JPH10142331A - Millimetric wave radar-loaded vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a millimetric wave radar-loaded vehicle which can detect not only a distance and a relative speed to an object, but a two-dimensional or three-dimensional meaning possessed by the object or applied beforehand to the object. SOLUTION: A transmission wave 3a is emitted from a transmission antenna 2a of a transmitting receiving antenna 2 set to a vehicle 1, and a reflected wave 3b from an object 4 is received at a receiving antenna 2b, thereby a distance L and a relative speed V to the object 4 are detected at a millimetric wave radar 5. In the vehicle loading the millimetric wave radar 5, an image- processing device 7 is loaded, with an image sensor 6 directed in a beam direction of the transmitting receiving antenna 2. The image-processing device 7 has a zoom part 8 which, when receiving information of at least the distance L from the millimetric wave radar 5, changes a size 4a of the object 4 photographed by the image sensor 6 based on the distance information to a predetermined magnification (m).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle equipped with a millimeter wave radar.

[0002]

2. Description of the Related Art Millimeter-wave radars are less susceptible to the effects of weather and dust and have a short wavelength, so that the receiving and transmitting antennas can be miniaturized, the antenna beam width θ (see FIG. 1) can be reduced, and the Doppler effect can be obtained. There is an advantage that the relative speed with respect to the object can be detected with high accuracy.

For this reason, recently, there has been an attempt to mount a millimeter-wave radar on a high-speed traveling vehicle in order to prevent a collision accident due to a driver's carelessness or misidentification on a highway. That is, as shown in FIG. 1, a transmitting wave 3a is emitted from a transmitting antenna 2a of a transmitting / receiving antenna 2 installed in a vehicle 1, and a reflected wave 3b is received from the object 4 by a receiving antenna 2b, so that a distance L to the object 4 is increased. And relative speed V (vehicle speed V ₁ -object speed V ₂ )
Is mounted.

[0004]

In mines and quarries, research on fleet operation by a plurality of unmanned vehicles is active. Also in this case, it is considered effective to mount the millimeter wave radar on these vehicles in view of the above advantages. However, unlike millimeter-wave radar-equipped vehicles that run on highways, the conventional millimeter-wave radar-equipped vehicles for operation in mines and quarries are only used for object detection that merely avoids collisions (that is, simple object presence detection). Instead, it is required that the object to be detected can be detected together with, for example, a traffic sign and its meaning, and the meaning of another vehicle and its attitude.

However, since a millimeter wave radar is basically a one-dimensional sensor (linear sensor) for detecting a distance and a relative speed to an object, such a two-dimensional or three-dimensional meaning is also detected. It is difficult to do.

The present invention has been made in view of the above-mentioned problems of the prior art,
It is an object of the present invention to provide a vehicle equipped with a millimeter-wave radar that can detect not only a distance and a relative speed to an object but also a two-dimensional or three-dimensional meaning given to the object or the object has in advance. Aim.

[0007]

A vehicle equipped with a millimeter-wave radar according to the present invention for achieving the above object will be described with reference to, for example, FIG. A vehicle equipped with a millimeter-wave radar 5 that emits a transmission wave 3a from the antenna 2a and receives a reflected wave 3b from the object 4 with the receiving antenna 2b to detect the distance L and the relative velocity V from the object 4 is as follows. It was configured as follows.

For example, referring to FIG. 2, an image processing device 7 in which an image sensor 6 is directed in the antenna beam direction of the transmitting and receiving antenna 2 is mounted. The zoom unit 8 receives the information on the distance L and changes the image pickup size 4a of the object 4 imaged by the image sensor 6 to a predetermined magnification m based on the information.

According to the above invention, first, the object 4 detected by the millimeter-wave radar 5 is affected by the transmission output and the like, but the distance L is at most 100 to 120 in the vehicle 1 equipped with the millimeter-wave radar.
m, and the antenna beam width θ is 4 to 5 ° (that is, the maximum detection width at a distance is about 3 to 4 m). For this reason, first, the image device 7 can ignore all images having a distance exceeding about 120 m and images having a width exceeding about 4 m. In addition, the image processing apparatus 7 has a zoom unit 8 that receives the distance information L from the millimeter wave radar 5 and changes the imaging size 4a of the object 4 to a predetermined magnification m based on the distance information L. For this reason, the imaged object (that is, the object that is required to correspond) after the predetermined magnification m in the image processing device 7 is the object detected by the millimeter wave radar 5 and is always at a constant size, for example. The distance storage capacity and storage software for the image processing apparatus can be substantially reduced. That is, the image processing device 7 in the vehicle equipped with the millimeter wave radar can be inexpensively and simply configured.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the examples, the specifications of the millimeter-wave radar used in this example will be described for easy understanding. It is to be noted that the same element codes as those described with reference to FIG. 1 in the section of the related art are used as they are, and the emphasis description is omitted.

A millimeter wave has a wavelength λ of 1 to 10 mm (that is, 3 mm).
00 to 30 GHz). In this example, frequency 5
9.5 GHz (ie, λ is approximately 5 mm) is used.
The signal processing method in the millimeter wave radar 5 is a pulse method,
A frequency CW method, an FM-CW method, and the like are known. In this example, the FM-CW method is adopted, and FFT (Fast Fourier Transform) is used as signal processing for further dividing a plurality of objects.
Is adopted.

In the FM-CW system, as shown in FIG. 3, a millimeter wave is modulated by a modulation wave (a triangular wave in this example), and a transmission wave 3a emitted from a transmission antenna 2a and a reception wave received by a reception antenna 2b. 3b with a mixer to obtain beat frequencies fb1 and fb2.
According to (2), the distance L and the relative speed V between the vehicle 1 and the detection object 4 are calculated.

L = C (fb2 + fb1) / (8ΔF · fm) (1) V = C (fb2-fb1) / (4fo) (2)

C is the speed of light, fb1 is the "beat frequency on the increasing side" shown in FIG. 3, fb2 is the "beat frequency on the decreasing side", and ΔF is the frequency shift width (in this example, 75 MHz; Represents the increase / decrease ± Δf as described later), and fm represents the frequency of the modulated wave (781.2 in this example).
5 Hz, which can also be increased or decreased ± Δfm, as will be described in detail later), and fo is the center frequency and the frequency of the millimeter wave (59.5 GHz).

The antenna beam width θ is expressed by the following equation (3). This is an angle up to a half value (1/2) of the maximum antenna gain at the antenna beam center c (see FIG. 1) where the antenna gain is the maximum, and indicates an effective spread range of the radio wave. In this example, θ 4 ° (that is, 2
°). θ is approximately 70λ / D (3)

The detection distance resolution performance ΔL of the radio wave radar with respect to the object 4 is obtained by the following equation (4).
L = 2 m (that is, L ± 1 m). ΔL = C / (2ΔF) (4)

Incidentally, in order to truly detect the object 4 two-dimensionally and three-dimensionally, an image processing device must be added to the vehicle equipped with the millimeter wave radar. However, if an image processing apparatus is simply added to a vehicle equipped with a millimeter-wave radar, it will be necessary to incorporate a myriad of software programs to deal with any situation in fleet operation, for example. Also, enormous time and cost are required for the software development. However, because the vehicles and courses vary from site to site, profitability is completely out of place. That is, even if the current image processing apparatus is simply added to a vehicle equipped with a millimeter-wave radar, it cannot contribute to economical fleet operation of a plurality of unmanned vehicles. Then, it constituted as follows.

That is, as shown in FIG. 2, an image processing device 7 in which the image sensor 6 is directed in the antenna beam direction of the transmitting / receiving antenna 2 provided in the vehicle 1 equipped with the millimeter wave radar is mounted. Then, the image processing device 7 has a zoom unit 8 that receives at least the distance L information from the millimeter wave radar 5 and changes the imaging size 4a of the object 4 imaged by the image sensor 6 to a predetermined magnification m based on this information. . For example, by increasing the magnification of a nearby object by 10 times and the magnification of a nearby object by 3 times, the area occupied by the object imaging on the screen is set to an optimal size regardless of the distance L (this is because the image processing apparatus is used. C
Needless to say, it does not mean that a screen such as an RT is necessary.) 9 is a vehicle control unit.

According to the above example, the following effects can be obtained. If the conventional image processing apparatus is simply mounted on a vehicle equipped with a millimeter-wave radar, other vehicles will capture images of distant scenery and road surfaces as well, so that it is difficult to specify an image to be obtained. Then, it is necessary to previously store the image to be obtained in the image processing apparatus and perform processing for removing all other images. Moreover, in order to obtain the distance to the specified object, the size of the specific object is also stored in advance, and the distance is calculated from the ratio with this size. Therefore, as described above, an enormous amount of time and expensive software are required before an operation command based on the imaging result is given to the vehicle control unit 9. However, according to the above example, first, the object 4 detected by the millimeter-wave radar 5 depends on the transmission output and the like. However, in the vehicle 1 equipped with the millimeter-wave radar, the distance L is at most about 100 to 120 m, and the antenna beam width θ is The angle is 4 to 5 ° (that is, the maximum detection width at a distance is about 3 to 4 m). For this reason, first, the image device 7 can ignore all images having a distance exceeding about 120 m and images having a width exceeding about 4 m. In addition, since the image processing apparatus 7 has the zoom unit 8 that receives the distance information L from the millimeter wave radar 5 and changes the imaging size 4a of the object 4 to the predetermined magnification m based on the distance information L, the image processing apparatus 7 uses the predetermined magnification. m
After that, all the imaging objects (that is, the objects required to respond) are the objects detected by the millimeter-wave radar 5, and at all times,
For example, since it has a fixed size, a huge amount of hardware storage capacity and storage software can be substantially eliminated for preprocessing in the conventional image processing apparatus described above. That is, the image processing device 7 in a vehicle equipped with a millimeter wave radar can be configured at a low cost and with a simple configuration.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a vehicle equipped with a millimeter wave radar.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a graph illustrating FM-CW.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vehicle 2 ... Transmission / reception antenna 2a ... Transmission antenna 2b ... Receiving antenna 3a ... Transmission wave 3b ... Reflection wave 4 ... Object 4a ... Imaging size 5 ... Millimeter wave radar 6 ... Image sensor 7 ... Image processing apparatus 8 ... Zoom part m ... Predetermined magnification

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G08G 1/16 G08G 1/16 D G09B 29/10 G09B 29/10 A

Claims (1)

[Claims] 1. A transmission wave 3a is emitted from a transmission antenna 2a of a transmission / reception antenna 2 installed in a vehicle 1, and a reflected wave 3b from the object 4 is received by a reception antenna 2b. In a vehicle equipped with a millimeter wave radar 5 for detecting V, an image processing device 7 in which an image sensor 6 is directed in the antenna beam direction of the transmission / reception antenna 2 is mounted, and the image processing device 7 includes a millimeter wave radar 5 A millimeter-wave radar-equipped vehicle comprising: a zoom unit that receives information of at least a distance L from the image sensor and changes the imaging size 4a of the object 4 imaged by the image sensor 6 to a predetermined magnification m based on the information.