JP2014202678A - Object detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an object that exists outside an own vehicle accurately.SOLUTION: An object detection device 10 comprises: a radar device 11 mounted in a vehicle 1; an object determining section 21 which detects an object that exists outside the vehicle 1 the radar device 11; and an extrapolation section 23 which, in the case where detection of the object by the object determining section 21 is interrupted, predicts a position of the object by extrapolation using the position of an object detected by the object determining section 21 in the past. The extrapolation section 23 uses a correlation between a distance from the vehicle 1 to the object and a reception level of electromagnetic wave by the radar device 11, and makes the allowable frequency of extrapolation in a distance having low reception level relatively larger than the allowable frequency of extrapolation in a distance having high reception level.

Description

  The present invention relates to an object detection device.

  Conventionally, when the recognition of a target that reflects a radar wave is interrupted due to multiple wave propagation on the road surface of the radar wave of the radar device mounted on the host vehicle, the position of the target is extrapolated, etc. When predicting the method, a technique for differentiating the prediction method is known depending on whether the first extrapolation after the recognition is interrupted or the second or subsequent extrapolation (for example, , See Patent Document 1).

JP 2004-233085 A

  By the way, in the radar apparatus according to the above-described prior art, the extrapolation upper limit number is a constant value, and extrapolation is performed according to the constant extrapolation upper limit number regardless of whether the target recognition is easily interrupted or not easily interrupted. May be continued, and the extrapolation is excessively repeated, resulting in a problem that the accuracy of detecting the target is lowered.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an object detection device capable of accurately detecting an object existing in the outside of the host vehicle.

In order to solve the above problems and achieve the object, the present invention employs the following aspects.
(1) An object detection device according to an aspect of the present invention includes a radar device (for example, the radar device 11 in the embodiment) mounted on a host vehicle (for example, the vehicle 1 in the embodiment), and The object detection unit (for example, the object determination unit 21 in the embodiment) that detects an object existing in the outside world and the detection of the object by the object detection unit are interrupted in the past. Extrapolation means for predicting the position of the object by extrapolation using the position of the object detected by the means (for example, the extrapolation unit 23 in the embodiment), and the extrapolation means Using the relative relationship between the distance from the vehicle to the object and the reception intensity of the electromagnetic wave by the radar device, the allowable number of extrapolations at the distance where the reception intensity is low (for example, the extrapolation counter C in the embodiment) ) Before Relatively increased than the allowable number of the extrapolation of the receiving intensity is high the distance.

(2) In the object detection device according to (1), the extrapolation unit stores a map of a correspondence relationship between the distance and the reception intensity (for example, a distance / reception level map in the embodiment). The map may be changed by changing the height position of the radar apparatus according to the state of the host vehicle, and the allowable number of extrapolations may be set by the changed map.

(3) In the object detection device according to (1) or (2), the extrapolation unit is a map of a correspondence relationship between the distance and the reception intensity (for example, a distance / reception level map in the embodiment). May be stored, the map may be changed according to the type of the object, and the allowable number of extrapolations may be set according to the changed map.

(4) In the object detection device according to any one of (1) to (3), the extrapolation unit is a map of a correspondence relationship between the distance and the reception intensity (for example, the distance in the embodiment). A reception level map) may be created based on a change in the reception intensity accompanying a change in the distance from the host vehicle to the stationary object or the oncoming vehicle among the objects detected by the radar device.

(5) An object detection device according to an aspect of the present invention includes a radar device (for example, the radar device 11 in the embodiment) mounted on a host vehicle (for example, the vehicle 1 in the embodiment), and The object detection unit (for example, the object determination unit 21 in the embodiment) that detects an object existing in the outside world and the detection of the object by the object detection unit are interrupted in the past. Extrapolation means (for example, extrapolation unit 23 in the embodiment) for predicting the position of the object by extrapolation using the position of the object detected by the means, and the extrapolation means includes the radar The allowable number of extrapolations (for example, extrapolation counter C in the embodiment) is set using the history of the received intensity of electromagnetic waves by the apparatus.

(6) In the object detection device according to (5), the extrapolation means detects the object continuously at least a plurality of times by the object detection means, and continues the plurality of times. When the reception strength decreases, the allowable number of extrapolations may be increased.

(7) In the object detection device according to (5) or (6), the extrapolation unit detects the object continuously at least a plurality of times by the object detection unit, and the plurality of times When the reception intensity continuously increases over time, the allowable number of extrapolations may be decreased.

(8) In the object detection device according to (6), when the amount of decrease in the reception intensity is equal to or less than a predetermined value, the allowable number of extrapolations is not changed or the allowable number of extrapolations is decreased. You may let them.

(9) In the object detection device according to (7), when the increase amount of the reception intensity is equal to or less than a predetermined value, the allowable number of extrapolations is not changed or the allowable number of extrapolations is increased. You may let them.

  According to the object detection apparatus according to the aspect described in (1) above, by increasing the allowable number of extrapolations at a distance where detection of an object is easily interrupted due to low reception intensity, Prediction can be continued properly. On the other hand, at a distance where the detection of an object is difficult to be interrupted due to a high reception strength, excessive extrapolation is prevented by relatively reducing the allowable number of extrapolations, for example, in the state where no object actually exists. It is possible to prevent the prediction from being continued as necessary. By these, it is possible to accurately detect an object outside the host vehicle.

Furthermore, in the case of (2) above, even if the height position of the radar apparatus changes due to changes in the load amount of the host vehicle, the height of the suspension, etc., extrapolation is performed by an appropriate map. An allowable number of times can be set.
Furthermore, in the case of (3) above, the allowable number of extrapolations can be set with an appropriate map according to the type of object.
Furthermore, in the case of (4) above, a map can be easily created while the host vehicle is traveling.

Furthermore, in the case of the above (5), the allowable number of extrapolations can be appropriately set based on the change in reception intensity obtained in real time while the host vehicle is traveling.
Furthermore, in the case of (6) above, it is estimated that the reception intensity changes in a decreasing tendency with respect to the next object detection, and by increasing the allowable number of extrapolations, the prediction of the object position can be continued appropriately. it can.
Furthermore, in the case of (7), it is estimated that the reception intensity changes in an increasing tendency with respect to the next object detection, and excessive extrapolation can be prevented by reducing the allowable number of extrapolations.
Furthermore, in the case of the above (8) or (9), when the amount of change in the reception intensity is equal to or less than a predetermined value for the next object detection, or the change tendency of the reception intensity is opposite to the previous trend. Presumed. Thereby, the allowable number of extrapolations can be set appropriately.

It is a block diagram of the object detection apparatus which concerns on embodiment of this invention. It is a figure which shows the distance and reception level map which shows the correspondence of the distance between the vehicle and the object which were calculated by the object detection apparatus which concerns on embodiment of this invention, and a reception level. The figure which shows the correspondence of the distance and reception level between the vehicle and the object which were detected by the object detection apparatus which concerns on embodiment of this invention, and the correspondence of the prediction distance estimated by extrapolation, and a reception level It is. It is a flowchart which shows operation | movement of the object detection apparatus which concerns on embodiment of this invention. It is a flowchart which shows the process of the target extrapolation shown in FIG. It is a flowchart which shows the process of the extrapolation counter setting shown in FIG. It is a block diagram of the object detection apparatus which concerns on the 3rd modification of embodiment of this invention. It is a flowchart which shows the process of an extrapolation counter setting among operation | movement of the object detection apparatus which concerns on the 3rd modification of embodiment of this invention. It is a figure which shows an example of the correspondence of the distance between the own vehicle and object which concern on the 3rd modification of embodiment of this invention, and a reception level. It is a figure which shows the correspondence of the distance and the reception level of the target of the last cycle and this time cycle which concern on the 3rd modification of embodiment of this invention, and the correspondence of the prediction distance and reception level in the next and the next cycle. is there.

Hereinafter, an object detection device according to an embodiment of the present invention will be described with reference to the accompanying drawings.
The object detection device 10 according to the present embodiment is based on the detection result of the object in the outside world, for example, so that it can automatically follow the preceding vehicle or can automatically avoid contact with the object in the outside world. It is mounted on a vehicle 1 that can be travel controlled. As shown in FIG. 1, the vehicle 1 includes a radar device 11, a yaw rate sensor 12, a speed sensor 13, a suspension height detection unit 14, a processing device 15, a brake actuator 16, a throttle actuator 17, It has. Further, the object detection device 10 includes, for example, a radar device 11, a yaw rate sensor 12, a speed sensor 13, a suspension height detection unit 14, and a processing device 15.

  The radar device 11 divides a detection target area set in the outside of the vehicle 1 into a plurality of angle areas, and transmits an electromagnetic wave transmission signal so as to scan each angle area. And the reflected signal of the reflected wave produced when each transmission signal is reflected by the object (for example, a stationary object, another vehicle, etc.) outside the vehicle 1 is received. The radar apparatus 11 generates a detection signal corresponding to the transmission signal and the reflected signal, for example, a detection signal related to the distance from the radar apparatus 11 to the external object and the relative speed of the external object due to the Doppler effect, and the generated detection signal Is output to the processing device 15. For example, if the radar apparatus 11 is a millimeter wave radar, the radar apparatus 11 outputs a beat signal obtained by mixing a transmission signal and a reflection signal as a detection signal.

The yaw rate sensor 12 detects the yaw rate of the vehicle body of the vehicle 1 (rotational angular velocity about the vertical axis of the center of gravity of the vehicle) and outputs a yaw rate detection signal to the processing device 15.
The speed sensor 13 detects the rotational speed (wheel speed) of the driving wheel of the vehicle 1, detects the speed of the vehicle body based on the wheel speed, and outputs a speed detection signal to the processing device 15.
The suspension height detection unit 14 detects the height of a suspension (not shown) of the vehicle 1 and outputs a suspension height detection signal to the processing device 15. For example, the suspension height detection unit 14 directly detects the height of the suspension or detects the brake caliper pressure and the deceleration of the vehicle body when the brake is operated, and based on the detection results, the vehicle 1 The load amount is detected, and the suspension height is detected based on the load amount.

  The processing device 15 includes an object determination unit 21, a distance / reception level map calculation unit 22, an extrapolation unit 23, and a vehicle control unit 24.

  The object determination unit 21 recognizes a target based on a detection signal output from the radar apparatus 11 in a cycle repeated at a predetermined cycle. For example, if the radar apparatus 11 is a frequency-modulated continuous wave (FMCW) millimeter wave radar, the object determination unit 21 extracts a peak frequency component from the power spectrum of the beat signal for each of the upstream and downstream frequencies. For the combination of peak frequency components (peak pair) in the up and down sections, the position (detection position) and the speed (detection speed, that is, the distance from the peak pair (that is, the distance from the vehicle 1) are obtained. Relative speed with respect to the vehicle 1). Further, based on the position and speed calculated for the peak pair in the previous cycle, the predicted position and predicted speed in the current cycle of the peak pair in the previous cycle are calculated. Then, if the positional difference between the detected position and the predicted position is less than the predetermined position difference and the speed difference between the detected speed and the predicted speed is less than the predetermined speed difference, there is a connection relationship between the peak pair of the previous cycle and the current cycle. The peak pair that is determined to have a connection relationship in a predetermined number of consecutive cycles or more is recognized as a target.

  The object determination unit 21 recognizes an object such as a stop object or another vehicle (a preceding vehicle, a preceding vehicle, an oncoming vehicle, etc.) from the recognized targets, and determines the type of the recognized object. For example, the object determination unit 21 is a large vehicle, a normal passenger car, and a motorcycle according to the intensity of the reflected signal reflected from another vehicle, that is, the received intensity (reception level or the like) of the reflected signal received by the radar device 11. Judging the type. Further, the object determination unit 21 determines the type of the other vehicle based on the size of the other vehicle according to the number of reflection points (detection points) of the reflected signal received by the radar device 11 on the other vehicle. The object determination unit 21 determines the type of the other vehicle based on the width dimension and the height dimension of the other vehicle according to the position of the reflection point (detection point) of the reflected signal received by the radar device 11 on the other vehicle. judge.

  The distance / reception level map calculation unit 22, for example, the suspension height of the vehicle 1 detected by the suspension height detection unit 14, the height position of the radar device 11 calculated in advance by storage or predetermined calculation, and object determination A distance / reception level map is calculated based on a predetermined ground propagation model of electromagnetic waves using the height position of the detection point of the object detected by the unit 21 and the type of the determined object. The height position of the radar apparatus 11 can be calculated using, for example, the detection limit distance of the radar apparatus 11.

For example, as shown in FIG. 2, the distance / reception level map includes the distance between the vehicle 1 and the object, and the reception intensity of the reflected signal reflected from the object and received by the radar apparatus 11 (for example, the reception level). ). In this distance / reception level map, the attenuation level of the electromagnetic wave received by the radar device 11 tends to increase as the distance increases, so that the reception level of the electromagnetic wave (reflected signal) by the radar device 11 tends to decrease. Change. Furthermore, due to the multiple wave propagation of the electromagnetic wave until the electromagnetic wave transmitted from the radar device 11 is reflected by the object and received by the radar device 11, the reception level becomes a maximum value along with the change in distance. It changes so as to repeat the minimum value alternately.
The radar apparatus 11 has a predetermined threshold for the reception level of electromagnetic waves, that is, a predetermined threshold for the intensity of detectable electromagnetic waves. This threshold increases the distance as shown in FIG. 2, for example. Along with this, it changes to a downward trend. Thereby, the difference between the maximum value of the reception level and the threshold value is larger than the difference between the minimum value of the reception level and the threshold value, and it becomes easy to detect an object stably at a distance corresponding to the maximum value. On the other hand, the difference between the minimum value of the reception level and the threshold value is smaller than the difference between the maximum value of the reception level and the threshold value, and it is difficult to detect an object at a distance corresponding to the minimum value.
Further, the reception level of the electromagnetic wave by the radar device 11 changes according to the type of the object. For example, as shown in FIG. Since the cross-sectional area is large, the reception level for the oncoming vehicle is relatively smaller than the reception level of the preceding vehicle, and the oncoming vehicle is more likely to be interrupted by the radar device 11 than the preceding vehicle. .

  The distance / reception level map calculation unit 22 is a combination of appropriate values for the suspension height of the vehicle 1, the height position of the radar device 11, the height position of the detection point of the object, the type of the object, and the like. The distance / reception level map calculated in step 1 may be used as a basic map. The basic map may be switched to another distance / reception level map that varies depending on the change in the height position of the radar device 11 according to the state of the vehicle 1 or the type of the object. The other distance / reception level map may be calculated by appropriate correction such as multiplying a distance / reception level map, which is a basic map, by a predetermined gain.

  The extrapolation unit 23 stores a history of the position and speed of the object detected by the object determination unit 21 when an object is detected by the radar device 11. When the detection of the object is interrupted by the radar device 11, the extrapolation is estimated only within a predetermined period after the timing when the interruption occurs based on the stored position and speed history of the object. Do. When the detection of the object is interrupted by the radar device 11, the reception level of the electromagnetic wave by the radar device 11 is, for example, around the minimum value between the maximum values of the reception level corresponding to the distances L4 and L5 shown in FIG. This is the case when it becomes less than a predetermined threshold. In this case, the extrapolation unit 23 starts from the vehicle 1 in the cycle in which the detection interruption occurs by extrapolation using the history of the position and speed of the object detected by the object determination unit 21 at the timing before the detection interruption occurs. Predicted distances L4a, L4b, and L4c to the object are calculated. Accordingly, the extrapolation unit 23 considers that the detection of the object is continued at the reception level corresponding to the predetermined threshold at the predicted distances L4a, L4b, and L4c.

  The extrapolation unit 23 sets the allowable number of extrapolation performed when the detection of the object by the radar apparatus 11 is interrupted by the distance / reception level map calculated by the distance / reception level map calculation unit 22. More specifically, the extrapolation unit 23 extrapolates the allowable number of extrapolations (extrapolation counter C described later) at a distance with a low reception level based on the distance / reception level map to an extrapolation at a distance with a high reception level. Is relatively larger than the allowable number of times. The extrapolation unit 23 determines that the decrease in the reception level due to the multiple wave propagation of the electromagnetic wave of the radar device 11 is negligible when the distance from the vehicle 1 to the object is less than the predetermined lower limit distance. Thus, it is not necessary to execute the process of changing the allowable number of extrapolations based on the reception level.

  The vehicle control unit 24 controls the travel of the vehicle 1 using the position and speed of the object detected by the object determination unit 21 and the position and speed of the object estimated by the extrapolation unit 23. For example, the vehicle control unit 24 sets the target vehicle speed for making the inter-vehicle distance between the vehicle 1 and the preceding vehicle coincide with the target inter-vehicle distance during execution of the follow-up traveling in which the vehicle 1 automatically follows the preceding vehicle. calculate. Then, the throttle actuator 17 or the brake actuator 16 is controlled so that the speed of the vehicle 1 matches the target vehicle speed. In addition, for example, the vehicle control unit 24 may perform contact based on the position and speed of the vehicle 1 and the object during execution of the contact avoidance control that automatically avoids contact with the object in the outside of the vehicle 1. The presence or absence of is determined. Then, the throttle actuator 17 or the brake actuator 16 and the steering actuator (not shown) are controlled so as to avoid contact between the vehicle 1 and the object.

  The object detection device 10 according to the present embodiment has the above-described configuration. Next, the operation of the object detection device 10 will be described.

First, for example, in step S01 shown in FIG. 4, the speed of the host vehicle detected by the speed sensor 13 is acquired.
Next, in step S02, the radar apparatus 11 is operated.
Next, in step S03, the target is recognized based on the detection signal output from the radar apparatus 11.
Next, in step S04, an object such as a stationary object or another vehicle is recognized from the recognized targets, and the type of the recognized object is determined. Then, the position and speed of the object are acquired based on the position and speed of the target calculated when recognizing the target.
Next, in step S05, a target extrapolation process described later is performed.
Next, in step S06, the position and speed of the recognized object and the position and speed of the object estimated by extrapolation are used so that the speed of the host vehicle matches the target vehicle speed. Control the brake actuator 16 and proceed to the end.

The target extrapolation process described above will be described below.
First, for example, in step S11 shown in FIG. 5, it is determined whether or not the number of targets recognized by the object determination unit 21 or estimated by the extrapolation unit 23 in the previous cycle is greater than zero.
If this determination is “NO”, the flow proceeds to return.
On the other hand, if this determination is “YES”, the flow proceeds to step S12.
In step S12, the target information of the previous cycle is acquired.

Next, in step S13, the position difference is less than the predetermined position difference and the speed difference is less than the predetermined speed difference between the target recognized by the object determination unit 21 in the current cycle and the target in the previous cycle. It is determined whether or not.
If this determination is “YES”, the flow proceeds to step S 14, in which extrapolation counter setting processing described later is executed, and the flow proceeds to step S 19 described later.
On the other hand, if this determination is “NO”, the flow proceeds to step S 15 described later.

In step S15, it is determined whether or not the extrapolation counter C is greater than zero.
If this determination is “NO”, the flow proceeds to step S 19 described later.
On the other hand, when the determination result is “YES”, the predicted position and the predicted speed of the target of the previous cycle in the current cycle are estimated by extrapolation using the target position and speed history before the previous cycle. To do.
Next, in step S17, the target information estimated by extrapolation is stored as target information of the current cycle.
Next, in step S18, a value (C-1) obtained by subtracting 1 from the extrapolation counter C is newly set as the extrapolation counter C, and the process proceeds to step S19.
In step S19, it is determined whether or not the above-described processing in steps S11 to S18 has been completed for all targets in the previous cycle.
If the determination result of step S19 is “YES”, the process proceeds to return.
On the other hand, when the determination result of step S19 is “NO”, the process returns to step S12 described above.

Hereinafter, the extrapolation counter setting process in step S14 will be described.
First, for example, in step S21 shown in FIG. 6, the predicted distance (that is, the distance from the vehicle 1) of the target recognized by the object determination unit 21 in the current cycle in the next cycle is used as the target position before the current cycle. And by extrapolation using the speed history.
Next, in step S22, it is determined by referring to the distance / reception level map whether the predicted distance of the next cycle is affected by the propagation of electromagnetic waves of the radar apparatus 11. More specifically, it is determined whether the reception level of the electromagnetic wave by the radar apparatus 11 corresponding to the predicted distance of the next cycle is less than a predetermined threshold value.
If this determination is “YES”, the flow proceeds to step S 24 described later.
On the other hand, if this determination is “NO”, the flow proceeds to step S 23, and in this step S 23, a predetermined upper limit number TSD that allows repetition of extrapolation is set as the extrapolation counter C, and the flow proceeds to return. .

In step S24, the predicted distance (that is, the distance from the vehicle 1) in the next cycle of the target recognized by the object determination unit 21 in the current cycle, the history of the position and speed of the target before the current cycle, and Obtained by extrapolation using the predicted distance of the next cycle.
Next, in step S25, the distance / reception level map is referred to and it is determined whether or not the predicted distance of the next cycle has the influence of the propagation of the electromagnetic wave of the radar apparatus 11. More specifically, it is determined whether or not the reception level of the electromagnetic wave by the radar apparatus 11 corresponding to the predicted distance of the next cycle is less than a predetermined threshold value.
If this determination is “NO”, the flow proceeds to step S 26, and in this step S 26, a value obtained by adding a first predetermined value (eg, 1) to the upper limit number TSD as the extrapolation counter C Set (TSD + 1) and proceed to return.
On the other hand, if this determination is “YES”, the flow proceeds to step S 27, and in this step S 27, the extrapolation counter C is a second predetermined value (for example, 2) larger than the first predetermined value for the upper limit number of times TSD. Etc.) is set and the value (TSD + 2) obtained by adding is set, and the process proceeds to return.

As described above, according to the object detection device 10 according to the present embodiment, at a distance where detection of an object is likely to be interrupted due to a low reception level, by relatively increasing the allowable number of extrapolation, The position prediction can be continued appropriately. On the other hand, at a distance where detection of an object is difficult to be interrupted due to a high reception level, excessive extrapolation is prevented by relatively reducing the allowable number of extrapolations. For example, it is possible to prevent the prediction from being continued unnecessarily in a state where no object actually exists. By these, the object of the external field of the vehicle 1 can be detected with high accuracy.
Furthermore, even when the height position of the radar apparatus 11 changes due to changes in the loading amount of the vehicle 1 or the height of the suspension, the allowable number of extrapolations by an appropriate distance / reception level map Can be set. Further, the allowable number of extrapolations can be set by an appropriate distance / reception level map corresponding to the type of object.

(First modification)
In the above-described embodiment, the distance / reception level map calculation unit 22 that calculates the distance / reception level map is provided. However, the present invention is not limited to this. For example, instead of the distance / reception level map calculation unit 22 A distance / reception level map storage unit that stores a previously created distance / reception level map may be provided. In the first modification, the extrapolation unit 23 may calculate the allowable number of extrapolations with reference to the distance / reception level map stored in the distance / reception level map storage unit.

(Second modification)
In the embodiment described above, the distance / reception level map calculation unit 22 calculates the distance / reception level map based on a predetermined ground propagation model of electromagnetic waves. However, the present invention is not limited to this. A distance / reception level map may be created on the basis of a change in reception intensity associated with a change in distance from the vehicle 1 to the detected object.
According to the second modification, the distance / reception level map can be easily created while the vehicle 1 is traveling. Further, during the execution of the follow-up traveling in which the vehicle 1 follows the preceding vehicle, a distance / reception level map is created by another vehicle (for example, an oncoming vehicle) recognized by the object determination unit 21, for example, other than the vehicle Compared with the case where the distance / reception level map is created by other objects, the practicality can be improved.

(Third Modification)
In the embodiment described above, a reception level history storage unit 31 is provided instead of the distance / reception level map calculation unit 22 as in the object detection apparatus 10 according to the third modification shown in FIG. The length detection unit 14 may be omitted.
In the third modification, the reception level history storage unit 31 is received in real time by the radar device 11 and the distance between the vehicle 1 and the object obtained in real time by the object determination unit 21 in the traveling state of the vehicle 1. The history of the reception level of the reflected signal of the electromagnetic wave reflected by the object is stored.

In the third modification, the extrapolation unit 23 sets the allowable number of extrapolations (that is, the extrapolation counter C) using the history of the distance and the reception level stored in the reception level history storage unit 31.
For example, when the extrapolation unit 23 decreases the reception level of a target that is determined to be continuously connected in at least a plurality of cycles and deviates from the theoretical range of change according to the distance. To increase the allowable number of extrapolations. When the amount of decrease in the reception level is equal to or less than a predetermined value, the allowable number of extrapolations is not changed or the allowable number of extrapolations is decreased. On the other hand, if the reception level of a target that has been determined to be continuously connected in at least multiple cycles has increased beyond the theoretical range of variation according to distance, extrapolation Reduce the allowed number of times. If the amount of increase in reception strength is equal to or less than a predetermined value, the allowable number of extrapolations is not changed or the allowable number of extrapolations is increased.

Hereinafter, the extrapolation counter setting process in step S14 described above in the third modification will be described.
First, for example, in step S31 shown in FIG. 8, the reception level of the reflection signal received by the radar apparatus 11 for the target recognized by the object determination unit 21 in the current cycle is acquired.
Next, in step S32, a theoretical change amount DST of the reception level corresponding to the distance is calculated between the target recognized by the object determination unit 21 in the current cycle and the target in the previous cycle. In this process, for example, as shown in FIG. 9, the distance (the distance from the vehicle 1 to the target) that has been grasped in advance and the theoretical reception level (the reception level of the reflected signal from the target received by the radar device 11). The theoretical reception levels PA and PB corresponding to the distances LA and LB of the previous and current cycles are acquired based on the information on the correspondence relationship with the theoretical value. Then, a theoretical change amount DST (= PB−PA) of the theoretical reception levels PA and PB corresponding to the distances LA and LB of the previous and current cycles is calculated. The theoretical reception level changes in an increasing trend as the distance decreases.

Next, in step S33, it is determined whether or not the value (RA + DST) obtained by adding the theoretical change amount DST to the reception level RA for the target in the previous cycle is greater than the reception level RB for the target in the current cycle. To do.
If this determination is “YES”, the flow proceeds to step S 34, where the extrapolation counter C is obtained by adding a third predetermined value (eg, 1) to the upper limit number TSD. Set (TSD + 1) and proceed to return.
On the other hand, if this determination is “NO”, the flow proceeds to step S33.

Next, in step S35, it is determined whether or not the value (RA + DST) obtained by adding the theoretical change amount DST to the reception level RA for the target in the previous cycle is smaller than the reception level RB for the target in the current cycle. To do.
If this determination is “YES”, the flow proceeds to step S 36, and in this step S 36, a value obtained by subtracting a fourth predetermined value (eg, 1) from the upper limit number TSD as the extrapolation counter C Set (TSD-1) and proceed to return.
On the other hand, if this determination is “NO”, the flow proceeds to step S 37, in which the upper limit number TSD is set as the extrapolation counter C, and the flow proceeds to return.

  In step S33 and step S35 described above, when the distance (distance from the vehicle 1 to the target) decreases from the previous cycle to the current cycle as shown in FIG. 9, the theoretical change amount DST (= PB-PA). ) Is a positive value. On the other hand, when the distance (the distance from the vehicle 1 to the target) increases from the previous cycle to the current cycle, the theoretical change amount DST (= PB−PA) is a negative value.

For example, as shown in FIG. 10A, when the level La, Lb of the target decreases from the previous cycle toward the current cycle, and the reception level of the electromagnetic wave by the radar device 11 changes to a decreasing tendency. It is determined that there is an influence of multiwave propagation of electromagnetic waves. That is, it is determined that there is a high possibility that the reception levels corresponding to the predicted distances Lc and Ld in the next and subsequent cycles will be less than the predetermined threshold. In this case, the extrapolation counter C is increased beyond the upper limit number of times TSD, and the number of times that the extrapolation is allowed is increased, thereby maintaining the connection relation of the targets between cycles.
Also, for example, as shown in FIG. 10B, the electromagnetic wave reception level by the radar apparatus 11 increases more than the theoretical change amount DST as the target distances La and Lb decrease from the previous cycle toward the current cycle. When it changes to a tendency, it determines with there being no influence of the multiwave propagation of electromagnetic waves. That is, it is determined that there is a low possibility that the reception level corresponding to at least the predicted distance Lc in the next cycle will be less than the predetermined threshold. In this case, the extrapolation counter C is maintained at the predetermined upper limit number of times TSD or is decreased below the upper limit number of times TSD to prevent excessive extrapolation.

According to the third modification, the allowable number of extrapolations can be appropriately set based on the change in the reception level obtained in real time in the traveling state of the vehicle 1. More specifically, when the reception level continuously decreases in the previous and current cycles, it is estimated that the reception level in the next cycle changes to a decreasing tendency. As a result, the prediction of the position of the object can be appropriately continued by increasing the allowable number of extrapolations. On the other hand, when the reception level increases continuously in the previous and current cycles, it is estimated that the reception level in the next cycle changes in an increasing trend. Accordingly, excessive extrapolation can be prevented by reducing the allowable number of extrapolations.
Furthermore, when the amount of decrease or increase in reception level from the previous cycle to the current cycle is less than or equal to a predetermined value, the amount of change in reception level from the current cycle to the next cycle is less than or equal to the predetermined value, or It is estimated that the change tendency is the opposite change tendency until now (that is, from before the previous cycle to the current cycle). Thereby, the allowable number of extrapolations can be set appropriately.

(Fourth modification)
In the above-described embodiment, the extrapolation counter C is set according to whether or not the reception level of the electromagnetic wave by the radar apparatus 11 corresponding to the predicted distance of the next and subsequent cycles is less than a predetermined threshold. Further, the extrapolation counter C may be set according to the difference between the reception level corresponding to the predicted distance and a predetermined threshold value.
Further, in the above-described embodiment, the upper limit number TSD is set as the extrapolation counter C when the predicted distance of the next cycle is not affected by the multiwave propagation of the electromagnetic wave of the radar apparatus 11, but the present invention is not limited to this. For example, the extrapolation counter C is set depending on whether or not the difference between the reception level corresponding to the target distance of the current cycle and the reception level corresponding to the predicted distance of the target of the next cycle is less than a predetermined difference. May be. For example, as shown in FIG. 10B, when the difference between the reception level corresponding to the target distance Lb in the current cycle and the reception level corresponding to the predicted distance Lc of the target in the next cycle is less than a predetermined difference. As the extrapolation counter C, an upper limit number TSD or a value (TSD + 1) obtained by adding a predetermined value (for example, 1) to the upper limit number TSD may be set.

  The present embodiment described above shows an example in carrying out the present invention, and it goes without saying that the present invention is not construed as being limited to the above-described embodiment.

DESCRIPTION OF SYMBOLS 1 Vehicle 10 Object detection apparatus 11 Radar apparatus 21 Object determination part (object detection means)
22 Distance / Reception Level Map Calculation Unit 23 Extrapolation Unit (Extrapolation Means)
24 vehicle control unit 31 reception level history storage unit

Claims (9)

A radar device mounted on the host vehicle;
Object detection means for detecting an object existing in the outside world of the host vehicle by the radar device;
Extrapolation means for predicting the position of the object by extrapolation using the position of the object detected by the object detection means in the past when detection of the object by the object detection means is interrupted;
With
The extrapolation means uses the relative relationship between the distance from the host vehicle to the object and the reception intensity of the electromagnetic wave by the radar device, and determines the allowable number of extrapolations at the distance at which the reception intensity is low. Relatively greater than the allowable number of extrapolations at the distance where the received strength is high,
An object detection device characterized by that. The extrapolation means stores a map of a correspondence relationship between the distance and the reception intensity, and the map is changed by changing the height position of the radar device according to the state of the host vehicle, and the map is changed. Setting the allowable number of extrapolation by map,
The object detection apparatus according to claim 1. The extrapolation means stores a map of a correspondence relationship between the distance and the reception intensity, changes the map according to the type of the object, and sets the allowable number of extrapolations according to the changed map.
The object detection device according to claim 1, wherein the object detection device is an object detection device. The extrapolation means receives the map of the correspondence relationship between the distance and the reception intensity according to a change in the distance from the own vehicle with respect to a stationary object or an oncoming vehicle among the objects detected by the radar device. Create based on intensity changes,
The object detection device according to any one of claims 1 to 3, wherein A radar device mounted on the host vehicle;
Object detection means for detecting an object existing in the outside world of the host vehicle by the radar device;
Extrapolation means for predicting the position of the object by extrapolation using the position of the object detected by the object detection means in the past when detection of the object by the object detection means is interrupted;
With
The extrapolation means sets the allowable number of extrapolations using a history of electromagnetic wave reception intensity by the radar device,
An object detection device characterized by that. The extrapolation means permits the extrapolation when the object is continuously detected at least a plurality of times by the object detection means, and the reception intensity is continuously reduced over the plurality of times. Increase the number of times,
The object detection apparatus according to claim 5. The extrapolation means permits the extrapolation when the object is continuously detected at least a plurality of times by the object detection means and the reception intensity increases continuously over the plurality of times. Decrease the number of times,
The object detection device according to claim 5, wherein the object detection device is an object detection device. When the amount of decrease in the received strength is a predetermined value or less, do not change the allowable number of extrapolation, or reduce the allowable number of extrapolation,
The object detection apparatus according to claim 6. If the increase amount of the reception strength is a predetermined value or less, do not change the allowable number of extrapolation, or increase the allowable number of extrapolation,
The object detection apparatus according to claim 7.

Images