JP3237488B2 - Scanning radar device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning radar apparatus, which is mounted on a vehicle and performs scanning to detect a target object.

[0002]

2. Description of the Related Art Conventionally, various devices have been developed and mounted on a vehicle for the purpose of improving a driver's driving operation in a low frequency range and improving safety, and the distance and relative speed to surrounding objects such as a preceding vehicle. The development of a radar device for detecting the occupation has been actively carried out. As a radar device, a device using a radio wave such as a millimeter wave or a device using a laser beam has been proposed.

For example, Japanese Patent Application Laid-Open No. 4-158293 discloses that light is scanned and emitted, light reflected by reflectors provided on the right and left rear portions of the body of a preceding vehicle is received, and a delay from light emission to light reception is received. The distance from the time to the reflector is calculated, and the midpoint between the scanning angles of the two reflectors having substantially the same distance is adopted as the center position of the preceding vehicle.

[0004]

In a scanning radar system using radio waves such as millimeter waves, it is not possible to specify the position of the reflector of the preceding vehicle. The center position cannot be specified. For this reason, in a scanning radar device using millimeter waves,
It is conceivable to simply estimate the end position of the preceding vehicle from the change in the reception level of the reflected signal according to the scanning angle and obtain the center position of the preceding vehicle, but noise is superimposed on the reflected signal,
Further, there is a problem that the end position of the preceding vehicle cannot be accurately detected because the reflection on the vehicle is not uniform, and the center position of the preceding vehicle cannot be accurately obtained.

[0005] The present invention has been made in view of the above points,
An object of the present invention is to provide a scanning radar apparatus capable of accurately detecting a scanning angle of a target object in a central direction by performing similarity approximation on a distribution pattern of a reception reflection signal level using an antenna gain pattern of the radar apparatus. I do.

[0006]

According to the first aspect of the present invention, as shown in FIG. 1A, radar means for emitting a radio wave in front of a vehicle, receiving a reflected signal, and detecting a target object. M1, scanning means M2 for scanning in the detection direction of the radar means, and antenna gain pattern of the radar means are sequentially moved relative to the entire distribution pattern of the received reflection signal level of the radar means with respect to the scanning angle. Moving position
Performs correlation calculation by location, relative movement for the entire above distribution pattern of the highest correlation the antenna gain pattern
And a center direction detecting means M3 for detecting a scanning angle of the target object in the center direction from the position .

For this reason, the reflection at the target object is non-uniform,
And even if noise is superimposed on the received reflection signal, the ideal distribution pattern of the reception reflection signal level should almost match the antenna gain pattern, and the peak in the distribution pattern of the reception reflection signal level is detected by similar approximation. Can,
It is possible to accurately detect the scanning angle of the target object in the center direction.

According to a second aspect of the present invention, as shown in FIG. 1 (B), in the scanning radar apparatus according to the first aspect, the distribution pattern of the received reflected signal level has a predetermined threshold when traveling in a curve. There is provided a center direction correcting means M4 for performing a predetermined correction in accordance with the curve direction with respect to the scanning angle at the center of the pair of end points exceeding the scanning direction to obtain the scanning angle in the center direction of the target object.

For this reason, even when the target object is inclined with respect to the emission direction of the radio wave when traveling in a curve, the distribution pattern of the received reflected signal level does not become similar to the antenna gain pattern, or the scanning angle shifts. By correcting the error, the scanning angle of the target object in the center direction can be accurately obtained.

[0010]

FIG. 2 is a block diagram showing an embodiment of the apparatus according to the present invention. In the figure, reference numeral 10 denotes a yaw rate sensor, which generates a yaw rate detection signal indicating the yaw rate of the vehicle using an angular velocity sensor such as a piezo gyro and supplies the signal to an electronic control unit (ECU) 11.

The ECU 11 is supplied with a detection signal from the vehicle speed sensor 13, filters the yaw rate, obtains the curvature of the currently traveling curve from the vehicle speed and the filtered yaw rate, and calculates the future curve from the curvature. Is calculated, and the deflection angle of the radar device is calculated from the estimated curvature of the future curve. ECU
11 supplies the deflection angle to the steering device 12. The steering device 12 deflects the beam so that the beam deflection angle of the radar device 14 becomes the calculated deflection angle. The radar device 14 is, for example, a millimeter-wave FMCW radar device, irradiates a millimeter-wave beam, receives a reflection signal reflected by a target object, and measures a relative distance and a relative speed with the target object.

The relative distance and the relative speed with respect to the target object are supplied to the ECU 11, and the ECU 11 determines whether the target object is dangerous to the own vehicle based on the relative distance and the relative speed with respect to the target object. Generates an alarm signal and activates the alarm 15. FIG. 3 shows a flowchart of the target object center direction detection processing executed by the ECU 11. This process is repeatedly executed at predetermined time intervals. In FIG. 5, in step S10, the radar means M is
For example, the radar device 14, which is 1, is steered from left to right and scans forward (beam scan). Step S above
10 and the steering device 12 correspond to the scanning means M2. Then, in step S12, the received reflected signal levels (received levels) of the target objects having substantially the same relative distance and relative speed are plotted with respect to the scan angle (scan angle) θ.

As shown in FIG. 4, a target object (target)
When the beam scanning of the target 20 is performed from left to right by the radar device 14, if the beam reflection at the target object 20 is ideal,
Scan angle θ at which the beam hits the left end of target object 20
_The detection is started from _L , and the detection is completed at a scan angle θ _R at which the beam passes through the right end of the target object 20, and a reception level characteristic as a distribution pattern with respect to the scan angle of the reception reflection signal level as shown in FIG. 5 is obtained. .

However, in practice, the boundary of the beam width is ambiguous, and the beam reflection at the target object 20 is not uniform but complicated, so that noise is superimposed and the reception level characteristic as shown in FIG. 6 is obtained. After the execution of step S12, the process proceeds to step S14, in which a smoothing process of the reception level characteristic plotted with respect to the scan angle θ is performed to reduce the influence of noise. Next, in step S16, a similarity approximation of the reception level characteristic obtained by performing smoothing using the antenna gain pattern of the radar device 14 as shown in FIG. 7 is performed. In this similarity approximation, an antenna gain pattern (antenna directivity pattern) is superimposed on a reception level characteristic and sequentially moved from the left end to the right end, and a correlation operation is performed at each movement position.

Next, in step S18, the peak position of the antenna gain pattern at the movement position (FIG. 8) of the antenna pattern having the highest correlation in the similarity approximation is determined by the scan center angle θ _C of the target object 20. And The above steps S12 to S18 correspond to the center direction detecting means M3.

As described above, even if the reflection at the target object 20 is uneven and the noise is superimposed on the received reflected signal,
The ideal distribution pattern of the received reflection signal level should almost match the antenna gain pattern, and the peak in the distribution pattern of the received reflection signal level can be detected by similar approximation, and the scanning angle of the target object in the center direction can be accurately detected. It is possible to do.

Next, at step S20, the vehicle speed sensor 1 is set at the yaw rate YAW detected by the yaw rate sensor 10.
The vehicle speed SPD detected in step 3 is divided to obtain a curvature _RL ( _RL = SPD / YAW) of the road on which the vehicle is currently traveling, and the curvature _RL is compared with a predetermined value to determine whether the vehicle is traveling. It is determined whether the vehicle is traveling on a curve. Here, when the curvature _RL is equal to or larger than the predetermined value, the process is terminated because it is not a curve.

Curvature R_LIs less than the specified value
If so, the process proceeds to step S22. In step S22
If the measured reception level characteristics match the specified threshold level
Scan angle A_nLFrom the threshold level
Scan angle A below_nRAngle difference of the target object
Detection width θ_WAnd this detection width θ_WIs the specified value 2θ _VH
It is determined whether or not: Note that 2θ_VHIs to the target object
And the vehicle width W (W is, for example, about 2 m)
Is obtained by the following equation.

Θ _VH = tan ⁻¹ (W / 2 · L) Here, as shown in FIG. 9, when the vehicle 25 is traveling in the left curve and the target object 30 is traveling ahead. think about. In this case, since the target object 30 is inclined with respect to the irradiation beam, the beam reflection becomes maximum at the left rear end of the target object 30, and the reception level characteristics shown in FIG. On the other hand, when the target object 30 is not inclined with respect to the irradiation beam, the reception level characteristic shown in FIG. 6B is obtained, and the detection width θ _W1 in FIG.
_Is smaller than the detection width θ _W2 . The specified value 2θ _VH is the detection width θ when the target object 30 is not inclined with respect to the irradiation beam.
_This is the estimated value of _W2 .

For this reason, if the vehicle travels inside the curve and the detection width θ _W is smaller than the specified value 2θ _{VH, the process} proceeds to step S2.
Proceed to step 4 to correct the scan center angle. Step S2
In FIG. 4, the scan angles _AnL and _{AnR as} shown in FIG.
Central scan central angle _{(A nL + A nR) /} 2 with the offset in the curve radially outer half vehicle width angle theta _VH seeking scan center angle theta _C with, theta _C obtained in step S18
Is corrected. In the case of a left curve, it is expressed by the following equation.

Θ _C = (A _nL + A _nR ) / 2 + θ _VH Thereafter, the routine proceeds to step S26. Step S20
If the vehicle is not running inside a curve, or if θ is determined in step S22
_{If W} > 2θ _VH , the process skips step S24 and proceeds to step S26. The above steps S20 to S24 correspond to the center direction correcting means M4.

As described above, when the vehicle is traveling on a curve, the target object 3
Even if 0 is inclined with respect to the emission direction of the radio wave and the distribution pattern of the received reflected signal level is not similar to the antenna gain pattern or the scanning angle is shifted, the error is corrected and the center of the target object is corrected. The direction scanning angle can be obtained accurately.

In step S26, it is determined whether or not the target object exists on the own lane, based on whether or not the following inequality is satisfied, and the process ends. θ _CV −θ _VH <θ _C <θ _CV + θ _VH θ _CV = sin ⁻¹ (L / 2 · _RL ) Here, θ _CV is the lane center angle determined by the curvature _RL and the relative distance between the target object. is there. That is, the scan center angle θ
_C is a half-vehicle width angle θ _{VH to the} left and right about the own lane center angle
It is determined that the target object exists on the own lane if it is within the range up to.

In step S28, it is determined whether or not the target object is dangerous to the own vehicle based on the relative distance and the relative speed of the target object on the own lane. To end.

[0025]

As described above, according to the first aspect of the present invention, a radar means for emitting a radio wave in front of the own vehicle, receiving a reflected signal and detecting a target object, and scanning the detection direction of the radar means. Scanning means, and sequentially moving the antenna gain pattern of the radar means relative to the entire distribution pattern of the received reflected signal level of the radar means with respect to the scanning angle.
Performs correlation calculation at each moving position, relative to the whole above the distribution pattern of the highest correlation the antenna gain pattern
And a center direction detecting means for detecting a scanning angle of the target object in the center direction from a typical moving position .

For this reason, the reflection at the target object is non-uniform,
And even if noise is superimposed on the received reflection signal, the ideal distribution pattern of the reception reflection signal level should almost match the antenna gain pattern, and the peak in the distribution pattern of the reception reflection signal level is detected by similar approximation. Can,
It is possible to accurately detect the scanning angle of the target object in the center direction.

According to a second aspect of the present invention, in the scanning radar apparatus according to the first aspect, when traveling in a curve, the central scanning angle between a pair of end points at which the distribution pattern of the received reflected signal level exceeds a predetermined threshold. And a center direction correcting means for performing a predetermined correction corresponding to the curve direction to obtain the scanning angle of the target object in the center direction.

For this reason, even when the target object is inclined with respect to the emission direction of the radio wave when traveling on a curve, the distribution pattern of the received reflected signal level may not be similar to the antenna gain pattern, or the scanning angle may be shifted. By correcting the error, the scanning angle of the target object in the center direction can be accurately obtained.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a block diagram of the device of the present invention.

FIG. 3 is a flowchart of a target object center direction detection process.

FIG. 4 is a diagram for explaining the present invention.

FIG. 5 is a diagram for explaining the present invention.

FIG. 6 is a diagram for explaining the present invention.

FIG. 7 is a diagram for explaining the present invention.

FIG. 8 is a diagram for explaining the present invention.

FIG. 9 is a diagram for explaining the present invention.

FIG. 10 is a diagram for explaining the present invention.

[Explanation of symbols]

 Reference Signs List 14 radar device 12 steering device M1 radar device M2 scanning device M3 center direction detecting device M4 center direction correcting device 10 yaw rate sensor 11 ECU 13 vehicle speed sensor 15 alarm

Claims (2)

(57) [Claims] 1. Radar means for emitting a radio wave in front of a vehicle and receiving a reflected signal to detect a target object; scanning means for scanning a detection direction of the radar means; and a received reflected signal of the radar means. The antenna gain pattern of the radar means is sequentially moved relative to the entire distribution pattern with respect to the level scanning angle , and correlation is performed at each movement position.
Perform calculations, and having a central direction detecting means for detecting the center direction scan angle of the target object from the relative movement position relative <br/> whole above the distribution pattern of the highest correlation the antenna gain pattern Scanning radar device. 2. The scanning radar apparatus according to claim 1, wherein, when traveling in a curve, the distribution pattern of the received reflection signal level is in accordance with the curve direction with respect to a central scanning angle between a pair of end points exceeding a predetermined threshold. A center direction correcting means for performing a predetermined correction to obtain a scanning angle in the center direction of the target object.