KR20010070558A - The digital signal procssing System for automobile using Millimeter wave radar - Google Patents

Abstract

PURPOSE: A milli-wave radar signal processing system for a vehicle is provided to sense and process distance and relative velocity to the party vehicle or obstacle in the front or rear of the vehicle. CONSTITUTION: The FMCW(Frequency Modulated Continuous Wave) linear pulse generating circuit(5) generates linear sawtooth wave of the FMCW to the FM transmitter of the milli-wave radar front-end(1). The A/D converter(4) converts the receiving signal from the receiver of the milli-wave radar front-end(1) to digital signal. The pre-processor(9) pre-process the radar signal. The post-processor(7) calculates the distance and relative velocity to the obstacle. The power supply(16) provides the stable power. The vehicle interface device is for interfacing the vehicle. The display device is for reliability and certification to the obstacle.

Description

Millipareda signal processing system for vehicles {The digital signal procssing System for automobile using Millimeter wave radar}

As a technique for implementing a millimeter wave radar, a lot of researches have been conducted using the MMIC (Microwave Monolithic Integrated Circuit) method, but the millimeter wave radar using the MMIC method has a problem of low supply and demand in manufacturing, and is still in mass production. This requires a research and development effort. In addition, when manufacturing a millimeter wave circuit using MMIC, the gate width should be reduced to less than 0.1mm because FET or HEMT, which is a device, should be operated at high frequency.In this case, not only manufacturing difficulty but also durability in manufacturing This weakness (insulation breakdown) is difficult to use. Considering the characteristics of milliwaves with an efficiency of less than 2-3%, the rest is consumed as heat, so it can be seen that the circuit is easily broken. In the case of MMIC, a strip antenna is used, and this antenna also has low efficiency, so that the beam width is difficult to be within 2-3 °, and it is difficult to read obstacles above 100M. have.

Therefore, the present invention has succeeded in wirelessly transmitting and receiving various problems not solved by the conventional MMIC method using the NRD Guide, and invented a technology that can be commercialized and applied to a vehicle by developing a high-performance real-time vehicle signal processing system. It was.

For automotive radars, price / performance and penetration are key issues. Existing systems are highly sensitive to road conditions (muddy water, climate, road conditions) and are too competitive to compete. The development of communication and electronic technology enables the production of such high-performance vehicle radar signal processing systems, and the development of high-performance real-time signal processing systems for price competitiveness and performance improvement by developing automobile radar as NRD guide technology as in the present invention. To solve the above problems.

1 is an overall block diagram of a vehicle millipera system;

2 is a configuration diagram and a flowchart of a vehicle millipareda front end;

3 is a system configuration diagram in a practical situation for a vehicle milliparea;

4 shows modulation characteristics of the FM transmitter of the millimeter wave front end by the FMCW linear pulse generation circuit;

5 (a) shows a triangular wave transmitted and received;

5 (b) shows the bit frequency due to the Doppler effect,

6 is a flowchart for finally measuring the relative speed and the distance to the obstacle from the input digital transmission and reception data.

<Description of the symbols for the main parts of the drawings>

1: Millimeter wave radar front end using NRD Guide

2: vehicle millimeter radar signal processing system designed through the present invention

3: Low Pass Filter to remove noise from signal received by FMCW

4: Part for converting analog signal into digital data

5: FMCW linear pulse generator circuit for continuous linear FM transmission of millimeter wave radar

6: preprocessor for real-time processing of digital signals

7: Post-processing processor for calculating relative velocity, position, and distance to an object

8,9: Preprocessing memory for primary storage of received signals

10,11: post-processing memory

12: Interface circuit for screen output for the final calculated object

13: display device

14: filter for information input and output of the vehicle

15: Vehicle input signal (Speed, Brake, Turn Right / Left)

16: power supply unit for supplying power to the system from the power input (12V, 24V) from the vehicle

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail.

1 is an overall block diagram of a vehicular millimeter wave radar system including a millimeter wave radar signal processing system according to an exemplary embodiment of the present invention.

The present invention is an FMCW linear pulse generation circuit (5) for generating a linear triangle wave of FMCW (Frequency Modulated Continuous Wave) as an FM transmitter of a vehicle millimeter wave radar front end (1) and millimeter wave radar front end, and millimeter wave radar front end. A / D convertor (3,4) for converting digitally received signal from receiver of preprocessing unit, preprocessor (6,8,9) in charge of preprocessing of radar signal, calculate distance and relative speed for obstacle A post-processing unit (7, 10, 11) for performing an operation or algorithm to perform, the vehicle interface unit (14, 15) for the interface with the vehicle, the power supply unit 16 for supplying a stable system power from the power input from the vehicle, and the final Consists of the display unit 12, 13 for checking the reliability and the result of the obstacle.

In addition, the preprocessor consists of a preprocessor 6 and preprocessor memories 8, 9, and the post processor consists of a post processor 7 and post processor memories 10, 11.

The vehicle millimeter wave radar front end (1, Fig. 2) is fitted with a circulator installed so that the output from the FM gunn oscillator using a gunn diode is protected from reflected waves that do not require the gunn oscillator, and radiated from the antenna. In addition, part of the output of the FM Gunn oscillator is inserted into the mixer together with the directional coupler and sent as a Lo wave to the mixer, with the reflected wave at the target received from the antenna. The beat signal obtained by mixing is amplified with an IF amplifier. The frequency of this beat signal is measured to find the distance and relative speed.

In the FMCW millimeter wave radar signal processing system, the FMCW linear pulse generator 5 can modulate a continuous transmission wave (generally adjusted to a triangular wave) and simultaneously measure the relative speed and distance of the target from the reflected wave from the target. It is to be. Specifically, since the frequency modulation is performed using 77 GHz as the center frequency, the linearity of the circuit generating triangular waves is important. Therefore, the present invention uses the most linear and stable section when FM modulation through offset, amplitude, frequency control using a 12-bit digital to analog converter or waveform generator. Fig. 4 shows FM modulation characteristics through the FM transmitter of the millimeter fader front end through the FMCW linear pulse generation circuit.

In the A / D convertor (3, 4), the IF signal (beat signal) input from the millimeter wave radar front end is a signal including a high frequency component (noise). Therefore, after removing the noise through the low pass filter 3, the analog signal is 12 bits. to digital At this time, the pulse generating circuit synchronizes with the point of time when the signal output starts.

The preprocessing unit has a memory control function of FIFO (First in First out) structure for real-time processing of input digital data, control management of A / D convertor and FMCW pulse generator circuit, interface with the post-processing processor, and peripherals for final result output. Functions as a circuit control and turns into a gate.

In the present invention, the post-processing unit adopts a Hitachi RISC CPU as a DSP core CPU. The radar signal received through the memory searches for a peak point of the signal through FFT (Fast Fourier Transform) processing. Will be.

The distance from the object and the relative speed are calculated from the number of detected obstacles and the frequency. Of course, it is important to remove the cutter to set the appropriate threshold for this signal processing.

Frequency modulation with triangular wave (repetition frequency) Modulation width ), The reflected wave changes from the target moving at the distance R and the relative speed v as shown by the dotted line in Fig. 5A. At this time, the bit frequency obtained by mixing the transmission wave and the reflected wave becomes as shown in FIG. 5 (b) by the Doppler effect. In the period where the transmission frequency increases, At the decreasing interval Say , Is expressed as

From here,

: Doppler frequency,

c: luminous flux

: Center frequency of transmission wave. At this time, beat frequency , The sum and the difference can be obtained to find the distance R to the target and the relative speed v.

When the radar and target are stationary together (ie v = 0), the beat frequency = = The distance R becomes as follows.

The display unit is composed of a display interface circuit 12 and a display device 13, and the obstacles extracted through the post-processing process 7 are corrected for the triangular wave after comparison and analysis with the front camera for verification of accuracy and results. It plays a role of improving accuracy through distance correction.

The interface for display is controlled by IIC communication using a decoder and encoder for video.

The vehicle interface units 14 and 15 need to report the driving state of the vehicle in order to develop a reliable radar that operates for preventing the collision of the vehicle. In other words, through the input of TRNL / R (Turn Left / Right) signal, Speed signal, Brake signal, etc., it analyzes the possibility of collision and the driving status with the vehicle in front, and then alarms or controls the driving vehicle.

The power supply unit 16 has a specificity of a vehicle, so the power supply source must be input from the vehicle. In other words, 24V for commercial vehicles and 12V for passenger cars should be input to supply the power (12V, 5V, 3.3V) used in the signal processing board to the system. In particular, care should be taken in ripple rejection by using carriers for the milli-wave band, which have a fairly high frequency in the milli-radar front end.

6 is a flowchart for finally measuring the relative speed and the distance to the obstacle from the input digital transmission and reception data.

The invention of the high performance real-time signal processing board for obstacles using the millimeter wave FMCW radar front end of about 10mW developed using the NRD guide has been described above. The FMCW method is a relatively widely used method because it can measure obstacles of multi targets and can measure the relative speed of each obstacle.

The radar was able to measure an object of about 150M distance (car), and within 50M, it was able to measure a person's degree and measure a small obstacle. The FM modulation width was about 100MHz, and the measurement accuracy was about 0.7M.

The invented millimeter wave radar signal processing board is considered to have high performance, small size, simple circuit and, above all, reproducibility and sufficient performance as a radar for preventing collision of automobiles.

In the future, it will be completed as a hybrid sensor for obstacle detection, collision prediction, and auto-crusing.

Specifically, since the radar for a vehicle according to the present invention is a sensor for accurately measuring the distance, relative speed, and position of an object, safety for a hybrid vehicle that can operate in conjunction with a lane departure warning device and an obstacle recognition device using an image sensor. Will develop the device. In addition, the vehicle safety devices and systems (sensors) are closely related to human safety, and after sufficient field tests, they plan to optimize the algorithms and specifications according to the situation. In addition, it can be applied to various fields as it can be applied to the defense and aerospace industry.

Claims (16)

Received signal from the receiver of the millimeter radar front end (1), the FMCW linear pulse generator (5) for generating the linear triangle wave to the FM transmitter of the millimeter radar front end, as shown in the representative diagram. A / D convertor (3,4) for converting to digital, preprocessor (6,8,9) for preprocessing radar signal, perform calculation or algorithm to calculate distance and relative velocity for obstacle Post-processing unit (7, 10, 11), the vehicle interface unit 14, 15 for the interface with the vehicle, the power supply unit 16 for supplying a stable system power from the power input from the vehicle, and the reliability and results for the final obstacle Vehicle radar device and method characterized in that provided and configured with a display (12, 13) for confirmation. The method according to claim 1, wherein the preprocessor consists of a preprocessor 6 and preprocessor memories 8, 9, and the post processor consists of a post processor 7 and post processor memories 10,11. Configuration and method for the radar device. The method according to claim 2, wherein the pre-processing unit is a memory control function of the FIFO structure for real-time processing of the input digital data, control management of the A / D convertor and FMCW pulse generation circuit, interface with the post-processing processor, peripheral for outputting the final result It is characterized in that it performs a function such as circuit control, and the post-processing unit searches the peak point of the signal through the FFT processing of the radar signal entering through the memory, the distance to the object, the relative number through the data such as the number of obstacles, frequency Radar apparatus and methods using methods of calculating speed. The vehicle millimeter wave radar front end (1, Fig. 2) is fitted with a circulator installed because the output from the FM gunn oscillator using a gunn diode is protected from reflected waves that do not require the gunn oscillator, A part of the output of the FM Gunn oscillator is inserted into the mixer as a Lo wave by inserting a directional coupler and input to the mixer together with the reflected wave from the target received from the antenna, the radar device characterized in that the amplified by the IF amplifier and the method . The FMCW linear pulse generating circuit (5) according to claim 1, wherein the FMCW linear pulse generating circuit (5) performs frequency modulation (generally adjusted to a triangular wave) on a continuous transmission wave and simultaneously measures the relative speed and distance of the target in the reflected wave from the target. Radar apparatus and its method, characterized in that. The FMCW linear pulse according to claim 5, which uses an offset, amplitude, and frequency control by using a digital to analog convertor or a waveform generator in order to construct a linear circuit by generating continuous triangular waves because frequency modulation is performed using the center frequency. Generating circuits and constructions, and radar devices and methods thereof using such circuits. According to claim 1, In the A / D convertor (3, 4) the IF signal (beat signal) input from the millimeter wave radar front end is a signal containing a high frequency component (noise), so through the low pass filter (3) A radar device and method, comprising the analog to digital conversion after the noise is removed. The radar device or the radar signal processing device and method according to claim 7, wherein the operation start time and the synchronization of the preprocessing and post-processing units are synchronized with the start time of the signal output in the pulse generating circuit. The method according to claim 1, wherein the preprocessing unit is a memory control function of the first in first out (FIFO) structure for real-time processing of the input digital data, control management of the A / D convertor and FMCW pulse generation circuit, an interface with the post-processing processor, A signal processing device, a radar device using the same, and a method thereof, comprising: a peripheral circuit control function for outputting a final result. The radar device according to claim 1, wherein the post-processing unit detects an obstacle by searching the peak point of the signal in the spectrum and data distribution through the FFT (Fast Fourier Transform) process. And the method. The radar apparatus or the signal processing apparatus according to claim 10, further comprising extracting final information through a calculation (Equation 1) in order to finally measure the relative speed and distance to the obstacle. . The display unit of claim 1, wherein the display unit includes a display interface circuit 12 and a display device 13, and the obstacles extracted through the post-processing process 7 are compared with the front camera for verification of accuracy and results. Radar apparatus and method comprising a portion having a role of improving the accuracy through the correction of the triangular wave or the distance after the analysis. The radar device and method according to claim 12, further comprising a display interface circuit comprising a video decoder and an encoder for controlling and communicating with IIC communication. A radar device and a sensor for a vehicle according to claim 1, characterized in that it comprises a vehicle interface unit (14, 15) for producing a reliable device. The method of claim 14, wherein the vehicle interface unit through the input of the TRNL / R (Turn Left / Right) signal, Speed signal, Brake signal, etc. After analyzing the possibility of collision and the driving state with the vehicle in front of the alarm for the driving vehicle or Radar apparatus and method for performing the control. According to claim 1, the power supply unit 16 has a special characteristic of the vehicle, the power supply source is used in the radar signal processing board (24V, 3.3V, 3.3V for commercial vehicles, 12V, 5V, 3.3) And a method for supplying the system to the system.