JP3734342B2 - Radar sensor axis alignment device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radar sensor mounted on a vehicle, and more particularly to an apparatus for aligning a scan center of a radar sensor with a vehicle axle.
[0002]
[Prior art]
FIG. 11 is a diagram for explaining a radar sensor mounted on a conventional vehicle. As shown in FIG. 1A, the movable or scan type radar sensor 1 mounted on the vehicle is fixed in front of the vehicle so that the scan center C coincides with the axle of the vehicle. The radar sensor 1 has a fixed range ± θ (scan angle) at a point 1A with respect to the scan center C with respect to the scan center C in FIG. While rotating, scan the vehicle ahead. The radar sensor 1 measures the distance between the vehicle ahead and the host vehicle, and the measured inter-vehicle distance is used for auto cruise control or the like that keeps the inter-vehicle distance constant.
[0003]
FIG. 12 is a diagram for explaining the level received by the radar sensor 1. As shown in FIG. 5A, when the vehicle ahead is in front, the transmission wave from the radar sensor 1 is reflected by the vehicle ahead and received by the radar sensor 1. As shown in FIG. 5A, the reception level of the radar sensor 1 is usually symmetrical with respect to the scan center C.
[0004]
As shown in FIG. 4B, when the position of the vehicle ahead shifts to the left side, the shape of the reception level of the radar sensor 1 also shifts to the left with respect to the scan center C.
As shown in FIG. 4C, when the radar sensor 1 receives some impact or vibration and the scan center C is shifted by a certain angle, the reception of the radar sensor 1 is performed even if the preceding vehicle is in front of the host vehicle. The shape of the level is also shifted with respect to the scan center C.
[0005]
[Problems to be solved by the invention]
FIG. 13 is a diagram illustrating a reception level by the radar sensor 1 when the distance between the preceding vehicle and the host vehicle is large in FIG. For example, if the scan center of the radar sensor 1 is deviated by 1 °, it will deviate by about 1.7 m at 100 m ahead, and this will point in a different direction by half the road width. When the distance to the vehicle is large, there is a problem that a reception signal from the radar sensor 1 cannot be obtained. When the radar sensor 1 is used for auto-cruise control or the like in which the inter-vehicle distance is constant, when such a problem occurs, the auto-cruise control may be canceled, but this makes the control complicated. It is also complicated to destroy the fixing of the radar sensor 1 and perform the fixing again.
[0006]
For this reason, it is conceivable to correct the scan center C based on the received signal of the radar sensor 1.
Generally, a potentiometer is attached to the driving unit of the radar sensor 1 to detect the reception level with respect to the scan angle. However, as shown in FIG. As shown in FIGS. 12B and 12C, it becomes asymmetric, and it is impossible to determine whether this is because the position of the vehicle ahead is not in front or because the scan center C is shifted due to the impact on the fixed radar sensor 1. For this reason, it is difficult to correct the shift of the scan center C so that the scan center C is aligned with the vehicle axle in consideration of the position of the vehicle ahead.
[0007]
Therefore, in view of the above problems, an object of the present invention is to provide an alignment apparatus for a radar sensor that can easily align the scan center C of the radar sensor that has once shifted with the axle of the vehicle.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a radar sensor fixed in front of the host vehicle so as to coincide with the scan center of the preceding vehicle and the axle of the host vehicle. And a camera fixed so that the center of the image to be captured matches, a radar drive control unit that drives the radar sensor within a scan angle range with respect to the scan center, and the front imaged by the camera An image processing unit for calculating a deviation angle from the axle of the own vehicle to the preceding vehicle based on a difference between a center position of the preceding vehicle obtained from a luminance distribution of a line drawing of the vehicle and an image center; A radar reception signal processing unit for calculating a received signal center angle from a scan center, in which the radar sensor is directed to the center of the preceding vehicle with respect to the reception signal having a certain spread, and the image processing unit A new scan center is formed based on the calculated shift angle and the received position center angle calculated by the radar reception signal processing unit, and the fixed scan sensor is shifted when the fixed radar sensor is shifted. And a radar center position correction unit that replaces a new scan center. This means makes it possible to easily adjust the scan center of the radar sensor once shifted to the axle of the vehicle.
[0009]
When the radar reception signal processing unit does not detect a reception signal within the scan angle, the radar drive control unit widens the scan angle. By this means, it is possible to cope with a large deviation of the radar sensor.
When a vehicle speed signal is input from the vehicle speed sensor and the host vehicle is stopped, a new scan center is formed. Image shake can be avoided and the accuracy of alignment can be improved.
[0010]
The image processing unit uses the test pattern to fix the camera so that the axle of the host vehicle coincides with the center of the captured image. This means facilitates fixing of the camera shaft to the axle.
If the scan center and the new scan center do not match, the lamp is turned on. By this means, the timing for adjusting the radar sensor and the camera can be easily obtained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a view for explaining an alignment apparatus for a radar sensor according to the present invention. As shown in the figure, the movable or scan type radar sensor 1 mounted on the vehicle is fixed in front of the vehicle so that the scan center C coincides with the vehicle axle. Further, as will be described later, a radar drive unit and a potentiometer are attached to the radar sensor 1. Further, the radar sensor 1 is provided with a transmitter 2 and a receiver 3.
[0012]
Furthermore, the camera 4 that captures the vehicle ahead is fixed in front of the vehicle so as to coincide with the center of the captured image and the axle of the vehicle. The resolution of the camera 4 is, for example, when the horizontal angle (horizontal direction) of the camera 4 is 50 ° and the number of dots 2D0 is 640, the resolution of 1 dot is γ / 2D0 = 50/640 = 0. 078 °.
[0013]
The reception signal of the receiver 3, the potentiometer potential signal, the image signal of the camera 4, and the vehicle speed signal from the vehicle speed sensor 5 are processed by the microcomputer 7 via the input interface 6. As a result of the processing, the microcomputer 7 outputs a driving signal to the radar sensor 1, a transmission control signal to the transmitter 2, a cruise control unit, and an inter-vehicle distance data to the display unit, and a radar sensor 1 for the vehicle axle to a ramp 10. The information about the deviation of the scan center and the information about the deviation of the image center of the camera 4 is output via the output processing circuit 8.
[0014]
FIG. 2 is a diagram for explaining a potentiometer and a driving unit of the radar sensor 1 of FIG. As shown in FIG. 4A, the radar sensor 1 is provided with a potentiometer 1B and a drive unit 1C. The drive unit 1C is configured to perform forward / reverse rotation of the motor 21 by a drive signal from the DC motor 21 that drives the radar sensor 1 via the potentiometer 1B, the battery 22 that drives the motor 21, and the output processing circuit 8. Switches 23 and 24 and a switch 25 for driving and stopping the motor 21 are provided.
[0015]
As shown in FIG. 2B, the potentiometer 1B converts the scan angle of the radar sensor 1 into a voltage, the potentiometer potential signal VX with respect to the scan center C of the radar sensor 1, and the scan angle ± with respect to the scan center C. The potentiometer potential signal VX ± ΔV is adjusted with respect to θ.
FIG. 3 is a diagram for explaining the processing contents of the microcomputer 7 of FIG. As shown in this figure, the microcomputer 7 is driven so that the distance calculation unit 71 calculates the distance to the vehicle ahead from the relationship between the transmission signal and the reception signal, and the potential signal VX−ΔV of the potentiometer 1B becomes VX + ΔV. A radar drive control unit 72 that scans the radar sensor 1 by outputting a transmission control signal that causes the transmitter 2 to transmit while outputting a radar drive control signal to the unit 1C, and an image signal captured by the camera 4 as a line drawing signal Is converted to, and preprocessing for blurring an image portion with large motion by time series smoothing processing is performed, only the front vehicle and the white line are recognized, the center position of the front vehicle is obtained, and the center of the image captured by the camera 4 and the front An image processing unit 73 that calculates an angle γDX with respect to the center of the vehicle, and a center potential signal of a reception signal that continues a certain level with respect to the potential signal of the potentiometer. A radar reception signal processing unit 74 that converts this into a scan angle to obtain a reception signal center angle Cα, an angle γDX calculated by the image processing unit 73, and a reception signal center angle Cα calculated by the radar reception signal processing unit 74. And a radar center position correction unit 75 that forms a scan center C (= Cα−γDX). The radar center position correcting unit 75 compares the new scan center C with the original scan center C used in the radar drive control unit 72, and if it is different, the original scan center C used in the radar drive control unit 7 is used. The scan center C is replaced with a new scan center C.
[0016]
FIG. 4 is a diagram illustrating the image processing unit 73 in FIG. As shown in this figure, the image processing unit 73 integrates the luminance of the line drawing in the white line in the vertical direction, obtains the width of the vehicle ahead by the luminance distribution, and calculates the number of dots DX at the center position (W / 2) of the vehicle. Ask for. The difference ΔDX (= D0−DX) between the dot D0 and the number of dots DX at the center position of the image captured by the camera 4 is obtained, and using this, the difference between the image center of the camera 4 and the center position of the preceding vehicle is obtained. The angle γDX with respect to ΔDX is
γDX = (γ / 2D0) × ΔDX
Is calculated as This angle γDX represents the angle of deviation from the axle of the host vehicle to the preceding vehicle, and can be obtained with high accuracy when the resolution of the camera 4 is taken into consideration. If the center of the image is the center of the preceding vehicle, this angle γDX is zero.
[0017]
FIG. 5 is a diagram for explaining the radar reception signal processing unit 74 of FIG. As shown in FIGS. 4A and 4B, the radar reception signal processing unit 74 inputs the reception signal and the potential signal of the potentiometer 1B, and converts the potential signal of the potentiometer 1B into a scan angle with respect to the scan center C of the radar sensor 1. To do. Further, the radar reception signal processing unit 74 integrates the reception signal with the scan angle to obtain the central angle Cα of the reception signal such that the left and right areas S− and S + are equal (S− = S +). As shown in FIG. 4C, when the center angle Cα of the received signal of the vehicle is the scan center C, the deviation is corrected so that the radar sensor 1 faces the preceding vehicle. As a simple example, when the vehicle is in front of the host vehicle, since γDX = 0, the scan center C of the radar sensor 1 coincides with the axle of the host vehicle. The correction is completed.
[0018]
FIG. 6 is a diagram for explaining the radar center position correction unit 75 of FIG. Since γDX ≠ 0 when the vehicle is not in front, the radar center position correction unit 75 uses Cα and γDX to set a new scan center C, as shown in FIG.
C = Cα-γDX
Calculate as By using this new scan center C, even when the vehicle is not in front, the axis of the radar sensor 1 coincides with the axis of the own vehicle.
[0019]
Accordingly, the radar drive control unit 72 performs scanning using the potential signal VX of the new potentiometer 1B with respect to the new scan center C obtained from the radar center position correction unit 75.
FIG. 7 is a diagram for explaining a case where the deviation of the radar sensor is large. When the deviation due to the impact or the like of the radar sensor is large, a received signal cannot be obtained within the range of the scan angle ± θ with respect to the scan center C. In this case, as shown in this figure, the range of the scan angle is widened. The received signal center angle Cα is obtained. This is to cope with a large impact.
[0020]
FIG. 8 is a flowchart for explaining a series of operations of the axis alignment device for the radar sensor according to the present invention, and FIG. 9 is a diagram showing a test pattern for the camera 4.
In step S1, if there is no request for correction of the deviation of the radar sensor 1, the front vehicle is scanned in step S2, the inter-vehicle distance from the front vehicle is calculated in step S3, and the process ends.
[0021]
In step S4, if there is a correction request, it is determined based on the signal from the vehicle speed sensor 5 whether the vehicle is stopped. If not, it is preferable to return to step S2. This is to avoid the shake of the camera 4 during traveling and to accurately calculate the deviation between the center of the image and the center of the preceding vehicle.
In step S5, the camera 4 is initially aligned using the test pattern shown in FIG. That is, the horizontal position of each line in FIG. 8 is read from the number of dots, and the camera 4 is fixed by aligning the vehicle axle and the image center. This alignment is performed as necessary, and if there is a deviation between the vehicle axle and the image center, the image center is corrected by the deviation. This is to enable alignment without breaking the fixing of the camera 4.
[0022]
In step S6, a deviation angle γDX from the center of the image to the preceding vehicle is calculated.
In step S7, the central angle Cα of the received signal of the radar sensor 1 is calculated.
In step S8, a new scan center C is calculated and compared with the original scan center. If the new scan center C is different, the process returns to step S2 to perform scanning based on the new scan center C.
[0023]
In this way, the radar sensor 1 can easily correct a deviation caused by an impact or the like.
FIG. 10 is a flowchart for explaining an additional example of the operation of FIG. As shown in the figure, in step S11, it is determined whether the original scan center and the new scan center match. If they match, the process ends. In step S12, if there is no match in step S11, the lamp 11 is turned on and the process is terminated. In this case, there is a possibility that a deviation occurs in the fixed radar sensor 1 or a deviation occurs in the fixed camera 4, so that the lamp 11 is turned on for caution. By turning on the lamp, it is possible to adjust the timing of the alignment of the radar sensor 1 and the alignment of the camera 4.
[0024]
【The invention's effect】
As described above, according to the present invention, the scan center of the radar sensor once shifted can be easily aligned with the axle of the vehicle.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an axis alignment apparatus for a radar sensor according to the present invention.
FIG. 2 is a diagram illustrating a potentiometer and a drive unit of the radar sensor 1 of FIG.
FIG. 3 is a diagram for explaining processing contents of the microcomputer 7 of FIG. 1;
4 is a diagram for explaining an image processing unit 73 in FIG. 3;
5 is a diagram for explaining a radar reception signal processing unit 74 in FIG. 3;
6 is a diagram for explaining a radar center position correction unit 75 in FIG. 3;
FIG. 7 is a diagram for explaining a case where a deviation of a radar sensor is large.
FIG. 8 is a flowchart illustrating a series of operations of the axis alignment device for a radar sensor according to the present invention.
FIG. 9 is a diagram showing a test pattern for the camera 4;
FIG. 10 is a flowchart for explaining an additional example of the operation of FIG. 8;
FIG. 11 is a diagram illustrating a radar sensor mounted on a conventional vehicle.
FIG. 12 is a diagram for explaining the level received by the radar sensor 1;
FIG. 13 is a diagram showing the reception level by the radar sensor 1 when the distance between the preceding vehicle and the host vehicle is large in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Radar sensor 2 ... Transmitter 3 ... Receiver 4 ... Camera 5 ... Vehicle speed sensor 7 ... Microcomputer 72 ... Radar drive control part 73 ... Image processing part 74 ... Radar received signal processing part 75 ... Radar center position correction part

Claims (6)

In a radar sensor that is fixed in front of the host vehicle so that the scan center direction of the preceding vehicle and the axle direction of the host vehicle coincide with each other,
A camera that is fixed in front of the vehicle and so that the axle and the center of the image to be captured coincide with each other;
A radar signal scanning unit that scans a radar signal in a range of a predetermined scan angle including at least the scan center direction ;
An image processing unit that calculates a deviation angle to the preceding vehicle based on an axle of the own vehicle from a difference between a center position of the preceding vehicle obtained from an image of the preceding vehicle captured by the camera and an image center;
The received signal is reflected to the front vehicle with constant spread and radar received signal processing unit for calculating a reception position central angle and the center direction of the center of the scan direction and the received signal is formed,
A new scan center is formed based on the deviation angle calculated by the image processing unit and the reception position central angle calculated by the radar reception signal processing unit, and when the fixed radar sensor is displaced, A radar sensor axis alignment apparatus comprising: a radar center position correction unit that replaces a scan center with the new scan center. In a radar sensor that is fixed in front of the host vehicle so as to coincide with the scan center of the preceding vehicle and the axle of the host vehicle,
A camera that is fixed in front of the host vehicle so that the axle and the center of the image to be captured coincide with each other;
A radar drive controller for driving the radar sensor in a range of scan angles with respect to the scan center;
Image processing for calculating a deviation angle to the preceding vehicle based on the axle of the own vehicle from the difference between the center position of the preceding vehicle and the image center obtained from the luminance distribution of the line drawing of the preceding vehicle imaged by the camera And
A radar reception signal processing unit that calculates a reception signal central angle from a scan center, with the radar sensor facing a center of the front vehicle for a reception signal reflected by the front vehicle and having a certain spread;
A new scan center is formed based on the deviation angle calculated by the image processing unit and the reception position central angle calculated by the radar reception signal processing unit, and when the fixed radar sensor is displaced, A radar sensor axis alignment apparatus comprising: a radar center position correction unit that replaces a scan center with the new scan center. 3. The radar sensor axis alignment apparatus according to claim 2, wherein when the received signal is not detected within a scan angle by the radar received signal processing unit, the scan angle is widened by the radar drive control unit. 3. The radar sensor axis alignment apparatus according to claim 1, wherein a new scan center is formed when a vehicle speed signal is input from the vehicle speed sensor and the host vehicle is stopped. 3. The radar sensor shaft according to claim 1, wherein the image processing unit fixes the camera so that the axle of the host vehicle coincides with the center of an image to be captured using a test pattern. 4. Alignment device. 3. The radar sensor axis alignment apparatus according to claim 1, wherein a lamp is lit if the scan center and the new scan center do not coincide with each other.

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