JPH06258429A - Forward security radar system for vehicle - Google Patents

Abstract

PURPOSE:To enable quick detection of interrupting vehicle, etc., by preparing a plurality of obstruction detecting systems and controlling the receiving signals for every obstruction detecting systems. CONSTITUTION:First, a control calculator 51 gives an instruction to a phase controller 44 to control the output azimuth of a pseudo noise(PN) generator 43 and is shifted to the increasing control for the output azimuth phase of the generator 43. Then, when the accumulated value of the output from a demodulator 32 reaches the specified threshold, the calculator 51 judges that there is any obstruction in the front and outputs the output of obstruction detection to a display, etc. When any obstruction is detected in the obstruction detecting system related to the generator 33, the calculator 51 regulates the output phase of a generator 43 to be zero and the accumulated value of the output from the demodulator 42 is compared with the threshold. Thus, in the state where any obstruction is detected by the system related to the generator 33 while a plurality of obstruction detecting systems are provided, the monitoring/detecting of interrupting vehicles, etc., is performed by the system related to the generator 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile forward warning radar device for detecting an obstacle existing in front of an automobile, and more particularly to a pseudo noise (PN) code modulation type radar device.

[0002]

2. Description of the Related Art As a forward warning radar device for automobiles,
Besides the FM-CW radar device, a PN code modulation type radar device has been developed. In the PN code modulation type radar device, a PN code which is a code string of a predetermined length is generated, and the carrier wave is phase-modulated by the generated PN code. The obtained phase modulated wave is transmitted to the front of the vehicle from, for example, a transmitting antenna provided at the front of the vehicle. When an obstacle such as another vehicle exists in front of the vehicle, the transmitted phase modulated wave is reflected by the obstacle. The reflected phase-modulated wave is received by the receiving antenna that is placed side by side with the transmitting antenna or shared with the transmitting antenna.

When the reflected wave is received, the reflected wave and the receiving P
The correlation of N codes is calculated. Here, the reflected wave is delayed from the transmitted wave by a time corresponding to the round trip distance between the vehicle and the obstacle. Therefore, by controlling the phase of the receiving PN code, which is the same code string as the PN code (transmission PN code) used at the time of transmission, the presence of the obstacle and its distance can be detected. That is, when the correlation between the reflected wave and the reception PN code is maximized, the distance corresponding to the phase difference between the transmission PN code and the reception PN code at that time (the distance obtained by multiplying the phase difference by c / 2: c Can be considered to be the presence of an obstacle. Once the presence of an obstacle is detected, this obstacle is usually tracked.

[0004]

However, after an obstacle appears at a certain distance, another obstacle (for example, an interruption vehicle) may appear at a distance shorter than the obstacle. When alerting the appearance of such an obstacle, it is necessary to interrupt the tracking operation of the obstacle currently being executed and then execute the obstacle detection operation again. However, such a tracking interruption
Since the measurement data regarding the obstacle is interrupted, it is inconvenient for the calculation or the like for determining the presence or absence of danger such as a collision. In addition, it is difficult to quickly detect the occurrence of an interruption vehicle or the like.

The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to quickly detect an interrupting vehicle without interrupting the operation of tracking an obstacle. To do.

[0006]

In order to achieve such an object, a forward warning radar device for an automobile according to the present invention generates a PN code for transmission which is a code string having a predetermined length, and transmits this PN code. A phase difference between a transmission system that modulates a carrier wave with a PN code and transmits a phase-modulated wave to the front of the mounted vehicle, a receiving unit that receives a reflected wave of the phase-modulated wave from an obstacle, and a PN code for transmission. Is controlled to gradually increase or decrease so that it falls within a predetermined range, a receiving PN code that is the same code string as the transmitting PN code is generated, and the correlation between the received reflected wave and the receiving PN code is calculated. If the correlation exceeds a predetermined value, it is determined that there is an obstacle at a distance corresponding to the phase difference between the transmitting PN code and the receiving PN code, and a plurality of obstacles such as a vehicle ahead are detected. Obstacle detection system and above The obstacle detection operation is executed by any one of the obstacle detection systems, and if an obstacle is detected by this operation, the detection operation of another obstacle at a closer distance is detected by another obstacle. Control means for controlling the control range of the reception PN code for each obstacle detection system so that the system is executed.

[0007]

In the vehicle forward warning radar device of the present invention, first, a transmission PN code, which is a code string having a predetermined length, is generated, and a carrier wave is modulated by this transmission PN code. The obtained phase-modulated wave is transmitted in front of the mounted vehicle.

When there is an obstacle ahead, the transmitted phase modulated wave is reflected by the obstacle. The receiving means receives the reflected wave. In each obstacle detection system, the correlation between the received reflected wave and the reception PN code is calculated.
The phase of the reception PN code, which is the same code string as the transmission PN code, is gradually increased or decreased so that the phase difference from the transmission PN code falls within a predetermined range. If the correlation exceeds a predetermined value, it is determined that an obstacle exists at a distance corresponding to the phase difference between the transmission PN code and the reception PN code. Thereby, an obstacle such as a vehicle ahead is detected.

In the present invention, such an obstacle detection operation is executed in a relay manner by a plurality of obstacle detection systems. For example, when there are two obstacle detection systems, the first and second systems, the control means first sets the phase control range of the reception PN code in the first system according to the code length of the transmission PN code, for example. And the obstacle detection operation is executed. If an obstacle is detected by the first system,
The control means starts the obstacle detection operation by the second system. At this time, the phase control range of the receiving PN code in the second system is set by the control means so that only other obstacles located closer than the obstacle detected by the first system are detected. It

By controlling the obstacle detection system as described above,
When an obstacle such as an interruption vehicle occurs, it can be detected quickly. At that time, there is no need to interrupt the operation of the system that has already detected the obstacle.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of a forward warning radar system for an automobile according to an embodiment of the present invention. The radar device shown in this figure first includes a PN generator 11, a transmitter 12, and a transmitting antenna 13 as a transmission system. The PN generator 11 generates a PN code, which is a code string of a predetermined length, and supplies this to the transmitter 12. Transmitter 12
Uses a transmission PN code supplied from the PN generator 11 to phase-modulate a carrier wave and transmits the carrier wave in front of the vehicle via the transmission antenna 13.

The radar system shown in this figure includes a receiving antenna 21 and a receiver 22 as a receiving system. The receiving antenna 21 receives the reflected wave coming from the front of the vehicle, and the receiver 22 performs processing such as amplification on the reflected wave. The output of the receiver 22 is supplied to the product calculators 31 and 41.

The apparatus shown in this figure has two obstacle detection systems. The first system is composed of a product calculator 31, a demodulator 32, a PN generator 33 and a phase controller 34. The second system is the product calculator 41 and the demodulator 4
2, a PN generator 43 and a phase controller 44.

The PN generators 33 and 43 generate the receiving PN code under the control of the phase controller 34 or 44, respectively. The reception PN code is the same code string as the transmission PN code generated by the PN generator 11, and its phase, that is, the output phase of the PN generators 33 and 43, is based on the phase of the transmission PN code. , Phase controller 3
4 or 44. Phase controllers 34 and 44
Is P in accordance with the phase information supplied from the control calculator 51.
It controls the output phase of the N generators 33 and 43. Therefore,
Under the control calculator 51, by the phase controllers 34 and 44,
The phase of the receiving PN code will be controlled.

The product calculators 31 and 41 are both receivers 22.
A signal related to the reflected wave is input from the corresponding PN generator 3
The product with the receiving PN code supplied from 3 or 43 is calculated. Each of the demodulators 32 and 42 demodulates the output of the corresponding product calculator 31 or 41 and supplies the result to the control calculator 51. The control calculator 51 includes the phase controller 34.
While controlling the phase of the PN code for reception via 44 and 44, the outputs of the demodulators 32 and 42 are input, and the presence of an obstacle in front and the distance thereof are detected based on these.
The control calculator 51 supplies the presence or absence of an obstacle as an obstacle detection output and the distance as a distance output to, for example, a display device or the like.

FIG. 2 shows the content of the operation of detecting the distance to the obstacle in this embodiment.

First, as shown in FIG. 2A, PN
The transmission PN code generated by the generator 11 is a code string that repeats with a certain time t _e as an epoch. PN
The generator 11 continuously generates the PN code for transmission with such an epoch t _e . The transmission signal transmitted from the transmitter 12 via the transmission antenna 13 is thus a signal phase-modulated by the epoch t _e .

When such a transmission signal is transmitted ahead of the vehicle and reflected by an obstacle, the reception signal received by the receiving antenna 21 and amplified by the receiver 22 is, for example, as shown in FIG. 2 (b). It becomes a signal. As shown in this figure, the reception signal is a signal delayed from the transmission signal by the time (radio wave propagation time) t _d required for the radio waves to travel back and forth between the vehicle and the obstacle.

The phase of the PN code for reception generated by the PN generator 33 or 43 is, as described above, based on the phase of the PN code for transmission generated by the PN generator 11, the phase controller 34 or 44. It is controlled by the control calculator 51 via. For example, the output phase of the PN generator 33 or 43 is controlled so that the phase difference from the PN code for transmission gradually increases from 0 to reach the epoch t _e . As a result of this control, the receiving PN output from the PN generator 33 or 43.
When the phase of the code coincides with the radio wave propagation time t _d as shown in FIG. 2C, the correlation value obtained by the control calculator 51 increases.

That is, in the product calculator 31 or 41, the received signal shown in FIG.
Or 43, the product of the receiving PN code is obtained, and the demodulator 32 or 42 demodulates this. The control calculator 51 calculates the correlation value between the reception signal and the reception PN code by accumulating the output of the demodulator 32 or 42 for a predetermined time, for example, an integral multiple of the epoch. Figure 2 (c)
As shown in, when the phase of the receiving PN code matches the phase of the received signal, the accumulated value (correlation value) obtained by the control calculator 51 increases and exceeds the threshold value at a certain point. . In other words, as shown in FIG. 2E, when the phase of the receiving PN code matches the radio wave propagation time t _d , the correlation value significantly increases. Control calculator 5
1 detects the presence of an obstacle by judging the correlation value with a threshold value, and at the same time, the phase of the receiving PN code at the time when the correlation value exceeds the threshold value, that is, the radio wave propagation time t _d is c. Multiply by / 2 to detect the distance to the obstacle.

The first feature of the present embodiment is that an obstacle detection system that executes such an operation is operated as shown in FIG.
The point is that the system will be established. The second feature of this embodiment is that the operation of each system is controlled so that an interrupting vehicle can be detected quickly. FIG. 3 shows the content of this control, that is, the flow of operation of the control calculator 51.

As shown in this figure, the control calculator 51
First, the output phase t _d2 of the PN generator 43 is epoch t
Set to the same value as _e (100). That is, by giving a command to the phase controller 44, the output phase of the PN generator 43 is controlled to t _e .

The control calculator 51 performs such step 1
After executing 00, the control shifts to the gradual increase control of the output phase t _d1 of the output phase 33 of the PN generator 33. That is, by giving a command to the phase controller 34, the output phase t _d1 of the PN generator 33 is controlled to 0 (102), and then the output phase t _d1 of the PN generator 33 is gradually increased by Δ (104). .
When step 104 is repeatedly executed, the PN generator 3
The output phase t _{d1 of} 3 gradually increases by Δ from the state of t _d1 = 0 (that is, the phase difference from the transmission PN code is 0), and reaches the output phase t _d2 of the PN generator 43 at a certain point (10
6). When the condition of step 106 is satisfied, the control calculator 51 returns to step 102 and returns the output phase t _d1 of the PN generator 33 to the initial value.

While the condition of step 106 is not satisfied, the routine proceeds from step 104 to step 106 and then to step 108. In step 108, the control calculator 51 determines whether the accumulated value of the output of the demodulator 32 has reached a predetermined threshold value. If this condition is not established, it can be considered that no obstacle has been captured by the system related to the PN generator 33, so the process returns to step 104, and the output phase t _d1 of the PN generator 33 is gradually increased. . If the condition of step 108 is satisfied, the control calculator 51 considers that an obstacle exists ahead,
An obstacle detection output indicating that an obstacle is present and a distance output indicating the distance of the obstacle are output to a display or the like in the subsequent stage (110). The distance calculation in step 110 is executed by multiplying the output phase t _d1 of the PN generator 33 by c / 2, as described above.

When an obstacle is detected by the obstacle detection system related to the PN generator 33 in this way, the control calculator 51
Controls the output phase t _d2 of the PN generator 43 to 0 (1
12). That is, a command is given to the phase controller 44, and PN
The output phase t _d2 of the generator 43 is controlled so that the phase of the reception PN code is the same as the phase of the transmission PN code. Control calculator 51
After making such a setting,
The same operation as 110 to 110 is executed (114 to 120).
However, the control target in steps 114 to 120 is
It is different from the control target in steps 104 to 110. That is, in step 114, the output phase t _d of the PN generator 43 is gradually increased by Δ, and step 11
In 6, the determination related to the condition of t _d2 ≧ t _d1 is executed,
In step 118, the accumulated value of the output of demodulator 42 is compared to a threshold value.

As described above, by executing steps 112 to 120 after executing step 110, the PN generator 3
The presence of an obstacle at a distance closer than the distance corresponding to the output phase t _{d1 of} 3, such as an interrupting vehicle, will be monitored and detected by the obstacle detection system related to the PN generator 43. After execution of step 120, the process returns to step 102.

Therefore, according to the present embodiment, a plurality of obstacle detection systems are provided, and the PN generator 43 is provided when the obstacles are detected by the system related to the PN generator 33.
Monitoring and detection of interrupt vehicles etc. by the system related to
In a state where an obstacle is detected by the system related to the generator 43, the system related to the PN generator 33 monitors and detects an obstacle at a shorter distance. Since the interrupt vehicle is monitored by another system without interrupting the operation of, the interrupted vehicle and other obstacles can be detected quickly while avoiding the interruption of the measurement data related to the obstacle currently being detected. It becomes possible. As a result, it is possible to prevent problems such as missing data required for determining the risk of collision, etc., and to speed up the calculation, which makes it possible to further improve the safety of traveling of the vehicle. Become.

In the above description, the transmitting antenna 13 and the receiving antenna 21 are separate bodies, but they can be shared by using a circulator or the like. Further, the demodulators 32 and 42 may be Costas demodulators or the like.

[0030]

As described above, according to the vehicle forward warning radar device of the present invention, when an obstacle is detected by a certain obstacle detection system, an obstacle detection operation by another obstacle detection system is performed. Since the phase control range of the latter receiving PN code at that time is set so that only other obstacles located at a distance closer than the obstacle detected by the former are set as the detection target, an interruption vehicle, etc. When an obstacle occurs, it can be detected quickly. At that time, there is no need to interrupt the operation of the system that has already detected the obstacle. Therefore, it is possible to prevent interruption of the measurement data, which is inconvenient when determining whether or not there is a risk, and prevent the determination time from being lengthened, and it is possible to further improve the safety of traveling of the vehicle.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a vehicle forward warning radar device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an operation of detecting a distance to an obstacle in this embodiment.

FIG. 3 is a flowchart showing a flow of operations of a control arithmetic unit in this embodiment.

[Explanation of symbols]

11,33,43 PN generator 12 transmitter 13 transmitting antenna 21 receiving antenna 22 receiver 31, 41 product calculating unit 32, 42 a demodulator 34 and 44 the phase controller 51 controls the calculator t _e transmission PN code for Epoch t _d Radio wave propagation time t _d1 , t _d2 Output phase of PN generator 33, 43

Claims (1)

[Claims] 1. A transmission system that generates a pseudo noise code for transmission, which is a code string having a predetermined length, modulates a carrier by the pseudo noise code for transmission, and transmits a phase-modulated wave to the front of a vehicle on which the phase-modulated wave is mounted. , A pseudo noise code for transmission while controlling the phase gradually so that the phase difference between the receiving means for receiving the reflected wave of the phase modulated wave from the obstacle and the pseudo noise code for transmission is within a predetermined range. Generate a pseudo-noise code for reception that is the same code string as
The correlation between the received reflected wave and the reception pseudo-noise code is calculated, and if the correlation exceeds a predetermined value, an obstacle is present at a distance corresponding to the phase difference between the transmission pseudo-noise code and the reception pseudo-noise code. By determining that there is an obstacle, a plurality of obstacle detection systems that detect an obstacle such as a vehicle ahead, and an obstacle detection operation is performed by one of the plurality of obstacle detection systems. When is detected, the control range of the pseudo noise code for reception is controlled for each obstacle detection system so that the detection operation of other obstacles located at a closer distance is executed by the other obstacle detection system. A forward warning radar device for an automobile, comprising: a control unit.