Radar high-precision positioning method for avoiding obstacles

Abstract

The invention relates to the technical field of radar positioning, and particularly discloses a radar high-precision positioning method for avoiding obstacles, which comprises the following steps of: S1, transmitting and receiving a radar signal in a detection period, and simultaneously acquiring environment information containing a known reflector position; s2, dividing the received original echo signal into a plurality of components, and estimating the signal arrival angle and the relative time delay of each component one by one; s3, marking the component with the time delay exceeding a threshold value as a delay signal, comparing the arrival angle of the delay signal with the direction of a reflector in the environment prior information, judging whether the delay signal comes from the known reflector, and if so, judging the delay signal as a multipath interference signal; and S4, eliminating all identified multipath interferences from the original signal to obtain a pure target echo signal, and further analyzing to obtain accurate obstacle information so as to realize high-precision positioning.

Description

Technical Field

[0001] This invention relates to the field of radar positioning technology, and more specifically to a high-precision radar positioning method for obstacle avoidance. Background Technology

[0002] In complex environments, radar systems often face challenges such as multipath reflections, environmental clutter, and human interference, resulting in chaotic received signals and making it difficult to effectively distinguish target echoes from noise.

[0003] Traditional radar positioning technology, limited by signal processing algorithms, often fails to accurately identify and filter invalid or misleading signals, leading to problems such as decreased positioning accuracy and trajectory drift. These issues are particularly pronounced in scenarios requiring high-precision positioning. While existing solutions attempt to improve performance by increasing the number of antennas, boosting transmission power, or employing complex filtering algorithms, these measures are either costly or complex to implement and fail to fundamentally address the core problem of low signal recognition.

[0004] Therefore, there is an urgent need for an innovative high-precision radar positioning method that can intelligently analyze and filter effective target reflection signals, effectively suppress interference, and ensure stable and accurate positioning in various complex environments, providing reliable support for the aforementioned application scenarios. Summary of the Invention

[0005] The purpose of this invention is to provide a high-precision radar positioning method for obstacle avoidance, and to solve the following technical problems.

[0006] The objective of this invention can be achieved through the following technical solutions: A high-precision radar positioning method for obstacle avoidance includes the following steps: Step S1: Set the detection period, transmit the detection signal through the radar antenna array within the detection period, receive the returned original echo signal, and obtain environmental prior information, including the positioning information of each known reflector; Step S2: Divide the original echo signal into several component signals, perform spatial spectrum estimation on each component signal to obtain the angle of arrival of each component signal relative to the antenna array; and perform time delay estimation on each component signal to obtain the relative time delay value of each component signal. Step S3: The component signal whose relative delay value exceeds the preset delay threshold is recorded as the delayed component signal; based on the environmental prior information and the angle of arrival of the delayed component signal, it is determined whether the delayed component signal originates from a known reflector. If the delayed component signal originates from a known reflector, the delayed component signal is recorded as a multipath interference signal. Step S4: Remove all multipath interference signals from the original echo signal to obtain the target echo signal, and analyze the target echo signal to obtain obstacle information within the detection period.

[0007] As a further aspect of the present invention: the prior information consists of all known reflectors acquired in the previous detection cycle, and the positioning information of each known reflector.

[0008] As a further aspect of the present invention: the process of determining the location information includes: The detection range is obtained by taking the location of the radar's antenna array as the center and the propagation radius as the radius; and a coordinate system is established within the detection range with the center as the origin, and the coordinates of the known reflector in the coordinate system are obtained and recorded as the positioning information of the known reflector.

[0009] As a further aspect of the present invention: the process of dividing the original echo signal into several component signals includes: Time-domain energy analysis is performed on the original echo signal to obtain the time window corresponding to the original echo signal. Several time nodes are selected within the time window, and the energy values ​​of the original echo signal at each time node are obtained to generate an energy distribution curve. All maxima on the energy distribution curve are obtained, and the energy values ​​corresponding to each maxima are recorded as energy peaks. All minima on the energy distribution curve are obtained, and the energy values ​​corresponding to each minima are recorded as energy valleys. The time nodes corresponding to each energy valley are used as time-domain segmentation points, and the original echo signal is divided into several time segments according to each time-domain segmentation point. Each time segment has a pair of adjacent energy valleys as its start and end boundaries, and contains one and only one energy peak. The signal within each time segment is recorded as a component signal.

[0010] As a further aspect of the present invention, the process of spatial spectral estimation of the component signal includes: Obtain the total number M of all array elements in the antenna array, where each array element is a single antenna within the array; for any component signal, sample the component signal N times based on the M array elements, where N is a preset number of sampling times, to obtain M×N sampled data. Construct an M-row, N-column matrix based on the sampled data, denoted as the received data matrix X; obtain the covariance matrix of the received data matrix. , where X H To receive the conjugate transpose of the data matrix X; The wavelength of the detection signal is obtained, and the steering vector a is determined based on the antenna array arrangement and the wavelength. i Based on the covariance matrix and the guiding vector, construct the space function. , where R -1Let a be the inverse of the covariance matrix. H ( i ) is the conjugate transpose of the guide vector; a range of arrival angles is set, and an angle step size is set. Several angle values ​​are selected within the range of arrival angles according to the angle step size. The value of P(θ) is obtained sequentially for each angle value, resulting in a set of function values. The maximum value P(θ) within the set of function values ​​is then obtained. max To obtain the maximum value P(θ) max The angle value corresponding to θ is denoted as the angle of arrival of the component signal relative to the antenna array.

[0011] As a further aspect of the present invention, the process of time delay estimation for each component signal includes: Let the detected signal be denoted as r(t), and for any component signal, let the component signal be denoted as s(t). Perform cross-correlation calculation on the detected signal and the component signals to obtain the cross-correlation function. Where k is the preset discrete delay step number and n is the index of the sampling point; obtain the cross-correlation function R rs When (k) reaches its maximum value, the corresponding discrete delay step number k max Then the relative time delay value Trel=k of the component signal is obtained. max / fs, where fs is the sampling rate.

[0012] As a further aspect of the present invention: the process of setting the delay threshold includes: Based on the prior information, the distances between all known reflectors and the radar's antenna array are obtained, and the minimum value d of these distances is selected. min Then we get the minimum extra distance L. min =2d min And obtain the minimum multipath delay t min =L min / c, where the minimum multipath delay is denoted as the delay threshold, and c is the speed of light.

[0013] As a further aspect of the present invention: the process of determining whether the delayed component signal originates from a known reflector includes: Based on the positioning information of each known reflector in the prior information and the origin in the coordinate system, the direction angle of each known reflector relative to the origin is obtained; for any delay component, the angle of arrival of the delay component signal and the angle deviation of each direction angle are obtained in sequence. If any angle deviation is less than or equal to a preset angle deviation threshold, it is determined that the delay component signal originates from a known reflector.

[0014] The beneficial effects of this invention are: Traditional methods either struggle to distinguish between multipath and direct signals or rely on complex models with high computational costs. In contrast, this invention utilizes prior knowledge of the location of known building structures, combined with the measurable physical characteristics of multipath signals—namely, time delay and angular pointing towards the reflector—to construct a clear and reliable discrimination logic. This logic identifies and locks onto multipath interference components from mixed echoes, achieving targeted identification of interference signals rather than generalized filtering. Thus, while effectively eliminating interference, it maximizes the protection of the integrity of the true target signal. Attached Figure Description

[0015] The invention will now be further described with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic diagram illustrating the steps of a high-precision radar positioning method for obstacle avoidance according to the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figure 1 As shown, this invention is a high-precision radar positioning method for obstacle avoidance, comprising the following steps: Step S1: Set the detection period, transmit the detection signal through the radar antenna array within the detection period, receive the returned original echo signal, and obtain environmental prior information, including the positioning information of each known reflector; It is worth noting that the process also includes a compensation step for the radar platform's own motion to maintain the validity of prior reflector position information in moving scenarios; the compensation step includes: The motion parameters of the radar platform during the current detection period are obtained, including displacement vector and rotation angle; the known reflector positioning information in the prior information is updated by coordinate transformation based on the motion parameters to obtain the updated prior information. Specifically, the process of acquiring the motion parameters includes obtaining the three-dimensional displacement and attitude changes of the radar platform between adjacent detection cycles through the inertial measurement unit mounted on the radar platform, or calculating the platform motion through the radar's own tracking results of fixed environmental features; the coordinate transformation and update process includes: Given the coordinates (x, y, z) of the known reflector in the radar coordinate system from the previous detection cycle, based on the displacement vector... and rotation angle The new coordinates (x´, y´, z´) in the current radar coordinate system are calculated using the rigid body transformation formula: ,in It is a rotation matrix; The updated prior information will be used to determine multipath interference in the current detection cycle, ensuring that the azimuth information of known reflectors remains accurate during radar movement, thereby maintaining the effectiveness of multipath identification and suppression. Furthermore, the motion compensation step also includes verifying the updated prior information. Specifically, in the current detection cycle, the received echo signal is preliminarily analyzed to extract the obvious fixed reflector orientation and match it with the reflector orientation in the updated prior information. If the matching error exceeds the preset tolerance, the motion parameters are corrected and the coordinate transformation is re-executed. In a preferred embodiment of the present invention, the process of setting the detection period includes: If the propagation radius R of the detection signal is preset and the propagation speed V of the detection signal under the current medium is obtained, then the detection period is set to 2tRV≥T>2RV, where t is the preset percentage of reserved redundancy time and t∈[110%,120%]; It should be noted that the detection period must be greater than or equal to the maximum multipath delay, and the maximum multipath delay is greater than 2RV. Therefore, a redundancy of [10%, 20%] is reserved to cope with the fluctuation of computational load under complex environments. In a preferred embodiment of the present invention, the prior information is all known reflectors obtained in the previous detection cycle, and the positioning information of each known reflector. Specifically, the environmental prior information is the set of all known fixed reflectors identified, learned, and confirmed in the previous one or more historical detection cycles; The process of determining the location information includes: Using the location of the radar's antenna array as the center and the propagation radius as the radius, the detection range is obtained; and using the center as the origin, a coordinate system is established within the detection range, and the coordinates of the known reflector in the coordinate system are obtained, which are recorded as the positioning information of the known reflector. Step S2: Divide the original echo signal into several component signals, perform spatial spectrum estimation on each component signal to obtain the angle of arrival of each component signal relative to the antenna array; and perform time delay estimation on each component signal to obtain the relative time delay value of each component signal. Specifically, time-domain energy analysis is performed on the preprocessed digital echo signal to calculate the energy of the signal in a continuous time unit and form an energy-time curve; all local maxima points, i.e. peaks, on the curve are identified, and each peak usually corresponds to a major signal source; the time-domain waveform of the original signal is divided into multiple continuous time segments using the local minima between adjacent peaks as dividing points, and each segment contains a major energy peak. For a component signal, a received data matrix is ​​constructed using the data received by each element of the antenna array. The sample covariance matrix of this matrix is ​​calculated, and combined with the steering vector related to the array geometry and wavelength, a spatial spectrum function is constructed according to the minimum variance distortionless response criterion. By scanning within the angular search range of this function, its main peak is located, and the angle corresponding to the peak is initially determined as the angle of arrival of the signal. Using a copy of the radar-transmitted detection signal or the earliest arriving direct signal as a reference signal, calculate the cross-correlation function between the component signal and the reference signal; search for the global peak of the cross-correlation function, and the time shift corresponding to the peak represents the time delay of the component signal relative to the reference signal; In a preferred embodiment of the present invention, the process of dividing the original echo signal into several component signals includes: Time-domain energy analysis is performed on the original echo signal to obtain the time window corresponding to the original echo signal. Several time nodes are selected within the time window, and the energy values ​​of the original echo signal at each time node are obtained to generate an energy distribution curve. All maxima on the energy distribution curve are obtained, and the energy values ​​corresponding to each maxima are recorded as energy peaks. All minima on the energy distribution curve are obtained, and the energy values ​​corresponding to each minima are recorded as energy valleys. The time nodes corresponding to each energy valley are used as time-domain segmentation points, and the original echo signal is divided into several time segments according to each time-domain segmentation point. Each time segment has a pair of adjacent energy valleys as its start and end boundaries, and contains one and only one energy peak. The signal within each time segment is recorded as a component signal. In a preferred embodiment of the present invention, the process of spatial spectrum estimation of the component signal includes: Obtain the total number M of all array elements in the antenna array, where each array element is a single antenna within the array; for any component signal, sample the component signal N times based on the M array elements, where N is a preset number of sampling times, to obtain M×N sampled data. Construct an M-row, N-column matrix based on the sampled data, denoted as the received data matrix X; obtain the covariance matrix of the received data matrix. , where X H To receive the conjugate transpose of the data matrix X; The wavelength of the detection signal is obtained, and the steering vector a is determined based on the antenna array arrangement and the wavelength. i Based on the covariance matrix and the guiding vector, construct the space function. , where R -1 Let a be the inverse of the covariance matrix. H ( i ) is the conjugate transpose of the guide vector; a range of arrival angles is set, and an angle step size is set. Several angle values ​​are selected within the range of arrival angles according to the angle step size. The value of P(θ) is obtained sequentially for each angle value, resulting in a set of function values. The maximum value P(θ) within the set of function values ​​is then obtained. max To obtain the maximum value P(θ) max The angle value corresponding to θ is denoted as the angle of arrival of the component signal relative to the antenna array; It should be noted that the range of the angle of arrival is set according to the detection range, and is generally set to a horizontal detection range [-90°, 90°] and a vertical detection range [-30°, 30°]. In a preferred embodiment of the present invention, the process of time delay estimation for each component signal includes: Let the detected signal be denoted as r(t), and for any component signal, let the component signal be denoted as s(t). Perform cross-correlation calculation on the detected signal and the component signals to obtain the cross-correlation function. Where k is the preset discrete delay step number and n is the index of the sampling point; obtain the cross-correlation function R rs When (k) reaches its maximum value, the corresponding discrete delay step number k max Then the relative time delay value Trel=k of the component signal is obtained. max / fs, where fs is the sampling rate; It should be noted that the peak of the cross-correlation function corresponds to the moment when the probe signal and the component signal are most similar, and the delay step k at this time is the number of steps corresponding to the time difference between the two. Step S3: The component signal whose relative delay value exceeds the preset delay threshold is recorded as the delayed component signal; based on the environmental prior information and the angle of arrival of the delayed component signal, it is determined whether the delayed component signal originates from a known reflector. If the delayed component signal originates from a known reflector, the delayed component signal is recorded as a multipath interference signal. In a preferred embodiment of the present invention, the process of setting the delay threshold includes: Based on the prior information, the distances between all known reflectors and the radar's antenna array are obtained, and the minimum value d of these distances is selected. min Then we get the minimum extra distance L. min =2d min And obtain the minimum multipath delay tmin =L min / c, where the minimum multipath delay is denoted as the delay threshold, and c is the speed of light; In a preferred embodiment of the present invention, the process of determining whether the delayed component signal originates from a known reflector includes: Based on the positioning information of each known reflector in the prior information and the origin in the coordinate system, the direction angle of each known reflector relative to the origin is obtained; for any delay component, the angle of arrival of the delay component signal and the angle deviation of each direction angle are obtained in sequence; if any angle deviation is less than or equal to a preset angle deviation threshold, it is determined that the source of the delay component signal is a known reflector. Furthermore, the angle deviation threshold is an adaptive angle deviation threshold, the value of which is dynamically adjusted according to the signal-to-noise ratio of the current detection environment to improve the system's robustness in distinguishing different signal qualities; the process of determining the angle deviation threshold includes: Step S3.1: Estimate the signal-to-noise ratio (SNR) of the current original echo signal or target echo signal. est Specifically, the noise power P is calculated during the signal's idle periods or during periods when there is no known target. noise And based on the total signal power P all Calculate SNR est =10×log 10 [(P all -P noise ) / P noise ]; Step S3.2: Based on the signal-to-noise ratio (SNR) est Calculate the adaptive angle deviation threshold θ th , specifically: A functional relationship between signal-to-noise ratio (SNR) and angle estimation error is established. In this relationship, a lower SNR results in a larger angle estimation error, and the required deviation threshold should be correspondingly relaxed. This functional relationship is generally as follows: , where θ base K is the reference angle deviation threshold, and K is the preset adjustment coefficient. Step S3.3: Replace the original fixed angle deviation threshold with the angle deviation threshold calculated according to the functional relationship, and perform a comparison and judgment between the delayed component signal and the known reflector direction angle; Understandably, by adaptively changing the angle deviation threshold with the signal-to-noise ratio, the discrimination conditions are tightened when the signal quality is good to improve the multipath identification accuracy, and the conditions are relaxed when the signal quality is poor to avoid missing real multipath interference, thereby significantly improving the overall robustness and reliability of the system in complex and variable electromagnetic environments. Step S4: Remove all multipath interference signals from the original echo signal to obtain the target echo signal, and analyze the target echo signal to obtain obstacle information within the detection period; In a preferred embodiment of the present invention, the process of obtaining the target echo signal includes generating a reference copy in the time domain that matches the waveform of the multipath interference signal, and canceling it out from the original echo signal to obtain the target echo signal after filtering out the multipath interference. In a preferred embodiment of the present invention, the process of analyzing the target echo signal includes performing constant false alarm rate detection on the target echo signal, extracting potential target points, estimating the distance, azimuth angle and radial velocity parameters for each point, and outputting the parameter estimation results as obstacle information in the current detection cycle. In a preferred embodiment of the present invention, the process of cancelling the original echo signal is implemented through a mathematical model, and the cancellation includes: Step S4.1: Set the time delay corresponding to the identified i-th multipath interference signal to τ. i The angle of arrival is θ i Based on radar response and environmental scattering characteristics, the comprehensive attenuation factor Q of the i-th multipath interference signal is estimated. i With additional phase offset W i The comprehensive attenuation factor Q i The additional phase shift W is obtained by comparing the amplitude spectrum ratio of the multipath signal and the direct reference signal. i Obtained through signal cross-correlation or phase spectrum analysis; Step S4.2: Denote the baseband waveform of the transmitted detection signal as p(t), and reconstruct the baseband waveform estimate m of the i-th multipath interference signal at the receiver. i (t)=Q i ·p(t-τ i )·e jφi Where j is the imaginary unit, e jφi This represents a complex rotation caused by a phase shift; Step S4.3: Overlay the reconstructed waveforms of all N identified multipath interference signals in the time domain to obtain the total multipath interference estimate. The multipath interference estimate is subtracted from the original echo signal y(t) to obtain the canceled signal y. cancel (t)=y(t)-M all .

[0019] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A high-precision radar positioning method for obstacle avoidance, characterized in that, Includes the following steps: Step S1: Set the detection period, transmit the detection signal through the radar antenna array within the detection period, receive the returned original echo signal, and obtain environmental prior information, including the positioning information of each known reflector; Step S2: Divide the original echo signal into several component signals, perform spatial spectrum estimation on each component signal, and obtain the angle of arrival of each component signal relative to the antenna array. The time delay of each component signal is estimated to obtain the relative time delay value of each component signal; Step S3: The component signal whose relative delay value exceeds the preset delay threshold is recorded as the delayed component signal; based on the environmental prior information and the angle of arrival of the delayed component signal, it is determined whether the delayed component signal originates from a known reflector. If the delayed component signal originates from a known reflector, the delayed component signal is recorded as a multipath interference signal. Step S4: Remove all multipath interference signals from the original echo signal to obtain the target echo signal, and analyze the target echo signal to obtain obstacle information within the detection period.

2. The radar high-precision positioning method for obstacle avoidance according to claim 1, characterized in that, In step S1, the prior information consists of all known reflectors acquired in the previous detection cycle, and the positioning information of each known reflector.

3. The high-precision radar positioning method for obstacle avoidance according to claim 2, characterized in that, In step S1, the process of determining the location information includes: The detection range is obtained by taking the location of the radar's antenna array as the center and the propagation radius as the radius; and a coordinate system is established within the detection range with the center as the origin, and the coordinates of the known reflector in the coordinate system are obtained and recorded as the positioning information of the known reflector.

4. The high-precision radar positioning method for obstacle avoidance according to claim 1, characterized in that, In step S2, the process of dividing the original echo signal into several component signals includes: Time-domain energy analysis is performed on the original echo signal to obtain the time window corresponding to the original echo signal. Several time nodes are selected within the time window, and the energy values ​​of the original echo signal at each time node are obtained to generate an energy distribution curve. All maxima on the energy distribution curve are obtained, and the energy values ​​corresponding to each maxima are recorded as energy peaks. All minima on the energy distribution curve are obtained, and the energy values ​​corresponding to each minima are recorded as energy valleys. The time nodes corresponding to each energy valley are used as time-domain segmentation points, and the original echo signal is divided into several time segments according to each time-domain segmentation point. Each time segment has a pair of adjacent energy valleys as its start and end boundaries, and contains one and only one energy peak. The signal within each time segment is recorded as a component signal.

5. A high-precision radar positioning method for obstacle avoidance according to claim 1, characterized in that, In step S2, the process of spatial spectral estimation of the component signals includes: Obtain the total number M of all array elements in the antenna array, where each array element is a single antenna within the array; for any component signal, sample the component signal N times based on the M array elements, where N is a preset number of sampling times, to obtain M×N sampled data. Construct an M-row, N-column matrix based on the sampled data, denoted as the received data matrix X; obtain the covariance matrix of the received data matrix. , where X H To receive the conjugate transpose of the data matrix X; The wavelength of the detection signal is obtained, and the steering vector a is determined based on the arrangement of the antenna array and the wavelength. θ Based on the covariance matrix and the guiding vector, construct the space function. , where R -1 Let a be the inverse of the covariance matrix. H ( θ ) is the conjugate transpose of the guide vector; a range of arrival angles is set, and an angle step size is set. Several angle values ​​are selected within the range of arrival angles according to the angle step size. The value of P(θ) is obtained sequentially for each angle value, resulting in a set of function values. The maximum value P(θ) within the set of function values ​​is then obtained. max To obtain the maximum value P(θ) max The angle value corresponding to θ is denoted as the angle of arrival of the component signal relative to the antenna array.

6. A high-precision radar positioning method for obstacle avoidance according to claim 1, characterized in that, In step S2, the process of time delay estimation for each component signal includes: Let the detected signal be denoted as r(t), and for any component signal, let the component signal be denoted as s(t). Perform cross-correlation calculation on the detected signal and the component signals to obtain the cross-correlation function. Where k is the preset discrete delay step number and n is the index of the sampling point; obtain the cross-correlation function R rs When (k) reaches its maximum value, the corresponding discrete delay step number k max Then the relative time delay value Trel=k of the component signal is obtained. max / fs, where fs is the sampling rate.

7. A high-precision radar positioning method for obstacle avoidance according to claim 1, characterized in that, In step S3, the process of setting the delay threshold includes: Based on the prior information, the distances between all known reflectors and the radar's antenna array are obtained, and the minimum value d of these distances is selected. min Then we get the minimum extra distance L. min =2d min And obtain the minimum multipath delay t min =L min / c, where the minimum multipath delay is denoted as the delay threshold, and c is the speed of light.

8. A high-precision radar positioning method for obstacle avoidance according to claim 1, characterized in that, In step S3, the process of determining whether the delayed component signal originates from a known reflector includes: Based on the positioning information of each known reflector in the prior information and the origin in the coordinate system, the direction angle of each known reflector relative to the origin is obtained; for any delay component, the angle of arrival of the delay component signal and the angle deviation of each direction angle are obtained in sequence. If any angle deviation is less than or equal to a preset angle deviation threshold, it is determined that the delay component signal originates from a known reflector.

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