JP2596112B2 - Anti-collision warning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial application field >> The present invention measures a distance between an own vehicle and a forward object,
The present invention relates to an improvement in a collision prevention alarm device that issues an alarm when the distance is shorter than the safe inter-vehicle distance.

<< Conventional Technology >> As a conventional collision prevention alarm device, for example, Japanese Unexamined Patent Publication No.
The thing described in No. 30500 is known, a laser beam is sent in front of the vehicle, the distance to the object is detected from the time when the reflected light reciprocates, and the distance between the own vehicle and the detected object is greater than the safe inter-vehicle distance. When it is short, an alarm is issued to prevent collision.

By the way, on a curved road, as shown in FIG. 5, a plurality of reflectors are arranged. The reflector has a higher reflectivity to light than surrounding guardrails or trees. Therefore, in this type of apparatus utilizing laser light, the detected objects are mostly those of the vehicle reflector and the roadside reflector. For this reason, when traveling on a curved road, it is necessary to determine that the roadside reflector is an obstacle and not to issue an alarm.

Therefore, the apparatus described in JP-A-62-130500 has the following configuration.

That is, in the state of FIG. 5A, it is assumed that the radar vehicle has detected the reflector (a).

In this case, the vehicle continues to travel, and FIG. 5 (b)
In this state, if the detection area of the radar is S, the detection target of the radar vehicle 10 changes from the reflector (a) to the reflector (b). In this state, the distance to the reflector (a) is R ₂ , and the distance to the reflector (b) is R ₁ .

FIG. 6 shows the results of the detection distance of the reflector over time. When the reflector to be detected changes from (A) to (B) as described above, the detection distance becomes R _2.
It has been changed to R ₁ from.

By the way, in this case, the difference L ₀ between R ₁ and R ₂ is substantially the installation interval of the reflector. As shown in FIG. 5, the reflectors are arranged at regular intervals at regular intervals.

Therefore, when the distance information of a certain distance difference (for example, L ₀ which is the difference between R ₁ and R ₂ ) is periodically detected while detecting the obstacle ahead (see FIG. 6), the detection target object is detected. Can be identified as a reflector.

Therefore, in this example, a constant reference value Rth corresponding to the reflector interval is provided, and when a new detection object satisfying | R ₁ −R ₂ |> Rth is detected, the detection object stops on the road instead of the reflector. It is configured to determine that the vehicle or dangerous obstacle and issue an alarm.

<< Problems to be Solved by the Invention >> However, in the conventional device as described above, a predetermined reference value Rth based on the reflector interval is set in advance, and this Rth is used as a criterion for determining the presence or absence of an obstacle. When traveling on a curved road where the reflector installation interval exceeds Rth, there is a problem that a false alarm is issued every time a reflector is detected.

For example, this is the case where, when Rth = 30 m, the reflector spacing is actually the legal maximum spacing of 50 m (see Traffic Engineering Handbook (1984), p. 758).

On the other hand, in order to avoid this problem, it is conceivable to set the value of the reference value Rth to the legal maximum interval of 50 m, but in this case it is said that no alarm is issued for a stationary object whose distance change is within 50 m. There is a problem.

Further, the reference value Rth is made smaller than 30 m, for example, Rth
= 5 m, but in this case, if the reflector interval is 5 m or more, there is a problem that a false alarm is issued to all the reflectors.

<< Object of the Invention >> In view of the above problems, the present invention accurately detects only an obstacle in front of a true vehicle irrespective of a reflector interval,
An object of the present invention is to provide a collision prevention alarm device capable of issuing an alarm for collision prevention.

<< Means for Solving the Problems >> In order to achieve the above object, the present invention is configured as shown in the claim correspondence diagram of FIG. 1, and detects a distance from a host vehicle to a detection object at predetermined time intervals. 1) and a safe inter-vehicle distance calculating means b for calculating a safe inter-vehicle distance while the vehicle is running, wherein the distance to the detected object detected by the first distance detecting means a is the safety In a collision prevention alarm device that issues an alarm when the vehicle distance becomes less than the inter-vehicle distance, a first determination unit c that determines whether a detected object in front of the vehicle is a stationary object, and the detected object is a stationary object by the first determination unit c. Is determined, the minimum distance information storage means d for storing the minimum distance to the detection object, and the detection object is determined as a stationary object by the first determination means c, and the minimum distance information storage means d When the minimum distance to the known object is stored, a second determination unit e that determines whether or not distance information having a distance difference greater than or equal to a predetermined value from the minimum distance is detected; and the second determination unit e. When it is determined that distance information having a distance difference of a predetermined value or more from the minimum distance is detected, a reflector detecting means f for detecting the detected object as a roadside reflector, and a reflector is detected by the reflector detecting means f In this case, the alarm output stopping means g for stopping the alarm output for a certain period of time, the second distance detecting means h for detecting the distance to the detected object even while the alarm output is stopped, and the second distance detecting means h When the distance to the detected object is smaller than the minimum distance stored in the minimum distance information storage means d, an alarm output stop release means i for releasing the stop of the alarm output; Characterized in that it has.

<< Description of Embodiments >> Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing a basic configuration of the present embodiment.

In FIG. 1, a laser beam generated by a laser driving circuit 1 is transmitted to the front of a vehicle by a light transmitting element 2 provided at a front portion of the vehicle.

On the other hand, the reflected light from the detection object is received by the light receiving element 3 also provided in the front part of the vehicle, and is detected by the distance detection circuit 4 based on the time Δt from the transmission of the laser light to the reception of the laser light. Is obtained by the following equation.

L = C · Δt / 2 (where C = 3.0 × 10 ⁸ m / s) In the alarm output determination circuit 5 composed mainly of a microcomputer, the alarm output determination circuit 5 Based on the distance information and the vehicle speed information detected from the vehicle speed sensor 6, it is configured to determine whether or not to issue an alarm for preventing collision.

The above is the basic configuration of the device of the present embodiment. Hereinafter, when a vehicle equipped with the device of the present embodiment is traveling on a curved road as shown in FIG. 5, the reflector installed on the road side is erroneously regarded as an obstacle. A processing procedure in a case where the vehicle travels while detecting only an obstacle in front of a true vehicle without detection will be described with reference to a flowchart of FIG.

By the way, the feature of this embodiment is that, when a reflector is detected ahead, a reflector flag is set once, and in principle, an alarm is not issued for a certain period of time (5 seconds in this example). When the preceding vehicle approaches due to sudden deceleration or the like, the warning stop is released and a warning is issued.

That is, when the program is started, first, detects the distance to a detected object by the distance detection circuit 4 calculates a relative speed V _R between the vehicle and the detected object by differentiating the value of time (step 100 ).

Then, the vehicle speed V is detected based on the output from the vehicle speed sensor 6 (step 102).

Thus, the relative speed between a detected object V _R and vehicle speed V
Is detected, it is next checked from these detection results whether or not the detected object is a stationary object (step 104). This is because, when the detected object is a stationary object, while is equal to the relative speed V _R and the vehicle speed V, if the detected object is not a stationary object a like case of the preceding vehicle, is better than the relative velocity V _R of the vehicle speed V becomes larger, is determined by comparing the relative speed V _R and the vehicle speed V.

Thus, if the detected object is not a stationary object (step 10
(NO in 4), and then calculates a safe inter-vehicle distance Rs between the vehicle and the detected object (step 106).

Here, the safe inter-vehicle distance Rs refers to a limit distance at which a collision can be avoided when the front vehicle decelerates at a deceleration greater than or equal to the deceleration α of the front vehicle even if the front vehicle suddenly brakes.

The safety inter-vehicle distance Rs is, for example, the vehicle speed V, and the reaction delay time from when the warning is recognized to when the brake is depressed.
td, the deceleration of the preceding vehicle alpha, when the relative speed is V _R, can be shown by the following equation.

_{Rs = V · td + V R} (2V-V R) / 2α Next, In step 108, the distance to the detected object Ri
Is detected by the distance detection circuit 4.

Thus, the safe inter-vehicle distance Rs and the distance to the detected object
When Ri is detected, it is then determined whether or not an alarm for collision prevention should be issued based on the detection results, that is, whether or not Rs ≧ Ri. If an alarm should be issued (YES in step 110), an alarm is output (step 112).

Meanwhile, if the detected object by the judgment of step 104 is determined to a stationary object, i.e. the relative speed V _R and the vehicle speed V
Is substantially equal (YES in step 104), the reflector that is a stationary object is not erroneously detected as an obstacle.
The following processing will be performed.

That is, first, in the processing of step 114, the minimum distance information _R0 to the stationary object is stored. This will now be described with reference to FIG. 4. Assuming that a stationary object is detected ahead of the vehicle to obtain polygonal distance information such as a solid line R, the minimum distance _R0 to the stationary object is set to the minimum distance. The information is detected and stored (step 114).

Then, in the subsequent step 116, it is checked whether or not distance information having a distance difference of 5 m or more is detected within the distance measurement time interval. This is because the minimum installation interval of the reflector is 5 m, so that if the detection object is a reflector, it should be detected that there is a distance difference of 5 m or more. And
In FIG. 4, L ₀ corresponds to the distance difference.

If distance information having a distance difference of 5 m or more is detected (YES in step 116), it can be determined that the detected object may be a reflector. ) Turn on the reflector flag (step 118). The output of the alarm is forcibly stopped while the reflector flag is ON.

On the other hand, if no distance information having a distance difference of 5 m or more is detected in step 116 (NO in step 116), it is determined that the detected object is not at least a reflector. In that case, an alarm output will be issued.

By the way, when the reflector flag is turned on by the processing of step 118, no alarm is issued in principle for five seconds thereafter. That is, referring again to FIG.
When the reflector flag is turned on at time tc after 5 seconds
Until then, no alarm is issued in principle.

However, there are cases where the preceding vehicle suddenly decelerates during that time. And in this case, the reflector flag is ON
It is necessary to issue a warning to prevent collisions even during the operation.

Therefore, in this embodiment, the distance information of the detected object ahead is sequentially input to the alarm output determination circuit 5 even while the reflector flag is ON. Then, in the processing of the subsequent step 120, it is checked whether or not distance information to the detected object smaller than the minimum distance information _{R0 is} detected while the reflector flag is ON (step 12).
0).

This is because the detection object is the minimum distance information R ₀ is smaller than the distance information if the reflector should be detected, the car or the like suddenly decelerated by checking if R ₀ is smaller than the distance information is detected It is checking whether there is.

If the distance information smaller than _R0 is detected, the reflector flag is turned off (step 122).

Then, the process proceeds to step 106 and subsequent steps.

That is, in FIG. 4, the minimum distance information R ₀ at tb.
When smaller distance information Rb is detected, the reflector flag is turned off at the same time.

Thus, in this embodiment, the reflector flag is
After being turned on, detection of distance data is continued, and detection of obstacles is continued.

On the other hand, when distance information smaller than R ₀ is not detected while the reflector flag is ON (N in step 120).
O) It is checked whether or not 5 seconds have elapsed since the reflector flag was turned on (step 124). If 5 seconds have elapsed (YES in step 124), the reflector flag is turned off (step 126). ). That is, in FIG. 4, the minimum distance information R ₀ while smaller distance information Rb is not detected, when five seconds from the time ta, so that tc at reflector flag is OFF.

As described above, the apparatus according to the present embodiment, when it is determined that the detected object when traveling on a curved road is a reflector, basically stops the generation of the alarm output for a certain period of time, and also outputs the distance information during the stop of the alarm output. Collection continues. And in the meantime,
When the detection object other than the reflector is detected, the stop of the alarm output is released thereafter, so that the alarm for the preceding vehicle or the like can be accurately output even during the stop period of the alarm output.

<< Effects of the Invention >> As described above, when a reflector is detected while traveling on a curved road, the collision prevention alarm device according to the present invention stops the alarm output for a certain period of time and continues to detect the distance to the detected object during this period. However, if the distance to the detected object detected during this time is smaller than the minimum distance to the reflector,
Since the stop of the warning output is released, there is an effect that regardless of the reflector interval, only a true obstacle in front of the vehicle can be accurately detected and a warning can be issued.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a block diagram showing a basic configuration of the present invention, FIG. 3 is a flowchart showing a processing procedure of the present invention, and FIG. 4 is a distance to a detection object and a reflector flag. 5 is an explanatory diagram when the detection target reflector moves while traveling on a curved road, and FIG. 6 is a detection distance explanation diagram when the detection target reflector moves in FIG. DESCRIPTION OF SYMBOLS 1 ... Laser drive circuit 2 ... Light transmitting element 3 ... Light receiving element 4 ... Distance detection circuit 5 ... Alarm output judgment circuit 6 ... Vehicle speed sensor

Claims (1)

(57) [Claims] A first distance detecting means for detecting a distance from a host vehicle to a detection object at predetermined time intervals; and a safe inter-vehicle distance calculating means for calculating a safe inter-vehicle distance while the vehicle is running. A collision prevention alarm device for issuing an alarm when a distance to a detected object detected by a first distance detecting means is equal to or less than the safe inter-vehicle distance, wherein a first object for determining whether or not the detected object in front of the vehicle is a stationary object. Determining means; a minimum distance information storage means for storing a minimum distance to the detected object when the detected object is determined to be a stationary object by the first determining means; When the minimum distance to the detected object is stored by the minimum distance information storage means, it is determined whether or not distance information having a distance difference greater than or equal to a predetermined value from the minimum distance is detected. Reflector means for detecting a detection object as a roadside reflector when it is determined that the distance information having a distance difference of a predetermined value or more from the minimum distance is detected by the second determination means; An alarm output stop means for stopping an alarm output for a predetermined time when the reflector is detected by the reflector detection means; a second distance detection means for detecting a distance to a detection object even while the alarm output is stopped; When the distance to the detected object detected by the distance detecting means is smaller than the minimum distance stored in the minimum distance information storage means, the alarm output stop releasing means for releasing the stop of the alarm output is provided. And anti-collision warning device.