JP3218826B2 - Advance vehicle approach warning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preceding vehicle approach warning device which detects an inter-vehicle distance from a host vehicle to a preceding vehicle and issues a warning to a driver when the vehicle approaches excessively.

[0002]

2. Description of the Related Art As a conventional preceding vehicle approach warning device,
For example, there is one described in Japanese Utility Model Laid-Open Publication No. 1-152282. In this device, an electromagnetic wave (for example, a laser beam) is emitted in front of a vehicle, a reflected wave of the electromagnetic wave is received, and a distance R from a propagation delay time from output to reception is detected from a reflector. Then, the warning distance Rs calculated based on the relative speed and the like is compared with the measured distance R,
If the actual distance R is shorter than the warning distance Rs, the driver is warned that the vehicle is approaching too far.
The above-mentioned warning distance corresponds to the minimum distance that can be safely stopped or avoided with a margin, and if it is less than that, it will be in an excessively close state. The above-mentioned warning distance Rs is given by the following (Equation 1) if the vehicle speed of the own vehicle is Va, the idle running time is Td, the deceleration is α, and the relative speed between the own vehicle and the preceding vehicle is d / dtR.
It is determined by the formula.

[0003]

(Equation 1)

[0004] The idle running time Td is the time from when the driver determines that the vehicle is approaching too far to when deceleration or braking is actually performed. In addition, when the driver is traveling with a safe distance between the vehicles in that situation, or when the driver keeps approaching immediately before passing, the above-mentioned one-stage warning sounds as above. Keeps ringing, which hinders comfortable driving and reduces the driver's attention to warnings due to too much warning,
It becomes impossible to call attention to excessive approach which is the original purpose of the alarm. Therefore, in the above-mentioned conventional preceding vehicle approach warning device, the second warning distance R ₀ shorter than the warning distance Rs is set, and the first warning distance R ₀ is set when the actual inter-vehicle distance R becomes equal to or less than the warning distance Rs. The alarm is set in two stages so as to generate a second alarm when the distance becomes equal to or less than a second alarm distance R _0, and is stopped after a first alarm signal is generated for a certain time in the first stage. The alarm is prevented from sounding continuously, and further, the second alarm is continuously generated in the second stage in which no further approach is required. Further, in the above-mentioned conventional preceding vehicle approach warning device, a warning is generated by comparing the actual inter-vehicle distance R with the warning distance Rs, but the inter-vehicle distance R is divided by the own vehicle speed Va as a physical quantity to be warned. A preceding vehicle approach warning device using the inter-vehicle time Th is also conceivable. In this case, an alarm is generated by comparing the above-mentioned inter-vehicle time Th with the inter-vehicle time to be warned. This method has substantially the same physical meaning as that based on the distance.

[0005]

The above-mentioned conventional approaching warning device for a preceding vehicle has the following problems. That is, in such an alarm device, a constant for an alarm is generally selected so that any driver can drive safely. Therefore, an alarm generated when the vehicle approaches the preceding vehicle is generated from a very far distance. Tends to be. In particular, the idling time Td varies greatly depending on the driver, but in the conventional alarm device, since importance is placed on safety, a large value is taken in accordance with the characteristics of a longer driver, and is too far depending on the driver. The user often feels uncomfortable that an alarm is generated. In addition, there is a problem in that alerts are generated too frequently, so that attention to an alert in a situation where an alert is really required is reduced. Originally, in a preceding vehicle approach warning device, it is ideal if an alarm can be generated only in an area where an individual driver feels that the vehicle is approaching excessively. The problem that the driver's attention is reduced and the driver cannot be alerted to the driver's excessive approach, which is the original purpose of the alarm, should not occur. Normally, if normal recognition and judgment are performed, it is easy to understand that all drivers can drive without a rear-end collision, so only a warning is issued in an over-close area where each driver feels the possibility of a rear-end collision. It is possible in principle to prevent a rear-end collision by generating the deceleration and starting the deceleration action.
However, since the over-approaching area in which the driver feels the possibility of a rear-end collision has a large individual difference for each driver, it is actually practical to generate an alarm in an area where each driver is satisfied. It was extremely difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and an object of the present invention is to provide a preceding vehicle approach warning device capable of generating an appropriate warning in an area suitable for each driver's personality. The purpose is to provide.

[0007]

In order to achieve the above object, the present invention is configured as described in the appended claims. FIG. 1 is a functional block diagram corresponding to the first aspect of the present invention. In FIG. 1, an inter-vehicle distance detecting means 1 detects an inter-vehicle distance between a host vehicle and a preceding vehicle. This inter-vehicle distance detecting means 1 is, for example, shown in FIG.
Corresponds to the radar device 21 in the embodiment. The own vehicle speed detecting means 3 detects the running speed of the own vehicle. The own vehicle speed detecting means 3 corresponds to, for example, a vehicle speed sensor 23 in the embodiment of FIG. The vehicle speed detecting means 3 is not described in claim 1, but is described in claim 2. Further, the deceleration start detecting means 13 detects that the driver has started deceleration. This deceleration start detecting means 13
Is the brake sensor 2 in the embodiment of FIG.
Equivalent to 9. Further, the relative speed calculating means 5 calculates the relative speed of the preceding vehicle with respect to the own vehicle from the temporal change of the detected inter-vehicle distance. The deceleration start margin time calculating means 15
Receives the output of the deceleration start of the deceleration start detection means 13,
An allowance time is calculated by dividing the inter-vehicle distance detection value at that time by the relative speed. The spare time storage means 17 stores a spare time at the start of the deceleration action for each deceleration. Also, prediction time estimation means 19, the minimum value of the margin time during each deceleration behavior stored in the spare time storage unit 17, estimates a predicted time of the driver. The predicted time is the case, there by the time the driver was expected at the time the driver starts the decelerating operation and expected to be excessively approaching state future
Means the time from when the predicted deceleration operation is started to when the vehicle approaches the over approach state. The inter-vehicle distance predicted value calculation means 7 calculates an inter-vehicle distance predicted value. This inter-vehicle distance predicted value is a predicted value of the inter-vehicle distance after the predicted time, and is a value obtained by subtracting a value obtained by multiplying the detected relative speed value by the predicted time estimated value from the detected inter-vehicle distance value. The warning determining means 9 determines that a warning is issued when the predicted distance between vehicles is shorter than the warning distance. The above-described relative speed calculation means 5, deceleration start allowance time calculation means 15, allowance time storage means 1
7. Predicted time estimating means 19, inter-vehicle distance predicted value calculating means 7
The alarm determining means 9 corresponds to, for example, the information processing circuit 25 in the embodiment of FIG. Further, the alarm generating means 11 issues an alarm to the driver according to the judgment of the alarm judging means 9. The alarm generation means 11 corresponds to, for example, an alarm generation device 27 in the embodiment of FIG.

Next, a second aspect of the present invention is the first aspect.
In the invention described in (1), the warning determination means 9 has, as the warning distance, a primary warning distance calculated according to a traveling variable including at least the own vehicle speed, and a secondary warning distance shorter than the primary warning distance. Then, the inter-vehicle time predicted value is compared with the two alarm distances, and if the inter-vehicle time predicted value is equal to or less than the primary alarm distance and greater than the secondary alarm distance, it is determined that a primary alarm is to be issued, and the secondary alarm is determined. When the distance is less than the distance, it is determined that a secondary alarm is issued. The invention according to claim 3 is a vehicle-to-vehicle time calculating means for calculating the ratio between the vehicle-to-vehicle distance detection value and the own vehicle speed detection value, that is, a vehicle-to-vehicle time, Means and estimated time to inter-vehicle time change rate (calculated by means similar to claim 1)
A vehicle-to-vehicle time prediction value calculating means for calculating a vehicle-to-vehicle time prediction value obtained by subtracting a value obtained by multiplying the vehicle-to-vehicle time calculation value from the vehicle-to-vehicle time calculation value; , And is controlled on the basis of time instead of the distance in claim 1 .
Further, the invention according to claim 4 has deceleration determining means for detecting deceleration during deceleration as predicted time estimating means,
If the deceleration determining means determines that the vehicle is suddenly decelerated, the spare time storage means does not store the spare time for the deceleration. According to a fifth aspect of the present invention, the deceleration start detecting means is configured to detect that the accelerator pedal has been released from the depressed state, as a deceleration start state. Also,
According to a sixth aspect of the present invention, the deceleration start detecting means is configured to detect that the brake pedal is depressed with the deceleration start state.

[0009]

Generally, when the driver controls the following distance and follows the preceding vehicle, the driver not only determines the current value of the following distance according to the running vehicle speed but also changes the following distance (the relative vehicle speed). ) To predict the distance between vehicles after a certain time,
It is known that inter-vehicle distance control is performed based on the predicted value (for example, see “Research on inter-vehicle distance control of driver”, Transactions of the Automotive Engineering Society of 1989, pp. 51-56). Therefore, if an alarm can be generated based on the inter-vehicle distance prediction value, it is possible to generate an alarm that matches the driver's feeling. But,
Actually, in order to obtain this inter-vehicle distance prediction value, it is necessary to determine a prediction time having a large individual difference for each driver, so that it is difficult to perform the calculation. Therefore, in the present invention, the margin time at the start of deceleration when approaching the preceding vehicle
The minimum value of the estimates and the estimated time of the driver, the inter-vehicle distance (or inter-vehicle time) after the predicted time predicted value, if it becomes smaller than the warning distance (or alarm inter-vehicle time), its It is configured to determine that the vehicle has entered the driver's warning area and generate a warning. The above-mentioned estimated time means the above-mentioned time when the driver determines that the vehicle will be in the excessive approach state after a certain time and performs the deceleration operation. That is, when the driver driver has been expected at the time of starting the deceleration operation and expected to be excessively approaching state future
This is the time from when the deceleration operation is started until the vehicle approaches the excessively close state, and has a different value depending on each driver. Although the predicted time in the above-mentioned paper is defined in a general driving state which is not limited to the time of deceleration, in the case of the present invention, since the device warns of excessive approach, as described above, the deceleration operation while approaching the preceding vehicle is performed as described above. Sometimes limited.

Here, how to estimate the value of the predicted time which differs for each driver will be described. FIG. 6 shows the distance R and the relative speed d / dt at the start of deceleration.
FIG. 7 is a characteristic diagram showing a relationship between the distance R and the relative speed d / dt at the time when deceleration is started in a scene where a normal driver approaches a preceding vehicle traveling at a lower speed than the own vehicle. R is measured, and data in a plurality of deceleration scenes are graphed. Here, one x mark indicates data in one approach scene. When a large number of such data are measured for the same driver, the following tendency is found. That is, the relationship between the inter-vehicle distance R at the point at which deceleration starts and the relative speed d / dt R at that time is represented by a straight line having a certain slope K represented by the following (Equation 2) (shown by a broken line in FIG. 6). Than the straight line)
It does not distribute below.

[0011]

(Equation 2)

From the data shown in FIG. 6, the allowance time Tc is expressed by the following equation (3).

[0013]

(Equation 3)

That is, the allowance time Tc is a value obtained by dividing the inter-vehicle distance R by the relative speed d / dt R, and represents a time until the inter-vehicle distance becomes zero when the current traveling speed is maintained. FIG. 7 is a graph in which the margin time of the above equation (3) is graphed. According to FIG. 7, it can be seen that the data of the margin time is distributed only over a certain value regardless of the value of the relative speed d / dtR. It is known that the lowest value of the area where the margin time is distributed differs for each driver and has a value unique to each driver. Consider the meaning of the lowest value of the distribution of the spare time. In other words, the margin time means a physical quantity of how many seconds after which the vehicle collides with the preceding vehicle if the current traveling speed is maintained. The driver estimates the inter-vehicle distance after the predicted time and travels.When considering that the predicted time matches the minimum value of the spare time, the driver starts deceleration when the vehicle is likely to collide after the predicted time. I understand it. Therefore, it is considered that the minimum value of the measured spare time coincides with the predicted time in the inter-vehicle distance prediction of the driver. In addition, although the distribution of the spare time is shown, in the actual driving behavior at the time of approaching, there are many cases in which the deceleration is started with an extra allowance (that is, the driver unconsciously decelerates before feeling the risk of a rear-end collision). . Therefore, the data of the entire spare time has many variations, and the average value and the like cannot be calculated clearly and the physical meaning is difficult to understand, but the minimum value can be defined to some extent. In the present invention, based on the above considerations, at the time of approaching the preceding vehicle, learn the minimum value of the spare time for each driver, and estimate the learned value as the predicted time of the driver, It is configured to generate an alarm based on this. With this configuration, it is possible to generate an appropriate alarm for each individual.

Specifically, the configuration is as follows. That is, in the first aspect, a margin time is calculated by dividing the inter-vehicle distance detection value at the start of deceleration by the relative speed, and the margin time at the start of the deceleration action is stored for each deceleration. Then, the minimum value among the stored spare times during the deceleration action is estimated as the predicted time of the driver. Next, an inter-vehicle distance predicted value is calculated using the predicted time estimated value. This inter-vehicle distance predicted value is a predicted value of the inter-vehicle distance after the predicted time, and is a value obtained by subtracting a value obtained by multiplying the detected relative speed value by the predicted time estimated value from the detected inter-vehicle distance value. Then, an alarm is issued when the above-mentioned inter-vehicle distance prediction value is shorter than the alarm distance. Next, in claim 2, as the warning distance,
The alarm is provided in two stages using a primary alarm distance and a secondary alarm distance shorter than the primary alarm distance.

Next, in claim 3, an inter-vehicle time predicted value is used instead of the inter-vehicle distance predicted value in claim 1, and the actual physical meaning is the same as in claim 1 . Next, in claim 4 , the spare time measured at the time of sudden deceleration is configured not to be stored as spare time data. This is to accurately estimate the predicted time by excluding data in a special state such as a sudden deceleration. Next, claims 5 and 6, relates arrangement of deceleration start detection means, according to claim 5,
The deceleration start state detects that the accelerator pedal has been released from the depressed state, and claim 6 detects that the brake pedal has been depressed as the deceleration start state.

[0017]

Embodiments of the present invention will be described below. FIG.
FIG. 1 is a block diagram of one embodiment of the present invention. In FIG. 2, reference numeral 21 denotes a radar device for detecting an inter-vehicle distance R from a preceding vehicle, and reference numeral 23 denotes a vehicle speed sensor for detecting the own vehicle speed Va.
29 is a brake sensor for detecting the start of deceleration, 31 is a deceleration G sensor for detecting the degree of deceleration during deceleration, and 33 is a road surface for detecting a coefficient of friction of a running road surface. μ sensor. An information processing circuit 25 includes a radar device 21, a vehicle speed sensor 23,
It receives the outputs from the brake sensor 29, the deceleration G sensor 31, and the road surface μ sensor 33 to determine the situation, and generates an alarm signal in the case of excessive approach. Reference numeral 27 denotes an alarm generating device which receives the alarm signal and generates an alarm. The radar device 21 uses a laser beam or a radio wave as a signal for transmission and reception, and the information processing circuit 25 can be constituted by, for example, a microcomputer. Further, as the alarm generation device 27, a device that issues an alarm such as sound (buzzer, voice, or the like), light (alarm lamp, or the like), vibration (device for vibrating a seat, or the like) can be used. As the brake sensor 29, for example, a brake switch that is turned on when a brake pedal is depressed can be used.
As the deceleration G sensor 31, for example, a semiconductor acceleration sensor can be used. The road surface μ sensor 33 includes, for example, a combination of a water drop sensor and a thermometer attached to the back surface of a fender or the like. By determining whether the road surface is dry or wet and determining the temperature in combination, It is possible to use a device that distinguishes between “dry road surface (friction coefficient: large)”, “rainy road surface (friction coefficient: medium)”, and “snow road surface (friction coefficient: small)”.

Next, the operation will be described. The radar device 21 detects an inter-vehicle distance R to a preceding vehicle, and generates a vehicle speed sensor 2.
3, the vehicle speed Va is detected. The information processing circuit 25 calculates the relative speed Vr between the preceding vehicle and the host vehicle based on these signals (Vr = d / dtR), and decelerates the vehicle based on the brake-on signal from the brake sensor 29. The start timing is detected, and the margin time Tc at that time is calculated and stored. The margin time Tc is a value obtained by dividing the inter-vehicle distance R by the relative speed Vr. At this time, the road surface condition is determined based on the road surface μ output from the road surface μ sensor 33, and the spare time Tc is stored for each road surface condition. The road surface condition is, for example, “dry road surface (coefficient of friction: large)” in fine weather, “rainy road surface (coefficient of friction: medium)” in rainy weather.
And “snow road surface (coefficient of friction: small) during snowfall. By doing so, for example, when traveling on a snowy road,
Predicted time τp estimated from the value of the spare time Tc on a sunny day
Thus, it is possible to prevent an error such as generating an alarm, and to cope with a change in characteristics due to a change in road surface conditions.
Further, rapid deceleration is detected based on the deceleration G signal from the deceleration G sensor 31, and the margin time Tc during rapid deceleration is not stored. This is to prevent the alarm from deviating from the normal range by learning an unusual margin time in which sudden deceleration occurs. Further, the estimated time τp of the driver is estimated from the stored value of the spare time Tc according to the road surface condition, and based on the value, a state of excessive approach to the preceding vehicle is determined. An alarm signal is output when the predicted distance value (described later in detail) is shorter than the alarm distance. In response to this alarm signal, the alarm generator 2
At 7, an alarm is generated. As a method of generating the alarm, for example, visual presentation using an alarm lamp or the like, audible presentation such as generation of an alarm sound, or tactile presentation such as vibration of a seat can be performed. As the above-mentioned warning distance, a value that changes according to the own vehicle speed or the relative speed can be used as shown in the above-described (Equation 1).

Next, FIG. 3 to FIG. 5 are flowcharts showing arithmetic processing in the information processing circuit 25. 3 to 5 indicate that parts having the same reference numerals are connected. Hereinafter, the operation will be described in detail with reference to FIGS. First, in step 41, the vehicle speed Va from the vehicle speed sensor 23 and the inter-vehicle distance R from the radar device 21 are read. Next, in step 43, the relative speed d / dt R between the host vehicle and the preceding vehicle is determined by calculating the rate of change of the inter-vehicle distance R. As a method for obtaining the relative speed d / dt R, a least square method or the like can be considered. Next, in step 45, it is determined whether or not the deceleration operation has been started based on the brake-on signal from the brake sensor 29. In this case, the vehicle is approaching the preceding vehicle (if the decrease in the inter-vehicle distance R is the minus direction of the relative speed, d / dt R <0 is approaching).
If a brake-on signal is input, it is determined that a deceleration operation has started. Here, if it is determined that the deceleration operation has started, the routine proceeds to step 71 and thereafter to learn the margin time Tc in the current deceleration operation. If it is not determined that the deceleration operation has started, the process proceeds directly to step 46.

As shown in FIG. 5, in the portion for learning the margin time after step 71, first, in step 71, the margin time Tc at the start of deceleration is calculated from the above equation (3).
Next, in step 73, it is determined whether or not an alarm has been issued at the start of deceleration. This is because when the driver starts deceleration in response to the alarm, the spare time Tc at that time is used.
Is not necessarily a value determined by the characteristics of the driver, and is not a value representative of the predicted time. Therefore, if an alarm has occurred, the process returns to step 46 without performing the current learning. If no alarm has been generated, the routine proceeds to step 75. In step 75, the value of the road surface μ is read from the road surface μ sensor 33, and in step 77, the current road surface condition is determined from the read value of the road surface μ. This judgment is (1)
Dry road surface, (2) rainy weather, and (3) snowy road are discriminated in about three stages, and the time to start deceleration in each situation is learned. Next, in step 79, it is determined based on the deceleration G signal Xg from the deceleration G sensor 31 whether or not rapid deceleration is performed. Specifically, deceleration G during deceleration action
The maximum value max (Xg) of (Xg) is compared with a predetermined value Xg0 as shown in the following equation (4). max (Xg) ≦ Xg0 (Equation 4) Since the above-described predetermined value Xg0 is a threshold value for determining sudden deceleration, it is necessary to set the predetermined value Xg0 for each of the above road conditions (1) to (3). is there. If the speed is larger than the predetermined value Xg0, rapid deceleration is not performed because the speed is decelerated. If the speed is lower than Xg0, the process is regarded as a normal deceleration operation, and the routine proceeds to step 81. I do. With the above processing, the learning processing of the margin time Tc in FIG. 5 is completed, and the process returns to FIG.

If it is determined in step 45 that the deceleration operation has not been started, the road surface μ is read in step 46, and the process proceeds to step 47, where the estimated time Tp in the current road surface condition is estimated. The estimation of the prediction time Tp is
As shown in the following equation (5), the minimum value min (Tc) of the spare time Tc learned and stored so far is set as the predicted time Tp in the same road surface condition as the present. Tp = min (Tc) (Equation 5) The reason for using the minimum value of the margin time Tc as the prediction time Tp as described above is as follows. That is, at the time of normal deceleration, the driver may take a large margin for stopping safely, but rarely decelerates at the last minute.
Therefore, when the average value or the mode value of the allowance time Tc at the time of the normal deceleration is taken, the value is largely biased toward the safe side. In addition, even if the minimum value of the margin time Tc is set as the prediction time Tp, the margin time Tc at the time of deceleration that is not a normal deceleration operation such as a sudden deceleration is excluded from the beginning in the above-mentioned step 73, so that a safe time is secured. There is no departure from the situation. Further, since the spare time Tc is learned according to the road surface condition and the predicted time Tp is estimated, it is possible to appropriately generate an alarm even if the road surface condition changes. Next, at step 49,
An inter-vehicle distance predicted value Rp after the predicted time Tp is calculated. This is obtained by subtracting the value of the product of the predicted time Tp and the relative speed d / dtR from the inter-vehicle distance R at that time, and is expressed by the following (Formula 6).

[0022]

(Equation 6)

In this embodiment, since the time when the inter-vehicle distance R decreases is set to the negative direction of the relative speed, d / dt R
-Tp becomes a negative value. Therefore, equation (6) is an equation in which d / dt R · Tp is added to the inter-vehicle distance R.

Next, at step 51, it is determined whether or not the inter-vehicle distance prediction value Rp at that time is in an excessively close state. Specifically, as shown in the following equation (7), Rp is K ₁ · Va
It is determined that the vehicle is in the excessive approach state in the following cases. K ₁ · Va ≧ Rp (Equation 7) Here, K ₁ is a constant for the primary warning, and the product of the constant K ₁ and the vehicle speed Va indicates the primary warning distance. In addition, 1
As the next warning distance, the warning distance Rs expressed by the above equation (1) may be used. If the above equation (Equation 7) holds, it means that the inter-vehicle distance predicted value Rp is equal to or less than the primary warning distance, and the primary warning or the second
Generate the next alarm. If the equation (7) does not hold, the process returns to the step 41. Next, in step 53, the secondary warning distance R ₀ (distance shorter than the primary warning distance) is compared with the inter-vehicle distance prediction value Rp, and when the inter-vehicle distance prediction value Rp is equal to or less than the secondary warning distance R _0. Proceeds to step 63 to generate a secondary alarm. If the inter-vehicle distance predicted value Rp is larger than the secondary warning distance R ₀ , a primary warning is issued in step 55 and subsequent steps. In step 55, by subtracting the alarm time TF ₁ from the current time Tn, it is determined whether a predetermined alarm time Delta] t has passed, if it is within the warning time Delta] t, in step 57 the primary alarm for the An alarm sound is generated, and in step 59, a command value is output to the alarm generator 27 so as to turn on the alarm lamp for the primary alarm. Alarm time Δ
If t is exceeded, the alarm sound for the primary alarm is stopped in step 61, and only the alarm lamp is turned on. Steps 63 to 69 are processing of an alarm sound and an alarm lamp related to the secondary alarm, and the contents are the same as those of the above-described steps 55 to 61 of the primary alarm. After the above-mentioned alarm is generated, the process returns to step 41 and the process is repeated.

Next, a second embodiment of the present invention will be described. In the first embodiment, the distance has been used as the reference for the warning, and the predicted distance Rp and the secondary warning distance R ₀ have been used. Even if the inter-vehicle time Th divided by the own vehicle speed Va is used,
Similar effects can be obtained. Originally, the inter-vehicle time Th is used instead of the inter-vehicle distance R in order to generate an alarm without affecting the own vehicle speed Va. Inter-vehicle time Th
The relationship between the distance R and the following distance R is as shown in the following equation (8). Th = R / Va (Equation 8) As described above, instead of the distance, the inter-vehicle time Th is used as a reference.
Is used, the time change rate d / dt Th of the inter-vehicle time Th
And calculating the inter-vehicle time change rate d / dt Th
Subtracting a value d / dt Th · Tp obtained by multiplying the estimated time Tp (calculated in the same manner as in the first embodiment) from the inter-vehicle time Th, and calculating the inter-vehicle time predicted value. A step of determining that a warning is issued when the predicted value is shorter than the warning inter-vehicle time may be provided. Note that the predicted inter-vehicle time is expressed by the following equation (9). Inter-vehicle time prediction value = Th + d / dt Th · Tp (Equation 9) In the above equation (9), as in the above (Equation 6), d / dt Th · Tp is a negative value. Therefore, d /
dt Th · Tp is added. The above-mentioned warning inter-vehicle time may be a predetermined value, but, like the first embodiment, the first alarm inter-vehicle time and the second alarm inter-vehicle time (first alarm inter-vehicle time> second alarm (Inter-vehicle time), and a primary alarm and a secondary alarm may be generated by the respective comparisons. In the above-described embodiments, the brake-on signal from the brake sensor 29 is used to determine the start of the deceleration operation. However, the accelerator sensor is used instead to detect that the accelerator is released from the depressed state. Is also good. In this case, the deceleration start operation can be detected at an earlier timing.

[0026]

As described above, according to the present invention, the margin time at the start of deceleration when approaching the preceding vehicle
The minimum value of, when the prediction time and the estimated driver, the inter-vehicle distance (or inter-vehicle time) after the predicted time predicted value, which is smaller than the warning distance (Alarm inter-vehicle time), the driver Is configured to generate an alarm when it is determined that the vehicle has entered the alarm region, an appropriate alarm can be generated in an area suitable for each driver's personality. For this reason, it is possible to solve the problem that an alarm is generated from too far away, or that alertness is reduced in a situation where an alarm is required due to the alarm being generated too frequently. The effect is obtained that it is possible to appropriately call attention to the driver's excessive approach which is the original purpose of the warning.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a block diagram of a preceding vehicle approach warning device showing one embodiment of the present invention.

FIG. 3 is a part of a flowchart showing a calculation process in the embodiment of FIG. 2;

FIG. 4 is another part of the flowchart showing the calculation processing in the embodiment of FIG. 2;

FIG. 5 is another part of the flowchart showing the calculation processing in the embodiment of FIG. 2;

FIG. 6 shows a distance R and a relative speed d / dt at the start of deceleration.
FIG. 4 is a characteristic diagram showing a relationship with R.

FIG. 7 is a graph showing a margin time.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inter-vehicle distance detecting means 19 ... Predicted time estimating means 3 ... Own vehicle speed detecting means 21 ... Radar device 5 ... Relative speed detecting means 23 ... Vehicle speed sensor 7 ... Inter-vehicle distance predicted value calculating means 25 ... Information processing circuit 9 ... Warning judging means 27 alarm generating device 11 alarm generating means 29 brake sensor 13 deceleration start detecting means 31 deceleration G
Sensor 15: deceleration start margin time calculating means 33: road surface μ
Sensor 17: spare time storage means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01S 13/00-13/95

Claims (6)

(57) [Claims] An inter-vehicle distance detecting means for detecting an inter-vehicle distance between the host vehicle and a preceding vehicle; a relative speed detecting means for detecting a relative speed between the own vehicle and the preceding vehicle; A deceleration start detecting means for detecting that the vehicle has started, and a deceleration start time for calculating a margin time obtained by dividing the inter-vehicle distance detection value at that time by the relative speed in response to an output of the deceleration start of the deceleration start detection means. Calculating means, extra time storage means for storing the extra time at the start of deceleration action for each deceleration, extra time for each deceleration action stored in extra time storage means
Vehicle to calculate a prediction time estimating means for estimating a prediction time the minimum value, the inter-vehicle distance estimated value obtained by a value obtained by multiplying between when the prediction to the relative velocity detection value by subtracting from the inter-vehicle distance detection value of the Distance predicting value calculating means, warning determining means for determining that a warning is issued when the inter-vehicle distance predicting value is shorter than the warning distance, and warning generating means for issuing a warning to a driver according to the determination of the warning determining means. A preceding vehicle approach warning device, characterized in that: 2. The vehicle according to claim 1, further comprising: own vehicle speed detecting means for detecting a traveling speed of the own vehicle;
1 calculated according to a traveling variable including at least the own vehicle speed
A secondary warning distance shorter than the primary warning distance, and comparing the inter-vehicle distance predicted value with the two warning distances. If the inter-vehicle distance predicted value is less than or equal to the primary warning distance, 2
If the distance is larger than the secondary alarm distance, it is determined that the primary alarm is issued, and 2
The preceding vehicle approach warning device according to claim 1, characterized in that it is configured to determine that a secondary warning is issued when the distance is less than the next warning distance. 3. An inter-vehicle distance detecting means for detecting an inter-vehicle distance between the own vehicle and a preceding vehicle; an own vehicle speed detecting means for detecting a running speed of the own vehicle; and a relative speed between the own vehicle and the preceding vehicle. Relative speed detecting means for detecting the vehicle speed, a ratio between the detected distance between the vehicles and the detected speed of the own vehicle, that is, a vehicle-to-vehicle time calculating means for calculating the vehicle-to-vehicle time, Calculation means; deceleration start detection means for detecting that the driver has started deceleration; and a margin obtained by receiving the output of deceleration start from the deceleration start detection means and dividing the inter-vehicle distance detection value at that time by the relative speed. A deceleration start margin time calculating means for calculating time, a margin time storage means for storing the margin time at the start of deceleration action for each deceleration, and a margin time for each deceleration action stored in the margin time storage means
Prediction time estimating means for estimating the minimum value among the prediction times, and an inter-vehicle time for calculating an inter-vehicle time prediction value obtained by subtracting a value obtained by multiplying the inter-vehicle time change rate by the prediction time from the inter-vehicle time calculation value. Predictive value calculating means, warning determining means for determining that a warning is issued when the inter-vehicle time predicted value is shorter than the warning inter-vehicle time, and warning generating means for issuing a warning to a driver according to the determination of the warning determining means. A preceding vehicle approach warning device, characterized in that: 4. The predicted time estimating means includes deceleration determining means for detecting deceleration during deceleration, and when the deceleration determining means determines that the vehicle is suddenly decelerated, the spare time storage means is provided. The preceding vehicle approach warning device according to any one of claims 1 to 3 , wherein the spare time in deceleration is not stored in the vehicle. Wherein said deceleration start detecting means, the deceleration start state, which is constituted so as to detect that it has been released from the accelerator pedal depression state, claims 1 to 4, characterized in that A preceding vehicle approach warning device according to any one of the above. Wherein said deceleration start detecting means, the deceleration start state, which is constituted so as to detect that the brake pedal is depressed, any one of claims 1 to 4, characterized in that 2. A preceding vehicle approach warning device according to claim 1.