JP5070713B2 - Object detection device - Google Patents

Description

  The present invention relates to an object detection apparatus including radar detection means for detecting an object by a radar, in particular, a high threshold object whose radar reflection intensity by the radar detection means is higher than a first threshold, and a radar reflection intensity that is the first threshold The present invention relates to an object detection device that detects a low threshold object that is lower than and lower than a second threshold.

  In recent years, driving support devices such as collision mitigation devices, inter-vehicle distance control devices, and tracking travel devices have been developed. In these driving assistance devices, it is important to detect an object existing in front of the host vehicle. The object detection device is a detection device that distinguishes a pedestrian and a vehicle by analyzing a reflected wave of the millimeter wave radar, and is a vehicle when it can be detected with a high threshold, and is a pedestrian when it can be detected with a low threshold. (For example, refer to Patent Document 1). That is, Patent Document 1 discloses a technique of having a low threshold value set to detect a target having a low reflection level compared to a normal threshold value set mainly to detect a vehicle. .

JP 2004-191131 A

  However, with the addition of a low threshold, the number of detected objects (target number) increases, but if all of them are output as detection results and set as processing targets, the calculation efficiency deteriorates. Therefore, the maximum number of objects to be output as a detection result is regulated so as not to exceed a predetermined value. However, in the conventional one, the point of specifically selecting the object to be processed is considered. Absent. In particular, since the number of target detections of the normal threshold millimeter wave target and the low threshold millimeter wave target always varies, there are the following problems. For example, if normal threshold millimeter wave targets detected based on the normal threshold are simply output as detection results in order, the low threshold millimeter wave target detected based on the low threshold may not be output at all. The detection sensitivity expansion effect that makes it possible to detect wave targets is halved. Conversely, for example, if the low threshold millimeter wave target detected based on the low threshold is simply output as the detection result in order, the normal threshold millimeter wave target detected based on the normal threshold may not be output at all. Even the detection performance of a conventional normal threshold millimeter wave target that uses only the normal threshold may not be ensured.

  The present invention has been made in view of the above, and it is possible to increase detection sensitivity and to ensure the reliability of object detection when detecting a high threshold object and a low threshold object using two thresholds having different levels. It is an object to provide an object detection device capable of performing

  In order to solve the above-described problems and achieve the object, an object detection apparatus according to the present invention includes radar detection means for detecting an object by radar, and the radar reflection intensity by the radar detection means is lower than a first threshold value. An object detection apparatus for detecting a high high threshold object and a low threshold object having a radar reflection intensity lower than the first threshold and higher than a second threshold, wherein the number of detected high threshold objects and the low threshold object number are low. The high threshold object candidate and the low threshold value are given priority in selection from the high threshold object candidate when the sum of the threshold object candidate number exceeds a predetermined maximum number of objects set to be outputable as a detection result. Selection means for assigning a selection process from object candidates and selecting a high threshold object and a low threshold object as a detection result is provided.

  In the object detection apparatus according to the present invention as set forth in the invention described above, the selection unit is configured to reduce the low threshold object candidate from the low threshold object candidate within a range not exceeding the predetermined maximum object number minus the selection number of the high threshold object. A threshold object is selected.

  The object detection device according to the present invention is the object detection device according to the above invention, wherein the selection means sets the high threshold object candidate to a high threshold within a range that does not exceed a predetermined priority selection number set smaller than the predetermined maximum object number. An object is preferentially selected.

  According to the object detection device of the present invention, when the sum of the detected number of high threshold object candidates and the number of low threshold object candidates exceeds a predetermined maximum number of objects that can be output as a detection result, the high threshold value Since the selection process from the high threshold object candidate and the low threshold object candidate is allocated so that the selection from the object candidate is given priority, the high threshold object and the low threshold object are selected as the detection results. Since the threshold object is always included and the detection sensitivity expansion effect using the second threshold can always be obtained, and the high threshold object is preferentially selected, the reliability of object detection using the first threshold There is an effect that the sex can be secured.

  Hereinafter, an embodiment of an object detection device according to the present invention will be described with reference to the drawings. The present embodiment shows an application example of the object detection device according to the present invention to a collision mitigation device mounted on a vehicle. The collision mitigation apparatus according to the present embodiment detects a front object and performs various controls to prevent / reduce a collision with the front object. In particular, the collision mitigation apparatus according to the present embodiment includes a millimeter wave radar for detecting a forward object, and detects the forward object based on a detection result by the millimeter wave radar.

  With reference to FIGS. 1-7, the collision mitigation apparatus 1 which concerns on this Embodiment is demonstrated. FIG. 1 is a configuration diagram of a collision mitigation apparatus 1 according to the present embodiment. The collision mitigation device 1 detects a front object, and when a front object is detected, performs brake control, suspension control, seat belt control, and alarm control according to the possibility of collision. The collision mitigation apparatus 1 sets a high threshold target and a low threshold target based on the detection result of radar reflection intensity by the millimeter wave radar in order to detect a forward object.

  Such a collision mitigation apparatus 1 includes a millimeter wave radar 2 corresponding to a radar detection means, a brake ECU (Electronic Control Unit) 4, a suspension control actuator 5, a seat belt actuator 6, a buzzer 7, a collision mitigation ECU 10, and the like. Transmits and receives various signals by CAN (Controller Area Network) (standard interface standard for in-vehicle LAN) communication.

  First, each target will be described. The high threshold target corresponding to the high threshold object uses a first threshold set mainly for the purpose of vehicle detection, so that the detection result of the radar reflection intensity by the millimeter wave radar 2 is higher than the first threshold. Is also a high object. For the low threshold target corresponding to the low threshold object, a second threshold (lower than the first threshold) set for the purpose of detecting an object other than the vehicle having a radar reflection intensity lower than that of the vehicle is used. Thus, the radar reflection intensity by the millimeter wave radar 2 is an object lower than the first threshold and higher than the second threshold.

  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 from the host vehicle while scanning the millimeter wave in a horizontal plane, and receives the reflected millimeter wave. Then, the millimeter wave radar 2 transmits the millimeter wave transmission / reception data to the collision mitigation ECU 10 as a radar signal. This transmission / reception data includes information on the transmitted millimeter wave, information on whether or not a reflected wave with respect to the transmitted millimeter wave has been received, and information on the radar reflection intensity when the reflected wave has been received.

  The brake ECU 4 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 4 sets a hydraulic control signal based on the target braking force of each wheel, and transmits each hydraulic signal to a brake control actuator that changes the hydraulic pressure of each wheel cylinder. In particular, when the brake ECU 4 receives a target brake force for each wheel from the collision mitigation ECU 10, the brake ECU 4 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 5 is an actuator that changes the hydraulic pressure of each hydraulic active suspension of the four wheels. When the suspension control actuator 5 receives the target damping force signal for each wheel from the collision mitigation ECU 10, the suspension control actuator 5 sets a 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 5 is shown in FIG. 1, it is provided for each of the four wheel suspensions.

  The seat belt actuator 6 is an actuator that pulls in each seat belt and changes the restraining force by the seat belt. When the seat belt actuator 6 receives the target pull-in amount signal for each seat belt from the collision reduction ECU 10, the seat belt actuator 6 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 6 is shown, but each is provided on the seat belt. Further, when the buzzer 7 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, a ROM, a RAM, and the like, and the CPU performs overall control of the collision mitigation apparatus 1 by executing a control program stored in the ROM. The collision reduction ECU 10 includes a high threshold target candidate selection unit 11, a low threshold target candidate selection unit 12, a target selection unit 13 as a selection unit, a collision prediction unit 14, a vehicle control unit 15, and the like. The collision mitigation ECU 10 takes in a radar signal from the millimeter wave radar 2 at regular intervals based on the master clock of the CPU, and at a certain interval, the high threshold target candidate selection unit 11 and the low threshold target candidates based on the radar information. High threshold target candidate and low threshold target candidate selection processing by the selection unit 12, high threshold target and low threshold target by the target selection unit 13 from the selected high threshold target candidate and low threshold target candidate Selective output processing is performed. As a result, the front object is detected, and the brake ECU 4, the suspension control actuator 5, and the seat belt actuator 6 according to the possibility of collision according to the type of whether the detected front object is a high threshold object or a low threshold object. The buzzer 7 is controlled.

  The high threshold target candidate selection unit 11 and the low threshold target candidate selection unit 12 will be described. The collision reduction ECU 10 calculates the distance to the object ahead based on the time from the emission to reception of the millimeter wave. In the object detection by the millimeter wave radar 2, an object is detected when the reflected millimeter wave can be received with a reception intensity equal to or higher than a predetermined threshold. Here, the high-threshold target candidate selection unit 11 uses the first threshold set in advance mainly for the purpose of detecting the vehicle, so that it can be received with a radar reflection intensity higher than the first threshold. This means that a high-threshold object has been detected, and one high-threshold target is detected each time the radar reflection intensity is received at the first threshold value or higher. Then, Hth_Num high threshold target candidates are selected from the detected own lane probability, relative speed, and distance information of the high threshold target. The number of high threshold target candidates to be selected is limited to a maximum of N_Hth, for example, eight.

  In addition, the low threshold target candidate selection unit 12 uses a second threshold that is set in advance mainly for the purpose of detecting an object other than a vehicle, so that it is lower than the first threshold and lower than the second threshold. A low-threshold object is detected when it can be received at a high radar reflection intensity, and one low-threshold object is received each time the radar reflection intensity is received at a level lower than the first threshold and higher than the second threshold. Detect the mark. Then, Lth_Num low threshold target candidates are selected from the own lane probability, relative speed, and distance information of the detected low threshold target. The number of low threshold target candidates to be selected is limited to a maximum of N_Lth, for example, eight.

  Next, the target selection unit 13 will be described. The target selection unit 13 is a range that does not exceed the maximum target number Nmax from the high threshold target candidate and the low threshold target candidate selected by the high threshold target candidate selection unit 11 and the low threshold target candidate selection unit 12. Thus, an appropriate number of high threshold targets and low threshold targets are selected as detection results and output to the collision prediction unit 14 and the like. Here, a predetermined maximum target number (maximum number of objects) Nmax that can be output as a detection result is set in advance, and in this embodiment, for example, Nmax = 8. The target selection unit 13 performs selection processing so that selection from the high threshold target candidate is prioritized when selecting from the high threshold target candidate and the low threshold target candidate. A predetermined priority selection number Npri for selection is also set in advance. The predetermined priority selection number Npri is a number such that 0 <Npri <maximum target number (maximum number of objects) Nmax. In the present embodiment, for example, Npri = 4 is set. The priority selection number Npri is not limited to four, but is preferably a number equal to or greater than ½ of the maximum target number Nmax.

  The target selection unit 13 gives priority to selection from the high threshold object candidate according to various conditions such as the maximum target number Nmax, the priority selection number Npri, the high threshold target candidate number Hth_Num, and the low threshold target candidate number Lth_Num. As described above, the selection process from the high threshold object candidate and the low threshold object candidate is allocated, and the high threshold object and the low threshold object are selected as the detection results.

  An example of selection processing by the target selection unit 13 according to various conditions will be described with reference to schematic diagrams shown in FIGS. First, when the sum of the number of high threshold target candidates Hth_Num and the number of low threshold target candidates Lth_Num is equal to or less than the maximum target number Nmax, all (Hth_Num + Lth_Num) high threshold target candidates and low threshold target candidates Select as high and low threshold targets.

  For example, FIG. 2 shows a case where Hth_Num = 3 high threshold target candidates and Lth_Num = 2 low threshold target candidates are detected as the forward target of the host vehicle. In this case, since (Hth_Num + Lth_Num) ≦ Nmax, Hth_Num = 3 high threshold target candidates and Lth_Num = 2 low threshold target candidates are all selected as the high threshold target and the low threshold target. In the figure, targets with parenthesized numbers (1) to (5) indicate selected targets, and the numbers indicate the order of selection. Note that the priority of target selection within each target candidate follows the order in which each target candidate is selected.

  FIG. 3 shows a case where Hth_Num = 5 high threshold target candidates and Lth_Num = 2 low threshold target candidates are detected as forward targets of the host vehicle. In this case, since (Hth_Num + Lth_Num) ≦ Nmax, Hth_Num = 5 high threshold target candidates and Lth_Num = 2 low threshold target candidates are all selected as the high threshold target and the low threshold target. In the example shown in FIG. 3, since the number of high threshold target candidates Hth_Num> the priority selection number Npri, the target selecting unit 13 firstly selects (1) to (1) to the target selection priority from the high threshold target candidates. After preferentially selecting four (= Npri) high-threshold targets as shown in (4), 2 as shown in (5) and (6) according to the target selection priority from the low-threshold target candidates. The low threshold target is selected, and the selection process is assigned so that one high threshold target is selected from the high threshold target candidates as shown in (7) for the remainder.

  Next, a case where the sum of the high threshold target candidate number Hth_Num and the low threshold target candidate number Lth_Num exceeds the maximum target number Nmax will be described. In this condition, first, when the number of high threshold target candidates Hth_Num ≦ priority selection number Npri, the target selection unit 13 sets the Hth_Num high threshold targets and (Nmax−Npri) low threshold targets. And (Npri−Hth_Num) low threshold targets are selected as detection results.

  FIG. 4 shows a case where Hth_Num = 3 high threshold target candidates and Lth_Num = 7 low threshold target candidates are detected as forward targets of the host vehicle. In this case, the target selection unit 13 first prioritizes three (= Hth_Num) high threshold targets as indicated by (1) to (3) according to the target selection priority from the high threshold target candidates. Then, four (= (Nmax−Npri)) low threshold targets are selected from the low threshold target candidates according to the target selection priority as shown in (4) to (7), and the remainder As shown in (8), the selection process is assigned so that one (= (Npri−Hth_Num)) high threshold targets are selected from the low threshold target candidates.

  Further, when the sum of the high threshold target candidate number Hth_Num and the low threshold target candidate number Lth_Num exceeds the maximum target number Nmax, the high threshold target candidate number Hth_Num> the priority selection number Npri, and When the number of low threshold target candidates Lth_Num ≧ (Nmax−Npri), the target selection unit 13 uses Npri high threshold targets and (Nmax−Npri) low threshold targets as detection results. select.

  FIG. 5 shows a case where Hth_Num = 5 high threshold target candidates and Lth_Num = 8 low threshold target candidates are detected as forward targets of the host vehicle. In this case, the target selection unit 13 first prioritizes four (= Npri) high threshold targets as indicated by (1) to (4) according to the target selection priority from the high threshold target candidates. And then select four (= (Nmax−Npri)) low-threshold targets as shown in (5) to (8) according to the target selection priority from the low-threshold target candidates. Allocate processing.

  Further, when the sum of the high threshold target candidate number Hth_Num and the low threshold target candidate number Lth_Num exceeds the maximum target number Nmax, the high threshold target candidate number Hth_Num> the priority selection number Npri, and When the number of low threshold target candidates Lth_Num <(Nmax−Npri), the target selection unit 13 includes Npri high threshold targets, Lth_Num low threshold targets, and (Nmax−Npri−Lth_Num). One high threshold target is selected as a detection result.

  FIG. 6 shows a case where Hth_Num = 8 high threshold target candidates and Lth_Num = 2 low threshold target candidates are detected as forward targets of the host vehicle. In this case, the target selection unit 13 first prioritizes four (= Npri) high threshold targets as indicated by (1) to (4) according to the target selection priority from the high threshold target candidates. (2) (2) (Lth_Num) low threshold targets are selected from the low threshold target candidates according to the target selection priority (5) (6). As shown in (7) and (8), selection processing is assigned so that two (= (Nmax−Npri−Lth_Num)) high threshold targets are selected from the high threshold target candidates.

  Next, the collision prediction unit 14 will be described. When the detection result including the high threshold target and the low threshold target is output by the target selection unit 13, the collision prediction unit 14 considers the speed according to each of the high threshold target and the low threshold target. Thus, the stage of possibility of collision is set based on the distance to the object set as the high threshold target or the low threshold target (for example, three stages of high possibility, low, and none).

  Further, when the possibility of a collision is set by the collision prediction unit 14, the vehicle control unit 15 sets the brake ECU 4, the suspension control actuator 5, the seat belt actuator 6, and the buzzer 7 according to the possibility of the collision. To control.

  Next, the operation in the collision reducing device 1 will be described. In particular, the flow of the target selection process in the target selection unit 13 will be described with reference to the flowchart shown in FIG. FIG. 7 is a schematic flowchart showing a flow of target selection processing according to the present embodiment.

  The millimeter wave radar 2 transmits the millimeter wave while scanning forward, receives the reflected wave, and transmits the transmission / reception data as a radar signal to the collision mitigation ECU 10. The collision mitigation ECU 10 receives a radar signal from the millimeter wave radar 2. Then, the high threshold target candidate selection unit 11 selects a high threshold target candidate based on the radar reflection intensity based on the radar signal, the first threshold, the own lane probability, and the like at regular time intervals. Similarly, the low threshold target candidate selection unit 12 selects a low threshold target candidate based on the radar reflection intensity based on the radar signal, the first threshold, the second threshold, the own lane probability, and the like at regular time intervals. . And the target selection part 11 performs the following target selection processes for every fixed time.

  First, it is determined whether or not it is the processing timing for every fixed time (step S1), and if it is the processing timing (step S1: Yes), the high threshold target candidate selecting unit 11 and the low threshold target candidate selecting unit 12 are used. To obtain a high threshold target candidate and a low threshold target candidate (step S2). Then, the acquired number of high threshold target candidates Hth_Num and the number of low threshold target candidates Lth_Num are set (step S3). Note that the maximum target number Nmax and the priority selection number Npri are set in advance.

  Therefore, it is determined whether or not the sum of the high threshold target candidate number Hth_Num and the low threshold target candidate number Lth_Num is equal to or less than the maximum target number Nmax (step S4). If the sum is equal to or less than the maximum target number Nmax (step S4: Yes), Hth_Num high threshold target candidates and Lth_Num low threshold target candidates are all selected as high threshold targets and low threshold targets. It outputs to the collision prediction part 14 (step S5).

  If the sum is not equal to or less than the maximum target number Nmax (step S4: No), it is determined whether or not the high threshold target candidate number Hth_Num ≦ the priority selection number Npri (step S6). When the number of high threshold target candidates Hth_Num ≦ the priority selection number Npri (step S6: Yes), the target selection unit 13 first selects Hth_Num high threshold targets preferentially, and then (Nmax -Npri) low-threshold targets are selected, and (Npri-Hth_Num) low-threshold targets are selected and output to the collision prediction unit 14 as detection results (step S7).

  On the other hand, when the high threshold target candidate number Hth_Num ≦ the priority selection number Npri is not satisfied (step S6: No), it is determined whether or not the low threshold target candidate number Lth_Num ≧ (Nmax−Npri) (step S8). ). When the number of low threshold target candidates Lth_Num ≧ (Nmax−Npri) (step S8: Yes), the target selection unit 13 first selects Npri high threshold targets preferentially, and then ( Nmax-Npri) low threshold targets are selected and output to the collision prediction unit 14 as detection results (step S9).

  Further, when the threshold value candidate number Lth_Num ≧ (Nmax−Npri) is not satisfied (step S8: No), the threshold value candidate number Lth_Num <(Nmax−Npri) is satisfied, and the target selection unit 13 First, Npri high-threshold targets are preferentially selected, then Lth_Num low-threshold targets are selected, and (Nmax-Npri-Lth_Num) high-threshold targets are selected. To the collision prediction unit 14 (step S10).

  When the high threshold target and the low threshold target to be processed this time are selected by such target selection processing, the collision prediction unit 14 determines the speed according to the high threshold target and the low threshold target. In consideration of the above, the stage of possibility of collision is set based on the distance to the object set as the high threshold target and the low threshold target, and the vehicle control unit 15 sets the stage of possibility of collision. In response, the brake ECU 4, the suspension control actuator 5, the seat belt actuator 6, and the buzzer 7 are controlled.

  As described above, according to the object detection device 1 according to the present embodiment, if the sum of the detected high threshold target candidate number Hth_Num and the low threshold target candidate number Lth_Num is equal to or less than the maximum target number Nmax. If all the candidates are selected and the sum of the high threshold target candidate number Hth_Num and the low threshold target candidate number Lth_Num exceeds the maximum target number Nmax, the selection from the high threshold object candidate has priority. As described above, the selection process from the high threshold object candidate and the low threshold object candidate is allocated and the high threshold object and the low threshold object are selected as the detection result, so that the detection result always includes the low threshold object. The effect of expanding the detection sensitivity using the threshold value of 2 can always be obtained, and the high-threshold object is preferentially selected, so that the reliability of object detection using the first threshold value can be ensured.

  Further, according to the object detection apparatus 1 according to the present embodiment, the low threshold object is selected from the low threshold object candidates within a range not exceeding the number obtained by subtracting the selected number of high threshold objects from the predetermined maximum target number Nmax. Since this is done, an appropriate number of low-threshold targets can be included and output under the restriction by the maximum target number Nmax.

  Also, according to the object detection device 1 according to the present embodiment, priority is given to the high threshold object from the high threshold object candidate within a range not exceeding the predetermined priority selection number Npri set smaller than the predetermined maximum target number Nmax. Therefore, it is possible to preferentially select an appropriate number of high threshold targets.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the present embodiment, an example of application to a collision mitigation device mounted on a vehicle has been described. However, other driving support devices such as an inter-vehicle distance control device and a following traveling device, and other devices such as a surrounding monitoring device may be used. Can also be applied, and can be used as a single object detection device. Further, as a mounting target, it may be mounted on a robot or the like in addition to the vehicle.

It is a lineblock diagram of the collision mitigation device concerning this embodiment. It is a schematic diagram which shows the example of a target selection process in case Hth_Num = 3 high threshold target candidates and Lth_Num = 2 low threshold target candidates are detected. It is a schematic diagram which shows the example of a target selection process in case Hth_Num = 5 high threshold target candidates and Lth_Num = 2 low threshold target candidates are detected. It is a schematic diagram which shows the example of a target selection process in case Hth_Num = 3 high threshold target candidates and Lth_Num = 7 low threshold target candidates are detected. It is a schematic diagram which shows the example of a target selection process in case Hth_Num = 5 high threshold target candidates and Lth_Num = 8 low threshold target candidates are detected. It is a schematic diagram which shows the example of a target selection process in case Hth_Num = 8 high threshold target candidates and Lth_Num = 2 low threshold target candidates are detected. It is a schematic flowchart which shows the flow of the target selection process which concerns on this Embodiment.

Explanation of symbols

2 Millimeter wave radar 13 Target selection unit

Claims (1)

Radar detection means for detecting an object by radar, a high-threshold object having a radar reflection intensity higher than the first threshold value by the radar detection means, and a radar reflection intensity lower than the first threshold value than the second threshold value; An object detection device for detecting an object having a high low threshold,
When the sum of the detected number of high threshold object candidates and the number of low threshold object candidates exceeds the predetermined maximum number of objects set to be output as a detection result, selection from the high threshold object candidates is given priority. Selecting means for allocating a selection process from the high threshold object candidate and the low threshold object candidate to select the high threshold object and the low threshold object as a detection result ,
The selection means includes
Selecting a low threshold object from the low threshold object candidates in a range not exceeding a number obtained by subtracting the selected number of the high threshold object from the predetermined maximum number of objects,
Object detection apparatus according to claim you to select a high threshold object from the high threshold object candidate within a range not exceeding a predetermined priority selection number set smaller than the predetermined maximum number of objects preferentially.

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