JP2006048568A - Object recognition method and object recognizing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recognize an object ahead of own vehicle, as accurately as possible, by distinguishing the object from other objects running alongside the object, based on the results of searches that a scanning laser radar mounted in own vehicle conducts, in an area ahead of own vehicle. <P>SOLUTION: The scanning laser radar 2 mounted in own vehicle 1 horizontally scans the area ahead of own vehicle and detects laser beam reflection points. The distance from the one's own vehicle 1 to each of the laser beam reflection points is measured, on the basis of a time difference between the transmission and reception of the laser radar 2. Of the laser beam reflecting points, the points whose measured distances are approximately equal within a set tolerance are selected as candidate points for recognition of the same object ahead of own vehicle. If any of the laser beam reflecting points that are located ahead of the candidate points by a set distance or more exist between two horizontally adjoining candidate points for recognition, the two candidate points for recognition are determined as the laser beam reflecting points of different objects and inhibited from merging, while the selected candidate points for recognition are merged and combined. Based on the result of the merging, the object to be recognized ahead of own vehicle is recognized, as it is, being distinguished from other objects running alongside the object. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an object recognition method and an object recognition device for recognizing an object in front of a host vehicle such as a preceding vehicle from a search result in front of the host vehicle of a scanning laser radar mounted on the host vehicle. The present invention relates to an object recognition method and an object recognition apparatus for recognizing an object to be recognized separately from other objects that run in parallel.

  Conventionally, in a vehicle equipped with a vehicle driving support system called ACC (Adaptive Cruise Control), a pre-crash safety system, etc., an approach to an obstacle such as a preceding vehicle ahead of the host vehicle is warned, or so-called damage reduction automatic braking In order to realize functions, etc., an image pickup device represented by a scanning laser radar or a monocular camera is installed in the vehicle as a detection sensor (vehicle front detection sensor) for the object to be recognized in front of the vehicle (the obstacle). Then, the object ahead of the vehicle is recognized continuously (from moment to moment).

  When a scanning laser radar is mounted on the host vehicle as the detection sensor, the front of the host vehicle is searched by scanning the front of the host vehicle in the vehicle width direction (left-right direction) with laser pulse irradiation. Repeatedly, the object to be recognized such as the preceding vehicle is detected from the range of each laser reflection point by receiving the reflected wave of the laser reflection point at the reflector of the vehicle in front of the host vehicle (so-called four-wheeled vehicle and two-wheeled vehicle) (For example, refer to Patent Document 1).

  On the other hand, when only the imaging device is mounted on the host vehicle as the detection sensor, the front of the host vehicle is continuously shot by the imaging device, so-called optical flow is detected by image processing such as edge detection of the shot image, and the It has been proposed to recognize an object to be recognized, such as a preceding vehicle ahead of the vehicle, separately from a non-recognized object such as a roadside signboard, a road sign or a road structure such as a guardrail (for example, see Patent Document 2). .)

  Also, a scanning laser radar and an imaging device are installed in the vehicle to form a so-called sensor fusion front detection sensor, and information on the front of the vehicle is obtained by exploring the scanning radar and imaging the imaging device. It has also been proposed to recognize an object to be recognized in front of the host vehicle such as a preceding vehicle having the possibility of being distinguished from the non-recognized object more accurately (see, for example, Patent Document 3).

JP-A-6-309600 (paragraphs [0010]-[0015], FIG. 2) JP 11-353565 (paragraphs [0022]-[0025], [0048], FIG. 1) JP 7-182484 A (paragraphs [0006]-[0010], FIG. 1)

  In the case of a conventional configuration in which a scanning laser radar is mounted on the vehicle as the vehicle front detection sensor, each laser reflection point received by the laser radar is unconditionally reflected on the same object to be recognized in each laser radar search. For example, as shown in FIG. 6A, the laser reflection points Ra of the left and right reflectors of the preceding vehicle (four-wheeled vehicle) A, which is an object to be recognized in front of the host vehicle, and the left or right The four-wheeled vehicle, two-wheeled vehicle, roadside object, and the laser reflection point Rb of the non-recognized target object B consisting of a railing of a bridge are combined into one, and the objects A and B are defined as one object C to be recognized. There is a risk of misrecognition.

  Further, as shown in FIG. 6B, the laser reflection points Rd and Re of two objects D and E such as a two-wheeled vehicle running in front of the host vehicle are combined into one, and both the objects D and E are combined. May be erroneously recognized as one object F to be recognized. In the case of FIG. 6B, the objects D and E are objects to be recognized.

  When such erroneous recognition occurs, for example, erroneous detection of the distance (inter-vehicle distance) and speed (relative speed) of the object A to be recognized shown in FIG. 6 occurs, and malfunctions such as ACC and pre-crash safety system occur. There is a problem that causes a fatal control error due to a misjudgment of the possibility of rear-end collision.

  On the other hand, in the case of the conventional configuration in which the conventional imaging device is mounted alone or in combination with a scanning laser radar on the own vehicle, the recognition target object and the non-recognition target object are recognized separately from the captured image. However, an expensive imaging device is required, and complicated image processing is also required, resulting in a problem of an expensive and complicated configuration.

  In this type of object recognition, from the viewpoint of improving safety with an inexpensive configuration as much as possible, only a scanning laser radar is mounted on the vehicle as a vehicle front detection sensor, It is desirable to accurately recognize an object to be recognized.

  The present invention recognizes the object to be recognized in front of the own vehicle as accurately as possible by distinguishing it from other objects that run in parallel, based on the result of the scanning laser radar mounted on the own vehicle in front of the own vehicle. Objective.

  In order to achieve the above-described object, the object recognition method of the present invention scans the front of the vehicle in the left-right direction by a scanning laser radar mounted on the vehicle, detects each laser reflection point, The distance from the vehicle to each laser reflection point is measured based on the transmission / reception time difference, and the laser reflection points that are substantially equal within the error range set by the measurement distance among the laser reflection points are respectively the same object in front of the vehicle. And when there is a laser reflection point ahead of the discrimination distance set by the two recognition candidate points between the two recognition candidate points adjacent to the left and right, the two recognition candidate points are used as lasers of different objects. While determining the reflection point and prohibiting the merge processing of the two recognition candidate points, the selected recognition candidate points are merged and combined, and the object ahead of the host vehicle is recognized from the combined state of the recognition candidate points. That It is a symptom (claim 1).

  In this case, the object presence range in the next scan of the laser radar is predicted from the recognition result of the object ahead of the host vehicle based on the current scan of the scanning laser radar and the detection speed of the object, and the object of the next scan It is practical and preferable to limit the laser reflection points effective for object recognition to the laser reflection points in the existence range.

  Next, the object recognition apparatus of the present invention is mounted on the own vehicle, scans the front of the own vehicle in the left-right direction, detects each laser reflection point, and based on the transmission / reception time difference between the laser radars. Ranging calculation means for measuring the distance from the own vehicle to each of the laser reflection points, and the same object in front of the own vehicle with laser reflection points that are substantially equal within the error range set by the measurement distance among the laser reflection points. If there is a laser reflection point that is more than the discrimination distance set by the candidate point selection means for selecting the recognition candidate point and the two recognition candidate points on the left and right adjacent to the recognition candidate points, the two recognition candidate points Merge processing means for merging and combining selected recognition candidate points while determining the laser reflection point of each different object and prohibiting the merge processing of the two recognition candidate points, and the combined state of the recognition candidate points From It is characterized in that a recognizing process means the car in front of the object (claim 3).

  In this case, provided with a range prediction means for predicting the existence range of the object in the next scan of the laser radar from the recognition result of the object ahead of the vehicle based on the current scan of the scanning laser radar and the detection speed of the object, It is practically preferable to limit the laser reflection point effective for the recognition of the object in the next scanning to the laser reflection point in the existence range by the distance measurement calculation means.

  First, according to the configuration of claims 1 and 3, each time the scanning laser radar mounted on the host vehicle is searched, the laser reflection points in the left and right directions ahead of the host vehicle are detected, and the transmission / reception time difference of the scanning laser radar is detected. The distance from the vehicle to each laser reflection point is measured by the distance measuring process based on the above.

  Further, laser reflection points that are substantially equal within the error range set by the measurement distance among the laser reflection points are selected as recognition candidate points for the same object in front of the host vehicle that is equidistant from the host vehicle.

  Next, in each selected recognition candidate point, when there is a laser reflection point of a more forward (distant) object between the two recognition candidate points adjacent to the left and right, the two recognition candidate points Since it is a laser reflection point, the two recognition candidate points adjacent to the left and right are prohibited from being merged as laser reflection points of different objects, and the remaining recognition candidate points are merged and combined.

  At this time, only the recognition candidate points of the same object in front of the host vehicle are combined into one by the merge process, and the recognition target object in front of the host vehicle is distinguished from other objects such as parallel running from the combined state. can do.

  Therefore, the object to be recognized in front of the own vehicle can be recognized as accurately as possible by distinguishing it from other objects that run in parallel, based on the result of the scanning laser radar mounted on the own vehicle in front of the own vehicle.

  Next, according to the configuration of claims 2 and 4, the object in the next scan of the scanning laser radar is obtained from the recognition result of the object ahead of the host vehicle based on the current scanning of the scanning laser radar and the detection speed of the object. Based on this prediction, the laser reflection point effective for recognizing the object is limited to the laser reflection point in the existence range in the next scanning of the scanning laser radar. The object in front of the host vehicle can be recognized without the unnecessary laser reflection point, and the object to be recognized in front of the host vehicle can be recognized more accurately with a practical configuration.

  Next, in order to describe the present invention in more detail, one embodiment thereof will be described in detail with reference to FIGS.

  FIG. 1 is a block diagram of an object recognition device for an own vehicle 1 having an approach warning / automatic brake control function such as an ACC and a pre-crash safety system, and FIGS. 2 and 3 are search results of the scanning laser radar 2 of FIG. FIG. 4 is an explanatory diagram of a scanning range of the scanning laser radar 2, and FIG. 5 is a flowchart for explaining processing of the object recognition apparatus of FIG.

  The object recognition apparatus shown in FIG. 1 includes only an inexpensive and small-sized scanning laser radar 2 mounted on the own vehicle 1 as the own vehicle forward detection sensor.

  This scanning laser radar 2 is provided at almost the vehicle center position such as the interior of the own vehicle 1 or in the hood, and repeatedly scans the front of the own vehicle in the left-right direction (vehicle width direction) while irradiating the laser with pulses. The front side of the vehicle is searched while receiving the reflected waves from the reflector of the vehicle (so-called four-wheeled vehicle, two-wheeled vehicle).

  The object recognition apparatus also includes various sensors for detecting the vehicle state such as a vehicle speed sensor 3 having a wheel speed sensor configuration for detecting the vehicle speed.

  After the engine of the host vehicle 1 is started, the scanning laser radar 2 repeatedly searches the front of the host vehicle, and transmits a laser pulse transmission (emission) timing signal and a received signal at the laser reflection point of the search result as an object of a microcomputer configuration. It outputs to ECU4 for recognition processing.

  The ECU 4 executes recognition processing based on an object recognition program set in advance in the memory unit 5, and next distance measurement calculation means 41, candidate point selection means 42, merge processing means 43, recognition output means 44, range prediction means 45 is formed.

(A) Ranging calculation means 41
This means 41 calculates the difference in transmission / reception time of the laser pulse based on the signal of the transmission timing of the radar pulse and the reception signal of the laser reflection point for every exploration of the scanning laser radar 2, and from the own vehicle 1 based on the calculated time difference. The distance to each laser reflection point is measured, and for example, the latest measurement result for one search is held in the memory unit 5 in a rewritable manner.

  By the way, the distance may be measured for the laser reflection points in the entire scanning range of the scanning laser radar 2, but in this embodiment, the distance is measured in the next scanning based on the prediction of the existence range of the range prediction means 45 described later. The effective laser reflection points are limited to the laser reflection points in the existing range, and the unnecessary laser reflection points in the scanning range of the scanning laser radar 2 are not measured to reduce the processing burden on the ECU 4 and to prevent errors. Prevent recognition.

(B) Candidate point selection means 42
Each time a new exploration measurement result is written in the memory unit 5, the means 42 sets each laser reflection point that is substantially equal within the error range set by the measurement distance among the laser reflection points to the same in front of the vehicle. Select object recognition candidate points.

  Specifically, as shown in the search results of FIGS. 2 and 3, for example, in the case of FIG. 2, the laser reflection point R <b> 11 in order from the left, which is substantially equidistant within the error range from the scanning laser radar 2, R12 and R13 are selected as recognition candidate points R11 *, R12 *, and R13 * of the same object. Similarly, in the case of FIG. 3, in order from the left, which is substantially equidistant within the error range, from the scanning laser radar 2. The laser reflection points R21, R22, and R23 are selected as recognition candidate points R21 *, R22 *, and R23 * of the same object. The distance of the error range is set based on experiments or the like, and is a constant value or a variable value that varies depending on the relative vehicle speed of an object ahead of the host vehicle such as a preceding vehicle, and is shorter than the vehicle length of various vehicles. It is.

(C) Merge processing means 43
This means 43, when there is a laser reflection point ahead of the discrimination distance α set by both recognition candidate points between the two recognition candidate points adjacent to the left and right, the two recognition candidate points adjacent to the left and right While determining the laser reflection point and prohibiting the merge process, the selected recognition candidate points are merged and combined.

  Specifically, for example, the recognition candidate points R11 * to R13 * in FIG. 2 are more than the discrimination distance α between the left and right two recognition candidate points R11 * and R12 * and between Ri2 * and Ri3 *. Therefore, all the recognition candidate points R11 * to R13 * are assumed to be laser reflection points of one preceding vehicle (the same object) ahead of the host vehicle, and the merge process is not prohibited. Are allowed to be joined together in a chain as shown by the connecting line a in the figure.

  On the other hand, for the recognition candidate points R21 * to R23 * in FIG. 3, between the two recognition candidate points R22 * and R23 * of the left and right two recognition candidate points R21 * and R22 *, R222 * and R23 *, There is a laser reflection point whose measurement distance is equal to or greater than the distance between the recognition candidate points R21 * to R23 * + the discrimination distance α, that is, a laser reflection point R3 that is ahead of the discrimination candidate point R21 * to R23 * by the discrimination distance α. .

  In this case, the laser reflection point R3 is not a laser reflection point of an object immediately preceding the preceding vehicle or the like ahead of the host vehicle, but a laser reflection point of an object such as a vehicle further ahead of the vehicle. The recognition candidate point R22 * and the recognition candidate point R23 * are obtained as laser reflection points of separate objects, and the laser reflected wave of the object such as a vehicle ahead of the object passes through the gap between the two objects. This is because the scanning laser radar 2 receives the signal.

  Therefore, for the recognition candidate points R21 * to R23 *, the merge processing of the recognition candidate points R22 * and R23 * is prohibited, and the recognition candidate points R21 * and R22 * are reflected by the same object such as a preceding vehicle ahead of the host vehicle. They are combined as points, and are combined into one as shown in FIG.

  The discrimination distance α is a fixed value set in consideration of the size of an object in front of the host vehicle, the distance in the front-rear direction (inter-vehicle distance), or the like based on experiments on various vehicles or the like. It is a variable value that changes according to variations in dimensions such as the width of the object.

(D) Recognition processing means 44
The means 44 recognizes an object ahead of the host vehicle from the processing result of the merge processing means 43 and outputs a recognition result.

  That is, when the merge processing result of FIG. 2 is obtained, the width and position of an object to be recognized such as a preceding vehicle in front of the host vehicle are detected from the width of the area gathered by the connecting line a in FIG. 3 and the merge processing result of FIG. 3 is obtained, similarly, the width and position of the object to be recognized such as the preceding vehicle ahead of the host vehicle are determined from the width of the area gathered by the connecting line b in FIG. The object is detected and recognized, and information on the width and position of the recognized object is output as an output of the recognition result.

(E) Range prediction means 45
This means 45 detects the detected vehicle speed (relative speed or vehicle speed sensor 3 based on the recognition result of the recognition processing means 44 based on the current scan of the scanning laser radar 2 and the time variation of the recognized measurement distance of the object ahead of the host vehicle. The range of the next scanning of an object ahead of the host vehicle such as the preceding vehicle is predicted from the detected speed such as the absolute speed obtained by adding the detected host vehicle speed).

  That is, based on the information on the width and position of the object recognized by the recognition processing means 44 in each scan of the scanning laser radar 2 and the relative speed of the object, the vehicle approaches or moves toward the vehicle 1 at that speed. The position change due to the separation from the vehicle 1 is traced to estimate where the object is located in the scanning range at the next scanning of the scanning laser radar 2, and the existence range of the next scanning is predicted from the estimated range.

  Then, this prediction result is supplied to the distance measurement calculation means 41, and the next scan of the scanning laser radar 2 is predicted from, for example, the current scanning range W1 or W2 within the entire scanning range W0 shown in FIG. The laser reflection point that is variable to the existing range W2 or W1 and is effective for recognizing the next scanning object of the scanning laser radar 2 is limited to the predicted laser reflection point of the existing range. The distance is measured only for the laser reflection point.

  When the above processing is shown in a flowchart, for example, as shown in steps S1 to S5 in FIG. 5, when the search output of the scanning laser radar 2 is generated in step S1 while the host vehicle 1 is traveling, the processing in step S2 is performed. The process shifts to a ranging process, and the distance calculation means 41 measures the distance from the own vehicle for each laser reflection point based on the search output of the scanning laser radar 2.

  Further, the process proceeds to the merge candidate point selection process in step S3, the recognition candidate point is selected by the candidate point selection means 42, and each recognition candidate point selected by the merge process in step S4 is merged by the merge processing means 43. In consideration of the prohibition of the processing, it is combined, and the recognition processing means 44 recognizes an object such as a preceding vehicle ahead of the host vehicle based on the result of the combination of the merge processing by the recognition processing in step S5. Then, the range predicting unit 45 predicts the existence range of the object for the next scan.

  Therefore, in the case of this embodiment, as a detection sensor in front of the own vehicle, an inexpensive configuration in which only the scanning laser radar 2 is mounted on the own vehicle 1 is used to recognize the front of the own vehicle such as a preceding vehicle based on the search result. The target object can be accurately recognized by being distinguished from other objects such as a parallel running vehicle.

  Based on the recognition result, the distance (inter-vehicle distance) and speed (relative speed) from the own vehicle can be accurately detected for the recognized object. Further, based on these detections, ACC and pre-crash safety can be detected. It is possible to prevent the erroneous determination of the possibility of rear-end collision in the system or the like, and to prevent the occurrence of a fatal control error by preventing the automatic brake from being erroneously controlled.

  Further, the effective range of the laser reflection point to be measured by the next scanning of the scanning laser radar 2 is estimated by predicting the range of the next scanning of the object to be recognized from the recognition result and the detection speed of the scanning laser radar 2 this time. Since it is limited to the laser reflection points in the predicted existence range, the processing of the ECU 4 can be performed quickly, and erroneous recognition based on unnecessary laser reflection points can be prevented to further improve the recognition accuracy.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof. For example, the range predicting means 45 is omitted. In each search of the scanning laser radar 2, distance measurement processing of laser reflection points in the entire scanning range may be performed.

  Of course, the recognition result can be applied not only to the approach warning / automatic brake control but also to various travel controls of the vehicle 1.

  By the way, in order to reduce the number of equipment parts of the own vehicle 1, for example, the scanning laser radar 2 of FIG. 1 can be applied to other control sensors such as follow-up traveling control.

It is a block diagram of one embodiment of this invention. It is explanatory drawing of an example of the search result of the scanning laser radar of FIG. It is explanatory drawing of the other example of the search result of the scanning laser radar of FIG. It is explanatory drawing of the scanning range of the scanning laser radar of FIG. It is a flowchart for process description of FIG. It is explanatory drawing of the recognition process of a prior art example.

Explanation of symbols

1 Vehicle 2 Scanning laser radar 4 ECU
41 Distance calculation means 42 Candidate point selection means 43 Merge processing means 44 Recognition processing means 45 Range prediction means R11 to R13, R21 to R23, R3 Laser reflection points R11 * to R13 *, R21 * to R23 * Recognition candidate points

Claims (4)

Scanning the front of the vehicle in the left-right direction with the scanning laser radar mounted on the vehicle, and detecting each laser reflection point,
Measure the distance from the own vehicle to each laser reflection point based on the transmission / reception time difference of the laser radar,
A laser reflection point that is substantially equal within an error range set by the measurement distance among the laser reflection points is selected as a recognition candidate point for the same object in front of the vehicle,
When there is a laser reflection point that is more than the discrimination distance set from the two recognition candidate points on the left and right adjacent to the two recognition candidate points, the two recognition candidate points are determined as laser reflection points of different objects, and the 2 While prohibiting recognition candidate point merging, merge each selected recognition candidate point,
An object recognition method characterized by recognizing an object ahead of the host vehicle from a combined state of the respective recognition candidate points. From the recognition result of the object ahead of the vehicle based on the current scan of the scanning laser radar and the detection speed of the object, predict the existence range of the object in the next scan of the laser radar,
2. The object recognition method according to claim 1, wherein a laser reflection point effective for recognition of the object in the next scan is limited to a laser reflection point in the existence range. A scanning laser radar mounted on the host vehicle that scans the front of the host vehicle in the left-right direction and detects each laser reflection point;
Ranging calculation means for measuring the distance from the own vehicle to each of the laser reflection points based on the transmission / reception time difference of the laser radar;
Candidate point selection means for selecting laser reflection points that are substantially equal within the error range set by the measurement distance among the laser reflection points as recognition candidate points for the same object in front of the vehicle,
When there is a laser reflection point that is more than the discrimination distance set from the two recognition candidate points on the left and right adjacent to the two recognition candidate points, the two recognition candidate points are determined as laser reflection points of different objects, and the 2 Merge processing means for merging and combining selected recognition candidate points while prohibiting recognition candidate point merge processing;
An object recognition apparatus comprising: a recognition processing means for recognizing an object ahead of the host vehicle from the combined state of the recognition candidate points. A range prediction means for predicting the existence range of the object in the next scan of the laser radar from the recognition result of the object ahead of the vehicle based on the current scan of the scanning laser radar and the detection speed of the object;
4. The object recognition apparatus according to claim 3, wherein the laser reflection point effective for recognizing the object in the next scan is limited to the laser reflection point in the existence range by the distance measuring means.

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