Aliasing determination device

Abstract

An information acquisition unit (S110) repeatedly acquires observation point information including an observation azimuth from a radar device. An axis offset acquisition unit (S120) acquires an axis offset of an actual mounting direction, representing the actual orientation of the radar device, relative to a reference mounting direction of the radar device. An aliasing calculation unit (S190) calculates an aliased bearing relative to the observation azimuth included in the observation point information. An instantaneous determination unit (S210-S220) determines, as the actual bearing, the observation azimuth or the aliased bearing that is closer to the reference mounting direction estimated from the axis offset and the actual mounting direction.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This international application claims priority based on Japanese Patent Application No. 2019-162006 filed with the Japan Patent Office on September 5, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a technique for determining phase aliasing of an orientation observed by a radar device. Background Art

[0004] In a radar device that uses an array antenna to receive reflected waves from a target object that has reflected radar waves and detects the target's direction using the phase difference Δθ between the received signals from each antenna, the periodicity of the phase makes it impossible to distinguish between Δθ = θ0 and Δθ = θ0 ± 2nπ. Furthermore, |θ0| < π, and n = 1, 2, etc.

[0005] For example, if a target object exists within the azimuth angle range (hereinafter referred to as the angle measurement range) corresponding to the phase difference Δθ of -π < Δθ ≤ +π [rad], its azimuth can be correctly detected. However, if a target object exists outside the angle measurement range, that is, within the range where the phase difference Δθ is Δθ ≤ -π or Δθ > π, the azimuth of the target object may be incorrectly detected as being within the angle measurement range due to so-called phase aliasing.

[0006] Patent Document 1 proposes a technique for tracking objects based on the presence or absence of historical connections. When a predicted value deviates from the angle measurement range, the system extracts observations that have historical connections to the alias-corrected predicted value and performs aliasing correction on these extracted observations, thereby obtaining the correct bearing. The predicted value refers to the value predicted based on the detection results in the previous processing cycle, while the observed value refers to the value actually observed in the current processing cycle.

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-91785

[0008] However, the inventors' detailed research revealed the following problem with the conventional technology described in Patent Document 1: When the radar device is offset, objects within the intended angle measurement range (in the absence of offset) are detected at aliased locations. This problem was discovered: if such an object is suddenly detected without a history of tracking, the aliased location is continuously detected as the object's correct location, making correction impossible. Summary of the Invention

[0009] One aspect of the present disclosure provides a technique for correctly detecting the orientation of a target object detected in a state where there is no tracking history, even if an axis offset exists in a radar apparatus.

[0010] One embodiment of the present disclosure is an aliasing determination device including an information acquisition unit, an axis offset acquisition unit, an aliasing calculation unit, and a transient determination unit.

[0011] An information acquisition unit repeatedly acquires observation point information containing observation values regarding a designated direction, i.e., an observation bearing, from a radar device mounted on a vehicle. The designated direction is at least one of a horizontal direction and a vertical direction. An axis offset acquisition unit uses the orientation of the radar device when mounted at a reference position as the mounting reference direction and the actual orientation of the radar device as the actual mounting direction, and acquires an axis offset in the designated direction relative to the mounting reference direction. An aliasing calculation unit calculates an aliased bearing, i.e., an estimated bearing when phase aliasing exists in the observation bearing included in the observation point information. An instantaneous determination unit determines, between the observation bearing and the aliased bearing associated with the observation bearing, the one that is closer to the mounting reference direction estimated based on the axis offset and the actual mounting direction as the actual bearing.

[0012] This configuration determines the presence of phase aliasing by setting the correct azimuth, whichever is closer to the reference orientation, between the observation orientation and the aliased orientation. Therefore, by determining the presence of phase aliasing without using the history of the observation orientation, the detection accuracy of the orientation of observation points within the original detection range centered on the reference orientation can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a block diagram showing the structure of the aliasing determination system.

[0014] Figure 2 It is an explanatory diagram illustrating an object detection range Rf.

[0015] Figure 3 This is a flowchart of the aliasing determination process according to the first embodiment.

[0016] Figure 4 This is an explanatory diagram regarding parameters and the like used in the aliasing determination process in the horizontal direction.

[0017] Figure 5 This is an explanatory diagram related to the determination of whether or not a target object exists in front in the horizontal aliasing determination process.

[0018] Figure 6 This is an explanatory diagram regarding the directivity of the radar device in the horizontal direction and the axis offset.

[0019] Figure 7This is an explanatory diagram showing the relationship between the angle measurement range, the observation azimuth, and the aliasing azimuth in the horizontal aliasing determination process.

[0020] Figure 8 It is an explanatory diagram showing the results of calculating the axis offset amount from the observation azimuth for each of the cases where the observation azimuth is not corrected based on the determination result of the aliasing determination and the case where the observation azimuth is corrected.

[0021] Figure 9 This is an explanatory diagram regarding parameters and the like used in the aliasing determination process in the vertical direction.

[0022] Figure 10 This is an explanatory diagram related to the determination of whether or not a target object exists in front in the aliasing determination process in the vertical direction.

[0023] Figure 11 This is an explanatory diagram related to the directivity of the radar device in the vertical direction, etc.

[0024] Figure 12 This is an explanatory diagram showing the relationship between the angle measurement range, the observation azimuth, and the aliasing azimuth in the aliasing determination process in the vertical direction.

[0025] Figure 13 This is a flowchart of the aliasing determination process according to the second embodiment.

[0026] Figure 14 This is a flowchart of the baseline update process. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0028] [1. First embodiment]

[0029] [1-1. Structure]

[0030] The aliasing determination system 1 of this embodiment is mounted on a vehicle, such as Figure 1 As shown, a radar device 2 , a camera 3 , an adjustment device 4 , an in-vehicle communication device 5 , and a control device 6 are provided.

[0031] like Figure 2 As shown, radar device 2 is installed at the front end of vehicle VH equipped with aliasing determination system 1. Radar device 2 transmits radar waves toward the front of vehicle VH and receives reflected radar waves to detect objects within detection range Rf in front of vehicle VH.

[0032] Radar device 2, for example, employs the FMCW method, alternately transmitting radar waves in an uplink modulation interval and a downlink modulation interval at a predetermined modulation cycle, and receiving the reflected radar waves. FMCW stands for Frequency Modulated Continuous Wave. Radar device 2 detects the received radar wave's received power P, the distance R to the point on the object that reflected the radar wave (hereinafter referred to as the observation point), the relative velocity Vr from the observation point, and the horizontal azimuth angle φx of the observation point for each modulation cycle. Furthermore, radar device 2 outputs observation point information indicating the detected received power P, distance R, relative velocity Vr, and horizontal azimuth angle φx to control device 6. Furthermore, the horizontal azimuth angle φx of the observation point is detected using the phase difference between the received signals received by the multiple receiving antennas of radar device 2. The azimuth angle region where phase aliasing does not occur in radar device 2 is defined as the angle measurement range, and the detection range Rf is set to an angle range at least narrower than the angle measurement range.

[0033] The camera 3 is attached to the front end of the vehicle VH or near a rearview mirror, and continuously captures images of the situation ahead of the vehicle VH including a detection range Rf.

[0034] The adjustment device 4 includes a motor and a gear mounted on the radar device 2. The adjustment device 4 adjusts the mounting angle of the radar device 2 by rotating the motor in response to a drive signal output from the control device 6. Specifically, the rotational force of the motor is transmitted to the gear, causing the radar device 2 to rotate about an axis extending in the vehicle height direction of the vehicle VH.

[0035] The in-vehicle communication device 5 communicates via an on-board LAN (Local Area Network) that interconnects various devices installed in the vehicle. The in-vehicle communication device 5 acquires detection signals from various sensors that detect vehicle behavior via the on-board LAN. The vehicle's behavior, which is the subject of detection, includes at least the speed Vs and the steering angle θ.

[0036] The control device 6 includes a microcomputer having a CPU 6a and a semiconductor memory (hereinafter referred to as "memory") 6b, such as a RAM or ROM. The various functions of the control device 6 are realized by the CPU 6a executing a program stored on a non-migratable physical recording medium. In this example, the memory 6b corresponds to the non-migratable physical recording medium that stores the program. Furthermore, the execution of the program executes the method corresponding to the program.

[0037] Functions implemented by the control device 6 executing the program include at least an axial shift detection unit 61 , an image analysis unit 62 , an aliasing determination unit 63 , and an axial shift adjustment unit 64 .

[0038] The axis deviation detection unit 61 detects the axis deviation amount γ of the actual mounting direction relative to the mounting reference direction in a specified direction based on the information of the observation point detected by the radar device 2. The mounting reference direction refers to the direction of the radar device 2 when the radar device 2 is mounted at the reference position where it should be installed. The actual mounting direction refers to the actual direction of the radar device 2 mounted on the vehicle. Here, the front direction of the radar device 2 is set as the direction of the radar device 2, and the front direction of the vehicle is set as the mounting reference direction. That is, Figure 4 As shown, the axis offset γ refers to the angle formed by the front direction of the radar device 2 with respect to the front direction of the vehicle.

[0039] The image analysis unit 62 detects the situation within the detection range Rf by analyzing the front image obtained from the camera 3. Specifically, the analysis results include at least information such as the position of the lane drawn on the road and the presence or absence of a preceding vehicle traveling in the same lane as the vehicle.

[0040] The aliasing determination unit 63 determines whether the azimuth information of the observation point detected by the radar device 2 is information subjected to phase aliasing, and corrects the azimuth information. Details will be described later. The corrected azimuth information is also used in the processing of the axis offset detection unit 61.

[0041] The axis deviation adjustment unit 64 adjusts the installation angle of the radar device 2 by driving the adjustment device 4 based on the detection result of the axis deviation detection unit 61 .

[0042] Note that detailed description of the axial misalignment detection unit 61 , the image analysis unit 62 , and the axial misalignment adjustment unit 64 will be omitted here.

[0043] The memory 6 b stores at least information indicating the directivity of the antenna included in the radar device 2 , that is, information associating an azimuth with a gain at the azimuth (hereinafter referred to as directivity information).

[0044] [1-2. Processing]

[0045] In order to realize the function as the aliasing determination unit 63, the Figure 3 The flowchart shown explains the aliasing determination process executed by the control device 6 .

[0046] When the aliasing determination system 1 is activated, the aliasing determination process is repeatedly executed.

[0047] In S110 , the control device 6 acquires observation point information from the radar device 2 .

[0048] In the next S120 , the control device 6 obtains the axis deviation amount γ which is the result of the axis deviation angle calculation process.

[0049] In the next S130, the control device 6 acquires the vehicle state via the in-vehicle communication device 5. The acquired vehicle state includes at least the vehicle speed Vs and the steering angle θ.

[0050] In the next step S140, the control device 6 acquires the analysis results of the image analysis process. The acquired analysis results include at least information on the object markers existing in the same lane as the vehicle.

[0051] In the following S150, the control device 6 determines whether the vehicle is traveling in a straight line. If it is determined that the vehicle is traveling in a straight line, the process proceeds to S160. If it is determined that the vehicle is not traveling in a straight line, the process proceeds to S260. Alternatively, for example, the determination of whether the vehicle is traveling in a straight line may be made based on the steering angle θ indicating the vehicle state acquired in S130. Alternatively, if the analysis results acquired in S140 include the shape of a white line, the determination of whether the vehicle is traveling in a straight line may be made based on the shape of the white line.

[0052] In S160, the control device 6 determines whether there is an object mark in front of the vehicle. If it is determined that there is an object mark, the process moves to S170. If it is determined that there is no object mark, the process moves to S260. Alternatively, for example, the determination of whether there is an object mark in front of the vehicle may be made based on the analysis result of the front image acquired in S140. Figure 5 As shown, based on the analysis results, it is determined whether there is a preceding vehicle in the lane.

[0053] In S170, the control device 6 selects one of the observation point information acquired in S110. The observation point corresponding to the observation point information is identified using Mi, and the direction of the observation point included in the observation point information (hereinafter referred to as the observation direction) αi is set. With the front direction of the radar device 2 as a reference (i.e., 0°), the observation direction αi is expressed as an angle clockwise from the front direction being positive and a counterclockwise angle being negative.

[0054] In the following S180, the control device 6 determines whether the observation point Mi selected in S170 is a moving object. If it is determined to be a moving object, the process proceeds to S190. If it is determined not to be a moving object, the process proceeds to S240. Furthermore, regarding whether it is a moving object, the control device 6 determines that the selected observation point Mi is a moving object if the absolute value of the difference between the relative speed (hereinafter referred to as the observation speed) Vri indicated by the observation point information of the selected observation point Mi and the host vehicle speed Vs acquired in S130 is greater than a threshold value.

[0055] In S190, assuming that phase aliasing occurs at the observation azimuth αi, the control device 6 calculates the aliasing azimuth βi, which is the azimuth at which the observation point Mi is estimated to exist. Specifically, Figure 4As shown in FIG. 1 , the azimuth angle width of the entire angle measurement range of the radar device 2 is defined as FOV and is calculated using equations (1) and (2).

[0056] βi=αi-FOV (when αi≥0) (1)

[0057] βi=αi+FOV (when αi<0) (2)

[0058] In the next S200, the control device 6 determines whether the aliasing direction βi is included in the range where the gain is greater than or equal to the threshold value (hereinafter referred to as the directional range) based on the radiation pattern representing the directivity of the radar device 2. If the control device 6 determines that the aliasing direction βi is within the directional range, it is determined that there is a possibility of phase aliasing and the process moves to S210. If it is determined that it is outside the directional range, it is determined that there is a low possibility of phase aliasing and the process moves to S240. For example, Figure 6 As shown in FIG. 1 , when the radiation pattern has a main lobe and side lobes, if the aliasing direction βi is within the side lobe, the actual observation point Mi is likely to be located in the aliasing direction βi. If the aliasing direction βi is between the main lobe and the side lobe, the probability that the actual observation point Mi is located in the aliasing direction βi is low, and the observation direction αi can be determined to be the correct direction.

[0059] In S210, the control device 6 uses equations (3) and (4) to calculate the differences between the observation orientation αi and the aliased orientation βi relative to the front direction of the vehicle (i.e., the mounting reference direction), that is, the front difference values dαi and dβi. That is, in this step, Figure 4 As shown in FIG, the axis offset γ is used to convert αi and βi expressed as angles based on the front direction of the radar device 2 into absolute values of angles based on the front direction of the vehicle. Figure 4 In this case, γ takes a negative value.

[0060] dαi=|αi-γ| (3)

[0061] dβi=|βi-γ| (4)

[0062] In the following S220, the control device 6 determines which of the observation direction αi and the aliasing direction βi is closer to the front direction. Specifically, based on the difference values dαi and dβi calculated in S210, it is determined whether dαi>dβi. If dαi>dβi, that is, if the aliasing direction βi is determined to be closer to the front direction of the vehicle than the observation direction αi, the control device 6 moves the process to S230. If dαi≤dβi, that is, if the observation direction αi is determined to be closer to the front direction of the vehicle than the aliasing direction βi, the control device 6 moves the process to S240.

[0063] In S230 , the control device 6 assumes that phase aliasing exists in the observation azimuth αi of the observation point Mi, sets the aliasing azimuth βi as the determined azimuth ψi of the observation point Mi, and proceeds to S250 .

[0064] In S240 , the control device 6 assumes that there is no phase aliasing in the observation azimuth αi of the observation point Mi, sets the observation azimuth αi as the determined azimuth ψi of the observation point Mi, and proceeds to S250 .

[0065] In S250, the control device 6 determines whether the processing from S170 to S240 has been completed for all observation point information acquired in S110. If it is determined that there is unprocessed observation point information, the control device 6 returns the process to S170. If it is determined that all observation point information has been processed, the control device 6 ends the aliasing determination process.

[0066] In S260 , the control device 6 does not determine the presence or absence of phase aliasing for all the observation point information acquired in S110 , sets the observation azimuth α as the determined azimuth ψ of the observation point M, and ends the aliasing determination process.

[0067] The determined orientation ψ of the observation point M is supplied to the subsequent processing together with the axis offset γ.

[0068] In addition, the determined orientation ψ, particularly the determined orientation ψ set in S230 and S240, is also used in the axis offset calculation process.

[0069] Furthermore, S110 corresponds to the information acquisition unit, S120 corresponds to the axis offset acquisition unit, S150 corresponds to the travel determination unit, S160 corresponds to the object determination unit, S180 corresponds to the movement determination unit, and S190 corresponds to the aliasing calculation unit. Furthermore, S200 corresponds to the directionality determination unit, S210-S220 correspond to the transient determination unit, and S230-S240 correspond to the processing execution unit. Furthermore, the control device 6 that performs the aliasing determination process corresponds to the aliasing determination device.

[0070] [1-3. Effect]

[0071] According to the first embodiment described in detail above, the following effects are achieved.

[0072] (1a) In the aliasing determination system 1, when the host vehicle is traveling in a straight line and there is an object in front of the host vehicle, aliasing determination of the observation direction αi is performed. Figure 7As shown, the presence of a target object in front of the host vehicle is utilized to determine the presence or absence of phase aliasing by using the observed direction αi or the aliased direction βi, whichever is closer to the vehicle's front direction, as the correct direction. Therefore, the aliasing determination system 1 can determine the presence or absence of phase aliasing without using the observation history of the direction of the observation point Mi, thereby obtaining the correct direction of the observation point Mi.

[0073] (1b) In the aliasing determination system 1, using the radiation pattern representing the directivity of the antenna of the radar device 2, if the aliasing direction βi is within the directional range where a gain greater than a threshold value is obtained within the radiation pattern, it is assumed that phase aliasing is likely to exist, and aliasing determination is performed. Specifically, since the received power of reflected waves from a target outside the directional range is very low and the probability of detection is low, it can be determined that phase aliasing does not exist if the aliasing direction βi is outside the directional range.

[0074] (1c) In the aliasing determination system 1, aliasing determination is performed when the observation point Mi is a moving object. That is, since it is highly likely that a stationary object such as a roadside object is not located in front of the vehicle, the accuracy of the aliasing determination can be improved by eliminating the stationary object.

[0075] (1d) In the aliasing determination system 1, the determined orientation ψ obtained through the aliasing determination process is used in the axis offset calculation process, thereby improving the calculation accuracy of the axis offset γ. For example, consider a case where an axis offset occurs in the positive direction of the angle φ. In this case, if the axis offset γ is estimated directly using the observation point orientation αi without considering phase aliasing, then Figure 8 As shown in the upper part of , the observation point Mi, which should have been detected in the positive direction, is detected in the negative direction due to phase aliasing. If the axis offset γ is estimated using such an observation point Mi, the axis offset γ is calculated to be offset to the negative side from the true value representing the front direction of the vehicle. In contrast, the aliasing direction βi is used as the determined direction ψi of the observation point Mi determined to have phase aliasing by the aliasing determination, so that Figure 8 As shown in the lower part of , the orientations ψi are roughly evenly distributed on the positive and negative sides of the true value. As a result, the axis offset γ is calculated, which is closer to the true value.

[0076] [1-4. Modifications]

[0077] In the above embodiment, an example of performing aliasing determination on the horizontal direction is shown, but it is also possible to perform aliasing determination on the horizontal direction. Figure 9 As shown in FIG, aliasing determination is performed for the vertical direction. In this case, the determination of whether there is an object target in the front in S160 is as follows: Figure 10 As shown in , it is determined based on whether it exists at the same height as the vehicle in the vertical direction. Figure 11 As shown, determination is performed taking into account the directivity in the vertical direction.

[0078] In this case, as with the horizontal orientation, Figure 12 As shown, the presence of a target object in front of the host vehicle is exploited to determine the presence of phase aliasing by using the observation azimuth αi or the aliased azimuth βi, whichever is closer to the vehicle's front direction, as the correct azimuth. Therefore, the aliasing determination system 1 can determine the presence of phase aliasing without using the observation history of the observation point Mi, thereby obtaining the correct vertical azimuth of the observation point Mi. Furthermore, the detection accuracy of the vertical axis offset γ of the radar device 2 can be improved.

[0079] [2. Second embodiment]

[0080] [2-1. Differences from the First Embodiment]

[0081] The basic structure of the second embodiment is the same as that of the first embodiment, so the following describes the differences. In addition, the same reference numerals as those in the first embodiment represent the same structures, and reference is made to the previous description.

[0082] The second embodiment differs from the first embodiment in that history information is used in the aliasing determination process.

[0083] [2-2. Processing]

[0084] Next, use Figure 13 The control device 6 of the second embodiment replaces Figure 3 The aliasing determination process performed in accordance with the aliasing determination process of the first embodiment shown in FIG. Except for the addition of S202, S204, and S255, the rest is the same as the first embodiment, so the difference will be described.

[0085] Furthermore, when a target object exists near the boundary of the detection range of the radar device 2, phase aliasing may cause observation points Mi based on the same target object to be detected on both sides of the boundary of the detection range in each processing cycle. The second embodiment also addresses such situations.

[0086] In case of an affirmative determination in S200 , the control device 6 proceeds to S202 , whereupon the control device 6 executes a reference update process.

[0087] use Figure 14 The details of the benchmark update process are described in the flowchart of FIG.

[0088] In S310, the control device 6 determines whether the received power Pi of the selected observation point Mi is greater than or equal to the maximum power maxPi stored at that time. If the control device 6 determines that Pi≥maxPi, the process proceeds to S320, and if the control device 6 determines that Pi<maxPi, the process proceeds to S400.

[0089] In S320 , the control device 6 updates the maximum power maxPi using the received power Pi.

[0090] In the following S330, the control device 6 determines whether the observed orientation αi and the reference orientation fαi are considered to be in the same orientation. Specifically, if the absolute value of the difference between αi and fαi is less than or equal to a threshold value THα, the observation orientation αi and the reference orientation fαi are considered to be in the same orientation. If the control device 6 determines that the observation orientation αi and the reference orientation fαi are in the same orientation, the control device 6 proceeds to S340. If the control device 6 determines that the observation orientation αi and the reference orientation fαi are not in the same orientation, the control device 6 proceeds to S360.

[0091] In S340, the control device 6 updates the reference orientation fαi using the observed orientation αi.

[0092] In the next S350 , the control device 6 counts up the count value Ci and ends the process.

[0093] In S360, the control device 6 determines whether the count value Ci is less than or equal to the first threshold value TH1c. If Ci≤TH1c, the process proceeds to S370, and if Ci>TH1c, the process proceeds to S390. TH1c is set to a relatively small value of approximately 2 to 5, for example.

[0094] In S370, the control device 6 updates the reference orientation fαi using the observed orientation αi.

[0095] In the next S380 , the control device 6 initializes the count value Ci to 1 and ends the process.

[0096] In S390 , the control device 6 counts down the count value Ci and ends the process.

[0097] In S400, similar to S330, the control device 6 determines whether the observation orientation αi and the reference orientation fαi are considered to be in the same orientation. If the control device 6 determines that they are considered to be in the same orientation, the process proceeds to S410. If not, the process proceeds to S420.

[0098] In S410 , the control device 6 counts up the count value Ci and ends the process.

[0099] In S420, the control device 6 determines whether the count value Ci is greater than or equal to the second threshold value TH2c. If Ci ≥ TH2c, the process proceeds to S430, and if Ci < TH2c, the process proceeds to S440. The second threshold value TH2c may be the same as or different from the first threshold value TH1c.

[0100] In S430 , the control device 6 counts down the count value Ci and ends the process.

[0101] In S440 , the control device 6 initializes the parameters Ci, fαi, and maxPi used in the reference update process and ends the process.

[0102] Specifically, when the received power Pi at the observation point Mi is greater than or equal to the maximum power maxPi, both the reference bearing fαi and the count value Ci are manipulated. Specifically, in S330 to S390, if the observed bearing αi at the observation point Mi with the maximum received power Pi is considered identical to the current reference bearing fαi, the reference bearing fαi is updated using this observed bearing αi, and the count value Ci is incremented. If the observed bearing αi differs from the current reference bearing fαi, and the count value Ci is greater than the first threshold THc1, the reference bearing fαi is not updated, and the count value Ci is decremented. Furthermore, if the count value Ci is less than the first threshold THc1, the reference bearing fαi is updated, and the count value Ci is initialized to 1.

[0103] If the received power Pi at the observation point Mi is less than the maximum power maxPi, the reference bearing fαi is not updated, and only the count value Ci is manipulated. Specifically, in S400-S440, if the observed bearing αi is considered to be the same as the current reference bearing fαi, the count value Ci is incremented. If the observed bearing αi differs from the current reference bearing fαi, the count value Ci is decremented if the count value Ci is greater than the second threshold TH2c. Furthermore, if the count value Ci is less than the second threshold TH2c, this indicates that the detection frequency of the observation point Mi in the bearing with the maximum power maxPi has decreased. Therefore, the parameters Ci, fαi, and maxPi are initialized to restart the observation from the beginning. Specifically, for example, Ci is set to 1, and fαi and maxPi are set to 0.

[0104] In this way, the time series of observation points is processed in the benchmark update process. As a result of the benchmark update process, the direction of the observation point Mi where the maximum received power is detected is defined as the reference direction fαi. The higher the frequency with which the observation point Mi is detected in the direction considered to be the same as the reference direction fαi, the larger the count value Ci becomes.

[0105] Back to Figure 13 In S204, following S202, the control device 6 determines, based on the processing results of S202, whether the count value Ci is greater than or equal to the threshold value THc and whether the observed bearing αi is considered to be the same as the reference bearing fαi. Furthermore, the threshold value THc is set to a value greater than or equal to 1 and less than the second threshold value TH2c. If the control device 6 makes an affirmative determination, the process proceeds to S240; if the determination is negative, the process proceeds to S210.

[0106] Specifically, if the observed bearing αi and the reference bearing fαi are considered to be in the same direction and the frequency of detecting the observation point Mi in the reference bearing fαi is relatively high, phase aliasing is assumed to be absent and the observed bearing αi is used as the final bearing ψi. In all other cases, aliasing determination is performed based on the headwise differences dαi and dβi.

[0107] In S255 , which is executed when a negative determination is made in either S150 or S160 , the control device 6 initializes all parameters fαi, maxPi, and Ci used in the reference update process, and shifts the process to S260 .

[0108] In addition, S202 corresponds to a reference orientation setting unit, and S204 corresponds to a sequence determination unit.

[0109] [2-3. Effect]

[0110] According to the second embodiment described in detail above, the effect (1a) of the first embodiment described above is achieved, and the following effects are achieved.

[0111] (2a) In the second embodiment, aliasing determination is performed using received power Pi for a series of observation points Mi detected over multiple processing cycles, thereby improving determination accuracy. Specifically, when phase aliasing occurs, a target object exists at the boundary of the detection range that deviates from the center of the radiation pattern. The received power Pi at the observation point Mi detected when phase aliasing occurs is lower than the received power Pi detected at the same location when phase aliasing does not occur. By utilizing this fact, determination accuracy can be improved.

[0112] [2-4. Modifications]

[0113] In the second embodiment, the reference update process increments and decrements the count value Ci using the received power Pi and the observed azimuth αi at the observation point Mi. However, the relative velocity Vri of the observation point Mi can also be used instead of the received power Pi. Specifically, the relative velocity detected for the observation point Mi is the range-direction component of the velocity at the observation point Mi. Therefore, even if the velocity at the observation point Mi is constant, the relative velocity is maximum when it is located in front of the vehicle, and decreases as the angle from the front of the vehicle increases. The relative velocity Vri of the observation point Mi detected in the presence of phase aliasing is smaller than the relative velocity Vri detected at the same location in the absence of phase aliasing. Utilizing this fact can improve determination accuracy.

[0114] [3. Other embodiments]

[0115] As mentioned above, although embodiment of this disclosure was described, this disclosure is not limited to the said embodiment, Various deformation|transformation can be carried out.

[0116] (3a) In the above embodiment, the radar device 2 transmits radar waves toward the front of the vehicle VH. However, the transmission direction of the radar waves is not limited to the front of the vehicle VH. For example, in the first embodiment, the radar device 2 may transmit radar waves toward at least one of the front, right front, left front, rear, right rear, left rear, right side, and left side of the vehicle VH. In the second embodiment, the radar waves may also be transmitted toward at least one of the front and rear of the vehicle VH.

[0117] (3b) In the above embodiment, radar device 2 employs the FMCW method. However, the radar method of radar device 2 is not limited to FMCW. For example, dual-frequency CW, FCM, or pulse modulation may also be employed. FCM is the abbreviation for Fast-Chirp Modulation.

[0118] (3c) In the above embodiment, the axis misalignment calculation process executed by the control device 6 calculates the stable axis misalignment γ based on the installation state of the radar device 2. However, the present disclosure is not limited to the above embodiment. For example, a tilt sensor or the like may be used to include the temporary tilt of the vehicle body due to the pitch or roll of the vehicle body in the axis misalignment γ.

[0119] (3d) In the above embodiment, in steps S230 and S240, which correspond to the processing execution unit, a correction process is performed to correct the observation direction based on the determination result of the presence or absence of phase aliasing. However, the present disclosure is not limited to the above embodiment. For example, a reporting process for reporting the determination result may be performed instead of or in addition to the correction process.

[0120] (3e) The control device 6 and the method thereof described in the present disclosure may also be implemented by a special-purpose computer, which is provided by constituting a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control device 6 and the method thereof described in the present disclosure may also be implemented by a special-purpose computer, which is provided by constituting a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control device 6 and the method thereof described in the present disclosure may also be implemented by one or more special-purpose computers, which are constituted by a combination of a processor and a memory programmed to execute one or more functions and a processor composed of one or more hardware logic circuits. In addition, a computer program may also be stored as an instruction executed by a computer in a non-migratable tangible recording medium that can be read by a computer. In the method for realizing the functions of each part included in the control device 6, it is not necessarily necessary to include software, and all of its functions may also be realized using one or more hardware.

[0121] (3f) It is also possible to implement multiple functions of one component of the above-mentioned embodiment by multiple components, or to implement one function of one component by multiple components. In addition, it is also possible to implement multiple functions of multiple components by one component, or to implement one function implemented by multiple components by one component. In addition, it is also possible to omit a part of the structure of the above-mentioned embodiment. In addition, it is also possible to add or replace at least a part of the structure of the above-mentioned embodiment with respect to the structure of other above-mentioned embodiments.

[0122] (3g) In addition to the above-mentioned aliasing determination device, the present disclosure can also be implemented in various forms, such as a system that uses the aliasing determination device as a component, a program for causing a computer to function as the aliasing determination device, a non-transferable physical recording medium such as a semiconductor memory that records the program, and an aliasing determination method.

Claims

1. An aliasing determination device, comprising: The information acquisition unit is configured to repeatedly acquire observation point information for an object existing within a predetermined detection range from a radar device mounted on the vehicle, wherein At least one of a horizontal direction and a vertical direction is used as a designated direction, the observation point information includes an observation point and an observation direction, and the observation direction is an observation direction of the observation point relative to the designated direction; an axial offset acquiring unit configured to: determine the orientation of the radar device when the radar device is mounted at a reference position as a mounting reference direction, determine the actual orientation of the radar device as an actual mounting direction, and acquire an axial offset amount of the actual mounting direction relative to the mounting reference direction in the specified direction; a target object determination unit configured to determine whether a target object exists in the mounting reference direction of the vehicle; an aliasing calculation unit configured to calculate an aliasing azimuth, the aliasing azimuth being an azimuth estimated when phase aliasing exists in the observation azimuth included in the observation point information; as well as a transient determination unit configured to perform phase aliasing determination when a target object exists in the mounting reference direction of the vehicle, the phase aliasing determination being for determining whether phase aliasing exists in the observation direction of the observation point; The instantaneous determination unit is configured as follows: Calculating a first difference value and a second difference value, wherein the first difference value is a difference between the observation azimuth and the mounting reference direction, and the second difference value is a difference between the aliasing azimuth and the mounting reference direction; If the first difference value is greater than the second difference value, determining that the aliasing azimuth is closer to the mounting reference direction than the observation azimuth and phase aliasing exists in the observation azimuth, and setting the aliasing azimuth as the actual azimuth of the observation point; as well as When the first difference value is equal to or smaller than the second difference value, it is determined that the observation azimuth is closer to the mounting reference direction than the aliasing azimuth and phase aliasing does not exist in the observation azimuth, and the observation azimuth is set as the actual azimuth of the observation point.

2. The aliasing determination device according to claim 1, wherein: The aliasing determination device further includes a processing execution unit configured to execute a process based on a determination result of the transient determination unit. The processing execution unit executes at least one of a reporting process of reporting the determination result and a correction process of correcting the observation direction based on the determination result.

3. The aliasing determination device according to claim 1 or 2, wherein: The aliasing determination device further comprises: a reference direction setting unit configured to, when the time series of the observation directions includes a plurality of the observation directions that cannot be considered to be in the same direction, set the observation direction of the observation point information at which at least one of the received power and the relative speed with the vehicle is detected to be the maximum as the reference direction; as well as A sequence determination unit is configured to determine that the observation azimuth included in the observation point information acquired by the information acquisition unit is an actual azimuth when the observation azimuth is considered to be the same direction as the reference azimuth set by the reference azimuth setting unit.

4. The aliasing determination device according to claim 1 or 2, wherein: The aliasing determination device further includes a movement determination unit configured to determine whether the object indicated by the observation point information is a moving object. The instantaneous determination unit performs determination when it is determined that the object indicated by the observation point information is a moving object.

5. The aliasing determination device according to claim 1 or 2, wherein: The aliasing determination device further includes a directivity determination unit configured to determine whether the object indicated by the observation point information is located within a directivity range that provides a gain greater than a preset threshold value in the radiation pattern of the radar device. The instantaneous determination unit makes a determination when the aliasing direction is within the directional range.

6. The aliasing determination device according to claim 1 or 2, wherein: The aliasing determination device further includes a driving determination unit configured to determine whether the vehicle is traveling in a straight line. The instantaneous determination unit performs determination when the vehicle is traveling in a straight line.

7. The aliasing determination device according to claim 1 or 2, wherein: The aliasing determination device further includes an axis offset detection unit configured to detect the axis offset amount of the radar device based on the observation point information. The axis deviation acquisition unit acquires the axis deviation amount from the axis deviation detection unit, The axis deviation detecting unit detects the axis deviation amount using the observation point information after the observation orientation is corrected based on the determination result of the instantaneous determination unit.

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