Radar device

Abstract

To provide a radar device with which it is possible to calculate azimuth errors with high accuracy.SOLUTION: A radar device is mounted to a mobile body 80, and comprises a detection unit 410, a speed acquisition unit 411, a tracking unit 413, a stationary object determination unit 414, a distance acquisition unit 415, an assumed angle calculation unit 416, and an error calculation unit 417. The tracking unit acquires the time sequence of object information corresponding to at least one object which is determined to be the same as a first object. The distance acquisition unit acquires a first distance which was acquired when a vehicle passed through the side of the first body out of the acquired time sequence of object information, when it is determined that the first object is a stationary object. The assumed angle calculation unit calculates an assumed angle on the basis of the acquired first distance and a second distance detected at this round of time. The error calculation unit calculates the difference between the calculated assumed angle and a first azimuth angle as the amount of an azimuth error at the first azimuth angle detected at this round of time.SELECTED DRAWING: Figure 9A

Description

[Technical field]

[0001] The present disclosure relates to techniques for measuring the azimuth angle of an object. [Background technology]

[0002] The object detection device described in Cited Document 1 derives a first distance and a first azimuth angle of a first target and a second distance of a second target based on a reflected wave of a transmission wave transmitted from a radar device. The first target and the second target are aligned parallel to the traveling direction of the vehicle, and the second target is located directly to the side of the vehicle. Furthermore, the object detection device derives a second azimuth angle, which is an assumed azimuth angle of the first target, based on the first distance and the second distance, and calculates a difference between the first azimuth angle and the second azimuth angle. The object detection device then corrects the azimuth angle derived based on the reflected wave using the difference. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6933986 Summary of the Invention [Problem to be solved by the invention]

[0004] Roadside objects that exist in an actual driving environment are not necessarily aligned parallel to the vehicle's driving direction. The object detection device described above assumes that the first target and the second target are aligned parallel to the vehicle's traveling direction, so when applied to an actual driving environment, an error occurs in estimating the difference, which is the azimuth error.

[0005] The present disclosure provides a radar device capable of calculating an azimuth error amount with high accuracy. [Means for solving the problem]

[0006] A radar device according to one aspect of the present disclosure is mounted on a moving body (80) and includes a detection unit (410), a speed acquisition unit (411), a tracking unit (413), a stationary object determination unit (414), a distance acquisition unit (415), an assumed angle calculation unit (416), and an error calculation unit (417). The detection unit detects object information including a distance, a relative speed, and an azimuth angle of an object present in a detection area around the moving body based on transmitted and received radar waves at a predetermined time interval. The speed acquisition unit acquires the speed of the moving body. The tracking unit (i) determines whether a first object corresponding to the object information detected by the detection unit at the current time is identical to any of the objects corresponding to the object information detected by the detection unit at the previous time, and (ii) acquires a time series of object information including the object information detected by the detection unit at the current time and object information corresponding to at least one object that was detected by the detection unit in the past and was determined to be identical to the first object. The stationary object determination unit determines whether the first object is a stationary object based on the relative speed and azimuth angle included in the target information detected by the detection unit and the speed of the vehicle acquired by the speed acquisition unit. When the stationary object determination unit determines that the first object is a stationary object, the distance acquisition unit acquires a first distance corresponding to a distance included in the object information acquired when the vehicle passed directly beside the first object from the time series of the object information acquired by the tracking unit. The assumed angle calculation unit calculates an assumed angle based on the first distance acquired by the distance acquisition unit and the second distance included in the target information detected by the detection unit at the current time. The error calculation unit calculates an amount of azimuth error for each azimuth angle. The error calculation unit calculates a difference between the assumed angle calculated by the assumed angle calculation unit and the first azimuth angle as an amount of azimuth error at the first azimuth angle included in the target information detected by the detection unit at the current time.

[0007] A radar device in one aspect of the present disclosure acquires a time series of target information of the same stationary object. The position detected for the same stationary object changes over time according to the behavior of the vehicle. Therefore, based on the behavior of the vehicle, the change in the position detected for the same stationary object over time is estimated, and a first distance taking into account the change in the position over time is acquired. Then, an assumed angle is calculated based on the first distance and the second distance. Therefore, the radar device can calculate the assumed angle while suppressing errors due to the arrangement or shape of the object. Furthermore, the radar device can calculate the azimuth error amount with high accuracy. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a configuration of a radar device according to a first embodiment. [Diagram 2] 2 is a diagram showing a detection range of the radar device according to the first embodiment. FIG. [Diagram 3] 3 is a block diagram showing functions of a signal processing unit according to the first embodiment. FIG. [Figure 4] 5 is a flowchart showing a direction error amount calculation process executed by a signal processing unit according to the first embodiment. [Diagram 5] 5 is a flowchart showing a stationary object extraction process executed by a signal processing unit according to the first embodiment. [Figure 6] 5 is a flowchart showing a process of acquiring a lateral position according to the first embodiment. [Figure 7] FIG. 1 is a diagram showing roadside objects arranged non-parallel to the road. [Figure 8] FIG. 2 is a diagram showing a time series of positions of roadside objects detected by the radar device according to the first embodiment. [Figure 9A] FIG. 4 is a diagram illustrating a method for calculating an assumed angle according to the first embodiment. [Figure 9B] 13A and 13B are diagrams illustrating a method for calculating an assumed angle according to a reference example. [Figure 10] 5 is a diagram showing a horizontal azimuth before correction, an azimuth error amount, and a horizontal azimuth after correction according to the first embodiment; FIG. [Figure 11]5 is a diagram showing an estimated value of an azimuth error amount according to the first embodiment and a true value of a measured azimuth error amount. FIG. [Figure 12] 10 is a flowchart showing a lateral position acquisition process executed by a signal processing unit according to the second embodiment. [Figure 13] 13 is a flowchart showing a lateral position acquisition process executed by a signal processing unit according to the third embodiment. [Figure 14] 13 is a flowchart showing an azimuth error amount calculation process executed by a signal processing unit according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. (First embodiment) <1-1. Configuration> The configuration of the radar device 10 according to this embodiment will be described with reference to FIGS. 1 to 3. In this embodiment, the radar device 10 is mounted on a vehicle 80. Specifically, the radar device 10 is mounted on the front center of the vehicle 80 (for example, the center of the front bumper), the left front side and the right front side of the vehicle 80 (for example, the left end and the right end of the front bumper), and the left rear side and the right rear side of the vehicle 80 (for example, the left end and the right end of the rear bumper). The radar devices 10 mounted on the above five locations have detection areas Rd of the front center, the left front, the right front, the left rear, and the right rear of the vehicle 80, respectively. It is not necessary that all of these five radar devices 10 are mounted on the vehicle 80. Only one of the five radar devices 10 may be mounted on the vehicle 80, or two or more of the five radar devices 10 may be mounted on the vehicle 80. Alternatively, six or more radar devices 10 may be mounted on the vehicle 80. In another embodiment, the radar device 10 may be mounted on a moving object other than the vehicle 80, such as an aircraft, a ship, or a train.

[0010] The radar device 10 includes a transceiver 2 and a signal processor 4. The transceiver 2 includes a transmitting antenna and a receiving antenna. The transmitting antenna repeatedly transmits radar waves at a predetermined period set by the signal processor 4. The receiving antenna receives reflected waves generated when the transmitted radar waves are reflected by an object, and sends a reception signal based on the received reflected waves to the signal processor 4.

[0011] The signal processing unit 4 includes a CPU 41 and a memory 42. The memory 42 includes a ROM 43 and a RAM 44. The signal processing unit 4 realizes various functions by the CPU 41 executing various programs, and executes a process of detecting object information of an object around the vehicle 80 based on the received signal. The object information includes a distance from the vehicle 80 to the object, a relative speed of the object with respect to the vehicle 80, and an azimuth angle of the object with respect to the vehicle 80.

[0012] Moreover, the signal processing unit 4 realizes various functions by the CPU 41 executing various programs, and executes a process of calculating the azimuth angle error amount Δθ. Furthermore, the signal processing unit 4 estimates the offset error amount of the azimuth angle. Specifically, the signal processing unit 4 has the functions of a detection unit 410, a speed acquisition unit 411, an offset error estimation unit 412, a tracking unit 413, a stationary object determination unit 414, a distance acquisition unit 415, an assumed angle calculation unit 416, and an error calculation unit 417.

[0013] The azimuth error amount Δθ occurs when the measurement accuracy of the azimuth angle decreases due to the distance from the radar device 10 mounted inside the bumper to the bumper and / or the shape of the bumper. The azimuth error amount Δθ depends on the azimuth angle and has a different value depending on the azimuth angle.

[0014] The offset error amount is the amount of error in the azimuth angle caused by deviation of the axis of the radar device 10. The offset error amount does not depend on the azimuth angle and has the same value in all directions. The offset error amount changes depending on the impact that the vehicle 80 receives while the vehicle 80 is traveling and / or stopped.

[0015] Furthermore, the signal processing unit 4 is connected to the on-vehicle sensor group 3, the assistance execution unit 5, the axis deviation notification device 51, and the mounted angle adjustment device 52. The on-vehicle sensor group 3 is various sensors mounted on the vehicle 80, and outputs measured values ​​to the signal processing unit 4. The various sensors include a vehicle speed sensor that measures the vehicle speed, a yaw rate sensor that measures the yaw rate, a steering angle sensor that measures the steering angle, and the like.

[0016] The assistance execution unit 5 assists the traveling of the vehicle 80 based on the position of the object detected by the signal processing unit 4. For example, when the possibility of the vehicle 80 colliding with an object increases, the assistance execution unit 5 outputs a warning or controls the traveling of the vehicle 80 to avoid the collision.

[0017] The axis deviation notification device 51 notifies the amount of offset error estimated by the signal processing unit 4. The mounting angle adjustment device 52 adjusts the mounting angle of the radar device 10 based on the amount of offset error estimated by the signal processing unit 4.

[0018] <1-2. Processing> <1-2-1. Orientation error calculation process> Next, the heading error calculation process executed by the signal processor 4 will be described with reference to the flowchart of Fig. 4. The signal processor 4 starts executing this process when the power of the vehicle 80 is turned on (for example, the ignition is turned on).

[0019] In S10, the detection unit 410 detects one or more objects existing around the vehicle 80 as targets having object information based on the received signal. The object information includes a distance R, a relative speed V, and an azimuth angle θ.

[0020] Next, in S20, the tracking unit 413 executes a tracking process for each of the targets detected in S10 to acquire a time series of object information corresponding to at least one target. Specifically, one target (hereinafter, a first target) is selected from at least one target detected at the current time (i.e., the current processing cycle). Then, the tracking unit 413 determines whether the first object corresponding to the first target is identical to any of the objects corresponding to targets detected at the previous time (i.e., the previous processing cycle). Furthermore, the tracking unit 413 acquires a time series of object information including the object information of the first target and object information corresponding to an object detected in the past and determined to be identical to the first object.

[0021] The objects determined to be identical to the first object include an object detected at the previous time (hereinafter, the previous first object), an object determined at the previous time to be identical to the first object (hereinafter, the same object before last), an object determined at the time before last to be identical to the same object before last, etc. For each of the targets detected in S10, the tracking unit 413 acquires a time series of object information including object information of each target and target information corresponding to an object detected in the past and determined to be identical to the object corresponding to each target.

[0022] The azimuth error amount Δθ is calculated as the difference between the detected azimuth angle θ and an assumed angle φ that is assumed based on the detected distance R. As shown in Fig. 9A, the assumed angle φ of the first object is calculated from the distance R of the first object and the lateral position Yb of the first object. The lateral position Yb is the distance from the vehicle 80 to the first object in a direction perpendicular to the traveling direction of the vehicle 80 (hereinafter, the lateral direction).

[0023] Here, FIG. 9B shows a calculation method of the assumed angle θ according to the reference example. As shown in FIG. 9B, in the reference example, it is assumed that the first stationary object P10 and the second stationary object P20, such as a roadside object, are arranged parallel to the traveling direction. The second stationary object P20 is an object different from the first stationary object P10. In the reference example, the lateral position Yb is detected as the distance from the vehicle 80 to the first stationary object P10 when the first stationary object P10 is located right beside the vehicle 80. Then, the assumed angle φ is calculated from the lateral position Yb and the distance R of the second stationary object P20. Furthermore, the azimuth error amount Δθ for the azimuth angle θ is calculated. However, like the first stationary object P1 and the second stationary object P2 shown in FIG. 7, roadside objects existing in the actual traveling environment are not necessarily arranged parallel to the traveling direction of the vehicle 80. Therefore, the method according to the reference example may not be able to calculate the assumed angle φ.

[0024] Therefore, in this embodiment, as described above, the signal processor 4 acquires the lateral position Yb of the same stationary object based on the time series of object information of the stationary object, and calculates the assumed angle φ. Fig. 8 shows a schematic time series of the positions of the first stationary object P1 and the second stationary object P2 detected at times t1 to t5. The positions here are positions relative to the vehicle 80 (i.e., positions with the vehicle 80 as the origin).

[0025] When the vehicle 80 is traveling in a straight line, the first stationary object P1 and the second stationary object P2 are moving from the front to the rear at positions separated by a predetermined distance in the lateral direction as viewed from the vehicle 80. Therefore, for example, when the vehicle 80 passes directly beside the first stationary object P1 at time t3, it is possible to calculate the assumed angle φ corresponding to the azimuth angle θ detected at time t1 from the distance R detected at time t3 and the distance R detected at time t1.

[0026] Furthermore, when the vehicle 80 is not traveling in a straight line, for example, traveling on a curve, the signal processing unit 4 corrects the detected lateral position when passing directly beside the vehicle 80 based on the behavior of the vehicle 80. The signal processing unit 4 estimates the behavior of the vehicle 80 (i.e., the distance traveled by the vehicle 80 in the lateral direction) based on the detection value (e.g., steering angle and / or yaw rate) output from the on-board sensor group 3. Then, the signal processing unit 4 corrects the lateral position of the stationary object based on the estimated behavior of the vehicle 80, using the lateral position when passing directly beside the stationary object as a reference. Specifically, the value obtained by adding the travel distance to the lateral position at the first time is set to the lateral position at the second time. The first time is the time when the vehicle 80 passes directly beside the stationary object. The travel distance is the distance traveled by the vehicle 80 in the lateral direction between the first time and the second time. In this way, the signal processing unit 4 can calculate the assumed angle φ based on the time series of object information of the stationary object by estimating the behavior of the vehicle 80. Therefore, in this embodiment, the tracking unit 413 acquires a time series of object information for each target.

[0027] Next, in S30, the stationary object determination unit 414 executes a stationary object extraction process. That is, the stationary object determination unit 414 extracts a target corresponding to a stationary object from at least one target detected at the current time. Furthermore, the stationary object determination unit 414 extracts a time series of object information corresponding to a stationary object from a time series of at least one object information. The details of the stationary object extraction process will be described later.

[0028] Next, in S40, the offset error estimating section 412 estimates the amount of offset error. Next, in S50, one target for which the processing of S60 to S90 has not been performed is selected from among all targets corresponding to stationary objects extracted in S30, and the processing of S60 to S90 is performed for the selected target (hereinafter, the selected target).

[0029] In S60, the distance acquisition unit 415 executes a lateral position acquisition process. Specifically, based on the time series of the object information of the selected target, the distance R detected when the vehicle 80 passes directly beside the object corresponding to the selected target is acquired as the lateral position Yb. The lateral position acquisition process will be described in detail later.

[0030] Next, in S70, an assumed angle φ=acos(Yb / R) is calculated from the lateral position Yb acquired in S60 and the distance R detected in S10.

[0031] Next, in S80, the error calculation unit 417 calculates the difference θ-φ between the azimuth angle θ detected in S10 and the assumed angle φ calculated in S70 as the azimuth error amount Δθ. Then, the error calculation unit 417 updates the error amount table based on the calculated azimuth error amount Δθ. As shown in Fig. 10, in the error amount table, the azimuth error amount Δθ is linked to the azimuth angle, and the azimuth error amount Δθ is stored for each azimuth angle. The error calculation unit 417 updates the azimuth error amount Δθ linked to the azimuth angle θ in the error amount table to the azimuth error amount Δθ calculated in S80.

[0032] Next, in S90, the error calculation unit 417 judges whether or not the processes of S60 to S80 have been performed for all targets corresponding to the stationary objects extracted in S30. If the error calculation unit 417 judges that the processes of S60 to S80 have not been performed for all targets corresponding to the stationary objects, the error calculation unit 417 returns to the process of S50, and if it judges that the processes of S60 to S80 have been performed for all targets corresponding to the stationary objects, the error calculation unit 417 proceeds to the process of S100.

[0033] Next, in S100, the error calculation unit 417 corrects the azimuth angles θ of all targets detected in S10 using the azimuth error amounts Δθ in the error amount table, as shown in FIG.

[0034] Next, in S110, the detection unit 410 determines whether the power of the vehicle 80 has been turned off. If it determines that the power is still on, the process returns to S10, and if it determines that the power has been turned off, the process ends.

[0035] <1-2-2. Stationary object extraction processing> Next, the stationary object extraction process executed by the stationary object determining unit 414 will be described with reference to the flowchart of FIG.

[0036] In S200, the stationary object determination unit 414 sets a stationary object extraction range. The stationary object extraction range is a range of the relative speed of a stationary object. The relative speed of a stationary object changes according to the vehicle speed of the vehicle 80. The stationary object determination unit 414 sets a stationary object extraction range, which is a range of the expected relative speed of a stationary object, according to the vehicle speed acquired by the speed acquisition unit 411.

[0037] Next, in S210, the stationary object determination unit 414 selects one target from among the targets detected in S10 for which the process of S210 has not been executed, and determines whether the object corresponding to the selected target is a stationary object. If the relative speed of the selected target is within the stationary object extraction range set in S200, the stationary object determination unit 414 determines that the selected target is a stationary object, and proceeds to the process of S220. If the relative speed of the selected target is not within the stationary object extraction range, the stationary object determination unit 414 determines that the selected target is not a stationary object, skips the process of S220, and proceeds to the process of S230.

[0038] In S220, the object corresponding to the target selected in S210 is determined to be a stationary object, and the process proceeds to S23. In S230, the stationary object determination unit 414 determines whether the process of S210 has been executed for all targets detected in S10. If the stationary object determination unit 414 determines that the process of S210 has not been executed for all targets, the process returns to S200. If the stationary object determination unit 414 determines that the process of S210 has been executed for all targets, the process ends and proceeds to the process of S40.

[0039] <1-2-3. Horizontal position acquisition process> Next, the lateral position acquisition process executed by distance acquisition section 415 will be described with reference to the flowchart of FIG.

[0040] In S300, the distance acquisition unit 415 acquires the vertical distance of the same stationary object at the previous time. The same stationary object is an object that is determined to be the same as the stationary object corresponding to the target selected in S50 (hereinafter, the selected stationary object) among the objects corresponding to the target detected at the previous time. The vertical distance is the distance in the traveling direction of the vehicle 80, and is calculated from the detected azimuth angle θ and the distance R. The distance acquisition unit 415 corrects the vertical distance based on the offset error amount estimated by the offset error estimation unit 412. Furthermore, when the vehicle 80 is not traveling in a straight line, the distance acquisition unit 415 corrects the vertical distance based on the behavior of the vehicle 80 so that it becomes the same as when the vehicle 80 is traveling in a straight line. When the selected stationary object is detected for the first time at the current time, the distance acquisition unit 415 sets the vertical distance of the same stationary object at the previous time to infinity.

[0041] Next, in S310, the distance acquisition unit 415 determines whether the magnitude of the vertical distance at the current time is greater than the magnitude of the vertical distance at the previous time. The vertical distance at the current time is calculated from the object information of the selected stationary object. If the distance acquisition unit 415 determines that the magnitude of the vertical distance at the current time is equal to or less than the magnitude of the vertical distance at the previous time, the process proceeds to S320. If the distance acquisition unit 415 determines that the magnitude of the vertical distance at the current time is greater than the magnitude of the vertical distance at the previous time, the process proceeds to S330.

[0042] In S320, the distance acquisition unit 415 registers the lateral distance acquired at the current time in the directly lateral position Yb. As the vehicle 80 approaches the directly lateral position of the selected stationary object, the vertical distance of the selected stationary object becomes shorter, and when the vehicle 80 is located directly lateral to the selected stationary object, the vertical distance of the selected stationary object becomes substantially zero (i.e., closest to zero). Then, as the vehicle 80 moves away from the selected stationary object, the vertical distance of the selected stationary object becomes longer. If the magnitude of the vertical distance at the current time is equal to or smaller than the magnitude of the vertical distance at the previous time, there is a possibility that the vehicle 80 passed directly lateral to the selected stationary object at the current time. Therefore, the distance acquisition unit 415 acquires the horizontal distance calculated from the azimuth angle θ and the distance R at the current time, and registers the acquired horizontal distance in the directly lateral position Yb of the selected stationary object. After the process of S320, the distance acquisition unit 415 proceeds to the process of S70.

[0043] In S330, the distance acquisition unit 415 acquires the directly lateral position Yb of the same object as the selected stationary object at the previous time. If the magnitude of the longitudinal distance at the current time is greater than the magnitude of the longitudinal distance at the previous time, the vehicle 80 has already passed directly lateral to the selected stationary object. Therefore, the distance acquisition unit 415 acquires the directly lateral position Yb of the same object as the selected stationary object at the previous time. Then, if the vehicle 80 has moved laterally between the previous time and the current time, the directly lateral position Yb at the previous time is corrected by the amount of lateral movement of the vehicle 80 (i.e., the lateral movement area of ​​the radar device 10) and registered as the directly lateral position Yb of the selected stationary object. The directly lateral position Yb at the previous time is the directly lateral position Yb registered in S330.

[0044] Until the vehicle 80 passes directly beside the selected stationary object, the lateral position Yb of the selected stationary object is updated in the process of S330 for each processing cycle. After the vehicle 80 passes directly beside the selected stationary object, the lateral position Yb of the selected stationary object becomes a value based on the last updated value in the process of S330. In other words, the lateral position Yb of the selected stationary object becomes a value based on the lateral distance acquired at the time when the longitudinal distance is shortest. After the process of S330, the distance acquisition unit 415 proceeds to the process of S70.

[0045] <1-3. Evaluation results> Fig. 11 shows a comparison between the calculated value of the azimuth error amount Δθ for the azimuth angle calculated by the error calculation unit 417 and the true value of the azimuth error amount for the azimuth angle measured in an actual road environment. In Fig. 11, the change in the calculated value of the azimuth angle error Δθ for the azimuth angle shows the same tendency as the change in the true value for the azimuth angle.

[0046] <1-4.Effects> According to the first embodiment described above in detail, the following effects are achieved. (1) The signal processing unit 4 acquires a time series of target information of the same stationary object. The position detected for the same stationary object changes over time according to the behavior of the vehicle 80. Therefore, based on the behavior of the vehicle 80, the time change of the position detected for the same stationary object can be estimated, and the lateral position Yb taking into account the time change of the position can be acquired. Then, based on the lateral position Yb and the distance R, the assumed angle φ is calculated. Therefore, the signal processing unit 4 can calculate the assumed angle φ while suppressing errors due to the arrangement or shape of the object. Furthermore, the signal processing unit 4 can calculate the azimuth error amount Δθ with high accuracy.

[0047] (2) The distance acquisition unit 415 corrects the object information with the offset error amount estimated by the offset error estimation unit 412, and acquires the directly-across position Yb based on the corrected object information. This suppresses the influence of the axis shift of the radar device 10, improving the accuracy of determination when passing directly alongside. This in turn improves the accuracy of calculation of the azimuth error amount.

[0048] (3) The distance acquisition unit 415 acquires the change in the longitudinal distance of the selected stationary object over time from the time series of object information of the selected stationary object, and can determine the time when the vehicle 80 passed directly beside the selected stationary object based on the acquired change in the longitudinal distance over time.

[0049] Second embodiment <2-1. Differences from the first embodiment> The second embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0050] In the first embodiment described above, the distance acquisition unit 415 acquires the lateral position Yb based on the vertical distance of the selected stationary object. In contrast, the second embodiment differs from the first embodiment in that the distance acquisition unit 415 acquires the lateral position Yb based on the distance R of the selected stationary object.

[0051] <2-2. Horizontal position acquisition process> With reference to the flowchart in FIG. 12, a description will be given of a lateral position acquisition process that the distance acquisition unit 415 in the second embodiment executes in place of the lateral position acquisition process shown in FIG. 6 in the first embodiment.

[0052] In S400, the distance acquisition unit 415 acquires the distance R of the same stationary object at the previous time. If the selected stationary object is detected for the first time at the current time, the distance acquisition unit 415 sets the previous distance R to infinity.

[0053] In S410, the distance acquisition unit 415 determines whether the distance R of the selected stationary object detected at the current time is greater than the distance R of the same object as the selected stationary object detected at the previous time. When the vehicle 80 is not traveling in a straight line, the distance acquisition unit 415 corrects the distance R based on the behavior of the vehicle 80 so that the distance R becomes the same as when the vehicle 80 is traveling in a straight line. When the distance acquisition unit 415 determines that the distance R at the current time is less than or equal to the distance R at the previous time, the process proceeds to S420. When the distance acquisition unit 415 determines that the distance R at the current time is greater than the distance R at the previous time, the process proceeds to S430.

[0054] In S420, the distance acquisition unit 415 executes the same process as S320. After the process of S420, the distance acquisition unit 415 proceeds to the process of S70. As the vehicle 80 approaches the lateral side of the selected stationary object, the distance R of the selected stationary object becomes shorter, and when the vehicle 80 is located lateral side of the selected stationary object, the distance R of the selected stationary object becomes the shortest. Then, as the vehicle 80 moves away from the selected stationary object, the distance R of the selected stationary object becomes longer. If the distance R at the current time is equal to or less than the distance R at the previous time, there is a possibility that the vehicle 80 passed lateral side of the selected stationary object at the current time. Therefore, the distance acquisition unit 415 registers the lateral distance of the selected stationary object acquired at the current time in the lateral position Yb of the selected stationary object.

[0055] In S430, the distance acquisition unit 415 executes the same process as S330. After the process of S430, the distance acquisition unit 415 proceeds to the process of S70. If the distance R at the current time is greater than the distance R at the previous time, the vehicle 80 has already passed directly beside the selected stationary object. Therefore, the distance acquisition unit 415 acquires the directly beside position Yb at the previous time of the same object as the selected stationary object.

[0056] <2-3.Effects> According to the second embodiment described above in detail, in addition to the effect (1) of the first embodiment described above, the following effect is further achieved.

[0057] (4) The distance acquisition unit 415 determines when the vehicle 80 passed directly beside the selected stationary object based on the change over time in the distance R of the selected stationary object. This makes it possible to determine when the vehicle 80 passed directly beside the selected stationary object while eliminating the influence of an error in the azimuth angle θ of the selected stationary object.

[0058] Third embodiment <3-1. Differences from the first embodiment> The third embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

[0059] In the first embodiment described above, the distance acquisition unit 415 acquires the lateral position Yb based on the vertical distance of the selected stationary object. In contrast, the third embodiment differs from the first embodiment in that the distance acquisition unit 415 acquires the lateral position Yb based on the relative speed V of the selected stationary object.

[0060] <3-2. Horizontal position acquisition process> With reference to the flowchart in FIG. 13, a description will be given of a lateral position acquisition process that is executed by the distance acquisition unit 415 in the third embodiment instead of the lateral position acquisition process shown in FIG. 6 in the first embodiment.

[0061] In S500, the distance acquisition unit 415 acquires the relative velocity V of the same stationary object at the previous time. If the selected stationary object is detected for the first time at the current time, the distance acquisition unit 415 sets the previous relative velocity V to infinity.

[0062] In S510, the distance acquisition unit 415 determines whether the relative speed V of the selected stationary object detected at the current time is greater than the relative speed V of the same object as the selected stationary object detected at the previous time. When the vehicle 80 is not traveling in a straight line, the distance acquisition unit 415 corrects the relative speed V based on the behavior of the vehicle 80 so that it becomes the same as when the vehicle 80 is traveling in a straight line. When the distance acquisition unit 415 determines that the relative speed V at the current time is equal to or less than the relative speed V at the previous time, the process proceeds to S520. When the distance acquisition unit 415 determines that the relative speed V at the current time is greater than the relative speed V at the previous time, the process proceeds to S530.

[0063] In S520, the distance acquisition unit 415 executes the same process as S320. After the process of S520, the distance acquisition unit 415 proceeds to the process of S70. As the vehicle 80 approaches the lateral side of the selected stationary object, the relative speed V of the selected stationary object decreases, and when the vehicle 80 is located lateral side of the selected stationary object, the relative speed V of the selected stationary object becomes approximately zero (i.e., approaches closest to zero). Then, as the vehicle 80 moves away from the selected stationary object, the relative speed V of the selected stationary object increases. If the relative speed V at the current time is equal to or less than the relative speed V at the previous time, there is a possibility that the vehicle 80 passed lateral side of the selected stationary object at the current time. Therefore, the distance acquisition unit 415 registers the lateral distance of the selected stationary object acquired at the current time in the lateral position Yb of the selected stationary object.

[0064] In S530, the distance acquisition unit 415 executes the same process as S330. After the process of S530, the distance acquisition unit 415 proceeds to the process of S70. If the relative speed V at the current time is greater than the relative speed V at the previous time, the vehicle 80 has already passed directly beside the selected stationary object. Therefore, the distance acquisition unit 415 acquires the directly beside position Yb at the previous time of the same object as the selected stationary object.

[0065] <3-3.Effects> According to the third embodiment described above in detail, in addition to the effect (1) of the first embodiment described above, the following effect is further achieved.

[0066] (5) The distance acquisition unit 415 determines when the vehicle 80 passed directly beside the selected stationary object based on the change over time in the relative speed V of the selected stationary object. This makes it possible to determine when the vehicle 80 passed directly beside the selected stationary object while eliminating the influence of an error in the azimuth angle θ of the selected stationary object.

[0067] (Fourth embodiment) <4-1. Differences from the first embodiment> The fourth embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0068] The fourth embodiment differs from the first embodiment in that the signal processor 4 calculates the azimuth error amount Δθ on the condition that the vehicle 80 is traveling in a straight line. That is, in the fourth embodiment, the signal processor 4 does not update the error amount table of the azimuth error amount Δθ when the vehicle 80 is not traveling in a straight line.

[0069] <4-2. Orientation error calculation process> With reference to the flowchart in FIG. 14, a description will be given of a lateral position acquisition process that the signal processing unit 4 of the fourth embodiment executes in place of the azimuth error calculation process shown in FIG. 4 of the first embodiment.

[0070] In this embodiment, the signal processing unit 4 executes the process of S55 in addition to the processes of S10 to S100 of the azimuth error calculation process shown in Fig. 4. Specifically, between the processes of S50 and S60, the distance acquisition unit 415 determines whether or not the vehicle 80 is traveling in a straight line based on the steering angle or yaw rate of the vehicle 80. If the distance acquisition unit 415 determines that the vehicle 80 is not traveling in a straight line, it returns to the process of S50, and if it determines that the vehicle 80 is traveling in a straight line, it proceeds to the process of S60.

[0071] Therefore, in this embodiment, the distance acquisition unit 415 acquires the lateral position Yb of the selected stationary object only when the vehicle 80 is traveling in a straight line. The assumed angle calculation unit 416 calculates the assumed angle φ only when the vehicle 80 is traveling in a straight line. The error calculation unit 417 calculates the azimuth error amount Δθ only when the vehicle 80 is traveling in a straight line.

[0072] <4-3.Effects> According to the fourth embodiment described above in detail, in addition to the effect (1) of the first embodiment described above, the following effect is further achieved.

[0073] (6) The error calculation unit 417 calculates the azimuth error amount Δθ only when the vehicle 80 is traveling in a straight line. When the vehicle 80 is traveling in a straight line, the lateral distance from the vehicle 80 to a stationary object is constant, so that the error calculation unit 417 can calculate the azimuth error amount Δθ with higher accuracy.

[0074] 5. Other Embodiments Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0075] (a) The judgment of S310 in the directly beside position acquisition process of the first embodiment, the judgment of S410 in the directly beside position acquisition process of the second embodiment, and the judgment of S510 in the directly beside position acquisition process of the third embodiment may be combined. That is, the distance acquisition unit 415 may execute two or more judgments among S310, S410, and S510, and proceed to the processing of S220, S320, and S420 when all of the two or more judgments are judged to be negative, and proceed to the processing of S230, S330, and S430 when any of the two or more judgments is judged to be positive. By judging when the vehicle 80 passed directly beside the selected stationary object based on a plurality of judgment conditions, the judgment accuracy at the time of passing directly beside the selected stationary object can be improved. Furthermore, the calculation accuracy of the azimuth error amount can be improved.

[0076] (b) In the first embodiment, it was determined that the vehicle 80 passed right beside the selected stationary object at the time when the magnitude of the vertical distance was minimum. However, it is possible that the vehicle 80 passes right beside the selected stationary object between the time when the magnitude of the vertical distance was minimum and the next time (the time when the vertical distance increased). Therefore, the distance acquisition unit 415 may acquire the right beside position Yb based on the lateral distance acquired at the time when the magnitude of the vertical distance was minimum and the lateral distance acquired at the next time. For example, the distance acquisition unit 415 may acquire the average of the lateral distances acquired at the above two times as the right beside position Yb. Similarly, in the second embodiment, the distance acquisition unit 415 may acquire the right beside position Yb based on the lateral distance acquired at the time when the distance R was minimum and the next time. In the third embodiment, the distance acquisition unit 415 may acquire the right beside position Yb based on the lateral distance acquired at the time when the relative speed V was minimum and the next time.

[0077] (c) The radar device 10 and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the radar device 10 and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the radar device 10 and the method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transient tangible recording medium as instructions executed by a computer. The method for realizing the functions of each unit included in the radar device 10 does not necessarily need to include software, and all of the functions may be realized using one or more hardware.

[0078] (d) Multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0079] (e) In addition to the above-mentioned radar device, the present disclosure can be realized in various forms, such as a system including the radar device as a component, a program for causing a computer to function as the radar device, a non-transient physical recording medium such as a semiconductor memory on which the program is recorded, and an azimuth error calculation method.

[0080] [Technical idea disclosed in this specification] [Item 1] A radar device (10) mounted on a moving body (80), a detection unit (410) configured to detect object information including a distance, a relative speed, and an azimuth angle of an object present in a detection area around the moving object based on transmitted and received radar waves at a predetermined time interval; A speed acquisition unit (411) configured to acquire the speed of the moving object; a tracking unit (413) configured to (i) determine whether a first object corresponding to object information detected by the detection unit at a current time is identical to any of the objects corresponding to object information detected by the detection unit at a previous time, and (ii) acquire a time series of object information including the object information detected by the detection unit at the current time and the object information detected by the detection unit in the past, the object information corresponding to at least one object determined to be identical to the first object; a stationary object determination unit (414) configured to determine whether the first object is a stationary object based on the relative speed and the azimuth angle included in the target information detected by the detection unit and the speed of the vehicle acquired by the speed acquisition unit; a distance acquisition unit (415) configured to acquire, when the stationary object determination unit has determined that the first object is a stationary object, a first distance corresponding to the distance included in the object information acquired when the vehicle passed directly beside the first object, from the time series of the object information acquired by the tracking unit; an assumed angle calculation unit (416) configured to calculate an assumed angle based on the first distance acquired by the distance acquisition unit and a second distance included in the target information detected by the detection unit at the current time; and an error calculation unit (417) configured to calculate an amount of azimuth error for each azimuth angle, the error calculation unit being configured to calculate a difference between the assumed angle calculated by the assumed angle calculation unit and the first azimuth angle as the amount of azimuth error at a first azimuth angle included in the target information detected by the detection unit at the current time. Radar equipment. [Item 2] The distance acquisition unit (415) is configured to calculate a time series of a longitudinal distance in a traveling direction of the vehicle from the time series of the object information, and determine a time when the vehicle passed right beside the first object based on a time when the longitudinal distance is minimum in the calculated time series of the longitudinal distance. Item 2. A radar device according to item 1. [Item 3] The distance acquisition unit (415) is configured to determine a time when the vehicle passed directly beside the first object, based on a time when the relative speed is closest to zero in the time series of the relative speed included in the time series of the object information. 3. The radar device according to item 1 or 2. [Item 4] The distance acquisition unit (415) is configured to determine when the vehicle passed right beside the first object, based on the time when the distance is minimum in the time series of distances included in the time series of object information. 4. A radar device according to any one of items 1 to 3. [Item 5] an offset error estimator (412) configured to estimate an offset error amount of the azimuth angle corresponding to an axial shift of the radar device (10); The distance acquisition unit (415) is configured to correct each of the time series of the longitudinal distances based on the amount of offset error estimated by the offset error estimation unit, and to determine the time when the vehicle passed directly beside the first object based on the time when the longitudinal distance is minimum in the corrected time series of the longitudinal distances. 5. A radar device according to any one of items 1 to 4. [Item 6] The distance acquisition unit is configured to determine when the vehicle has passed directly beside the first object based on a time when at least two of the following conditions are satisfied: (i) the longitudinal distance is a minimum in a time series of longitudinal distances in the vehicle's traveling direction calculated from the time series of the object information; (ii) the relative speed is closest to zero in a time series of the relative speed included in the time series of the object information; and (iii) the distance is a minimum in a time series of the distance included in the time series of the object information. 6. A radar device according to any one of items 1 to 5. [Item 7] The error calculation unit (417) is configured to calculate the amount of azimuth error when the moving body is traveling in a straight line. 7. A radar device according to any one of items 1 to 6. [Explanation of symbols]

[0081] 4...signal processing unit, 5...assistance execution unit, 10...radar device, 80...vehicle, 410...detection unit, 411...speed acquisition unit, 412...offset error estimation unit, 413...tracking unit, 414...stationary object determination unit, 415...distance acquisition unit, 416...estimated angle calculation unit, 417...error calculation unit.

Claims

1. A radar device (10) mounted on a moving body (80), A detection unit (410) configured to detect object information including a distance, a relative speed, and an azimuth angle of an object present in a detection area around the moving body based on transmitted and received radar waves at a predetermined time interval; A speed acquisition unit (411) configured to acquire the speed of the moving object; a tracking unit (413) configured to (i) determine whether a first object corresponding to object information detected by the detection unit at a current time is identical to any of objects corresponding to object information detected by the detection unit at a previous time, and (ii) acquire a time series of object information including the object information detected by the detection unit at the current time and the object information detected by the detection unit in the past, the object information corresponding to at least one object determined to be identical to the first object; a stationary object determination unit (414) configured to determine whether the first object is a stationary object based on the relative speed and the azimuth angle included in the target information detected by the detection unit and the speed of the vehicle acquired by the speed acquisition unit; a distance acquisition unit (415) configured to acquire a first distance corresponding to the distance included in the object information acquired when the vehicle passed right beside the first object from the time series of the object information acquired by the tracking unit when the first object is determined to be a stationary object by the stationary object determination unit; an assumed angle calculation unit (416) configured to calculate an assumed angle based on the first distance acquired by the distance acquisition unit and a second distance included in the target information detected by the detection unit at the current time; and an error calculation unit (417) configured to calculate an amount of azimuth error for each azimuth angle, the error calculation unit being configured to calculate a difference between the assumed angle calculated by the assumed angle calculation unit and the first azimuth angle as the amount of azimuth error at a first azimuth angle included in the target information detected by the detection unit at the current time. Radar equipment.

2. The distance acquisition unit (415) is configured to calculate a time series of a vertical distance in a traveling direction of the vehicle from the time series of the object information, and determine a time when the vehicle passed right beside the first object based on a time when the vertical distance is minimum in the calculated time series of the vertical distance. The radar device according to claim 1 .

3. The distance acquisition unit (415) is configured to determine a time when the vehicle passed directly beside the first object based on a time when the relative speed is closest to zero in a time series of the relative speed included in the time series of the object information.

3. A radar device according to claim 1 or 2.

4. The distance acquisition unit (415) is configured to determine a time when the vehicle passed right beside the first object based on a time when the distance is minimum in the time series of distances included in the time series of object information.

3. A radar device according to claim 1 or 2.

5. an offset error estimating unit (412) configured to estimate an offset error amount of the azimuth angle corresponding to an axial shift of the radar device (10); The distance acquisition unit (415) is configured to correct each of the time series of the longitudinal distances based on the amount of offset error estimated by the offset error estimation unit, and to determine the time when the vehicle passed right beside the first object based on the time when the longitudinal distance is minimum in the corrected time series of the longitudinal distances. The radar device according to claim 2 .

6. The distance acquisition unit is configured to determine when the vehicle has passed directly beside the first object based on a time when at least two of the following conditions are satisfied: (i) the longitudinal distance is minimum in a time series of longitudinal distances in the traveling direction of the vehicle calculated from the time series of the object information, (ii) the relative velocity is closest to zero in a time series of the relative velocity included in the time series of the object information, and (iii) the distance is minimum in a time series of the distance included in the time series of the object information. The radar device according to claim 1 .

7. The error calculation unit (417) is configured to calculate the amount of azimuth error when the moving body is traveling in a straight line. The radar device according to claim 1 .

Images