A millimeter wave radar height detection system and a detection method thereof

Abstract

The present application relates to the technical field of millimeter wave radar detection, and particularly relates to a millimeter wave radar height detection system and a detection method thereof, which comprises: a millimeter wave radar module that emits millimeter wave radar signals to a human body detection area and receives echo signals formed by the reflection of the human body and the ground; a signal preprocessing module that performs low-pass filtering processing on the echo signals to obtain radar intermediate frequency signals; a target detection module that performs constant false alarm rate (CFAR) detection on the radar intermediate frequency signals to generate target distance distribution data; a ground occlusion area detection module that identifies a continuous ground echo interface and detects a ground echo occlusion area formed by the occlusion of the human body, so as to determine the detection area of the human body; a human body structure identification module that identifies a human body scattering structure and determines the upper boundary and the lower boundary of the human body scattering structure; and a height calculation module that determines the height of the human body according to the distance difference between the upper and lower boundaries of the human body scattering structure. The present application can accurately determine the human body detection area in the presence of ground echo interference.

Description

Technical Field

[0001] This invention relates to the field of millimeter-wave radar detection technology, and in particular to a millimeter-wave radar height detection system and its detection method. Background Technology

[0002] Millimeter-wave radar is a sensing technology that uses electromagnetic waves for target detection and distance measurement. It features non-contact measurement, strong environmental adaptability, and insensitivity to lighting conditions, making it widely used in human body detection, smart home devices, and health monitoring equipment. In human height detection applications, millimeter-wave radar typically transmits radar signals to the detection area and receives the echo signals reflected from the human body and the ground. The target distance is then calculated based on the radar signal propagation time, thus enabling the detection of human height. For example, by processing the radar echo signal and combining it with target detection algorithms, the distance information corresponding to the human target can be obtained, allowing the calculation of the human height given the radar's installation height.

[0003] In practical applications, the human body and the ground are usually within the radar detection range at the same time. The human body echo and the ground echo are prone to overlap or mutual interference in the distance dimension data, which makes it difficult to accurately determine the detection area of ​​the human body, and thus affects the accuracy of subsequent human structure recognition and height calculation. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides a millimeter-wave radar height detection system and its detection method, aiming to improve the problem of easy aliasing or mutual interference between human body echo and ground echo in distance dimension data.

[0005] In a first aspect, the present invention provides the following technical solution: a millimeter-wave radar height detection system, comprising the following modules: The millimeter-wave radar module is used to transmit millimeter-wave radar signals to the human body detection area and receive echo signals reflected by the human body and the ground. The signal preprocessing module is used to perform low-pass filtering on the echo signal to obtain the radar intermediate frequency signal; The target detection module is used to perform constant false alarm rate (CFAR) detection on the radar intermediate frequency signal to detect human echo targets and generate target distance distribution data. The ground obstruction area detection module is used to identify the ground echo continuity interface in the target distance distribution data, and detect areas in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted. The area is identified as the ground echo obstruction area formed by the human body blocking the millimeter wave signal, thereby determining the detection area where the human body is located. The human body structure recognition module is used to identify human body scattering structures that form a continuous scattering distribution along the vertical direction within the detection area where the human body is located, and to determine the upper and lower boundaries of the human body scattering structures based on the changes in scattering intensity. The height calculation module is used to determine a person's height based on the distance difference between the top of the head (corresponding to the upper boundary of the human body's scattering structure) and the bottom (corresponding to the lower boundary of the human body's bottom).

[0006] By adopting the above technical solution, it is possible to identify the continuous interface of ground echo in the target distance distribution data, and detect the area in the continuous interface of ground echo where the echo intensity is significantly reduced and the continuity is interrupted. This area is identified as the ground echo occlusion area formed by human body occlusion, thereby determining the detection area of ​​human body. This achieves accurate identification of human body detection area and solves the problem that human body echo and ground echo are prone to overlap or mutual interference in distance dimension data, making it difficult to determine the detection area of ​​human body.

[0007] Preferably, in the millimeter-wave radar module, the step of transmitting millimeter-wave radar signals to the human body detection area and receiving echo signals reflected from the human body and the ground includes: Millimeter-wave radar signals are periodically emitted into the human detection area, and the millimeter-wave radar signals are reflected by the human body and the ground during propagation to form echo signals. The system receives echo signals and samples them to obtain the echo signal strength at different distances. Echo signal intensity data are generated and distributed along the vertical detection direction.

[0008] Preferably, in the signal preprocessing module, the step of performing low-pass filtering on the echo signal to obtain the radar intermediate frequency signal includes: Acquire time-series data of the echo signal; The time series data is low-pass filtered according to a preset cutoff frequency to remove high-frequency noise components in the echo signal. The intermediate frequency component in the echo signal is retained to form a radar intermediate frequency signal for human target detection.

[0009] Preferably, in the target detection module, the constant false alarm rate (CFAR) detection of the radar intermediate frequency signal includes: Set the unit to be detected in the range dimension data corresponding to the radar intermediate frequency signal, and select a preset number of reference units on both sides of the unit to be detected; Calculate the background power value based on the echo signal strength of the reference unit; The detection threshold is calculated based on the background power value and the preset threshold factor; The echo signal intensity of the unit to be detected is compared with the detection threshold. When the echo signal intensity is greater than the detection threshold, the position of the unit to be detected is determined to be the target echo.

[0010] Preferably, in the ground obstruction area detection module, identifying the ground echo continuity interface in the target distance distribution data includes: Perform a distance dimension scan on the target distance distribution data to obtain the echo signal intensity corresponding to different distance positions; Identify distance segments with continuous and stable echo intensity based on echo signal strength; The distance segment is defined as the ground echo continuity interface.

[0011] Preferably, in the ground obstruction area detection module, the regions in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted include: Detect changes in echo signal intensity along the distance direction in a continuous ground echo interface; When the detected echo signal strength is lower than the preset threshold and the echo signal strength is interrupted within a continuous distance segment, the corresponding area is determined to be the echo strength attenuation area. The ground echo blocking area formed by the human body blocking millimeter-wave signals is determined based on the echo intensity attenuation area.

[0012] Preferably, in the human body structure recognition module, the step of recognizing the human body scattering structure that forms a continuous scattering distribution along the vertical direction within the detection area where the human body is located includes: Scan the target distance distribution data along the vertical detection direction within the detection area where the human body is located to obtain the echo signal intensity corresponding to different distance positions; Identify scattering regions where the echo intensity is continuous and the height range matches the height characteristics of a human body based on the echo signal intensity. The scattering region was determined to be the human body's scattering structure.

[0013] Preferably, in the human body structure recognition module, determining the upper and lower boundaries of the human body scattering structure based on changes in scattering intensity includes: Detect changes in echo signal intensity along the vertical detection direction in the human body's scattering structure; The location where the echo signal intensity abruptly changes from background noise to the human body scattering signal is defined as the upper boundary of the human body scattering structure. The location where the echo signal intensity changes from the human body scattering signal to the ground scattering signal is determined as the lower boundary of the human body scattering structure.

[0014] Preferably, in the height calculation module, determining the human height based on the distance difference between the top of the head corresponding to the upper boundary of the human body's scattering structure and the bottom of the body corresponding to the lower boundary includes: Obtain the top-of-the-head distance corresponding to the upper boundary of the human body scattering structure and the bottom-of-the-body distance corresponding to the lower boundary of the human body scattering structure; The distance difference between the top of the head and the bottom is calculated, and the distance difference is determined as the height of the human body.

[0015] Secondly, the present invention provides the following technical solution: a millimeter-wave radar height detection method, the method comprising: S1. Transmit millimeter-wave radar signals to the human body detection area and receive echo signals reflected by the human body and the ground. S2. Perform low-pass filtering on the echo signal to obtain the radar intermediate frequency signal; S3. Perform constant false alarm rate (CFAR) detection on the radar intermediate frequency signal to detect human echo targets and generate target distance distribution data. S4. Identify the ground echo continuity interface in the target distance distribution data, and detect the area in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted. Determine the area as the ground echo blocking area formed by the human body blocking the millimeter wave signal, thereby determining the detection area where the human body is located. S5. Identify the human body scattering structure that forms a continuous scattering distribution along the vertical direction within the detection area where the human body is located, and determine the upper and lower boundaries of the human body scattering structure based on the change in scattering intensity. S6. Determine the height of a person based on the distance difference between the top of the head corresponding to the upper boundary of the human body's scattering structure and the bottom of the body corresponding to the lower boundary.

[0016] The present invention has the following beneficial effects: 1. In this invention, by identifying the ground echo continuity interface in the target distance distribution data and detecting the area where the echo intensity decreases and the continuity is interrupted in the ground echo continuity interface, the ground echo obstruction area formed by human body obstruction is determined, thereby realizing the accurate positioning of the detection area where the human body is located and solving the problem that the human body target and ground echo overlap during the millimeter wave radar detection process makes it difficult to determine the human body position.

[0017] 2. In this invention, by identifying the human body scattering structure that forms a continuous scattering distribution along the vertical direction within the detection area where the human body is located, and determining the upper and lower boundaries of the human body scattering structure based on the change in scattering intensity, stable identification of the boundaries of the human body scattering structure is achieved, solving the problem of unstable identification of human body structure caused by environmental clutter or discrete echo interference.

[0018] 3. In this invention, by obtaining the distance from the top of the head corresponding to the upper boundary of the human body scattering structure and the distance from the bottom corresponding to the lower boundary, and determining the height of the human body based on the distance difference between the two, the height calculation based on the boundary of the human body scattering structure is realized, which solves the problem of difficulty in accurately extracting the effective height information of the human body in the traditional millimeter-wave radar height detection process. Attached Figure Description

[0019] Figure 1 This is an architectural diagram of a millimeter-wave radar height detection system proposed in this invention; Figure 2 This is a flowchart of a millimeter-wave radar height detection method proposed in this invention. Detailed Implementation

[0020] The technical solutions in 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.

[0021] Example 1: In a first embodiment of the present invention, a millimeter-wave radar height detection system is provided, such as... Figure 1 As shown, it includes the following modules: The millimeter-wave radar module is used to transmit millimeter-wave radar signals to the human body detection area and receive echo signals reflected by the human body and the ground. Furthermore, in the millimeter-wave radar module, the step of transmitting millimeter-wave radar signals to the human body detection area and receiving echo signals reflected from the human body and the ground includes: Millimeter-wave radar signals are periodically emitted into the human detection area, and the millimeter-wave radar signals are reflected by the human body and the ground during propagation to form echo signals. The system receives echo signals and samples them to obtain the echo signal strength at different distances. Echo signal intensity data are generated and distributed along the vertical detection direction.

[0022] Specifically, the millimeter-wave radar module is used to transmit millimeter-wave radar signals to the human body detection area and receive echo signals reflected from the human body and the ground. The millimeter-wave radar module may include a millimeter-wave radar chip, a transmitting antenna, and a receiving antenna. The millimeter-wave radar chip integrates a radar transceiver and a transceiver antenna control unit. It generates millimeter-wave radar signals through the transmitting end and radiates them to the human body detection area through the transmitting antenna. The receiving antenna is used to receive echo signals reflected from the human body surface and the ground. In one possible implementation, the millimeter-wave radar module can be installed above the human body detection area, so that the radar signal propagates along the vertical detection direction, thereby creating different echo distributions in the distance dimension for the human head, the human body, and the ground. Through the above method, echo information within the human body detection area can be acquired, providing raw detection data for subsequent signal processing. The millimeter-wave radar module continuously scans the human detection area by periodically transmitting millimeter-wave radar signals. This periodic transmission is controlled by the radar chip's internal control unit. In each detection cycle, a millimeter-wave radar signal is transmitted to the human detection area, causing it to be reflected by both the human body and the ground during its spatial propagation, forming echo signals. Because the human body has a continuous spatial structure from head to toe, it generates scattered echoes of varying intensities at different heights. The ground typically forms a relatively continuous planar reflective interface, resulting in a stable echo distribution across the range dimension. Upon receiving the echo signal, the receiving antenna inputs it to the radar receiving channel for signal conditioning, such as amplification and basic filtering, to ensure the echo signal falls within an amplitude range suitable for subsequent digital processing. The received echo signal is sampled to obtain the echo signal intensity corresponding to different distance positions. The sampling process can be implemented by an analog-to-digital converter (ADC) to convert the continuous analog echo signal into a discrete digital signal, thereby forming an echo signal time series. The echo time series can be represented as follows: ;in, Indicates the first The amplitude of the echo signal at each sampling point This indicates the sampling point number; by extracting the amplitude or power from the time series, the echo signal strength data at the corresponding sampling location can be obtained; in one possible implementation, the echo signal strength can be calculated using the absolute value of the amplitude, i.e. ;in Indicates the first The echo signal intensity corresponding to each sampling point; in this way, the echo time series can be converted into echo signal intensity data that reflects the target scattering intensity distribution; To establish the correspondence between sampling points and spatial distances, distance mapping processing of the echo data is required based on the radar signal propagation time. When a radar signal is emitted from the transmitter, reflects off the target, and returns to the receiver, its propagation distance can be calculated using the signal propagation time. The distance calculation relationship is as follows: ; in Indicates the distance to the target. This indicates the speed at which electromagnetic waves propagate through the air. This represents the propagation time of a radar signal from transmission to reception; this distance calculation relationship can be used to convert the echo signal time series into range-dimensional data, thereby obtaining the echo signal intensity distribution corresponding to different distance positions; Arranging the aforementioned distance data in distance order creates echo signal intensity data distributed along the vertical detection direction. Since millimeter-wave radar modules are typically installed above the human detection area and perform detection vertically, different distance positions correspond to different height positions of the human body in the vertical direction. This method allows for the spatial distribution of echo intensity of the human head, the human body itself, and the ground. This echo signal intensity data reflects the scattering characteristics of the human body and the ground at different heights, providing fundamental input data for subsequent low-pass filtering, constant false alarm rate target detection, ground echo continuous interface recognition, and human structure boundary determination. Through this process, a complete signal acquisition flow can be achieved, from millimeter-wave radar signal transmission, echo reception, signal sampling to distance mapping and echo intensity data construction, thus providing fundamental data support for subsequent human height detection.

[0023] The signal preprocessing module is used to perform low-pass filtering on the echo signal to obtain the radar intermediate frequency signal; Furthermore, in the signal preprocessing module, the step of performing low-pass filtering on the echo signal to obtain the radar intermediate frequency signal includes: Acquire time-series data of the echo signal; The time series data is low-pass filtered according to a preset cutoff frequency to remove high-frequency noise components in the echo signal. The intermediate frequency component in the echo signal is retained to form a radar intermediate frequency signal for human target detection.

[0024] Specifically, the signal preprocessing module processes the echo signal received by the millimeter-wave radar module to obtain a radar intermediate frequency signal suitable for subsequent target detection. After the millimeter-wave radar module transmits the millimeter-wave radar signal in the human detection area and receives the echo signal formed by the human body and ground reflection, the echo signal first enters the signal preprocessing module for processing. The signal preprocessing module can be implemented by the signal processing unit inside the radar chip or the MCU processing module, for example, by using an embedded processor to perform digital signal processing on the echo signal. The signal preprocessing module can suppress high-frequency noise in the original echo signal, so that the signal retains the effective frequency components of the human body scattered echo, thereby providing a stable input signal for subsequent human target detection. The signal preprocessing module first acquires the time-series data of the echo signal; after analog-to-digital conversion at the receiving end, the echo signal is converted into a discrete digital signal, thus obtaining the sampling sequence of the echo signal on the time axis; this time series can be represented as ;in Indicates the first The amplitude of the echo signal at each sampling point This indicates the sampling point number; time series data can reflect the distribution of echoes generated by the human body and the ground at different propagation times and locations, providing input data for subsequent filtering processing. Low-pass filtering is applied to time series data according to a preset cutoff frequency to remove high-frequency noise components from the echo signal. Low-pass filtering can be implemented using digital filtering algorithms, such as the finite impulse response (FIR) filtering algorithm. FIR is a digital signal processing method that filters signals through convolution operations, and its output signal can be expressed as: ; in This represents the filtered output signal. This represents the input time series signal. Represents the filter coefficients. Indicates the filter order. This indicates the filter coefficient number; by setting the filter coefficients, the signal can pass through within a preset cutoff frequency, while attenuating high-frequency noise components above the cutoff frequency. The low-pass filtering process described above can preserve the intermediate frequency (IF) component in the echo signal, thereby forming a radar IF signal for human target detection. The radar IF signal can reflect the echo distribution characteristics of the human body and the ground in the range dimension and provide a basic signal input for subsequent constant false alarm rate (CFAR) target detection processing. Through this processing flow, noise suppression and effective signal extraction of the original echo signal can be achieved, thus completing the signal preprocessing process in the millimeter-wave radar height detection system.

[0025] The target detection module is used to perform constant false alarm rate (CFAR) detection on the radar intermediate frequency signal to detect human echo targets and generate target distance distribution data. Furthermore, in the target detection module, the constant false alarm rate (CFAR) detection of the radar intermediate frequency signal includes: Set the unit to be detected in the range dimension data corresponding to the radar intermediate frequency signal, and select a preset number of reference units on both sides of the unit to be detected; Calculate the background power value based on the echo signal strength of the reference unit; The detection threshold is calculated based on the background power value and the preset threshold factor; The echo signal intensity of the unit to be detected is compared with the detection threshold. When the echo signal intensity is greater than the detection threshold, the position of the unit to be detected is determined to be the target echo.

[0026] Specifically, the target detection module performs constant false alarm rate (CFAR) detection on the radar intermediate frequency (IF) signal output by the signal preprocessing module, thereby identifying human echo targets in the range dimension data and forming target range distribution data. Even after low-pass filtering, the radar IF signal still contains various signal components such as human body scattering echoes, ground reflection echoes, and environmental clutter. Therefore, an adaptive target detection method is needed to determine valid targets. CFAR detection is a target detection method that estimates local background power and adaptively adjusts the detection threshold. This method can maintain a relatively stable false alarm probability at different distances, thus achieving reliable target detection even with background changes. The target detection module first divides the range dimension data corresponding to the radar intermediate frequency signal into multiple continuous range units, each corresponding to a range position in the detection space. During the detection process, the current range unit is selected as the unit to be detected, and a preset number of reference units are selected on both sides of the unit to be detected to estimate the local background power. The reference units are usually located in the range segment near the unit to be detected to reflect the echo energy distribution in the vicinity. By setting multiple reference units, the impact of individual echo fluctuations on background estimation can be reduced, making the background power estimation more stable. The background power value is calculated based on the echo signal strength of the reference unit; for ease of description, the first... The echo signal intensity of each reference cell is denoted as ;in Indicates the first The echo signal power or amplitude of each reference cell is a characteristic quantity. The reference element number is represented by , and the number of reference elements is denoted as . The background power value is denoted as Background power can be calculated from the average value of the reference cells, and its expression is: ; in This indicates the background power level in the vicinity of the detected unit. This indicates the number of reference cells; the power estimate reflecting the level of local clutter or background echo can be obtained in the above way, providing a basis for subsequent threshold calculation; The detection threshold is calculated based on the background power value and a preset threshold factor; the detection threshold is denoted as... The threshold factor is denoted as The threshold factor is related to the expected false alarm probability and the number of reference units, and its value can be configured according to the system's detection requirements; the detection threshold can be expressed as: ; in This indicates the detection threshold of the current unit to be detected. Indicates the threshold factor. This represents the background power value; in this way, the detection threshold can be adaptively generated based on the background power at different distances, allowing the detection threshold to be adjusted as the background changes. The echo signal intensity of the unit to be detected is compared with a detection threshold to complete target determination; the echo signal intensity of the unit to be detected is denoted as... ;when When, it is determined that there is a target echo at the location corresponding to the current distance cell; when When the current distance cell is located, it is determined that the position corresponding to the current distance cell does not constitute a target echo. By moving the cell to be detected one by one along the distance dimension and repeating the above background power calculation, threshold calculation and comparison process, the target echo position that meets the detection conditions can be identified in the entire distance dimension data. By performing continuous constant false alarm rate (CFAR) detection on the range dimension data, the target echo distribution of the human body and the ground in the range dimension can be obtained. Recording the detected target echo positions in order of distance forms target range distribution data. This target range distribution data reflects the distribution characteristics of human body scattered echoes and ground reflected echoes at different range positions, and provides basic data input for subsequent identification of ground echo continuity interfaces, determination of the detection area where the human body is located, and extraction of human body scattering structure. Through the above processing flow, the target detection module realizes the conversion process from radar intermediate frequency signal to target range distribution data, thus constituting a key detection link in the signal processing flow of the millimeter-wave radar height detection system.

[0027] The ground obstruction area detection module is used to identify the ground echo continuity interface in the target distance distribution data, and detect areas in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted. The area is identified as the ground echo obstruction area formed by the human body blocking the millimeter wave signal, thereby determining the detection area where the human body is located. Furthermore, in the ground obstruction area detection module, identifying the ground echo continuity interface in the target distance distribution data includes: Perform a distance dimension scan on the target distance distribution data to obtain the echo signal intensity corresponding to different distance positions; Identify distance segments with continuous and stable echo intensity based on echo signal strength; The distance segment is defined as the ground echo continuity interface.

[0028] Furthermore, in the ground obstruction area detection module, the regions in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted include: Detect changes in echo signal intensity along the distance direction in a continuous ground echo interface; When the detected echo signal strength is lower than the preset threshold and the echo signal strength is interrupted within a continuous distance segment, the corresponding area is determined to be the echo strength attenuation area. The ground echo blocking area formed by the human body blocking millimeter-wave signals is determined based on the echo intensity attenuation area.

[0029] Specifically, the ground obstruction zone detection module is used to identify the ground echo continuity interface in the target distance distribution data, and on the basis of this ground echo continuity interface, detect the echo attenuation area formed by the human body blocking the millimeter-wave signal, thereby determining the detection area where the human body is located. When the millimeter-wave radar is installed above the human body detection area, the radar signal propagates downward and generates reflected echoes on the human body surface and the ground. Because the ground has a relatively continuous planar structure, its echoes usually present as continuous and relatively stable echo segments in the distance dimension. When a human body is in the detection area, the human body will block part of the millimeter-wave signal from reaching the ground, causing the ground echo at the corresponding location to weaken or be interrupted. By utilizing this echo change characteristic, the spatial area where the human body is located can be identified in the distance dimension data. The ground obstruction area detection module first performs a distance dimension scan on the target distance distribution data to obtain the echo signal intensity corresponding to different distance positions; the distance positions are denoted as... The echo signal strength corresponding to this distance position is denoted as ;in Indicates the first A distance location, This indicates the echo signal strength corresponding to that distance; by measuring along the distance direction... By performing sequential scanning, the distribution of echo intensity as a function of distance within the entire detection area can be obtained. When the ground is unobstructed, the change in echo intensity between adjacent distances is usually small and continuous. Therefore, the ground echo continuity interface can be determined based on the distance segment where the echo intensity is continuous and stable. After identifying the continuous interface of ground echoes, the changes in echo signal intensity within this interface are further detected to identify areas where the echo intensity is significantly reduced and the continuity is interrupted. When a human body is located between the radar and the ground, the human body will block part of the millimeter-wave signal, causing the ground echo intensity at the corresponding distance to decrease. When the echo signal intensity in a certain distance segment is lower than a preset threshold and this low-intensity state occurs at continuous distance positions, this distance segment can be identified as an echo intensity attenuation area. This echo intensity attenuation area corresponds to the ground echo blocking area formed by the human body blocking the millimeter-wave signal. The detection area of ​​the human body can be determined by the location range of the echo intensity attenuation region in the distance dimension. Since the human body is located between the radar and the ground, the spatial region above the ground echo blockage area corresponds to the location of the human body. Through this process, the detection area of ​​the human body can be determined in the target distance distribution data, thereby providing spatial range constraints for subsequent human body scattering structure recognition and determination of the upper and lower boundaries of the human body.

[0030] The human body structure recognition module is used to identify human body scattering structures that form a continuous scattering distribution along the vertical direction within the detection area where the human body is located, and to determine the upper and lower boundaries of the human body scattering structures based on the changes in scattering intensity. Furthermore, in the human body structure recognition module, the identification of human body scattering structures forming a continuous scattering distribution along the vertical direction within the detection area where the human body is located includes: Scan the target distance distribution data along the vertical detection direction within the detection area where the human body is located to obtain the echo signal intensity corresponding to different distance positions; Identify scattering regions where the echo intensity is continuous and the height range matches the height characteristics of a human body based on the echo signal intensity. The scattering region was determined to be the human body's scattering structure.

[0031] Furthermore, in the human body structure recognition module, determining the upper and lower boundaries of the human body scattering structure based on changes in scattering intensity includes: Detect changes in echo signal intensity along the vertical detection direction in the human body's scattering structure; The location where the echo signal intensity abruptly changes from background noise to the human body scattering signal is defined as the upper boundary of the human body scattering structure. The location where the echo signal intensity changes from the human body scattering signal to the ground scattering signal is determined as the lower boundary of the human body scattering structure.

[0032] Specifically, the human structure recognition module is used to identify the human body scattering structure that forms a continuous scattering distribution along the vertical direction within the detection area of ​​the human body, and to determine the upper and lower boundaries of the human body scattering structure based on this scattering structure. When the millimeter-wave radar emits radar signals vertically above the human body detection area, the human head, torso, and lower limbs will form continuously distributed scattering echoes in the range dimension, while the ground usually forms relatively stable planar reflected echoes. Therefore, given that the detection area of ​​the human body has been determined, the continuous distribution characteristics of the human body scattering echoes in the vertical direction and the intensity variation relationship between the human body scattering echoes and the background echoes and ground echoes can be used to identify the human body scattering structure and extract the corresponding structural boundaries, thereby providing basic data for subsequent human height calculation. To determine the upper boundary of the human body scattering structure, a gradient detection algorithm based on the first derivative of the signal is employed. By differentiating the echo power spectrum within the detection area of ​​the human body, the rate of change of the echo signal intensity is calculated, and the first step position with the largest rate of change that meets the preset signal-to-noise ratio requirement is identified as the upper boundary of the human body scattering structure. This method does not rely on the absolute amplitude of the echo signal. Even when the echo from above the human head is weak due to hair scattering or wearing a hat, it can still accurately extract the location of the initial reflection interface in physical space, effectively avoiding boundary positioning errors caused by echo intensity fluctuations. The human structure recognition module first scans the target distance distribution data along the vertical detection direction within the detection area where the human body is located to obtain the echo signal intensity corresponding to different distance positions. By sequentially reading the echo signal intensity at each distance position, the vertical echo intensity distribution within the detection area where the human body is located can be obtained. Since the human body forms a continuous structure in space from head to feet, the human body echo usually appears as a continuously distributed scattering area in the distance dimension, while background noise or environmental clutter usually appears as a discrete or discontinuous distribution. Based on this characteristic, the scattering area with continuous echo intensity and a height range that meets the human body height characteristics can be identified according to the continuity of the echo signal intensity in the distance dimension, and this scattering area can be identified as the human body scattering structure. The human body height characteristics can be set according to the system application scenario, for example, limiting the height range of the continuous scattering section to the height range where the human body may appear, thereby avoiding misidentification of local stray echoes as human structures. After identifying the human body scattering structure, it is necessary to further determine the upper and lower boundaries of the human body scattering structure based on the changes in scattering intensity. The echo signal intensity within the human body scattering structure is continuously detected along the vertical detection direction. When the echo signal intensity suddenly increases from the background echo level and enters the human body scattering echo segment, the location of this intensity change can be determined as the upper boundary of the human body scattering structure, which corresponds to the top of the human head. Continuing to detect downwards along the vertical detection direction, when the echo signal intensity gradually transitions from human body scattering echo to ground reflection echo, the transition location can be determined as the lower boundary of the human body scattering structure, which corresponds to the scattering transition interface between the human feet and the ground. After determining the distance positions corresponding to the upper and lower boundaries of the human body's scattering structure, the distance to the top of the head and the distance to the bottom of the body can be obtained. In millimeter-wave radar systems, there is a correspondence between distance position and echo propagation time; the target distance can be calculated using the radar signal propagation time, and the distance relationship satisfies: ; in Indicates the distance between the radar and the target. This indicates the speed at which electromagnetic waves propagate through the air. This represents the propagation time of the radar signal from transmission to reception. Using the aforementioned distance relationship, the echo positions corresponding to the upper and lower boundaries of the human body's scattering structure can be converted into actual distance values, thereby obtaining the distance to the top of the human head and the distance to the bottom of the human body. This distance information is further used for subsequent height calculation. Through the above processing flow, the human body structure recognition module completes a continuous processing procedure from scanning the detection area where the human body is located, recognizing the human body's scattering structure, to extracting the structural boundaries, providing key structural parameters for height calculation in the millimeter-wave radar height detection system. To eliminate the impact of non-standard standing postures (such as looking down or slightly bending over) on height calculation, this system introduces temporal stability verification logic into the human body structure recognition module. The system performs sliding window smoothing on target distance distribution data across multiple consecutive frames and combines this with the lateral distribution characteristics of the ground occlusion area for comprehensive judgment. When an increase in the lateral width of the ground occlusion area is detected, and a momentary decrease in the longitudinal height of the human body's scattering structure is detected, the system determines that the current detection posture is non-ideal and automatically retrieves the historical peak frame data with the most stable height characteristics within that detection period for height calculation. This temporal compensation mechanism ensures that the output height result remains highly consistent and reliable even when the user's posture dynamically changes.

[0033] The height calculation module is used to determine a person's height based on the distance difference between the top of the head (corresponding to the upper boundary of the human body's scattering structure) and the bottom (corresponding to the lower boundary of the human body's bottom).

[0034] Furthermore, in the height calculation module, determining the human height based on the distance difference between the top of the head corresponding to the upper boundary of the human body's scattering structure and the bottom of the body corresponding to the lower boundary includes: Obtain the top-of-the-head distance corresponding to the upper boundary of the human body scattering structure and the bottom-of-the-body distance corresponding to the lower boundary of the human body scattering structure; The distance difference between the top of the head and the bottom is calculated, and the distance difference is determined as the height of the human body.

[0035] Specifically, the height calculation module determines a person's height based on the distance difference between the top of the head (corresponding to the upper boundary of the human body's scattering structure) and the bottom of the body (corresponding to the lower boundary of the human body's scattering structure). After the human body structure recognition module completes continuous scattering structure recognition within the detection area of ​​the human body, it can further obtain the upper boundary corresponding to the top of the human head and the lower boundary corresponding to the scattering transition interface between the human feet and the ground. The height calculation module processes the distance information corresponding to these two boundary positions, thereby converting the structural boundary results obtained in the previous stage into the final height result. This processing method is integrated with the overall process of millimeter-wave radar height detection, that is, after radar transmission and reception, signal preprocessing, target detection, ground obstruction area detection, and human body structure recognition are completed, the height calculation module determines the height value. The height calculation module first obtains the top-of-the-head distance corresponding to the upper boundary of the human body's scattering structure and the bottom-of-the-body distance corresponding to the lower boundary of the human body's scattering structure. The top-of-the-head distance corresponds to the distance of the top of the human head relative to the millimeter-wave radar module, and the bottom-of-the-body distance corresponds to the distance of the scattering transition interface between the human feet and the ground relative to the millimeter-wave radar module. These two distance values ​​can be directly read from the previous module based on the distance position of the boundary, or calculated from the echo propagation time corresponding to the boundary position. In one possible implementation, both the top-of-the-head distance and the bottom-of-the-body distance are obtained from the boundary positions in the distance dimension data, thus ensuring consistency between the height calculation and the previous boundary recognition results. The height calculation module calculates the difference between the distance from the top of the head and the distance from the bottom of the body, and determines this difference as the human height; the distance from the top of the head is recorded as... ;in, The distance from the top of the head to the upper boundary of the human body's scattering structure is represented by ; the distance from the bottom of the human body is denoted as . ;in, This represents the bottom distance corresponding to the lower boundary of the human body's scattering structure; the human body height is denoted as... ;in, This represents the human height value; the calculation relationship for human height can be expressed as: ; This calculation shows that human height is determined by the difference between the distance from the bottom of the human body and the distance from the top of the human head. Since both the distance from the top of the head and the distance from the bottom of the human body originate from the boundary of the human body's scattering structure under the same detection direction, the spatial dimensions of the human body in the vertical detection direction can be directly reflected by the distance difference. After completing the distance difference calculation, the height calculation module can output the height value as the system output for external devices to call or display. For example, in the application scenario of height and weight scales, the height value can be sent to the display unit or host computer system through the communication interface module for subsequent display, storage or health data processing. Through the above processing, the height calculation module completes the process of obtaining the human height value from the distance of the human body scattering structure boundary, so that the structural features identified by the front-end modules are finally converted into human height detection results. The distance difference calculation method employed in this invention is essentially based on the strong coupling relationship between the physical space occupied by the human body and the electromagnetic wave reflection interface. Because the system simultaneously locks the upper boundary (top of the head) and lower boundary (ground transition zone) of the human body, this dual-reference point offset compensation mechanism can offset system errors caused by minor radar installation sway or overall human body displacement. Compared to the traditional method that relies solely on subtracting the top-of-the-head distance from the radar installation height, this solution transforms the originally uncontrollable changes in human body scattering distribution into a quantifiable spatial geometric relationship by capturing the relative difference between the two boundaries of the human body in real time, thereby achieving high-precision height measurement.

[0036] Example 2: In some applications of height detection equipment, such as millimeter-wave radar height detection devices installed in intelligent height and weight detection equipment or indoor human body detection equipment, the millimeter-wave radar is usually installed above the human body and performs vertical detection of the human body detection area. During actual detection, the human body and the ground are usually within the radar detection range simultaneously. Because the human body echo and the ground echo are prone to overlap or mutual interference in the distance dimension data, it is difficult to accurately determine the detection area of ​​the human body, thus affecting the accuracy of human structure recognition and height calculation. To solve the above problems, this invention provides a millimeter-wave radar height detection method, the structure of which is as follows... Figure 2 As shown. The specific implementation process of this method is as follows: S1. Transmit millimeter-wave radar signals to the human body detection area and receive echo signals reflected by the human body and the ground. S2. Perform low-pass filtering on the echo signal to obtain the radar intermediate frequency signal; S3. Perform constant false alarm rate (CFAR) detection on the radar intermediate frequency signal to detect human echo targets and generate target distance distribution data. S4. Identify the ground echo continuity interface in the target distance distribution data, and detect the area in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted. Determine the area as the ground echo blocking area formed by the human body blocking the millimeter wave signal, thereby determining the detection area where the human body is located. S5. Identify the human body scattering structure that forms a continuous scattering distribution along the vertical direction within the detection area where the human body is located, and determine the upper and lower boundaries of the human body scattering structure based on the change in scattering intensity. S6. Determine the height of a person based on the distance difference between the top of the head corresponding to the upper boundary of the human body's scattering structure and the bottom of the body corresponding to the lower boundary.

[0037] Specifically, in step S1, the millimeter-wave radar module periodically transmits millimeter-wave radar signals to the human body detection area. During propagation, the millimeter-wave radar signals are reflected by the human body surface and the ground to form echo signals. The millimeter-wave radar module receives the reflected echoes and performs sampling processing to obtain echo signal intensity data corresponding to different distance positions, forming echo signal data distributed along the vertical detection direction. In practical application scenarios, the millimeter-wave radar is usually installed above the human body and detects downwards. Therefore, the human body and the ground will appear in the detection range at the same time, so the received echo signal includes both human body reflected echoes and ground reflected echoes. In step S2, the received echo signal is preprocessed to remove high-frequency noise components from the echo signal. Specifically, the echo signal is sampled to obtain time series data of the echo signal, and the time series data is low-pass filtered according to a preset cutoff frequency to filter out high-frequency noise components in the echo signal and retain the intermediate frequency components in the echo signal to form a radar intermediate frequency signal for target detection. In step S3, constant false alarm rate (CFAR) detection is performed on the radar intermediate frequency signal to identify human echo targets and generate target range distribution data. A target unit is set in the range dimension data corresponding to the radar intermediate frequency signal, and a certain number of reference units are selected on both sides of the target unit. The background power value is obtained by statistically calculating the echo signal intensity of the reference units, and a detection threshold is calculated based on the background power value and a preset threshold factor. The echo signal intensity of the target unit is compared with the detection threshold. When the echo signal intensity of the target unit is greater than the detection threshold, it is determined that a target echo exists at that location, thereby obtaining target range distribution data. In step S4, the ground echo continuity interface is identified in the target range distribution data, and areas in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted are detected. Since the ground usually has continuous and stable reflection characteristics, it appears as a segment with continuous and stable echo intensity in the range dimension data. Therefore, the ground echo continuity interface can be identified by scanning the target range distribution data in the range dimension. When a human body is located between the radar and the ground, the human body will block some millimeter wave signals, causing the ground echo intensity to decrease or the continuity to be interrupted at the corresponding location. Therefore, the area where the echo intensity decreases and the continuity is interrupted can be identified as the ground echo blocking area formed by the human body blocking the signal, and the detection area where the human body is located can be determined based on the blocking area. In step S5, the target distance distribution data is scanned along the vertical detection direction within the detection area where the human body is located. Based on the echo signal intensity, a scattering area with continuous echo intensity and a height range that meets the height characteristics of the human body is identified, and this scattering area is determined as the human body scattering structure. After identifying the human body scattering structure, the upper and lower boundaries of the human body scattering structure are further determined based on the change in scattering intensity. Specifically, when the echo signal intensity changes abruptly from background noise to human body scattering signal, this location is determined as the upper boundary of the human body scattering structure, and when the echo signal intensity changes from human body scattering signal to ground scattering signal, this location is determined as the lower boundary of the human body scattering structure. In step S6, the height of the human body is determined based on the distance difference between the top of the head corresponding to the upper boundary of the human body scattering structure and the bottom of the body corresponding to the lower boundary. Specifically, the top of the head corresponding to the upper boundary of the human body scattering structure and the bottom of the body scattering structure corresponding to the lower boundary of the human body scattering structure are obtained, and the height of the human body is calculated based on the distance difference between the two, thereby obtaining the final height detection result of the human body.

[0038] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A millimeter-wave radar height detection system, characterized in that, Includes the following modules: The millimeter-wave radar module is used to transmit millimeter-wave radar signals to the human body detection area and receive echo signals reflected by the human body and the ground. The signal preprocessing module is used to perform low-pass filtering on the echo signal to obtain the radar intermediate frequency signal; The target detection module is used to perform constant false alarm rate (CFAR) detection on the radar intermediate frequency signal to detect human echo targets and generate target distance distribution data. The ground obstruction area detection module is used to identify the ground echo continuity interface in the target distance distribution data, and detect areas in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted. The area is identified as the ground echo obstruction area formed by the human body blocking the millimeter wave signal, thereby determining the detection area where the human body is located. The human body structure recognition module is used to identify human body scattering structures that form a continuous scattering distribution along the vertical direction within the detection area where the human body is located, and to determine the upper and lower boundaries of the human body scattering structures based on the changes in scattering intensity. The height calculation module is used to determine a person's height based on the distance difference between the top of the head (corresponding to the upper boundary of the human body's scattering structure) and the bottom (corresponding to the lower boundary of the human body's bottom).

2. The millimeter-wave radar height detection system according to claim 1, characterized in that, In the millimeter-wave radar module, the step of transmitting millimeter-wave radar signals to the human body detection area and receiving echo signals reflected from the human body and the ground includes: Millimeter-wave radar signals are periodically emitted into the human detection area, and the millimeter-wave radar signals are reflected by the human body and the ground during propagation to form echo signals. The system receives echo signals and samples them to obtain the echo signal strength at different distances. Echo signal intensity data are generated and distributed along the vertical detection direction.

3. The millimeter-wave radar height detection system according to claim 1, characterized in that, In the signal preprocessing module, the step of performing low-pass filtering on the echo signal to obtain the radar intermediate frequency signal includes: Acquire time-series data of the echo signal; The time series data is low-pass filtered according to a preset cutoff frequency to remove high-frequency noise components in the echo signal. The intermediate frequency component in the echo signal is retained to form a radar intermediate frequency signal for human target detection.

4. The millimeter-wave radar height detection system according to claim 1, characterized in that, In the target detection module, the constant false alarm rate (CFAR) detection of the radar intermediate frequency signal includes: Set the unit to be detected in the range dimension data corresponding to the radar intermediate frequency signal, and select a preset number of reference units on both sides of the unit to be detected; Calculate the background power value based on the echo signal strength of the reference unit; The detection threshold is calculated based on the background power value and the preset threshold factor; The echo signal intensity of the unit to be detected is compared with the detection threshold. When the echo signal intensity is greater than the detection threshold, the position of the unit to be detected is determined to be the target echo.

5. The millimeter-wave radar height detection system according to claim 1, characterized in that, In the ground obstruction area detection module, identifying the ground echo continuity interface in the target distance distribution data includes: Perform a distance dimension scan on the target distance distribution data to obtain the echo signal intensity corresponding to different distance positions; Identify distance segments with continuous and stable echo intensity based on echo signal strength; The distance segment is defined as the ground echo continuity interface.

6. The millimeter-wave radar height detection system according to claim 1, characterized in that, In the ground obstruction area detection module, the regions in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted include: Detect changes in echo signal intensity along the distance direction in a continuous ground echo interface; When the detected echo signal strength is lower than the preset threshold and the echo signal strength is interrupted within a continuous distance segment, the corresponding area is determined to be the echo strength attenuation area. The ground echo blocking area formed by the human body blocking millimeter-wave signals is determined based on the echo intensity attenuation area.

7. The millimeter-wave radar height detection system according to claim 1, characterized in that, In the human body structure recognition module, the step of identifying the human body scattering structure that forms a continuous scattering distribution along the vertical direction within the detection area of ​​the human body includes: Scan the target distance distribution data along the vertical detection direction within the detection area where the human body is located to obtain the echo signal intensity corresponding to different distance positions; Identify scattering regions where the echo intensity is continuous and the height range matches the height characteristics of a human body based on the echo signal intensity. The scattering region was determined to be the human body's scattering structure.

8. The millimeter-wave radar height detection system according to claim 1, characterized in that, In the human body structure recognition module, determining the upper and lower boundaries of the human body scattering structure based on changes in scattering intensity includes: Detect changes in echo signal intensity along the vertical detection direction in the human body's scattering structure; The location where the echo signal intensity abruptly changes from background noise to the human body scattering signal is defined as the upper boundary of the human body scattering structure. The location where the echo signal intensity changes from the human body scattering signal to the ground scattering signal is determined as the lower boundary of the human body scattering structure.

9. A millimeter-wave radar height detection system according to claim 1, characterized in that, In the height calculation module, determining the human height based on the distance difference between the top of the head corresponding to the upper boundary of the human body's scattering structure and the bottom of the body corresponding to the lower boundary includes: Obtain the top-of-the-head distance corresponding to the upper boundary of the human body scattering structure and the bottom-of-the-body distance corresponding to the lower boundary of the human body scattering structure; The distance difference between the top of the head and the bottom is calculated, and the distance difference is determined as the height of the human body.

10. A height detection method using millimeter-wave radar, characterized in that, The method for a millimeter-wave radar height detection system according to any one of claims 1-9 comprises: S1. Transmit millimeter-wave radar signals to the human body detection area and receive echo signals reflected by the human body and the ground. S2. Perform low-pass filtering on the echo signal to obtain the radar intermediate frequency signal; S3. Perform constant false alarm rate (CFAR) detection on the radar intermediate frequency signal to detect human echo targets and generate target distance distribution data. S4. Identify the ground echo continuity interface in the target distance distribution data, and detect the area in the ground echo continuity interface where the echo intensity is significantly reduced and the continuity is interrupted. Determine the area as the ground echo blocking area formed by the human body blocking the millimeter wave signal, thereby determining the detection area where the human body is located. S5. Identify the human body scattering structure that forms a continuous scattering distribution along the vertical direction within the detection area where the human body is located, and determine the upper and lower boundaries of the human body scattering structure based on the change in scattering intensity. S6. Determine the height of a person based on the distance difference between the top of the head corresponding to the upper boundary of the human body's scattering structure and the bottom of the body corresponding to the lower boundary.

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