Contactless moving target speed measurement method, system, device and storage medium

Abstract

The present invention relates to a contactless moving target speed measurement method, system, device, and storage medium, comprising: obtaining channel state information containing the target's motion state through at least two receiving devices, eliminating random phase offsets of the channel state information to obtain new channel state information, and performing noise reduction filtering on the new channel state information; identifying the target's motion state based on the new channel state information, and dynamically selecting the two optimal receiving devices if the target is moving; extracting the Doppler frequency shift caused by the target's motion from the two optimal receiving devices, and calculating the target's motion speed based on the Doppler frequency shift; the motion speed includes the magnitude and direction of motion. The present invention can simultaneously and accurately measure the speed and direction of a moving target without the moving target carrying or touching any device.

Description

Technical Field

[0001] The present invention relates to the technical field of speed measurement, and in particular to a contactless moving target speed measurement method, system, device and storage medium based on wireless radio frequency signals. Background Art

[0002] In the field of situational awareness, especially in scenarios such as smart homes, unmanned shopping malls, and smart airports, speed measurement of moving targets is one of the important foundations for realizing applications such as positioning tracking and behavior recognition.

[0003] Traditional methods use inertial measurement units (IMUs) to measure the speed of moving targets, which are contact-based speed measurement methods. However, these methods require carrying a speed measurement device at all times, resulting in limited universality and low comfort. In comparison, non-contact speed measurement of moving targets does not require the moving target to carry or touch any device, offering advantages such as non-intrusiveness, universality, and high comfort. Leveraging wireless radio frequency devices commonly found in everyday environments such as homes and offices (e.g., WiFi routers and 4G / 5G mobile terminals) for non-contact speed measurement of moving targets offers the advantages of easy deployment and low cost.

[0004] Existing solutions suffer from the following technical issues: 1. They ignore the impact of the target's position and direction on velocity estimation accuracy, failing to guarantee high-precision velocity estimation for all possible positions and directions. 2. The complex optimization algorithms employed are not conducive to real-time processing, making it difficult to meet the requirements of real-time target trajectory tracking in real-world scenarios. 3. They can only estimate partial velocity information about the target, namely the magnitude or direction of motion. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a contactless moving target speed measurement method, system, device and storage medium, which can accurately measure the speed and direction of a moving target at the same time without the moving target carrying or touching any equipment.

[0006] To achieve the above-mentioned purpose, on the one hand, the technical solution adopted by the present invention is: a contactless moving target speed measurement method, which includes: obtaining channel state information containing the target motion state through at least two receiving devices, eliminating the random phase offset of the channel state information to obtain new channel state information, and performing noise reduction filtering on the new channel state information; identifying the target motion state according to the new channel state information, and dynamically selecting the two best receiving devices if the target is moving; extracting the Doppler frequency shift caused by the target motion from the two best receiving devices, and calculating the target motion speed according to the Doppler frequency shift; the motion speed includes the degree and direction of motion.

[0007] Further, obtaining new channel state information after eliminating the random phase offset of the channel state information includes:

[0008] Each of the receiving devices simultaneously receives radio frequency signals from the same transmitting device through at least two antennas thereof;

[0009] The receiving device collects the channel state information from at least two of the antennas, and divides or conjugate-multiplies the channel state information collected from each of the antennas at the same time to obtain the new channel state information, thereby eliminating the random phase offset in the channel state information caused by time asynchrony between the receiving device and the transmitting device.

[0010] Furthermore, the noise reduction filtering process uses a Savitzky-Golay filter or a sliding average filtering method to filter and reduce noise on the new channel state information.

[0011] Furthermore, identifying the target motion state according to the new channel state information includes:

[0012] If the second peak value of the autocorrelation function value of the amplitude signal or the phase signal of the new state information of at least one of the receiving devices is greater than a preset first threshold, it is determined that the target is moving;

[0013] Alternatively, if the fluctuation of the amplitude signal or the phase signal of the new channel state information of at least one of the receiving devices is greater than a preset second threshold, it is determined that the target is moving.

[0014] Furthermore, the dynamically selecting the two optimal receiving devices includes:

[0015] Calculating a position scale coefficient index of all the receiving devices, and if the position scale coefficient index is less than a preset third threshold, excluding the receiving device corresponding to the position scale coefficient index;

[0016] Calculating joint indices of the remaining receiving devices for the same transmitting device, and selecting the receiving devices corresponding to the two largest joint indices as the optimal two receiving devices;

[0017] Alternatively, the joint indexes of all the receiving devices for the same transmitting device are directly calculated, and the receiving devices corresponding to the two largest joint indexes are selected as the optimal two receiving devices.

[0018] Furthermore, extracting the Doppler frequency shift caused by the target motion from the two optimal receiving devices respectively includes:

[0019] A time-frequency spectrum is obtained from the new channel state information of each receiving device, and a frequency value corresponding to the maximum energy in the time-frequency spectrum at each moment is selected as the Doppler frequency shift caused by the movement of the target at that moment.

[0020] Further, calculating the moving speed of the target according to the Doppler frequency shift includes:

[0021] According to the Doppler shift, the equations are constructed:

[0022]

[0023] Among them, f D1 and f D2 are the Doppler shifts obtained from the first and second optimally selected receiving devices, α R1 and α R2 are the angles of the target location relative to the first and second optimally selected receiving devices; α T is the angle of the target relative to the transmitting device; θ is the target's direction of motion; f is the frequency of the wireless signal; c is the speed of light; the target's direction of motion θ is obtained by the analytical equations:

[0024] θ=(α T +α R1 ) / 2+angle(Φ2-Φ1cos(Δα / 2),Φ1sin(Δα / 2));

[0025] Where Φ1=f D1 cos((a T -α R2 ) / 2)), Φ2=f D2 cos((α T -α R1 ) / 2)), Δα=α R2 -α R1, angle(a,b)=arctan2(b / a) is the inverse tangent function in the four quadrants; the target's motion speed v is obtained by the target's motion direction θ:

[0026] v=-cf D1 / (fcos(θ-(α T +α R1 ) / 2)·2cos((α T -α R1 ) / 2));

[0027] Or, use the optimization algorithm to find the target's speed and direction of movement so that the objective function is minimized. The preferred objective function is v,θ for:

[0028]

[0029] Among them, f Dj It is the Doppler frequency shift obtained on the jth receiving device according to the given target's moving speed v and moving direction θ. is the Doppler frequency shift actually obtained on the jth receiving device, and M is the total number of the receiving devices used.

[0030] On the other hand, the technical solution adopted by the present invention is: a contactless moving target speed measurement system, which includes: a signal processing module, a dynamic optimization module and a motion speed calculation module; the signal processing module obtains channel state information containing the target motion state through at least two receiving devices, eliminates the random phase offset of the channel state information to obtain new channel state information, and performs noise reduction filtering on the new channel state information; the dynamic optimization module identifies the target motion state according to the new channel state information, and dynamically selects the two best receiving devices if the target is moving; the motion speed calculation module extracts the Doppler frequency shift caused by the target movement from the two best receiving devices, and calculates the motion speed of the target according to the Doppler frequency shift; the motion speed includes the degree and direction of movement.

[0031] On the other hand, the technical solution adopted by the present invention is: a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, and when the instructions are executed by a computing device, the computing device performs any one of the above methods.

[0032] On the other hand, the technical solution adopted by the present invention is: a computing device, which includes: one or more processors, a memory and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing any of the above methods.

[0033] The present invention has the following advantages due to the adoption of the above technical solution:

[0034] 1. The present invention can meet the real-time requirements of the system and ensure the accuracy requirements of speed measurement, achieving optimal or near-optimal speed estimation under given device placement.

[0035] 2. The technical solution provided by the present invention has low requirements on equipment and can be implemented on some common commercial wireless radio frequency signal transceivers (such as WiFi network cards, WiFi routers, mobile phone terminals, etc.) without modifying any hardware. Therefore, it has the advantages of easy deployment, low cost and high efficiency.

[0036] 3. The present invention does not require the target to carry or touch any equipment, and has the advantages of being non-intrusive, simple and easy to use.

[0037] 4. The present invention is applicable to any wireless radio frequency (RF) signal device with separate transmission and reception, including but not limited to WiFi devices, 4G / 5G devices, RFID devices, LoRa devices, etc., and can accurately measure the speed and direction of a moving target simultaneously without the moving target carrying or touching any device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 1 is a schematic diagram of the overall flow of a measurement method in one embodiment of the present invention;

[0039] Figure 2 is a specific flow chart of a method for measuring the motion speed of a moving target according to one embodiment of the present invention;

[0040] Figure 3 A non-contact moving target speed measurement system is constructed according to an embodiment of the present invention;

[0041] Figure 4 The relationship between the Doppler shift and the speed, direction, and position of a moving target relative to an RF transceiver according to an embodiment of the present invention;

[0042] Figure 5 It is a schematic diagram of the structure of a computing device in one embodiment of the present invention. DETAILED DESCRIPTION

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] The basic principle of the present invention is that when a target moves in physical space, the Doppler effect causes the frequency of the RF signal received by the RF receiving device to differ from the frequency of the RF signal sent by the RF transmitting device. This frequency difference is called the Doppler shift. By leveraging the precise mathematical relationship between the Doppler shift and the target's velocity, direction, and position relative to the RF transceiver in a separate RF system, the present invention quantitatively reveals that the accuracy of measuring a target's velocity from the Doppler shift is critically dependent on the target's position and direction relative to the RF transceiver. Therefore, the present invention proposes a dynamic optimization selection strategy that automatically and dynamically selects the optimal RF receiving device from multiple RF receiving devices based on the target's position and direction relative to the RF transceiver, thereby achieving high-precision estimation of the target's velocity.

[0046] Therefore, the present invention provides a contactless moving target speed measurement method, system, device and storage medium. For any RF device with separated transmission and reception that can extract Doppler frequency shift, at least one RF transmitting device is deployed to send signals, and at least two RF receiving devices are deployed to receive signals. Random phase offset noise and amplitude noise are eliminated from the received signals to determine whether the target is moving. When the target is moving, the two optimal RF receiving devices are dynamically selected to extract Doppler frequency shift from the signal, and finally the speed of the moving target (including speed magnitude and direction of movement) is estimated. The present invention supports solving the target's speed in an analytical way - including speed magnitude and direction of movement, which can meet the real-time requirements of the system. The present invention quantitatively characterizes the influence of the position and direction of movement of the target relative to the RF transceiver device on the speed measurement accuracy, and then proposes a dynamic optimization selection strategy, which automatically and dynamically selects the optimal two RF transceiver devices from at least two RF transceiver devices according to the position and direction of movement of the target relative to the RF transceiver device to extract Doppler frequency shift, which is further used to measure the target's speed, ensuring that the system can achieve near-optimal performance.

[0047] In the present invention, the specific terms have the following meanings:

[0048] RF stands for radio frequency signal, and CSI stands for channel state information;

[0049] a is an RF transmitter Tx, which supports sending RF signals and is equipped with at least one antenna;

[0050] bc is a first to a second RF receiving device, which supports receiving RF signals and is configured with at least two antennas;

[0051] The RF transmitting device may be a WiFi router, a 4G / 5G base station, etc., the RF receiving device may be a WiFi terminal, a 4G / 5G terminal, etc., and the RF signal may be a WiFi signal, a 4G / 5G signal, etc.;

[0052] Tx is an RF transmitting device, Rx is an RF receiving device, and a reference coordinate system is established with Tx as the origin and Rx in the positive direction of the x-axis. This reference coordinate system is a form adopted in this embodiment, and the method of the present invention is also applicable to similar reference systems;

[0053] is the position of the target at time t;

[0054] v is the target's speed;

[0055] θ is the target's direction of motion;

[0056] v n The target's velocity is projected onto the surface with Tx and Rx as the focus and and The sum of the major axis lengths of the ellipse is at point The magnitude of the velocity on the normal line;

[0057] α T is the Angle of Departure (AoD) of the RF signal;

[0058] α R is the angle of arrival (AoA) of the RF signal;

[0059] Assume that the target location is (x, y), and the locations of the RF receiving device and the RF transmitting device are (x T ,y T ) and (x R ,y R ),but:

[0060] α T =arctan2((yy T ) / (xx T )), and α R =arctan2((yy r ) / (xx R )), arctan2(*) is the inverse tangent function in the four quadrants.

[0061] In one embodiment of the present invention, Figure 1 As shown, a non-contact moving target speed measurement method is provided. This embodiment uses the method applied to a terminal as an example for illustration. It is understandable that the method can also be applied to a server, and can also be applied to a system including a terminal and a server, and implemented through the interaction between the terminal and the server. In this embodiment, the method includes the following steps:

[0062] 1) acquiring channel state information including the target motion state through at least two receiving devices, eliminating random phase offsets of the channel state information to obtain new channel state information, and performing noise reduction filtering on the new channel state information;

[0063] 2) Identify the target's motion state based on the new channel state information. If the target is moving, dynamically select the two optimal receiving devices.

[0064] 3) The Doppler shift caused by the target's motion is extracted from the two optimal receiving devices respectively, and the target's motion speed is calculated based on the Doppler shift; the motion speed includes the magnitude and direction of motion.

[0065] In the above step 1), at least three RF transceiver devices are arranged in this embodiment, such as Figure 3As shown, there is an RF transmitter Tx and at least two RF receivers. The RF transmitter Tx is configured with at least one antenna to transmit RF signals, and the RF receivers are each configured with at least two antennas to receive corresponding RF signals. The RF transceiver can be a laptop, Mini PC, or any other device that supports RF signal transmission and reception. Both the transmitting and receiving antennas can be vertically polarized omnidirectional antennas.

[0066] Preferably, a common WiFi device is used as a signal transmitting device, and a daily commercial WiFi network card (such as Intel5300 network card, Atheros AR9580 network card, Atheros AR9590 network card, etc.) is installed on a personal computer as a WiFi signal receiving end to collect CSI signals. Common commercial WiFi network cards support at least two antennas, and use a WiFi signal with a center frequency of 5.32GHz as the RF signal. A 2.4GHz WiFi signal can also be selected as the RF signal, and an omnidirectional antenna is used.

[0067] Preferably, other RF devices can also be selected, such as a 4G / 5G base station as an RF signal transmitting device; a 4G / 5G terminal as an RF receiving device; and the RF signal is a wireless signal used by the 4G / 5G device.

[0068] Preferably, other RF devices may be selected, such as RFID tags as RF signal transmitting devices (active RFID tags or passive RFID tags); the RF receiving device is an RFID reader; and the RF signal is a wireless signal used by the RFID device.

[0069] Preferably, other RF devices may be selected, such as a LoRa node as an RF signal transmitting device; a LoRa gateway as an RF receiving device; and the RF signal is a wireless signal used by the LoRa device.

[0070] In the above step 1), if Figure 2 As shown, the new channel state information is obtained after eliminating the random phase offset of the channel state information: for each RF receiving device, at least two antennas are used to eliminate the random phase offset caused by clock asynchrony between the transmitting and receiving devices; wherein, the random phase offset refers to the random phase offset in the channel state information estimation caused by RF signal sampling frequency offset, carrier frequency offset, packet detection frequency offset, device startup phase lock, etc. Specifically:

[0071] Each receiving device receives the radio frequency signal from the same transmitting device simultaneously through at least two antennas it has;

[0072] The receiving device collects channel state information from at least two antennas and divides or conjugate-multiplies the channel state information collected from each antenna at the same time to obtain new channel state information, thereby eliminating random phase offsets in the channel state information caused by time asynchrony between the receiving device and the transmitting device.

[0073] In this embodiment, preferably, each RF receiving device simultaneously receives RF signals from the same RF transmitting device via at least two of its antennas. The RF receiving device collects channel state information (CSI) from the at least two antennas and divides the CSI collected simultaneously from each antenna to eliminate random phase offsets in the signal caused by time asynchrony between the RF receiving device and the RF transmitting device. For example, at time t, the channel state information for an RF signal with frequency f on one antenna is H1(f, t), and the channel state information on the other antenna is H2(f, t). The new channel state information after eliminating the random phase offset is: S(f, t) = H1(f, t) / H2(f, t).

[0074] Preferably, each RF receiving device simultaneously receives RF signals from the same RF transmitting device via at least two of its antennas. The RF receiving device collects channel state information (CSI) from the at least two antennas and conjugate-multiplies the CSI collected simultaneously from each antenna to eliminate random phase offsets in the signal caused by time asynchrony between the RF receiving device and the RF transmitting device. For example, at time t, the channel state information for an RF signal with a frequency of f on one antenna is H1(f, t), and the channel state information on the other antenna is H2(f, t). The new channel state information after eliminating the random phase offset is obtained as: in represents the conjugate of a.

[0075] In the above step 1), the noise reduction filtering process uses a Savitzky-Golay filter or a sliding average filter method to filter and reduce the noise of the new channel state information.

[0076] In this embodiment, for each RF receiving device, the noise in the new channel state information obtained after the random phase offset is eliminated is further filtered and noise reduced:

[0077] Preferably, for the new signals [S1(f, t), S2(f, t), ..., S N (f, t)], and use Savitzky-Golay filter to perform noise reduction filtering on the new signal to generate the noise-reduced filtered signal S s (f,t)=[S1s (f,t),S 2s (f,t),…,S Ns (f,t)].

[0078] Preferably, for the new signals [S1(f, t), S2(f, t), ..., S N (f, t)], the new signal obtained is subjected to noise reduction filtering using the sliding average filtering method to generate a noise-reduced filtered signal S s (f,t)=[S 1s (f,t),S 2s (f,t),…,S Ns (f,t)].

[0079] In the above step 2), the target motion state is identified according to the new channel state information, specifically:

[0080] If the second peak of the autocorrelation function value of the amplitude signal or the phase signal of the new channel state information of at least one receiving device is greater than a preset first threshold, it is determined that the target is moving;

[0081] Alternatively, if the fluctuation of the amplitude signal or the phase signal of the new channel state information of at least one receiving device is greater than a preset second threshold, it is determined that the target is moving.

[0082] In this embodiment, all of the at least two RF receiving devices are used to determine whether the target is moving based on the signal after noise reduction filtering.

[0083] Preferably, the noise reduction filtered signal S is calculated s The method of autocorrelation of (f, t) takes the second peak in the spectrum obtained by the autocorrelation function and determines whether the target is moving based on a set threshold. When the second peak of the autocorrelation function value of at least one RF receiving device among all RF receiving devices is greater than the set threshold, it is determined that the target is moving.

[0084] Preferably, the signal fluctuation may be calculated, and when the fluctuation of the amplitude signal of the channel state information of at least one RF receiving device among all the RF receiving devices is greater than a set threshold, it is determined that the target is moving.

[0085] In the above step 2), the two best receiving devices are dynamically selected: if the target is active, the two best receiving devices are automatically and dynamically selected from at least two RF receiving devices.

[0086] The relationship between the target's velocity measurement accuracy and Doppler frequency shift accuracy is: where d vIt indicates the accuracy of the target's speed, that is, the difference from the true speed value; It represents the accuracy of Doppler frequency shift, that is, the difference from the actual Doppler frequency shift value; c is the speed of light, which is a constant; f is the frequency of the RF signal; θ is the direction of movement of the target; α T and α R They are the angles of the target location relative to the RF transmitter and the RF receiver, also known as the angle of departure (AoD) and angle of arrival (AoA) of the RF signal. Assume that the target location is (x, y), and the locations of the RF receiver and the RF transmitter are (x T ,y T ) and (x R ,y R ), then α T =arctan2((yy T ) / (xx T )), and α R =arctan2((yy R ) / (xx R )), arctan2(*) is the inverse tangent function in the four quadrants. Ignoring the sign problem, in order to accurately estimate the target's speed, that is, to minimize d v , the target's direction of motion θ and its position relative to the RF transceiver should be selected so that cos(θ-(α T +α R ) / 2) the largest RF receiving device, on the other hand, should be selected based on the position of the target relative to the RF transceiver device so that cos((α T -α R ) / 2)The largest RF receiving device.

[0087] The relationship between the target's motion direction measurement accuracy and Doppler frequency shift accuracy is: where d θ It represents the accuracy of the target's movement direction, that is, the difference from the true movement direction value; It represents the accuracy of Doppler frequency shift, that is, the difference from the actual Doppler frequency shift value; c is the speed of light, which is a constant; v is the speed of the target; f is the frequency of the RF signal; θ is the direction of the target's movement; α T and α RThey are the angles of the target location relative to the RF transmitter and the RF receiver, also known as the angle of departure (AoD) and angle of arrival (AoA) of the RF signal. Assume that the target location is (x, y), and the locations of the RF receiver and the RF transmitter are (x T ,y T ) and (x R ,y R ), then α T =arctan2((yy T ) / (xx T )), and α R =arctan2((yy R ) / (xx R )), arctan2(*) is the inverse tangent function in the four quadrants. Ignoring the sign problem, in order to accurately estimate the direction of motion of the target, that is, to minimize d θ , the target's direction of motion θ and its position relative to the RF transceiver should be selected so that sin(θ-(α T +α R ) / 2) the largest RF receiving device, on the other hand, should be selected based on the position of the target relative to the RF transceiver device so that cos((α T -α R ) / 2)The largest RF receiving device.

[0088] Specifically, the two optimal receiving devices are dynamically selected using one of the following two methods:

[0089] Method 1: Calculate the position scale factor index of all receiving devices If the position ratio coefficient index is less than a preset third threshold, excluding the receiving device corresponding to the position ratio coefficient index;

[0090] Calculate the joint index of the remaining receiving devices for the same transmitting device, and select the receiving devices corresponding to the two largest joint indexes as the optimal two receiving devices;

[0091] For example, first, based on the position of the target at the previous moment, for the same RF transmitting device, calculate the position proportional coefficient index corresponding to the jth RF receiving device in, is the target's AoD at time t-1, is the AoA of the target on the jth RF receiving device at time t-1; this indicator is calculated for each RF receiving device in all RF receiving devices, and a threshold is set to exclude receiving devices with a value smaller than the threshold; then, in order to take into account the estimation accuracy of the target's speed and direction of movement, the target's position and direction of movement θ at the previous moment are used to estimate the target's speed and direction of movement. t-1 , for the same RF transmitting device, calculate the joint index corresponding to the jth RF receiving device The joint index is calculated for all RF receiving devices excluded in the previous step, and two RF receiving devices that maximize the joint index are selected as the optimal two RF receiving devices.

[0092] Among them, the position of the moving target relative to the RF transceiver device at the last moment and the direction of movement at the last moment can directly give the real position of the moving target; or, the position of the moving target relative to the RF transceiver device at the last moment and the direction of movement at the last moment can be iteratively obtained by giving the initial position and initial direction of movement, combined with the movement speed measured by the present invention.

[0093] Method 2: Directly calculate the joint index of all receiving devices for the same transmitting device, and select the receiving devices corresponding to the two largest joint indexes as the two optimal receiving devices;

[0094] For example, according to the position and movement direction θ of the target at the previous moment t-1 , for the same RF transmitting device, calculate the joint index corresponding to the jth RF receiving device Among them, αTt-1 is the AoD of the target at time t-1, The target is the AoA corresponding to the j-th RF receiving device at time t-1. The joint index is calculated for each of all RF receiving devices, and the two RF receiving devices that maximize the joint index are automatically selected as the optimal two RF receiving devices.

[0095] In step 3) above, the Doppler frequency shift caused by the target's motion is extracted from the two optimal receiving devices respectively. Specifically, a time-frequency spectrum is obtained from the new channel state information of each receiving device, and the frequency value corresponding to the maximum energy in the time-frequency spectrum at each moment is selected as the Doppler frequency shift caused by the target's motion at that moment.

[0096] In this embodiment, preferably, a time-frequency analysis method, a continuous 1-D wavelet transform (CWT) method is used to extract the noise reduction filtered signal S from each RF receiving device. sThe time-frequency spectrum is obtained from (f, t), and the frequency value corresponding to the maximum energy in the time-frequency spectrum at each moment is selected as the Doppler frequency shift caused by the movement of the target at that moment.

[0097] Preferably, a time-frequency analysis method, Short Time Fourier Transform (STFT), is used to obtain the noise reduction filtered signal S from each RF receiving device. s The time-frequency spectrum is obtained from (f, t), and the frequency value corresponding to the maximum energy in the time-frequency spectrum at each moment is selected as the Doppler frequency shift caused by the movement of the target at that moment.

[0098] In the above step 3), the target's moving speed is calculated based on the Doppler frequency shift: the target's moving speed, including the speed magnitude and moving direction, is calculated based on the Doppler frequency shift extracted from the two optimally selected RF receiving devices.

[0099] like Figure 4 As shown, for a given pair of RF transceivers, the relationship between the Doppler shift caused by the target and the position, velocity, and direction of movement of the target relative to the RF transceiver is f D =-(fvcos(θ-(α T +α R ) / 2)·2cos((α T -α R ) / 2)) / c, where f is the frequency of the RF signal; v is the speed of the target; θ is the direction of the target; α T and α R They are the angles of the target location relative to the RF transmitter and the RF receiver, also known as the angle of departure (AoD) and angle of arrival (AoA) of the RF signal. Assume that the target location is (x, y), and the locations of the RF receiver and the RF transmitter are (x T ,y T ) and (x R ,y R ), then α T =arctan2((yy T ) / (xx T )), and α R =arctan2((yy R ) / (xx R )), arxtαc2(*) is the inverse tangent function in the four quadrants; c is the speed of light, which is a constant.

[0100] The target's velocity is calculated using one of the following two methods:

[0101] Method 1: For each of the two optimally selected RF receiving devices, an equation can be obtained, and a system of equations can be constructed based on the Doppler frequency shift:

[0102]

[0103] Among them, f D1 and f D2 are the Doppler shifts obtained from the first and second optimally selected receiving devices, α R1 and α R2 are the angles of the target location relative to the first and second optimally selected receiving devices; α T is the angle of the target relative to the transmitting device; θ is the target's direction of motion; f is the frequency of the wireless signal; c is the speed of light; the direction of motion θ obtained analytically is:

[0104] θ=(α T +α R1 ) / 2+angle(Φ2-Φ1cos(Δα / 2),Φ1sin(Δα / 2)),

[0105] where Φ1=f D1 cos((α T -α R2 ) / 2)), Φ2=f D2 cos((α T -α R1 ) / 2)), Δα=α R2 -α R1 , angle(a,b)=arctan2(b / a) is the inverse tangent function in the four quadrants; the target's motion speed v is obtained by analyzing the equation group:

[0106] v=-cf D1 / (fcos(θ-(α T +α R1 ) / 2)·2cos((α T -α R1 ) / 2)).

[0107] Method 2: You can select the RF receiving device without dynamic optimization, and use the optimization algorithm to find the target's speed and direction of movement to minimize the objective function. The optimal objective function is v,θ for:

[0108]

[0109] Among them, f DjIt is the Doppler frequency shift obtained on the jth receiving device based on the given target's velocity v and target's direction θ. is the Doppler shift actually obtained on the jth receiving device, and M is the total number of receiving devices used.

[0110] In the above embodiments, after the RF transceiver equipment is arranged in step 1), the remaining steps can be executed in real time, including eliminating random phase offsets, filtering signal noise, identifying target motion status, dynamically selecting RF receiving equipment, extracting Doppler frequency shift, and measuring target motion speed.

[0111] In one embodiment of the present invention, a non-contact moving target speed measurement system is provided, which includes: a signal processing module, a dynamic optimization module and a motion speed calculation module;

[0112] a signal processing module that obtains channel state information including the target motion state through at least two receiving devices, eliminates random phase offsets of the channel state information to obtain new channel state information, and performs noise reduction filtering on the new channel state information;

[0113] The dynamic optimization module identifies the target's motion state based on the new channel state information. If the target is moving, it dynamically selects the two best receiving devices.

[0114] The motion speed calculation module extracts the Doppler frequency shift caused by the target's motion from the two best receiving devices, and calculates the target's motion speed based on the Doppler frequency shift; the motion speed includes the magnitude and direction of motion.

[0115] The system provided in this embodiment is used to execute the above-mentioned method embodiments. Please refer to the above-mentioned embodiments for specific processes and detailed contents, which will not be repeated here.

[0116] like Figure 5FIG. 1 is a schematic diagram of the structure of a computing device provided in one embodiment of the present invention. The computing device may be a terminal and may include: a processor, a communication interface, a memory, a display screen, and an input device. The processor, the communication interface, and the memory communicate with each other via a communication bus. The processor is used to provide computing and control capabilities. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. When the computer program is executed by the processor, it implements a measurement method. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The communication interface is used to communicate with an external terminal in a wired or wireless manner. The wireless manner may be implemented through WIFI, a management network, NFC (near field communication), or other technologies. The display screen may be a liquid crystal display or an electronic ink display screen. The input device may be a touch layer covering the display screen, or a key, trackball, or touchpad provided on the housing of the computing device, or an external keyboard, touchpad, or mouse. The processor may call the logic instructions in the memory to execute the following method:

[0117] Channel state information containing the target's motion state is obtained through at least two receiving devices, and new channel state information is obtained after eliminating the random phase offset of the channel state information. The new channel state information is subjected to noise reduction filtering. The target's motion state is identified based on the new channel state information. If the target is moving, the two optimal receiving devices are dynamically selected. The Doppler frequency shift caused by the target's motion is extracted from the two optimal receiving devices, and the target's motion speed is calculated based on the Doppler frequency shift. The motion speed includes the magnitude and direction of motion.

[0118] In addition, the logical instructions in the above-mentioned memory can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0119] Those skilled in the art will understand that Figure 5 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computing device to which the solution of the present application is applied. The specific computing device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0120] In one embodiment of the present invention, a computer program product is provided, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the methods provided by the above-mentioned method embodiments, for example, including: obtaining channel state information containing the target motion state through at least two receiving devices, eliminating the random phase offset of the channel state information to obtain new channel state information, and performing noise reduction filtering on the new channel state information; identifying the target motion state based on the new channel state information, and dynamically selecting the two best receiving devices if the target is moving; extracting the Doppler frequency shift caused by the target motion from the two best receiving devices, and calculating the target motion speed based on the Doppler frequency shift; the motion speed includes the degree and direction of motion.

[0121] In one embodiment of the present invention, a non-transitory computer-readable storage medium is provided, which stores server instructions, and the computer instructions enable a computer to execute the methods provided in the above embodiments, for example, including: obtaining channel state information containing the target motion state through at least two receiving devices, eliminating the random phase offset of the channel state information to obtain new channel state information, and performing noise reduction filtering on the new channel state information; identifying the target motion state based on the new channel state information, and dynamically selecting the two best receiving devices if the target is moving; extracting the Doppler frequency shift caused by the target motion from the two best receiving devices, and calculating the target motion speed based on the Doppler frequency shift; the motion speed includes the degree and direction of motion.

[0122] The above embodiment provides a computer-readable storage medium, whose implementation principle and technical effects are similar to those of the above method embodiment, and will not be repeated here.

[0123] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0124] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0125] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A non-contact moving target speed measurement method, characterized in that: include: Acquiring channel state information including a target motion state through at least two receiving devices, eliminating a random phase offset of the channel state information to obtain new channel state information, and performing noise reduction filtering on the new channel state information; Identifying the target motion state according to the new channel state information, and dynamically selecting the two optimal receiving devices if the target is moving; Extracting the Doppler frequency shift caused by the target's motion from the two optimal receiving devices respectively, and calculating the target's motion speed according to the Doppler frequency shift; the motion speed includes a magnitude and a motion direction; The dynamically selecting the two optimal receiving devices includes: Calculating a position scale coefficient index of all the receiving devices, and if the position scale coefficient index is less than a preset third threshold, excluding the receiving device corresponding to the position scale coefficient index; Calculating joint indices of the remaining receiving devices for the same transmitting device, and selecting the receiving devices corresponding to the two largest joint indices as the optimal two receiving devices; Alternatively, directly calculating the joint index of all the receiving devices for the same transmitting device, and selecting the receiving devices corresponding to the two largest joint indexes as the optimal two receiving devices; The extracting the Doppler frequency shift caused by the motion of the target from the two optimal receiving devices respectively includes: A time-frequency spectrum is obtained from the new channel state information of each receiving device, and a frequency value corresponding to the maximum energy in the time-frequency spectrum at each moment is selected as the Doppler frequency shift caused by the movement of the target at that moment.

2. The non-contact moving target speed measurement method according to claim 1, wherein: Obtaining new channel state information after eliminating the random phase offset of the channel state information includes: Each of the receiving devices simultaneously receives radio frequency signals from the same transmitting device through at least two antennas thereof; The receiving device collects the channel state information from at least two of the antennas, and divides or conjugate-multiplies the channel state information collected from each of the antennas at the same time to obtain the new channel state information, thereby eliminating the random phase offset in the channel state information caused by time asynchrony between the receiving device and the transmitting device.

3. The non-contact moving target speed measurement method according to claim 2, wherein: The noise reduction filtering process uses a Savitzky-Golay filter or a sliding average filtering method to filter and reduce noise on the new channel state information.

4. The non-contact moving target speed measurement method according to claim 1, wherein: The identifying the target motion state according to the new channel state information includes: If the second peak of the autocorrelation function value of the amplitude signal or the phase signal of the new channel state information of at least one of the receiving devices is greater than a preset first threshold, it is determined that the target is moving; Alternatively, if the fluctuation of the amplitude signal or the phase signal of the new channel state information of at least one of the receiving devices is greater than a preset second threshold, it is determined that the target is moving.

5. The non-contact moving target speed measurement method according to claim 1, wherein: Calculating the moving speed of the target according to the Doppler frequency shift includes: According to the Doppler shift, the equations are constructed: Among them, f D1 and f D2 are the Doppler shifts obtained from the first and second optimally selected receiving devices, α R1 and α R2 are the angles of the target location relative to the first and second optimally selected receiving devices; α T is the angle of the target relative to the transmitting device; θ is the target's direction of movement; f is the frequency of the wireless signal; c is the speed of light; v is the target's speed; The target's motion direction θ is obtained by analyzing the equations: θ=(a T +a R1 ) / 2+angle(Φ2-Φ1cos(Δα / 2),Φ1sin(Δα / 2)); Where Φ1=f D1 cos((α T -α R2 ) / 2), Φ2=f D2 cos((α T -α R1 ) / 2), Δα=α R2 -α R1 , angle(a, b)=arctan2(b / a) is the inverse tangent function in the four quadrants; The target's motion speed v is obtained by the target's motion direction θ: v=-cf D1 / (fcos(θ-(α T +a R1 ) / 2)·2cos((α T -a R1 ) / 2)); Or, use the optimization algorithm to find the target's speed and direction of movement so that the objective function is minimized. The preferred objective function is v，θ for: Among them, f Dj It is the Doppler frequency shift obtained on the jth receiving device according to the given target's moving speed v and moving direction θ. is the Doppler frequency shift actually obtained on the jth receiving device, and M is the total number of the receiving devices used.

6. A non-contact moving target speed measurement system, characterized in that: include: Signal processing module, dynamic optimization module and motion speed calculation module; The signal processing module obtains channel state information including a target motion state through at least two receiving devices, eliminates a random phase offset of the channel state information to obtain new channel state information, and performs noise reduction filtering on the new channel state information; The dynamic optimization module identifies the target motion state according to the new channel state information, and dynamically selects the two optimal receiving devices if the target is moving; The movement speed calculation module extracts the Doppler frequency shift caused by the movement of the target from the two optimal receiving devices respectively, and calculates the movement speed of the target according to the Doppler frequency shift; the movement speed includes the magnitude and direction of movement.

7. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any one of the methods of claims 1 to 5 .

8. A computing device, characterized in that include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing any one of the methods according to claims 1 to 5.

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