Radar sensor for distance and speed induction triggering

Abstract

The utility model relates to a radar sensor for sensing and triggering distance and speed, which belongs to the technical field of radar sensors and comprises an MMIC (Monolithic Microwave Integrated Circuit) which comprises a receiver, a VCO (Voltage Controlled Oscillator), a transmitter, a temperature sensor and a frequency divider, a receiving antenna array, wherein the receiving antenna array is connected with the receiver; a transmitting antenna array, wherein the transmitting antenna array is connected with the transmitter; an MCU, wherein the MCU comprises an ADC and a DAC; the amplifier group is communicated with the receiver and the ADC; the voltage follower is communicated with the VCO and the DAC (Digital-to-Analog Converter); the frequency discriminator and the amplifier are communicated, the frequency discriminator is communicated with the frequency divider, and the amplifier is communicated with the ADC; and the crystal oscillator is connected with the MCU.

Description

Technical Field

[0001] This utility model relates to the field of radar sensor technology, and in particular to a radar sensor for distance and speed sensing triggering. Background Technology

[0002] A distance-velocity sensing-triggered low-cost radar sensor is a sensor that uses microwave signals to measure distance and velocity. It utilizes the time delay and frequency variation of radar echo signals to measure the distance and velocity of a target object. The principle behind this technology is to transmit microwave signals to the target object via an antenna and receive the returned echo signals. By calculating the signal's time delay and frequency variation, the distance and velocity information of the target object can be obtained.

[0003] Specifically, the sensor transmits high-frequency microwave signals through an antenna and receives the echo signals reflected back from the target object. Using time difference measurement technology, the round-trip time of the signal can be calculated, thus determining the distance to the target object. Simultaneously, as the target object moves along the scanning direction of the sensor antenna, the frequency of the echo signal changes; the Doppler effect can be used to further determine the target object's velocity. Furthermore, low-cost radar sensors employ several technical optimizations, such as using multiple modulation methods to improve signal stability and robustness, and using digital signal processing and filtering algorithms for signal preprocessing and analysis to enhance measurement accuracy and reliability.

[0004] Besides the technical principles and optimization measures mentioned above, there are other factors to consider. One important factor is antenna design. Antenna design directly affects the sensor's sensitivity and resolution, therefore it needs to be optimized according to the specific application scenario. Furthermore, low-cost radar sensors also need to consider the balance between cost and reliability. The lower the cost of the sensor, the wider its applicability, but measurement accuracy and reliability cannot be sacrificed, especially in scenarios requiring high-precision measurements.

[0005] Currently, low-cost radar sensors have been applied in many fields, such as smart homes, intelligent transportation, and robot navigation. These sensors enable not only accurate distance and speed measurements but also target object detection and classification. In the future, with continuous technological advancements, low-cost radar sensors will become more widespread and mature.

[0006] Millimeter-wave radar operates in the millimeter-wave band. Millimeter waves typically refer to the 30–300 GHz frequency band (wavelength 1–10 mm). Since the wavelength of millimeter waves falls between centimeter waves and light waves, they combine the advantages of microwave guidance and photoelectric guidance. Compared to centimeter-wave seekers, millimeter-wave seekers are smaller, lighter, and have higher spatial resolution. Compared to infrared, laser, and television optical seekers, millimeter-wave seekers have stronger penetration capabilities through fog, smoke, and dust, and are all-weather (except in heavy rain) and all-time. Furthermore, millimeter-wave seekers have superior anti-jamming and anti-stealth capabilities compared to other microwave seekers.

[0007] Millimeter-wave radar mainly consists of three parts: radar radio frequency front-end, signal processing system, and back-end algorithm. In existing products, patent licensing fees for radar back-end algorithms account for approximately 50% of the cost, radio frequency front-end accounts for approximately 40%, and signal processing system accounts for approximately 10%.

[0008] The radio frequency (RF) front-end transmits and receives millimeter waves to obtain intermediate frequency (IF) signals, from which information such as range and velocity is extracted. Therefore, the RF front-end directly determines the performance of the radar system. The signal processing system is also a crucial component of radar, extracting specific target information from the IF signals acquired by the RF front-end by embedding different signal processing algorithms. Back-end algorithms account for the highest proportion of the overall cost of millimeter-wave radar. For millimeter-wave radar, domestic researchers have proposed numerous algorithms from multiple perspectives, including frequency domain, time domain, and time-frequency analysis, achieving high accuracy in offline experiments. However, domestic radar products mainly use frequency domain-based Fast Fourier Transform (FFT) and its improved algorithms for analysis, which has limitations in measurement accuracy and applicability. Foreign algorithms, on the other hand, are strictly protected by patents and are very expensive.

[0009] Existing ultrasonic radar technology suffers from at least the following drawbacks: its transmission speed varies under different weather conditions such as snow and rain, and is relatively slow; it has a large scattering angle and poor directionality, resulting in weak echo signals when measuring distant targets, which affects measurement accuracy; and when multiple ultrasonic radars are located in the same area, mutual interference may occur. Millimeter-wave radar, on the other hand, is moderately priced, effectively overcomes the challenges of harsh environments, and does not suffer from mutual interference issues. Utility Model Content

[0010] In order to overcome the above-mentioned defects of the prior art, the present invention provides a radar sensor for distance and speed sensing triggering, so as to solve the problems mentioned in the background art.

[0011] To achieve the aforementioned objectives, this utility model provides a radar sensor for distance and velocity sensing triggering, comprising:

[0012] MMIC, which includes a receiver, VCO, transmitter, temperature sensor and frequency divider;

[0013] A receiving antenna array, wherein the receiving antenna array is connected to the receiver;

[0014] A transmitting antenna array, which is connected to the transmitter;

[0015] MCU, the MCU including ADC and DAC;

[0016] An amplifier group, wherein the amplifier group is connected to the receiver and the ADC;

[0017] A voltage follower, wherein the voltage follower is connected to the VCO and the DAC;

[0018] A frequency discriminator and an amplifier are connected, the frequency discriminator is connected to the frequency divider, and the amplifier is connected to the ADC;

[0019] A crystal oscillator, which is connected to the MCU.

[0020] Furthermore, the voltage follower includes a GS321-TR chip.

[0021] Furthermore, the amplifier group includes a GS358 chip.

[0022] Furthermore, the sensor is made of RO4350B ceramic material with a thickness of 0.508mm, and its surface is tin-plated and treated with anti-oxidation.

[0023] Furthermore, the transmitting antenna array and the receiving antenna array adopt a dual-element structure, wherein the first element and the second element are symmetrically placed close to each other on both sides of the MMIC, and both adopt an insert-fed rectangular microstrip antenna.

[0024] Furthermore, the ports of the transmitting antenna array and the receiving antenna array are CPWG coplanar waveguide structures.

[0025] Compared with the prior art, the beneficial effects of this utility model are:

[0026] 1. This invention optimizes antenna layout, merges main and side lobes, and optimizes impedance continuity to ensure impedance matching, which can provide at least a 2-fold increase in sensitivity and a 1.5-fold increase in detection range.

[0027] 2. This invention integrates the front-end and back-end into one unit, optimizing the circuit board layout and resulting in lower power consumption and smaller size;

[0028] 3. The 24GHz millimeter-wave radar sensor proposed in this invention uses the ISM band near 24GHz, which can be used globally without any radio regulatory obstacles. Compared with lasers and ultrasound, 24GHz millimeter waves are less affected by adverse conditions such as fog, rain, snow, and dust. They have excellent wave transmission properties for materials such as nylon, plastic, glass, and ceramics, making them very suitable for installation in sealed nylon plastic housings or inside ceramic tiles.

[0029] 4. This system measures flow rate in a non-contact manner. It has a stable and reliable structure, is less affected by the external environment, has low cost, long service life, is suitable for promotion and popularization in various scenarios, and has low maintenance costs.

[0030] 5. The front-end module and the back-end module are connected by BGA (Ball Grid Array) welding, which simplifies the welding process and enables automated welding.

[0031] 6. By optimizing the backend module, the problem of insufficient resolution of the millimeter-wave radar module was improved;

[0032] 7. By making full use of the PCB board area, the MCU can be offered in two different packages, giving users more choices;

[0033] 8. The dual-element design greatly reduces the physical area of ​​the invention, significantly lowering the cost. Attached Figure Description

[0034] Figure 1 This is a block diagram of the circuit board structure of the millimeter-wave radar device according to an embodiment of the present invention;

[0035] Figure 2 This is a circuit diagram of the analog switch group and filter amplifier group circuit of the millimeter-wave radar device according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the front-end module and amplifier circuit of the millimeter-wave radar device according to an embodiment of this utility model;

[0037] Figure 4 This is a partial circuit schematic diagram of the MCU of the millimeter-wave radar device according to an embodiment of this utility model;

[0038] Figure 5 This is a schematic diagram of the layout of the front end of the millimeter-wave radar device according to an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the antenna array of a millimeter-wave radar device according to an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the utility model, not all embodiments. The embodiments of this utility model are described below with reference to the accompanying drawings.

[0041] refer to Figure 1 , Figure 3 The main body of the invention is a single circuit board, including a receiving antenna array 1, a receiver 2, a VCO 3, a transmitter 4, a transmitting antenna array 5, a frequency divider 7, a temperature sensor 6, an amplifier group 8, a voltage follower 9, a frequency discriminator 10, an amplifier 11, an MCU 15, and a crystal oscillator 14.

[0042] In the main circuit board, the front-end module and the back-end module are connected by BGA soldering.

[0043] The secondary intermediate frequency gain function and the adaptive long-distance and short-distance ranging function are implemented by MMIC 16, MCU 15, amplifier group 8, and analog switch group;

[0044] refer to Figure 2 , Figure 4 After the echo signal is amplified by the first stage of the front-end module, it is simultaneously sent to the PB1 pin of the MCU and the second stage amplifier by the output pin IFI_AMP of the front-end module. The first stage amplified echo signal sent to the second stage amplifier is first sent to the first analog switch IC6, which is then split into two paths and connected in series with capacitors of different capacitance values ​​before being sent to the NO and NC pins of the first analog switch respectively. The PA4 pin of MCU15 controls the output port COM of the first analog switch to connect to the NO or NC port. The output echo signal is sent to the -IN pin of the second stage amplifier IC5-GS358. After the echo signal is amplified, it is output by the OUT pin of the second stage amplifier IC5-GS358 chip and sent to MCU15. The second stage amplified echo signal sent to MCU15 is filtered by C13 and then sent to the PA0 pin of MCU15.

[0045] refer to Figure 2 , Figure 4After the echo signal is amplified by the first stage of the front-end module, it is simultaneously sent to the PA7 pin of the MCU and the second stage amplifier by the output pin IFQ_AMP of the front-end module. The first stage amplified echo signal sent to the second stage amplifier is first sent to the second analog switch IC7, which is then split into two paths and connected in series with capacitors of different capacitance values ​​before being sent to the NO and NC pins of the second analog switch respectively. The PA4 pin of MCU 15 controls the output port COM of the second analog switch to connect to the NO or NC port. The output echo signal is sent to the -IN pin of the second stage amplifier IC5-GS358. After the echo signal is amplified, it is output by the OUT pin of the second stage amplifier IC5-GS358 chip and sent to MCU 15. The second stage amplified echo signal sent to MCU 15 is filtered by C13 and then sent to the PA3 pin of MCU 15.

[0046] The PA7, PB1, PA0, and PA3 pins of MCU 15 receive the first-stage amplified echo signal and the second-stage amplified echo signal, respectively. Each pin can simultaneously receive signals for FMCW or CW mode. Based on the echo signal received by the pin, it determines whether intermediate frequency gain is needed, makes a judgment, selects the appropriate echo amplification signal, and automatically performs long-distance and short-distance ranging.

[0047] The CW / FMCW dual operating mode switching function is implemented by MCU 15 and analog switch group;

[0048] The echo signals of the first analog switch IC6 are connected in series with capacitors of different capacitance values ​​and then sent to the NO and NC pins of the first analog switch IC201 respectively. The MCU 15 sends a control signal to the IN pin of the GS4157 chip through the PA4 pin to control the output port COM of the first analog switch to connect to the NO or NC port. When the NO port is connected, it is filtered by capacitor C26 and then sent to the input terminal of IC5 in the secondary amplifier. When the NC port is connected, it is filtered by capacitor C28 and then sent to the input terminal of IC5 in the secondary amplifier.

[0049] The echo signals of the first analog switch IC6 are connected in series with capacitors of different capacitance values ​​and then sent to the NO and NC pins of the first analog switch IC6 respectively. The MCU 15 sends a control signal to the IN pin of the GS4157 chip through the PA4 pin to control the output port COM of the first analog switch to connect to the NO or NC port. When the NO port is connected, it is filtered by capacitor C26 and then sent to the input of IC5 in the secondary amplifier. When the NC port is connected, it is filtered by capacitor C27 and then sent to the input of IC5 in the secondary amplifier.

[0050] The echo signal of the second analog switch IC7 is connected in series with capacitors of different capacitance values ​​and then sent to the NO and NC pins of the second analog switch IC7 respectively. The MCU 15 sends a control signal to the IN pin of the GS4157 chip through the PA4 pin to control the output port COM of the first analog switch to connect to the NO or NC port. When the NO port is connected, it is filtered by capacitor C28 and then sent to the input of IC5 in the secondary amplifier. When the NC port is connected, it is filtered by capacitor C29 and then sent to the input of IC5 in the secondary amplifier.

[0051] The linear modulation frequency calibration function is implemented by MCU 24, MMIC 16, frequency discriminator 10, and amplifier 11;

[0052] MCU 15 sends a modulated voltage signal to the VTUNE pin of MMIC 16 via the PB1 pin. MMIC 16 generates a frequency based on the given modulated voltage signal. After being divided by frequency divider 7 within MMIC 16, the frequency signal is output from the DIV pin to low-pass filter 10, then to the input of amplifier 11 (including the GS321 chip), and finally to MCU 15. The divided signal output from the frequency divider passes through a frequency discriminator. Based on the amplitude-frequency characteristics of the discriminator, different frequency signals will have different output amplitudes. Based on the signal amplitude acquired by the AD converter, the frequency of the signal output by the frequency divider can be determined, thereby correcting the output frequency. MCU 15 compares the actual received frequency signal with the frequency that the modulated voltage can generate, thus achieving linear modulation frequency calibration. In CW mode, this function only requires calibration at one point; in FMCW mode, it performs frequency linear calibration.

[0053] refer to Figure 2 The VOUT port of the GS321 chip in the voltage follower 9IC4 outputs voltage to the VTUNE pin of the MMIC 16;

[0054] refer to Figure 5 The transmitting antenna array 5 and the receiving antenna array 1 are distributed on both sides of the MMIC 16. Pins 19 and 20 are located at the center of the long side of the sensor. The amplifier 21 is located in the MMIC 16, between the pin 19 on one side and between the transmitting antenna array 5 and the receiving antenna array 1.

[0055] refer to Figure 6The transmitting antenna 5 and receiving antenna 1 of the 24GHz millimeter-wave radar sensor of the present invention are a dual-element hybrid feeding structure, wherein two radiating patches 22 and radiating patches 23 are fed uniformly with equal amplitude and phase. The feeding point of each element has a certain insertion depth to match the transmission line impedance. The circular dipole and the side-fed array elements have better standing wave characteristics and wider bandwidth. The horizontal and vertical spacing of the two array elements are reasonably optimized in the sensor, so that the side lobes and the main lobe are merged. Compared with similar products on the market, the influence of the side lobes is eliminated. The ports of the transmitting antenna array 5 and the receiving antenna array 1 are CPWG coplanar waveguide structures, which also achieve higher isolation.

[0056] The 24GHz millimeter-wave radar sensor described in this invention generates a single-frequency signal within a certain range around 24GHz via a VCO 3. The frequency of this single-frequency signal can be controlled by the user's modulation voltage, and the user can also detect the frequency divider output to determine this frequency. A portion of the energy from the high-frequency signal generated by the voltage-controlled oscillator is radiated into space through a power amplifier and transmitting antenna, while the remaining energy is provided to the receiver as a local oscillator signal. When the electromagnetic wave encounters a target during its propagation through the air, a small portion is reflected. The reflected echo signal is intercepted by the receiving antenna to form an electrical signal. The receiver continuously outputs the difference in frequency and phase between the local oscillator signal and the echo signal as a beat signal. After passing through a filter and amplifier, the beat signal is processed by the user. By analyzing the frequency and phase of the beat signal, information such as the position and velocity of the target in space can be determined.

[0057] refer to Figure 5 The transmitting antenna array 5 transmits an FMCW wave, whose frequency changes according to a triangular wave pattern over time. The frequency of the echo received by the radar follows the same triangular wave pattern as the transmitted frequency, but with a time difference. After performing FFT (Fast Fourier Transform) processing on the intermediate frequency signal using MCU 24, the distance to the target can be accurately obtained by analyzing the frequency difference signal on the power spectrum. All objects reflecting electromagnetic waves will be reflected in the power spectrum. By tracking the change of each frequency value, the object's speed and motion state can be determined. After further performing two-dimensional FFT processing on the intermediate frequency signal, the object's azimuth angle can be further determined by tracking the phase difference of the frequency values.

[0058] The technical solution of this utility model has been described above with reference to specific embodiments. However, it should be noted that the above description is only for explaining the solution of this utility model and should not be construed as a specific limitation on the scope of protection of the utility model in any way. Based on this explanation, other specific embodiments or equivalent substitutions of this utility model that can be conceived by those skilled in the art without creative effort will all fall within the scope of protection of this utility model.

Claims

1. A radar sensor for distance speed induced triggering, characterized in that include: MMIC (16), the MMIC (16) includes a receiver (2), a VCO (3), a transmitter (4), a temperature sensor (6), and a frequency divider (7); A receiving antenna array (1) is connected to the receiver (2); A transmitting antenna array (5) is connected to the transmitter (4); MCU (15), wherein the MCU (15) includes ADC (12) and DAC (13); Amplifier group (8), the amplifier group (8) being connected to the receiver (2) and the ADC (12); A voltage follower (9) is connected to the VCO (3) and the DAC (13); A frequency discriminator (10) and an amplifier (11) are connected, the frequency discriminator (10) is connected to the frequency divider (7), and the amplifier (11) is connected to the ADC (12); Crystal oscillator (14), which is connected to the MCU (15).

2. Radar sensor for distance speed induced triggering according to claim 1, characterized in that The voltage follower (9) includes a GS321-TR chip.

3. The radar sensor for distance and velocity sensing triggering according to claim 1, characterized in that, The amplifier group (8) includes a GS358 chip.

4. The radar sensor for distance speed induced triggering of claim 1, wherein, The sensor is made of RO4350B ceramic material with a thickness of 0.508mm, and its surface is tin-plated and treated with anti-oxidation.

5. The radar sensor for distance and velocity sensing triggering according to claim 1, characterized in that, The transmitting antenna array (5) and receiving antenna array (1) adopt a dual-element structure, wherein the first element (22) and the second element (23) are symmetrically placed close to each other on both sides of the MMIC (16), and both adopt an insert-fed rectangular microstrip antenna.

6. The radar sensor for distance and velocity sensing triggering according to claim 1, characterized in that, The ports (24) of the transmitting antenna array (5) and the receiving antenna array (1) are CPWG coplanar waveguide structures.

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