Axis offset estimation device

Abstract

The present invention relates to an axis offset estimation device. The axis offset estimation device (4) for estimating the axis offset angle of a radar device mounted on a mobile body comprises an acquisition unit (S10), an extraction unit (S20), a device system coordinate unit (S30, S210) and an estimation unit (S30, S220, S230, S320, S330). The estimation unit is configured to estimate the axis offset angle using a relational expression. The relational expression is an equation that is established between at least one unknown parameter of the axis offset angle of the coordinate axis of the radar device around an object axis and at least one element contained in the device system coordinates of a road surface reflection point, wherein the object axis is at least one of a horizontal axis as the coordinate axis of the mobile body and a travel direction axis.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This international application claims the benefit of priority based on Japanese Patent Application No. 2019-186313 filed with the Japan Patent Office on October 9, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a technology for estimating an axis deviation angle of a radar device that detects the orientation and relative speed of an object. Background Art

[0004] In a vehicle-mounted radar device, the setting state may change for some reason, thereby causing the central axis of the radar beam to shift, which is called axis deviation. For example, the following patent document 1 discloses a technology for estimating the axis deviation angle of the vehicle-mounted radar device based on the maximum reception intensity of the reflected wave from the vicinity of the vehicle when axis deviation occurs.

[0005] Patent Document 1: Japanese Patent No. 6321448

[0006] However, as a result of detailed studies by the inventors, it has been found that the conventional device described in Patent Document 1 has a problem in that the estimation accuracy of the axis deviation angle decreases when there is an object with a high reflection intensity such as a manhole at a distance from the vehicle. Summary of the invention

[0007] One aspect of the present disclosure is to provide a technique for improving the estimation accuracy of a shaft offset angle.

[0008] One aspect of the present disclosure is an axis offset estimation device for estimating an axis offset angle of a radar device mounted on a mobile object. The axis offset estimation device includes an acquisition unit, an extraction unit, a device-system coordinate unit, and an estimation unit.

[0009] The acquisition unit is configured to acquire reflection point information for each of the plurality of reflection points detected by the radar device, wherein the reflection point information at least includes an azimuth angle of the relevant reflection point and a distance between the radar device and the reflection point, wherein the azimuth angle of the relevant reflection point is a horizontal angle and a vertical angle obtained with the beam direction as a reference. The beam direction is a direction along the central axis of the radar beam. The extraction unit is configured to extract at least one road surface reflection point detected by reflection from the road surface from among the plurality of reflection points based on at least the reflection point information.

[0010] The device system coordinate unit is configured to determine the device system coordinate for each road surface reflection point based on the reflection point information, wherein the device system coordinate is a three-dimensional coordinate based on the coordinate axis of the radar device. The estimation unit is configured to estimate the axis offset angle using a relational expression. The relational expression is an expression that is established between at least one unknown parameter including the axis offset angle of the coordinate axis of the radar device around an object axis and at least one element included in the device system coordinate of the road surface reflection point, wherein the object axis is one of a horizontal axis and a traveling direction axis as the coordinate axis of the moving body.

[0011] As a result, the axis misalignment estimation device estimates the axis misalignment angle mathematically, and thus can suppress estimation errors of the axis misalignment angle compared to a conventional device that estimates the axis misalignment angle based on the maximum reception intensity of reflected waves from the vicinity of the vehicle when the axis misalignment occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a block diagram showing the structure of a vehicle control system.

[0013] Figure 2 This is an explanatory diagram for explaining the irradiation range of radar waves in the horizontal direction.

[0014] Figure 3 This is an explanatory diagram for explaining the irradiation range of radar waves in the vertical direction.

[0015] Figure 4 It is an explanatory diagram for explaining the axis deviation of the radar device.

[0016] Figure 5 It is an explanatory diagram for explaining the vertical axis offset angle and the roll angle.

[0017] Figure 6 is a flowchart of the axis offset estimation process.

[0018] Figure 7 It is a flowchart of the road surface reflection extraction process.

[0019] Figure 8 This is a flowchart of the angle estimation process according to the first embodiment.

[0020] Fig. 9 This is an explanatory diagram for explaining the principle of estimating the vertical axis offset angle in the first embodiment.

[0021] Fig.10 This is a flowchart of the angle estimation process of Modification Example 1.

[0022] Fig.11 This is an explanatory diagram for explaining the principle of estimating the roll angle in the first modification.

[0023] Fig.12 This is a flowchart of the angle estimation process according to the second embodiment.

[0024] Fig.13 It is an explanatory diagram for explaining the principle of estimating the vertical axis offset angle in the second embodiment.

[0025] Fig.14 This is a flowchart of the angle estimation process of Modification Example 2.

[0026] Fig.15 This is an explanatory diagram for explaining the principle of estimating the roll angle in the second modification.

[0027] Fig.16 This is a flowchart of the angle estimation process of Modification Example 4.

[0028] Fig.17 This is an explanatory diagram for explaining the principle of estimating the vertical axis offset angle and the roll angle in Modification 4. DETAILED DESCRIPTION

[0029] Hereinafter, the exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, the "vertical" mentioned below is not limited to the "vertical" in the strict sense, and it may not be strictly "vertical" as long as the same effect is achieved. The same also applies to the "horizontal" and "aligned" mentioned below.

[0030] [1. First embodiment]

[0031] [1-1. Structure]

[0032] Figure 1 The vehicle control system 1 shown is a system mounted on a vehicle VH as a mobile body. The vehicle control system 1 includes a radar device 2, a vehicle-mounted sensor group 3, a signal processing unit 4, and an assist execution unit 5. In addition, the vehicle control system 1 may also include an axis deviation notification device 51 and a mounting angle adjustment device 52. Hereinafter, the vehicle VH on which the vehicle control system 1 is mounted is also referred to as the host vehicle VH. In addition, the vehicle width direction of the host vehicle VH is also referred to as the horizontal direction, and the vehicle height direction is also referred to as the vertical direction.

[0033] like Figure 2 as well as Figure 3 As shown, the radar device 2 is mounted on the front side of the vehicle VH. The radar device 2 irradiates radar waves within a predetermined angle range Ra in the horizontal direction in front of the vehicle VH and within a predetermined angle range Rb in the vertical direction in front of the vehicle VH. The radar device 2 generates reflection point information related to the reflection point where the radar wave is reflected by receiving the reflected wave of the irradiated radar wave.

[0034] In addition, the radar device 2 may be a so-called millimeter wave radar that uses electromagnetic waves in the millimeter wave band as radar waves, a laser radar that uses lasers as radar waves, or a sonar that uses sound waves as radar waves. In short, the antenna unit that transmits and receives radar waves is configured to detect the arrival direction of the reflected wave in any of the horizontal and vertical directions. The antenna unit may also include array antennas arranged in the horizontal and vertical directions.

[0035] The radar device 2 is installed so that the beam direction coincides with the front-rear direction of the vehicle VH, that is, the traveling direction, and detects various targets existing in front of the vehicle VH. The beam direction refers to the direction along the central axis CA of the irradiated radar beam.

[0036] The reflection point information generated by the radar device 2 includes at least the azimuth of the reflection point and the distance of the reflection point. The distance of the reflection point refers to the distance between the radar device 2 and the reflection point. In addition, the radar device 2 can also be configured to detect the relative speed of the reflection point relative to the vehicle VH and the reception intensity of the radar beam reflected by the reflection point. The reflection point information can also include the relative speed and reception intensity of the reflection point.

[0037] like Figure 2 , 3 As shown in FIG. 1 , the azimuth of the reflection point refers to at least one of the horizontal angle (hereinafter referred to as the horizontal angle) Hor and the vertical angle (hereinafter referred to as the vertical angle) Ver where the reflection point exists, which are obtained based on the beam direction, and the beam direction is the direction along the central axis CA of the radar beam. In the present embodiment, both the vertical angle Ver and the horizontal angle Hor are included in the reflection point information as information indicating the azimuth of the reflection point.

[0038] also, Figure 4 The vertical axis offset is shown, that is, the axis offset of the radar device 2 around the left-right axis. The axis offset refers to the offset of the coordinate axis of the radar device 2 when the radar device 2 is actually installed on the vehicle VH relative to the coordinate axis of the radar device 2 when the radar device 2 is correctly installed on the vehicle VH. The axis offset angle represents the magnitude of such axis offset in degrees.

[0039] Here, if Figure 5 As shown, the coordinate axes of the radar device 2 refer to the vertical axis Zs extending along the vertical direction of the radar device 2, the horizontal axis Ys extending along the horizontal direction of the radar device 2, and the front-rear axis Xs extending along the front and rear direction of the radar device 2 when the radar device 2 is installed in the vehicle VH. The vertical axis Zs, the horizontal axis Ys, and the front-rear axis Xs are orthogonal to each other. In the present embodiment in which the radar device 2 is provided in front of the vehicle VH, the front-rear axis Xs is equal to the central axis CA.

[0040] On the other hand, the coordinate axes of the host vehicle VH are the vertical axis Zc extending in the vertical direction, the horizontal axis Yc extending in the horizontal direction, and the traveling direction axis Xc extending in the traveling direction of the host vehicle VH. The vertical axis Zc, the horizontal axis Yc, and the traveling direction axis Xc are orthogonal to each other.

[0041] For example, in the present embodiment, when the radar device 2 is correctly mounted on the vehicle VH, the central axis CA is aligned with the traveling direction of the vehicle VH as described above. In other words, when the radar device 2 is correctly mounted on the vehicle VH, the direction of the coordinate axis of the radar device 2 is aligned with the direction of the coordinate axis of the vehicle VH.

[0042] The axis offset in this embodiment includes a vertical axis offset and a roll axis offset.

[0043] Here, the vertical axis offset refers to a state in which the vertical axis Zs, which is the coordinate axis of the radar device 2, and the vertical axis Zc, which is the coordinate axis of the vehicle VH, are offset. The axis offset angle when the vertical axis is offset is referred to as the vertical axis offset angle α. p . Vertical axis offset angle α p is the so-called pitch angle α p , is the axis deviation angle of the coordinate axis of the radar device 2 (i.e., the left-right axis Ys) about the horizontal axis Yc of the vehicle VH. In other words, the vertical axis deviation angle α p is the axis deviation angle when an axis deviation occurs around the left-right axis Ys of the radar device 2. Figure 5 It can be seen that the vertical axis offset angle α p It may be an angle indicating the magnitude of the offset between the front-rear axis Xs, which is the coordinate axis of the radar device 2 , and the traveling direction axis Xc, which is the coordinate axis of the host vehicle VH.

[0044] On the other hand, the roll axis offset refers to a state in which the left-right axis Ys as the coordinate axis of the radar device 2 and the horizontal axis Yc as the coordinate axis of the host vehicle VH are offset. The axis offset angle when the roll axis is offset is referred to as the roll angle α. r In other words, the roll angle α r is the axis deviation angle of the coordinate axis of the radar device 2 (ie, the front-rear axis Xs) about the traveling direction axis Xc of the host vehicle VH. r It is an axis deviation angle when an axis deviation around the front-rear axis Xs of the radar device 2 occurs.

[0045] In this embodiment, the radar device 2 adopts the FMCW method, alternately sends radar waves in the uplink modulation interval and radar waves in the downlink modulation interval according to a preset modulation period, and receives reflected radar waves. FMCW is the abbreviation of Frequency Modulated Continuous Wave. In this embodiment, the radar device 2 detects the azimuth angle of the reflection point, that is, the horizontal angle Hor and the vertical angle Ver, the distance to the reflection point, the relative speed to the reflection point, and the received power of the received radar wave as the reflection point information according to each modulation period as described above. Hereinafter, the received power of the received radar wave is referred to as the reflected power.

[0046] The vehicle-mounted sensor group 3 is at least one sensor mounted on the vehicle VH in order to detect the state of the vehicle VH, etc. The vehicle-mounted sensor group 3 may include a vehicle speed sensor. The vehicle speed sensor is a sensor that detects the vehicle speed based on the rotation of the wheels. In addition, the vehicle-mounted sensor group 3 may also include a camera. The camera captures the same range as the irradiation range of the radar wave of the radar device 2. In addition, the vehicle-mounted sensor group 3 may also include an acceleration sensor. The acceleration sensor detects the acceleration of the vehicle VH. In addition, the vehicle-mounted sensor group 3 may also include a yaw rate sensor. The yaw rate sensor detects the speed of change of the yaw angle indicating the inclination of the traveling direction of the vehicle VH relative to the front of the vehicle VH.

[0047] The signal processing unit 4 has a microcomputer including a CPU 41, and semiconductor memories such as ROM 43, RAM 44, and flash memory (hereinafter referred to as memory 42). The various functions of the signal processing unit 4 are realized by the CPU 41 executing a program stored in a non-migrating physical recording medium. In this example, the memory 42 is equivalent to a non-migrating physical recording medium storing the program. In addition, by executing the program, the method corresponding to the program is executed. In addition, the number of microcomputers constituting the signal processing unit 4 can be one or more. In addition, the method for realizing the various functions of the signal processing unit 4 is not limited to software, and one or more hardware can also be used to realize part or all of its elements. For example, in the case where the above-mentioned functions are realized by an electronic circuit as hardware, the electronic circuit can also be realized by a digital circuit containing many logic circuits, or an analog circuit, or a combination thereof.

[0048] The processing executed by the signal processing unit 4 includes at least a target object recognition process and an axis offset estimation process.

[0049] The object mark recognition process detects the lane in which the host vehicle VH is traveling, the preceding vehicle traveling in the same lane as the host vehicle VH, other vehicles, obstacles, etc., based on the reflection point information obtained from the radar device 2 and various information obtained from the vehicle-mounted sensor group 3. The processing result of the object mark recognition process is output to the assistance execution unit 5, etc.

[0050] The axial offset estimation process detects the axial offset angle of the beam direction of the radar device 2 relative to the traveling direction of the host vehicle VH. Details will be described later. The signal processing unit 4 that executes the axial offset estimation process corresponds to the axial offset estimation device.

[0051] The assistance execution unit 5 controls various vehicle-mounted devices based on the processing results of the object mark recognition processing executed by the signal processing unit 4 to execute the prescribed driving assistance. The various vehicle-mounted devices that become the control objects may include a monitor that displays images, an audio device that outputs alarm sounds and guidance sounds. In addition, it may also include a control device that controls the internal combustion engine, power transmission mechanism, brake mechanism, etc. of the vehicle VH.

[0052] The axle misalignment notification device 51 is a sound output device provided in the vehicle cabin, and outputs a warning sound to the passengers of the host vehicle VH. Alternatively, an audio device or the like included in the assist execution unit 5 may be used as the axle misalignment notification device 51.

[0053] The mounting angle adjustment device 52 includes a motor and a gear mounted on the radar device 2. The mounting angle adjustment device 52 rotates the motor according to the drive signal output from the signal processing unit 4. Thus, the rotational force of the motor is transmitted to the gear, and the radar device 2 is rotated around the axis along the horizontal direction and the axis along the vertical direction.

[0054] [1-2. Processing]

[0055] (1-1) Axis offset estimation processing

[0056] Next, use Figure 6 The flowchart of FIG. 4 illustrates the axis deviation estimation process performed by the signal processing unit 4. The process is started when the ignition switch is turned on. In addition, the vertical axis deviation angle (ie, the pitch angle) α which is estimated as the axis deviation angle is hereinafter p The following example is used to illustrate this.

[0057] When this process is started, in S10, the signal processing unit 4 acquires the reflection point information from the radar device 2. Hereinafter, the reflection point determined based on the reflection point information is referred to as the acquired reflection point. In addition, the signal processing unit 4 acquires various detection results including the vehicle speed Cm from the vehicle-mounted sensor group 3.

[0058] In S20, the signal processing unit 4 performs a road surface reflection extraction process. The road surface reflection extraction process is a process for extracting reflection points on the road surface, that is, road surface reflection points, from the acquired reflection points. The road surface reflection points refer to reflection points detected by reflection from the passage surface. The details of the road surface reflection extraction process will be described later.

[0059] In S30, the signal processing unit 4 performs an angle estimation process. The angle estimation process is a process of estimating the axis deviation angle of the radar device 2. In other words, in this embodiment, the signal processing unit 4 estimates the vertical axis deviation angle α. p The details of the angle estimation process will be described later.

[0060] In S35, the signal processing unit 4 determines whether the axis offset angle estimated in S30 needs to be adjusted. p If the angle is greater than a predetermined threshold angle, the signal processing unit 4 determines that the vertical axis is offset by an angle α. p Need to adjust. Offset angle α on the vertical axis p If the angle is less than the threshold value and adjustment is not required, the signal processing unit 4 moves the process to S70 and adjusts the vertical axis offset angle α. p If the angle is equal to or greater than the threshold angle and adjustment is necessary, the process proceeds to S40 .

[0061] In S40, the signal processing unit 4 determines whether the axis offset angle estimated in S30 is within the adjustable range of the mounting angle adjustment device 52. If the axis offset angle estimated in S30 is within the adjustable range, the signal processing unit 4 moves the process to S50, and if it is not within the adjustable range, moves the process to S60. In other words, when the vertical axis offset angle α is p If it is within the adjustable range, the signal processing unit 4 shifts the process to S50.

[0062] In S50, the signal processing unit 4 adjusts the radar mounting angle to the axis offset angle estimated in S30 by the mounting angle adjustment device 52. In other words, the signal processing unit 4 rotates the radar device 2 around the left-right axis Ys of the radar device 2 by the vertical axis offset angle α. p The mounting angle of the radar device 2 is adjusted by the amount of. Then, the signal processing unit 4 ends the axis offset estimation process.

[0063] In addition, the signal processing unit 4 may calculate the azimuth obtained by correcting the azimuth of the reflection point acquired in S10 by the axis offset angle estimated in S30 in a process different from the actual axis offset estimation process. Furthermore, the signal processing unit 4 may perform the above-mentioned target object recognition process based on the corrected azimuth.

[0064] In S60, the signal processing unit 4 outputs diagnostic information indicating that the axis offset has occurred in the radar device 2 to an external device of the signal processing unit 4. Hereinafter, the diagnostic information indicating that the axis offset has occurred in the radar device 2 is referred to as the axis offset diagnosis. The external device may also be the axis offset notification device 51. The signal processing unit 4 may also output the axis offset diagnosis to the axis offset notification device 51, for example. The axis offset notification device 51 may also output a warning sound according to the axis offset diagnosis.

[0065] In S70, the signal processing unit 4 determines whether the ignition switch is turned off. Here, if the ignition switch is not turned off, the signal processing unit 4 moves the process to S10. On the other hand, if the ignition switch is turned off, the signal processing unit 4 ends the own axis offset estimation process.

[0066] (2-2) Road surface reflection extraction and processing

[0067] Next, use Figure 7 The flowchart of FIG. 1 illustrates the road surface reflection extraction process executed by the signal processing unit 4 in S20 of the axis deviation estimation process.

[0068] In S100, the signal processing unit 4 acquires detection results of the state of the host vehicle VH and the like by various sensors from the vehicle-mounted sensor group 3. The detection results mentioned here may include the vehicle speed, acceleration, yaw angle and the like of the host vehicle VH.

[0069] In S110 , the signal processing unit 4 determines whether to extract a road surface reflection point based on the detection results of the state of the host vehicle VH and the like acquired from the vehicle-mounted sensor group 3 .

[0070] Specifically, the signal processing unit 4 determines whether the body of the host vehicle VH is stable relative to the road surface based on the detection result of the state of the host vehicle VH, and determines to extract the road surface reflection point if the body of the host vehicle VH is stable relative to the road surface.

[0071] The state in which the vehicle body of the host vehicle VH is stable relative to the road surface may be a state in which the vehicle body of the host vehicle VH is not tilted relative to the road surface, or a state in which the vehicle body of the host vehicle VH is not moving up and down relative to the road surface. In other words, the state in which the vehicle body of the host vehicle VH is stable relative to the road surface may be a state in which the host vehicle VH is not traveling on a curve with a large curvature, or a state in which the host vehicle VH is not traveling on a road with a large unevenness.

[0072] Here, when the vehicle is not traveling on a road with large bumps, it can be said that the vehicle is traveling on a flat road. In this case, it is considered that the speed and acceleration are greater than when the vehicle is traveling on a road with large bumps. On the other hand, when the vehicle is not traveling on a curve with large curvature, it can be said that the vehicle is close to traveling on a straight road. In this case, the speed and acceleration are often greater than when the vehicle is traveling on a curve with large curvature, and the speed of change of the yaw angle is smaller than when the vehicle is traveling on a curve with large curvature.

[0073] Therefore, the signal processing unit 4 may also determine that the body of the vehicle VH is in a stable state relative to the road surface when the vehicle speed of the vehicle VH is above a predetermined vehicle speed threshold, and determine to extract the road surface reflection point. In other words, the signal processing unit 4 may also determine that the body of the vehicle VH is in an unstable state relative to the road surface when the vehicle speed of the vehicle VH is less than the vehicle speed threshold, and determine not to extract the road surface reflection point.

[0074] Similarly, the signal processing unit 4 may also determine that the body of the vehicle VH is in a stable state relative to the road surface when the acceleration of the vehicle VH is greater than a predetermined acceleration threshold, and determine to extract the road surface reflection point. Similarly, the signal processing unit 4 may also determine that the body of the vehicle VH is in a stable state relative to the road surface when the rate of change of the yaw angle of the vehicle VH is less than a predetermined threshold, and determine to extract the road surface reflection point.

[0075] When it is determined that a road surface reflection point is to be extracted, the signal processing unit 4 moves the process to S120 , and when it is determined that a road surface reflection point is not to be extracted, the signal processing unit 4 moves the process to S180 .

[0076] In S120, the signal processing unit 4 selects one acquisition reflection point from all acquisition reflection points. The signal processing unit 4 executes the processes of S130 to S195 for the selected acquisition reflection point (hereinafter, simply referred to as an acquisition reflection point).

[0077] In S130, the signal processing unit 4 determines whether the acquired reflection point is within the extraction range, which is a specified azimuth range including the central axis CA in the horizontal direction. If the acquired reflection point is within the azimuth range, the signal processing unit 4 moves the processing to S140, and if the selected acquired reflection point is not within the azimuth range, the processing moves to S190.

[0078] In other words, the signal processing unit 4 extracts the acquisition reflection points located within the extraction range from the plurality of acquisition reflection points. The extraction range can be determined, for example, as a range of ±several degrees to several tens of degrees including the central axis CA in the horizontal direction. In other words, in the present embodiment in which the radar device 2 is provided in front of the vehicle VH, the extraction range is determined as a prescribed range near the traveling direction of the vehicle VH. The extraction range can also be determined in advance by experiments, etc. The extraction range is pre-stored in the memory 42.

[0079] In S140, the signal processing unit 4 determines whether the distance between the selected acquisition reflection point and the radar device 2 is less than a predetermined distance threshold. If the distance between the selected acquisition reflection point and the radar device 2 is less than the distance threshold, the signal processing unit 4 moves the process to S150, and if the distance between the selected acquisition reflection point and the radar device 2 is greater than the distance threshold, the signal processing unit 4 moves the process to S190.

[0080] In other words, the signal processing unit 4 extracts the acquired reflection points whose distance from the radar device 2 is smaller than the distance threshold. The distance threshold is stored in the memory 42 in advance.

[0081] In S150, the signal processing unit 4 determines whether the acquired reflection point is a stationary reflection point. If the acquired reflection point is a stationary reflection point, the signal processing unit 4 moves the process to S160, and if the acquired reflection point is not a stationary reflection point, the process moves to S190. A stationary reflection point refers to a reflection point where radar waves are reflected by a stationary object.

[0082] In other words, the signal processing unit 4 extracts the stationary reflection points from the acquired reflection points. Specifically, the signal processing unit 4 can use the vehicle speed Cm acquired in S10, set the relative speed included in the reflection point information to q, set the preset lower speed threshold to ε1, and set the upper speed threshold to ε2, and extract the acquired reflection points that satisfy ε1≤q / Cm<ε2 as stationary reflection points. That is, the acquired reflection points in which the ratio of the vehicle speed Cm to the relative speed q is greater than ε1 and less than ε2, which is a predetermined speed threshold range, can be extracted as stationary reflection points.

[0083] When the direction from the stationary reflection point toward the radar device 2 is consistent with the beam direction, the vehicle speed Cm and the relative speed q of the reflection point are the same, and the direction of the relative speed q is opposite to the vehicle speed Cm, so q / Cm = -1. In this way, the reflection point with q / Cm = -1 is considered to be a stationary reflection point.

[0084] However, the vehicle speed Cm obtained from the vehicle-mounted sensor group 3 is not necessarily consistent with the actual vehicle speed due to wheel slippage, etc. In addition, the relative speed q detected by the radar device 2 also contains errors. Therefore, there is a situation where q / Cm=-1 is not necessarily true even at a stationary reflection point. The lower speed threshold ε1 and the upper speed threshold ε2 can also be appropriately set in consideration of these effects.

[0085] In S160, the signal processing unit 4 determines whether the reflected power at the reflection point is less than a predetermined power threshold. If the reflected power at the reflection point is less than the power threshold, the signal processing unit 4 moves the process to S170, and if the reflected power at the reflection point is greater than the power threshold, the signal processing unit 4 moves the process to S190.

[0086] In other words, the signal processing unit 4 extracts the reflection points where the reflection power is less than the power threshold. It is considered that the reflection power from the road surface is smaller than the reflection power from other vehicles, for example. The power threshold can be appropriately determined based on such reflection power from the road surface. For example, the power threshold can also be determined in advance through experiments, etc. The power threshold is pre-stored in the memory 42.

[0087] In S170, the signal processing unit 4 determines whether the acquired reflection point is recognized as a road surface in the captured image of the camera. If the acquired reflection point is estimated as a road surface in the captured image, the signal processing unit 4 moves the process to S180, and if the acquired reflection point is not estimated as a road surface in the captured image, the process moves to S195.

[0088] In other words, the signal processing unit 4 extracts the acquired reflection points recognized as the road surface in the captured image. In addition, the signal processing unit 4 may also be configured to acquire the captured image of the camera and estimate the azimuth range recognized as the road surface in the captured image in a process different from the own-axis offset estimation process.

[0089] In S180 , the signal processing unit 4 determines that the acquired reflection point is a road surface reflection point, stores the three-dimensional coordinates of the acquired reflection point as a road surface reflection point in the memory 42 , and moves the process to S195 .

[0090] In S190 , the signal processing unit 4 determines that the acquired reflection point is not a road surface reflection point, does not store the acquired reflection point in the memory 42 , and moves the process to S195 .

[0091] In S195, the signal processing unit 4 determines whether the confirmation of whether all the acquired reflection points are road surface reflection points has been completed. Here, if the confirmation has not been completed, the signal processing unit 4 moves the processing to S110 and repeats the processing of S110-S195. On the other hand, if the confirmation has been completed, the signal processing unit 4 ends the road surface reflection extraction processing.

[0092] In other words, in the road surface extraction process of the present embodiment, among the acquired reflection points, those that satisfy all of the following (a) to (d) are extracted as road surface reflection points.

[0093] (a) It is located within the extraction range including the central axis CA in the horizontal direction.

[0094] (b) The distance to the radar device 2 is smaller than the distance threshold.

[0095] (c) is the stationary reflection point.

[0096] (d) The reflected power is less than the power threshold.

[0097] (e) Recognized as a road surface in the image captured by the camera.

[0098] In addition, the road surface reflection extraction process may also be configured to satisfy at least (a) of the above (a)-(e). In other words, the road surface reflection extraction process may also be configured to satisfy (a) and further satisfy at least one of (b)-(e). Alternatively, the road surface reflection extraction process may also be configured to satisfy at least (a) and (b). In other words, the road surface reflection extraction process may also be configured to satisfy (a) and (b), and the road surface reflection extraction process may also be configured to further satisfy at least one of (c)-(e).

[0099] [2-3. Angle estimation processing]

[0100] Next, use Figure 8 The flowchart of FIG. 1 illustrates the angle estimation process executed by the signal processing unit 4 in S30 of the axis deviation estimation process.

[0101] In S210, the signal processing unit 4 calculates the device coordinates of the road surface reflection point based on the reflection point information and using the distance and azimuth included in the reflection point information. The device coordinates refer to three-dimensional coordinates based on the coordinate axes of the radar device 2. The device coordinates are coordinates that have the horizontal distance (ys), the vertical distance (zs) on the plane orthogonal to the beam direction, and the distance (xs) in the above beam direction as elements. The signal processing unit 4 calculates the device coordinates (xs, ys, zs) for all road surface reflection points and stores them in the memory 42.

[0102] In S220 , the signal processing unit 4 estimates the axis offset angle included in the unknown parameters using a relational expression established between two unknown parameters including the axis offset angle and two elements included in the device system coordinates.

[0103] The axis deviation angle refers to the axis deviation angle of the coordinate axis of the radar device 2 around the target axis, which is one of the horizontal axis Yc and the traveling direction axis Xc, which are the coordinate axes of the host vehicle VH. As described above, in the present embodiment, the axis deviation angle of the coordinate axis of the radar device 2 around the horizontal axis Yc, that is, the vertical axis deviation angle α is estimated with the horizontal axis Yc, which is the coordinate axis of the host vehicle VH, as the target axis. p The method is described below.

[0104] The coordinate axis of the radar device 2 corresponding to the target axis is called the corresponding axis. The two elements included in the above-mentioned device-based coordinates refer to the elements related to the two coordinate axes of the radar device 2 included in the plane perpendicular to the corresponding axis among the three coordinate axes of the radar device 2. In other words, the two elements included in the above-mentioned device-based coordinates are equivalent to the coordinates of the projection point of the road surface reflection point projected onto the plane perpendicular to the corresponding axis among the three coordinate axes of the radar device 2, that is, the projection plane.

[0105] In estimating the vertical axis offset angle α p In the present embodiment, the coordinate axis corresponding to the horizontal axis Yc as the object axis among the three coordinate axes of the radar device 2 is the left-right axis Ys. That is, the elements (i.e., zs and xs) related to the up-down axis Zs and the front-back axis Xs of the radar device 2 included in the plane perpendicular to the left-right axis Ys as the corresponding axis among the three coordinate axes of the radar device 2 are equivalent to the two elements included in the above-mentioned device system coordinates. In other words, the two elements zs and xs included in the device system coordinates are equivalent to the coordinates of the projection point of the road surface reflection point projected onto the projection plane perpendicular to the left-right axis Ys.

[0106] like Fig. 9 As shown, the road surface reflection point is located on the road surface. In other words, the road surface reflection point is located on the same plane as the road surface. Therefore, it is considered that multiple road surface reflection points are arranged linearly on the projection surface. In other words, the following formula (1) holds.

[0107] [Number 1]

[0108] z s =α p x s +β p (1)

[0109] Formula (1) is a linear formula representing a straight line on the projection plane based on the front-rear axis Xs and the up-down axis Zs. p Represents the slope of the straight line, that is, the vertical axis offset angle α p . β p represents the intercept on the upper and lower axis Zs (i.e., Z intercept). The unknown number is α p and β p Since there are two unknowns, the vertical axis offset angle α is estimated based on at least two road surface reflection points. p In addition, the vertical axis offset angle α as an unknown number can also be estimated based on multiple road surface reflection points using the least square method or the like. p .

[0110] The signal processing unit 4 calculates the estimated vertical axis offset angle α p The data is stored in the memory 42 and the angle estimation process is terminated.

[0111] [1-3. Effect]

[0112] According to the first embodiment described in detail above, the following effects are achieved.

[0113] (1a) In S10, the signal processing unit 4 repeatedly obtains reflection point information for each of the multiple reflection points detected by the radar device 2. The reflection point information at least includes the azimuth of the relevant reflection point and the distance between the radar device 2 and the reflection point. The azimuth of the relevant reflection point is a horizontal angle and a vertical angle calculated based on the beam direction. In S20, the signal processing unit 4 extracts at least one road surface reflection point from the multiple reflection points based on at least the reflection point information.

[0114] In S210, the signal processing unit 4 determines the device system coordinates for each road surface reflection point based on the reflection point information. In S220, the signal processing unit 4 uses the coordinates of the device system including at least the axis offset angle (i.e., the vertical axis offset angle α). p ) of the two unknown parameters (i.e., α p and β p ) and the two elements (i.e., xs and zs) contained in the device coordinates of the road reflection point (i.e., equation (1)), to estimate the vertical axis offset angle α p . Vertical axis offset angle α p It is an axis deviation angle of the coordinate axis of the radar device 2 around the target axis (ie, the horizontal axis Yc) which is one of the horizontal axis Yc and the traveling direction axis Xc which are the coordinate axes of the host vehicle VH.

[0115] Here, the radar device 2 detects the device coordinates of each reflection point with high accuracy. The signal processing unit 4 arithmetically estimates the vertical axis offset angle α as the axis offset angle based on the device coordinates of the road surface reflection point. p .

[0116] As a result, the signal processing unit 4 mathematically estimates the axis deviation angle, so that the estimation error of the axis deviation angle can be suppressed compared with the conventional device that estimates the axis deviation angle based on the maximum reception intensity of the reflected wave from the vicinity of the vehicle when the axis deviation occurs. This is because in the conventional device, for example, when there is a manhole with a large reflection intensity in the distance, the estimation accuracy of the axis deviation angle may be reduced.

[0117] (1b) The two elements (i.e., xs and zs) included in the above-mentioned device-based coordinates are elements related to the two coordinate axes (i.e., the front-rear axis Xs and the up-down axis Zs) of the radar device 2 included in a plane perpendicular to the corresponding axis (i.e., the left-right axis Ys) among the three coordinate axes of the radar device 2. The corresponding axis is a coordinate axis of the radar device 2 corresponding to the target axis (i.e., Yc). Thus, since the offset angle is estimated based on the two-dimensional coordinate axes, the processing load of the signal processing unit 4 can be reduced compared to the case of using the device-based coordinates, which are three-dimensional coordinates.

[0118] (1c) The signal processing unit 4 may also be configured to obtain the detection result of the state of the vehicle VH from the vehicle-mounted sensor group 3 that detects the state of the vehicle VH in S110, and judge whether the body of the vehicle VH is stable relative to the road surface based on the detection result. Moreover, the signal processing unit 4 may also be configured to extract at least one road surface reflection point from multiple reflection points in S20 when it is judged that the body of the vehicle VH is stable relative to the road surface. As a result, it is difficult to extract reflection points on non-planar road surfaces such as inclined surfaces and concave-convex surfaces as road surface reflection points. That is, it is easy to extract reflection points on flat road surfaces as road surface reflection points, so the axis offset angle can be estimated with good accuracy based on the fact that the road surface reflection points are located on the same plane.

[0119] (1d) The signal processing unit 4 may be configured to extract at least one reflection point located within a predetermined azimuth range including the central axis CA of the radar beam in the horizontal direction as a road surface reflection point from among the plurality of reflection points in S130 based on the reflection point information.

[0120] As a result, since the road surface is considered to be at least located near the front of the traveling direction of the vehicle VH (ie, the direction of the central axis CA of the radar beam), the accuracy of extracting the reflection points on the road surface can be improved by appropriately determining the prescribed azimuth range.

[0121] (1e) The signal processing unit 4 may be configured to extract at least one reflection point whose distance from the radar device 2 is less than a distance threshold from the plurality of reflection points as a road surface reflection point in S140 based on the reflection point information. As a result, since it is considered that the road surface is at least located near the vehicle VH, the accuracy of extracting the reflection points on the road surface can be further improved by appropriately defining the distance threshold.

[0122] (1f) The reflection point information may also include the relative speed of the reflection point with respect to the vehicle VH. The signal processing unit 4 may also be configured to extract at least one reflection point that is a stationary reflection point from the plurality of reflection points as a road surface reflection point in S150 based on the reflection point information. As a result, the road surface is stationary with respect to the vehicle VH, so that the accuracy of extracting the reflection points on the road surface can be further improved.

[0123] (1g) The reflection point information may also include the reception intensity of the reflection point. The signal processing unit 4 may also be configured to extract at least one reflection point whose reflection power is less than the power threshold as a road surface reflection point in S160 based on the reflection point information. As a result, since the reflection power from the road surface is considered to be smaller than the reflection power from other vehicles, for example, the power threshold is appropriately determined based on the reflection power from the road surface, so that the accuracy of extracting the reflection point on the road surface can be further improved.

[0124] (1h) The signal processing unit 4 may also be configured to acquire a captured image of a camera and estimate the azimuth range of the road surface identified in the captured image. The signal processing unit 4 may also be configured to extract at least one reflection point in the azimuth range estimated as the road surface in the captured image from the plurality of reflection points in S170 as a road surface reflection point. In this way, the accuracy of extracting the road surface reflection point can be further improved.

[0125] In the above-described embodiment, the host vehicle VH corresponds to the moving body, and the signal processing unit 4 corresponds to the axial misalignment estimation device.

[0126] The coordinate axes of the host vehicle VH correspond to the coordinate axes of the moving body. p Equivalent to the axis offset angle. α p and β p is equivalent to two unknown parameters containing the axis offset angle. In other words, α p and β p Equivalent to at least one unknown parameter including the axis offset angle. xs and zs are equivalent to two elements included in the device system coordinates. The horizontal axis Yc is equivalent to the object axis, the left and right axis Ys is equivalent to the corresponding axis, and the two coordinate axes of the radar device 2 included in the plane perpendicular to the corresponding axis are equivalent to the front-back axis Xs and the up-down axis Zs.

[0127] [1-4. Modifications]

[0128] (Variation 1) The signal processing unit 4 may also replace the vertical axis offset angle α p , and the estimated roll angle α r As the axis offset angle. In the first modification, the signal processing unit 4 may also perform Fig.10 The angle estimation process shown is replaced by Figure 8 The angle estimation process is shown in FIG. Fig.10 In the angle estimation process shown, Figure 8 The S220 in the example is replaced by S230.

[0129] In S210, the signal processing unit 4 and Figure 8 The illustrated S210 similarly determines the device system coordinates for each road surface reflection point based on the reflection point information.

[0130] In S230, the signal processing unit 4 may also use a method including at least the axis offset angle (ie, the roll angle α) r ) of the two unknown parameters (i.e., α r and β r ) and the two elements (i.e., ys and zs) contained in the device system coordinates of the road reflection point (i.e., (2) described later), to estimate the roll angle α r .

[0131] Roll angle α r It is an axis deviation angle of the coordinate axis of the radar device 2 around the target axis (ie, the traveling direction axis Xc), which is one of the horizontal axis Yc and the traveling direction axis Xc that are the coordinate axes of the host vehicle VH.

[0132] The two elements included in the device-based coordinates are elements related to the two coordinate axes (i.e., left-right axis Ys and up-down axis Zs) of the radar device 2 included in a plane perpendicular to the corresponding axis (i.e., front-back axis Xs) corresponding to the object axis (i.e., the traveling direction axis Xc) among the three coordinate axes of the radar device 2. In other words, the two elements ys and zs included in the device-based coordinates are equivalent to the coordinates of the projection point of the road surface reflection point projected onto the projection plane perpendicular to the front-back axis Xs as the corresponding axis.

[0133] like Fig.11 As shown, the road surface reflection points are located on the same plane as the road surface. Based on this, it is considered that a plurality of road surface reflection points are arranged linearly on the projection plane. In other words, the following equation (2) holds true.

[0134] [Number 2]

[0135] z s =α r y s +β r (2)

[0136] Formula (2) is a linear equation representing a straight line on the projection plane based on the left-right axis Ys and the up-down axis Zs. r Indicates the slope of the straight line, that is, the roll angle α r . β r represents the intercept on the upper and lower axis Zs (i.e., Z intercept). The unknown number is α r and β r These two.

[0137] The signal processing unit 4 converts the estimated roll angle α into r The data is stored in the memory 42 and the angle estimation process is terminated.

[0138] In addition, in Modification 1, the roll angle α r Equivalent to the axis offset angle. α r and β r is equivalent to two unknown parameters containing at least the axis offset angle. In other words, α r and β rEquivalent to at least one unknown parameter including the axis offset angle. ys and zs are equivalent to two elements contained in the device system coordinates. The travel direction axis Xc is equivalent to the object axis, the front-back axis Xs is equivalent to the corresponding axis, and the two coordinate axes of the radar device 2 contained in the plane perpendicular to the corresponding axis are equivalent to the left-right axis Ys and the up-down axis Zs.

[0139] [2. Second Embodiment]

[0140] [2-1. Structure]

[0141] The basic structure of the second embodiment is the same as that of the first embodiment, so the differences are described below. In addition, the same reference numerals as those of the first embodiment represent the same structure, and the previous description is referred to. In the second embodiment, the difference from the first embodiment is that the signal processing unit 4 only uses the axis offset angle as an unknown parameter and estimates the axis offset angle. p The following description will be given as an example of an axis offset angle.

[0142] [2-2. Processing]

[0143] The signal processing unit 4 performs Fig.12 The angle estimation process of the second embodiment shown is replaced by Figure 8 The angle estimation process of the first embodiment is shown.

[0144] In S310 , the signal processing unit 4 calculates the device system coordinates (xs, ys, zs) for all road surface reflection points, similarly to the process of S210 in the angle estimation process of the first embodiment, and stores them in the memory 42 .

[0145] In S320, the signal processing unit 4 uses the vertical axis offset angle α as an unknown parameter. p The axis offset angle is estimated by using the relational expression (i.e., equation (3)) between the mounting height H of the radar device 2 and two elements (i.e., xs and zs) included in the device system coordinates. The mounting height H refers to the height of the radar device 2 in the vehicle VH from the road surface and is pre-stored in the memory 42.

[0146] [Number 3]

[0147]

[0148] In addition, if Fig.13 As shown in the formula (3), the front-rear axis Xs and the up-down axis Zs as the coordinate axes of the radar device 2 on the projection plane are rotated by the vertical axis offset angle α p The amount is obtained by being consistent with the traveling direction axis Xc and the vertical axis Zc which are the coordinate axes of the vehicle VH.

[0149] In other words, as shown in equation (4), on the projection plane, the two elements (xs, zs) of the device system coordinates are offset by an angle α around the travel direction axis Xc by the coordinate axis of the radar device 2. p The vehicle coordinates are three-dimensional coordinates (xc, yc, zc) based on the coordinate axes of the host vehicle VH. In other words, on the projection plane, the two elements (xs, zs) of the device coordinates are offset by the vertical axis by rotating the radar device 2 around the front-rear axis Xs by an angle α. p The quantity is consistent with the two elements (xc, zc) of the vehicle coordinate system.

[0150] [Number 4]

[0151]

[0152]

[0153] Here, assuming that the vertical axis is offset by an angle α p When is small enough, the approximate formulas shown in formulas (5) and (6) are obtained from formula (4). In addition, Fig.13 As shown, it can be seen that since the road surface reflection point is located on the same plane as the road surface, the size of the element zc in the vertical axis Zc direction in the vehicle coordinates (xc, yc, zc) is equal to the mounting height H of the radar device 2, and the sign is negative. Therefore, equation (7) can be obtained. Based on equation (7), the above equation (3) is obtained.

[0154] The signal processing unit 4 calculates the vertical axis offset angle α based on equation (3): p , the calculated vertical axis offset angle α p The data is stored in the memory 42 and the angle estimation process is terminated.

[0155] [2-3. Effect]

[0156] According to the second embodiment described in detail above, the following effects are achieved.

[0157] (2a) In S320, the signal processing unit 4 estimates the vertical axis offset angle α using the relational expression (i.e., equation (3)): p This relationship is obtained when an unknown parameter (i.e., the vertical axis offset angle α) is p ), the mounting height H of the radar device 2 and the two elements (i.e., xs and zs) included in the device system coordinates of the road surface reflection point. Vertical axis offset angle α pIt is an axis deviation angle of the coordinate axis of the radar device 2 around the target axis (ie, the horizontal axis Yc), which is one of the horizontal axis Yc and the traveling direction axis Xc that are the coordinate axes of the host vehicle VH.

[0158] As a result, the signal processing unit 4 can obtain the same effect as the above-mentioned (1a). In addition, the signal processing unit 4 can estimate the vertical axis deviation angle α based on at least one road surface reflection point. p .

[0159] (2b) The mounting height H may be pre-stored in the memory 42 mounted on the host vehicle VH. The signal processing unit 4 may estimate the axis deviation angle based on the mounting height H pre-stored in the memory 42. As a result, the host vehicle VH may not have a new structure for detecting the mounting height H of the radar device 2.

[0160] Furthermore, in the above embodiment, the vertical axis is offset by an angle α p Equivalent to the axis offset angle. α p is equivalent to an unknown parameter as the axis offset angle. In other words, α p Equivalent to at least one unknown parameter including the axis offset angle. xs and zs are equivalent to two elements included in the device system coordinates. The horizontal axis Yc is equivalent to the object axis, the left and right axis Ys is equivalent to the corresponding axis, and the two coordinate axes of the radar device 2 included in the plane perpendicular to the corresponding axis are equivalent to the front-back axis Xs and the up-down axis Zs.

[0161] [2-4. Modifications]

[0162] (Variation 2) The signal processing unit 4 may also replace the vertical axis offset angle α p , and the estimated roll angle α r As the axis offset angle. In the second modification, the signal processing unit 4 may also perform Fig.14 The angle estimation process shown is replaced by Fig.12 The angle estimation process is shown in FIG. Fig.14 In the angle estimation process shown, Fig.12 S320 in is replaced by S330.

[0163] In S310, the signal processing unit 4 and Fig.12 The illustrated S310 similarly determines the device system coordinates for each road surface reflection point based on the reflection point information.

[0164] In S330, the signal processing unit 4 may also use the relational expression (ie, equation (8)) to estimate the roll angle α r .

[0165] [Number 5]

[0166]

[0167] Equation (8) is based on an unknown parameter (i.e., the roll angle α r ), the mounting height H of the radar device 2 and the two elements (i.e., ys and zs) included in the device system coordinates of the road surface reflection point. Roll angle α r It is an axis deviation angle of the coordinate axis of the radar device 2 around the target axis (ie, the traveling direction axis Xc), which is one of the horizontal axis Yc and the traveling direction axis Xc that are the coordinate axes of the host vehicle VH.

[0168] like Fig.15 As shown in the figure, the equation (8) is based on the left and right axis Ys and the up and down axis Zs as the coordinate axes of the radar device 2 on the projection plane, which are rotated by the roll angle α r The amount is obtained by coinciding with the horizontal axis Yc and the vertical axis Zc as the coordinate axes of the host vehicle VH. In other words, equation (12) is obtained by equation (9) - equation (11), and the above-mentioned equation (8) is obtained based on equation (12).

[0169] [Number 6]

[0170]

[0171] [z c ]=[z s +α r y s ]=[-H] (12)

[0172] The signal processing unit 4 calculates the roll angle α based on the above equation (8): r , the calculated roll angle α r The data is stored in the memory 42 and the angle estimation process is terminated.

[0173] Furthermore, in the above embodiment, the roll angle α r Equivalent to the axis offset angle. α r is equivalent to an unknown parameter as the axis offset angle. In other words, α r Equivalent to at least one unknown parameter including the axis offset angle. ys and zs are equivalent to two elements contained in the device system coordinates. The travel direction axis Xc is equivalent to the object axis, the front-back axis Xs is equivalent to the corresponding axis, and the two coordinate axes of the radar device 2 contained in the plane perpendicular to the corresponding axis are equivalent to the left-right axis Ys and the up-down axis Zs.

[0174] (Variant 3) The vehicle-mounted sensor group 3 may also include a sensor for detecting the position of the radar device 2. The sensor may be, for example, a camera or various radar devices. The signal processing unit 4 may also estimate the axis offset angle based on the mounting height H detected by the sensor during the angle estimation process.

[0175] As a result, even when the radar device 2 deviates upward or downward on the vertical axis Zc after the mounting height H is stored in the memory 42, the axis deviation angle can be accurately estimated based on the mounting height H detected by the sensor.

[0176] (Variation 4) The signal processing unit 4 may also estimate the vertical axis offset angle α p and the roll angle α r In the modification 4, the signal processing unit 4 may also perform Fig.16 The angle estimation process shown is replaced by Fig.12 The angle estimation process is shown in FIG. Fig.16 In the angle estimation process shown, Fig.12 The S320 in is replaced by S340.

[0177] In S340, the signal processing unit 4 may also use the relational expression (ie, (19) described later) to estimate the vertical axis offset angle α. p and the roll angle α r .

[0178] like Fig.17 As shown in the formula (19), the coordinate axis of the radar device 2 is rotated around the left-right axis Ys by the vertical axis offset angle α. p The amount and the roll angle α around the front and rear axis Xs r The amount is obtained by making it consistent with the coordinate axis of the host vehicle VH. In other words, equations (13) to (15) are obtained.

[0179] [Number 7]

[0180]

[0181] Furthermore, based on equation (15), equations (16) to (18) are obtained.

[0182] [Number 8]

[0183] [Z c ]=[-H] (16)

[0184] [Z C ]=[α P X s -α r Y s +Z s ]=[-H] (17)

[0185]

[0186] Furthermore, the above-mentioned formula (19) is obtained based on formula (18).

[0187] [Number 9]

[0188]

[0189] Where A=[X s -Y s ] (20)

[0190] B=[-Z s -H] (21)

[0191] Equation (19) is a mathematical expression that takes into account two unknown parameters (i.e., the vertical axis offset angle α) p and the roll angle α r ), the mounting height H of the radar device 2 and the three elements (i.e., xs, ys, and zs) contained in the device system coordinates of the road surface reflection point.

[0192] The signal processing unit 4 calculates the vertical axis offset angle α based on the above equation (19): p and the roll angle α r , the calculated vertical axis offset angle α p and the roll angle α r The data is stored in the memory 42 and the angle estimation process is terminated.

[0193] [3. Other embodiments]

[0194] As mentioned above, although embodiment of this disclosure was described, this disclosure is not limited to the said embodiment, Various deformation|transformation and implementation are possible.

[0195] (3a) In the above embodiment, although the radar device 2 transmits radar waves toward the front of the vehicle VH, the transmission direction of the radar waves is not limited to the front of the vehicle VH. For example, the radar device 2 may be configured to 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.

[0196] (3b) In the above embodiment, the radar device 2 adopts the FMCW method, but the radar method of the radar device 2 is not limited to FMCW, and may be configured to adopt dual-frequency CW, FCM, or pulse. FCM is an abbreviation for Fast-Chirp Modulation.

[0197] (3c) In the above embodiment, an example is shown in which the signal processing unit 4 executes the axis shift estimation process. However, the radar device 2 may execute the axis shift estimation process.

[0198] (3d) The signal processing unit 4 and its method described in the present disclosure may also be implemented by a dedicated computer provided by a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the signal processing unit 4 and its method described in the present disclosure may also be implemented by a dedicated computer provided by a processor composed of one or more dedicated hardware logic circuits. Alternatively, the signal processing unit 4 and its method described in the present disclosure may also be implemented by one or more dedicated computers composed of 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 computer-readable non-migratable tangible recording medium. The method for implementing the functions of each unit included in the signal processing unit 4 does not necessarily need to include software, and all of its functions may be implemented using one or more hardware.

[0199] (3e) It is also possible to implement multiple functions of one component in 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, part of the structure of the above-mentioned embodiment may be omitted. In addition, it is also possible to add or replace at least part of the structure of the above-mentioned embodiment with the structure of other above-mentioned embodiments.

[0200] (3f) In addition to the above-mentioned signal processing unit 4, radar device 2, and vehicle control system 1, the present disclosure can also be implemented in various ways such as a program for enabling the signal processing unit 4 to function, a non-migrating physical recording medium such as a semiconductor memory recording the program, an axis offset estimation method, etc.

[0201] In the above embodiment, the vehicle VH corresponds to the mobile body, the signal processing unit 4 corresponds to the axis deviation estimation device, and the memory 42 corresponds to the storage device. In addition, S10 corresponds to the processing as the acquisition unit, S20 corresponds to the processing as the extraction unit, S30 and S21 correspond to the processing as the device system coordinate unit, and S30, S220, S230, S320, S330, and S340 correspond to the processing as the estimation unit.

Claims

1. An axial deviation estimation device for estimating an axial deviation angle of a radar device mounted on a mobile object, comprising: The acquisition unit is configured to acquire reflection point information for each of the plurality of reflection points detected by the radar device, wherein: The reflection point information at least includes an azimuth angle related to the reflection point and a distance between the radar device and the reflection point. The azimuth angle related to the reflection point is a horizontal angle and a vertical angle obtained based on a beam direction. The beam direction is a direction along a central axis of the radar beam. an extracting unit configured to extract at least one road surface reflection point detected by reflection from a road surface from among the plurality of reflection points based at least on the reflection point information; an apparatus coordinate unit configured to determine apparatus coordinates for each of the road surface reflection points based on the reflection point information, wherein the apparatus coordinates are three-dimensional coordinates based on coordinate axes of the radar device; and An estimation unit estimates the axis offset angle using a relational expression, and estimates the axis offset angle based on a straight line parameter approximating the distribution of the device system coordinates of the road surface reflection point in a projection plane orthogonal to the object axis, wherein the relational expression holds between at least one unknown parameter of the axis offset angle of the coordinate axis of the radar device around the object axis and at least one element included in the device system coordinates of the road surface reflection point, and the object axis is at least one of a horizontal axis serving as the coordinate axis of the moving body and a traveling direction axis.

2. The axial offset estimation device according to claim 1, wherein: The estimation unit is configured to estimate the axis offset angle included in the unknown parameter using the relational expression that holds true between the two unknown parameters including the one axis offset angle and the two elements included in the device system coordinates.

3. The axial offset estimation device according to claim 1, wherein: The estimation unit is configured to estimate the axis offset angle included in the unknown parameter using the relational expression established between one of the unknown parameters, which is the axis offset angle, the mounting height of the radar device, and two elements included in the device system coordinates.

4. The axial offset estimation device according to claim 3, wherein: The above-mentioned loading height is pre-stored in a storage device mounted on the above-mentioned moving body. The estimation unit is configured to estimate the axis deviation angle based on the mounting height pre-stored in the storage device.

5. The axial offset estimation device according to claim 3, wherein: The mobile body includes a sensor for detecting the position of the radar device. The estimation unit is configured to estimate the axis deviation angle based on the mounting height detected by the sensor.

6. An axial deviation estimation device for estimating an axial deviation angle of a radar device mounted on a mobile object, comprising: The acquisition unit is configured to acquire reflection point information for each of the plurality of reflection points detected by the radar device, wherein: The reflection point information at least includes an azimuth angle related to the reflection point and a distance between the radar device and the reflection point. The azimuth angle related to the reflection point is a horizontal angle and a vertical angle obtained based on a beam direction. The beam direction is a direction along a central axis of the radar beam. an extracting unit configured to determine whether the vehicle body of the moving object is in a stable state relative to the road surface, and if it is determined that the vehicle body of the moving object is in a stable state relative to the road surface, extract at least one road surface reflection point detected by reflection from the road surface from among the plurality of reflection points based on at least the reflection point information; an apparatus coordinate unit configured to determine apparatus coordinates for each of the road surface reflection points based on the reflection point information, wherein the apparatus coordinates are three-dimensional coordinates based on coordinate axes of the radar device; and An estimation unit is configured to estimate the above-mentioned axis deviation angle using a relational expression, wherein the above-mentioned relational expression holds between at least one unknown parameter of the above-mentioned axis deviation angle of the coordinate axis of the above-mentioned radar device around the object axis and at least one element included in the above-mentioned device system coordinates of the above-mentioned road surface reflection point, and the above-mentioned object axis is at least one of a horizontal axis serving as the coordinate axis of the above-mentioned mobile body and a traveling direction axis.

Images