JP5163084B2 - Object detection device - Google Patents

Description

  The present invention relates to an object detection apparatus that detects an object using a detection point by a radar.

In recent years, driving support devices such as collision prevention devices and inter-vehicle control devices have been developed. In these driving assistance devices, it is important to detect a vehicle traveling in front of the host vehicle. The object detection apparatus groups detection points that satisfy a predetermined condition among a large number of detection points detected by a radar such as a laser radar, and obtains object information from the group of detection points of each group (Patent Document) 1, see Patent Document 2).
JP 2006-38755 A JP 2007-212418 A

  In the case of a laser radar, the laser beam is irradiated radially at a predetermined angular interval, so that the distance resolution becomes worse as the distance from the laser radar increases. For this reason, if grouping is performed under the same conditions without taking this distance resolution into consideration, there is a case where appropriate grouping is not performed on detection points for an object existing at a position away from the laser radar. As a result, for example, detection points for one object may be grouped into a plurality of groups and detected as a plurality of objects.

  Therefore, an object of the present invention is to provide an object detection apparatus that detects an object with high accuracy in object detection using a radar.

The object detection apparatus according to the present invention includes a radar detection unit that detects the position of an object, a distance calculation unit that calculates a distance between two detection points detected by the radar detection unit, and a distance calculation unit that uses 2 Based on the larger distance resolution of the radar detection means at each position of each detection point, the distance calculation means calculates the threshold value setting means for setting a larger value as the grouping threshold value as the distance resolution is larger. If the distance between the two detection points is less than the threshold value set by the threshold setting means, the two detection points are grouped together to group the detection points detected by the radar detection means. a grouping means for, for each group that is grouped by the grouping unit, further comprising a object detecting means for detecting an object using the detection points in the group And butterflies.

  In this object detection device, an electromagnetic wave is transmitted by the radar detection means and the reflected electromagnetic wave is received, and a detection point for the object is acquired based on transmission / reception information of the electromagnetic wave. Since the radar detecting means transmits electromagnetic waves radially at every predetermined angle, the distance between the transmitted electromagnetic waves becomes wider and the distance resolution deteriorates as the distance from the radar detecting means increases. Therefore, as the object is located farther from the laser detection means, the distance between the detection points with respect to the object becomes wider. Therefore, in the object detection apparatus, the threshold value of the grouping is set by the threshold value setting means according to the distance resolution of the radar detection means at the position of each detection point. In the object detection apparatus, each detection point is grouped by the grouping unit based on the set threshold value, and the object is detected using the detection point of each group grouped by the object detection unit. As described above, in this object detection apparatus, by appropriately changing the grouping threshold according to the distance resolution at the position of the detection point, appropriate grouping can be performed according to the distance resolution, and the object can be detected with high accuracy. be able to.

  In this object detection device, the distance between the two detection points is calculated by the distance calculation means. In the object detection apparatus, the distance resolution at each position of the two detection points is compared by the threshold setting means, and the grouping threshold is set according to the larger distance resolution. Further, in the object detection device, when the distance between the two detection points is less than the set threshold by the grouping means, the two detection points are set to the same group. As described above, the object detection apparatus dynamically changes the grouping threshold according to the larger distance resolution among the distance resolutions at the respective positions of the two detection points to be grouped, thereby detecting the two detection points. It is possible to determine with high accuracy whether or not the points may be in the same group (that is, whether or not the points are detection points for the same object).

  The present invention can detect an object with high accuracy by changing the grouping threshold according to the distance resolution of the radar detection means at the position of the detection point.

  Hereinafter, an embodiment of an object detection device according to the present invention will be described with reference to the drawings.

  In the present embodiment, the object detection device according to the present invention is applied to an obstacle detection device mounted on a vehicle. The obstacle detection device according to the present embodiment detects obstacles around the vehicle (for example, other vehicles, bicycles, and pedestrians), and uses the detected obstacle information as a driving support device such as an inter-vehicle control device or a collision prevention device. To provide. The detection direction may be the entire circumferential direction of the vehicle, or only the direction according to the purpose such as front, side, and rear.

  With reference to FIGS. 1-3, the obstruction detection apparatus 1 which concerns on this Embodiment is demonstrated. FIG. 1 is a configuration diagram of an obstacle detection apparatus according to the present embodiment. FIG. 2 is an explanatory diagram of a grouping method in the ECU of FIG. FIG. 3 shows an example of the grouping result. (A) shows the result of the conventional grouping method, and (b) shows the result of the grouping method in the ECU of FIG.

  The obstacle detection apparatus 1 acquires detection points by a radar using laser light, groups the detection points based on the distance between the two detection points, and obtains obstacle information from the detection points of each grouped group. In particular, the obstacle detection apparatus 1 changes the grouping threshold according to the distance resolution of the radar at the position of the detection point in order to improve the grouping accuracy. For this purpose, the obstacle detection device 1 includes a laser radar 2 and an ECU [Electronic Control Unit] 3.

  In the present embodiment, the laser radar 2 corresponds to the laser detection means described in the claims, and each process in the ECU 3 includes the threshold setting means, the grouping means, the object detection means, and the distance described in the claims. It corresponds to the calculation means.

  The laser radar 2 is a radar that detects an object using laser light. One or a plurality of laser radars 2 are provided according to the detection direction (detection region) of the obstacle, and are attached to a predetermined location (for example, the center of the front end) of the vehicle according to the detection direction of the obstacle. The laser radar 2 emits laser light at a predetermined angle in the left-right direction at regular intervals, and receives the reflected laser light. Each time the laser beam is received, the laser radar 2 calculates a relative distance from the detection point (reflection point) based on at least the time from emission to reception, and detects the detection point (reflection point) from the emission angle of the laser beam. The relative direction is calculated. Then, the laser radar 2 transmits information (relative distance, relative direction, etc.) about all the detection points that can be detected by one scan at regular intervals to the ECU 3 as a radar signal.

  As shown in FIG. 2, laser beams L1, L2,... Are emitted radially from the laser radar 2 at predetermined angular intervals. Therefore, when the distance DN between the laser beams L1 and L2 at a position close to the laser radar 2 is compared with the distance DD between the laser beams L1 and L2 at a position far from the laser radar 2, the distance DD at a position far from the laser radar 2 becomes wider. That is, as the position is farther from the laser radar 2, the distance resolution of the laser radar 2 becomes larger and the interval between detection points becomes wider.

  The ECU 3 is an electronic control unit including a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like, and comprehensively controls the obstacle detection apparatus 1. The ECU 3 receives a radar signal from the laser radar 2 at regular intervals. Then, the ECU 3 performs obstacle detection processing using information on detection points included in the radar signal at regular intervals, and when the obstacle is detected, the ECU 3 is operated using the obstacle information as an obstacle information signal. Send to support device.

  The obstacle detection process will be described. When the ECU 3 acquires the information of the detection points, the same number of label arrays as the detection points detected in one scan are secured in a predetermined area of the RAM, and the label array is initialized. The label array is an array for storing the group numbers of the respective detection points, and the detection points having the same group number are the same group (obstacle).

  The ECU 3 sequentially extracts combinations of two detection points from all detection points detected in one scan, and performs the following processing for all combinations. First, the ECU 3 calculates the distance between the two detection points based on the extracted relative distance and relative direction of each detection point. Next, the ECU 3 calculates distance resolution at each position (distance from the laser radar 2) of the two detected detection points. The ECU 3 compares the two distance resolutions, and sets a grouping threshold according to the larger distance resolution (that is, the distance resolution at the detection point far from the laser radar 2). Here, the larger distance resolution may be set as the threshold value as it is, or a value obtained by multiplying the larger distance resolution by a safety factor (a coefficient larger than 1) is used as the threshold value in order to have some margin. Also good. Therefore, as the threshold value, the distance resolution itself at the position of the detection point far from the laser radar 2 or a value slightly larger than the distance resolution is set. Next, the ECU 3 compares the calculated distance between the detection points and the set threshold value, and if the distance between the detection points is less than the threshold value, a label with the same number is assigned to the two detection points. If the distance between the detection points is less than the threshold value and one of the two detection points to which the same number of labels is assigned has already been labeled, the other detection point has one of the detection points. Is given a label with a number already assigned.

  In the example shown in FIG. 2, in the case of the combination of the detection point P <b> 1 and the detection point P <b> 2, the detection point P <b> 1 and the detection point P <b> 2 are approximately the same position from the laser radar 2 and relatively close to the laser radar 2. , A small threshold value is set. However, since the distance between the detection point P1 and the detection point P2 is also narrow, the distance between the detection points P1 and P2 is less than the small threshold value, and the same label is assigned to the detection point P1 and the detection point P2. In the case of the combination of the detection point P8 and the detection point P9, the detection point P8 and the detection point P9 are at the same position from the laser radar 2 and relatively far from the laser radar 2, so a large threshold value is set. Is done. Therefore, although the distance between the detection point P8 and the detection point P9 is relatively wide, the distance between the detection points P8 and P9 is less than the large threshold value, and the same label is assigned to the detection point P8 and the detection point P9. In the case of the combination of the detection point P1 and the detection point P8, since the detection point P8 is located farther from the laser radar 2 than the detection point P1, a threshold value having a large value corresponding to the position of the detection point P8 is set. However, since the distance between the detection point P1 and the detection point P8 is very wide, the distance between the detection points P1 and P8 is equal to or greater than the large threshold value, and the same label is not given to the detection point P1 and the detection point P8.

  When the process for all combinations of the two detection points is completed, the ECU 3 assigns a label with a new number to the detection point to which no label is assigned. That is, different numbers are assigned to detection points that do not have a combination of detection points whose distance between detection points is less than the threshold. And in ECU3, based on the label number of each detection point in a label arrangement | sequence, the detection point of the same number is divided into the same group. Further, for each group, the ECU 3 calculates the position, size, speed, movement direction, and the like of the group (that is, the obstacle) from the relative positions and relative directions of all detection points included in the group. The speed and the moving direction are calculated based on the change from the position at the previous time using the obstacle information at the previous time (may also use past obstacle information such as the previous time). It should be noted that a group in which the number of detection points of the group is less than a predetermined number is not recognized as an obstacle and information on the obstacle is not calculated.

  In the example of FIG. 2, the detection points P1,..., P7 are assigned labels with the same number to form a group G1, the detection points P8,. Is formed.

  In the example shown in FIG. 3, the laser beam emitted from the laser radar 2 at every predetermined angle is reflected from the front surface of the other vehicle to the left side surface, and a large number of detection points P1, P2,. . In this example, the left front end (detection points P5, P6) of the other vehicle is closest to the laser radar 2, and the rear side of the left side surface (detection point P12, etc.) is farther from the laser radar 2. The detection point interval (between detection points P11 and P12, etc.) is wider toward the rear side of the left side surface. Therefore, when the distance between the detection points is determined with the same threshold value according to the conventional grouping technique, the groups are grouped into a plurality of groups Ga1, Ga2,... As shown in FIG. However, if the threshold value by the grouping method in the ECU 3 is changed according to the distance resolution, it is grouped into one group Gb1 as shown in FIG.

  With reference to FIG. 1, the operation | movement in the obstruction detection apparatus 1 is demonstrated. In particular, the processing in the ECU 3 will be described along the flowchart of FIG. FIG. 4 is a flowchart showing the flow of processing in the ECU of FIG.

  The laser radar 2 emits a laser beam at a predetermined angle in the left-right direction and receives the reflected light at regular time intervals. The laser radar 2 calculates information about each detection point and transmits a radar signal to the ECU 3.

  Every time a radar signal is received (every fixed time), the ECU 3 acquires information on detection points (S1). Then, the ECU 3 prepares the same number of label arrays as the acquired detection points, and initializes the label arrays (S2).

  The ECU 3 sequentially extracts combinations of two detection points from the acquired detection points. The ECU 3 calculates the distance between the detection points based on the positions of the two detection points (S3). Further, the ECU 3 calculates the distance resolution at each position of the two detection points, and sets a threshold according to the larger distance resolution (S4). Then, the ECU 3 determines whether or not the distance between the detection points is less than the threshold value. If the distance is less than the threshold value, the same number of labels is assigned to the two detection points (S5).

  The ECU 3 determines whether or not the processing for all combinations of the two detection points has been completed (S6). If it is determined in S6 that the processing for all combinations has not been completed, the ECU 3 returns to S3, extracts the next two detection point combinations, and performs processing for this combination.

  If it is determined in S6 that the processing for all combinations has been completed, the ECU 3 assigns a label with a new number to each detection point to which no label is assigned (S7). Then, the ECU 3 groups the detection points according to the label number (S8). Further, the ECU 3 calculates obstacle information for each group based on the information on the detection points included in each group (S9). Then, the ECU 3 transmits the obstacle information as an obstacle information signal to the driving support device.

  According to this obstacle detection apparatus 1, by dynamically changing the grouping threshold according to the larger distance resolution of the distance resolutions of the laser radar 2 at each position of the two detection points to be grouped, It is possible to determine with high accuracy whether or not the two detection points may be in the same group. As a result, appropriate grouping can be performed and obstacles can be detected with high accuracy.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, in the present embodiment, the present invention is applied to an obstacle detection device mounted on a vehicle. In addition to obstacles around the vehicle, various objects can be detected as detection targets according to the usage of the object detection device. In addition to the vehicle, the vehicle can be mounted on other objects such as a robot.

  In this embodiment, a laser radar is used as the radar detection means, but other radars such as a millimeter wave radar may be used.

It is a block diagram of the obstruction detection apparatus which concerns on this Embodiment. It is explanatory drawing of the grouping method in ECU of FIG. It is an example of the result of grouping, (a) is a result by the conventional grouping method, (b) is a result by the grouping method in ECU of FIG. It is a flowchart which shows the flow of the process in ECU of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Obstacle detection apparatus, 2 ... Laser radar, 3 ... ECU

Claims (1)

Radar detecting means for detecting the position of the object;
Distance calculating means for calculating a distance between two detection points detected by the radar detecting means;
Threshold setting means for setting a larger grouping threshold value as the distance resolution increases, based on the larger distance resolution of the radar detection means at each position of the two detection points used in the distance calculation means. When,
When the distance between the two detection points calculated by the distance calculation means is less than the threshold value set by the threshold setting means, the two detection points are grouped into the same group, thereby the radar detection means. Grouping means for grouping each detected point detected in
An object detection device comprising: an object detection unit that detects an object using a detection point included in the group for each group grouped by the grouping unit.

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