JPH1144756A - Radar sensor centering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily perform centering of an axle at the center of scan of a sensor in the case where a radar sensor is displaced by replacing the center of scan, with which a sensor is directed to the center of a former traveling vehicle, with the new center of scan. SOLUTION: A radar drive control part of a micro computer 7 outputs the radar drive control signal, and while outputs the transmission control signal to a transmitter 2 so as to make a radar sensor 1 scan. An image processing part computes an angle γDX between the center of an image, which is picked up by a camera 4 by obtaining the center position of a preceding vehicle, and the center of the forward traveling vehicle. A radar receiving signal processing part obtains the electric potential signal of the center of the receiving signal, and this signal is converted to the angle of scan so as to obtain the center angle Cα of the receiving signal. A radar center position correcting part forms a new center of scan C (=Cα -γDX) on the basis of the angle γDX and the center angle Cα of the receiving signal. In the case where the new center C of scan and the original center C of scan are different from each other, the original center C of scan is replaced with the new center C of scan.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar sensor mounted on a vehicle, and more particularly to an apparatus for aligning the scan center of the radar sensor with the axle of the vehicle.

[0002]

2. Description of the Related Art FIG. 11 illustrates a radar sensor mounted on a conventional vehicle. As shown in FIG. 1A, a movable or scan type radar sensor 1 mounted on a 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 moves the scan center C in FIG.
As shown in (d), the vehicle in front is scanned while rotating by a fixed range ± θ (scan angle) at point 1A with respect to the scan center C. The radar sensor 1 measures the distance between the preceding vehicle and the own vehicle, and the measured inter-vehicle distance is used for auto cruise control or the like for keeping the inter-vehicle distance constant.

FIG. 12 is a diagram for explaining the level received by the radar sensor 1. As shown in FIG. 2A, 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. 3A, the reception level of the radar sensor 1 is usually symmetric with respect to the scanning center C.

As shown in FIG. 1B, when the position of the preceding vehicle shifts to the left, the shape of the reception level of the radar sensor 1 also shifts to the left with respect to the scanning center C. As shown in FIG. 3C, when the radar sensor 1 receives some shock or vibration and shifts the scan center C by a certain angle, the reception of the radar sensor 1 is performed even if the preceding vehicle is in front of the own vehicle. The shape of the level is also shifted with respect to the scan center C.

[0005]

FIG. 13 is a block diagram of FIG.
FIG. 3C is a diagram illustrating the reception level of the radar sensor 1 when the distance between the preceding vehicle and the host vehicle is large. For example, if the scan center of the radar sensor 1 is shifted by 1 °, it will be shifted by about 1.7 m at a distance of 100 m, and this will be directed in a direction different by half the width of the road. Therefore, as shown in FIG. If the distance to the car 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 for keeping the inter-vehicle distance constant, if such a problem occurs, the auto cruise control may be canceled.
This makes the control complicated. It is also troublesome to destroy the fixation of the radar sensor 1 and re-fix it.

For this reason, it is conceivable to correct the scan center C based on the reception signal of the radar sensor 1. In general, a potentiometer is attached to the drive 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. 12 (b) and 12 (c), it becomes unsymmetrical, and it cannot be determined whether the cause is that the position of the vehicle ahead is not in front or that the scan center C has 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 axle of the vehicle in consideration of the position of the vehicle ahead.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a radar sensor axis aligning apparatus that can easily adjust the scan center C of a radar sensor once shifted to the axle of a vehicle.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a radar sensor fixed in front of a host vehicle so as to coincide with the scan center of the host vehicle and the axle of the host vehicle. A camera fixed in front of the vehicle and such that the axle and the center of the captured image coincide with each other, and a radar drive control unit that drives the radar sensor within a scan angle range with respect to the scan center. An image for calculating a deviation angle from the axle of the host vehicle to the front vehicle based on a difference between a center position of the front vehicle and an image center obtained from a luminance distribution of a line drawing of the front vehicle captured by the camera; A processing unit configured to calculate a reception signal center angle from a scan center, in which the radar sensor is directed to the center of the front vehicle with respect to the reception signal reflected by the front vehicle and having a certain spread. A new scanning center is formed based on a processing unit and a shift angle calculated by the image processing unit and a reception position center angle calculated by the radar reception signal processing unit, and the fixed radar sensor is shifted. In this case, a radar center position correction unit that replaces the scan center with the new scan center is provided. By this means, the scan center of the radar sensor once shifted can be easily adjusted to the axle of the vehicle.

If the radar reception signal processor does not detect a reception signal within the scan angle, the radar drive controller 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 a vehicle speed sensor and the own vehicle is stopped, a new scan center is formed. Image shake can be avoided, and the accuracy of axis alignment can be improved.

The image processing section fixes the camera using a test pattern so that the axle of the vehicle coincides with the center of the image to be captured. This measure facilitates the fixing of the camera shaft to the axle. If the scan center does not match the new scan center, a lamp is turned on. By this means, the timing for adjusting the radar sensor and the camera can be easily obtained.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view for explaining a radar sensor axis alignment apparatus according to the present invention. As shown in the figure, a movable or scan type radar sensor 1 mounted on a vehicle is fixed in front of the vehicle such that a scan center C thereof coincides with an axle of the vehicle. Further, a radar driving unit and a potentiometer are attached to the radar sensor 1 as described later. Further, the radar sensor 1 is provided with a transmitter 2 and a receiver 3.

Further, a camera 4 for capturing the vehicle in front of the vehicle is fixed 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, the horizontal (horizontal) angle of view γ of the camera 4 is set to 50.
°, and the number of dots 2D0 is 640, the resolution of one dot is γ / 2D0 = 50/640 = 0.078 °.

The microcomputer 7 processes the received signal of the receiver 3, the potential signal of the potentiometer, the image signal of the camera 4, and the vehicle speed signal from the vehicle speed sensor 5 via the input interface 6. The microcomputer 7 outputs the driving signal to the radar sensor 1, the transmission control signal to the transmitter 2, the inter-vehicle distance data to the cruise control unit and the display unit as a result of the processing, and outputs the radar sensor 1 with respect to the axle of the vehicle to the lamp 10. The information on the occurrence of the shift of the scan center and the shift of the image center of the camera 4 is output via the output processing circuit 8.

FIG. 2 is a diagram for explaining the potentiometer and the drive unit of the radar sensor 1 of FIG. As shown in FIG. 1A, the radar sensor 1 is provided with a potentiometer 1B and a driving unit 1C. The driving unit 1C is a DC motor 21 for driving the radar sensor 1 via the potentiometer 1B, a battery 22 for driving the motor 21, and a drive signal from the output processing circuit 8 for rotating the motor 21 forward and backward. Switches 23 and 24 and driving of the motor 21;
And a switch 25 for stopping.

As shown in FIG. 2B, the potentiometer 1B converts the scan angle of the radar sensor 1 into a voltage, and the potentiometer potential signal VX with respect to the scan center C of the radar sensor 1 and the potential with respect to the scan center C. Potentiometer potential signal V for scan angle ± θ
It is adjusted to output X ± ΔV. FIG. 3 is FIG.
FIG. 3 is a diagram for explaining processing contents of the microcomputer 7 of FIG. As shown in the figure, a microcomputer 7 calculates a distance to a vehicle ahead from a relationship between a transmission signal and a reception signal, and drives the potential signal of the potentiometer 1B from VX-ΔV to VX + ΔV. A radar drive control unit 72 that outputs a transmission control signal for causing the transmitter 2 to perform transmission while outputting a radar drive control signal to the unit 1C and scans the radar sensor 1; , And performs preprocessing to blur an image part having a large motion by a time-series smoothing process, recognizes only a preceding vehicle and a white line, obtains a center position of the preceding vehicle, obtains a center position of an image captured by the camera 4, and An image processing unit 73 for calculating an angle γDX with respect to the center of the vehicle, and a potential signal at the center of the received signal that maintains a constant level with respect to the potential signal of the potentiometer Radar receiving signal processing unit 74 to which was converted to the angle of the scan the received signal center angle Cα
And a radar center position correction unit 75 that forms a new scan center C (= Cα−γDX) based on the angle γDX calculated by the image processing unit 73 and the reception signal center angle Cα calculated by the radar reception signal processing unit 74. Have. The radar center position correction unit 75 compares the new scan center C with the original scan center C used by the radar drive control unit 72, and if they are different, the original scan center C used by the radar drive control unit 7 is different. The scan center C is replaced with a new scan center C.

FIG. 4 is a diagram for explaining the image processing section 73 of FIG. As shown in the figure, the image processing unit 73 integrates the brightness of the line drawing in the white line in the vertical direction, obtains the width W of the preceding vehicle from the brightness distribution, and calculates the number DX of dots at the center position (W / 2) of the vehicle. Ask for. The difference ΔDX (= D0−D) between the dot D0 at the center position of the image captured by the camera 4 and the dot number DX
X) is obtained, and using this, an angle γDX with respect to the difference ΔDX between the image center of the camera 4 and the center position of the vehicle ahead is calculated as γDX = (γ / 2D0) × ΔDX. This angle γDX represents a deviation angle from the axle of the own vehicle to the preceding vehicle, and can be obtained with high accuracy in consideration of the resolution of the camera 4. If the center of the vehicle is located at the center of the image, this angle γDX is zero.

FIG. 5 is a diagram for explaining the radar reception signal processing section 74 of FIG. As shown in FIGS. 7A and 7B, the radar reception signal processing unit 74 receives 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. I do. Further, the radar reception signal processing unit 74
Integrates the received signal at the scan angle to calculate the left and right areas S-,
A central angle Cα of the received signal such that S + becomes equal (S− = S +) is obtained. As shown in FIG. 3C, when the center angle Cα of the received signal of the vehicle is set to the scan center C, the displacement is corrected so that the radar sensor 1 is directed to the vehicle in front. As a simple example, if the vehicle is in front of itself, γD
Since X = 0, the scan center C of the radar sensor 1 coincides with the axle of the host vehicle, and the correction of the displacement due to the impact of the radar sensor 1 is completed.

FIG. 6 is a diagram for explaining the radar center position correcting section 75 of FIG. When there is no vehicle in front, γ
Since DX ≠ 0, as shown in this figure, the radar center position correction unit 75 calculates a new scan center C using Cα and γDX as C = Cα−γDX. By using this new scan center C, the radar sensor 1 can be used even when the vehicle is not in front.
Axis coincides with the axle of the own vehicle.

Along with this, the radar drive control unit 72 sets a new scan center C obtained from the radar center position correction unit 75.
Is performed using the new potential signal VX of the potentiometer 1B. FIG. 7 is a diagram illustrating a case where the displacement of the radar sensor is large. If the deviation due to the impact of the radar sensor or the like is large, a received signal cannot be obtained within a range of the scan angle ± θ with respect to the scan center C. In this case, as shown in FIG. , The received signal center angle Cα is determined. This is to deal with a large shock.

FIG. 8 is a flowchart for explaining a series of operations of the radar sensor axis aligning apparatus according to the present invention.
FIG. 9 is a view showing a test pattern for the camera 4. If there is no request for correction of the displacement of the radar sensor 1 in step S1, a scan of the preceding vehicle is performed in step S2, and the inter-vehicle distance with the preceding vehicle is calculated in step S3, and the process ends.

In step S4, if there is a correction request, it is preferable to determine whether the vehicle is stopped based on the signal of the vehicle speed sensor 5, and if not, it is preferable to return to step S2. Avoid the shake of the camera 4 while running,
This is for accurately calculating the deviation between the center of the image and the center of the preceding vehicle. In step S5, the camera 4 is initially aligned with 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 so that the axle of the vehicle and the center of the image are aligned. This alignment is performed as necessary, and if there is a shift between the axle of the vehicle and the center of the image, the center of the image is corrected based on the shift. This is to enable alignment without breaking the fixing of the camera 4.

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 signal received by 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 center is different, the process returns to step S2 to perform scanning based on the new scan center C.

As described above, the radar sensor 1 can easily correct a displacement caused by an impact or the like.
FIG. 10 is a flowchart illustrating an additional example of the operation in FIG. As shown in the figure, in step S11, it is determined whether or not the original scan center and the new scan center match, and if they match, the process ends. In step S12, if there is no match in step S11, the lamp 11
Is turned on to end the processing. In this case, since there is a possibility that the fixed radar sensor 1 is shifted or the fixed camera 4 is shifted, the lamp 11 is turned on to give attention. This lamp lighting makes it possible to set the timing for adjusting the alignment of the radar sensor 1 and the alignment of the camera 4.

[0024]

As described above, according to the present invention, the scan center of the radar sensor once shifted can be easily adjusted to the axle of the vehicle.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a radar sensor axis alignment apparatus 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 view for explaining processing contents of a microcomputer 7 of FIG. 1;

FIG. 4 is a diagram illustrating an image processing unit 73 of FIG. 3;

FIG. 5 is a diagram illustrating a radar reception signal processing unit 74 of FIG. 3;

FIG. 6 is a diagram illustrating a radar center position correction unit 75 of FIG. 3;

FIG. 7 is a diagram illustrating a case where the displacement of the radar sensor is large.

FIG. 8 is a flowchart illustrating a series of operations of the radar sensor axis alignment device according to the present invention.

FIG. 9 is a diagram showing a test pattern for the camera 4;

FIG. 10 is a flowchart illustrating an additional example of the operation in FIG. 8;

FIG. 11 is a diagram illustrating a radar sensor mounted on a conventional vehicle.

FIG. 12 is a diagram illustrating levels received by the radar sensor 1.

FIG. 13 is a diagram showing the reception level of the radar sensor 1 in the case where 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 reception signal processing part 75 ... Radar center position correction part

Claims (5)

[Claims] 1. A radar sensor fixed in front of an own vehicle so as to coincide with a scan center of the preceding vehicle and an axle of the own vehicle, wherein a radar sensor is provided in front of the own vehicle and the axle and a center of a captured image. A radar drive control unit that drives the radar sensor within a scan angle range with respect to the scan center, and a brightness distribution of a line drawing of the preceding vehicle captured by the camera. An image processing unit that calculates a shift angle to the front vehicle based on an axle of the own vehicle from a difference between a center position of the front vehicle and an image center; and a reception signal that is reflected by the front vehicle and has a certain spread. About the radar sensor is directed to the center of the preceding vehicle,
A radar reception signal processing unit that calculates a reception signal center angle from a scan center; and a new scan based on the shift angle calculated by the image processing unit and the reception position center angle calculated by the radar reception signal processing unit. A radar center position correction unit that forms a center and replaces the scan center with the new scan center when the fixed radar sensor is displaced. 2. The radar sensor according to claim 1, wherein when the radar reception signal processing unit does not detect a reception signal within a scan angle, the radar drive control unit increases the scan angle. Alignment device. 3. The axis alignment device for a radar sensor 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 vehicle is stopped. 4. The radar according to claim 1, wherein the image processing unit fixes the camera using a test pattern so that an axle of the own vehicle coincides with a center of a captured image. Sensor alignment device. 5. The axis alignment apparatus for a radar sensor according to claim 1, wherein a lamp is turned on when the scan center does not coincide with the new scan center.