JP3136238B2 - Rear-end collision judgment method in rear-end collision prevention system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention automatically determines the risk of a rear-end collision by a processing unit based on the following distance, the speed of the own vehicle, etc., notifies the driver of the rear-end collision risk, and uses a rear-end collision avoiding means. The present invention relates to a rear-end collision determination method in a rear-end collision prevention system that performs an automatic rear-end collision avoiding operation.

[0002]

2. Description of the Related Art Conventionally, a rear-end collision prevention system that automatically determines the danger of a rear-end collision and performs an automatic rear-end collision avoiding operation by a rear-end collision avoiding means is configured as shown in FIG.

That is, in FIG. 5, reference numeral 1 denotes a laser radar for detecting an inter-vehicle distance from a preceding vehicle, 2 denotes a wiper switch that is turned on by operation of a wiper, 3 denotes a turn switch that is operated and turned on when turning left or right, and 4 denotes a turn switch. A steering angle sensor for detecting a steering angle according to a steering operation, an idle switch for turning on and off in conjunction with depression of an accelerator, a back lamp switch for turning on when a shift lever of the transmission is at a back position, 7 is a stop lamp switch that turns on and off in conjunction with depression of the brake, 8 is a wheel speed sensor that detects the vehicle speed,
Reference numeral 9 denotes an ECU serving as a processing unit, which takes in the output of the laser radar 1, the state of each of the switches 2, 3, 5 to 7, the outputs of the steering angle sensor 4 and the wheel speed sensor 8, and obtains the following distance and the wheels by the laser radar 1. The danger of a rear-end collision is determined based on the speed of the own vehicle by the speed sensor 8, and when it is determined that there is a danger of a rear-end collision, a forced control command is given to an automatic brake control unit 10 as a rear-end collision avoidance unit, and an automatic brake is applied. The warning means 11 including a display or a speaker is controlled by the ECU 9 to issue a warning to the driver that there is a risk of collision. At this time, the operation state of the automatic brake control means 10 is fed back to the ECU 9. When the ECU 9 determines that the danger of a rear-end collision has disappeared, the ECU 9 forcibly controls the automatic brake control means 10. Decree is to be released.

At this time, when judging the danger of a rear-end collision,
As described above, the reference inter-vehicle distance is determined in accordance with the own vehicle speed and the relative speed of the preceding vehicle. If the current inter-vehicle distance becomes less than that, it is determined that there is a danger of a rear-end collision, and an alarm or an automatic brake is driven. The speed at which the reference inter-vehicle distance is determined is provided with a predetermined range, or an adjustment switch or the like is provided to finely adjust the collision risk determination.

[0005]

However, in the above-described conventional determination of the risk of rear-end collision, it is difficult to provide flexibility to all driving conditions such as road surface conditions and vehicle speed changes. Even if it is not considered necessary to issue a warning, a warning may be issued by the warning means 11 or, conversely, automatic braking may not be performed despite the high risk of a rear-end collision.

Accordingly, the present invention has been made in order to solve the above-mentioned problems, and has as its object to flexibly cope with all running conditions such as a change in vehicle speed.

[0007]

A rear-end collision risk judging method in a rear-end collision prevention system according to the present invention automatically judges a rear-end collision risk with a preceding vehicle by a processing unit based on an inter-vehicle distance, an own vehicle speed, and the like. A rear-end collision prevention system that informs a driver of a rear-end collision danger and performs an automatic rear-end collision avoiding operation by a rear-end collision avoiding unit, wherein the processing unit activates the rear-end collision avoiding unit when the vehicle approaches further. ,
This is the difference between the avoidance start inter-vehicle time derived based on the deceleration of the own vehicle, the preceding vehicle speed, and the deceleration of the preceding vehicle, and the current inter-vehicle time derived by dividing the current inter-vehicle distance by the own vehicle speed. A margin time is calculated, and a margin time change speed, which is a time change amount of the margin time, and a margin time change acceleration, which is a time change amount of the margin time change speed, are calculated, and the margin time, the margin time change speed, A collision risk increase / decrease degree is calculated based on a plurality of risk increase / decrease degree certainty degrees calculated from the positive, negative, and zero certainty degrees of the marginal time change acceleration, respectively, and a cumulative value of the rearward collision risk increase / decrease is larger than a predetermined value. Sometimes, the processing unit notifies the rear-end collision danger and drives the rear-end collision avoiding means.

[0008]

According to the present invention, the processing unit calculates a margin time, which is the difference between the avoidance start inter-vehicle time and the current inter-vehicle time when the rear-end collision avoidance means is activated when the vehicle approaches further, and a time change of the margin time. The marginal time change speed, which is a quantity, and the marginal time change acceleration, which is the time change amount of the marginal time change speed, are calculated, and the marginal time, the marginal time change speed, and the marginal time change acceleration are positive, negative, and zero, respectively. A plurality of risk increase / decrease degree certainty degrees are calculated from the certainty degrees, a rear-end collision increase / decrease degree is calculated based on these risk increase / decrease degree certainty degrees, and when the cumulative value of the rear-end collision change degree is greater than a predetermined value, the processing unit Since the rear-end collision is reported, the rear-end collision can be determined flexibly in response to all driving conditions such as changes in vehicle speed. It is possible to some extent predict the dangerous rear-end collision by taking into account the speed.

[0009]

FIG. 1 is a flowchart for explaining the operation of an embodiment of the present invention, and FIGS. 2 to 4 are explanatory diagrams of the operation.

Since the system applied in this embodiment is the same as the configuration shown in FIG. 5, duplicate description will be avoided and the following description will also refer to FIG. 5, but the functions of the ECU 9 differ in the following points. ing.

That is, the avoidance start inter-vehicle time Tla is determined based on the own vehicle speed Vs, the deceleration Gs of the own vehicle, the preceding vehicle speed Vp, and the deceleration Gp of the preceding vehicle, at which the automatic brake control means 10 is operated when the vehicle approaches further. At the same time, the current inter-vehicle time Tl calculated from the current inter-vehicle distance L and the own vehicle speed Vs is calculated, and the spare time T ', which is the difference between the avoidance start inter-vehicle time Tla and the current inter-vehicle time Tl, is calculated. The marginal time change rate Δ which is the amount of time change of the marginal time T ′
T ′ and a marginal time change acceleration Δ ² T ′ which is a time change amount of the marginal time change rate ΔT ′ are calculated, and each of the marginal time T ′, the marginal time change rate ΔT ′, and the marginal time change acceleration Δ ² T ′ are respectively calculated. From the positive (P), negative (N), and zero (Z) certainty of
1, W2, W3, W4, W5 are calculated, and the rear-end collision risk increase / decrease degree ΔD is calculated based on the respective risk increase / decrease degree certainties W1, W2, W3, W4, W5. It is determined whether or not it is equal to or more than a system operation reference value b which is a predetermined value. If the value is equal to or more than b, the alarm means 11 is controlled to issue a warning to the driver that there is a danger of a rear-end collision, and an automatic brake control means. 10 is driven.

Further, the marginal time change rate ΔT '
Indicates whether the inter-vehicle distance is reduced or widened even at the same inter-vehicle distance, and the marginal time change acceleration Δ ² T ′ indicates whether or not the tendency is further enhanced.

Next, the control operation will be described with reference to the flowchart of FIG.

First, the state of the wiper switch 2 is determined by the ECU 9
(Step S0), the own vehicle speed Vs is derived based on the output of the wheel speed sensor 8 (Step S1), and the deceleration Gs of the own vehicle is derived based on the own vehicle speed Vs and the state of the wiper switch 2. (Step S2) Based on the inter-vehicle distance L by the laser radar 1 and the own vehicle speed Vs, the preceding vehicle speed Vp and the deceleration Gp of the preceding vehicle are derived (Step S3), and these Vs, Gs, Vp, G
Based on p, the avoidance start inter-vehicle time Tla that activates the automatic brake control means 10 when the vehicle approaches further is calculated (step S4).

At this time, the deceleration Gp of the preceding vehicle is calculated by taking into account the detection response delay caused by the filter processing shown in FIG.
Is set as follows.

[0016]

(Equation 1)

Further, the own vehicle speed Vs and the preceding vehicle speed Vp
The distance L between vehicles can be classified as follows according to the size of the vehicle. That is, the inter-vehicle distance L is expressed by Equation 2 when (1) Vp ≦ 0, by Equation 3 when (2) Vp> Vs, and (3a) 0 <Vp ≦ V
In the case of s and Gp × Ts ≧ Vp (when the preceding vehicle stops faster than the own vehicle), Equation 4, (3b) 0 <Vp ≦
At the time of Vs, and when Gp × Ts <Vp (when the preceding vehicle stops later than the own vehicle), it is expressed by Expression 5, respectively. However, in any case, when a determination result of L <0 is obtained, L = 0. In these equations, Ts is the braking time.

[0018]

(Equation 2)

[0019]

(Equation 3)

[0020]

(Equation 4)

[0021]

(Equation 5)

When the value obtained by dividing the inter-vehicle distance L obtained in this way by the own vehicle speed Vs becomes closer to this, an avoidance start inter-vehicle time Tla that activates the automatic brake control means 10 is obtained.

Next, as shown in FIG. 1, the current inter-vehicle time Tl is calculated (step S5).
l and the avoidance start inter-vehicle time Tla calculated in step S4.
Time T ', which is the difference from the calculated
6) A marginal time change rate ΔT ′, which is a time change amount, is calculated from the marginal time T ′ (step S7), and a marginal time change acceleration Δ ² T is a time change amount of the marginal time change rate ΔT ′. Are calculated (step S8), and the first to fifth dangers are determined from the certainty factors P, N, and Z of the margin time T ′, the margin time change rate ΔT ′, and the margin time change acceleration Δ ² T ′, respectively. Increase / decrease degree confidence W
1, W2, W3, W4, and W5 are calculated, and the rear-end collision risk increase / decrease degree ΔD is calculated based on the respective risk increase / decrease degree certainties W1, W2, W3, W4, and W5 (step S9).

Here, the margin time T ′, the margin time change rate ΔT ′, and the margin time change acceleration Δ ² T ′ are P,
The confidence factors N and Z are as shown in FIGS. 2, 3, and 4, respectively, and Ps in FIG. 2 is a confidence value having a small positive value.

Then, as basic rules, the respective risk increase / decrease degree certainties W1, W2, W3, W4, W5 are determined as follows.

(1) The first risk increase / decrease degree certainty W1 is defined by the value of the certainty that the spare time T 'is P and the spare time change rate Δ
It is given by the product of the certainty value that T 'is P ...
(T ′ = P certainty) × (ΔT ′ = P certainty) (2) The second risk increase / decrease degree certainty W2 is the value of the certainty at which the allowance time change rate ΔT ′ is Z and the allowance time Acceleration Δ
² T 'is given by the product of the certainty values with Z ...
(ΔT ′ = Confidence of Z) × (Δ ² T ′ = Confidence of Z) (3) The third risk increase / decrease degree confidence W3 is a value of the confidence that the spare time T ′ is P and the spare time. The rate of change ΔT ′ is given by the product of the certainty factors N.... (T ′ = P certainty factor) × (ΔT ′ = N certainty factor) (4) Fourth risk increase / decrease degree certainty factor W4 Is the value of the certainty factor that the margin time T ′ is Ps and the margin time change rate ΔT ′ is N
Is given by the product of the value of the certainty factor that is, and the sum of the value of the certainty factor that the spare time acceleration Δ ² T ′ is Z and the certainty value that the spare time acceleration Δ ² T ′ is P ... (T '= Confidence of Ps) × (ΔT' = confidence of N) × ｛(Δ ² T '= Z
+ (Δ ² T ′ = P certainty factor)｝ (5) The fifth risk increase / decrease degree certainty factor W5 is the value of the certainty factor Z for which the margin time T ′ is zero and the margin time T ′. the sum of the product of a small value of reliability level Ps is a positive value and the margin time acceleration delta ² T 'is negative and is confidence N value, the margin time change rate delta
It is given by the product of the certainty factor N where T 'is negative ...
｛(T ′ = confidence of Z) + (T ′ = confidence of Ps) ×
{(Δ ² T '= confidence of N)} × (ΔT' = confidence of N) In addition, a rear-end collision risk decreasing rate ΔD is obtained by calculation of Equation 6.

[0027]

(Equation 6)

At this time, in Equation 6, the respective danger increase / decrease degree certainties W1, W2, W3, W4, and W5 are weighted, for example, -0.5 for W1, and-for W2.
Weights of 0.2, W3 are multiplied by 0.1, W4 is multiplied by 0.25, and W5 is multiplied by 0.5. Note that W1 and W2
The negative value of the weight indicates that the risk of a rear-end collision is low, and is because a negative factor is considered in the degree of increase or decrease in rear-end collision risk.

Next, as shown in FIG. 1, it is determined whether or not the cumulative value ΣΔD of the rear-end collision risk increase / decrease degree ΔD is greater than or equal to the system operation reference value b (step S10).
If O, the system is not operated (step S11),
Thereafter, the process returns to the start. On the other hand, if the result of the determination is YES, the system is operated, and a warning that the danger of a rear-end collision is high is issued by the warning means 11, and the automatic brake control means 10 is controlled to apply the automatic brake. (Step S12), and then return to start.

Therefore, the spare time T ', which is the difference between the avoidance start inter-vehicle time Tla and the current inter-vehicle time Tl, the allowance time change speed ΔT', which is the time change amount of the allowance time T ', and the allowance time change speed ΔT''is calculated, and these margin time T' of a time variation margin time change acceleration delta ² T confidence, margin times change rate [delta] T ', margin times change acceleration delta ² T' are each a positive, negative, and zero , A plurality of risk increase / decrease degree certainties W1 to W5 are calculated from them, and a rear-end collision change degree ΔD is calculated based on these risk increase / decrease degree certainties. The cumulative value ΣΔD of the rear-end collision change degree ΔD is equal to or greater than the system operation reference value b. In this case, the danger of a rear-end collision is notified by the ECU 9, so that the danger of the rear-end collision can be determined flexibly in response to all driving conditions such as a change in vehicle speed, and the marginal time change speed Δ
It is possible to predict the rear-end collision to some extent by taking into account T 'and the marginal time change acceleration Δ ² T'.

[0031]

As described above, according to the present invention, a plurality of risk increase / decrease degree certainties are calculated from the certainties in which the margin time, the margin time change speed, and the margin time change acceleration are respectively positive, negative, and zero. The degree of collision risk increase / decrease is calculated based on these risk increase / decrease degree certainties, and when the cumulative value of the degree of collision risk increase / decrease is greater than a predetermined value, the processing unit informs the danger of the collision, so that any processing such as vehicle speed change The collision risk can be judged flexibly in response to the conditions, and the collision risk can be predicted to some extent by taking into account the speed of change of the spare time and the acceleration of the spare time, thereby improving the safety during traveling. This is extremely effective in improving the reliability of the rear-end collision prevention system.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining the operation of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of one embodiment.

FIG. 3 is an operation explanatory diagram of one embodiment.

FIG. 4 is an operation explanatory diagram of one embodiment.

FIG. 5 is a block diagram of a general rear-end collision prevention system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser radar 8 wheel speed sensor 9 ECU (processing unit) 10 automatic brake control means (collision avoidance means) 11 alarm means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G08G 1/16 B60T 7/12

Claims (1)

(57) [Claims] 1. A danger of a rear-end collision with a preceding vehicle is automatically determined by a processing unit based on an inter-vehicle distance, an own vehicle speed, and the like, and a driver is notified of a rear-end collision danger. A rear-end collision prevention system that performs an avoiding operation, wherein the processing unit is configured to operate the rear-end collision avoiding means when the vehicle approaches the vehicle further, based on the own vehicle speed, the own vehicle deceleration, the preceding vehicle speed, and the deceleration of the preceding vehicle. A spare time, which is a difference between the derived avoidance start inter-vehicle time and a current inter-vehicle time derived by dividing the current inter-vehicle distance by the own vehicle speed, is calculated, and the extra time, which is a time change amount of the extra time, is calculated. A change speed and a marginal time change acceleration, which is a time change amount of the marginal time change speed, are calculated, and each of the marginal time, the marginal time change speed, and the certainty factor that is positive, negative, and zero for the marginal time change acceleration, respectively. A collision risk increase / decrease degree is calculated based on the calculated plurality of risk increase / decrease degree certainties, and when the cumulative value of the collision risk increase / decrease degree is larger than a predetermined value, the processing unit notifies the collision risk and the collision avoidance is performed. A method of determining a rear-end collision in a rear-end collision prevention system, characterized by driving a means.