阅读说明：本技术 雷达装置以及具备该雷达装置的车辆 (Radar device and vehicle provided with same ) 是由 荒川畅哉 柏木克久 于 2020-03-13 设计创作，主要内容包括：本发明提供不变更天线罩的形状,就能够提高目标物的位置的检测精度,并且防止检测到虚假图像的雷达装置。对于在测定目标物的位置时由混频器电路(3)获得的测定时中间频率信号(IFγ),通过利用天线罩反射修正部(8)减去预先存储于修正用数据存储部(6)的差分(Diff.),来去除因发送波在天线罩(5)的内部反射而产生的反射波的检测量。并且,在天线罩反射修正部(8)进行该减法时,通过对有关减法值的相位进行由相移量计算部(7)计算出的相移量(e～(jΔθ))程度的修正,来矫正测定时中间频率信号(IFγ)的由装置温度引起的相移。距离/角度运算部(4)根据像这样进行了修正的测定时中间频率信号(IFγ),来运算目标物的位置。(The invention provides a radar device capable of improving the detection precision of the position of a target object and preventing false images from being detected without changing the shape of an antenna cover. A difference previously stored in a correction data storage unit (6) is subtracted from a measurement intermediate frequency signal (IF gamma) obtained by a mixer circuit (3) when the position of a target object is measured by a radome reflection correction unit (8)A detection amount of a reflected wave generated by reflection of the transmission wave inside the antenna cover (5) is removed by Diff. When the radome reflection correction unit (8) performs the subtraction, the phase shift amount (e) calculated by the phase shift amount calculation unit (7) is applied to the phase of the subtraction value jΔθ ) The correction of the degree corrects the phase shift of the intermediate frequency signal (IF gamma) caused by the temperature of the device at the time of measurement. The distance/angle calculation unit (4) calculates the position of the target object on the basis of the corrected measurement intermediate frequency signal (IF γ).)

1. A radar device is characterized by comprising:

a transmission signal generator that generates a transmission signal;

a transmission antenna for transmitting the transmission signal generated by the transmission signal generator as a transmission wave;

a receiving antenna for receiving a reflected wave reflected by the target object upon collision of the transmission wave;

a mixer circuit that mixes a transmission signal transmitted by the transmission antenna and a reception signal received by the reception antenna and converts the mixed signals into an intermediate frequency signal;

an antenna housing, a protection device;

a correction data storage unit which stores in advance a difference between an installation-time intermediate frequency signal obtained by a mixer circuit when the radome is installed in the apparatus and a non-installation-time intermediate frequency signal obtained by the mixer circuit when the radome is not installed in the apparatus;

a phase shift amount calculation unit that calculates a phase shift amount of the intermediate frequency signal obtained by the mixer circuit due to the device temperature; and

and a radome reflection correction unit which subtracts the difference stored in the correction data storage unit in advance from the measurement intermediate frequency signal obtained by the mixer circuit at the time of measuring the target object, and corrects the phase shift amount calculated by the phase shift amount calculation unit with respect to the phase of the subtraction value at the time of subtraction.

2. Radar apparatus according to claim 1,

the correction data storage unit stores in advance data of the mounting intermediate frequency signal obtained by the mixer circuit when the radome is mounted on the device together with the difference,

the phase shift amount calculation unit calculates the phase shift amount based on a phase difference at a predetermined frequency between the measurement-time intermediate frequency signal obtained by the mixer circuit when the target object is measured and the mounting-time intermediate frequency signal stored in advance in the correction data storage unit.

3. Radar apparatus according to claim 2,

the disclosed device is provided with: a signal path for branching a part of the transmission signal generated by the transmission signal generator to a reception signal line of the reception antenna, an attenuator provided in the signal path for attenuating the transmission signal branched to the signal path, and a delay device provided in the signal path for delaying the transmission signal branched to the signal path.

4. Radar apparatus according to claim 3,

the delay device has a function of adjusting a delay time of the transmission signal branched to the signal path.

5. Radar apparatus according to any one of claims 2 to 4,

the predetermined frequency is a frequency in a frequency band different from a frequency corresponding to a distance to the target object.

6. Radar apparatus according to claim 1,

the disclosed device is provided with: a temperature sensor for measuring the temperature of the device, and a table in which the phase shift amounts of the device at the respective temperatures are stored in advance,

the phase shift amount calculation unit calculates a phase shift amount stored in the table in association with the device temperature measured by the temperature sensor as the phase shift amount due to the device temperature of the intermediate frequency signal.

7. Radar apparatus according to any one of claims 1 to 6,

the antenna system further includes an arithmetic circuit for calculating a position of a target object based on the measurement-time intermediate frequency signal converted by the mixer circuit and corrected by the antenna-cover reflection correction unit.

8. Radar apparatus according to any one of claims 1 to 7,

the antenna cover is provided with a housing made of a material that reflects radio waves, and the housing covers the periphery of the device except for the emission direction of the transmission waves transmitted from the transmission antenna and the incidence direction of the reflection waves received by the reception antenna.

9. Radar apparatus according to claim 8,

the inner surface of the housing is provided with a radio wave absorber for absorbing radio waves.

10. A vehicle, characterized in that,

a radar apparatus according to any one of claims 1 to 9.

11. The vehicle of claim 10,

the radar device is provided in the rocker panel as the antenna cover, with the rocker panel forming a vehicle body below a door on a vehicle side surface.

Technical Field

The present invention relates to a radar device provided with an antenna cover for measuring a target object by receiving a reflected wave reflected by a target object upon which a transmitted wave collides, and a vehicle provided with the radar device.

Background

Conventionally, as such a radar device, for example, a device disclosed in patent document 1 is known.

The radar device includes a housing, an element unit, and a cover unit. The element unit has an antenna substrate having an array antenna for transmitting and receiving radio waves formed on one surface. The antenna substrate is housed in a case, and a cover is fixed to the front surface of the case. The cover portion is formed of a dielectric material that transmits radio waves transmitted and received by the element portion, and the center portion of the transmission portion is a flat surface portion having a planar shape parallel to the antenna surface. The range of the planar portion is set to a range overlapping with a range in which the brewster angle is enlarged with respect to the antenna center plane. The brewster angle is an incident angle at which the reflectance of a horizontally polarized wave at an interface between substances having different refractive indices becomes 0.

An incident angle of a radar wave radiated from the array antenna in the cover of the planar portion is not more than a Brewster angle. Therefore, the cover portion constituting the radome can suppress the reflectance of horizontally polarized waves of radar waves. Therefore, a decrease in the sensitivity of the radar device due to reflection of the horizontally polarized wave can be suppressed, and the detection accuracy can be improved. In addition, it is possible to prevent detection of a false image that does not actually exist due to reflection of a radar wave inside the hood.

Patent document 1: japanese patent laid-open publication No. 2018-179847

However, for example, when a part of a vehicle body such as a door handle or a rocker panel of a vehicle is used as a radome as in an on-vehicle radar, since the vehicle body shape of the vehicle cannot be freely changed, it is not possible to suppress reflection of a radar wave inside the radome by designing the shape of the radome as in the conventional radar device disclosed in patent document 1. Therefore, in a radar device in which the shape of the antenna cover cannot be changed, it is difficult to improve the detection accuracy of the target object or to prevent detection of a false image while suppressing a decrease in the sensitivity of the radar device as in the conventional radar device disclosed in patent document 1.

Disclosure of Invention

The present invention has been made to solve the above problems, and provides a radar apparatus including: a transmission signal generator that generates a transmission signal; a transmission antenna for transmitting the transmission signal generated by the transmission signal generator as a transmission wave; a receiving antenna for receiving a reflected wave reflected by the target object upon collision of the transmission wave; a mixer circuit that mixes a transmission signal transmitted by the transmission antenna and a reception signal received by the reception antenna and converts the mixed signals into an intermediate frequency signal; an antenna housing, a protection device; a correction data storage unit that stores in advance a difference between an installation-time intermediate frequency signal obtained by the mixer circuit when the radome is installed in the apparatus and a non-installation-time intermediate frequency signal obtained by the mixer circuit when the radome is not installed in the apparatus; a phase shift amount calculation unit that calculates a phase shift amount of the intermediate frequency signal obtained by the mixer circuit due to the device temperature; and a radome reflection correction unit which subtracts the difference stored in the correction data storage unit in advance from the measurement intermediate frequency signal obtained by the mixer circuit when the target object is measured, and corrects the phase of the subtraction value by the phase shift amount calculated by the phase shift amount calculation unit during the subtraction.

According to this configuration, the radome reflection correction unit subtracts the difference previously stored in the correction data storage unit from the intermediate frequency signal for measurement obtained by the mixer circuit at the time of measuring the target object, thereby removing the detection amount of the reflected wave generated by the reflection of the transmission wave inside the radome. When the radome reflection correction unit performs the subtraction, the phase shift amount calculation unit corrects the phase of the subtracted value by the degree of the phase shift amount calculated by the phase shift amount calculation unit, thereby correcting the phase shift of the intermediate frequency signal caused by the device temperature at the time of measurement. Therefore, without changing the shape of the radome, the influence of the reflection component of the radar wave inside the radome can be removed with high accuracy, the detection accuracy of the target object can be improved, and the detection of false images can be prevented.

In addition, the present invention constitutes a vehicle including the radar device described above.

According to the present invention, it is possible to provide a radar device capable of preventing detection of a false image while improving detection accuracy of a target object without changing the shape of an antenna cover, and a vehicle including the radar device.

Drawings

Fig. 1 is a block diagram showing a schematic configuration of a radar apparatus according to a first embodiment of the present invention.

Fig. 2 is a diagram conceptually illustrating a method of solving correction data in the radar device according to the first embodiment.

Fig. 3 is a diagram conceptually illustrating a method of solving the phase shift amount in the radar device of the first embodiment.

Fig. 4 is a diagram conceptually illustrating a method of correcting a measurement-time intermediate frequency signal in the radar device according to the first embodiment.

Fig. 5 is a graph showing a comparison between the intermediate frequency signal at the time of measurement corrected by the radome reflection correction unit constituting the radar device of the first embodiment and the intermediate frequency signal at the time of measurement not corrected, and the intermediate frequency signal at the time of non-attachment of the radome.

Fig. 6 is a block diagram showing a schematic configuration of a radar device according to a second embodiment of the present invention.

Fig. 7 is a block diagram showing a schematic configuration of a radar device according to a third embodiment of the present invention.

Fig. 8 is a schematic configuration diagram of a vehicle according to an embodiment of the present invention.

Fig. 9 is a front view of a rocker panel to which a radar device of a fourth embodiment of the invention is mounted.

Fig. 10 (a) is a cross-sectional view of a radar device according to a fourth embodiment, and (b) is a perspective view of a housing shown in (a).

Fig. 11 (a) is a cross-sectional view showing a reflection state of a transmission wave by the inner surface of the antenna cover in the radar device according to the fourth embodiment, and (b) is a cross-sectional view showing a reflection state of a transmission wave by the inner surface of the antenna cover in the radar device not covered with the housing.

Fig. 12 is a cross-sectional view of a radar device according to a first modification of the fourth embodiment, in which a radio wave absorber is provided on an inner surface of a housing.

Fig. 13 (a) is a cross-sectional view of a radar device according to a second modification of the fourth embodiment in which the periphery of the device is covered with a housing having a rectangular parallelepiped shape with five sides, and (b) is a perspective view of the housing shown in (a).

Fig. 14 (a) is a cross-sectional view of a radar device according to a third modification of the fourth embodiment in which the periphery of the device is covered with a dome-shaped case, and (b) is a perspective view of the case shown in (a).

Detailed Description

Next, a mode for implementing the radar apparatus of the present invention will be explained.

Fig. 1 is a block diagram showing a schematic configuration of a radar apparatus 1A according to a first embodiment of the present invention.

The radar device 1A includes an RF (Radio Frequency) signal generator 2, a transmission antenna Tx, reception antennas Rx1, Rx2, Rx3, and Rx4 (hereinafter, collectively referred to as Rx), a mixer circuit 3, a distance/angle calculation unit 4, and an antenna cover 5 that covers and protects the radar device 1A. In the present embodiment, a case where one transmission antenna Tx and four reception antennas Rx are used will be described, but the number of them is not limited to this. For example, the number of transmission antennas Tx may be four, and the number of reception antennas Rx may be twelve.

The RF signal generator 2 is a transmission signal generator that generates a transmission signal s, and is constituted by a voltage-controlled oscillator or the like. The transmission antenna Tx converts the transmission signal s generated by the RF signal generator 2 into a transmission wave such as a millimeter wave, and transmits the transmission wave to an object not shown. The transmission signal s is transmitted within the circuit, and the transmission wave propagates in space. The reception antennas Rx1, Rx2, Rx3, Rx4 receive reflected waves reflected by the object upon which the transmission waves collide. Each mixer circuit 3 mixes a transmission signal s transmitted from a transmission antenna Tx and reception signals r1, r2, r3, and r4 (hereinafter collectively referred to as "r") received from reception antennas Rx1, Rx2, Rx3, and Rx4, and converts the signals into intermediate frequency signals IF1, IF2, IF3, and IF4 (hereinafter collectively referred to as "IF"). Specifically, each mixer circuit 3 multiplies the transmission signal wave voltage Vtx of the transmission signal s by the reception signal wave voltage Vrx of each reception signal r1, r2, r3, r4, and converts the transmission signal s into intermediate frequency signals IF1, IF2, IF3, IF4 for each of the reception signals r1, r2, r3, r4 received by each reception antenna Rx1, Rx2, Rx3, Rx 4.

The distance/angle calculator 4 constitutes a calculation circuit for calculating the position of the target object based on the intermediate frequency signals IF1, IF2, IF3, and IF4 converted by the mixer circuit 3. In the present embodiment, the distance/angle calculation unit 4 calculates the distance R to the target object from the frequencies f of the intermediate frequency signals IF1, IF2, IF3, and IF4, and calculates the azimuth angle of the target object from the phase difference between the intermediate frequency signals IF1, IF2, IF3, and IF 4. In the present embodiment, a case will be described in which the distance R to the target object and the azimuth angle θ of the target object are calculated as the two-dimensional position of the target object. However, the transmission antennas Tx may be arranged in a two-dimensional array or the like, and the elevation angle of the target object may be further determinedTo calculate the three-dimensional position of the target object.

In the present embodiment, the radar device 1A includes a correction data storage unit 6, a phase shift amount calculation unit 7, and a radome reflection correction unit 8 between the mixer circuit 3 and the distance/angle calculation unit 4. The correction data storage unit 6 stores in advance a difference diff between mounting intermediate frequency signals IF1, IF2, IF3, IF4 (hereinafter, referred to as IF α) obtained by the mixer circuit 3 when the antenna cover 5 is mounted to the radar device 1A and non-mounting intermediate frequency signals IF1, IF2, IF3, IF4 (hereinafter, referred to as IF β) obtained by the mixer circuit 3 when the antenna cover 5 is not mounted to the radar device 1A. That is, when the antenna cover 5 is attached and when the antenna cover 5 is not attached, a transmission wave is transmitted from the transmission antenna Tx under the same environment, a reception signal of a transmission wave component leaking from the transmission system to the reception system is mixed with the transmission signal s output from the RF signal generator 2 in the mixer circuit 3, the attachment intermediate frequency signal IF α and the non-attachment intermediate frequency signal IF β are measured in advance, and the difference diff between them is stored as correction data in the correction data storage unit 6.

Fig. 2 is a diagram conceptually illustrating a method of solving the correction data. Graph a shown in the figure shows the intermediate frequency signal IF α at the time of mounting measured for any of the reception antennas Rx1, Rx2, Rx3, and Rx4, and graph B shows the intermediate frequency signal IF β at the time of non-mounting measured for any of the reception antennas Rx1, Rx2, Rx3, and Rx 4. The horizontal axis of each graph represents a distance R [ m ] corresponding to the frequency f of the intermediate frequency signal IF, and the vertical axis represents the signal intensity Power [ dB ] of the intermediate frequency signal IF. The intermediate frequency signal IF is represented by a complex number, and only the signal intensity thereof is shown in each graph, but the phase thereof is also measured at the same time.

Since the transmission wave component leaks from the transmission system to the reception system in the radar apparatus 1A, the signal intensity of the near-range intermediate frequency signal IF increases in each graph A, B. In addition, in the mounting intermediate frequency signal If α of the graph a, the signal intensity at a short distance is improved by about 20[ dB ] as compared with the non-mounting intermediate frequency signal If β of the graph B. This is because the components of the transmission wave transmitted from the transmission antenna Tx and reflected by the antenna cover 5 are received by the reception antenna Rx. When the position of the target object is measured by the radar device 1A, the reflection component becomes an important factor for causing a false image to appear. In the present embodiment, the difference diff is calculated by subtracting the non-mounting intermediate frequency signal IF from the mounting intermediate frequency signal IF α, thereby obtaining the reflection component that is an important factor of the dummy image, and storing the reflection component as correction data in the correction data storage unit 6. In the present embodiment, the data of the intermediate frequency signal IF α at the time of mounting shown in the graph a is stored in advance in the correction data storage unit 6 together with the difference diff. Data of these difference diff and the intermediate frequency signal IF α at the time of mounting are measured for each of the reception antennas Rx1, Rx2, Rx3, and Rx4, and stored in advance in the correction data storage unit 6 for each of the reception antennas Rx1, Rx2, Rx3, and Rx 4.

When the difference diff stored in advance in the correction data storage unit 6 is acquired, and when the position of the target object is actually measured by the radar device 1A, there may be a difference in temperature of the radar device 1A. IF the temperature of the radar device 1A varies, the phase of the intermediate frequency signal IF obtained by the mixer circuit 3 shifts. The phase shift amount calculation unit 7 calculates the amount of phase shift of the intermediate frequency signal IF obtained by the mixer circuit 3 due to the device temperature. In the present embodiment, the phase shift amount calculation unit 7 calculates the amount of phase shift based on the phase difference at a predetermined frequency between the measurement intermediate frequency signal (hereinafter, referred to as IF γ) obtained by the mixer circuit 3 when the position of the target object is measured and the mounting intermediate frequency signal IF α stored in advance in the correction data storage unit 6.

Fig. 3 is a diagram for applying FFT (Fast Fourier Transform) to the intermediate frequency signal IF, and conceptually illustrates a method for solving the phase shift amount. The graph C shown in the figure shows the intermediate frequency signal IF γ at the time of measurement measured for each of the reception antennas Rx1, Rx2, Rx3, and Rx4, and the graph D shows the intermediate frequency signal IF α at the time of mounting measured and stored in advance for each of the reception antennas Rx1, Rx2, Rx3, and Rx 4. The horizontal axis and the vertical axis of each of these graphs are the same as those of the graph shown in fig. 2. The measurement line indicated by the solid line is the measurement result obtained for the reception antenna Rx1, the measurement line indicated by the short dashed line is the measurement result obtained for the reception antenna Rx2, the measurement line indicated by the one-dot chain line is the measurement result obtained for the reception antenna Rx3, and the measurement line indicated by the long dashed line is the measurement result obtained for the reception antenna Rx 4. Here, the intermediate frequency signal IF is also represented by a complex number, and only the signal intensity thereof is shown in each graph, but the phase thereof is also measured at the same time.

In the present embodiment, the predetermined frequency for calculating the phase shift amount of the two signals, i.e., the measurement-time intermediate frequency signal IF γ of the graph C and the installation-time intermediate frequency signal IF α of the graph D, is set to a frequency f of a frequency band different from the frequency f corresponding to the distance R to the target. Here, the frequency f corresponding to a short distance where no target exists, that is, the frequency f of the transmission wave component leaking from the transmission system to the reception system is set. The frequency f corresponds to a bin at a distance Rc shown by a broken line in each of the graphs C and D shown in fig. 3, and the bin will be described as a reference bin hereinafter. The frequency spectrum of the intermediate frequency signal IF after FFT has a shape in which long bars having widths are arranged at equal intervals, and the bin (bin) here refers to the long bar. The phase shift amount calculating section 7 calculates a difference between the phase of the measurement intermediate frequency signal IF γ and the phase of the mounting intermediate frequency signal IF α in the reference bin as a phase shift amount e^jΔθ. Here, e^jΔθIs an exponential function with e as the base.

In the present embodiment, the phase shift amount calculation unit 7 calculates a difference between the phase of the average value of the measurement intermediate frequency signal IF γ and the phase of the average value of the installation intermediate frequency signal IF α in the reference bin as the phase shift amount e^jΔθ. However, the phase difference between the phase of the intermediate frequency signal IF γ at the time of measurement in the reference bin and the phase of the intermediate frequency signal IF α at the time of installation may be calculated independently for each of the receiving antennas Rx1, Rx2, Rx3, and Rx4, and the phase shift amount e may be obtained independently for each of the receiving antennas Rx1, Rx2, Rx3, and Rx4^jΔθ。

The radome reflection correction unit 8 receives the difference diff from the correction data storage unit 6 and the phase shift amount e from the phase shift amount calculation unit 7^jΔθ. Then, the difference diff stored in advance in the correction data storage unit 6 is subtracted from the measurement intermediate frequency signal IF γ, and the phase of the subtraction value is calculated by the phase shift amount calculation unit 7 at the time of the subtractionAmount of phase shift e^jΔθAnd (5) correcting the degree.

Fig. 4 is a diagram conceptually illustrating this correction method by the radome reflection correction unit 8. Graph E shown in the figure is a measurement-time intermediate frequency signal IF γ measured for any one of the reception antennas Rx1, Rx2, Rx3, and Rx4, and the horizontal axis and the vertical axis of the graph are the same as those of the graph shown in fig. 2. In the present embodiment, the radome reflection correction unit 8 first integrates the phase shift amount e with respect to the measurement-time intermediate frequency signal IF γ^jΔθThe phase of the intermediate frequency signal IF gamma at the time of measurement is corrected. Then, the difference diff input from the correction data storage unit 6 is subtracted from the integrated value. This subtraction value is a corrected measurement-time intermediate frequency signal IF γ from which the influence of the reflection component of the transmission wave inside the antenna cover 5 is removed. The calculation performed by the radome reflection correction unit 8 is performed for each of the reception antennas Rx1, Rx2, Rx3, and Rx4, and the difference diff, which is stored in the correction data storage unit 6 in advance for each of the reception antennas Rx1, Rx2, Rx3, and Rx4, is subtracted from the phase correction value of the measurement intermediate frequency signal IF γ obtained for each of the antennas Rx1, Rx2, Rx3, and Rx 4.

In the present embodiment, the difference diff is subtracted after the phase of the intermediate frequency signal IF γ is corrected at the time of measurement. However, the difference Diff may be accumulated by a phase shift amount e of which sign is inverted^－jΔθThe phase of the difference Diff is corrected, and the phase-corrected difference Diff is subtracted from the intermediate frequency signal IF gamma at the time of measurement.

Fig. 5 is a graph showing the measurement intermediate frequency signal IF γ subjected to such correction and the measurement intermediate frequency signal IF γ not subjected to such correction, by comparing them with the non-attachment intermediate frequency signal IF β of the antenna cover 5. The horizontal axis and the vertical axis of the graph are the same as those of the graph shown in fig. 2. The measurement line 21 shown by a short broken line indicates an ideal non-installation intermediate frequency signal IF β obtained when the radome 5 is not installed in the radar apparatus 1A, which is completely free from the influence of the reflection component of the radome 5. The measurement line 22 shown by a solid line represents the intermediate frequency signal IF γ at the time of measurement obtained by performing the above correction when the antenna cover 5 is attached. The measurement line 23 indicated by a long broken line indicates the intermediate frequency signal IF γ at the time of measurement obtained without the above-described correction when the antenna cover 5 is attached.

As can be seen from this graph, the intermediate frequency signal IF γ at the time of measurement shown in the measurement line 22 obtained by correction at a short distance has substantially the same measurement result as the intermediate frequency signal IF β at the time of non-mounting as compared with the intermediate frequency signal IF γ at the time of measurement shown in the measurement line 23 obtained without correction. Thus, the phase shift e of the intermediate frequency signal IF gamma during measurement is confirmed^jΔθThe difference diff is subtracted from the phase-corrected measurement intermediate frequency signal IF γ by correcting the degree, thereby greatly reducing the reflection component of the transmission wave inside the antenna cover 5.

The distance/angle calculation unit 4 receives the measurement intermediate frequency signal IF γ from the radome reflection correction unit 8, from which the influence of the radome 5 is removed, and calculates the position of the target object, in the present embodiment, the distance R to the target object and the azimuth angle of the target object, based on the received measurement intermediate frequency signal IF γ.

According to the radar device 1A of the present embodiment, as shown in fig. 4, the radome reflection correction unit 8 subtracts the difference diff previously stored in the correction data storage unit 6 from the measurement intermediate frequency signal IF γ obtained by the mixer circuit 3 when the position of the target object is measured, thereby removing the amount of detection of the reflected wave generated by the reflection of the transmission wave inside the radome 5. When the radome reflection correction unit 8 performs the subtraction, the phase shift amount e calculated by the phase shift amount calculation unit 7 is corrected by the phase of the subtraction value^jΔθThe phase shift of the intermediate frequency signal IF gamma at the time of measurement caused by the device temperature is corrected. The distance/angle calculation unit 4 calculates the position of the target object based on the measurement intermediate frequency signal IF γ corrected in this manner.

Therefore, according to the radar device 1A of the present embodiment, since the measurement data itself obtained by the mixer circuit 3 is directly subjected to the correction for removing the influence of the antenna cover 5 without correcting the position calculation data of the target object, the correction for removing the influence of the antenna cover 5 can be performed with high accuracy. Therefore, without changing the shape of the antenna cover 5, it is possible to remove the influence of the reflection component of the radar wave inside the antenna cover 5 with high accuracy, improve the detection accuracy of the position of the target object calculated by the distance/angle calculation unit 4, and prevent the detection of false images.

In addition, according to the radar device 1A of the present embodiment, as shown in fig. 3, the phase shift amount e of the intermediate frequency signal IF obtained by the mixer circuit 3 due to the device temperature can be easily calculated by the phase shift amount calculating unit 7 from the phase difference between the two signals of the intermediate frequency signal IF γ at the time of measurement and the intermediate frequency signal IF α at the time of mounting^jΔθ。

In addition, according to the radar device 1A of the present embodiment, the phase shift amount e is calculated^jΔθThe frequency f in the reference bin(s) is different from the frequency band of the frequency f corresponding to the distance R to the target object, so that the amount of phase shift e by the phase shift amount calculation unit 7 can be eliminated^jΔθThe distance/angle calculation unit 4 calculates the position of the calculation target object, with influence of the calculation of (2). Therefore, the accuracy of the calculation of the position of the target object by the distance/angle calculation unit 4 can be ensured.

Next, a radar device according to a second embodiment of the present invention will be described. Fig. 6 is a block diagram showing a schematic configuration of a radar device 1B according to the second embodiment. In this figure, the same or corresponding portions as those in fig. 1 are denoted by the same reference numerals, and the description thereof is omitted.

The radar device 1B of the second embodiment is different from the radar device 1A of the first embodiment described above only in that it includes a signal path p for branching a part of the transmission signal s generated by the RF signal generator 2 to the reception signal lines of the reception antennas Rx1, Rx2, Rx3, and Rx4, and the attenuator 31 and the delay device 32 provided in each signal path p. The other structure is the same as that of the radar device 1A of the first embodiment described above. The attenuator 31 attenuates the transmission signal s branched to the signal path p, and reduces the signal intensity of the transmission signal s which is excessively large. The delay device 32 delays the transmission signal s branched to the signal path p by a predetermined time.

According to the radar device 1B of the second embodiment, a part of the transmission signal s is dividedThe reception signal lines flow to the respective reception antennas Rx1, Rx2, Rx3, and Rx 4. The signal strength is reduced by the attenuator 31, delayed for a predetermined time by the delay device 32, and input to the mixer circuit 3. Therefore, the mixer circuit 3 mixes the transmission signal s transmitted from the transmission antenna Tx with a part of the transmission signal s attenuated and delayed by the reception signal line branched to the reception antenna Rx, and generates an intermediate frequency signal IF η for calculating the phase shift amount. The phase shift amount calculating unit 7 calculates the amount of phase shift e of the intermediate frequency signal IF obtained by the mixer circuit 3 due to the device temperature, based on the phase difference between the intermediate frequency signal IF η for calculating the amount of phase shift and the reference bin of the two signals stored in advance in the correction data storage unit 6, i.e., the intermediate frequency signal IF α at the time of mounting^jΔθ。

Therefore, according to the radar device 1B of the second embodiment, the same operational effect as that of the radar device 1A of the first embodiment is obtained, such that the intermediate frequency signal IF obtained by the mixer circuit 3 can be corrected with high accuracy so as to remove the influence of the radome 5, and the phase shift amount e of the intermediate frequency signal IF due to the device temperature can be reliably calculated from the intermediate frequency signal IF η for phase shift amount calculation and the intermediate frequency signal IF α at the time of mounting without being affected by the signal state of the intermediate frequency signal IF γ at the time of measuring the position of the target object at the time of measuring the intermediate frequency signal IF γ obtained by the mixer circuit 3^jΔθ. Therefore, even IF the intermediate frequency signal IF γ at the time of measurement is a signal obtained when the signal level of the transmission wave component leaking from the transmission system to the reception system is extremely low, when the leaked transmission wave component cannot be detected, or the like, the phase shift amount e of the intermediate frequency signal IF due to the device temperature can be reliably calculated^jΔθ. Thereby, the phase shift e can be always adjusted according to the phase shift amount^jΔθThe phase of the intermediate frequency signal IF γ at the time of measurement is appropriately corrected, and the position of the target object can be accurately calculated by the distance/angle calculation unit 4 at all times.

In the above-described embodiment, the delay device 32 may have a function of adjusting the delay time of the transmission signal s branched to the signal path p. According to this configuration, the delay time of the transmission signal s branched to the signal path p can be set to an arbitrary time by the delay time adjustment function of the delay device 32. Therefore, the input time of the transmission signal s branched to the signal path p to the mixer circuit 3, which is analog signal processing of the reception signal r, can be set to an arbitrary time.

Therefore, the calculated phase shift amount e of the two signals, the intermediate frequency signal IF η for phase shift amount calculation and the intermediate frequency signal IF α at the time of installation, can be obtained^jΔθThe frequency f of the reference bin of (2) is set to an arbitrary frequency fc. Thus, the phase shift e can be calculated^jΔθIs set to be able to easily realize the phase shift amount e^jΔθThe calculated frequency fc. For example, at a distance of 5[ m ] to the target]Can be in the range of 6[ m ]]Sets a reference bin to calculate the phase shift e^jΔθ。

Next, a radar device according to a third embodiment of the present invention will be described. Fig. 7 is a block diagram showing a schematic configuration of a radar device 1C according to the third embodiment. In this figure, the same or corresponding portions as those in fig. 1 are denoted by the same reference numerals, and the description thereof is omitted.

The radar device 1C according to the third embodiment includes only the temperature sensor 41 and the table 42 indicating the relationship between the device temperature and the phase change, the outputs of the mixer circuits 3 are directly supplied to the radome reflection correction unit 8 without passing through the phase shift amount calculation unit 7, and the phase shift amount calculation unit 7 calculates the phase shift amount e from the outputs of the temperature sensor 41 and the table 42^jΔθThe point of (1) is different from the radar device 1A of the first embodiment. The other structure is the same as that of the radar device 1A of the first embodiment described above. The temperature sensor 41 measures the temperature of the radar device 1C. The table 42 stores in advance the phase shift amount e of the radar device 1C at each temperature^jΔθAs a list. The phase shift amount calculation unit 7 stores the phase shift amount e in the table 42 in association with the device temperature measured by the temperature sensor 41^jΔθPhase shift e caused by device temperature as intermediate frequency signal IF^jΔθAnd outputs the result to the radome reflection correction unit 8.

According to the third embodimentThe radar device 1C can be based on the phase shift e stored in the table 42 corresponding to the device temperature measured by the temperature sensor 41^jΔθThe phase shift amount e of the intermediate frequency signal IF obtained by the mixer circuit 3 due to the device temperature is easily calculated by the phase shift amount calculating section 7^jΔθ. And, based on the calculated phase shift e^jΔθThe correction of the measurement-time intermediate frequency signal IF γ has the same operational effects as those of the radar device 1A according to the first embodiment.

In the above-described embodiment, the phase shift amount e of the radar device 1C at each temperature is stored in the radar device 1C^jΔθThe case of table 42 (a) is explained. However, the phase shift amount e of the radar device 1C at each temperature may be stored in a personal computer, a microcomputer, or the like outside the radar device 1C^jΔθ。

The radar devices 1A, 1B, and 1C of the present invention are preferably used for an on-vehicle radar or the like that detects a target object at a relatively short distance. Fig. 8 shows a schematic structure of a vehicle 51 according to an embodiment of the present invention. The radar devices 1A, 1B, and 1C have a rocker panel 51B, which forms a vehicle body below a door 51A on a vehicle side, as an antenna cover 5, and are provided inside the rocker panel 51B. By providing the radar devices 1A, 1B, and 1C in the vehicle 51 in this manner, it is possible to detect an obstacle around the vehicle, for example, a curb 52 or the like, when the door 51A is opened and closed by the radar devices 1A, 1B, and 1C, and it is possible to prevent the door 51A from colliding with the obstacle such as the curb 52 or the like and damaging the door 51A.

Next, a radar device according to a fourth embodiment of the present invention will be described. Fig. 9 is a front view of the rocker panel 51b as viewed from the side of the vehicle 51 when the radar device 1D of the fourth embodiment is mounted in the rocker panel 51 b. Fig. 10 (a) is a cross-sectional view of the radar device 1D when the rocker panel 51b shown in fig. 9 is attached to the vehicle 51.

When the rocker panel 51b is attached to the vehicle 51, the rear surface of the rocker panel 51b is covered with a metal plate 51c of the vehicle body portion of the vehicle 51 as shown in fig. 10 (a). The rocker panel 51b is formed of a material that transmits radio waves such as resin, and the radar device 1D having the rocker panel 51b as the antenna cover 5 is configured to be covered by the housing 9 inside the antenna cover 5. The internal structure of the radar device 1D is the same as that of any of the radar devices 1A, 1B, and 1C of the above embodiments.

As shown in the external perspective view of fig. 10 (b), the housing 9 has a rectangular parallelepiped shape having four surfaces without a top plate and a front plate, and is made of a material that reflects radio waves, for example, a metal such as copper, aluminum, or iron, or a resin containing metal particles. As shown in fig. 10 (a), the roof of the rocker panel 51b constitutes the roof of the housing 9 that faces upward of the vehicle 51. The front panel of the housing 9 facing the outside of the side surface of the vehicle 51 is positioned in the emission direction of the transmission wave transmitted from the transmission antenna Tx and the incidence direction of the reflected wave received by the reception antenna Rx, and blocks the emission of the radio wave from the housing 9 and the incidence of the radio wave into the housing 9, and therefore is removed from the housing 9. The casing 9 covers the periphery of the radar device 1D except for the emission direction of the transmission wave transmitted from the transmission antenna Tx and the incidence direction of the reflected wave received by the reception antenna Rx in this manner. The size of the housing 9 and the distance between the housing 9 and the radar device 1D may be arbitrary.

Fig. 11 (a) shows a reflection state of a part of the radio wave g reflected by the inner surface of the antenna cover 5 when the radio wave emitted from the transmission antenna Tx hits the transmission antenna in the radar device 1D according to the fourth embodiment including the housing 9. Fig. 11 (b) shows a reflection state of a part of the radio wave g reflected by the inner surface of the antenna cover 5 when colliding with the transmission wave emitted from the transmission antenna Tx in the radar device 1D without the housing 9. In fig. 11, the same portions as those in fig. 10 are denoted by the same reference numerals, and the description thereof is omitted.

In the radar device 1D according to the fourth embodiment shown in fig. 11 (a), a part of the radio wave g of the transmission wave emitted from the transmission antenna Tx that collides with the inner surface of the antenna cover 5 and is reflected is confined in the housing 9. However, in the radar device 1D shown in fig. 11 (b) which does not include the housing 9, a part of the radio wave g of the transmission wave emitted from the transmission antenna Tx which is reflected by the inner surface of the antenna cover 5 is transmitted through the antenna cover 5 and is blown out of the antenna cover 5 to collide with the road surface 10 as shown in the drawing. A part of the radio wave g that has collided with the road surface 10 returns to the radar device 1D along the same optical path, and is received by the receiving antenna Rx in the radar device 1D.

As described above, the radome reflection correction unit 8 removes the amount of detection of the reflected wave generated by the reflection of the transmission wave emitted from the transmission antenna Tx inside the radome 5 at the time of measuring the position of the target object by subtracting the difference diff stored in the correction data storage unit 6 in advance from the measurement intermediate frequency signal IF γ. The difference diff is calculated in advance by subtracting the non-mounting intermediate frequency signal IF β of the antenna cover 5 from the mounting intermediate frequency signal IF α of the antenna cover 5, and is stored as correction data in the correction data storage unit 6. However, the environment of the radar device 1D when calculating the correction data differs from the environment when actually measuring the position of the target object, and for example, as shown in fig. 11 (b), in an environment where a part of the radio wave g reflected from the road surface 10 is received by the receiving antenna Rx, the assumed value of the intermediate frequency signal IF α at the time of installation changes under the influence of the part of the radio wave g received by the receiving antenna Rx, and the value of the difference diff is different from the value assumed in advance and stored in the correction data storage unit 6.

On the other hand, in the radar device 1D of the fourth embodiment, as shown in fig. 11 (a), the periphery of the radar device 1D is covered by the housing 9, and a part of the radio wave g of the transmission wave emitted from the transmission antenna Tx which hits the inner surface of the antenna cover 5 and is reflected is confined within the housing 9. Therefore, the environment of the radar device 1D when actually measuring the position of the target object is not affected by the radio wave g reflected from the road surface 10 at the receiving antenna Rx as shown in fig. 11 (b), and can be maintained to be the same as the environment of the radar device 1D when calculating the correction data. Therefore, the radome reflection correction unit 8 can accurately remove the detection amount of the reflected wave generated by the reflection of the transmission wave inside the radome 5 at the time of measuring the position of the target object by subtracting the difference diff stored in the correction data storage unit 6 in advance from the measurement intermediate frequency signal IF γ. Therefore, according to the radar device 1D of the fourth embodiment, the position of the target object can be accurately measured.

As shown in a cross-sectional view of fig. 12, the radar device 1D according to the fourth embodiment may be configured to include a radio wave absorber 11 that absorbs radio waves on an inner surface 9a (see fig. 10 b) of the housing 9. The radio wave absorber 11 is formed in a sheet shape, a pyramid shape, a hair shape, or the like, for example, and the shape, material, and the like may be selected so as to absorb radio waves. In fig. 12, the same portions as those in fig. 10 are denoted by the same reference numerals, and the description thereof is omitted.

By providing the radio wave absorber 11 on the inner surface 9a of the housing 9, the intensity of the radio wave g confined in the housing 9 is attenuated as shown in fig. 11 (a). If the intensity of the radio wave g confined in the housing 9 is strong, the difference diff between the installation-time intermediate frequency If α and the non-installation-time intermediate frequency signal If β increases, and If there is an error in the phase shift amount Δ θ estimated from the reference bin, the component that cannot be removed by the subtraction shown in fig. 4 increases, and the corrected data also includes a large error. However, if the intensity of the radio wave g confined in the case 9 is attenuated by the radio wave absorber 11, the difference diff is reduced, and the influence on the corrected data is reduced even if the phase shift amount Δ θ includes an error.

Further, if the intensity of the radio wave g confined in the case 9 is large, the signal input to the electronic components constituting the receiving system of the radar device 1D is large and saturated, but if the intensity of the radio wave g is attenuated by the radio wave absorber 11, such a saturation problem does not occur. Therefore, by providing the radio wave absorber 11 on the inner surface 9a of the housing 9, it is possible to reduce errors included in the value of the corrected data, and to accurately measure the mounting-time intermediate frequency signal IF α in the receiving system of the radar device 1D, thereby improving the measurement accuracy of the position of the target object obtained by subtracting the difference diff from the measurement-time intermediate frequency signal IF γ.

In the radar device 1D of the fourth embodiment, even if the radio wave g escapes from the housing 9 to above the rocker panel 51b, that is, above the vehicle 51, there is no reflection object such as the road surface 10 above the vehicle 51, and therefore, there is no roof panel of the housing 9. However, as shown in a cross-sectional view of the radar device 1D shown in fig. 13 (a) and a perspective view of the housing 9A shown in fig. 13 (b), the housing 9A preferably includes a top plate and the housing 9A preferably has five-sided side surfaces. In fig. 13, the same portions as those in fig. 10 are denoted by the same reference numerals, and the description thereof is omitted. According to the housing 9A, even when a reflecting object is present above the housing 9A, the corrected data can be calculated without being affected by the radio wave g reflected from the reflecting object, and the position of the target object can be accurately measured.

In the radar device 1D of the fourth embodiment, the case 9 has a rectangular parallelepiped shape, but the case 9 may have a dome shape as shown in a cross-sectional view of the radar device 1D shown in fig. 14 (a) and a perspective view of the case 9B shown in fig. 14 (B), instead of the rectangular parallelepiped shape. In fig. 14, the same portions as those in fig. 10 are denoted by the same reference numerals, and the description thereof is omitted. The casing 9B covers the periphery of the radar device 1D, as with the casings 9 and 9A, except for the emission direction of the transmission wave transmitted from the transmission antenna Tx and the incidence direction of the reflected wave received by the reception antenna Rx. The same operational effects as those of the above-described embodiments can be obtained by the case 9B.

Further, the inner surfaces of the cases 9A and 9B shown in fig. 13 and 14 may be provided with radio wave absorbers 11. With these respective configurations, the same operational effects as those of the radar device 1D shown in fig. 12 can be achieved.

In the above-described embodiments, the case where the radar devices 1A, 1B, 1C, and 1D each include the distance/angle calculation unit 4 as a calculation circuit to measure the position of the target object has been described. However, the radar device of the present invention does not necessarily measure the position of the target object, and may measure the movement (motion) of the target object based on, for example, a reflected wave that is returned after the transmission wave collides with the target object. According to such a radar apparatus, the intermediate frequency signal IF obtained by the mixer circuit 3 can be corrected with high accuracy by removing the influence of the radome, and the same operational effects as those of the above-described embodiments can be obtained.

Description of the reference numerals

1A, 1B, 1C, 1D … radar device, 2 … RF signal generator, 3 … mixer circuit, 4 … distance/angle arithmetic unit (arithmetic circuit), 5 … antenna cover, 6 … correction data storage unit, 7 … phase shift amount calculation unit, 8 … antenna cover reflection correction unit, 9A, 9B … casing, 10 … road surface, 11 … radio wave absorber, 31 … attenuator, 32 … retarder, 41 … temperature sensor, 42 … table, 51 … vehicle, 51B … rocker panel (antenna cover), Tx … transmitting antenna, Rx1, Rx2, Rx3, Rx4 … receiving antenna, p … signal path.