A target tracking and firing method for unmanned aerial gun sight

Abstract

The present disclosure provides a target tracking and firing method for unmanned aerial gun sight, comprising: locking a target by using a viewing and sighting system of a gun sighting system, driving the gun sighting system by a two-axis servo stabilizing component to make a gun sighting line point to the target, and controlling the gun to implement firing on the target; in the firing process, real-time acquiring attitude angle information of the unmanned aerial vehicle and servo angle information of the gun sighting system, performing coordinate fusion operation on the attitude angle information and the servo angle information, and predicting a servo azimuth angle and a servo pitch angle that the gun sighting system should point to after firing; after the target is lost due to the pose offset of the gun sighting system caused by the recoil, the gun sighting system is driven to point to the target again by the two-axis servo stabilizing component according to the predicted servo azimuth angle and the servo pitch angle, the target is tracked and locked again, and the firing is completed again. The present disclosure solves the problem that the target is lost due to the pose offset caused by the recoil of the gun by real-time fusion of the unmanned aerial vehicle attitude angle and the gun sighting servo angle to predict the recall position.

Description

Technical Field

[0001] This disclosure relates to the field of airborne gun aiming stabilization platforms, and more specifically to a target tracking and firing method for an unmanned aerial vehicle (UAV) gun aiming system. Background Technology

[0002] Currently, drones primarily use mechanically fixed methods to mount firearms. The firearms and sighting systems lack azimuth and pitch linkage capabilities, limiting firing to a fixed angle after assembly. This makes stable target locking, tracking, and precise engagement impossible under dynamic flight conditions. More importantly, existing solutions do not specifically address the recoil issue upon firing. The recoil impact at the moment of firing causes a significant pitch deflection in the sighting system, resulting in the line of sight deviating from the target and the sighting system losing target imagery for a short period. This makes it impossible to quickly recover tracking and complete continuous firing after a single shot, severely restricting the combat effectiveness of drone-mounted firearms. Summary of the Invention

[0003] In view of the above problems, this disclosure provides a method for target tracking and firing of a recoil-resistant UAV-mounted gun sight.

[0004] This disclosure provides a target tracking and firing method for an unmanned aerial vehicle (UAV) equipped with a gun sight, comprising: locking onto a target using the sight system of the gun sight system; driving the gun sight system to point the aiming line of the gun at the target via a two-axis servo stabilization component; and controlling the gun to fire at the target; during firing, acquiring the attitude angle information of the UAV and the servo angle information of the gun sight system in real time; performing coordinate fusion calculation on the attitude angle information and the servo angle information to predict the servo azimuth angle and servo pitch angle that the gun sight system should point to after firing; and after the recoil causes the gun sight system to lose its position due to attitude shift, the gun sight system is driven to point back at the target based on the predicted servo azimuth angle and servo pitch angle, re-tracking and locking onto the target and firing again.

[0005] According to embodiments of this disclosure, locking a target using the aiming system of a gun sight system includes: performing multispectral detection on the target using a visible light camera, an infrared detector, and a laser rangefinder arranged on the same optical axis; fusing the target position information obtained by each sensor in the same optical axis coordinate system to obtain a unified position coordinate of the target in the gun sight system coordinate system; and driving a two-axis servo stabilization component based on the unified position coordinate to align the gun firing axis with the target.

[0006] According to embodiments of this disclosure, a two-axis servo stabilization component drives an azimuth motor and a pitch motor using a proportional-integral (PI) control algorithm with lead and lag self-tuning via a servo controller. This includes: tuning the PI control parameters with crossover frequency and phase margin as constraints; tuning the lead parameters to raise the phase in the mid-to-high frequency band; tuning the lag parameters to enhance the gain in the low-frequency band; jointly fine-tuning the parameters of the PI control, lead, and lag components to ensure the system simultaneously meets preset targets for phase margin, gain margin, low-frequency gain, and crossover frequency; and driving the azimuth and pitch motors with the tuned PI control, lead, and lag parameters.

[0007] According to embodiments of this disclosure, when driving the azimuth motor and the pitch motor, a high-frequency suppression step for the speed feedback signal is further included: a first-order inertial filter module is connected in series in the speed feedback signal path of the speed loop controller, the cutoff frequency is determined by identifying the system frequency characteristics, and high-frequency disturbances above the cutoff frequency are filtered and suppressed; a notch filter module is connected in series in the speed feedback signal path, the notch filter center frequency is set as the system resonant frequency, and frequency-selective suppression is performed on the amplitude instability range at the resonant frequency.

[0008] According to an embodiment of this disclosure, the cutoff frequency of the first-order inertial filter module is determined by: identifying the open-loop frequency characteristics of the gun aiming system to obtain the actual Bode plot of the system; identifying the main frequency range of high-frequency disturbances based on the Bode plot, and setting the cutoff frequency at the starting frequency of the high-frequency disturbance range.

[0009] According to embodiments of this disclosure, attitude angle information and servo angle information are fused together to predict the servo azimuth and servo pitch angles that the aiming system should point to after firing. This includes: constructing an attitude rotation matrix from the UAV coordinate system to the geographic coordinate system using the current azimuth, pitch, and roll angles of the UAV; constructing a pointing transformation matrix from the aiming system coordinate system to the UAV coordinate system using the current servo azimuth and servo pitch angles of the aiming system; and using the attitude rotation matrix and the pointing transformation matrix, performing coordinate transformation on the position information of the target in the geographic coordinate system before firing, and calculating the servo azimuth and servo pitch angles that the aiming system should point to after firing to re-aime at the target.

[0010] According to embodiments of this disclosure, driving the gun aiming system to re-point at the target based on the predicted servo azimuth and servo pitch angles includes: after the firing command is issued, when the angular velocity disturbance caused by recoil exceeds a first preset threshold, using the predicted servo azimuth and servo pitch angles as servo control commands to drive the azimuth motor and pitch motor to output compensating torque, causing the gun aiming system to revert to the direction of the target; after the angular velocity disturbance of the gun aiming system is less than a second preset threshold, the observation and aiming system reconfirms the target lock status, and triggers the next firing command after confirming the lock.

[0011] A second aspect of the present invention provides a UAV-borne gun aiming system capable of implementing the aforementioned UAV-borne gun aiming target tracking and firing method, comprising: a two-axis servo stabilization assembly, including a servo azimuth assembly and a servo pitch assembly, for providing drive torque in the azimuth and pitch directions, wherein the servo azimuth assembly and the servo pitch assembly are connected via a rotating shaft to form a two-axis stabilization platform, and at least includes an azimuth frame, an azimuth axis, an azimuth motor, and an azimuth angle sensor, wherein the azimuth motor drives the azimuth frame to rotate around the azimuth axis via the azimuth axis, for providing drive torque in the azimuth direction; the servo pitch assembly is rotatable via a rotating shaft. The device is mounted on the azimuth frame of the servo azimuth assembly and includes at least a pitch U-shaped bracket, a pitch axis, a pitch motor, a pitch angle sensor, and an inertial measurement unit. The pitch motor drives the pitch U-shaped bracket to rotate around the pitch axis via the pitch axis, providing driving torque in the pitch direction. The sighting system is fixedly mounted on the servo pitch assembly and is used for locking onto and tracking targets. The firearm is fixedly mounted on the servo pitch assembly and located below the sighting system. The firing axis of the firearm is parallel to the aiming axis of the sighting system and is used to engage targets locked by the sighting system according to the adjustment of the two-axis servo stabilization components.

[0012] According to embodiments of this disclosure, the system further includes a servo controller, which is signal-connected to the azimuth motor, pitch motor, azimuth angle sensor, pitch angle sensor, and inertial measurement unit, and communicatively connected to the UAV flight control unit, for controlling the movement of the servo azimuth and servo pitch components; the servo controller includes a speed loop controller, a current loop controller, a PWM power amplifier module, and a current sensor, wherein: the speed loop controller has an input terminal for receiving speed commands and speed feedback signals from the inertial measurement unit, and an output terminal connected to the input terminal of the current loop controller for outputting current commands; the current loop controller has an input terminal connected to the output terminal of the speed loop controller and the signal output terminal of the current sensor, and an output terminal connected to the input terminal of the PWM power amplifier module for outputting motor control signals; the PWM power amplifier module has an input terminal connected to the output terminal of the current loop controller, and its output terminal connected to the azimuth motor or pitch motor for providing drive current; the current sensor has a current detection terminal connected in series in the power supply circuit of the azimuth motor or pitch motor, and its signal output terminal connected to the feedback input terminal of the current loop controller for providing current feedback signals.

[0013] According to embodiments of this disclosure, the servo controller further includes a first-order inertial filter module and a notch filter module; the first-order inertial filter module is connected in series in the speed feedback signal input terminal or the forward path of the speed loop controller; the notch filter module is connected in series in the speed feedback signal input terminal of the speed loop controller.

[0014] According to the target tracking and firing method of the UAV-borne gun sight provided in this disclosure, after locking the target through the observation and aiming system, the two-axis servo stabilization component drives the gun aiming line to point at the target and fire. During the firing process, the UAV attitude angle and the gun sight servo angle are fused in real time to predict the callback position. Since the coordinate fusion calculation gives the target servo angle prediction value after the recoil disturbance is eliminated at the moment of firing, it solves the problem that the gun sight system posture shift caused by the recoil of the gun causes the target to be lost and the callback direction cannot be quickly determined. It realizes the rapid callback, relocking and continuous firing of the target without relying on visual re-search under recoil disturbance. Attached Figure Description

[0015] Figure 1 A flowchart illustrating a target tracking and firing method for an unmanned aerial vehicle (UAV) equipped with a gun sight, provided as an embodiment of the present invention;

[0016] Figure 2 A schematic diagram of an unmanned aerial vehicle (UAV) mounted gun aiming system according to an embodiment of the present disclosure is shown.

[0017] Figure 3 A Bode diagram of a PI controller according to an embodiment of the present disclosure is illustrated schematically;

[0018] Figure 4 A Bode plot illustrating the lead-out stage according to an embodiment of the present disclosure is shown schematically.

[0019] Figure 5 A Bode plot of hysteresis is schematically shown according to an embodiment of the present disclosure;

[0020] Figure 6 A Bode diagram of a PI controller according to an embodiment of the present disclosure is illustrated schematically;

[0021] Figure 7 A block diagram of a stable loop servo control according to an embodiment of the present disclosure is schematically shown;

[0022] Figure 8 An open Bode plot of a first-order inertial filter according to an embodiment of the present disclosure is illustrated schematically.

[0023] Figure 9 An open-loop Bode plot of the velocity loop according to an embodiment of the present disclosure is illustrated schematically;

[0024] Figure 10 An open-loop Bode plot of a velocity loop notch filter according to an embodiment of the present disclosure is schematically shown.

[0025] Figure 11 A schematic diagram illustrating the tracking firing and angle adjustment process of a gun aiming system according to an embodiment of the present disclosure is shown.

[0026] Figure 12A schematic diagram of a physical image of an unmanned aerial vehicle (UAV) gun aiming system according to an embodiment of the present disclosure is shown.

[0027] Figure 13 A test diagram according to an embodiment of the present disclosure is illustrated schematically;

[0028] Figure 14 A diagram illustrating test results according to an embodiment of the present disclosure is shown schematically. Detailed Implementation

[0029] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0031] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0032] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0033] Figure 1 This is a flowchart illustrating a target tracking and firing method for an unmanned aerial vehicle (UAV) equipped with a gun sight, as provided in an embodiment of the present invention. Figure 1As shown, this disclosure provides a target tracking and firing method for an unmanned aerial vehicle (UAV) equipped with a gun sight, including: S1, locking the target using the aiming system of the gun sight system, driving the gun sight system to point the aiming line of the gun at the target through a two-axis servo stabilization component, and controlling the gun to fire at the target; S2, during firing, acquiring the attitude angle information of the UAV and the servo angle information of the gun sight system in real time, performing coordinate fusion calculation on the attitude angle information and the servo angle information, and predicting the servo azimuth angle and servo pitch angle that the gun sight system should point to after firing; S3, after the recoil causes the gun sight system to lose its position due to attitude shift, the gun sight system is driven to point back at the target based on the predicted servo azimuth angle and servo pitch angle, re-tracking and locking the target and firing again.

[0034] Based on the above embodiments, the aiming system of the gun sight system is used to lock the target, including: performing multispectral detection on the target by using a visible light camera, an infrared detector and a laser rangefinder set on the same optical axis; fusing the target position information obtained by each sensor in the same optical axis coordinate system to obtain the unified position coordinates of the target in the gun sight system coordinate system; and driving a two-axis servo stabilization component based on the unified position coordinates to align the gun firing axis with the target.

[0035] Based on the above embodiments, the two-axis servo stabilization component drives the azimuth and pitch motors using a proportional-integral (PI) control algorithm with lead and lag self-tuning via a servo controller. This includes: tuning the PI control parameters with crossover frequency and phase margin as constraints; tuning the lead parameters to raise the phase in the mid-to-high frequency band; tuning the lag parameters to enhance the gain in the low frequency band; jointly fine-tuning the parameters of the PI control, lead, and lag components to ensure that the system simultaneously meets the preset targets for phase margin, gain margin, low-frequency gain, and crossover frequency; and driving the azimuth and pitch motors with the tuned PI control, lead, and lag parameters.

[0036] In this embodiment, the servo control of the intelligent gun aiming system adopts a PI+lead-lag self-tuning algorithm, wherein the PI controller is as follows:

[0037]

[0038] To control the gain, increase Increase system gain; decrease The overall system gain decreases, but the system phase remains unchanged. The integral frequency is expressed in Hz. The integrator can improve low-frequency gain but reduces phase, leading to a decrease in the system's phase margin. This is relevant in a PI controller. and These correspond to the controller gain and corner frequency, respectively, in the case of no coupling. When , At that time, Birdturu Figure 3 As shown.

[0039] Advanced steps:

[0040]

[0041] The left corner frequency of the leading element is expressed in Hz. The right-hand corner frequency is expressed in Hz. A lead element can improve the phase of high-frequency components without changing the low-frequency gain, but it will increase the gain of high-frequency components, leading to a decrease in the system's gain margin. , At that time, the controller Bode diagram is as follows Figure 4 As shown.

[0042] The hysteresis element is equivalent to a PI controller with a gain of 1.

[0043]

[0044] The corner frequency of the hysteresis circuit is expressed in Hz. The hysteresis circuit can improve the low-frequency gain without changing the high-frequency gain, but it will reduce the phase, resulting in a decrease in the system's phase margin. The larger the value, the greater the effect of the lag mechanism. The smaller the value, the smaller the lag effect. When At that time, the controller Bode diagram is as follows Figure 5 As shown.

[0045] PI + lead-lag controller:

[0046]

[0047] in, , , , , Bode diagram of time as shown Figure 6 As shown.

[0048] When debugging actual system parameters, you can first adjust the PI to make the system meet a certain amplitude crossover frequency and phase margin. Then, adjust the lead element to increase the phase margin and check the amplitude margin. Next, adjust the lag element to increase the low-frequency gain, while the phase margin will decrease. Finally, fine-tune each element to make the system have sufficient phase margin, amplitude margin, low-frequency gain, and a suitable amplitude crossover frequency.

[0049] It should be noted that the servo control of the UAV-borne intelligent gun aiming system adopts a PI+lead-lag self-tuning algorithm. By adjusting the parameters, the system has sufficient stability margin and pass-through frequency to meet the system's rapid response requirements.

[0050] Through the embodiments of this disclosure, a proportional-integral (PI) plus lead-lag self-tuning control algorithm is adopted by the servo controller. The parameters of the PI, lead, and lag components are tuned layer by layer with crossover frequency and phase margin as constraints, and fine-tuned together until all four indicators meet the requirements. Since the lead component raises the phase in the mid-to-high frequency band, it enhances the controller's ability to predict and respond to rapid disturbances. The lag component increases the gain in the low frequency band, providing the high torque driving capability required to counteract recoil impacts. This solves the contradiction between insufficient response speed and insufficient driving torque faced by conventional PI control under recoil impacts, and achieves fast and stable tracking of the system while simultaneously meeting the preset requirements in terms of phase margin, gain margin, low-frequency gain, and crossover frequency.

[0051] Based on the above embodiments, when driving the azimuth motor and pitch motor, a high-frequency suppression step for the speed feedback signal is also included: a first-order inertial filter module is connected in series in the speed feedback signal path of the speed loop controller, the cutoff frequency is determined by identifying the system frequency characteristics, and high-frequency disturbances above the cutoff frequency are filtered and suppressed; a notch filter module is connected in series in the speed feedback signal path, the notch filter center frequency is set as the system resonant frequency, and frequency-selective suppression is performed on the amplitude instability range at the resonant frequency.

[0052] like Figure 9 As shown, the speed loop response bandwidth is only about 15Hz, but the amplitude is unstable at the 110Hz resonant frequency point. The actual system will gradually oscillate, and the resonant element directly affects the improvement of the speed loop bandwidth and channel gain.

[0053] To suppress the 110Hz resonant point and improve the system's speed loop bandwidth and disturbance rejection capability, a notch filter is used to suppress this high-frequency resonant point. A notch filter is a classic filtering device used in control system design to suppress resonances at specific frequencies. The notch filter loop configuration used in this disclosure for the 110Hz resonant point is as follows:

[0054]

[0055] In the formula: It is the notch width. This is the center frequency of the notch filter, i.e., the center frequency of the resonance. This represents the notch depth factor (generally, a value <1 is used when a notch filter is applied). After adding a notch filter to the control loop, the open-loop Bode plot of the system velocity loop is as follows: Figure 10 As shown.

[0056] Through the embodiments of this disclosure, high-frequency disturbance suppression based on first-order inertial filtering effectively improves the stability of the UAV-borne intelligent gun aiming system. Using a notch filter to suppress specific high-frequency resonant points improves the system's response bandwidth and anti-high-frequency disturbance capability, laying the foundation for high-precision target locking, tracking, and firing. Since recoil impact simultaneously generates two different types of disturbances—broadband high-frequency mechanical vibration and structural resonance at a specific frequency—a single filtering method cannot address both. This solution solves the problem of controller output disorder and system self-oscillation caused by the simultaneous injection of broadband recoil disturbance and resonant signals into the velocity feedback loop. It achieves both broadband and frequency-selective purification of the recoil disturbance component in the velocity feedback signal, simultaneously improving the velocity loop response bandwidth and anti-disturbance capability.

[0057] Based on the above embodiments, the cutoff frequency of the first-order inertial filter module is determined in the following way: the open-loop frequency characteristics of the gun aiming system are identified to obtain the actual Bode plot of the system; the main frequency range of high-frequency disturbances is identified based on the Bode plot, and the cutoff frequency is set at the starting frequency of the high-frequency disturbance range.

[0058] In this embodiment, when the intelligent gun aiming system is subjected to high-frequency disturbances, the stabilization loop cannot respond quickly to these disturbances, causing the line of sight to jitter. To improve the stability of the intelligent gun aiming system and enhance its anti-interference capability, a first-order inertial filtering algorithm is used to filter the high-frequency disturbances received by the system. The transfer function of the first-order inertial filter is:

[0059]

[0060] In the formula: , This is the cutoff frequency of the first-order inertial filter. Figure 8 The figure shows the open-loop Bode plot of a first-order inertial filter with a cutoff frequency of 100Hz. It can be seen that at the cutoff frequency, the system amplitude is reduced, and the system no longer responds to high-frequency information, but this is accompanied by phase lag. In a practical system, the system model is first obtained through model identification, and the cutoff frequency of the first-order inertial filter is determined based on the Bode plot of the actual system.

[0061] To address high-frequency disturbances at a specific high-frequency point, a notch filter is used to suppress them, thereby improving the system's response bandwidth and stability accuracy. Through the action of the notch filter connected in series with the speed loop controller, the amplitude margin is significantly reduced at the high-frequency resonant point, regaining a certain high-frequency amplitude margin. The channel gain of the speed loop is further improved, and the system's response bandwidth and anti-high-frequency disturbance capability can be optimized.

[0062] Through the embodiments of this disclosure, the actual Bode plot of the gun aiming system is obtained by identifying the open-loop frequency characteristics of the system. Based on the Bode plot, the main frequency range of high-frequency disturbances is identified, and the cutoff frequency of the first-order inertial filter is set at the starting frequency of the range. This achieves a balance between maximizing the attenuation energy of high-frequency recoil disturbances and minimizing the loss of tracking control bandwidth.

[0063] Based on the above embodiments, the attitude angle information and servo angle information are fused into coordinates to predict the servo azimuth and servo pitch angles that the aiming system should point to after firing. This includes: constructing an attitude rotation matrix from the UAV coordinate system to the geographic coordinate system using the current azimuth, pitch, and roll angles of the UAV; constructing a pointing transformation matrix from the aiming system coordinate system to the UAV coordinate system using the current servo azimuth and servo pitch angles of the aiming system; and using the attitude rotation matrix and the pointing transformation matrix, performing coordinate transformation on the position information of the target in the geographic coordinate system before firing, and calculating the servo azimuth and servo pitch angles that the aiming system should point to after firing to re-aime at the target.

[0064] Furthermore, Figure 11 This diagram illustrates a flowchart of a gun aiming system for tracking, firing, and angle adjustment according to an embodiment of the present disclosure. Applied to the aforementioned UAV-borne gun aiming system, when firing at a target, the recoil of the weapon affects the UAV's attitude and the gun aiming system's servo, making target tracking easily lost. This results in the weapon being unable to automatically re-find the target and fire again after firing. To solve this problem, a fusion algorithm based on the UAV's attitude and the gun aiming system's servo angle is designed to predict the servo angle in real time. During firing, the gun aiming system experiences pitch-up motion due to recoil. Based on the real-time predicted servo angle, the gun aiming system quickly adjusts back to the firing angle position, re-tracks the target, and then fires again.

[0065] The coordinate transformations and angle calculations involved specifically include:

[0066] During flight, the attitude of the drone changes from orientation to position. , up and down , roll This indicates that when all three axis attitude angles are zero, the UAV coordinate system... With geographic coordinate system They completely overlap. When the three-axis attitude angles are not zero, the transformation relationship between them can be calculated using the attitude angle rotation matrix. This indicates the transformation from the UAV coordinate system to the geographic coordinate system. Note: express , express .

[0067]

[0068] The UAV-borne intelligent gun aiming system consists of azimuth angle and pitch angle Indicates that when azimuth and elevation are zero, the gun aiming system coordinate system... The coordinate system coincides with that of the drone. The transformation matrix between the two systems is determined after the gun sight system rotates. for:

[0069]

[0070] By transforming the drone's attitude angle and the gun aiming system's servo angle, the target's servo azimuth and pitch angle in the gun aiming system's coordinate system can be predicted in real time. After losing the target, the servo quickly responds to this angle value, retracks the target, and completes the re-firing.

[0071] The servo angle calculation formula is:

[0072]

[0073] System test and test results as follows Figures 12-13 As shown, the test results were as follows: 10 single shots were fired in the test, and 10 shots hit the target, with a hit rate of 100%.

[0074] Through the embodiments of this disclosure, an attitude rotation matrix from the UAV coordinate system to the geographic coordinate system is constructed using the UAV's real-time azimuth, pitch, and roll angles, and a pointing transformation matrix from the gun aiming coordinate system to the UAV coordinate system is constructed using the gun aiming servo azimuth and servo pitch angles. The known position of the target in the geographic coordinate system before firing is calculated into the servo angle that the gun aiming should point at after firing using the dual-matrix inverse transformation. Since the geographic coordinates of the target have been determined by the observation and aiming system before firing, the coordinate calculation is completed entirely based on the real-time data of the flight control and servo sensors without relying on the reacquisition of visual images. This solves the problem that the observation and aiming system cannot re-lock the target through image recognition due to recoil, and realizes predictive callback without relying on the visual feedback channel.

[0075] Based on the above embodiments, the gun aiming system is driven to re-point towards the target according to the predicted servo azimuth and servo pitch angles, including: after the firing command is issued, when the angular velocity disturbance caused by recoil exceeds a first preset threshold, the predicted servo azimuth and servo pitch angles are used as servo control commands to drive the azimuth motor and pitch motor to output compensation torque, so that the gun aiming system returns to the direction of the target; after the angular velocity disturbance of the gun aiming system is less than a second preset threshold, the observation and aiming system reconfirms the target lock status, and triggers the next firing command after confirming the lock.

[0076] Through the embodiments of this disclosure, the angular velocity signal is monitored in real time by the inertial measurement unit. When the recoil angular velocity disturbance is detected to exceed the first preset threshold, the predicted servo angle is immediately used as a control command to drive the torque motor to output the compensation torque to implement the callback. After the angular velocity disturbance drops below the second preset threshold and the system is confirmed to be stable, the observation and aiming system reconfirms the target lock status and triggers the next firing. This solves the problem of missing the target or firing accidentally when the system enters the aiming judgment prematurely before it is fully stable during the callback process.

[0077] Based on the same inventive concept, embodiments of this disclosure provide an unmanned aerial vehicle (UAV) mounted gun aiming system, including a two-axis servo stabilization assembly, an aiming system, and a firearm; wherein, the two-axis servo stabilization assembly includes a servo azimuth assembly and a servo pitch assembly, used to provide drive torque in the azimuth and pitch directions; the aiming system is fixedly mounted on the servo pitch assembly, used to lock onto and track targets; the firearm is fixedly mounted on the servo pitch assembly and located below the aiming system, with the firing axis of the firearm parallel to the aiming axis of the aiming system, used to engage targets locked by the aiming system according to the adjustment of the two-axis servo stabilization assembly.

[0078] Figure 2 A schematic diagram of a drone-borne gun aiming system according to an embodiment of the present disclosure is shown, such as... Figure 2 As shown, this is a typical two-axis, two-frame structure. The servo azimuth assembly includes an azimuth mount, azimuth outer frame, top cover, azimuth angle sensor mount, azimuth axis, azimuth motor, and azimuth angle sensor. The servo pitch assembly includes a pitch adapter plate, pitch U-frame, pitch axis, pitch motor components, pitch angle sensor components, and side covers. An observation and aiming system integrating a visible light camera, infrared detector, and laser rangefinder, along with the firearm, are mounted on the upper and lower parts of the pitch axis system, respectively. The azimuth and pitch servo motors drive the observation and aiming axis and the firearm to designated positions in space. To achieve precise target locking, tracking, and firing, the azimuth and pitch servo motors are brushless DC motors with high positional accuracy, high torque, fast response, strong overload capacity, and direct load drive capability.

[0079] It should be noted that the two axes of the sighting system and the firearm are set to be parallel. The system only needs a one-time calibration to determine the fixed deviation between the aiming line and the firing line. After that, when tracking the target, the servo system only needs to drive the platform to align the aiming line with the target, and the firing line will automatically point in the correct direction, simplifying real-time fire control calculations. Mounting the heavier firearm below the sighting system helps to lower the center of gravity and improve the servo system's ability to resist disturbances and maintain stability. At the same time, this top-bottom layout can prevent the vibration generated during firearm firing from directly interfering with or damaging the sighting sensor above. Finally, the sighting system and the firearm are installed as independent modules in parallel, which facilitates their respective disassembly and maintenance.

[0080] Through the embodiments of this disclosure, an observation and aiming device is mounted on a servo-stabilized platform of an unmanned aerial vehicle (UAV) gun aiming system. Based on the fusion of the UAV's attitude and the servo angle of the gun aiming system, the gun aiming system can quickly adjust to complete target tracking after firing and fire again under the influence of the gun's recoil. This achieves azimuth and pitch linkage functions and is mainly used in the fields of aircraft optoelectronic pod stabilization platforms and airborne gun aiming stabilization platforms.

[0081] Based on the above embodiments, a two-axis servo stabilization assembly includes: a servo azimuth assembly, which is connected to the servo pitch assembly via a pivot to form a two-axis stabilization platform, and includes at least an azimuth frame, an azimuth axis, an azimuth motor, and an azimuth angle sensor. The azimuth motor drives the azimuth frame to rotate around the azimuth axis via the azimuth axis, thereby providing azimuth driving torque; and a servo pitch assembly, which is rotatably mounted within the azimuth frame of the servo azimuth assembly via a pivot, and includes at least a pitch U-shaped frame, a pitch axis, a pitch motor, a pitch angle sensor, and an inertial measurement unit. The pitch motor drives the pitch U-shaped frame to rotate around the pitch axis via the pitch axis, thereby providing pitch driving torque.

[0082] Through the embodiments of this disclosure, by constructing a two-axis stable platform and using a brushless DC torque motor to directly drive the azimuth and pitch axes, the system can quickly respond to and compensate for recoil impacts, thus solving the technical problem that the severe angular disturbances caused by recoil cannot be quickly suppressed, leading to system instability.

[0083] Based on the above embodiments, the azimuth motor and the pitch motor are DC brushless torque motors.

[0084] The embodiments disclosed herein enhance the flexibility of UAV-borne intelligent gun aiming systems. By selecting DC brushless torque motors with high positioning accuracy, high torque, fast response, and strong overload capacity, the system achieves linkage of azimuth and pitch axes, ensuring all-round and multi-angle strikes.

[0085] Based on the above embodiments, the system also includes a servo controller, which is connected to the azimuth motor, pitch motor, azimuth angle sensor, pitch angle sensor and inertial measurement unit respectively, and communicates with the UAV flight control unit to control the movement of the servo azimuth component and the servo pitch component.

[0086] Through the embodiments of this disclosure, since recoil disturbance involves the rapid processing and coordination of multi-source information, the servo controller is used to fuse data from the UAV attitude angle and the gun aiming system servo angle to achieve centralized perception of recoil disturbance.

[0087] Figure 7 A block diagram of a stable loop servo control according to an embodiment of the present disclosure is schematically shown, such as Figure 7As shown, the servo controller includes a speed loop controller, a current loop controller, a PWM power amplifier module, and a current sensor. The speed loop controller receives speed commands and speed feedback signals from the inertial measurement unit at its input, and its output is connected to the input of the current loop controller to output current commands. The current loop controller's input is connected to the output of the speed loop controller and the signal output of the current sensor, and its output is connected to the input of the PWM power amplifier module to output motor control signals. The PWM power amplifier module's input is connected to the output of the current loop controller, and its output is connected to the azimuth or pitch motor to provide drive current. The current sensor's current detection terminal is connected in series in the power supply circuit of the azimuth or pitch motor, and its signal output is connected to the feedback input of the current loop controller to provide current feedback signals.

[0088] It should be noted that the above content refers to the stabilization circuit of the single-axis frame of the intelligent gun aiming system. The azimuth motor or pitch motor is controlled through the same stabilization circuit.

[0089] Through the embodiments of this disclosure, the line-of-sight stabilization of the intelligent gun aiming system mainly relies on the inertial gyroscope as a feedback quantity in the angular velocity loop to form a stabilizing loop. By constructing a speed and current dual closed-loop control architecture inside the servo controller and the connection relationship of each module, recoil disturbances are suppressed quickly and smoothly, providing a hardware control loop guarantee for achieving fast-response torque compensation to counteract recoil.

[0090] Based on the above embodiments, the servo controller further includes a first-order inertial filter module and a notch filter module; the first-order inertial filter module is connected in series in the speed feedback signal input terminal or the forward path of the speed loop controller; the notch filter module is connected in series in the speed feedback signal input terminal of the speed loop controller.

[0091] Based on the above embodiments, the servo azimuth assembly further includes an azimuth base, a top cover, and an azimuth angle sensor mount. The azimuth base serves as the mounting base for the servo azimuth assembly, and the azimuth outer frame is rotatably mounted on the azimuth base via an azimuth axis. The top cover is mounted on the top of the azimuth outer frame. The azimuth angle sensor mount is mounted on the azimuth outer frame or the azimuth base for fixedly mounting the azimuth angle sensor. The servo pitch assembly further includes a side cover and a pitch adapter plate. The side cover is mounted on the side of the pitch U-shaped frame. The pitch adapter plate is connected to the pitch U-shaped frame for mounting the observation and aiming system and firearms. The output shaft of the azimuth motor is directly connected to the azimuth axis via a coupling, and the output shaft of the pitch motor is directly connected to the pitch axis via a coupling.

[0092] The embodiments disclosed herein ensure the installation rigidity and stability of the observation, aiming, and striking unit during the process of withstanding and counteracting recoil.

[0093] Based on the above embodiments, the observation and aiming system includes at least a visible light camera, an infrared detector, and a laser rangefinder arranged on the same optical axis.

[0094] Through the embodiments of this disclosure, since recoil may cause the target to be temporarily lost, the alignment error and time delay caused by the need to fuse information from different optical axis sensors during target re-aiming are solved by using a visible light camera, infrared detector and laser rangefinder set on the same optical axis. This achieves complete synchronization of multispectral detection information in physical space, provides a unified observation benchmark for quickly and seamlessly re-acquiring the target after recoil disturbance, and supports the continuous strike process.

[0095] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A method for target tracking and firing using a UAV-mounted gun sight, characterized in that, include: The sighting system locks onto the target, and the two-axis servo stabilization component drives the sighting system to point the firearm's aiming line toward the target, and controls the firearm to fire at the target. During firing, the attitude angle information of the UAV and the servo angle information of the gun sight system are acquired in real time. The attitude angle information and the servo angle information are fused together to predict the servo azimuth angle and servo pitch angle that the gun sight system should point to after firing. After the recoil causes the aiming system to shift its position and lose the target, the aiming system is driven to point back at the target based on the predicted servo azimuth and servo pitch angles, and then re-tracks and locks onto the target to fire again.

2. The method according to claim 1, wherein, The sighting system that uses the gun aiming system to lock onto the target includes: The target is detected by multispectral detection using a visible light camera, an infrared detector and a laser rangefinder set on the same optical axis. The target position information obtained by each sensor in the same optical axis coordinate system is fused to obtain the unified position coordinates of the target in the gun aiming system coordinate system. The two-axis servo stabilization component is driven according to the unified position coordinates to align the gun firing axis with the target.

3. The method according to claim 1, wherein, The two-axis servo stabilization component drives the azimuth and pitch motors via a proportional-integral (PI) plus lead-lag self-tuning control algorithm through a servo controller, including: The proportional-integral control parameters are tuned with crossover frequency and phase margin as constraints. Adjust the parameters of the lead element to raise the phase in the mid-to-high frequency band; Adjust the hysteresis parameters to enhance the gain in the low-frequency band; The parameters of the proportional-integral control loop, the lead loop, and the lag loop are jointly fine-tuned to ensure that the system simultaneously meets the preset targets for phase margin, gain margin, low-frequency gain, and crossover frequency. The azimuth motor and pitch motor are driven by the tunable proportional-integral control parameters, lead parameters, and lag parameters.

4. The method according to claim 3, wherein, When driving the azimuth motor and pitch motor, a high-frequency suppression step for the speed feedback signal is also included: A first-order inertial filter module is connected in series in the speed feedback signal path of the speed loop controller. The cutoff frequency is determined by identifying the system frequency characteristics, and high-frequency disturbances above the cutoff frequency are filtered and suppressed. A notch filter module is connected in series in the speed feedback signal path, and the notch filter center frequency is set as the system resonant frequency to selectively suppress the amplitude instability range at the resonant frequency.

5. The method according to claim 4, wherein, The cutoff frequency of the first-order inertial filter module is determined in the following way: Open-loop frequency characteristics of the gun aiming system are identified to obtain the actual Bode plot of the system; Based on the Bode plot, the main frequency range of high-frequency disturbances is identified, and the cutoff frequency is set at the starting frequency of the high-frequency disturbance range.

6. The method according to claim 1, wherein, The attitude angle information and the servo angle information are fused together to predict the servo azimuth and servo elevation angles that the aiming system should point to after firing, including: Construct an attitude rotation matrix from the UAV coordinate system to the geographic coordinate system using the UAV's current azimuth, pitch, and roll angles; Construct a pointing transformation matrix from the gun aiming system coordinate system to the UAV coordinate system using the current servo azimuth and servo pitch angles of the gun aiming system; Using the attitude rotation matrix and pointing transformation matrix, the position information of the target in the geographic coordinate system before firing is transformed to calculate the servo azimuth and servo elevation angles that the gun sight system should point to in order to re-aime at the target after firing.

7. The method according to claim 6, wherein, The method of driving the gun aiming system to re-point at the target based on the predicted servo azimuth and servo elevation angles includes: After the firing command is issued, if the angular velocity disturbance caused by recoil exceeds the first preset threshold, the predicted servo azimuth angle and servo pitch angle are used as servo control commands to drive the azimuth motor and pitch motor to output compensation torque, so that the gun aiming system returns to the direction of the target. Once the angular velocity disturbance of the aiming system is less than the second preset threshold, the aiming system reconfirms the target lock status, and triggers the next firing command after the lock is confirmed.

8. A UAV-borne gun aiming system, characterized in that, This includes a two-axis servo stabilization system, a sighting system, and the firearm; among which, The two-axis servo stabilization assembly includes a servo azimuth assembly and a servo pitch assembly, used to provide drive torque in the azimuth and pitch directions. The servo azimuth assembly and the servo pitch assembly are connected via a pivot to form a two-axis stabilization platform, and include at least an azimuth frame, an azimuth axis, an azimuth motor, and an azimuth angle sensor. The azimuth motor drives the azimuth frame to rotate around the azimuth axis via the azimuth axis, used to provide drive torque in the azimuth direction. The servo pitch assembly is rotatably mounted within the azimuth frame of the servo azimuth assembly via the pivot, and includes at least a pitch U-shaped frame, a pitch axis, a pitch motor, a pitch angle sensor, and an inertial measurement unit. The pitch motor drives the pitch U-shaped frame to rotate around the pitch axis via the pitch axis, used to provide drive torque in the pitch direction. The observation and aiming system is fixedly installed on the servo pitch component and is used to lock onto and track the target; The firearm is fixedly mounted on the servo pitch assembly and located below the sighting system. The firing axis of the firearm is set parallel to the aiming axis of the sighting system, and is used to engage the target locked by the sighting system according to the adjustment of the two-axis servo stabilization assembly.

9. The system according to claim 8, wherein, The system also includes a servo controller, which is signal-connected to the azimuth motor, the pitch motor, the azimuth angle sensor, the pitch angle sensor and the inertial measurement unit, and is communicatively connected to the UAV flight control unit, for controlling the movement of the servo azimuth component and the servo pitch component; The servo controller includes a speed loop controller, a current loop controller, a PWM power amplifier module, and a current sensor, wherein: The speed loop controller has an input terminal for receiving speed commands and speed feedback signals from the inertial measurement unit, and an output terminal connected to the input terminal of the current loop controller for outputting current commands. The current loop controller has its input terminal connected to the output terminal of the speed loop controller and the signal output terminal of the current sensor, and its output terminal connected to the input terminal of the PWM power amplifier module for outputting motor control signals. The PWM power amplifier module has its input terminal connected to the output terminal of the current loop controller, and its output terminal connected to the azimuth motor or the pitch motor to provide drive current. The current sensor has its current detection end connected in series in the power supply circuit of the azimuth motor or the pitch motor, and its signal output end connected to the feedback input end of the current loop controller to provide a current feedback signal.

10. The system according to claim 9, wherein, The servo controller further includes a first-order inertial filter module and a notch filter module; the first-order inertial filter module is connected in series in the speed feedback signal input terminal or the forward path of the speed loop controller; the notch filter module is connected in series in the speed feedback signal input terminal of the speed loop controller.

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