JP3019686B2 - Inter-vehicle distance control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-vehicle distance control apparatus, and more particularly, to measuring an inter-vehicle distance with a preceding vehicle using a CCD camera and controlling the inter-vehicle distance to an appropriate distance so that the vehicle follows the preceding vehicle. To an inter-vehicle distance control device.

[0002]

2. Description of the Related Art Conventionally, CCDs have been used to image the front of a vehicle.
A camera is installed, a known image processing is performed on the captured image to detect an inter-vehicle distance with a preceding vehicle, and a relative speed is detected by differentiating the inter-vehicle distance. A device for controlling the vehicle speed has been devised. (Japanese Patent Application No. 3-264863).

This device is devised for the purpose of automatically controlling the acceleration and deceleration of a vehicle during a traffic jam, for example, and uses the inter-vehicle distance and the relative speed with respect to a preceding vehicle as a reference for executing the acceleration and deceleration control. Things.

[0004] That is, if the driving force and the braking force are controlled so as to maintain a constant inter-vehicle distance with a preceding vehicle during a traffic jam, the vehicle follows the preceding vehicle and automatic driving is realized. . When setting the braking force and the driving force so as to maintain the inter-vehicle distance at an appropriate distance, smooth running characteristics are secured by taking into account the relative speed with respect to the preceding vehicle.

[0005]

By the way, when detecting an inter-vehicle distance from an image captured using a CCD camera,
The narrower the angle of view of the CCD camera is, the more advantageous in detecting the distance between vehicles. This is because the narrower the angle of view, that is, the smaller the area to be imaged, the higher the density of the image, and the higher the resolution.

[0006] However, when it is assumed that the vehicle is automatically driven based on the image captured by the CCD camera, the CCD camera is required to ensure that the vehicle ahead is within the angle of view even when the road is curved. It is necessary to set the angle of view, and in practice, a certain limit is imposed on the resolution of the CCD camera.

In this case, in a situation where the inter-vehicle distance from the preceding vehicle, which is the object to be imaged, is short, the ratio of the preceding vehicle in the captured image is large, and as a result, the preceding vehicle is imaged with high density, so that there is no problem. However, when the inter-vehicle distance is relatively large, the ratio of the front vehicle in the captured image is low, and the accuracy of detecting the inter-vehicle distance obtained by processing the image data is degraded.

[0008] When the accuracy of detecting the inter-vehicle distance is deteriorated in this way, the accuracy of the relative speed obtained by differentiating the distance is greatly deteriorated, and the value is used as basic data for driving force and braking force control. If it is used, hunting occurs in control, and the control accuracy is remarkably deteriorated contrary to the purpose originally introduced as basic data in order to improve control accuracy.

On the other hand, the reason why the relative speed with respect to the preceding vehicle is used as basic data for driving force and braking force control is that delicate control at the time of approach cannot be executed based on only the inter-vehicle distance. When the inter-vehicle distance is ensured, it is not necessary to control the driving force and the braking force with high accuracy.

[0010] The present invention has been made in view of the above-mentioned point, and in a region where the inter-vehicle distance detected based on the image data captured by the CCD camera can secure appropriate accuracy, the inter-vehicle distance and the relative speed are set. Control the vehicle speed based on
An object of the present invention is to provide an inter-vehicle distance control device that solves the above-described problem by performing vehicle speed control based on only the inter-vehicle distance when the inter-vehicle distance exceeds the region.

[0011]

FIG. 1 is a block diagram showing the principle of an inter-vehicle distance control apparatus for achieving the above-mentioned object. That is, the above-mentioned object is as follows: an inter-vehicle distance detecting means 2 for detecting an inter-vehicle distance with a preceding vehicle based on image data captured by a CCD camera 1 as shown in FIG. And a relative speed detecting means 3 for detecting a relative speed with respect to a preceding vehicle based on the detected vehicle speed, and controlling the vehicle speed based on the detected vehicle distance and relative speed to maintain an appropriate vehicle distance. Determining means 4 for determining whether the inter-vehicle distance detected by the inter-vehicle distance detecting means 2 is within a range in which the relative speed detecting means 3 can detect a relative speed with appropriate accuracy, When the relative speed detection means 3 determines that the inter-vehicle distance detected by the inter-vehicle distance detection means 2 is within a range in which the relative speed detection means 3 can calculate the relative speed with an appropriate accuracy, the inter-vehicle distance and the relative speed are used. When the determination means 4 determines that the inter-vehicle distance detected by the inter-vehicle distance detection means 2 is not within a range in which the relative speed detection means 3 can detect the relative speed with appropriate accuracy. Is achieved by an inter-vehicle distance control device including a vehicle speed control means 5 for controlling the vehicle speed based only on the inter-vehicle distance.

Further, in the following distance control apparatus having the above-mentioned structure, the determining means 4 determines a distance between vehicles used as a criterion for determining whether or not the relative speed detecting means 3 can detect the relative speed with appropriate accuracy. The configuration in which the determination value is set in accordance with the angle of view of the CCD camera 1 is effective in fully utilizing the capability of the CCD camera.

[0013]

In the inter-vehicle distance control apparatus according to the present invention, the vehicle speed control means 5 controls the vehicle speed control only when the detection accuracy of the relative speed detection means 3 is appropriate in accordance with the result of the judgment by the judgment means 4. Adopt relative speed as basic data.

Therefore, if the inter-vehicle distance is too large to maintain the high detection accuracy with respect to the angle of view of the CCD camera 1, the vehicle speed is determined based on the inter-vehicle distance alone. Control will be executed,
There is no significant deterioration in control accuracy.

On the other hand, in an area where the inter-vehicle distance between the vehicle and the preceding vehicle is short and high control accuracy is required for the vehicle speed,
The determination means 4 determines that the detection accuracy of the relative speed detection means 3 is appropriate, and the vehicle speed control means 5
In addition to the inter-vehicle distance detected by the inter-vehicle distance detecting means 2, the relative speed detected by the relative speed detecting means 3 is also adopted as basic data for vehicle speed control. Therefore, in such a situation, the vehicle speed is controlled with high accuracy, and delicate inter-vehicle distance control is realized.

Further, the determining means 4 determines a determination value of the inter-vehicle distance used as a reference for determining whether or not the relative speed detecting means 3 can detect the relative speed with appropriate accuracy. When the setting is made in accordance with the angle of view, the determination as to whether or not to adopt the relative speed as the basic data of the vehicle speed control is performed in consideration of the characteristics of the CCD camera 1 as a result. CCD
The best vehicle speed control will be realized in a state where the capabilities of the camera are fully utilized.

[0017]

FIG. 2 shows an overall configuration diagram of an inter-vehicle distance control apparatus according to an embodiment of the present invention. The device shown in the figure has, in addition to a mechanism for controlling the vehicle speed by a normal brake operation and a throttle operation, a function of following the vehicle in front while keeping an appropriate inter-vehicle distance as a congestion mode, The function of controlling the vehicle speed with a small force and an easy operation is also used as a friendmatic mode (FM mode).

That is, the device shown in FIG. 1 shows a characteristic operation as an inter-vehicle distance control device when the congestion mode is selected. Hereinafter, the configuration will be described in detail.

In FIG. 2, an electronic control unit (control ECU) 10
Is a main part of the apparatus of this embodiment, which is constituted mainly by a microcomputer and realizes a part of the inter-vehicle distance detecting means 2, the relative speed detecting means 3, the determining means 4, and the vehicle speed controlling means 5.

The control ECU 10 includes a healthy person mode FM
A mode changeover switch 11 for mode switching, a vehicle speed sensor 12 for generating a pulse signal having a cycle corresponding to the vehicle speed, and an engine speed sensor 13 for generating a pulse signal having a cycle corresponding to the rotation speed of the internal combustion engine are connected. The set switch 14 is a switch for selecting the above-described traffic jam mode, and the operation lever 15 is a lever used for instructing acceleration / deceleration of the vehicle in the FM mode.

In FIG. 2, FL and FR and RL and RR indicate left and right front wheels and left and right rear wheels, respectively. Each of these wheels is independently provided with a brake mechanism 16 to 19 that operates by hydraulic pressure to brake each wheel. Note that these brake mechanisms 16 to 19 are configured to exert a braking force according to the supplied hydraulic pressure.

The left and right front wheels FL and FR are provided with hydraulic sensors 20 and 21 for detecting actual brake pressures actually supplied to the brake mechanisms 16 to 19, respectively. These oil pressure sensors 20 and 21 supply signals corresponding to the detected oil pressure to the control ECU 10.

The inter-vehicle distance control device according to the present embodiment is capable of adjusting the opening of the throttle valve 22 for controlling the amount of intake air supplied to the internal combustion engine by electronic control. Has been realized. Code 4
Numeral 0 indicates an electronic control throttle provided to realize such a mechanism. The electronic control throttle 40 is a DC motor (DC
-MOTOR) 41 as a drive source, and the operation lever 1
Control ECU 10 according to the acceleration / deceleration instruction amount supplied from
The opening of the throttle valve 22 is adjusted based on the throttle opening signal output from the controller.

That is, the throttle valve 22 is driven not only by the accelerator pedal 23 but also by the wire 24. Here, an end of the wire 24 is connected to a shaft 43 that rotates in conjunction with an electromagnetic clutch 42 to which rotation of the DC motor 41 is transmitted. Therefore, when the electromagnetic clutch 42 is connected to the DC motor 41,
As the wire rotates, the wire 24 opens and closes the throttle valve 22 and the opening of the throttle valve 22 fluctuates.

The electromagnetic clutch 42 operates in accordance with a control signal supplied from the control ECU 10, and the DC motor 41
And the throttle valve 22 are disconnected or connected.
That is, when the electromagnetic clutch 42 is disengaged, the throttle valve 22 no longer opens according to the rotation of the DC motor 41.

The electronically controlled throttle 40 has the configuration shown in FIG.
The opening degree sensor 4 detects the actual opening degree of the throttle valve 22 based on the rotation angle of the electromagnetic clutch 42 as shown in FIG.
4 are incorporated. The opening degree sensor 44 controls the detected actual opening degree data of the throttle valve 22 to control E.
It is transmitting to CU10.

On the other hand, reference numeral 50 in FIG.
An electronically controlled brake system which realizes a part of the vehicle speed control means 5 by electronically controlling the adjustment of the brake pressure supplied to 6 to 19 is shown. That is, in the inter-vehicle distance control device of the present embodiment, the above-described vehicle speed control means 5 is realized by the control ECU 10 appropriately driving the electronic control throttle 40 and the electronic control brake system 50.

Hereinafter, the structure of the electronic control brake system 50 will be described. In FIG. 2, reference numeral 51 denotes a brake booster (control B / B) which is a main part of the electronic control brake system 50. The control B / B 51 includes a negative pressure chamber 51a, a variable pressure chamber 51b, and a master cylinder 51c as shown in FIG.

The negative pressure chamber 51a communicates via a check valve 52 with a throttle valve downstream of an intake pipe (not shown) of the internal combustion engine, and is supplied with a negative intake pressure (E / G vacuum) during operation of the internal combustion engine. The check valve 52 is a one-way valve that allows only the flow from the negative pressure chamber 51a to the internal combustion engine. For this reason, even when the intake negative pressure of the internal combustion engine is increased to near the atmospheric pressure, it is possible to maintain an appropriate negative pressure in the negative pressure chamber 51a.

On the other hand, the transformation chamber 51b has two air introduction valves E
It communicates with the atmosphere through the ACVs 1 and 2 and the air filters 53 and 54, and communicates with the intake pipe of the internal combustion engine through the negative pressure introduction valve EACV 3 and the check valve 52. Therefore, the pressure in the transformation chamber 51b is equal to the atmospheric introduction valve EACV.
When the negative pressure introduction valve EACV3 is opened by closing the valves 1 and 2, the pressure becomes equal to the internal pressure of the negative pressure chamber 51a. When the EACV3 is opened and the EACV3 is closed, the pressure becomes atmospheric pressure.

The master cylinder 51c is a cylinder that supplies a hydraulic pressure corresponding to the pressure difference between the negative pressure chamber 51a and the variable pressure chamber 51b to each of the brake mechanisms 16-19. That is, the negative pressure chamber 5 is provided in the master cylinder 51c.
A piston for separating the pressure chamber 1a from the transformation chamber 51b is provided, and when air is introduced into the transformation chamber 51b, a thrust is generated in the piston from the transformation chamber 51b to the negative pressure chamber 51a.

Then, the thrust is converted into a hydraulic pressure via a push rod connected to the piston, and is supplied to each of the brake mechanisms 16 to 19 as a boosted brake pressure. On the other hand, when the inside of the variable pressure chamber 51b is maintained at a negative pressure, no force acts on the piston in the master cylinder 51c. For this reason, the brake mechanisms 16 to 19 are not supplied with a brake pressure high enough to drive them, and no braking force acts on each wheel.

In this embodiment, the negative pressure chamber 5
1 a communicates with the variable pressure chamber 51 b via a negative pressure control valve (VSV) 55. Therefore, for example, when the healthy person mode is selected, the VSV 55 is opened to maintain the internal pressure of the negative pressure chamber 51a and the internal pressure of the variable pressure chamber 51b at the same pressure. The boost function does not operate, and even if the operation lever 15 is erroneously operated, the brake boost function does not operate.

Reference numeral 25 indicates a brake pedal provided corresponding to the normal person mode. This brake pedal 2
5 is the master cylinder 26 for the brake pedal 25
And is supplied to the high select device 56 of the electronic control brake system 50. Here, the high select device 56 uses the higher one of the hydraulic pressures supplied from the two master cylinders 26 and 51c to each of the brake mechanisms 16 to
19 is a device for transmitting.

A known anti-lock brake system (ABS) is incorporated in the brake system of this embodiment, and the hydraulic pressure supplied from the high select device 56 is applied to each brake mechanism 16 through the ABS mechanism 27. 19
Supplied to

The control ECU 10 also includes a stop lamp (STOP lamp) 28 which is lit when the brake mechanisms 16 to 19 are operated and the vehicle is being braked, and whether the current mode is the healthy person mode or the FM mode. A mode display lamp 29 for displaying whether or not there is, and a set lamp 30 for displaying the ON / OFF state of the set switch 14, that is, the selection status of the traffic jam mode, are connected. These lamps function as indicators for the driver, and inform the driver and the like of the state of the control ECU 10.

Further, the control ECU 10 according to the present embodiment is provided with a predetermined distance D (for example, 130 mm in the present embodiment) up and down.
A CCD camera 60 provided with two CCD sensors which are arranged shifted only by one is connected. The CCD camera 60 supplies image data of images captured by the two CCD sensors to the control ECU 10, and the control ECU 10 determines the distance between the vehicle and the vehicle existing in front of the vehicle based on the two image data. The distance, the relative speed, and the like are calculated, and the inter-vehicle distance control is executed based on the result.

When arranging the CCD camera 60 to image the front of the vehicle, it is necessary to consider the angle of view α of the CCD camera 60 as shown in FIG. CC
This is because the area that can be imaged by the D camera 60 is limited to an angle of view α corresponding to the field of view, and image data cannot be obtained for an area beyond this.

Accordingly, in an apparatus such as the inter-vehicle distance control apparatus according to the present embodiment, which is intended to realize automatic driving related to vehicle speed during a traffic jam, when a vehicle approaches a curve or when a preceding vehicle travels in a traveling lane. When the line is changed, α needs to be set wide enough to keep the preceding vehicle within the angle of view.

Here, the angle of view α of the CCD camera 60 is, as shown in FIG.
This value is determined by the focal length f of the lens 62 provided to oppose the CD sensor 61. In this case, the following equation is an equation representing the relationship between the angle of view α, the width L, and the focal length f.

F = (L / 2) · cot (α / 2) (1) That is, when the width L of the CCD sensor 61 is fixed,
The more the lens 62 having a shorter focal length f is used, the larger the angle of view α becomes. In order to secure the angle of view α required from the above viewpoint, an appropriate distance is secured as the focal length f of the lens 62. It is necessary.

By the way, in the present embodiment, in order to obtain the inter-vehicle distance, two CCD sensors 61 are arranged at two places separated by a predetermined distance D up and down, respectively.
A method of calculating an inter-vehicle distance DST to a vehicle based on two image data obtained by imaging a vehicle ahead of the vehicle with the D sensor 61 as a viewpoint is adopted.

That is, when the distance between bits corresponding to the distance between pixels of the CCD sensor 61 is Δx (13.4 μm in the present embodiment), the two CCD sensors 61
Assuming that the same object having an image formed thereon is imaged at a position shifted by n bits, DST: D =
f: (Δx · n) holds, and therefore, the following distance DST can be expressed by the following equation.

DST = (f · D) / (Δx · n) (2) In this case, when the distance D between the CCD sensors 61 and the bit distance Δx of the CCD sensor 61 are considered to be fixed, A vehicle existing ahead by the inter-vehicle distance DST is detected with a larger bit shift n as the focal length f of the lens 62 is larger.

That is, comparing the case where the focal length of the lens 62 is f and the case where it is twice as large as 2f, the same inter-vehicle distance DST is DST = (f · f D) / (Δx · n) or DST = (2f · D) / (Δx · 2n).

Here, in each of these cases, the detection accuracy of the CCD sensor 61, that is, the least significant bit (LSB)
When the focal length is f, and when 2f
The following values are obtained for each of the cases:

LSB (f) = (f · D) / (Δx · n) − (f · D) / (Δx · n + 1) = (f · D / Δx) / (n · (n + 1)) (3) LSB (2f) = (2f · D) / (Δx · 2n) − (2f · D) / (Δx · 2n + 1) = (f · D / Δx) / (n · (2n + 1)) (4) As is clear from the above equations (3) and (4), LSB
(F) and LSB (2f) are both functions of n, and the smaller the value thereof, that is, the shorter the inter-vehicle distance DST, the greater the value of LS.
As B, a large value is obtained. In addition, the following relationship always holds between LSB (f) and LSB (2f).

LSB (f)> LSB (2f) (5) That is, when measuring the inter-vehicle distance DST using the CCD camera 60, the shorter the DST and the more the lens 62
As the focal length f of the camera becomes longer, a smaller LSB can be obtained, and the inter-vehicle distance can be detected based on higher accuracy. That is, from the viewpoint of ensuring the detection accuracy of the inter-vehicle distance, it is desirable that the focal length f be set as long as possible, and in this sense, the focal length f has a characteristic contrary to the above-described securing of the angle of view α. .

Therefore, conventionally, in an apparatus for detecting the inter-vehicle distance using the CCD camera 60 and automatically controlling the vehicle based on the detection result, the focal point of the lens 62 is determined as a harmony point between these two requirements. The distance f has been set.

Incidentally, in order to appropriately follow the preceding vehicle in a traffic congestion and travel, it is advantageous to use not only the inter-vehicle distance but also the relative speed with respect to the preceding vehicle as basic data for vehicle speed control. This is because, even when the same inter-vehicle distance is ensured, the content of the vehicle speed control naturally differs depending on whether the distance is far or close.

In other words, in a traffic jam where starting and stopping are repeated, an appropriate inter-vehicle distance is required to stop the vehicle and to start the vehicle before the inter-vehicle distance is unduly increased. Not only that, but also the relative speed must be used as basic data for vehicle speed control.

In this case, the differential value DDST of the inter-vehicle distance DST with respect to the preceding vehicle corresponds to the relative speed with respect to the preceding vehicle. When the DST is detected in advance as in this embodiment, the relative speed DDST is calculated. Can be obtained very easily. For this reason, conventionally, in a device having such a configuration, a configuration in which vehicle speed control is performed to maintain an appropriate inter-vehicle distance based on the inter-vehicle distance and the relative speed has been generally adopted. Incidentally, as described above, the detection accuracy of the inter-vehicle distance DST by the CCD camera 60 is disadvantageous as the DST to be detected is longer, and
In view of the necessity of securing the angle of view α to an appropriate level, the restriction of the focal length f being fixed, and the like, it is avoided that the detection accuracy is deteriorated in an area where the inter-vehicle distance DST is large to some extent. I can't. For this reason, when executing the vehicle speed control, in consideration of the fact that the inter-vehicle distance DST is secured to some extent and there is no possibility of a rear-end collision, the vehicle speed control is performed after approving such a detection error.

However, since the relative speed DDST is a value obtained by differentiating the inter-vehicle distance DST, a large detection error occurs in the DDST under such circumstances, and the relative speed DDST is determined based on the inter-vehicle distance DST and the relative speed DDST as described above. If the vehicle speed control is continued, hunting may occur in control.

The inter-vehicle distance control device according to the present embodiment is designed to eliminate such an adverse effect when the relative speed DDST is used as basic data for vehicle speed control.
In a region where the DST detection accuracy cannot maintain appropriate accuracy, the vehicle speed control is performed based only on the inter-vehicle distance DST.

Hereinafter, a control ECU for realizing such a function will be described.
The specific processing contents executed by 10 will be described with reference to the flowchart of the congestion control subroutine shown in FIG. It should be noted that the routine shown in the figure is a routine that is executed every predetermined time when the congestion mode is selected by the set switch 14.

As shown in FIG. 4, when this routine is started, first, in step 100, a target inter-vehicle distance is calculated in accordance with the current vehicle speed. Here, the target inter-vehicle distance is
A vehicle distance required for the vehicle to stop, in the present embodiment, a braking distance obtained by multiplying a predetermined constant K ₁ of the detected value of the vehicle speed sensor 12, should be ensured when stopping It is determined as the sum of the stopping distance.

When the target inter-vehicle distance is obtained in this way,
Proceeding to step 102, it is determined whether or not the inter-vehicle distance DST obtained as described above (see the above equation (2)) is equal to or greater than a predetermined value based on the image captured by the CCD camera 60. This predetermined value is set when the CCD camera 60 is set to the required angle of view α.
This is a value experimentally set as a boundary value at which the relative speed DDST can be calculated with appropriate accuracy based on the detected inter-vehicle distance DST.

Accordingly, in an area where the distance DST ≧ the predetermined value does not hold, appropriate accuracy can be ensured for the relative speed DDST calculated based on the DST. On the other hand, in an area where the following distance DST ≧ predetermined value is satisfied, there is no guarantee on the accuracy of the relative distance DDST, and if the value is used as basic data for vehicle speed control, hunting may occur. become.

For this reason, in this routine, if the inter-vehicle distance DST is far enough to satisfy the condition shown in step 102, the process proceeds to step 104 to execute the vehicle speed control based only on the inter-vehicle distance DST. If the inter-vehicle distance DST is close enough that the condition of step 102 is not satisfied, the inter-vehicle distance DST and the relative speed DDS
Steps 106 and 1 to execute vehicle speed control based on T
08 to calculate the required values for the respective driving forces.

[0060] In this case, the difference between the inter-vehicle distance DST and the target inter-vehicle distance detected in step 104, seeking driving force is multiplied by a predetermined constant K _2. That is, when the actual inter-vehicle distance DST is excessively large with respect to the target inter-vehicle distance set as the distance at which the vehicle can safely stop, a positive driving force is required in accordance with the surplus. Conversely, when the actual inter-vehicle distance DST is too small relative to the target inter-vehicle distance, a negative driving force, that is, a braking force is required according to the shortage.

On the other hand, in step 106, the difference between the inter-vehicle distance DST detected this time and the inter-vehicle distance DST detected last time is obtained, and the value is divided by the sampling time required from the time of the previous detection to the time of this detection. Gives the relative speed D
This is the step of obtaining the DST.

Step 108 is a step of calculating the driving force required of the vehicle based on the relative speed DDST and the inter-vehicle distance DST. in this case,
In this routine, the vehicle distance component obtained by multiplying the difference between the case as well as inter-vehicle distance DST and target inter-vehicle distance constant K ₃ in step 104, determined by multiplying the constant K ₄ to the relative speed DDST The value obtained by adding the relative speed components is used as the driving force.

As a result, the driving force is equal to the actual inter-vehicle distance DST.
Is set to a tendency to approach the target inter-vehicle distance, and is larger when the sign of the relative speed is positive, that is, when the inter-vehicle distance tends to separate, and when the relative speed is negative, that is, when the inter-vehicle distance approaches. If there is a tendency, the driving force is corrected to be smaller, and a driving force that realizes realistic vehicle speed control that can ensure high safety when approaching is set.

As described above, the method according to the inter-vehicle distance is
After each driving force is calculated, the routine proceeds to step 110, where it is determined whether the driving force is positive or negative. This is because it is necessary to execute throttle control in order to secure a positive driving force, and to perform brake control in order to secure a negative driving force, that is, a braking force. .

If the driving force> 0 is satisfied, the routine proceeds to step 200, where the required throttle opening TTHL is set according to the magnitude of the driving force, and the throttle control is executed based on the TTLL to execute the current throttle opening. Is completed. On the other hand, if the driving force> 0 is not established, step 300
To the required brake pressure TBP according to the magnitude of the braking force.
L is set, and the brake control is executed based on the TBPL, and the current process ends.

As a result, in a situation where the inter-vehicle distance DST is relatively short during traffic congestion, the target inter-vehicle distance is finally set based on the inter-vehicle distance DST and the relative distance DDST. In addition, at the time of separation, an appropriate driving force is set promptly to match the actual inter-vehicle distance DST with the target inter-vehicle distance.

Then, the inter-vehicle distance DST exceeding a predetermined level
Is ensured, the relative speed DDST, which may be accompanied by a significant decrease in accuracy, is excluded from the basic data of the vehicle speed control. Although the accuracy is rough, the vehicle speed control is continued with sufficient accuracy to follow the preceding vehicle without hunting in control.

Hereinafter, in order to realize the processing of steps 200 and 300 in the apparatus shown in FIG.
Will be described.

FIG. 5 shows a flowchart of an example of a throttle control subroutine specifically illustrating the processing contents of the above step 200. Hereinafter, the processing content of the throttle control in the present embodiment will be described with reference to FIG.

In this embodiment, the throttle valve 2
A feedback system is configured using the opening sensor 44 that detects the actual opening of the second motor, and the DC motor 41 is driven by proportional-integral-derivative control (PID control).

That is, when the throttle control routine shown in FIG. 5 is started, first, at step 202, the throttle opening instruction amount TTLL that can realize the driving force calculated as described above is detected.

When the detection of TTLL is completed, step 20
The program proceeds to step 4, wherein the actual throttle opening THR detected by the opening sensor 44 is read, and the deviation of the throttle opening with respect to the indicated amount is calculated according to the following equation: TTH _(t) = TTHL-THR.

[0073] Step 206, of the opening degree instruction signal is supplied to the DC motor 41 is a step of obtaining a basic value of the differential control components, throttle deviation TTH current throttle deviation TTH and _(t) in the previous control cycle _(t By calculating the difference from _-1) , a differential amount ΔTTH of the throttle deviation is calculated.

In step 208, the DC motor 41
Is a step of obtaining a basic value for calculating an integral control component of the opening degree instruction signal supplied to the throttle opening signal, and adding the current throttle deviation TTH _(t) to the integral value of the throttle deviation up to the previous time to obtain an integral amount of ΔTTH ∫ Calculate ΔTTH.

As described above, the differential control component of the opening degree instruction signal,
After calculating the integral control component, the process proceeds to step 210.
Proportional gain G set experimentally in advance_P, Integral gay
G _I, Differential gain G_DThe basic control using
Calculate the quantity TTHI.

TTHI = G_P・ TTH_(t)+ G_I・ ∫T
TH_(t)+ G_DΔTTH Then, when the basic control amount TTHI has been calculated,
Proceed to step 212 to change the battery voltage V_BCorrection for fluctuation of
I do. The voltage of the battery mounted on the vehicle is
Throttle valve fluctuates significantly depending on rolling conditions, etc.
This is because it is necessary to precisely control the opening degree of the opening 22.
It should be noted that the control ECU 10 of the present embodiment device determines that the battery voltage V
_BCorrection coefficient K for_VBIs provided as a map in advance.
(Refer to FIG. 6), this map is_BRefer to
Correction coefficient K required by the rotor _VBIs calculated.

Then, the actual control amount is calculated by multiplying the basic control amount TTHI calculated in step 210 by this correction coefficient K _VB, and the value is stored as the final opening instruction amount TTHI ( Step 214).

Thereafter, in step 216, a duty ratio corresponding to TTHI is calculated, and in step 218, a drive signal having the duty ratio is output to the DC motor 41, and the current processing ends.

As described above, in the apparatus of this embodiment,
When a positive driving force is required, high-precision throttle control by PID control is executed in accordance with a target throttle opening TTHL set to realize the driving force, and vehicle speed control is appropriately realized. become.

FIG. 7 is a flowchart showing step 300 in FIG.
3 is a flowchart of an example of a brake control subroutine specifically showing the processing of FIG. This routine controls the electric control brake system 50 based on the target brake pressure TBPL set in accordance with the above-mentioned braking force when a braking force is required to realize the vehicle speed control. This is a well-known process executed by the control ECU to supply an appropriate brake pressure to the control ECU. Hereinafter, the specific contents will be described.

As shown in FIG. 2, the inter-vehicle distance control device according to the present embodiment utilizes the differential pressure between the internal pressure of the negative pressure chamber 51a and the internal pressure of the variable pressure chamber 51b of the control brake booster 51, as shown in FIG. To increase the brake pressure supplied to. Therefore, the negative pressure chamber 51a and the variable pressure chamber 51
The greater the pressure difference from b, the greater the actual brake pressure supplied to the brake mechanisms 16 to 19.

On the other hand, EACVs 1 to 3 for controlling conduction between the variable pressure chamber 51b and the atmosphere and the intake pipe are control valves for changing the opening area of the conduction portion in accordance with a flow rate instruction signal supplied from the control ECU 10. For this reason, even if the conduction area is the same, the atmosphere introduction valve EAC depends on whether the negative pressure stored in the transformation chamber 51b, that is, the intake negative pressure is large or small.
A difference occurs in the amount of air introduced when V1 and V2 are opened.

Similarly, when the negative pressure introduction valve EACV3 is opened while the atmosphere is being introduced into the transformation chamber 51b,
The amount of air flowing out of the variable pressure chamber 51b to the intake pipe varies depending on the magnitude of the intake negative pressure.

That is, in order to make the operation feeling of the operation lever 15 by the driver equal to the braking force exerted by each of the brake mechanisms 16 to 19, that is, the actual brake pressure supplied from the master cylinder 51c, EACV1 to EACV3 are required. Is required to be able to control the amount of air introduced into the variable pressure chamber 51b when the valve is opened or the amount of air flowing out of the variable pressure chamber 51b regardless of the magnitude of the intake negative pressure of the internal combustion engine.

Therefore, in this embodiment, the intake negative pressure generated in the intake pipe of the internal combustion engine is detected, and the opening areas of the EACVs 1 to 3 when the EACVs 1 to 3 are opened are determined based on the detected intake negative pressure. It is to be corrected.

At step 302, the engine speed NE is detected from the output signal of the speed sensor 4, and at step 3
The reason why the actual throttle opening THR is detected based on the output signal of the throttle opening sensor 24 in 04 is to realize such processing.

That is, the intake negative pressure E / GB of the internal combustion engine can be grasped as a function of the engine speed NE and the throttle opening THR. It is known that the lower the NE and the smaller the THR, the lower the pressure. ing. For this reason, in the present embodiment, a map as shown in FIG.
When the NE and THR are detected as described above, the process proceeds to step 306, where NE and THR are stored.
Is used to search the map for the intake negative pressure E / GB of the internal combustion engine.

By the way, when braking the vehicle,
The lower the vehicle speed, the greater the shock due to the braking effect. In general, during low-speed traveling, fine adjustment of braking force is often required rather than strong braking force. Therefore, in order to make the driver's operational sensation correspond to the braking sensation of the vehicle in the system of the present embodiment, it is necessary to perform correction according to the vehicle speed.

Therefore, in the present embodiment, the above steps
In step 306, the intake negative pressure E / GB of the internal combustion engine was estimated.
Proceed to step 308 to correct for the vehicle speed.
The vehicle speed V based on the output signal of the vehicle speed sensor 12._WCalculation
Go out. And, in this way, the intake negative pressure E / GB and
Vehicle speed V_WAfter estimating the E / GB and V_WTo
To introduce a predetermined amount of air into the transformation chamber 51b based on the
Correction gain G_BAnd G _VWAsk for.

That is, when the atmosphere introduction valves EACV1 and EACV2 are opened to introduce the atmosphere into the transformation chamber 51b,
The amount of air introduced into the chamber is a function of the opening areas of the EACVs 1 and 2 and the pressure in the variable pressure chamber 51b before the EACVs 1 and 2 are opened, that is, the intake negative pressure E / GB of the internal combustion engine. The larger the opening area of 2, the lower the intake negative pressure E / GB, the more air is introduced.

Therefore, in order to introduce a predetermined amount of air into the variable pressure chamber 51b regardless of the magnitude of the intake negative pressure E / GB,
The larger the intake negative pressure E / GB, the smaller the opening areas of the EACVs 1 and 2 need to be corrected. Therefore, in the present embodiment, a map as shown in FIG.
Stored in 10, and calculates the correction gain G _B by searching this map in the intake negative pressure E / GB estimated in step 306 in step 310.

[0092] In addition, the relationship between vehicle speed V _W and the braking force, it is necessary to suppress the boost force of the control B / B as the vehicle speed V _W is slow as described above. That is, a large amount of air needs to be introduced into the variable pressure chamber 51b during high-speed traveling, and a small amount of air needs to be introduced into the variable pressure chamber 51b during low-speed traveling. Therefore, in the present embodiment, the relationship between the vehicle speed V _W and the correction gain G _VW as shown in FIG.
In step 312, the correction gain G _VW is obtained by searching this map with the vehicle speed V _W.

In step 314, the difference ΔBP between the target brake pressure TBPL set to realize the braking force calculated in the routine shown in FIG. 4 and the actual brake pressure detected by the oil pressure sensors 20 and 21 is detected. I have. Here, the sign of ΔBP is positive because the target brake pressure TB
This is a case where the actual brake pressure BPR is low with respect to PL, that is, a case where a stronger braking force is required. Also Δ
The sign of BP is not positive because the target brake pressure TBP
This is a case where L is lower than or equal to the actual brake pressure BPR, that is, a case where a reduction in the braking force is required.

Meanwhile, the actual brake pressure BPR supplied to the brake mechanisms 16 to 19 indicates a pressure corresponding to the differential pressure generated between the negative pressure chamber 51a and the pressure reducing chamber 51b as described above. Therefore, as the actual brake pressure BPR increases, the pressure difference between the negative pressure chamber 51a and the variable pressure chamber 51b increases, that is, the pressure in the variable pressure chamber 51b should be closer to the atmospheric pressure.

On the other hand, when the air introduction valves EACV1 and EACV2 are opened, the amount of air introduced into the transformation chamber 51b per unit time becomes smaller as the pressure in the transformation chamber 51b becomes closer to the atmospheric pressure. On the other hand, when the negative pressure introduction valve EACV3 is opened to supply the intake negative pressure into the variable pressure chamber 51b, the amount of air flowing out of the variable pressure chamber 51b increases as the pressure in the variable pressure chamber 51b approaches the atmospheric pressure, that is, the actual amount of air. The larger the brake pressure BPR, the larger the amount.

Therefore, in order to make the actual braking force change correspond to the driver's operational feeling, it is necessary to correct the actual brake pressure BPR at each moment. That is,
When the driver intends to increase the braking force, the larger the actual brake pressure BPR at that time is, the larger the opening area of the EACVs 1 and 2 at the time of opening the valve is, and the driver intends to reduce the braking force. In this case, as the actual brake pressure BPR increases, the opening area of the EACV 3 at the time of opening the valve needs to be corrected smaller.

Therefore, in this embodiment, if ΔBP is detected in step 314, step 316 is executed.
Then, it is determined whether or not the value is a positive value. And
If ΔBP> 0, the routine proceeds to step 318, where a correction gain G _BPU for increasing the actual brake pressure BPR is calculated.
The driver if ΔBP ≦ 0, it is determined to have an intention to weaken the braking power, and to calculate the correction gain G _BPD for decompressing the actual brake pressure BPR proceeds to step 320.

In this embodiment, each correction
Gain G_BPU, G_BPDIs the actual brake pressure B as described above.
Focusing on the value determined as a function of PR,
In the control ECU 10, G shown in FIGS._BPUor
Is G_BPDAnd a map showing the relationship between
Then, this is searched with the actual brake pressure BPR and G_BPUAnd G
_BPDYou are seeking.

In this manner, the response to the intake negative pressure of the internal combustion engine is reduced.
Correction gain G_B, Correction gain G for vehicle speed_VW, Real b
Correction gain G for rake pressure BPR_BPUOr G_BPDTo
After the calculation, the process proceeds to step 322, where these correction gay
And the total correction gain G_BRKAsk for. In addition, this
If ΔBP> 0 in step 628 in the above case,
If it is determined, the total correction gain G_BRK= G_B* G_VW
* G_BPUAnd it is determined that ΔBP ≦ 0.
Then, the total correction gain G_BRK= G_B* G_VW* G _BPDTona
You.

In the next steps 324 and 326, the opening areas TAF1 to TAF3 of the EACVs 1 to 3 to be secured to allow a desired amount of air to flow through the EACVs 1 to 3 are calculated using the total correction gain G _BRK . Here, TAF1 = TAF
The reason that 2 = TAF / 2 and TAF3 = TAF is that the introduction of the atmosphere into the transformation chamber 51b is performed by the atmosphere introduction valve EA.
This is because the intake negative pressure is performed only from the negative pressure introduction valve EACV3, while the control is performed simultaneously from CV1 and CV2.

In order to realize a braking force that matches the driver's operational feeling, the opening areas TAF1 to TAF3 of the EACVs 1 to 3 are to be realized.
Is obtained by integrating the difference between the driver's requested brake pressure TBPR and the actual brake pressure BPR, that is, ΔBP calculated in step 314 and the total correction gain G _BRK ( Step 3
24).

Further, as shown in the characteristic diagram of FIG. 12, the atmosphere introduction valves EACV1, EACV2 and the negative pressure introduction valve 3 have a characteristic of opening with an opening area TAF corresponding to the current I of the supplied flow control signal. Have. Therefore, when the opening area of each of the introduction valves EACV1 to 3 is calculated in step 324, the process proceeds to step 328, and the opening area TAF is calculated.
Calculate the current values I _{1 to} I ₃ to be supplied in order to realize 1 to ₃ .

In step 328, when it is desired to increase the braking force, for example, based on the target brake pressure TBPL, the currents I ₁ and I ₂ are supplied to the air introduction valves EACV1 and EACV2, respectively, and the braking force is reduced. the current processing is terminated by supplying a current I ₃ relative to the negative pressure introducing valve EACV3 if you want.

As described above, in the following distance control apparatus of the present embodiment, the target brake pressure TBPL set to realize the braking force required for the vehicle speed control is appropriately supplied to each of the brake mechanisms 16 to 19. Various considerations have been made to achieve safe and smooth inter-vehicle distance control under high-precision vehicle speed control.

[0105]

As described above, according to the first aspect of the present invention, in a situation where the inter-vehicle distance to the preceding vehicle is relatively short and high control accuracy is required when automatically controlling the vehicle speed,
The vehicle speed can be controlled with high accuracy using the relative speed in addition to the inter-vehicle distance as basic data. If the distance between the vehicles is relatively long and the accuracy of detecting the relative speed cannot be properly secured, the control accuracy is significantly reduced by performing the vehicle speed control based only on the distance between the vehicles.

As described above, the inter-vehicle distance control apparatus according to the present invention can control the accuracy of the inter-vehicle distance detection by the CCD camera in an area where the inter-vehicle distance is relatively long. Accuracy is ensured, and appropriate control accuracy can be ensured in the entire inter-vehicle distance region without requiring a high detection accuracy for the CCD camera.

According to the second aspect of the present invention, whether the detected relative distance is used as basic data for vehicle speed control is determined.
The vehicle speed is set based on the angle of view of the CCD camera, that is, the detection accuracy with respect to the inter-vehicle distance of the CCD camera. Therefore, the vehicle speed is based on the inter-vehicle distance and the relative speed within the longest inter-vehicle distance allowed according to the resolution of the CCD camera. The control is executed, and there is a feature that highly accurate vehicle speed control can be realized in a state where the capability of the CCD camera is sufficiently utilized.

[Brief description of the drawings]

FIG. 1 is a principle diagram of an inter-vehicle distance control device according to the present invention.

FIG. 2 is an overall configuration diagram of an inter-vehicle distance control device according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining the relationship between the angle of view α of the CCD camera and the accuracy of detecting the distance between vehicles.

FIG. 4 is a flowchart of an example of a traffic jam control routine executed by a control ECU.

FIG. 5 is a flowchart of an example of a throttle control subroutine executed by a control ECU.

FIG. 6 is a map for _{obtaining a} battery correction coefficient K _VB in a throttle control subroutine.

FIG. 7 is a flowchart of an example of a brake control subroutine executed by a control ECU.

FIG. 8 is a characteristic diagram showing a relationship between a throttle opening degree THR and an engine speed NE of the internal combustion engine and an intake negative pressure E / GB.

In Figure 9 a braking control subroutine correction gain G _B
It is a map for obtaining.

FIG. 10 shows a correction gain G in a brake control subroutine.
It is a map for _{obtaining VW} .

11 is a map for obtaining a pressure increase correction gain G _BPU and reduced pressure during correction gain G _BPD in the brake control subroutine.

FIG. 12 is a characteristic diagram showing the relationship between the opening area TAF and the current I of the flow rate instruction signal when the atmosphere introduction valve and the negative pressure introduction valve are opened.

[Explanation of symbols]

 1,60 CCD camera 2 Inter-vehicle distance detection means 3 Relative speed detection means 4 Judgment means 5 Vehicle speed control means 10 Control ECU 11 Mode switch 14 Set switch 15 Operating lever 16-19 Brake mechanism 20,21 Oil pressure sensor 22 Throttle valve 23 Accelerator Pedal 25 Brake pedal 40 Electronic control throttle 50 Electronic control brake system 51 Control brake booster 51a Negative pressure chamber 51b Transformation chamber 51c Master cylinder EACV1, 2 Atmospheric introduction valve EACV3 Negative pressure introduction valve

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-104977 (JP, A) JP-A-5-104993 (JP, A) JP-A-5-106475 (JP, A) JP-A-4-104 248489 (JP, A) JP-A-4-276585 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60K 31/00 F02D 29/02 301 G01C 3/06 G01C 11/00

Claims (2)

(57) [Claims] An inter-vehicle distance detecting means for detecting an inter-vehicle distance with a preceding vehicle based on image data captured by a CCD camera, and a relative speed with respect to a preceding vehicle based on the inter-vehicle distance detected by the inter-vehicle distance detecting means. An inter-vehicle distance control device that includes a relative speed detecting means for detecting, and maintains an appropriate inter-vehicle distance by controlling the vehicle speed based on the detected inter-vehicle distance and the relative speed. Determining means for determining whether the distance is within a range in which the relative speed detecting means can detect relative speed with appropriate accuracy; and determining the distance between the vehicles detected by the following distance detecting means, When the speed detecting unit determines that the relative speed is within the range in which the relative speed can be calculated with appropriate accuracy, the vehicle speed is controlled based on the inter-vehicle distance and the relative speed. Vehicle speed control means for controlling the vehicle speed based only on the inter-vehicle distance when it is determined that the inter-vehicle distance detected by the separation detection means is not within a range in which the relative speed detection means can detect the relative speed with appropriate accuracy. An inter-vehicle distance control device comprising: 2. The method according to claim 1, wherein the determining unit determines a value of the inter-vehicle distance used as a reference for determining whether the relative speed detecting unit can detect the relative speed with appropriate accuracy.
2. The inter-vehicle distance control device according to claim 1, wherein the setting is made according to the angle of view of the CD camera.