KR20100058279A - Distance control method - Google Patents

Abstract

PURPOSE: A distance control method between vehicles is provided to accurately determine a brake operation of a vehicle by controlling the on/off of a brake with an offset target operated for a target vehicle to vehicle distance. CONSTITUTION: A distance control method between vehicles can change a target vehicular gap by the speed of a vehicle when a vehicle to vehicle distance with a preceding vehicle is shorter than the target vehicle to vehicle distance, and the speed of the vehicle is faster than the preceding vehicle. The distance control method between vehicles comprises the following steps: measuring the vehicle to vehicle distance and the speed of the vehicle using a vehicle to vehicle distance apparatus and a vehicle speed sensor; obtaining a brake pressure from the vehicle to vehicle distance and the vehicle speed; and controlling the brake pressure.

Description

Distance control method

The present invention relates to an inter-vehicle distance control method, and more particularly, to an inter-vehicle distance control method for removing anxiety or fear that the driver has in the traveling control device.

In general, a driving control device equipped with a distance control device and a target speed control device automatically decelerates its own vehicle if the preceding vehicle decelerates. Fig. 1 is a block diagram showing a conventional travel control device, in which a target deceleration is calculated, and the brake is controlled to match the deceleration of the target while comparing with the deceleration of the own vehicle detected by the acceleration sensor 5. .

Reference numeral 1 denotes an inter-vehicle distance measuring device, 2 is a vehicle speed sensor, 3 is an inter-vehicle distance control unit, 6 is a target vehicle speed control unit, 7 is a brake control unit, and 8 is acceleration control.

2 illustrates a general configuration of an adaptive cruise control (ACC), wherein the ACC is a device that automatically runs at a constant speed while maintaining a constant distance from a preceding vehicle.

The ACC measures the inter-vehicle distance with the preceding vehicle and controls to maintain the specified inter-vehicle distance. For example, if the measured inter-vehicle distance is smaller than the designated inter-vehicle distance, the brake is automatically applied to reduce the speed. If the inter-vehicle distance with the preceding vehicle is larger than the designated inter-vehicle distance, the vehicle accelerates to increase its speed.

In addition, Japanese Patent Laid-Open No. Hei 4-314638 discloses a collision avoidance apparatus in which a target deceleration is calculated from the relative speed and the distance between the preceding vehicles interrupted in the train, and the brake is controlled based on the target deceleration. In this case, if the speed of the preceding vehicle is slow, the target deceleration that is not sudden brake may be determined even if the distance between the vehicles is short. That is, sudden braking can be avoided.

Further, Japanese Patent Laid-Open No. Hei 11-11273 discloses a travel control device that prevents rapid braking when a preceding vehicle suddenly decelerates. When the preceding vehicle suddenly decelerates, the target deceleration of the own vehicle is increased, so that the deceleration of the preceding vehicle is detected to control the braking at a faster deceleration in order to avoid sudden braking.

Although the driver's time to press the brake pedal is different depending on the driver and the reaction degree is different, even if the driver's time to press the brake pedal is late, the spare time of braking increases, thereby avoiding sudden braking.

However, the conventional driving control apparatus as described above is a technique for avoiding sudden braking and not giving the driver a sense of discomfort, and it is not always possible to say that the time to start the brake is a proper time. For example, in the ACC, when the distance between the preceding vehicle is shorter than the preset distance, the brake is operated. Therefore, there is a time delay before the brake is applied, so the distance between the vehicles becomes shorter.

The present invention has been made in view of the above, it is possible to accurately determine the on and off of the brake, and to remove the anxiety or fear that gives the driver when the distance between the target is shortened and his car approaches the preceding vehicle. The purpose is to provide a method for controlling the distance between vehicles.

The above object is a method for controlling a distance between vehicles,

When the inter-vehicle distance with the preceding vehicle is shorter than the target inter-vehicle distance and the relative speed of the host vehicle is faster than the preceding vehicle, the target inter-vehicle distance is achieved according to the inter-vehicle distance control method.

Preferably, the step of measuring the distance between the vehicle and the vehicle speed from the vehicle distance measuring device and the vehicle speed sensor; Obtaining brake pressure from the inter-vehicle distance and vehicle speed, assuming that brake pressure is proportional to vehicle mass multiplied by acceleration; And controlling the brake pressure to fall within a brake pressure range of an upper limit and a lower limit determined as a function of the vehicle speed.

Further, controlling the brake pressure to fall within the upper and lower brake pressure ranges defined as a function of the vehicle speed may include boosting the brake pressure so as not to rotate the wheel by the valve and reducing the brake pressure to rotate the wheel. Alternating steps.

Accordingly, according to the inter-vehicle distance control method according to the present invention, the braking of the vehicle can be accurately determined by offsetting the target inter-vehicle distance and controlling the on / off of the brake with the offset target, and the own vehicle determines the target inter-vehicle distance. There is no passing or approaching the preceding vehicle, and it does not give the driver anxiety or fear.

In addition, abrupt deceleration can be eliminated by controlling the brake pressure to fall within the brake pressure ranges of the upper and lower limits determined as a function of the vehicle speed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating a configuration of a driving control apparatus according to an embodiment of the present invention.

In FIG. 3, the ACC refers to the travel controller 10, and the travel controller 10 directly controls the on and off of the brake.

The traveling control unit 10 is provided with a vehicle distance measuring device for measuring the distance to the preceding vehicle traveling in front of the own vehicle (self), the distance measurement is a milli wave (Radar), It can be realized by a laser radar, an ultrasonic sensor, or the like.

In addition, since the vehicle controller can receive the signal from the vehicle speed sensor and the acceleration sensor can calculate the vehicle acceleration from the vehicle speed sensor, it is not necessary to install the vehicle in the travel controller 10. In addition, the target vehicle distance is set in advance in the travel control unit 10, and at the time of brake control, the throttle 12 (Throttle) is turned off.

Referring to the distance control method between the vehicle according to the present invention in detail as follows.

4 is a graph showing the inter-vehicle distance according to the conventional brake timing before improvement. When the target inter-vehicle distance with the preceding vehicle at the time of deceleration of the vehicle is set as the brake line, the brake on and off before the improvement is a brake line. Since it is done below, the target distance cannot be maintained.

FIG. 5 is a graph showing the inter-vehicle distance according to the brake timing of the present invention after improvement, and offsets by τ according to the speed of the own vehicle, as shown in FIG. Therefore, his car is wider than the distance between the target cars before the offset so that the vehicle does not approach the preceding vehicle.

FIG. 6 is a graph for explaining a brake control method according to the present invention. When the brake control is turned on, the brake pressure is controlled to enter between the brake pressure upper limit line and the brake lower limit line. In this case, the dotted line is a case where the brake pressure is not controlled, and the solid line is a case where the brake pressure is controlled according to the present invention.

7 is a block diagram showing the configuration of the brake control unit 12. The brake control unit 12 includes a brake booster 14, a master cylinder 15, and an ABS 16 (antilock brake system).

The brake booster receives the brake signal to amplify the brake signal, the master cylinder receives the amplified signal to generate the brake hydraulic pressure, and the ABS 16 receives the generated brake hydraulic pressure to adjust the pressure and brake pressure to each wheel. To pass.

In addition, the ABS alternately performs the operation of raising the brake pressure to stop the rotation of the wheel by controlling the valve and reducing the brake pressure to rotate the wheel.

Such a mechanism further includes a hydraulic sensor to control the upper limit of the brake pressure and the lower limit of the brake pressure.

If the preceding vehicle travels at the speed v _leading , and the own vehicle is traveling at the speed v _real , and the distance from the own vehicle to the preceding vehicle is the inter-vehicle distance d, the throttle 12 to the position where the preceding vehicle was located When the vehicle is turned off and the deceleration acceleration is assumed and the speed is equal to the preceding vehicle by using a _{sup position} , the time to proceed is as follows.

Here, if the vehicle speed of the preceding vehicle is assumed to be constant, and the vehicle is relatively considered as the reference vehicle, the own vehicle is considered to approach the preceding vehicle stopped by the acceleration a _{sup position} and the initial speed v _real -v _leading . At this time, the relative distance d * in which the host vehicle runs until the relative speed becomes zero is expressed by the following equation.

If you substitute Equation 1 into Equation 2,

Here, a = 2a _{sup position sup_ para} la When, Equation (4) is represented by the expression.

The condition under which the vehicle runs at the same speed as the preceding vehicle up to the target inter-vehicle distance? _Set v _l (? _Set is the set inter-vehicle time) is given by the following equation.

In addition, in order to restrict the deceleration, a logic for controlling the brake is added when the vehicle falls within a constant speed difference.

Break-on condition

The following equation (7) is used to define the position where the parameter is added and the brake is actuated as follows.

τ _{Brake_on_para} is a parameter introduced to offset the value obtained by Equation 6.

This condition alone causes excessive deceleration at v _real <v _leading to be lower than the controllable speed. Therefore, the following equation is introduced to stop braking at the point where the speed is lower than that of the preceding vehicle.

Δv _{brake_on_para} is a parameter that defines a speed range in which braking is performed.

In the case of break-on, the following equations (7) and (8) are determined.

Break-off condition

Using Equation 6, the position where the parameter is added and the brake is released is defined below.

τ _{Brake_on_para} is a parameter introduced to offset the value obtained by Equation 6, like the break-on condition.

In the current program, control is performed using the same value.

Since only this condition decelerates too much and becomes lower than the controllable speed, the following equation is introduced to stop the activity at the time when the speed drops from the preceding vehicle.

Δv _{brake_on_para} is a parameter that defines a speed range in which braking is performed.

In the case of break-off, the following expressions (9) and (10) are determined as or conditions.

Handling when the brake judgment condition is not suitable

Processing in the case where the above conditions are not suitable is in accordance with the following rules.

1. Initial Conditions

It is called break-off condition at the start.

2. When brake on

Even when the brake on condition is not satisfied, it is called "break on" until the brake off condition is satisfied.

3. When break off

Even when the break-off condition is not satisfied, it is called "break off" until the break-on condition is satisfied.

In addition, in order to use the brake timing and adjust the distance between the vehicle and the preceding vehicle, the driver should also be relieved about the brake pressure. Here, the present invention proposes a method of giving relief to the brake pressure.

The distance between vehicles is the acceleration divided by the square of the relative speed between the preceding car and the second car of the car. The acceleration at the time of brake has a proportional relation between the brake pressure and the acceleration times the vehicle mass. Therefore, the vehicle pressure is multiplied by the proportional coefficient as a parameter, and the brake pressure is obtained from the equation for calculating the distance between vehicles.

If there is a preceding vehicle and the relative vehicle is considered as a reference, the time required for the speed change between the relative acceleration a _{real_relativity} of the own vehicle and Δv _{real_relativity} = 0, where the relative velocity of the own vehicle becomes zero, The following relationship is obtained.

Δv _{real_relativity} = a _relativity

The relative distance which runs at this time is shown by a following formula.

Substituting Equation 1 here gives:

When this data is combined, the following equation (12) is obtained.

Here, the relationship between the weight m of the vehicle, the relative acceleration a _{real_relativity} and the brake pressure P _brake is made.

Here, from the equations (12) and (13), the running distance d = [?] V _{real_relativity} dt is shown below.

Here, if the distance between vehicles in the current state is L and the vehicle speed v _leading of the preceding vehicle is the inter-vehicle time τ _{brake_pressure_para} of the target at which the vehicle speed is the same, the distance d that travels until the same speed as the preceding vehicle is shown as follows. .

The following equations are required from equations (14) and (15).

If a dimensionless term is obtained from the above equation, the part is multiplied by a parameter, and the adjustment term is obtained.

Expressing the equation using the own vehicle speed v _real is as follows.

The brake pressure is calculated by the above equation.

However, in order to cope with the case where the pressure rises too much, the upper limit value P _{upper_limit} and the brake booster 14 lower limit value P _{lower_limit} are input by the following equation.

Are parameters which determine the upper and lower limit values of the brake pressure, respectively.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all the various forms of embodiments that can be carried out without departing from the spirit.

1 is a block diagram showing a conventional traveling control device;

2 is a block diagram showing a general configuration of an ACC;

3 is a block diagram showing a configuration of a driving control apparatus according to an embodiment of the present invention;

4 is a graph showing the inter-vehicle distance according to the brake timing of the prior art before improvement;

5 is a graph showing the inter-vehicle distance according to the brake timing of the present invention after improvement;

6 is a graph for explaining a brake control method according to the present invention;

7 is a block diagram showing a configuration of a brake control unit according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: driving control unit 11: Excel

12: Throttle 13: Brake Control

14 brake booster 15 master cylinder

16: ABS 17: brake pedal

Claims (3)

In the inter-vehicle distance control method, And the target inter-vehicle distance is varied according to the own vehicle speed when the inter-vehicle distance with the preceding vehicle is shorter than the target inter-vehicle distance and the relative speed of the own vehicle is faster than the preceding vehicle. The method according to claim 1, Measuring a distance between the vehicle and a vehicle speed from the vehicle distance measuring device and the vehicle speed sensor; Assuming that the brake pressure is proportional to the vehicle mass multiplied by the acceleration, obtaining the brake pressure from the inter-vehicle distance and the vehicle speed; Controlling the brake pressure to fall within a brake pressure range of an upper limit and a lower limit determined as a function of vehicle speed. The method according to claim 2, Controlling the brake pressure to fall within the upper and lower brake pressure ranges as a function of the vehicle speed alternates by boosting the brake pressure so as not to rotate the wheel by the valve and reducing the brake pressure to rotate the wheel. Distance control method comprising the step of performing.

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