JP2002071788A - Radar device mounting method and radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar device mounting method capable of minimizing the amount of wraparound of radio waves due to peripheral elements. SOLUTION: As changing the relative angle between an plane array antenna for transmission and reception and a bumper 3, the control voltage of an AGC 16 is extracted from a monitor terminal 21 to monitor the amplification degree of an amplifier 15, and the relative angle is fixed when the amplification degree is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a radar device on a moving body such as an automobile, and more particularly, to an array antenna having a plurality of element antennas and a receiving method for receiving the signals by each element antenna. The present invention relates to a radar device mounting method for mounting a radar device equipped with an amplifier for amplifying a signal and an auto gain controller for controlling the amplification degree of the amplifier with a control voltage so that the output of the amplifier is constant, to a moving body. Further, the present invention relates to a radar device suitable for executing the mounting method.

[0002]

2. Description of the Related Art A radar device mounted on a vehicle is required to be mounted at a position that is not directly visible from the outside so as not to impair the appearance of the vehicle. Generally, it is often installed inside the front bumper.

[0003]

However, the space inside the bumper is narrow, and if the bumper is to be mounted in this narrow space, the antenna of the radar device and the rear surface of the bumper are necessarily arranged close to each other.

The bumper is usually made of a radio wave transmitting material such as resin, but when the antenna and the bumper are close to each other, for example, several centimeters or less, the radio wave output from the transmitting antenna is reflected by the bumper and goes around to the receiving antenna. I understood.

[0005] If this amount of wraparound is large, D
Since the C component increases, the amplification of the received signal amplifier is limited by the auto gain controller, and as a result, there is a problem that the detection power is reduced.

[0006]

SUMMARY OF THE INVENTION A method of mounting a radar apparatus according to the present invention has been made in order to solve such a problem, and has an array antenna having a plurality of element antennas and a reception signal received by each element antenna. An amplifier for amplifying the
In a radar device mounting method for mounting a radar device equipped with an auto gain controller that controls the amplification degree of the amplifier by a control voltage so that the output of the amplifier is constant, the radar device is finely adjusted to a predetermined position of the mobile object. It is determined that the amplification degree is the largest during execution of the first step of temporarily fixing as possible, the second step of changing the fixed position of the radar apparatus within a finely adjustable range while operating the radar apparatus, and the execution of the second step. And a third step of determining the fixed position of the radar device at the position at which the radar device is located.

[0007] According to the studies by the inventors, it has been found that the amount of radio waves output from the transmitting antenna reflected by a nearby object and circulated to the receiving antenna fluctuates greatly due to a slight change in the relative angle between the nearby object and the antenna. Was. In particular, it was found that the variation in the amount of radio wave wraparound was different for each element antenna.

[0008] Therefore, after the temporary fixing is performed in the first step so as to be finely adjusted, the fixed position of the radar device is changed in the second step to change the amount of the radio wave wrapping around the receiving antenna.

As described above, when the relative angle between the object fixed in the immediate vicinity of the radar device and the antenna of the radar device changes, the amount of radio wave wrapping around from the transmitting antenna to the receiving antenna by the object changes. If the amount of radio waves is large, the amplification of the amplifier is reduced by the function of the auto gain controller. Conversely, if the amount of radio waves is small, the amplification is large.

In the third step, the fixed position is determined at the position where the amplification degree is determined to be the largest, so that the radar device is fixed at the position where the amount of radio wave wraparound is the smallest. In particular, the radar device is fixed at a position where the difference between the wraparound amounts of the element antennas is small.

When the moving body is an automobile and the predetermined position where the radar device is temporarily fixed is inside the bumper, the electric wave wraps around due to the reflection at the bumper. According to the present invention, the amount of wrap around is reduced. The smallest.

In order for the auto gain controller to function effectively, it is desirable that the target exists at an appropriate position in the detection target area, for example, a position at a distance of about 10 m from the radar device. The target can be any target, but if a dummy target with an appropriate reflectance is placed, the gain adjustment by the auto gain controller will be effectively performed, so it is possible to clearly capture the change in amplification degree. it can.

The degree of amplification can be known from the control voltage of the auto gain controller.

The auto gain controller in the radar device according to the present invention has a control voltage monitor terminal for outputting a control voltage to the outside. Therefore, the amplification degree of the amplifier can be easily detected.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As one embodiment of a radar device mounting method of the present invention, a case where a radar device 1 is mounted inside a front bumper 3 of an automobile 2 as shown in FIG. 1 will be described.

FIG. 2 is a block diagram showing an internal configuration of the radar device 1, and FIG. 3 is an external view showing an attached state of the radar device 1 inside the front bumper 3.

The radar apparatus 1 is an FM-CW radar apparatus that uses a transmission signal obtained by multiplying a continuous wave (CW) by frequency modulation (FM), and uses a frequency of a beat signal which is a difference signal between the transmission signal and the reception signal. The distance and the relative speed of the target are detected based on the target.

The radar device 1 is also a DBF radar device that performs digital beam forming processing. That is, the radar device 2 includes, as a receiving antenna, a planar array antenna in which a plurality of element antennas are arranged in a plane, converts a received signal of each element antenna into a digital signal, and then performs a phase rotation on the digital received signal. The beam generation and beam scanning are performed by performing the processing and the synthesis processing.

The radar device 1 has three element antennas Rx
Receiving planar array antenna 10 having 1 to Rx3
And a transmitting antenna 11 arranged on the same plane as the planar array antenna 10, and the receiving planar array antenna 10 and the transmitting antenna 11 constitute a transmitting / receiving planar array antenna.

Each of the element antennas Rx1 to Rx3 is connected to one input terminal of a mixer 13 via a changeover switch 12. The changeover switch 12 performs connection switching between the element antennas Rx1 to Rx3 and the mixer 13 based on a switching signal from the outside.

A signal received by any of the element antennas Rx1 to Rx3 is mixed by the mixer 13 with a transmission signal from the oscillator 14. The received signal is down-converted by this mixing, and a beat signal which is a difference signal between the transmitted signal and the received signal is generated. The beat signal is input to an A / D converter 19 via an amplifier 15 and a low-pass filter 18 and is converted into a digital signal.

The digital signal processing section (DSP) 20
A digital beat signal from the A / D converter 19 is input, and a digital beat signal within a predetermined time is captured for each element antenna. Next, fast Fourier transform processing (FFT processing) is performed on the captured digital beat signal, and beam scanning is performed by DBF synthesis using the result of the Fourier transform. Finally, the distance and the relative speed of the target are calculated according to the search principle of the FM-CW radar device.

A detection circuit 17 and an automatic gain controller (AGC) 16 are added to the amplifier 15, and a feedback circuit is formed in which the amplification (gain) is automatically adjusted so that the output of the amplifier 15 becomes constant. Have been. That is, the amplification degree of the amplifier 15 can be adjusted by the control voltage of the AGC 16,
5 is small, the output level of the detection circuit 17 becomes low, and the AGC 16 detects this and outputs a control voltage that increases the amplification degree of the amplifier 15. Conversely, if the output amplitude of the amplifier 15 is large, the output level of the detection circuit 17 increases, and the AGC 16 outputs a control voltage that reduces the amplification of the amplifier 15.

The AGC 16 has a monitor terminal 21 so that the control voltage can be externally detected through the monitor terminal 21.

The bumper 3 is located close to the front of the planar array antenna 10 and the transmitting antenna 11. The bumper 3 is generally made of a resin, and transmits radio waves as a transmission signal and a reception signal of the radar device 1.
However, as in the present embodiment, the planar array antenna 10
If the distance between the transmitting antenna 11 and the bumper 3 is only about several centimeters, the radio wave (transmitting signal) emitted from the transmitting antenna 11 is reflected by the bumper 3 and goes around to the receiving antenna 10.

This wraparound radio wave (hereinafter, this radio wave is referred to as a carrier) becomes a DC component when it is mixed with the transmission signal from the oscillator 14 by the mixer 13. This is because the bumper 3 can be regarded as an object whose distance is substantially zero.

FIG. 4 shows the relationship between the frequency of the beat signal output by the mixer 13 and the output power when the radar device 1 is operated with a dummy target placed several meters ahead of the radar device 1. It is a graph.

The beat signal frequency corresponds to the target distance, and the frequencies f41 and f42 of the peaks 41 and 42
Indicates the distance to the dummy target. The peak 43 at the position where the frequency is zero, that is, the DC component is caused by the carrier. The power of the DC component greatly varies only by slightly shifting the relative angle between the planar array antenna 10 and the transmitting antenna 11 and the bumper 3.

According to the experiment of the inventor, when the front surface of the transmitting / receiving planar array antenna composed of the planar array antenna 10 and the transmitting antenna 11 and the back surface of the bumper 3 are parallel, the amount of carriers is the smallest. I understood. However, the back surface of the bumper 3 is often a gently curved surface, and the amount of carriers differs for each element antenna. In addition, the variation of the carrier when the relative angle between the transmitting / receiving planar array antenna and the bumper 3 is changed. The method also differs for each element antenna.

FIGS. 5A and 5B are graphs showing the output waveforms of the mixer 13 when the output waveform shown in FIG. 5A is obtained and when the output waveform shown in FIG. 5B is obtained. The relative angle between the transmitting / receiving planar array antenna and the bumper 3 is slightly different. In the figure, the horizontal axis is time, and the element antennas Rx1 to Rx3 are
Indicates that they can be sequentially switched. This switching is repeated continuously thereafter.

Transmission / reception plane array antenna and bumper 3
When the relative angle with respect to
It is assumed that the state changes from FIG. 5A to FIG. 5B. As can be seen from this figure, when the received signal of the element antenna Rx1 is used as a reference, the DC component of the received signal of the element antenna Rx2 is large, and the D component of the received signal of the element antenna Rx3 is large.
The C component is smaller. Although not shown in this figure, the DC component of the element antenna Rx1 as a reference has also changed, and FIG.
It is assumed that the DC component is larger than (a).

When comparing FIG. 5A and FIG. 5B,
Total amplitudes 51 and 52 of element antennas Rx1 to Rx3
Are different from each other. The whole amplitude 52 is larger than the whole amplitude 51, and the case of FIG.
The carrier amount is larger than in the case of (a).

As described above, when the relative angle between the transmitting / receiving planar array antenna and the bumper 3 is changed, the mixer 13
, The overall amplitude of the output signal (beat signal) changes, and at the same time, the magnitude of the DC component also changes. This signal is subsequently amplified by the amplifier 15, but the operation of the detection circuit 17 and the AGC 16 adjusts the amplification degree of the amplifier 15 so that the output becomes constant.

According to the example of FIG. 5, when the output of the mixer 13 changes from the state of FIG. 5A to the state of FIG.
That is, when the amplitude changes so as to increase the overall amplitude, the AGC 16 is controlled so that the amplification of the amplifier 15 decreases.
Control voltage changes. Conversely, when the output of the mixer 13 changes from the state shown in FIG. 5B to the state shown in FIG. 5A, that is, when the overall amplitude decreases, the amplification of the amplifier 15 increases. So that A
The control voltage of the GC 16 changes.

Therefore, while changing the relative angle between the transmitting / receiving planar array antenna and the bumper 3, the AGC 1
By taking out the control voltage of No. 6 from the monitor terminal 21 and monitoring the amplification degree of the amplifier 15 and fixing the relative angle when the amplification degree becomes the minimum, the influence of the carrier can be minimized.

FIG. 3 shows a state in which a radar device is mounted inside the bumper 3. The radar device 1 is fixed to a fixing plate 30, and the fixing plate 30 is fastened and fixed to a mounting structure (not shown) on the vehicle side by three bolts 61 to 63.

The fastening portion with the bolt 61 completely fixes the fixing plate 30 to the mounting structure. The fastening portion with the bolt 62 and the fastening portion with the bolt 63 connect the fixing plate 30 and the mounting structure with each other depending on the tightening angle of the bolt. The spacing can be fine-tuned. By rotating the bolt 62,
For example, the radar apparatus 1 can be rotated about the virtual axis 31 within an adjustment range of about 1 degree. Similarly, by rotating the bolt 63, the radar apparatus 1 can be rotated about the virtual axis 32 within an adjustment range of, for example, about once. Therefore, by rotating the bolts 62 and 63, the relative angle between the radar device 1 and the bumper 3 can be finely adjusted in two directions.

This fine adjustment is executed while the radar device 1 is operated by placing a dummy target in front of the radar device 1 mounted inside the bumper 3, and the amplification degree of the amplifier 15 is controlled based on the control voltage of the AGC 16. To monitor. When the amplification degree reaches the maximum within the adjustment range, if the tightening angles of the bolts 62 and 63 are fixed, the mounting that minimizes the carrier amount can be achieved.

In this embodiment, the relative angle between the radar device 1 and the bumper 3 is adjusted in a state where the dummy target is arranged so that the adjustment of the amplification degree by the AGC 16 is appropriately performed. It is not necessary to arrange the target. In that case, an arbitrary object existing in front of the radar device 1 is a target.

In this embodiment, the moving body to which the radar device is attached is an automobile, but is not limited to this. For example, the present invention can be applied to a motorcycle.

[0041]

As described above, according to the radar apparatus mounting method of the present invention, mounting that minimizes the amount of carriers can be performed by a new and simple method of observing the amplification degree of the amplifier mounted on the radar apparatus. it can.

[Brief description of the drawings]

FIG. 1 is an external view of an automobile using a radar device mounting method according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a radar device according to an embodiment of the present invention.

FIG. 3 is a plan view showing an attached state of a radar device according to one embodiment of the present invention.

FIG. 4 is a graph showing mixer output.

FIG. 5 is a waveform diagram of a reception signal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Radar apparatus, 2 ... Car, 3 ... Front bumper, 10
... Reception array antenna, 11 ... Transmission antenna, 12 ...
Changeover switch, 13: Mixer, 16: Amplifier, 16: A
GC, 21: Monitor terminal.

Claims (5)

[Claims] 1. An array antenna having a plurality of element antennas, an amplifier for amplifying a signal received by each of the element antennas, and an amplification degree of the amplifier controlled by a control voltage so that an output of the amplifier is constant. A radar device mounting method for mounting a radar device having an auto gain controller for controlling the radar device on a moving body, a first step of temporarily fixing the radar apparatus to a predetermined position of the moving body so as to be finely adjustable; and operating the radar apparatus. A second step of changing the fixed position of the radar apparatus within the finely adjustable range while fixing the radar apparatus at the position where the amplification degree is determined to be the largest during the execution of the second step. And a third step of determining a position. 2. The method according to claim 1, wherein the moving body is an automobile, and the predetermined position is inside a bumper of the automobile. 3. The radar device mounting method according to claim 1, wherein the second step is performed in a state where a dummy target is arranged in a detection target area of the radar device. 4. The radar according to claim 1, wherein the determination of the amplification degree in the third step is performed based on a control voltage applied to the amplifier by the auto gain controller. Device mounting method. 5. An array antenna having a plurality of element antennas, an amplifier for amplifying a received signal received by each of the element antennas, and an amplification degree of the amplifier controlled by a control voltage so that an output of the amplifier is constant. In a radar apparatus comprising: an auto gain controller for controlling; and a signal processing unit for processing an output signal of the amplifier to perform object recognition, wherein the auto gain controller has a control voltage monitor terminal for outputting the control voltage to the outside. A radar device characterized by the above-mentioned.