charging circuit failure.

[0039] The method provided in this application has several advantages. First, by connecting a current-limiting resistor in series in the charging circuit, the charging current is limited to a safe range, protecting the reliability of the onboard power grid and power supply equipment. This avoids the problem that when the UAV is initially powered on or recharged after clutch engagement, the voltage across the supercapacitor is initially zero or low. If directly connected to the grid, this would generate a large instantaneous charging current, leading to severe fluctuations in generator output voltage and burning out rectifier devices. Second, by utilizing the low impedance characteristics of a diode during forward conduction, this application provides a nearly resistance-free direct path for supercapacitor discharge, ensuring that instantaneous energy can be injected into the grid quickly and efficiently. This effectively suppresses voltage drops below the device's operating threshold and avoids the problem of extremely short voltage drops during clutch engagement. Third, the energy storage circuit provided in this application requires only one power resistor, one diode, and the supercapacitor itself. It features fewer component types, smaller size, and lower cost, making it particularly suitable for loitering attack UAV platforms that are sensitive to size, weight, and cost.

[0040] Furthermore, the method provided in this application for determining whether a UAV has reached the launch time includes: using a Hall effect speed sensor to collect engine speed signals in real time, and obtaining the engine speed after filtering; using a triaxial accelerometer to collect acceleration signals along the launch direction at a preset frequency, and obtaining the engine acceleration after low-pass filtering; when the engine speed is ≥ a first speed threshold and the fluctuation range is ≤ ±100 RPM within N consecutive sampling points, it is determined that the engine start state is established; when the X-axis acceleration value is ≥ an acceleration threshold within N consecutive sampling points, it is determined that the engine launch state is established; when the engine start state and the engine launch state are established simultaneously and the duration is greater than or equal to a first preset time, it is determined that the UAV has reached the launch time.

[0041] Specifically, Figure 5 This application provides a flowchart illustrating the process for determining whether a drone has reached the unpacking time. Figure 5 As shown, the accurate method for determining the launch time includes two parts: sensor signal acquisition and status determination, and also incorporates a mechanism to prevent false judgments. The sensor signal acquisition uses a Hall effect speed sensor to collect engine speed signals in real time, sampling once every 10ms, and outputting the effective speed value after filtering. A three-axis accelerometer is used to collect acceleration signals along the launch direction (X-axis), with a sampling frequency of 200Hz, and high-frequency noise is removed by low-pass filtering (cutoff frequency 40Hz). The status determination mainly determines the time starting point for subsequent processes, i.e., the launch time of the UAV. When the engine speed is ≥3500RPM and the fluctuation range is ≤±100RPM within 10 consecutive sampling points (i.e., 0.1 seconds), the engine is considered to be in the starting state. When the X-axis (forward) acceleration value is ≥2g within 10 consecutive sampling points (i.e., 50ms), the launch state is considered to be in the launching state. The system sets a time synchronization window. =0.2 seconds. When both states are simultaneously established and the duration is ≥0.2 seconds, the system determines that the ejection moment has occurred and triggers the subsequent control process. At the same time, an anti-false judgment mechanism is designed. If only the engine start state is established but the ejection launch state is not established, or the ejection launch state is established but the engine start state is not established, the system will not trigger the subsequent process to prevent the engine from spinning at high speed inside the box and from prematurely engaging inside the box, which could damage the UAV.

[0042] This application requires that the engine start-up state and the launch-out-of-pack state be simultaneously established and maintained for a certain period of time before determining the launch-out-of-pack moment. This ensures that the subsequent engagement process is only allowed to start after the UAV has actually flown out of the pack, thus eliminating the dangerous operating conditions of engagement within the pack from the source. Furthermore, if the system misjudges the launch-out moment (e.g., assuming launch-out based solely on engine speed signal), the engine may enter high-speed operation within the pack. Due to the poor heat dissipation conditions inside the pack, prolonged high-speed idling will accelerate engine wear and may cause ignition system malfunctions due to overheating, indirectly affecting the speed response capability at the moment of engagement. This application, by incorporating acceleration signals, prevents false triggering based solely on speed signals, thereby protecting the engine and ensuring it always maintains a good working condition, guaranteeing that it can output sufficient mechanical energy to withstand load impacts at the moment of engagement.

[0043] Since the clutch disengagement moment is the zero point in the entire speed regulation process, if the error in this time reference is too large (e.g., triggering too early results in excessively long adjustment time, causing the engine to wait too long in the high-speed range; triggering too late results in insufficient adjustment time, forcing engagement before the speed reaches the target range), it will cause the engine speed to deviate from the optimal value during engagement, thereby exacerbating speed and voltage drops. This application uses a dual-signal continuous judgment to control the error in determining the clutch disengagement moment to the millisecond level, enabling subsequent delayed start-up, closed-loop speed regulation, and engagement timing judgment to be executed accurately. Ultimately, this ensures that the clutch engages when the engine has sufficient mechanical inertia, significantly reducing the speed drop and effectively mitigating the problems caused by back voltage drops.

[0044] Furthermore, the step of dynamically adjusting the throttle opening using a closed-loop control algorithm after reaching the exit time, so that the engine speed is smoothly increased to the preset target engagement speed range, specifically includes: using the exit time as a reference, determining whether the exit time delay time is greater than a preset delay time; if it is greater than the preset delay time, using a closed-loop control algorithm to dynamically adjust the throttle opening, so that the engine speed is smoothly increased to the preset target engagement speed range.

[0045] Specifically, please refer to Figure 6 , Figure 6 The schematic diagram of the meshing control process based on speed coordination provided in this application is as follows: Figure 6 As shown, this application uses the ejection moment as the time reference to construct a closed-loop speed regulation and clutch engagement coordinated control mechanism to achieve precise matching between engine speed and clutch engagement timing. Specifically, this includes: starting timing from the ejection moment, the system presets a speed regulation start delay time according to the launch method. To prevent the engine from entering high-speed operation before it is fully detached from the launch box, thus preventing premature engagement within the box and prolonged high-speed operation of the engine, and extending engine life; the engine speed signal is collected in real time, and the electronic throttle opening is dynamically adjusted using a closed-loop control algorithm to ensure that the engine speed is smoothly and quickly increased to the target engagement range; a speed detection time window is set. If the engine speed stabilizes within the target range within this time, the system automatically issues a clutch engagement command; otherwise... If the internal speed does not reach the target range, the forced engagement program is activated, allowing engagement operations to be performed at a safe speed to ensure task continuity. After the clutch engagement command is issued, the engine speed change is continuously monitored. When the speed is detected to drop back to the normal operating range, the engagement command is automatically stopped, and the system switches to the normal speed control mode, realizing a closed-loop control logic of dynamic response, precise engagement, and automatic disengagement.

[0046] The control process is initiated and the time reference is established with the launch box exit time as the unified time reference for system control. The system starts the speed adjustment process 0.15 seconds after the launch box exit time (adjustable range: 0.1–0.3 seconds) to ensure that the UAV has completely detached from the launch box and avoid interference between the propeller and the launch box after premature engagement. The delay time is preset by the launch method, box structure and flight mission requirements, and supports ground debugging parameter configuration.

[0047] The engagement timing determination for the speed coordination is achieved by continuously and smoothly increasing the engine speed through the electronic throttle controller after the engine speed regulation is initiated, with the goal of increasing the speed to a preset engagement speed range (preferred range: 9000–10000 RPM); the system collects engine speed signals in real time; and sets a speed detection time window. The preferred time is 0.8 seconds (adjustable range: 0.5–2 seconds), starting from the moment the speed regulation is initiated. If the engine speed meets the criteria for stably entering the target range within this time window, the system automatically determines that the engagement condition is met and enters the clutch control stage. If the condition is not met within the time window, the system enters the safety fault tolerance mechanism and initiates the forced engagement mode of the clutch to ensure that the task is not interrupted.

[0048] This application uses the moment of exiting the launch canister as the starting point of the entire speed adjustment process. The system does not immediately begin increasing the engine speed at the moment of exiting the launch canister. Instead, it first determines whether the delay time after exiting the launch canister is greater than a preset delay time. Speed ​​adjustment is only initiated when the delay time after exiting the launch canister exceeds a preset value (e.g., 0.15 seconds in the embodiment, adjustable range 0.1~0.3 seconds). After the delay time meets the condition, the system uses a closed-loop control algorithm (e.g., PID control) to dynamically adjust the electronic throttle opening, so that the engine speed is smoothly and quickly increased from the current idle speed to the preset target engagement speed range (e.g., 9000~10000 RPM). Therefore, after the UAV flies out of the launch canister, it does not immediately accelerate the engine. Instead, it waits for a short period of time to ensure that the UAV is completely detached from the launch canister and its flight attitude is stable before starting to accelerate smoothly, preparing for subsequent clutch engagement. If the engine speed is increased immediately after the drone leaves the enclosure, the acceleration sensor signal may spike or misinterpret, and it takes time (usually tens to hundreds of milliseconds) for the drone to completely detach from the rear of the enclosure. Premature acceleration could cause the engine speed to rise before the drone is fully out of the enclosure. At this time: the cooling conditions inside the enclosure are poor, and the heat generated by the high speed is difficult to dissipate, accelerating engine wear and potentially causing overheating and cylinder scoring; although the propeller is not engaged, the high-speed idling engine itself vibrates more intensely, potentially damaging the enclosure and the drone's structure. This application introduces a preset delay time (e.g., 0.15 seconds) to ensure that the engine only begins to accelerate after the drone is completely free from the physical constraints of the enclosure, effectively protecting the engine. If the system issues a clutch engagement command for some reason (e.g., misinterpretation) before the drone is fully out of the enclosure, the propeller will rotate inside the enclosure and collide with it, instantly causing the propeller blades to break, the drone to go out of control, or even explode. The delay time ensures that the speed increase and clutch engagement are postponed until at least after the drone has left the enclosure, providing a safety margin even if the control logic malfunctions. Prolonged high-speed idling of the engine inside the enclosure not only wastes fuel (for loitering attack drones, fuel consumption directly impacts range), but also accumulates heat within the sealed enclosure, potentially affecting electronic equipment or posing a fire hazard. The time delay forces the system to maintain low-power idling before exiting the enclosure, reducing unnecessary energy loss and heat buildup.

[0049] This application ensures that the engine starts to accelerate in a safe and stable environment by setting a reasonable delay time, thereby guaranteeing that the engine is indeed in the preset high-speed target range and in good condition at the moment of clutch engagement, thus creating a mechanical basis for mitigating subsequent voltage drop.

[0050] Furthermore, the preset delay time is preset according to the launch method, housing structure and flight mission requirements, and supports ground debugging parameter configuration.

[0051] Specifically, the preset delay time can be calibrated based on parameters such as launch method (e.g., catapult, propellant gas propulsion), launch box length, and UAV mass (supporting ground debugging), exhibiting strong engineering adaptability. For example, a slightly longer delay time can be set for heavy UAVs with slower launch speeds to ensure complete separation. Different launch methods (e.g., gas catapult, compressed air catapult, rocket booster, etc.) result in different launch speed curves for the UAV, requiring different safety delay times. Structural parameters such as launch box length, internal guide rail friction coefficient, and the gap between the launch box and the UAV affect the actual time it takes for the UAV to completely separate from the launch box. Some missions require rapid entry into high-speed operation to handle emergency maneuvers, allowing for a shorter delay; while missions with higher requirements for engine lifespan can extend the delay.

[0052] If a fixed delay time is used, if the delay is too short, for heavy drones or long launch canisters with slow ejection speeds, the engine may not be fully detached from the canister within 0.2 seconds. In this case, starting the speed increase still carries the risk of high-speed idling inside the canister or premature engagement. If the delay is too long, for light drones or short launch canisters with fast ejection speeds, 0.2 seconds may be too long. This could cause the engine to remain in the low-speed range for an extended period after safely ejecting from the canister, crowding out the time window for subsequent speed adjustment. It might not be able to increase the speed to the target range before clutch engagement, resulting in a lower speed at engagement and exacerbating speed and voltage drops.

[0053] The method provided in this application addresses the issue that loitering attack drones may be deployed on various launch platforms (shipborne, vehicle-mounted, man-portable, etc.), each with significantly different launch dynamics characteristics. This application allows for individual calibration of delay times for specific launch methods and enclosure structures, enabling the same startup protection method to be adapted to multiple platforms without modifying hardware or core control logic algorithms; optimal matching can be achieved solely through parameter configuration.

[0054] Furthermore, the step of driving the clutch when the engine speed is within the target engagement speed range to connect the engine and propeller shaft and achieve clutch engagement specifically includes the following scheme: Based on the start time of the speed regulation process, the engine speed is collected in real time; if the engine speed is within the detection time window... If the engine speed smoothly increases to the preset target engagement speed range, then the clutch engages; if the engine speed is within the detection time window... If the speed does not smoothly increase to the preset target engagement speed range, the clutch will be forcibly engaged.

[0055] Specifically, existing technologies use fixed-time engagement, failing to consider individual engine differences. Different engines may exhibit varying speed responses at the same throttle opening (e.g., machining tolerances, wear levels, fuel quality, ambient temperature). If an engine responds slowly and fails to reach the target speed within the preset adjustment time, the fixed-time scheme will still force engagement at that moment, leading to excessively low speed and a significantly increased risk of stalling. Alternatively, if the system is designed to engage only upon reaching the target speed, it may never reach the target speed (e.g., due to a minor engine malfunction), preventing the UAV from starting. This application introduces a detection time window combined with a forced engagement mechanism. For engines with normal response, the target speed is reached within the window, and engagement is performed under optimal conditions, minimizing impact and voltage drop. For engines with slow response or minor anomalies, engagement is forced at the current speed after the window ends, without further waiting. Although the impact may be slightly greater, the mission continues, preventing the UAV from crashing or freezing in mid-air.

[0056] Furthermore, in real-world combat environments, UAVs may face harsh operating conditions (such as low temperatures causing slower engine response, batch-to-batch viscosity variations in fuel, and slight sensor drift). If the control system rigidly requires reaching the target rotational speed, even a single unexpected response delay can lead to mission interruption. This application employs a forced engagement mechanism to ensure the system can still perform its basic functions under non-ideal conditions, conforming to the fault-tolerant design principles of weapon systems.

[0057] This application also provides a start-up protection device for a loitering attack drone, applied to the start-up system of a loitering attack drone; the start-up system of the loitering attack drone includes: a main control computer, an electronic throttle controller, a Hall effect speed sensor, a three-axis accelerometer, an engine, a clutch, a propeller, a generator, an onboard electrical grid, and an energy storage circuit connected in parallel to the onboard electrical grid; the Hall effect speed sensor is installed at the crankshaft end of the engine, and the three-axis accelerometer is installed at the front of the fuselage for detecting acceleration in the launch direction; The start-up protection device includes: The starting unit is used to start the engine and maintain it in an idling state before the box launch, and to make the engine run in a preset low power range through the electro-electronic throttle controller; A charging unit is used to drive the engine to continuously output electrical energy to charge the energy storage circuit; The judgment unit is used to determine whether the drone has reached the time to leave the box; The regulating unit, upon reaching the engagement point, initiates a speed regulation process via the electronic throttle controller to smoothly increase the engine speed to the preset target engagement speed range. The engagement unit is used to drive the clutch when the engine speed is within the target engagement speed range, so as to connect the engine and the propeller shaft to power and realize clutch engagement. A switching unit is used to switch the energy storage circuit from charging mode to discharging mode during clutch engagement. The switching unit is also used to switch the energy storage circuit from the discharge mode to the charging mode after the clutch engagement is completed.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for protecting the startup of a loitering attack drone, characterized in that, Application in the launch system of loitering attack drones; The loitering attack UAV start-up system includes: a main control computer, an electronic throttle controller, a Hall effect speed sensor, a three-axis accelerometer, an engine, a clutch, a propeller, a generator, an onboard electrical grid, and an energy storage circuit connected in parallel to the onboard electrical grid; the Hall effect speed sensor is installed at the crankshaft end of the engine, and the three-axis accelerometer is installed at the front of the fuselage to detect acceleration in the launch direction; The startup protection method includes: Before the box-type launch, the engine is started and kept in an idling state, and the engine is operated in a preset low-power range through the electro-electronic throttle controller; at the same time, the engine drives the generator to continuously output electrical energy to charge the energy storage circuit; The system determines whether the drone has reached the ejection point. Once the ejection point is reached, the electronic throttle controller initiates a speed regulation process to quickly and smoothly increase the engine speed to the preset target engagement speed range. When the engine speed is within the target engagement speed range, the clutch is driven to connect the engine to the propeller shaft and achieve clutch engagement. During clutch engagement, the energy storage circuit is switched from charging mode to discharging mode; After the clutch is engaged, the energy storage circuit is switched from discharge mode to charging mode.

2. The method for protecting the start-up of a loitering attack UAV according to claim 1, characterized in that, The energy storage circuit includes: A supercapacitor and a current-limiting resistor are connected in series, and a unidirectional diode is connected in parallel across the current-limiting resistor.

3. The method for protecting the start-up of a loitering attack UAV according to claim 2, characterized in that, The capacity of the supercapacitor ; in, The system's rated voltage. P is the minimum operating voltage of the system, P is the system power, and T is the clutch engagement duration.

4. The method for protecting the start-up of a loitering attack UAV according to claim 1, characterized in that, The determination of whether the drone has reached the unpacking time includes: The engine speed signal is acquired in real time using a Hall effect speed sensor and obtained after filtering. The engine speed is also acquired along the launch direction using a triaxial accelerometer at a preset frequency and obtained after low-pass filtering. When the engine speed is ≥ the first speed threshold and the fluctuation range is ≤ ±100RPM within N consecutive sampling points, the engine start state is determined to be established. When the X-axis acceleration value is greater than or equal to the acceleration threshold within N consecutive sampling points, the engine launch status is determined to be valid. When the engine start-up state and the engine launch-out-of-box state are both established simultaneously and the duration is greater than or equal to the first preset time, the time when the UAV arrives at the launch-out-of-box is determined.

5. The method for protecting the start-up of a loitering attack UAV according to claim 1, characterized in that, Upon reaching the exit point, the throttle opening is dynamically adjusted via an electronic throttle controller using a closed-loop control algorithm to rapidly and smoothly increase the engine speed to the preset target engagement speed range. This includes: Based on the time of exiting the box, determine whether the delay time of exiting the box is greater than the preset delay time; If the delay time is greater than the preset delay time, a closed-loop control algorithm is used to dynamically adjust the throttle opening so that the engine speed can be quickly and smoothly increased to the preset target engagement speed range.

6. The method for protecting the start-up of a loitering attack UAV according to claim 5, characterized in that, The preset delay time is preset according to the launch method, housing structure and flight mission requirements, and supports ground debugging parameter configuration.

7. The method for protecting the start-up of a loitering attack UAV according to claim 1, characterized in that, The step of driving the clutch to connect the engine to the propeller shaft and achieve clutch engagement when the engine speed is within the target engagement speed range includes: Based on the start time of the speed regulation process, the engine speed is collected in real time. If the engine speed is within the detection time window... If the engine speed smoothly increases to the preset target engagement speed range, then the clutch engages; if the engine speed is within the detection time window... If the speed does not smoothly increase to the preset target engagement speed range, the clutch will be forcibly engaged.

8. A start-up protection device for a loitering attack drone, characterized in that, Application in the launch system of loitering attack drones; The loitering attack UAV start-up system includes: a main control computer, an electronic throttle controller, a Hall effect speed sensor, a three-axis accelerometer, an engine, a clutch, a propeller, a generator, an onboard electrical grid, and an energy storage circuit connected in parallel to the onboard electrical grid; the Hall effect speed sensor is installed at the crankshaft end of the engine, and the three-axis accelerometer is installed at the front of the fuselage to detect acceleration in the launch direction; The start-up protection device includes: The starting unit is used to start the engine and maintain it in an idling state before the box launch, and to make the engine run in a preset low power range through the electro-electronic throttle controller; A charging unit is used to drive the engine to continuously output electrical energy to charge the energy storage circuit; The judgment unit is used to determine whether the drone has reached the time to leave the box; The regulating unit, upon reaching the engagement point, initiates a speed regulation process via the electronic throttle controller to smoothly increase the engine speed to the preset target engagement speed range. The engagement unit is used to drive the clutch when the engine speed is within the target engagement speed range, so as to connect the engine and the propeller shaft to power and realize clutch engagement. A switching unit is used to switch the energy storage circuit from charging mode to discharging mode during clutch engagement. The switching unit is also used to switch the energy storage circuit from the discharge mode to the charging mode after the clutch engagement is completed.

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