Road environment sensing system based on millimeter wave radar imaging

Abstract

The invention belongs to the field of radar detection and radar imaging, and relates to a road environment sensing system based on millimeter-wave radar imaging, which comprises a millimeter-wave radar sensor unit for transmitting electromagnetic waves, receiving target echoes and acquiring road environment information in a radar view range; the antenna beam control unit is used for controlling a beam transmitting mode of the millimeter wave radar antenna array, realizing high-precision detection and providing a data source; the data preprocessing unit is used for performing data analysis on the original data acquired by the antenna beam control unit, processing the data through four-dimensional FFT (Fast Fourier Transform), and acquiring the data of the distance, the speed, the height and the direction between the road environment and the target on the road; the environment imaging and detecting unit is used for processing data to realize three-dimensional imaging and moving target detection of the road environment and identifying abnormal conditions in the road environment; and the alarm unit gives an alarm according to the detection processing result. The three-dimensional imaging of the road environment can be realized, and the detailed information of the target can be obtained.

Description

Technical Field

[0001] The present invention belongs to the field of radar detection and radar imaging, and particularly relates to a millimeter wave radar imaging system, and particularly relates to a road environment perception system based on millimeter wave radar imaging, which is used for imaging and perception of road environment. Background Art

[0002] Roads are important infrastructure. Preventing and detecting the intrusion of foreign objects (such as pedestrians, animals, falling rocks, etc.), rail wear and road collapse are of great significance to preventing major accidents and protecting the normal operation of the road system.

[0003] At present, cameras and LiDARs have been widely used in road environment monitoring. Cameras can obtain rich image information, and LiDARs can obtain accurate information such as the angle, distance, and speed of the target. However, both sensors have major defects. Although cameras have the advantages of obtaining rich image information and being inexpensive and easy to install, camera sensors are easily affected by environmental factors such as weather and light when collecting data, and target distance and speed information will be lost in the image data. LiDARs are expensive and have relatively high data acquisition and processing costs. Environmental changes will also affect their acquisition of target information.

[0004] Although millimeter-wave radar sensors have the advantage of working around the clock and in all weather conditions, they can only obtain the target's 2D plane coordinates and speed by measuring the target's distance and angle. The radar can only perform planar imaging of the road environment, and there is a risk of false detection and missed detection of targets. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a road environment perception system based on millimeter wave radar imaging, so as to achieve stereoscopic imaging of the road environment and obtain detailed information of the target.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The road environment perception system based on millimeter-wave radar imaging includes:

[0008] Millimeter wave radar sensor unit, used to transmit electromagnetic waves and receive target echoes to obtain road environment information within the radar field of view;

[0009] Antenna beam control unit, which controls the beam emission mode of the millimeter-wave radar antenna array, realizes high-precision detection of the road environment, and provides a data source for the environmental imaging and detection unit;

[0010] The data preprocessing unit analyzes the raw data obtained by the antenna beam control unit, processes the data through 4-dimensional FFT, and obtains the distance, speed, height, and direction data between the road environment and the target on the road;

[0011] Environmental imaging and detection unit, through data processing, realizes stereoscopic imaging of the road environment and detection of moving targets, as well as identification of abnormal situations in the road environment;

[0012] The alarm unit implements an alarm based on the detection and processing results of the environmental imaging and detection unit.

[0013] In one embodiment, the millimeter wave radar sensor unit includes:

[0014] The antenna array unit has multiple transmitting antennas and multiple receiving antennas, which transmit electromagnetic waves outward with a set beam and receive target echoes;

[0015] A baseband processing unit, used to convert the target echo received by the antenna from an analog signal into a digital signal;

[0016] Signal data processing unit, used for storage and execution of signal processing and data processing programs.

[0017] In one embodiment, the antenna beam control unit includes:

[0018] A transmission control unit controls the beam transmission mode of the millimeter wave radar antenna array in a time division multiplexing manner;

[0019] The receiving control unit completely receives the data from each transmitting antenna;

[0020] The antenna beam control unit controls the transmission and reception modes of the antenna array to form an orthogonal time-sharing multiple-input multiple-output mode, thereby achieving the acquisition of original data of the road environment.

[0021] In one embodiment, the data preprocessing unit includes:

[0022] A data analysis unit, which performs data analysis on the original road environment data acquired by the antenna beam control unit;

[0023] A data calibration unit calibrates the antenna phase, frequency and process error of the parsed data according to the calibration matrix;

[0024] The data processing unit performs range FFT and Doppler FFT changes on the calibration data to obtain a range-Doppler matrix set containing target range and velocity information;

[0025] The moving target detection unit completes the detection of each range-Doppler matrix in the CFAR detection module; and performs velocity deambiguation and phase compensation on the target detected in the CFAR; after deambiguation and compensation, the azimuth and pitch angle of the target are estimated, and finally the four-dimensional information of the target is obtained.

[0026] In one embodiment, the data analysis of the data analysis unit is to perform incoherent integration, data pre-processing and CFAR processing on the RDM matrix in the moving target detection unit. Please specify whether it is completed before or after the CFAR detection module completes the detection, and explain the corresponding purpose.

[0027] In one embodiment, the environment imaging and detection unit comprises:

[0028] The imaging processing unit converts the target direction angle and pitch angle obtained by the preprocessing unit into point cloud coordinates to obtain a three-dimensional point cloud map of the target, uses a compressed sensing algorithm to perceive the road environment, and forms a three-dimensional radar image;

[0029] The radar image detection unit uses a template matching algorithm to detect obstacles on the railway.

[0030] In one embodiment, the alarm unit sends alarm information to a monitoring center and a road alarm device via a network.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) The present invention uses millimeter wave radar to obtain road environment information, realizes accurate acquisition of target three-dimensional coordinates and speed information, and avoids the influence of weather on the sensor.

[0033] 2) The present invention uses CFAR and DOA algorithms to obtain information such as speed, horizontal angle, pitch angle, distance, etc. of moving targets on the road, uses point cloud coordinate transformation and compressed sensing algorithms to perceive the road environment, and forms a three-dimensional radar image.

[0034] 3) The present invention designs an alarm unit to ensure that the road monitoring station and the railway site can handle abnormal situations in a timely manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a system structure block diagram of the present invention;

[0036] Figure 2 It is a schematic diagram of the application of the system of the present invention;

[0037] Figure 3 is a schematic diagram of target detection and beam control of a millimeter wave radar sensor unit of the present invention;

[0038] Figure 4 It is a flow chart of the data preprocessing unit of the present invention;

[0039] Figure 5 It is the principle diagram of point cloud coordinate transformation of the environmental imaging and detection unit;

[0040] Figure 6 Imaging and foreign object detection discrimination block diagram of the environmental imaging and detection unit;

[0041] Figure 7 It is the early warning frame diagram. DETAILED DESCRIPTION

[0042] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0043] In view of the shortcomings of millimeter-wave radar and the requirements for road environment detection (for example, obtaining target information in a timely and accurate manner and clear images), the present invention has designed a millimeter-wave radar detection system. By designing an antenna array, while ensuring the detection accuracy of the radar directional dimension, it has a high-precision pitch resolution, thereby achieving four-dimensional data acquisition of target speed, azimuth, pitch angle, and distance. And further realize stereoscopic imaging of the road environment to obtain detailed information of the target. Compared with traditional radars, millimeter-wave radar detection systems are more accurate and reliable, and are more adapted to the needs of road environment monitoring applications.

[0044] like Figure 1 As shown, the present invention mainly includes a millimeter wave radar sensor unit, an antenna beam control unit, a data preprocessing unit, an environment imaging and detection unit and an alarm unit. It is easy to understand that the number of each unit of the present invention can be set as needed.

[0045] Among them, the function of the millimeter wave radar sensor unit is to emit electromagnetic waves and receive target echoes, thereby obtaining road environment information within the radar field of view. Its millimeter wave antenna forms a MIMO system through a linear array. The main function of the antenna beam control unit is to control the beam emission mode of the antenna array of the millimeter wave radar to achieve high-precision detection of the road environment, obtain high-precision road environment data, and provide a data source for the environmental imaging and detection unit. The data preprocessing unit performs data analysis on the raw data obtained by the antenna beam control unit, and processes the data through 4-dimensional FFT to obtain the distance, speed, height, and direction information between the road environment and the target on the road, that is, data. The environmental imaging and detection unit processes the data to achieve stereoscopic imaging and moving target detection of the road environment, and identifies abnormal situations such as obstacles, pedestrians, and animals in the road environment. The alarm unit implements an alarm based on the detection and processing results of the environmental imaging and detection unit.

[0046] Reference Figure 2Due to its small size, the millimeter-wave radar can be installed together with the alarm unit on the bracket at the top of the roadside guardrail. It is worth noting that the millimeter-wave radar needs to be tilted downward at a certain angle to align it with the center of the rail to ensure comprehensive perception of the road environment.

[0047] After the millimeter-wave radar transmits the sensed information to the environmental imaging and detection unit after preliminary processing, the environmental imaging and detection unit calibrates, preprocesses, detects moving targets, and images the data, then detects whether there are foreign objects on the rails, and can determine the state of the target (moving target or static target). After giving the judgment result, if there are foreign objects, the information will be sent to the early warning device and monitoring center through the network, thereby realizing the perception, monitoring and early warning of the road environment.

[0048] The millimeter wave radar sensor unit of the present invention mainly includes an antenna array unit, a baseband processing unit and a signal data processing unit, wherein the antenna array unit has multiple transmitting antennas and multiple receiving antennas, and sends electromagnetic waves outward with a set specific beam and receives target echoes; the baseband processing unit converts the target echo received by the antenna from an analog signal to a digital signal, and the signal data processing unit is used for storing and executing signal processing and data processing programs.

[0049] Reference Figure 3 In one embodiment of the present invention, the antenna array has 12 transmitting antennas and 16 receiving antennas. The beam control unit controls the antenna array to form an orthogonal time-division multiple-input multiple-output mode (TDM-MIMO). In the MIMO mode, 12 transmitting array elements simultaneously transmit orthogonal signals. These orthogonal signals are received by 16 receiving array elements after being scattered by the target. 12×16 observation channels are formed from the transmitting array elements to the receiving array elements. Each receiving array element at the receiving end obtains 12×16 echoes through signal modulation and filtering matching. The echo of each orthogonal signal carries independent target information, so that the radar can cover a wide space at the same time, and the transmitting signals will not affect each other in the air, so the target information obtained by the radar will be more accurate. The echo data is processed and converted into a digital signal and transmitted to the environmental imaging and detection unit.

[0050] The antenna beam control unit includes a transmitting control unit and a receiving control unit. The transmitting control unit controls the beam transmission mode of the millimeter wave radar antenna array in a time division multiplexing manner; the receiving control unit completely receives the data of each transmitting antenna. Through the control of the transmitting and receiving modes of the antenna array by the antenna beam control unit, an orthogonal time-division multiple input multiple output mode (TDM-MIMO) can be formed to obtain the original data of the road environment.

[0051] The data preprocessing unit of the present invention mainly includes a data analysis unit, a data calibration unit, a data processing unit and a moving target detection unit. Figure 4 The data analysis unit analyzes the original data of the road environment obtained by the antenna beam control unit; the data calibration unit calibrates the antenna phase, frequency and process error of the analyzed data according to the calibration matrix; the data processing unit performs range FFT and Doppler FFT changes on the calibration data to obtain a range-Doppler matrix (RDM) set containing target distance and speed information; the moving target detection unit completes the detection of each range-Doppler matrix in the CFAR detection module, and in the moving target detection unit, the RDM matrix is ​​incoherently integrated, data pre-processed and CFAR processed; next, the target detected in the CFAR is subjected to velocity deambiguation and phase compensation; after deambiguation and compensation, the target is angle estimated, first the azimuth angle is estimated, and then the pitch angle is estimated, and finally the four-dimensional information of the target is obtained.

[0052] The environmental imaging and detection unit of the present invention mainly includes an imaging processing unit and a radar image detection unit, wherein the imaging processing unit performs point cloud coordinate conversion on the target direction angle and pitch angle obtained by the preprocessing unit to obtain a three-dimensional point cloud map of the target, uses a compressed sensing algorithm to realize perception of the road environment, and forms a three-dimensional radar image; the radar image detection unit uses a template matching algorithm to detect obstacles on the railway.

[0053] Specifically, refer to Figure 5 The target direction angle (α) and elevation angle (β) obtained by the radar are the angles of the target relative to the azimuth antenna and the elevation antenna, respectively, not the true angle of the target in the three-dimensional coordinate system. Therefore, it is necessary to geometrically transform the angle information obtained by the radar according to the conversion relationship shown in the figure to obtain the direction angle (θ) and elevation angle of the target relative to the radar dot. Then the target three-dimensional point cloud image is obtained.

[0054] Reference Figure 6 After receiving the radar data, the environmental imaging and detection unit extracts the moving target information and finally obtains the four-dimensional information of the moving target in the road environment, including the speed, distance, horizontal angle and pitch angle; forms the radar imaging of the road environment through point cloud coordinate transformation and compressed sensing algorithm; transmits the moving target information and radar image to the image detection unit, detects obstacles on the rails through the template matching algorithm, and sends the detection results to the alarm unit.

[0055] Reference Figure 7 The alarm unit receives the radar image detection results. When there are foreign objects on the railway, the system will send the information to the monitoring center through the network. At the same time, it will link the road alarm device on site to issue voice and alarm light warnings.

Claims

1. A road environment perception system based on millimeter wave radar imaging, characterized in that: include: Millimeter wave radar sensor unit, used to transmit electromagnetic waves and receive target echoes to obtain road environment information within the radar field of view; Antenna beam control unit, which controls the beam emission mode of the millimeter-wave radar antenna array, realizes high-precision detection of the road environment, and provides a data source for the environmental imaging and detection unit; The data preprocessing unit analyzes the raw data obtained by the antenna beam control unit, processes the data through 4-dimensional FFT, and obtains the distance, speed, height, and direction data between the road environment and the target on the road; Environmental imaging and detection unit, through data processing, realizes stereoscopic imaging of the road environment and detection of moving targets, as well as identification of abnormal situations in the road environment; The alarm unit implements an alarm based on the detection and processing results of the environmental imaging and detection unit.

2. The road environment perception system based on millimeter wave radar imaging according to claim 1 is characterized in that: The millimeter wave radar sensor unit comprises: The antenna array unit has multiple transmitting antennas and multiple receiving antennas, which transmit electromagnetic waves outward with a set beam and receive target echoes; A baseband processing unit, used to convert the target echo received by the antenna from an analog signal into a digital signal; Signal data processing unit, used for storage and execution of signal processing and data processing programs.

3. The road environment perception system based on millimeter wave radar imaging according to claim 1 is characterized in that: The antenna beam control unit comprises: A transmission control unit controls the beam transmission mode of the millimeter wave radar antenna array in a time division multiplexing manner; The receiving control unit completely receives the data from each transmitting antenna; The antenna beam control unit controls the transmission and reception modes of the antenna array to form an orthogonal time-sharing multiple-input multiple-output mode, thereby achieving the acquisition of original data of the road environment.

4. The road environment perception system based on millimeter wave radar imaging according to claim 1 is characterized in that: The data preprocessing unit comprises: A data analysis unit, which performs data analysis on the original road environment data acquired by the antenna beam control unit; A data calibration unit calibrates the antenna phase, frequency and process error of the parsed data according to the calibration matrix; The data processing unit performs range FFT and Doppler FFT changes on the calibration data to obtain a range-Doppler matrix set containing target range and velocity information; The moving target detection unit completes the detection of each range-Doppler matrix in the CFAR detection module; and performs velocity deambiguation and phase compensation on the target detected in the CFAR; after deambiguation and compensation, the azimuth and pitch angle of the target are estimated, and finally the four-dimensional information of the target is obtained.

5. The road environment perception system based on millimeter wave radar imaging according to claim 4 is characterized in that: The data analysis of the data analysis unit is the incoherent integration, data pre-processing and CFAR processing of the RDM matrix in the moving target detection unit. Please specify whether it is completed before or after "the CFAR detection module completes the detection" and explain the corresponding purpose.

6. The road environment perception system based on millimeter wave radar imaging according to claim 1 is characterized in that: The environmental imaging and detection unit comprises: The imaging processing unit converts the target direction angle and pitch angle obtained by the preprocessing unit into point cloud coordinates to obtain a three-dimensional point cloud map of the target, uses a compressed sensing algorithm to perceive the road environment, and forms a three-dimensional radar image; The radar image detection unit uses a template matching algorithm to detect obstacles on the railway.

7. The road environment perception system based on millimeter wave radar imaging according to claim 1 is characterized in that: The alarm unit sends alarm information to the monitoring center and the road alarm device through the network.

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