JP2015227782A - Rader device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the load of arithmetic processing.SOLUTION: A rader device has the following scan modes: a first scan mode that scans a transmission wave in a horizontal direction with respect to each of multiple irradiation angles when an object to be monitored is detected at the multiple irradiation angles in a vertical direction; and a second scan mode that selects at least one of the irradiation angles when the object to be monitored is detected at the irradiation angles in the vertical direction, to scan the transmission wave in a horizontal direction with respect to the selected irradiation angle. A scan mode setting section of a lader device 1 sets the first scan mode or the second scan mode, on the basis of a relationship in distance between a vehicle and the object to be monitored.

Description

  The present invention relates to a radar apparatus that detects surrounding objects.

  Conventionally, this type of radar apparatus is known. For example, Patent Document 1 below discloses a technique in which an object is detected by scanning in the vertical direction, estimating the angle at which the target exists, and scanning in the horizontal direction at that angle.

JP 2004-101347 A

  By the way, when scanning in the vertical direction, there is a high possibility that the angle at which the target exists is estimated at a plurality of locations. However, conventionally, horizontal scanning is performed for each of the plurality of angles, and as the number of angles to be scanned increases, the calculation processing load required for object detection increases. .

  Therefore, an object of the present invention is to provide a radar device that can improve the disadvantages of the conventional example and reduce the load of arithmetic processing.

  In order to achieve the above object, the present invention irradiates a transmission wave within a predetermined range centering on the moving direction of the vehicle, receives a reflected wave of the irradiated transmission wave, and transmits the transmission wave in a vertical direction. A scanning unit capable of scanning in the horizontal direction, an object detection unit for detecting an object existing in the irradiation direction based on the transmitted transmission wave and the received reflected wave, and the transmission / reception unit and the object Scanning mode of the transmission wave based on at least one of a distance and a relative speed between the object to be monitored detected by the detection unit or an estimated time until the vehicle contacts the object to be monitored A scanning mode setting unit for setting Then, as the scanning mode, when an object to be monitored is detected at a plurality of irradiation angles in the vertical direction, a first scan that scans the transmission wave in the horizontal direction with respect to each of the plurality of irradiation angles. When the object to be monitored is detected at a plurality of irradiation angles in the mode and the vertical direction, at least one irradiation angle is selected from the plurality of irradiation angles, and the selected irradiation angle is selected. And a second scanning mode for scanning the transmission wave in a horizontal direction, the scanning mode setting unit is configured so that the distance from the object to be monitored detected at the plurality of irradiation angles is longer than a predetermined distance. Or if the transceiver is moving at a higher speed than the object to be monitored and the relative speed with the object to be monitored is lower than a predetermined speed, or If the transmission / reception unit is moving below the speed of the object to be monitored or if the estimated time is longer than a predetermined time, the first scanning mode is set and detected at the plurality of irradiation angles. If the distance to the object to be monitored is equal to or less than the predetermined distance, or the transmitter / receiver is moving at a higher speed than the object to be monitored, and the object to be monitored If the relative speed is equal to or higher than the predetermined speed, or if the estimated time is equal to or shorter than the predetermined time, the second scanning mode is set, and the object detection unit is set to the second scanning mode. In this case, the object detection in the horizontal direction is performed with higher detection accuracy than in the first scanning mode.

  The radar apparatus according to the present invention reduces the calculation processing load when the second scanning mode is performed, and therefore can increase the frequency of updating information related to an object to be monitored. Therefore, when the driving support control or the preventive safety control is performed, the determination time for the object to be monitored can be shortened, and the control accuracy for the object to be monitored can be improved. As described above, the radar apparatus optimizes the scanning method of the transmission wave (radio wave) depending on whether the update frequency is sufficient, for example, at the reference update rate or when the update frequency needs to be increased beyond the reference update rate. be able to.

FIG. 1 is a diagram showing an example of a radar apparatus according to the present invention and a usage pattern thereof. FIG. 2 is a diagram for describing selection of a target to be watched using an extension line in the traveling direction of the host vehicle. FIG. 3 is a flowchart for explaining the arithmetic processing of the radar apparatus according to the present invention. FIG. 4 is a flowchart for explaining arithmetic processing of the radar apparatus according to the present invention.

  Embodiments of a radar apparatus according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

[Example]
An embodiment of a radar apparatus according to the present invention will be described with reference to FIGS.

  The radar apparatus 1 according to the present embodiment is attached to a vehicle (own vehicle) 10 as shown in FIG. 1 and detects an object existing around the own vehicle 10. The own vehicle 10 uses information on the detected object (position information, relative speed information, etc.) to perform driving such as inter-vehicle control with the preceding vehicle (object) 100 and follow-up traveling control with respect to the preceding vehicle 100. Carry out support control and preventive safety control such as vehicle motion control (vehicle behavior control, etc.) and accident avoidance support control. In this example, the radar device 1 is disposed in the front portion of the host vehicle 10.

  The radar apparatus 1 is, for example, a millimeter wave radar apparatus (millimeter wave radar sensor).

  The radar apparatus 1 includes a transmission / reception unit for a transmission wave (radio wave beam) and its reflection wave. Specifically, the transmission / reception unit includes an irradiation unit (transmission antenna) that irradiates a radio wave beam within a predetermined range centering on the moving direction of the host vehicle 10 (forward direction in this example), and reflection of the irradiated radio wave beam. It is roughly divided into a receiving unit (receiving antenna) that receives a wave. As the transmitting antenna, for example, a phased array antenna that forms a radio wave beam by DBF (digital beam forming) technology is used.

  In addition, the radar apparatus 1 includes a scanning unit that can scan a radio wave beam in a first direction and a second direction orthogonal to the first direction. In this example, the radio wave beam can be scanned in the vertical direction (up and down direction) and the horizontal direction (left and right direction) when the vehicle is mounted.

  Further, the radar apparatus 1 is provided with an object detection unit that detects an object existing in the irradiation direction based on the irradiated radio wave beam and the received reflected wave. The object detection unit detects an object by a well-known method in this technical field. For example, the object detection unit determines the presence or absence of an object based on the intensity of the reflected wave (hereinafter referred to as “reflection intensity”).

  Further, the radar apparatus 1 includes object information for estimating a distance and a relative speed between the own vehicle 10 (strictly speaking, a transmission / reception unit of the radar apparatus 1) and the detected object when the object detecting unit detects the object. An estimation unit is provided. In addition, the object information estimation unit can estimate a line connecting the host vehicle 10 (transmission / reception unit) and the object, and an angle formed between the line and the moving direction of the host vehicle 10 (transmission / reception unit) (that is, the own vehicle). The direction in which an object is present with respect to the vehicle 10 (transmission / reception unit) can be estimated. The object information estimation unit can estimate the position of the object with respect to the host vehicle 10 (transmission / reception unit) based on the angle and the distance from the host vehicle 10 to the detected object. In addition, when there is a possibility that the host vehicle 10 may come into contact with the detected object, the object information estimation unit calculates the angle, the distance between the host vehicle 10 (transceiver unit) and the detected object, and the host vehicle 10 (send / receive Part) and the detected object, the time (TTC: Time To Collision) until the host vehicle 10 contacts the detected object can be estimated. The object information estimation unit estimates these various types of information by a well-known method in this technical field. For example, here, an FM-CW (Frequency Modulated Continuous Wave) method, a pulse method, a multi-frequency CW (Continuous Wave) method, or the like may be used.

  By the way, the radar apparatus 1 can detect objects with higher accuracy by detecting objects over a wider range and with higher resolution in order to improve accuracy and controllability related to driving support control and preventive safety control. It is required to be able to do it. In addition, in the radar apparatus 1, the irradiation direction of the radio wave beam is different from the direction assumed at the time of design due to an axis shift with respect to a design value accompanying a change in occupants or a change in the loading state of a load, a change in road gradient, and the like. There is a possibility of shifting in the vertical direction. For this reason, the radar apparatus 1 is required to reduce the influence of such a radio wave beam shift. In driving support control and preventive safety control, an object that should be monitored in terms of control, such as the preceding vehicle 100, and an object that does not need to be monitored because the vehicle 10 has no trouble in traveling (the own vehicle). It is necessary to distinguish between the billboard 111 disposed above the 10 traveling roads and the iron plate 112 installed on the traveling road.

  In order to detect an object in a wider range, for example, the scanning range of the scanning unit may be widened. Further, in order to detect an object with higher resolution, for example, a radio wave beam may be irradiated with a reduced directivity.

  In addition, the scanning unit reduces the influence of such a deviation of the radio beam and also determines whether the detected object is a monitoring target for control in the vertical direction (elevation angle). Direction and depression angle direction).

  For example, the scanning unit first scans the radio wave beam in the vertical direction about the front of the host vehicle 10. Then, the object detection unit determines the presence / absence of an object based on the reflection intensity distribution obtained by the operation. When the object exists, the object detection unit determines whether or not the object is an object to be monitored (hereinafter referred to as “target”) based on the estimation information of the object information estimation unit for the object. Determine. If the target is not found in the scanning, the scanning unit scans in the vertical direction again, for example, shifting to either the left or right. When the target is found, the irradiation angle (0 degree or elevation angle or depression angle) of the radio wave beam in the vertical direction where the target exists is detected. Then, the scanning unit scans the radio wave beam in the horizontal direction while maintaining the irradiation angle in the vertical direction where the target exists.

  Here, the radar apparatus 1 detects a target at a plurality of irradiation angles (a plurality of elevation angles, a plurality of depression angles, or a plurality of elevation angles and depression angles) in the vertical direction by widening the scanning range and increasing the resolution in object detection. Sometimes. In such a case, scanning is performed by scanning a radio wave beam in the horizontal direction for each irradiation angle, despite the fact that the scanning time has become longer due to the wider angle and higher resolution of the object detection. Further, it takes time, and there is a possibility that the update rate of information related to the target (position information, relative speed information, etc.) will decrease.

  Therefore, in this embodiment, at least the following two scanning modes are provided.

  The first scanning mode is a scanning mode used in a scene where the reference update rate is sufficient (that is, a scene that does not require an increase in the update rate). A scene that is sufficient at the reference update rate is, for example, a case where the host vehicle 10 is not likely to contact the target or the possibility is not equal. On the other hand, a scene where the reference update rate is insufficient (that is, a scene that requires an increase in the update rate) is, for example, a case where the host vehicle 10 may come into contact with the target. In the first scanning mode, when a radio wave beam is scanned in the vertical direction and a target is detected at a plurality of irradiation angles in the vertical direction, the irradiation angle is maintained for each of the plurality of irradiation angles. The radio beam is scanned in the horizontal direction. That is, in the first scanning mode, the horizontal operation is performed for all irradiation angles at which the target is detected in the vertical scanning. Note that, for example, in the first scanning after the ignition is turned on, the first scanning mode is set.

  The second scanning mode is a scanning mode used in a scene that requires an increase in update rate. In the second scanning mode, when a radio wave beam is scanned in the vertical direction and a target is detected at a plurality of irradiation angles in the vertical direction, at least one irradiation angle is selected from the plurality of irradiation angles, The radio wave beam is scanned in the horizontal direction while maintaining the irradiation angle with respect to the selected vertical irradiation angle. In the second scanning mode, an irradiation angle of a target that needs to be watched more closely (hereinafter referred to as “target to be watched”) among the targets detected in the vertical scanning is selected. For this reason, also in the second scanning mode, when all targets detected in the vertical scanning are recognized as the target to be watched, all irradiation angles in which the targets are detected in the vertical scanning are horizontal. The direction may be manipulated. For example, there is a possibility of contact with the host vehicle 10, and the update target is increased with respect to the reference update rate, and information (position information, relative speed information, etc.) is quickly updated from one to the next. It's a target that you need.

  The radar apparatus 1 is provided with a scanning mode setting unit. When the target is detected at a plurality of irradiation angles in the vertical direction, the scanning mode setting unit determines, for each irradiation angle of the target, whether the detected target corresponds to a target requiring attention. The radio wave beam scanning mode is set based on the determination result. For example, when the target is detected at a plurality of irradiation angles by at least one vertical scanning, the scanning mode setting unit determines whether or not the target for each predetermined angle is a target requiring attention. Set the scanning mode. In principle, the scanning mode setting unit sets the first scanning mode when the target to be watched does not exist as a result of the determination, and sets the second scanning mode when the target to be watched exists as a result of the judgment. Set to scan mode.

  For example, when the distance between the host vehicle 10 (transmission / reception unit) and the target is longer than a predetermined distance (first predetermined distance), the scanning mode setting unit determines that the target does not correspond to a target requiring attention, When the distance is equal to or less than the predetermined distance, it is determined that the target corresponds to a target requiring attention. That is, the scanning mode setting unit sets the first scanning mode when the distance is longer than the predetermined distance, and sets the second scanning mode when the distance is equal to or less than the predetermined distance.

  Further, the scanning mode setting unit is such that the host vehicle 10 (transmission / reception unit) is moving at a higher speed than the target (that is, the relative speed at which the distance between the host vehicle 10 and the target is reduced), and If the relative speed between the target and the host vehicle 10 is lower than the predetermined speed, it is determined that the target does not correspond to the target requiring attention, and the host vehicle 10 (transmission / reception unit) moves at a higher speed than the target. If the relative speed between the target and the host vehicle 10 is equal to or higher than the predetermined speed, it is determined that the target corresponds to the target requiring attention. That is, the scanning mode setting unit sets the first scanning mode in the former case, and sets the second scanning mode in the latter case. Further, when the host vehicle 10 (transmission / reception unit) is moving below the target speed, the scanning mode setting unit determines that the target does not correspond to the target requiring attention, and sets the first scanning mode.

  The scanning mode setting unit is configured such that the distance between the host vehicle 10 (transmission / reception unit) and the target is longer than a predetermined distance (first predetermined distance), and the host vehicle 10 (transmission / reception unit) is longer than the target. When moving at high speed (that is, the relative speed at which the distance between the host vehicle 10 and the target is reduced) and the relative speed between the target and the host vehicle 10 is lower than a predetermined speed, The first scanning mode may be set by determining that the target does not correspond to the target requiring attention. Further, the scanning mode setting unit is configured such that the distance is equal to or less than a predetermined distance, the own vehicle 10 (transmission / reception unit) is moving at a higher speed than the target, and the distance between the target and the own vehicle 10 is When the relative speed is equal to or higher than a predetermined speed, the second scanning mode may be set by determining that the target corresponds to a target requiring attention.

  Further, when the estimated time until the host vehicle 10 contacts the target is longer than the predetermined time, the scanning mode setting unit determines that the target does not correspond to the target requiring attention, and the estimated time is equal to or shorter than the predetermined time. In this case, it is determined that the target is a target requiring attention. That is, the scanning mode setting unit sets the first scanning mode when the estimated time is longer than the predetermined time, and sets the second scanning mode when the estimated time is equal to or shorter than the predetermined time.

  Therefore, the scanning mode setting unit estimates at least one of the distance and the relative speed between the host vehicle 10 (transmission / reception unit) and the target detected by the object detection unit or until the host vehicle 10 contacts the target. The radio wave beam scanning mode can be set based on the time.

  In addition, the scanning mode setting unit, when the shortest distance between the extension line Le in the moving direction (traveling direction) of the host vehicle 10 shown in FIG. 2 and the target is longer than a predetermined distance (first predetermined distance), the target May be determined not to correspond to the target requiring attention, and when the shortest distance is equal to or less than a predetermined distance, it may be determined that the target corresponds to the target requiring attention. That is, the scanning mode setting unit sets the first scanning mode when the shortest distance is longer than the predetermined distance (first predetermined distance), and sets the second scanning mode when the shortest distance is equal to or less than the predetermined distance. . The extension line Le can be estimated based on, for example, the steering angle, the vehicle speed, the yaw rate, etc. of the host vehicle 10. In FIG. 2, the preceding vehicle 100 and a pole (object) 113 such as a utility pole are illustrated as targets. The shortest distance is estimated by the object information estimation unit described above.

  Hereinafter, the operation of the radar apparatus 1 will be described with reference to the flowcharts of FIGS. 3 and 4.

  The scanning unit scans the radio wave beam in the vertical direction (step ST1). As a result, the radar apparatus 1 can obtain the reflection intensity distribution of the portion where the scanning is performed.

  The object detection unit determines the presence or absence of the target based on the reflection intensity distribution (step ST2). For example, the presence / absence of the target is determined by comparing the reflection intensity with a threshold value for the reflection intensity distribution and detecting the peak of the reflection intensity. If the target is not found, this calculation process is temporarily terminated. On the other hand, when the target is found, all irradiation angles in the vertical direction of the radio wave beam related to the detection of the target are detected (step ST3).

  When the target is found, the scanning mode setting unit determines whether the scanning mode for the target is set to the first scanning mode or the second scanning mode (step ST4). For the first time, the process proceeds to step ST5 on the assumption that the first scanning mode is set as described above.

  If the first scanning mode is set, the scanning unit performs radio wave beam scanning in the horizontal direction with respect to the irradiation angle in the vertical direction related to all detected targets (step ST5). If the second scanning mode is set, the scanning unit performs radio wave beam scanning in the horizontal direction with respect to the vertical irradiation angle selected in step ST9G or step ST9H described later (step ST6). . As a result, the radar apparatus 1 can obtain the reflection intensity distribution of the portion where the horizontal scanning is performed. Here, it is assumed that the target is detected even in the horizontal scanning.

  The object detection unit detects all irradiation angles in the horizontal direction of the radio wave beam related to the detection of the target (step ST7). At that time, when the second scanning mode is set, the object detection unit performs object detection in the horizontal direction with higher detection accuracy than in the first scanning mode. For this reason, when the second scanning mode is set, for example, the transmission / reception unit squeezes the directivity to irradiate the radio beam, thereby increasing the resolution or widening the irradiation angle in the horizontal direction. What is necessary is just to raise detection accuracy.

  The object information estimation unit estimates target information (at least one of the estimation information described above) detected by the horizontal scanning (step ST8). In the own vehicle 10, driving support control and preventive safety control are implemented using the estimated information.

  The scanning mode setting unit sets the scanning mode for the next process using the estimated information (step ST9).

  For example, as shown in FIG. 4, the scanning mode setting unit determines whether or not there are a plurality of targets having estimation information (step ST9A).

  If there is only one target having estimation information, the scanning mode setting unit proceeds to step ST9F described later, and sets the scanning mode to the first scanning mode.

  On the other hand, when there are a plurality of targets having estimation information, the scanning mode setting unit determines whether or not a target requiring attention exists among the targets (step ST9B).

  The scanning mode setting unit determines whether or not the previous scanning mode is the first scanning mode when the target requiring attention does not exist (step ST9C).

  If the previous scan mode is not the first scan mode, the process proceeds to step ST9I described later, and the scan mode is set to the second scan mode.

  On the other hand, when the previous scanning mode is the first scanning mode, the scanning mode setting unit determines whether or not a certain time has elapsed after scanning in the first scanning mode (step ST9D).

  If the predetermined time has not elapsed, the process proceeds to step ST9I described later, and the scanning mode is set to the second scanning mode.

  On the other hand, when the predetermined time has elapsed, the scanning mode setting unit determines whether or not the number of targets is equal to or less than a threshold value (step ST9E). There is an upper limit to the number of targets that can be handled by this arithmetic processing depending on the communication capacity, processing capacity, and the like. From the viewpoint of object detection, even if the horizontal scanning is performed up to the number of targets exceeding the upper limit, the detection accuracy is not necessarily improved despite the longer scanning time. . For this reason, here, the upper limit is set as a threshold value, and the number of targets handled in the subsequent arithmetic processing is limited to prevent the scanning time from becoming long.

  When the number of targets is equal to or less than the threshold, the scanning mode setting unit sets the scanning mode of the next process to the first scanning mode (step ST9F).

  On the other hand, when the number of targets exceeds the threshold value, the scanning mode setting unit selects the irradiation angle in the vertical direction related to the number of targets whose upper limit is the threshold value (step ST9G). The selection target here may be determined, for example, by using the estimation information of the object information estimation unit to create an index indicating the importance level for all targets and assigning a priority order from the highest priority level. Then, the scanning mode setting unit proceeds to step ST9I described later, and sets the scanning mode to the second scanning mode. In this case, the horizontal scanning of the radio wave beam is performed with respect to the irradiation angle in the vertical direction related to the newly detected target. Although the number of targets (the number of irradiation angles) is limited here, the vertical resolution may be reduced instead.

  In addition, when there is a target requiring attention, the scanning mode setting unit selects an irradiation angle in the vertical direction related to the target requiring attention (step ST9H). Then, the scan mode setting unit sets the scan mode of the next process to the second scan mode (step ST9I).

  In the radar apparatus 1 according to the present embodiment, there is no target to be watched, the previous scanning mode is the first scanning mode, a certain time has passed since the scanning, and the number of targets is If the threshold is less than or equal to the threshold, the reference update rate is sufficient to update the information related to the target (at least one of the estimation information described above), so that the horizontal radio wave beam for all vertical irradiation angles related to the target The first scanning mode for performing the scanning is set. On the other hand, when there is a target requiring attention, the radar apparatus 1 does not have sufficient update frequency of information regarding the target requiring attention (at least one of the estimation information described above) at the reference update rate. Set to the second scanning mode that scans the horizontal radio wave beam with respect to the vertical irradiation angle related to the target, and the horizontal radio wave beam to the vertical irradiation angle related to the target other than the target of interest. Is not performed. For this reason, when the second scanning mode is carried out, the calculation processing load is reduced, so that the frequency of updating information relating to the target requiring attention can be increased. Therefore, when the driving support control and the preventive safety control are performed, the determination time for the target requiring attention can be shortened, and the control accuracy for the target requiring attention can be increased. Thus, the radar apparatus 1 can optimize the radio wave beam scanning method when the update frequency is sufficient at the reference update rate and when the update frequency needs to be increased beyond the reference update rate.

  Further, the radar apparatus 1 does not have a target to be watched and the previous scanning mode is not the first scanning mode, or does not have a target to watch and the previous scanning mode. Is the first scanning mode, and a certain time has not elapsed since the scanning, but when the number of targets exceeds the threshold, the horizontal direction with respect to the vertical irradiation angle related to the target with the threshold as the upper limit The second scanning mode for scanning the radio wave beam is set. For this reason, the radar apparatus 1 can reduce the processing load even in such a case.

  As described above, the radar apparatus 1 can detect an object in a wide range and with high resolution, and can appropriately switch the update rate of information regarding the target according to the target. For this reason, this radar apparatus 1 can improve the controllability of driving assistance control or preventive safety control.

1 Radar device 10 Own vehicle (vehicle)
100 preceding vehicle (object)
113 pole (object)

Claims (1)

A transmission / reception unit that irradiates a transmission wave within a predetermined range centered on a moving direction of the vehicle and receives a reflected wave of the irradiated transmission wave;
A scanning unit capable of scanning the transmission wave in a vertical direction and a horizontal direction;
An object detection unit that detects an object present in the irradiation direction based on the irradiated transmitted wave and the received reflected wave;
Based on at least one of a distance and a relative speed between the transmission / reception unit and the object to be monitored detected by the object detection unit or an estimated time until the vehicle contacts the object to be monitored. A scanning mode setting unit for setting a scanning mode of the transmission wave;
With
As the scanning mode, when an object to be monitored is detected at a plurality of irradiation angles in the vertical direction, a first scanning mode for scanning the transmission wave in the horizontal direction with respect to each of the plurality of irradiation angles; When an object to be monitored is detected at a plurality of irradiation angles in the vertical direction, at least one irradiation angle is selected from the plurality of irradiation angles, and the transmission is performed with respect to the selected irradiation angle. A second scanning mode for scanning the waves in the horizontal direction,
The scanning mode setting unit is configured so that the distance between the object to be monitored detected at the plurality of irradiation angles is longer than a predetermined distance, or the transmission / reception unit is faster than the object to be monitored. And the relative speed with the object to be monitored is lower than a predetermined speed, or the transmission / reception unit is moving below the speed of the object to be monitored, or If the estimated time is longer than a predetermined time, the first scanning mode is set, and if the distance to the monitoring target object detected at the plurality of irradiation angles is equal to or less than the predetermined distance, or If the transceiver is moving at a higher speed than the object to be monitored and the relative speed with the object to be monitored is equal to or higher than the predetermined speed, or the estimated time is If it is less than the predetermined time Setting the second scanning mode,
The radar apparatus according to claim 1, wherein when the second scanning mode is set, the object detecting unit performs object detection in a horizontal direction with higher detection accuracy than in the first scanning mode.

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