JP2000006684A - Vehicle travel control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a safety travel property high even when a preceding vehicle accelerates to the tracking control vehicle speed or above by limiting the acceleration of this vehicle when the specified preceding vehicle accelerates to the prescribed vehicle speed or above, and stopping the travel control when the inter-vehicle distance exceeds the target prescribed distance. SOLUTION: When this vehicle 1 judges a vehicle located on its lane as a preceding vehicle based on the information from a laser radar 2 and a CCD camera 4, the inter-vehicle distance is measured, the speed of the vehicle 1 is calculated from a wheel speed sensor 32, the target inter-vehicle distance is set, and the speed of the preceding vehicle is calculated from the relative speed. When the preceding vehicle exceeds the prescribed speed during a tracking travel, the vehicle 1 does not track the preceding vehicle, and the tracking travel control is canceled only when the inter-vehicle distance from the preceding vehicle becomes K times the target inter-vehicle distance. When the preceding vehicle temporarily accelerates over the prescribed vehicle speed then immediately decelerates, the tracking travel control is not canceled until the preceding vehicle sufficiently separates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel control device for a vehicle, and more particularly, to a tracking drive control technique in the drive control.

[0002]

2. Related Background Art In recent years, in order to reduce the driving operation of an automobile, a travel control device having an inter-vehicle distance control device for pursuing a preceding vehicle has been developed and put into practical use.

[0003] A traveling control device provided with this inter-vehicle distance control device detects an inter-vehicle distance between a host vehicle and a preceding vehicle based on information from a forward recognition device such as a camera or a laser radar. The engine output and the braking force are adjusted so that the distance becomes a preset target inter-vehicle distance, thereby accelerating and decelerating the vehicle to track the preceding vehicle (tracking control).

Normally, in such tracking control, when the preceding vehicle reaches a predetermined vehicle speed in order to prevent the own vehicle from excessively tracking the preceding vehicle when the preceding vehicle continues to accelerate, the tracking driving is performed. The control is stopped.

However, when the preceding vehicle reaches a predetermined vehicle speed, the tracking drive control is suddenly stopped.
After that, when the inter-vehicle distance is shortened due to the deceleration of the preceding vehicle, for example, there is a problem that the tracking traveling control cannot be satisfactorily performed and traveling safety is impaired.

Therefore, for example, when the preceding vehicle accelerates and is no longer detected, the vehicle speed at that time is held for a predetermined time, or the acceleration / deceleration target value at that time is held for a predetermined time. An apparatus configured to maintain the tracking state for a while is disclosed in Japanese Patent Application Laid-Open No. 6-320983.

[0007]

The apparatus disclosed in the above publication is configured to accelerate the host vehicle at least until the preceding vehicle is no longer detected. In other words, in this device, the own vehicle follows the preceding vehicle faithfully as long as the preceding vehicle is detected. In this case, the own vehicle may be excessively accelerated, which is not preferable. .

In the apparatus disclosed in the above publication, the tracking control is terminated after a predetermined time has passed since the preceding vehicle is no longer detected, and the own vehicle speed is returned to the set vehicle speed. With such a configuration, the vehicle is running without monitoring the preceding vehicle at all during the predetermined time,
It is hard to say that sufficient driving safety has been obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to control the traveling of a vehicle so as to maintain high traveling safety even when the preceding vehicle accelerates at a speed higher than the tracking control vehicle speed. It is to provide a device.

[0010]

To achieve the above object, according to the first aspect of the present invention, the vehicle speed of the own vehicle is controlled so that the inter-vehicle distance between the own vehicle and the preceding vehicle becomes the target inter-vehicle distance. In a travel control device for a vehicle that performs travel control, a preceding vehicle specifying unit that specifies a preceding vehicle, an inter-vehicle distance detecting unit that detects an inter-vehicle distance, an own vehicle speed detecting unit that detects an own vehicle speed, and a preceding vehicle that detects a preceding vehicle speed Vehicle speed detection means, and target inter-vehicle distance setting means for setting a target inter-vehicle distance based on one of the own vehicle speed and the preceding vehicle speed, wherein the specified preceding vehicle accelerates and the preceding vehicle speed becomes greater than a predetermined vehicle speed. Sometimes
First, the acceleration of the own vehicle is limited by the acceleration limiting means. Thereafter, when the inter-vehicle distance exceeds a predetermined distance that is larger than the target inter-vehicle distance, the travel control suspending means suspends the travel control.

Accordingly, for example, when the own vehicle is following the preceding vehicle specified by the target inter-vehicle distance, the preceding vehicle speed temporarily exceeds a predetermined vehicle speed, accelerates, and then immediately decelerates, and the preceding vehicle speed returns to the predetermined vehicle speed again. Even if it returns below the vehicle speed,
While the acceleration of the own vehicle is suitably restricted, the tracking driving control is continuously executed without being stopped until the specified preceding vehicle is sufficiently separated from the vehicle ahead of the predetermined distance. It is possible to realize traveling control with high traveling safety according to the driver's intention while monitoring the vehicle.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there is shown a schematic configuration diagram of a traveling control device according to the present invention mounted on a vehicle 1. Hereinafter, the traveling control device according to the present invention will be described with reference to FIG. The configuration will be described.

At the front of the vehicle 1, a laser beam is emitted toward the front, and by scanning this laser beam, an object located in front of the vehicle 1 can be recognized, and the distance to the object can be measured. A simple scanning laser radar 2 is provided. In addition, the vehicle 1
A CCD camera 4 for capturing an image in front of is mounted. The CCD camera 4 is also capable of recognizing an object located in front, a lane (white line), and the like.

The engine 6 is connected to a throttle valve 8 for controlling the amount of intake air to the engine 6 and adjusting the engine output. More specifically, the throttle valve 8 can automatically adjust the valve opening based on an operation signal output from an electronic control unit (ECU) 50 to be described later according to the opening of an accelerator pedal (not shown) or the like. A simple throttle actuator 12 is provided.

A pair of left and right front wheels (drive wheels) 20, 20 and a pair of right and left rear wheels (sub wheels) 22, 22 are provided with service brakes 24 such as hydraulic disc brakes, respectively. It is connected to a brake pedal 28 via a brake master cylinder 26 having a pressure booster. Further, the brake master cylinder 26 is provided with a negative pressure type brake actuator 30 capable of automatically operating the service brake 24 in response to an operation signal from the ECU 50 regardless of an input from the brake pedal 28.

A wheel speed sensor 32 for detecting a right wheel speed VSR and a left wheel speed VSL is provided in the vicinity of the rear wheels 22, 22, which are slave wheels, corresponding to each wheel.
These wheel speed sensors 32 function as host vehicle speed detecting means for detecting the host vehicle speed Ve.

On a steering column 36 of a steering wheel 34 provided in the cabin of the vehicle 1, a tracking travel switching operation switch 38 for switching a travel control device of the vehicle 1 between a normal traveling state and a traveling state by tracking traveling control is provided. Is provided. When the tracking travel changeover operation switch 38 is operated to the set side, the inter-vehicle distance control, that is, the tracking travel control is started, and when it is operated to the reset side, the inter-vehicle distance control is released.

The ECU 50 is a main control device that controls various controls of the vehicle 1. As shown in the figure, the input side of the ECU 50 is connected to various sensors and switches such as the scanning laser radar 2, the CCD camera 4, the wheel speed sensors 32, 32, and the tracking drive switch 38. ,
Various driving devices such as a throttle actuator 12 and a brake actuator 30 are connected to the output side.

Hereinafter, the control contents of the traveling control device configured as described above will be described. That is, the operation and effect according to the present invention will be described.

Referring to FIGS. 2 and 3, there is shown a flowchart of a tracking drive control routine. The control procedure of the tracking drive control according to the present invention will be described below with reference to FIGS.

When the tracking drive switch 38 is operated to the set side to start the tracking control, first, in step S10, a preceding vehicle determination process is performed. Specifically, in step S10, when an object is recognized in front of the vehicle 1 based on information from the scanning laser radar 2 and the CCD camera 4, it is determined whether or not the object is a vehicle. If it is determined that the vehicle is a vehicle, the vehicle is determined to be a preceding vehicle. When there are a plurality of preceding vehicles, for example, a vehicle located on the own vehicle lane recognized by the CCD camera 4 or on the own vehicle lane estimated from the own vehicle steering wheel angle is determined as the preceding vehicle. As a result, the preceding vehicle is determined, and in this control, the preceding vehicle, that is, the preceding vehicle when the tracking drive switching switch 38 is set, is specified as the preceding vehicle of the vehicle 1 (the preceding vehicle). Specific means).

In step S12, the wheel speed sensor 3
The vehicle speed of the vehicle 1, that is, the host vehicle speed Ve is calculated based on the information from the host vehicles 2 and 32 (host vehicle speed detecting means). Here, the vehicle speed Ve is calculated, for example, by the following equation (1).

Ve = (VSR + VSL) / 2 (1) That is, the own vehicle speed Ve is an average value of the right wheel speed VSR and the left wheel speed VSL.

In step S14, the distance from the host vehicle to the preceding vehicle, that is, the inter-vehicle distance L is accurately measured based on information from the scanning laser radar 2 (inter-vehicle distance detecting means).

In the next step S16, the relative speed Vr between the host vehicle and the preceding vehicle is calculated based on the inter-vehicle distance information L. More specifically, the relative speed Vr is calculated based on the value of the inter-vehicle distance information L when the routine was last executed, that is, the amount of change ΔL between the previous value and the current value. At this time, if the change amount ΔL is positive and the relative speed Vr is positive, it is considered that the own vehicle is moving away from the preceding vehicle. If the change amount ΔL is negative and the relative speed Vr is negative, the own vehicle approaches the preceding vehicle. Can be considered to be.

In step S18, the preceding vehicle speed Vf is calculated from the following equation (2) based on the own vehicle speed Ve and the relative speed Vr (preceding vehicle speed detecting means).

Vf = Ve + Vr (2) Here, the preceding vehicle acceleration αf is also calculated by differentiating the preceding vehicle speed Vf. Specifically, the preceding vehicle acceleration αf is calculated from the change amount ΔVf between the previous value and the current value of the preceding vehicle speed information Vf when the routine was last executed.

In the next step S20, the host vehicle speed Ve is determined.
The target inter-vehicle distance Le is set based on the following formula (target inter-vehicle distance setting means). Specifically, a map indicating the relationship between Ve and Le as shown in FIG. 4 is preset and stored in the ECU 50, and the target inter-vehicle distance Le is obtained from the map. In FIG. 4, Lo is a minimum inter-vehicle distance (minimum inter-vehicle distance to be secured between the own vehicle and the preceding vehicle when it is assumed that the preceding vehicle has decelerated and the own vehicle has stopped (Ve = 0 km / h)). For example, 10 m) is shown.

In step S22, a target acceleration / deceleration αe of the vehicle is calculated. The target acceleration / deceleration αe is calculated, for example, from the following equation (3).

[0030] ^{αe = Vr 2/2 · (} L-Le) ... (3) Here, the target acceleration .alpha.e showed acceleration when the positive value will indicate a deceleration when negative .

In step S24 of FIG. 3, the preceding vehicle speed Vf
Is greater than a predetermined vehicle speed Vfx. Specifically, the predetermined vehicle speed Vfx is a preset upper limit vehicle speed of the preceding vehicle at the time of performing the tracking driving control, that is, whether the preceding vehicle speed Vf is increased and the tracking driving control is canceled (stopped). It is determined whether or not.

The determination result of step S24 is false (No)
If it is determined that the preceding vehicle speed Vf is equal to or lower than the predetermined vehicle speed Vfx, the process proceeds to step S32. On the other hand, if the determination result is true (Y
es), that is, when it is determined that the preceding vehicle speed Vf is higher than the predetermined vehicle speed Vfx, the process proceeds to step S26.

In step S26, the preceding vehicle speed Vf is once fixed at a predetermined vehicle speed Vfx. That is, when the preceding vehicle speed Vf exceeds the predetermined vehicle speed Vfx and the situation in which the tracking drive control is canceled is established, the target preceding vehicle speed Vf is limited to the predetermined vehicle speed Vfx so that the own vehicle accelerates forever and does not track the preceding vehicle. (Acceleration limiting means).

In the next step S28, the inter-vehicle distance L is larger than the target inter-vehicle distance Le multiplied by a predetermined coefficient K (for example, 1.5) (K.Le) (L> K.Le). It is determined whether or not. That is, when canceling the tracking drive control, the following distance L to the preceding vehicle is determined.

The result of the determination in step S28 is true (Yes).
If it is determined that the inter-vehicle distance L is larger than the product (K · Le) of the target inter-vehicle distance Le and the predetermined coefficient K, in step S30, the tracking travel control is canceled (travel control stopping means).

On the other hand, if the determination result of step S28 is false (N
If it is determined in o) that the inter-vehicle distance L is equal to or less than the product (K · Le) of the target inter-vehicle distance Le and the predetermined coefficient K, the process proceeds to step S32.

That is, referring to FIG. 5, the relationship between the target inter-vehicle distance Le that changes according to the own vehicle speed Ve, the product value (K · Le) of the target inter-vehicle distance Le and the predetermined coefficient K, and the inter-vehicle distance L are shown. However, as shown in the figure, when the inter-vehicle distance L exceeds the product value (K · Le) larger than the target inter-vehicle distance Le and reaches an area shown by oblique lines, the tracking travel control is canceled.

That is, when the preceding vehicle accelerates and becomes higher than the predetermined vehicle speed Vfx, the own vehicle is restricted in the vehicle speed and the preceding vehicle moves farther away. K times the distance Le (for example, 1.5 times)
In this case, the tracking travel control is canceled for the first time when the vehicle travels up to the distance, and the tracking travel control is continued without being canceled when the distance is less than or equal to the distance.

Thus, for example, when the own vehicle is following the preceding vehicle with the target inter-vehicle distance Le, the preceding vehicle speed Vf temporarily exceeds the predetermined vehicle speed Vfx, accelerates, and then immediately decelerates. Even if Vf returns to the predetermined vehicle speed Vfx or less again, the tracking drive control is satisfactorily continued without being canceled, and the driver must set the tracking drive switching operation switch 38 again. It is possible to avoid troublesomeness, such as the inconvenience, and to realize the traveling control according to the driver's intention. In addition, since the preceding vehicle is actually monitored until the tracking traveling control is cancelled, traveling control with high traveling safety can be realized.

In step S32, it is determined whether or not the own vehicle should be decelerated. That is, here, it is determined whether to perform the braking control or the throttle control. More specifically, the braking control is performed when the following conditions 1) to 3) are satisfied.

1) During tracking control 2) Vr <0 3) L <La or αe> αe1 where La is a braking start distance when the own vehicle approaches the preceding vehicle, and is relative to own vehicle speed Ve. It is set based on a map that is set in advance based on the speed Vr.

That is, in the step S32, the relative speed Vr becomes negative during the tracking drive control, and the inter-vehicle distance L falls below the braking start distance La, or the target acceleration / deceleration αe exceeds a predetermined value αe1. Is determined.

The determination result of step S32 is false (No)
If any of the above conditions is not satisfied, the process proceeds to step S34 to perform throttle control. The throttle control is for controlling the operation of the throttle actuator 12 according to the running state. Note that the throttle control is actually executed by a separately provided subroutine, but details thereof are omitted here.

On the other hand, if the result of the determination in step S32 is true (Y
If it is determined in es) that each of the above conditions is satisfied, the process proceeds to step S36 to execute braking control. In the braking control, a braking force to be generated by the service brake 24 is calculated based on the target acceleration / deceleration αe, and the operation of the brake actuator 30 is controlled according to the braking force. As a result, the vehicle 1 is properly and appropriately decelerated. Note that the braking control is actually executed by a separately provided subroutine, but details thereof are omitted here.

As described above, in the traveling control device according to the present invention, when the preceding vehicle speed Vf exceeds the predetermined vehicle speed Vfx while the own vehicle is following the preceding vehicle, the own vehicle switches to the preceding vehicle. After the tracking is not performed, the tracking travel control is canceled only when the inter-vehicle distance L from the preceding vehicle becomes K times (for example, 1.5 times) the target inter-vehicle distance Le.

Therefore, when the own vehicle is following the preceding vehicle at the target inter-vehicle distance Le, the preceding vehicle speed Vf temporarily exceeds the predetermined vehicle speed Vfx, accelerates immediately, and then decelerates immediately to reduce the preceding vehicle speed Vf again to the predetermined vehicle speed Vf. Even if the vehicle speed returns to the vehicle speed Vfx or less, the tracking drive control is continuously executed without being canceled until the preceding vehicle is sufficiently separated, and the driving safety according to the driver's intention is high. Travel control can be realized.

The traveling control device identifies a preceding vehicle in an urban area or the like and identifies the preceding vehicle in a low speed region (for example, 0 km / h <Vf <
This is particularly effective when the tracking traveling control is performed at 40 km / h). That is, in this case, the predetermined vehicle speed Vfx (for example, 4
0 km / h), the tracking control is canceled. However, in the city area, the vehicle (preceding vehicle) generally travels while repeating acceleration and deceleration according to the traffic conditions. Maintaining the tracking control until the preceding vehicle separates reliably during the change is extremely effective in securing the driving safety.

[0048]

As described above in detail, according to the vehicle traveling control apparatus of the first aspect, when the specified preceding vehicle accelerates and the preceding vehicle speed becomes higher than the predetermined vehicle speed, first, the own vehicle accelerates. Is limited by the acceleration limiting means,
When the inter-vehicle distance exceeds a predetermined distance that is larger than the target inter-vehicle distance, the travel control is stopped by the travel control canceling means. Even when the preceding vehicle speed temporarily exceeds the predetermined vehicle speed and accelerates, and then immediately decelerates and the preceding vehicle speed returns to the predetermined vehicle speed or less, the acceleration of the own vehicle is preferably limited and Until the preceding vehicle is separated far enough beyond the specified distance, the tracking driving control can be continuously performed well, realizing the driving control with high driving safety according to the driver's intention while actually monitoring the preceding vehicle. can do.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a traveling control device according to the present invention mounted on a vehicle.

FIG. 2 is a part of a flowchart showing a tracking drive control routine according to the present invention.

FIG. 3 is the remaining part of the flowchart showing the tracking drive control routine following FIG. 2;

FIG. 4 is a map showing a relationship between a host vehicle speed Ve and a target inter-vehicle distance Le.

FIG. 5 shows a target inter-vehicle distance Le that changes according to the vehicle speed Ve.
4 is a map showing a relationship between a product value (K · Le) of the target inter-vehicle distance Le and a predetermined coefficient K and an inter-vehicle distance L.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle (own vehicle) 2 Scanning laser radar 32 Wheel speed sensor 38 Tracking drive switching switch 50 Electronic control unit (ECU)

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference)

Claims (1)

[Claims] 1. A traveling control device for a vehicle for controlling traveling speed by controlling the vehicle speed of the own vehicle such that an inter-vehicle distance between the own vehicle and a preceding vehicle becomes a target inter-vehicle distance. An inter-vehicle distance detecting means for detecting the inter-vehicle distance, an own vehicle speed detecting means for detecting an own vehicle speed, a preceding vehicle speed detecting means for detecting a preceding vehicle speed, an own vehicle speed detected by the own vehicle speed detecting means, and the preceding vehicle speed Target inter-vehicle distance setting means for setting the target inter-vehicle distance based on one of the preceding vehicle speeds detected by the detecting means, and the preceding vehicle specified by the preceding vehicle specifying means is accelerated and detected by the preceding vehicle speed detecting means. Acceleration limiting means for limiting the acceleration of the own vehicle when the preceding vehicle speed becomes higher than a predetermined vehicle speed, and after the acceleration of the own vehicle is limited by the acceleration limiting means, the inter-vehicle distance becomes the target Travel control device for a vehicle, characterized by comprising: a traveling control stop means to stop the cruise control when exceeding a greater predetermined distance than between the distance.