JPH10325869A - Vehicle radar apparatus and automatic cruise control system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multifunctional radar device for a vehicle that is suitable, for example, for the automatic traveling control system of an inexpensive vehicle. SOLUTION: A device has a radar head that transmits beams into a region including a shoulder and receives a reflected wave and a means for detecting a position in a width direction of an own vehicle on a roadway based on the reflected wave being received by the radar head. Preferably, the transmission direction of the beams is rotated toward the shoulder side only by a specific angle of θ from a direction that is parallel to the center line of a lane, distance L from the received reflection wave to a reflected body on the shoulder is detected, and a position Xd in the width direction of the own vehicle on the roadway is detected based on the distance L and the angle θ.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device using radio waves in the millimeter wave band or a laser beam, and a distance between a preceding vehicle and the width direction of a road on which the own vehicle is traveling using the radar device. The present invention relates to an automatic traveling control system that detects the position of the vehicle and controls the traveling speed and the position in the width direction of the vehicle by steering.

[0002]

2. Description of the Related Art For the purpose of application to a warning device for rear-end collision and collision prevention, a vehicle-mounted radar system using a millimeter wave band radio wave or a laser beam has been developed. In this on-vehicle radar system, if the beam width of radio waves or light beams is too wide, not only true obstacles such as preceding vehicles that are subject to warning, but also structures on the roadside that are not subject to warning, such as guardrails, will be falsely reported. It will be detected as an obstacle.

[0003] In order not to detect such structures on the road shoulder, the width of the beam is narrowed down to an appropriate size.
However, even when the width of the beam is narrowed, when traveling on a curve, the front guardrail appears in front of the vehicle, so that detection of reflected waves from the future is inevitable. In this case, it is determined that the reflected wave is a reflected wave from the guardrail based on the characteristic of the reflected wave such as including the reflected waves from the reflectors arranged at regular intervals, and is excluded from the alarm.

[0004] With the spread of the above-mentioned vehicle radar device, an ACC (Automatic Control System) which automatically controls the speed and steering angle of the own vehicle so as to keep the inter-vehicle distance with a preceding vehicle detected by the vehicle radar device at a safe inter-vehicle distance. Adaptive Cruise Control) system is spreading. This ACC system is a CD-ROM
And a navigation system including a positioning device for the vehicle such as a GPS receiver.

In order to add an automatic control function related to steering in addition to the adaptive control function of the traveling speed by the ACC system, the position of the host vehicle on the road, which position in the lane the host vehicle is traveling, is determined. Need to detect. Further, Japanese Patent Application Laid-Open No. Hei 8-16994 discloses a technique of detecting a lane boundary using a CCD camera and issuing an alarm to a driver when the departure state of the vehicle from the traveling lane continues for a predetermined time. It has been disclosed. Using this conventional technique, an automatic steering function can be realized so that the center of the vehicle coincides with the center of the lane.

[0006]

The automatic steering function using the camera requires a relatively expensive image processing device in addition to a radar device required for detecting a distance between the vehicle and a preceding vehicle. There is a problem that the whole ACC system becomes expensive. Accordingly, an object of the present invention is to reduce the cost of an ACC system by providing a vehicle radar device having a function of detecting the position of the own vehicle on a roadway in addition to a function of detecting an inter-vehicle distance to a preceding vehicle. It is to plan.

[0007]

According to the present invention, there is provided a radar apparatus for a vehicle, which transmits a beam to an area including a road shoulder and receives a reflected wave, and a signal received by the radar head. A width direction position detecting means for detecting a position of the own vehicle on the road based on the reflected wave.

A of the present invention using the above-mentioned vehicle radar device
The CC system includes a control unit that performs automatic steering so that the position of the own vehicle in the width direction on the roadway detected by the radar device substantially coincides with the center of the lane.

[0009]

According to a preferred embodiment of the present invention, a beam is transmitted to a region including a road shoulder by rotating the beam to a road shoulder side by a predetermined angle θ from a direction parallel to the center line of the lane and transmitting a reflected wave. And the distance L between the own vehicle and the reflector on the road shoulder is detected from the reflected wave received by the radar head, and the detected distance L and the predetermined angle θ are used to detect the distance L on the roadway of the own vehicle. And a position detecting means for detecting a position Xd in the width direction.

According to a further preferred embodiment of the present invention,
The reflected wave is composed of components generated by a plurality of reflectors formed by reflectors and other structures discretely arranged on the road shoulder, and the reflected wave received by the radar head is included in the reflected wave. Amplification is performed to make the propagation losses of the components substantially equal, and the component of the maximum amplitude included in the amplified reflected wave is detected as a component by the reflector located at the center of the beam, and located at the center of the beam. The distance between the reflector and the host vehicle is calculated as the distance L.

According to a further preferred embodiment of the present invention,
The width of the shoulder of the road on which the vehicle is traveling is estimated or automatically read from a set value or an electronic road map, and the width of the road shoulder is subtracted from the above Xd to obtain the width of the road lane of the own vehicle. There is further provided means for detecting a position in the width direction from the boundary line.

According to a further preferred embodiment of the present invention,
Estimate the width of the lane in which the vehicle is traveling, or automatically read from the set value or the digitized road map, and subtract the integer value of the lane width from Xd to obtain the lane width of the lane on which the vehicle is traveling. Means for detecting a position in the width direction from the boundary line of.

[0013]

FIG. 2 is a functional block diagram showing a configuration of a vehicular radar apparatus 20 according to an embodiment of the present invention, in conjunction with an ACC system 10. As shown in FIG. This vehicle radar system 20
Represents the FM radar head 21 and the common transmitting / receiving antenna 22a,
22b, a fast Fourier transform circuit (FFT) 23, and a digital processing device (DSP) 24.

The ACC system 10 that operates while transmitting and receiving data to and from the radar apparatus 20 of the above embodiment includes an arithmetic unit 11, a GPS receiver 12, and a GPS correction data receiver 1.
3. digitized map data 14, various sensors 15a including a vehicle speed sensor, a yaw rate sensor, a stealing sensor, etc.
15n, various actuators 16a-16m including a drive mechanism for a throttle, a brake, a steering gear, etc., a key input unit 17, and a display / output unit 18.

In the ACC system 10, the position of the own vehicle is calculated from the navigation message received from the satellite by the GPS receiver 12 and the GPS correction data received by the correction data receiver 13, and the calculation unit 11 is notified. Arithmetic unit 1
1 notifies the digitized map data reproducing unit 14 of the position of the vehicle notified from the GPS receiver 12, and this reproducing unit 14
Reproduces a part of the digitized map data including the notified position of the own vehicle from the CD-ROM and transfers it to the arithmetic unit 11. The digitized map data is used as data for calculation in the calculation unit 11, is transferred to the display / output unit 18, and is displayed on a display device such as a liquid crystal display panel.

The arithmetic unit 11 converts various data indicating the traveling state of the vehicle input from various sensors such as the vehicle speed sensor 15a with the position of the vehicle detected by the GPS receiver and the reproduced map data. In this connection, various control data for controlling the running state are created by outputting the data to various actuators including the throttle valve 16a and the like to perform automatic running control. At this time, the calculation unit 11 keeps the inter-vehicle distance to the preceding vehicle detected and notified by the radar device 20 at a safe inter-vehicle distance determined according to the traveling state of the host vehicle and the like. The steering angle is controlled such that the position of the own vehicle on the lane to be notified is located substantially at the center of the traveling lane (lane).

The radar device 20 includes a transmitting / receiving antenna 2 mainly used for detecting an inter-vehicle distance to a preceding vehicle.
2a and an antenna 22b for both transmission and reception which is mainly used to detect the position of the vehicle on the road.
The FM signal beam is radiated from the transmitting / receiving antenna 22b to an area including the road shoulder ahead of the vehicle, and the reflected wave is received.

FIG. 1A shows an antenna 22b used for both transmission and reception.
FIG. 1 illustrates a state in which a radio wave beam is emitted from a vehicle to an area including a road shoulder ahead of a vehicle. This radio wave is composed of, for example, an FM signal in the millimeter wave band and has a divergence angle of θw. Have been. The outer edge of the road shoulder usually has reflectors (reflectors) A, B,
Constructs such as C, D, E, etc. are arranged at a constant cycle.

The reflected FM beam reflected by the reflector and received by the transmission / reception antenna 22b is mixed with a local FM signal by the FM radar head 21 and converted into a low-frequency beat signal. This low-frequency beat signal is transferred from the FM radar head 21 to the subsequent fast Fourier transform circuit 23, and is converted into a frequency spectrum as illustrated in FIG. In FIG. 1B, the horizontal axis represents the frequency of the beat signal generated by the reflected wave from each of the reflectors A, B, C, D, E,..., And therefore, up to each of the reflectors A, B, C, D, and E. , And the vertical axis indicates the level of the amplitude of the reflected wave from each of the reflectors A, B, C, D, E,.

Since the distance from the vehicle increases in the order of the reflectors A, B, C, D, E,..., The propagation loss of the emitted beam and its reflected wave increases in the same order, and the level decreases. . As shown in FIG. 1 (c), as the frequency (distance) increases, the amplification gain for the received reflected wave increases so as to compensate for this distance-dependent propagation loss.
This means that all reflectors A, B, C, D, E
Means to convert into a frequency spectrum of a beat signal that should be obtained under a virtual state that the object exists at an equal distance from the vehicle.

By compensating for this propagation loss so that the reflected waves from each reflector are substantially equal,
A frequency spectrum of the beat signal as illustrated in FIG. 1D is obtained. The frequency spectrum of the beat signal obtained from the reflected wave reflects the directivity of the antenna 22b, in which the level of the radiated radio wave increases as the beam approaches the center from the periphery. FIG. 1D indicates that the frequency component of the maximum level is a reflected wave from the reflector (reflector C in this example) located at the center of the irradiation beam.

Assuming that the distance in the width direction from the host vehicle to the reflector C on the roadway is Lc, the distance is given by Xd = Lc · sin θ (1) Assuming that the width of the road shoulder is d, the distance Xw from the outer edge of the own lane on the road shoulder side is given by Xw = Xd−d = Lc · sinθ−d (2)

On a road having a plurality of lanes on one side, when the width of each lane is D and n is a natural number, if Xw> n · D,
The distance Xw of the own lane from the boundary line on the shoulder side of the road is given by Xw = Xd−dn−D = Lc · sinθ−dn−D (3)

The width d of the road shoulder and the width D of the lane in the above equations (2) and (3) can be approximated by typical values.
It is also possible to read out a value corresponding to the traveling position of the own vehicle by recording it as digitized map data in the CC system 10, or to input a number determined by the driver while watching the road condition. Can also.

In the example of FIG. 1, the traveling direction of the host vehicle is parallel to the road shoulder, but in the short term, the parallel relationship may be broken. The calculation method in this case will be described with reference to FIG. FIG. 3 illustrates a case where the traveling direction of the host vehicle is rotated toward the road shoulder by an angle θoff from the center line of the lane.

The distances from the vehicle to the reflectors M and S at the center and the outer edge of the beam are defined as Rm and Rs. The lengths of the perpendiculars MJ and SK drawn from the reflectors M and S onto a line extending from the center line of the own vehicle are represented by L, respectively.
Assuming m and Ls, Lm = Rm · sinθ (4) Ls = Rs · sinθw (5) is obtained.

If a perpendicular is drawn from the reflector M onto the perpendicular SK, and this is taken as MT, the quadrilateral MTKJ becomes a rectangle. As a result, the opposite side MT and JK become parallel, and the angle (SMT) becomes θoff. From this, tan θoff = line segment MT / line segment ST (6) is obtained.

The relationship of the line segment ST = Ls−Lm = Rs · sin θw−Rm · sinθ (7) The line segment MT = Rm · cosθ−Rs · cos θw (8) is established. Therefore, from the equations (6) to (7), θoff = tan ^-1 (Rs / sinθw-Rm / sinθ) / (Rm / cosθ-Rs / cosθw) (9) Therefore, the equations (1) to Substituting θ + θoff obtained by adding θoff calculated from equation (9) into θ of (3), and Lc
May be replaced with Rm.

Next, a method for detecting the position of the host vehicle on the road at a curve will be described with reference to FIG. First, the digital signal processing unit 24 requests the ACC system 10 to notify of the curvature radius R of the road while assuming orthogonal (x, y) coordinates with the position of the own vehicle as the origin. The calculation unit 11 of the ACC system 10 calculates from the vehicle speed and the yaw rate detected by the corresponding sensor, or the radius of curvature R of the road read from the digitized map data.
To the digital signal processor 24 of the vehicle radar device 20.
Notify.

The digital signal processor 24 approximates the estimated travel locus of the vehicle based on the radius of curvature R of the road notified from the ACC system 10 by the following equation. (X−R) ² + y ² = R ² (10) The locus of the reflector group on the road shoulder is approximated by the following equation. (X−R + Xd) ² + y ² = R ² (11)

The digital signal processor 24 radiates a beam from the antenna 22a installed facing the front of the vehicle, and calculates the distance Y to the reflector CC at the center of the beam according to the method described above. Since the position (0, Y) of the reflector CC exists on the trajectory of the reflector group given by the above equation (11), (−R + Xd) ² + Y ² = R ² (12) is obtained. By solving the equation (12), Xd = R− (R ² −Y ² ) ^1/2 (13) is obtained as the position Xd on the road measured from the edge of the road shoulder.

FIG. 4 shows an example in which the position of the reflector CC located at the center of the beam is detected using a beam radiating toward the front of the vehicle. FIG. 5 shows an example in which a reflector CC located at the center of the vehicle is detected using a beam irradiated in a direction rotated toward the road shoulder side by θ from the front of the vehicle.
This will be described with reference to FIG.

As described above, the distance to the reflector CC located at the center of the beam is detected, and this is defined as Y. Assuming that the coordinates of the CC are (X ', Y'), X '= Y.sin.theta., Y' = Y.cos.theta. R + Xd) ² + (Y · cos θ) ² = R ² (15) By solving equation (15), Xd = (R−Y · sin θ) − [R ² − (Y · cos θ) ² ] ^1/2 ... (16) is obtained.

FIG. 6 shows that a plurality of beams B1, B2 and B3 having the same or different directivity are radiated in front of the host vehicle.
1 shows an embodiment of a multi-beam type vehicle radar apparatus which is a kind of electronic scanning for receiving a reflected wave. In this multi-beam type vehicle radar device, the corresponding reflected wave is received, information on the width direction position on the road is obtained independently for each beam, and thereafter, information on each beam is integrated. In addition, highly accurate and highly accurate detection of position information is performed.

In the above-described vehicle radar apparatus, the positioning of the host vehicle in the width direction on the roadway is performed by setting the relative orthogonal (x, y) coordinates with the host vehicle as the origin.
On the other hand, as illustrated in FIG. 7, absolute orthogonal (x, y) coordinates with an origin at an appropriate point near the own vehicle are set, and the position of the own vehicle that changes with time is set.精度, △, □, ▽, and the positions ●, ▲, ■, ▼ of the plurality of reflectors on the road shoulder detected at the positions of the respective vehicles are subjected to statistical processing such as the least squares method, thereby achieving high accuracy and high accuracy. It is also possible to adopt a configuration in which the traveling locus of the own vehicle and the locus of the road shoulder of the accuracy are obtained, and the position of the own vehicle in the width direction on the road is calculated based on these locus.

The present invention has been described above by taking the case where the FM radar system is adopted as an example. However, it is also possible to adopt a pulse radar system that radiates a pulsed radio wave to a region including the road shoulder and receives a reflected wave from each reflector. In this case, the pulse-like reflected waves from each reflector are amplified by an amplifier whose amplification gain increases with time and then arranged on the time axis, and the pulse is positioned at the center of the radiation beam from the position of the pulse having the maximum amplitude. The distance to the reflector is calculated.

Further, the case of radiating a radio wave beam has been exemplified. However, by emitting a pulsed laser beam with a weak directivity and receiving a reflected wave, or by scanning a pulsed laser beam with a sharp directivity at an appropriate angle range and emitting and receiving a reflected wave, A configuration in which the position of the host vehicle in the width direction on the roadway may be detected.

Further, the beam scanning method is not limited to the electronic method, but may be a mechanical scanning method. Further, a configuration may be adopted in which the position in the width direction is detected with higher accuracy by comparing the position in the width direction of the road detected by the radar device of the present invention with the position in the width direction detected by the camera.

[0039]

As described above in detail, according to the vehicular radar apparatus of the present invention, a radar head for transmitting a beam to an area including a road shoulder and receiving a reflected wave, and a reflected wave received by the radar head And a position detecting means for detecting the position of the own vehicle on the road based on the vehicle. By using such a vehicle radar device, a relatively expensive image processing device becomes unnecessary. In addition, since the position in the width direction can be measured using a radar device for measuring the distance to the obstacle ahead, the effect that the entire automatic cruise control system can be realized at low cost can be achieved.

Further, according to the present invention, the lane keeping function can be realized by making only a slight change to the ACC system equipped with the radar device necessary for detecting the inter-vehicle distance from the preceding vehicle. For this reason, low cost and highly functional A
A CC system can be realized.

[Brief description of the drawings]

FIG. 1 is an operation principle of the present invention in which a beam of a radio wave is emitted to an area including a road shoulder in front of a vehicle, and a reflected wave is received and analyzed to detect a position in a width direction on a roadway. It is a conceptual diagram for demonstrating.

FIG. 2 is a functional block diagram showing a configuration of a vehicular radar device 20 according to an embodiment of the present invention, together with a relationship with an ACC system 10;

FIG. 3 is a conceptual diagram for explaining another operation principle of the present invention.

FIG. 4 is a conceptual diagram for explaining still another operation principle of the present invention.

FIG. 5 is a conceptual diagram for explaining still another operation principle of the present invention.

FIG. 6 is a conceptual diagram for explaining still another operation principle of the present invention.

FIG. 7 is a conceptual diagram for explaining still another operation principle of the present invention.

[Explanation of symbols]

 10 ACC system 11 Computing unit 12 GPS receiver 13 GPS correction data receiver 14 Electronic map data reproducing unit 15 Various sensors 16 Various actuators 20 Vehicle radar device 21 FM radar head 22a, 22b Common transmitting and receiving antenna 23 High-speed Fourier transform circuit 24 Digital processing section

Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B62D 13:00

Claims (9)

[Claims] 1. A radar head for transmitting a beam to an area including a road shoulder and receiving a reflected wave, and a position detecting means for detecting a position in a width direction of a vehicle on a road based on the reflected wave received by the radar head. A radar device for a vehicle, comprising: 2. A radar head for transmitting a beam and receiving a reflected wave by rotating a predetermined angle θ in a region including a road shoulder from a direction parallel to the center line of the lane to a road shoulder, and a reflection received by the radar head. The distance L between the own vehicle and the reflector on the road shoulder is detected from the wave, and the position X in the width direction of the own vehicle on the roadway is obtained from the detected distance L and the predetermined angle θ.
and v. a position detecting means for detecting d. 3. The reflected wave received by the radar head according to claim 2, wherein the reflected wave comprises components generated by a plurality of reflectors formed by reflectors or other structures discretely arranged on the road shoulder. On the other hand, a correction is made to make the propagation loss of each component included in the reflected wave substantially equal, and the component of the maximum amplitude included in the corrected reflected wave is a component by the reflector positioned at the center of the beam. A vehicle radar device wherein the distance between the detected vehicle and the reflector located at the center of the beam and the host vehicle is calculated as the distance L. 4. The vehicle according to claim 2, wherein the width of the road shoulder of the road on which the vehicle is traveling is estimated, or automatically read from a set value or an electronic road map, and the width of the road shoulder is subtracted from the Xd. A vehicle radar apparatus further comprising means for detecting a position in a width direction from a boundary line of a traveling lane of a host vehicle on a road shoulder side. 5. The vehicle according to claim 4, wherein the width of the lane in which the vehicle is traveling is estimated or automatically read from a set value or an electronic road map, and an integer value of the lane width is subtracted from the Xd. A vehicle radar apparatus further comprising means for detecting a position in a width direction from a boundary line on a road shoulder side of a traveling lane of the host vehicle. 6. The vehicle according to claim 2, wherein the predetermined angle θ is a predetermined rotation angle from a center line of the vehicle to a road shoulder side, and a center line of the vehicle and a center line of the lane. And the deviation angle θoff is determined from the distribution of the level of the reflected wave. 7. The vehicle according to claim 2, wherein an expected traveling trajectory of the vehicle on a curved road is approximated by a first arc having a radius of curvature R, and an outer edge line of the road shoulder is defined by the first arc. Is approximated by a second arc shifted outward from the center by approximately the Xd, and the reflector on the road shoulder detected by the vehicular radar device is arranged at a predetermined position on the second arc, A vehicle radar device, wherein a position xd of the host vehicle in a width direction on a road is detected. 8. A distance from the vehicle in front and a widthwise position of the vehicle on the roadway are detected by emitting a beam in front of the vehicle and receiving a reflected wave from the reflector. Vehicle radar device. 9. A radar head for transmitting a beam to an area including a road shoulder and receiving a reflected wave, and position detecting means for detecting a position in a width direction of a vehicle on a road based on the reflected wave received by the radar head. An automatic cruise control system, comprising: control means for performing automatic steering so that the position in the width direction detected by the position detection means substantially coincides with the center of the lane.