Target positioning method and device, RHS radar system, medium, equipment and product

Abstract

The invention discloses a target positioning method and device, an RHS radar system, a medium, equipment and a program product, and the method comprises the steps: carrying out the superposition of first frequency domain signals of beat frequency signals on different radio frequency chains in a distance dimension, obtaining a superposed signal, estimating a distance, and carrying out the superposition of the first frequency domain signals of the beat frequency signals in the distance dimension; the method comprises the following steps: acquiring a first frequency domain signal, performing phase error compensation on the first frequency domain signal according to an effective far and near field boundary, and then for each distance value in a distance estimation result, accurately estimating an angle region with a target on the distance value by using the compensated first frequency domain signal, thereby obtaining a distance estimation result according to each distance value and an angle estimation result on each distance value. Therefore, near-field and far-field multi-target positioning results can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of target positioning, and in particular, to a target positioning method, device, RHS radar system, medium, device and product. Background Art

[0002] With the rapid development of location-based application services such as autonomous driving, simultaneous localization and mapping, the demand for high-precision, low-power and low-cost positioning systems is increasing day by day. As a new type of radar antenna, the Reconfigurable Holographic Surface (RHS) can achieve amplitude control of each RHS unit on the antenna only by simple diode and microstrip line technologies. Therefore, it can replace the radar antenna using phased arrays and realize a large-scale antenna array with low power consumption and low cost.

[0003] Although the RHS provides a low-power and low-cost solution for large-scale radar antennas, the increase in antenna size leads to an expansion of the near-field range. For targets located both in the near field and in the far field, hybrid near-far field positioning needs to be studied. Summary of the Invention

[0004] The object of the present invention is to propose a target positioning method, device, RHS radar system, medium, device and program product for the deficiencies of the above-mentioned prior art, and this object is achieved by the following technical solutions.

[0005] The first aspect of the present invention proposes a target positioning method applied to an RHS radar system. The RHS radar system includes a receiving end and a transmitting end, and a plurality of radio frequency chains are formed between the receiving end and the transmitting end. The method includes:

[0006] Obtain a first frequency domain signal of the beat frequency signal of the receiving end on each radio frequency chain in the distance dimension;

[0007] Based on the superimposed signal of the first frequency domain signals of each radio frequency chain, determine a distance estimation result, where the distance estimation result includes at least one distance value;

[0008] Compensate the phase error of the first frequency domain signal according to the near-far field demarcation line;

[0009] For each distance value in the distance estimation result, use the compensated first frequency domain signal to determine an angle estimation result at the distance value, where the angle estimation result is used to represent an angular region where a target exists, and the angular region refers to a discrete angular region obtained by dividing the angle detection range of the RHS radar system;

[0010] Obtain the positioning result of at least one target based on the distance estimation result and the angle estimation result at each distance value in the distance estimation result.

[0011] The second aspect of the present invention proposes an RHS radar system, characterized in that the system includes a receiving end and a transmitting end;

[0012] The transmitting end includes a transmitting antenna and a transmitter. The transmitting antenna includes multiple rows of RHS units and multiple first feeds. Each row of RHS units is connected to one of the first feeds, and the transmitter is used to generate a transmission signal and feed it into each of the first feeds;

[0013] The receiving end includes a receiving antenna and a receiver. The receiving antenna includes multiple rows of RHS units and multiple second feeds. Each row of RHS units is connected to one of the second feeds. The receiver is used to receive the received signals transmitted by each of the second feeds, and generate beat signals on different radio frequency chains composed of the multiple first feeds and the multiple second feeds according to the transmission signal and the received signal. The receiver is also used to perform the steps of the target positioning method described in the first aspect.

[0014] The third aspect of the present invention proposes a target positioning device, which is applied to an RHS radar system. The RHS radar system includes a receiving end and a transmitting end, and multiple radio frequency chains are formed between the receiving end and the transmitting end. The device includes:

[0015] A first transformation module, configured to obtain a first frequency domain signal of the beat signal of the receiving end on each radio frequency chain in the distance dimension;

[0016] A distance estimation module, configured to determine a distance estimation result based on the superimposed signal of the first frequency domain signals of each radio frequency chain. The distance estimation result includes at least one distance value;

[0017] A compensation module, configured to compensate for the phase error of the first frequency domain signal according to the far-field and near-field demarcation line;

[0018] An angle estimation module, configured to, for each distance value in the distance estimation result, use the compensated first frequency domain signal to determine an angle estimation result at the distance value. The angle estimation result is used to represent the angular region where a target exists. The angular region refers to the discrete angular regions obtained by dividing the angle detection range of the RHS radar system;

[0019] A target positioning module, configured to obtain the positioning result of at least one target based on the distance estimation result and the angle estimation result at each distance value in the distance estimation result.

[0020] A fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes the program to implement the method as described in the first aspect.

[0021] A fifth aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored, and the program is executed by a processor to implement the method as described in the first aspect.

[0022] A sixth aspect of the present invention provides a computer program product, including a computer program, characterized in that the computer program is executed by a processor to implement the method as described in the first aspect.

[0023] Based on the above-mentioned target positioning method, device, RHS radar system, medium, device, and program product, the present invention has the following beneficial effects or advantages:

[0024] By superimposing the first frequency-domain signals of the beat frequency signals on different radio frequency chains in the distance dimension to obtain a superimposed signal for estimating the distance, compensating the phase error of the first frequency-domain signal according to the effective near-field and far-field demarcation line, and then for each distance value in the distance estimation result, accurately estimating the angular region where a target exists at this distance value by using the compensated first frequency-domain signal, so that according to each distance value and the angular estimation results at each distance value, multi-target positioning results of the near field and the far field can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present invention, form a part of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0026] Figure 1 It is a schematic diagram of an antenna based on RHS shown according to an exemplary embodiment of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of an RHS radar system shown according to an exemplary embodiment of the present invention;

[0028] Figure 3 It is a flowchart of an embodiment of a target positioning method shown according to an exemplary embodiment of the present invention;

[0029] Figures 4A - 4B It is a schematic diagram of the comparison of positioning errors between the present solution and other solutions shown according to an exemplary embodiment of the present invention;

[0030] Figure 5 It is a schematic diagram of the structure of a target positioning device shown according to an exemplary embodiment of the present invention;

[0031] Figure 6 Schematic diagram of the hardware structure of an electronic device according to an exemplary embodiment of the present invention;

[0032] Figure 7 Schematic diagram of the structure of a storage medium according to an exemplary embodiment of the present invention. Detailed implementation manners

[0033] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are merely examples of systems and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0034] The terms used in the present invention are for the purpose of describing particular embodiments only and are not intended to limit the present invention. The singular forms "a", "said", and "the" used in the present invention and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0035] It should be understood that although the terms first, second, third, etc. may be used in the present invention to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0036] The prior art mainly performs multi-target near-field and far-field positioning based on narrowband signals or broadband signals.

[0037] The positioning technology based on narrowband signals performs target positioning by analyzing the phase of the received signal. Due to its narrowband characteristics, such methods cannot estimate the distance of far-field targets, and the accuracy of the distance estimation of near-field targets decreases as the distance increases. The far-field positioning technology based on broadband signals cannot be applied to the near-field scenario due to the change of the channel model, while the near-field positioning technology based on broadband signals requires known distance information for error correction and cannot be applied to the mixed near-far-field scenario. Therefore, the positioning technology based on broadband signals is only applicable to far-field positioning or near-field positioning with known distance information.

[0038] It can be seen that there is a need to study a new scheme for joint distance and angle estimation in a mixed near-field and far-field scenario.

[0039] Based on this, the present invention proposes a target positioning method to achieve high-precision estimation of the distance and angle of near-field and far-field targets. By superimposing the first-frequency-domain signals of the beat-frequency signals on different radio-frequency chains in the distance dimension, a superimposed signal is obtained to estimate the distance, and the phase error of the first-frequency-domain signal is compensated according to the effective near-field and far-field demarcation line. Then, for each distance value in the distance estimation result, the angular region where a target exists at this distance value is accurately estimated according to the compensated first-frequency-domain signal. Thus, according to each distance value and the angle estimation results at each distance value, multi-target positioning results of the near-field and far-field can be obtained.

[0040] The following uses specific embodiments to elaborate in detail on the target positioning scheme proposed by the present invention.

[0041] Figure 1 FIG. 10 is a schematic diagram of an antenna based on RHS according to an exemplary embodiment of the present invention. The antenna includes a feed source and RHS units. After the radar signal is fed into the feed source, it propagates in the form of electromagnetic waves on the entire metasurface and serially excites the RHS units. At each RHS unit, the amplitude of the radiated electromagnetic wave can be independently regulated by adjusting the voltage of the diode.

[0042] Assume that the antenna has N RHS units and L feed sources. These N RHS units are arranged in rows, and each row of RHS units is correspondingly provided with a feed source connection. Define the number of RHS units in each row as N d , then N = N d *L.

[0043] When used as a transmitting antenna, its effect on electromagnetic waves can be represented by the holographic beamforming matrix M t . The size of this matrix is N×L, and the value of each element in this matrix can be expressed as:

[0044]

[0045] Among them, is the value of the (n,i)-th element in the matrix, which is used to represent the phase and amplitude changes experienced by the electromagnetic wave from being fed into the i-th feed source to being radiated by the n-th RHS unit; μ t represents the coupling factor, which is defined as the ratio of the energy obtained by an RHS unit to the energy fed into a feed source and is a known quantity; represents the radiation amplitude of the n-th RHS unit on the transmitting antenna; a n,i is a parameter with a value of 0 or 1. When the n-th RHS unit is located in the i-th row of the antenna, the value is 1, otherwise it is 0; It represents the in - house phase and amplitude change when electromagnetic waves are fed from the \(i\) - th feed and propagate to the \(n\) - th RHS unit.

[0046] When acting as a receiving antenna, according to the reciprocity of antennas, the holographic beamforming matrix \(M\) at this time r The value of each element in it can be expressed as:

[0047]

[0048] where is the value of the \((n,i)\) - th element in the matrix, which is used to represent the phase and amplitude change experienced by electromagnetic waves when propagating from the \(n\) - th RHS unit to the \(i\) - th feed; \(\mu\) r represents the coupling factor, which is defined as the ratio of the energy obtained by an RHS unit to the energy fed by a feed; represents the received amplitude of the \(n\) - th RHS unit on the receiving antenna; It represents the in - house phase and amplitude change when electromagnetic waves propagate from the \(n\) - th RHS unit to the \(i\) - th feed.

[0049] Figure 2 This is a schematic diagram of the structure of an RHS radar system shown according to an exemplary embodiment of the present invention. The RHS radar system includes a transmitting end and a receiving end. The transmitting end includes a transmitting antenna and a transmitter. The transmitting antenna is connected to the transmitter. The transmitter can be understood as a machine that generates radar signals, and the radar signals can adopt frequency - modulated continuous - wave (FMCW, Frequency - modulated continuous Wave) signals; the receiving end includes a receiving antenna and a receiver. The receiving antenna is connected to the receiver. The receiver can be understood as a signal - processing machine. Both the transmitting antenna and the receiving antenna are RHS - based antennas, and the origin \(O\) of the coordinate axis is located at the mid - point between the receiving antenna and the transmitting antenna.

[0050] The transmitting antenna includes \(L\) rows of RHS units and \(L\) first feeds. Each row of RHS units is connected to one first feed. The receiving antenna includes \(L\) rows of RHS units and \(L\) second feeds. Each row of RHS units is connected to one second feed.

[0051] In this embodiment, the pairwise combination between the \(L\) first feeds and the \(L\) second feeds forms multiple radio frequency chains. Specifically, the signal emitted from the \(i\) - th first feed of the transmitting antenna and received by the \(j\) - th second feed of the receiving antenna is one radio frequency chain. Therefore, the number of radio frequency chains formed between the \(L\) first feeds and the \(L\) second feeds is \(L\times L\).

[0052] When performing target positioning, the transmitter generates L transmission signals and feeds them into L rows of RHS units through L first feeds on the transmitting antenna respectively. The transmission signals propagate in the form of electromagnetic waves in each row of RHS units and radiate into free space. After being reflected by the target, they are received by the RHS units on the receiving antenna and transmitted to the receiver through L second feeds. In the receiver, according to the received signals of each second feed and the transmission signals of each first feed on the transmitting antenna, beat frequency signals on different radio frequency chains are generated, and their representation in the spatial domain is as follows:

[0053]

[0054] where y i,j [m] represents the beat frequency signal on the radio frequency chain formed between the i-th first feed and the j-th second feed, m = 0,..., N s -1 represents the time sampling point; K is the number of targets to be located; β k represents the complex channel gain related to the k-th target; f c and B respectively represent the center frequency and bandwidth of the radar signal; W n′ [m] represents the Gaussian white noise of the n-th RHS unit on the receiving antenna at the m-th time sampling point; ′ represents the propagation delay of the signal from the n-th RHS unit on the transmitting antenna through the k-th target to the n'-th RHS unit on the receiving antenna.

[0055] Then, by superimposing the first frequency domain signals of the beat frequency signals on different radio frequency chains in the distance dimension, a superimposed signal is obtained to estimate the distance, and the phase error of the first frequency domain signal is compensated according to the effective far-field and near-field boundary line. Then, for each distance value in the distance estimation result, the angular region where there is a target at this distance value is accurately estimated according to the compensated first frequency domain signal. Thus, according to each distance value and the angular estimation results at each distance value, the multi-target positioning results of the near field and the far field can be obtained.

[0056] The above process of estimating the distance and angle of the target based on the beat frequency signal can be executed on the receiver or on a separate external device. The present invention does not make specific limitations on this.

[0057] Figure 3 FIG. is a flowchart of an embodiment of a target positioning method according to an exemplary embodiment of the present invention. Based on the above-described Figure 2 shown RHS radar system, as Figure 3 shown, the target positioning method includes the following steps:

[0058] Step 101: Obtain the first frequency domain signal of the beat frequency signal on each radio frequency chain at the receiving end in the distance dimension;

[0059] Step 102: Determine a distance estimation result based on the superimposed signal of the first frequency-domain signals of each radio frequency chain, where the distance estimation result includes at least one distance value;

[0060] Step 103: Compensate the phase error of the first frequency-domain signal according to the far-field and near-field demarcation line;

[0061] Step 104: For each distance value in the distance estimation result, determine an angle estimation result at the distance value by using the compensated first frequency-domain signal;

[0062] Step 105: Obtain a positioning result of at least one target according to the distance estimation result and the angle estimation results at each distance value in the distance estimation result.

[0063] The beat frequency signal can be understood as the frequency difference signal generated during the mixing process of two waveforms with similar but not exactly the same frequencies, that is, the signal generated during the mixing process of the transmitted signal and the received signal.

[0064] The first frequency-domain signal can be understood as the signal representation obtained by converting the beat frequency signal from the time domain to the distance domain. The conversion method can be the discrete Fourier transform (DFT, discrete Fourier transform). The distance information of the target can be extracted through the DFT in the distance dimension. According to the above formula 3, let the signal propagation delay corresponding to the distance from the target to the origin O be c represents the speed of light, and R k represents the distance from the target to the origin O. When the representation form of the first frequency-domain signal is as follows:

[0065]

[0066] where Y i,j [p] represents the first frequency-domain signal of the beat frequency signal on the radio frequency chain formed between the i-th first feeder and the j-th second feeder; β k represents the complex channel gain related to the k-th target; The function has a peak at x = 0; is the noise in the transform domain.

[0067] It should be noted that the above is used to characterize that the distance between the RHS units is much smaller than the distance from the target to the origin O.

[0068] The superimposed signal is the addition result of the first frequency-domain signals of different radio frequency chains. The representation form of the superimposed signal is as follows:

[0069]

[0070] The distance estimation result can be understood as the distance value estimation result of multiple targets in free space. That is to say, at least one target corresponds to each distance value in the distance estimation result.

[0071] In a radar system, the beat frequency signal not only contains distance information but may also contain the angle information of the target. Before angle estimation, considering the phase error of the beat frequency signal, by dividing the angle detection range of the RHS radar system into K m discrete angle regions, that is and rewriting based on the representation form of the first frequency-domain signal shown in the above formula 4, the rewritten representation form is as follows:

[0072]

[0073] where is the complex channel gain related to the k-th angle region, and is non-zero if and only if there is a target in the k-th angle region ; W i,j [ρ] has the meaning as described in the above formula 4; represents the propagation delay of the n-th RHS unit on the transmitting antenna after being reflected by the target at (R ρ , θ k ) and propagating to the n'-th unit on the receiving antenna.

[0074] It should be noted that when the comparison result of the distance value R ρ , θ k ) of the target with the far-field and near-field demarcation line is different, ρ different representation forms are adopted to achieve different compensations for the phase error. Therefore represents the sensing matrix after compensating the phase error. At this time, Y [ρ] is the first frequency-domain signal after compensation. i,j

[0075] The far-field and near-field demarcation line can be understood as the distance demarcation line of the far-field target and the near-field target relative to the RHS radar system in free space. If the distance value is greater than the far-field and near-field demarcation line, it means the target is in the far field. If the distance value is less than the far-field and near-field demarcation line, it means the target is in the near field.

[0076] When estimating the angle of the target at each distance value in the distance estimation result, let then the matrix form of the above formula 6 is as follows:

[0077]

[0078] where is a sparse vector to be estimated, and is non-zero if and only if there is a target in the k-th angular region. According to the compressive sensing theory, it can be obtained by solving the following optimization problem P1:

[0079]

[0080] where P1 is a multi-measurement vector problem; ||·|| i represents the norm; ∈ is a predefined threshold parameter; is the constraint condition of problem P1.

[0081] By solving the above P1 problem using the orthogonal matching pursuit method (OMP, Orthogonal Matching Pursuit), let the solution result of problem P1 be Then the angle estimation result can be expressed as:

[0082]

[0083] where

[0084] The angle estimation result is used to represent the angular regions where there are targets. Combining with the distance values in the distance estimation result means which angular regions with targets exist at this distance value. The angular region refers to the discrete angular regions divided from the angular detection range of the RHS radar system.

[0085] Exemplarily, assume that the distance value R in the distance estimation result ρ corresponding angle estimation result indicates that the angular regions with targets are and Then it means that there are 2 targets at the distance value R ρ and the positioning result of one target is The positioning result of the other target is

[0086] So far, the above Figure 1 shown process is completed. By superimposing the first frequency-domain signals of the beat signals on different radio frequency chains in the distance dimension, the superimposed signal is obtained to estimate the distance, and the phase error of the first frequency-domain signal is compensated according to the effective far-field and near-field boundary line. Then, for each distance value in the distance estimation result, the angular regions with targets at this distance value are accurately estimated by using the compensated first frequency-domain signal. Thus, according to each distance value and the angle estimation results at each distance value, the multi-target positioning results of the near field and the far field can be obtained.

[0087] In an alternative embodiment, determining the distance estimation result based on the superimposed signal of the first frequency-domain signals of each radio frequency chain in step 102 may include:

[0088] Detect the peak of the superimposed signal, and generate a distance estimation result according to the frequency value corresponding to the detected peak and a preset distance estimation relation.

[0089] The peak of the superimposed signal can be understood as the local maximum in the frequency domain of the distance dimension. In the distance dimension, this peak corresponds to the distance information of the target. Usually, when the RHS radar system performs target detection, the waveform of the beat signal is known. Therefore, the waveform of the superimposed signal of the frequency-domain signals of each beat signal is also known. Therefore, by detecting the peak through the known signal waveform, it is possible to obtain which peaks are on the superimposed signal, and then the frequency values corresponding to these peaks can be obtained in the known signal waveform.

[0090] The preset distance estimation relation is expressed as follows:

[0091]

[0092] where c represents the speed of light; B represents the bandwidth of the radar signal; ρ represents the frequency value corresponding to the peak.

[0093] Express the frequency value corresponding to the detected peak as If J is less than or equal to the number K of targets to be located, the distance estimation result {R ρ} can be expressed as:

[0094]

[0095] In this embodiment, by detecting the peak of the superimposed signal, since in the distance dimension the peak corresponds to the distance information of the target, by using the pre-derived distance estimation relation and substituting the frequency value corresponding to the peak into this relation, the distance estimation result can be obtained.

[0096] In an alternative embodiment, compensating for the phase error of the first frequency-domain signal according to the far-field and near-field demarcation line in step 103 may include:

[0097] When the distance of the target to be located is greater than the far-field and near-field demarcation line, use a preset far-field model to compensate for the phase error of the first frequency-domain signal; when the distance of the target to be located is less than the far-field and near-field demarcation line, use a preset near-field model to compensate for the phase error of the first frequency-domain signal.

[0098] The far-field model can be understood as the mathematical model of the signal propagation delay when the target is in the far field, and the near-field model can be understood as the mathematical model of the signal propagation delay when the target is in the near field.

[0099] When the k-th target is in the far field, the far-field model can be expressed as:

[0100]

[0101] When the k-th target is in the near field, the near-field model can be expressed as:

[0102]

[0103] In the above Formulas 9 and 10, R k and θ k respectively represent the distance and azimuth angle of the k-th target to the origin of coordinates; τ nn′ (R k , θ k ) represents the propagation delay from the n-th RHS unit on the transmitting antenna, after being reflected by the target at (R k , θ k ), to the n'-th unit on the receiving antenna; c represents the speed of light; and respectively represent the horizontal and vertical coordinates of the n-th RHS unit on the transmitting antenna and the n'-th RHS unit on the receiving antenna.

[0104] Thus, it can be seen that when the distance value R ρ is greater than the far-field and near-field demarcation line R eff , the in the above Formula 6 is substituted with the far-field model Formula 9. When the distance value R ρ is less than the far-field and near-field demarcation line R eff , the in the above Formula 6 is substituted with the near-field model Formula 10.

[0105] In this embodiment, when performing angle estimation, by comparing the already estimated distance value with the effective far-field and near-field demarcation line, in order to achieve accurate angle estimation, if it is greater than the far-field and near-field demarcation line, it indicates that the target at this distance value belongs to a far-field target, and the far-field model is used for phase error compensation. If it is less than the far-field and near-field demarcation line, it indicates that the target at this distance value belongs to a near-field target, and the near-field model is used for phase error compensation.

[0106] In an alternative embodiment, before using the RHS radar system for target positioning, by optimizing the radiation amplitude of the transmitting antenna and the receiving amplitude of the receiving antenna, the target positioning accuracy can be further improved.

[0107] The optimization process includes: obtaining the mutual coherence relation expression of the sensing matrix by using the first amplitude of the RHS unit of the receiving antenna at the receiving end and the second amplitude of the RHS unit of the transmitting antenna at the transmitting end, taking the first amplitude and the second amplitude within the preset value range as the constraint conditions, solving the minimum optimization problem of the mutual coherence relation expression to obtain the optimized value of the first amplitude and the optimized value of the second amplitude, adjusting the diode voltage of each RHS unit at the receiving end by using the optimized value of the first amplitude, and adjusting the diode voltage of each RHS unit at the transmitting end by using the optimized value of the second amplitude.

[0108] The first amplitude is the receiving amplitude of the receiving antenna The second amplitude is the radiation amplitude of the transmitting antenna The mutual coherence relation expression of the sensing matrix is defined as follows:

[0109]

[0110] In the above formula 11, denotes the k-th column of, p = 0, 1…N s , k1 and k2 take 1, 2……K m ; Since the and are as shown in the above formula 1 and formula 2, so is represented by and .

[0111] The above optimization problem P2 can be established as:

[0112]

[0113] Among them, is the constraint condition of the P2 problem, indicating that is a real number between 0 and 1, that is, the preset value range is 0 to 1.

[0114] Since the in the P2 problem are mutually coupled and difficult to solve directly, so by decomposing P2 into P t sub-problem and P r sub-problem and solving them iteratively, using l = t and ι = r to represent the parameters of the transmitting antenna and the receiving antenna respectively, then the two sub-problems can be uniformly represented as:

[0115]

[0116] Among them, The (n, n′)-th element of

[0117] The above-mentioned P ι problem can be solved by the Successive Convex Approximation (SCA) method. By iteratively solving the P t sub-problem and the P r sub-problem, the radiation amplitude of the transmitting antenna and the optimized result of the receiving amplitude of the receiving antenna can be obtained, that is, the optimized value of the first amplitude and the optimized value of the second amplitude. In an alternative embodiment, the process of obtaining the above-mentioned near-field and far-field boundary can include:

[0118] Using the steering vector of the receiving antenna in the near field at the receiving end and the steering vector of the transmitting antenna in the near field at the transmitting end to obtain the near-field channel matrix, using the steering vector of the receiving antenna in the far field and the steering vector of the transmitting antenna in the far field to obtain the far-field channel matrix, using the near-field channel matrix, the far-field channel matrix, and the preset maximum channel gain loss to obtain the relationship between distance and angle, and then according to the angle detection range of the radar system and the said relationship, determining the distance values at different angles, and selecting the minimum value from the distance values at different angles as the near-field and far-field boundary.

[0119] The derivation process of the relationship between distance and angle is as follows:

[0120] Assume that a target is located at (R, θ). When it is in the near field, the near-field channel matrix H(R, θ) ∈ C

[0121] can be expressed as: N×N

[0122]

[0123] where h t (R, θ) represents the steering vector of the transmitting antenna in the near field, with a vector size of N. The n-th element of the vector h t (R, θ) λ c represents the wavelength of the center frequency f c ; represents the horizontal and vertical coordinates of the n-th RHS unit of the transmitting antenna; h r (R, θ) represents the steering vector of the receiving antenna in the near field, with a vector size of N as well. The n-th element of the vector h r (R, θ) represents the horizontal and vertical coordinates of the n-th RHS unit of the receiving antenna.

[0124] ​Similarly, when the target is in the far field, the far-field channel matrix H F (R,θ) ∈ C N×N can be expressed as:

[0125]

[0126] where h t,F (R,θ) represents the steering vector of the transmitting antenna in the far field, with a vector size of N, and the n-th element of h t,F (R,θ) h r,F (R,θ) represents the steering vector of the receiving antenna in the far field, also with a vector size of N, and the n-th element of h r,F (R,θ)

[0127] The normalized coherence ζ(R,θ) of the near-field channel matrix H(R,θ) and the far-field channel matrix H F (R,θ) is defined as:

[0128]

[0129] where ζ(R,θ) can be used to measure the channel gain loss caused by applying the far-field model, that is, the channel gain loss = 1 - ζ(R,θ). Specifically, let δ be the maximum acceptable channel gain loss, that is, 1 - ζ(R,θ) = δ, and the relationship between distance and angle can be obtained as:

[0130]

[0131] where represents the maximum aperture length of the RHS; v1 and v2 satisfy and d x and d y represent the spacing between RHS units along the x-axis and y-axis respectively, and the function G(x) is defined as

[0132] Assume that the angle detection range of the RHS radar system is from 0 degrees to 180 degrees. By substituting θ = 0, 1, 2... 180 into the above formula 15, 181 distance values can be obtained, and the minimum distance value among them is selected as the far-near field boundary R eff .

[0133] Based on the above embodiments, the present invention utilizes the low power consumption and amplitude regulation characteristics of the RHS, designs an optimization algorithm for the RHS amplitude, establishes a radar positioning system based on the RHS, reduces the hardware cost and power consumption of the antenna and radar system, and obtains an effective far - near field boundary by deriving a closed - form expression of the far - near field boundary. Thus, by designing a distance and angle estimation method for mixed far - near field targets, high - precision and low - power joint far - near field multi - target positioning is achieved.

[0134] As Figure 4A shown, it is the error comparison of the present invention's solution and other existing solutions in terms of target distance estimation. As Figure 4A can be seen, when the same signal - to - noise ratio (SNR) is adopted, the root - mean - square error (RMSE r (m)) of the distance estimation of the present invention's solution is always lower than that of other solutions.

[0135] As Figure 4B shown, it is the error comparison of the present invention's solution and other existing solutions in terms of target angle estimation. As Figure 4B can be seen, when the same signal - to - noise ratio (SNR) is adopted, the root - mean - square error (RMSE th (deg)) of the angle estimation of the present invention's solution is always lower than that of other solutions.

[0136] Corresponding to the embodiments of the foregoing target positioning method, the present invention also provides embodiments of a target positioning device.

[0137] Figure 5 Shown is a schematic structural diagram of a target positioning device according to an exemplary embodiment of the present invention. The target positioning device includes:

[0138] A first transformation module 410, configured to obtain a first frequency - domain signal of the beat frequency signal on each RF chain of the receiving end in the distance dimension;

[0139] A distance estimation module 420, configured to determine a distance estimation result based on the superimposed signal of the first frequency - domain signals of each RF chain, where the distance estimation result includes at least one distance value;

[0140] A compensation module 430, configured to compensate for the phase error of the first frequency - domain signal according to the far - near field boundary;

[0141] An angle estimation module 440, configured to, for each distance value in the distance estimation result, use the compensated first frequency - domain signal to determine an angle estimation result at the distance value, where the angle estimation result is used to represent an angle region where a target exists, and the angle region refers to a discrete angle region obtained by dividing the angle detection range of the RHS radar system;

[0142] A target positioning module 450, configured to obtain a positioning result of at least one target according to the distance estimation result and the angle estimation result at each distance value in the distance estimation result.

[0143] For the implementation processes of the functions and roles of each unit in the above device, please refer to the implementation processes of the corresponding steps in the above method for details, and will not be elaborated here.

[0144] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The system embodiment described above is only illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the present invention. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0145] Figure 6 The figure is a hardware structure diagram of an electronic device according to an exemplary embodiment of the present invention. The electronic device includes: a communication interface 401, a processor 402, a machine-readable storage medium 403, and a bus 404. Among them, the communication interface 401, the processor 402, and the machine-readable storage medium 403 complete mutual communication through the bus 404. The processor 402 can execute the target positioning method described above by reading and executing the machine-executable instructions corresponding to the control logic of the target positioning method in the machine-readable storage medium 403. For the specific content of this method, please refer to the above embodiments and will not be repeated here.

[0146] The machine-readable storage medium 403 mentioned in the present invention can be any electronic, magnetic, optical or other physical storage system, which can contain or store information, such as executable instructions, data, etc. For example, the machine-readable storage medium can be: a volatile memory, a non-volatile memory, or a similar storage medium. Specifically, the machine-readable storage medium 403 can be a RAM (Random Access Memory), a flash memory, a storage drive (such as a hard disk drive), any type of storage disk (such as an optical disc, a DVD, etc.), or a similar storage medium, or a combination thereof.

[0147] The embodiment of the present invention also provides a computer-readable storage medium corresponding to the target positioning method provided in the foregoing embodiment. Please refer to Figure 7As shown, the computer-readable storage medium shown is an optical disc 30, on which a computer program (i.e., a program product) is stored. When the computer program is run by a processor, it will execute the target positioning method provided by any of the foregoing embodiments.

[0148] It should be noted that examples of the computer-readable storage medium may also include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other optical and magnetic storage media, which will not be elaborated here one by one.

[0149] The computer-readable storage medium provided in the above embodiments of the present invention and the target positioning method provided in the embodiments of the present invention are based on the same inventive concept and have the same beneficial effects as the methods adopted, run, or implemented by the application programs stored therein.

[0150] The embodiments of the present invention also provide a computer program product corresponding to the target positioning method provided in the foregoing embodiments. The computer program product includes a computer program, and the computer program is executed by a processor to implement the target positioning method provided in the foregoing embodiments.

[0151] The computer program product provided in the above embodiments of the present invention and the target positioning method provided in the embodiments of the present invention are based on the same inventive concept and have the same beneficial effects as the methods adopted, run, or implemented by the application programs stored therein.

[0152] Those skilled in the art will readily think of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include common general knowledge or conventional technical means in the technical field not disclosed by the present invention. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present invention are pointed out by the following claims.

[0153] It should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, commodity or device including the said element.

[0154] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A target positioning method, characterized in that: Applied to a reconfigurable holographic metasurface RHS radar system, the RHS radar system includes a receiving end and a transmitting end, and a plurality of radio frequency chains are formed between the receiving end and the transmitting end. The method includes: Acquire a first frequency domain signal of the beat frequency signal of the receiving end on each radio frequency chain in the distance dimension; Determine a distance estimation result based on the superposition signal of the first frequency domain signal of each radio frequency chain, wherein the distance estimation result includes at least one distance value; Compensating for a phase error of the first frequency domain signal according to a far-field and near-field dividing line; For each distance value in the distance estimation result, determine an angle estimation result on the distance value using the compensated first frequency domain signal, wherein the angle estimation result is used to represent an angle region where a target exists, and the angle region refers to a discrete angle region into which an angle detection range of the RHS radar system is divided; A positioning result of at least one target is obtained according to the distance estimation result and the angle estimation result at each distance value in the distance estimation result.

2. The method according to claim 1, characterized in that The determining of the distance estimation result based on the superposition signal of the first frequency domain signal of each radio frequency chain includes: Detecting a peak value of the superimposed signal; The distance estimation result is generated according to the frequency value corresponding to the peak value and a preset distance estimation relationship.

3. The method according to claim 1, characterized in that: The compensating the phase error of the first frequency domain signal according to the far-field and near-field dividing line includes: When the distance of the target to be located is greater than the far-field and near-field dividing line, a preset far-field model is used to compensate the phase error of the first frequency domain signal; When the distance value is smaller than the far-field and near-field dividing line, a preset near-field model is used to compensate for the phase error of the first frequency domain signal.

4. The method according to any one of claims 1 to 3, characterized in that: The method further comprises: Obtaining a mutual coherence relation of a sensing matrix using a first amplitude of an RHS unit of a receiving antenna in a receiving end and a second amplitude of an RHS unit of a transmitting antenna in a transmitting end; Taking the first amplitude and the second amplitude as a restriction condition that they are within a preset value range, the optimized value of the first amplitude and the optimized value of the second amplitude are obtained by solving the minimum optimization problem of the mutual coherence relationship; adjusting the diode voltage of each RHS unit in the receiving end using the optimized value of the first amplitude; The diode voltage of each RHS unit in the transmitting end is adjusted using the optimized value of the second amplitude.

5. The method according to any one of claims 1 to 3, characterized in that: The method also includes a process of obtaining the far-field and near-field dividing line: A near-field channel matrix is ​​obtained by using a steering vector of a receiving antenna in a receiving end and a steering vector of a transmitting antenna in a transmitting end. Obtaining a far-field channel matrix using a steering vector of the receiving antenna in the far field and a steering vector of the transmitting antenna in the far field; Obtaining a relationship between distance and angle using the near-field channel matrix, the far-field channel matrix, and a preset maximum channel gain loss; Determining distance values ​​at different angles according to the angular detection range of the RHS radar system and the relationship; The minimum value is selected from the distance values ​​at different angles as the far-field and near-field dividing line.

6. A reconfigurable holographic metasurface RHS radar system, characterized in that: The system includes a receiving end and a transmitting end; The transmitting end includes a transmitting antenna and a transmitter, the transmitting antenna includes a plurality of rows of RHS units and a plurality of first feed sources, each row of RHS units is connected to one of the first feed sources, and the transmitter is used to generate a transmitting signal and feed it into each of the first feed sources; The receiving end includes a receiving antenna and a receiver, the receiving antenna includes multiple rows of RHS units and multiple second feed sources, each row of RHS units is connected to one of the second feed sources, the receiver is used to receive a receiving signal transmitted by each of the second feed sources, and generate a beat frequency signal on different RF chains composed of the multiple first feed sources and the multiple second feed sources based on the transmitting signal and the receiving signal, and the receiver is also used to execute the steps of the target positioning method described in any one of claims 1 to 5 above.

7. A target positioning device, characterized in that: Applied to a reconfigurable holographic metasurface RHS radar system, the RHS radar system includes a receiving end and a transmitting end, a plurality of radio frequency chains are formed between the receiving end and the transmitting end, and the device includes: A first transformation module, used for acquiring a first frequency domain signal of the beat frequency signal of the receiving end on each radio frequency chain in a distance dimension; a distance estimation module, configured to determine a distance estimation result based on a superimposed signal of the first frequency domain signal of each radio frequency chain, wherein the distance estimation result includes at least one distance value; A compensation module, used for compensating the phase error of the first frequency domain signal according to the far-field and near-field dividing line; an angle estimation module, for determining, for each distance value in the distance estimation result, an angle estimation result on the distance value using the compensated first frequency domain signal, wherein the angle estimation result is used to indicate an angle region where a target exists, and the angle region refers to a discrete angle region into which an angle detection range of the RHS radar system is divided; The target positioning module is used to obtain a positioning result of at least one target according to the distance estimation result and the angle estimation result at each distance value in the distance estimation result.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: The processor executes the program to implement the method according to any one of claims 1 to 5.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the method according to any one of claims 1 to 5.

10. A computer program product, comprising a computer program, characterized in that The computer program is executed by a processor to implement the method according to any one of claims 1 to 8.

Images