JP4824511B2 - Vehicle travel safety device - Google Patents

Description

  The present invention relates to a vehicle travel safety device, and more specifically to an apparatus that detects an obstacle such as another vehicle around the vehicle (own vehicle) and avoids contact with the object.

Detecting an object such as a preceding vehicle in the vehicle traveling direction using a radar is often performed. As an example, the technique described in the following Patent Document 1 previously proposed by the present applicant can be given. In the prior art, a large number of reflected points, which are the sources of reflected waves obtained by radiating beams in a plurality of directions of the vehicle traveling direction and reflected by an object, are detected, and the same number of detected reflected points are detected. The segment is divided into one or a plurality of reflection point groups estimated to belong to the object, and line segments constituting the contour of the object are obtained therefrom. Next, the intersection is regarded as an end point, and the possibility of contact when overtaking an object such as a preceding vehicle is determined from the position of the end point and the width of the host vehicle, and the driver is warned when there is a possibility of contact. Configured as follows.
JP 2000-206241 A

  Thus, in the above-described prior art, the possibility of contact at the time of overtaking is determined from the end points (intersection points) of the line segment constituting the contour of the object and the width of the own vehicle, and a warning is given if there is a possibility of contact And configured to support contact avoidance. In other words, the prior art focuses on avoiding contact when overtaking an object such as a preceding vehicle that is moving in the same direction, but approaching the traveling path of the vehicle (own vehicle) from the side at the front crossroad or T-shaped road. Avoiding contact with an object such as a so-called encounter vehicle is not necessarily the same as that during overtaking.

  When another vehicle enters the vehicle's road from the side, generally the intersection of the front and side line segments of the other vehicle is detected. Depending on the degree of entry into the travel path, noise, or the like, only one line segment can be detected, and the intersection may not be detected. Therefore, in avoiding contact with an object such as an encounter vehicle, there may be a scene where it is necessary to determine whether or not there is contact with an object based on an end point recognized from one line segment instead of an intersection.

  Therefore, the object of the present invention is to solve the above-mentioned problems, and to effectively make contact with an object such as a so-called encounter vehicle that approaches the traveling path of the vehicle (own vehicle) from the side at the front cross road or T-shaped road. An object of the present invention is to provide an object detection device for a vehicle which is avoided.

In order to solve the above object, in the claim 1, wherein the object based transmits the electromagnetic wave in the traveling direction of the vehicle, the reflection points obtained by reflecting the one object present in the advancing direction An object detection means for detecting a line segment, a line segment recognition means for recognizing a line segment constituting an outline of the object based on an array of point groups obtained by projecting the reflection points onto a two-dimensional plane, and the recognized End point extracting means for extracting an end point of the object based on a line segment; and a relative relationship calculating means for calculating a relative relation between the object and the object including a relative speed of the object with respect to the vehicle based on the extracted end point; , A contact possibility estimating means for estimating the possibility of contact of the vehicle with the object based on the calculated relative relationship, and a pre-contact before the contact is estimated when the possibility of the contact is estimated. The vehicle and the object in time In the vehicular travel safety device, the assisting actuating means includes two assisting operation means for actuating the contact avoidance assisting means for assisting the avoidance of contact with the vehicle when the number of the recognized line segments is one. Compared to the case where it is recognized, the contact avoidance support means is operated at a time when the predetermined time is delayed.

  In the vehicle travel safety device according to claim 2, the object detection means detects the object at a predetermined time interval, and the support actuating means determines the number of the recognized line segments at a detection time point. Even if there are two, when only one is recognized at the subsequent detection time, the contact avoidance support means is operated at the predetermined time.

According to the first aspect of the present invention, the line segment constituting the outline of one object is recognized and recognized based on the array of point groups obtained by projecting the reflection point obtained by reflecting the object onto the two-dimensional plane. The end point of the object is extracted based on the line segment, the relative relationship with the object is calculated based on the extracted end point, and the contact with the object is estimated based on the calculated relative relationship. In the traveling safety device for a vehicle that operates the contact avoidance assisting means that assists in avoiding contact with an object at a predetermined time before, when the number of recognized line segments is one, compared to when two are recognized, Since the contact avoidance support means is configured to operate when the predetermined time is delayed, it is possible to determine the likelihood of the end point from the number of recognized line segments. As a result, the vehicle from the side on the front cross or T-shaped road (Wow) approaching the driving path of (own vehicle) That Crossing can be detected accurately an object such as a vehicle, it is possible to effectively avoid contact with it.

  In addition, when the number of recognized line segments is 1, there is a possibility that the vehicle is not an encounter vehicle from the side, so contact avoidance support means is activated by operating the contact avoidance support means when the predetermined time is delayed. The excessive operation of the means can be prevented.

  In the vehicle travel safety device according to claim 2, even if the number of line segments recognized at a certain detection time is two, only one is recognized at the subsequent detection time, Since the contact avoidance support means is configured to operate at a predetermined time, it is possible to effectively avoid contact with an object such as an encounter vehicle. In other words, the fact that two line segments have been recognized in the past is that the extraction accuracy of the end points is high, and it is considered that only one line segment is recognized because the object has moved to the front of the vehicle (own vehicle). Thus, by operating the contact avoidance support means at the original predetermined time instead of the delay time, it is possible to reliably avoid contact with the object.

  The best mode for carrying out a vehicle travel safety device according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram generally showing a vehicle travel safety device according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes a vehicle (own vehicle), and a four-cylinder internal combustion engine (shown as “ENG” in FIG. 1, hereinafter referred to as “engine”) 12 is mounted on the front thereof. The output of the engine 12 is input to an automatic transmission (shown as “T / M” in FIG. 1) 14. The automatic transmission 14 is a stepped type with 5 forward speeds and 1 reverse speed, and the output of the engine 12 is appropriately shifted there and transmitted to the left and right front wheels 16, driving the left and right front wheels 16, and the left and right rear wheels. 20 is driven and the vehicle 10 is driven.

  The driver's seat of the vehicle 10 is provided with an alarm device 22 including an audio speaker and an indicator, and alerts the driver by voice and vision. A brake pedal 24 disposed on the driver's seat floor of the vehicle 10 is a brake (disc brake) mounted on each of the left and right front wheels 16 and rear wheels 20 via a master back 26, a master cylinder 30 and a brake hydraulic mechanism 32. 34.

  When the driver operates (depresses) the brake pedal 24, the depressing force (depressing force) is increased by the master back 26, and the master cylinder 30 generates a braking pressure with the increased depressing force, via the brake hydraulic mechanism 32. Then, the brakes 34 attached to the front wheels 16 and the rear wheels 20 are operated to decelerate (brake) the vehicle 10. A brake switch 36 is disposed in the vicinity of the brake pedal 24 and outputs an ON signal when the driver operates the brake pedal 24.

The brake hydraulic mechanism 32 includes an electromagnetic solenoid valve group inserted in an oil passage connected to a reservoir, a hydraulic pump, and an electric motor (all not shown) that drives the hydraulic pump. The electromagnetic solenoid valve group is connected to an ECU (Electronic Control Unit) 40 via a drive circuit (not shown), and thus the four brakes 34 are mutually connected by the ECU 40 separately from the operation of the brake pedal 24 by the driver. Configured to operate independently.

  In the above, the alarm device 22, the brake hydraulic mechanism 32 and the brake 34 correspond to contact avoidance support means, and the ECU 40 corresponds to support operation means.

A radar (laser scan radar) 42 is provided at the front of the vehicle 10. The radar 42 emits a laser beam (electromagnetic wave (carrier wave)) in the traveling direction of the vehicle 10, and approaches the traveling path of the vehicle (own vehicle) from the side at a cross road or T-shaped road in front of the vehicle 10. An object is detected by receiving a reflected wave obtained by reflecting a laser beam on an object such as an encounter vehicle. Reference numeral 42a indicates a detection area (scan range).

  The output of the radar 42 is sent to a radar output processing ECU (electronic control unit) 44 composed of a microcomputer. The radar output processing ECU 44 recognizes a line segment constituting the contour of the object based on an array of point clouds obtained by projecting the reflection points onto a two-dimensional plane, and determines an end point of the object based on the recognized line segment. Extract. Further, the direction of the object is detected from the incident direction of the reflected wave, and two-dimensional information of the object is obtained.

Then, the relative speed from when firing a laser beam, is relative distance calculated in the extracted edge point to the object is measured the time until receiving the reflected light, an object by further differentiating the relative distance That is, the radar output processing ECU 44 calculates a relative relationship with the object including the relative speed of the object with respect to the vehicle 10 based on the extracted end points. Note that details of line segment recognition and the like are described in the above-described prior art previously proposed by the present applicant, and thus detailed description thereof is omitted.

  The output of the radar output processing ECU 44 is sent to an ECU (electronic control unit) 40. Although illustration is omitted, the ECU 40 is constituted by a microcomputer including a CPU, a RAM, a ROM, an input / output circuit, and the like.

  A wheel speed sensor 46 is disposed in the vicinity of the front wheel 16 and the rear wheel 20 and outputs a pulse signal for each predetermined rotation angle of each wheel. A steering angle sensor 52 is disposed in the vicinity of the steering wheel 50 provided in the driver's seat of the vehicle 10 and generates an output proportional to the steering angle of the steering wheel 50 input by the driver. Further, a yaw rate sensor 56 is disposed in the vicinity of the center position of the vehicle 10 and generates an output corresponding to the yaw rate (angular velocity) around the gravity axis of the vehicle 10.

  A crank angle sensor 60 is disposed near the crankshaft (not shown) of the engine 12 to output a pulse signal such as a crank angle signal, and an absolute pressure sensor 62 is provided to the intake pipe (not shown). It is arranged and outputs a signal corresponding to the absolute pressure (engine load) in the intake pipe. A throttle opening sensor 64 is disposed near a throttle valve (not shown) and outputs a signal corresponding to the throttle opening.

  The output of the sensor group described above is also sent to the ECU 40. The ECU 40 counts the outputs of the four wheel speed sensors 46, calculates the average value thereof, and so on, detects the speed (vehicle speed) Vo of the vehicle 10, and counts the output of the crank angle sensor 60 to detect the engine. The rotational speed NE is detected.

  FIG. 2 is a flowchart showing the operation of the apparatus shown in FIG. This is executed in the ECU 40 every predetermined time, for example, every 100 msec.

  Explaining below, the vehicle information such as the vehicle speed Vo and the yaw rate detected by the wheel speed sensor 46 and the yaw rate sensor 56 in S10 is captured, and the process proceeds to S12, where the vehicle is based on the captured vehicle speed Vo and the yaw rate. 10 courses are estimated.

  Next, in S14, a flag is set from the detection state of the opponent vehicle (object).

  FIG. 3 is a sub-routine flow chart showing the processing.

  Prior to the description of FIG. 3, the operation of the vehicle travel safety device according to this embodiment will be described with reference to FIG.

  In FIG. 4 and subsequent figures, an object (partner vehicle) 104 such as a so-called encounter vehicle traveling on a cross road or T-shaped road 102 positioned in front of the traveling path 100 on which the vehicle 10 travels and approaching the traveling path 100 from the side. As described first, the object of the present invention is to effectively avoid contact with such an encounter vehicle (an opponent vehicle, an object) 104.

  As shown in FIG. 4 and the like, in the detection area 42a of the radar 42, the opponent vehicle 104 is regarded as a laser reflection point. When the reflection point is projected on a two-dimensional plane on the scanner data, which is composed of the traveling direction (X direction) of the own vehicle 10 and the direction (Y direction) orthogonal thereto, a plurality of reflection points of the opponent vehicle 104 are close to each other. Since the vehicle 104 is continuously distributed in position, the opponent vehicle 104 is expressed as a set of reflection points, that is, an array of point groups.

  Referring to FIG. 3, the output information of the radar 42 is fetched from the radar output processing ECU 44 in S100, and the process proceeds to S102, where the set of reflection points (array of point groups) described above is detected. Next, the process proceeds to S104, where line segments constituting the contour of the opponent vehicle 104 are recognized from the detected point cloud array, and end points are extracted based on the recognized line segments.

  In the example shown in FIG. 4, since the opponent vehicle 104 is detected on two surfaces, the traveling direction (X direction) and the direction orthogonal to the traveling direction (Y direction), two line segments are recognized and recognized. The end point P is extracted based on the line segment. In this case, since the end point P is a point corresponding to the forefront of the line segment of the opponent vehicle 104, the end point P means an end portion on the front side of the contour of the opponent vehicle 104. As described above, since the line segment is recognized by the radar output processing ECU 44, the ECU 40 actually stops reading the output of the radar output processing ECU 44 in the processing of S102 and S104.

  Next, the process proceeds to S106, where it is determined whether or not the number of recognized line segments is 2. If the determination is affirmative, the process proceeds to S108, and the bit of the flag is set (set) to 1. The example shown in FIGS. 4 and 5 corresponds to this.

  On the other hand, when the opponent vehicle 104 is detected on only one surface, the number of recognized line segments is one. Also, when the opponent vehicle 104 moves and reaches the front of the host vehicle 10 or the vicinity thereof, the number of line segments that can be recognized is one. The example shown in FIG.

  Accordingly, when the result in S106 is negative, the process proceeds to S110, where it is determined whether two line segments have been recognized at the past detection time, that is, at the past execution time of the flowchart of FIG. Advances to S108. On the other hand, when the result in S110 is negative, the program proceeds to S112, where the bit of the flag is set (set) to 0.

  Returning to the description of the flow chart of FIG. 2, the process then proceeds to S <b> 16 where the end point P obtained by the radar output processing is tracked in time series, the relative speed Vy of the opponent vehicle 104 with respect to the own vehicle 10, The distance Dt (corresponding to the relative position of the opponent vehicle 104 with respect to the host vehicle 10) between the extension line obtained by extending the end point P of the line segment constituting the contour of the host vehicle 10 and the host vehicle 10 is calculated. Thus, the relative relationship of the opponent vehicle 104 such as the relative speed Vy is calculated based on the extracted end point P. Note that the relative speed Vy and the like are actually read by reading the values calculated by the radar output processing ECU 44.

  Next, in S18, the predicted contact area Ac is obtained. As shown in FIG. 4, the predicted contact area Ac corresponds to the area of the host vehicle 10 at a position where the estimated route extension line of the host vehicle 10 (same as the line indicating the distance Dt) and the extension line of the opponent vehicle 104 intersect. In this area, if it is assumed that the driver of the host vehicle 10 does not take an avoiding action such as deceleration or change of course, and the opponent vehicle 104 also proceeds as it is, an area where the own vehicle 10 is predicted to contact the opponent vehicle 104 is means.

  Next, in S20, the predicted contact time TTCt (shown in FIG. 5) is calculated by dividing the calculated distance Dt from the calculated distance Dt and the own vehicle speed Vo, more specifically, by the detected own vehicle speed Vo. ) The predicted contact time TTCt is predicted to be required for the host vehicle 10 to contact the partner vehicle 104 when it is assumed that the driver does not take any avoidance action such as deceleration or course change and the partner vehicle 104 also travels as it is. Means time.

  Next, in S22, the distance Dy1 from the end point P of the opponent vehicle 104 to the predicted contact area Ac is obtained, and the distance Dy2 (the vehicle width of the own vehicle + α (set appropriately) and the vehicle length of the opponent vehicle 104 are added to Dy1. The time TTCy1 predicted to be required for the opponent vehicle 104 to reach the predicted contact area Ac from the obtained distances Dy1, Dy2 and the relative speed Vy of the opponent vehicle 104 with respect to the own vehicle 10 A time TTCy2 (shown in FIG. 5) that is predicted to be required for the opponent vehicle 104 to pass through the predicted contact area Ac is obtained.

  The time TTCy1 predicted to be required for the opponent vehicle 104 to reach the predicted contact area Ac is obtained by Dy1 / Vy. Further, the time TTCy2 predicted to be required for the opponent vehicle 104 to pass through the predicted contact area Ac is obtained by Dy2 / Vy.

  Next, the process proceeds to S24, and as shown in the figure, it is determined whether or not there is a relationship that the predicted contact time TTCt is between the calculated times TTCy1 and TTCy2. If it is affirmed and it is estimated that there is a possibility of contact, the process proceeds to S26, in which the flag bit is set to 0, that is, the number of recognized line segments is one. Judge.

  When it is determined negative in S26 and it is determined that the number of line segments recognized this time or last time is two, the process proceeds to S28, and it is determined whether or not the predicted contact time TTCt is less than a first time TTCthr1 (for example, 2.5 sec). . When the result in S28 is affirmative and the predicted contact time is determined to be less than the first time TTCthr1, the process proceeds to S30, the alarm device 22 is activated to alert the driver, and then the brake 34 is activated via the brake hydraulic mechanism 32. That is, the contact avoidance support means is activated.

  Next, in S32, after a set time (for example, 1.0 sec), the operation of the brake 34 is released. If the result in S28 is NO, there is a time allowance, and the processing of S30 and the like is skipped.

  On the other hand, when the result in S26 is affirmative, that is, when it is determined that the number of recognized line segments is one, the process proceeds to S34, and whether or not the predicted contact time TTCt is less than the second time TTCthr0 (for example, 2.0 sec). If the answer is affirmative, the process proceeds to S30, the alarm device 22 is activated, and the brake 34 is activated. Then, the process proceeds to S32, and after the set time has elapsed, the operation of the brake 34 is released.

  Note that when the result in S34 is NO, there is time in the same manner, and therefore the processing of S30 and the like is skipped. Further, when the result in S24 is NO, there is no possibility that the own vehicle 10 will come into contact with the opponent vehicle 104, and therefore the processing after S26 is skipped.

  In this embodiment, as described above, the line segments constituting the contour of the opponent vehicle 104 based on the array of point groups obtained by projecting the reflection points obtained by reflecting the opponent vehicle (object) 104 on a two-dimensional plane are shown. At the same time, the end point P of the opponent vehicle is extracted based on the recognized line segment, and the relative relationship composed of the relative speed Vy and the distances Dt, Dy1, and Dy2 of the opponent vehicle 104 is calculated based on the extracted end point P.

  The predicted contact time TTCt calculated based on the relative relationship consisting of the calculated relative speed Vy and the distances Dt, Dy1, and Dy2, more specifically based on the relative relationship, and the opponent vehicle 104 in the predicted contact area Ac. Based on the time TTCy1 predicted to be required to reach the vehicle and the time TTCy2 predicted to be required for the opponent vehicle 104 to pass the predicted contact area Ac, the presence / absence of the possibility that the host vehicle 10 may contact the opponent vehicle 104 is determined. When it is estimated that there is a possibility of contact (when TTCy1 <TTCt <TTCy2 holds), the opponent at a predetermined time before contact, that is, when the predicted contact time TTCt is less than the first time TTCthr1 Contact avoidance assisting means (alarm device 22, brake hydraulic mechanism 32 and brake 34) for assisting avoidance of contact with vehicle 104 In addition, when the number of recognized line segments is 1, when the predicted contact time TTCt is less than the second time TTCthr0 shorter than the first time TTCthr0 compared to the case where two line segments are recognized, In other words, since the contact avoidance support means is operated at a time when the predetermined time is delayed, it is possible to determine the likelihood of the end point P from the number of recognized line segments. Therefore, it is possible to accurately detect the opponent vehicle 104 such as a so-called encounter vehicle that approaches the estimated route (traveling route) of the host vehicle 10 from the side, and contact with the vehicle can be effectively avoided.

  In addition, when the number of recognized line segments is one, there is a possibility that the opponent vehicle 104 is not an encounter vehicle from the side. Therefore, by operating the contact avoidance support means when the predetermined time is delayed, The excessive operation of the contact avoidance support means can be prevented.

  Further, when only one line segment is recognized at the subsequent detection time point even though the number of line segments recognized at the past detection time point (a certain detection time point) is two, the contact avoidance support means at a predetermined time Therefore, it is possible to effectively avoid contact with the partner vehicle 104 such as an encounter vehicle. In other words, the fact that two line segments have been recognized in the past means that the extraction accuracy of the end point P is high, and it is considered that only one line segment is recognized because the opponent vehicle 104 has moved to the front of the host vehicle 10. Thus, by operating the contact avoidance support means at the original predetermined time instead of the delay time, it is possible to reliably avoid contact with the object.

This embodiment as described above, on the basis transmits the electromagnetic wave in the traveling direction of the vehicle (own vehicle) 10, the one object reflection points obtained by reflecting the (other vehicle) 104 existing in the traveling direction Based on an object detection means (radar 42, radar output processing ECU 44) for detecting an object and an array of point groups obtained by projecting the reflection points onto a two-dimensional plane, a line segment constituting the contour of the object is recognized. Line segment recognition means (ECU 40 (radar output processing ECU 44), S100 to S102), and end point extraction means (ECU 40 (radar output processing ECU 44), S104) for extracting the end point of the object based on the recognized line segment; , A relative relationship calculating means (ECU 40 (radar 40) for calculating a relative relationship with the object, including a relative speed Vy of the object with respect to the vehicle, based on the extracted end points. Force processing ECUs 44), S16), contact possibility estimation means (ECU 40, S18 to S24) for estimating the presence / absence of the possibility of the vehicle contacting the object based on the calculated relative relationship, When it is estimated that there is a possibility, contact avoidance support means (alarm device 22, brake hydraulic mechanism 32, brake 34) that supports contact avoidance between the vehicle and the object at a predetermined time (TTCt <TTCthr1) before contact. In the vehicle travel safety device provided with the assist actuating means (ECU 40, S24 to S32) for actuating the actuating device), the assist actuating means is recognized when the number of the recognized line segments is one. Compared to the case, the contact avoidance support means is operated at a time (TTCt <TTCthr0) delayed from the predetermined time (ECU 40, S26, S34, 30, S32) was as configuration.

  Further, the object detection means detects the object at a predetermined time interval, and the support activation means has two recognized line segments at a certain detection time point (past detection time point). However, when only one is recognized at the subsequent detection time (ECU 40, S110, S108), the contact avoidance support means is operated at the predetermined time (ECU 40, S26 to S32).

  In the above description, the object is detected from the output of the laser radar. However, instead of or in addition to this, a millimeter wave radar may be used.

  Further, although the alarm device 22 is alarmed by both sound and vision, the alarm device 22 may alarm only by either sound or vision. Further, instead of or in addition to the alarm device 22, a driver's seat (not shown) of the vehicle 10 may be vibrated by an appropriate means, or a seat belt (not shown) may be pulled in.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an overall traveling safety device for a vehicle according to an embodiment of the present invention. It is a flowchart which shows operation | movement of the apparatus shown in FIG. 2 is a sub-routine flow chart showing a flag setting process of the flow chart. 1 is projected onto the two-dimensional plane on the scanner data, which consists of the traveling direction (X direction) of the vehicle and the direction (Y direction) perpendicular to the traveling direction of the own vehicle. It is explanatory drawing obtained. Similarly, it is an explanatory diagram obtained by projecting the distribution of the reflection point group of the radar laser beam and the object shown in FIG. 1 onto a two-dimensional plane on the scanner data. Similarly, it is an explanatory diagram obtained by projecting the distribution of the reflection point group of the radar laser beam and the object shown in FIG. 1 onto a two-dimensional plane on the scanner data.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Vehicle (own vehicle), 12 engine (internal combustion engine), 16 front wheel, 20 rear wheel, 22 alarm device, 34 brake, 36 brake switch, 40 ECU (electronic control unit), 42 laser radar, 42a detection area, 44 radar Output processing ECU, 46 wheel speed sensor, 100 traveling road, 102 cross road or T-shaped road, 104 object (partner vehicle)

Claims (2)

Transmits the electromagnetic wave in the traveling direction of the vehicle, and object detecting means for detecting the object based on the reflection points obtained by reflecting the one object present in the advancing direction, projecting the reflection point on the two-dimensional plane Line segment recognizing means for recognizing a line segment constituting the outline of the object based on the array of point groups obtained as described above, and end point extracting means for extracting the end point of the object based on the recognized line segment; Relative relationship calculating means for calculating a relative relationship between the object including the relative speed of the object with respect to the vehicle based on the extracted end points, and the vehicle contacting the object based on the calculated relative relationship Contact possibility estimating means for estimating the possibility of contact, and contact avoidance support that supports contact avoidance between the vehicle and the object at a predetermined time before contact when it is estimated that there is a possibility of contact Actuated means In the vehicle travel safety device comprising the support actuating means, the support actuating means delays the predetermined time when the number of recognized line segments is one when compared with the case when two are recognized. A travel safety device for a vehicle, wherein the contact avoidance support means is actuated at a time when the contact is made.   The object detection means detects the object at a predetermined time interval, and the support actuating means detects a subsequent detection time point even though the number of recognized line segments is two at a detection time point. 2. The vehicle travel safety device according to claim 1, wherein when only one is recognized, the contact avoidance support means is operated at the predetermined time.

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