JPH04236388A - Radar system for motorcar - Google Patents

Abstract

PURPOSE:To receive and recognize correctly the reflected waves of only radar waves transmitted from one' s own motorcar and prevent the obstruction detection mistaken, by drawing an exact line between radar waves from one' s own motorcar and radar waves from the other motorcar. CONSTITUTION:A radar wave generating element to generate the radar waves for detecting an obstruction is constituted so as to be possible to generate plural frequencies different each other. Therewith, ID signals to recognize being the radar waves from one' s own motorcar are piled up to the said radar waves transmitted. Where the radar waves received by the discrimination making the said ID signals a reference are the radar waves of the other motorcar with the same frequency number as it of one' s own motorcar, the false detection by the input of the radar waves of the other motorcar is prevented by changing the frequency of the radar waves from the said radar wave generating element to the other frequency.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile radar system equipped with an obstacle detection function.

0002

2. Description of the Related Art For example, as disclosed in Japanese Unexamined Patent Application Publication No. 58-131575, two sets of ultrasonic waves latched and input via a latching means are used to detect obstacles such as a preceding vehicle while the vehicle is running. Only when the received wave outputs of reflected waves such as sound waves match each other, the received wave outputs are determined to be correct obstacle detection outputs and an alarm is generated, thereby preventing false detection due to external noise. Obstacle detection systems for automobiles are well known in the art.

Regarding the use of such an obstacle detection system for automobiles, recently, for example, laser waves are used as radar waves instead of the above-mentioned ultrasonic waves, and the distance between the vehicle and the vehicle in front is detected from the reflection time of the waves, and the By comparing the actual following distance with the limit distance corresponding to the vehicle speed, if the actual following distance is smaller than the above-mentioned limit following distance, the system notifies the driver of this situation with a warning lamp etc. to encourage safe driving. Automobile inter-vehicle distance control devices that enable this are being developed.

0004

[Problem to be solved by the invention] However, when the above-mentioned inter-vehicle distance detection system is adopted, if another vehicle traveling in the opposite lane has radar waves of the same frequency as the own vehicle, In this case, it is impossible to distinguish whether the received radar waves are reflected waves from the own vehicle or directly transmitted from the oncoming vehicle, making it impossible to accurately detect the distance between vehicles. There's a problem.

Therefore, in order to solve this problem, for example, the above-mentioned radar waves are circularly polarized, and the radar waves of the own vehicle are distinguished from those of other vehicles by the difference in the rotation direction of the circularly polarized radar waves. Although it is possible to adopt a system, this system requires an expensive polarizer, resulting in an extremely high cost.

[0006]

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above problems and providing a radar system for detecting obstacles with high detection accuracy and low cost. A radar wave generating means for generating radar waves for detecting obstacles; a radar wave transmitting means for transmitting the radar waves generated by the radar wave generating means toward the front of the vehicle; and a radar wave transmitted by the radar wave transmitting means. In an automobile radar system comprising a reflected wave receiving means for receiving reflected waves from wave obstacles, the radar wave generating means is configured to generate radar waves capable of oscillating radar waves of a plurality of frequencies having mutually different frequency values. an oscillating means, an ID signal generating means for generating an ID signal for recognizing an own vehicle transmitted wave having a frequency different from a frequency of a radar wave oscillated by the radar wave oscillating means, and an ID signal of the ID signal generating means; It is determined whether the received radar waves are those of the own vehicle or another vehicle based on the frequency of the radar waves transmitted from the other vehicle, and the frequency of the radar waves transmitted from the other vehicle is currently transmitted from the radar wave transmitting means of the own vehicle. The present invention is characterized by further comprising oscillation frequency switching means for switching the oscillation frequency of the radar wave oscillated by the radar wave oscillation means to another oscillation frequency when the frequency is equal to the frequency of the radar wave.

[0007]

[Operation] As described above, in the automobile radar system of the present invention, the radar wave generating means for generating radar waves for detecting an obstacle, for example, a vehicle traveling in front of the own vehicle as an obstacle, is mutually connected. The radar wave oscillation means is configured by a radar wave oscillation means capable of generating a plurality of frequencies with different frequency values, and an ID signal generation means is provided, and the radar wave transmitted from the radar wave transmission means is a radar wave transmitted from the own vehicle. An ID signal for recognizing the vehicle is superimposed, and if the received radar wave is determined based on the ID signal as a radar wave of another vehicle with the same frequency as that of the own vehicle, the radar wave is transmitted from the radar wave transmitting means. By changing the frequency of the radar wave for detecting an obstacle to another frequency, the sensor prevents the detection due to reception of another vehicle's radar wave.

[0008]

Therefore, according to the automotive radar system of the present invention, it is possible to always accurately detect obstacles without being affected by radar waves of other vehicles, and even when configured as an inter-vehicle distance control system, it is possible to detect obstacles in the opposite lane. By eliminating the influence of radar waves from oncoming vehicles, it is possible to create a highly reliable control system that is free from malfunctions.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 5 show an automobile radar system according to an embodiment of the present invention.

First, FIG. 1 shows the configuration of the radar system. In the figure, reference numeral 1 indicates a modulated wave for forming a plurality of laser radar waves (hereinafter simply referred to as radar waves) having mutually different frequency values. It is a modulated wave oscillator that oscillates. The modulated wave oscillator 1 is composed of, for example, a voltage-controlled variable frequency oscillator (VCO), and in a steady state, the power supply voltage +B input from the power supply terminal T1 is converted by the first voltage converter 2. A modulated wave having a first oscillation frequency f1 corresponding to the first control voltage value V1 is oscillated, while when a control voltage switching signal is supplied from the ID signal discriminator 19 described later, the first control voltage is A second oscillation frequency f according to a second control voltage value V2 different from V1
It is designed to oscillate two modulated waves.

The modulated wave output of the modulated wave oscillator 1 is then supplied to the radar carrier wave oscillator 3, where it is modulated by multiplying the radar carrier wave by the modulated wave of the first or second oscillation frequency f1 or f2, and the modulated wave is modulated. The radar waves of the first and second frequencies f1 and f2 are supplied to a directional coupler (waveguide) 6 for transmission via an isolator 5. The directional coupler 6 receives an ID signal modulated by the ID signal carrier oscillator 8 based on the oscillation frequency f3 of the ID signal oscillator 7, which is different from the first and second frequencies f1 and f2. The ID signal is superimposed on the radar wave to form a radar wave for detecting an obstacle, and the radar wave is sent to the vehicle via the millimeter wave transmitting antenna 9, for example, as shown in FIGS. 3 to 5. X (or Y)
Transmit toward the front.

[0012] The radar waves are originally intended to be emitted toward the rear of a vehicle traveling in front of the own vehicle, and the reflected waves that hit the rear of the vehicle in front are detected by the receiver described below. The distance between the vehicle and the vehicle in front and the relative speed are measured based on the delay time (Doppler shift) from the time of transmission of the received wave. Further, the ID signal is unique for distinguishing and identifying the radar waves of the own vehicle transmitted as described above from the radar waves of other vehicles.

That is, reference numeral 11 is a receiving antenna for millimeter waves that inputs the reflected wave of the radar wave transmitted as described above that hits the vehicle in front (obstacle) and is reflected. After the reflected wave signal inputted through the second directional coupler (waveguide) 12 is separated into an ID signal and a radar wave, the ID signal is sent to a demodulator 18, are supplied to the isolator 13, respectively.

The radar wave signal supplied to the isolator 13 is further frequency-converted into the above-mentioned modulation frequency signals by a frequency converter 14, and then passes through a bandpass filter 15 having a predetermined filter constant to pick up signals of only a predetermined frequency. and is supplied to the inter-vehicle distance (relative speed) detector 16. The inter-vehicle distance detector 16 forms an inter-vehicle distance detection signal based on the signal picked up by the band-pass filter 15, amplifies the signal to a predetermined level via an amplifier 17, and sends the signal to a terminal as sensing information (inter-vehicle distance information). The signal is inputted to a predetermined determination circuit via T2, and the actual inter-vehicle distance is compared with the limit inter-vehicle distance, a warning, etc. is performed, and the driver is notified.

On the other hand, the ID signal supplied to the demodulator 18 and demodulated is input to an ID signal discriminator 19, where the ID signals of the own vehicle and the other vehicle are discriminated.

As a result of ID signal discrimination by the ID signal discriminator 19, if the received radar wave ID signal is the own vehicle's radar wave ID signal, it is determined that the vehicle in front (obstacle) is correctly identified.
The first voltage converter 2 determines that the wave is a reflected wave from
By supplying the vehicle determination output only to the second voltage converter 20 without supplying a control voltage switching signal to the frequency f1 of the radar wave transmitted by the vehicle, the filter constant of the bandpass filter 15 is determined by A bandpass signal of the same frequency is supplied to the inter-vehicle distance detector 16 as described above. The inter-vehicle distance detector 16 detects the transmission signal f(t) and the transmission signal f(t), as shown in FIG.
Received signal (reflected wave signal) delayed by a predetermined time (τ)
f(t-τ) From the mutual frequency versus time relationship, (b
), the beat frequencies fb1 and fb2 are generated, and the inter-vehicle distance is detected based on the beat frequencies fb1 and fb2.

[0017] By the way, as mentioned above, the radar waves that are radiated and transmitted in the direction in front of the own vehicle However, for example, if the road in question curves in an S-shape as shown in Figure 3, the light will be radiated in the direction of the opposite lane. Moreover, in the case where there is an opposing vehicle Y in this state as shown in FIG. 4, both the mutually opposing vehicles channel), it is necessary to distinguish it from its own radar waves.

[0018] This distinction is made by the ID included in the radar wave mentioned above.
This will be done based on the signal.

That is, when the ID signal is different from the radar wave of the own vehicle as described above, the ID signal discriminator 19 sends a control voltage switching signal to the first voltage converter 2. The oscillation control voltage of the modulated wave oscillator 1 is switched from the first control voltage value V1 to the second control voltage value V2, and the oscillation frequency of the modulated wave oscillator 1 is changed to the first oscillation frequency f1. (A channel) to 2nd
The signal is switched to the oscillation frequency f2 (B channel) and transmitted toward the vehicle in front in the same way as in the case described above. As a result, the frequency of the radar wave transmitted from the transmitting antenna 9 becomes the second frequency f2 (B channel). Therefore, the receiving frequency will eventually be different from the frequency f1 (A channel) of the other vehicle, and the following distance can be accurately detected without being affected by the radar waves of the other vehicle in the above-mentioned post-reception processing. , it is now possible to guarantee a highly accurate inter-vehicle distance detection function.

After the above detection, when vehicles X and Y pass each other and the situation is as shown in FIG. 5, the original frequency f1 (
A channel).

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an automobile radar system according to an embodiment of the present invention.

FIG. 2 is a time chart showing the principle of inter-vehicle distance measurement of the automobile radar system according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a first operational mode showing the operation of the automobile radar system according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a second operational mode showing the operation of the automobile radar system according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram of a third operational mode showing the operation of the automobile radar system according to the embodiment of the present invention.

[Explanation of symbols]

1 is a modulated wave oscillator, 2 is a first voltage converter, 3 is a radar carrier wave oscillator, 6 is a first directional coupler, 7 is an ID signal oscillator, 8 is an ID signal carrier wave oscillator, 9 is a transmitting antenna, 11 is a receiving antenna, 12 is a second directional coupler, 1
5 is a band pass filter, 16 is an inter-vehicle distance detector, 19
is an ID signal discriminator, and 20 is a second voltage converter.

Claims (1)

[Claims] 1. Radar wave generating means for generating radar waves for detecting obstacles; radar wave transmitting means for transmitting the radar waves generated by the radar wave generating means toward the front of the vehicle;
A vehicle radar system comprising a reflected wave receiving means for receiving a reflected wave from an obstacle of the radar wave transmitted by the radar wave transmitting means, wherein the radar wave generating means includes a plurality of radar wave generating means having mutually different frequency values. It is constituted by a radar wave oscillation means capable of oscillating a radar wave of a frequency,
An ID signal generating means for generating an ID signal for recognizing a self-vehicle transmitted wave having a frequency different from the frequency of the radar wave oscillated by the radar wave oscillating means, and a radar wave received based on the ID signal of the ID signal generating means. The frequency of the radar wave transmitted from the other vehicle is equal to the frequency of the radar wave currently transmitted from the radar wave transmitting means of the own vehicle. 1. A radar system for an automobile, wherein the radar system for an automobile is further provided with an oscillation frequency switching means for switching the oscillation frequency of the radar wave oscillated by the radar wave oscillation means to another oscillation frequency.