JP3125496B2 - 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 cruise control system for a vehicle, and more particularly to a cruise control system for a vehicle having a following mode and a constant speed mode.

[0002]

2. Description of the Related Art Conventionally, various devices have been developed and mounted in order to reduce driving operation of a driver and improve safety.
A travel control device that detects an inter-vehicle distance to a preceding vehicle and performs a follow-up traveling while maintaining the inter-vehicle distance to the preceding vehicle at a safe inter-vehicle distance is one of them.

For example, in Japanese Utility Model Laid-Open Publication No. Sho 59-172385, when a preceding vehicle is detected in a monitoring area of a radar and the preceding vehicle is detected, the vehicle follows the preceding vehicle in accordance with an inter-vehicle distance from the preceding vehicle, and follows the preceding vehicle. A configuration is disclosed in which, when a vehicle comes out of the monitoring area of the radar, the vehicle speed at the time when the vehicle comes off is held for a predetermined time and the vehicle travels at a constant speed. Thus, even if the reflected signal from the preceding vehicle is interrupted on a curved road or the like, the current vehicle speed is maintained without being accelerated to the set vehicle speed before the interruption, so that it is possible to prevent approaching the preceding vehicle.

[0004]

However, depending on the driving situation, there may be a case where it is not desirable to change the control only by whether or not the preceding vehicle exists in the monitoring area of the radar. For example, if the preceding vehicle is approaching a curved road while overtaking the third vehicle in the adjacent lane while traveling on a road with a plurality of lanes, not only the preceding vehicle in the own lane but also the third vehicle in the monitoring area of the radar of the own vehicle. If only the preceding vehicle in the own lane deviates from the monitoring area of the radar, it may not be detected that the preceding vehicle in the own lane has deviated from the monitoring area, and the vehicle follows the third vehicle. The situation that does it occurs. At this time, when the speed difference between the third vehicle and the preceding vehicle in the own lane is large, the own vehicle is suddenly decelerated, and there is a problem that drivability is deteriorated.

Accordingly, the applicant of the present application has previously filed Japanese Patent Application No. 4-29.
No. 7274 proposed the following vehicle travel control device. In other words, when the preceding vehicle in the own lane and the third vehicle in the adjacent lane are both within the monitoring area of the inter-vehicle distance detecting means such as a radar on a curved lane and the preceding vehicle deviates from the monitoring area, the following distance is calculated. No big change appears,
Since the detected preceding vehicle has changed from the own lane to the adjacent lane, a large change appears in the relative speed. Therefore, the inter-vehicle distance and the relative speed change amount are compared with the respective threshold values, and if there is no change in the inter-vehicle distance but there is a sudden change in the relative speed, and the vehicle travels on a curved road from the steering angle detected by the steering angle detection means. If it is determined that the vehicle is running, it is determined that the detected preceding vehicle has changed to the third vehicle in the adjacent lane.

However, on a curved road, the speed change of the vehicle ahead of the own lane is generally large. Therefore, even if the vehicle ahead of the own lane is captured by the radar while traveling on the curved road,
If the preceding vehicle suddenly accelerates or decelerates and its speed changes suddenly, there is a risk that the preceding vehicle in the own lane may be erroneously recognized as being out of the radar detection range.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to detect that the detection target has shifted from the preceding vehicle in the own lane to the third vehicle even in the special driving situation described above. It is an object of the present invention to provide a vehicular travel control device capable of making a reliable determination.

[0008]

In order to achieve the above object, a vehicular travel control device according to the present invention maintains a predetermined inter-vehicle distance with a preceding vehicle when a preceding vehicle exists. A radar device for detecting a preceding vehicle, and a speed detecting means for detecting a speed of the own vehicle, in a vehicle traveling control device having a following traveling mode for following and a constant speed traveling mode for traveling at a constant speed when there is no preceding vehicle. Inter-vehicle distance comparing means for comparing a change in inter-vehicle distance with a preceding vehicle detected by the radar device with a predetermined distance change threshold; and a change in reflected signal intensity from the preceding vehicle detected by the radar device. An intensity comparison means for comparing the vehicle with a predetermined intensity change threshold, a travel path determination means for determining whether the vehicle is traveling on a curved road, and a change in the inter-vehicle distance is equal to or less than the distance change threshold, Reflected signal strength When the change is equal to or greater than the intensity change threshold and the own vehicle is traveling on a curved road, a determining unit that determines that there is a change in the preceding vehicle; and when the determining unit determines a change in the preceding vehicle. Control means for shifting from the following traveling mode to another mode.

[0009]

The running control device for a vehicle according to the present invention has such a structure, and can grasp the detected preceding vehicle more accurately from not only the change in the inter-vehicle distance but also the change in the reflected signal intensity.

That is, as described above, when both the preceding vehicle in the own lane and the third vehicle in the adjacent lane are within the monitoring area of the radar device on the curved lane and the preceding vehicle departs from the monitoring area, the following distance Does not show a big change,
Since the detected preceding vehicle has changed, a large change appears in the reflected signal intensity of the radar.

Therefore, the inter-vehicle distance and the amount of change in the reflected signal intensity are compared with the respective threshold values. If there is no change in the inter-vehicle distance but there is a change in the reflected signal intensity, it is determined that the vehicle is traveling on a curved road. In this case, it can be determined that the detected preceding vehicle has changed to the third vehicle in the adjacent lane.

[0012]

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 signal direction is mounted at a predetermined position in the front of the vehicle. The signal detected by the radar device 10 is supplied to the electronic control unit ECU 16, and the reflected signal strength, the inter-vehicle distance to the preceding vehicle, and the like are calculated. Also,
A vehicle speed sensor 12 and a steering angle sensor 14 are also mounted, and detect a vehicle speed and a steering angle, respectively, and supply them to the ECU 16.
The ECU 16 has a CPU, a ROM, a RAM, and the like, calculates a safe inter-vehicle distance based on the own vehicle speed, and based on a difference between the current inter-vehicle distance and the calculated safe inter-vehicle distance, a throttle actuator for maintaining the safe inter-vehicle distance. 18 or the brake actuator 20 is controlled to follow the preceding vehicle. If there is no preceding vehicle to follow, the throttle actuator 18 is controlled so as to run at a constant speed at a preset vehicle speed. The brake actuator 20
By controlling only the throttle actuator 18 without controlling the vehicle, simple follow-up traveling control can be performed.

The ECU 16 compares the amount of change in the inter-vehicle distance with a predetermined threshold (distance change threshold) to determine whether or not the inter-vehicle distance has suddenly changed, and determines the amount of change in the reflected signal intensity from the preceding vehicle. Calculated and predetermined threshold (intensity change threshold)
Then, it is determined whether or not the reflected signal intensity has suddenly changed. Then, although the inter-vehicle distance does not change suddenly, the reflected signal intensity changes, and the steering angle sensor 14
Is compared with a predetermined threshold value (steering threshold value), and if the own vehicle is traveling on a curved road, the detected preceding vehicle is another vehicle (a third vehicle traveling in an adjacent lane) Then, the throttle actuator 18 is controlled to maintain the current vehicle speed detected by the vehicle speed sensor 12.
Specifically, the distance change threshold, the intensity change threshold, and the steering threshold are stored in the ROM or the RAM in advance, and the
U sequentially reads them, compares the distance change (ie, relative speed) with the distance change threshold, compares the change in the reflected signal intensity with the intensity change threshold, and determines that the distance change is less than or equal to the distance change threshold and the reflected signal intensity If the change amount is equal to or greater than the intensity change threshold value, the steering angle is further compared with the threshold value. If the change amount is equal to or greater than the threshold value, a control signal is supplied to the throttle actuator 18 via the I / O board to maintain the current vehicle speed. The configuration is such that the throttle actuator 18 is controlled in order to achieve this.

FIG. 2 is a flowchart showing the processing of the ECU 16. First, a magnitude comparison between a change in the inter-vehicle distance and a distance change threshold is performed (S100). If there is a sudden change in the inter-vehicle distance, it can be determined that the target and the detected preceding vehicle have changed (S110). On the other hand, when there is no sudden change in the inter-vehicle distance, whether or not the reflection level (reflection signal intensity) has suddenly changed is compared with the intensity change threshold (S120). If there is a sudden change in the reflected signal strength, it can be determined that the target has changed (S14).
0), when there is no change in the reflected signal intensity, it can be determined that there is no change in the target (S130). In this manner, the presence or absence of a change in the target is determined, and if the target has changed, the magnitude of the steering wheel angle is compared with a predetermined steering threshold value (S150, S170), and the steering angle becomes large. If it is determined that the vehicle is traveling on the runway, the process shifts to control for maintaining the current vehicle speed (S180).
On the other hand, if the target does not change or the steering angle is equal to or less than the predetermined steering threshold even if the target changes, the following distance is controlled by controlling the following distance (S160).

As described above, in the present embodiment, it is determined whether or not the detected preceding vehicle has changed based on the change in the inter-vehicle distance and the change in the reflected signal intensity. In addition, even when the vehicle suddenly decelerates, the change in the detected preceding vehicle can be reliably recognized, and the vehicle can shift to follow-up traveling or constant speed traveling to continue smooth traveling.

[0017]

As described above, according to the vehicle traveling control device of the present invention, not only the vehicle ahead of the own lane but also the third vehicle exists within the monitoring area of the radar of the own vehicle on the curved road. Then, even when only the preceding vehicle in the own lane deviates from the radar monitoring area, it is possible to reliably determine that the target vehicle has changed, and to perform a target change countermeasure based on this determination.

[Brief description of the drawings]

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

FIG. 2 is a flowchart of an ECU according to the embodiment.

[Explanation of symbols]

 Reference Signs List 10 radar device 12 vehicle speed sensor 14 steering angle sensor 16 ECU 18 throttle actuator 20 brake actuator

Claims (1)

(57) [Claims] When a preceding vehicle exists, a following traveling mode in which the vehicle follows the vehicle while maintaining a predetermined inter-vehicle distance with the preceding vehicle and a constant speed traveling mode in which the vehicle travels at a constant speed when there is no preceding vehicle. A vehicle travel control device comprising: a radar device for detecting a preceding vehicle; speed detecting means for detecting a speed of the own vehicle; and a change in inter-vehicle distance between the preceding vehicle detected by the radar device and a predetermined distance change. An inter-vehicle distance comparing means for comparing with a threshold value; an intensity comparing means for comparing a change in the reflected signal intensity from the preceding vehicle detected by the radar device with a predetermined intensity change threshold value; Travel path determination means for determining whether or not the change in the inter-vehicle distance is equal to or less than the distance change threshold, and the change in the reflected signal intensity is equal to or greater than the intensity change threshold;
And determining means for determining that there is a change in the preceding vehicle when the own vehicle is traveling on a curved road; and when the determining means determines a change in the preceding vehicle, changing from the following traveling mode to another mode. A traveling control device for a vehicle, comprising: control means for shifting to (c).