JP2906874B2 - Travel control device for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling control device for a vehicle, and more particularly to an improvement in a following traveling performance in a bad environment such as a thaw.

[0002]

2. Description of the Related Art Conventionally, various devices have been developed and mounted in order to reduce driver's driving operation and improve safety, and a radar device is used to detect an inter-vehicle distance to a preceding vehicle using a radar device.
A travel control device that follows the preceding vehicle while keeping the inter-vehicle distance with the preceding vehicle at a safe inter-vehicle distance is one of them.

In such a traveling control device, it is needless to say how to accurately catch the preceding vehicle by the radar device, and the weather during traveling may reduce the performance of the radar such as rain, fog and snow. In the case of a harsh environment, the tracking performance deteriorates as the performance of the radar decreases. Therefore, conventionally, for example, Japanese Patent Laid-Open No. 61-16137
As disclosed in Japanese Unexamined Patent Application Publication No. H10-205, a bad environment detecting means for detecting that the current weather environment is in a bad environment such as rain, fog, and snow is provided. There has been proposed a configuration for improving the safety of the travel control device by canceling the following travel by the following travel control means when a bad environment is detected.

[0004]

As described above, in the related art, the following running is canceled in a bad environment, but in a real running environment, the following running is caused by the weather conditions such as rain, fog, and snow. In some cases, not only a bad environment is realized, but also a bad environment that causes performance degradation of the radar device due to other factors. For example, even when the weather conditions are good and clear, even when the snow melts, the mud on the road surface adheres to the traveling vehicle, and the body of the vehicle including the rear portion is very dirty.
The reflection intensity of radio waves and laser light from the radar device decreases. Such a decrease in the reflection intensity not only significantly reduces the detection distance of the radar device, but also causes a malfunction of the traveling control device linked to the radar device. In other words, if a dirty vehicle is present in the vicinity while traveling on a curved road, and a clean vehicle without dirt is traveling in the distance, a distant clean vehicle with high reflection intensity is detected and follows the distant preceding vehicle. There is a possibility of running.

Further, since the detectable distance of a dirty vehicle is reduced, the vehicle is accelerated following a clean vehicle, and when the dirty vehicle is interrupted, the radar has a short detection distance, so that a sudden braking is required. There is also a possibility that it will.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to grasp not only weather conditions but also the degree of dirt on surrounding vehicles, which is a direct cause of deterioration of radar performance. It is another object of the present invention to provide a vehicular travel control device capable of performing a follow-up traveling that is more adapted to the environment by changing the following traveling performance according to the degree of the contamination.

[0007]

In order to achieve the above object, a vehicle travel control device according to the present invention controls a vehicle speed of a vehicle with a predetermined control gain based on an inter-vehicle distance to a preceding vehicle.
In a traveling control device for a vehicle that follows a preceding vehicle, a radar device that detects the preceding vehicle, and an evaluation unit that evaluates the degree of dirt on the preceding vehicle based on the reflection intensity and the inter-vehicle distance of the preceding vehicle detected by the radar device. Calculating means for calculating a ratio of the preceding vehicle evaluated as dirty by a predetermined value or more to the total number of detected preceding vehicles within a predetermined time; and accelerating an acceleration gain among the control gains according to the ratio. Control means for adjusting.

[0008]

The vehicle traveling control device of the present invention has such a configuration, and evaluates the degree of dirt on the preceding vehicle by the evaluation means from the relationship between the reflection intensity of the detected preceding vehicle and the inter-vehicle distance. That is, when the preceding vehicle is contaminated with mud on the road surface at the time of the thaw, even if the distance between the preceding vehicle and the own vehicle is small, the reflection intensity is significantly lower than that of a clean vehicle. Therefore,
By comparing the inter-vehicle distance of a clean vehicle with the reflection intensity, it is possible to objectively evaluate how dirty the preceding vehicle is. Then, the ratio of the vehicle that is dirty by a predetermined value or more is calculated, and when the ratio of the dirty vehicle is large, it is determined that the surrounding environment of the own vehicle is under a bad environment, and the acceleration gain during the following running is adjusted. That is, it is set low and follows the preceding vehicle gently.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vehicle travel control device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of this embodiment. A radar device 10 that emits microwaves or laser light and detects the front of the vehicle in the traveling direction is mounted at a predetermined position at the front of the vehicle. The information of the preceding vehicle detected by the radar device 10 is used as an electronic control unit ECU for automatic following.
14 to calculate the inter-vehicle distance to the preceding vehicle, the relative speed, and the like. A vehicle speed sensor 12 is also provided at a predetermined position of the vehicle, detects the speed of the own vehicle, and supplies the same to the ECU 14 in the same manner. The ECU 14 calculates the safe inter-vehicle distance with the preceding vehicle based on the relative speed with respect to the preceding vehicle and the own vehicle speed, and based on the difference between the current inter-vehicle distance and the calculated safe inter-vehicle distance, maintains the safe inter-vehicle distance. The vehicle follows the preceding vehicle by controlling the throttle actuator 16 or the brake actuator 18. It is also possible to perform simpler follow-up running control by controlling only the throttle actuator 16 without controlling the brake actuator 18.

Further, the ECU 14 in the present embodiment evaluates the degree of dirt on the detected preceding vehicle in order to further grasp the environment around the own vehicle. Judgment is made, and the acceleration gain of the control gains for the following traveling is set lower than the normal acceleration gain, and the vehicle shifts to the gentle following traveling. The degree of contamination of the detected preceding vehicle is evaluated based on the detection signal supplied from the radar device 10, that is, the inter-vehicle distance to the preceding vehicle and its reflection intensity.

FIG. 3 shows the relationship between the detection distance and the reflection intensity. The horizontal axis indicates the detection distance (m) and the vertical axis indicates the reflection intensity (%).
Are separated into two areas. That is, the body of the detection preceding vehicle (specifically, the rear portion irradiated with radio waves or laser beams) is free from dirt, has a good reflection intensity in the area A, and mud or the like adheres from the road surface due to mud when thawed. And a region B in which reflection intensity is reduced due to contamination of the rear portion, and an undetectable region which cannot be captured by the radar apparatus 10 because the degree of contamination is severe and the reflection intensity is extremely low. ECU 14
Stores the data shown in FIG. 3 in a memory as a map, and based on the detection signal supplied from the radar device 10, the data of (distance, reflection intensity) are represented by A and B shown in FIG. , It is determined whether any of the three undetectable areas falls. If the detected data corresponds to the area B, the preceding vehicle is determined to be dirty, and the number of vehicles is counted sequentially. The ECU 14 may store the boundary line between the region A and the region B and the boundary line between the region B and the undetectable region as a functional expression instead of storing the data shown in FIG. 3 as a map. Good. Then, the ratio of the dirty preceding vehicle within a predetermined time is calculated, the acceleration gain is set low according to this ratio, and the throttle actuator 16 (or the brake actuator 18) is controlled to perform the following running adapted to the bad environment. Do.

Hereinafter, EC will be described with reference to the flowchart of FIG.
The operation of U14 will be described in detail.

The ECU 14 counts the number of dirty preceding vehicles among the detected preceding vehicles and calculates the ratio of the detected preceding vehicles to all the detected preceding vehicles. Data valid for calculating the ratio includes the latest data in order to accurately reflect the current driving environment. Need to be something. Thus, the ECU 14 of the present embodiment performs processing so as to update the data at every cycle T0. Whether or not the period T0 has elapsed is determined by comparing the timer times T and T0 (S10).
0), if the period T0 has not elapsed, the radar device 1
If the preceding vehicle is detected by 0, the variable ni indicating the number of detected preceding vehicles is incremented by 1, and the number of detected preceding vehicles is counted (S200). Then, it is determined which of the three areas shown in FIG. 3 corresponds to the detected inter-vehicle distance and the reflection intensity of the preceding vehicle. Specifically, it is determined whether or not the area A corresponds (S210).
If the area does not correspond to the area, the area corresponds to the area B (the preceding vehicle corresponding to the undetectable area cannot be detected). Therefore, the variable nBi indicating the number of dirty preceding vehicles is incremented by 1 and becomes dirty. Count the number of preceding vehicles (S2
20). Then, among the detected preceding vehicles, the ratio of dirty preceding vehicles is calculated, but when the total number of detected preceding vehicles, which is a population, is small, it is meaningless to calculate the ratio, and that the total number is small. It also means that the road on which the vehicle is traveling is clear, so there is no need to change the control gain for following travel (since there is no lane change or interruption,
Control problems such as hunting are unlikely to occur). Therefore,
The total number of preceding vehicles detected to date, that is,
-1) The number of detected ni-1 in the detection cycle T0 and the current i
It is determined whether or not the sum ni-1 + ni with the number of preceding vehicles ni detected up to the present time is equal to or greater than a predetermined value N (S230). The ratio x of the preceding vehicle is calculated. The ratio x is calculated as follows: x = (nBi + nBi-1) / (ni + ni-1) .100 Needless to say, the denominator in the above equation is the total number of detected preceding vehicles, and the numerator is the total number of dirty preceding vehicles. Then, after the ratio x is calculated,
The ECU 14 determines the acceleration gain g of the control gains using the ratio x. The acceleration gain is determined by multiplying the normal acceleration gain g0 by the adjustment coefficient k, that is, g = k · g0
The adjustment coefficient k is determined according to the ratio x. The process of determining the adjustment coefficient k is S250-S320. If the detected number of preceding vehicles is equal to or less than the predetermined value, it is not necessary to change the acceleration gain as described above, so K is set to 1.0 (S250). In other cases, K is determined so that the acceleration gain is set lower in accordance with the increase in the ratio X. FIG. 4 shows an example of a method of determining k in accordance with x. The acceleration gain is set to 1.0 without changing the acceleration gain up to a predetermined rate x1, and is set to be inversely proportional to x at a rate higher than x1. And k is set to 0 to prohibit acceleration at a predetermined ratio x2 or more. By setting in this way, when there are many dirty preceding vehicles, the acceleration gain is set to be low in accordance with the ratio, so that the acceleration is performed gently. In addition, control is not acceleration,
That is, in the case of deceleration, it is not appropriate to set the gain low from the viewpoint of fail-safe. Therefore, in this embodiment, the control gain is set to the same value as usual (S310).
Then, follow-up running is performed with the control gain determined in this way (S330). Therefore, when the preceding vehicle is dirty, such as when the snow melts, the acceleration gain of the following running is adjusted according to the ratio of the dirty preceding vehicle, so that the smooth following running can be performed in a bad environment.

In this embodiment, the acceleration gain is determined inversely as shown in FIG. 4, but it goes without saying that the acceleration gain may be determined in another manner, for example, an exponential function.

[0016]

As described above, according to the vehicle travel control device of the present invention, the acceleration gain can be adjusted even in a bad environment where the preceding vehicle is dirty and the performance of the radar device must be reduced. By doing so, hunting and the like can be prevented, and a smooth following run can be performed according to the surrounding environment.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an embodiment of the present invention.

FIG. 2 is a processing flowchart of an ECU of the embodiment.

FIG. 3 is a diagram showing a relationship between an inter-vehicle distance and a reflection intensity in the embodiment.

FIG. 4 is a diagram showing a relationship between a ratio of a dirty preceding vehicle and a gain adjustment coefficient according to the embodiment.

[Explanation of symbols]

 Reference Signs List 10 radar device 12 vehicle speed sensor 14 ECU 16 throttle actuator 18 brake actuator

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G08G 1/16 B60K 31/00 F02D 29/02 301 G05D 1/02

Claims (1)

(57) [Claims] 1. A traveling control device for a vehicle that travels following a preceding vehicle by controlling its own vehicle speed with a predetermined control gain based on an inter-vehicle distance from the preceding vehicle, wherein the radar device detects the preceding vehicle, and the radar device. Evaluating means for evaluating the degree of dirt on the preceding vehicle based on the reflection intensity of the preceding vehicle and the inter-vehicle distance detected in the above step; and A traveling control device for a vehicle, comprising: computing means for computing a ratio with respect to a preceding vehicle; and control means for adjusting an acceleration gain among the control gains according to the ratio.