CN203535221U - Vehicular millimeter wave anticollision radar system - Google Patents

Abstract

The utility model provides a vehicle-mounted millimeter-wave anti-collision radar system, which includes a transceiver antenna device, a transmitting circuit module, a receiving circuit module, a DSP module, a RAM for data buffering, a Flash memory, a clock module and a power supply module; wherein the receiving circuit module Contains 4 receiving channels, each channel includes filter circuit, amplifier circuit and A/D conversion module; the input terminal of the receiving module is connected to the transceiver antenna device, and the output terminal is connected to the DSP module; the transmitting circuit module includes a D/A conversion module and amplifying circuit; the A/D conversion module is an A/D conversion module with synchronous serial output, and the synchronous serial output port is connected to the 4-way synchronous serial input interface of the DSP module. A low-cost synchronous serial output AD conversion module is used, and 4 synchronous serial input interfaces are constructed by using the limited input and output pins on the DSP module to realize synchronous sampling of 4 signals. This reduces the cost of hardware and reduces the size of the circuit board.

Description

Vehicle millimeter wave anti-collision radar system

technical field

The utility model relates to a vehicle-mounted millimeter wave anti-collision radar system, which belongs to the field of active safety control of automobiles.

Background technique

With the rapid development of my country's automobile industry, traffic accidents occur frequently. The car anti-collision system can monitor the road environment in real time, assist the driver to make correct handling in emergency situations, and prevent car collision accidents. At present, automobile collision avoidance technologies mainly include ultrasonic, laser, infrared and radar. Considering factors such as detection distance, identification ability, penetration, stability and cost, radar technology has shown certain advantages. Therefore, the research on vehicle anti-collision radar has become the main research direction in the field of automobile anti-collision technology. Since millimeter-wave radar has a series of advantages such as no ranging blind zone, low transmitter power, high resolution, and low cost, automotive anti-collision radars widely use the linear frequency modulated continuous wave (LFMCW) system.

In recent years, the United States, Japan and Germany have made some achievements in the field of vehicle collision avoidance radar, and have successfully developed LFWCM vehicle collision avoidance radar with multiple frequencies. my country's research on vehicle driving environment perception and recognition systems is relatively late, and domestic research institutions are relatively scattered, so domestic automotive radar research is still in the development and exploration stage.

On the basis of the above problems, the applicant has developed a frequency-domain constant false alarm detection method for the vehicle-mounted millimeter-wave anti-collision radar system, which can effectively reduce the false alarm rate detected by the anti-collision radar system and enhance the real-time performance of the system. sex and effectiveness. The specific literature reference is the relevant patent document with the application number: 201210169343.1 and the title of the invention: "Frequency Domain Constant False Alarm Detection Method for Vehicle-mounted Millimeter-Wave Anti-collision Radar System", which discloses a vehicle-mounted millimeter-wave anti-collision radar system. A constant false alarm detection method in the frequency domain. The millimeter wave anti-collision radar system adopted in the method includes a DSP module, a transmitting circuit module, a receiving circuit module, and a transceiver antenna device. The DSP module is also connected to a RAM and a clock module. The DSP module transmits The circuit module controls the transceiver antenna device to emit frequency-modulated continuous waves. When there is a target in front of the anti-collision radar system, the transceiver antenna device receives the echo signal and outputs it as four analog signals, and the receiving circuit module processes the four analog signals. sent to the DSP module for processing. The receiving circuit module mainly completes the receiving and processing of the time-domain difference-frequency signal. Traditional automotive radar has two methods for receiving and processing the time-domain difference-frequency signal: one is to select a DSP with a multi-channel A/D conversion unit. The module samples and processes the signal, but because the DSP module performs sequential A/D conversion on the signal, to achieve synchronous sampling of the signal, the requirements for the DSP module are very high, resulting in the high cost of the automotive radar. Based on this technology, the other is to use a low-cost DSP module without an AD conversion unit, and use an external AD conversion module with a parallel interface to perform AD conversion on the time domain difference frequency signal. If four 12bit sampling precision AD The conversion module is connected to the DSP module in parallel, which requires the DSP module to have rich input and output pin resources, and this type of chip also has strong signal processing capabilities, and the cost is often high. Therefore, the mainstream DSP module TMS320VC5502 of TI Company with lower price is chosen. This chip has rich signal processing capability, but the peripheral input and output pin resources are very few. If the AD conversion module with parallel interface is used in the periphery, the external memory interface of the chip can only be used to expand the external hardware through the external latch and drive chip, which will cause the increase of hardware cost and the increase of circuit board size. The circuit board size of automotive radar is often strictly limited, and the smaller the size, the better.

Contents of the invention

The purpose of this utility model is to provide a vehicle-mounted millimeter-wave anti-collision radar system, which adopts a low-cost synchronous serial output AD conversion module, uses the limited input and output pins on the DSP module to construct 4 synchronous serial input interfaces, and realizes 4 synchronous serial input interfaces. Synchronous sampling of the signal. This reduces the cost of hardware and reduces the size of the circuit board.

Technical solutions

The vehicle-mounted millimeter-wave anti-collision radar system includes a transceiver antenna device, a transmitting circuit module, a receiving circuit module, a DSP module, a data buffer RAM, a Flash memory, a clock module and a power supply module; the output terminal of the transmitting circuit module is connected to the input of the transmitting and receiving antenna device terminal, the control terminal of the DSP module is connected to the input terminal of the transmitting circuit module, the output terminal of the transceiver antenna device is connected to the input terminal of the receiving circuit module, and the output terminal of the receiving circuit module is connected to the input terminal of the DSP module, and the DSP The output terminals of the module are respectively connected to the control terminals of the data cache RAM, Flash memory, clock module and power module. The receiving circuit module includes 4 receiving channels, each channel includes a filter circuit, an amplifier circuit and an A/D conversion module; the transmitting circuit module Including a D/A conversion module and an amplifying circuit; the A/D conversion module is an A/D conversion module with synchronous serial output, and the input end of the DSP module includes 4 synchronous serial input interfaces, and the A/D The synchronous serial output port of the D conversion module is connected to the 4-way synchronous serial input interface of the DSP module.

As a further optimization solution of the present invention, the A/D conversion module is a dual-channel A/D conversion module with a serial interface.

As a further optimization scheme of the present invention, the op-amp device of the transmitting circuit module adopts the low-noise op-amp chip AD8651 of ADI Company; the op-amp device of the receiving circuit module adopts the low-noise op-amp chip AD8652 of ADI Company.

As a further optimization scheme of the present invention, the main chip of the A/D conversion module of the receiving circuit module is 12 chip AD7866 of ADI Company; the main chip of the D/A conversion module of the transmitting circuit module is 12 chip AD5320 of ADI Company .

As a further optimization scheme of the present invention, the main chip of the DSP module adopts the TMS5000 series chip TMS320VC5502 of TI Company.

Beneficial effect

The millimeter wave anti-collision radar system provided by the utility model is simple, small in size, low in cost and easy to install. The receiving circuit adopts an AD conversion module with a dual-channel serial interface to achieve synchronous sampling of 4-way signals.

Description of drawings

Fig. 1 is a structural schematic diagram of a 24GHz vehicle-mounted millimeter-wave anti-collision radar system of the present invention.

specific implementation plan

Below in conjunction with accompanying drawing, technical scheme of the present utility model is described in further detail:

As shown in Figure 1, a 24GHz vehicle-mounted millimeter-wave anti-collision radar system includes a transceiver antenna device for transmitting and receiving FM continuous waves, a transmitting circuit module for generating the required modulation waveform, and a transmitting circuit module for receiving A receiving circuit module for front-end signal processing, a DSP module for digital signal processing, a RAM for data buffering and a Flash memory for storing programs, a clock module for providing a reference clock for the DSP module, a A power module used to provide power to various parts of the system. The receiving circuit module includes 4 receiving channels, and each channel is composed of an amplification, filter circuit, and A/D conversion module; the transmitting circuit module is composed of a D/A conversion module and an amplification circuit.

When the radar is working, the DSP module generates a frequency-sweeping voltage digital signal, and an analog voltage value is generated by the D/A and the operational amplifier circuit to control the voltage-controlled oscillator of the antenna, and a linear frequency-modulated continuous wave whose modulation waveform is a symmetrical triangular wave is generated. The start frequency and stop frequency can be programmed. Part of the FM continuous wave is transmitted through the transmitting antenna, and part of it is divided into 4 channels I1, Q1, I2, and Q2 to be coupled to the mixer as local oscillator signals. The signals in the channels of Q1 and Q2 are obtained after the original signal is shifted by 90 degrees.

The transmitted signal is reflected by the target and received by two receiving antennas. Each antenna divides the received echoes into two groups, that is, the antenna RX1 puts the received echoes into I1 and Q1 channels, and the echoes received by RX2 into I2, Q2 channel. After the echo signal is amplified and processed by low noise, it is mixed with the existing 4 signals by the mixer to obtain the difference frequency signal. The difference frequency signal obtained after frequency mixing is processed by intermediate frequency filtering, and finally output to the receiving circuit module in the form of four intermediate frequency analog signals through the transceiver antenna device.

The receiving circuit module mainly completes the receiving and processing of the time-domain difference-frequency signal. Traditional automotive radars have two methods for receiving and processing the time-domain difference-frequency signal: one is to select a DSP module with multiple A/D conversion units for The signal is sampled and processed, but because the DSP module internally performs sequential A/D conversion on the signal, to achieve synchronous sampling of the signal, the requirements for the DSP module are very high, resulting in the high cost of the automotive radar. The other is to use a low-cost DSP module without an AD conversion unit, and use an external AD conversion module with a parallel interface to perform AD conversion on the time-domain difference frequency signal. If four 12bit sampling precision AD conversion modules are connected in parallel Into the DSP module, which requires the DSP module to have rich input and output pin resources, and this kind of chip has strong signal processing capability at the same time, and the cost is often high. Therefore, the mainstream DSP module TMS320VC5502 of TI Company with lower price is chosen. This chip has rich signal processing capability, but the peripheral input and output pin resources are very few. If the AD conversion module with parallel interface is used in the periphery, the external memory interface of the chip can only be used to expand the external hardware through the external latch and drive chip, which will cause the increase of hardware cost and the increase of circuit board size. However, the circuit board size of automotive radar is often strictly limited, and the smaller the size, the better. Therefore, it is conceived to use a low-cost synchronous serial output AD conversion module, and use the limited input and output pins on the DSP module to build 4 synchronous Serial input interface to realize synchronous sampling of 4 signals. This reduces the cost of hardware and reduces the size of the circuit board.

The receiving circuit module amplifies, filters, and A/D converts the 4-way intermediate frequency signals to generate digital signals and sends them to the DSP module for digital signal processing. In the receiving circuit module, a dual-channel AD conversion module with a serial interface is used. Only two AD conversion modules are required to convert, and the synchronous sampling of the 4-channel signal required by the system is achieved. On the basis of reducing costs, it greatly saves DSP module pin resources.

In order to obtain the parameter information of the target, it is necessary to analyze the spectrum of the difference frequency signal in the upswing and downswings of the FM respectively. For the specific processing method, please refer to the patent application document with the patent application number: 201210169343.1. The digital signal processing process is as follows: the DSP module first divides the sampled digital signal into a frequency rising section and a falling section and latches them into the RAM respectively. After the data is latched, use the DSP module to perform Fast Fourier Transform (FFT) on the latched data to obtain the frequency spectrum of the difference frequency signal. The frequency point corresponding to the spectrum peak is detected by the spectrum peak search algorithm and the corresponding phase is measured, and then the constant false alarm processing (CFAR) is performed on the generated peak frequency point. CFAR is actually a kind of adaptive threshold detection, which uses the reference window samples adjacent to the front and rear of the unit under test to estimate the parameters of the environmental noise. This estimated value can adjust the judgment threshold in real time to achieve the purpose of constant false alarm detection. Since each peak frequency point may be the corresponding spectral line of the target echo, or may be clutter interference, the target spectral line can be effectively detected under the premise of effectively controlling the false alarm rate after using this method. At this time, theoretically, there will only be spectral lines corresponding to the target in the spectrum. However, due to the interference of background clutter and receiver thermal noise in the actual working environment of the radar, when the signal-to-noise ratio drops to a certain level, the CFAR-processed There will still be false alarm targets in the spectrum. At this time, the clutter cancellation process is performed on the signal. The clutter cancellation method, as the name implies, is to remove the spectral lines with the same frequency value as the spectral lines in the rising and falling sections of FM. In order to avoid the situation of removing the spectral line of the moving target by mistake, fully consider whether the amplitude spectral values are equal when performing clutter cancellation. If the frequency and amplitude spectra are equal, the spectral line is removed; if one of the two is not equal, the spectral line is retained. In addition, the influence of spectrum jitter must be considered, and a certain error space must be reserved when clutter is canceled. Using clutter cancellation can effectively remove the stationary target and the clutter generated by the target.

To overcome the problem of the presence of false targets due to lack of correlation, a spectral pairing procedure is performed. Finally, the distance, speed and phase angle information of the target are calculated according to the frequency and phase of the spectral lines corresponding to the target in the upswing and downslopes of FM.

The above-mentioned transceiver antenna device includes a transmitting antenna and two receiving antennas, and adopts the comprehensive radar sensor IVQ-905 of Innosent Company;

The attenuation circuit in the transmitting circuit module attenuates the frequency-sweeping voltage signal after D/A conversion to generate a small-amplitude analog signal. The op-amp device adopts ADI's low-noise op-amp chip AD8651;

The op amp device in the receiving circuit module adopts ADI's low-noise op amp chip AD8652;

The main chip of the A/D conversion module is the 12-bit chip AD7866 of ADI Company;

The main chip of the D/A conversion module is the 12-bit chip AD5320 of ADI Company

The main chip of the DSP module adopts the TMS5000 series chip TMS320VC5502 of TI Company;

External expansion RAM memory adopts 256K*16bit chip IS61LV25616 of ISSI company;

The externally expanded Flash memory adopts AMD's 4-megabit chip Am29LV400B.

The above embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto. All equivalents or improvements made within the disclosure scope of the utility model all fall within the protection scope of the utility model.

Claims (5)

1. Vehicle-mounted millimeter-wave anti-collision radar system, including transceiver antenna device, transmitting circuit module, receiving circuit module, DSP module, data buffer RAM, Flash memory, clock module and power supply module; the output terminal of the transmitting circuit module is connected to the transmitting and receiving antenna device The input terminal of the DSP module is connected to the input terminal of the transmitting circuit module, the output terminal of the transceiver antenna device is connected to the input terminal of the receiving circuit module, and the output terminal of the receiving circuit module is connected to the input terminal of the DSP module, so Said DSP module output end is respectively connected to the control end of data cache RAM, Flash memory, clock module and power supply module, and receiving circuit module includes 4 receiving channels, and each channel includes filtering circuit, amplifying circuit and A/D conversion module; The circuit module includes a D/A conversion module and an amplifying circuit; it is characterized in that: the A/D conversion module is an A/D conversion module with synchronous serial output, and the input end of the DSP module includes 4 synchronous serial inputs The synchronous serial output port of the A/D conversion module is connected to the 4 synchronous serial input ports of the DSP module. 2. The vehicle-mounted millimeter-wave anti-collision radar system according to claim 1, wherein the A/D conversion module is a dual-channel A/D conversion module with a serial interface. 3. The vehicle-mounted millimeter-wave anti-collision radar system according to claim 1 or 2, characterized in that: the operational amplifier of the transmitting circuit module adopts the low-noise operational amplifier chip AD8651 of ADI Company; the operational amplifier of the receiving circuit module adopts ADI The company's low-noise operational amplifier chip AD8652. 4. vehicle-mounted millimeter-wave anti-collision radar system according to claim 1 is characterized in that: the main chip of the A/D conversion module of receiving circuit module is 12 chip AD7866 of ADI Company; The D/A conversion of transmitting circuit module The main chip of the module is the 12-bit chip AD5320 of ADI Company. 5. The vehicle-mounted millimeter-wave anti-collision radar system according to claim 1, characterized in that: the main chip of the DSP module adopts the TMS5000 series chip TMS320VC5502 of TI Company.

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