Obstacle detection method and device

Abstract

The invention relates to an obstacle detection method and device. The method comprises the following steps: acquiring current detection data acquired by each radar sensor in a target external area on a vehicle based on a center frequency distributed at the current moment; the obstacle detection condition of the vehicle is determined according to the current detection data; and according to the obstacle detection condition, the frequency of each radar sensor is adjusted, so that obstacles around the vehicle can be continuously detected. According to the technical scheme, the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors are overlapped or not overlapped, and the signal receiver can correctly receive and analyze the signals of the radar sensors under the condition of overlapping, so that the accuracy of detecting the distance between the vehicle and the surrounding obstacle is improved.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to an obstacle detection method and device. Background Art

[0002] Radar sensors (such as ultrasonic radars) transmit high-frequency radar signals, receive reflected radar signals, and measure distance by calculating the time difference between the round trip signals. Radar sensors play an important role in assisted parking scenarios. They can provide accurate distance measurement, help drivers better understand the distance between the vehicle and surrounding obstacles, and improve parking safety.

[0003] However, radar sensors are prone to co-frequency interference when working. This is mainly caused by multiple radar sensors using the same or similar operating frequencies in the same environment. The signals emitted by multiple radar sensors are superimposed on each other, making it difficult for the receiving end to correctly receive and analyze the signals. As a result, there is a problem of low accuracy in the distance between the vehicle and surrounding obstacles determined based on radar signals. Summary of the invention

[0004] Based on this, it is necessary to provide an obstacle detection method and device to address the above technical problems, which can improve the accuracy of detecting the distance between the vehicle and the surrounding obstacles.

[0005] In a first aspect, the present application provides an obstacle detection method, the method comprising:

[0006] Obtaining current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency assigned at the current moment;

[0007] Determining the obstacle detection status of the vehicle according to each current detection data;

[0008] According to the obstacle detection situation, the frequency of each radar sensor is adjusted to continuously detect obstacles around the vehicle;

[0009] Among them, the types of the radar sensors are the same, and the frequency constraint conditions are satisfied between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trend of the variable frequency center frequency in the corresponding frequency interval is increasing or decreasing.

[0010] In one of the embodiments, the center frequency allocated to each radar sensor at the current moment is selected from candidate center frequencies; wherein the number of candidate center frequencies is the same as the number of radars of the radar sensors deployed in the target external area, and each candidate center frequency includes a fixed frequency center frequency and a variable frequency center frequency.

[0011] In one embodiment, each candidate center frequency is determined by:

[0012] The operating frequency range of the radar sensor is divided to obtain at least two fixed-frequency center frequencies; wherein the frequency intervals corresponding to two adjacent fixed-frequency center frequencies do not overlap;

[0013] When the number of deployed radar sensors is greater than the number of frequencies of the fixed-frequency center frequency, determining a quantity difference between the number of deployed radar sensors and the number of frequencies;

[0014] Add the variable frequency center frequencies of the difference value between adjacent fixed frequency center frequencies; wherein the frequency intervals corresponding to two adjacent variable frequency center frequencies do not overlap.

[0015] In one embodiment, the frequency adjustment of each radar sensor according to the obstacle detection situation includes:

[0016] Determining a next frequency adjustment mode at a next moment according to the obstacle detection situation;

[0017] Determining the center frequency of each radar sensor at a next moment according to the consistency between the current frequency adjustment mode at the current moment and the next frequency adjustment mode;

[0018] Based on the center frequency of each radar sensor at the next moment, the frequency of each radar sensor is adjusted.

[0019] In one embodiment, determining the center frequency of each radar sensor at the next moment according to the consistency between the current frequency adjustment mode at the current moment and the next frequency adjustment mode includes:

[0020] If the current frequency adjustment mode at the current moment is consistent with the next frequency adjustment mode, determining the center frequency of each radar sensor at the next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment;

[0021] If the current frequency adjustment mode at the current moment is inconsistent with the next frequency adjustment mode, the center frequency of each radar sensor at the next moment is determined according to the next frequency adjustment mode.

[0022] In one embodiment, determining the center frequency of each radar sensor at a next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment includes:

[0023] If the current frequency adjustment mode is the obstacle-free mode, the frequency change trend of the frequency conversion center frequency in the center frequency allocated to each radar sensor at the current moment in the corresponding frequency interval is reversely transformed to obtain a new center frequency allocated to each radar sensor at the current moment;

[0024] For each radar sensor, the new center frequency allocated to the radar sensor at the current moment is used as the center frequency of the radar sensor corresponding to the next sensor sequence number at the next moment;

[0025] The sensor numbers of two adjacent radar sensors are incremented, and the next sensor number of the last sensor number is the first sensor number.

[0026] In one embodiment, determining the center frequency of each radar sensor at a next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment includes:

[0027] If the current frequency adjustment mode is the side-front obstacle mode, the center frequency of the first target radar sensor at the next moment is determined according to the center frequency assigned to the first target radar sensor located in the side-front area of ​​the target external area at the current moment, the detection parameters corresponding to each candidate center frequency, and the frequency conversion rule; wherein the frequency conversion rule is that the detection distance corresponding to the center frequency of the first target radar sensor at the next moment is less than the detection distance corresponding to the center frequency at the current moment;

[0028] determining, according to the detection parameter corresponding to the center frequency of the first target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency, the center frequency of a radar sensor adjacent to the first target radar sensor at the next moment;

[0029] With the goal of satisfying the frequency constraint condition between two adjacent radar sensors, the center frequencies at the next moment are allocated to the remaining radar sensors.

[0030] In one embodiment, determining the center frequency of a radar sensor adjacent to the first target radar sensor at the next moment according to the detection parameter corresponding to the center frequency of the first target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency includes:

[0031] Determine the detection blind area of ​​the first target radar sensor according to the detection parameters corresponding to the center frequency of the first target radar sensor at the next moment; wherein the detection parameters include the detection distance and the detection range;

[0032] The center frequency of a radar sensor adjacent to the first target radar sensor at a next moment is determined according to the detection blind spot and the detection parameters corresponding to each candidate center frequency; wherein the detection parameters corresponding to the center frequency of the radar sensor adjacent to the first target radar sensor at the next moment can cover the detection blind spot.

[0033] In one embodiment, determining the center frequency of each radar sensor at a next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment includes:

[0034] If the current frequency adjustment mode is the front obstacle mode, and the center frequency assigned to each second target radar sensor located in the front area of ​​the target external area at the current moment is the frequency conversion center frequency, then the frequency change trend of the frequency conversion center frequency of each second target radar sensor in the corresponding frequency interval is reversely transformed, and the center frequency of each second target radar sensor after reverse transformation is alternately transformed to obtain the center frequency of each second target radar sensor at the next moment;

[0035] allocating a maximum center frequency or a minimum center frequency to a radar sensor adjacent to the second target radar sensor at the next moment according to the detection parameter corresponding to the center frequency of the second target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency;

[0036] With the goal of satisfying the frequency constraint condition between two adjacent radar sensors, the center frequencies at the next moment are allocated to the remaining radar sensors.

[0037] In one embodiment, determining the next frequency adjustment mode at the next moment according to the obstacle detection situation includes:

[0038] If the obstacle detection condition is that no obstacle is detected, determining that the next frequency adjustment mode at the next moment is a no-obstacle mode;

[0039] If the obstacle detection condition is that the obstacle is detected in front of the side of the target external area, determining the next frequency adjustment mode at the next moment to be the side-front obstacle mode;

[0040] If the obstacle detection situation is that an obstacle is detected right in front of the target external area, then the next frequency adjustment mode at the next moment is determined to be the front obstacle mode.

[0041] In a second aspect, the present application further provides an obstacle detection device, the device comprising:

[0042] An acquisition module is used to acquire current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency assigned at the current moment;

[0043] A determination module, used to determine the obstacle detection status of the vehicle according to each current detection data;

[0044] An adjustment module, used to adjust the frequency of each radar sensor according to the obstacle detection situation, so as to continuously detect obstacles around the vehicle;

[0045] Among them, the types of the radar sensors are the same, and the frequency constraint conditions are satisfied between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trend of the variable frequency center frequency in the corresponding frequency interval is increasing or decreasing.

[0046] In a third aspect, the present application further provides a computer device, the computer device comprising a memory and a processor, the memory storing a computer program, and the processor implementing the following steps when executing the computer program:

[0047] Obtaining current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency assigned at the current moment;

[0048] Determining the obstacle detection status of the vehicle according to each current detection data;

[0049] According to the obstacle detection situation, the frequency of each radar sensor is adjusted to continuously detect obstacles around the vehicle;

[0050] Among them, the types of the radar sensors are the same, and the frequency constraint conditions are satisfied between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trend of the variable frequency center frequency in the corresponding frequency interval is increasing or decreasing.

[0051] In a fourth aspect, the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following steps are implemented:

[0052] Obtaining current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency assigned at the current moment;

[0053] Determining the obstacle detection status of the vehicle according to each current detection data;

[0054] According to the obstacle detection situation, the frequency of each radar sensor is adjusted to continuously detect obstacles around the vehicle;

[0055] Among them, the types of the radar sensors are the same, and the frequency constraint conditions are satisfied between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trend of the variable frequency center frequency in the corresponding frequency interval is increasing or decreasing.

[0056] In a fifth aspect, the present application further provides a computer program product, the computer program product comprising a computer program, which implements the following steps when executed by a processor:

[0057] Obtaining current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency assigned at the current moment;

[0058] Determining the obstacle detection status of the vehicle according to each current detection data;

[0059] According to the obstacle detection situation, the frequency of each radar sensor is adjusted to continuously detect obstacles around the vehicle;

[0060] Among them, the types of the radar sensors are the same, and the frequency constraint conditions are satisfied between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trend of the variable frequency center frequency in the corresponding frequency interval is increasing or decreasing.

[0061] The above obstacle detection method and device obtain the current detection data collected by each radar sensor in the target external area on the vehicle based on the center frequency assigned at the current moment; and determine the obstacle detection status of the vehicle according to each current detection data; and then adjust the frequency of each radar sensor according to the obstacle detection status to continuously detect obstacles around the vehicle. Wherein, when the types of each radar sensor are the same, the frequency intervals corresponding to the center frequencies of two adjacent radar sensors overlap or do not overlap, and when there is overlap, there is a variable frequency center frequency and a fixed frequency center frequency in the center frequencies of the two adjacent radar sensors, and the variable frequency center frequency increases or decreases in the corresponding frequency interval. In this way, if the frequency intervals corresponding to the center frequencies of two adjacent radar sensors do not overlap, the problem of co-frequency resonance will not arise; even if the frequency intervals corresponding to the center frequencies of two adjacent radar sensors overlap, one of the center frequencies of the two adjacent radar sensors is a variable frequency center frequency, and the other is a fixed frequency center frequency, and the variable frequency center frequency increases or decreases within the corresponding frequency interval, so that the waveforms of the variable frequency center frequency and the fixed frequency center frequency are not the same. Even if there is an intersection, the signal receiver can correctly receive and analyze the radar sensor signal according to the waveforms of the variable frequency center frequency and the fixed frequency center frequency, thereby improving the accuracy of detecting the distance between the vehicle and the surrounding obstacles. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 is an application environment diagram of an obstacle detection method in one embodiment;

[0063] Figure 2 is a flow chart of an obstacle detection method in one embodiment;

[0064] Figure 3A is a schematic diagram of a process for determining each candidate center frequency in an embodiment;

[0065] Figure 3B A schematic diagram of the relationship between the fixed frequency center frequency, the upper limit frequency, and the lower limit frequency in one embodiment;

[0066] Figure 4is a schematic diagram of a process of adjusting the frequency of each radar sensor in one embodiment;

[0067] Figure 5 A schematic diagram of a flow chart of determining the center frequency of each radar sensor at the next moment in another embodiment;

[0068] Figure 6 is a schematic diagram of the distribution of radar sensors in the same external area in one embodiment;

[0069] Figure 7 It is a schematic diagram of a flow chart of determining the center frequency of each radar sensor at the next moment in another embodiment;

[0070] Figure 8 A schematic diagram of a detection range in an embodiment;

[0071] Fig. 9 A schematic diagram of a flow chart of determining a center frequency of a radar sensor adjacent to a first target radar sensor at a next moment in an embodiment;

[0072] Fig.10 A schematic diagram of determining the center frequency of each radar sensor at the next moment in yet another embodiment;

[0073] Fig.11 is a flow chart of an obstacle detection method in another embodiment;

[0074] Fig.12 is a structural block diagram of an obstacle detection device in one embodiment;

[0075] Fig.13 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0077] The obstacle detection method provided in the embodiment of the present application can be applied to Figure 1 The application environment shown is specifically applied to an application scenario of detecting the distance between a vehicle and an obstacle.

[0078] Exemplarily, a preset number of radar sensors of the same type may be deployed on the vehicle, for example, 12 radar sensors may be deployed, and the radar sensors may be ultrasonic radar sensors, laser radar sensors, or millimeter wave radar sensors, etc. Among them, the 12 radar sensors may be deployed on the front bumper, 4 of which are respectively deployed, one on each of the left and right sides of the front bumper, and on the rear bumper, 4 of which are respectively deployed, one on each of the left and right sides of the rear bumper.

[0079] Among them, 12 radar sensors are connected to the parking distance control system (PDC) through a single line, and the data transmission and its port are the input / output interface (I / O) port (12-way lead) on the PDC. Then the PDC is connected to the domain controller through a twisted pair cable, and the data transmission and its port are the controller area network bus or the controller area network (Controller Area Network / CAN with Flexible Data-Rate, CAN / CAN FD) protocol to transmit data to the inside of the domain controller. The microcontroller unit (MCU) inside the domain controller analyzes the radar sensor echo signal data, and finally gives it to the system-on-chip (SOC) end for algorithm fusion to determine the distance between the vehicle and the obstacle, and then adjust the center frequency of each radar sensor. The above method can be performed by Figure 1 The SOC in the system is used for execution.

[0080] In one embodiment, Figure 2 As shown, an obstacle detection method is provided, which is applied to Figure 1 The SOC in the example is used to illustrate, including the following steps:

[0081] S201, obtaining current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency allocated at the current moment.

[0082] For example, the target external area on the vehicle may be the front bumper area or the rear bumper area of ​​the vehicle. The current detection data collected by each radar sensor based on the center frequency assigned at the current moment may be obtained through the CAN bus protocol; wherein the current detection data may include data such as the transmission time and transmission rate of the radar signal, which is used to determine the distance between the vehicle and the obstacle, and determine the position of the obstacle in the vehicle.

[0083] Among them, the types of each radar sensor are the same, and the frequency constraint conditions are met between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trends of the variable frequency center frequencies in the corresponding frequency interval are increasing or decreasing; the fixed frequency center frequency transmits signals at a fixed frequency. This setting is to avoid radar sensors of the same type using the same or similar center frequencies (working frequencies) in the same environment or location, thereby avoiding the signals emitted by radar sensors using the same or similar center frequencies from being superimposed on each other, resulting in the phenomenon that it is difficult for the receiving end to correctly receive and parse the signals, thereby causing signal distortion, data loss or communication interruption.

[0084] S202: Determine the obstacle detection status of the vehicle according to each current detection data.

[0085] Furthermore, the current detection data may include the distance and angle between the obstacle and the vehicle, and then the triangulation positioning method may be used in combination with the distance and angle between the obstacle and the vehicle to determine the coordinates of the obstacle in the vehicle coordinate system, and then the area of ​​the vehicle where the obstacle is located may be determined, that is, the obstacle detection status of the vehicle may be determined.

[0086] S203, adjusting the frequency of each radar sensor according to the obstacle detection situation, so as to continuously detect obstacles around the vehicle.

[0087] Furthermore, the frequency of each radar sensor can be adjusted according to the obstacle detection situation, that is, according to the area of ​​the vehicle where the obstacle is located, so as to adjust the detection distance and detection range of each radar sensor to continuously detect the movement trend of the obstacle, that is, to achieve continuous detection of obstacles around the vehicle.

[0088] The above obstacle detection method obtains the current detection data collected by each radar sensor in the target external area on the vehicle based on the center frequency assigned at the current moment; and determines the obstacle detection status of the vehicle according to each current detection data; and then adjusts the frequency of each radar sensor according to the obstacle detection status to continuously detect obstacles around the vehicle. Wherein, when the types of each radar sensor are the same, the frequency intervals corresponding to the center frequencies of two adjacent radar sensors overlap or do not overlap, and when there is overlap, there is a variable frequency center frequency and a fixed frequency center frequency in the center frequencies of the two adjacent radar sensors, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different; the variable frequency center frequency increases or decreases in the corresponding frequency interval. In this way, if the frequency intervals corresponding to the center frequencies of two adjacent radar sensors do not overlap, the problem of co-frequency resonance will not arise; even if the frequency intervals corresponding to the center frequencies of two adjacent radar sensors overlap, one of the center frequencies of the two adjacent radar sensors is a variable frequency center frequency and the other is a fixed frequency center frequency, and the variable frequency center frequency increases or decreases within the corresponding frequency interval, so that the waveforms of the variable frequency center frequency and the fixed frequency center frequency are not the same, even if there is an intersection, the signal receiver can correctly receive and analyze the radar sensor signal according to the waveforms of the variable frequency center frequency and the fixed frequency center frequency; or in the case of two variable frequency center frequencies with the same frequency interval, the frequency change trends of the two variable frequency center frequencies within the corresponding frequency interval are opposite and the frequency change rates are different, and no intersection will appear, and the signal receiver can correctly receive and analyze the radar sensor signal, thereby improving the accuracy of detecting the distance between the vehicle and the surrounding obstacles.

[0089] In some optional implementations, the center frequency allocated to each radar sensor at the current moment in the above embodiment is selected from each candidate center frequency; wherein the number of each candidate center frequency is the same as the number of radars of the radar sensors deployed in the target external area, and each candidate center frequency includes a fixed frequency center frequency and a variable frequency center frequency.

[0090] In an embodiment of the present application, each candidate center frequency is determined in advance, so that the determined candidate center frequencies include a fixed-frequency center frequency and a variable-frequency center frequency, and the frequency intervals corresponding to the fixed-frequency center frequencies do not overlap, and the frequency intervals between the variable-frequency center frequencies do not overlap, and the variable-frequency center frequencies increase or decrease in the corresponding frequency intervals. In this way, even if the frequency interval corresponding to the variable-frequency center frequency overlaps with the frequency interval corresponding to the fixed-frequency center frequency, since the signal waveforms of the fixed-frequency center frequency and the variable-frequency center frequency are different, the receiver can also distinguish between the signal of the fixed-frequency center frequency and the signal of the variable-frequency center frequency, thereby avoiding the problem of co-frequency interference, thereby improving the accuracy of detecting the distance between the obstacle and the vehicle.

[0091] Furthermore, the embodiment of the present application provides an achievable method for determining each candidate center frequency. Figure 3A , Figure 3A A schematic diagram of a process for determining each candidate center frequency is provided, which specifically includes the following steps:

[0092] S301, dividing the operating frequency range of the radar sensor to obtain at least two fixed frequency center frequencies.

[0093] It should be noted that, taking an ultrasonic radar sensor as an example, the operating frequency range of the ultrasonic radar sensor is 20 khz-150 khz, and the operating frequency range of the radar sensor is divided, and the frequency intervals corresponding to two adjacent fixed-frequency center frequencies do not overlap as the basis for division, and at least two fixed-frequency center frequencies are obtained. For example, the obtained fixed-frequency center frequencies are 28 khz, 58 khz and 126 khz.

[0094] For example, a fixed frequency center frequency can be randomly selected within the working frequency range of the ultrasonic radar sensor of 20 khz-150 khz, for example, the fixed frequency center frequency is selected as 28 khz. Then, the upper limit frequency and the lower limit frequency corresponding to the fixed frequency center frequency can be calculated according to the fixed frequency center frequency, and then the frequency interval corresponding to the fixed frequency center frequency can be determined according to the upper limit frequency and the lower limit frequency.

[0095] See also Figure 3B , Figure 3B A schematic diagram of the relationship between the fixed frequency center frequency, the upper limit frequency and the lower limit frequency is provided. The upper limit frequency and the lower limit frequency corresponding to the fixed frequency center frequency can be determined in the following way:

[0096]

[0097] Among them, f m is the fixed frequency center frequency, f a is the upper limit frequency of the fixed frequency center frequency, f b When determining the next fixed frequency center frequency, it is necessary to ensure that the frequency interval corresponding to the lower limit frequency and the upper limit frequency of the next fixed frequency center frequency does not overlap with the frequency interval corresponding to the lower limit frequency and the upper limit frequency of the previous fixed frequency center frequency.

[0098] Referring to Table 1, Table 1 provides a schematic diagram of frequency intervals of determined fixed-frequency center frequencies, so that the frequency intervals of the determined fixed-frequency center frequencies do not overlap.

[0099] Table 1:

[0100] <![CDATA[Center frequency f m > <![CDATA[Upper frequency limit f a > <![CDATA[Lower frequency limit f b > 28 37 19 58 75 41 126 163 89

[0101] S302: When the number of deployed radar sensors is greater than the number of frequencies of the fixed-frequency center frequency, determine a quantity difference between the number of deployed sensors and the number of frequencies.

[0102] For example, if the number of radar sensors deployed on the front bumper of the vehicle is less than or equal to 3, the fixed frequency center frequency can be selected from 28khz, 58khz and 126khz. In the case where the number of deployed sensors is greater than the number of frequencies of the fixed frequency center frequency, for example, when the number of deployed sensors is 6, the difference between the number of deployed sensors and the number of frequencies is first determined, for example, the determined difference is 3.

[0103] S303, adding a number of variable frequency center frequencies of the difference value between adjacent fixed frequency center frequencies.

[0104] Further, a number of variable frequency center frequencies of a difference value may be added between adjacent fixed frequency center frequencies, for example, three variable frequency center frequencies may be added, wherein the frequency intervals corresponding to two adjacent variable frequency center frequencies do not overlap. For example, the three determined variable frequency center frequencies are 40±5 khz, 68±5 khz, and 86±5 khz.

[0105] Table 2:

[0106]

[0107] For example, see Table 2, which provides a frequency range diagram of a center frequency. The frequency ranges of the fixed-frequency center frequencies do not overlap, and the frequency ranges of the variable-frequency center frequencies do not overlap, and the center frequencies are replaced by letters in sequence, the serial number 0 after the letter represents the fixed-frequency center frequency, the serial numbers 1 and 2 after the letter represent the variable-frequency center frequency, 1 represents that the variable-frequency center frequency increases in the corresponding frequency range, and 2 represents that the variable-frequency center frequency decreases in the corresponding frequency range.

[0108] It should be noted that the embodiments of the present application can use the physical properties of the ceramic pressed piece in the radar transducer to indirectly control the piezoelectric frequency generated by the transducer by controlling the changes in voltage and current, and then design radar sensors with different center frequencies and bandwidths. The radar sensor can be designed based on the center frequency and bandwidth to avoid the same frequency interference phenomenon by making the upper and lower limit frequencies have no intersection relationship.

[0109] In the embodiment of the present application, by determining each fixed-frequency center frequency with non-overlapping frequency intervals and each variable-frequency center frequency with non-overlapping frequency intervals, it is convenient to avoid the problem of co-frequency interference when setting the center frequency of each radar sensor.

[0110] In some optional implementations, the embodiments of the present application can automatically adjust the center frequency of each radar sensor according to the detection situation of the obstacle to achieve continuous detection of the obstacle.

[0111] See also Figure 4 , Figure 4 A schematic diagram of a process for adjusting the frequency of each radar sensor is provided, which specifically includes the following steps:

[0112] S401, determining the next frequency adjustment mode at the next moment according to the obstacle detection situation.

[0113] For example, the target external area of ​​the vehicle can be divided into the side front and the front in advance, and a correspondence between the obstacle detection situation and the frequency adjustment mode can be established. Then, according to the obstacle detection situation, the next frequency adjustment mode at the next moment corresponding to the obstacle detection situation can be determined in the pre-established correspondence.

[0114] Exemplarily, the relationship between the pre-established obstacle detection situation and the frequency adjustment mode may be as follows:

[0115] If the obstacle detection condition is that no obstacle is detected, the corresponding frequency adjustment mode is the obstacle-free mode. Therefore, based on the obstacle detection condition, the next frequency adjustment mode determined at the next moment is the obstacle-free mode.

[0116] If the obstacle detection situation is that the obstacle is detected in front of the side of the target external area, the corresponding frequency adjustment mode is the side front obstacle mode. Therefore, based on the obstacle detection situation, the next frequency adjustment mode at the next moment is determined to be the side front obstacle mode.

[0117] If the obstacle detection situation is that the obstacle is detected directly in front of the target external area, the corresponding frequency adjustment mode is the directly in front obstacle mode. Therefore, based on the obstacle detection situation, the next frequency adjustment mode determined at the next moment is the directly in front obstacle mode.

[0118] In an embodiment of the present application, by pre-establishing a correspondence between obstacle detection conditions and frequency adjustment modes, it is possible to switch to the frequency adjustment mode at the next moment based on the obstacle detection conditions at the current moment, and it is possible to automatically adjust the center frequency of each radar sensor according to the obstacle detection conditions, thereby achieving continuous detection of obstacles.

[0119] S402, determining the center frequency of each radar sensor at the next moment according to the consistency between the current frequency adjustment mode at the current moment and the next frequency adjustment mode.

[0120] Furthermore, the center frequency of each radar sensor at the next moment can be determined based on the consistency between the current frequency adjustment mode and the next frequency adjustment mode at the current moment. For example, if the current frequency adjustment mode and the next frequency adjustment mode are consistent, such as both are obstacle-free modes, the center frequency of each radar sensor at the next moment can be determined based on the obstacle-free mode and the center frequency of each radar sensor at the current moment. If the current frequency adjustment mode and the next frequency adjustment mode are inconsistent, such as the current frequency adjustment mode is obstacle-free mode and the next frequency adjustment mode is side-front obstacle mode, the center frequency of each radar sensor at the next moment is the center frequency of each radar sensor corresponding to the initial moment in the side-front obstacle mode.

[0121] S403, adjusting the frequency of each radar sensor based on the center frequency of each radar sensor at the next moment.

[0122] Furthermore, the frequency of each radar sensor can be adjusted based on the center frequency of each radar sensor at the next moment, and each radar sensor can be used to continuously detect obstacles.

[0123] In the embodiment of the present application, by comparing whether the current frequency adjustment mode is consistent with the next frequency adjustment mode, the center frequency of each radar sensor at the next moment is determined, thereby realizing automatic switching of the center frequency of each radar sensor, thereby realizing continuous detection of obstacles.

[0124] Further, in the above embodiment, S402 determines the center frequency of each radar sensor at the next moment according to the consistency between the current frequency adjustment mode at the current moment and the next frequency adjustment mode, which can be specifically implemented in the following manner:

[0125] If the current frequency adjustment mode at the current moment is consistent with the next frequency adjustment mode, the center frequency of each radar sensor at the next moment is determined according to the current frequency adjustment mode and the center frequency assigned to each radar sensor at the current moment. It should be noted that the center frequency corresponding to each radar sensor at each moment in each frequency adjustment cycle under each frequency adjustment mode can be pre-established. When the frequency adjustment mode remains unchanged, the center frequency of each radar sensor at the next moment can be determined according to the center frequency corresponding to each radar sensor at each moment in each frequency adjustment cycle under the frequency adjustment mode and the center frequency assigned to each radar sensor at the current moment.

[0126] If the current frequency adjustment mode at the current moment is inconsistent with the next frequency adjustment mode, the center frequency of each radar sensor at the next moment is determined according to the next frequency adjustment mode.

[0127] For example, if the current frequency adjustment mode at the current moment is inconsistent with the next frequency adjustment mode, the center frequency of each radar sensor at the next moment can be determined according to the next frequency adjustment mode. Thus, the center frequency corresponding to each radar sensor at each moment in each frequency adjustment cycle under each frequency adjustment mode is pre-established. If the current frequency adjustment mode at the current moment is inconsistent with the next frequency adjustment mode, the center frequency corresponding to each radar sensor at the initial moment in the frequency adjustment cycle under the next frequency adjustment mode can be used as the center frequency of each radar sensor at the next moment.

[0128] In an embodiment of the present application, a feasible method is provided for determining the center frequency of each radar sensor at the next moment based on the consistency between the current frequency adjustment mode at the current moment and the next frequency adjustment mode, thereby realizing automatic adjustment of the center frequency of each radar sensor according to the obstacle detection situation to achieve the purpose of continuous detection of obstacles.

[0129] In some optional implementations, the embodiments of the present application provide an implementable method for determining the center frequency of each radar sensor at the next moment when the current frequency adjustment mode and the next frequency adjustment mode are consistent and in an obstacle-free mode.

[0130] For example, see Figure 5 , Figure 5 Another flow chart for determining the center frequency of each radar sensor at the next moment is provided, which specifically includes the following steps:

[0131] S501, if the current frequency adjustment mode is the obstacle-free mode, the frequency change trend of the frequency conversion center frequency in the center frequency allocated to each radar sensor at the current moment in the corresponding frequency interval is reversely transformed to obtain a new center frequency allocated to each radar sensor at the current moment.

[0132] It should be noted that the center frequency allocated to each radar sensor at the current moment may include a fixed frequency center frequency or a variable frequency center frequency. Since there are two frequency change trends of the variable frequency center frequency in the corresponding frequency interval, namely increasing or decreasing, it can also be understood as up-sweep and down-sweep. If the same variable frequency center frequency with the same change trend is emitted by the same or adjacent radar sensors at adjacent moments, it is easy to cause signal overlap, making it difficult for the receiver to correctly receive and analyze the echo signal. In order to avoid this problem, it is necessary to perform an opposite transformation on the frequency change trend of the variable frequency center frequency in the corresponding frequency interval allocated to each radar sensor at the current moment, that is, to transform the increasing into the decreasing, or to transform the decreasing into the increasing, so as to obtain the new center frequency allocated to each radar sensor at the current moment.

[0133] S502 : For each radar sensor, use the new center frequency allocated to the radar sensor at the current moment as the center frequency of the radar sensor corresponding to the next sensor sequence number at the next moment.

[0134] Furthermore, a sensor serial number may be assigned to each radar sensor located in the same external area. For example, if six radar sensors are deployed in the front bumper area of ​​the vehicle, the six radar sensors are numbered and the areas where the radar sensors are located are divided.

[0135] For example, see Figure 6 , Figure 6 A schematic diagram of the distribution of radar sensors in the external area of ​​the same target is provided. The external area of ​​the target is divided into area 1, area 2 and area 3, which correspond to the left front, the front and the right front, respectively. The left front and the right front are regarded as the side front. Sensors with serial numbers 1 and 2 are located in the left front of the side front, sensors with serial numbers 3 and 4 are located in the front, and sensors with serial numbers 5 and 6 are located in the right front of the side front.

[0136] Optionally, for each radar sensor, the new center frequency allocated to the radar sensor at the current moment is used as the center frequency of the radar sensor corresponding to the next sensor number at the next moment. The sensor numbers of two adjacent radar sensors are incremented, and the next sensor number of the last sensor number is the first sensor number.

[0137] For example, in Figure 6 On this basis, an embodiment of the present application provides a pre-established center frequency corresponding to each radar sensor at each moment in a frequency adjustment cycle in the obstacle-free mode, and takes an example in which a frequency adjustment cycle in the obstacle-free mode includes 6 moments for illustration.

[0138] The six radar sensors are represented by sensor1, sensor2, sensor3, sensor4, sensor5 and sensor6. The center frequency corresponding to each radar sensor at each moment in a frequency adjustment cycle is as follows:

[0139] T1: (sensor1=A0)(sensor2=B1)(sensor3=C0)(sensor4=D2)(sensor5=E1)(sensor6=F0);

[0140] T2: (sensor1=F0)(sensor2=A0)(sensor3=B2)(sensor4=C0)(sensor5=D1)(sensor6=E2);

[0141] T3: (sensor1=E1)(sensor2=F0)(sensor3=A0)(sensor4=B1)(sensor5=C0)(sensor6=D2);

[0142] T4: (sensor1=D1)(sensor2=E2)(sensor3=F0)(sensor4=A0)(sensor5=B1)(sensor6=C0);

[0143] T5: (sensor1=C0)(sensor2=D2)(sensor3=E1)(sensor4=F0)(sensor5=A0)(sensor6=B2);

[0144] T6: (sensor1=B1) (sensor2=C0) (sensor3=D1) (sensor4=E2) (sensor5=F0) (sensor6=A0).

[0145] It should be noted that each moment within a frequency adjustment cycle can be used as the current moment, and the center frequency corresponding to each radar sensor at the next moment can be determined based on the center frequency corresponding to each radar sensor at each moment within a frequency adjustment cycle in the obstacle-free mode and the current moment.

[0146] In an embodiment of the present application, a feasible method is provided for automatically switching the center frequency of each radar sensor at the next moment when the current frequency adjustment mode and the next frequency adjustment mode are consistent and in an obstacle-free mode, thereby achieving continuous detection of obstacles.

[0147] In some optional implementations, an embodiment of the present application provides an implementable method for determining the center frequency of each radar sensor at the next moment in a side front obstacle mode when the current frequency adjustment mode and the next frequency adjustment mode are consistent.

[0148] For example, see Figure 7 , Figure 7 Another flow chart for determining the center frequency of each radar sensor at the next moment is provided, which specifically includes the following steps:

[0149] S701, if the current frequency adjustment mode is the side front obstacle mode, the center frequency of the first target radar sensor at the next moment is determined according to the center frequency assigned to the first target radar sensor located in the side front area in the target external area at the current moment, the detection parameters corresponding to each candidate center frequency, and the frequency conversion rule.

[0150] For example, the embodiments of the present application are also based on Figure 6 Taking the radar sensors shown as an example, the radar sensor with serial number 2 is used as the first target radar sensor. If the current frequency adjustment mode is the side-front obstacle mode, the center frequency of the first target radar sensor at the next moment is determined according to the center frequency assigned to the first target radar sensor located in the side-front area of ​​the target external area at the current moment, the detection parameters corresponding to each candidate center frequency, and the frequency conversion rule. Among them, the frequency conversion rule is that the detection distance corresponding to the center frequency of the first target radar sensor at the next moment is less than the detection distance corresponding to the center frequency at the current moment. It can be understood that this setting is to make the detection distance of the first target radar sensor change from far to near in the same frequency adjustment cycle, so as to detect whether the obstacle has a tendency to approach the vehicle.

[0151] S702: Determine a center frequency of a radar sensor adjacent to the first target radar sensor at the next moment according to a detection parameter corresponding to the center frequency of the first target radar sensor at the next moment and detection parameters corresponding to each candidate center frequency.

[0152] It should be noted that the larger the center frequency, the larger the corresponding detection distance and the smaller the detection range (Field of View, FOV). Figure 8 , Figure 8 A detection range diagram is provided, wherein the FOVs of the radar sensors need to have overlapping parts to achieve full coverage of the target's external area, so as to monitor the movement trend and direction of obstacles in the target's external area.

[0153] Since the detection distance of the first target radar sensor changes from far to near in the same frequency adjustment period, the detection range is from small to large. When the detection distance of the first target radar sensor is large, the radar sensor adjacent to the first target radar sensor needs to make up for the detection range of the first target radar sensor; and when the detection range of the first target radar sensor is large, the radar sensor adjacent to the first target radar sensor needs to make up for the detection distance of the first target radar sensor, so that the radar sensor can detect the movement trend of obstacles in the entire target external area.

[0154] Based on this, the detection parameters corresponding to the center frequency of the first target radar sensor at the next moment may include a detection distance and a detection range. The center frequency of the radar sensor adjacent to the first target radar sensor at the next moment may be determined according to the detection parameters corresponding to the center frequency of the first target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency, so that the radar sensor adjacent to the first target radar sensor can make up for the detection distance or detection range of the first target sensor at the next moment; for example, the center frequencies of the radar sensors numbered 1 and numbered 3 at the next moment can be set to make up for the detection distance or detection range of the first target sensor.

[0155] S703 , with the goal of satisfying the frequency constraint condition between two adjacent radar sensors, allocate center frequencies at the next moment to the remaining radar sensors.

[0156] Exemplarily, when allocating center frequencies for the remaining radar sensors at the next moment, the goal can be to satisfy frequency constraints between two adjacent radar sensors, so as to avoid co-frequency interference with the center frequencies of the already allocated radar sensors when allocating center frequencies for the remaining radar sensors at the next moment; on this basis, the remaining radar sensors located at the outermost end of the target external area can be allocated center frequencies with longer detection distances to detect whether there are new obstacles approaching the outermost end of the target external area.

[0157] In an embodiment of the present application, a feasible method is provided for automatically switching the center frequency of each radar sensor at the next moment when the current frequency adjustment mode and the next frequency adjustment mode are consistent and in the side front obstacle mode, thereby realizing continuous detection of obstacles.

[0158] Furthermore, the present application embodiment provides a specific implementation method of S702 in the above embodiment, see Fig. 9 , Fig. 9 A schematic flow chart of determining the center frequency of a radar sensor adjacent to a first target radar sensor at a next moment is provided, which specifically includes the following steps:

[0159] S901, determining a detection blind area of ​​the first target radar sensor according to a detection parameter corresponding to a center frequency of the first target radar sensor at a next moment.

[0160] Exemplarily, the detection parameters may include a detection distance and a detection range. The detection blind area of ​​the first target radar sensor, that is, the range that cannot be detected by the first target radar sensor, may be determined according to the detection distance and detection range corresponding to the center frequency of the first target radar sensor at the next moment and the side front area range in the target external area.

[0161] S902: Determine a center frequency of a radar sensor adjacent to the first target radar sensor at a next moment according to the detection blind area and the detection parameters corresponding to each candidate center frequency.

[0162] Furthermore, the center frequency of the radar sensor adjacent to the first target radar sensor at the next moment can be determined based on the detection blind spot and the detection parameters corresponding to each candidate center frequency, so that the detection parameters corresponding to the center frequency of the radar sensor adjacent to the first target radar sensor at the next moment can cover the detection blind spot.

[0163] In an embodiment of the present application, by setting the center frequency of a radar sensor adjacent to the first target radar sensor located in the side front area at the next moment, the detection range and distance of the first target radar sensor can be compensated to avoid the detection range of the first target radar sensor failing to cover the entire side front area, thereby enabling accurate detection of the movement trend and direction of the obstacle.

[0164] For example, in Figure 6 On this basis, an embodiment of the present application provides a pre-established center frequency corresponding to each radar sensor at each moment in a frequency adjustment cycle in a side front obstacle mode, and takes an example in which a frequency adjustment cycle in an obstacle-free mode includes 3 moments for explanation.

[0165] When the front side is the left front, the center frequencies corresponding to the radar sensors at each time in a frequency adjustment cycle are as follows:

[0166] T1: (sensor1=E2)(sensor2=F0)(sensor3=D2)(sensor4=E1)(sensor5=A0)(sensor6=F0);

[0167] T2: (sensor1=E1)(sensor2=C0)(sensor3=D1)(sensor4=E2)(sensor5=B1)(sensor6=D2);

[0168] T3: (sensor1=D2) (sensor2=B2) (sensor3=B1) (sensor4=A0) (sensor5=B2) (sensor6=D1).

[0169] In this mode, when an obstacle appears in the left front, the center frequency of sensor2 at T1 is selected as F0, which has the longest detection distance, but a small detection range. Therefore, the center frequencies of sensor1 and sensor3 are selected as E2 and D2, which can make up for the detection range of sensor2. E2 and D2 decrease in sequence, and the detection distance increases from far to near. If it is a moving obstacle, the direction of its movement can be monitored.

[0170] At time T2, the center frequency of sensor1 is E1, and it detects from near to far. Sensor1 is installed on the left side of the front guard, and has a large angle deviation from sensor2 adjacent to the front side, so it can predict whether the obstacle is moving to the left and close to sensor1; the center frequencies of sensor2 and sensor3 are C0 and D1 respectively, and the installation angle deviation between the two is small, which can also achieve continuous monitoring of the obstacle's stillness or movement, and continuous monitoring of the obstacle's movement direction.

[0171] At time T3, the detection distance of sensor2 continues to decrease, and the center frequencies of sensor1 and sensor3 are selected as D2 and B1 to compensate for the detection distance and detection range of sensor2, so as to continuously monitor whether the obstacle is stationary or moving, and continuously monitor the direction of the obstacle's movement.

[0172] When the front side is the right front, the center frequencies corresponding to the radar sensors numbered 6, 5 and 4 at each moment in one frequency adjustment cycle are adjusted in the same manner as the center frequencies corresponding to the radar sensors numbered 1, 2 and 3 when the front side is the left front; the center frequencies corresponding to the radar sensors numbered 1, 2 and 3 are adjusted in the same manner as the center frequencies corresponding to the radar sensors numbered 6, 5 and 4 when the front side is the left front.

[0173] When the front side is the right front, the center frequencies corresponding to the radar sensors at each time in a frequency adjustment cycle are as follows:

[0174] T1: (sensor6=E2)(sensor5=F0)(sensor4=D2)(sensor3=E1)(sensor2=A0)(sensor1=F0);

[0175] T2: (sensor6=E1)(sensor5=C0)(sensor4=D1)(sensor3=E2)(sensor2=B1)(sensor1=D2);

[0176] T3: (sensor6=D2) (sensor5=B2) (sensor4=B1) (sensor3=A0) (sensor2=B2) (sensor1=D1).

[0177] The rule followed by the center frequency corresponding to each radar sensor at each moment in a frequency adjustment cycle is similar to that in the case where the side front is the right front, and will not be repeated here.

[0178] In some optional implementations, the embodiments of the present application provide an implementable method for determining the center frequency of each radar sensor at the next moment when the current frequency adjustment mode and the next frequency adjustment mode are consistent and in the straight ahead obstacle mode.

[0179] For example, see Fig.10 , Fig.10 Another flow chart for determining the center frequency of each radar sensor at the next moment is provided, which specifically includes the following steps:

[0180] S1001, if the current frequency adjustment mode is the front obstacle mode, and the center frequency assigned to each second target radar sensor located in the front area of ​​the target external area at the current moment is the variable frequency center frequency, then the frequency change trend of the variable frequency center frequency of each second target radar sensor in the corresponding frequency interval is reversely transformed, and the center frequency of each second target radar sensor after reverse transformation is alternately transformed to obtain the center frequency of each second target radar sensor at the next moment.

[0181] For example, taking the case where the radar sensors deployed in the area directly in front of the target external area include at least two, for example, Figure 6 Among them, sensor3 and sensor4 are used as second target radar sensors located in the area directly in front of the target external area.

[0182] If the current frequency adjustment mode is the obstacle mode in front, and the center frequency assigned to each second target radar sensor in the area in front of the target external area at the current moment is the variable frequency center frequency, then in order to avoid the echo signal that was not received at the previous moment from being interfered by the sensor signal emitted at the next moment, it is necessary to reversely transform the frequency change trend of the variable frequency center frequency of each second target radar sensor in the corresponding frequency interval. For example, the frequency change trend of the variable frequency center frequency of each second target radar sensor in the corresponding frequency interval is transformed from increasing to decreasing, or from decreasing to increasing. Then, the center frequency of each second target radar sensor after the reverse transformation is alternately transformed to obtain the center frequency of each second target radar sensor at the next moment.

[0183] For example, if the center frequencies of sensor3 and sensor4 at the previous moment are E2 and D1 respectively, then the center frequencies of sensor3 and sensor4 at the next moment are D2 and E1 respectively.

[0184] S1002: Allocate a maximum center frequency or a minimum center frequency to a radar sensor adjacent to the second target radar sensor at the next moment according to the detection parameter corresponding to the center frequency of the second target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency.

[0185] Exemplarily, in order to predict whether an obstacle has a tendency to move to the left or right, the maximum center frequency or the minimum center frequency can be allocated to the radar sensor adjacent to the second target radar sensor at the next moment based on the detection parameters corresponding to the center frequency of the second target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency.

[0186] Optionally, when predicting whether the obstacle has a tendency to move to the left, the maximum center frequency can be allocated to the radar sensor sensor2 adjacent to the second target radar sensor at the next moment, and the minimum center frequency can be allocated to the radar sensor sensor5 adjacent to the second target radar sensor at the next moment, so as to use sensor2 to detect whether the obstacle has a tendency to move to the left, and use sensor5 to make up for the detection range of sensor4.

[0187] When predicting whether the obstacle has a tendency to move to the right, the maximum center frequency can be allocated to the radar sensor sensor5 adjacent to the second target radar sensor at the next moment, and the minimum center frequency can be allocated to the radar sensor sensor2 adjacent to the second target radar sensor at the next moment, so as to use sensor5 to detect whether the obstacle has a tendency to move to the right, and use sensor2 to make up for the detection range of sensor3.

[0188] S1003 , with the goal of satisfying the frequency constraint condition between two adjacent radar sensors, allocate center frequencies at the next moment to the remaining radar sensors.

[0189] For example, when allocating the center frequencies of the remaining radar sensors sensor1 and sensor6 at the next moment, it is necessary to aim to satisfy the frequency constraint conditions between two adjacent radar sensors to avoid the co-frequency interference between the center frequencies of radar sensors sensor1 and sensor6 and the already allocated center frequencies. For example, on the basis of ensuring that the center frequencies of radar sensors sensor1 and sensor6 do not interfere with the already allocated center frequencies, a larger center frequency can be allocated to sensor1 and sensor6 as much as possible to increase the detection distance of the radar sensors on both sides of the target external area, so as to timely detect whether there are obstacles on both sides of the target external area.

[0190] Exemplarily, when the side front is the front, the center frequency corresponding to each radar sensor at each time in a frequency adjustment cycle is as follows:

[0191] T1: (sensor1=B1)(sensor2=A0)(sensor3=E2)(sensor4=D1)(sensor5=F0)(sensor6=B1);

[0192] T2: (sensor1=B2)(sensor2=F0)(sensor3=D2)(sensor4=E1)(sensor5=A0)(sensor6=B2);

[0193] T3: (sensor1=B1)(sensor2=A0)(sensor3=E2)(sensor4=D1)(sensor5=F0)(sensor6=B1);

[0194] T4: (sensor1=B2) (sensor2=F0) (sensor3=D2) (sensor4=E1) (sensor5=A0) (sensor6=B2).

[0195] First, sensor3 and sensor4 are set to E2 and D1 frequencies, and then exchanged to D1 and E2 frequencies. After obtaining the direct echo distance and the indirect echo distance, the coordinates of the detected obstacle under the vehicle coordinate axis are solved according to the triangulation positioning, and then the approximate direction of the obstacle can be known.

[0196] Sensor5 at time T1 and sensor2 at time T2 are set to F0, with the longest detection distance. This is the threshold value for distinguishing the left and right movement trend of obstacles. When the obstacle has a left and right movement trend, sensor5 and sensor2 will be triggered, and the echo signal will be received, and then the side and front obstacle mode will be switched.

[0197] Since the insurance mechanism needs to do a repeated inspection to further determine whether the obstacle is moving, and if it is a moving obstacle, it can continuously track the movement bias. In this way, the entire front area can be scanned and the position of the obstacle relative to the vehicle can be calculated.

[0198] In an embodiment of the present application, by setting the center frequency of the second target radar sensor located in the front area, it is possible to detect whether the obstacle has a tendency to approach the vehicle; and by setting the center frequency of the radar sensor adjacent to the second target radar sensor located in the front area at the next moment to detect whether the obstacle has a tendency to move to the left or right, thereby being able to accurately detect the movement trend and direction of the obstacle.

[0199] It should be noted that if obstacles appear in at least two of the front area, the left front area, and the right front area, when allocating the center frequency at each moment to each radar sensor in each area, the goal may be to satisfy the frequency constraint between two adjacent radar sensors, that is, on the basis of no co-frequency interference, the detection distance of the radar sensor in each area is gradually reduced, and the center frequency of the adjacent radar sensor can make up for its detection range. The center frequency at each moment is allocated to each radar sensor in each area, so as to achieve continuous detection of the movement trend and direction of the obstacle.

[0200] It should be noted that the detection data detected by each radar sensor in various frequency adjustment modes in the above embodiments can be combined with the data collected by other sensors to detect obstacles more accurately, which helps to enhance the diversity of conditions for intelligent driving algorithm design and functional scenario judgment.

[0201] In some optional implementations, see Fig.11 , Fig.11 A flowchart of another obstacle detection method is provided, which specifically includes the following steps:

[0202] S1101, obtaining current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency allocated at the current moment.

[0203] S1102: Determine the obstacle detection status of the vehicle based on each current detection data.

[0204] S1103, determining the next frequency adjustment mode at the next moment according to the obstacle detection situation.

[0205] S1104, determining the center frequency of each radar sensor at the next moment according to the consistency between the current frequency adjustment mode at the current moment and the next frequency adjustment mode.

[0206] S1105: Based on the center frequency of each radar sensor at the next moment, the frequency of each radar sensor is adjusted to continuously detect obstacles around the vehicle.

[0207] In intelligent driving, the ultrasonic radar system needs multiple cycles to transmit signals in a round-trip manner to detect the entire environment around the vehicle body. The round-trip mode is complex in design, and it is impossible for all ultrasonic radar systems to work at the same time. The cycle for scanning the entire environment is long and the timeliness is low.

[0208] The obstacle detection method provided by the embodiment of the present application can make the radar sensors work at the same time in all periods, without considering the interval between groups and the cycle change time, so that the radar sensors can switch the center frequency of each radar sensor without delay according to the actual scene. And by setting different candidate center frequencies, it can be achieved that even if the FOV of the radar sensors overlap, the same frequency interference phenomenon can be avoided.

[0209] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0210] Based on the same inventive concept, the embodiment of the present application also provides an obstacle detection device for implementing the above-mentioned obstacle detection method. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above-mentioned method, so the specific limitations in one or more obstacle detection device embodiments provided below can refer to the limitations on the obstacle detection method above, and will not be repeated here.

[0211] In one embodiment, Fig.12 As shown, an obstacle detection device is provided, comprising:

[0212] An acquisition module 10 is used to acquire current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency assigned at the current moment;

[0213] The determination module 20 is used to determine the obstacle detection status of the vehicle according to each current detection data;

[0214] An adjustment module 30, for adjusting the frequency of each radar sensor according to the obstacle detection situation, so as to continuously detect obstacles around the vehicle;

[0215] Among them, the types of the radar sensors are the same, and the frequency constraint conditions are satisfied between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trend of the variable frequency center frequencies in the corresponding frequency interval is increasing or decreasing.

[0216] In one of the embodiments, the center frequency allocated to each radar sensor at the current moment is selected from each candidate center frequency; wherein the number of each candidate center frequency is the same as the number of radars of the radar sensors deployed in the target external area, and each candidate center frequency includes a fixed frequency center frequency and a variable frequency center frequency.

[0217] The obstacle detection device obtains the current detection data collected by each radar sensor in the target external area on the vehicle based on the center frequency assigned at the current moment; and determines the obstacle detection status of the vehicle according to each current detection data; and then adjusts the frequency of each radar sensor according to the obstacle detection status to continuously detect obstacles around the vehicle. Wherein, when the types of each radar sensor are the same, the frequency intervals corresponding to the center frequencies of two adjacent radar sensors overlap or do not overlap, and when there is overlap, there is a variable frequency center frequency and a fixed frequency center frequency in the center frequencies of the two adjacent radar sensors, and the variable frequency center frequency increases or decreases in the corresponding frequency interval. In this way, if the frequency intervals corresponding to the center frequencies of two adjacent radar sensors do not overlap, the problem of co-frequency resonance will not arise; even if the frequency intervals corresponding to the center frequencies of two adjacent radar sensors overlap, one of the center frequencies of the two adjacent radar sensors is a variable frequency center frequency and the other is a fixed frequency center frequency, and the variable frequency center frequency increases or decreases within the corresponding frequency interval, so that the waveforms of the variable frequency center frequency and the fixed frequency center frequency are not the same, even if there is an intersection, the signal receiver can correctly receive and analyze the radar sensor signal according to the waveforms of the variable frequency center frequency and the fixed frequency center frequency; or in the case of two variable frequency center frequencies with the same frequency interval, the frequency change trends of the two variable frequency center frequencies within the corresponding frequency interval are opposite and the frequency change rates are different, and no intersection will appear, and the signal receiver can correctly receive and analyze the radar sensor signal, thereby improving the accuracy of detecting the distance between the vehicle and the surrounding obstacles.

[0218] In one embodiment, the determination module 20 is further configured to:

[0219] The working frequency range of the radar sensor is divided to obtain at least two fixed-frequency center frequencies; wherein the frequency intervals corresponding to two adjacent fixed-frequency center frequencies do not overlap; when the deployment quantity of each radar sensor is greater than the frequency quantity of the fixed-frequency center frequency, the quantity difference between the deployment quantity and the frequency quantity is determined; and variable-frequency center frequencies of the quantity difference are added between adjacent fixed-frequency center frequencies; wherein the frequency intervals corresponding to two adjacent variable-frequency center frequencies do not overlap.

[0220] In one embodiment, the adjustment module 30 specifically includes:

[0221] A first determining unit, configured to determine a next frequency adjustment mode at a next moment according to an obstacle detection situation;

[0222] A second determining unit, configured to determine the center frequency of each radar sensor at a next moment according to the consistency between the current frequency adjustment mode at a current moment and the next frequency adjustment mode;

[0223] The adjustment unit is used to adjust the frequency of each radar sensor based on the center frequency of each radar sensor at the next moment.

[0224] In one embodiment, the second determining unit specifically includes:

[0225] A first determination subunit is used to determine the center frequency of each radar sensor at a next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment if the current frequency adjustment mode at the current moment is consistent with the next frequency adjustment mode;

[0226] The second determining subunit is used to determine the center frequency of each radar sensor at the next moment according to the next frequency adjustment mode if the current frequency adjustment mode at the current moment and the next frequency adjustment mode are inconsistent.

[0227] In one embodiment, the first determining subunit is specifically configured to:

[0228] If the current frequency adjustment mode is the obstacle-free mode, the frequency change trend of the variable frequency center frequency in the corresponding frequency interval among the center frequencies allocated to each radar sensor at the current moment is reversed to obtain a new center frequency allocated to each radar sensor at the current moment; for each radar sensor, the new center frequency allocated to the radar sensor at the current moment is used as the center frequency of the radar sensor corresponding to the next sensor number at the next moment; wherein, the sensor numbers of two adjacent radar sensors are incremented, and the next sensor number of the last sensor number is the first sensor number.

[0229] In one embodiment, the first determining subunit is specifically configured to:

[0230] If the current frequency adjustment mode is the side-front obstacle mode, the center frequency of the first target radar sensor at the next moment is determined according to the center frequency allocated to the first target radar sensor located in the side-front area of ​​the target external area at the current moment, the detection parameters corresponding to each candidate center frequency, and the frequency conversion rule; wherein the frequency conversion rule is that the detection distance corresponding to the center frequency of the first target radar sensor at the next moment is less than the detection distance corresponding to the center frequency at the current moment; the center frequency of the radar sensor adjacent to the first target radar sensor at the next moment is determined according to the detection parameters corresponding to the center frequency of the first target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency; and the center frequency at the next moment is allocated to the remaining radar sensors with the goal of satisfying the frequency constraint condition between two adjacent radar sensors.

[0231] In one embodiment, the first determining subunit is specifically configured to:

[0232] The detection blind spot of the first target radar sensor is determined according to the detection parameters corresponding to the center frequency of the first target radar sensor at the next moment, wherein the detection parameters include the detection distance and the detection range; the center frequency of the radar sensor adjacent to the first target radar sensor at the next moment is determined according to the detection blind spot and the detection parameters corresponding to each candidate center frequency; wherein the detection parameters corresponding to the center frequency of the radar sensor adjacent to the first target radar sensor at the next moment can cover the detection blind spot.

[0233] In one embodiment, the first determining subunit is specifically configured to:

[0234] If the current frequency adjustment mode is the front obstacle mode, and the center frequency assigned to each second target radar sensor located in the front area of ​​the target external area at the current moment is the variable frequency center frequency, then the frequency change trend of the variable frequency center frequency of each second target radar sensor in the corresponding frequency interval is reversely transformed, and the center frequency of each second target radar sensor after reverse transformation is alternately transformed to obtain the center frequency of each second target radar sensor at the next moment; according to the detection parameter corresponding to the center frequency of the second target radar sensor at the next moment and the detection parameter corresponding to each candidate center frequency, the maximum center frequency or the minimum center frequency is assigned to the radar sensor adjacent to the second target radar sensor at the next moment; with the goal of satisfying the frequency constraint condition between two adjacent radar sensors, the center frequency of the next moment is assigned to the remaining radar sensors.

[0235] In one embodiment, the first determining unit is specifically configured to:

[0236] If the obstacle detection situation is that no obstacle is detected, the next frequency adjustment mode at the next moment is determined to be the no obstacle mode; if the obstacle detection situation is that an obstacle is detected in front of the side of the target external area, the next frequency adjustment mode at the next moment is determined to be the side front obstacle mode; if the obstacle detection situation is that an obstacle is detected directly in front of the target external area, the next frequency adjustment mode at the next moment is determined to be the front obstacle mode.

[0237] Each module in the above obstacle detection device can be implemented in whole or in part by software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each module.

[0238] In one embodiment, a computer device is provided, which includes a SOC, and its internal structure diagram can be as follows: Fig.13 As shown. The computer device includes a processor, a memory and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store each candidate center frequency data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, an obstacle detection method is implemented.

[0239] Those skilled in the art will understand that Fig.13 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0240] In one embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the steps of the obstacle detection method described in any of the above embodiments are implemented.

[0241] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the obstacle detection method described in any of the above embodiments are implemented.

[0242] In one embodiment, a computer program product is provided, including a computer program, which implements the steps of the obstacle detection method described in any of the above embodiments when executed by a processor.

[0243] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0244] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0245] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. An obstacle detection method, characterized in that: The method comprises: Obtaining current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency assigned at the current moment; Determining the obstacle detection status of the vehicle according to each current detection data; According to the obstacle detection situation, the frequency of each radar sensor is adjusted to continuously detect obstacles around the vehicle; Among them, the types of the radar sensors are the same, and the frequency constraint conditions are satisfied between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trend of the variable frequency center frequency in the corresponding frequency interval is increasing or decreasing.

2. The method according to claim 1, characterized in that The center frequency allocated to each radar sensor at the current moment is selected from each candidate center frequency; wherein the number of each candidate center frequency is the same as the number of radars of the radar sensors deployed in the target external area, and each candidate center frequency includes a fixed frequency center frequency and a variable frequency center frequency.

3. The method according to claim 2, characterized in that Each candidate center frequency is determined by: The operating frequency range of the radar sensor is divided to obtain at least two fixed-frequency center frequencies; wherein the frequency intervals corresponding to two adjacent fixed-frequency center frequencies do not overlap; When the number of deployed radar sensors is greater than the number of frequencies of the fixed-frequency center frequency, determining a quantity difference between the number of deployed radar sensors and the number of frequencies; Add the variable frequency center frequencies of the difference value between adjacent fixed frequency center frequencies; wherein the frequency intervals corresponding to two adjacent variable frequency center frequencies do not overlap.

4. The method according to claim 1, characterized in that The step of adjusting the frequency of each radar sensor according to the obstacle detection situation includes: Determining a next frequency adjustment mode at a next moment according to the obstacle detection situation; Determining the center frequency of each radar sensor at a next moment according to the consistency between the current frequency adjustment mode at the current moment and the next frequency adjustment mode; Based on the center frequency of each radar sensor at the next moment, the frequency of each radar sensor is adjusted.

5. The method according to claim 4, characterized in that The step of determining the center frequency of each radar sensor at the next moment according to the consistency between the current frequency adjustment mode at the current moment and the next frequency adjustment mode includes: If the current frequency adjustment mode at the current moment is consistent with the next frequency adjustment mode, determining the center frequency of each radar sensor at the next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment; If the current frequency adjustment mode at the current moment is inconsistent with the next frequency adjustment mode, the center frequency of each radar sensor at the next moment is determined according to the next frequency adjustment mode.

6. The method according to claim 5, characterized in that The determining the center frequency of each radar sensor at a next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment includes: If the current frequency adjustment mode is the obstacle-free mode, the frequency change trend of the frequency conversion center frequency in the center frequency allocated to each radar sensor at the current moment in the corresponding frequency interval is reversely transformed to obtain a new center frequency allocated to each radar sensor at the current moment; For each radar sensor, the new center frequency allocated to the radar sensor at the current moment is used as the center frequency of the radar sensor corresponding to the next sensor sequence number at the next moment; The sensor numbers of two adjacent radar sensors are incremented, and the next sensor number of the last sensor number is the first sensor number.

7. The method according to claim 5, characterized in that The determining the center frequency of each radar sensor at a next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment includes: If the current frequency adjustment mode is the side-front obstacle mode, the center frequency of the first target radar sensor at the next moment is determined according to the center frequency assigned to the first target radar sensor located in the side-front area of ​​the target external area at the current moment, the detection parameters corresponding to each candidate center frequency, and the frequency conversion rule; wherein the frequency conversion rule is that the detection distance corresponding to the center frequency of the first target radar sensor at the next moment is less than the detection distance corresponding to the center frequency at the current moment; determining, according to the detection parameter corresponding to the center frequency of the first target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency, the center frequency of a radar sensor adjacent to the first target radar sensor at the next moment; With the goal of satisfying the frequency constraint condition between two adjacent radar sensors, the center frequencies at the next moment are allocated to the remaining radar sensors.

8. The method according to claim 7, characterized in that The determining, according to the detection parameter corresponding to the center frequency of the first target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency, the center frequency of the radar sensor adjacent to the first target radar sensor at the next moment includes: Determine the detection blind area of ​​the first target radar sensor according to the detection parameters corresponding to the center frequency of the first target radar sensor at the next moment; wherein the detection parameters include the detection distance and the detection range; The center frequency of a radar sensor adjacent to the first target radar sensor at a next moment is determined according to the detection blind spot and the detection parameters corresponding to each candidate center frequency; wherein the detection parameters corresponding to the center frequency of the radar sensor adjacent to the first target radar sensor at the next moment can cover the detection blind spot.

9. The method according to claim 5, characterized in that The determining the center frequency of each radar sensor at a next moment according to the current frequency adjustment mode and the center frequency allocated to each radar sensor at the current moment includes: If the current frequency adjustment mode is the front obstacle mode, and the center frequency assigned to each second target radar sensor located in the front area of ​​the target external area at the current moment is the frequency conversion center frequency, then the frequency change trend of the frequency conversion center frequency of each second target radar sensor in the corresponding frequency interval is reversely transformed, and the center frequency of each second target radar sensor after reverse transformation is alternately transformed to obtain the center frequency of each second target radar sensor at the next moment; allocating a maximum center frequency or a minimum center frequency to a radar sensor adjacent to the second target radar sensor at the next moment according to the detection parameter corresponding to the center frequency of the second target radar sensor at the next moment and the detection parameters corresponding to each candidate center frequency; With the goal of satisfying the frequency constraint condition between two adjacent radar sensors, the center frequencies at the next moment are allocated to the remaining radar sensors.

10. The method according to claim 4, characterized in that Determining a next frequency adjustment mode at a next moment according to the obstacle detection situation includes: If the obstacle detection condition is that no obstacle is detected, determining that the next frequency adjustment mode at the next moment is a no-obstacle mode; If the obstacle detection condition is that the obstacle is detected in front of the side of the target external area, determining the next frequency adjustment mode at the next moment to be the side-front obstacle mode; If the obstacle detection situation is that an obstacle is detected right in front of the target external area, then the next frequency adjustment mode at the next moment is determined to be the front obstacle mode.

11. An obstacle detection device, characterized in that: The device comprises: An acquisition module is used to acquire current detection data collected by each radar sensor in the target external area on the vehicle based on the central frequency assigned at the current moment; A determination module, used to determine the obstacle detection status of the vehicle according to each current detection data; An adjustment module, used to adjust the frequency of each radar sensor according to the obstacle detection situation, so as to continuously detect obstacles around the vehicle; Among them, the types of the radar sensors are the same, and the frequency constraint conditions are satisfied between two adjacent radar sensors; the frequency constraint conditions include whether the frequency intervals corresponding to the center frequencies of the two adjacent radar sensors overlap or do not overlap; in the case of overlap, the center frequencies of the two adjacent radar sensors are a variable frequency center frequency and a fixed frequency center frequency, or two variable frequency center frequencies with the same frequency interval, and the frequency change trends of the two variable frequency center frequencies in the corresponding frequency interval are opposite and the frequency change rates are different, and the frequency change trend of the variable frequency center frequency in the corresponding frequency interval is increasing or decreasing.

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