Millimeter wave radar system based on underground mine roadway and vehicle auxiliary driving system

Abstract

The invention provides a millimeter wave radar system based on an underground mine tunnel and a vehicle auxiliary system. The radar system is characterized in that a radar radio frequency front-end circuit comprises a plurality of cascaded millimeter wave radar chips which are connected with a data acquisition and processing module through a serial peripheral interface, and the plurality of cascaded millimeter wave radar chips are divided into a master chip and at least one slave chip; local oscillation signals generated by the master chip are distributed to the slave chip through the Wilkinson power divider, a digital frame synchronization clock is distributed to the slave chip through the master chip and the clock distributor, and original ADC data captured by the millimeter wave radar chips are transmitted to the data acquisition and processing module. And the data acquisition and processing module is used for performing multi-dimensional FFT processing on the original ADC data transmitted by the radar radio frequency front-end circuit to obtain a distance Doppler image, and separating and identifying a distance and speed map in the distance Doppler image through a CFAR algorithm to obtain distance and speed information of each target around and in the roadway.

Description

Technical Field

[0001] The present application relates to technical fields such as intelligent coal mines and intelligent driving, and in particular to a millimeter wave radar system based on underground mine tunnels and a vehicle assisted driving system having the same. Background Art

[0002] At present, there is no mature and complete vehicle assisted driving system in coal mines. In most cases, the assisted driving system has not been applied to the driving environment underground. In recent years, the 4D millimeter wave radar imaging solutions of major leading companies have significantly improved the assisted driving system on ground roads, but there is no complete system and solution designed for the conditions and situations of underground tunnels.

[0003] Although LiDAR has the advantages of long detection distance and high accuracy, its point cloud accuracy is greatly affected by dust, which has a great impact on the target to be identified. Although traditional millimeter-wave radar is less affected by light and dust, its resolution is not high, so it is not as good as LiDAR in multi-target identification. If used alone in coal mines, there will be safety risks. Summary of the invention

[0004] The present application provides a millimeter wave radar system based on an underground mine tunnel and a vehicle assisted driving system having the same.

[0005] According to a first aspect of an embodiment of the present application, a millimeter wave radar system based on an underground mine tunnel is provided, comprising: a radar radio frequency front-end circuit and a data acquisition and processing module, wherein:

[0006] The radar RF front-end circuit includes a plurality of cascaded millimeter-wave radar chips, the plurality of cascaded millimeter-wave radar chips are respectively connected to the data acquisition and processing module through a serial peripheral interface, the plurality of cascaded millimeter-wave radar chips are divided into a master chip and at least one slave chip, the local oscillator signal generated by the master chip is distributed to the at least one slave chip through a Wilkinson power divider, the digital frame synchronization clock in the plurality of cascaded millimeter-wave radar chips is distributed to the at least one slave chip through the master chip and a clock distributor, and the raw ADC data captured by each of the plurality of cascaded millimeter-wave radar chips is transmitted to the data acquisition and processing module in a CSI-2 format;

[0007] The data acquisition and processing module is used to perform multi-dimensional FFT processing on the original ADC data transmitted by the radar RF front-end circuit to obtain a range Doppler image, and to separate and identify the range-velocity spectrum in the range Doppler image through a CFAR algorithm to obtain the peak feature points of each target, and to obtain the distance and speed information of each target around and in the lane based on the peak feature points of each target.

[0008] According to a second aspect of an embodiment of the present application, there is provided a vehicle assisted driving system for use in an underground coal mine, comprising: the millimeter wave radar system described in the first aspect above.

[0009] According to the technical solution of the present application, the present application designs multiple cascaded millimeter-wave radar chips by sampling in the radar RF front-end circuit. The multiple cascaded millimeter-wave radar chips are divided into a master chip and a slave chip. The local oscillator signal generated by the master chip is distributed to the slave chip through a Wilkinson power divider, and the digital frame synchronization clock is distributed to the slave chip through the master chip and the clock distributor. That is, the sharing and distribution of each clock makes the multiple cascaded millimeter-wave radar chips operate in a coordinated manner. The multi-cascade millimeter-wave radar chip of the present application is connected to the data acquisition and processing module through the SPI interface, which is used to receive and configure each millimeter-wave radar chip, and transmit the raw ADC data captured by each chip to the data acquisition and processing module through the CSI-2 format, so that the data acquisition and processing module receives and frames the raw ADC data, and simulates and sets different threshold value domains in the CFAR algorithm according to the tunnel conditions, thereby preventing the special conditions of the tunnel wall from affecting the identification of target personnel, vehicles and equipment, so that the millimeter-wave radar system provided by the present application is more suitable for underground coal mine scenes, and provides more accurate perception data for the auxiliary driving system used in underground coal mines, significantly improving the system's perception ability, all-weather working ability and multi-target detection ability, thereby improving work efficiency and safety.

[0010] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0012] Figure 1 A block diagram of a millimeter wave radar system based on an underground mine tunnel provided in an embodiment of the present application;

[0013] Figure 2 An example diagram of a radar RF front-end circuit in a 4D millimeter-wave radar system provided in an embodiment of the present application;

[0014] Figure 3 A block diagram of a vehicle assisted driving system for use in underground coal mines provided in an embodiment of the present application. DETAILED DESCRIPTION

[0015] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0016] The millimeter wave radar system based on an underground mine tunnel and a vehicle assisted driving system having the same according to an embodiment of the present application are described below with reference to the accompanying drawings.

[0017] Figure 1 This is a block diagram of a millimeter wave radar system based on an underground mine tunnel provided in an embodiment of the present application. Figure 1 As shown, the millimeter wave radar system based on the underground mine tunnel may include but is not limited to: a radar radio frequency front-end circuit 100 and a data acquisition and processing module 200.

[0018] Among them, Figure 1 As shown, the radar RF front-end circuit 100 may include multiple cascaded millimeter-wave radar chips 101, and the multiple cascaded millimeter-wave radar chips 101 are respectively connected to the data acquisition and processing module 200 through a serial peripheral interface (Serial Peripheral Interface, referred to as: SPI), and the multiple cascaded millimeter-wave radar chips 101 can be divided into a master chip and at least one slave chip. The local oscillator signal generated by the master chip can be distributed to at least one slave chip through a Wilkinson power divider, and the digital frame synchronization clock in the multiple cascaded millimeter-wave radar chips 101 can be distributed to at least one slave chip through the master chip and the clock distributor, and the original ADC data captured by each of the multiple cascaded millimeter-wave radar chips 101 can be transmitted to the data acquisition and processing module 200 in CSI-2 (camera interface standard, which can support a variety of pixel formats) format.

[0019] In some embodiments, the master chip in the multiple cascaded millimeter-wave radar chips 101 can be used as a pitch angle transmitting end, and the transmitting antenna of the master chip can be distributed along the longitudinal Y coordinate of the radar. The transmitting antenna of the slave chip in the multiple cascaded millimeter-wave radar chips 101 can be used to improve the horizontal angular resolution of the radar and can be distributed along the lateral X-axis of the radar.

[0020] In some embodiments, the transmitting and receiving antenna arrays of the 4D millimeter wave radar ranging imaging system can be designed with an onboard patch antenna array. Exemplarily, each transmitting and receiving antenna in the transmitting and receiving antenna array can be implemented as a single-channel single-ended GCPW (Grounded Coplanar Waveguide) fed microstrip patch, and the signal routing design of each transmitting and receiving antenna can meet single-ended impedance matching to ensure the complete transmission of the radar RF signal.

[0021] In some embodiments, the radar RF front-end circuit may further include at least one power management chip, the number of the at least one power management chip is associated with the number of multiple cascaded millimeter-wave radar chips, wherein the at least one power management chip can provide power for the multiple cascaded millimeter-wave radar chips.

[0022] In some embodiments, when the power management chip is supplying power to the corresponding millimeter-wave radar chip, if there is a problem with the power supply of the millimeter-wave radar chip, a feedback signal can be sent to the data acquisition processing module. Exemplarily, the power management chip has a feedback mechanism. If there is a problem with the power supply of the millimeter-wave radar chip, the power management chip of the millimeter-wave radar chip will send a feedback signal (also called a power supply feedback signal) to the data acquisition processing module, and the feedback signal is an error signal.

[0023] In some embodiments, each of the multiple cascaded millimeter-wave radar chips may include multiple transmit channels and multiple receive channels, and each transmit channel and each receive channel may form a virtual channel. For example, with 4 millimeter-wave radar chips, a 4-cascade radar system (i.e., a 4D millimeter-wave radar system) is formed, wherein each millimeter-wave radar chip has 3 transmit channels and 4 receive channels, and each transmit and receive will form a virtual channel, so a 4-cascade radar system can be formed to generate a total of 12 transmit and 16 receive radar matrices, equivalent to 192 radar virtual channels.

[0024] The data acquisition and processing module 200 is used to perform multi-dimensional FFT processing on the original ADC data transmitted by the radar RF front-end circuit 100 to obtain a range Doppler image (RDM), and to separate and identify the range-velocity spectrum in the range Doppler image through a CFAR (Constant False-Alarm Rate) algorithm to obtain the peak feature points of each target, and to obtain the distance and velocity information of each target around and in the lane based on the peak feature points of each target.

[0025] In some embodiments, the data acquisition and processing module 200 is used to: perform FFT (Fast Fourier Transform) processing on the original ADC (Analog-to-Digital Converter) data transmitted by the radar RF front-end circuit to obtain distance information; sample the one-dimensional processed data and perform FFT processing on the sampled data to obtain positive and negative values ​​as the velocity value and direction of the target object; perform FFT processing on each virtual channel to obtain a range Doppler image.

[0026] In some embodiments, the data acquisition processing module may include an acquisition processing chip, which can develop and debug the serial peripheral interface and control interface of the radar RF front-end circuit through a PL (Programmable Logic) terminal program to configure the radar's transmission parameters and ADC sampling parameters. Exemplarily, the radar's transmission parameters may include but are not limited to radar pulse adjustment and pulse number, frame number, transmission mode, etc. The ADC's sampling parameters may include but are not limited to sampling time and number of sampling points, etc.

[0027] In order to facilitate those skilled in the art to understand the present application more clearly, Figure 2 A detailed description is given, in which it is assumed that the number of millimeter-wave radar chips 101 is 4, that is, a 4D millimeter-wave radar system is formed by 4 cascaded millimeter-wave radar chips 101.

[0028] For example, the design of the 4D millimeter wave radar system is mainly composed of two parts: hardware module and software module. The hardware part is divided into radar RF front-end circuit and FPGA (Field Programmable Gate Array) data acquisition and processing end. The software end includes debugging radar transmission parameter settings and data acquisition and processing. The data acquisition and processing module in this article can include the data acquisition and processing end and the data acquisition and processing.

[0029] like Figure 2As shown in the figure, the radar RF front-end circuit is designed as follows: the radar RF front-end circuit adopts a four-cascade millimeter-wave radar chip design. The four millimeter-wave radar chips are connected to the data acquisition and processing module through the SPI interface to receive and configure each millimeter-wave radar chip. One of the four millimeter-wave radar chips is the master chip, and the other three are slave chips. The 20GHz local oscillator (between 19GHz and 20.25GHz) generated by the synthesizer of the master chip is distributed to the slave chip through the Wilkinson power divider. The digital frame synchronization clock is also generated by the master chip and distributed to each slave chip through the clock distributor. The 40MH system clock is generated by the crystal oscillator connected to the master chip and redistributed to each slave chip through the master chip and the clock distributor. The sharing and distribution of each clock makes the four cascade millimeter-wave radar chips work in unison. The raw ADC data captured by each millimeter-wave radar chip is transmitted to the data acquisition and processing module in CSI-2 format.

[0030] The radar RF front-end circuit design also includes power input and distribution management design. The power input design meets the intrinsic safety design of coal mine power supply. The voltage distribution and management adopts a suitable PMIC power management chip. One chip can meet the power supply and power-on timing requirements of two radar chips. For example, the input voltage of the power management chip can be 5V, the output power can be 1.8V, or it can be 1.2V, or it can be 1.0V, etc. The power design includes a feedback mechanism. If there is a problem with the millimeter-wave radar chip (or power management chip) powering on, the power supply power-on feedback signal will report an error and be transmitted to the data acquisition and processing module. Each millimeter-wave radar chip has 3 transmitting channels and 4 receiving channels. Each transmission and reception will form a virtual channel, so the 4-cascade millimeter-wave radar system can generate a total of 12 transmissions and 16 receptions of the radar matrix, which is equivalent to 192 radar virtual channels. Among them, the main chip in the 4-cascade millimeter-wave radar chip is used as the pitch angle transmitting end, and the transmitting antenna is distributed along the longitudinal y coordinate of the radar. The transmitting antennas of the other three slave chips are used to improve the horizontal angular resolution of the radar and are distributed along the horizontal x axis of the radar.

[0031] In view of the limitations of the width of underground tunnels, the single repeatability of the tunnel walls, and the slow relative movement speed of personnel and equipment, the radar parameters can be configured as a short-range, high-angle, high-resolution radar, and the radar's transmitting and receiving antenna arrays can be designed with onboard patch antenna arrays. Taking into account the radar's short range, high bandwidth, high gain and other characteristics, this application provides a new type of transmitting antenna array. Each transmitting and receiving antenna is implemented as a single-channel single-ended GCPW-fed microstrip patch, and the signal routing design satisfies single-ended impedance matching to ensure the complete transmission of the radar RF signal.

[0032] Exemplarily, the data acquisition and processing module is designed as follows: the data acquisition and processing end uses the XCZU4EV series as the core chip, and the SPI and control interface of the cascaded RF module are developed and debugged through the PL end program to configure the radar's transmission parameters (such as radar pulse adjustment and pulse number, frame number, transmission mode, etc.) and ADC sampling parameters (such as sampling time and number of sampling points), and receive and frame the CSI-2 radar data transmitted through the high-speed connector. The acquisition module can perform multi-dimensional FFT analysis on the real-time transmitted signal data to obtain the original RDM range Doppler image, and then use the CFAR algorithm to calculate and identify the speed and distance information of multiple targets. At the same time, different threshold value domains are simulated and set in the CFAR algorithm according to the lane conditions, so as to prevent the special conditions of the lane wall from affecting the identification of target personnel, vehicles and equipment.

[0033] The multi-dimensional FFT analysis of radar data by the data acquisition and processing module may include: first-dimensional FFT analysis (range FFT), second-dimensional FFT analysis (speed FFT) and third-dimensional (angle FFT) analysis. Among them, the first-dimensional FFT analysis refers to the FFT of the pulse signal chirp (coded pulse technology) of the radar data. The second-dimensional FFT analysis refers to the FFT analysis of each group of samples, and the positive and negative values ​​generated are the speed value and direction of the target object. The third-dimensional (angle FFT) analysis refers to the FFT analysis of each virtual channel, which can obtain the range Doppler azimuth map. The range-speed map generated after the two-dimensional FFT analysis is subjected to the CFAR algorithm to separate and identify the peak feature points of each target, thereby identifying the specific distance and speed of each target around and in the lane.

[0034] The data acquisition and processing module can have three Gigabit network ports, which can support direct real-time transmission of radar data. After the radar raw data enters the data acquisition and processing module, the data acquisition and processing module can directly receive and frame the radar raw data and upload it to the host computer in real time. The host computer can fuse and uniformly process the millimeter-wave radar data sent by the data acquisition and processing module with the data of other devices such as the laser radar vision camera.

[0035] In the above embodiment, the present application samples multiple cascaded millimeter wave radar chip designs in the radar RF front-end circuit. The multiple cascaded millimeter wave radar chips are divided into a master chip and a slave chip. The local oscillator signal generated by the master chip is distributed to the slave chip through a Wilkinson power divider, and the digital frame synchronization clock is distributed to the slave chip through the master chip and the clock distributor, that is, the multiple cascaded millimeter wave radar chips are operated in a coordinated manner through the sharing and distribution of each clock. The multiple cascaded millimeter wave radar chip of the present application is connected to the data acquisition and processing module through an SPI interface to receive and configure each millimeter wave radar chip, and transmit the original ADC data captured by each to the data acquisition and processing module through the CSI-2 format, so that the data acquisition and processing module receives and frames the original ADC data, and simulates and sets different threshold value domains in the CFAR algorithm according to the roadway conditions, thereby preventing the special conditions of the roadway wall from identifying the target personnel, vehicles and equipment, so that the millimeter wave radar system provided by the present application is more suitable for underground coal mine scenes, and provides more accurate perception data for the auxiliary driving system used in underground coal mines, significantly improving the system's perception ability, all-weather working ability and multi-target detection ability, thereby improving work efficiency and safety.

[0036] Figure 3 This is a block diagram of a vehicle assisted driving system for use in coal mines provided in an embodiment of the present application. Figure 3 As shown, the vehicle assisted driving system may include: a millimeter wave radar system. The millimeter wave radar system may be the above Figure 1 and Figure 2 For the millimeter wave radar system based on underground mine tunnels shown in any of the embodiments, its optional implementation method can be found in the relevant description of any of the above embodiments, which will not be repeated here.

[0037] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0039] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0040] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0041] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A millimeter wave radar system based on underground mine tunnels, characterized in that: include: Radar RF front-end circuit and data acquisition processing module, including: The radar RF front-end circuit includes a plurality of cascaded millimeter-wave radar chips, the plurality of cascaded millimeter-wave radar chips are respectively connected to the data acquisition and processing module through a serial peripheral interface, the plurality of cascaded millimeter-wave radar chips are divided into a master chip and at least one slave chip, the local oscillator signal generated by the master chip is distributed to the at least one slave chip through a Wilkinson power divider, the digital frame synchronization clock in the plurality of cascaded millimeter-wave radar chips is distributed to the at least one slave chip through the master chip and a clock distributor, and the raw ADC data captured by each of the plurality of cascaded millimeter-wave radar chips is transmitted to the data acquisition and processing module in a CSI-2 format; The data acquisition and processing module is used to perform multi-dimensional FFT processing on the original ADC data transmitted by the radar RF front-end circuit to obtain a range Doppler image, and to separate and identify the range-velocity spectrum in the range Doppler image through a CFAR algorithm to obtain the peak feature points of each target, and to obtain the distance and speed information of each target around and in the lane based on the peak feature points of each target.

2. The system according to claim 1, characterized in that The radar RF front-end circuit further includes at least one power management chip, the number of the at least one power management chip is associated with the number of the plurality of cascaded millimeter-wave radar chips, wherein: The at least one power management chip supplies power to the multiple cascaded millimeter-wave radar chips.

3. The system according to claim 2, characterized in that When the power management chip is supplying power to the corresponding millimeter-wave radar chip, if there is a problem with the power supply of the millimeter-wave radar chip, the power management chip sends a feedback signal to the data acquisition and processing module.

4. The system according to claim 1, characterized in that Each of the multiple cascaded millimeter-wave radar chips includes multiple transmitting channels and multiple receiving channels, and each of the transmitting channels and each of the receiving channels can form a virtual channel.

5. The system according to claim 4, characterized in that The data acquisition and processing module is used for: Performing FFT processing on the original ADC data transmitted by the radar RF front-end circuit to obtain distance information; The one-dimensional processed data is sampled, and the sampled data is processed by FFT to obtain the positive and negative values ​​as the velocity value and direction of the target object; Perform FFT processing on each of the virtual channels to obtain the range Doppler image.

6. The system according to claim 1, wherein: The master chip is used as a pitch angle transmitting end, and the transmitting antenna of the master chip is distributed along the longitudinal Y coordinate of the radar. The transmitting antenna of the at least one slave chip is used to improve the horizontal angular resolution of the radar and is distributed along the lateral X axis of the radar.

7. The system according to claim 1, characterized in that The transmitting and receiving antenna arrays of the 4D millimeter wave radar ranging imaging system are designed with onboard patch antenna arrays.

8. The system according to claim 7, characterized in that Each transmitting and receiving antenna in the transmitting and receiving antenna array is implemented as a single-channel single-ended GCPW-fed microstrip patch, and the signal routing design of each transmitting and receiving antenna satisfies single-ended impedance matching.

9. The system according to any one of claims 1 to 8, characterized in that: The data acquisition and processing module includes an acquisition and processing chip, which develops and debugs the serial peripheral interface and control interface of the radar RF front-end circuit through a PL-side program, and is used to configure the radar's transmission parameters and ADC sampling parameters.

10. A vehicle assisted driving system for use in coal mines, characterized in that: include: A millimeter wave radar system as claimed in any one of claims 1 to 9.

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