JP3135723B2 - Vehicle safety devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving safety device for avoiding contact with an obstacle such as a preceding vehicle existing in front of a host vehicle. The present invention relates to an improvement of a device for detecting a distance or the like.

[0002]

2. Description of the Related Art Conventionally, as a driving safety device for a vehicle of this type, for example, as disclosed in Japanese Patent Application Laid-Open No. 53-16230, a radar device is used to connect a host vehicle to an obstacle ahead. The distance and relative speed are continuously detected, and based on the detection results, it is determined whether or not the vehicle may come into contact with an obstacle in front of the vehicle. It is known to apply a braking force to each wheel or to activate a warning device to issue a warning to a driver.

[0003] In particular, when the information of an obstacle is not output from the radar apparatus, the information of the distance and the relative speed to the obstacle are determined by using the information obtained up to that time. It is disclosed that a current value is estimated and a possibility of contact is determined based on the current value.

[0004]

The above estimation is continuously performed for a certain period of time from the time when the obstacle information is no longer output. However, in setting the estimation time, the following problem occurs. is there. In other words, if the estimation time is set to be long, the estimation error increases with the elapse of the estimation time. The possibility that the automatic braking or the like is erroneously activated increases. On the other hand, for an obstacle located at a position relatively distant from the host vehicle, even if the estimation time is set relatively long, alarms and automatic braking do not malfunction due to estimation errors. In sensing, an obstacle farther away from the host vehicle is more likely to be lost. Therefore, if the estimation time is set short, the effect of the estimation for obstacles farther from the host vehicle is significantly reduced.

[0005] The present invention has been made in view of such a point, and an object of the present invention is to change the estimated time according to the situation such as the distance to the obstacle immediately before the obstacle is lost. Accordingly, an object of the present invention is to provide a traveling safety device for a vehicle that can appropriately perform estimation and prevent malfunctions such as an alarm and automatic braking while ensuring safety.

[0006]

According to a first aspect of the present invention, there is provided a radar apparatus for transmitting a radar wave toward the front of a host vehicle and detecting an obstacle existing in front of the host vehicle. In a driving safety device for a vehicle that determines the possibility of contact between the own vehicle and the obstacle from information on the obstacle detected by the radar device, when the information on the obstacle is not output from the radar device , , The information of the obstacle is output
Only until the specified time has passed since
Contact possibility determining means for estimating at least the current value of the distance between the own vehicle and the obstacle based on the information up to that time to determine the possibility of contact between the own vehicle and the obstacle, and the radar device And an estimated time changing means for changing the predetermined time according to the situation when the information on the obstacle is no longer output from.

[0007] The inventions of claims 2 and 3 are all dependent on the invention of claim 1 and more specifically show the estimated time changing means as one of the components.

That is, in the invention according to claim 2, the estimated time changing means sets the predetermined time as the distance between the obstacle and the host vehicle immediately before the information of the obstacle is no longer output from the radar device becomes longer. It changes the time longer.

In the invention according to claim 3, the estimated time changing means is provided when the distance between the obstacle and the host vehicle immediately before the information on the obstacle is no longer output from the radar device is larger than a predetermined value. The predetermined time is changed to be longer than when it is small, and the predetermined value is a function value having the vehicle speed, the relative speed between the vehicle and an obstacle, and the friction coefficient of a running road surface as parameters.

[0010]

According to the above-mentioned structure, according to the first aspect of the present invention,
When the information on the obstacle is no longer output from the radar device, the contact possibility determining means outputs the information on the obstacle.
Only during the period from when the vehicle disappears until a predetermined time elapses , at least the current value of the distance between the vehicle and the obstacle is estimated based on the information up to that time, and the possibility of contact between the vehicle and the obstacle may be estimated . Judge. Then, when there is a possibility of contact, contact avoidance measures such as an alarm and automatic braking are taken to avoid contact between the host vehicle and the obstacle.

The predetermined time is changed by the estimated time changing means in accordance with the situation when the information on the obstacle is no longer output from the radar device. The change of the predetermined time is, for example, the longer the predetermined time is, the longer the distance between the obstacle and the host vehicle immediately before the information of the obstacle is no longer output from the radar device. If the obstacle is relatively far away from your vehicle,
By continuing the guessing for a relatively long time, the effect of the guessing can be enhanced.For obstacles that are relatively close to the host vehicle, the guessing can be continued for a relatively short time so that an alarm or automatic braking caused by a guess error can be made. And so on can be prevented.

[0012]

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

FIG. 1 shows a block configuration of a vehicle safety device according to an embodiment of the present invention. In this figure, 1
Is a radar head unit provided at the front of the vehicle body. The radar head unit 1 transmits a pulse laser beam as a radar wave from a transmitting unit toward the front of the own vehicle, and a preceding vehicle or the like existing in front of the vehicle. The receiving unit receives the reflected wave reflected on the obstacle. The radar head unit 1 is of a scanning type that scans a pulse laser beam transmitted from its transmitter at a relatively wide angle in the horizontal direction. The signal from the radar head unit 1 is input to the arithmetic unit 2 and the arithmetic unit 2
In the above, the distance between each obstacle existing in the scanning range and the own vehicle, the direction of the obstacle with respect to the own vehicle, and the like are calculated based on the delay time from the transmission time of the laser reception light. The radar head unit 1 and the arithmetic unit 2 constitute a scan-type radar device 3 that detects an obstacle existing in front of the host vehicle.

Reference numeral 4 denotes a steering angle sensor for detecting a steering angle of a steering wheel (hereinafter, simply referred to as a steering angle). Reference numeral 5 denotes a vehicle speed sensor for detecting a vehicle speed of the own vehicle (own vehicle speed). , 5 are input to the traveling route predicting means 6. The traveling path predicting means 6 predicts the traveling path of the host vehicle based on the steering angle θH and the vehicle speed vo, and specifically calculates the radius of curvature R of the traveling path. In addition, the traveling route prediction means 6 also calculates the sideslip angle β of the vehicle. The curvature radius R and the sideslip angle β are:
It is calculated by the following equation (1).

[0015]

(Equation 1)

Further, among obstacles detected by the radar device 3, reference numeral 11 denotes an obstacle existing in an area along the traveling path predicted by the traveling path predicting means 6 and closest to the own vehicle. The information of the closest obstacle identified by the identification means 11 is input to the contact possibility determination means 12, and the determination means 12 identifies the vehicle with the own vehicle. The possibility of contact with the obstacle is determined. When there is a possibility of contact, the actuator 13 of the automatic braking device operates to apply a braking force to each wheel based on the control signal output from the determination means 12, and an alarm is issued prior to the braking. The device 14 is activated to alert the driver.

In addition, reference numeral 21 denotes a storage unit for storing obstacle information output from the radar device 3 (the operation unit 2) for a predetermined period, and reference numeral 22 denotes estimating means for receiving the obstacle information from the radar device 3. Thus, the estimating means 22 includes the radar device 3
Is to estimate the current value of the distance between the host vehicle and the obstacle based on the information on the obstacle stored in the storage unit 21 when the information on the obstacle is no longer output from the storage unit 21 It is. The contact possibility determining means 12, when the closest obstacle becomes unreachable grasped by the identification means 11 prevents information of the obstacle from the radar device 3 is outputted, the
Predetermined time has passed since obstacle information is no longer output
Only until that time, the possibility of contact between the host vehicle and the obstacle is determined based on the information from the estimating means 22. The estimating means 22 and contact possibility determination
Means 12 outputs obstacle information from radar device 3
Information is no longer output when
Only until the specified time has passed since
At least between the vehicle and the obstacle
Estimate the current value of the distance to allow contact between your vehicle and obstacles
The contact possibility determining means of the present invention for determining the
ing.

The reference numeral 23 designates the above-mentioned condition according to the situation when the information on the obstacle is no longer output from the radar device 3.
Estimated time changing means for changing the predetermined time. The changing means 23 includes the radar device 3, the storage unit 21, the vehicle speed sensor 5, and a road surface μ for detecting a friction coefficient (μ) of a running road surface.
Each signal from the sensor 24 is input.

Next, the identification of the closest obstacle by the identification means 11, the estimation by the estimation means 22, and the change of the predetermined time by the estimation time change means 23 will be described in detail with reference to the flowcharts shown in FIGS. .

In FIGS. 2 and 3, after starting,
First, in step S11, data from the traveling path predicting means 6 (that is, turning radius R and side slip angle β of the traveling path) is obtained, and in step S12, data from the radar device 3 (arithmetic unit 2) is obtained. The data of the radar device 3 is M
And the distance Li between the obstacle and the vehicle (i = 1 to M).
), The horizontal angle φi of the obstacle from the center line of the radar device 3 (which substantially coincides with the center line of the host vehicle) and the no-echo counter Ci. Note that the no-echo counter Ci is required between one obstacle (i = n) in scanning the radar apparatus 3 in one direction and an obstacle (i = n-1) adjacent to the scanning direction leading side. It shows the time when it was done.

Subsequently, at step S13, ln is set to infinity, t
Initial values are set by setting n to 0 and i to 0. Where ln
Means the distance from the obstacle closest to the host vehicle among the obstacles existing on the traveling path.

After the initial value is set, i is counted up by one in step S14, and it is determined in step S15 whether i is equal to or less than M. If the determination is YES, ψo, ψmin, and ψmax are calculated by the following equations in step S16.

Ψo = (Li / 2R) -βψmin = ψo- (W / 2Li) ψmax = ψo + (W / 2Li) Here, as shown in FIG. 4, ψo is the forward movement of the vehicle A and Li ahead. The straight line a2 connecting the center line CL of the road is the included angle formed by the center line a1 of the vehicle A (the center line of the radar device 3). W is the width of the traveling path B, which is set to a value slightly larger than the width of the host vehicle A. ψmin and ψ
max is the center line of the own vehicle A (the radar device 3) connecting each straight line connecting the own vehicle A and the left and right ends of the traveling path B in front of Li.
Is the included angle with respect to the center line a1. However, the sign is positive in the clockwise direction. In FIG. 4, R is the radius of curvature of the traveling path, β is the side slip angle of the vehicle A, and is the included angle between the traveling direction (velocity vector vo) of the vehicle A and the center line a1.

Subsequently, in step S17, the no-echo counter Ci is added to to, and the added value is newly set as to. Thereafter, in step S18, it is determined whether or not the horizontal angle φi of the obstacle is a value between ψmin and ψmax, that is, whether or not the obstacle is on the traveling path B. Subsequently, in step S19, it is determined whether or not the distance Li between the obstacle and the host vehicle is smaller than In. If the determination is YES, the distance Li is set to In in step S20, and to
Are set to tn, respectively. Thereafter, the process returns to step S14. Also, when the determination in step S18 or S19 is NO, the process returns to step S14.

By repeating the above steps S14 to S20, the obstacle closest to the own vehicle on the traveling path B of the own vehicle A is identified from the M obstacles detected by the radar device 3, and The distance between the nearest obstacle and the host vehicle is set to ln.

When all the M pieces of obstacle data have been checked, a value obtained by subtracting tn from to in step S21 is newly set as to (= to-tn). Here, the previous to is the added value of the no-echo counter of all data from the point of detection of the closest obstacle during the previous frame scanning of the radar device 3, and tn is the value of the radar device 3 from the replacement of step S20. This is the time required for scanning the nearest obstacle in one frame scanning. Accordingly, the new to is the time from the point of detection of the nearest obstacle to the point of detection of the last detected obstacle. When this time to is reached, the radar apparatus 3 scans the nearest obstacle for the next one frame. By adding the no-echo counter Ci until an object is detected, the time required to detect the nearest obstacle twice during two-frame scanning is measured. This time is used for calculating a relative speed V between the host vehicle and the nearest obstacle in step S34 described later.

Subsequently, it is determined in step S22 whether or not ln is infinite, that is, whether or not the initial value is set. If the initial value is still set, ln is set to 0 in step S23, and step S31 is performed. Move to. When ln is a finite value, the process directly proceeds to step S31.

In step S31, it is determined whether there is an obstacle (closest obstacle) in the traveling path B, and the determination is YES.
In the case of, the n count is set to 0 in step S32,
After performing various substitutions for calculating the relative speed in step S33, the current distance (ie, current value) l0 between the host vehicle and the nearest obstacle is determined in step S34 by an interpolation method such as the least square method. In addition to the calculation, the relative speed V between the current vehicle and the nearest obstacle is calculated using the distance l0, and then the process returns.

On the other hand, if the determination in step S31 is NO, the n count is incremented by one in step S35, and then the threshold value Lx is set in step S36. The threshold value Lx is a function value using the vehicle speed vo of the own vehicle, the relative speed V between the own vehicle and the nearest obstacle, and the friction coefficient μ of the running road surface as parameters (Lx = f (vo, V,
μ)), as shown in FIGS. 5 (a) to 5 (c), as the vehicle speed v0 or the relative speed V increases, or the friction coefficient μ increases from 1 to 0.
, The threshold value Lx is set to gradually increase.

Subsequently, in step S37, the distance between the obstacle and the host vehicle immediately before the nearest obstacle in the traveling path B disappears (that is, immediately before the information on the obstacle is no longer output from the radar device 3). It is determined whether or not ln is greater than the threshold value Lx. If the determination is YES, step S
At 38, N is set to the N value for setting the predetermined time, and when the determination is NO, the N value is set to N1 at step S39. Here, No> N 1 of the large and small relationship. Therefore, in steps S36 to S39, when the distance ln between the obstacle and the host vehicle immediately before the nearest obstacle disappears is longer than the threshold value Lx, the predetermined time is longer than when the distance In is smaller than the threshold value Lx. The estimated time is changed by the estimated time changing means 23.

After setting the N value, it is determined in step S40 whether or not the n count is equal to or less than the N value.
In the case of S, in step S41, the distance l0 between the current vehicle and the nearest obstacle is calculated by extrapolation using the data up to the previous time. The current value of this distance l 0 is the distance l n between the nearest obstacle just before the closest obstacle disappears.
And the relative velocity V, it is estimated by the following equation.

Lo = ln + V · T where T is the elapsed time from the time when the nearest obstacle disappeared.

The estimation of the distance lo is performed by the estimation means 22.
Done in Return after this guess.

On the other hand, if the determination in step S40 is NO, n count is set to 0 in step S42, and both lj and tj are set to 0 in step S43.
In step S44, the distance lo and the relative speed V between the host vehicle and the nearest obstacle are both set to 0, and then the process returns.

That is, it can be seen from steps S40 to S44.
As a result, information on obstacles is no longer output from the radar device 3.
The obstacle information is no longer output
Only between the passage of the predetermined time,
The possibility of contact is determined.

Next, the operation and effect of the above embodiment will be described. Usually, the identification means 11 selects the M obstacles detected by the radar device 3 on the traveling path B of the vehicle A. The obstacle closest to the own vehicle is identified, and information on the obstacle (the current value of the distance lo and the relative speed V between the own vehicle and the obstacle) is output to the contact possibility determining means 12. The determining means 12 determines the possibility of contact between the host vehicle and the nearest obstacle based on the obstacle information from the identifying means 11, and when there is a possibility of contact, the actuator of the automatic braking device 13 to apply a braking force to each wheel to apply braking, and prior to the braking, an alarm device 1
Activate 4 to alert the driver. As a result, contact between the vehicle and the nearest obstacle on the traveling path can be avoided, and safety can be ensured.

On the other hand, when the information on the obstacle is no longer output from the radar device 3,
1 based on the information obtained before the obstacle information was not output, which is stored in No. 1 while maintaining the current value of the relative speed V between the own vehicle and the obstacle at the previous value, In addition to estimating the current value of the distance l0 from the obstacle , the contact possibility determination means 12 determines that the information on the obstacle is no longer output.
The estimating means 22 is only used until a predetermined time elapses.
, The possibility of contact between the vehicle and the obstacle is determined. And when there is a possibility of contact,
The contact possibility determining means 12 applies an alarm and automatic braking as a contact avoidance measure in the same manner as in the case of the contact possibility determination based on the obstacle information from the identification means 11 described above. Contact can be avoided.

In this case, the predetermined time is changed by the estimated time changing means 23 in accordance with the distance ln between the obstacle and the host vehicle immediately before the output of the information on the obstacle is stopped. when greater than threshold Lx is where
It is longer than when the fixed time is small. For this reason, estimation of obstacles relatively distant from the host vehicle is continued for a relatively long time, and the effect of the estimation can be enhanced. Since the operation is only continued for a relatively short time, it is possible to prevent a malfunction such as an alarm or an automatic braking caused by the estimation error. Further, the threshold value Lx is a function value having parameters of the vehicle speed vo, the relative speed V, and the friction coefficient μ of the traveling road surface, which are factors related to the braking distance of the host vehicle, and the vehicle speed v0 or the relative speed V The higher, or the coefficient of friction μ is 0
The threshold value Lx gradually increases as the braking distance increases, that is, as the braking distance increases, so that the estimation can be performed more appropriately by changing the predetermined time.

It should be noted that the present invention is not limited to the above-described embodiment, but includes various other modifications.
For example, in the above embodiment, it is determined whether the distance ln between the obstacle and the host vehicle immediately before the information on the obstacle is no longer output from the radar device 3 is larger or smaller than a predetermined threshold Lx. Although the predetermined time is changed in two stages, it may be changed in three or more stages or continuously. The point is that the longer the distance ln between the obstacle and the host vehicle immediately before the information on the obstacle is no longer output from the radar device 3, the longer the predetermined time should be changed.

In the above embodiment, the predetermined time is changed according to the distance ln between the obstacle and the host vehicle immediately before the information on the obstacle is no longer output from the radar device 3.
In the present invention, it is needless to say that the predetermined time may be changed according to the congestion state of the road when the information on the obstacle is no longer output from the radar device 3.

[0041]

As described above, according to the vehicle safety device of the present invention, when the information of an obstacle is not output from the radar device, the information of the obstacle is not output.
It is possible to make contact between the host vehicle and the obstacle by estimating at least the current value of the distance between the host vehicle and the obstacle based on the information up to that time only until a predetermined time has elapsed since
By determining the gender and changing the predetermined time according to the situation at that time, the guess can be appropriately performed, and the safety can be improved.

In particular, according to the second aspect of the present invention, the predetermined time is changed longer as the distance between the obstacle and the host vehicle immediately before the information on the obstacle is no longer output from the radar device is longer. In addition, the estimation of an obstacle relatively far from the vehicle can be continued for a relatively long time, the effect of the estimation can be enhanced, and malfunctions such as alarms and automatic braking caused by estimation errors can be prevented.

According to the third aspect of the present invention, the threshold value of the distance to the obstacle for which the predetermined time is changed is determined based on the own vehicle speed and the own vehicle speed which are factors related to the braking distance of the own vehicle. Since it is changed according to the relative speed between the vehicle and the obstacle and the friction coefficient of the traveling road surface, it is possible to make a more appropriate estimation by changing the predetermined time.

[Brief description of the drawings]

FIG. 1 is a block diagram of a vehicle safety device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a method for identifying a nearest obstacle.

FIG. 3 is a flowchart illustrating a method for calculating a distance between a host vehicle and a nearest obstacle;

FIG. 4 is a schematic diagram showing a positional relationship between a host vehicle and a traveling route.

FIG. 5 is a diagram showing a correlation between a threshold value Lx, a vehicle speed vo, a relative speed V, and a friction coefficient μ of a running road surface.

[Explanation of symbols]

3 Radar apparatus 12 Contact possibility judgment means 22 Estimation means (contact possibility judgment means) 23 Estimation time change means

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Ayumu Doi 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Kenichi Okuda 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Inside (72) Inventor Yasunori Yamamoto 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Corporation (72) Inventor Satoshi Morioka 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Corporation (72) Inventor Tomohiko Adachi 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-53-16230 (JP, A) JP-A-4-102200 (JP, A) JP-A-59-182704 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/51 G01S 13/00-13/95 G01S 17/00-17 / 95 G08G 1/16

Claims (3)

(57) [Claims] A radar device for transmitting a radar wave forward of the host vehicle and detecting an obstacle existing in front of the host vehicle;
In a driving safety device for a vehicle that determines the possibility of contact between the own vehicle and the obstacle from information on the obstacle detected by the radar device, when the information on the obstacle is not output from the radar device , Predetermined after information on the obstacle is no longer output
Only until the time elapses , based on the information so far, at least the current value of the distance between the host vehicle and the obstacle
A contact possibility determining means for guessing and determining the possibility of contact between the host vehicle and the obstacle; and changing the predetermined time according to a situation when information on the obstacle is no longer output from the radar device. A traveling safety device for a vehicle, comprising: an estimated time changing unit. 2. The estimated time changing means changes the predetermined time longer as the distance between the obstacle and the host vehicle immediately before output of information on the obstacle from the radar device is stopped. The driving safety device for a vehicle according to claim 1. 3. The estimated time changing means, when the distance between the obstacle and the host vehicle immediately before the information on the obstacle is no longer output from the radar device is larger than a predetermined value, is smaller than the predetermined time than when the distance is smaller. The vehicle safety device according to claim 1, wherein the predetermined value is a function value having parameters of the own vehicle speed, a relative speed between the own vehicle and an obstacle, and a friction coefficient of a running road surface.