JP2006292681A - Object detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an object detection apparatus capable of highly accurately detecting objects. <P>SOLUTION: The object detection apparatus 1 for detecting objects on the basis of both information by a radar and information by images is provided with a radar detection means 2 for detecting objects by the radar; an image detection means 3 for detecting objects by images; and a determination means 10 for determining whether an object detected by the radar detection means 2 and an object detected by the image detection means 3 are one and the same object or not on the basis of both position information of the object detected by the radar detection means 2 and the position information of the object detected by the image detection means 3. In the case that a plurality of objects detected by the radar detection means 2 correspond to an object detected by the image detection means 3, the determination means 10 determines that an object close to an estimated track of travel of the center of a vehicle among the plurality of objects is one and the same object. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an object detection apparatus that detects an object based on information from a radar and information from an image.

In recent years, driving support devices such as a collision reducing device, an inter-vehicle distance control device, and a following traveling device have been developed. In these driving assistance devices, it is important to detect a vehicle traveling in front of the host vehicle. In order to improve the detection accuracy, the object detection apparatus includes an apparatus including two detection means, that is, a detection means using a radar such as a millimeter wave radar and a detection means using an image such as a stereo camera. In the object detection apparatus including these two detection means, the radar detection object detected based on the information from the radar and the image detection object detected based on the information from the image are collated, and the radar detection object and the image detection object are detected. It is determined whether or not they are the same object, and the object determined to be the same is set as an object to be detected such as a preceding vehicle (see Patent Document 1).
JP 2004-117071 A

  In the conventional collation method, if there are multiple radar detection objects similar to one image detection object as a result of the collation, the radar detection object having the highest similarity is determined as the same object. May be determined as the same object. Therefore, even if the radar detection object and the image detection object are different objects, there is a possibility that they are determined to be the same object.

  For example, when the object to be detected is a front vehicle, in object detection based on image information, if a part of the front vehicle is shaded, the front vehicle is divided and detected, and the road side (left side) end of the front vehicle is detected. May be used as an image detection object. In this case, if an object detection based on radar information detects a motorcycle or a roadside pole (a sign, etc.) running parallel to the preceding vehicle as a radar detection object in addition to the preceding vehicle, each radar detection object and the preceding vehicle are detected. In comparison with the image detection object at the road side end, there is a possibility that the motorcycle or the radar detection object of the road side pole close to the image detection object at the road side end of the preceding vehicle is determined as the same object.

  Therefore, an object of the present invention is to provide an object detection device that detects an object with high accuracy.

  An object detection apparatus according to the present invention includes a radar detection means for detecting an object by radar, an image detection means for detecting an object by an image, position information of the object detected by the radar detection means, and an object detected by the image detection means. And determining means for determining whether or not the object detected by the radar detecting means and the object detected by the image detecting means are the same object based on the position information, the determining means for the object detected by the image detecting means When a plurality of objects detected by the radar detection means correspond to each other, an object close to the estimated traveling locus at the center of the vehicle among the plurality of objects is determined as the same object.

  In this object detection apparatus, an object is detected based on radar information from the radar detection means, and position information obtained from the radar information is acquired for the detected object. Further, the object detection device detects an object based on image information obtained by the image detection means, and acquires position information obtained from the image information for the detected object. In the object detection apparatus, the determination unit determines whether the detection objects detected by the detection units are the same object based on the position information of the detection object detected by the radar detection unit and the position information of the detection object detected by the image detection unit. At this time, if a plurality of detection objects by the radar detection means correspond to a detection object by the image detection means (that is, if there are a plurality of radar detection objects having similarity to the image detection object) The means compares the distances of the plurality of detected objects from the estimated traveling locus at the center of the vehicle, and determines that the radar detected object closest to the estimated traveling locus is the same object as the image detected object. As described above, the object detection means considers not only the position information of each detection object but also the distance from the traveling locus of the vehicle center of the detection object detected by the radar detection means. Therefore, in the object detection means, when there are a plurality of detection objects by the radar detection means similar to the detection object by the image detection means, an object (for example, an object closer to the traveling locus of the host vehicle than the object located on the road side) Vehicle) can be determined as the same object. As a result, the object detection apparatus can detect an object closer to the traveling locus at the center of the host vehicle with high accuracy. For example, a roadside part of a forward vehicle traveling in the lane is detected as a detection object by the image detection means, and the forward vehicle (position information in the vehicle width direction is near the center of the lane as a detection object by the radar detection means. ) And a motorcycle running in parallel with the vehicle ahead of it (position information in the vehicle width direction is near the left end of the lane), it is close to the center line of the lane of the two detected objects by the radar detection means It is possible to determine that the detection object of the preceding vehicle (the detection object closer to the traveling locus at the center of the host vehicle) is the same object as the detection object by the image detection means.

  The object detection apparatus according to the present invention may be configured to include estimation means for estimating a traveling locus at the center of the vehicle.

  In this object detection apparatus, the traveling locus at the center of the vehicle is estimated by the estimating means. Then, when a plurality of detection objects by the radar detection means correspond to the detection objects by the image detection means, the determination means uses a plurality of information based on the estimated traveling locus and position information of each detection object by the radar detection means. For each detected object, the distance from the estimated traveling locus at the center of the vehicle is obtained, and based on each distance, it is determined whether or not the object detected by the image detecting means is the same object. As described above, the object detection apparatus can detect the object with higher accuracy by using the traveling locus of the vehicle center with high accuracy actually obtained.

  According to the present invention, it is possible to detect an object closer to the traveling locus of the vehicle center with high accuracy.

  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 a collision mitigation device mounted on a vehicle. The collision mitigation apparatus according to the present embodiment detects a forward vehicle as a detection target and performs various controls to prevent / reduce a collision with the forward vehicle. In particular, the collision mitigation apparatus according to the present embodiment includes two sensors, a millimeter wave radar and a stereo camera, for detecting a vehicle ahead, and collates a detection object by the millimeter wave radar with a detection object by the stereo camera. To detect the vehicle ahead. In this embodiment, there are two forms depending on the difference in the collation processing. The first embodiment is a form in which the tracking process for the detected object is not performed for each sensor, and the second embodiment is for each sensor. This is a form for performing tracking processing on a detected object.

  With reference to FIGS. 1-7, the collision mitigation apparatus 1 which concerns on 1st Embodiment is demonstrated. FIG. 1 is a configuration diagram of a collision mitigation device according to the present embodiment. FIG. 2 is an explanatory diagram of a radar target, a stereo image target, and a fusion target according to the present embodiment. FIG. 3 is an explanatory diagram of a collation method between the previous fusion target and the radar target according to the first embodiment. FIG. 4 is an explanatory diagram of a collation method between the previous fusion target and the stereo image target according to the first embodiment. FIG. 5 is an explanatory diagram of a method for collating a radar target and a stereo image target according to the present embodiment. FIG. 6 is an explanatory diagram of a collation method between a radar target and a stereo image target when there are two radar targets similar to the stereo image target according to the present embodiment. FIG. 7 is an explanatory diagram of a method for calculating the distance between the radar target and the center line of the lane according to this embodiment, where (a) is a case where the road curve R> 0, and (b) is the road. This is the case of the curve R <0.

  The collision mitigation device 1 detects a vehicle ahead and performs brake control, suspension control, seat belt control, and alarm control according to the possibility of collision when a front object is detected. The collision mitigation apparatus 1 sets a radar target based on information from a millimeter wave radar and sets a stereo image target based on a stereo image from a stereo camera in order to detect a vehicle ahead. A fusion target (vehicle ahead) is set by collating with the image target. At this time, the collision mitigation apparatus 1 collates the radar target or stereo image target with the previous fusion target without tracking each of the radar target and the stereo image target. In particular, in the collision mitigation apparatus 1, when there are a plurality of radar targets that are similar to a single stereo target, the lane center line of each radar target (the center line of the lane is defined as the own vehicle). The distance from the center of the vehicle width direction is regarded as a travel locus). The collision mitigation apparatus 1 includes a millimeter wave radar 2, a stereo camera 3, a vehicle speed sensor 4, a yaw rate sensor 5, a brake ECU [Electronic Control Unit] 6, a suspension control actuator 7, a seat belt actuator 8, a buzzer 9, a collision mitigation ECU 10, and the like. These devices transmit and receive various signals by CAN [Controller Area Network] (standard interface standard for in-vehicle LAN) communication.

  In this embodiment, the millimeter wave radar 2 corresponds to the radar detection means described in the claims, the stereo camera 3 corresponds to the image detection means described in the claims, and the collision reduction ECU 10 is patented. This corresponds to the determination means described in the claims.

  First, each target will be described with reference to FIG. The radar target is an object detected based on information from the millimeter wave radar 2. In the radar target, the distance to the object that can be acquired from the radar information, the lateral position of the object, and the relative speed with the object are set. The stereo image target is an object detected based on a stereo image obtained by the stereo camera 3. For stereo image targets, the distance to the front end surface of the object that can be acquired from the stereo image, the horizontal position of the center of the front end surface of the object, the relative speed with the object, the width of the object (the length in the left-right direction with respect to the host vehicle) The depth of the object (the length in the direction away from the host vehicle), the height of the object, and the height position of the object are set. The fusion target is an object that has a high similarity in the collation between the radar target and the stereo image target, and can determine that the radar target and the stereo image target are the same object. In the fusion target, the distance and relative speed from the radar target and the horizontal position, width, depth, height, and height position from the stereo image target are set. Information on this fusion target is information about the vehicle ahead.

  The millimeter wave radar 2 is a radar for detecting an object using millimeter waves. The millimeter wave radar 2 is attached to the front center of the host vehicle. The millimeter wave radar 2 transmits the millimeter wave forward while scanning the millimeter wave in a horizontal plane, and receives the reflected millimeter wave. The millimeter wave radar 2 transmits the millimeter wave transmission / reception data to the collision mitigation ECU 10 as a radar signal.

  The stereo camera 3 is composed of two CCD cameras, and the two CCD cameras are arranged at a predetermined interval in the horizontal direction. The stereo camera 3 is also attached to the front center of the host vehicle. The stereo camera 3 transmits left and right stereo image data captured by the two CCD cameras to the collision reduction ECU 10 as image signals.

  The vehicle speed sensor 4 is a sensor that detects the speed of the vehicle. The vehicle speed sensor 4 transmits the detected value to the collision reduction ECU 10 as a vehicle speed signal. The yaw rate sensor 5 is a sensor that detects the yaw rate of the vehicle. The yaw rate sensor 5 transmits the detected value to the collision reduction ECU 10 as a yaw rate signal.

  The brake ECU 6 is an ECU that adjusts the hydraulic pressure of each wheel cylinder of the four wheels and controls the braking force of the four wheels. The brake ECU 6 sets a hydraulic control signal based on the target brake force of each wheel, and transmits each hydraulic control signal to a brake control actuator that changes the hydraulic pressure of each wheel cylinder. In particular, when the brake ECU 6 receives a target brake force signal for each wheel from the collision reduction ECU 10, the brake ECU 6 sets a hydraulic control signal based on the target brake force indicated by the target brake force signal. Incidentally, when receiving the hydraulic control signal, the brake control actuator changes the hydraulic pressure of the wheel cylinder based on the target hydraulic pressure indicated by the hydraulic control signal.

  The suspension control actuator 7 is an actuator that changes the hydraulic pressure of each hydraulic active suspension of the four wheels. When the suspension control actuator 7 receives the target damping force signal for each wheel from the collision reduction ECU 10, the suspension control actuator 7 sets the target hydraulic pressure based on the target damping force indicated by each target damping force signal, and the hydraulic active suspension based on the target hydraulic pressure. Change the oil pressure. Although only one suspension control actuator 7 is shown in FIG. 1, it is provided for each of the four wheel suspensions.

  The seat belt actuator 8 is an actuator that pulls in each seat belt and changes the restraining force by the seat belt. When the seat belt actuator 8 receives the target pull-in amount signal for each seat belt from the collision reduction ECU 10, the seat belt actuator 8 pulls in the seat belt according to the target pull-in amount indicated by each target pull-in amount signal. In FIG. 1, only one seat belt actuator 8 is illustrated, but each seat belt actuator 8 is provided for each seat belt.

  When the buzzer 9 receives an alarm signal from the collision mitigation ECU 10, it outputs a buzzer sound.

  The collision mitigation ECU 10 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 collision mitigation apparatus 1. The collision mitigation ECU 10 receives a radar signal from the millimeter wave radar 2, each image signal from the stereo camera 3, a vehicle speed signal from the vehicle speed sensor 4, and a yaw rate signal from the yaw rate sensor 5 at regular intervals based on the master clock of the CPU. Incorporate. Then, the collision mitigation ECU 10 performs a radar target setting process based on radar information and a stereo image target setting process based on the stereo image at regular intervals, and the previous fusion target, the current radar target, and the stereo image target. The collation process based on is performed, and the fusion target is set this time. Further, the collision mitigation ECU 10 performs a collision mitigation process based on the relationship between the current fusion target (front vehicle) and the host vehicle.

  The radar target setting process will be described. The collision reduction ECU 10 calculates the distance to the object ahead based on the time from when the millimeter wave is emitted to when it is received. Further, the collision reduction ECU 10 calculates a relative speed with respect to a front object. Further, the collision mitigation ECU 10 detects the direction of the millimeter wave that has been reflected most strongly among the reflected millimeter waves, and obtains the angle formed by the traveling direction of the host vehicle and the direction of the object from that direction, and from that angle Calculate the horizontal position. In the object detection by the millimeter wave radar 2, since the object is detected when the reflected millimeter wave is received, one radar target is obtained every time the reflected millimeter wave is received. Further, in the object detection by the millimeter wave radar 2, the distance to the object can be accurately detected, and thus the accuracy of the distance and the relative speed is particularly high.

  The stereo image target setting process will be described. The collision mitigation ECU 10 triangulateally identifies a front object by using the difference in the appearance of the object in the left and right stereo images, and determines the position from the stereo camera 3 to the object (distance to the front end surface of the object). The horizontal position of the front end surface of the object, the height position of the object) are calculated, and the three-dimensional size (horizontal width, depth, height) of the object is calculated. Further, the collision reduction ECU 10 calculates a relative speed with respect to a front object. In the object detection by the stereo camera 3, the object is detected when the object can be specified from the left and right stereo images, so that one stereo image target is obtained each time the object is specified. Further, in the object detection by the stereo camera 3, since the object can be detected three-dimensionally, information on the size of the object can be acquired.

  The verification process will be described. First, the collision reduction ECU 10 collates the previous fusion target and the current radar target at regular time intervals. Specifically, as shown in FIG. 3, the collision mitigation ECU 10 sets a distance threshold and a lateral position threshold around the position (distance, lateral position) of the previous fusion target LF (as indicated by the broken line in FIG. 3). The relative velocity threshold is set with the relative velocity of the previous fusion target LF as the median value. Then, the collision mitigation ECU 10 determines whether or not the position (distance, lateral position) of the current radar target TL is within the distance threshold and the lateral position threshold with the position of the previous fusion target LF as the center. At the same time, it is determined whether or not the relative speed of the radar target TL is within the relative speed threshold value. The collision mitigation ECU 10 determines that the current radar target TL is similar to the previous fusion target LF when it is within all the thresholds in this determination, and if even one is not within the threshold. It is determined that there is no similarity. In this collation, collation is performed in consideration of position information held by the radar target with the previous fusion target in which highly accurate information is set as the center.

  In addition, the collision reduction ECU 10 collates the previous fusion target with the current stereo image target at regular time intervals. Specifically, as shown in FIG. 4, the collision mitigation ECU 10 sets the distance threshold value, the horizontal position threshold value, and the height position value around the position (distance, horizontal position, height position) of the previous fusion target LF. In addition to setting a threshold value, a threshold value for the depth of the object, a threshold value for the width of the object, and a threshold value for the height of the object (see the three-dimensional area indicated by the broken line in FIG. 4), and the relative speed of the previous fusion target LF as the median value Set the relative speed threshold. In the collision mitigation ECU 10, the position (distance, lateral position, height) of the current stereo image target TI is within the threshold of the distance centered on the position of the previous fusion target LF, and within the threshold of the lateral position and the height position. Whether or not the size (depth, width, height) of the current stereo image target TI is within the depth threshold, the width threshold, and the height threshold. At the same time, it is determined whether or not the relative speed of the stereo image target TI is within the relative speed threshold value. Then, the collision reduction ECU 10 determines that the current stereo image target TI is similar to the previous fusion target LF when it is within all the thresholds in this determination, and even one of them is not within the threshold. It is determined that there is no similarity in the case. In this collation, collation is performed in consideration of the size information of the three-dimensional object with respect to the position information held by the stereo image target with the previous fusion target in which highly accurate information is set as the center.

  When there are a current radar target and a current stereo image target similar to the previous fusion target, the collision reduction ECU 10 compares the current radar target with the current stereo image target. Specifically, as shown in FIG. 5, the collision mitigation ECU 10 sets a distance threshold value and a horizontal position threshold value around the position (distance, horizontal position) of the current radar target TL, and also sets a depth threshold value of the object. Then, the threshold value of the horizontal width of the object is set (see the plane area indicated by the broken line in FIG. 5), and the relative speed threshold value is set with the relative speed of the current radar target TL as the median value. Then, the collision reduction ECU 10 determines whether or not the position (distance, lateral position) of the current stereo image target TI is within the distance threshold and the lateral position threshold with the position of the current radar target TL as the center. It is determined whether or not the size (depth, width) of the stereo image target TI is within the depth threshold and the width threshold, and the relative speed of the stereo image target TI is within the relative speed threshold. It is determined whether or not. Then, the collision mitigation ECU 10 determines that the current radar target TL and the current stereo image target TI are similar if they are within all the thresholds in this determination, and even one of them is within the threshold. If not, it is determined that there is no similarity. When it is determined that there is similarity, the collision reduction ECU 10 stores the combination of the current radar target TL and the current stereo image target TI. On the other hand, if it is determined that there is no similarity, the collision reduction ECU 10 deletes the previous fusion target. In this collation, the distance accuracy is high, the current radar target with the horizontal position at the center of the object is the center, and the stereo image target has the position information held by the radar target and the stereo image target. Matches in consideration of size information.

  When there are a plurality of radar targets, one stereo image target and a plurality of radar targets may have similarities. In particular, when only a part of the front vehicle is detected as a stereo image target due to a part of the front vehicle being shaded or the like (when the size information of the stereo image target is smaller than the size of the vehicle) ), There is a possibility that a stereo image target composed of a part of the preceding vehicle will satisfy each threshold condition centered on each of the plurality of radar targets. For example, as shown in FIG. 6, when the left end portion of the preceding vehicle is detected as the stereo image target TI, the size information of the stereo image target TI is small, so the object located at the left end portion in the lane The stereo image target TI satisfies all the threshold conditions centered on the radar target TL1 that detected the object, and each threshold condition centered on the radar target TL2 detected the object located near the center in the lane Are satisfied by the stereo image target TI, and one stereo image target TI is determined to be similar to the two radar targets TL1 and TL2. In this case, the radar target that can be determined to be the same object as the stereo image target TI needs to be narrowed down to one from the plurality of radar targets TL1 and TL2.

  When the subject of detection when the host vehicle is traveling is a forward vehicle, it is highly likely that the forward vehicle is traveling near the estimated traveling locus at the center of the host vehicle in the vehicle width direction. Therefore, when there are a plurality of radar targets, a radar target that is close to the estimated traveling locus in the center in the vehicle width direction of the host vehicle is selected from the plurality of radar targets. In this case, since the vehicle is likely to travel in the center of the lane, the estimated travel locus at the center in the vehicle width direction of the host vehicle can be regarded as the center of the lane in which the host vehicle is traveling. it can.

  Since the detection target is a forward vehicle and the vehicle is more likely to travel near the center than near the end of the lane, it can be estimated that the center in the vehicle width direction of the vehicle is closer to the center than the end of the lane. In the object detection by the millimeter wave radar 2, there is a high possibility of detecting the vicinity of the center of the object as a lateral position. Therefore, the radar target closer to the center of the lane is more likely to be a vehicle. Therefore, in order to narrow down a plurality of radar targets to one radar target, the distance between the lateral position and the center line of the lane is obtained for each radar target, and the radar target having the shortest distance is selected. . In the case of the example shown in FIG. 6, since the radar target TL2 is closer to the center line LC of the lane, the radar target TL2 is selected, and the radar target TL2 and the stereo image target TI are determined to be the same object. .

  When collation for all combinations of all current radar targets and all current stereo image targets that are similar for any fusion target is completed, the collision mitigation ECU 10 causes the current radar target and the current stereo image object to be collated. It is determined whether there is one or a plurality of current radar targets that are determined to be similar to one stereo image target from a combination that is determined to be similar to the target and stored. . When it is determined that there is one similar radar target this time, the collision mitigation ECU 10 updates the arbitrary fusion target as the current fusion target, and uses the distance of the current radar target and the current fusion target as information. In addition to setting the relative speed, the horizontal position, width, depth, height, and height position of the current stereo image target are set.

  On the other hand, when it is determined that there are a plurality of similar radar targets this time, the collision reduction ECU 10 selects a current radar target that can be determined as the same object as the current stereo image target from the plurality of current radar targets. To do. Specifically, the collision reduction ECU 10 calculates the distance between the current radar target and the center line of the lane using the lateral position of the current radar target for each current radar target. Then, the collision reduction ECU 10 compares the distances from the center line of the lane for a plurality of current radar targets, and selects the current radar target having the shortest distance. Further, the collision mitigation ECU 10 updates the arbitrary fusion target as the current fusion target with the selected current radar target, and determines the distance and relative velocity of the selected current radar target as information on the current fusion target. At the same time, the horizontal position, width, depth, height, and height position of the stereo image target are set.

  With reference to FIG. 7, a method of calculating the distance X ′ between the radar target TL and the center line LC of the lane will be described. The collision mitigation ECU 10 calculates the distance between the radar target and the center line of the lane on the assumption that the estimated traveling locus of the center of the host vehicle in the vehicle width direction coincides with the center of the lane. First, the collision reduction ECU 10 determines whether or not the yaw rate Y based on the yaw rate signal is zero. When the yaw rate Y is 0 (that is, when the host vehicle is traveling straight), the collision reduction ECU 10 uses the absolute value of the lateral position X of the radar target as the distance X ′ between the radar target TL and the center line LC of the lane. Set as.

  On the other hand, when the yaw rate Y is not 0 (that is, when the host vehicle is turning along the road), the collision reduction ECU 10 uses Equation (1) to estimate the curve R of the currently traveling road. Then, the curve R is calculated using the vehicle speed V and the yaw rate Y based on the vehicle speed signal. When the curve R is larger than 0, the collision reduction ECU 10 uses the distance Z from the vehicle R to the radar target TL set to the curve R and the radar target TL according to the equation (2) to A distance XR in the vehicle width direction between the position and the front position of the radar target is calculated. Then, the collision mitigation ECU 10 uses the distance XR in the vehicle width direction and the lateral position X set in the radar target TL according to Equation (3) to calculate the distance X between the radar target TL and the center line LC of the lane. 'Is calculated. On the other hand, when the curve R is smaller than 0, the collision reduction ECU 10 uses the distance Z between the curve R and the radar target TL according to the equation (4), at the current position of the host vehicle and the position ahead of the radar target TL. The distance XR in the vehicle width direction is calculated. Then, the collision reduction ECU 10 calculates the distance X ′ between the radar target TL and the center line LC of the lane by using the distance XR in the vehicle width direction and the lateral position X according to the equation (5). Thus, the center line LC of the lane is processed as the estimated travel locus of the center of the host vehicle in the vehicle width direction.

  However, the yaw rate Y is set to a positive value when the vehicle turns right, and set to a negative value when the vehicle turns left. Accordingly, the curve R also has a positive value when the vehicle turns right and a negative value when the vehicle turns left. Further, the lateral position X is a positive value on the right side and a negative value on the left side when the lateral position of the host vehicle is 0. The absolute value of the curve R is required to be larger than the distance Z from the own vehicle to the radar target.

  When the current radar target and the current stereo image that are not similar to the updated current fusion target remain, the collision reduction ECU 10 determines whether the remaining current radar target and the current stereo image target are the same. Perform verification. This collation method is a collation method similar to the above-described current radar target and the current stereo image. In the collision mitigation ECU 10, if there is a current radar target and a current stereo image determined to be similar, a new fusion target is newly set, and each information of the current fusion target is set in the same manner as described above. . Also in this case, when there are a plurality of radar targets similar to one stereo image target, one radar target is selected from the plurality of radar targets by the same method as described above. Each information of the fusion target this time is set using the selected radar target.

  When there are a plurality of targets to be collated in each collation (for example, when there are a plurality of radar targets this time), collation is performed for all combinations. Each threshold value is set in advance in consideration of detection accuracy by the millimeter wave radar 2 and the stereo camera 3 and stored in the collision mitigation ECU 10. The distance threshold and the relative speed threshold may be variable in consideration of the vehicle speed of the host vehicle. Depth, width, and height represent the size of the object. Since the detection target is a vehicle, the threshold values of depth, width, and height are set based on the size of a general vehicle.

  In FIG. 8, a motorcycle traveling near the roadside is detected as a radar target TL1, a forward vehicle traveling in the center of the lane is detected as a radar target TL2, and the left end of the forward vehicle is a stereo image target. An example of a collation result when it is detected as TI is shown. Since the stereo image target TI is close to the two radar targets TL1 and TL2 and has narrow width information, it is determined that the stereo image target TI is similar to the two radar targets TL1 and TL2. At this time, when the distance from the center line of the radar target TL1 to the center line of the radar target TL2 is compared with the distance from the center line of the radar target TL2, the distance from the center line of the radar target TL2 is short. It is determined that the target TL2 is the same object as the stereo image target TI. Further, in FIG. 9, the pole standing on the road side is detected as the radar target TL1, the front vehicle traveling in the center of the lane is detected as the radar target TL2, and the left end of the front vehicle is the stereo image target. An example of a collation result when it is detected as TI is shown. Also in this case, as in the example of FIG. 8, the radar target TL2 is determined to be the same object as the stereo image target TI. Thus, even when a stereo image target is similar to a plurality of radar targets, the vehicle ahead is detected as an object to be detected by using the distance from the center line of the lane of each radar target. Does not detect objects that are far from the center line of the lane such as motorcycles and poles near the roadside. Incidentally, when the entire preceding vehicle is detected as the stereo image target TI, the width information of the stereo image target TI becomes wide, so that each threshold condition centering on the radar target TL1 is not satisfied, and the radar target is not satisfied. It is determined that there is no similarity with TL1.

  The collision mitigation process will be described. When there is a fusion target this time (that is, when there is a forward vehicle), the collision reduction ECU 10 considers the vehicle speed and is a stage of a possibility of a collision based on the distance information set for the fusion target this time ( For example, three stages of high possibility, low possibility, and none are set. The collision mitigation ECU 10 controls the brake ECU 6, the suspension control actuators 7,..., The seat belt actuators 8,.

  The case where there is a three-stage possibility of collision of this control will be described as an example. In a stage where there is no possibility of collision, the collision reduction ECU 10 does not control the brake ECU 6, the suspension control actuators 7,..., The seat belt actuators 8,.

  At the stage where the possibility of collision is low, the collision reduction ECU 10 does not control the brake ECU 6, the suspension control actuators 7,..., But controls the seat belt actuators 8,. Specifically, the collision reduction ECU 10 sets a target pull-in amount signal for slightly retracting the seat belt in order to notify that the vehicle is approaching ahead, and the target pull-in amount signal is set as the seat belt actuator 8. .. (To be transmitted only to the seat belt actuator 8 in the driver's seat). Further, the collision mitigation ECU 10 sets an alarm signal to notify that the vehicle is approaching ahead, and transmits the alarm signal to the buzzer 9.

  At a stage where the possibility of a collision is high, the collision reduction ECU 10 controls the brake ECU 6, the suspension control actuators 7,..., The seat belt actuators 8,. Specifically, the collision reduction ECU 10 sets a target brake force signal for decelerating the vehicle, and transmits the target brake force signal to the brake ECU 6. Further, the collision mitigation ECU 10 sets a target damping force signal for preventing the vehicle from tilting (so that the front portion does not sink), and sends the target damping force signal to the suspension control actuators 7. Send. Further, the collision reduction ECU 10 sets a target pull-in amount signal for strongly restraining the occupant, and transmits the target pull-in amount signal to the seat belt actuators 8. Further, the collision mitigation ECU 10 sets an alarm signal to notify that the vehicle is approaching ahead, and transmits the alarm signal to the buzzer 9.

  In addition to the possibility of a collision, the amount of overlap with the vehicle ahead is also determined, and the brake ECU 6, suspension control actuator 7,..., Seat belt actuator 8,. The buzzer 9 may be controlled.

  With reference to FIGS. 1-7, the operation | movement in the collision mitigation apparatus 1 is demonstrated. In particular, the flow of collation processing in the collision mitigation ECU 10 will be described with reference to the flowchart of FIG. FIG. 10 is a flowchart showing a flow of collation processing according to the first embodiment.

  The millimeter wave radar 2 transmits the millimeter wave forward and receives the reflected millimeter wave, and transmits the transmission / reception data as a radar signal to the collision mitigation ECU 10. The stereo camera 3 images the front and transmits the captured left and right stereo images to the collision reduction ECU 10 as image signals. The vehicle speed sensor 4 detects the vehicle speed of the host vehicle, and transmits the detected value to the collision reduction ECU 10 as a vehicle speed signal. The yaw rate sensor 5 detects the yaw rate of the host vehicle, and transmits the detected value to the collision reduction ECU 10 as a yaw rate signal.

  The collision mitigation ECU 10 receives a radar signal from the millimeter wave radar 2 and receives each image signal from the stereo camera 3. Then, the collision mitigation ECU 10 sets a radar target based on radar information based on radar signals at regular time intervals. Also. The collision reduction ECU 10 sets a stereo image target based on the left and right stereo images of each image signal at regular intervals.

  Then, the collision reduction ECU 10 performs the following verification process at regular intervals. The collision mitigation ECU 10 collates the previous fusion target and the radar target based on the distance, the position information of the lateral position, and the relative speed (S10). Further, the collision mitigation ECU 10 collates the previous fusion target with the stereo image target based on the position information of the distance, the horizontal position, the height position, the depth, the width, the height information, and the relative speed (S11). ). Then, when there are a radar target and a stereo image target similar to the previous fusion target, the collision reduction ECU 10 uses the distance, the position information of the lateral position, the depth, the size information of the lateral width, and the relative speed, The radar target is compared with the stereo image target (S12).

  The collision reduction ECU 10 determines whether there is similarity in the collation in S12 (S13). If it is determined that there is similarity in S13, the collision reduction ECU 10 determines whether there are two or more radar targets that are similar to the stereo image target (S14). If it is determined in S14 that there are two or more, the collision reduction ECU 10 calculates the distance from the center line of the lane to the radar target for each radar target, and the center of the lane for two or more radar targets. Compare each distance from the line. The collision mitigation ECU 10 selects the radar target with the shortest distance, updates the previous fusion target to the current fusion target with the stereo image target similar to the selected radar target, and At this time, the distance and relative speed of the selected radar target are set as fusion target information, and the horizontal position, width, depth, height, and height position of the stereo image target are set (S15). At this time, the similar radar target and stereo image target are deleted. On the other hand, if it is determined in S14 that there is one, the collision reduction ECU 10 updates the previous fusion target to the current fusion target using the radar target and the stereo image target that are similar one-to-one. Then, the distance and relative speed of the radar target are set as information on the fusion target this time, and the horizontal position, width, depth, height, and height position of the stereo image target are set (S16). At this time, the similar radar target and stereo image target are deleted. On the other hand, if it is determined in S13 that there is no similarity, the collision reduction ECU 10 deletes the previous fusion target that has been collated (S17). The processing from S10 to S17 is performed for all combinations of all previous fusion targets, all radar targets, and all stereo image targets. By the processing so far, the tracking for the previous fusion target is completed.

  When the radar target and the stereo image target remain, the collision reduction ECU 10 compares the radar target with the stereo image target based on the distance, the position information of the lateral position, the depth, the size information of the width, and the relative speed. (S18).

  The collision reduction ECU 10 determines whether there is similarity in the collation in S18 (S19). If it is determined in S19 that there is similarity, the collision reduction ECU 10 determines whether there are two or more radar targets that are similar to the stereo image target (S20). When it is determined that there are two or more in S20, the collision reduction ECU 10 calculates the distance from the center line of the lane to the radar target for each radar target, and the center of the lane for two or more radar targets. Compare each distance from the line. Then, the collision mitigation ECU 10 selects the radar target having the shortest distance, sets the current fusion target with the stereo image target similar to the selected radar target, and sets the current fusion target. The distance and relative speed of the selected radar target are set as information, and the horizontal position, width, depth, height, and height position of the stereo image target are set (S21). On the other hand, if it is determined in S20 that there is one, the collision mitigation ECU 10 sets the current fusion target by using the radar target and the stereo image target that are similar one-to-one, and the current fusion. The distance and relative speed of the radar target are set as target information, and the horizontal position, width, depth, height, and height position of the stereo image target are set (S22). The processing from S18 to S22 is performed for all combinations of all remaining radar targets and all stereo image targets. By the processing so far, the collation processing of all radar targets and all stereo image targets is completed.

  When the previous fusion target has not been set, the collision reduction ECU 10 performs the matching process from the process of S18 without performing the processes of S10 to S17. If no radar target or stereo image target remains after the current fusion target is updated, the collision reduction ECU 10 ends the current collation process without performing the processes of S18 to S22. In addition, when at least one of the radar target and the stereo image target is not set, the current matching process is not performed.

  When the current fusion target is set by the collation process, the collision reduction ECU 10 sets the stage of possibility of collision based on the information set in the fusion target, and according to the stage of possibility of collision The brake ECU 6, the suspension control actuator 7,..., The seat belt actuator 8,. With this control, when the possibility of a collision with the preceding vehicle is low, the driver recognizes the approach of the preceding vehicle by the seat belt retracting by the seat belt actuators 8... And the buzzer 9 outputting the buzzer sound. Furthermore, when the possibility of a collision with the vehicle ahead increases, the brake ECU 6 decelerates by automatic braking force and the suspension hardness is adjusted by the suspension control actuators 7..., And the seat belt actuators 8. The occupant is strongly restrained by further retracting the belt, and the driver is made to recognize further approach of the vehicle ahead by the output of the buzzer sound by the buzzer 9. On the other hand, when the current fusion target is not set by the collation process, the collision reduction ECU 10 does not perform the current collision reduction process.

  According to this collision mitigation apparatus 1, when there are a plurality of radar targets having similarity to a stereo image target, the distances from the center line of the lane of the plurality of radar targets are compared, A radar target that can be determined to be the same object as the stereo image target can be selected, and the vehicle ahead can be detected with high accuracy. In particular, in the collision mitigation apparatus 1, when calculating the distance from the center line of the lane of the radar target, it is calculated on the assumption that the traveling track of the center of the lane coincides with the center of the vehicle in the vehicle width direction. Therefore, no means for estimating the center line of the lane is required, and the configuration can be simplified.

  Furthermore, according to this collision mitigation apparatus 1, since collation is performed using size information in addition to position information, collation can be performed in consideration of the size of the vehicle to be detected. Can be detected. Furthermore, according to the collision mitigation apparatus 1, since the collation is performed using the relative speed, the vehicle that is a moving body can be detected with higher accuracy.

  A collision mitigation device 21 according to a second embodiment will be described with reference to FIGS. 1, 2, and 5 to 7. In the collision mitigation device 21, the same components as those in the collision mitigation device 1 according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The collision mitigation device 21 differs from the collision mitigation device 1 in radar target setting processing, stereo image target setting processing, and collation processing. That is, the collision mitigation apparatus 21 tracks each of the radar target and the stereo image target, and does not collate the radar target or the stereo image target with the previous fusion target. Therefore, the collision mitigation device 21 differs from the collision mitigation device 1 only in the process of the collision mitigation ECU, and includes a collision mitigation ECU 30 instead of the collision mitigation ECU 10 according to the first embodiment. In the second embodiment, the collision reduction ECU 30 corresponds to a determination unit described in the claims.

  The collision mitigation ECU 30 is also an electronic control unit that performs overall control of the collision mitigation device 21 in the same manner as the collision mitigation ECU 10 according to the first embodiment. The collision reduction ECU 30 is different from the collision reduction ECU 10 in radar target setting processing, stereo image target setting processing, and collation processing. Therefore, only each process will be described.

  The radar target setting process will be described. Similar to the first embodiment, the collision reduction ECU 30 obtains a radar target from the radar information at regular intervals. Further, the collision mitigation ECU 30 collates the previous radar target and the obtained radar target at regular time intervals. This collation is a collation method similar to the collation method between the previous fusion target and the current radar target in the first embodiment, and collation is performed based on distance, lateral position, and relative speed. At this time, each threshold value is set around the previous radar target instead of the previous fusion target, and it is determined whether or not the radar target is within the threshold value. When the collision reduction ECU 30 determines that there is similarity in the collation, the previous radar target is updated as the current radar target, and the current information is set. On the other hand, when the collision reduction ECU 30 determines that there is no similarity in the collation, the previous radar target is deleted. The collision reduction ECU 30 newly sets a radar target that has no similarity to the previous radar target as the current radar target.

  The stereo image target setting process will be described. Similar to the first embodiment, the collision reduction ECU 30 obtains a stereo image target from a stereo image at regular intervals. Further, the collision reduction ECU 30 collates the previous stereo image with the obtained stereo image target at regular time intervals. This collation is a collation method similar to the collation method of the previous fusion target and the current stereo image target in the first embodiment, and the distance, horizontal position, height position, depth, width, height, relative Check by speed. At this time, each threshold value is set around the previous stereo image target instead of the previous fusion target, and it is determined whether or not the stereo image target is included in each threshold value. When the collision reduction ECU 30 determines that there is similarity in the collation, the previous stereo image target is updated as the current stereo image target, and the current information is set. On the other hand, when the collision reduction ECU 30 determines that there is no similarity in the collation, the previous stereo image target is deleted. Further, the collision reduction ECU 30 newly sets a stereo image target that has no similarity to the previous stereo image target as the current stereo image target.

  The collision reduction ECU 30 assigns a recognition number to each object recognized as a target by detection by each sensor, and determines whether tracking is performed using the recognition number.

  The verification process will be described. The collision reduction ECU 30 collates the current radar target with the current stereo image target at regular time intervals. This collation is a collation method similar to the collation method of the remaining current radar target and the current stereo image target in the first embodiment, and collation is performed by distance, lateral position, depth, lateral width, and relative speed. . When there are a plurality of targets to be collated in the collation (for example, when there are a plurality of radar targets this time), collation is performed for all combinations.

  The operation of the collision mitigation device 21 will be described with reference to FIGS. 1, 2, and 5 to 7. In particular, the flow of collation processing in the collision reduction ECU 30 will be described with reference to the flowchart of FIG. FIG. 11 is a flowchart showing the flow of the collation process according to the second embodiment. Here, only the radar target setting process, the stereo image target setting process, and the collation process in the collision reduction ECU 30 different from the operation in the collision reduction apparatus 1 will be described.

  The collision reduction ECU 30 receives a radar signal from the millimeter wave radar 2 and receives each image signal from the stereo camera 3.

  Then, the collision reduction ECU 30 acquires a radar target based on the radar information based on the radar signal at regular time intervals. Then, the collision reduction ECU 30 collates the acquired radar target with the previous radar target in order to track the previous radar target at regular intervals. As a result of the collation, the collision reduction ECU 30 updates the previous radar target having similarity as the current radar target, sets the current information, and deletes the previous radar target having no similarity. Further, the collision reduction ECU 30 newly sets a radar target that has no similarity among the acquired radar targets as the current radar target. When the radar target has not been set last time, the collision reduction ECU 30 sets all the acquired radar targets as the current radar target.

  In addition, the collision reduction ECU 30 acquires a stereo image target based on the left and right stereo images of each image signal at regular time intervals. Then, the collision reduction ECU 30 collates the acquired stereo image target with the previous stereo image target in order to track the previous stereo image target at regular intervals. As a result of the collation, the collision reduction ECU 30 updates the previous stereo image target having similarity as the current stereo image target, sets the current information, and deletes the previous stereo image target having no similarity. . Further, the collision reduction ECU 30 newly sets a stereo image target having no similarity among the acquired stereo image targets as the current stereo image target. If the previous stereo image target has not been set, the collision reduction ECU 30 sets all the acquired stereo image targets as the current stereo image target.

  Then, the collision reduction ECU 30 performs the following verification process at regular intervals. The collision reduction ECU 30 collates the radar target with the stereo image target based on the distance, the position information of the lateral position, the depth, the width information, and the relative speed (S30).

  The collision reduction ECU 30 determines whether there is similarity in the collation in S30 (S31). If it is determined that there is similarity in S31, the collision reduction ECU 30 determines whether there are two or more radar targets having similarity to the stereo image target (S32). When it is determined in S32 that there are two or more, the collision reduction ECU 30 calculates the distance from the center line of the lane to the radar target for each radar target, and the center of the lane for two or more radar targets. Compare each distance from the line. Then, the collision reduction ECU 30 selects the radar target with the shortest distance, sets the current fusion target with the stereo image target similar to the selected radar target, and sets the current fusion target. The distance and relative speed of the selected radar target are set as information, and the horizontal position, width, depth, height, and height position of the stereo image target are set (S33). On the other hand, if it is determined in S32 that there is one, the collision mitigation ECU 30 sets the current fusion target by using the radar target and the stereo image target that have a one-to-one similarity, and the current fusion. The distance and relative speed of the radar target are set as target information, and the horizontal position, width, depth, height, and height position of the stereo image target are set (S34). The processes of S30 to S34 are performed for all combinations of all radar targets and all stereo image targets. By the processing so far, the collation processing of all radar targets and all stereo image targets is completed. If at least one of the radar target and the stereo image target is not set, the current matching process is not performed.

  This collision mitigation device 21 also has the same effect as the collision mitigation device 1 according to the first embodiment.

  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 a collision mitigation device mounted on a vehicle. It can also be used as a single detection device. Further, as a detection target, it is also possible to detect other objects such as motorcycles and obstacles existing on the lane other than the vehicle ahead.

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

  In this embodiment, a stereo camera is used as the image detection unit. However, a camera other than the stereo camera may be used.

  In this embodiment, the configuration is such that the setting of the radar target based on the information by the millimeter wave radar and the setting of the stereo image target based on the stereo image by the stereo camera are performed by the collision mitigation ECU. The radar target may be set by a millimeter wave radar, or the stereo camera may be provided with an image processing unit, and the stereo image target may be set by the stereo camera.

  In the present embodiment, it is assumed that the center of the lane coincides with the traveling locus of the center of the host vehicle, and the distance from each lane center line of each radar target is obtained. A lane (for example, white lines on both sides) is detected using information such as an image, a center line of the lane is estimated by calculation, and each radar target is based on the estimated center line and position information of each radar target. The distance from the center line may be obtained. Road information such as car navigation may be used as a method for estimating the center line of the lane.

  In this embodiment, the radar target is determined to be close to the center of the lane with reference to the center line of the lane. However, the direction from the radar provided at the center in front of the vehicle is used as a reference. Thus, it may be determined whether or not the radar target is close to the estimated traveling locus in the center in the vehicle width direction, or from the road boundary of the lane on which the host vehicle is traveling or the boundary with the opposite lane It may be determined whether the radar target is close to the estimated traveling locus in the center in the vehicle width direction based on the distance from the section.

  In this embodiment, the collation is performed using the size information such as the width and depth and the relative speed. However, the collation may be performed without using the relative speed, or the size information It is good also as a structure which collates without using all or one part.

  Further, in the present embodiment, it is configured that it is determined that there is similarity when all threshold conditions are satisfied by determination by a plurality of threshold values in each collation, but some threshold conditions among all threshold conditions It is good also as a structure which determines with there being similarity, when satisfy | filling.

  In the second embodiment, the collision mitigation ECU uses a radar target tracking determination process based on information from a millimeter wave radar, a stereo image target tracking determination process based on a stereo image, and a radar target and a stereo image. Although it is configured to perform a collation process with a target, it is not necessary to perform all these processes in a collision reduction ECU, and a millimeter wave radar ECU for performing a radar target tracking determination process based on information by a millimeter wave radar An image ECU for performing a tracking determination process of a stereo image target based on a stereo image by a stereo camera may be provided separately from the collision reduction ECU. In this case, the target tracking determination processing is performed by the millimeter wave radar ECU and the image ECU, and the matching processing is performed by the collision reduction ECU. In such a configuration, it is suitable that the millimeter wave radar ECU is disposed between the millimeter wave radar and the collision mitigation ECU, and the image ECU is disposed between the stereo camera and the collision mitigation ECU.

It is a lineblock diagram of the collision mitigation device concerning this embodiment. It is explanatory drawing of the radar target concerning this Embodiment, a stereo image target, and a fusion target. It is explanatory drawing of the collation method with the last fusion target and radar target which concern on 1st Embodiment. It is explanatory drawing of the collation method with the last fusion target and stereo image target which concerns on 1st Embodiment. It is explanatory drawing of the collation method of the radar target and stereo image target which concerns on this Embodiment. It is explanatory drawing of the collation method of a radar target and a stereo image target in case the two radar targets which have similarity with the stereo image target concerning this Embodiment exist. It is explanatory drawing of the calculation method of the distance of the radar target concerning this Embodiment, and the centerline of a lane, (a) is a case where road curve R> 0, (b) is road curve R << This is the case of 0. It is an example of the collation result when there are two radar targets having similarity to the stereo image target. It is another example of the collation result when there are two radar targets having similarity to the stereo image target. It is a flowchart which shows the flow of the collation process which concerns on 1st Embodiment. It is a flowchart which shows the flow of the collation process which concerns on 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,21 ... Collision mitigation device, 2 ... Millimeter wave radar, 3 ... Stereo camera, 4 ... Vehicle speed sensor, 5 ... Yaw rate sensor, 6 ... Brake ECU, 7 ... Suspension control actuator, 8 ... Seat belt actuator, 9 ... Buzzer, 10, 30 ... Collision reduction ECU

Claims (2)

Radar detecting means for detecting an object by radar;
Image detection means for detecting an object from an image;
Whether the object detected by the radar detection means and the object detected by the image detection means are the same based on the position information of the object detected by the radar detection means and the position information of the object detected by the image detection means And a judging means for judging
In the case where a plurality of objects detected by the radar detection unit correspond to the object detected by the image detection unit, the determination unit selects an object close to the estimated traveling locus of the vehicle center among the plurality of objects. An object detection apparatus characterized in that it is determined as the same object.   The object detection apparatus according to claim 1, further comprising an estimation unit that estimates a travel locus at the center of the vehicle.

Images