Target positioning method and system based on interferometer direction finding

Abstract

The invention relates to the technical field of flight carrier positioning, and discloses a target positioning method and system based on interferometer direction finding, and the method comprises the steps: carrying out the direction finding of a flight carrier at first preset time intervals in a preset positioning time period, and storing the direction finding angle information to obtain a direction finding angle vector; performing least square fitting on the direction finding angle and the time to obtain a fitting curve function reflecting the relation between the direction finding angle and the time; drawing an error equation for the direction-finding angle vector and the fitting curve function, and finding a first positioning direction-finding angle corresponding to a minimum error value which is closest to the starting time and is greater than a positioning angle threshold value in a preset positioning time period, the second positioning direction finding angle corresponds to the minimum error value which is closest to the end time and is greater than the positioning angle threshold value; and performing cross positioning according to the first direction-finding angle for positioning and the second direction-finding angle for positioning to obtain a positioning point. The positioning precision is high, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of flight vehicle positioning, and in particular to a target positioning method based on interferometer direction finding and a system geometry antenna array interferometer. Background Art

[0002] Nowadays, electromagnetic technology is developing rapidly. In daily life, electromagnetic technology is everywhere, such as communication electromagnetic waves, electromagnetic receivers, electromagnetic interference, etc., which makes it possible to discover target radiation sources and study positioning systems in complex electromagnetic environments. In conventional positioning systems, multiple nodes are generally required for positioning, such as TDOA algorithms, or two-dimensional direction finding. The former has high multi-node costs, and the latter requires a suitable array area. On a flying carrier, the array area is very limited.

[0003] Therefore, there is an urgent need for a target positioning method and system based on interferometer direction finding to solve the above problems. Summary of the invention

[0004] Based on the above, the object of the present invention is to provide a target positioning method and system based on interferometer direction finding, which has high positioning accuracy and low cost.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A target positioning method based on interferometer direction finding, comprising:

[0007] During a preset positioning time period, the flying vehicle is directed at every first preset time, and the direction-finding angle information is stored to obtain a direction-finding angle vector;

[0008] The least square method is used to fit the direction finding angle and time, and a fitting curve function reflecting the relationship between the direction finding angle and time is obtained;

[0009] Subtract the direction finding angle vector from the fitting curve function to find the first direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold closest to the start time within the preset positioning time period, and the second direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold closest to the end time;

[0010] Cross-positioning is performed according to the first positioning direction-finding angle and the second positioning direction-finding angle to obtain a positioning point.

[0011] As a preferred solution of a target positioning method based on interferometer direction finding, least squares fitting of direction finding angle and time includes:

[0012] Take formula (1) as the objective function:

[0013]

[0014] Among them, y i is the direction finding angle vector; t is the time;

[0015] is the fitting curve function of the least squares method:

[0016]

[0017] By solving the parameters a, b, and c when E is minimum, we can obtain the fitting curve function reflecting the relationship between the direction finding angle and time.

[0018] As a preferred solution of a target positioning method based on interferometer direction finding, performing direction finding on a flying vehicle at first preset time intervals includes:

[0019] At first preset intervals, the phase difference of the longest baseline in the direction-finding antenna array on the flying vehicle is calculated by a virtual baseline method, and then sinα corresponding to the incident angle α of the electromagnetic wave signal is obtained according to the phase difference of the longest baseline;

[0020] Calculating the actual phase difference of each real baseline in the direction-finding antenna array by a staggered baseline method, and then solving the sinβ array corresponding to the incident angle β of the electromagnetic wave signal according to the actual phase difference of each real baseline;

[0021] Subtract sinα from all sinβ elements in the sinβ array to obtain an error array, find the minimum error through the index, and solve the incident angle β of the electromagnetic wave signal according to the sinβ element corresponding to the minimum error.

[0022] As a preferred solution of a target positioning method based on interferometer direction finding, performing direction finding on a flying vehicle at first preset time intervals further includes:

[0023] Performing N direction finding on the electromagnetic wave signal, calculating the incident angle α and the incident angle β by using the virtual baseline method and the staggered baseline method respectively in each direction finding;

[0024] The incident angle α and the incident angle β obtained by N calculations are subjected to fusion filtering to obtain the incident angle γ of the corrected electromagnetic wave signal, wherein the fusion filtering is calculated according to the following formula:

[0025]

[0026] Where N is the number of direction finding, N≥1; λ is the filter coefficient, which is obtained through expert experience;

[0027] The incident angle γ is the direction-finding angle obtained by performing direction-finding on the flying vehicle every first preset time.

[0028] As a preferred solution of a target positioning method based on interferometer direction finding, calculating the actual phase difference of each real baseline in the antenna array by a staggered baseline method includes the following steps:

[0029] Assume that the actual phase difference of the electromagnetic wave signal reaching a real baseline is:

[0030]

[0031] in, is the actual phase difference corresponding to the nth real baseline; τ is the incident wavelength of the electromagnetic wave signal; d n is the length corresponding to the nth real baseline; is the measured phase difference corresponding to the nth real baseline; k n is the fuzzy number corresponding to the nth real baseline; n is a positive integer greater than or equal to 1;

[0032] From formula (5), we can see that yes Remainders about 2π;

[0033] Combining equation (4) and equation (5), we get:

[0034]

[0035] set up where m1, m2, ..., m n Coprime, then m1d1=m2d2=…=m n d n ,,have

[0036]

[0037] From the above formula, we can set After rounding, it is modulo m n The remainder of

[0038] According to the remainder theorem, we can solve for X, then

[0039]

[0040] The actual phase difference of the electromagnetic wave signal reaching each real baseline is obtained by calculating the fuzzy number corresponding to each real baseline.

[0041] As a preferred solution of a target positioning method based on interferometer direction finding, jitter is taken into account when calculating the actual phase difference of each real baseline in the antenna array by the staggered baseline method. Assuming that the maximum error of the jitter is Δε, the residue combination of the measured phase difference corresponding to each real baseline is:

[0042]

[0043] Substituting equation (10) into equation (8), we get k nleft , k n , k nright ;

[0044] According to the obtained fuzzy numbers corresponding to each real baseline and the left and right error values ​​of each fuzzy number, the actual phase difference of the electromagnetic wave signal reaching each real baseline and the actual phase difference left error value and the actual phase difference right error value corresponding to each actual phase difference are calculated, and the n real baselines corresponding to the n real baselines are obtained. 3 actual phase difference combinations, each of the actual phase difference combinations includes n first phase differences corresponding to n real baselines, wherein each of the first phase differences is the actual phase difference, the actual phase difference left error value or the actual phase difference right error value.

[0045] As a preferred solution of a target positioning method based on interferometer direction finding, n real baselines corresponding to n are obtained by the staggered baseline method. 3 The actual phase difference combination also includes:

[0046] Taking the length of each real baseline as the X-axis and the first phase difference in each actual phase difference combination as the Y-axis, performing least squares fitting to obtain a linear relationship between each real baseline and the first phase difference in each actual phase difference combination;

[0047] Recalculate the second phase difference in each actual phase difference combination corresponding to each real baseline according to the linear relationship;

[0048] Each sinβ corresponding to the incident angle β of the electromagnetic wave signal is obtained by solving each second phase difference obtained by the recalculation, and is saved as a sinβ array. The sinβ array includes n 3 sinβ elements.

[0049] A target positioning system based on interferometer direction finding, comprising:

[0050] A direction finding module, used to find the direction of the flying vehicle at intervals of a first preset time within a preset positioning time period, and store the direction finding angle information to obtain a direction finding angle vector;

[0051] A fitting calculation module is used to perform least square fitting on the direction finding angle and time to obtain a fitting curve function reflecting the relationship between the direction finding angle and time;

[0052] An optimization module is used to make an error equation for the direction finding angle vector and the fitting curve function, and find the first direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold closest to the start time within a preset positioning time period, and the second direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold closest to the end time;

[0053] The positioning module is used to perform cross positioning according to the first positioning direction finding angle and the second positioning direction finding angle to obtain a positioning point.

[0054] As a preferred solution of a target positioning system based on interferometer direction finding, the direction finding module includes:

[0055] A first calculation module is used to calculate the phase difference of the longest baseline in the antenna array by a virtual baseline method, and then solve sinα corresponding to the incident angle α of the electromagnetic wave signal according to the phase difference of the longest baseline;

[0056] A second calculation module is used to calculate the actual phase difference of each real baseline in the antenna array by using a staggered baseline method, and then solve the sinβ array corresponding to the incident angle β of the electromagnetic wave signal according to the actual phase difference of each real baseline;

[0057] The third calculation module is used to subtract sinα from all sinβ elements in the sinβ array to obtain an error array, find the minimum error through indexing, and solve the incident angle β of the electromagnetic wave signal according to the sinβ element corresponding to the minimum error.

[0058] As a preferred solution of a target positioning system based on interferometer direction finding, the direction finding module further includes:

[0059] The fusion filter calculation module is used to perform fusion filtering on the incident angle α and the incident angle β obtained by N times of calculation, and calculate the incident angle γ of the corrected electromagnetic wave signal.

[0060] The beneficial effects of the present invention are:

[0061] The present invention provides a target positioning method based on interferometer direction finding, which is beneficial to saving costs and array area by performing direction finding on a flying vehicle at each first preset time within a preset positioning time period; then a fitting curve function is obtained by fitting through the least squares method, and finally the first positioning direction finding angle and the second positioning direction finding angle with the longest interval are found, and cross-positioning is performed to obtain the final positioning point of the flying vehicle, with small positioning error and high positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0063] Figure 1 The process of the target positioning method based on interferometer direction finding provided by the embodiment of the present invention is Figure 1 ;

[0064] Figure 2 is an algorithm flow chart of a target positioning method based on interferometer direction finding provided by an embodiment of the present invention;

[0065] Figure 3 1 is a schematic diagram of least squares method fitting direction finding angle provided by an embodiment of the present invention;

[0066] Figure 4 is a flow chart of a direction finding method provided by an embodiment of the present invention;

[0067] Figure 5 is an antenna array distribution diagram provided by an embodiment of the present invention;

[0068] Figure 6 It is a schematic diagram of the structure of an antenna array provided by an embodiment of the present invention loaded on a flying vehicle.

[0069] In the figure:

[0070] 1. Flying carrier. DETAILED DESCRIPTION

[0071] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0072] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] like Figures 1 to 6As shown, the present invention provides a target positioning method based on interferometer direction finding, which specifically includes the following steps:

[0074] S100: performing direction finding on the flying vehicle at intervals of a first preset time within a preset positioning time period, and storing direction finding angle information to obtain a direction finding angle vector;

[0075] In this embodiment, it is assumed that within the preset positioning time period, the flying carrier flies in a straight line at a uniform speed, for example, the flying carrier continues to fly in a straight line at a speed of 200 km / h, and the target radiation source is within an angle of -45° to +45°. Exemplarily, the preset positioning time period is, for example, 120 seconds, and the first preset time is 1 second, that is, a direction finding angle is obtained by performing a direction finding operation every 1 second within 120 seconds. Of course, in other embodiments, the preset positioning time period and the first preset time may also be other, for example, the preset positioning time period is, for example, 110 seconds, 130 seconds, etc., and the first preset time is 1 second, 2 seconds, etc., which are specifically set according to actual needs.

[0076] In this embodiment, before starting positioning, the flying vehicle is first initially oriented and directed. The flying vehicle's orientation is adjusted according to the measured orientation so that the target radiation source is within an angle of -45° to +45°. The flying vehicle is then made to fly at a uniform speed and positioning is started. During positioning, the target radiation source is directionally measured and stored within a preset positioning time period.

[0077] Among them, flying vehicles include but are not limited to aircraft, drones, etc.

[0078] S200: performing least squares fitting on the direction finding angle and time to obtain a fitting curve function reflecting the relationship between the direction finding angle and time;

[0079] Preferably, after performing multiple direction finding within a preset positioning time period to obtain the direction finding angle vector, the direction finding angle vector is subjected to IIR filtering to improve subsequent calculation accuracy, thereby improving positioning accuracy. It should be noted that IIR filtering is a relatively mature prior art, and therefore, it will not be described in detail here.

[0080] Specifically, performing the least squares fitting on the direction finding angle and time includes:

[0081] Take formula (1) as the objective function:

[0082]

[0083] Among them, y i is the direction finding angle vector; t is the time;

[0084] is the fitting curve function of the least squares method:

[0085]

[0086] By solving the parameters a, b, and c when E is minimum, we can obtain the fitting curve function reflecting the relationship between the direction finding angle and time.

[0087] By introducing the objective function and using the least squares method to fit the curve of the direction finding angle changing with time, the sum of the squares of the difference between the measured value (the measured direction finding angle) and the theoretical value (the output value of the fitting curve function) is minimized, that is, the fitting object is infinitely close to the target object, the fitting effect is better, and the subsequent calculation accuracy can be effectively improved.

[0088] S300: Subtract the direction finding angle vector from the fitting curve function to find the first direction finding angle for positioning that corresponds to the minimum error value greater than the positioning angle threshold that is closest to the start time within the preset positioning time period, and the second direction finding angle for positioning that corresponds to the minimum error value greater than the positioning angle threshold that is closest to the end time; wherein the positioning angle threshold is, for example, 3°, 4°, etc., which is set according to actual needs.

[0089] Under the premise of error, the larger the cross positioning angle, the smaller the impact of the error. Figure 3 As shown, the fitting curve and the scatter plot of direction finding angles are obtained by the least square method. The direction finding angle for the first positioning is represented in the figure as the scatter point closest to the fitting curve and closest to the starting time, for example Figure 3 At point S in the figure, the second positioning direction finding angle is represented in the figure as the scattered point closest to the fitting curve and closest to the end time, for example Figure 3 The interval between point S and point P is the largest, so that the positioning point obtained by cross positioning using these two points in the subsequent process has a higher accuracy.

[0090] S400: Perform cross positioning according to the first positioning direction finding angle and the second positioning direction finding angle to obtain a positioning point.

[0091] After finding the first direction finding angle for positioning and the second direction finding angle for positioning, the direction finding rays of the two time nodes corresponding to the first direction finding angle for positioning and the second direction finding angle for positioning are intersected, and the intersection point is the positioning point.

[0092] Furthermore, if Figures 4 to 6 As shown, in step S100, the direction finding is performed using the following direction finding method, which specifically includes the following steps:

[0093] S101: Calculate the phase difference of the longest baseline in the antenna array by using a virtual baseline method, and then solve the sinα corresponding to the incident angle α of the electromagnetic wave signal according to the phase difference of the longest baseline;

[0094] More specifically, in step S101, the following steps are specifically included:

[0095] S1011: several virtual baselines are set in the real baseline array so that the shortest virtual baseline length is less than half the wavelength of the highest frequency of the broadband signal; wherein, the setting of the virtual baseline is a relatively mature prior art, and therefore, it is not described here one by one. The lengths of the real baselines and virtual baselines are known, and are set to be D1, D2, ..., D n .

[0096] S1012: Due to:

[0097]

[0098] The phase difference of the shortest virtual baseline is obtained according to the following formula:

[0099]

[0100] in, is the phase difference of the shortest virtual baseline, The corresponding measured phase difference of the shortest virtual baseline;

[0101] S1013: Obtaining the phase difference of the second shortest baseline according to the phase difference of the shortest virtual baseline; specifically comprising the following steps:

[0102] The rough value of the phase difference of the second shortest baseline is calculated by the following formula:

[0103]

[0104] because

[0105]

[0106] in, is the phase difference of the second shortest baseline, The corresponding measured phase difference of the second shortest baseline;

[0107] Find the index with The closest The corresponding k 2虚 , the exact value of the phase difference of the second shortest baseline can be obtained.

[0108] S1014: Calculate the phase difference of the third shortest baseline according to the phase difference of the second shortest baseline, and so on to calculate the phase difference of the longest baseline.

[0109] S1015: Substitute the phase difference of the longest baseline into equation (101) to obtain sinα corresponding to the incident angle α of the electromagnetic wave signal.

[0110] S102: Calculate the actual phase difference of each real baseline in the antenna array by using the staggered baseline method, and then solve the sinβ array corresponding to the incident angle β of the electromagnetic wave signal according to the actual phase difference of each real baseline;

[0111] Specifically, calculating the actual phase difference of each real baseline in the antenna array by the staggered baseline method includes the following steps:

[0112] S1021: Assume that the actual phase difference of the electromagnetic wave signal reaching a real baseline is:

[0113]

[0114] in, is the actual phase difference corresponding to the nth real baseline; τ is the incident wavelength of the electromagnetic wave signal; d n is the length corresponding to the nth real baseline; is the measured phase difference corresponding to the nth real baseline; k n is the fuzzy number corresponding to the nth real baseline; n is a positive integer greater than or equal to 1;

[0115] From formula (5), we can see that yes Remainders about 2π;

[0116] Combining equation (4) and equation (5), we get:

[0117]

[0118] set up where m1, m2, ..., m n Coprime, then m1d1=m2d2=…=m n d n ,,have

[0119]

[0120]

[0121] From the above formula, we can set After rounding, it is modulo m n The remainder of

[0122] According to the remainder theorem, we can solve for X, then

[0123]

[0124] The actual phase difference of the electromagnetic wave signal reaching each real baseline is obtained by calculating the fuzzy number corresponding to each real baseline.

[0125] Preferably, jitter is taken into account when calculating the actual phase difference of each real baseline in the antenna array by the staggered baseline method. Assuming that the maximum error of the jitter is Δε, the residue combination of the measured phase difference corresponding to each real baseline is:

[0126]

[0127] Substituting equation (10) into equation (8), we get k nleft , k n , k nright ;

[0128] According to the obtained fuzzy numbers corresponding to each real baseline and the left and right error values ​​of each fuzzy number, the actual phase difference of the electromagnetic wave signal reaching each real baseline and the actual phase difference left error value and the actual phase difference right error value corresponding to each actual phase difference are calculated, and the n real baselines corresponding to the n real baselines are obtained. 3 actual phase difference combinations, each of the actual phase difference combinations includes n first phase differences corresponding to n real baselines, wherein each of the first phase differences is the actual phase difference, the actual phase difference left error value or the actual phase difference right error value.

[0129] S1022: Obtain n real baselines corresponding to n real baselines by using the staggered baseline method 3 The actual phase difference combination also includes:

[0130] The length of each real baseline is taken as the X-axis, and the first phase difference in each actual phase difference combination is taken as the Y-axis, and the least squares fitting is performed to obtain the linear relationship between each real baseline and the first phase difference in each actual phase difference combination;

[0131] Recalculate the second phase difference in each actual phase difference combination corresponding to each real baseline according to the linear relationship;

[0132] According to each second phase difference obtained by recalculation, each sinβ corresponding to the incident angle β of the electromagnetic wave signal is solved and saved as a sinβ array. The sinβ array includes n 3 sinβ elements.

[0133] S103: Subtract sinα from all sinβ elements in the sinβ array to obtain an error array, find the minimum error through the index, and solve the incident angle β of the electromagnetic wave signal according to the sinβ element corresponding to the minimum error.

[0134] After the sinβ array is obtained, step S1023 is performed. In this embodiment, n 3Subtract sinα from each sinβ element to get the error array, then find the minimum error through the index, and determine the sinβ[Index] closest to sinα based on the minimum error. Then, the incident angle β of the electromagnetic wave signal can be solved based on sinβ[Index].

[0135] The sinα corresponding to the incident angle α of the electromagnetic wave signal is obtained through the virtual baseline method, and then the sinβ array corresponding to the incident angle β of the electromagnetic wave signal is obtained through the staggered baseline method. Finally, the sinβ closest to sinα can be found through the index. The incident angle β of the electromagnetic wave signal can be obtained based on the found sinβ. The obtained incident angle of the electromagnetic wave signal is more accurate and faster.

[0136] In order to further improve the accuracy of the incident angle of the electromagnetic wave signal, the direction finding of the flying vehicle at every first preset time further includes:

[0137] S1041: performing N direction finding on the electromagnetic wave signal, and calculating the incident angle α and the incident angle β by using the virtual baseline method and the staggered baseline method respectively for each direction finding;

[0138] S1042: Perform fusion filtering on the incident angle α and the incident angle β obtained by N calculations to obtain the incident angle γ of the corrected electromagnetic wave signal, wherein the fusion filtering is calculated according to the following formula:

[0139]

[0140] Wherein, N is the number of direction finding times, N≥1; λ is the filter coefficient, which is obtained through expert experience.

[0141] The direction finding method provided by this embodiment can effectively solve the technical problems of limited accuracy and direction finding ambiguity in the prior art, integrate the advantages of the virtual baseline method and the staggered baseline method, take advantage of each other's strengths and overcome their weaknesses, increase the anti-interference ability under noisy conditions, and achieve high sensitivity, high accuracy and high speed in direction finding, thereby achieving accurate target positioning, and can be used in scenarios such as conventional target positioning.

[0142] The above steps are further described below in conjunction with embodiments:

[0143] like Figure 4 and Figure 5 As shown in the figure, based on the conventional measurement frequency range and the size of the loaded antenna, four real direction-finding antennas are arranged within the effective arrangement length of the missile body, namely E, F, G, and H, and two virtual antennas are set, namely A and B, where the length of each baseline is D BF , D AF , D EF , D EG , D EH .

[0144] According to steps S101-S103, the phase difference φ of each baseline is solved in sequence by the virtual baseline method. BF虚 ,φ AF虚 ,φ EF虚 ,φ EG虚 ,φ EH虚 , so according to the phase difference φ corresponding to the longest baseline EH虚 Obtain sinα corresponding to the incident angle α of the electromagnetic wave signal.

[0145] When the actual phase difference of each real baseline in the antenna array is calculated by the staggered baseline method, d1 = D EF d2=D EG d3=D EH ;

[0146] According to step S102, the fuzzy number corresponding to each real baseline is obtained, and the actual phase difference φ of the electromagnetic wave signal reaching each real baseline is calculated. EF ,φ EG ,φ EH If jitter is taken into account, the error value φ of each actual phase difference is calculated. EFleft ; φ EFright ,φ EGleft ,φ EGright ,φ EHleft ,φ EHright . Then we can get 27 actual phase difference combinations corresponding to each real baseline: {φ EF ,φ EG ,φ EH}、{φ EFleft ,φ EG ,φ EH}、{φ EFright ,φ EG ,φ EH}、{φ EF ,φ EGleft ,φ EH}、{φ EF ,φ EGright ,φ EH}、{φ EF ,φ EG ,φ EHleft}、{φ EF ,φ EG ,φ EHright}、{φ EFleft ,φ EGleft ,φ EH}、{φ EFleft ,φ EGright ,φ EH}、{φ EFright ,φ EGleft ,φ EH}、{φEFright ,φ EGright ,φ EH}、{φ EFleft ,φ EG ,φ EHleft}、{φ EFleft ,φ EG ,φ EHright}、{φ EGright ,φ EG ,φ EHleft}、{φ EGrightt ,φ EG ,φ EHright}、{φ EF ,φ EGleft ,φ EHleft}、{φ EF ,φ EGleft ,φ EHright}、{φ EF ,φ EGright ,φ EHleft}、{φ EF ,φ EGright ,φ EHright}、{φ EFleft ,φ EGleft ,φ EHleft}、{φ EFright ,φ EGleft ,φ EHleft}、{φ EFleft ,φ EGright ,φ EHleft}、{φ EFleft ,φ EGleft ,φ EHright}、{φ EFright ,φ EGright ,φ EHleft}、{φ EFright ,φ EGleft ,φ EHright}、{φ EFleft ,φ EGright ,φ EHright}、{φ EFright ,φ EGright ,φ EHrigh};

[0147] Take d1, d2, and d3 as the X-axis, and the above 27 actual phase difference combinations as the Y-axis, respectively, and perform least squares fitting to obtain the linear relationship between each real baseline and the first phase difference in each corresponding actual phase difference combination; recalculate the second phase difference in each actual phase difference combination corresponding to each real baseline according to the linear relationship;

[0148] Then, 27 sinβs are obtained according to the re-determined second phase difference in each actual phase difference combination, and the 27 sinβs are saved as a sinβ array;

[0149] Subtract sinα from each sinβ element in the sinβ array to obtain an error array, then find the sinβ element corresponding to the minimum error through the index, and calculate the incident angle β of the electromagnetic wave signal based on the sinβ element closest to sinα.

[0150] Perform direction finding N times, that is, repeat the above steps, and finally perform fusion filtering on the incident angle α and the incident angle β calculated N times according to step S1042 to obtain the incident angle γ of the corrected electromagnetic wave signal.

[0151] The target positioning method based on interferometer direction finding in the present invention collects scattered points of direction finding angles during the flight of the flying vehicle, performs least squares filtering and fitting, selects the optimal point for multi-point cross positioning, and the final positioning error is less than 5%. At the same time, compared with the multi-node positioning and geometric antenna array interferometer two-dimensional direction finding in the prior art, the target positioning method based on interferometer direction finding provided in this embodiment can effectively save costs, and only needs to arrange a number of antennas, such as 4 antennas, on the flying vehicle, saving the array area, and is suitable for flying vehicles with limited array area.

[0152] The target positioning method based on interferometer direction finding provided in this embodiment is mainly applied in target positioning based on electromagnetic sensing platform. When the target is a signal radiation source, the target positioning method based on interferometer direction finding can well locate the specific longitude and latitude coordinates of the target radiation source.

[0153] The present embodiment also provides a target positioning system based on interferometer direction finding, which can be loaded on a flying vehicle. The target positioning system based on interferometer direction finding includes a direction finding module, a fitting calculation module, an optimization module and a positioning module. The direction finding module is used to perform direction finding on the flying vehicle at intervals of a first preset time within a preset positioning time period, and store the direction finding angle information to obtain a direction finding angle vector; the fitting calculation module is used to perform least squares fitting on the direction finding angle and time to obtain a fitting curve function that reflects the relationship between the direction finding angle and time; the optimization module is used to make an error equation for the direction finding angle vector and the fitting curve function, and find the first direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold that is closest to the start time within the preset positioning time period, and the second direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold that is closest to the end time; the positioning module is used to perform cross-positioning based on the first direction finding angle for positioning and the second direction finding angle for positioning to obtain a positioning point.

[0154] Specifically, the direction finding module system includes a first calculation module, a second calculation module and a third calculation module. The first calculation module is used to calculate the phase difference of the longest baseline in the antenna array by a virtual baseline method, and then solve the sinα corresponding to the incident angle α of the electromagnetic wave signal according to the phase difference of the longest baseline; the second calculation module is used to calculate the actual phase difference of each real baseline in the antenna array by a staggered baseline method, and then solve the sinβ array corresponding to the incident angle β of the electromagnetic wave signal according to the actual phase difference of each real baseline; the third calculation module is used to subtract sinα from all sinβ elements in the sinβ array to obtain an error array, and find the minimum error through the index, and solve the incident angle β of the electromagnetic wave signal according to the sinβ element corresponding to the minimum error.

[0155] In this embodiment, the direction finding module also includes a fusion filter calculation module, which is used to perform fusion filtering on the incident angle α and the incident angle β obtained by N times of calculation, and calculate the incident angle γ of the corrected electromagnetic wave signal. The incident angle of the electromagnetic wave signal can be accurately obtained at a high speed, and a more accurate direction finding angle can be provided for subsequent target positioning calculation, thereby improving positioning accuracy.

[0156] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A target positioning method based on interferometer direction finding, characterized in that: include: During a preset positioning time period, the flying vehicle is directed at every first preset time, and the direction-finding angle information is stored to obtain a direction-finding angle vector; The least square method is used to fit the direction finding angle and time, and a fitting curve function reflecting the relationship between the direction finding angle and time is obtained; Subtract the direction finding angle vector from the fitting curve function to find the first direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold closest to the start time within the preset positioning time period, and the second direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold closest to the end time; Cross-positioning is performed according to the first positioning direction-finding angle and the second positioning direction-finding angle to obtain a positioning point.

2. The target positioning method based on interferometer direction finding according to claim 1, characterized in that: The least squares fit of the direction finding angle and time includes: Take formula (1) as the objective function: Among them, y i is the direction finding angle vector; t is the time; is the fitting curve function of the least squares method: By solving the parameters a, b, and c when E is minimum, we can obtain the fitting curve function reflecting the relationship between the direction finding angle and time.

3. The target positioning method based on interferometer direction finding according to claim 1, characterized in that: The performing direction finding on the flying vehicle at every first preset time includes: At first preset intervals, the phase difference of the longest baseline in the direction-finding antenna array on the flying vehicle is calculated by a virtual baseline method, and then sinα corresponding to the incident angle α of the electromagnetic wave signal is obtained according to the phase difference of the longest baseline; Calculating the actual phase difference of each real baseline in the direction-finding antenna array by a staggered baseline method, and then solving the sinβ array corresponding to the incident angle β of the electromagnetic wave signal according to the actual phase difference of each real baseline; Subtract sinα from all sinβ elements in the sinβ array to obtain an error array, find the minimum error through the index, and solve the incident angle β of the electromagnetic wave signal according to the sinβ element corresponding to the minimum error.

4. The target positioning method based on interferometer direction finding according to claim 3, characterized in that: The step of performing direction finding on the flying vehicle at every first preset time period further comprises: Performing N direction finding on the electromagnetic wave signal, calculating the incident angle α and the incident angle β by using the virtual baseline method and the staggered baseline method respectively in each direction finding; The incident angle α and the incident angle β obtained by N calculations are subjected to fusion filtering to obtain the incident angle γ of the corrected electromagnetic wave signal, wherein the fusion filtering is calculated according to the following formula: Where N is the number of direction finding, N≥1; λ is the filter coefficient, which is obtained through expert experience; The incident angle γ is the direction-finding angle obtained by performing direction-finding on the flying vehicle every first preset time.

5. The target positioning method based on interferometer direction finding according to claim 4, characterized in that: Calculating the actual phase difference of each real baseline in the antenna array by the staggered baseline method includes the following steps: Assume that the actual phase difference of the electromagnetic wave signal reaching a real baseline is: in, is the actual phase difference corresponding to the nth real baseline; τ is the incident wavelength of the electromagnetic wave signal; d n is the length corresponding to the nth real baseline; is the measured phase difference corresponding to the nth real baseline; k n is the fuzzy number corresponding to the nth real baseline; n is a positive integer greater than or equal to 1; From formula (5), we can see that yes Remainders about 2π; Combining equation (4) and equation (5), we get: set up where m1, m2, ..., m n Coprime, then m1d1=m2d2=…=m n d n ,,have From the above formula, we can set After rounding, it is modulo m n The remainder of According to the remainder theorem, we can solve for X, then The actual phase difference of the electromagnetic wave signal reaching each real baseline is obtained by calculating the fuzzy number corresponding to each real baseline.

6. The target positioning method based on interferometer direction finding according to claim 5, characterized in that: When calculating the actual phase difference of each real baseline in the antenna array by the staggered baseline method, jitter is taken into account. Assuming that the maximum error of jitter is Δε, the residue combination of the measured phase difference corresponding to each real baseline is: Substituting equation (10) into equation (8), we get k nleft , k n , k nright ; According to the obtained fuzzy numbers corresponding to each real baseline and the left and right error values ​​of each fuzzy number, the actual phase difference of the electromagnetic wave signal reaching each real baseline and the actual phase difference left error value and the actual phase difference right error value corresponding to each actual phase difference are calculated, and the n real baselines corresponding to the n real baselines are obtained. 3 actual phase difference combinations, each of the actual phase difference combinations includes n first phase differences corresponding to n real baselines, wherein each of the first phase differences is the actual phase difference, the actual phase difference left error value or the actual phase difference right error value.

7. The target positioning method based on interferometer direction finding according to claim 6, characterized in that: The n real baselines corresponding to the n real baselines are obtained by the staggered baseline method. 3 The actual phase difference combination also includes: Taking the length of each real baseline as the X-axis and the first phase difference in each actual phase difference combination as the Y-axis, performing least squares fitting to obtain a linear relationship between each real baseline and the first phase difference in each actual phase difference combination; Recalculate the second phase difference in each actual phase difference combination corresponding to each real baseline according to the linear relationship; Each sinβ corresponding to the incident angle β of the electromagnetic wave signal is obtained by solving each second phase difference obtained by the recalculation, and is saved as a sinβ array. The sinβ array includes n 3 sinβ elements.

8. A target positioning system based on interferometer direction finding, characterized in that: include: A direction finding module, used to find the direction of the flying vehicle at intervals of a first preset time within a preset positioning time period, and store the direction finding angle information to obtain a direction finding angle vector; A fitting calculation module is used to perform least square fitting on the direction finding angle and time to obtain a fitting curve function reflecting the relationship between the direction finding angle and time; An optimization module is used to make an error equation for the direction finding angle vector and the fitting curve function, and find the first direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold closest to the start time within a preset positioning time period, and the second direction finding angle for positioning corresponding to the minimum error value greater than the positioning angle threshold closest to the end time; The positioning module is used to perform cross positioning according to the first positioning direction finding angle and the second positioning direction finding angle to obtain a positioning point.

9. The target positioning system based on interferometer direction finding according to claim 8, characterized in that: The direction finding module comprises: A first calculation module is used to calculate the phase difference of the longest baseline in the antenna array by a virtual baseline method, and then solve sinα corresponding to the incident angle α of the electromagnetic wave signal according to the phase difference of the longest baseline; A second calculation module is used to calculate the actual phase difference of each real baseline in the antenna array by using a staggered baseline method, and then solve the sinβ array corresponding to the incident angle β of the electromagnetic wave signal according to the actual phase difference of each real baseline; The third calculation module is used to subtract sinα from all sinβ elements in the sinβ array to obtain an error array, find the minimum error through indexing, and solve the incident angle β of the electromagnetic wave signal according to the sinβ element corresponding to the minimum error.

10. The target positioning system based on interferometer direction finding according to claim 9, characterized in that: The direction finding module also includes: The fusion filter calculation module is used to perform fusion filtering on the incident angle α and the incident angle β obtained by N times of calculation, and calculate the incident angle γ of the corrected electromagnetic wave signal.

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