CN114942438A - Night vision system and night vision method based on millimeter wave radar - Google Patents
Night vision system and night vision method based on millimeter wave radar Download PDFInfo
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- CN114942438A CN114942438A CN202210461416.8A CN202210461416A CN114942438A CN 114942438 A CN114942438 A CN 114942438A CN 202210461416 A CN202210461416 A CN 202210461416A CN 114942438 A CN114942438 A CN 114942438A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
Abstract
The invention provides a night vision system and a night vision method based on a millimeter wave radar, aiming at the characteristic that the night vision system only needs to roughly depict the outline of a human body without clearly identifying accurate environment details, the capacity of displaying the rough outline of the human body in a specific scene is realized through the algorithm optimization of the millimeter wave radar, and the limitation that the original millimeter wave radar technology can only identify the length, the width and other parameter information of an object is changed. The millimeter wave radar adopted by the invention is not limited by environment, can be started under various environmental conditions, and provides support and guarantee for the driving safety of a driver at night. The invention is based on the current mainstream vehicle configuration, completes night vision function without adding other devices such as an infrared camera, and saves cost. The invention is simple and practical, is suitable for all vehicle types, can interact with various types of millimeter wave radar systems, and performs modular operation.
Description
Technical Field
The invention belongs to the technical field of vehicle environment sensing detection, and particularly relates to a night vision system and a night vision method based on a millimeter wave radar.
Background
The current night vision system for automobiles can change the darkness to be like the daytime by using an infrared technology, so that a driver can see more clearly in the dark. The structure of the night vision system consists of two parts: one part is an infrared camera and the other part is a display system. The night vision system needs to consider the imaging technology in the state without visible light during design. Generally, the infrared night vision image is limited to a single red frequency band, so the infrared night vision image is generally a black-white or black-green image. Generally limited by the infrared wave resolving power, the restored image has a certain difference from visible light, see fig. 1.
The existing night vision system cannot be supported by an infrared system (an infrared camera), and with the help of the auxiliary system, a driver can obtain higher anticipation ability at night or in the weak light driving process, and the auxiliary system can provide more comprehensive and accurate information or give early warning to the driver aiming at potential danger.
The infrared night vision is carried out by the camera at night. The infrared night vision camera is characterized in that under a dark environment without visible light or glimmer light, an infrared emitting device is adopted to project infrared light to an object actively, the infrared light enters a lens to form an image after being reflected by the object, and a monitoring picture which can not be seen by human eyes under the dark environment can be shot. The monitoring picture shot at night is usually a black and white image.
1) Because the infrared night is limited by the environment because of the performance of the camera, for example, the performance is reduced or degraded at high temperature, the infrared camera cannot be arranged in a high-temperature area, and the like, and the design of the infrared camera is also limited.
2) The infrared camera can only be used for night vision with a single function, has huge competitive pressure in the current automobile market, needs to reduce the cost, and is specially arranged at the current time so as not to be paid.
The existing air night vision system does not have an infrared camera, but the two infrared cameras which are very mature are applied to the automobile and can only be used for night vision with a single function; in addition, the competition pressure in the current automobile market is huge, and the cost needs to be reduced, so that the special infrared camera for the automobile is specially arranged at the current, and huge cost pressure is generated; if a certain joint-market vehicle type can be equipped with the night vision function on the top, the price is 3000 yuan.
The millimeter wave has the advantages of microwave and infrared, has certain penetrating power, and can distinguish objects with different physical properties according to the size of scattering energy, so that the application of the millimeter wave radar on a night vision system becomes possible. The existing millimeter wave radar is used for ADAS functions such as ACC \ AEB and the like; however, the millimeter wave radar technology can only identify parameter information such as the length and the width of an object, and cannot image the environment or a human body.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: a night vision system and a night vision method based on a millimeter wave radar are provided for realizing a function of monochrome display with discrimination on a human body outline in a night vision image.
The technical scheme adopted by the invention for solving the technical problems is as follows: the night vision method based on the millimeter wave radar comprises the following steps:
s0: the night vision system based on the millimeter wave radar is built and comprises the millimeter wave radar, an illumination sensor, a central controller and a display unit, wherein the millimeter wave radar, the illumination sensor, the central controller and the display unit are respectively hung on a whole vehicle bus; the millimeter wave radar comprises an antenna, a signal source, a circulator, a mixer, an amplifier, a sampler, an AD converter and a signal processor;
s1: the illumination sensor collects an illumination signal and sends the illumination signal to the central controller through the bus of the whole vehicle; the central controller judges whether the function is started or not through the function switch signal, and requests to start the night vision function if the switch signal is received and the current state of the millimeter wave radar is normal in standby;
s2: the millimeter wave radar sequentially sends millimeter waves through an antenna and receives echoes of each frequency point in a millimeter wave frequency band to obtain basic echo signals, then the echo signals are subjected to Fourier summation and conversion to spatial frequency, and the basic echo signals are recorded as superposition of plane waves with different azimuth angles and pitch angles and different wave numbers in a reasonable working echo interval; collecting spatial interference fringes, recording a diffraction pattern of each scattering point on a target, and sequentially and rapidly scanning to perform single-channel imaging;
s3: the central controller analyzes and processes the echo signals, performs phase compensation on each plane wave component, restores the phase signals into actual three-dimensional distance distribution of a target, analyzes and extends the frequency spectrum of an expanded image in a frequency domain, improves the resolution and reconstructs the image to obtain night vision imaging by decomposing and reducing noise, restoring maximum likelihood and analyzing and extending the frequency spectrum of the expanded image in the frequency domain;
s4: the central controller sends the image to the display unit for display.
According to the scheme, in the step S2, the scanning track of the millimeter wave radar in the scene is approximately a long and narrow ellipse, and the imaging speed is 1 Hz; the scanning speed is determined according to the integration time and the imaging time, and the maximum integration time is adopted within the allowed imaging time so as to improve the sensitivity of the system; the constraint relation between the scanning speed and the integration time is as follows:
according to the scheme, in the step S2, single-channel imaging is performed when one array element of the antenna is transmitting and the other array element of the antenna is receiving, and the other antennas are in the off state.
According to the scheme, in the step S2, the specific steps are as follows:
s21: a signal source transmits millimeter wave signals outwards through a circulator and an antenna;
s22: echo signals of millimeter wave signals after being scattered by a target are received by an antenna;
s23: the signal received by the antenna is divided into two paths after passing through the circulator, and the two paths of signals are respectively mixed with one path of local oscillation signal and the other path of delayed local oscillation signal to obtain two orthogonal zero intermediate frequency signals I and Q;
s24: the zero intermediate frequency signal sequentially passes through an amplifier, a filter and AD sampling to obtain a discrete digital signal;
s25: setting an echo beam which is emitted by the millimeter wave radar and has a specific width and is scattered by a target at a position (X, Y, z) to be received by an antenna at the position (X, Y), wherein omega is an echo angle measured and calculated by the millimeter wave radar by taking a radar central plane as a reference; a (x, y, z) is the complex amplitude distribution of the target radiation, K is the number of circular waves, r is the distance, K and r are both vectors in the three-dimensional space, and K r is the vector dot product of the K and r; performing down-conversion and low-pass filtering in sequence to obtain a signal of each frequency point as follows:
let E (x, y, ω) be the time domain signal after fourier transforming the time dimension FT:
E(X，Y，ω)＝FT[E(X，Y，t)]，
let K x 、K y And K z For the anisotropic component of K, the dot product of K and r is:
K·r＝(x-X)K x +(y-Y)Ky+(z-Z)Kz；
unfolding and gathering spherical waves into superposition of plane waves, and substituting the superposition into an original formula to obtain the plane wave:
a three-dimensional fourier transform is used on the above equation:
this equation is a two-dimensional inverse fourier transform, IFT, obtained by ignoring the constant term:
obtaining:
the night vision imaging formula of the millimeter wave radar obtained by inverse transformation of the formula is as follows:
further, in step S3, the specific steps include:
let c be the speed of light, then K z The following relationships exist:
carrying out time dimension processing on a night vision imaging formula to obtain distance information of a target; assuming B as the bandwidth, the distance-wise resolution is:
the night vision system based on the millimeter wave radar comprises the millimeter wave radar, an illumination sensor, a central controller and a display unit, wherein the millimeter wave radar, the illumination sensor, the central controller and the display unit are respectively hung on a whole vehicle bus; the millimeter wave radar is used for acquiring electromagnetic wave reflection information of a real scene environment, determining a reflection echo and a scattering echo of a target and forming an original input of a target image; the millimeter wave radar comprises an antenna, a signal source, a circulator, a mixer, an amplifier, a sampler, an AD converter and a signal processor; the signal source is used for transmitting millimeter wave signals outwards through the circulator and the antenna; the antenna is used for transmitting and receiving signals; the circulator is used for dividing signals into multiple paths; the mixer is used for mixing the multi-channel signals; the amplifier, the sampler and the AD converter are respectively used for amplifying, sampling and carrying out analog-to-digital conversion on the signals; the signal processor is used for imaging the discrete digital signals; the illumination sensor is used for acquiring an illumination signal; the central controller is used for storing an algorithm comprising an ADAS function, processing the fused image information and controlling the vehicle to act according to a torque and braking deceleration request under the condition of meeting the condition; the display unit is used for outputting quasi-image information for a driver to view; the whole vehicle bus is used for providing signals required by the night vision system comprising a switching signal of the night vision system and a real-time vehicle speed signal to the central controller.
Further, the antennas are two-dimensional arrays in the OXY plane, with the OXY plane where the target is located at a distance R from the OXY plane.
A computer storage medium having stored therein a computer program executable by a computer processor, the computer program performing a millimeter wave radar based night vision method.
The invention has the beneficial effects that:
1. according to the night vision system and the night vision method based on the millimeter wave radar, the existing millimeter wave radar system of the original vehicle is utilized for the existing infrared night vision system, under the condition that extra configuration is not added, spatial interference fringes are collected, the diffraction pattern of each scattering point on a target is recorded by utilizing the coherence principle of electromagnetic waves, and finally a millimeter wave night vision image of the target is obtained through image reconstruction; specific night vision image support is provided for a driver, and a monochrome display function with discrimination on the human body outline is realized.
2. Aiming at the characteristic that a night vision system only needs to roughly depict the human body contour and does not need to clearly identify accurate environment details, the method improves the feedback resolution and quality under limited conditions through the algorithm optimization of the millimeter wave radar, realizes the capability of displaying the rough human body contour in a specific scene, obtains a three-dimensional millimeter wave image of a target, restores the real shape of the target, improves the resolution and the sensitivity, and simultaneously improves the target identification probability; the limitation that the original millimeter wave radar technology can only identify parameter information such as the length, the width and the like of an object is changed.
3. The millimeter wave radar adopted by the invention is not limited by environment, can be started under various environmental conditions, and provides support and guarantee for the driving safety of a driver at night.
4. Based on the current mainstream vehicle configuration, the night vision function is completed under the condition that other equipment such as an infrared camera is not additionally arranged, so that the cost is saved; the vehicle model equipped with the millimeter wave radar and having the ADAS function is configured from the second lowest distribution or the middle distribution, and the infrared night vision is generally configured at the top distribution; the invention is simple and practical, is suitable for all vehicle types, can interact with various types of millimeter wave radar systems, and performs modular operation.
Drawings
Fig. 1 is an infrared diagram of a prior art night vision system.
Fig. 2 is a functional block diagram of an embodiment of the present invention.
FIG. 3 is a functional block diagram of an imaging system of an embodiment of the present invention.
Fig. 4 is a circuit diagram of an imaging system of an embodiment of the present invention.
Fig. 5 is a signal processing flow diagram of an embodiment of the invention.
Fig. 6 is a theoretical schematic of an embodiment of the invention.
FIG. 7 is a flow chart of an imaging algorithm of an embodiment of the present invention.
Fig. 8 is a flow chart of an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Referring to FIG. 2, an embodiment of the present invention includes a millimeter wave radar supporting partial algorithm control, a central controller (with a substantially millimeter wave radar-based night vision system), and a display system; the millimeter wave radar, the central controller and the display system are all hung on the whole vehicle CAN bus.
The millimeter wave radar is used for collecting electromagnetic wave reflection information of a real scene environment, determining a target reflection flash echo and forming original input of a target image;
the whole vehicle CAN bus is used for providing signals required by a night vision system, such as a point night vision system switching signal and a real-time vehicle speed signal, to the central controller;
the central controller (with millimeter wave radar based night vision system algorithm) is used for 1) storage and calculation of the functional algorithm of the present invention; 2) fusing and processing image information; 3) an algorithm program for normal ADAS, etc. functions is stored and corresponding torque and brake deceleration requests are calculated for control if conditions are met.
The display system is used for providing quasi-image information for a driver to view;
the central controller processor of the present invention, as distinguished from the millimeter wave radar system, requires a greater level of computation and some image processing capability.
Referring to fig. 3, the imaging system to be used in the present invention is designed as follows, wherein the existing millimeter wave radar and antenna at the front end are configured by the prior art and hardware:
1. the subsequent hardware of the imaging system mainly comprises an antenna, a signal source, a mixer, an amplifier, a sampler, a signal processor and the like. The millimeter wave signal is radiated from the antenna through the circulator, the echo signal is received by the antenna after being scattered by the target, then the signal is mixed with the local oscillator signal to obtain a zero intermediate frequency signal, and the signal after passing through the amplifier and the filter enters the AD sampling to obtain a discrete digital signal
2. The front end structure of the imaging system is as shown in fig. 4, a millimeter wave signal transmitted by the system is received by a receiving antenna after being scattered by a target, the signal is divided into two paths after passing through a circulator, the two paths of signals are respectively mixed with two paths (one path of delayed) of local oscillator signals to obtain two orthogonal I, Q signals, and the signals are amplified by an amplifier and subjected to AD sampling to be imaged.
3. During operation, each millimeter wave antenna is scanned sequentially and rapidly, that is, only one array element is transmitting and the other array element is receiving at the same time, and other antennas are in a closed state. The invention is therefore single channel imaging.
4. The software architecture design of the signal processing of the night vision system of the millimeter wave radar is shown in fig. 5.
The night vision rendering algorithm of the invention is (built in the imaging processing module):
1. the invention discloses a night vision imaging algorithm, which aims to improve the feedback resolution and the quality under the limited condition so as to achieve the purpose of displaying a night vision image. The night vision imaging algorithm can obtain a three-dimensional millimeter wave image of a target, can restore the real shape of the target, improves the resolution and the sensitivity, and simultaneously improves the target recognition probability. Millimeter wave imaging utilizes the coherence principle of electromagnetic waves, records the diffraction pattern of each scattering point on a target by collecting spatial interference fringes, and finally obtains a millimeter wave night vision image of the target through image reconstruction.
2. The millimeter wave radar antenna receives the echo of each frequency point in the millimeter wave frequency band in proper order, obtains basic callback signal, passes through Fourier and converts echo signal to spatial frequency, popular language: and recording the echo as superposition of plane waves with different azimuth angles, pitch angles and different wave numbers in a reasonable working echo interval. And finally, carrying out phase compensation on each plane wave component to restore the actual three-dimensional distance distribution of the target. And the central controller obtains a three-dimensional image by taking a model.
3. The night vision system theory principle based on the millimeter wave radar is shown in figure 6, the millimeter wave radar has a two-dimensional antenna receiving array on an XY plane, and an OXY plane where a target is located is arranged at a distance R from the XY plane. The target can be traced through an algorithm to form a night vision image.
4. The night vision system algorithm based on the millimeter wave radar is arranged in the central controller, and specifically comprises the following steps: after a wave beam with a specific width of a millimeter wave transmitting antenna of the millimeter wave radar is scattered by a target at the position (X, Y, z), the reflected wave beam is received by a receiving antenna at the position (X, Y), and omega is an echo angle measured and calculated by the millimeter wave radar by taking a radar central plane as a reference; and then, performing down-conversion and low-pass filtering, wherein the signal of each frequency point can be obtained as follows:
where A (x, y, z) is the complex amplitude distribution of the target radiation, K is the number of circular waves, r is the distance, K and r are both vectors in three-dimensional space, and K.r is the vector dot product thereof. E (x, y, ω) is a time domain signal obtained by fourier transforming the time dimension (denoted as FT), that is:
E(X，Y，ω)＝FT[E(X，Y，t)]
the dot product of K and r at this time is:
K·r＝(X-X)K x +(y-Y)k y +(z-Z)K z
in the formula K x 、K y And K z Is the isotropic component of K. The spherical waves are unfolded and can be collected into superposition of plane waves, and then the superposition is substituted into the original formula:
the above equation uses a three-dimensional fourier transform, namely:
this time equation is again a two-dimensional inverse fourier transform (operation denoted as IFT), ignoring the constant term, and includes:
the following can be obtained:
the imaging formula for obtaining the millimeter wave night vision imaging is obtained by performing inverse transformation on the formula as follows:
the formula is an imaging formula of the night vision system algorithm based on the millimeter wave radar.
Wherein K is z The following relationships exist:
the night vision system algorithm formula based on the millimeter wave radar also processes the time dimension to obtain the distance information of the target. The distance-wise resolution can be calculated by:
where c is the speed of light and B is the bandwidth.
1. When the system is applied to automobiles and practical application, the speed and the stability are balanced. Therefore, a scanning method is needed, and electromagnetic waves greatly influence the imaging quality along with the automobile motion vibration generated by the millimeter wave radar during scanning and the vibration generated by inertia during the deceleration and acceleration processes during steering. The millimeter wave radar needs to separate the front end from the data acquisition system, and can be separately and independently controlled, so that the stability of the system is improved. In the invention, the system design and implementation are relatively simple, and the main characteristic is that the scanning track in the scene is approximate to a long and narrow ellipse. The imaging speed is 1Hz (calibrated) when the method is applied to a final imaging system. Note: the millimeter wave scanning track technology is not repeated for the prior art, is mainly used for a millimeter wave radar to track a target, and only restricts the tracking area of the millimeter wave radar.
2. The final comprehensive scanning speed of the invention comprehensively considers the integration time and the imaging time, and the maximum integration time is adopted in the allowed imaging time to improve the system sensitivity. Also in light of the foregoing discussion, the scan speed and integration time should have the following constraints:
if λ is 8mm and τ is 2ms, v is <2 m/s. Taking a millimeter wave image of 2m × 2m as an example, it is assumed that the scanning time accounts for 10% and the integration time is 2 ms. And carrying out imaging time constraint control. (the actual vehicle type is determined according to the actual conditions of lambda and tau)
3. Imaging algorithms directly affect system quality and are the subject of imaging. The invention processes the image in a plurality of ways flexibly, such as decomposition noise reduction and maximum likelihood recovery. On the other hand, the image restoration can also extend the frequency spectrum of the image by analyzing and extending in the frequency domain, thereby realizing the improvement of the resolution, see (prior art: built-in image processing module)
Referring to fig. 8, the night vision method based on millimeter wave radar of the present invention includes the following steps:
s1: function opening and illumination judgment
The system reads the illumination signal through the CAN bus and judges whether the function is started or not through the function switch signal. If the switching signal is received and other conditions are met, and the radar controller and the corresponding necessary current state are normal in standby, the night vision system function of the millimeter wave radar is requested to be started.
S2: millimeter wave transmission and reception
The central controller controls each millimeter wave antenna to sequentially and rapidly scan, one array element transmits and the other array element receives, and other antennas are in a closed state at the moment. And (4) performing single-channel imaging, and analyzing and processing the received radar echo signal by a central controller (the subsequent hardware of the imaging system mainly comprises an antenna, a signal source, a mixer, an amplifier, a sampler, a signal processor and the like).
S3: imaging of images
The central controller controls the integrated software module algorithm (as the software architecture design)
The core steps are as follows: the night vision of the invention presents the algorithm as (built-in imaging processing module)
S4: output of images
The central controller sends the image to the display unit for display.
The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.
Claims (8)
1. The night vision method based on the millimeter wave radar is characterized in that: the method comprises the following steps:
s0: the night vision system based on the millimeter wave radar is built and comprises the millimeter wave radar, an illumination sensor, a central controller and a display unit, wherein the millimeter wave radar, the illumination sensor, the central controller and the display unit are respectively hung on a whole vehicle bus; the millimeter wave radar comprises an antenna, a signal source, a circulator, a mixer, an amplifier, a sampler, an AD converter and a signal processor;
s1: the illumination sensor collects an illumination signal and sends the illumination signal to the central controller through the bus of the whole vehicle; the central controller judges whether the function is started or not through the function switch signal, and requests to start the night vision function if the switch signal is received and the current state of the millimeter wave radar is normal in standby;
s2: the millimeter wave radar sequentially sends millimeter waves through an antenna and receives echoes of each frequency point in a millimeter wave frequency band to obtain basic echo signals, then the echo signals are subjected to Fourier summation and conversion to spatial frequency, and the superposition of plane waves with different azimuth angles and pitch angles and different wave numbers in a reasonable working echo interval is recorded; collecting spatial interference fringes, recording a diffraction pattern of each scattering point on a target, and sequentially and rapidly scanning to perform single-channel imaging;
s3: the central controller analyzes and processes echo signals, performs phase compensation on each plane wave component, restores the phase components into actual three-dimensional distance distribution of a target, and improves resolution ratio reconstruction images to obtain night vision imaging by decomposing and reducing noise, restoring maximum likelihood and analyzing and extending frequency spectrum of an expanded image in a frequency domain;
s4: the central controller sends the image to the display unit for display.
2. The millimeter-wave radar-based night vision method of claim 1, wherein: in the step S2, the scanning trajectory of the millimeter wave radar in the scene is approximately a long and narrow ellipse, and the imaging speed is 1 Hz;
the scanning speed is determined according to the integration time and the imaging time, and the maximum integration time is adopted in the allowed imaging time to improve the sensitivity of the system; the constraint relation between the scanning speed and the integration time is as follows:
3. the millimeter-wave radar-based night vision method of claim 1, wherein: in step S2, in the single channel imaging, one antenna element is transmitting and the other antenna element is receiving, and the other antennas are in the off state.
4. The millimeter-wave radar-based night vision method of claim 1, wherein: in the step S2, the specific steps are as follows:
s21: the signal source transmits millimeter wave signals outwards through the circulator and the antenna;
s22: echo signals of millimeter wave signals after being scattered by a target are received by an antenna;
s23: the signal received by the antenna is divided into two paths after passing through the circulator, and the two paths of signals are respectively mixed with one path of local oscillation signal and the other path of delayed local oscillation signal to obtain two orthogonal zero intermediate frequency signals I and Q;
s24: the zero intermediate frequency signal sequentially passes through an amplifier, a filter and AD sampling to obtain a discrete digital signal;
s25: setting an echo beam which is emitted by the millimeter wave radar and has a specific width and is scattered by a target at a position (X, Y, z) to be received by an antenna at the position (X, Y), wherein omega is an echo angle measured and calculated by the millimeter wave radar by taking a radar central plane as a reference; a (x, y, z) is the complex amplitude distribution of the target radiation, K is the number of circular waves, r is the distance, K and r are both vectors in the three-dimensional space, and K r is the vector dot product of the K and r; performing down-conversion and low-pass filtering in sequence to obtain a signal of each frequency point as follows:
let E (x, y, ω) be the time domain signal after fourier transforming the time dimension FT:
E(X，Y，ω)＝FT[E(X，Y，t)]，
let K x 、K y And K z For the anisotropic component of K, the dot product of K and r is:
K·r＝(x-X)K x +(y-Y)K y +(z-Z)K z ；
unfolding and gathering spherical waves into superposition of plane waves, and substituting the superposition into an original formula to obtain the plane wave:
a three-dimensional fourier transform is used for the above equation:
this equation is a two-dimensional inverse fourier transform, IFT, obtained by ignoring the constant term:
obtaining:
the night vision imaging formula of the millimeter wave radar obtained by inverse transformation of the formula is as follows:
5. the millimeter-wave radar-based night vision method of claim 4, wherein: in the step S3, the specific steps are:
let c be lightFast, then K z The following relationships exist:
carrying out time dimension processing on a night vision imaging formula to obtain distance information of a target; assuming B as the bandwidth, the distance-wise resolution is:
6. night vision system for use in a millimeter wave radar based night vision method according to any one of the claims 1 to 5, characterized in that: the system comprises a millimeter wave radar, an illumination sensor, a central controller and a display unit, wherein the millimeter wave radar, the illumination sensor, the central controller and the display unit are respectively hung on a whole vehicle bus;
the millimeter wave radar is used for collecting electromagnetic wave reflection information of a real scene environment, determining a reflection echo and a scattering echo of a target and forming an original input of a target image;
the millimeter wave radar comprises an antenna, a signal source, a circulator, a mixer, an amplifier, a sampler, an AD converter and a signal processor; the signal source is used for transmitting millimeter wave signals outwards through the circulator and the antenna; the antenna is used for transmitting and receiving signals; the circulator is used for dividing signals into multiple paths; the mixer is used for mixing the multi-channel signals; the amplifier, the sampler and the AD converter are respectively used for amplifying, sampling and carrying out analog-to-digital conversion on the signals; the signal processor is used for imaging the discrete digital signals;
the illumination sensor is used for acquiring an illumination signal;
the central controller is used for storing an algorithm comprising an ADAS function, processing the fused image information and controlling the vehicle to act according to a torque and braking deceleration request under the condition of meeting the condition;
the display unit is used for outputting quasi-image information for a driver to view;
the whole vehicle bus is used for providing signals required by the night vision system comprising a switching signal of the night vision system and a real-time vehicle speed signal to the central controller.
7. The millimeter-wave radar-based night vision system of claim 6, wherein:
the antennas are two-dimensional arrays in the OXY plane, with the OXY plane where the target is located at a distance R from the OXY plane.
8. A computer storage medium, characterized in that: stored therein is a computer program executable by a computer processor, the computer program performing the millimeter wave radar-based night vision method of any one of claims 1 to 5.
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