WO2015151458A1

WO2015151458A1 - Onboard system and onboard program

Info

Publication number: WO2015151458A1
Application number: PCT/JP2015/001667
Authority: WO
Inventors: 哲郎足立
Original assignee: 株式会社デンソー
Priority date: 2014-03-31
Filing date: 2015-03-24
Publication date: 2015-10-08
Also published as: JP2015194895A

Abstract

This onboard system (1) is equipped with: an inter-vehicle distance measurement section (3a) that measures an inter-vehicle distance to a preceding vehicle from the host vehicle; an anticipated collision time calculation section (3b) that calculates an anticipated collision time at which the inter-vehicle distance becomes zero; a temporal change monitoring section (3d) that monitors temporal changes in the inter-vehicle distance on the basis of temporal changes in the anticipated collision time calculated by the anticipated collision time calculation section; and an operation control section (3e) for controlling predetermined operations to be performed by operation units (4-6) on the basis of the relationship between the inter-vehicle distance measured by the inter-vehicle distance measurement section and the temporal changes in the inter-vehicle distance being monitored by the temporal change monitoring section.

Description

In-vehicle system and in-vehicle program

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2014-72297 filed on March 31, 2014, the disclosure of which is incorporated herein by reference.

The present disclosure relates to an in-vehicle system and an in-vehicle program that perform a predetermined operation according to the distance between the host vehicle and a preceding vehicle.

2. Description of the Related Art Conventionally, an in-vehicle system that measures a distance between a host vehicle and a preceding vehicle and performs a predetermined operation such as, for example, a warning according to the measured distance between vehicles is provided. As a method of measuring the inter-vehicle distance, Patent Document 1 discloses a method of using the lane width (white line) as known information and measuring the inter-vehicle distance based on the lane width of the place where the preceding vehicle is located. Patent Document 2 discloses a technique for measuring a distance between vehicles based on the size of a license plate using a license plate of a preceding vehicle. Patent Document 3 discloses a method of measuring an inter-vehicle distance based on the principle of triangulation using two (a pair of left and right) optical systems. Patent Document 4 discloses a method of measuring the inter-vehicle distance based on the principle of triangulation using two cameras. In Patent Document 5, as an index of collision risk, TTC (Timesionto 示す Collision) indicating the time from the current time until the vehicle collides with the preceding vehicle is calculated, and according to the inter-vehicle distance. A configuration for performing a predetermined operation is disclosed.

JP-A-7-77421 JP 61-219825 A Japanese Patent Laid-Open No. 3-195916 JP 2000-266539 A JP 2012-98776 A

The inventor of the present application has found the following regarding the above-described technique.
In Patent Document 1, the lane width may be different between a general road and an expressway, and there is a possibility that the inter-vehicle distance is erroneously measured. In Patent Document 2, when the number plate of the preceding vehicle cannot be recognized, the inter-vehicle distance cannot be measured. In

Patent Documents

3 and 4, two optical systems and cameras are required, and the structure is complicated. In Patent Document 5, although the inter-vehicle distance can be measured without requiring a complicated structure as much as Patent Documents 1 to 4, it is not assumed that the speed of either the host vehicle or the preceding vehicle has changed. Therefore, there is a problem that when one of the own vehicle and the preceding vehicle changes in speed, the predetermined operation cannot be appropriately performed according to the inter-vehicle distance.

The present disclosure has been made in view of the above-described circumstances, and the object thereof is not to require a complicated configuration, and whichever of the own vehicle and the preceding vehicle changes the speed. An object of the present invention is to provide an in-vehicle system and an in-vehicle program that can appropriately perform a predetermined operation in accordance with an inter-vehicle distance from a vehicle to a preceding vehicle.

The on-vehicle system of an example of the present disclosure includes an inter-vehicle distance measurement unit, a collision expected time calculation unit, a time change monitoring unit, and an operation control unit. The inter-vehicle distance measurement unit measures the inter-vehicle distance from the host vehicle to the preceding vehicle. The predicted collision time calculation unit calculates a predicted collision time when the inter-vehicle distance is zero. The time change monitoring unit monitors the time change of the inter-vehicle distance based on the time change of the predicted collision time calculated by the predicted collision time calculation unit. The operation control unit controls a predetermined operation performed by the operation unit based on the relationship between the inter-vehicle distance measured by the inter-vehicle distance measurement unit and the time change of the inter-vehicle distance monitored by the time change monitoring unit.

When both the own vehicle and the preceding vehicle travel at a constant speed and the speed of the own vehicle is faster than the speed of the preceding vehicle, the own vehicle approaches the preceding vehicle. At this time, since the speed difference between the speed of the own vehicle and the speed of the preceding vehicle is constant, the change in the inter-vehicle distance from the own vehicle to the preceding vehicle is constant. Therefore, the predicted collision time at which the inter-vehicle distance is zero is constant (does not change) with any time as a reference. On the other hand, when either the own vehicle or the preceding vehicle changes the speed, the predicted collision time changes with the passage of time. Therefore, paying attention to the fact that the predicted collision time changes with time, the temporal change in the inter-vehicle distance is monitored based on the temporal change in the predicted collision time. And based on the relationship between the measured inter-vehicle distance and the time change of the inter-vehicle distance being monitored, the predetermined operation performed by the operation unit is controlled. That is, if the inter-vehicle distance monitoring the time change is larger than the measured inter-vehicle distance, it is determined that the possibility of collision is relatively small. On the other hand, if the inter-vehicle distance is smaller than the measured inter-vehicle distance, the possibility of collision is determined. Is determined to be relatively large, and a predetermined operation such as notifying a warning or controlling the behavior of the vehicle is performed. Thus, a predetermined operation is appropriately performed according to the distance between the own vehicle and the preceding vehicle, regardless of which of the own vehicle and the preceding vehicle changes the speed without requiring a complicated configuration. be able to.

An in-vehicle program according to an example of the present disclosure includes a first procedure for measuring an inter-vehicle distance from the host vehicle to a preceding vehicle and a second procedure for calculating an estimated collision time at which the inter-vehicle distance is zero. And a third procedure for monitoring the temporal change of the inter-vehicle distance based on the temporal change of the predicted collision time calculated by the second procedure, and the inter-vehicle distance measured by the first procedure and the third procedure. This is an in-vehicle program that executes a fourth procedure for controlling a predetermined operation performed by the operation unit (4 to 6) based on the relationship with the time change of the inter-vehicle distance.

Even with such an in-vehicle program, the same effect as the above-mentioned in-vehicle system can be achieved. Note that the in-vehicle program may be stored in a non-temporary storage medium.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the attached drawings
FIG. 1 is a functional block diagram illustrating an embodiment. FIG. 2 is a diagram illustrating the principle of measuring the inter-vehicle distance. FIG. 3 is a diagram illustrating the influence due to the difference in length of the object to be imaged. FIG. 4 is a diagram illustrating the relationship between the length x of the camera image and the distance Z with respect to shooting objects having different lengths. FIG. 5 is a diagram showing changes in the inter-vehicle distance. FIG. 6 is a diagram showing a change in the inter-vehicle distance when both the host vehicle and the preceding vehicle are traveling at a constant speed. FIG. 7 is a diagram showing a change in allowable time when both the host vehicle and the preceding vehicle are traveling at a constant speed. FIG. 8 is a diagram illustrating an example of a change in the inter-vehicle distance according to a change in the speed of the host vehicle or the preceding vehicle. FIG. 9 is a diagram illustrating another example of the change in the inter-vehicle distance according to the change in the speed of the host vehicle or the preceding vehicle. FIG. 10 is a diagram illustrating a classification of changes in the inter-vehicle distance. FIG. 11 is a diagram illustrating an example of prediction of a change in the inter-vehicle distance. FIG. 12 is a diagram illustrating another example of prediction of a change in the inter-vehicle distance. FIG. 13 is a first flowchart. FIG. 14 is a second flowchart. FIG. 15 is a third flowchart. FIG. 16 is a fourth flowchart.

Hereinafter, an embodiment will be described with reference to the drawings. A vehicle equipped with the in-vehicle system 1 is the own vehicle, and a vehicle traveling in front of the own vehicle is a preceding vehicle. The in-vehicle system 1 includes a camera 2 (imaging unit, imaging unit), a control unit 3 (control unit), a display unit 4 (display unit), a sound output unit 5 (sound output unit), and a vehicle behavior control unit 6. (Vehicle behavior control means, operation section, operation means). The camera 2 is a single-lens camera. The camera 2 is a CCD (Charge Coupled Device) image sensor that captures the front of the host vehicle, acquires a captured image at a frame period of a predetermined number of seconds (for example, 1/10 second), and acquires the captured image. Is output to the control unit 3. The camera 2 may be a CMOS (Complementary Metal Metal Oxide Semiconductor) image sensor. The display unit 4 is an example of an operation unit, an operation unit, a notification unit, and a notification unit. The sound output unit 5 is an example of an operation unit, an operation unit, a notification unit, and a notification unit.

The control unit 3 is mainly composed of a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 3 controls the overall operation of the in-vehicle system 1 by the CPU executing a control program (including the in-vehicle program) stored in the ROM. Based on the function to be executed, the control unit 3 includes an inter-vehicle distance measuring unit 3a (an inter-vehicle distance measuring unit), an image size calculating unit 3b (an image size calculating unit), and an estimated collision time calculating unit 3c (an estimated collision time calculating unit). ), A time change monitoring unit 3d (time change monitoring means), and an operation control unit 3e (operation control means). The image size calculation unit 3b, the predicted collision time calculation unit 3c, the time change monitoring unit 3d, the inter-vehicle distance measurement unit 3a, and the motion control unit 3e are configured by software.

The inter-vehicle distance measuring unit 3a measures the inter-vehicle distance from the host vehicle to the preceding vehicle. The image size calculation unit 3 b calculates the image size of the preceding vehicle that occupies the captured image acquired by the camera 2. The predicted collision time calculation unit 3c uses the image size calculated by the image size calculation unit 3b and the shooting time when the camera 2 shots the front of the host vehicle, and the speed of the host vehicle and the speed of the preceding vehicle at the shooting time. When the host vehicle continues to travel at a relative speed that is a difference from the above, a predicted collision time at which the inter-vehicle distance from the host vehicle to the preceding vehicle becomes zero is calculated. The time change monitoring unit 3d monitors the time change of the inter-vehicle distance from the host vehicle to the preceding vehicle based on the time change of the predicted collision time calculated by the predicted collision time calculation unit 3c. Based on the relationship between the inter-vehicle distance measured by the inter-vehicle distance measuring unit 3a and the time change of the inter-vehicle distance monitored by the time change monitoring unit 3d, the operation control unit 3e displays the display unit 4, the sound output unit 5, and the vehicle behavior. The operation of the control unit 6 is controlled.

When the display command signal is input from the control unit 3, the display unit 4 displays various screens such as a warning screen (draws) based on the input display command signal. When the sound output command signal is input from the control unit 3, the sound output unit 5 outputs various sounds such as a warning sound based on the input sound output command signal. When a vehicle behavior command signal is input from the control unit 3, the vehicle behavior control unit 6 controls various vehicle behaviors such as brake control based on the input vehicle behavior command signal.

Next, the principle of the present invention will be described. First, the principle of measuring the inter-vehicle distance from the host vehicle to the preceding vehicle is shown in FIG. In this case, each term is defined as follows.

2W ₀ : Length of object to be photographed (vehicle width of preceding vehicle)
Z ₁ , Z ₂ : Distance from the origin O (the center of the lens of the camera 2) to the object to be photographed (distance between the vehicles)
2x _1: origin O distance to the object to be shot from the length of the shooting target on the CCD imaging plane when the "Z _1" (the vehicle width of the preceding vehicle) length equivalent camera image 2x _2: Origin The length of the camera image corresponding to the length of the object to be photographed on the CCD image plane (vehicle width of the preceding vehicle) when the distance from O to the object to be photographed is “Z ₂ ” R _x , R _y : CCD Resolution in the x and y directions φ _x , φ _y : CCD viewing angle on the x and y axes l: Distance from the origin O to the CCD image plane In this case, the distance from the origin O to the CCD image plane is ,

It becomes. The relationship between the distance from the origin O to the object to be photographed and the size on the CCD image plane is
_{_{_{x 1 / l = W 0 /}}} Z l ··· (2)
x ₂ / l = W ₀ / Z ₂ (3)
It becomes. Therefore, from the equations (2) and (3),
_{_{_{_{x 1 / x 2 = Z 2}}}} / Z l ··· (4)
∴Z ₂ = x ₁ Z ₁ / x ₂ (5) In the equation (5), when x ₁ with respect to Z ₁ is obtained in advance as a reference value, if the inter-vehicle distance for any x is Z,
Z = x ₁ Z ₁ / x (6)
It becomes.

Next, Fig. 3 shows the effect of the vehicle width difference of the preceding vehicle. Each term is defined as follows.

2W ₁ : Length of the reference imaging object 2W ₂ : Length of the other imaging object Z ₁ : Distance from the origin O to the reference imaging object Z ₂ : Distance from the origin O to another imaging object In this case, the length of the image on the CCD image plane of the other imaging object length (2W ₂ ) is set to the length of the image on the CCD image plane of the reference imaging object length (2W ₁ ). When arranged so as to be aligned to (2 × ₁ ), the following relationship is established.

_{_{_{_{2W 1 / Z l = 2W 2}}}} / Z 2 ··· (7)
∴Z ₂ = (W ₂ / W ₁ ) Z _l (8)
That is, as shown in FIG. 4, always W _{2 /} W ₁ × distance of Z ₁ of the standard photography object becomes the distance from the origin O to the other of the object to be shot. When the distance is measured using a photographed image photographed by one camera 2, the length of the image on the CCD image plane may be the same for the photographing objects having different lengths as described above. When the distance to the object does not change with time, it is impossible to measure the distance to the imaging object having a different shape.

On the other hand, it is assumed that the distance to the object to be photographed changes with time. At intervals of unit time Δt (for example, 1 second), the distance from the photographed image to the object to be photographed at that time is obtained by equation (6). A linear equation Z = at + b passing through a point A at a distance Z (t) at time t and a point B at a distance Z (t−Δt) at time (t−Δt) is as shown in FIG. In this linear equation, when the vehicle continuously travels at a speed at time t (constant speed travel), the time t _p when Z = 0 becomes t _p = −b / a. (T _p -t) indicates that the distance to the object to be photographed becomes zero after (t _p -t) seconds when the vehicle travels at a constant speed based on the speed (relative speed) at time t.

Generally, the values of a and b of a straight line y = ax + b passing through two points (x1, y1) (x2, y2) are obtained as follows.

a = (y1-y2) / (x1-x2) (9)
b = (x1y2-x2y1) / (x1-x2) (10)
When the formulas (9) and (10) are applied to FIG. 5, the formula of the straight line passing through the two points AB is as follows.

a = − [Z (t−Δt) −Z (t)] / Δt (11)
b = − [(t−Δt) Z (t) −tZ (t−Δt)] / Δt (12)
The value of the Z = 0 _t = t _p is as follows.

t _p = − [(t−Δt) Z (t) −tZ (t−Δt)] /
[Z (t−Δt) −Z (t)] (13)
As shown in FIG. 3, when the _{t p} of the standard photography object length 2W ₁ and _{t p1,} the _{t p} other shooting target length 2W ₂ and _{_{t _p2,} t} _p1, _{t p2} Are as follows.

t _p1 = − [(t−Δt) Z ₁ (t) −tZ ₁ (t−Δt)] /
[Z ₁ (t−Δt) −Z ₁ (t)] (14)
t _p2 = − [(t−Δt) Z ₂ (t) −tZ ₂ (t−Δt)] /
[Z ₂ (t−Δt) −Z ₂ (t)] (15)
Further, from the equation (8), Z ₂ (t) = (W ₂ / W ₁ ) Z ₁ (t) = αZ ₁ (t) (α is a coefficient)
t _p2 = − [(t−Δt) αZ ₁ (t) −tαZ ₁ (t−Δt)] /
_{[ΑZ 1 (t- △ t)} -αZ 1 (t)]
= − [(T−Δt) Z ₁ (t) −tZ ₁ (t−Δt)] /
[Z ₁ (t−Δt) −Z ₁ (t)]
= T _p1 (16)
∴ t _p1 = t _p2 (17)
It becomes.

(17), the time t _p the distance to the imaging target in the case where continues to move at a speed at an arbitrary time t (or relative movement) becomes zero, the length reference of the object imaging target Even if it is different from the thing, it shows that it is the same. By using this principle and paying attention to the change in the inter-vehicle distance from the host vehicle to the preceding vehicle, the inter-vehicle distance can be measured under the same conditions regardless of the length (size) of the subject.

Here, it is possible to obtain practically on the system, since the image size x of the camera 2 relative to the distance Z, as shown in equation (8), equation for t _p with x is ( Substituting equation (6) into equation 13) yields the following. That is,
t _p = − [(t−Δt) Z (t) −tZ (t−Δt)] /
[Z (t−Δt) −Z (t)]
If Z (t) = x ₁ Z ₁ / x (t) is substituted into
t _p = − [(t−Δt) x (t−Δt) −tx (t)] /
[X (t) −x (t−Δt)] (18)
Equation (18) is expressed as follows: a size x (t−Δt) and x (t) when an arbitrary object changes on the screen of the camera 2 in a unit time Δt from time (t−Δt) to t. by obtaining the information of t), indicating that the time t _p the distance to the object becomes zero is obtained. Further, if it is possible to capture the same object image, if any in the object shape x (t) is obtained, indicating that t _p is measurable with the same formula.

Next, TTC (Time to Collision), which is an index of collision risk that the own vehicle collides with the preceding vehicle, will be described.

First, FIG. 6 shows the change in the inter-vehicle distance when both the host vehicle and the preceding vehicle are traveling at a constant speed, and the host vehicle is approaching the preceding vehicle, and FIG. 7 shows the change in TTC. Each term is defined as follows.

Va: own vehicle speed Vb: own vehicle speed Z: inter-vehicle distance When both the own vehicle and the preceding vehicle are traveling at a constant speed and the preceding vehicle is traveling at a speed slower than the own vehicle, the own vehicle Approaches the preceding car. At this time, since the speed difference between the speed of the own vehicle and the speed of the preceding vehicle is constant, the change in the inter-vehicle distance from the own vehicle to the preceding vehicle is constant. Therefore, if the time when the inter-vehicle distance becomes zero is “t _p ” and the current time is “t”, “t _p ” does not change and “TTC” is “t _p ” regardless of the time. This is the same as the value obtained by subtracting “t” from. For example, the distance between vehicles: 100m (t = 0)
Speed of preceding vehicle: 15m / sec
Speed of own vehicle: 20m / sec
When, using a _{t p} (13) equation, the calculated at _{t = 1, △△ t p =} - [(t- △ t) Z (t) -tZ (t- △ t)] /
[Z (t−Δt) −Z (t)]
=-[(1-1) × 95-1 × 100] /
(100-95) = 20 (19)
It becomes.

Actually, both the own vehicle and the preceding vehicle do not always travel at a constant speed. Thus, we analyzed for t _p when either the speed of the host vehicle and the preceding vehicle has changed. State in which both the vehicle and the preceding vehicle is traveling at a constant speed of t _p value when either of the (own speed of the vehicle speed> the preceding vehicle) of the vehicle or the preceding vehicle starts accelerating or decelerating The change is shown in FIG. A straight line passing through the two points BA indicates a case where both the host vehicle and the preceding vehicle are traveling at a constant speed. In this case, the change in the inter-vehicle distance is always constant, is a t _p is constant. On the other hand, a straight line passing through the two points BA ₁ indicates a case where the host vehicle starts to decelerate or a preceding vehicle starts to accelerate. In this case, the change in distance between the vehicles, since both the vehicle and the preceding vehicle becomes smaller than when the vehicle travels at a constant speed (constant-speed traveling), t _p is a value greater than the constant-speed running Become. On the other hand, a straight line passing through the two points BA ₂ indicates a case where the host vehicle starts to accelerate or a preceding vehicle starts to decelerate. In this case, the change in distance between the vehicles, since larger than during constant speed running, t _p becomes smaller than the constant-speed running.

Further, in FIG. 9, when the slope of the straight line is positive, it indicates that (t _p -t) is negative, and the inter-vehicle distance is widened because the own vehicle starts decelerating or the preceding vehicle starts accelerating. Indicates that On the other hand, if the slope of the straight line is negative, it indicates that (t _p -t) is positive, indicating that the distance between the vehicles has been shortened because the host vehicle has started acceleration or the preceding vehicle has started to decelerate. Show. If the deceleration is activated, it indicates t _p in the case of constant speed running at an average value of the speed at two points in the unit time, the line connecting the two points is always changing it. Therefore, if there is a change in speed, it is not possible to deal with t _p time varying as the allowable time to a vehicle collision, by using a time variation of t _p, attention arouse system Ya the approaching a preceding vehicle It can be used as a system for controlling vehicle behavior and realize convenient functions.

When both the host vehicle and the preceding vehicle are traveling at a constant speed, the change in the inter-vehicle distance is constant, whereas when either the host vehicle or the preceding vehicle starts decelerating, the inter-vehicle distance Change is not constant. Specifically, if the inter-vehicle distances at (t−2Δt), (t−Δt) and t are Z (t−2Δt), Z (t−Δt) and Z (t), The relationship shown in FIG. Less than,
(1) When the host vehicle approaches the preceding vehicle and starts decelerating (2) The case where the host vehicle starts decelerating after the preceding vehicle starts decelerating will be sequentially described.

(1) When the host vehicle approaches the preceding vehicle and starts decelerating When both the host vehicle and the preceding vehicle are traveling at a constant speed and the host vehicle approaches the preceding vehicle, No. 1 shown in FIG. 1 state. T _p in this case refers to a certain time. When the t _p becomes a certain value to start the safety deceleration (point A), the vehicle stops at the point B to maintain the inter-vehicle distance immediately before collision when decelerating at a constant acceleration (or, prior Find the limit speed change with a quadratic function. FIG. 11 shows the prediction of the change in the inter-vehicle distance when the host vehicle approaches the preceding vehicle and starts deceleration. In FIG. 11, the two-dimensional equation of the section AB is expressed as Z = a (t−t _c ) ² (20)
And t _c is the time at point B where Z = 0, and a is a coefficient.

Although the slope of the equation (20) at the point A is dZ / dt, it is also the slope of the straight line of the change in the inter-vehicle distance (section AC) when not decelerating. From equation (20)
dZ / dt = 2a (t−t _c ) (21)
And when t = 0,
dZ / dt = -2 at _c (22)
It becomes. Therefore, the equation of the line segment AC is Z = −2 at _c t + at _c ² = −at _c (2 t−t _c ) (23)
It becomes. Time _{t p} of the point C as the Z = 0 than (23),
t _p = t _c / 2 (24)
It becomes. Also, the value of Z (0) at t = 0 is obtained from the equation (20).
_{^{a = Z (0) / t}} c 2 = Z (0) / 4t p 2 ··· (25)
Therefore, the equation (20) is as follows.

Z (t) = Z (0) (t−2t _p ) ² / 4t _p ² (26)
It becomes.

In equation (26), if deceleration is started so that the following relational expression is established in the section AB, a safe inter-vehicle distance can be secured.

Z (t)> Z (0) (t−2t _p ) ² / 4t _p ² (27)
The expression (27) is represented by x as follows.

x (t) <4t _p ² x (0) / (t−2t _p ) ² (28)
Here, _{t p} is obtained from the equation (18).

(2) When the host vehicle starts decelerating after the preceding vehicle starts decelerating When the preceding vehicle starts decelerating when the host vehicle is following at the same speed as the preceding vehicle, No. shown in FIG. 3 state. FIG. 12 shows a prediction of a change in the inter-vehicle distance when the host vehicle starts decelerating after the preceding vehicle starts decelerating. In FIG. 12, the time when the preceding vehicle starts decelerating at point A is set to t = 0. Assuming that the point A2 (time t = 2Δt) where the change in the inter-vehicle distance is about 5%, if the point at the time t = Δt is A1, the relationship between the inter-vehicle distances at the points A, A1, A2 is The relationship of No. 3 shown in FIG. When the acceleration of deceleration of the preceding vehicle is constant, the change in the inter-vehicle distance becomes a quadratic function, so that it becomes a parabola AB passing through A1 and A2 as shown in FIG.

Parabolic formula,
Z _A = at ² + c (29)
The _{Z A} when the _{t = 0, t 1 = 2} △ t Z A (0), when the Z A _{(t 1),}
Z _A (t ₁ ) = at ₁ ² + Z _A (0) (30)
a = [Z _A (t ₁ ) −Z _A (0)] / t ₁ ² (31)
Z _A (t) = [Z _A (t ₁ ) −Z _A (0)] t ² / t ₁ ² + Z _A (0) (32)

Next, a parabola having the same magnitude as equation (32), a coefficient of a quadratic term in the opposite direction, and a minimum value at Z = 0 is assumed. Assuming that t having the minimum value is t _c , the equation Z _B is as follows.

Z _B = [Z _A (0) −Z _A (t ₁ )] (t t _c ) ² / t ₁ ² (33)
When the expression (33) is obtained so that the expression (32) and the expression (33) are in contact with each other in the range of t> 0,
dZ _A / dt = 2 [Z _A (t ₁ ) −Z _A (0)] t / t ₁ ² (34)
dZ _B / dt = 2 [Z _A (0) −Z _A (t ₁ )] (tt _c ) / t ₁ ² ... (35) From t, dZ _A / dt = dZ _B / dt The value of
[Z _A (t ₁ ) −Z _A (0)] t = [Z _A (0) −Z _A (t ₁ )] (t−t _c ) (36)
2 [Z _A (t ₁ ) −Z _A (0)] t = − [Z _A (0) −Z _A (t ₁ )] t _c (37)
t = t _c / 2 (38)
Therefore, it can be seen that contact at a point E which corresponds to the midpoint of from 0 to t _c. When t _c at this time is obtained,

If the host vehicle is decelerated so as to satisfy Z (t) ≧ Z _B (t) in the section of t _c / 2 ≦ t ≦ t _c , it reaches a stop (or the same speed) state without colliding with the preceding vehicle. be able to.

α = Z _A (t ₁ ) / Z _A (0) = x _A (0) / x _A (t ₁ )
Then,

Also, since the relationship Z (t) x (t) = Z _A (0) x _A (0) is established,

That is, after t _c is obtained by the equation (41), Z (t) or x (t) is satisfied so that the equation (44) or (47) is established in the range of t _c / 2 ≦ t ≦ t _c. By decelerating so as to obtain the following distance, the inter-vehicle distance to the preceding vehicle can be maintained so as not to collide.

In the range of t ₁ ≦ t ≦ t _c / 2, a safe inter-vehicle distance can be secured by starting deceleration so that the following expression (48) or (49) is satisfied from the expression (32). It is possible to continue.

In the range of 0 ≦ t ≦ t _c / 2, a safe inter-vehicle distance can be secured by starting deceleration so that the equation (32) or the following equation (50) is satisfied. .

Next, the operation of the above-described configuration will be described with reference to FIGS.

The control part 3 is related to this embodiment, and performs a collision determination process regularly with a predetermined period. When the collision determination process is started, the control unit 3 performs initial setting (S1) and determines whether or not the engine is stopped (S2). If it is determined that the engine is not stopped (running) (S2: NO), the controller 3 determines whether ΔT seconds have elapsed (ΔT seconds have passed) or not (S3). If the controller 3 determines that it is ΔT seconds later (S3: YES), it inputs (captures) a captured image from the camera 3 (S4). And the control part 3 detects a preceding vehicle in the input picked-up image (S5), and determines whether a preceding vehicle exists in the picked-up image (S6). When the control unit 3 determines that there is no preceding vehicle in the captured image (S6: NO), the control unit 3 returns to step S1 described above, and repeatedly executes step S1 and subsequent steps.

On the other hand, if the control unit 3 determines that the preceding vehicle is present in the captured image (S6: YES), it measures and records the inter-vehicle distance Z (t) from the host vehicle to the preceding vehicle (S7) (first) procedure). At this time, the control unit 3 calculates the image size of the preceding vehicle in the captured image (fifth procedure). Next, the control unit 3 compares Z (t−2Δt), Z (t−Δt), and Z (t) (S8). In this case, the control unit 3 sets Δt = nΔT (n is a natural number).

The control unit 3 determines whether or not the following first relationship is established (S9).

Z (t−2Δt)> Z (t−Δt)> Z (t) (first relation)
If the control part 3 determines with the 1st relationship not being materialized (S9: NO), it will return to above-described step S1.

On the other hand, when determining that the first relationship is established (S9: YES), the control unit 3 determines whether or not the following second relationship is established (S10).

Z (t−2Δt) + Z (t) = 2Z (t−Δt) (second relation)
When it is determined that the second relationship is established (S10: YES), the control unit 3 determines that both the host vehicle and the preceding vehicle are traveling at a constant speed.

Control unit 3, when both the host vehicle and the preceding vehicle is determined to be traveling at a constant speed, it is determined whether the already calculated t _c (S12). Control unit 3 determines that not been calculated _{t c (S12: NO),} (14) or (18) time using equation t, calculates a _{t p} in (t-△ t) (S13) . Then, the control unit 3 calculates the time from the current time up to t _p where the calculated, compares the time and limit time from the current time of the calculated until t _p (S14). The limit time is the maximum time that can wait for warning notification.

Control unit 3, when the time from the current time until t _p is determined not less than the critical hours (S14: NO), a normal range can afford the inter-vehicle distance, is a possibility that the vehicle will collide with the preceding vehicle It determines with it being relatively low, outputs the signal of a normal range (S15), and returns to above-mentioned step S2. On the other hand, the control unit 3, when the time from the current time until t _p is determined to be equal to or less than the limit hours (S14: YES), there is no margin in the inter-vehicle distance, a possibility that the vehicle will collide with the preceding vehicle relative Is determined to be high, an approach warning signal is output (S16), and the process returns to step S2. That is, the control unit 3 outputs an approaching caution display command signal indicating that the host vehicle is approaching the preceding vehicle to the display unit 4, and outputs an approaching caution sound output command signal to the sound output unit 5. The process returns to step S2. The display unit 4 displays a warning screen when a display command signal for approaching attention is input from the control unit 3. The sound output unit 5 outputs a warning sound when receiving a display command signal for approaching attention from the control unit 3. Thereby, it is possible to notify the driver that the possibility that the host vehicle will collide with the preceding vehicle is relatively high.

On the other hand, when the control unit 3 determines that the above-described second relationship is not established (S10: NO), the control unit 3 determines whether the following third relationship is established (S11).
Z (t−2Δt) + Z (t)> 2Z (t−Δt) (third relation)
When determining that the third relationship is established (S11: YES), the controller 3 determines that the preceding vehicle is traveling at a constant speed and that the host vehicle has started to decelerate. The control unit 3 determines the preceding vehicle is traveling at a constant speed, when it is determined that the vehicle has started decelerating, whether it is already calculated t _p (S17). Control unit 3 determines that not been calculated _{t p} (S17: NO), determines whether the already calculated _{t c} (S18). Control unit 3 determines that not been calculated _{t c (S18: NO),} (13) or (18) time using equation t, calculates a _{t p} in (t-△ t) (S19) (Second procedure).

The control unit 3 determines whether the expression (27) or (28) is established at the current time t (S20) (third procedure). When it is determined that the expression (27) or (28) is established at the current time t (S20: YES), the control unit 3 determines that it is in the normal range, and outputs a signal in the normal range (S21). Return to step S2. On the other hand, when the control unit 3 determines that the equations (27) and (28) are not satisfied at the current time t (S20: NO), the control unit 3 determines that the possibility that the host vehicle collides with the preceding vehicle is relatively high. Then, an approach warning signal is output (S22) (fourth procedure), and the process returns to step S2. Also in this case, the display unit 4 displays a warning screen when the display instruction signal for approaching attention is input from the control unit 3. The sound output unit 5 outputs a warning sound when receiving a display command signal for approaching attention from the control unit 3. Thereby, it is possible to notify the driver that the possibility that the host vehicle will collide with the preceding vehicle is relatively high.

On the other hand, when determining that the third relationship is not established (S11: NO), the control unit 3 determines that the preceding vehicle starts decelerating and the host vehicle is traveling at a constant speed. Control unit 3, the preceding vehicle starts decelerating, the vehicle is determined to be traveling at a constant speed, it is determined whether the already calculated t _c (S23). Control unit 3 determines that not been calculated _{t c} (S23: NO), the following relation determines whether satisfied (S24).

αZ (t−2Δt)> Z (t) (1>α> 0)
Control unit 3 determines that the relationship is satisfied (S24: YES), obtains the _{t c} using (41) Equation (S25). Next, the control unit 3 determines whether or not t ₁ ≦ t ≦ t _c / 2 is satisfied (S26). If it is determined that t ₁ ≦ t ≦ t _c / 2 is not satisfied (S26: NO), the control unit 3 determines whether t _c / 2 ≦ t ≦ t _c is satisfied (S27). Control unit 3 _determines that _{_{t c / 2 ≦ t ≦ t}} c is satisfied (S27: YES), (44) or (47) determines whether the expression is satisfied (S28). When it is determined that the formula (44) or the formula (47) is established (S28: YES), the control unit 3 determines that the range is in the normal range, outputs a signal in the normal range (S29), and returns to step S2 described above. . On the other hand, if the control unit 3 determines that neither the formula (44) nor the formula (47) is established (S28: NO), the control unit 3 determines that the possibility that the host vehicle collides with the preceding vehicle is relatively high, and approaches. A caution signal is output (S30), and the process returns to step S2. Also in this case, the display unit 4 displays a warning screen when the display instruction signal for approaching attention is input from the control unit 3. The sound output unit 5 outputs a warning sound when receiving a display command signal for approaching attention from the control unit 3. Thereby, it is possible to notify the driver that the possibility that the host vehicle will collide with the preceding vehicle is relatively high.

If it is determined that t ₁ ≦ t ≦ t _c / 2 is satisfied (S26: YES), the controller 3 determines whether or not the expression (48) or (49) is satisfied (S31). When it is determined that the formula (48) or the formula (49) is established (S31: YES), the control unit 3 determines that the range is in the normal range, outputs a signal in the normal range (S29), and returns to step S2 described above. . On the other hand, if the control unit 3 determines that neither the formula (48) nor the formula (49) is established (S31: NO), the control unit 3 determines that the possibility that the host vehicle collides with the preceding vehicle is relatively high, and approaches. A caution signal is output (S30), and the process returns to step S2. Also in this case, the display unit 4 displays a warning screen when the display instruction signal for approaching attention is input from the control unit 3. The sound output unit 5 outputs a warning sound when receiving a display command signal for approaching attention from the control unit 3. Thereby, it is possible to notify the driver that the possibility that the host vehicle will collide with the preceding vehicle is relatively high.

As described above, according to the present embodiment, in the in-vehicle system 1, paying attention to which of the own vehicle and the preceding vehicle changes the speed, the expected collision time changes as time elapses. The time change of the inter-vehicle distance is monitored based on the time change. Then, the notification operation is controlled based on the relationship between the measured inter-vehicle distance and the time variation of the monitored inter-vehicle distance. That is, if the inter-vehicle distance monitoring the time change is larger than the measured inter-vehicle distance, it is determined that the possibility of collision is relatively small. On the other hand, if the inter-vehicle distance is smaller than the measured inter-vehicle distance, the possibility of collision is determined. Is determined to be relatively large, and a warning is notified. Thus, the notification operation is appropriately performed according to the inter-vehicle distance from the own vehicle to the preceding vehicle regardless of which of the own vehicle and the preceding vehicle changes the speed without requiring a complicated configuration. be able to.

Embodiments are not limited to the above-described embodiments, but include embodiments modified or expanded as follows.

Although the configuration in which the inter-vehicle distance is measured using a single-lens camera is exemplified, the inter-vehicle distance may be measured using a two-lens camera or a distance measuring sensor such as a radar. That is, the estimated collision time when the distance between vehicles measured using a distance measuring sensor such as a two-lens camera or a radar is zero is calculated, and the time variation of the distance between vehicles is monitored based on the time variation of the calculated estimated collision time. You may do it.

Although it has been determined that the possibility that the host vehicle collides with the preceding vehicle is relatively high, the display unit 4 displays a warning screen and the sound output unit 5 outputs a warning sound as a predetermined operation. For example, vehicle control such as brake control may be performed so that the vehicle behavior control unit 6 avoids a collision.

Claims

An inter-vehicle distance measuring unit (3a) for measuring an inter-vehicle distance from the host vehicle to a preceding vehicle;
A predicted collision time calculation unit (3c) that calculates a predicted collision time when the inter-vehicle distance is zero;
A time change monitoring unit (3d) for monitoring the time change of the inter-vehicle distance based on the time change of the predicted collision time calculated by the expected collision time calculation unit;
Based on the relationship between the inter-vehicle distance measured by the inter-vehicle distance measuring unit and the time variation of the inter-vehicle distance monitored by the time variation monitoring unit, the predetermined operation performed by the operation unit (4 to 6) is controlled. An in-vehicle system (1) including an operation control unit (3e).
In the in-vehicle system according to claim 1,
A photographing unit (2) for photographing the front of the host vehicle and acquiring a photographed image;
An image size calculation unit (3b) that calculates an image size of a preceding vehicle in the captured image acquired by the imaging unit;
The predicted collision time calculation unit uses the image size calculated by the image size calculation unit and the shooting time when the front of the host vehicle was shot by the shooting unit, and the speed of the host vehicle at the shooting time and the preceding vehicle A vehicle-mounted system that calculates a predicted collision time at which the inter-vehicle distance becomes zero when the host vehicle continues to travel at a relative speed that is a difference from the speed of the vehicle.
In the in-vehicle system according to claim 1 or 2,
The said operation | movement part is a vehicle-mounted system containing the alerting | reporting part (4, 5) which alert | reports a warning.
In the in-vehicle system according to claim 3,
The said alerting | reporting part is a vehicle-mounted system containing at least any one of the display part (4) which alert | reports a warning by a display, and the sound output part (5) which alert | reports a warning by sound output.
In the in-vehicle system according to claim 1 or 2,
The said operation | movement part is a vehicle-mounted system containing the vehicle behavior control part (6) which controls the behavior of a vehicle.
In the control unit (3) of the in-vehicle system (1)
A first procedure for measuring an inter-vehicle distance from the host vehicle to a preceding vehicle;
A second procedure for calculating a predicted collision time at which the inter-vehicle distance is zero;
A third procedure for monitoring the time change of the inter-vehicle distance based on the time change of the predicted collision time calculated by the second procedure;
Based on the relationship between the inter-vehicle distance measured by the first procedure and the time change of the inter-vehicle distance monitored by the third procedure, a predetermined operation performed by the operation unit (4 to 6) is controlled. The in-vehicle program which performs 4 procedures.
In the in-vehicle program according to claim 6,
Including a fifth procedure for calculating the image size of the preceding vehicle in the captured image acquired by the imaging unit (2) that captures the front of the host vehicle,
In the second procedure, using the image size calculated in the fifth procedure and the shooting time when the front of the host vehicle was shot by the shooting unit, the speed of the host vehicle and the speed of the preceding vehicle at the shooting time A vehicle-mounted program for calculating a predicted collision time at which the inter-vehicle distance becomes zero when the host vehicle continues to travel at a relative speed that is a difference from the vehicle.