Capacitive close-range target accurate detection method for small UAVs

Abstract

The present invention provides a method for accurately detecting capacitive close-range targets for small unmanned aerial vehicles (UAVs). The method features a capacitive detector's integrated electrode structure designed in conjunction with the UAV's body structure. Simulations are then used to optimize the structural layout. The detection performance of the capacitive detector in rainy and interfering environments is simulated, and a state-machine-based digital target recognition algorithm is employed to improve the anti-interference performance of close-range target detection in complex environments. This method addresses the issues of precise strike and reliable detonation control for small attack UAVs. The designed algorithm can accurately determine the distance to a target at close range, effectively improving the ability to control damage to the target.

Description

Technical Field

[0001] The present invention belongs to the field of precise detection, distance determination and detonation control when a small unmanned aerial vehicle attacks a target at close range. Specifically, it is a method for precise detection of capacitive close-range targets for a small unmanned aerial vehicle, involving quasi-electrostatic field capacitance detection and integrated electrode design and simulation, and a method for precise detection, distance determination and anti-interference of close-range targets. Background Art

[0002] With the growing adoption of unmanned combat, small attack drones hold great potential in modern warfare. Currently, small attack drones typically utilize human-in-the-loop control. Operators use video feeds from cameras to steer the drone toward its target, utilizing the impact force of impact to trigger the fire. Given the drone's small mass and low flight speed, the impact overload is minimal when impacting a target, especially a moving one. Setting the trigger switch sensitivity too high poses safety risks during flight. Sudden speed fluctuations and nutation during flight could lead to a potential mid-flight explosion. Setting the trigger switch sensitivity too low could lead to misfires due to the low impact overload when the drone impacts its target at a lower speed, reducing operational reliability. Therefore, using a trigger-activated mechanism for small drones presents a trade-off between safety and reliability. Furthermore, given that the targets are primarily human beings, this mechanism presents a problem of low destructive effectiveness. Therefore, it is not appropriate to use a trigger fuze type for this type of small UAV fuze. In view of the size and weight requirements of the small UAV, as well as the lethality of the warhead, it is more appropriate to control the detonation distance within the range of 10cm to 20cm. That is, the use of an ultra-close-range proximity control mode can better meet the fuze-war coordination requirements.

[0003] Existing short-range detection systems primarily rely on radio and laser detection. Their accuracy is high at low speeds, but errors are larger at higher speeds. Radio detection also exhibits poor immunity to electromagnetic interference, while laser detection performs poorly in rainy and snowy environments. Both are also relatively expensive. Capacitive detection offers advantages such as low cost, safety, reliability, and resistance to electromagnetic interference. Currently, capacitive detection is used as a proximity sensor in civilian applications, with distance accuracy in the millimeter range. However, it is primarily used in situations with relatively low relative speeds, typically less than 1 meter per second. In military applications, both in China and abroad, it primarily utilizes analog signal processing for close-range proximity control of high-speed, small- and medium-caliber ammunition. The blast height is generally controlled above 0.5 meters. However, proximity sensors do not meet the processing speed requirements of drones, which require a flight speed of 10 meters per second. Consequently, the range and accuracy of military proximity control systems fall short of the ultra-close-range detection and detonation control requirements of drones. Summary of the Invention

[0004] The purpose of the present invention is to achieve proximity detonation control when a small unmanned aerial vehicle attacks a target at close range and improve the damage effect. First, an integrated electrode structure of the capacitive detector is designed in combination with the UAV body structure. The optimized structural layout can be obtained through simulation methods. A detection performance simulation method of the capacitive detector in a rainy interference environment is also given. Then, a digital target recognition algorithm based on a state machine is designed to improve the anti-interference performance during close-range detection in complex environments.

[0005] The method of the present invention is achieved through the following technical solutions:

[0006] The method for accurately detecting capacitive close-range targets for small UAVs includes the following steps:

[0007] (1) Simulation of the structural layout of an integrated dual-electrode capacitive detector conforming to the UAV body;

[0008] (1.1) The capacitance detector adopts a dual-electrode capacitance detection system;

[0009] (1.2) Based on the structural characteristics of a small quadrotor drone, the electrode distribution is designed using space field simulation software. The capacitive detection electrode structure for a small quadrotor drone is modeled in COMSOL space field simulation software. Simulations of drone-target intersections are performed using the drone's rotor frame as the sensing electrode, the support base as the induction electrode, and the rotor frame as the sensing electrode, the support base as the induction electrode.

[0010] (1.3) Through the simulation of step (1.2), it can be respectively obtained that the change characteristics of the induced capacitance during the intersection process when the rotor frame is the sensing electrode and the support base is the sensing electrode, and the change characteristics of the induced capacitance during the radial intersection process when the rotor frame is the sensing electrode and the support base is the sensing electrode. By comparison, it is found that when the rotor frame is used as the sensing electrode, the change of the induced capacitance during the radial intersection process is stable and the change amplitude is large.

[0011] (1.4) For the capacitance detector electrode distribution structure selected in step (1.3), simulate the capacitance change characteristics when the UAV passes through a rain curtain. By designing a rain curtain environment at a certain distance from the target, Comsol simulates the capacitance change characteristics of the UAV's radial rendezvous process through the rain curtain.

[0012] (1.5) Use the target sensing capacitance change characteristics and rain curtain interference characteristics obtained in steps (1.3) and (1.4) during the rendezvous process as data for designing signal processing, target recognition and anti-interference methods.

[0013] (2) Digital target recognition, precise ranging, and anti-interference processing based on state machines;

[0014] (2.1) Through the spatial field simulation method, the intersection process and the interference passing through the rain curtain were simulated respectively, and the change law of the induction capacitance during the intersection process was obtained. This law was analyzed to obtain the signal characteristics of the interference object and design a filtering algorithm for the interference.

[0015] (2.2) Design a capacitance detection hardware system to perform A / D sampling of the detection voltage and the filtering process in step (2.1).

[0016] (2.3) Perform multi-state analysis on the filtered signal to accurately identify the target and determine the precise distance at close range. The presence of a target is determined by detecting the amplitude and amplitude change of the detected voltage after digital filtering. If the amplitude and amplitude change conditions are continuously met, the target is determined to be present. The detection voltage change rate is then calculated to accurately identify the target.

[0017] (2.4) If the signal in step (2.3) remains continuous and meets the preset rate of change threshold, the system starts the timer. If the timing reaches the preset duration and the detection voltage reaches the preset change amount, it is determined that the detonation ignition distance has been reached.

[0018] (2.5) If the detection signal meets the preset conditions in (2.4), the detonation ignition signal is output.

[0019] The technical effects of the technical solution of the present invention are as follows:

[0020] (1) Based on the structural characteristics of small quad-rotor UAVs, an integrated electrode structure for capacitive target detection is designed for UAVs. A simulation method is designed to obtain an electrode distribution scheme that is relatively more sensitive to changes in induced capacitance during intersection. Based on the electrode structure distribution, a UAV passing through a rain curtain model is simulated to obtain the changing characteristics of the induced capacitance when the UAV passes through the rain curtain.

[0021] (2) Aiming at the problem of precise strike and reliable detonation control of small attack UAV targets, the designed algorithm can accurately determine the distance to the target under close-range conditions, thereby effectively improving the strike and damage capability of the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A spatial model diagram of the UAV quad-rotor frame of the present invention configured as a sensing electrode and a supporting base configured as a sensing electrode;

[0023] Figure 2 This is a spatial model diagram of the UAV quad-rotor frame of the present invention as the sensing electrode and the supporting base as the sensing electrode;

[0024] Figure 3 The curve of the change of the induction capacitance during the radial intersection process when the outer frame of the quad-rotor of the UAV of the present invention is set as the induction electrode and the support base is set as the sensing electrode;

[0025] Figure 4 The curve of the change of the induction capacitance during the radial intersection process when the outer frame of the quad-rotor of the UAV of the present invention is the sensing electrode and the supporting base is the sensing electrode;

[0026] Figure 5 This is a spatial model diagram of the drone of the present invention passing through a rain curtain;

[0027] Figure 6 The comparison of the changes in the sensing capacitance when the UAV passes through a rain curtain and the sensing capacitance in a normal environment during the radial rendezvous process of the present invention is shown;

[0028] Figure 7 This is a structural block diagram of the system implementation of the present invention;

[0029] Figure 8 This is the state transition diagram of the target recognition algorithm of the present invention. DETAILED DESCRIPTION

[0030] The present invention designs a dual-electrode detection system based on the capacitance detection principle. The front-end detection electrode senses the target. When the target appears, the electrostatic field around the electrode is disturbed, causing the capacitance between the detection electrode and the rear-end inherent electrode to change, thereby causing the detection signal to change.

[0031] Through space field simulation software, a small quadrotor UAV is simulated and compared with the characteristics of the change of induced capacitance during the radial intersection of the rotor frame as the sensing electrode, the supporting base as the induction electrode, and the rotor frame as the sensing electrode and the supporting base as the sensing electrode. Through comparative analysis, it is found that the change of induced capacitance during the radial intersection of the rotor frame as the sensing electrode and the supporting base as the sensing electrode is more stable.

[0032] The missile-target rendezvous process under different interference environments was simulated and analyzed using space field simulation software, and the interference signal characteristics were obtained. According to the interference signal characteristics and the application background noise characteristics, a weighted sliding digital filtering algorithm and a target recognition algorithm based on a state machine were designed.

[0033] The specific technical solutions of the present invention are described with reference to the accompanying drawings.

[0034] The method for accurately detecting capacitive close-range targets for small UAVs includes the following steps:

[0035] (1) Simulation of the structural layout of an integrated dual-electrode capacitive detector that is compatible with the UAV;

[0036] (1.1) The capacitance detector adopts a dual-electrode capacitance detection structure;

[0037] (1.2) For small quad-rotor drones, the electrode distribution is designed based on the structural characteristics of the quad-rotor drone using space field simulation software. In COMSOL space field simulation software, the small quad-rotor drone is modeled, and the space medium is set to air, with a dielectric constant of 1, and the dielectric constant of the drone is set to ∞. The rotor frame of the drone is used as the sensing electrode, and the support base is used as the induction electrode. Figure 1 , and the rotor frame is the sensing electrode, the support base is the induction electrode, see Figure 2 , to conduct radial rendezvous simulation between UAV and target.

[0038] (1.3) Through the simulation of step (1.2), the variation characteristics of the induction capacitance during the radial intersection process of the rotor frame as the induction electrode and the support base as the induction electrode can be obtained. Figure 3 , and the rotor frame is the sensing electrode, the support base is the induction electrode during the radial intersection process of the induction capacitance, see Figure 4 By comparison, it is found that when the rotor outer frame is the inductive electrode, the induced capacitance changes in the radial intersection process are stable and the change amplitude is large.

[0039] (1.4) For the UAV electrode distribution structure selected in step (1.3), simulate the capacitance change characteristics when the UAV passes through the rain curtain. By designing a rain curtain environment at a certain distance from the target, see Figure 5 , the distance to the target is 50cm-70cm, the raindrop diameter is 0.3cm, and the rain curtain spacing is 3cm. The inductive capacitance change characteristics of the instantaneous rain curtain appearing during the radial rendezvous process of the UAV are simulated by Comsol. Figure 6 ;

[0040] (1.5) Use the target capacitance change characteristics and interference characteristics obtained in steps (1.3) and (1.4) during the intersection process as data for designing signal processing, target recognition and anti-interference methods.

[0041] (2) Digital target recognition, precise ranging, and anti-interference processing based on state machines;

[0042] (2.1) Through the spatial field simulation method, the intersection process and the interference passing through the rain curtain are simulated respectively, and the change law of the inductive capacitance in the intersection process is obtained. This law is analyzed to obtain the signal characteristics of the interference object and design a filtering algorithm for the interference.

[0043] (2.2) Design the capacitance detection hardware system, see Figure 7 , including an oscillation circuit, a detection circuit, an analog filtering circuit, a microprocessor control circuit, etc., to perform detection voltage A / D sampling and filtering processing in step (2.1) during the detection process.

[0044] (2.3) Perform multi-state analysis on the filtered signal to accurately identify the target and accurately determine the distance at close range. Figure 8 The presence of a target is determined by detecting the amplitude and amplitude change of the detection voltage after digital filtering. If the amplitude and amplitude change conditions are continuously met, the target is determined to exist, and the detection voltage change rate is calculated to accurately identify the target.

[0045] (2.4) If the signal in step (2.3) remains continuous and meets the preset rate of change threshold, the system starts the timer. If the timing reaches the preset duration and the detection voltage reaches the preset change amount, it is determined that the detonation distance has been reached.

[0046] (2.5) If the detection signal meets the preset conditions in (2.4), the detonation ignition signal is output, see Figure 8 , Table 1.

[0047] Table 1 Meaning of symbols in the state machine algorithm diagram

[0048]

[0049]

[0050] To improve the applicability and robustness of the capacitive detection system, a state machine algorithm based on multi-state analysis was designed. This algorithm defines the changing trends of the detection voltage during the missile-target rendezvous process as different states. By comprehensively analyzing the logical relationships between these states, it can determine whether a target exists and whether the attack range has been reached. This state machine-based target recognition algorithm primarily consists of five states: No Target (NT), Suspected Target (ST), Target Appear (TA), Certain Target (CT), and Attack Position (AP).

[0051] Combining the signal characteristics during the rendezvous process, the following target recognition criteria are designed:

[0052] 1) By Figure 8 As can be seen, when no target is present, the detection voltage tends to be a straight line, with minimal fluctuations. The microcontroller samples the detection voltage data in real time. When the detection voltage amplitude meets the start voltage, it begins calculating the detection voltage change. If the detection voltage change amplitude exceeds the set threshold, the detection system enters the "ST" state. If the detection voltage change amplitude does not meet the preset threshold, the detection system remains in the "NT" state.

[0053] 2) After the system enters "ST", it continues to detect the change in the detection voltage. When the change in the detection voltage is greater than the preset threshold for four consecutive times, the system enters the "TA" state, otherwise the detection system enters the "NT" state.

[0054] 3) When the system is in the "TA" state, it begins calculating the detection voltage change rate. This is obtained by performing a differential operation on the pre-processed signal data. When the detection voltage change rate exceeds the set threshold, the counting mode is activated. If the change rate meets the preset condition four times in a row, the detection system enters the "CT" state. Otherwise, the detection system enters the "ST" state.

[0055] 4) When the system enters the "CT" state, the detection system identifies the target as confirmed, and the signal processing module starts the timer. To accurately measure the explosion height, the signal processing module performs the following operations:

[0056] a) Calculate the change in detection voltage from time i to time k in the "CT" state to determine whether it reaches the reasonable explosion height control range. If the change in detection voltage during this period meets the preset conditions, the specified explosion height is reached and the detection system outputs an ignition signal at time k.

[0057] b) By combining the preset bullet velocity with timer information, the ammunition's flight distance is calculated, thereby controlling the impact position. When either of conditions a or b is met, the system enters the "AP" state. If the rate of change of the detector voltage is non-monotonic during this state, the detection system enters the "TA" state.

[0058] When the signal meets the preset conditions of detection voltage amplitude, detection voltage amplitude change, amplitude change rate and final time or detection voltage amplitude change in the state machine target recognition algorithm, the detonation control signal is started.

Claims

1. A capacitive close-range target precision detection method for small UAVs, characterized in that: First, the integrated electrode structure of the capacitive detector is designed based on the UAV's body structure. The optimized structural layout is obtained through simulation methods. A simulation method for the detection performance of the capacitive detector in a rainy interference environment is given. A digital target recognition algorithm based on a state machine is used to improve the anti-interference performance of close-range detection in complex environments. The following steps are involved: (1) Simulation of the structural layout of an integrated dual-electrode capacitive detector that is compatible with the UAV; (1.1) The capacitance detector adopts a dual-electrode capacitance detection system; (1.2) For a small quadrotor drone, the electrode distribution is designed based on its structural characteristics using space field simulation software. The small quadrotor drone is modeled in COMSOL space field simulation software, with the space medium set to air, the dielectric constant to 1, and the dielectric constant of the drone set to ∞. The radial rendezvous process between the drone and the target is simulated using the drone's rotor frame as the sensing electrode and the support base as the induction electrode, and the rotor frame as the sensing electrode and the support base as the induction electrode. (1.3) Through simulation in step (1.2), the variation characteristics of the induced capacitance during the radial intersection process when the rotor frame is the sensing electrode and the support base is the sensing electrode are obtained, as well as the variation characteristics of the induced capacitance during the radial intersection process when the rotor frame is the sensing electrode and the support base is the sensing electrode; (1.4) For the UAV electrode distribution structure selected in step (1.3), simulate the capacitance change characteristics when the UAV passes through a rain curtain. By designing a rain curtain environment at a certain distance from the target, use Comsol to simulate the capacitance change characteristics of the instantaneous rain curtain during the UAV radial rendezvous process. (1.5) Using the target capacitance change characteristics and interference characteristics obtained in steps (1.3) and (1.4) during the rendezvous process as data for designing signal processing, target recognition, and anti-interference methods; (2) Digital target recognition, precise ranging and anti-interference processing based on state machine (2.1) Using spatial field simulation methods, simulate the intersection process and the interference through the rain curtain. Determine the variation of the inductive capacitance during the intersection process, obtain the signal characteristics of the interference object, and design a filtering algorithm to address the interference. (2.2) Design a capacitance detection hardware system to perform A / D sampling of the detection voltage and the filtering process in step (2.1); (2.3) Perform multi-state analysis on the filtered signal. The detection voltage amplitude and amplitude change after digital filtering are detected to determine whether a target is present. If the amplitude and amplitude change conditions are continuously met, the target is determined to be present. The detection voltage change rate is calculated to accurately identify the target. (2.4) If the signal in step (2.3) remains continuous and meets the preset rate of change threshold, the system starts the timer. If the timer reaches the preset duration and the detection voltage reaches the preset change amount, it is determined that the detonation distance has been reached; (2.5) If the detection signal meets the preset conditions in (2.4), the detonation signal is output.

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