Radar device

Abstract

A radar device according to one aspect of the present disclosure is mounted on a mobile body, and comprises a detection unit, a speed acquisition unit, a tracking unit, a stationary object determination unit, a distance acquisition unit, an assumed angle calculation unit, and an error calculation unit. The tracking unit acquires a time series of object information corresponding to at least one object determined to be the same as a first object. Upon the first object being determined to be a stationary object, the distance acquisition unit acquires, from the acquired time series of object information, a first distance acquired when the vehicle passed right alongside the first object. The assumed angle calculation unit calculates an assumed angle on the basis of the acquired first distance and a second distance detected at the current time. The error calculation unit calculates the difference between the calculated assumed angle and a first azimuth angle as an azimuth error amount at the first azimuth angle detected at the current time.

Description

radar equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This international application claims priority based on Japanese Patent Application No. 2023-199074, filed with the Japan Patent Office on November 24, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to techniques for measuring the azimuth angle of an object.

[0003] The object detection device described in the following 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 vehicle's traveling direction, 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.

[0004] Patent No. 6933986

[0005] Roadside objects that exist in an actual driving environment are not necessarily aligned parallel to the vehicle's driving direction. As a result of detailed investigation by the inventors, it was found that, because the object detection device assumes that the first target and the second target are aligned parallel to the vehicle's traveling direction, when the device is applied to an actual driving environment, an error may occur in estimating the difference, which is the azimuth error.

[0006] The present disclosure desirably provides a radar device capable of calculating the amount of azimuth error with high accuracy.

[0007] A radar device according to one aspect of the present disclosure is mounted on a moving object and includes a detection unit, a speed acquisition unit, a tracking unit, a stationary object determination unit, a distance acquisition unit, an assumed angle calculation unit, and an error calculation unit. The detection unit detects object information of objects present in a detection area around the moving object based on transmitted and received radar waves at a predetermined time interval. The object information includes the distance, relative speed, and azimuth angle of the object. The speed acquisition unit acquires the speed of the moving object. The tracking unit determines whether a first object corresponding to the object information detected by the detection unit at a current time is identical to any of the objects corresponding to the object information detected by the detection unit at a previous time, and acquires a time series of the object information. The time series of the object information includes the object information detected by the detection unit at the current time and object information corresponding to at least one object previously detected by the detection unit that 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 vehicle speed acquired by the speed acquisition unit. The distance acquisition unit acquires a first distance when the stationary object determination unit determines that the first object is a stationary object. The first distance corresponds to the distance included in object information acquired when the vehicle passed directly beside the first object, among the time series of 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 the difference between the assumed angle calculated by the assumed angle calculation unit and the first azimuth angle as the amount of azimuth error at the first azimuth angle included in the target information detected by the detection unit at the current time.

[0008] A radar device according to one aspect of the present disclosure acquires a time series of object information for the same stationary object. The detected position of the same stationary object changes over time depending on the behavior of the vehicle. Therefore, the time change in the detected position of the same stationary object is estimated based on the behavior of the vehicle, and a first distance that takes the time change in position into account is acquired. Then, an estimated angle is calculated based on the first distance and the second distance. Therefore, the radar device can calculate the estimated angle while suppressing errors due to the position or shape of the object. Consequently, the radar device can calculate the azimuth error amount with high accuracy.

[0009] 1 is a block diagram showing the configuration of a radar device according to a first embodiment. FIG. 2 is a diagram showing a detection range of the radar device according to the first embodiment. FIG. 3 is a block diagram showing functions of a signal processing unit according to the first embodiment. FIG. 4 is a flowchart showing an azimuth error amount calculation process executed by the signal processing unit according to the first embodiment. FIG. 5 is a flowchart showing a stationary object extraction process executed by the signal processing unit according to the first embodiment. FIG. 6 is a flowchart showing a true lateral position acquisition process according to the first embodiment. FIG. 7 is a diagram showing roadside objects lined up non-parallel to the road. FIG. 8 is a diagram showing a time series of positions of roadside objects detected by the radar device according to the first embodiment. FIG. 9 is a diagram showing a method for calculating an assumed angle according to the first embodiment. FIG. 10 is a diagram showing a method for calculating an assumed angle according to a reference example. FIG. 11 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. 12 is a diagram showing an estimated value of the azimuth error amount and a true value of the measured azimuth error amount according to the first embodiment. FIG. 13 is a flowchart showing a true lateral position acquisition process executed by the signal processing unit according to the second embodiment. FIG. 14 is a flowchart showing a true lateral position acquisition process executed by the signal processing unit according to the third embodiment. FIG. 15 is a flowchart showing an azimuth error amount calculation process executed by the signal processing unit according to the fourth embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] (First Embodiment) <1-1. Configuration> The configuration of a 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 devices 10 are mounted at the front center of the vehicle 80 (e.g., the center of the front bumper), the left front and right front sides of the vehicle 80 (e.g., the left and right ends of the front bumper), and the left rear and right rear sides of the vehicle 80 (e.g., the left and right ends of the rear bumper). The radar devices 10 mounted at the above five locations have detection areas Rd at 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 for all five radar devices 10 to be mounted on the vehicle 80. Only one of the five radar devices 10 may be mounted on the vehicle 80, or two or more 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 body other than the vehicle 80, such as an aircraft, a ship, or a train.

[0012] 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 cycle 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.

[0013] 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 processing to detect object information of objects around the vehicle 80 based on the received signal. The object information includes the distance from the vehicle 80 to the object, the relative speed of the object with respect to the vehicle 80, and the azimuth angle of the object with respect to the vehicle 80.

[0014] Furthermore, the signal processing unit 4 performs processing to calculate the azimuth angle error amount Δθ by realizing various functions as a result of the CPU 41 executing various programs. Furthermore, the signal processing unit 4 estimates the azimuth angle offset error amount. 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.

[0015] 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 its value varies depending on the azimuth angle.

[0016] The offset error amount is the amount of error in the azimuth angle caused by a deviation of the axis of the radar device 10. The offset error amount is not dependent 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.

[0017] The signal processing unit 4 is also connected to the on-board sensor group 3, the assistance execution unit 5, the axis deviation notification device 51, and the on-board angle adjustment device 52. The on-board 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.

[0018] The assistance execution unit 5 assists the vehicle 80 in traveling 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.

[0019] 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.

[0020] <1-2. Processing> <1-2-1. Heading Error Calculation Processing> Next, the heading error calculation processing executed by the signal processing unit 4 will be described with reference to the flowchart in Fig. 4. The signal processing unit 4 starts executing this processing when the power of the vehicle 80 is turned on (for example, the ignition is turned on).

[0021] In S10, the detection unit 410 detects one or more objects present around the vehicle 80 as targets having object information based on the received signals. The object information includes a distance R, a relative speed V, and an azimuth angle θ.

[0022] Next, in S20, the tracking unit 413 performs a tracking process on 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 the at least one target detected at the current time (i.e., the current processing cycle). The tracking unit 413 then 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 objects detected in the past and determined to be identical to the first object.

[0023] The objects determined to be identical to the first object include an object detected at the previous time (hereinafter referred to as the previous first object), an object determined at the previous time to be identical to the first object (hereinafter referred to as the same object before last), an object determined at the time before last to be identical to the same object before last, etc. The tracking unit 413 acquires a time series of object information for each of the targets detected in S10. The time series of object information includes object information for the target detected this time and object information corresponding to objects detected in the past and determined to be identical to the object corresponding to the current target.

[0024] 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 referred to as the lateral direction).

[0025] FIG. 9B illustrates a method for calculating the assumed angle φ according to a reference example. As shown in FIG. 9B , the reference example assumes that a first stationary object P10 and a second stationary object P20, such as roadside objects, are aligned parallel to the traveling direction. The second stationary object P20 is a different object 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 directly beside the vehicle 80. The assumed angle φ is then calculated from the lateral position Yb and the distance R to the second stationary object P20. Finally, the azimuth error amount Δθ relative to the azimuth angle θ is calculated. The azimuth angle θ is the azimuth angle of the detected second stationary object P20. However, roadside objects in an actual traveling environment, such as the first stationary object P1 and the second stationary object P2 shown in FIG. 7 , are not necessarily aligned 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.

[0026] Therefore, in this embodiment, as described above, the signal processing unit 4 acquires the lateral position Yb of the stationary object based on the time series of object information of the same stationary object, and calculates the assumed angle φ. Figure 8 schematically shows the time series of the positions of the first stationary object P1 and the second stationary object P2 detected from time t1 to t5. The positions here are positions relative to the vehicle 80 (i.e., positions with the vehicle 80 as the origin).

[0027] 7, the first stationary object P1 and the second stationary object P2 are moving from front to rear at positions spaced a predetermined distance apart in the lateral direction from the vehicle 80. Therefore, for example, if the vehicle 80 passes directly beside the first stationary object P1 at time t3, the estimated angle φ corresponding to the azimuth angle θ detected at time t1 can be calculated from the distance R detected at time t3 and the distance R detected at time t1.

[0028] Furthermore, when the vehicle 80 is not traveling in a straight line, for example, when traveling on a curve, the signal processing unit 4 corrects the detected lateral position at the time of passing directly alongside 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 detection values ​​(e.g., steering angle and / or yaw rate) output from the on-board sensor group 3. The signal processing unit 4 then corrects the lateral position of the stationary object based on the estimated behavior of the vehicle 80, using the lateral position at the time of passing directly alongside the stationary object as a reference. Specifically, the lateral position at the second time is determined by adding the travel distance to the lateral position at the first time. The first time is the time when the vehicle 80 passes directly alongside 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, by estimating the behavior of the vehicle 80, the signal processing unit 4 can calculate the estimated angle φ based on the time series of object information of the stationary object. Therefore, in this embodiment, the tracking unit 413 acquires the time series of object information of each target.

[0029] 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 piece of object information. The stationary object extraction process will be described in detail later.

[0030] Next, in S40, the offset error estimating unit 412 estimates the amount of offset error.

[0031] Next, in S50, one target for which the processing of S60 to S90 has not been performed is selected from the targets corresponding to all stationary objects extracted in S30, and the processing of S60 to S90 is performed for the selected target (hereinafter referred to as the selected target).

[0032] In S60, the distance acquisition unit 415 executes a process of acquiring a lateral position. Specifically, based on the time series of object information of the selected target, the distance R detected when the vehicle 80 passed directly beside the object corresponding to the selected target is acquired as the lateral position Yb. The details of the process of acquiring a lateral position will be described later.

[0033] Next, in S70, the estimated angle φ=acos(Yb / R) is calculated from the lateral position Yb acquired in S60 and the distance R detected in S10.

[0034] 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.

[0035] Next, in S90, the error calculation unit 417 determines whether or not the processes of S60 to S80 have been executed for all targets corresponding to the stationary objects extracted in S30. If the error calculation unit 417 determines that the processes of S60 to S80 have not been executed for all targets corresponding to the stationary objects, it returns to the process of S50, and if it determines that the processes of S60 to S80 have been executed for all targets corresponding to the stationary objects, it proceeds to the process of S100.

[0036] Subsequently, in S100, the error calculation unit 417 corrects the azimuth angles θ of all targets detected in S10 using the azimuth error amount Δθ in the error amount table, as shown in FIG.

[0037] 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; if it determines that the power has been turned off, the process ends.

[0038] <1-2-2. Stationary Object Extraction Processing> Next, the stationary object extraction processing executed by the stationary object determination unit 414 will be described with reference to the flowchart of FIG.

[0039] In S200, the stationary object determination unit 414 sets a stationary object extraction range. The stationary object extraction range is a range of relative speeds of stationary objects. The relative speeds of stationary objects change depending on the speed of the vehicle 80. The stationary object determination unit 414 sets the stationary object extraction range, which is a range of expected relative speeds of stationary objects, depending on the vehicle speed acquired by the speed acquisition unit 411.

[0040] Next, in S210, the stationary object determination unit 414 selects one target from among the targets detected in S10 for which the processing 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 processing 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 processing of S220, and proceeds to the processing of S230.

[0041] In S220, the object corresponding to the target selected in S210 is determined to be a stationary object, and the process proceeds to S23.

[0042] In S230, the stationary object determination unit 414 determines whether the processing of S210 has been executed for all targets detected in S10. If the stationary object determination unit 414 determines that the processing of S210 has not been executed for all targets, the processing returns to S200. If the stationary object determination unit 414 determines that the processing of S210 has been executed for all targets, the processing ends and the processing proceeds to S40.

[0043] <1-2-3. Abutment Position Acquisition Processing> Next, the abutment position acquisition processing executed by the distance acquisition unit 415 will be described with reference to the flowchart of FIG.

[0044] In S300, the distance acquisition unit 415 acquires the foreground distance of the same stationary object at the previous time. The same stationary object is an object that, among the objects corresponding to targets detected at the previous time, is determined to be the same as the stationary object corresponding to the target selected in S50 (hereinafter referred to as the selected stationary object). The foreground 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 foreground distance based on the offset error amount estimated by the offset error estimating unit 412. Furthermore, when the vehicle 80 is not traveling in a straight line, the distance acquisition unit 415 corrects the foreground distance based on the behavior of the vehicle 80 so that it is 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 foreground distance of the same stationary object at infinity.

[0045] 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 less than or equal to 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.

[0046] In S320, the distance acquisition unit 415 registers the lateral distance acquired at the current time as the directly beside position Yb. As the vehicle 80 approaches directly beside the selected stationary object, the longitudinal distance of the selected stationary object decreases, and when the vehicle 80 is positioned directly beside the selected stationary object, the longitudinal distance of the selected stationary object becomes approximately zero (i.e., closest to zero). Then, as the vehicle 80 moves away from the selected stationary object, the longitudinal distance of the selected stationary object increases. If the magnitude of the longitudinal distance at the current time is equal to or less than the magnitude of the longitudinal distance at the previous time, there is a possibility that the vehicle 80 passed directly beside the selected stationary object at the current time. Therefore, the distance acquisition unit 415 acquires the lateral distance calculated from the azimuth angle θ and the distance R at the current time, and registers the acquired lateral distance as the directly beside position Yb of the selected stationary object. After processing S320, the distance acquisition unit 415 proceeds to processing S70.

[0047] 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 forward distance at the current time is greater than the magnitude of the forward distance 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 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 amount of lateral movement 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.

[0048] Until the vehicle 80 passes directly beside the selected stationary object, the lateral position Yb of the selected stationary object is updated in the processing 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 value last updated in the processing 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 was shortest. After the processing of S330, the distance acquisition unit 415 proceeds to the processing of S70.

[0049] <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.

[0050] <1-4. Effects> According to the first embodiment described above in detail, the following effects are achieved.

[0051] (1) The signal processing unit 4 acquires a time series of target information for the same stationary object. The detected position of the same stationary object changes over time depending on the behavior of the vehicle 80. Therefore, it is possible to estimate the change in the detected position of the same stationary object over time based on the behavior of the vehicle 80 and acquire the lateral position Yb that takes the change in position over time into account. Then, the assumed angle φ is calculated based on the lateral position Yb and the distance R. Therefore, the signal processing unit 4 can calculate the assumed angle φ while suppressing errors due to the position or shape of the object. Consequently, the signal processing unit 4 can calculate the azimuth error amount Δθ with high accuracy.

[0052] (2) The distance acquisition unit 415 corrects the object information using the offset error estimated by the offset error estimation unit 412, and acquires the directly-across position Yb based on the corrected object information. This reduces the influence of the axis shift of the radar device 10, improving the accuracy of determination when the object passes directly aside. This in turn improves the accuracy of calculation of the azimuth error amount.

[0053] (3) The distance acquisition unit 415 acquires the change in the vertical distance of the selected stationary object over time from the time series of the 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 vertical distance over time.

[0054] Second Embodiment 2-1. Differences from First Embodiment The second embodiment has the same basic configuration as the first embodiment, and therefore the 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 is to be referred to.

[0055] 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, in the second embodiment, the distance acquisition unit 415 acquires the lateral position Yb based on the distance R of the selected stationary object, which is different from the first embodiment.

[0056] <2-2. Aspect Position Acquisition Processing> Aspect position acquisition processing that the distance acquisition unit 415 of the second embodiment executes in place of the aspect position acquisition processing shown in FIG. 6 of the first embodiment will be described with reference to the flowchart of FIG.

[0057] 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.

[0058] 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. If 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 it becomes the same as when the vehicle 80 is traveling in a straight line. If 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. If 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.

[0059] In S420, the distance acquisition unit 415 executes the same processing as in S320. After processing S420, the distance acquisition unit 415 proceeds to processing S70. As the vehicle 80 approaches directly beside the selected stationary object, the distance R of the selected stationary object becomes shorter, and when the vehicle 80 is positioned directly beside the selected stationary object, the distance R of the selected stationary object becomes 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 less than or equal to the distance R at the previous time, there is a possibility that the vehicle 80 passed directly beside 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 as the directly beside position Yb of the selected stationary object.

[0060] In S430, the distance acquisition unit 415 executes the same process as in 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.

[0061] 2-3. Effects According to the second embodiment described above in detail, the effect (1) of the first embodiment described above is achieved, and further, the following effects are achieved.

[0062] (4) The distance acquisition unit 415 determines when the vehicle 80 has 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 has passed directly beside the selected stationary object while eliminating the influence of an error in the azimuth angle θ of the selected stationary object.

[0063] (Third embodiment) <3-1. Differences from the first embodiment> The third embodiment has the same basic configuration as the first embodiment, so the differences will be described below. Note that the same reference numerals as in the first embodiment indicate the same configuration, and the preceding description should be referred to.

[0064] 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, in the third embodiment, the distance acquisition unit 415 acquires the lateral position Yb based on the relative velocity V of the selected stationary object, which is different from the first embodiment.

[0065] <3-2. Aspect Position Acquisition Processing> Aspect position acquisition processing that the distance acquisition unit 415 of the third embodiment executes instead of the aspect position acquisition processing shown in FIG. 6 of the first embodiment will be described with reference to the flowchart of FIG.

[0066] 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.

[0067] 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. If 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. If the distance acquisition unit 415 determines that the relative speed V at the current time is less than or equal to the relative speed V at the previous time, the process proceeds to S520. If 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.

[0068] In S520, the distance acquisition unit 415 executes the same processing as S320. After the processing of S520, the distance acquisition unit 415 proceeds to the processing of S70. As the vehicle 80 approaches directly beside the selected stationary object, the relative speed V of the selected stationary object decreases, and when the vehicle 80 is positioned directly beside the selected stationary object, the relative speed V of the selected stationary object becomes approximately zero (i.e., 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 directly beside 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 as the directly beside position Yb of the selected stationary object.

[0069] In S530, the distance acquisition unit 415 executes the same processing as in S330. After the processing of S530, the distance acquisition unit 415 proceeds to the processing 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 of the same object as the selected stationary object at the previous time.

[0070] <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 effects are also achieved.

[0071] (5) The distance acquisition unit 415 determines when the vehicle 80 has passed directly beside the selected stationary object based on the change over time in the relative velocity V of the selected stationary object. This makes it possible to determine when the vehicle 80 has passed directly beside the selected stationary object while eliminating the influence of an error in the azimuth angle θ of the selected stationary object.

[0072] (Fourth embodiment) <4-1. Differences from the first embodiment> The basic configuration of the fourth embodiment is the same as that of the first embodiment, so the differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and reference is made to the preceding description.

[0073] The fourth embodiment differs from the first embodiment in that the signal processing unit 4 calculates the heading error amount Δθ on the condition that the vehicle 80 is traveling in a straight line. That is, in the fourth embodiment, the signal processing unit 4 does not update the error amount table of the heading error amount Δθ when the vehicle 80 is not traveling in a straight line.

[0074] <4-2. Orientation Error Calculation Process> With reference to the flowchart in FIG. 14, the lateral position acquisition process that the signal processing unit 4 of the fourth embodiment executes in place of the orientation error calculation process shown in FIG. 4 of the first embodiment will be described.

[0075] In this embodiment, the signal processing unit 4 executes processing of S55 in addition to the processing of S10 to S100 of the heading error calculation processing shown in Fig. 4. Specifically, between the processing of S50 and the processing of 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 processing of S50, and if it determines that the vehicle 80 is traveling in a straight line, it proceeds to the processing of S60.

[0076] 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.

[0077] 4-3. Effects According to the fourth embodiment described above in detail, the effect (1) of the first embodiment described above is achieved, and further, the following effects are achieved.

[0078] (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 the error calculation unit 417 can calculate the azimuth error amount Δθ with higher accuracy.

[0079] (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 modifications.

[0080] (a) The determination of S310 in the directly beside position acquisition process of the first embodiment, the determination of S410 in the directly beside position acquisition process of the second embodiment, and the determination 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 determinations among S310, S410, and S510, and if all of the two or more determinations are negative, proceed to the processing of S220, S320, and S420. If any of the two or more determinations is positive, proceed to the processing of S230, S330, and S430. By determining when the vehicle 80 has passed directly beside the selected stationary object based on multiple determination conditions, the accuracy of the determination of the directly beside passing can be improved. Consequently, the accuracy of the calculation of the azimuth error amount can be improved.

[0081] (b) In the first embodiment, it was determined that the vehicle 80 passed directly beside the selected stationary object at the time when the magnitude of the longitudinal distance was minimum. However, it is possible that the vehicle 80 passes directly beside the selected stationary object between the time when the magnitude of the longitudinal distance was minimum and the next time (the time when the longitudinal distance increased). Therefore, the distance acquisition unit 415 may acquire the directly beside position Yb based on the lateral distance acquired at the time when the magnitude of the longitudinal distance was minimum and the lateral distance acquired at the next time. For example, the distance acquisition unit 415 may acquire the directly beside position Yb as the average of the lateral distances acquired at the two times. Similarly, in the second embodiment, the distance acquisition unit 415 may acquire the directly 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 directly beside position Yb based on the lateral distance acquired at the time when the relative velocity V was minimum and the next time.

[0082] (c) The radar device 10 and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the radar device 10 and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the radar device 10 and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible recording medium. The method for implementing the functions of each unit included in the radar device 10 does not necessarily need to include software; all of the functions may be implemented using one or more hardware devices.

[0083] (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.

[0084] (e) In addition to the above-described radar device, the present disclosure can also 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 a method for calculating the amount of azimuth error.[Technical Ideas Disclosed in the Present Specification] [Item 1] A radar device (10) mounted on a moving body (80), comprising: a detection unit (410) configured to detect object information 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 object information including a distance, a relative speed, and an azimuth angle of the object; a speed acquisition unit (411) configured to acquire the speed of the moving body; and a tracking unit (413) configured to (i) determine whether a first object corresponding to the object information detected by the detection unit at a current time is identical to any of the objects corresponding to the object information detected by the detection unit at a previous time, and (ii) acquire a time series of the object information, the time series of the object information including the object information detected by the detection unit at the current time and the object information corresponding to at least one object detected by the detection unit in the past and 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 when the stationary object determination unit determines that the first object is a stationary object, the first distance corresponding to the distance included in the object information acquired when the vehicle passed directly beside the first object in the time series of the object information acquired by the tracking unit; and 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; an error calculation unit (417) configured to calculate an amount of azimuth error for each azimuth angle, and 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 a current time.[Item 2] The radar device according to Item 1, wherein the distance acquisition unit (415) is configured to calculate a time series of a forward distance in the vehicle's traveling direction from the time series of object information, and determine when the vehicle passed directly beside the first object based on when the forward distance is smallest in the calculated time series of forward distance. [Item 3] The radar device according to Item 1 or 2, wherein the distance acquisition unit (415) is configured to determine when the vehicle passed directly beside the first object based on when the relative velocity is closest to zero in the time series of the relative velocity included in the time series of object information. [Item 4] The radar device according to any one of Items 1 to 3, wherein the distance acquisition unit (415) is configured to determine when the vehicle passed directly beside the first object based on when the distance is smallest in the time series of distance included in the time series of object information. [Item 5] The radar device according to any one of Items 1 to 4, further comprising an offset error estimation unit (412) configured to estimate an offset error amount of the azimuth angle corresponding to an axial deviation of the radar device (10), wherein the distance acquisition unit (415) is configured to (i) correct each of the time series of the longitudinal distances based on the offset error amount estimated by the offset error estimation unit, and (ii) determine a time when the vehicle passed directly beside the first object based on a time when the longitudinal distance is smallest in the corrected time series of the longitudinal distances. [Item 6] The radar device according to any one of Items 1 to 5, wherein the distance acquisition unit is configured to determine when the vehicle has passed directly beside the first object based on 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 vehicle's traveling direction calculated from the time series of object information, (ii) the relative velocity is closest to zero in a time series of relative velocity included in the time series of object information, and (iii) the distance is minimum in the time series of distance included in the time series of object information. [Item 7] The radar device according to any one of Items 1 to 6, wherein the error calculation unit (417) is configured to calculate the amount of azimuth error when the moving body is traveling in a straight line.

Claims

1. A radar device (10) mounted on a moving body (80), comprising: a detection unit (410) configured to detect object information 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 object information including a distance, a relative speed, and an azimuth angle of the object; a speed acquisition unit (411) configured to acquire the speed of the moving body; and a tracking unit (413) configured to (i) determine 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) acquire a time series of the object information, the time series of the object information including the object information detected by the detection unit at the current time and the object information corresponding to at least one object detected by the detection unit in the past and 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 when the stationary object determination unit determines that the first object is a stationary object, the first distance corresponding to the distance included in the object information acquired when the vehicle passed right beside the first object in 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; 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 a current time.

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

3. The radar device according to claim 1 or 2, wherein the distance acquisition unit (415) is configured to determine when the vehicle passed directly beside the first object based on the time when the relative velocity is closest to zero in the time series of the relative velocity included in the time series of the object information.

4. The radar device according to claim 1 or 2, wherein the distance acquisition unit (415) is configured to determine when the vehicle has passed directly beside the first object based on the time when the distance is smallest in the time series of distances included in the time series of object information.

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

6. The radar device of claim 1, wherein the distance acquisition unit is configured to determine when the vehicle has passed directly beside the first object based on 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 object information, (ii) the relative velocity is closest to zero in the time series of relative velocity included in the time series of object information, and (iii) the distance is a minimum in the time series of distance included in the time series of object information.

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

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