Pulse wave calibration method based on millimeter wave radar

Abstract

The invention discloses a pulse wave calibration method based on millimeter wave radar, which comprises the following steps: synchronously acquiring radar pulse waves and standard pulse waves, respectively storing the radar pulse waves and the standard pulse waves in a radar pulse wave matrix and a standard pulse wave matrix, and then normalizing two groups of pulse wave signals to eliminate amplitude difference; through differential and three-valued quantization processing, pulse wave change characteristics are extracted, alignment of radar pulse waves and standard pulse waves is realized through cross-correlation operation, a calibration matrix is generated by utilizing least square fitting based on aligned signals, and in actual use, signal distortion of radar pulse wave detection can be corrected based on the matrix, real-time calibration is realized, and the accuracy of radar pulse wave detection is improved. Signal deviation caused by individual difference, equipment interference and remote detection is eliminated, the precision and stability of long-time health monitoring are ensured, and the method is efficient, small in calculation burden and suitable for health management and remote monitoring application.

Description

Technical Field

[0001] The invention relates to the technical field of pulse wave calibration, and in particular to a pulse wave calibration method based on millimeter wave radar. Background Art

[0002] As the trend of population aging becomes increasingly prominent, the health of the elderly has received widespread attention from the society. Continuous monitoring of the health indicators of the elderly is of great significance to the health management and disease prevention of the elderly. Pulse wave is an important basis for judging the health status of the human body. Monitoring it can provide health information in many aspects, such as heart function, vascular health, blood circulation status, and physiological and pathological status of the human body. However, the current mainstream pulse wave monitoring solutions are mainly contact-based and not suitable for long-term monitoring. For this reason, the relevant fields have turned their attention to non-contact pulse wave monitoring solutions, among which the pulse wave monitoring solution based on millimeter wave radar is particularly popular.

[0003] In practical applications, pulse waves assist health diagnosis in two main ways: one is to directly monitor the pulse wave waveform, and medical staff interpret the waveform to assist in health analysis or disease diagnosis; the other is to automatically extract waveform features based on the monitored pulse wave, and analyze health indicators (such as blood pressure, heart rate, heart rate variability, etc.) according to expert models. Either implementation method is highly dependent on the accuracy of pulse wave monitoring. However, non-contact monitoring solutions such as millimeter wave radars have an uncertain degree of distortion in the monitored pulse wave due to long-distance detection, individual differences, and internal interference, which affects subsequent waveform interpretation or feature extraction, and may lead to diagnostic bias. Summary of the invention

[0004] Technical purpose: In view of the shortcomings of existing millimeter-wave radar in detecting pulse waves, the present invention discloses a pulse wave calibration method based on millimeter-wave radar, which can reduce pulse wave distortion and improve the accuracy of pulse wave monitoring.

[0005] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0006] A pulse wave calibration method based on millimeter wave radar specifically comprises the following steps:

[0007] Synchronously collect a set of radar pulse waves monitored by a radar unit and a standard pulse wave monitored by a standard unit, and store them in a radar pulse wave matrix and a standard pulse wave matrix respectively, wherein the standard unit is a contact pulse wave sensing unit;

[0008] Normalize the radar pulse wave matrix and the standard pulse wave matrix to eliminate the amplitude difference;

[0009] Performing waveform alignment on the normalized radar pulse wave matrix and the normalized standard pulse wave matrix to obtain a reference pulse wave matrix aligned with the normalized radar pulse wave matrix;

[0010] Downsampling the normalized radar pulse wave matrix and the reference pulse wave matrix to obtain a downsampled radar pulse wave matrix and a downsampled reference pulse wave matrix;

[0011] Fitting the downsampled radar pulse wave matrix and the downsampled reference pulse wave matrix by the least square method, generating a calibration matrix and storing it for subsequent calibration of the radar pulse wave;

[0012] In actual use, the collected pulse wave is saved in a pulse wave matrix, and the radar pulse wave in the pulse wave matrix is ​​downsampled to obtain a downsampled pulse wave matrix;

[0013] Correcting the downsampled pulse wave matrix using the stored calibration matrix to obtain a downsampled corrected pulse wave matrix;

[0014] Calculating a correction factor matrix according to the downsampled pulse wave matrix and the downsampled corrected pulse wave matrix, and performing linear interpolation on the correction factor matrix to obtain a complete correction factor matrix;

[0015] The pulse wave matrix is ​​corrected based on the complete correction factor matrix to obtain a corrected pulse wave matrix, thereby completing the calibration of the pulse wave.

[0016] Preferably, waveform alignment is performed on the normalized radar pulse wave matrix and the normalized standard pulse wave matrix to obtain a reference pulse wave matrix aligned with the normalized radar pulse wave matrix, specifically comprising the following steps:

[0017] Performing differential processing on the normalized radar pulse wave matrix and the normalized standard pulse wave matrix to obtain a differential radar pulse wave matrix and a differential standard pulse wave matrix respectively;

[0018] Performing three-value quantization processing on the differential radar pulse wave matrix and the differential standard pulse wave matrix, and quantizing the radar pulse wave and the standard pulse wave between -1, 0 and 1;

[0019] Performing cross-correlation operation row by row on the differential radar pulse wave matrix after ternary quantization processing and the differential standard pulse wave matrix after ternary quantization processing to obtain a cross-correlation function of the two, and performing offset calculation on each cross-correlation function to obtain an offset vector;

[0020] The normalized standard pulse wave matrix is ​​clipped according to the offset number vector to obtain a reference pulse wave matrix, and the reference pulse wave matrix is ​​aligned with the normalized radar pulse wave matrix.

[0021] Preferably, the normalized radar pulse wave matrix and the normalized standard pulse wave matrix are subjected to differential processing to obtain the specific calculation formulas of the differential radar pulse wave matrix and the differential standard pulse wave matrix respectively as follows:

[0022]

[0023] Among them, RPWD(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the differential radar pulse wave matrix, and RPWN(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the normalized radar pulse wave matrix; SPWD(i,j) represents the jth sampling point of the standard pulse wave in the i-th row in the differential standard pulse wave matrix, and RPWN(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the normalized standard pulse wave matrix, and i and j represent the row index and column index respectively.

[0024] Preferably, the differential radar pulse wave matrix and the differential standard pulse wave matrix are subjected to three-value quantization processing, and the specific calculation process formula for quantizing the radar pulse wave and the standard pulse wave between -1, 0 and 1 is as follows:

[0025]

[0026] Among them, RPWT(i,j) represents the jth sampling point of the radar pulse wave in the i-th row of the differential radar pulse wave matrix after three-value quantization processing, RPWD(i,j) represents the jth sampling point of the radar pulse wave in the i-th row of the differential radar pulse wave matrix, G TR represents the quantization threshold for the differential radar pulse wave matrix; SPWT(i,j) represents the jth sampling point of the radar pulse wave in the ith row of the differential standard pulse wave matrix after three-value quantization processing, SPWD(i,j) represents the jth sampling point of the radar pulse wave in the ith row of the standard radar pulse wave matrix, G TS represents the quantization threshold for the differential standard pulse wave matrix, and i and j represent the row index and column index respectively.

[0027] Preferably, a cross-correlation operation is performed on the differential radar pulse wave matrix after ternary quantization processing and the differential standard pulse wave matrix after ternary quantization processing to obtain a cross-correlation function of the two, and the specific process of calculating the offset number for each cross-correlation function to obtain the offset number vector is:

[0028] The differential radar pulse wave matrix after ternary quantization processing and the differential standard pulse wave matrix after ternary quantization processing are cross-correlated to obtain the cross-correlation function of the two. The calculation formula is as follows:

[0029]

[0030] Among them, R i represents the cross-correlation function of the pulse wave in the ith row in the differential radar pulse wave matrix after ternary quantization and the differential standard pulse wave matrix after ternary quantization, k represents the offset, N R Indicates the number of sampling points of radar pulse wave, N S Indicates the number of sampling points of the standard pulse wave;

[0031] Perform peak search for each cross-correlation function in turn, and use the k value corresponding to the peak position as the offset number, and save it to the offset number vector N OFF In which the offset number of the i-th row of pulse wave is:

[0032]

[0033] in, Represents R i (k) Take the k value corresponding to the maximum peak.

[0034] Preferably, the normalized standard pulse wave matrix is ​​clipped according to the offset vector to obtain a reference pulse wave matrix. The specific calculation process of aligning the reference pulse wave matrix with the normalized radar pulse wave matrix is ​​as follows:

[0035]

[0036] Among them, bidx represents the starting index of the reference pulse wave in the standard pulse, eidx represents the ending index of the reference pulse in the standard pulse wave, BPWN(i) represents the i-th reference pulse wave, and SPWN(i,bidx:eidx) represents the sampling value of the index range from bidx to eidx in the i-th row of the SPWN matrix.

[0037] Preferably, the calculation formula of the calibration matrix is ​​as follows:

[0038] C=(RPWC T ×RPWC) -1 ×RPWC T ×BPWC

[0039] Wherein, C represents the calibration matrix, RPWC represents the downsampled radar pulse wave matrix, and BPWC represents the downsampled reference pulse wave matrix.

[0040] Preferably, the calculation formula of the correction factor matrix is ​​as follows:

[0041] SFC(i,j)=PWA(i,j) / PWC(i,j)

[0042] Among them, SFC(i,j) is the i-th row and j-th column element of the correction factor matrix SFC, which represents the scaling degree of the j-th sampling point in the i-th row downsampled radar pulse wave after correction, PWA(i,j) represents the j-th sampling point in the i-th row of radar pulse wave in the downsampled corrected pulse wave matrix PWA, and PWC(i,j) represents the j-th sampling point in the i-th row of radar pulse wave in the downsampled pulse wave matrix PWC;

[0043] Linear interpolation is performed on the correction factor matrix SFC to obtain the complete correction factor matrix SF. The calculation formula for the i-th row data of the complete correction factor matrix is ​​as follows:

[0044]

[0045] Where D represents the extraction factor, N C Represents the number of radar pulse wave sampling points in the downsampled pulse wave matrix.

[0046] Preferably, the calculation formula for correcting the pulse wave matrix is ​​as follows:

[0047] PWB=PW·SF

[0048] Wherein, PWB represents the modified pulse wave matrix, PW represents the pulse wave matrix, SF represents the complete correction factor matrix, and · represents the matrix Hadamard product.

[0049] Beneficial effects: The pulse wave calibration method based on millimeter wave radar provided by the present invention has the following beneficial effects:

[0050] 1. The present invention first synchronously collects radar pulse waves and standard pulse waves, and obtains a calibration matrix after fitting through normalization, differential processing, three-value quantization, and cross-correlation operations, and stores the calibration matrix in the device. Then, the radar pulse wave is calibrated based on the calibration matrix in formal use. Under the premise that the device does not fail or the measured individual does not change, only one calculation is required to obtain the calibration matrix for calibrating the radar pulse wave. This method can effectively correct the pulse wave signal collected by the millimeter-wave radar, eliminate the influence of equipment interference and individual differences such as body shape, skin thickness, etc. on the signal, reduce pulse distortion, and improve the accuracy of pulse wave monitoring, thereby improving the waveform interpretation or feature extraction based on the pulse wave in the later stage.

[0051] 2. The present invention uses downsampling and interpolation technology in calibration, which can maintain high efficiency and low consumption during the calibration process, ensuring the signal stability and accuracy after long-term use of the equipment. This correction capability effectively improves the reliability of long-term monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0053] Figure 1 A detailed flow chart of the pulse wave calibration method based on millimeter wave radar of the present invention;

[0054] Figure 2 The present invention provides an overall process of parameter calibration and application calibration of the pulse wave calibration method based on millimeter wave radar;

[0055] Figure 3 This is a schematic diagram of synchronously collecting radar pulse waves and standard pulse waves according to the present invention;

[0056] Figure 4 The present invention is a flow chart of obtaining a reference pulse wave matrix aligned with a normalized radar pulse wave matrix. DETAILED DESCRIPTION

[0057] The present invention will be described more clearly and completely below by way of a preferred embodiment in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the embodiment.

[0058] like Figure 1 and Figure 2 As shown, the present invention provides a pulse wave calibration method based on millimeter wave radar. The method can be divided into two parts, parameter calibration and application calibration. The function of parameter calibration is to generate a calibration matrix by fitting and matching the radar pulse wave and the standard pulse wave. After the calibration is successful, the calibration matrix will be persistently stored. Usually, the parameter calibration process only needs to be executed once, unless the detection object is changed or the performance of the equipment changes after long-term use, recalibration is required. The application calibration is to perform real-time correction on the radar pulse wave according to the calibration matrix during actual use to obtain a more accurate pulse wave waveform, which specifically includes the following steps:

[0059] S101. Synchronously collect a group of radar pulse waves monitored by the radar unit and standard pulse waves monitored by the standard unit, and store them in a radar pulse wave matrix and a standard pulse wave matrix respectively. The standard unit is a contact pulse wave sensing unit.

[0060] In one embodiment, the standard unit is usually a contact pulse wave sensing unit (such as a photoelectric sensor). The integration method of the standard unit can be fixed integration, that is, each radar is fixedly integrated with a standard unit, or it can be pluggable integration, that is, the standard module is made into a pluggable module, and the radar is connected when the radar needs to be calibrated. In this way, multiple radars can share one standard unit. Since the radar equipment only needs to be calibrated occasionally, the pluggable integration solution is a more economical choice.

[0061] like Figure 3 The figure shows a synchronous data collection method. A smart card with integrated millimeter wave radar and a pluggable photoelectric sensor can be used to measure the pulse wave at the same position. The human body can be lying or sitting still during the collection. The collection time is not less than 5 minutes. A set of radar pulse waves and standard pulse waves are obtained, and the results are stored in the radar pulse wave matrix RPW and the standard pulse wave matrix SPW respectively. The size of the matrix RPW is N. PW ×N R , each row in the matrix represents a radar pulse wave, and the matrix contains a total of N PW radar pulse waves, each radar pulse has N sampling points R ; The size of the matrix SPW is N PW ×N S , each row in the matrix represents a standard pulse wave, and the matrix contains a total of N PW standard pulse waves, each with N sampling points S .

[0062] The number of radar pulse waves and standard pulse waves is the same, and the pulse wave sampling frequency is also the same, but the number of sampling points of the standard pulse wave in SPW is greater than that of the radar pulse wave in RPW. The reason is that when selecting the pulse wave, it is impossible to ensure that the radar pulse wave and the standard pulse wave data are completely aligned. Therefore, this scheme reserves a certain amount of redundant sampling points before and after the standard pulse wave to facilitate data alignment operations. The standard pulse wave reserves 25% of redundant sampling points before and after the radar pulse wave, that is, N S N R 1.5 times of.

[0063] S102. Normalizing the radar pulse wave matrix and the standard pulse wave matrix to eliminate amplitude differences.

[0064] The amplitudes of the monitored radar pulse wave and the standard pulse wave may differ greatly due to the following two reasons: first, the measurement principles of the radar unit and the standard unit are different; second, the pulse wave amplitude is affected by many external factors (such as the location of the measuring point, human posture, etc.). Since the absolute amplitude of the pulse wave has great uncertainty, and we are mainly concerned about the shape of the pulse wave, this solution isolates the influence of the absolute amplitude by performing normalization processing on the radar pulse wave matrix RPW and the standard pulse wave matrix SPW. The normalization processing method is as follows:

[0065]

[0066] Among them, RPWN represents the radar pulse wave matrix after normalization, and SPWN represents the standard pulse wave matrix after normalization.

[0067] S103, performing waveform alignment on the normalized radar pulse wave matrix and the normalized standard pulse wave matrix to obtain a reference pulse wave matrix aligned with the normalized radar pulse wave matrix.

[0068] like Figure 4 As shown, the radar pulse wave and the standard pulse wave obtained in the above steps may have data misalignment, and the two must be aligned before fitting and matching, which specifically includes the following steps:

[0069] S301 , performing differential processing on the normalized radar pulse wave matrix and the normalized standard pulse wave matrix to obtain a differential radar pulse wave matrix and a differential standard pulse wave matrix respectively.

[0070] The specific calculation formula is as follows:

[0071]

[0072] Among them, RPWD(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the differential radar pulse wave matrix, and RPWN(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the normalized radar pulse wave matrix; SPWD(i,j) represents the jth sampling point of the standard pulse wave in the i-th row in the differential standard pulse wave matrix, and RPWN(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the normalized standard pulse wave matrix, and i and j represent the row index and column index respectively.

[0073] S302 , performing three-value quantization processing on the differential radar pulse wave matrix and the differential standard pulse wave matrix, and quantizing the radar pulse wave and the standard pulse wave between -1, 0 and 1.

[0074] In order to avoid excessive weights of sampling points with larger values ​​in subsequent cross-correlation calculations, the differential pulse wave data in the differential radar pulse wave matrix RPWD and the differential standard pulse wave matrix SPWD are subjected to three-value quantization processing to obtain the radar pulse wave matrix RPWT after three-value quantization processing and the standard pulse wave matrix SPWT after three-value quantization processing. The so-called three-value quantization refers to quantizing the differential pulse wave data to three values ​​of -1, 0 and 1 according to the numerical size. The specific calculation process formula is as follows:

[0075]

[0076] Among them, RPWT(i,j) represents the jth sampling point of the radar pulse wave in the i-th row of the differential radar pulse wave matrix after three-value quantization processing, RPWD(i,j) represents the jth sampling point of the radar pulse wave in the i-th row of the differential radar pulse wave matrix, G TRrepresents the quantization threshold for the differential radar pulse wave matrix; SPWT(i,j) represents the jth sampling point of the radar pulse wave in the ith row of the differential standard pulse wave matrix after three-value quantization processing, SPWD(i,j) represents the jth sampling point of the radar pulse wave in the ith row of the standard radar pulse wave matrix, G TS represents the quantization threshold for the differential standard pulse wave matrix, and i and j represent the row index and column index respectively.

[0077] S303, performing cross-correlation operation row by row on the differential radar pulse wave matrix after ternary quantization processing and the differential standard pulse wave matrix after ternary quantization processing, to obtain N PW Two cross-correlation functions are obtained, and the offset number vector is obtained by calculating the offset number for each cross-correlation function.

[0078] In one embodiment, the specific process is:

[0079] S3031, performing cross-correlation operation row by row on the differential radar pulse wave matrix after ternary quantization processing and the differential standard pulse wave matrix after ternary quantization processing, to obtain N PW The cross-correlation function of the two is calculated as follows:

[0080]

[0081] Among them, R i represents the cross-correlation function of the pulse wave in the ith row in the differential radar pulse wave matrix after ternary quantization and the differential standard pulse wave matrix after ternary quantization, k represents the offset, N R Indicates the number of sampling points of radar pulse wave, N S Indicates the number of sampling points of the standard pulse wave;

[0082] S3032, perform peak search on each cross-correlation function in turn, and use the k value corresponding to the peak position as the offset number, and save it to the offset number vector N OFF In , the offset number of the i-th row of pulse wave is:

[0083]

[0084] in, Represents R i (k) Take the k value corresponding to the maximum peak.

[0085] Since sufficient redundant sampling points are reserved on the left side of the standard pulse in step S101, the standard pulse can only be aligned with the radar pulse wave by shifting it to the left by a certain number of points, that is, N OFF The values ​​in the vector must be positive.

[0086] S304, the normalized standard pulse wave matrix is ​​clipped according to the offset number vector to obtain a reference pulse wave matrix, and the reference pulse wave matrix is ​​aligned with the normalized radar pulse wave matrix.

[0087] The so-called trimming is to remove the front and back sampling points of each standard pulse wave in the normalized standard pulse wave matrix SPWN to align it with the corresponding radar pulse wave. The specific calculation process is as follows:

[0088]

[0089] Among them, bidx represents the starting index of the reference pulse wave in the standard pulse, eidx represents the ending index of the reference pulse in the standard pulse wave, BPWN(i) represents the i-th reference pulse wave, and SPWN(i,bidx:eidx) represents the sampling value of the index range from bidx to eidx in the i-th row of the SPWN matrix.

[0090] S104 , downsampling the normalized radar pulse wave matrix and the reference pulse wave matrix to obtain a downsampled radar pulse wave matrix and a downsampled reference pulse wave matrix.

[0091] In order to save computing power and storage space, the present invention first uses the decimation method to perform downsampling processing on all pulse waves in the normalized radar pulse wave matrix RPWN and the reference pulse wave matrix BPWN to obtain the downsampled radar pulse wave matrix RPWC and the downsampled reference pulse wave matrix BPWC, and then performs fitting matching. The number of radar pulse wave sampling points before and after downsampling is N and N respectively. R and N C , the extraction factor is D, so the following relationship holds:

[0092] N C =N R / D

[0093] The down-sampling radar pulse wave matrix RPWC and the down-sampling reference pulse wave matrix BPWC obtained by down-sampling are:

[0094]

[0095] Among them, RPWC(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the downsampled radar pulse wave matrix, and BPWC(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the reference pulse wave matrix.

[0096] In one embodiment, the decimation factor D is set to 8, that is, the radar pulse wave sampling point N after downsampling C is the radar pulse wave sampling point N before downsampling R One eighth of .

[0097] S105 , fitting the downsampled radar pulse wave matrix and the downsampled reference pulse wave matrix by the least square method, generating a calibration matrix and storing it for subsequent calibration of the radar pulse wave.

[0098] This step is based on the downsampled radar pulse wave matrix RPWC and the downsampled reference pulse wave matrix BPWC, and uses the least squares criterion to fit the calibration matrix C, that is:

[0099]

[0100] In the formula, the diag(·) operator represents taking the diagonal elements of the matrix. According to the above formula, the analytical result of the calibration matrix C can be calculated as follows, and its size is N C ×N C , the specific calculation formula is as follows:

[0101] C=(RPWC T ×RPWC) -1 ×RPWC T ×BPWC

[0102] After the calibration matrix C is obtained, it is stored in the device memory. If the device does not fail or error occurs or the measurement individual does not change, the calibration matrix can be used to calibrate and correct the radar pulse wave that needs to be calibrated subsequently, without the need to recalculate the calibration matrix every time calibration is performed.

[0103] Application calibration is to correct the radar pulse wave based on the pulse wave calibration matrix C during formal use. Since the calibration matrix C is the result of dimensionality reduction (i.e., it corresponds to the pulse wave matrix after downsampling, not the original pulse wave matrix), the radar pulse wave needs to be downsampled first during application calibration, and then the pulse wave correction is performed. After the correction is completed, the sampling rate needs to be restored. The specific process is as follows:

[0104] S106. In actual use, the collected pulse waves are stored in a pulse wave matrix, and the radar pulse waves in the pulse wave matrix are downsampled to obtain a downsampled pulse wave matrix.

[0105] First, a set of radar pulse waves is collected and saved in the pulse wave matrix PW. The size of PW is N ROW ×N COL , indicating that there are N ROW radar pulse waves, each of which has a length of N COL , and N COL The number of radar pulse wave sampling points N during parameter calibration R equal.

[0106] The size of the calibration matrix C is N C ×N C , and the length of the pulse wave to be calibrated is N COL , the pulse wave length to be calibrated needs to be downsampled to N C Points can be calibrated using the calibration matrix C. Since the length of the pulse wave to be calibrated is N COL The radar pulse length N during the calibration process R are equal, so the same decimation factor D as used during calibration can be used to achieve downsampling.

[0107] Sampling is performed on all pulse waves in the pulse wave matrix PW in turn, and the obtained downsampled pulse wave matrix is ​​recorded as PWC. The jth sampling point of the i-th pulse wave in the matrix is:

[0108] PWC(i,j)=PW(i,D×j)

[0109] S107 . Correct the down-sampled pulse wave matrix using the stored calibration matrix to obtain a down-sampled corrected pulse wave matrix.

[0110] After obtaining the downsampled pulse wave matrix PWC, the calibration matrix C can be directly used to correct it to obtain the downsampled corrected pulse wave matrix PWA. The calculation method is as follows:

[0111] PWA=PWC×C

[0112] S108. Calculate a correction factor matrix according to the downsampled pulse wave matrix and the downsampled corrected pulse wave matrix, and perform linear interpolation on the correction factor matrix to obtain a complete correction factor matrix.

[0113] According to the downsampled pulse wave matrix and the downsampled corrected pulse wave matrix, the correction factor matrix SFC can be obtained. The element in the i-th row and j-th column of SFC represents the scaling degree of the j-th sampling point in the i-th downsampled pulse wave after correction. The calculation method is:

[0114] SFC(i,j)=PWA(i,j) / PWC(i,j)

[0115] Among them, SFC(i,j) is the i-th row and j-th column element of the correction factor matrix SFC, which represents the scaling degree of the j-th sampling point in the i-th row downsampled radar pulse wave after correction, PWA(i,j) represents the j-th sampling point in the i-th row of radar pulse wave in the downsampled corrected pulse wave matrix PWA, and PWC(i,j) represents the j-th sampling point in the i-th row of radar pulse wave in the downsampled pulse wave matrix PWC;

[0116] Linear interpolation is performed on the correction factor matrix SFC row by row to obtain the complete correction factor matrix SF. The calculation formula for the data in the i-th row of the complete correction factor matrix is ​​as follows:

[0117]

[0118] Where D represents the extraction factor, N C Represents the number of radar pulse wave sampling points in the downsampled pulse wave matrix.

[0119] S109, correcting the pulse wave matrix based on the complete correction factor matrix to obtain a corrected pulse wave matrix, thereby completing the calibration of the pulse wave.

[0120] The calculation formula of the corrected pulse wave matrix is ​​as follows:

[0121] PWB=PW·SF

[0122] Wherein, PWB represents the modified pulse wave matrix, PW represents the pulse wave matrix, SF represents the complete correction factor matrix, and · represents the matrix Hadamard product.

[0123] Each row of the result PWB of the above formula represents a corrected radar pulse wave. Compared with the original uncalibrated pulse wave matrix PW, the radar pulse wave in the corrected pulse wave matrix PWB is closer to the standard pulse wave.

[0124] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A pulse wave calibration method based on millimeter wave radar, characterized in that: The specific steps include: Synchronously collect a set of radar pulse waves monitored by a radar unit and a standard pulse wave monitored by a standard unit, and store them in a radar pulse wave matrix and a standard pulse wave matrix respectively, wherein the standard unit is a contact pulse wave sensing unit; Normalize the radar pulse wave matrix and the standard pulse wave matrix to eliminate the amplitude difference; Performing waveform alignment on the normalized radar pulse wave matrix and the normalized standard pulse wave matrix to obtain a reference pulse wave matrix aligned with the normalized radar pulse wave matrix; Downsampling the normalized radar pulse wave matrix and the reference pulse wave matrix to obtain a downsampled radar pulse wave matrix and a downsampled reference pulse wave matrix; Fitting the downsampled radar pulse wave matrix and the downsampled reference pulse wave matrix by the least square method, generating a calibration matrix and storing it for subsequent calibration of the radar pulse wave; In actual use, the collected pulse wave is saved in a pulse wave matrix, and the radar pulse wave in the pulse wave matrix is ​​downsampled to obtain a downsampled pulse wave matrix; Correcting the downsampled pulse wave matrix using the stored calibration matrix to obtain a downsampled corrected pulse wave matrix; Calculating a correction factor matrix according to the downsampled pulse wave matrix and the downsampled corrected pulse wave matrix, and performing linear interpolation on the correction factor matrix to obtain a complete correction factor matrix; The pulse wave matrix is ​​corrected based on the complete correction factor matrix to obtain a corrected pulse wave matrix, thereby completing the calibration of the pulse wave.

2. The pulse wave calibration method based on millimeter wave radar according to claim 1, characterized in that: Performing waveform alignment on the normalized radar pulse wave matrix and the normalized standard pulse wave matrix to obtain a reference pulse wave matrix aligned with the normalized radar pulse wave matrix specifically includes the following steps: Performing differential processing on the normalized radar pulse wave matrix and the normalized standard pulse wave matrix to obtain a differential radar pulse wave matrix and a differential standard pulse wave matrix respectively; Performing three-value quantization processing on the differential radar pulse wave matrix and the differential standard pulse wave matrix, and quantizing the radar pulse wave and the standard pulse wave between -1, 0 and 1; Performing cross-correlation operation row by row on the differential radar pulse wave matrix after ternary quantization processing and the differential standard pulse wave matrix after ternary quantization processing to obtain the cross-correlation function of the two, and performing offset calculation on each cross-correlation function to obtain an offset vector; The normalized standard pulse wave matrix is ​​clipped according to the offset number vector to obtain a reference pulse wave matrix, and the reference pulse wave matrix is ​​aligned with the normalized radar pulse wave matrix.

3. The pulse wave calibration method based on millimeter wave radar according to claim 2, characterized in that: The normalized radar pulse wave matrix and the normalized standard pulse wave matrix are subjected to differential processing, and the specific calculation formulas of the differential radar pulse wave matrix and the differential standard pulse wave matrix are obtained as follows: Among them, RPWD(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the differential radar pulse wave matrix, and RPWN(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the normalized radar pulse wave matrix; SPWD(i,j) represents the jth sampling point of the standard pulse wave in the i-th row in the differential standard pulse wave matrix, and RPWN(i,j) represents the jth sampling point of the radar pulse wave in the i-th row in the normalized standard pulse wave matrix, and i and j represent the row index and column index respectively.

4. The pulse wave calibration method based on millimeter wave radar according to claim 2, characterized in that: The differential radar pulse wave matrix and the differential standard pulse wave matrix are subjected to three-value quantization processing, and the specific calculation process formula for quantizing the radar pulse wave and the standard pulse wave between -1, 0 and 1 is as follows: Among them, RPWT(i,j) represents the jth sampling point of the radar pulse wave in the i-th row of the differential radar pulse wave matrix after three-value quantization processing, RPWD(i,j) represents the jth sampling point of the radar pulse wave in the i-th row of the differential radar pulse wave matrix, G TR represents the quantization threshold for the differential radar pulse wave matrix; SPWT(i,j) represents the jth sampling point of the radar pulse wave in the ith row of the differential standard pulse wave matrix after three-value quantization processing, SPWD(i,j) represents the jth sampling point of the radar pulse wave in the ith row of the standard radar pulse wave matrix, G TS represents the quantization threshold for the differential standard pulse wave matrix, and i and j represent the row index and column index respectively.

5. The pulse wave calibration method based on millimeter wave radar according to claim 2, characterized in that: The differential radar pulse wave matrix after ternary quantization and the differential standard pulse wave matrix after ternary quantization are cross-correlated row by row to obtain the cross-correlation function of the two. The specific process of calculating the offset number of each cross-correlation function to obtain the offset number vector is as follows: The differential radar pulse wave matrix after ternary quantization processing and the differential standard pulse wave matrix after ternary quantization processing are cross-correlated row by row to obtain the cross-correlation function of the two. The calculation formula is as follows: Among them, R i represents the cross-correlation function of the pulse wave in the ith row in the differential radar pulse wave matrix after ternary quantization and the differential standard pulse wave matrix after ternary quantization, k represents the offset, N R Indicates the number of sampling points of radar pulse wave, N S Indicates the number of sampling points of the standard pulse wave; Perform peak search for each cross-correlation function in turn, and use the k value corresponding to the peak position as the offset number, and save it to the offset number vector N OFF In , the offset number of the i-th row of pulse wave is: in, Represents R i (k) Take the k value corresponding to the maximum peak.

6. The pulse wave calibration method based on millimeter wave radar according to claim 2, characterized in that: The normalized standard pulse wave matrix is ​​clipped according to the offset vector to obtain the reference pulse wave matrix. The specific calculation process of aligning the reference pulse wave matrix with the normalized radar pulse wave matrix is ​​as follows: Among them, bidx represents the starting index of the reference pulse wave in the standard pulse, eidx represents the ending index of the reference pulse in the standard pulse wave, BPWN(i) represents the i-th reference pulse wave, and SPWN(i,bidx:eidx) represents the sampling value of the index range from bidx to eidx in the i-th row of the SPWN matrix.

7. The pulse wave calibration method based on millimeter wave radar according to claim 1, characterized in that: The calibration matrix is ​​calculated as follows: C=(RPWC T ×RPWC) -1 ×RPWC T ×BPWC Wherein, C represents the calibration matrix, RPWC represents the downsampled radar pulse wave matrix, and BPWC represents the downsampled reference pulse wave matrix.

8. The pulse wave calibration method based on millimeter wave radar according to claim 1, characterized in that: The calculation formula of the correction factor matrix is ​​as follows: SFC(i,j)=PWA(i,j) / PWC(i,j) Among them, SFC(i,j) is the i-th row and j-th column element of the correction factor matrix SFC, which represents the scaling degree of the j-th sampling point in the i-th row downsampled radar pulse wave after correction, PWA(i,j) represents the j-th sampling point in the i-th row of radar pulse wave in the downsampled corrected pulse wave matrix PWA, and PWC(i,j) represents the j-th sampling point in the i-th row of radar pulse wave in the downsampled pulse wave matrix PWC; Linear interpolation is performed on the correction factor matrix SFC to obtain the complete correction factor matrix SF. The data calculation formula for the i-th row of the complete correction factor matrix is ​​as follows: Where D represents the extraction factor, N C Represents the number of radar pulse wave sampling points in the downsampled pulse wave matrix.

9. The pulse wave calibration method based on millimeter wave radar according to claim 1, characterized in that: The calculation formula of the corrected pulse wave matrix is ​​as follows: PWB=PW·SF Wherein, PWB represents the modified pulse wave matrix, PW represents the pulse wave matrix, SF represents the complete correction factor matrix, and · represents the matrix Hadamard product.

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