JPH05141286A - Traveling control device for vehicle - Google Patents

Abstract

PURPOSE:To enable smooth control to be carried out with good responsiveness, in a traveling control device for a vehicle in which acceleration/deceleration control is carried out by using a relative speed with the preceding vehicle for following up with the preceding vehicle. CONSTITUTION:The detected signals from an intervehicle distance sensor 10 and a vehicle speed sensor 12 are input into a microcomputer 18. The microcomputer 18 calculates two kinds of relative speeds: an actual relative speed, and a smoothed relative speed, from the time rate of change of intervehicle distance. When the vehicle speed is greatly deviated from that at the time of detection of a vehicle or from a target traveling condition, vehicle-speed control is carried out by using the actual relative speed, while when it is near to the target traveling condition, vehicle-speed control is carried out by using the smoothed relative speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular travel control device, and more particularly to a vehicular travel control device that follows the preceding vehicle by using the relative speed between the preceding vehicle and the subject vehicle.

[0002]

2. Description of the Related Art Conventionally, a traveling control device for automatically adjusting the speed of a vehicle has been developed for the purpose of reducing the driving operation of a driver and improving safety in traveling on a highway.

In such a traveling control device, a constant speed traveling mode in which the driver cruises the vehicle at a predetermined vehicle speed, and when there is a preceding vehicle, the distance between the preceding vehicle and the preceding vehicle is maintained at a safe distance. However, a follow-up traveling mode or the like that follows the preceding vehicle is set.

In the following traveling mode, the vehicle speed control is performed so that the current vehicle-to-vehicle distance matches the target vehicle-to-vehicle distance calculated based on a predetermined vehicle speed or relative speed, but more accurate and smooth control is performed. In order to realize it, it is important how accurately these vehicle speeds and relative speeds, especially relative speeds, can be detected.

For example, Japanese Patent Laid-Open No. 61-187100 discloses a vehicle collision for smoothing the relative speed between the own vehicle and an obstacle to reduce the variation to evaluate the possibility of collision between the own vehicle and the obstacle. A prevention device is disclosed.

[0006]

However, in the configuration in which the smoothed relative speed is simply applied to the above-described follow-up traveling control, the smoothing is required in a situation where the inter-vehicle distance to the preceding vehicle changes abruptly. Control is delayed by time,
This causes a problem such that the distance between the vehicle and the preceding vehicle is drastically reduced.

On the other hand, if the smoothing time is shortened, such a control delay can be eliminated, but the variation in the detected relative speed value becomes large, and smooth control cannot be performed, which gives the driver an unpleasant feeling.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a vehicle running control device capable of performing accurate and smooth control when performing follow-up running using relative speed. Especially.

[0009]

In order to achieve the above object, the present invention detects an inter-vehicle distance detecting means 1 for detecting an inter-vehicle distance to a preceding vehicle as shown in FIG. 1 and a speed of an own vehicle. A vehicle speed detecting means 2, a relative speed calculating means for calculating a relative speed between the preceding vehicle and the host vehicle, a target inter-vehicle distance calculating means 3 for calculating a target inter-vehicle distance based on the vehicle speed and the relative speed,
In a vehicle travel control device including a control unit 4 that controls a throttle so that the inter-vehicle distance to a preceding vehicle becomes the target inter-vehicle distance, the actual relative speed is calculated from the amount of change in the inter-vehicle distance within the first predetermined time. An actual relative speed calculation means 5 for
Smoothing relative speed calculating means 6 for calculating a smoothing relative speed from a change amount of the inter-vehicle distance within a second predetermined time period that is larger than the first predetermined time period, and the absolute value of the smoothing relative speed is first
When the absolute value of the difference between the vehicle-to-vehicle distance and the target vehicle-to-vehicle distance is equal to or less than the first set vehicle-to-vehicle distance, the target vehicle-to-vehicle distance calculating means calculates the vehicle speed based on the vehicle speed and the smooth relative speed. A second target distance is calculated and the absolute value of the smooth relative speed is larger than the first set relative value.
If the absolute value of the difference between the inter-vehicle distance and the target inter-vehicle distance is greater than or equal to the set relative value and is greater than or equal to the second set relative value that is greater than the first set inter-vehicle value, the target inter-vehicle distance calculation means 3 is The target inter-vehicle distance is calculated based on the vehicle speed and the actual relative speed.

[0010]

The vehicle travel control device of the present invention has such a configuration and performs follow-up travel using two types of relative speeds, the actual relative speed and the smooth relative speed.

In a traveling state in which the relative speed (smooth relative speed) is small and the vehicle-to-vehicle distance is almost equal to the target vehicle-to-vehicle distance, there is a time margin for performing accurate control without variations, so smoothing is performed using the smooth relative speed. However, if the relative speed is large and the positional relationship with the preceding vehicle is likely to change drastically, or if the inter-vehicle distance is far from the target inter-vehicle distance, control should be started early. The control is performed using the actual relative speed.

[0012]

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

FIG. 2 shows a block diagram of the configuration of this embodiment. Inter-vehicle distance sensor 10 as inter-vehicle distance detecting means
Is provided at the front of the vehicle. This inter-vehicle distance sensor 10
For example, it is possible to use a CCD camera, a radar device, a laser radar device, or the like that captures an image of a preceding vehicle.
A vehicle speed sensor 12 that optically detects the rotation speed of the drive shaft of the vehicle is provided as vehicle speed detection means.

A setting switch 14 for setting the vehicle speed during constant speed running is provided in the driver's seat, and a system switch and a switching switch for switching the inter-vehicle distance during follow-up running (two steps, far / near in this embodiment). Is also installed in the driver's seat. Then, the signals from these respective sensors and SW are supplied to the microcomputer 18.

The microcomputer 18 has an input / output port, a ROM storing a processing program to be described later, a CPU for performing an operation according to the processing program, a RAM for storing an operation result, and the like. The relative speed is calculated from the time change rate of the inter-vehicle distance.

Here, in this embodiment, the microcomputer 18 calculates two types of relative speeds. The first relative speed is a sampling time of 0.8 seconds and a sampling frequency of 1
Actual relative velocity VRR which is the average of the relative velocity calculated in 6 times
The first and second relative velocities are smooth relative velocities VRR2, which are the averages of the relative velocities calculated at sampling times of 1.6 seconds and 32 times of sampling. Then, the two types of relative velocities VRR1 and VRR2 calculated in this way are appropriately used in relation to the preceding vehicle, and the throttle actuator 20 or the brake actuator 22 (in this embodiment, basically, vehicle speed control by throttle control is performed. Therefore, the brake actuator is not controlled, but it is also possible to perform the brake control if necessary) to control the traveling of the vehicle by the control signal to the alarm / display device 24 provided in the driver's seat. The vehicle distance is displayed, or an alarm is given to the driver when the vehicle distance becomes unacceptable.

The processing of the microcomputer 18 will be described in detail below with reference to the flowchart of FIG. First,
It is determined whether the traveling of the vehicle is the following traveling in which the inter-vehicle distance is controlled to follow the preceding vehicle (S101). This determination is made based on whether or not the changeover switch 16 which is also a system switch is turned on, and whether or not finite data is supplied from the inter-vehicle distance sensor 10. When following the vehicle, it is next determined whether or not the vehicle is detected (S102).
This determination is a determination as to whether or not there is a preceding vehicle to follow in the previous process and the preceding vehicle is detected for the first time in this process. Whether finite data was supplied from the inter-vehicle distance sensor 10 for the first time. It is determined by whether or not.

When the vehicle is detected, the inter-vehicle distance data is not accumulated, the distance data is not stable, and the running state of the preceding vehicle to be followed is unknown. Therefore, it is necessary to start the control early. There is. Therefore, control is performed using the actual relative speed VRR1 which has a short calculation time (S103). Specifically, first, the target inter-vehicle distance LT is calculated using the vehicle speed V and the actual relative speed VRR1. Several functions can be used to calculate the target inter-vehicle distance, but in this embodiment, they are calculated by the following equation.

LT = vehicle speed × 2.5−actual relative speed × 4 (near) LT = vehicle speed × 4−actual relative speed × 6 (far) Note that near / far corresponds to near / far selected by the switching SW. Is a calculation formula that is set as follows. Then, this target inter-vehicle distance L
The difference E = L-LT between the vehicle-to-vehicle distance L detected by the vehicle-to-vehicle distance sensor 10 is calculated, and the target vehicle speed VT is determined by VT = V + GE (G: gain) so that the difference becomes zero. The actuator 20 is controlled. As the control mode, the throttle is opened during acceleration, and the throttle is fully closed and overdrive is turned off during deceleration. Then, when the control using this actual relative speed VRR1 is being performed, the flag I is set to 0 (S104).
This flag I is an important flag for giving a hysteresis characteristic described later to control.

On the other hand, when it is determined in S102 that the vehicle is not detected, the smooth relative velocity VRR2 is first evaluated (S105). That is, the absolute value of the smooth relative velocity VRR2 and the first set relative value α1 are compared in magnitude. When following the preceding vehicle relatively well, the relative speed takes a small value and becomes smaller than α1. In this case, the absolute value of the difference between the target inter-vehicle distance LT and the current inter-vehicle distance L is further compared with the first set inter-vehicle value β1 (S10).
6). When following the preceding vehicle relatively well, the current vehicle-to-vehicle distance is closer to the target vehicle-to-vehicle distance and is smaller than β1. In this way, when the vehicle is following the preceding vehicle well, the smooth relative speed VRR is reduced in order to perform stable control and reduce hunting.
Follow-up control is performed using 2 (S107). In particular,
From the vehicle speed and the smooth relative speed, the target inter-vehicle distance LT is calculated by LT = vehicle speed × 2.5−smooth relative speed × 4 (near) LT = vehicle speed × 4−smooth relative speed × 6 (far), and the actual relative distance described above is calculated. Similar to the control by the speed VRR1, the target vehicle speed is calculated and the throttle actuator 20 is controlled. Then, the flag I is set to 1 when the control based on the smooth relative velocity VRR2 is performed (S108).

FIG. 4 shows the relationship between the smooth relative speed VRR2 and the inter-vehicle distance. The shaded area in the figure is the smooth relative velocity VRR.
The absolute value of 2 is less than or equal to the first set relative value, and the absolute value of the difference between the inter-vehicle distance and the target inter-vehicle distance is less than or equal to the first set inter-vehicle value (control by smooth relative speed VRR2).

On the other hand, when the traveling state of the vehicle is outside the hatched area in FIG. 4, the smooth relative speed VRR2 and the second set relative value α2
The magnitude comparison with (α1 <α2) is performed (S10).
9). When the relative speed with respect to the preceding vehicle is large, it is necessary to reduce the relative speed early, so the control is performed using the actual relative speed VRR1 whose calculation time is short as described above (S10).
3). Further, even if the relative speed is not so large, the inter-vehicle distance is significantly different from the target inter-vehicle distance, specifically, the absolute value of the difference between the inter-vehicle distance and the target inter-vehicle distance is larger than the second set inter-vehicle value β2. Control based on the actual relative speed is performed to start the control (S110). In FIG. 4, such a large relative speed or a case where the inter-vehicle distance greatly differs from the target inter-vehicle distance is shown outside the dotted line region.

As described above, when the preceding vehicle to be followed is detected for the first time, and when the traveling state (relative speed and inter-vehicle distance) deviates greatly from the target traveling state, the vehicle speed control is performed using the actual relative speed VRR1. The vehicle speed control is performed using the smooth relative speed VRR2 in the vicinity of the target traveling state, but in other traveling states, that is, in the area inside the dotted line (excluding the shaded area) in FIG. , It controls the running of the vehicle with a hysteresis characteristic.

Here, the hysteresis characteristic means that when the control is performed at the actual relative speed VRR1, the control is continued at this actual relative speed VRR1 when the control shifts to this area, and the control at the smooth relative speed VRR2 is performed. If this area is shifted to after this is performed, this smooth relative velocity VRR2 continues.
Means that the control is performed by. That is,
In this area, the control content changes according to the control content until the transition to this area. By providing a hysteresis characteristic in this way, the actual relative speed VRR1
It is possible to make a smooth transition when the control by the control shifts to the control by the smooth relative velocity VRR2 (or vice versa).

Specifically, this hysteresis characteristic is achieved by the value of the flag I. As described above, the flag I is set to 0 when the control by the actual relative speed VRR1 is performed.
Is set to (S104), smooth relative velocity VRR2
The flag I is set to 1 when the control is performed by (S108). Therefore, the value of the flag I is checked when the traveling state of the vehicle is in an area other than the hatched area and the area outside the dotted line in FIG. 4 (S111), and when the flag I is 0, control is performed by the actual relative speed VRR1 ( S103), if the flag I is 1, the smooth relative velocity VRR
By performing the control according to 2 (S107), the control can be provided with a hysteresis characteristic, and smooth control can be performed over all traveling states.

As described above, in this embodiment, the two kinds of relative speeds, that is, the actual relative speed and the smooth relative speed, are selectively used according to the running state to perform the control, and the smooth control with good responsiveness and no variation is performed. Can be achieved at the same time.

[0027]

As described above, according to the vehicle travel control device of the present invention, when the preceding vehicle is traveling,
It has excellent responsiveness and can perform accurate and smooth control.

[Brief description of drawings]

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

FIG. 2 is a configuration block diagram of an embodiment of the present invention.

FIG. 3 is a processing flowchart diagram of the embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a relative speed and an inter-vehicle distance in the embodiment.

[Explanation of symbols]

 10 Distance sensor 12 Vehicle speed sensor 14 Setting SW 16 Switching SW 18 Microcomputer 20 Throttle actuator 22 Brake actuator

Claims (1)

[Claims] 1. An inter-vehicle distance detecting means for detecting an inter-vehicle distance to a preceding vehicle, a vehicle speed detecting means for detecting a speed of the own vehicle, and a relative speed calculating means for calculating a relative speed between the preceding vehicle and the own vehicle. A vehicle traveling control device comprising: a target vehicle distance calculation means for calculating a target vehicle distance based on the vehicle speed and the relative speed; and a control means for controlling a throttle so that a vehicle distance to a preceding vehicle becomes the target vehicle distance. In the above, the actual relative speed calculating means for calculating the actual relative speed from the amount of change in the inter-vehicle distance within the first predetermined time, and the smooth relative from the amount of change in the inter-vehicle distance within the second predetermined time larger than the first predetermined time Smooth relative speed calculating means for calculating speed, wherein the absolute value of the smooth relative speed is less than or equal to a first set relative value, and the absolute value of the difference between the inter-vehicle distance and the target inter-vehicle distance is first. Set distance value When it is below, the target inter-vehicle distance calculating means calculates the target inter-vehicle distance based on the vehicle speed and the smooth relative speed, and the absolute value of the smooth relative speed is a second set relative value larger than the first set relative value. When the absolute value of the difference between the inter-vehicle distance and the target inter-vehicle distance is equal to or greater than the second set relative value that is greater than the first set inter-vehicle value, the target inter-vehicle distance calculation unit determines the vehicle speed and the actual value. A travel control device for a vehicle, wherein the target inter-vehicle distance is calculated based on a relative speed.