Vehicle positioning method and system based on millimeter-wave identification technology

Abstract

This invention discloses a vehicle positioning method and system based on millimeter-wave identification technology. The system includes an onboard millimeter-wave radar mounted on the vehicle to be located and several millimeter-wave tags positioned on the roadside. The onboard millimeter-wave radar includes a transmitter, a receiver, and a signal processing module. The transmitter periodically transmits linear frequency modulated continuous wave signals to the surrounding environment. The millimeter-wave tags receive and modulate the linear frequency modulated continuous wave signals to generate tag signals and reflect them. The receiver receives radar echo signals, including tag signals reflected from the millimeter-wave tags and other environmental echo signals. The signal processing module processes multiple tag signals identified from the radar echo signals to obtain the true location information of the vehicle to be located. This system can achieve precise vehicle positioning and, compared to existing positioning systems, has lower cost and higher positioning accuracy.

Description

Technical Field

[0001] This invention belongs to the field of vehicle positioning technology, specifically relating to a vehicle positioning method and system based on millimeter-wave recognition technology. Background Technology

[0002] Intelligent Traffic Systems (ITS), as a large-scale, comprehensive transportation and management system, leverages the rapid development of the Internet of Things (IoT) in recent years. It efficiently combines advanced control, sensing, communication, and information technologies with computer technology, applying them comprehensively to the entire traffic management system. Because it significantly alleviates traffic congestion, effectively reduces traffic accidents, improves the safety of the transportation system, and reduces environmental pollution, it has become one of the most representative applications in the IoT field.

[0003] Achieving real-time and accurate vehicle positioning is a crucial component of intelligent transportation systems. To date, GPS (Global Positioning System) remains the most widely used technology in vehicle positioning, providing vehicles with real-time three-dimensional positioning, speed, and time information.

[0004] However, due to infrastructure obstructing direct GPS signal reception and generating multipath interference or non-line-of-sight reception, all GPS-based solutions exhibit significant performance losses in dense urban driving environments. Furthermore, positioning systems based on cameras, LiDAR, or roadside units are typically limited in terms of positioning accuracy and installation cost. Therefore, there is an urgent need for an effective solution to achieve high-precision vehicle positioning. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a vehicle positioning method and system based on millimeter-wave identification technology. The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] In a first aspect, the present invention provides a vehicle positioning method based on millimeter-wave recognition technology, comprising:

[0007] The vehicle-mounted millimeter-wave radar, mounted on the vehicle to be located, periodically transmits linear frequency modulated continuous wave signals to the surrounding environment.

[0008] The linear frequency modulated continuous wave signal is received and modulated using millimeter-wave tags installed on the roadside to generate tag signals and then reflected.

[0009] The vehicle-mounted millimeter-wave radar is used to receive radar echo signals; wherein, the radar echo signals include tag signals reflected from the millimeter-wave tag and other environmental echo signals;

[0010] The received radar echo signal is identified to obtain multiple tag signals reflected by different millimeter-wave tags. At the same time, the multiple tag signals are processed to obtain the real location information of the vehicle to be located.

[0011] In one embodiment of the present invention, the linear frequency modulated continuous wave signal is an orthogonal waveform signal generated using time-domain multiplexing technology.

[0012] In one embodiment of the present invention, a millimeter-wave tag disposed on the roadside is used to receive and modulate the linear frequency modulated continuous wave signal to generate a tag signal and reflect it, including:

[0013] The millimeter-wave tag reflects the linear frequency modulated continuous wave signal by backscattering, and simultaneously modulates its own position information onto the reflected signal to generate a tag signal, which is then reflected.

[0014] In one embodiment of the present invention, processing of multiple tag signals to obtain the true location information of the vehicle to be located includes:

[0015] The multiple tag signals are processed to obtain the corresponding tag position information and the distance, relative speed and azimuth angle information between the tag and the vehicle to be located.

[0016] Based on the least squares method, the true location information of the vehicle to be located is calculated by using the location information of multiple tags and the distance and azimuth information between the tag and the vehicle to be located.

[0017] Secondly, the present invention provides a vehicle positioning system based on millimeter-wave identification technology, including an on-board millimeter-wave radar mounted on the vehicle to be located and a number of millimeter-wave tags set on the roadside; wherein, the on-board millimeter-wave radar includes a transmitter, a receiver and a signal processing module;

[0018] The transmitter is used to periodically transmit linear frequency modulated continuous wave signals to the surrounding environment;

[0019] The millimeter-wave tag is used to receive and modulate the linear frequency modulated continuous wave signal to generate a tag signal and reflect it.

[0020] The receiver is used to receive radar echo signals; wherein, the radar echo signals include tag signals reflected from millimeter-wave tags and other environmental echo signals;

[0021] The signal processing module is used to identify the received radar echo signal, obtain multiple tag signals reflected by different millimeter-wave tags, and process the multiple tag signals to obtain the real location information of the vehicle to be located.

[0022] In one embodiment of the present invention, the transmitter specifically employs time-domain multiplexing technology to generate orthogonal waveform signals in order to obtain linear frequency modulated continuous wave signals and transmit them.

[0023] In one embodiment of the present invention, the millimeter-wave tag specifically reflects the linear frequency modulated continuous wave signal by backscattering, and simultaneously modulates its own position information onto the reflected signal.

[0024] In one embodiment of the present invention, the signal processing module includes an information extraction unit and a calculation unit; wherein,

[0025] The information extraction unit is used to process multiple tag signals to obtain the corresponding tag location information and the distance, relative speed and azimuth information between the tag and the vehicle to be located.

[0026] The calculation unit is used to calculate the true location information of the vehicle to be located based on the least squares method, using multiple tag location information and the distance and azimuth information between the tag and the vehicle to be located.

[0027] The beneficial effects of this invention are:

[0028] 1. The vehicle positioning system based on millimeter-wave identification technology provided by this invention utilizes the vehicle-mounted millimeter-wave radar on the vehicle to be located to communicate with millimeter-wave tags deployed on the roadside. By acquiring tag signals reflected from multiple tags, and then identifying and extracting the backscattered signals of the tags, the distance, relative speed, and azimuth information between the tags and the vehicle to be located are obtained; and the position information of the vehicle to be located is obtained by calculation. This method can still achieve accurate vehicle positioning in scenarios where GPS positioning is poor, and compared with positioning systems based on cameras, lidar, and roadside units, it has lower cost and higher positioning accuracy.

[0029] 2. The vehicle positioning system based on millimeter-wave identification technology provided by this invention makes full use of existing vehicle-mounted millimeter-wave radar as a reader to communicate with millimeter-wave tags, eliminating the need to install other hardware devices on the vehicle and saving installation costs.

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0031] Figure 1 This is a schematic flowchart of a vehicle positioning method based on millimeter-wave recognition technology provided in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram illustrating a scenario where a vehicle-mounted millimeter-wave radar communicates with millimeter-wave tags deployed on the road and other targets, as provided in an embodiment of the present invention.

[0033] Figure 3 This is a principle block diagram of MIMO-based radar identification provided in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the time-division multiplexing scheme provided in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the MIMO radar virtual receiver array configuration provided in an embodiment of the present invention;

[0036] Figure 6 This is a structural block diagram of a vehicle positioning system based on millimeter-wave recognition technology provided in an embodiment of the present invention;

[0037] Figure 7 This is a CDF curve diagram of the positioning error in straight and curved road scenarios provided by an embodiment of the present invention. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0039] Example 1

[0040] Please see Figure 1 , Figure 1 This is a flowchart illustrating a vehicle positioning method based on millimeter-wave recognition technology provided in an embodiment of the present invention, which includes:

[0041] Step 1: Use the onboard millimeter-wave radar mounted on the vehicle to be located to periodically transmit linear frequency modulated continuous wave signals to the surrounding environment.

[0042] Specifically, during vehicle operation, each onboard millimeter-wave radar transmitter periodically sends out linear frequency modulated continuous waves. When these signals are incident on various targets in the surrounding environment, they form echo signals.

[0043] In this embodiment, the linear frequency modulated continuous wave signal is an orthogonal waveform signal generated using time-domain multiplexing technology.

[0044] In order to support multiple channels, this embodiment selects a simple time-domain multiplexing technique that is widely used in automotive radar to generate orthogonal waveforms, which can help the vehicle-mounted millimeter-wave radar separate signals from different transmitter channels.

[0045] Step 2: Receive and modulate linear frequency modulated continuous wave signals using millimeter-wave tags installed on the roadside to generate tag signals and reflect them.

[0046] Specifically, when a roadside millimeter-wave tag receives a linear frequency modulated continuous wave (LFM) signal emitted by a vehicle-mounted millimeter-wave radar, it performs backscatter modulation on the signal. The millimeter-wave tag reflects the LFM signal via backscattering, simultaneously modulating its own position information onto the reflected signal to generate a tag signal, which is then reflected. See also... Figure 2 , Figure 2 This is a schematic diagram illustrating a scenario where a vehicle-mounted millimeter-wave radar communicates with millimeter-wave tags deployed on the road and other targets, as provided in an embodiment of the present invention.

[0047] It should be noted that the specific implementation method and signal modulation method of the millimeter wave tag can refer to existing related technologies, and will not be described in detail in this embodiment.

[0048] Step 3: Receive radar echo signals using the vehicle-mounted millimeter-wave radar; the radar echo signals include tag signals reflected from the millimeter-wave tag and other environmental echo signals.

[0049] Specifically, the vehicle-mounted millimeter-wave radar receives echo reflections from tags and other targets within the radar's detection range. The tags then backscatter and modulate the received radar incident signal, transmitting their own position information to the radar receiver.

[0050] Step 4: Identify the received radar echo signals to obtain multiple tag signals reflected by different millimeter-wave tags. Process the multiple tag signals to obtain the true location information of the vehicle to be located.

[0051] After identifying the tag signals, multiple tag signals need to be processed to obtain the corresponding tag location information, as well as the distance, relative speed, and azimuth angle information between the tag and the vehicle to be located.

[0052] Specifically, first, all receiving antennas receive radar echo signals from the tag, and the received signals are mixed and sampled with the transmitted signals to obtain an intermediate frequency (IF) signal. Second, the radar collects multiple scans of the waveform on each linear phased array antenna element. These collected scans form a data cube and are stored in a buffer. Once a certain number of scans fill the buffer, these scans are sequentially subjected to FFT operations along the fast and slow time dimensions of the data cube to obtain a range Doppler map containing the tag's relative velocity and range information. Finally, a third FFT is performed along the spatial dimension using the phase difference between the receiving antennas to generate an angular spectrum, obtaining the tag's azimuth angle.

[0053] To explain in detail the process by which an automotive millimeter-wave radar identifies tags, tag distance, relative speed, and azimuth from echo signals, the following explanation uses an automotive MIMO (multi-input multi-output) millimeter-wave radar as an example.

[0054] Please see Figure 3 , Figure 3 This is a principle block diagram of MIMO radar-based identification provided in an embodiment of the present invention. The MIMO radar includes M... t There are 1 transmitting antenna and the element spacing is d. t Uniform transmitting antenna array and having M r There are 1 receiving antenna and the element spacing is d. r A uniform receiving antenna array.

[0055] At the MIMO radar transmitter, the signal synthesizer generates a linear frequency modulated continuous wave by controlling the output frequency of the voltage-controlled oscillator. The generated linear frequency modulated continuous wave signal is then amplified by a power amplifier and transmitted by the transmitter antenna. A portion of the generated signal is fed into the receiver for mixing with the received signal to generate a baseband signal.

[0056] In MIMO radar operating in time-division multiplexing mode, only one transmit antenna is scheduled for transmission per time slot. The orthogonality of the transmitted frequency-modulated continuous waves is reflected in time; each time slot corresponds to M... t One transmission channel in a transmit antenna, continuously switching between transmit and receive channels among all possible channels to ensure that only one set of channels is active at any given time, such as... Figure 4 As shown.

[0057] Taking the first frequency modulation cycle of a certain transmitting antenna as an example, and neglecting the initial phase, the instantaneous frequency of the transmitted signal at any time t (0 ≤ t ≤ T) is given by the following formula:

[0058]

[0059] In the formula, f0 is the starting frequency of the linear frequency modulated pulse. Here, is the scan slope, T is the scan period, and B is the transmission bandwidth. Therefore, during the tag response period, the m-th... t Transmitted signals of each channel It can be modeled as a function of time t:

[0060]

[0061] in, It is the amplitude of the transmitted signal, m t =1,2,...M tThe millimeter-wave tag backscatters the incident signal from the radar and utilizes a frequency of f. mod The radar cross section of the tag is modulated by a periodic signal. This results in the backscattered signal of the millimeter-wave tag being given by the following equation:

[0062]

[0063] in, The signal comes from the mth t The time it takes for the propagation from the location of the transmitting antenna to the location of the millimeter-wave tag, and ω 1,mt (t) is additive white Gaussian noise with zero mean and variance. The modulated signal s mod (t) can be approximated as a rectangular waveform with a 50% duty cycle, causing the tag's radar cross-section to vary between two states according to the modulation frequency. Since s mod (t) is a period of T mod =1 / f mod The function can therefore be expanded using a Fourier series as:

[0064]

[0065] Among them, c k These are the Fourier coefficients.

[0066] In M r In a channel configured as a receiver, the received signal attenuates due to the propagation distance and is delayed by the round-trip time τ. 2,mr Then the m-th receiver of the radar array r The backscattered signal from the tag received by each element at the baseband is written as:

[0067]

[0068] in, It refers to the received signal amplitude, which is related to the tag's radar cross-section, path loss, antenna gain, etc. It is additive white Gaussian noise with zero mean and variance.

[0069] Then, by the radar receiver M r The signal received by each component is amplified by a low-noise amplifier and mixed with the transmitted signal. The resulting intermediate frequency signal can be modeled as follows:

[0070]

[0071] in, Indicates the amplitude of the intermediate frequency signal. Depending on the position of the signal passing through the MMID tag from the mth t The position of the transmitting antenna propagates to the m-th antenna.r The time spent on the location of each receiving antenna It's noise.

[0072] For the above-mentioned vehicle-mounted MIMO radar, assume that the spacing between the transmitting array elements satisfies:

[0073] d t =M r ·d r

[0074] MIMO radar using time-division multiplexing can synthesize a virtual receiver array, which is equivalent to having M t ×M r Each element and spacing d r A uniform linear array, such as Figure 5 As shown.

[0075] Assume m t ·d t and m r ·d r Let {(R} be the x-coordinates corresponding to the positions of each transmitter and receiver antenna. i ,θ i Let )|i=1,2,...Q} represent the position of the i-th tag in spherical coordinates, with respect to the radar velocity v. i Movement. Q is the maximum number of tags observed by the vehicle's radar at a given moment. For the i-th tag, the round-trip time delay is remodeled as:

[0076]

[0077] Where l = 1, 2, ..., L-1, and L is the number of frequency modulation cycles. m = M r ×m t +m r m = 1, 2, ..., M t ×M r Let m represent the m-th antenna in the virtual receiver array, and c be the speed of light.

[0078] Since the frequency modulation period is very small, typically on the order of microseconds, the relative speed between the tag and the vehicle can be assumed to remain constant over L pulses. Meanwhile, in a radar system based on a digital receiver, the intermediate frequency (IF) signal at the mixer output passes through a low-pass filter and is sampled and converted into a digital signal by an analog-to-digital converter. Therefore, for Q tags, the IF signal received by the m-th antenna channel can be expressed as...

[0079]

[0080] Where n = 1, 2, ..., N s -1, N s This represents the number of samples. It is the Doppler frequency shift generated between the vehicle's movement and the i-th tag, which is inversely proportional to the wavelength λ, and its sign is positive or negative, depending on whether the tag is approaching or moving away from the radar.

[0081] First, the intermediate frequency (IF) signal is recorded and subjected to a Fast Fourier Transform (FFT) in the frequency domain to detect the tag signal. When the tag is unmodulated, the tag signal cannot be detected because it is masked by strong reflections from other targets, clutter, and phase noise interference. However, when the tag is modulated, two distinct peaks appear in the spectrum of the IF signal around the modulation frequency. Then, using the unmodulated received signal as a reference for background subtraction, major multipath reflections from surrounding targets (such as road signs or nearby vehicles) can be eliminated. Due to the tag's backscatter modulation, the tag signal is preserved after background subtraction, allowing for tag identification based on different radar cross sections.

[0082] Obviously, the aforementioned intermediate frequency signal s IF (n,l,m) remains a linear frequency modulated signal, and its frequency and phase are closely related to the distance and speed information of the tag. Therefore, the frequency and phase of the intermediate frequency signal corresponding to the i-th tag can be obtained as follows:

[0083]

[0084]

[0085] It is important to note that, due to the rapid decrease of the Fourier coefficients with respect to the harmonic exponent k, higher harmonics (k>1) are typically below the background noise and will not be detected. Therefore, based on the above equation, the modulation frequency for the i-th tag can be easily found. The frequency offset and phase offset centered are:

[0086]

[0087]

[0088] Then, the distance and relative velocity of the i-th label are:

[0089]

[0090]

[0091] Furthermore, the phase difference between receiving antennas can be used to identify tags in the azimuth plane. In a virtual receiving array, the phase difference between adjacent receiving channels can be expressed as:

[0092]

[0093] Therefore, the orientation angle of the i-th label can be determined as follows:

[0094]

[0095] Through the above operations, the tag's location information, as well as the distance, relative speed, and azimuth angle between the tag and the vehicle to be located, can be identified from the radar echo signal.

[0096] Finally, based on the least squares method, the true location information of the vehicle to be located is calculated using the location information of multiple tags and the distance and azimuth information between the tag and the vehicle to be located.

[0097] Optionally, as one implementation, this embodiment uses the relevant information of the three tag signals to calculate the position information of the vehicle to be located. Specifically, after obtaining the distance and azimuth information of at least three tags and the actual position information, the position coordinates of the vehicle to be located can be calculated using the least squares algorithm, which can minimize the sum of squares of the errors between the final vehicle position coordinates and the actual vehicle position coordinates.

[0098] For details on the implementation of the least squares method, please refer to existing related technologies; this embodiment will not provide a detailed explanation.

[0099] The method provided in this embodiment utilizes an onboard millimeter-wave radar on the vehicle to be located to communicate with millimeter-wave tags deployed on the roadside. By acquiring tag signals reflected from multiple tags, and then identifying and extracting the backscattered signals of the tags, it obtains the distance, relative speed, and azimuth information between the tags and the vehicle to be located. The position information of the vehicle to be located is then calculated. This method can still achieve accurate vehicle positioning even in scenarios where GPS positioning is ineffective, and compared to positioning systems based on cameras, LiDAR, and roadside units, it has lower cost and higher positioning accuracy. Furthermore, this method eliminates the need to install other hardware on the vehicle, saving installation costs.

[0100] Example 2

[0101] This embodiment provides a vehicle positioning system based on millimeter-wave identification technology to implement the method provided in Embodiment 1 above. Please refer to... Figure 6 , Figure 6 This is a structural block diagram of a vehicle positioning system based on millimeter-wave recognition technology provided in an embodiment of the present invention, which includes:

[0102] The vehicle-mounted millimeter-wave radar is mounted on the vehicle to be located, and several millimeter-wave tags are set on the roadside; the vehicle-mounted millimeter-wave radar includes a transmitter, a receiver, and a signal processing module.

[0103] The transmitter is used to periodically transmit linear frequency modulated continuous wave signals into the surrounding environment;

[0104] Millimeter-wave tags are used to receive and modulate linear frequency modulated continuous wave signals to generate tag signals and reflect them;

[0105] The receiver is used to receive radar echo signals; wherein, the radar echo signals include tag signals reflected from millimeter-wave tags and other environmental echo signals;

[0106] The signal processing module is used to identify the received radar echo signals, obtain multiple tag signals reflected by different millimeter-wave tags, and process multiple tag signals to obtain the real location information of the vehicle to be located.

[0107] Optionally, as one implementation method, the transmitter specifically uses time-domain multiplexing technology to generate orthogonal waveform signals to obtain linear frequency modulated continuous wave signals for transmission.

[0108] In this embodiment, a group of millimeter-wave tags are regularly distributed and widely deployed along lane markings and road boundary lines. Each millimeter-wave tag specifically reflects a linear frequency modulated continuous wave signal through backscattering, while simultaneously modulating its own position information onto the reflected signal.

[0109] Furthermore, the signal processing module includes an information extraction unit and a computation unit; wherein,

[0110] The information extraction unit is used to process multiple tag signals to obtain the corresponding tag location information and the distance, relative speed and azimuth angle information between the tag and the vehicle to be located.

[0111] The calculation unit is used to calculate the true location information of the vehicle to be located based on the least squares method, using multiple tag location information and the distance and azimuth information between the tag and the vehicle to be located.

[0112] The system provided in this embodiment can implement the method provided in Embodiment 1 above. For the specific implementation process, please refer to Embodiment 1 above, which will not be repeated here.

[0113] Therefore, the vehicle positioning system based on millimeter-wave identification technology provided in this embodiment can still achieve accurate vehicle positioning even in scenarios where GPS positioning is ineffective. Compared with positioning systems based on cameras, LiDAR, and roadside units, it has lower cost and higher positioning accuracy. Furthermore, the system makes full use of existing vehicle-mounted millimeter-wave radar as a reader to communicate with millimeter-wave tags, eliminating the need to install other hardware devices on the vehicle and saving installation costs.

[0114] Example 3

[0115] The beneficial effects of the present invention will be further illustrated by the following experiments.

[0116] Specifically, vehicle motion and road scenarios were modeled. In a straight-road scenario, 16 sets of millimeter-wave tags were evenly and intermittently deployed on both sides of a 500m long and 3.35m wide horizontal road, with tags on the same side spaced 30m apart. The target vehicle traveled forward at a constant horizontal speed, and the vehicle-mounted millimeter-wave radar, installed at the front of the vehicle, detected and identified the roadside millimeter-wave tags with a maximum detection range of 200m. Similarly, in a curved scenario, 12 sets of millimeter-wave tags were deployed on a 377m long and 3.35m wide S-shaped curve to support precise vehicle positioning.

[0117] Please see Figure 7 , Figure 7 The CDF curves of the positioning error of this embodiment of the invention are shown in straight and curved road scenarios. This embodiment of the invention can achieve centimeter-level positioning of vehicles. Furthermore, the results show that the positioning performance in curved scenarios is slightly lower than that in straight road scenarios. This result is predictable because the detection performance of radar decreases in curved scenarios, increasing the initial estimation error of the vehicle. Additionally, on road sections with greater curvature, it affects subsequent detection and recognition of roadside tags, thereby reducing the estimation performance of the vehicle's position.

[0118] In the vehicle positioning system based on millimeter-wave identification technology provided by this invention, the vehicle to be located communicates with millimeter-wave tags deployed on the roadside via an onboard millimeter-wave radar to obtain the location information of multiple tags. Then, by identifying and extracting the backscattered signals of the tags, the distance, relative speed, and azimuth information between the tags and the vehicle to be located are obtained. Finally, based on the distance and azimuth information of the tags and the actual location information, high-precision positioning of the vehicle to be located is achieved. This invention fully utilizes existing onboard millimeter-wave radar as a reader to communicate with millimeter-wave tags, without the need to install other hardware devices on the vehicle. Furthermore, this invention can still achieve accurate vehicle positioning even in scenarios where GPS positioning is ineffective, and compared to positioning systems based on cameras, LiDAR, and roadside units, it has lower costs and higher positioning accuracy.

[0119] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A vehicle positioning method based on a millimeter wave recognition technology, characterized by, The method comprises the steps of: The vehicle-mounted millimeter-wave radar, installed on the vehicle to be located, periodically transmits linear frequency modulated continuous wave signals to the surrounding environment; the vehicle-mounted millimeter-wave radar is a vehicle-mounted MIMO millimeter-wave radar, comprising... There are one transmitting antenna and the element spacing is [missing information]. Uniform transmitting antenna array and having There are one receiving antenna and the element spacing is... A uniform receiving antenna array; receiving and modulating the linear frequency modulation continuous wave signal by the millimeter wave tag arranged on the roadside to generate a tag signal and reflect it; receiving a radar echo signal by the vehicle-mounted millimeter wave radar; wherein the radar echo signal comprises the tag signal reflected by the millimeter wave tag and other environmental echo signals; identifying the received radar echo signal to obtain a plurality of tag signals reflected by different millimeter wave tags, and processing the plurality of tag signals to respectively obtain corresponding tag position information and distance, relative speed and azimuth angle information of the tag and the current vehicle to be positioned, specifically comprising: mixing and sampling the received tag signal and the transmitted linear frequency modulation continuous wave signal to obtain an intermediate frequency signal; The frequency and phase of the intermediate frequency signal of the first tag are obtained by performing fast Fourier transform on the intermediate frequency signal in the frequency domain and using a non-modulated received tag signal for background subtraction. i The frequency and phase of the intermediate frequency signal of the first tag are obtained by performing fast Fourier transform on the intermediate frequency signal in the frequency domain and using a non-modulated received tag signal for background subtraction. wherein, is the scan slope, is the scan period, is the transmission bandwidth, is the harmonic index, is the position of the th tag in spherical coordinates, moving with a velocity relative to the radar, is the maximum number of tags observed by the vehicle radar at a certain time instant; is the Doppler shift between the vehicle motion and the th tag, is the wavelength, is the speed of light, is the starting frequency of the chirp. The modulation frequency of the first tag is centered at a frequency offset and a phase offset of: Then, the distance and relative velocity of the first i tag are: in the virtual receiving array, the phase difference between adjacent receiving channels can be represented as: The direction angle information of the first label is solved as: ​ based on the least square method, calculating the real position information of the vehicle to be positioned by using the plurality of tag position information and the distance and azimuth angle information of the tag and the current vehicle to be positioned. 2.The vehicle positioning method based on the millimeter wave recognition technology according to claim 1, wherein, The linear frequency modulation continuous wave signal is an orthogonal waveform signal generated by using a time domain multiplexing technology. 3.The vehicle positioning method based on the millimeter wave recognition technology according to claim 1, wherein, receiving and modulating the linear frequency modulation continuous wave signal by the millimeter wave tag arranged on the roadside to generate a tag signal and reflect it, comprising: The millimeter wave tag reflects the linear frequency modulation continuous wave signal by backscattering, and modulates the position information of the tag onto the reflected signal to generate a tag signal and reflect it.

4. A vehicle positioning system based on millimeter wave recognition technology, characterized by, This includes an onboard millimeter-wave radar mounted on the vehicle to be located and several millimeter-wave tags placed on the roadside; wherein, the onboard millimeter-wave radar includes a transmitter, a receiver, and a signal processing module; the onboard millimeter-wave radar is an onboard MIMO millimeter-wave radar, comprising... There are one transmitting antenna and the element spacing is [missing information]. Uniform transmitting antenna array and having There are one receiving antenna and the element spacing is... A uniform receiving antenna array; The transmitter is configured to periodically transmit a linear frequency modulation continuous wave signal to the surrounding environment. The millimeter wave tag is configured to receive and modulate the linear frequency modulation continuous wave signal to generate a tag signal and reflect it. The receiver is configured to receive a radar echo signal; wherein the radar echo signal comprises the tag signal reflected by the millimeter wave tag and other environmental echo signals. The signal processing module is configured to identify the received radar echo signal to obtain a plurality of tag signals reflected by different millimeter wave tags, and process the plurality of tag signals to respectively obtain corresponding tag position information and distance, relative speed and azimuth angle information of the tag and the current vehicle to be positioned, specifically comprising: mixing and sampling the received tag signal and the transmitted linear frequency modulation continuous wave signal to obtain an intermediate frequency signal; The frequency and phase of the intermediate frequency signal of the first tag are obtained by performing fast Fourier transform on the intermediate frequency signal in the frequency domain and using a non-modulated received tag signal for background subtraction. i The frequency and phase of the intermediate frequency signal of the first tag are obtained by performing fast Fourier transform on the intermediate frequency signal in the frequency domain and using a non-modulated received tag signal for background subtraction. wherein, is the scan slope, is the scan period, is the transmission bandwidth, is the harmonic index, is the position of the th tag in spherical coordinates, moving with a velocity relative to the radar, is the maximum number of tags observed by the vehicle radar at a certain time instant; is the Doppler shift between the vehicle motion and the th tag, is the wavelength, is the speed of light, is the starting frequency of the chirp. The modulation frequency of the first tag is centered around a frequency offset and a phase offset of : Then, the distance and relative velocity of the first i tag are: in the virtual receiving array, the phase difference between adjacent receiving channels can be represented as: The direction angle information of the first label is solved as: ​ based on the least square method, calculating the real position information of the vehicle to be positioned by using the plurality of tag position information and the distance and azimuth angle information of the tag and the current vehicle to be positioned.

5. The vehicle positioning system based on millimeter wave recognition technology according to claim 4, characterized in that, The transmitter specifically generates an orthogonal waveform signal by using a time domain multiplexing technology to obtain a linear frequency modulation continuous wave signal and transmit it.

6. The vehicle positioning system based on millimeter wave recognition technology according to claim 5, wherein, The millimeter wave tag specifically reflects the linear frequency modulation continuous wave signal by backscattering, and modulates the position information of the tag onto the reflected signal.

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