An unmanned millimeter wave radar failure detection method

Abstract

The application provides an unmanned millimeter wave radar failure detection method, characterized by comprising the following steps: S1: measuring the distance between the millimeter wave radar and a detected object, and displaying the distance through a visual interface; S2: modulating the echo of the millimeter wave radar through the micro-Doppler effect of an angle reflector, thereby interfering with the transmission signal and the receiving signal of the millimeter wave radar; and S3: changing the scattering cross section of the millimeter wave radar by adjusting the position of the angle reflector, and obtaining a failure detection result through the distance comparison of different positions of the angle reflector.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of unmanned driving, and particularly relates to an unmanned driving millimeter wave radar failure detection method. BACKGROUND

[0002] Unmanned driving is a complex system composed of cloud services, sensors, computing units, automatic driving algorithms, chassis power systems, etc. Due to the exposure of a large number of components, it brings serious security challenges. Sensor data interference is a prominent security risk. Millimeter wave refers to electromagnetic waves of 1-10 mm, which has a large bandwidth, high resolution, and small antenna component size, and can adapt to harsh environments. The frequency-modulated continuous wave radar system (FMCW) of the vehicle millimeter wave radar is suitable for short-range detection. Failure detection is needed to improve the safety of the unmanned driving system. The existing unmanned driving millimeter wave radar failure detection method is complex, has high cost, and has poor reliability.

[0003] For example, the publication number CN110316184A provides a millimeter wave radar-based electric vehicle lane-changing steering assist failure system and method. The millimeter wave radar installed on the left and right sides of the rear of the vehicle detects the blind area of the rearview mirror in real time. When it is detected that the obstacle poses a danger to the vehicle, the data processing controller sends a command to the warning device to issue a warning prompt. When it is detected that the driver's operation on the vehicle will pose a danger to the obstacle, the data processing controller sends a command to the alarm device to issue an alarm prompt, and simultaneously sends an alarm command to the vehicle controller. The vehicle controller sends a control command to the electric hydraulic assist steering system to make the steering wheel assist steering failure.

[0004] For example, the publication number CN112946593A discloses a millimeter wave radar testing system and method. The system includes a control device, a radar adjusting device, and a detection device. The control device is electrically connected to the radar adjusting device and the detection device. The radar adjusting device is installed with a millimeter wave radar, and the detection device is installed with an angle reflector. The control device is used to send a first control signal to the radar adjusting device and a second control signal to the detection device. The radar adjusting device is used to adjust the millimeter wave radar to a target field of view angle according to the first control signal, so that the millimeter wave radar emits electromagnetic wave signals at the target field of view angle. The detection device is used to adjust the angle reflector to a target height according to the second control signal. The control device is also used to calculate the performance parameters of the millimeter wave radar according to the echo signals received by the millimeter wave radar.

[0005] Therefore, it is necessary to provide an unmanned driving millimeter wave radar failure detection method to solve the above problems. SUMMARY

[0006] The application aims to provide an unmanned millimeter wave radar failure detection method, which utilizes the radar echo characteristics of corner reflector to interfere with the transmission signal of millimeter wave radar to obtain the failure detection effect.

[0007] The application provides the following technical solutions:

[0008] An unmanned millimeter wave radar failure detection method comprises the following steps:

[0009] S1: measuring the distance between the millimeter wave radar and the detected object and displaying the distance through a visual interface;

[0010] S2: modulating the echo of the millimeter wave radar through the micro-Doppler effect of the corner reflector to interfere with the transmission signal and the receiving signal of the millimeter wave radar;

[0011] S3: changing the scattering cross-section area of the millimeter wave radar by adjusting the position of the corner reflector and obtaining the failure detection result through the distance comparison of the corner reflector at different positions.

[0012] Further, in step S1, the method for measuring the distance between the millimeter wave radar and the detected object comprises:

[0013] S11: the millimeter wave radar transmits a series of continuous frequency modulation millimeter wave signals outward through an antenna and receives the reflected signals of the detected object, wherein the frequency modulation millimeter wave signals are the center frequency of the transmission signals; wherein the frequency of the transmission wave changes with time according to the law of the modulation voltage, the reflected wave has the same shape as the transmission wave, only with a time delay, the frequency difference between the transmission signal and the reflected signal at a certain time is the intermediate frequency signal frequency of the mixing output, and the target distance is proportional to the intermediate frequency frequency output by the front end;

[0014] S12: the corner reflector transmits a frequency modulation signal, and the sweep bandwidth of the frequency modulation signal is ; generally, the modulation signal is a triangular wave signal;

[0015] S13: obtaining the frequency difference between the frequency modulation millimeter wave signal transmitted by the millimeter wave radar and the received reflected signal ;

[0016] S14: obtaining the intermediate frequency signal frequency of the mixing output when the detected object and the millimeter wave radar are relatively stationary ;

[0017] S15: obtaining the Doppler shift of the reflected signal generated when the detected object and the millimeter wave radar are relatively moving ;

[0018] S16: the frequency-modulated millimeter wave signal , the sweep bandwidth of the frequency-modulated signal is , the frequency difference , the intermediate frequency signal frequency , the Doppler shift , the distance between the millimeter wave radar and the detected object is calculated .

[0019] Preferably, the distance between the millimeter wave radar and the detected object is calculated The formula is:

[0020]

[0021] In the formula, is the speed of light, is the carrier wavelength of the millimeter wave signal, is the test time.

[0022] Preferably, in step S2, the modulation of the corner reflector echo to the millimeter wave radar utilizes the micro-Doppler effect, and the specific method includes:

[0023] S21: obtaining the time-domain echo signal of the reflection point P according to the continuous frequency-modulated millimeter wave signal of the millimeter wave radar;

[0024] S22: obtaining the instantaneous slant range between the rotation point of the corner reflector and the detected object according to the time-domain echo signal;

[0025] S23: obtaining the difference frequency signal after the rotation point echo signal is processed by the frequency-modulated signal through the instantaneous slant range between the rotation point p and the detected object.

[0026] Preferably, the continuous frequency-modulated millimeter wave signal emitted by the millimeter wave radar is the emission signal in a pulse duration, and the formula is represented as:

[0027]

[0028] In the formula, , is the center frequency, T p is the time width, is the frequency modulation rate; represents the fast time, T is the pulse repetition period, and the slow time = mT is used to measure the time of pulse emission, m represents the pulse number, is the time variable;

[0029] The time domain echo signal is expressed as:

[0030] ;

[0031] In the formula, A is the scattering coefficient of the point P ; R t m is the one-way distance between the scattering point and the radar when the point is irradiated by the first pulse; m

[0032] The instantaneous slant range is expressed as:

[0033] ;

[0034] In the formula, p represents the rotating point of the corner reflector, r is the rotating radius, f p is the rotating frequency (angular frequency ), is the initial phase, v is the radial velocity of the detected object relative to the radar, R 0 is the distance between the rotating center and the radar platform;

[0035] The difference frequency signal is expressed as:

[0036]

[0037] In the formula, is the scattering coefficient of the rotating point, c is the speed of light, is the carrier wavelength, is the frequency modulation slope, is the reference distance, represents the distance offset of the detected object relative to the reference distance.

[0038] Preferably, in step S3, the method for adjusting the position of the corner reflector to change the radar scattering cross section area comprises:

[0039] S31: placing the corner reflector at different positions of the detected object;

[0040] S32: using the micro-Doppler characteristics of the rotating corner reflector and the different rotating characteristics of multiple rotating corner reflectors to effectively modulate the echo, expanding the interference range coverage in the azimuth direction, thereby improving the interference efficiency of the corner reflector.

[0041] Preferably, the RCS of the triangular corner reflector is:

[0042] ;​​

[0043] wherein, i is the incident angle of the incident light, n is the refractive index of the corner reflector, n 0 is the refractive index of the working environment; is the length of the right angle side of the corner reflector.

[0044] When the azimuth angle is different, the RCS of the triangular reflector will also change, and the change rule formula is:

[0045]

[0046] wherein, i is the incident angle of the incident light, n is the refractive index of the corner reflector, n 0 is the refractive index of the working environment; is the length of the right angle side of the corner reflector.

[0047] Preferably, in step S31, the corner reflector is placed at different positions of the detection object, including placing the corner reflector in front of the detection object and placing the corner reflector on the side of the detection object.

[0048] Preferably, the distance includes the straight-line distance between the millimeter wave radar and the detection object, the up-and-down distance between the millimeter wave radar and the detection object, and the left-and-right distance between the millimeter wave radar and the detection object.

[0049] The present application has the following beneficial effects:

[0050] 1. The failure detection is performed by the millimeter wave radar, which has a large bandwidth, high resolution, small antenna component size, and can adapt to harsh environments. Only the millimeter wave radar needs to be interfered to achieve the effect of failure detection, and the detection method is simple.

[0051] 2. The corner reflector modulates the echo of the millimeter wave radar by using the Doppler effect, so that the corner reflector interferes with the transmission signal of the millimeter wave radar, and adjusting the position and movement of the corner reflector changes the radar scattering cross section. Not only is the cost low, but also the detection effect can be well interfered. BRIEF DESCRIPTION OF DRAWINGS

[0052] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application together with the embodiments thereof, and explain the principles of the present application, and are used to explain the present application but do not limit the present application. In the drawings:

[0053] Figure 1 is a flowchart of the present application. DETAILED DESCRIPTION

[0054] As shown in the figure, an unmanned millimeter wave radar failure detection method provided by the application comprises the following steps:

[0055] S1: measuring the distance between the millimeter wave radar and the detected object and displaying the distance through a visual interface; the distance includes the straight-line distance between the millimeter wave radar and the detected object, the up-and-down distance between the millimeter wave radar and the detected object, and the left-and-right distance between the millimeter wave radar and the detected object;

[0056] S2: modulating the echo of the millimeter wave radar through the micro-Doppler effect of the corner reflector to interfere with the transmission signal and the reception signal of the millimeter wave radar; wherein: the Doppler effect refers to the change in frequency caused by the relative motion between objects; the corner reflector is a special retroreflector with the characteristics of radar echo and is widely used in laser radars. The micro-Doppler effect of the corner reflector is used to modulate the echo of the millimeter wave radar, so that the corner reflector interferes with the transmission signal of the millimeter wave radar. The radar corner reflector can effectively resist radar detection, mainly composed of several mutually perpendicular metal surfaces. After multiple reflections of the radar wave, the radar wave is finally reflected back along the incident direction. The corner reflector not only has low cost, but also can produce obvious interference effect.

[0057] S3: changing the radar cross section (RCS) of the millimeter wave radar by adjusting the position of the corner reflector and obtaining the failure detection result by comparing the distances at different positions of the corner reflector;

[0058] Wherein, the radar cross section (RCS) is a physical quantity representing the scattering ability of the radar target to the incident electromagnetic wave. The measurement of the radar target RCS can be divided into single station and double station modes. The single station RCS test in the absolute sense requires a single antenna to simultaneously transmit and receive signals, which has high requirements for signals. Therefore, two antennas are used to receive and transmit signals respectively. The single station and double station measurement methods are distinguished by the positions of the receiver and the transmitter. If the transmitter and the receiver are in the same position, it is called a single station measurement system. If the transmitter and the receiver are in different positions, it is called a double station measurement system.

[0059] The RCS test requires that the target is in the far field range of the transmitter or the receiver. The far field range refers to the electromagnetic wave excited by the transmitter that can be directly regarded as a plane wave when it reaches the vicinity of the target. It can be realized by external field test and internal field contraction field test. The external field test requires a large field range and strict electromagnetic environment, so that the electromagnetic wave can propagate far enough to be approximated as a plane wave. The contraction field test is mainly used in indoor scenes. Various types of reflector antennas are used to convert the electromagnetic wave excited by the transmitter into an approximate plane wave to meet the requirements.

[0060] In step S1, the method for measuring the distance between the millimeter wave radar and the detected object comprises:

[0061] S11: The millimeter wave radar transmits a series of continuous frequency modulation millimeter wave signals to the outside through an antenna and receives the reflected signals of the detected object, wherein the frequency modulation millimeter wave signals have a center frequency of the transmitted signals;

[0062] S12: The corner reflector transmits the frequency modulation signals, and the sweep bandwidth of the frequency modulation signals is ;

[0063] S13: The frequency difference between the frequency modulation millimeter wave signals transmitted by the millimeter wave radar and the received reflected signals is obtained ; ;

[0064] S14: The intermediate frequency signal frequency of the mixed output when the detected object and the millimeter wave radar are relatively stationary is obtained ;

[0065] S15: The Doppler frequency shift generated by the reflected signals when the detected object and the millimeter wave radar are relatively moving is obtained ;

[0066] S16: According to the frequency modulation millimeter wave signals , the sweep bandwidth of the frequency modulation signals is , the frequency difference is , the intermediate frequency signal frequency is , and the Doppler frequency shift is , the distance between the millimeter wave radar and the detected object is calculated ;

[0067] The calculation formula of the distance between the millimeter wave radar and the detected object is as follows:

[0068]

[0069] In the formula, c is the speed of light, is the carrier wavelength of the millimeter wave signals, and t is the test time.

[0070] In step S2, the echo of the millimeter wave radar by the corner reflector is modulated by using the micro-Doppler effect, and the specific method comprises:

[0071] S21: The time-domain echo signal of the reflection point P is obtained according to the continuous frequency modulation millimeter wave signals transmitted by the millimeter wave radar;

[0072] S22: The instantaneous slant range between the rotation point of the corner reflector and the detected object is obtained according to the time-domain echo signal.​

[0073] S23: the instantaneous slant range between the rotating point p and the test object is obtained, and the beat signal after the rotating point echo signal is processed by the frequency modulation signal is obtained.

[0074] The frequency modulated continuous wave (FMCW) signal transmitted by the millimeter wave radar is a transmitted signal in a pulse duration, and its formula is expressed as:

[0075]

[0076] In the formula, , is the center frequency, T p is the time width, is the frequency modulation rate; indicates the fast time, and m indicates the pulse number, T is the pulse repetition period, and the slow time = mT is used to measure the time of pulse transmission; the above formula is the time domain expression of the FMCW signal, which is a function about the time variable ;

[0077] The time domain echo signal formula of the reflecting point P is expressed as:

[0078] ;

[0079] In the formula, A is the scattering coefficient of the point P , R is the one-way distance between the scattering point and the radar when the point is irradiated by the mth pulse; t m m The instantaneous slant range between the rotating point

[0080] of the corner reflector and the test object is expressed as: p

[0081] ;

[0082] In the formula, p indicates the rotating point of the corner reflector, r is the rotating radius, f p is the rotating frequency (angular frequency ), v is the radial velocity of the test object relative to the radar, that is, the velocity component of the target along the direction of the radar wave velocity approaching or moving away; ​​is the initial phase, R 0 is the distance between the rotation center and the radar platform;

[0083] The difference frequency signal formula of the FMCW signal transmitted by the millimeter wave radar after frequency modulation processing is:

[0084]

[0085] In the formula, is the scattering coefficient of the rotation point, c is the speed of light, is the carrier wavelength, μ is the frequency modulation slope, is the reference distance, that is, the reference distance used for signal demodulation and matching; represents the distance offset of the detected object relative to the reference distance, .

[0086] In step S3, the method for adjusting the position of the corner reflector to change the radar scattering cross section area includes:

[0087] S31: Place the corner reflector at different positions of the detected object;

[0088] S32: Use the micro-Doppler characteristics of the rotating corner reflector and the different rotation characteristics of multiple rotating corner reflectors to effectively modulate the echo, expand the interference range coverage in the azimuth direction, and thus improve the interference efficiency of the corner reflector.

[0089] The RCS of the triangular corner reflector is:

[0090] ;

[0091] In the formula, i is the incident angle of the incident light, n is the refractive index of the corner reflector, n 0 is the refractive index of the working environment; is the length of the right angle side of the corner reflector.

[0092] When the azimuth angle is different, the RCS of the triangular reflector will also change, and the change rule formula is:

[0093]

[0094] In the formula, i is the incident angle of the incident light, n is the refractive index of the corner reflector, n 0 is the refractive index of the working environment; is the length of the right angle side of the corner reflector.

[0095] In step S31, placing the corner reflector at different positions of the detection object includes placing the corner reflector in front of the detection object and placing the corner reflector at the side of the detection object.

[0096] Embodiment one:

[0097] Millimeter wave radar uses platform XCOM:

[0098] 1, connect the module USB line to the computer;

[0099] 2, through the power supply port to the radar on 5V / 2A power supply;

[0100] 3, the computer driver installation will appear 2 serial ports, at this time open the serial port debugging assistant, open COM19 with the serial port debugging assistant, different COM port number of different computers;

[0101] 4, the serial port debugging assistant opens the COM19 port, the baud rate selects 115200, 1 stop bit, 8 data bits, no check bit, after opening, send the radar start-up instruction sensorStart in the form of string;

[0102] 5, send sensorStart, the radar starts to send the coordinates of the detected target, wherein Y represents the distance measured to the target.

[0103] When the actual distance of the object is 11.2 meters, the triangular corner reflector is used for confrontation, the object is placed in the RCS range of the triangular corner reflector, so that the millimeter wave radar transmission waveform is reflected in multiple directions when encountering the triangular corner reflector, and the millimeter wave radar receiving signal is disturbed by the RCS of the corner reflector, so as to achieve the purpose of ranging interference, and finally the experimental effect is obtained. The measured distance is 8.4 meters, and the effect of the confrontation is 2.8 meters (11.2-8.4).

[0104] The above only describes the preferred embodiments of the present application and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An unmanned millimeter wave radar failure detection method, characterized by, The method comprises the following steps: S1: measuring the distance between the millimeter wave radar and the detected object, and displaying the distance through a visual interface; S2: modulating the echo of the millimeter wave radar through the micro-Doppler effect of the corner reflector, thereby interfering with the transmission and reception signals of the millimeter wave radar, specifically comprising: S21: obtaining a time-domain echo signal of the reflection point according to the continuous frequency modulation millimeter wave signal transmitted by the millimeter wave radar P ; S22: obtaining the instantaneous slant range between the rotating point of the corner reflector and the test object according to the time domain echo signal; S23: by rotating the point p The instantaneous slant range between the test object and the rotating point echo signal after the difference frequency signal processing of the frequency modulation signal; The continuous frequency millimeter wave signal transmitted by the millimeter wave radar is a transmission signal within a pulse duration, and its formula is represented as: wherein , is the center frequency, T p is the time width, is the frequency modulation rate; denotes the fast time, T is the pulse repetition period, the slow time = mT for metering the time of the pulse emission, m denotes the pulse number, is the time variable; The formula of the time domain echo signal is represented as: ； In the formula, A For point P The scattering coefficient, R ( t m ) is the scattering point at the th m The one-way distance between the radar and the pulse illumination; The formula of the instantaneous slant range is represented as: ； wherein p represents the rotation point of the corner reflector, r is the rotation radius, the angular frequency , f p is the rotation frequency, is the initial phase, R 0 is the distance of the rotation center from the radar platform, v is the radial velocity of the detected object relative to the radar; The formula of the difference frequency signal is represented as: wherein is the scattering coefficient at the point of rotation, c is the speed of light, is the carrier wavelength, is the frequency modulation slope, is the reference distance, denotes the distance offset of the detection object relative to the reference distance; S3: changing the scattering cross section of the millimeter wave radar by adjusting the position of the corner reflector, and obtaining the failure detection result by comparing the distances at different positions of the corner reflector; wherein the method of adjusting the position of the corner reflector to change the radar scattering cross section comprises: S31: placing the corner reflector at different positions of the detected object; S32: using the micro-Doppler characteristics of the rotating corner reflector and the different rotation characteristics of multiple rotating corner reflectors to effectively modulate the echo, thereby expanding the interference range in the azimuth direction and improving the interference efficiency of the corner reflector.

2. The method of claim 1, wherein, In step S1, the method for measuring the distance between the millimeter wave radar and the detected object comprises: S11: The millimeter wave radar transmits a series of continuous frequency modulation millimeter wave signals outward through an antenna and receives a reflected signal of the detection object, wherein the frequency modulation millimeter wave signal is the center frequency of the transmitted signal; S12: the corner reflector transmits a frequency-modulated signal, a sweep bandwidth of the frequency-modulated signal being ; S13: Obtain the frequency-modulated millimeter wave signal transmitted by the millimeter wave radar The frequency difference from the received reflection signal ; S14: Obtain the intermediate frequency signal frequency of the mixing output when the detection object and the millimeter wave radar are relatively stationary ; S15: Obtain Doppler shift generated by reflected signal when relative motion between detection object and millimeter wave radar ; S16: the frequency-modulated millimeter wave signal , the sweep bandwidth of the frequency-modulated signal is , the frequency difference , the intermediate frequency signal frequency , the Doppler shift The distance between the millimeter wave radar and the detected object is calculated .

3. The method of claim 2, wherein, The millimeter wave radar and the distance between the detected object The calculation formula is: wherein c is the speed of light, λ is the carrier wavelength of the millimeter wave signal, t is the test time.

4. The method of claim 1, wherein, The RCS of the triangular corner reflector is: ； wherein i is the angle of incidence of the incident light ray, n is the refractive index of the corner reflector, n 0 is the refractive index of the working environment; is the length of the straight side of the corner reflector; When the azimuth angle If not, the RCS of the triangular reflector will also change, and the change rule is expressed as: wherein i is the angle of incidence of the incident light ray, n is the refractive index of the corner reflector, n 0 is the refractive index of the working environment; is the length of the straight side of the corner reflector.

5. The method of claim 1, wherein, In step S31, placing the corner reflector at different positions of the detected object comprises placing the corner reflector in front of the detected object and placing the corner reflector on the side of the detected object.

6. The method of claim 1, wherein, The distance includes the straight-line distance between the millimeter wave radar and the detected object, the up-and-down distance between the millimeter wave radar and the detected object, and the left-and-right distance between the millimeter wave radar and the detected object.

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