JPH069941B2 - Inter-vehicle distance control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inter-vehicle distance control device for maintaining an inter-vehicle distance between a preceding vehicle and a preceding vehicle at a safe inter-vehicle distance by controlling an own vehicle speed to an acceleration control or a deceleration control, in particular, The present invention relates to an inter-vehicle distance control device that can appropriately perform deceleration control.

[Technical background of the invention and its problems] In a vehicle-to-vehicle distance control device that maintains a vehicle-to-vehicle distance to a preceding vehicle at a safe vehicle-to-vehicle distance according to a vehicle speed, the vehicle-to-vehicle distance is less than the safe vehicle-to-vehicle distance due to deceleration of the vehicle in front. If the vehicle becomes too short and approaches the preceding vehicle too much, the brake is applied to reduce the speed of the host vehicle so as to continue safe follow-up traveling to the preceding vehicle.

By the way, in this case, a device is proposed in which a predetermined reference deceleration is set for deceleration, and the vehicle speed is decelerated so as to match the reference deceleration to achieve smooth deceleration. (Japanese Patent Laid-Open No. 52-12
1238). However, in this conventional device, since the deceleration operation is performed only by the braking operation, when an attempt is made to match the vehicle speed with the predetermined reference deceleration,
Inevitably, intermittent braking operations such as applying and releasing the brakes must be frequently performed, and the hunting phenomenon resulting from this is not always sufficient to achieve smooth deceleration. In addition, such deceleration operation
Regardless of the driving condition of the engine, only the brake is used, so the energy generated by the engine is wasted,
There is a risk that fuel efficiency will deteriorate.

[Object of the Invention] The present invention has been made in view of the above, and an object of the present invention is to provide an inter-vehicle distance control device capable of performing efficient and appropriate deceleration without causing discomfort to an occupant. To provide.

[Summary of the Invention] In order to achieve the above object, an inter-vehicle distance between a host vehicle and a preceding vehicle is detected, and the host vehicle is accelerated or decelerated in accordance with a change in the inter-vehicle distance to cause the host vehicle to be ahead of the preceding vehicle. In a vehicle-to-vehicle distance control device that causes a vehicle to follow a predetermined vehicle-to-vehicle distance, the present invention determines deceleration detecting means 1 for detecting the deceleration of the host vehicle and whether or not the detected vehicle-to-vehicle distance is shorter than the predetermined vehicle-to-vehicle distance. Distance determining means 3, a deceleration determining means 5 for determining whether or not the deceleration detected by the deceleration detecting means is smaller than a predetermined reference deceleration, and the distance determining means 3
When it is determined that the inter-vehicle distance is shorter than the predetermined inter-vehicle distance, and when the deceleration determination unit 5 determines that the deceleration is smaller than the reference deceleration, the deceleration and the reference deceleration are Calculation means 7 for calculating a ratio or a difference
And a first braking portion control means 9 for controlling the opening of the throttle valve in a direction of closing the opening when the calculated value of the ratio or difference is within a predetermined first range, When the value of the ratio or difference is in a predetermined second range that is larger than the first range, the opening of the throttle valve is controlled to be closed from the current opening, and the gear ratio of the transmission is changed. Second braking portion control means 11 for performing downshift control so as to change to a gear ratio larger than the current gear ratio,
When the value of the ratio or the difference is in a predetermined third range that is larger than the second range, the opening of the throttle valve is controlled to be closed from the current opening to change the gear ratio of the transmission. And a third braking portion control means 13 for controlling downshifting so as to change to a gear ratio larger than the current gear ratio and controlling the brake actuator so as to increase the braking force of the wheels. .

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention. In the figure, the output of the engine 21 is the transmitter 23,
It is transmitted to the left and right rear wheels 28L and 28R via the propeller shaft 25 and the differential gear 27. 29 is an ignition switch, 31 is an accelerator pedal, 33
Is a brake pedal. 37 is a select bar,
As a result, the form of power transmission from the engine is selected from forward, backward, neutral, parking and the like. Left and right front wheels 39
L, 39R and left and right rear wheels 28L, 28R are respectively provided with brake discs 41L, 41R, 45L, 45R, and these brake discs are connected to the brake pedal 33 via brake pads 43L, 43R, 47L, 47R, respectively. The brake can be applied by operating. Reference numeral 35 is a lever for a parking brake.

Reference numeral 49 is a control unit which constitutes a deceleration detecting means and a distance determining means.
It is composed of a microcomputer including an OM, a RAM, an input / output interface and the like. The control unit 49 is connected to detect the state of the engine and other parts, and the control unit 49 includes a brake actuator 67,
The throttle valve actuator 57 and the exhaust pipe valve actuator 63 can be controlled. When the control unit 49 controls the brake actuator 67, the brake discs are controlled via the brake pads of each wheel, so that the braking force can be applied to each wheel. When the control unit 49 controls the throttle valve actuator 57 and the exhaust pipe valve actuator 63, the opening and closing operations of the throttle valve 59 and the exhaust pipe valve 65 are respectively controlled thereby, and the output of the engine can be adjusted. . Reference numeral 55 is a vehicle speed sensor, and vehicle speed information detected by the vehicle speed sensor 55 is supplied to the control unit 49. A power supply voltage is supplied to the control unit 49 and other parts from a battery 51 directly and via a power supply relay 53. Reference numeral 69 denotes a data input device. The operation mode changes according to the data input from the data input device 69, and the data input from the data input device 69 is displayed on the display device 71. There is. Reference numeral 61 denotes a radar sensor, which transmits an electromagnetic wave forward of the vehicle under the control of the control unit 49, receives a reflected wave of the electromagnetic wave, and supplies the reflected wave to the control unit 49.
Calculates the inter-vehicle distance to the preceding vehicle.

FIG. 3 is an explanatory diagram for detecting the inter-vehicle distance from the preceding vehicle 75 by the radar sensor 61. Under the control of the control unit 49, the electromagnetic wave transmitted from the radar sensor 61 is reflected by the preceding vehicle 75 and received again by the radar sensor 61, and this received signal is supplied to the control unit 49. The control unit 49 calculates the inter-vehicle distance between the own vehicle 73 and the preceding vehicle 75 from the time difference between the time when the electromagnetic wave is transmitted from the radar sensor 61 and the time when the reflected wave is received.

Next, the operation of this embodiment will be described with reference to the flowcharts of FIGS. 4 and 5.

The control unit 49 first calculates the actual inter-vehicle distance R from the preceding vehicle (step 200). The calculation of the actual inter-vehicle distance R is performed at regular time intervals by the interrupt processing shown in FIGS. 5 (a) and 5 (b). That is, the interrupt processing shown in FIG. 5 (a) is activated by being interrupted by an interrupt pulse generated in the control unit 49 at regular intervals (step 800). As a result, the control unit 49 sends the radar sensor drive signal to the radar sensor 6
1 and the radar sensor 61 sends out an electromagnetic wave toward the preceding vehicle ahead of the vehicle (step 810), and the control unit 49 drives a timer composed of, for example, software to end this interrupt processing (step 82).
0). When the electromagnetic wave is output from the radar sensor 61 in this way, the reflected wave that hits the preceding vehicle is received by the radar sensor 61 as described above, and the interrupt signal shown in FIG. The process is activated (step 850). When the interrupt processing shown in FIG. 5 (b) is started, the timer is stopped by this, the counted time T ₀ is stored (step 860), and then the timer is reset to execute the interrupt processing. End (step 87)
0). In other words, this timer detects the reflected wave in the interrupt process shown in FIG. 5 (b) from the time when the radar sensor 41 sends out an electromagnetic wave toward the preceding vehicle ahead of the vehicle in the interrupt process shown in FIG. 5 (a). The time difference T ₀ up to the time of reception is measured. Control unit 4
9 calculates the actual inter-vehicle distance R from the preceding vehicle based on this time difference T ₀ .

Assuming that the interrupt time interval of the interrupt processing shown in FIGS. 5 (a) and 5 (b) is ΔT, the control unit 49 calculates the inter-vehicle distance calculated in step 200, which is one time before, ie, the time Δ.
The relative speed V with respect to the preceding vehicle is calculated by dividing the difference from the inter-vehicle distance detected by the interruption process before T by the interruption time interval ΔT (step 210). Then, the relative velocity V calculated in this way and the predetermined reference deceleration α
From this, the safe inter-vehicle distance R ₀ is calculated based on the formula R ₀ = 2αV ² (step 220). The reference deceleration rate α is a value that can be appropriately changed depending on the situation such as weather and road surface.

The safety inter-vehicle distance R ₀ thus obtained is compared with the inter-vehicle distance R obtained in step 200 in the next step 230, and when the inter-vehicle distance R is not smaller than the safe inter-vehicle distance R ₀ , that is, the inter-vehicle distance R ₀ If R is greater than the safe inter-vehicle distance R ₀ , there is no problem in safe driving, so flags THLG, EXVFLG, and BRKFLG, which will be described later, are 0 respectively.
To step 200, and the same operation is repeated. However, as a result of the check in step 230, if the inter-vehicle distance R is smaller than the safe inter-vehicle distance R ₀ , it is necessary to decelerate and maintain the inter-vehicle distance at the safe inter-vehicle distance, and therefore the process proceeds to the next step 250 and subsequent steps. In step 250, the deceleration difference Δα obtained by subtracting the actual deceleration α ₀ of the vehicle from the predetermined reference deceleration α.
To calculate. Here, the actual deceleration α ₀ of the vehicle has a positive value when the vehicle is actually decelerating, and has a negative value when the vehicle is accelerating.

In the next step 260, it is checked whether or not this deceleration difference Δα is larger than zero. The fact that the deceleration difference Δα is larger than 0 means that the actual deceleration of the vehicle is smaller than the reference deceleration α, and the deceleration must be further increased.
After the next step 300, the deceleration operation is further strengthened according to the degree of the deceleration difference. As a result of the check in step 260, the deceleration difference Δα
If is less than 0, the routine proceeds to step 600, where it is checked whether the deceleration difference Δα is 0, and the deceleration difference Δα is checked.
If α is 0, it means that the deceleration is properly controlled to a predetermined reference deceleration, and therefore the process returns to the original step 200 via the step 240. However, as a result of the check in step 600, the deceleration difference Δα is 0.
If it is negative, it means that the actual deceleration of the vehicle has been decelerated to a degree larger than the predetermined reference deceleration, so that the procedure proceeds to the next step 610 and thereafter to mitigate the deceleration operation. I am trying.

First, as a result of the check in step 260, if the deceleration and the difference Δα are larger than 0, that is, positive, and the actual deceleration of the vehicle is smaller than the predetermined reference deceleration, further deceleration operation is performed. The processing operation for strengthening will be described after step 300. Step 300
In the above, the deceleration index S for performing this deceleration operation is calculated by the ratio (S = α / α ₀ ) of the predetermined reference deceleration to the actual deceleration α ₀ of the vehicle. By calculating the deceleration index S, it is possible to know how large the predetermined reference deceleration is relative to the actual deceleration of the vehicle, that is, how much the deceleration should be increased. In step 300, the deceleration index S thus obtained is set to the predetermined reference values S ₁ , S ₂ , S ₃ , S ₄ , S.
_5, and when the deceleration index S is smaller than the reference value S ₁ , the process proceeds to step 310, and when the deceleration index S is larger than the reference value S ₁ , the process proceeds to step 320 and the reference value S ₂
If it is larger than the reference value, the process proceeds to step 330 and the reference value S
When it is larger than ₃ , the process proceeds to step 340, when it is larger than the reference value S ₄ , the process proceeds to step 350, and when it is larger than the reference value S ₅ , the process proceeds to step 360 and the deceleration according to each deceleration index. It will be strengthened. These reference values are such that S ₂ is larger than S ₁ , S ₃ is larger than S ₂ , S ₄ is larger than S ₃ ,
S ₅ is larger than ₄ . As the deceleration index S increases, the deceleration is significantly strengthened.

Further, in decelerating, not only the brake is controlled but also the throttle valve, the exhaust pipe valve are controlled, and the engine braking such as downshifting of the gear is also operated. A throttle valve flag THFLG that defines the control amount of the throttle valve and an exhaust pipe valve EXV that defines the control amount of the exhaust pipe valve in order to define these control amounts.
FLG, brake flag B that defines the control amount of the brake
An RKFLG and a downshift flag GRFLG that defines whether or not to downshift the gear are provided, and a throttle valve flag THFLG, an exhaust pipe valve flag EXVFLG, and a brake flag BRK are set according to the value of each deceleration index S.
The FLG is set to 1 to 5, which is divided into 5 stages. In this case, the deceleration effect is large when the flag is set to 5, and the deceleration effect is reduced when the flag is set to 1. The relationship between the set value of each flag and the deceleration effect will be described in an easy-to-understand manner by taking the case of brake control as an example. Now, the control amount of the brake is divided into stages from 0 to 10, where 0 is the state where the brake is not applied, 1 is the state where the brake is weakest, and 10 is the state where the brake is applied most strongly. Then, if 6 is being applied to the brake via the brake actuator as the brake control amount, and if the brake flag BRKFLG is set to a value of 3 as a result of the determination by the deceleration index, the brake is supplied in this case. The controlled amount is 6
The control amount of 6+ (10−6) × 3/5 = 8.4 is added to the brake through the brake actuator, and the deceleration is strengthened.

Next, the deceleration index S in step 300 is the reference value S
Each processing after being classified by ₁ to S ₅ will be described. First, when the deceleration index S is relatively small and smaller than the reference value S ₁ , the process proceeds to step 310, and the current throttle valve flag THFLG is set to 1 Is added. Next, the routine proceeds to step 370, where it is discriminated whether or not the throttle valve flag THFLG as a result of this addition is larger than 5. If the throttle valve flag THFLG is larger than 5, this throttle valve flag THFLG is set to 5
To the exhaust pipe valve flag EX (step 380).
Check if VFLG equals 5 (step 390). If the exhaust pipe valve flag EXVFLG is not equal to 5, this exhaust pipe valve flag EXVFL
1 is added to G (step 400), the process proceeds to step 650 to determine the deceleration control amount according to various flags, and the control unit 49 outputs a control signal corresponding to the determined deceleration control amount to perform deceleration. Also, the above step 3
If the throttle valve flag THFLG in 70 is smaller than 5 and if the exhaust pipe valve flag EXVFLG in step 390 is equal to 5, the process directly goes from the respective step to the next step 650 to respond to various flags in this state. The control amount is determined and a control signal corresponding to this control amount is output (step 710).

If the deceleration index S is larger than the reference value S _{1 as} a result of the check in step 300, the process proceeds to step 320 and the current throttle valve flag THFL is set.
A value obtained by adding 2 to the value of G is set as the value of the throttle valve flag, and the process proceeds to step 370 and thereafter. Since the operation after step 370 is the same as the above-mentioned operation, its explanation is omitted.

When the deceleration index S is larger than the reference value S ₂ ,
Proceeding to step 330, the throttle valve flag THFLG is set to 5 here. Then, it is checked whether the exhaust pipe valve flag EXVFLG is smaller than 3 (step 410), and the exhaust pipe valve flag EXVFLG is checked.
Is less than 3, this exhaust pipe valve flag EX
VFLG is set to 3 (step 420), the process proceeds to steps 650 and 660, the above-mentioned operation is performed, and the process returns to step 200. In step 410,
If the exhaust pipe valve flag EXVFLG is not smaller than 3, the routine proceeds to step 390, where the exhaust pipe valve flag E is
It is checked whether XVFLG is equal to 5, and if it is not equal to 5, 1 is added to the value of the exhaust pipe valve flag EXVFLG (step 400), and the step 65 is executed.
Proceed to 0 or later. When the exhaust pipe valve flag EXVFLG is equal to 5 in step 390, the process proceeds to step 650 and thereafter.

Furthermore, as a result of the check in step 300, if the deceleration index S is larger than the reference value S ₃ , step 340
To the throttle valve flag THFLG at 5
And the exhaust pipe valve flag EXVFLG is set to 5 (step 430), then it is checked in the next step 440 whether downshifting is possible. The check as to whether or not the shift down is possible is performed as a measure against engine overrun based on the relationship between the current shift gear position and the current vehicle speed. If downshifting is possible from the gear position and vehicle speed, the downshift flag GRFLG is set to ON (step 4
50) and proceed to step 650. This step 65
At 0, the control amount is determined according to various flags as described above, but in this case, the downshift flag GR
Since the FLG is on, downshifting is also done,
The engine brake is applied. If the result of the check in step 440 is that downshifting is not possible, no particular downshift flag is set and the process proceeds to step 650 and thereafter.

When the deceleration index S is larger than the reference value S ₄ ,
Proceed to step 350, and throttle valve flag THF
After setting LG to 5 and further setting the exhaust pipe valve flag EXVFLG to 5 in the next step 460, it is checked in step 470 whether or not the shift down is possible, as described above. If downshifting is possible due to the relationship between the current gear position and the current vehicle speed, the downshift flag GRFLG is set to ON (step 48).
0), 1 is further added to the brake flag BRKFLG (step 490), and the process proceeds to step 650 and the following steps.
Performs control according to the flag. In addition, the step 47
As a result of the determination as to whether or not the shift down is appropriate at 0, if the shift down is not appropriate, step 480 is skipped and step 490 is proceeded to, 1 is added to the brake flag BRKFLG and step 650 and subsequent steps are proceeded to.

If the deceleration index S is larger than the reference value S _{5 as} a result of the check in step 300, the process proceeds to step 360 to set the throttle valve flag THFLF to 5
Is set, and after the exhaust pipe valve flag EXVFLG is set to 5 in step 500, it is similarly determined whether or not downshifting is possible (step 510). If downshift is possible, downshift flag GRF
After setting LG to ON and proceeding to step 520 and further setting the brake flag BRKFLG to 5 (step 530), proceeding to step 650 and subsequent steps, the deceleration control according to each flag is performed. Step 51
If the result of the check at 0 is that downshifting is not possible, step 520 is skipped and step 530 is proceeded to, where the brake flag is set and the same operation is performed.

In the above operation, steps 250 and 260 constitute deceleration determination means, step 300 constitutes arithmetic means, and steps 310, 320, 330, 370 to 420, and 650 and 660 are first braking portions. Steps 340, 430 through 450, and 650, 660 that constitute the control means constitute the second braking portion control means, and steps 350, 360, 460 through 530, and 65.
Reference numerals 0 and 660 constitute third braking unit control means.

In the above operation, the actual inter-vehicle distance R with the preceding vehicle is the safe inter-vehicle distance R
Is smaller than ₀ , and the deceleration difference Δα obtained by subtracting the actual deceleration α ₀ of the vehicle from the predetermined reference deceleration α is positive,
Since the deceleration of the vehicle is smaller than the predetermined reference deceleration, the process is to further strengthen the deceleration operation. Next, as a result of the check in step 260, the deceleration and the difference Δα are 0.
The processing in the following case will be described after step 600.

In step 600, it is checked whether the deceleration difference Δα is 0, that is, whether the actual deceleration of the vehicle is equal to a predetermined reference deceleration. When both decelerations are equal, that is, when the deceleration difference Δα is 0, the routine proceeds to step 240, and the above-mentioned respective flags THFL.
G, EXVFLG, BRKFLG are set to 0, and the process returns to step 200.

However, the deceleration difference Δα in step 600
If it is not equal to 0 and is negative, it means that the actual deceleration of the vehicle is larger than the predetermined reference deceleration and the deceleration is too strong. Therefore, proceed to step 610 and thereafter. It is trying to slow down the deceleration. Therefore, first, at step 610, it is checked whether the brake flag BRKFLG is 0, that is, whether the brake is being controlled or not.
Here, when the brake flag BRKFLG is 0, it means that the brake is not controlled, and when the brake flag BRKFLG is other than 0, it means that the brake is controlled. When the brake flag BRKFLG is not 0, that is, when the brake is being controlled, the routine proceeds to step 615, where 1 is subtracted from the current brake flag BRKFLG to weaken the brake control by one step, and then the routine proceeds to step 650. , A control amount corresponding to each flag is determined, and a control signal corresponding to this control amount is output to each actuator (step 66).
0), return to step 200.

If the result of the check in step 610 is that the brake flag BRKFLG is 0, that is, if the brake is not being controlled, the routine proceeds to the next step 620, where it is checked if the exhaust pipe valve flag EXVFIL is 0. . Exhaust pipe valve flag EXVFLG is 0
If the exhaust pipe valve EXVFLG is not 0, it means that the exhaust pipe valve is not being controlled. As a result of this check, the exhaust pipe valve flag EXVFLG is 0.
If not, that is, if the exhaust pipe valve is being controlled, the routine proceeds to step 625, where 1 is subtracted from the current value of the exhaust pipe valve flag to weaken the exhaust pipe valve control by one step, and the routine proceeds to step 650 and thereafter. It has become. If the exhaust pipe valve flag is 0 as a result of the check in step 620, that is, if the exhaust pipe valve is not controlled, the accelerator pedal 3
Check if 1 is stepped on (step 63
0), if the accelerator pedal 31 is not depressed, the process directly proceeds to step 650 and the following steps.
When is operated by stepping on, the routine proceeds to step 640, where it is checked whether the throttle valve flag THFLG is 0 or not. Throttle valve flag TH
When FLG is not 0, that is, when the throttle valve is being controlled, 1 is subtracted from the current value of the throttle valve flag, the throttle valve is opened by one step, and the process proceeds to step 650 and thereafter. On the other hand, when the throttle valve flag THFLG is 0, that is, when the throttle valve is not being controlled, the process directly proceeds to step 650 and the above, the above-described processing operation is performed, and then the process returns to step 200. That is, in the operation after step 610, the control of the brake flag, the exhaust pipe valve flag, the throttle valve flag, etc. is weakened step by step to weaken the actual deceleration of the vehicle and match it with a predetermined reference deceleration. Is what you are doing.

[Effects of the Invention] As described above, the host vehicle is made to follow the preceding vehicle at a safe inter-vehicle distance by accelerating or decelerating the host vehicle speed according to the change in the inter-vehicle distance between the host vehicle and the preceding vehicle. In the inter-vehicle distance control device according to the present invention, when the actual deceleration is smaller than the preset reference deceleration, the braking force of the brake is increased according to the ratio of the reference deceleration to the actual deceleration. By appropriately selecting and controlling the output of the engine and the gear ratio of the transmission, it is possible to decelerate at the reference deceleration, so it is possible to decelerate appropriately without causing discomfort to the occupants. . Further, there is no wasteful consumption of energy due to the intermittent braking operation as in the prior art, and it is possible to contribute to the improvement of fuel consumption.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a block diagram of an inter-vehicle distance control device showing an embodiment of the present invention, and FIG. 3 is a diagram for explaining the operation of a radar sensor used in FIG. ,
FIG. 4 is a flow chart showing the operation of the inter-vehicle distance control device of FIG. 2, and FIGS. 5 (a) and 5 (b) are flow charts showing interrupt processing in the inter-vehicle distance control device of FIG. DESCRIPTION OF SYMBOLS 1 ... Deceleration detection means 3 ... Distance determination means 5 ... Deceleration determination means 7 ... Calculation means 9 ... 1st braking part control means 11 ... 2nd braking part control means 13 ... 3rd braking part control means

Claims (1)

[Claims] 1. An inter-vehicle distance between a host vehicle and a preceding vehicle is detected, and the host vehicle is made to follow the preceding vehicle at a predetermined inter-vehicle distance by accelerating or decelerating the host vehicle speed in accordance with a change in the inter-vehicle distance. In the inter-vehicle distance control device, the deceleration detecting means for detecting the deceleration of the host vehicle, the distance determining means for determining whether or not the detected inter-vehicle distance is shorter than the predetermined inter-vehicle distance, and the deceleration detecting means. Deceleration determination means for determining whether the detected deceleration is smaller than a predetermined reference deceleration, and the distance determination means determines that the inter-vehicle distance is shorter than the predetermined inter-vehicle distance, and the deceleration When it is determined by the determination means that the deceleration is smaller than the reference deceleration, calculation means for calculating a ratio or a difference between the deceleration and the reference deceleration, and the calculated value of the ratio or difference are calculated in advance. First decided A first braking portion control means for controlling the opening of the throttle valve in a direction to be closed from the current opening when in the range; and a predetermined first value of the ratio or difference larger than the first range. When it is in the range of 2, the throttle valve opening is controlled to be closed from the current opening, and the gear ratio of the transmission is downshifted so as to be changed to a gear ratio larger than the current gear ratio. And a braking unit control means for controlling the opening of the throttle valve to be closed from the current opening when the ratio or the difference is in a predetermined third range that is larger than the second range. A third braking portion control means for downshifting to change the gear ratio of the transmission to a gear ratio higher than the current gear ratio and controlling the brake actuator to increase the braking force of the wheels. To have Vehicle distance control apparatus according to claim.