CN117826084A - A detection method for judging whether a millimeter-wave radar is blocked based on target distance and angle - Google Patents

Abstract

The present invention provides a detection method for judging whether a millimeter-wave radar is blocked based on target distance and angle. It includes step 1: obtaining the original ADC data of the millimeter-wave radar directly covered by foreign objects and performing standard radar signal processing to obtain the target distance and angle value, and statistically analyzing the distribution of the distance and angle values of the target corresponding to the blocking object to obtain the maximum distance value and the maximum angle value; step 2: quantifying step 1 multiple times to obtain the distance mean and angle mean of each experimental value, and setting the distance threshold and angle threshold; step 3: obtaining the original ADC data of the millimeter-wave radar at the current moment, performing standard radar signal processing on the ADC data, and obtaining the current target distance value and angle value; step 4: judging whether the radar has detected a target with a distance less than the distance threshold at the current moment, if not, it is considered that it is not blocked; if the distance value is less than the distance threshold and the angle is less than the angle threshold, it is considered that the target is an obstruction, and the radar is judged to be blocked.

Description

A detection method for judging whether a millimeter-wave radar is blocked based on target distance and angle

Technical Field

The present invention relates to the field of radar technology, and in particular to a method for determining an obstruction based on a target distance and an angle value detected by a radar, and further determining whether the radar is obstructed.

Background technique

As one of the sensors for intelligent driving car environment perception, millimeter wave radar is widely used due to its unique advantages of all-weather, all-day, low cost, and real-time speed measurement capabilities. In actual applications, millimeter wave radar is generally installed in the bumper of the car. The bumper covering the radar is generally specially designed in terms of material selection, surface treatment, and installation angle to ensure that the radar electromagnetic wave has good permeability and minimize the attenuation of electromagnetic wave energy and the distortion of the beam. However, during the long-term use of the vehicle, wet snow, mud or other obstructions may cover the surface of the bumper facing the radar, which will affect the radar's perception of the vehicle's external environment. When severely obstructed, the radar may even lose the ability to detect targets in the surrounding environment.

Huizhou Desay SV Intelligent Transportation Technology Research Institute Co., Ltd. A method for detecting the obstruction status of a vehicle-mounted millimeter-wave radar based on target recognition. The method uses the detectable distance between the millimeter-wave radar's ground reflection and the absolutely stationary reflector in the environment based on the vehicle speed information, and analyzes the situation where there is foreign object obstruction and the situation where there is no foreign object obstruction at the bumper directly in front of the millimeter-wave radar.

Huizhou Desay SV Intelligent Transportation Technology Research Institute Co., Ltd. A vehicle-mounted millimeter-wave radar obstruction detection method based on amplitude change rate analysis. Obtain the FFT amplitude change characteristic statistical analysis of the time domain echo signals of multiple channels of the millimeter-wave radar under the conditions of direct coverage by foreign objects and without direct coverage by foreign objects, and judge whether the millimeter-wave radar is obstructed based on the FFT amplitude change characteristic statistical analysis results and the FFT amplitude change characteristic statistical analysis results of the time domain echo signals of multiple channels of the millimeter-wave radar at the current moment.

The above two methods mainly judge whether the radar is blocked based on the difference in detection results when the radar is blocked. However, these methods may misjudge in some special scenarios, such as when the vehicle is in an open environment, because the number of targets in the environment is small, which is similar to the situation when the radar is blocked. At this time, judging based solely on the number of targets will lead to misjudgment. This patent proposes a method to directly detect the obstruction based on distance and angle to determine whether the radar is blocked.

Summary of the invention

In view of this, the present application provides a method for determining whether a millimeter-wave radar is blocked based on target distance and angle.

In order to solve the above technical problems, the technical solution of the present invention is as follows:

A method for determining whether a millimeter-wave radar is blocked based on target distance and angle comprises the following steps:

Step 1: Obtain the original ADC data of the millimeter-wave radar under direct coverage of foreign objects and perform standard radar signal processing to obtain the distance and angle values of each target, and then count the distribution of the distance and angle values of the target corresponding to the obstruction to obtain its maximum distance value and maximum angle value;

Step 2: quantify step 1 multiple times to calculate the distance mean and angle mean of each experimental value, and set the distance threshold and angle threshold;

Step 3: Obtain the original ADC data of the millimeter-wave radar at the current moment, perform standard radar signal processing on the ADC data, and obtain the target distance value and angle value in the current environment;

Step 4: Determine whether the radar has detected a target whose distance is less than the distance threshold at the current moment. If not, it is considered that there is no obstruction; if the distance value is less than the distance threshold and the angle is less than the angle threshold, the target is considered to be an obstruction and the radar is determined to be obstructed;

The specific contents of step 1 are as follows: Under the transmission and reception of a radar frame, the original ADC data of each channel collected by the receiving antenna is compressed in the distance and speed dimensions through 2D-FFT, and then incoherently accumulated in the channel dimension. The accumulated data matrix is subjected to constant false alarm (CFAR) algorithm detection to detect the target, and the distance and speed information of each target can be obtained at this time. Then, the angle estimation (DOA) of these targets is performed to complete the distance, speed and angle measurement of the target.

The specific content of step 2 is as follows: When the radar is blocked, the blocker is close to the car hood, the target distance corresponding to the blocker must be very small, and because it is directly in front of the radar, the detected target angle value should be close to 0 ^0. The target distance and angle statistics obtained from multiple groups of experiments set the maximum distance value threshold R0 and the maximum angle value threshold α0. The two thresholds can be set equal to or slightly larger than the statistical means Rmean and αmean under multiple experiments.

The present invention performs statistical analysis on the target distance and angle values detected by the radar to judge the obstruction of the millimeter-wave radar, thereby effectively realizing the obstruction condition detection of the vehicle-mounted millimeter-wave radar. The method is simple and effective, has low requirements on computing power, ensures the vehicle-mounted millimeter-wave radar system's ability to perceive the environment, and meets the real-time requirements of the application.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a flow chart of this patent solution

Figure 2 is a flowchart of data preprocessing

Figure 3 is a signal processing flow chart

Figure 4 is a measurement diagram

Specific implementation plan

A method for judging whether a millimeter-wave radar is blocked based on target distance and angle, using the millimeter-wave radar to detect the detectable distance and angle value of the obstruction, respectively analyzing the two situations of foreign object obstruction and no foreign object obstruction at the bumper directly in front of the millimeter-wave radar, presetting the distance and angle thresholds based on the statistical laws of the distance and angle of the obstruction during the obstruction obtained in advance based on experimental statistical results, and comparing the thresholds with the actual distance and angle values in the real-time obstruction detection process to confirm the results. This method is simple, effective, and has low computing power requirements, ensuring the vehicle-mounted millimeter-wave radar system's ability to perceive the environment and meeting the real-time requirements of the application.

The steps of the above-mentioned method for detecting the shielding state of the vehicle-mounted millimeter-wave radar are as follows:

Step 1: After the car starts, if the millimeter-wave radar is blocked by foreign objects, obtain the distance and angle values that the millimeter-wave radar can detect in the corresponding speed dimension under the current blocking condition; this step is a quantitative analysis, and the purpose is to obtain the corresponding algorithm threshold by analyzing the situation of foreign object blocking. Statistically calculate the distribution of the distance and angle values of the target corresponding to the blocking object to obtain its maximum distance value Ri and angle value αi. Specifically, the radar's transmission signal data and reception signal data can be mixed to obtain a mixed signal, and the mixed signal can be subjected to distance dimension Fourier transform and angle Fourier transform to obtain the distance data value and angle data value.

Step 2: Repeat step 1 for multiple quantizations. When the radar is blocked, the blockage is close to the car hood. The target distance corresponding to the blockage must be very small, and because it is directly in front of the radar, the angle values of the detected targets should be close to 0 ^° . By collecting the target distances and statistical laws corresponding to these blockages when the radar is blocked, the maximum distance threshold Ro and the maximum angle threshold αo are set. The two thresholds can be set equal to or slightly larger than the statistical means Rmean and αmean under multiple experiments.

The implementation method of the threshold-based confirmation result in the above step 2 is as follows:

Get the distance and angle values detected by the millimeter-wave radar in the actual scene. After obtaining the distance threshold Ro and the angle threshold αo, first determine whether the radar has detected a target with a distance less than Ro at this moment. If not, we believe that the radar is not blocked. If there is a target with a distance less than Ro and the angle of the target is less than the angle threshold αo, we believe that the target is an obstruction and determine that the radar is blocked.

The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Ordinary persons in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

The technical contents not described in detail in the present invention are all known technologies.

Claims (3)

1. A detection method for judging the shielding state of a millimeter-wave radar based on target distance and angle, characterized in that it comprises the following steps: Step 1: Obtain the original ADC data of the millimeter-wave radar under direct coverage of foreign objects and perform standard radar signal processing to obtain the distance and angle values of each target, and count the distribution of the distance and angle values of the target corresponding to the obstruction to obtain its maximum distance value and maximum angle value; Step 2: quantify step 1 multiple times to calculate the distance mean and angle mean of each experimental value, and set the distance threshold and angle threshold; Step 3, obtaining the original ADC data of the millimeter wave radar at the current moment, performing standard radar signal processing on the ADC data, and obtaining the target distance value and angle value in the current environment; Step 4, determine whether the radar has detected a target with a distance less than the distance threshold at the current moment. If not, it is considered that there is no obstruction. If the distance value is less than the distance threshold and the angle is less than the angle threshold, the target is considered to be an obstruction and the radar is determined to be blocked. 2. The detection method according to claim 1, characterized in that step 1 specifically comprises the following sub-steps: Step 1.1: Under the radar frame transmission and reception, the raw ADC data of each channel collected by the receiving antenna is compressed into the distance and speed dimensions through 2D-FFT; Step 1.2: Then, incoherent accumulation is performed in the channel dimension. The accumulated data matrix is subjected to constant false alarm (CFAR) algorithm detection to detect the target. At this time, the distance and speed information of each target can be obtained. Then, the angle estimation (DOA) of these targets is performed to complete the distance, speed and angle measurement of the target. 3. The detection method according to claim 1, characterized in that step 2 specifically comprises the following sub-steps: Step 2.1: When the radar is blocked, the blocker is close to the car hood, the target distance corresponding to the blocker must be very small, and because it is directly in front of the radar, the detected target angle value should be close to 0 ⁰ ; Step 2.2: Based on the target distance and angle statistics obtained from multiple sets of experiments, set the maximum distance value threshold R0 and the maximum angle value threshold α0. The two thresholds can be set equal to or slightly larger than the statistical means Rmean and αmean obtained from multiple experiments.