JP2000180532A - Object position detection method of scan-type radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the position of an object, especially, the center position of the object, in various states by detecting the angle of the peak of the power of a reflected beam as the center position of the object when there is one peak of the power of the reflected beam. SOLUTION: At a radar signal processing part 12, a reflection signal from a radar antenna 1 is subjected to FFT processing, a power spectrum is detected, distance to a target and relative speed are calculated, and the data is sent to a recognition part 13 to be controlled. At the recognition part 13 to be controlled, based on the distance to the target being received from the radar signal processing part 12, the relative speed, and vehicle information being received from an ECU 7 for controlling the distance between cars, a scan angle is instructed to a scan angle control part 11, and at the same time the target to be controlled is judged for transmitting to the ECU 7 for controlling the distance between cars. At the scan angle control part 11, the scan angle or the like on traveling in a curve is controlled in the case of a fixing-type radar, and the scan angle is controlled in the case of a scan-type radar. In a scan mechanism 2, a control signal from the scan angle control part 11 is received, and beams are successively emitted at a specific angle for scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type radar, and more particularly to a method for detecting an object position of a scanning type radar which is mounted on a vehicle and sequentially scans a beam at a predetermined angle to scan and detect an object.

[0002]

2. Description of the Related Art In an inter-vehicle distance control, an on-vehicle radar device that emits a radar beam in front of a host vehicle and detects an object such as a preceding vehicle is used. Some radar apparatuses use radio waves such as millimeter waves, and others use laser beams. Using these radar devices, the distance to the preceding vehicle, the relative speed with respect to the preceding vehicle, and the accurate position of the preceding vehicle are detected, and the following distance control is performed. In order to accurately detect the position of the preceding vehicle, it is important to detect the center position of the preceding vehicle.

[0003]

For example, in the case of a millimeter-wave scanning radar, various factors are added to the detection area in addition to the spread of the antenna pattern, and it is difficult to accurately detect the position of an object. When the center position of the preceding vehicle is obtained, the center position can be obtained by estimating the end position of the preceding vehicle from the form of the reception level of the reflected signal. But,
Since the reflection from the vehicle is not uniform and the noise is superimposed on the reflection signal, the end position of the preceding vehicle cannot always be detected accurately, and the part with the highest reflection level is the center of the object. However, the center position of the preceding vehicle may not be accurately obtained. For example,
For a point object such as a corner reflector, the peak position of the reflected power can be determined to be the center of the object, but since the shape and size of the preceding vehicle are various, the peak position is always the center of the object. Not necessarily. For example, when a large vehicle is detected at a short distance, the reflected power does not always reach the maximum at the center of the object.

Accordingly, an object of the present invention is to provide a method for accurately detecting the position of an object, particularly the center position of the object, in various situations in a scanning radar.

[0005]

In order to solve the above-mentioned problems, the present invention solves the above problem by changing the peak shape of the reflected beam power which appears in various forms depending on the size of the object, the distance to the object, and the like. It is an object of the present invention to provide a method for detecting a position, in particular, a center position of an object. According to the object position detection method of the scanning radar of the present invention, when the reflected beam has one power peak, the angle of the reflected beam power peak is detected as the center position of the object.

When the number of peaks of the power of the reflected beam is plural and the number of peaks formed by the plural peaks is one, the peak having the largest power among the plural peaks and both sides thereof Is detected as the center position of the object. Further, when the number of peaks of the power of the reflected beam is plural and the number of peaks formed by the plural peaks is plural, the center angle of the width of the angle at both ends of the peak is set as the center position of the object. To detect.

In the case where the number of peaks of the power of the reflected beam is plural, the number of peaks formed by the plural peaks is plural, and the power of the reflected beam includes the reflection by the side lobe. , A threshold is set to remove the power of reflection by the side lobe, and the angle of the center of the width at the peak angles at both ends of the remaining peak is detected as the center position of the object.

Further, the center position of the object is detected by combining the above methods. If the number of peaks of the power of the reflected beam is plural, the area of the surface formed from the power and the angle is obtained, and the angle obtained by dividing the obtained area into two is detected as the center position of the object.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an outline of the configuration of an inter-vehicle distance control device using a scanning radar. The radar sensor unit is, for example, a millimeter-wave radar, and includes a radar antenna 1, a scanning mechanism 2, and a signal processing circuit 3.
The inter-vehicle distance control ECU 7 receives signals from the steering sensor 4, the yaw rate sensor 5, the vehicle speed sensor 6, and the signal processing circuit 3 of the radar sensor unit, and controls the alarm 8, the brake 9, the throttle 10, and the like. The inter-vehicle distance control ECU 7 also sends a signal to the signal processing circuit 3 of the radar sensor unit.

FIG. 2 shows the configuration of the signal processing circuit 3 of FIG. The signal processing circuit 3 includes a scanning angle control unit 1
1, a radar signal processing unit 12, and a control target recognition unit 13. The radar signal processing unit 12 performs FFT processing on the reflected signal from the radar antenna 1, detects a power spectrum, calculates the distance to the target and the relative speed, and transmits the data to the control target recognition unit 13. The control target recognizing unit 13 receives the distance from the target, the relative speed received from the radar signal processing unit 12, and the vehicle information obtained from the steering sensor 4, the yaw rate sensor 5, the vehicle speed sensor 6, and the like received from the inter-vehicle distance control ECU 7. The scan angle is instructed to the scan angle control unit 11 on the basis of this, and the target to be controlled is determined and transmitted to the following distance control ECU 7.
The scanning angle control unit 11 controls a scanning angle or the like when traveling on a curve in the case of a fixed radar, and controls a scanning scanning angle in the case of a scanning radar. The scanning mechanism 2 receives a control signal from the scanning control unit 11 and sequentially emits a beam at a predetermined angle to perform scanning.

In the above configuration, the radar sensor unit is, for example, a millimeter wave radar, but may be a laser radar.
Hereinafter, how the center position of the object is detected by the scanning radar of the inter-vehicle distance control device shown in FIGS. 1 and 2 will be described. FIG. 3 shows a state in which the vehicle B preceding the own vehicle A is a small object such as a motorcycle, and is traveling relatively far ahead of the own vehicle A, for example, 100 m ahead. In such a case, only one beam is reflected from the preceding vehicle B as shown in FIG. As a result, the beam reflected from the preceding vehicle B is represented as one peak having the power p at a certain beam emission angle θ, as shown in FIG. Therefore, in such a case, the angle of this peak is detected as the center of the object. In this case, the radar signal processing unit 12 in FIG. 2 calculates and detects the center position and the distance of the preceding vehicle B from the reflected power p and the angle θ, and sends them to the control object recognition unit 13.

FIG. 4 shows that the vehicle B ahead of the own vehicle A
A relatively small object, relatively close ahead of the vehicle A, for example
For example, the vehicle is traveling 20 m ahead. This
In such a case, as shown in FIG.
What is done is multiple beams. As a result, the preceding vehicle B
The beam reflected from is shaped like a single peak
The beam launch angle as shown in FIG.
Degree θ_a,θ_b,θ_c,θ_d,θ _ePower p at_a,p_b,p_c,p
_d,p_eAre represented as multiple peaks with in this case
Reflections in the preceding vehicle are not always uniform
The shape formed by the peak as shown in FIG.
The shape often has multiple peaks, and the reflected power at both ends
p_aAnd p_eOften represents the width of the preceding vehicle.
No. Therefore, the reflected power p_aAnd p_eWidth W at an angle of
Angle θ which is the center position (position of W / 2)_cPosition ahead
It is detected as the center position of the traveling vehicle. In addition, FIG.
Then θ_cPosition is θ_aAnd θ_eThe center between
Is generally the center position of the width W of the angle._xIs θ_x= (Θ₁+ Θ_Two) / 2. Where θ₁And θ_TwoIs the opposite of
Indicates the angle of the firing power. In this case, the radar signal processing of FIG.
The processing unit 12 has a reflection power p_a-P_eAnd angle θ_a−θ_eOr
Calculate and detect the center position and distance of the preceding vehicle B from
This is sent to the control target recognition unit 13.

FIG. 5 shows a state in which the vehicle B preceding the own vehicle A is a large object such as a truck, and is traveling forward, for example, 100 m ahead, which is relatively far from the own vehicle A. . In such a case, a plurality of beams are reflected from the preceding vehicle B as shown in FIG. As a result, beam reflected from the preceding vehicle B, as shown in FIG. 5 (b), beam emission angle _{θ a, θ b, θ c} , the power in the _{θ d p a, p b,} p c, p d In many cases, the shape of the peak is composed of a plurality of peaks having a peak. Regarded as close to the center position of the angle theta _b is a preceding vehicle in such a case, the largest power p _b, using peak p _b the peak p _a and p _c on both sides as data for position detection. And determining the angle theta _x of the center of the object in consideration of the size of the three power _{p a, p b, p c} . Angle of center and angle theta _x the size of the three power are balanced. Specifically, the angle θ _x
Is determined by the following equation.

Θ _x = ｛θ _b (p _a −p _b ) + θ _c (p _b
−p _c )｝ / (p _b + p _c ) In the above equation, θ _x, θ _{b, and} θ _c are angles based on θ _a . In this case, the radar signal processor 12 of FIG. 2 obtains an angle theta _x to the equilibrium from reflected power p _a -p _d and the angle theta _a - [theta] _d, detected by calculating the center position and the distance and the like of the preceding vehicle B Then, it sends it to the control target recognition unit 13.

FIG. 6 shows an object which is a preceding vehicle in all beams.
This is a state in which detection is performed. For example, FIG.
(A) As shown in FIG.
In addition, if the vehicle is located immediately in front of vehicle A,
All beams of the radar (for convenience, the main beam
Is assumed to be reflected by the preceding vehicle B)
In this case, the beam firing angle θ as shown in FIG._a,θ
_b,θ_c,θ_d,θ_e,θ_f,θ_g,θ_h,θ_i,θ_j,θ_kPower in
-P_a,p_b,p_c,p_d,p_e,p_f,p_g,p_h,p_i,p_j,p _kHave
Represented as multiple peaks. Of these powers
p_a,p_b,p_cAnd p_i,p_j,p_kThe peak level of the other
It is lower than the power. This is the side robe
Reflection from the object, and is not necessary for detecting the position of the object.
Threshold p_thAnd remove the remaining peaks.
P_d,To p_hAngle of the center of the width W at the angle of the peak of
Degree θ_xIs detected as the center of the preceding vehicle. θ_xIs
It is determined by the following equation.

Θ _x = (θ _d + θ _h ) / 2 In the figure, θ _x = θ _f . Whether or not the reflection is caused by the side lobe is determined as follows.
FIG. 7 is a diagram showing a main beam and its side lobe.
Side lobes b and c are generated on both sides of the main beam a, and the angle θ with the main beam is 4 ° or more. Therefore, whether or not the reflection is caused by the side lobe is determined to be the reflection by the side lobe if it is separated by 4 ° or more from the beak of the reflection by the main beam, and the reflection power of this portion is cut off by a threshold value and removed.

In this case, the radar signal processing unit 12 in FIG. 2 determines the presence or absence of a side lobe from the reflected power p _a -p _K and the angle θ _a -θ _K , and removes the reflected power due to the side lobe based on a threshold. , The center position and the distance of the preceding vehicle B are calculated and detected, and sent to the control object recognition unit 13.
FIG. 8 is a diagram illustrating a case where the angle of the center of the object is detected from the area of the surface formed from the reflected power of the beam and the angle of the beam. The reflection of the beam from the object is the angle θ _a, θ
_{b, θ c, θ d} in the power p _a, p _b, and emerged as p _c, p _d. In such a case, the area of a portion surrounded by oblique lines is obtained. Since this area is composed of parts A, B, and C, the area of each part is determined. For example, the area of the portion A is obtained by the following equation.

A = (p _a + p _b ) (θ _b -θ _a ) / 2 Similarly, the areas of B and C are obtained, and the area of the hatched portion can be obtained. Then, an angle θ _x that divides the area obtained by the above equation into two is obtained, and the position of this angle is set as the center of the detected object. In this case, the radar signal processing unit 12 in FIG. 2 calculates the reflected power p _a −p _d and the angle θ _a −θ _d
The areas of A, B, and C are obtained, the angle at which this area is bisected is calculated, the center position and the distance of the preceding vehicle B are detected, and sent to the control target recognition unit 13.

The above describes how to detect the position of an object, particularly the center position of the object, in accordance with the peak shape of the reflected power that appears in various forms depending on the size of the object, the distance to the object, and the like. It is stated. Next, a method of using the above detection methods in combination will be described. FIG. 9 is a flowchart showing a procedure of a method using the above detection methods in combination. In the flowchart of the figure, the determination in each step is performed by the radar signal processing unit 13 in FIG.

In the flowchart of FIG. 1, it is first determined whether or not the detected peak of the reflected power is more than one (S1). If it is not more than 1 (No), that is, if it is 1, it is considered that the situation is as shown in FIG.
The angle at which the peak occurs is detected as the center position of the preceding vehicle (S2). If the peak of the reflected power is more than one (Yes), then it is determined whether or not the peak formed by the peak has more than one peak (S3). If it not more than 1 (No), i.e., is considered that in the case of 1 is a situation shown in FIG. 5, the largest power p _b
Is considered close to the center position of the preceding vehicle, and the peak p
_b and using a peak p _a and p _c on both sides as data for position detection. And these three powers p _a, p _b, p
_The angle θ _x at which the power is balanced is determined in consideration of the size of _c , and this angle is detected as the center position of the object (S
4).

If there is more than one peak in the shape formed by the peak of the reflected power (Yes), that is, if there are a plurality of peaks, it is determined whether or not the reflected power due to the side lobe exists (S5). Whether or not the reflected power due to the side lobe exists can be determined by detecting whether or not the reflected power exists at an angle of 4 ° or more from the angle of the reflected power due to the main beam. If does not exist (No), it is considered that the situation shown in FIG. 4, for detecting the position of the reflected power p _a and p is the center position position of the width W of the _e theta _c at both ends as the center position of the preceding vehicle (S7).

When the reflected power due to the side lobe exists (Yes), it is considered that the situation is as shown in FIG. 6, so that the reflected power due to the side lobe is removed by setting a certain threshold (S6). Then, the angle of the center of the width at the angle of the reflected power after the removal is obtained, and the position of the angle is detected as the center position of the preceding vehicle (S7). It should be noted that the method of obtaining from the area shown in FIG. 8 can be used independently in any situation separately from the method shown in the flowchart.

[0023]

According to the method of the present invention, the center position of the object can be detected according to the peak shape of the power of the reflected beam appearing in various forms. Therefore, in a scanning radar, the position of an object, particularly the center position of the object, can be accurately detected in various situations.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a configuration of an inter-vehicle distance control device using a scanning radar.

FIG. 2 is a diagram illustrating a configuration of a signal processing circuit of FIG. 1;

FIG. 3 is a diagram showing a state in which a vehicle preceding the own vehicle is traveling relatively small and relatively ahead.

FIG. 4 is a diagram showing a state in which a vehicle preceding the own vehicle is relatively small and is traveling relatively close ahead.

FIG. 5 is a diagram illustrating a state in which a vehicle ahead of the host vehicle is traveling large and relatively distant ahead.

FIG. 6 is a diagram showing a state in which a preceding vehicle is detected by all beams.

FIG. 7 is a diagram showing a main beam and its side lobe.

FIG. 8 is a diagram illustrating a case where a center angle of an object is detected from an area formed from a reflected power of a beam and an angle of the beam.

FIG. 9 is a flowchart showing a procedure of an object position detecting method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Radar antenna 2 ... Scanning mechanism 3 ... Signal processing circuit 4 ... Steering sensor 5 ... Yaw rate sensor 6 ... Vehicle speed sensor 7 ... Vehicle distance control ECU 8 ... Warning device 9 ... Brake 10 ... Throttle 11 ... Scan angle control unit 12 ... Radar signal processing unit 13 ... Control target recognition unit

 ──────────────────────────────────────────────────の Continuation of the front page (72) Inventor Makoto Takagi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 5J070 AB24 AC01 AC02 AC06 AE01 AF03 AG03 AH14 AH19 AK22 BD10 BF02 BF03 BF04 BF10 BF12 BF16 BF21 5J084 AA02 AA07 AA10 AB01 AC02 AD03 AD12 EA04

Claims (7)

[Claims] 1. A method for detecting an object position of a scanning radar, in which a beam is sequentially emitted at a predetermined angle to perform scanning, wherein the number of peaks of the power of a reflected beam is detected.
When there is only one peak, a method of detecting the angle of the peak of the power of the reflected beam as the center position of the object. 2. A method for detecting an object position of a scanning radar, in which a beam is sequentially emitted at a predetermined angle to perform scanning, wherein the number of power peaks of the reflected beam is detected.
When the number of peaks is plural, the number of peaks formed by the plurality of peaks is detected. When the number of peaks is one, the peak having the largest power among the plurality of peaks and the peaks on both sides of the peak are detected. A method of detecting an angle at which the magnitudes of powers of two peaks are balanced as a center position of an object. 3. A method for detecting an object position of a scanning radar, in which a beam is sequentially emitted at a predetermined angle to perform scanning, wherein the number of power peaks of the reflected beam is detected.
If the number of peaks is plural, the number of peaks formed by the plurality of peaks is detected, and if the number of peaks is plural, the center angle of the width of the angle at both ends of the peak is detected as the center position of the object. how to. 4. A method for detecting an object position of a scanning radar, in which a beam is sequentially emitted at a predetermined angle to perform scanning, the number of power peaks of a reflected beam being detected,
If the number of peaks is plural, the number of peaks formed by the plurality of peaks is detected, and if the number of peaks is plural, it is detected whether or not the power of the reflected beam includes reflection by a side lobe, A method of setting a threshold value to remove the power of reflection by the side lobe and detecting the center angle of the width of the angle at both ends of the remaining peak as the center position of the object. 5. A method for detecting an object position of a scanning radar, in which a beam is sequentially emitted at a predetermined angle to perform scanning, wherein the number of power peaks of a reflected beam is detected.
When there are a plurality of peaks, a method of calculating the area of a surface formed from the power and the angle and detecting an angle at which the obtained area is bisected as the center position of the object. 6. A method for detecting an object position of a scanning radar in which a beam is sequentially emitted at a predetermined angle to perform scanning, wherein the number of power peaks of a reflected beam is detected.
If the number of peaks is one, the angle of the peak of the power of the reflected beam is detected as the center position of the object. If the number of peaks of the power of the reflected beam is plural, the plurality of peaks are formed. The number of peaks to be detected is detected, and when the number of peaks is one, the angle at which the magnitude of the power of the three peaks, the peak having the largest power among the plurality of peaks and the peaks on both sides thereof, is balanced with the center of the object. When the number of peaks of the power of the reflected beam detected as a position is plural and the number of peaks formed by the plural peaks is plural, the angle of the center of the width of the angle at both ends of the peak is set to the angle of the object. Method to detect as the center position. 7. When the number of peaks of the power of the reflected beam is plural and the number of peaks formed by the plurality of peaks is plural, whether the power of the reflected beam includes reflection due to a side lobe or not. 7. The method according to claim 6, wherein a threshold value is set to determine whether or not the peak is included, the power of the reflection by the side lobe is removed, and the angle at the center of the width of the angle at both ends of the remaining peak is detected as the center position of the object.