JP2827615B2 - 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 a traveling control device for detecting a preceding vehicle by using a CCD sensor and following the preceding vehicle.

[0002]

2. Description of the Related Art Conventionally, a traveling control device for a vehicle has been developed for the purpose of reducing the driving operation of a driver. In such a vehicle travel control device, generally, when there is no preceding vehicle, the driver travels at a constant speed at a preset speed, and when the preceding vehicle exists within a predetermined range, the vehicle follows the preceding vehicle. The vehicle travels with the inter-vehicle distance kept as constant as possible.

Here, in order to follow the preceding vehicle, it is necessary to accurately measure the distance between the vehicle and the preceding vehicle, and therefore, a laser radar device or a distance measuring device using a CCD sensor is mounted on the vehicle. You. For example, JP-A-3-165212
Japanese Patent Application Laid-Open Publication No. H11-163873 proposes a device in which a pair of CCD sensors is arranged in a vertical direction, and a distance between the vehicle and a preceding vehicle is detected by using a shift amount of the image of the vehicle in the vertical direction. 10 and 11 show the principle of distance measurement using such a pair of CCD sensors. In FIG. 10, the CCD sensors 10a and 10b are arranged in a vertical direction at a predetermined distance D (referred to as a base line length). In addition, these CCD sensors 10
Lenses 12a and 12b having a predetermined focal length f are arranged in front of the lenses 10a and 10b to collect light from a vehicle ahead and form an image on the CCD sensors 10a and 10b.

Here, when the preceding vehicle is located at infinity, the imaging positions of the CCD sensors 10a and 10b are both at the origin O, but when the preceding vehicle is located at A in FIG. Moves from O to the point P.

[0005] When the vehicle ahead approaches further and is located at B in the figure, the image forming position on the CCD sensor 10b further moves from the origin O to point Q in the figure.

[0006] As described above, depending on the distance to the vehicle ahead, C
Since the imaging position between the CD sensors 10a and 10b shifts, the distance between the vehicle and the preceding vehicle can be detected by detecting the shift amount. Specifically, if the inter-vehicle distance is L, the focal length of the lens is f, the base line length is D, the shift amount n is represented by the number of bits of the CCD sensor, and the bit length of the CCD sensor is Δx, L = fD / nΔx. The inter-vehicle distance L can be calculated.

Here, in order to detect the shift amount n, an evaluation function called a correlation degree is used. This correlation degree S (j)
As shown in FIG. 11, S (j) = Σ | B (i) is obtained from the front vehicle image output R (i) obtained by the CCD sensor 10a and the front vehicle image output B (i) obtained by the CCD sensor 10b. ) −R (i + j) |. This equation shifts the output R (i) of the CCD sensor 10a by j each time.
b indicates the degree of coincidence with the output B (i),
The bit shift amount at which the correlation degree S (i) becomes a minimum is the shift amount to be obtained.

[0008]

As described above, the conventional vehicle travel control device calculates the degree of correlation of the image of the forward vehicle obtained by the CCD sensor and calculates the degree of correlation based on the amount of deviation at which the degree of correlation becomes minimal. The inter-vehicle distance to the preceding vehicle was calculated, and further, the throttle or brake of the own vehicle was controlled based on the inter-vehicle distance to control the inter-vehicle distance to be constant. However, there is a problem that running control may not be performed smoothly.

FIG. 12 shows a vehicle arrangement showing an example of such a case. Passenger car 1 in front of own vehicle 11
2 and a truck 14 is located in front of the passenger car 12. The inter-vehicle distance between the host vehicle 11 and the passenger car 12 is L ₁ , and the inter-vehicle distance between the host vehicle 11 and the truck 14 is L ₂ . CC in such a vehicle arrangement
FIG. 13 shows the D sensor output and the degree of correlation calculated from the CCD sensor output. First, FIG. 13A shows the CCD sensor output in the vehicle arrangement shown in FIG. 12, and an image output corresponding to the passenger car 12 and the truck 14 is obtained. FIG. 13B is a graph showing the degree of correlation at this time, and the horizontal axis shows the distance obtained by converting the shift amount by the above-described equation. The bit shift amount at which the degree of correlation is minimized is the deviation amount to be obtained.
It will shift amount a is determined in the case of (B), thus the inter-vehicle distance in this case is L _2.

On the other hand, the speed of the host vehicle 11 is increased, etc.
FIGS. 13C and 13D show the output of the CCD sensor and the degree of correlation when the inter-vehicle distance from the vehicle is reduced. FIG.
In (C), as the inter-vehicle distance between the host vehicle 11 and the passenger car 12 and the truck 14 is reduced, the truck image output has a large luminance, causing an overflow. On the other hand, the luminance of the passenger car also increases, so that the CCD output has a large value. Becomes Correlation at this time changes as shown in FIG. 13 (D), the deviation amount for obtaining the drawing b, and the inter-vehicle distance at this time is L _1.

Accordingly, the inter-vehicle distance obtained from the output of the CCD sensor is L _{2 at} a certain time, that is, the inter-vehicle distance between the vehicle 11 and the truck 14, and the next time, the inter-vehicle distance is L ₁ , that is, the own vehicle 11 The vehicle-to-vehicle distance between the vehicle and the passenger car 12 is output, and the vehicle-to-vehicle distance changes discontinuously.

[0012] Then, even when the running of the own vehicle is controlled in accordance with the inter-vehicle distance, the acceleration / deceleration is discontinuously performed depending on the inter-vehicle distance that changes discontinuously, and the drivability deteriorates. There was a problem.

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 accurately detect a relative positional relationship between a host vehicle and a preceding vehicle by using a CCD sensor and to perform smooth acceleration / deceleration control. It is an object of the present invention to provide a vehicle travel control device capable of performing the following.

[0014]

In order to achieve the above-mentioned object, a vehicular traveling control device according to the present invention comprises a CCD sensor 1 for photographing a preceding vehicle as shown in FIG.
A shift amount calculating means 2 for calculating a shift amount at which the correlation degree of the front vehicle image obtained by the CD sensor 1 is minimized, and the existence probability of the shift amount based on the value of the correlation degree corresponding to the shift amount and the slope , A storage means 4 for storing a preset risk level as a function of a predetermined area in front of the vehicle, and a relative positional relationship with a preceding vehicle based on the shift amount, the existence probability and the risk level. Evaluation means 5 for evaluating
And a control means for controlling the throttle or the brake based on the evaluation result.

[0015]

The running control device for a vehicle according to the present invention has the above-described configuration, and does not simply control the running of the own vehicle by calculating the inter-vehicle distance from the shifting amount, but integrates the calculated shifting amount. The vehicle is controlled based on the evaluation result and the traveling of the own vehicle is controlled based on the evaluation result.

That is, as described above, when there are a plurality of vehicles such as passenger cars and trucks in front of the own vehicle, there are a plurality of shift amounts corresponding thereto, but all of these shift amounts are present. Gives environmental information in front of the host vehicle.

Therefore, in the present invention, the importance of these deviation amounts given to the own vehicle is evaluated based on the existence probability, and the relative position (inter-vehicle distance and vehicle direction) with respect to the own vehicle is evaluated based on the degree of risk. This is to comprehensively calculate the relative positional relationship with the preceding vehicle.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a traveling control device for a vehicle according to the present invention.

FIG. 2 is a block diagram showing the configuration of this embodiment. A plurality of pairs of CCD sensors 1a, 1b,...
It is provided in the horizontal direction. As an installation position, it can be attached to, for example, a bumper at the front of the vehicle. Detection outputs from the plurality of CCD sensor pairs are sent to a signal processing unit 16.
And converted from an analog signal to a digital signal. The CCD sensor output converted to the digital signal is further input to the microcomputer 24. The microcomputer 24 includes an input interface 24a, a CPU 24b for performing a predetermined calculation process described later, a ROM 24c storing a predetermined program, a RAM 24d for temporarily storing calculation results and a risk described later, and an output interface 24e. Is output to the throttle actuator 26 to the brake actuator 28 to control the traveling of the vehicle.

Hereinafter, the operation of the microcomputer 24 will be described in detail with reference to the flowchart of FIG.

First, the output from the CCD sensor is converted into a digital signal by the signal processing section 16 in S101.
Then, in step S102, the CPU 24b calculates the minimum value of the correlation degree from the CCD sensor output converted into the digital signal. The correlation degree S (j) is, as described above, a pair of C
Assuming that the CD sensor outputs are B (i) and R (i), respectively, S (j) = Σ | B (i) −R (i + j) | Is calculated. FIG. 5 shows an example of the degree of correlation calculated in this way, and shows a case where there are three bit shift amounts at which the degree of correlation is minimal. These bit shift amounts are assumed to be n _i (i = 1, 2, 3). Since the CCD sensor pair is provided with a plurality horizontally, bit shift n _i is calculated in this manner correlations for each of these plurality of CCD sensor pairs is minimized. Since the plurality of CCD sensor pairs have different detection areas, as shown in FIG.
Summing up the bit shift amount n _i obtained by the sensor pair, n
_i (θ). Then, the CPU 24b stores the calculated n _i (θ) in the RAM 24d.

Next, the CPU 24b proceeds to S103,
Evaluation function F for evaluating the relative positional relationship with the preceding vehicle
Is calculated. The evaluation function F is stored in the above-mentioned bit shift amount n _i (θ), the existence probability ξ (r, θ) of the bit shift amount n _i (theta) and is preset as a function of the vehicle forward of the predetermined region RAM24d C _r (r,
θ). Here, the existence probability ξ (r, θ)
Is set according to the value of the degree of correlation and the slope of each bit shift amount n _i (θ). For example, in the case of the bit shift amounts n ₁ , n ₂ , and n ₃ shown in FIG. 5, the magnitude relationship between the degrees of correlation is S (n
₂ ) <S (n ₃ ) <S (n ₁ ). Moreover, the largest of the bit shift amount n ₁ and n ₂ the inclination is the inclination of the bit shift amount n ₂ are almost identical. Therefore, in this case, the existence probability is set to 1 considering that the image of the preceding vehicle corresponding to the bit shift amount n ₂ is the most important. Then, considering that the bit shift amount n ₃ is important, the existence probability ξ is set to 0.
5. Finally, the existence probability の of the bit shift amount n ₁ is set to 0.2.

As described above, instead of employing any one of the plurality of bit shift amounts, weighting them and taking into account all the bit shift amounts allows the CCD sensor to obtain the bit shift amount. It is possible to comprehensively evaluate all the images of the preceding vehicle obtained. FIG. 7 shows an example of the existence probability ξ (r, θ) given to the bit shift amount obtained by a plurality of CCD sensor pairs. Indicates a scatter probability of 0.5, and a white circle indicates an existence probability of 0.2.

On the other hand, the degree of danger C _r (r, θ) set and stored as a function of a predetermined area in front of the vehicle increases as the azimuth angle θ decreases, and increases as the distance r from the vehicle decreases. This is a function having the characteristic of increasing the value, an example of which is shown in FIG. In the figure, the horizontal axis is the azimuth angle θ, and the vertical axis is the distance r from the vehicle. The risk level C _r (r, θ) is shown as an iso-line in FIG. 6, and 100, 95, 90, 70, 50 in the figure.
Are shown.

The CPU 24b uses the existence probability ξ (r, θ) calculated based on the bit shift amount n _i (θ) and the preset risk degree C _r (r, θ) in this manner. To evaluate _i (θ),

[0026]

(Equation 1)

The evaluation function F is calculated as follows. In the integration section, the azimuth angle θ is set to −30 degrees to 30 degrees (the center line in the longitudinal direction of the vehicle is set to 0 degrees), and the distance r is set to 0 m to 100 m in consideration of the resolution of the CCD sensor. As is clear from the equation, the evaluation function F is the bit shift amount n
_i (theta) is large, large risk C _r, and the existence probability ξ (r, θ) means that there is a vehicle ahead as the nearest vehicle is large, the value is larger. On the other hand, if the bit shift amount n _i (θ) is small, the degree of danger C _r (r, θ) is small, and the probability of existence ξ (r, θ) is small, the preceding vehicle is far from the host vehicle. Means that the value is smaller.

As described above, in order to reflect the relative positional relationship between the host vehicle and the preceding vehicle, the required acceleration is set in advance for the evaluation function F, for example, as shown in FIG. The required acceleration can be calculated according to the value of the evaluation function.

Step S104 is a step of calculating the required acceleration, and the CPU sets the required acceleration to the calculated required acceleration.
24b is a throttle actuator 26 or a brake actuator 2 via an output interface 24e.
8 to supply a control signal to perform throttle and brake control (S105).

FIG. 9 shows an example of the value of the evaluation function F and the change over time of the required acceleration calculated based on the evaluation function F. For comparison, a broken line indicates a calculated distance obtained from a conventional CCD sensor output and a required acceleration determined based on the calculated distance. The conventional distance output sometimes shows a discontinuous change as described above, but when the evaluation function F is used as in the present embodiment, a continuous result can be obtained. It is understood that the required acceleration also changes smoothly.

As described above, in this embodiment, the deviation amount,
It is to comprehensively evaluate the relative positional relationship with a plurality of vehicles ahead using the parameters of existence establishment and degree of danger, and it is more accurate than the conventional device that simply calculates the distance between vehicles from the amount of deviation and controls traveling. Travel control becomes possible.

[0032]

As described above, according to the vehicle travel control device of the present invention, the forward vehicle image obtained from the output of the CCD sensor is comprehensively evaluated, and the relative positional relationship with the forward vehicle is appropriately determined. Smooth running control can be performed by accurately grasping.

[Brief description of the drawings]

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

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

FIG. 3 is an operation flowchart of the embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a distance r and an azimuth angle θ in the embodiment.

FIG. 5 is a graph showing an example of a degree of correlation in the embodiment.

FIG. 6 is a graph showing an example of a degree of risk in the embodiment.

FIG. 7 is a graph showing an example of an existence probability in the embodiment.

FIG. 8 is a graph showing a relationship between an evaluation function and a required acceleration in the embodiment.

FIG. 9 is a graph showing a time change of the evaluation function and a time change of the required acceleration in the embodiment.

FIG. 10 is a diagram illustrating the principle of distance measurement using a pair of CCD sensors.

FIG. 11 is a diagram illustrating the principle of distance measurement using a pair of CCD sensors.

FIG. 12 is an explanatory diagram showing a vehicle arrangement of a host vehicle and a preceding vehicle.

FIG. 13 is an explanatory diagram showing a relationship between a CCD sensor output and a calculated degree of correlation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CCD sensor 16 Signal processing unit 24 Microcomputer 26 Throttle actuator 28 Brake actuator

Continuation of front page (58) Fields investigated (Int. Cl. ⁶ , DB name) B60K 31/00 F02D 29/02 G01C 3/06

Claims (1)

(57) [Claims] 1. A CCD sensor for photographing a preceding vehicle, a displacement calculating means for calculating a displacement at which a correlation degree of an image of the front vehicle obtained by the CCD sensor is minimized, and Existence probability calculating means for calculating the existence probability of the deviation amount based on the value of the correlation degree and inclination; storage means for storing a risk degree set in advance as a function of a predetermined area in front of the vehicle; And a control means for controlling a throttle or a brake based on a result of the evaluation, and a control means for controlling a throttle or a brake on the basis of the evaluation result.