JPH05273340A - On-vehicle radar equipment - Google Patents

Abstract

PURPOSE:To rationally and easily obtain a beam width which can correspond to the variation of the spread angle of an area to be measured by providing a control means which reduces the beam width of radio waves radiated from an antenna as the speed of a vehicle increases. CONSTITUTION:Since a CPU 34 moves a parabolic reflector 11 in the advancing direction of a vehicle and radiates a long sharp beam having a narrow width by driving a motor 32 through a motor driver 33 so that a feed horn 12 can approach the focal point of the reflector 11 when the speed of the vehicle detected by means of a vehicle speed sensor 35 increases, a remote obstruction can be detected when the vehicle runs at a high speed. On the contrary, when the vehicle runs at a low speed at the time of crossing an intersection or changing its advancing direction, the detectable extent in the lateral direction is expanded by widening the beam width by separating the horn 12 from the focusing position of the reflector 11. Therefore, the detectable extent in the lateral direction is expanded at the sacrifice of the detectable distance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle radar device used for a vehicle collision prevention device or the like.

[0002]

2. Description of the Related Art Currently, an on-vehicle radar device is under development for preventing a vehicle collision. This on-vehicle radar device detects a positional relationship with a preceding vehicle or an oncoming vehicle by radiating waves such as light, ultrasonic waves, and radio waves in front of the vehicle body and receiving reflected waves thereof. As a vehicle-mounted radar device that uses radio waves, as disclosed in Japanese Patent Application No. 64-86984, the FM radar system is considered promising because of the need for short-distance monitoring. In such an on-vehicle radar device, an obvious matter that the divergence angle of the beam is adjusted in accordance with the divergence angle of the area whose distance is to be measured is described in JP-A-64-1992.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
No. 92 does not specifically disclose how to determine the divergence angle of the region to be measured, and it simply has a case where the vehicle travels on a straight track and a curve. It only shows an example in which the spread angle to be measured may be different when traveling on an orbit. Therefore, it is desired to provide a rational and simple means for controlling the beam width according to the change in the spread angle of the region to be measured.

Further, in the range disclosed in the above-mentioned Japanese Patent Laid-Open No. 64-1992, there is no specific disclosure about how to adjust (control) the beam divergence angle. Therefore, it is desired to provide a rational and simple control means for performing the adjustment.

[0005]

An on-vehicle radar device according to the present invention comprises an antenna for radiating a beam of radio waves, a transceiver for supplying radiated radio waves to the antenna and a radio wave received by the antenna, and Beam width control means for decreasing the width of the beam of the radio wave radiated from the antenna as the vehicle speed increases.

[0006]

1 is a block diagram showing the structure of an on-vehicle radar device according to an embodiment of the present invention. 10 is an antenna, 20 is a transceiver, and 30 is a beam width control section. Antenna 10
Is a parabolic reflector 11 and a feed horn (radiator) 1
It consists of two. The beam width control unit 30 includes the reflector support 3
1, linear motor 32, motor driver 33, CPU3
4 and speed sensor 35.

2 and 3 are a side view and a front view showing the external appearance of part of the beam width control unit 30 and the antenna 10, the transceiver 20, and (X, Y, Z) in the drawings. The rectangular coordinates are set for convenience of explanation.

The transceiver 20 is installed in the front end portion of the vehicle while being housed in the housing 21. The front view (FIG. 3) is viewed from the front side (Z-axis direction) of the vehicle, and the right side is the front side (Z-axis direction) of the vehicle in the side view (FIG. 2). A feed horn 12 that is electrically coupled to the transceiver 20 is planted on the upper surface of the housing 21, and radiates a millimeter wave band radio wave backward and obliquely upward of the vehicle. The feed horn 1 is provided diagonally above the feed horn 12.
Parabolic reflector 1 so that 2 is located at the focal position
1 is supported by the reflector support 31. The reflector support 31 is held so as to be displaceable in the Z-axis direction by a linear motor 32 fixed to the transceiver housing 21.

As shown by the dotted line in FIG. 2, the millimeter wave band radio wave emitted from the feed horn 12a obliquely rearward and upward is reflected by the parabolic reflector 11 to be emitted as a substantially horizontal beam forward. In this way, the feed horn 12
A parabolic antenna in a form in which is arranged outside the path of the transmission / reception beam is called an offset parabolic antenna. This offset parabolic antenna is suitable for vehicle installation because the feed horn does not block the beam, the aperture efficiency is improved and the directivity is sharpened, and as a result, the parabolic reflector can be downsized.

In the on-vehicle radar device of the above-described embodiment, the parabolic reflector 11 is moved forward / backward in the traveling direction of the vehicle by the linear motor 32, whereby the feed horn 12 fixed on the housing 11 of the transceiver 10 is moved. The position of the parabolic reflector 11 can be relatively close to or away from the focus. As shown in FIG. 4, when the feed horn 12 approaches the focus of the parabolic reflector 11, a narrow and sharp beam is emitted as shown by beam β1, and conversely, the feed horn 12 causes the parabolic reflector 11 to move. Beam b1 when out of focus
A wide beam is emitted as shown by.

The adjustment of the beam width by the movement of the parabolic reflector 11 is automatically performed by the CPU 34 according to the speed of the vehicle detected by the vehicle speed sensor 35. That is,
The CPU 34 receives the vehicle speed detected by the vehicle speed sensor 35,
By driving the motor 32 through the motor driver 33 so that the feed horn 12 approaches the focal position of the parabolic reflector 11 as the vehicle speed increases, the reflector 11 is moved forward or backward in the traveling direction.

When traveling at a high speed, it is necessary to extend the detectable distance forward in order to detect a distant obstacle, and it is necessary to sharpen the beam for this purpose. The width of the beam that can be detected decreases with the sharpening of the beam. However, since the steering angle becomes small when traveling at high speed from a safety standpoint, there is no inconvenience even if the width of the beam that can be detected is narrow. On the contrary, as understood from the assumption of intersections, the steering angle tends to increase as the speed decreases. Therefore, it is necessary to widen the width that can be detected, and it is necessary to widen the beam width. The detectable distance decreases as the beam width increases, but there is no inconvenience because it is sufficient to detect an obstacle at a short distance when traveling at low speed.

FIG. 5 is a front view showing the configuration of the antenna 10 and the transceiver 20 of the vehicle-mounted radar device according to another embodiment of the present invention. The difference between this embodiment and the above embodiment is that the feed horns 12 of the antenna 10 are arranged in the lateral direction (X-axis direction) near the focal point of the reflector 11 to form four feed horns 12a, 12b, 12c, 12d, and therefore the overall configuration is the block diagram of FIG.
The side view is replaced by the side view of FIG. 2, and the same components are designated by the same reference numerals.

As shown in FIG. 6, the millimeter-wave band radio waves radiated from the four radiators 12a to 12d arranged near the focal point of the parabolic reflector 11 are aligned with the radiation direction in the XZ plane. Four beams B1 and B with different beam widths
2, B3, B4 are emitted forward. In this manner, a configuration in which a plurality of radiators are arranged so as to be displaced from the focal position of the parabolic reflector and a plurality of beams having different radiation directions are emitted is called a defocus multi-beam antenna. This defocused multi-beam antenna has an optimum form as a vehicle-mounted antenna that requires a small beam width or scan width but requires a small size.

In a low-speed traveling state in which the vehicle speed detected by the vehicle speed sensor 35 does not reach a predetermined threshold value, the CPU 34 has two feed horns 12a, 12d outside the focus.
By supplying a radio wave only to emit the beams B3 and B4, the detection width of the entire beam emitted from the antenna 10 is increased. The CPU 34 radiates from the antenna 10 by supplying radio waves only to the inner two feed horns 12b and 12c close to the focal point to radiate the beams B1 and B2 in a high-speed traveling state where the vehicle speed exceeds a predetermined threshold value. Increase the detection distance of the entire beam being irradiated.

In addition to controlling the beam width by selecting the beam, the CPU 34 also adjusts the beam width by moving the parabolic reflector 11. That is, the CPU 34 receives the vehicle speed detected by the vehicle speed sensor 35, and the motor driver 33 so that the feed horns 12 a to 12 d approach the focal position of the parabolic reflector 11 as the vehicle speed increases.
The reflector 11 is moved forward or backward in the traveling direction by driving the motor 32 via.

The configuration for controlling the beam width according to the traveling speed by combining the beam selection and the reflector movement in the defocused multi-beam antenna has been exemplified above. However, it is also possible to adopt a configuration in which the reflector is fixed in the defocus multi-beam antenna and the beam width according to the traveling speed is controlled only by selecting the beam.

Further, although the parabolic shape is used as the reflector, various reflectors having a substantially parabolic shape including some deformed shapes can be used.

[0019]

Since the on-vehicle radar device of the present invention has a structure in which the width of the beam of the radio wave radiated from the antenna is reduced as the vehicle speed increases, it copes with the change in the spread angle of the region to be measured. There is an advantage that the controlled beam width can be reasonably and easily realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an on-vehicle radar device according to an embodiment of the present invention.

FIG. 2 is a side view of a portion of an antenna and a transceiver of the above embodiment.

FIG. 3 is a front view of a portion of an antenna and a transceiver of the above embodiment.

FIG. 4 is a conceptual diagram for explaining how the beam width changes due to movement of a parabolic reflector.

FIG. 5 is a side view of a portion of an antenna and a transceiver of an on-vehicle radar device according to another embodiment of the present invention.

FIG. 6 is a conceptual diagram for explaining that the beam width is changed by selecting a part of a plurality of beams in the other embodiment.

[Explanation of symbols]

 10 Antenna 11 Parabolic Reflector 12 Feed Horn (Radiator) 20 Transceiver 21 Transceiver Housing 31 Reflector Support 32 Linear Motor 33 Motor Driver 34 CPU 35 Vehicle Speed Sensor

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 3, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art Currently, an on-vehicle radar device is under development for preventing a vehicle collision. This on-vehicle radar device detects a positional relationship with a preceding vehicle or an oncoming vehicle by radiating waves such as light, ultrasonic waves, and radio waves in front of the vehicle body and receiving reflected waves thereof. As a vehicle-mounted radar device that uses radio waves, as disclosed in Japanese Patent Application No. 64-86984, the FM radar system is considered promising because of the need for short-distance monitoring. In such an on-vehicle radar device, Japanese Patent Laid-Open No. 64-1992 describes a high-level concept of adjusting the divergence angle of a beam according to the divergence angle of a region whose distance is to be measured.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

[0003]

The above-mentioned Patent Document [0006], car
Both are traveling on a straight track and a track with a curve
The spread angle to be measured is different when traveling on the road.
Although it shows that it is different, how to determine this spread angle
There are still issues to be solved. Therefore, there is a demand for a rational and simple means for controlling the beam width according to the change in the spread angle of the region to be measured.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

Also, how to adjust the beam divergence angle
There remains a problem to be solved regarding whether to adjust (control) .
Therefore, rational and simple means for making adjustments are desired.

Claims (3)

[Claims] 1. An antenna for radiating a radio wave beam, a transmitter / receiver for supplying a radiated radio wave to the antenna and receiving a radio wave received by the antenna, and a width of the radio wave beam radiated from the antenna for a vehicle. A vehicle-mounted radar device, comprising: a beam width control unit that decreases with an increase in speed. 2. The antenna comprises a single radiator electrically coupled to the transceiver and radiating radio waves rearward and obliquely upward of the vehicle, or a plurality of radiators arranged in the vehicle width direction of the vehicle. A parabolic shape or almost a parabola that is arranged diagonally above each radiator while positioning the single or multiple radiators near the focal point and emits the radio waves emitted from the radiators as a beam toward the front of the vehicle. And a beam-shaped control means, wherein the beam width control means causes the reflector of the antenna to approach the single or a plurality of radiators according to the speed of the vehicle.
The vehicle-mounted radar device according to claim 1, further comprising means for separating the vehicle-mounted radar. 3. The antenna comprises a plurality of radiators electrically coupled to the transceiver and arranged in the vehicle width direction of the vehicle for radiating radio waves rearward and obliquely upward of the vehicle, and these radiators are focused. And a parabolic or nearly parabolic reflector that is placed diagonally above each radiator while being positioned in the vicinity of and emits the radio waves radiated from this radiator to the front of the vehicle as a beam with different directivity. 2. The beam width control means comprises beam selection means for selecting only a part of a plurality of radio wave beams emitted from the antenna according to the speed of the vehicle. In-vehicle radar device.