JP2001116839A - Sensor for intervehicular distance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a ghost from being mis-recognized as an actual target. SOLUTION: This intervehicular distance sensor mounted on an own vehicle 15 calculates an actual line 44 correspondent to a wall 13 based on a detected target to find a base line 45 based on the acutual line 44. The target 14 existing outside the base line 45 counts as the ghost to be erased. The ghost caused by reflecting a radio wave of a millimter wave radar by the wall 13 is thereby prevented from being detected. The base line is compared with the actual line and the base line is updated by learning to prevent erroneous recognition for the ghost accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle mounted on a vehicle,
The present invention relates to an inter-vehicle distance sensor that detects a relative distance to a target.

[0002]

2. Description of the Related Art Conventionally, an inter-vehicle distance sensor using a millimeter wave radar for detecting a target such as a preceding vehicle is mounted on a vehicle, and a detection output is output from an automatic cruise control system (AC).
C). This inter-vehicle distance sensor radiates millimeter waves toward the front of the vehicle, receives the reflected radio waves from the target, and mixes the received signal with the transmitted signal to detect the relative distance to the target, relative speed, etc. Was.

[0003]

The reason why a conventional inter-vehicle distance sensor detects a ghost will be described with reference to FIG.
In conventional inter-vehicle distance sensors using millimeter wave radar,
When the radio wave 12 reflected by the preceding vehicle 11 is reflected by a wall 13 such as a tunnel wall or a soundproof wall, a ghost 14
Was erroneously recognized as traveling. In order to prevent this erroneous recognition, the conventional inter-vehicle distance sensor is adapted to recognize only a vehicle traveling ahead of the vehicle 15. However, even when such measures are taken, a ghost may be erroneously recognized as a vehicle running ahead of the own vehicle on a curved road or the like.

An object of the present invention is to provide an inter-vehicle distance sensor capable of preventing a ghost from being erroneously recognized as an actual target.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object. The present invention relates to an inter-vehicle distance sensor mounted on a vehicle and detecting a relative distance to a target, wherein a means for calculating an actual line constituted by a stationary object from the detected target and a basic line based on the actual line And a means for determining whether the detected target is inside or outside the basic line, and deleting the outside target.

[0006] When the vehicle travels along a stationary object such as a wall, the following distance sensor detects a target from among the detected targets.
The actual line constituted by the continuous stationary objects is calculated, and the basic line is calculated based on the actual line. Those outside the basic line are determined to be ghosts and are deleted. This prevents a ghost generated by the reflection of the radio wave from being erroneously recognized as an actual target.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A millimeter-wave radar inter-vehicle distance sensor to which the present invention is applied will be described with reference to the drawings. FIG.
2 shows a circuit configuration of an inter-vehicle distance sensor 21. The transmitter 22
A millimeter wave signal modulated into a ramp waveform is transmitted to a transmitting antenna 23.
Irradiate from The radio wave emitted from the transmission antenna 23 at a predetermined beam angle is reflected by the target when there is a target such as a preceding vehicle. Receiving antenna 2
4 receives the radio wave reflected by the target. The received signal is mixed with a local oscillation signal from the transmitter 22 by a mixer 25 and input to a digital signal processor 30 via a filter 26, an amplifier 27, an auto gain controller 28, and an A / D converter 29. You.

In the digital signal processor 30, the FF
The T processing unit 31, the frequency analysis unit 32, and the signal processing unit 33 calculate a relative distance, a relative speed, and a lateral position of each target. In addition, since these structures and operations are the same as those of the conventional inter-vehicle distance sensor, detailed description is omitted. The calculation result of the following distance sensor 21 is A
It is output to the CC device (automatic traveling control device) 34. AC
The C device 34 performs automatic traveling control based on each target information acquired from the following distance sensor 21.

An example of a method for identifying a ghost will be described with reference to FIGS. Now, as shown in FIG. 3, the vehicle 15 is traveling on a straight lane along a wall 13 such as a tunnel wall or a soundproof wall, and the preceding vehicle 11 exists on the same traveling lane in front. Suppose At this time, FIG.
As described above, the inter-vehicle distance sensor 21 detects not only the preceding vehicle 11 but also the ghost 14 outside the wall 13 as a target by signal analysis. at the same time,
The protrusions 41, 42, and 43 fixed to the wall 13 are detected as stationary objects.

FIG. 4 illustrates the relative distance and the lateral position of each target calculated by the inter-vehicle distance sensor 21 in the state of FIG. The preceding vehicle 11 ahead of the own vehicle 15 is detected at the position of the lateral position 0. The protrusions 41, 42, 43 of the wall 13 are detected as stationary objects (relative speed = own vehicle speed). Projection 4 detected continuously
The lines formed by 1, 42 and 43 are assumed to be actual lines 44.

When the radio wave is reflected on the wall 13 and the ghost 14 is detected, the horizontal position of the ghost 14 is outside the actual line 44. Therefore, the actual line 44
Ghost 1 for targets detected outside
4, the target information is not output to the ACC device 34. In the example described above, the target outside the actual line 44 is determined to be the ghost 14. However, if a stationary object such as a sign is determined to be the actual line 44, there is a possibility that a vehicle that is actually traveling on an adjacent lane is erroneously determined as a ghost. In order to prevent such a situation, the basic line 45 is used as a reference for determining a ghost. The above-described example is an example in which the basic line 45 is matched with the actual line 44, and the present invention includes this example in the technical scope.

Next, a specific example of a ghost determination method using the basic line 45 will be described below. 1. A line 46 for one lane is set as the width of the own vehicle traveling lane. Also, a width for one lane is set on both sides from the own vehicle traveling lane. The line that determines the width of the total of three lanes is the maximum value 47 of the basic line.

2. Information on the stationary target existing outside the line 46 of the own vehicle traveling lane among the stationary target detected by the millimeter wave radar is collected. 3. An actual line 44 is calculated from the collected horizontal position of the stationary target. At this time, 3
Only when the above is detected, the actual line 44 is calculated, and when it is less than that, by not performing the calculation of the actual line 44, a stationary object such as a sign appearing accidentally is regarded as a wall. False recognition can be prevented. Also, as a method of determining the horizontal position of the line,
There are a method of averaging the horizontal position of each target, and a method of using the target with the smallest horizontal position (the innermost target).

4. Learning is performed by comparing the actual line 44 with the previous basic line 45, and a new basic line 45 is obtained.
To determine. Here, the conventional basic line is a basic line that has been updated by the processing of the signal processing unit 33 up to the previous time. The default value of the basic line is
The above-described maximum value 47 of the basic line is set. If the actual line 44 is inside the basic line 45, the basic line is learned inside. For example, a new basic line is set inside the currently stored basic line 45 by a certain value. Alternatively, a new basic line 45 is set inside by a value proportional to the difference between the actual line 44 and the basic line 45.

As described above, by setting a new basic line 45 by learning, the basic line 45 is not largely changed by a stationary object that appears fragmentarily, and an actual vehicle or the like is erroneously determined to be a ghost. Will not be done. Also, if the stationary object is a continuous one such as a wall,
The basic line 45 approaches the actual line 44. Also, when the actual line 44 is outside the basic line 45, the basic line 45 is learned to the outside similarly to the case of the inside. However, when the new basic line 45 is outside the maximum value 47 of the basic line, the basic line 45 is held at the maximum value 47, and the new basic line 45 is set further outside. do not do.

The operation of the signal processing unit 33 for implementing the above-described processing will be described with reference to the flowchart of FIG.
As in the case of a normal inter-vehicle distance sensor, in the processing up to step S11, information such as the relative distance, relative speed, and beam angle for each target is obtained. Step S12
Then, it is determined whether or not there is a target having a high relative speed outside the line 46 of the vehicle traveling lane stored in advance. Here, if there is a target with a high relative speed, that is, a stationary object, the process proceeds to step S14.
Proceed to 3.

In step S13, it is determined whether there is a target whose distance derivative is equal to the relative speed. Here, if there is a target whose distance derivative is equal to the relative speed, that is, a target such as a guardrail, the process proceeds to step S14, and if not, the process proceeds to step S40. Step S
At 14, the actual line 44 is calculated from the lateral position of the target because the protrusions 41 to 43 or the guardrails from the wall are detected as the targets.

In step S15, it is determined whether the actual line 44 is inside or outside the previous basic line 45. If it is inside, a new basic line 45 is set in step S16 by shifting the previous basic line inside by learning. If outside, step S
At 17, a new basic line 45 is set by shifting the basic line outward by a fixed value or a proportional value by learning.

When learning to the outside of step S17 is completed, it is determined in step S18 whether or not the new basic line 45 is outside the maximum value 47 stored in advance. Here, if it is not outside, the process proceeds to step S20, but if it is outside, that is, if the obtained basic line is outside the front three lanes, the stored maximum value 47 is added to the new basic line 45 in step S19. Set as As a result, the basic line 45 does not spread beyond the three front lanes.

In step S20, the basic line 45 is
Either a stationary object is detected and newly set, or the stationary object is not detected and remains as it is. In step S20, it is determined whether the target other than the target recognized as the actual line 44 is inside or outside the basic line 45. If the target is inside the basic line 45, the target is determined as a target to be recognized in step S21. Also, if outside,
In step S22, the target is deleted as a ghost.

After step S22, the target information is output to the ACC unit 34, and the process returns to the FFT process, the frequency analysis and the like.

[0022]

According to the present invention, it is possible to prevent a ghost from being erroneously recognized as an actual target in an inter-vehicle distance sensor.

[Brief description of the drawings]

FIG. 1 is a diagram showing the reason why a ghost is detected by a conventional inter-vehicle distance sensor.

FIG. 2 is a diagram showing a circuit configuration of an inter-vehicle distance sensor to which the present invention is applied.

FIG. 3 is a diagram showing a situation where an inter-vehicle distance sensor of the present invention is placed.

FIG. 4 is a view showing each target information in the situation of FIG. 3;

FIG. 5 is a flowchart showing processing in the signal processing unit of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Leading vehicle 12 ... Radio wave 13 ... Wall 14 ... Ghost 15 ... Own vehicle 21 ... Inter-vehicle distance sensor 22 ... Transmitting device 23 ... Transmitting antenna 24 ... Receiving antenna 25 ... Mixer 26 ... Filter 27 ... Amplifier 28 ... Auto gain controller 29 ... A / D converter 30 ... Digital signal processor 31 ... FFT processing unit 32 ... Frequency analysis unit 33 ... Signal processing unit 34 ... ACC device 41,42,43 ... Protrusion 44 ... Real line 45 ... Basic line 46 ... 1 Lane line 47: Maximum value of basic line

Claims (4)

[Claims] 1. An inter-vehicle distance sensor mounted on a vehicle and detecting a relative distance to a target, a means for calculating an actual line constituted by a stationary object from the detected target, and based on the actual line. An inter-vehicle distance sensor, comprising: means for calculating a basic line; and means for determining whether a detected target is inside or outside the basic line, and eliminating targets outside the basic line. . 2. The inter-vehicle distance sensor according to claim 1, wherein the means for calculating the actual line calculates an average value of a target detected as a stationary object and uses the average as an actual line. 3. The inter-vehicle distance sensor according to claim 1, wherein the means for calculating the basic line compares the actual line with a previous basic line and calculates a new basic line by learning. 4. The apparatus according to claim 1, wherein said means for calculating said basic line holds said maximum value as a new basic line when said new basic line is larger than a predetermined maximum value. 2. The inter-vehicle distance sensor according to claim 1.