A method for detecting and identifying the electrostatic field of moving targets

Abstract

The present invention provides a method for detecting and identifying the electrostatic field of a moving target, comprising the following steps: S1, detecting an electrostatic signal carried by the moving target and generating a corresponding electrostatic sensor signal, performing digital filtering and signal extraction on the electrostatic sensor signal to obtain second digital electrostatic sensor signals of multiple channels; S2, establishing a detector coordinate system with the detector as the origin, and calculating electric field intensity component signals of the target in the X, Y, and Z axis directions of the detector coordinate system based on the second digital electrostatic sensor signals of the multiple channels; S3, based on the relative speed between the detector and the target, performing digital filtering on the electric field intensity components respectively through filters corresponding to the relative speed; S4, performing low-frequency suppression signal compensation on the electric field intensity component signals after digital filtering; S5, smoothing the signal-compensated electric field intensity component signals based on time; and S6, calculating the azimuth of the target based on the electric field intensity component signals after the smoothing process in step S5.

Description

Technical Field

[0001] The present invention relates to the technical field of short-range detection of moving targets, and in particular to a method for detecting and identifying the electrostatic field of a moving target. Background Art

[0002] Any object that uses a motor or moves will inevitably be charged with static electricity. The static electricity field generated by a moving target is a useful source of information. Electrostatic detection acquires target information by detecting the static electricity field surrounding the target. This method of detecting moving targets has the following advantages over other detection methods such as radio or laser detection:

[0003] (1) Electrostatic detection technology is a passive detection technology and is not easily interfered with.

[0004] (2) Moving targets generate a large number of electrons due to air friction and other reasons. During the flight, charges will accumulate on the surface, and the generated electrostatic field can be easily detected.

[0005] (3) Compared with traditional detection technology, electrostatic detection technology has strong resistance to electromagnetic environment interference.

[0006] Therefore, there is an urgent need for a method for detecting and identifying electrostatic targets to meet the needs of short-range detection of moving targets. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for detecting and identifying the electrostatic field of a moving target, which can identify the position of the target relative to the detector by detecting the electrostatic signal carried by the moving target.

[0008] In order to achieve the above object, the present invention provides a method for detecting and identifying the electrostatic field of a moving target, comprising the steps of:

[0009] S1. Detecting an electrostatic signal carried by a moving target and generating an electrostatic sensor signal corresponding to the electrostatic signal; performing digital filtering and signal extraction on the electrostatic sensor signal to obtain second digital electrostatic sensor signals of multiple channels;

[0010] S2. Establishing a detector coordinate system with the detector as the origin; calculating the electric field intensity component signals of the target in the X, Y, and Z axis directions of the detector coordinate system based on the second digital electrostatic sensor signals of the multiple channels;

[0011] S3. Based on the relative speed between the detector and the target, digitally filter the electric field intensity component signals using filters corresponding to the relative speeds;

[0012] S4, compensating the low-frequency suppression signal for the electric field intensity component signal after digital filtering;

[0013] S5. Smoothing the electric field intensity component signal after signal compensation based on time;

[0014] S6. Calculate the azimuth angle of the target based on the electric field intensity component signal after the smoothing process in step S5.

[0015] Optionally, step S1 includes:

[0016] S11, the electrostatic sensor of the detector generates a corresponding electrostatic sensor signal based on the detected moving target; the electrostatic sensor signal is an analog signal; the electrostatic sensor signal is amplified, and the amplified electrostatic sensor signal is converted into a corresponding first digital electrostatic sensor signal;

[0017] S12, filtering out interference signals outside the passband in the first digital electrostatic sensor signal through a low-pass filter;

[0018] S13 . Perform signal extraction on the filtered first digital electrostatic sensor signal to obtain second digital electrostatic sensor signals of multiple channels.

[0019] Optionally, in step S1, the second digital electrostatic sensor signals of the first to eighth channels are obtained through the annular first electrostatic sensor and the second electrostatic sensor; the second digital electrostatic sensor signals of the first to eighth channels are respectively recorded as D11, D12, D13, D14, D21, D22, D23, and D24; the central axis of the first electrostatic sensor is parallel to the X-axis of the detector coordinate system, and the central axis of the second electrostatic sensor is parallel to the Y-axis of the detector coordinate system; along the circumferential direction of the first electrostatic sensor, the first electrostatic sensor is evenly divided into four sequentially distributed segments, and D11, D12, D13, and D14 correspond to the four segments respectively; along the circumferential direction of the second electrostatic sensor, the second electrostatic sensor is evenly divided into four sequentially distributed segments, and D21, D22, D23, and D24 correspond to the four segments respectively.

[0020] Optionally, in step S2, let Ex, Еy, and Еz be the electric field intensity component signals in the X, Y, and Z axis directions, respectively.

[0021] Еy=(D11-D13+D21-D23) / 2;

[0022] Еz=(D12-D14+D22-D24) / 2;

[0023] Ex=D11+D12+D13+D14-(D21+D22+D23+D24).

[0024] Optionally, in step S3, let V be the relative velocity between the detector and the target. When V > t1, the electric field intensity component signals in the X, Y, and Z axis directions are not filtered; when t2 < V ≤ t1, the electric field intensity component signals in the X, Y, and Z axis directions are filtered through a first filter, and the cut-off frequency of the first filter is f1; when V ≤ t2, the electric field intensity component signals in the X, Y, and Z axis directions are filtered through a second filter, and the cut-off frequency of the second filter is f2; t1 and t2 are set velocity values.

[0025] Optionally, step S4 includes:

[0026] S41. Filter Ei through a smoothing filter with a coefficient of 1, where Ei = Ex, Ey, Ez;

[0027] S42. Calculate Ei′ based on the relative velocity V between the detector and the target, where Ei′ is the compensation value of Ei; Ei′ = Ex′, Ey′, Ez′;

[0028] When V > t1, Ei′ = Floor(Ei / 2 );

[0029] When t2 < V ≤ t1, Ei′ = Floor(Ei / 2 9 );

[0030] When V ≤ t2, Ei′ = Floor(Ei / 2 8 );

[0031] Floor(·) represents the floor operation, and update Ei with E′i + Ei; to achieve compensation for the low-frequency suppression signal of Ei.

[0032] Optionally, step S5 includes:

[0033] S51. Calculate

[0034] where t represents time, and Ei″(t) = EX″(t), EY″(t), EZ″(t); EX″(t), EY″(t), and EZ″(t) respectively represent the electric field intensity component signals in the X, Y, and Z axis directions after smoothing at the current moment; < is the angle between the projection of the target on the YZ plane of the detector coordinate system and the positive direction of the Y axis; θ is the angle between the projection of the target on the XY plane of the detector coordinate system and the positive direction of the X axis.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1) The present invention processes and calculates based on multi-channel electrostatic sensor signals and has strong anti-interference capability.

[0042] 2) The electrostatic sensor signal (voltage signal) generated when the electrostatic sensor detects the target is proportional to the target's electric field strength signal. The present invention obtains the target's electric field strength component signal through equivalent calculation of the electrostatic sensor signal, thereby calculating the target's direction information.

[0043] 3) The present invention adopts an adaptive filtering processing method to digitally filter the electric field intensity component signal based on a filter corresponding to the relative velocity (the relative velocity between the moving target and the detector), thereby improving the accuracy of the system in calculating the target direction.

[0044] 4) The present invention compensates the electric field intensity component signal with a low-frequency suppression signal, thereby reducing the deviation caused by the electrostatic sensor signal during the amplification process and improving the target direction solution accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are one embodiment of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort:

[0046] Figure 1 Flowchart of the method for detecting and identifying the electrostatic field of a moving target according to the present invention;

[0047] Figure 2 This is a schematic diagram of the distribution of electrostatic sensors in an embodiment of the present invention;

[0048] Figure 3 is a schematic diagram of filtering an electric field intensity component signal based on the relative velocity between a target and a detector in an embodiment of the present invention;

[0049] Figure 4 This is a flow chart of performing low-frequency suppression signal compensation on an electric field intensity component signal in an embodiment of the present invention;

[0050] Figure 5 This is a schematic diagram of the principle of calculating the target azimuth angle in an embodiment of the present invention;

[0051] In the figure: 1. FIR filter, 2. FIR filter, 3. Smoothing filter. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] It will be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0054] It should also be understood that the terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0055] It should be further understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0056] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0057] In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0058] The present invention provides a method for detecting and identifying the electrostatic field of a moving target. Figure 1 As shown, it includes the following steps:

[0059] S1. The electrostatic sensor of the detector generates a corresponding electrostatic sensor signal based on the detected moving target; digitally filters and extracts the electrostatic sensor signal to obtain second digital electrostatic sensor signals of multiple channels;

[0060] Step S1 includes:

[0061] S11. Detect the electrostatic signal carried by the moving target and generate an electrostatic sensor signal corresponding to the electrostatic signal; the electrostatic sensor signal is generated by the electrostatic sensor on the detector and is an analog signal; the electrostatic sensor signal is amplified by an analog amplifier circuit, and the amplified electrostatic sensor signal is converted into a corresponding first digital electrostatic sensor signal by an ADC (Analog-to-Digital Converter).

[0062] S12: Filter out interference signals outside the passband in the first digital electrostatic sensor signal through a low-pass filter.

[0063] S13, extract the first digital electrostatic sensor signal after filtering to obtain the second digital electrostatic sensor signal of multiple channels. Figure 2 As shown, the second digital electrostatic sensor signals of the first to eighth channels are obtained through the annular first electrostatic sensor and the second electrostatic sensor; the second digital electrostatic sensor signals of the first to eighth channels are respectively recorded as D11, D12, D13, D14, D21, D22, D23, and D24; the central axis of the first electrostatic sensor is parallel to the X-axis of the detector coordinate system, and the central axis of the second electrostatic sensor is parallel to the Y-axis of the detector coordinate system; along the circumferential direction of the first electrostatic sensor, the first electrostatic sensor is evenly divided into four sequentially distributed segments, and D11, D12, D13, and D14 correspond to the four segments respectively; along the circumferential direction of the second electrostatic sensor, the second electrostatic sensor is evenly divided into four sequentially distributed segments, and D21, D22, D23, and D24 correspond to the four segments respectively.

[0064] S2. Establish a detector coordinate system with the detector as the origin; calculate the electric field intensity component signals of the target in the X, Y, and Z axis directions of the detector coordinate system based on the second digital electrostatic sensor signals of the multiple channels.

[0065] In this embodiment, the electric field intensity component signals in each direction are calculated based on the second digital electrostatic sensor signals of the first to eighth channels.

[0066] In an ideal uniform atmospheric environment, the calculation formula of the target electric field vector E is as follows:

[0067]

[0068] Let \(r\) be the distance between the observation point and the target, \(\sigma\) be the charge density of the target at the observation point, and \(\vec{r}\) n be the unit vector in the normal direction at the observation point, \(\varepsilon_0\) be the vacuum permittivity, \(\varepsilon\) be the relative permittivity of the medium around the target, and \(L\) be the maximum size of the target.

[0069] Assume that the point target moves parallel to the \(Ox\) axis of the detector coordinate system, and the origin of the detector coordinate system is taken as the moment \(t = 0\). The modulus of the electric field vector of the target and its components can be expressed as:

[0070]

[0071]

[0072]

[0073] where \(V_0\) is the relative velocity between the target and the detector, \(h\) is the closest distance between the target and the detector, \(\theta\) is the azimuth angle of the target, and \(q\) is the electric charge of the target.

[0074] Let \(E_x\), \(E_y\), and \(E_z\) be the electric field intensity component signals in the directions of the \(X\), \(Y\), and \(Z\) axes respectively. The electrostatic sensor signal (voltage signal) generated by the electrostatic sensor is proportional to the electric field intensity signal of the target (composed of \(E_x\), \(E_y\), and \(E_z\)). Therefore, the calculation formulas for \(E_x\), \(E_y\), and \(E_z\) are respectively:

[0075] \(E_y=(D_{11}-D_{13}+D_{21}-D_{23}) / 2\);

[0076] \(E_z=(D_{12}-D_{14}+D_{22}-D_{24}) / 2\);

[0077] \(E_x = D_{11}+D_{12}+D_{13}+D_{14}-(D_{21}+D_{22}+D_{23}+D_{24})\).

[0078] S3. Based on the relative velocity between the detector and the target, digital filtering is performed on the electric field intensity component signals respectively through the filters corresponding to the relative velocity.

[0079] As Figure 3 shown, let \(V\) be the relative velocity between the detector and the target. When \(V > t_1\), no filtering is performed on the electric field intensity component signals in the directions of the \(X\), \(Y\), and \(Z\) axes; when \(t_2 < V\leq t_1\), the electric field intensity component signals in the directions of the \(X\), \(Y\), and \(Z\) axes are filtered through the first filter 1, as Figure 5As shown, the cutoff frequency of the first filter 1 is f1. When V ≤ t2, the electric field intensity component signals in the X, Y, and Z axis directions are filtered by the second filter 2, and the cutoff frequency of the second filter 2 is f2. Where t1 and t2 are the set speed values. In this embodiment, the first filter 1 and the second filter 2 are both FIR filters.

[0080] S4, compensating the low-frequency suppression signal for the electric field intensity component signal after digital filtering;

[0081] like Figure 4 As shown, step S4 includes:

[0082] S41, filtering Ei by a smoothing filter 4 (also a low-pass filter) with a coefficient of 1, Ei = Ex, Ey, Ez;

[0083] S42. Calculate Ei′ based on the relative velocity V between the detector and the target, where Ei′ is the compensation value of Ei; Ei′=Ex′, Ey′, Ez′;

[0084] When V>t1, Ei′=Floor(Ei / 2 10 );

[0085] When t2 <V≤t1,Ei′=Floor(Ei / 2 9 );

[0086] When V≤t2, Ei′=Floor(Ei / 2 8 );

[0087] Floor(·) represents a floor operation, and E′i+Ei is used to update Ei, thereby compensating Ei for the low-frequency suppression signal.

[0088] S5. Smoothing the electric field intensity component signal after signal compensation based on time;

[0089] Optionally, step S5 includes:

[0090] S51, calculation

[0091] Where t represents time, Ei″(t)=EX″(t),EY″(t),EZ″(t); EX″(t), EY″(t), EZ″(t) represent the electric field intensity component signals in the X, Y, and Z axis directions after smoothing at the current moment, respectively;

[0092] S52. Update Ei(t) with Ei″(t).

[0093] S6. Calculate the azimuth angle of the target based on the electric field intensity component signal after the smoothing process in step S5.

[0094]

[0095]

[0096] like Figure 5 As shown, is the angle between the projection of the target on the YZ plane of the detector coordinate system and the positive direction of the Y axis; θ is the angle between the projection of the target on the XY plane of the detector coordinate system and the positive direction of the X axis.

[0097] The present invention processes and calculates based on a multi-channel second digital quantity electrostatic sensor signal, and has a strong anti-interference capability. The electrostatic sensor signal (voltage signal) generated when the electrostatic sensor detects a target is proportional to the target's electric field strength signal. The present invention obtains the target's electric field strength signal through equivalent calculation of the electrostatic sensor signal, thereby calculating the target's azimuth information. The present invention also adopts an adaptive filtering processing method, digitally filtering the electric field strength component signal based on a filter corresponding to the relative speed (the relative speed between the moving target and the detector), thereby improving the accuracy of the system in calculating the target's azimuth. The present invention also compensates the electric field strength component signal with a low-frequency suppression signal, reducing the deviation caused by the electrostatic sensor signal during the amplification process and improving the accuracy of the target azimuth solution.

[0098] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0099] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for detecting and identifying the electrostatic field of a moving target, characterized in that: Steps included: S1. Detect the electrostatic signal carried by a moving target to generate an electrostatic sensor signal corresponding to the electrostatic signal; perform digital filtering and signal decimation on the electrostatic sensor signal to obtain second digital electrostatic sensor signals of multiple channels; S2. Establish a detector coordinate system with the detector as the origin; Based on the second digital electrostatic sensor signals of the multiple channels, calculate the electric field intensity component signals of the target in the X, Y, and Z axis directions of the detector coordinate system; S3. Based on the relative velocity between the detector and the target, perform digital filtering on the electric field intensity component signals respectively through filters corresponding to the relative velocity; In step S3, let V be the relative velocity between the detector and the target. When V > t1, do not filter the electric field intensity component signals in the X, Y, and Z axis directions; when t2 < V ≤ t1, filter the electric field intensity component signals in the X, Y, and Z axis directions through a first filter, and the cut-off frequency of the first filter is f1; when V ≤ t2, filter the electric field intensity component signals in the X, Y, and Z axis directions through a second filter, and the cut-off frequency of the second filter is f2; t1 and t2 are set velocity values; S4. Compensate the low-frequency suppression signal for the digitally filtered electric field intensity component signals; Step S4 includes: S41. Filter Ei through a smoothing filter with a coefficient of 1, where Ei = Ex, Ey, Ez; S42. Based on the relative velocity V between the detector and the target, calculate Ei′, where Ei′ is the compensation value of Ei; Ei′ = Ex′, Ey′, Ez′; When V>t1, Ei′=Floor(Ei / 2 10 ); When t2 <V≤t1,Ei′=Floor(Ei / 2 9 ); When V≤t2, Ei′=Floor(Ei / 2 8 ); Floor(·) represents the floor operation, and update Ei with E′i + Ei; to achieve compensation for the low-frequency suppression signal of Ei; S5. Smooth the electric field intensity component signals after signal compensation based on time; S6. Calculate the azimuth angle of the target based on the electric field intensity component signals smoothed in step S5.

2. The method for detecting and identifying the electrostatic field of a moving target according to claim 1, wherein: Step S1 includes: S11. The electrostatic sensor of the detector generates a corresponding electrostatic sensor signal based on the detected moving target; the electrostatic sensor signal is an analog signal; amplify the electrostatic sensor signal and convert the amplified electrostatic sensor signal into a corresponding first digital electrostatic sensor signal; S12. Filter out the out-of-band interference signals in the first digital electrostatic sensor signal through a low-pass filter; S13. Perform signal decimation on the filtered first digital electrostatic sensor signal to obtain second digital electrostatic sensor signals of multiple channels.

3. The method for detecting and identifying the electrostatic field of a moving target according to claim 1, wherein: In step S1, the second digital electrostatic sensor signals of the first to eighth channels are obtained through the annular first electrostatic sensor and the second electrostatic sensor; the second digital electrostatic sensor signals of the first to eighth channels are respectively recorded as D11, D12, D13, D14, D21, D22, D23, and D24; the central axis of the first electrostatic sensor is parallel to the X-axis of the detector coordinate system, and the central axis of the second electrostatic sensor is parallel to the Y-axis of the detector coordinate system; along the circumferential direction of the first electrostatic sensor, the first electrostatic sensor is evenly divided into four sequentially distributed segments, and D11, D12, D13, and D14 correspond to the four segments in sequence; along the circumferential direction of the second electrostatic sensor, the second electrostatic sensor is evenly divided into four sequentially distributed segments, and D21, D22, D23, and D24 correspond to the four segments in sequence.

4. The method for detecting and identifying the electrostatic field of a moving target according to claim 3, wherein: In step S2, let Ex, Ey, and Ez be the electric field intensity component signals in the X, Y, and Z axis directions, respectively. Ey = (D11 - D13 + D21 - D23) / 2; Ez = (D12 - D14 + D22 - D24) / 2; Ex=D11+D12+D13+D14-(D21+D22+D23+D24).

5. The method for detecting and identifying the electrostatic field of a moving target according to claim 1, wherein: Step S5 includes: S51, calculation Where t represents time, Ei″(t)=EX″(t),EY″(t),EZ″(t); EX″(t), EY″(t), EZ″(t) represent the electric field intensity component signals in the X, Y, and Z axis directions after smoothing at the current moment, respectively; S52. Update Ei(t) with Ei″(t).

6. The method for detecting and identifying the electrostatic field of a moving target according to claim 1, wherein: Step S6 comprises: in, is the angle between the projection of the target on the YZ plane of the detector coordinate system and the positive direction of the Y axis; θ is the angle between the projection of the target on the XY plane of the detector coordinate system and the positive direction of the X axis.

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