JP2021004792A - Radar device and object detection method of radar device - Google Patents

Abstract

To accurately detect a position of an object in a depression angle direction.SOLUTION: A radar device has: a plurality of receiving antennas 17-1 to 17-4 which are aligned in a first direction; at least two transmission antennas 16-1 to 16-2 having different directional characteristics with respect to a second direction orthogonal to the first direction; first angle detection means (horizontal direction detection part 242) for detecting a first angle being an angle within which an object exists with respect to the first direction; second angle detection means (vertical direction detection part 243) for detecting a second angle being an angle within which the object exists with respect to the second direction on the basis of an intensity ratio of a received signal which is received by the receiving antenna; and storage means (table group 243a) for storing a plurality of tables indicating a relationship between the intensity ratio and the second angle according to the first angle which may be detected by the first angle detection means. The second angle detection means detects the second angle by referring to the table according to the first angle which is detected by the first detection means.SELECTED DRAWING: Figure 1

Description

The present invention relates to a radar device and a method for detecting an object of the radar device.

The techniques disclosed in Patent Document 1 and Patent Document 2 include two transmitting antennas and one receiving antenna arranged in the same plane in a radar device that identifies the position of a target using a 2-channel monopulse radar. Then, one of the transmitting antennas squeezes at an angle θ1 with respect to the boresight axis, and the other of the transmitting antennas squints at an angle θ2 with respect to the boresight axis, and the elevation amplitude ratio formed by these two transmitting antennas. It is characterized by deriving the elevation angle of the target based on the pattern.

Special Table 2015-528111 Japanese Unexamined Patent Publication No. 2016-102801

However, in the techniques disclosed in Patent Document 1 and Patent Document 2, the relationship between the elevation / depression angle (elevation angle) and the amplitude ratio may differ depending on the horizontal angle. In such a case, the elevation / depression angle may differ. There is a problem that the position of the direction is erroneously detected.

An object of the present invention is to provide a radar device capable of accurately detecting the position of an object in the elevation / depression angle direction and a method for detecting the object of the radar device.

In order to solve the above problems, the present invention is different from each other in a radar device for detecting an object with respect to a plurality of receiving antennas arranged in a row in the first direction and a second direction substantially orthogonal to the first direction. The reception is transmitted from each of the at least two transmitting antennas having directional characteristics, the first angle detecting means for detecting the first angle which is the angle at which the object exists in the first direction, and the transmitting antenna. Based on the intensity ratio of the received signal received by the antenna, the second angle detecting means for detecting the second angle, which is the angle at which the object exists, and the first angle detecting means for detecting the second direction are detected. It has a storage means for storing a plurality of tables showing the relationship between the intensity ratio and the second angle according to each of the first angles, and the second angle detecting means detects the first angle. It is characterized in that the second angle is detected with reference to the table corresponding to the first angle detected by the means.
According to such a configuration, it is possible to accurately detect the position of the object in the elevation / depression angle direction.

Further, the present invention is characterized in that the first angle detecting means detects the first angle of the object based on the angle spectrum of the received signal acquired by the Fourier transform.
According to such a configuration, the first angle can be obtained accurately and easily.

Further, in the present invention, the first angle detecting means sequentially transmits from each of the transmitting antennas, detects the first angle based on all the received signals received by the receiving antenna, and detects the first angle, and the second angle. The detection means is characterized in that the second angle is detected based on each of the received signals received by the receiving antenna, which is sequentially transmitted from each of the transmitting antennas.
According to such a configuration, the first angle is detected accurately based on all the transmitting antennas, and the second angle is detected based on each transmitting antenna, thereby sharing the configuration and efficiently performing the first angle. And the detection of the second angle can be realized.

Further, in the present invention, the first angle detecting means executes a process of sequentially transmitting from each of the transmitting antennas and obtaining an angle for all the received signals received by the receiving antenna, and peaks the processing result. The first angle is detected based on the position, and the second angle detecting means sequentially transmits from each of the transmitting antennas and obtains an angle for each of the received signals received by the receiving antenna. It is characterized in that the conversion process is executed and the intensity ratio at the first angle corresponding to the peak position detected by the first angle detecting means is detected.
According to such a configuration, the first angle is accurately detected based on the angle Fourier transform results of the received signals of all the transmitting antennas, and the second angle is detected based on the accurately detected first angle. Therefore, the detection accuracy of the second angle can be improved while reducing the processing.

Further, the present invention is characterized in that the first direction is a substantially horizontal direction, and the radar device is mounted on a vehicle.
According to such a configuration, an object existing around the vehicle can be accurately detected in the horizontal direction, and the position in the vertical direction thereof can also be detected.

Further, in the present invention, the transmitting antenna and the receiving antenna are each composed of a plurality of element antennas, and the number of the element antennas constituting one transmitting antenna is the number of the element antennas constituting one receiving antenna. It is characterized by being less than the number of.
According to such a configuration, it is possible to suppress a decrease in power related to the elevation / depression angle on the transmitting side and suppress a shortening of the detectable distance.

Further, in the present invention, the receiving antenna has a plurality of element antennas adjacent to each other including the element antenna closest to the transmitting antenna, and the power supplied to the element antenna closest to the transmitting antenna is It is characterized in that it is less than or equal to the power supplied to the other plurality of element antennas.
According to such a configuration, the isolation characteristics of the transmitting antenna and the receiving antenna can be improved.

Further, the present invention relates to a radar device having a plurality of receiving antennas arranged in a row in the first direction and at least two transmitting antennas having different directional characteristics in the second direction substantially orthogonal to the first direction. In the object detection method, the first angle detection step of detecting the first angle, which is the angle at which the object exists, and the reception transmitted from each of the transmitting antennas and received by the receiving antenna in the first direction. A second angle detection step that detects a second angle that is an angle at which the object exists in the second direction based on the signal intensity ratio, and each of the first that can be detected in the first angle detection step. It has a storage step for storing a plurality of tables showing the relationship between the intensity ratio and the second angle according to the angle, and the second angle detection step is detected in the first angle detection step. The second angle is detected by referring to the table corresponding to the first angle.
According to such a method, it is possible to accurately detect the position of the object in the elevation / depression angle direction.

According to the present invention, it is possible to provide a radar device capable of accurately detecting the position of an object in the elevation / depression angle direction and a method for detecting the object of the radar device.

It is a figure which shows the structural example of the radar apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the operation principle of the radar apparatus shown in FIG. It is a figure which shows the directivity characteristic of the transmission signal of the conventional radar apparatus. It is a figure which shows the directivity characteristic of the transmission signal of the embodiment shown in FIG. It is a figure which shows the result of 4 array angle FFT processing and 8 array angle FFT processing. This is an example of a curve showing the relationship between the angle index and the azimuth. It is a figure which shows the relationship between the gain difference and the elevation / depression angle at each azimuth angle. It is a figure which shows the polygonal line which approximates FIG. 7. It is a figure which shows the time waveform of the transmission signal of embodiment shown in FIG. It is a figure for demonstrating the operation of the virtual array antenna of the embodiment shown in FIG. It is a figure for demonstrating the operation of the virtual array antenna of the embodiment shown in FIG. It is a figure which shows the actual measurement result of the virtual array antenna of the embodiment shown in FIG. It is an arrangement example of the transmitting antenna and the receiving antenna of the embodiment shown in FIG. It is a figure which shows the operation as the virtual array antenna by the embodiment shown in FIG. It is a figure which shows the detailed configuration example of the transmitting antenna shown in FIG. It is a schematic diagram for demonstrating the relationship between the width of a beam radiated from a transmitting antenna and a detectable distance. It is a figure which shows the state which suppressed the side lobe by a receiving antenna. It is a figure which shows the detailed configuration example of the receiving antenna shown in FIG. It is a figure which shows the power gradient of the transmitting antenna and the receiving antenna shown in FIG. It is a figure which shows the operation of the embodiment shown in FIG. It is a figure which shows the operation of the embodiment shown in FIG. It is a figure for demonstrating the operation of the equivalent time sampling of the embodiment shown in FIG. It is a figure for demonstrating the process executed in the arithmetic unit shown in FIG. It is a flowchart for demonstrating operation of Embodiment shown in FIG. It is a flowchart for demonstrating operation of Embodiment shown in FIG. It is a flowchart for demonstrating operation of Embodiment shown in FIG. It is a flowchart for demonstrating operation of Embodiment shown in FIG. It is a figure for demonstrating another operation of the embodiment shown in FIG. It is a figure which shows the structural example of the radar apparatus which concerns on other embodiment of this invention.

Next, an embodiment of the present invention will be described.

(A) Explanation of Configuration of Embodiment of the Present Invention FIG. 1 is a diagram showing a configuration example of a radar device according to the embodiment of the present invention. As shown in this figure, the radar device 10 according to the embodiment of the present invention is mounted on a vehicle such as an automobile, and detects an object such as another vehicle, a pedestrian, or an obstacle existing around the vehicle. To do.

Here, the radar device 10 includes a control unit 11, an oscillation unit 12, a pulse shaping unit 13, a variable amplification unit 14, a selection unit 15, transmission antennas 16-1 to 16-2, and reception antennas 17-1 to 17-4. The selection unit 18, the amplification unit 19, the multiplication unit 20, the IF (Intermediate Frequency) amplification unit 21, the A / D (Analog to Digital) conversion unit 22, the storage unit 23, and the calculation unit 24 are the main components.

Here, the control unit 11 is composed of, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and controls each unit of the device. The dashed arrow in the figure indicates the control line.

The oscillating unit 12 generates and outputs a locally-generated signal having a predetermined frequency according to the control of the control unit 11.

The pulse shaping unit 13 shapes the rectangular wave supplied from the control unit 11 into a signal having a pulse waveform described later and outputs it.

The variable amplification unit 14 is configured by a voltage control amplifier circuit, and amplifies and outputs a locally generated signal according to the voltage of the pulse waveform supplied from the pulse shaping unit 13.

The selection unit 15 selects one of the transmission antennas 16-1 to 16-2 according to the control of the control unit 11 and supplies the output signal from the variable amplification unit 14.

The transmitting antennas 16-1 to 16-2 transmit the output signal from the variable amplification unit 14 as an electromagnetic wave toward the object.

The receiving antennas 17-1 to 17-4 receive the reflected signal transmitted by the transmitting antennas 16-1 to 16-2 and reflected by the object, convert it into an RF (Radio Frequency) signal, and send it to the selection unit 18. Supply.

The selection unit 18 selects any one of the RF signals supplied from the receiving antennas 17-1 to 17-4 and outputs the RF signal to the amplification unit 19.

The amplification unit 19 amplifies the RF signal output from the selection unit 18 with a predetermined gain and supplies it to the multiplication unit 20.

The multiplication unit 20 multiplies the local signal supplied from the oscillation unit 12 with the RF signal supplied from the amplification unit 19 to generate an IF (Intermediate Frequency) signal and output it.

The IF amplification unit 21 amplifies the IF signal output from the multiplication unit 20 with a predetermined gain and outputs the signal.

The A / D conversion unit 22 converts the IF signal output from the IF amplification unit 21 into digital data and outputs it.

The storage unit 23 is composed of, for example, a RAM or the like, and stores digital data supplied from the A / D conversion unit 22.

The calculation unit 24 includes a processing unit 241, a horizontal detection unit 242, a vertical detection unit 243, and a processing unit 244.

The processing unit 241 performs FFT (Fast Fourier Transform) processing on the digital data stored in the storage unit 23 to generate and output two-dimensional data relating to frequency and distance.

The horizontal detection unit 242 performs an angle FFT process using the data of eight array antenna systems supplied from the processing unit 241 to specify the horizontal angle of the object.

The vertical detection unit 243 performs an angle FFT process from the data supplied from the processing unit 241 using the data of the four array antennas related to the transmitting antennas 16-1 and 16-2, respectively. Further, the vertical detection unit 243 is used to collect data of four array antenna systems related to the transmission antennas 16-1 and 16-2 at the horizontal angle (azimuth) of the object specified by the horizontal detection unit 242. Calculate the strength ratio. Further, the vertical detection unit 243 acquires information indicating the relationship between the vertical angle (elevation / depression angle) and the intensity ratio corresponding to the azimuth angle of the object specified by the horizontal detection unit 242 from the table group 243a. Then, based on this information, the elevation / depression angle of the object is specified.

The processing unit 244 is based on the distance information acquired by the processing unit 241 and the position and speed of the object specified based on the azimuth and elevation / depression angles acquired by the horizontal detection unit 242 and the vertical detection unit 243. Therefore, the presence or absence of collision or contact with the own vehicle is determined, and the determination result is not shown in a higher-level device (for example, an application processing unit in the radar device 10 or an ECU (Electric Control Unit) outside the radar device 10). ). Alternatively, the position and speed information of the object is supplied to the ECU, and the ECU determines whether or not there is a collision or contact with the automobile.

Although not shown in FIG. 1 for simplification of the drawings, the multiplication unit 20 orthogonally demodulates the signal output from the amplification unit 19 and outputs it as an IQ signal. Therefore, the two components I and Q are transmitted from the multiplication unit 20 onward.

(B) Description of Operation of Embodiment Next, the operation of the embodiment of the present invention will be described. In the following, the operation of the embodiment of the present invention will be described with reference to FIGS. 2 to 23, and then the detailed operation will be described with reference to the flowcharts of FIGS. 24 to 27.

2 to 8 are diagrams showing the operating principle of the present invention. As an example, consider the case where a radar device is installed in the rear bumper of the vehicle shown in FIG. In this case, the conventional radar device transmits a transmission signal having directivity as shown in FIG. 3 toward the rear of the vehicle. In FIG. 3, the horizontal axis represents the gain [dB] and the vertical axis represents the elevation / depression angle. In the example of FIG. 3, the transmitted signal has a directivity characteristic of line symmetry about the axis of the elevation / depression angle of 0 degrees. Since the conventional radar device cannot detect the angle in the elevation / depression angle direction, the object O1 (for example, a pole installed on the ground) shown in FIG. 2 (A) and the object shown in FIG. 2 (B). It cannot be distinguished from O2 (for example, a bollard installed on the ground). For this reason, in the conventional radar device, a warning may be issued to the object O2, or the vehicle may be stopped by operating the brake.

In the present embodiment, as shown in FIG. 4, transmission signals having different directivity in the vertical direction are transmitted at different timings. Then, the angle in the vertical direction is obtained from the difference in the power (for example, intensity, amplitude, etc.) of these reflected signals reflected by the object. More specifically, in the example shown in FIG. 4, the solid line curve shows the directivity characteristic of the transmitted signal having the first directivity characteristic, and the broken line curve shows the directivity characteristic of the transmitted signal having the second directivity characteristic. In the embodiment of the present invention, for example, a solid line transmission signal having the first directivity is transmitted from the transmission antenna 16-1, and the first reflection signal reflected by the object is received. Further, the transmission antenna 16-2 transmits a transmission signal having a broken line having a second directivity characteristic, and receives the second reflection signal reflected by the object.

The horizontal detection unit 242 acquires the data of eight array antennas related to all the transmitting antennas 16-1 and 16-2 from the data defined by the distance and frequency supplied from the processing unit 241 and performs the angle FFT processing. By executing this, for example, the processing result shown by the solid line in FIG. 5 is obtained. In FIG. 5, the horizontal axis represents the angle index after the FFT process, and the vertical axis represents the amplitude.

The horizontal direction detection unit 242 identifies the horizontal position of the object by detecting the peak of the processing result data, and specifies the angle index i1 which is the peak position. The horizontal direction detection unit 242 refers to the information showing the correspondence between the angle index and the azimuth angle shown in FIG. 6, and converts the specified angle index into the azimuth angle. Then, the angle index and the azimuth angle are output to the vertical direction detection unit 243. The horizontal axis of FIG. 6 indicates the azimuth angle, and the vertical axis indicates the angle index. In FIG. 6, a plurality of curves are drawn, which will be described later.

The vertical detection unit 243 performs angle FFT processing on the data of the four array antennas related to the transmission antenna 16-1 from the data defined by the distance and frequency supplied from the processing unit 241, so that the interval in FIG. 5 is set. Obtain the processing result shown by the long broken line. Similarly, the vertical detection unit 243 obtains the processing result shown by the broken line having a short interval in FIG. 5 by performing the angle FFT processing on the data of the four array antennas related to the transmitting antenna 16-2.

The vertical detection unit 243 acquires the amplitude value a1 corresponding to the angle index supplied from the horizontal detection unit 242 in the processing result shown by the broken line having a long interval in FIG. 5, and is shown by the broken line having a short interval in FIG. In the processing result, the amplitude value a2 corresponding to the angle index supplied from the horizontal detection unit 242 is acquired. Then, the intensity ratio (a1 / a2) of the amplitude values a1 and a2 is obtained.

The vertical detection unit 243 specifies the elevation / depression angle based on the correspondence between the ratio of the amplitude values and the elevation / depression angle. For example, in the case of the object O2 shown in FIG. 2B, the second reflected signal with respect to the transmission signal having the second directional characteristic has a certain intensity (power), but the first with respect to the transmission signal having the first directional characteristic. Since the intensity of the reflected signal is smaller than that of the second reflected signal (second reflected signal> first reflected signal), a1 / a2 <1 in this case.

On the other hand, in the case of the object O1 shown in FIG. 2 (A), the intensity of the first reflected signal with respect to the transmitted signal having the first directivity and the intensity of the second reflected signal with respect to the transmitted signal having the second directivity are approximately a certain magnitude. Therefore, a1 / a2 is larger than that in FIG. 2 (B). That is, it is possible to roughly distinguish the objects in terms of strength ratio.

Further, a table in which the relationship between a1 / a2 and the elevation / depression angle of the object is associated is stored in advance, and by referring to this table, the elevation / depression angle of the object can be obtained from a1 / a2. ..

By the way, the relationship between the strength ratio and the elevation / depression angle is not always constant depending on the azimuth angle. FIG. 7 is a diagram showing the relationship between the gain difference (Tx1-Tx2) and the elevation / depression angle. In FIG. 7, each of the polygonal lines shows the relationship between the elevation / depression angle and the gain difference at the azimuth angle shown in the upper left of FIG. 7. As shown in FIG. 7, in an actual radar device, the elevation / depression angle characteristic may depend on the azimuth angle depending on the circuit board, radome, and the like. In particular, in an in-vehicle radar device, the azimuth range is generally wider than the elevation / depression range, so it is difficult to define a wide azimuth with one elevation / depression characteristic.

Therefore, in the present embodiment, the vertical detection unit 243 obtains information showing the relationship between the gain difference and the elevation / depression angle shown in FIG. 7 or a characteristic obtained by linearly approximating the characteristic shown in FIG. 7 as shown in FIG. It is stored in advance as a table group 243a composed of a plurality of tables associated with the corners, and a table corresponding to the azimuth angle detected by the horizontal direction detection unit 242 is acquired from the table group 243a and corresponds to the table. The elevation / depression angle is specified based on the relationship between the gain difference (or intensity ratio) and the elevation / depression angle. In FIG. 8, a fold line having section information and two types of inclination information is used as one table, and the elevation / depression angle is specified from the gain difference (or strength ratio) with reference to the fold line. Since the range of elevation and depression angles is relatively narrow, from the viewpoint of storage capacity suppression, information on the section and two types of inclination, or even less information (for example, information on the section and one type of inclination) is used. It is preferable to specify the elevation / depression angle approximately. In FIG. 8, the range from −60 degrees to +60 degrees is defined as nine polygonal lines in increments of 15 degrees, but the angle range other than this may be a polygonal line in increments of other than this, for example, in increments of 3 degrees. Further, instead of a polygonal line, a straight line or a curved line may be used, or an approximate expression indicating a polygonal line, a straight line, or a curved line may be used. Further, when the polygonal line of the corresponding angle does not exist, the value for the target angle may be obtained from the polygonal line of a close angle by interpolation processing. For example, in the case of 55 degrees, it may be obtained by interpolation processing from the polygonal lines of 45 degrees and 60 degrees.

The processing unit 244 detects the height of the object based on the elevation / depression angle supplied from the vertical detection unit 243. Then, as shown in FIG. 2 (A), if the height is such that it contacts (or collides with) the vehicle, a warning or control is given, and as shown in FIG. 2 (B), at a height that does not contact the vehicle. In some cases, warnings or controls can be turned off.

Next, the detailed operation of the embodiment of the present invention will be described with reference to FIGS. 1 to 23.

When the engine of the vehicle (not shown) equipped with the radar device 10 is started, the power supply to each part of the radar device 10 shown in FIG. 1 is started, and the operation becomes possible.

When the supply of power supply power is started, the control unit 11 starts the output of the local signal to the oscillation unit 12 and supplies a rectangular wave to the pulse shaping unit 13 to generate a pulse signal. As a result, the pulse signal shown in FIG. 9 is output from the transmitting antennas 16-1 to 16-2.

FIG. 9 is a diagram showing an example of a transmission signal transmitted from the radar device 10 shown in FIG. As shown in FIG. 9A, the transmission signal includes a pulse P with a repetition period T0. As shown in the enlarged view of FIG. 9B, the pulse P has an amplitude of A.

FIG. 9C shows an example of a signal supplied from the control unit 11 to the pulse shaping unit 13. The pulse shaping unit 13 shapes and outputs the rectangular wave shown in FIG. 9 (C) supplied from the control unit 11 as shown in FIG. 9 (B). The variable amplification unit 14 amplifies and outputs the local signal supplied from the oscillation unit 12 based on the amplitude of the signal supplied from the pulse shaping unit 13. As shown in FIG. 9C, the signal supplied from the control unit 11 has a pulse width W so that the amplitude of the pulse signal output from the variable amplification unit 14 is A shown in FIG. 9B. It has been adjusted.

The pulse P transmitted from either one of the transmitting antennas 16-1 and 16-2 is reflected by the object, received as a reflected signal by the receiving antennas 17-1 to 17-4, converted into an RF signal, and output. Will be done.

Since the selection unit 18 selects any one of the receiving antennas 17-1 to 17-4, the reflected signal received by the receiving antennas 17-1 to 17-4 selected by the selection unit 18 becomes an RF signal. It is converted and supplied to the amplification unit 19.

The amplification unit 19 amplifies and outputs the RF signal supplied from the selection unit 18 with a predetermined gain. The multiplication unit 20 multiplies the received signal supplied from the amplification unit 19 and the locally generated signal supplied from the oscillation unit 12, converts (down-converts) the signal into an IF signal, and outputs the signal.

The IF amplification unit 21 amplifies and outputs the IF signal supplied from the multiplication unit 20. The A / D conversion unit 22 A / D-converts the IF signal supplied from the IF amplification unit 21 and outputs the signal. The A / D conversion unit 22 samples the received signal supplied from the IF amplification unit 21 for an equivalent time and outputs it, as will be described later with reference to FIG.

The storage unit 23 stores the digital data output from the A / D conversion unit 22 and supplies it to the processing unit 241 of the calculation unit 24.

As will be described later, the processing unit 241 performs FFT processing on the digital data supplied from the storage unit 23 to generate two-dimensional data related to the distance and frequency, and the horizontal detection unit 242 and the vertical detection unit 242. Supply to 243.

The horizontal direction detection unit 242 executes a process of detecting the position and speed of the object in the horizontal direction in the same manner as the conventional radar device. The horizontal detection unit 242 uses the transmitting antennas 16-1 to 16-2 and the receiving antennas 17-1 to 17-4 to improve the resolution of the horizontal position by using the principle of the virtual array antenna. be able to.

The principle of the virtual array antenna will be described below. As shown in FIG. 10, eight receiving antennas Rx (0) to Rx (7) indicated by triangles are arranged at intervals d, and at a predetermined distance from the receiving antennas Rx (7), they are also formed in triangles. It is assumed that the transmitting antenna Tx shown is arranged. At this time, as shown in FIG. 10, when the incident angle of the radio wave with respect to the front direction of each antenna is θ, the path difference of the receiving antenna Rx (1) with respect to the receiving antenna Rx (0) is calculated by the following equation (1). It is represented by. The plus sign indicates that the distance between the routes is long, and the minus sign indicates that the distance is short.

ΔL = −d · sin (θ) ・ ・ ・ (1)

Further, when the wavelength of the radio wave is λ, the phase difference Δφ of the receiving antenna Rx (1) with respect to the receiving antenna Rx (0) is expressed by the following equation (2).

Δφ = -2πd / λ ・ sin (θ) ・ ・ ・ (2)

From the above, the received signal v_Rx (m, Tx1) of each receiving antenna Rx (m) (m = 0,1, ..., 7) is represented by the following equation (3). Note that j is an imaginary number.

v_Rx (m, Tx1) = v_Rx (0, Tx1) ・ exp (j ・ m ・ Δφ)
... (3)

From the above equations (2) and (3), it can be seen that the phase rotation components of the receiving antenna correspond to the incident angle of the radio wave. By Fourier transforming these received signals, it is possible to extract the received signal rotation component, that is, to specify the incident angle of the radio wave. Further, the incident angle may be specified by high resolution processing other than the Fourier transform.

Next, as shown in FIG. 11, consider a case where the transmitting antenna Tx2 is newly provided and the receiving antennas Rx (4) to Rx (7) are excluded. At this time, the distance from Tx2 to the object is longer by N / 2 ・ d ・ sin (θ) than Tx1, and the distance from the receiving antenna Rx (0) to the object with respect to the receiving antenna Rx (4). Is also longer by N / 2 ・ d ・ sin (θ). At this time, the following equations (4) and (5) are established. However, N indicates the number of receiving antennas (N = 8 in the example of FIG. 11).

v_Rx (m, Tx1) = v_Rx (m, Tx1) ... (4)
However, when m ≦ N / 2-1

v_Rx (m, Tx1) = v_Rx (m-N / 2, Tx2) · exp (j · N · Δφ)
... (5)
However, when m> N / 2-1

From the above equations (4) and (5), it can be seen that the system of only one transmitting antenna Tx1 and the system of two transmitting antennas Tx1 and Tx2 are equivalent when the angles of the outward path and the returning path are the same. ..

Here, exp (j · N · Δφ) on the right side of the equation (5) is a phase correction term, which is equivalent to moving the antenna by N minutes. Therefore, when the system having one Tx1 shown in FIG. 12 (A) is equivalent to the system having two Tx1 and Tx2 shown in FIG. 12 (B), as shown in FIG. 12 (C), By calculating assuming that the receiving antennas Rx (-4) to Rx (3) are arranged, exp (j), which is a phase correction term, is shown in the following equations (6) to (13).・ There is no need to consider N ・ Δφ).

v_Rx (-4, Tx) = v_Rx (0, Tx2) ... (6)
v_Rx (-3, Tx) = v_Rx (1, Tx2) ... (7)
v_Rx (-2, Tx) = v_Rx (2, Tx2) ... (8)
v_Rx (-1, Tx) = v_Rx (3, Tx2) ... (9)
v_Rx (0, Tx) = v_Rx (0, Tx1) ... (10)
v_Rx (1, Tx) = v_Rx (1, Tx1) ... (11)
v_Rx (2, Tx) = v_Rx (2, Tx1) ... (12)
v_Rx (3, Tx) = v_Rx (3, Tx1) ... (13)

That is, by using the two transmitting antennas, the four receiving antennas can be virtually expanded to eight. In this embodiment, the principle of such a virtual array antenna is used.

FIG. 13 shows a detailed configuration example of the transmitting antennas 16-1 to 16-2 and the receiving antennas 17-1 to 17-4 shown in FIG. In the example shown in FIG. 13, the transmitting antennas 16-1 to 16-2 are each composed of an array antenna having four element antennas, specifically, a patch antenna. Further, the receiving antennas 17-1 to 17-4 are each composed of eight element antennas, specifically, an array antenna having a patch antenna. The receiving antennas 17-1 to 17-4 are formed, for example, on the surface of a dielectric substrate or the like, and as shown in FIG. 13, eight patches in the Y direction, which is the vertical direction, are linearly spaced at predetermined intervals. Arranged and configured. Further, the receiving antennas 17-1 to 17-4 are arranged at predetermined intervals in the X direction, which is the left-right direction, and patches constituting the receiving antennas 17-1 to 17-4 are arranged in a matrix. The transmitting antenna 16-1 is arranged at the lower right of the receiving antenna 17-1, and the transmitting antenna 16-2 is arranged at the lower left of the receiving antenna 17-4. Assuming that the distances of the receiving antennas 17-1 to 17-4 are d, the distances of the transmitting antennas 16-1 to 16-2 are represented by 4 × d. Further, the transmitting antenna 16-1 and the receiving antenna 17-1 are arranged so as to be separated by a distance D in the X direction, and the transmitting antenna 16-2 and the receiving antenna 17-4 are arranged so as to be separated by a distance D in the X direction. Has been done.

Although the arrangement of the antenna shown in FIG. 13 is different from that of FIG. 11, it can operate as a virtual array antenna as shown in FIG. That is, by using the transmitting antennas 16-1 to 16-2, the receiving antennas 17-1 to 17-4 are virtually extended to the 8-array antennas of the receiving antennas 17-1 to 17-8.

FIG. 15 shows a detailed configuration example of the transmitting antennas 16-1 to 16-2 shown in FIG. In FIG. 15, the distance between the transmitting antennas 16-1 to 16-2 is narrower than the actual distance in order to simplify the drawing. In the example of FIG. 15, the transmitting antenna 16-1 has four patch antennas 1611 to 1614. Further, the patch antennas 1611 to 1614 are connected to each other by feed lines L11 to L13, and a transmission signal is supplied from the feed point Fp1. Similarly, the transmitting antenna 16-2 also has four patch antennas 1621-1624. Further, the patch antennas 1621 to 1624 are connected to each other by feed lines L21 to L23, and a transmission signal is supplied from the feed point Fp2.

Here, the lengths of the feeder lines L11 to L13 constituting the transmitting antenna 16-1 are set so that L13> L12> L11. The lengths of the feeder lines L21 to L23 constituting the transmitting antenna 16-2 are set so that L23> L22> L21.

By setting in this way, a phase delay occurs according to the length of the feeder line. Therefore, when the transmission signal is supplied to the feed point Fp1 in the transmission antenna 16-1, the phases are in the order of the patch antennas 1611 to 1614. Since the advanced electromagnetic wave is transmitted, the electromagnetic wave is radiated downward. At the transmitting antenna 16-2, the electromagnetic wave whose phase is advanced in the order of the patch antennas 1624 to 1621 is transmitted, so that the electromagnetic wave is radiated upward. Will be done. As a result, the directivity shown in FIG. 4 can be realized.

Further, in the present embodiment, as shown in FIG. 13, the number of patch antennas constituting the transmitting antennas 16-1 to 16-2 is 4, and the number of patch antennas constituting the receiving antennas 17-1 to 17-4 is set to 4. The number is set to 8, and the number of patch antennas constituting the transmitting antennas 16-1 to 16-2 is set to be smaller. This is due to the following reasons. That is, when the beam width (for example, half width) of the transmitting antennas 16-1 to 16-2 is wide, the area where the beams overlap is wide, and when the beam width is narrow, the beams overlap. The area is small. FIG. 16 is a diagram schematically showing overlapping regions depending on whether the beam is wide or narrow. More specifically, FIG. 16 is a schematic view showing an overlapping state of two beams upward and downward in the vertical direction, FIG. 16A shows a case where the beam width is wide, and FIG. 16B shows a case where the beam width is wide. The case where the width of the beam is narrow is shown. In addition, in FIG. 16A and FIG. 16B, the beam irradiation angle (vertical angle) is the same. When an object is detected using the two transmitting antennas 16-1 to 16-2, the range in which the object can be detected is the range in which the two beams overlap. Therefore, in FIG. 16A, the gain G1 is obtained. It is the corresponding range, and in FIG. 16B, it is the range corresponding to the gain G2. Therefore, the wider the beam width, the farther the object can be detected.

Therefore, in the present embodiment, the beam width in the vertical direction is increased by setting the number of elements constituting the transmitting antennas 16-1 to 16-2 to 4, which is less than 8 of the receiving antennas 17-1 to 17-4. It is widened and the fluctuation of the detectable distance is made smaller than when the beam width in the vertical direction is narrow. Specifically, even if the tilt angle is the same, the decrease in gain in the frontal direction of the elevation / depression angle is small, and the decrease in gain can be small even when the pitch angle is changed when the vehicle is mounted. In addition, the effect of transmitted radio waves on other devices increases or decreases in proportion to the product of the peak gain of the antenna and the supplied power (for example, the regulation of the Radio Law is the product of the peak gain of the antenna and the supplied power). Determined by). Therefore, if the beam width is widened, the peak gain of the antenna is reduced, but by increasing the supplied power in accordance with the decrease in the peak gain, it is possible to suppress the power reduction related to the elevation / depression angle. At that time, the influence on other devices is the same as before the increase. And, of course, the radar device can be downsized because the number of elements of the transmitting antenna is small.

The above is a description of the transmission gain of the transmitting antennas 16-1 to 16-2, but the receiving antennas 17-1 to 17-4 also have a receiving gain, and the transmitting antennas 16-1 to 16- The total gain can be calculated by multiplying the transmission gain of 2 and the reception gain of the receiving antennas 17-1 to 17-4. FIG. 17 is a diagram showing the total gain obtained by the product of the transmitting antennas 16-1 to 16-2 and the receiving antennas 17-1 to 17-4. In this figure, the broken line shows the gain when the receiving antenna shown in FIG. 18 (A) is used, and the solid line shows the gain when the receiving antenna shown in FIG. 18 (B) is used.

In the receiving antenna shown in FIG. 18A, the widths of the feeder lines L31 to L36 connecting the patch antennas 1711 to 1718 are substantially constant. On the other hand, in the receiving antenna shown in FIG. 18B, a narrow path is shaped in a part of the feeder lines L41 to L46 connecting the patch antennas 1721 to 1728 to adjust the width, and as a result, FIG. Like the curve shown by the solid line, the side lobes are suppressed as compared with the curve shown by the broken line. More specifically, for example, when the patch antennas 1721 to 1724 are viewed from the center in the vertical direction of the antenna of FIG. 18B, the patch antennas are connected so that the impedances of the patch antennas have different values. The width of a part of the feeding line is adjusted. The same applies to the patch antennas 1725 to 1728. Since the angle range in which the side lobes exist has a gain, false positives may occur. In the case of the gain curve shown by the broken line, the side lobe gain is larger and the number is larger than that of the solid line gain curve, so there is a high possibility that an object outside the main lobe range is erroneously detected by the side lobe. On the other hand, in the solid line gain curve, the side lobes are suppressed (the gain is small and the number is small), so that false detection of the object can be reduced.

As described above, the total gain can be obtained by the product of the transmitting antennas 16-1 to 16-2 and the receiving antennas 17-1 to 17-4, so the transmitting antennas 16-1 to 16-2 should be adjusted. But it is possible to suppress the side lobes. However, since the number of patch antennas of the transmitting antennas 16-1 to 16-2 is small, the degree of freedom in design is low. On the other hand, the receiving antennas 17-1 to 17-4 have a high degree of freedom in design because the number of patch antennas is large. Therefore, in the present embodiment, the side lobes are suppressed in the receiving antennas 17-1 to 17-4.

FIG. 19 is a diagram showing the power supplied to the elements constituting the transmitting antenna 16-1 and the receiving antenna 17-1. The transmitting antenna 16-2 and the receiving antennas 17-2 to 17-4 are also supplied with the same power as in FIG. 19, but are omitted for simplification of the drawings. As shown in FIG. 19, the receiving antenna 17-1 is set so that the power of the element decreases as it approaches both ends and has a power gradient. In this way, the power supplied to the element closest to the transmitting antenna 16-1 is equal to or less than the power supplied to a plurality of elements adjacent to each other, such as an element adjacent to the element and an element adjacent to the element. It has become. A part of the radio wave transmitted from the transmitting antenna 16-1 wraps around the receiving antenna 17-1 and is received. In particular, the size of the wraparound becomes remarkable at the position closest to the transmitting antenna and the receiving antenna. Therefore, for example, by setting the power of the receiving antenna 17-1 as shown in FIG. 19, the side lobe is reduced, and the power in a portion close to the transmitting antenna 16-1 is suppressed, so that such wraparound is performed. Can be reduced. At the same time, the polarization direction of the antenna and the layout direction of the antenna are orthogonal to each other to suppress wraparound. As a result, it is possible to detect an object closer to the object and the elevation / depression angle. Further, since the transmitting antenna and the receiving antenna can be brought close to each other, the device can be miniaturized.

Further, in the embodiment of the present invention, the radio waves transmitted from the two transmitting antennas are tilted, and the elevation / depression angle is detected based on the difference in the amplitude of the received signals. It is also possible to detect the elevation / depression angle by the phase difference. That is, it is also possible to give a phase difference to the radio waves transmitted from the two transmitting antennas and detect the elevation / depression angle based on the phase difference of the received signal. When detecting the elevation / depression angle based on the phase difference, it is necessary to displace the transmitting antennas 16-1 to 16-2 in the vertical direction (Y), but in order to improve the angle discrimination performance, this is necessary. It is necessary to increase the deviation. In that case, the area occupied by the transmitting antennas 16-1 to 16-2 in the Y direction becomes large, so that the size of the device becomes large. On the other hand, in the case of the embodiment of the present invention, in order to tilt the radio wave, it can be achieved by adjusting the power supply to each antenna element without changing the position of the antenna. Therefore, even if the tilt angle is increased, the device can be tilted. There is also a feature that the size does not increase.

Next, equivalent time sampling will be described. FIG. 22 is a diagram showing an example of equivalent time sampling processing for pulse P. FIG. 22 (A) shows the transmitted pulse P. Further, FIGS. 22 (B) to 22 (G) show fields in equivalent time sampling. More specifically, when the pulse P shown in FIG. 22 (A) is transmitted, as shown in FIG. 22 (B), in the first field, the A / D conversion unit 22 has a period t1 from the peak position of the pulse P. Perform sampling with. In the example of FIG. 22, each field is sampled five times as shown by an arrow. As shown in FIG. 22C, in the second field, when compared with the first field, sampling is started with an offset of time τ1. The sampling period is t1 as in the first field. As shown in FIGS. 22 (D), in the third field, sampling is started offset by a time τ1 as compared with the second field, and similarly, as shown in FIGS. 22 (E) to 22 (G), the third field is used. In the 3 to 6 fields, sampling is started with an offset of time τ1 as compared with the immediately preceding field.

Although details are not shown in FIG. 22, in each field, for example, one high-frequency pulse signal is transmitted and received for each of the transmitting antennas 16-1 and 16-2 and the receiving antennas 17-1 to 17-4. And sampling is performed at the same offset. That is, in the first field, for example, a pulse is transmitted from the transmitting antenna 16-1, and the reflected signal is sampled by the receiving antenna 17-1 at each timing shown in FIG. 22 (B). Next, the antenna is switched to the receiving antenna 17-2, and the reflected signal is sampled at each timing shown in FIG. 22 (B). Next, the receiving antennas 17-3 to 17-4 similarly sample the reflected signal at each timing shown in FIG. 22B. Subsequently, the transmitting antenna is switched to 16-2, and the reflected signal is sampled by the receiving antennas 17-1 to 17-4 at each timing shown in FIG. 22 (B). Assuming that the above operation is one cycle, such a cycle is performed once for the first field (a total of 8 (= 2 × 4 × 1) high frequency pulse signals are transmitted), and the data in the first field is obtained. To be acquired. When the sampling of the first field is completed, the sampling of the second to sixth fields is subsequently executed. Then, when the sampling of all the fields is completed, the sampling of the first field is resumed again. After repeating such an equivalent time sampling process a predetermined number of times (for example, 2,048 times), a process of detecting an object and the like are executed. In FIG. 22, the number of sampling times for each field is set to 5, but other times may be used. Further, in each field, one cycle is performed once, but it may be repeated a number of times other than this.

Next, the processing of the calculation unit 24 will be described in detail. The processing unit 241 is sampled for equivalent time by the A / D conversion unit 22, and each distance information is stored in the storage unit 23. Further, by repeatedly acquiring each of these distance information a plurality of times in a fixed time, each distance information at each fixed time is stored in the storage unit 23. By reading out the data for each time at each distance stored in the storage unit 23 and performing the FFT process, not only the distance to the object but also the two-dimensional data related to the frequency is generated. As a result, four systems of two-dimensional data by the transmitting antenna 16-1 and the receiving antennas 17-1 to 17-4, and four systems of two-dimensional data by the transmitting antenna 16-2 and the receiving antennas 17-1 to 17-4, Two-dimensional data of distance and frequency in a total of eight systems are obtained. It should be noted that a plurality of antenna sequences, a plurality of distance sequences, a repeating sequence for acquiring frequency components, and the order of acquisition of these can be arbitrarily determined by design. In addition, before the following angle processing, a detection process that uses some threshold to narrow down the data with sufficient amplitude among the two-dimensional data defined by the distance and frequency as a signal that is a candidate for the object. It is also possible to do. Thereby, it is possible to reduce the quantity of the following angle processing.

The horizontal detection unit 242 executes the process P1 surrounded by a broken line on the left side of FIG. 23. That is, the horizontal detection unit 242 uses the above-mentioned total of eight systems of data as eight-point data, and performs zero padding to generate data such as 128 points or 256 points (power points of 2). .. The horizontal detection unit 242 executes 8-array angle FFT processing (P10) on the data obtained by performing zero padding, so that, for example, the processing result as shown by the solid line in FIG. 5, the so-called angle spectrum, can be obtained. obtain.

Next, the horizontal direction detection unit 242 executes the peak index search process (P11) on the angle spectrum as a result obtained by the 8-array angle FFT process. As a result, in the example of FIG. 5, the angle index i1 of the peak position in the curve shown by the solid line is acquired. It is also possible to determine a signal that is a candidate for an object by comparing the acquired peak amplitude value with some threshold value. The peak amplitude obtained at this stage is the result of integrating the information of all channels of the transmitting antenna and the receiving antenna, and by making a judgment based on the result of a high S / N (Signal Noise) ratio, the object can be accurately measured. Signal can be identified. Further, by excluding the noise component from the object at this stage, it is possible to reduce the number of times of processing and further reduce the subsequent processing load. Further, by using the information of all channels for the angle detection in the horizontal plane direction, it is possible to improve the resolution in the horizontal plane where high resolution is required in a wide range.

Next, the horizontal direction detection unit 242 refers to the table (TA1) showing the relationship between the angle index and the azimuth stored in advance, and executes the process (P12) of specifying the azimuth angle of the object. More specifically, the azimuth is specified with reference to a table showing the relationship between the angle index and the azimuth as shown in FIG. For example, in the example of FIG. 5, the angle index at the peak position of the solid line curve is about “65”, and when “65” is applied to FIG. 6, an azimuth of about -30 degrees is obtained.

Since the transmitting antennas 16-1 and 16-2 have different directivity characteristics in the vertical direction as shown in FIG. 4, the relationship between the angular index and the azimuth angle is different for each of the transmitting antennas 16-1 and 16-2. It is expected that they will be different. However, as shown in FIG. 6, when the mounting angle of the radar device is 0 degrees with respect to the horizontal direction (shown by the solid line in FIG. 6) and when it is +6 degrees with respect to the horizontal direction (the interval in FIG. 6). There is almost no change in characteristics between the case of -6 degrees with respect to the horizontal direction (when indicated by a broken line with a short interval in FIG. 6) and the case of -6 degrees with respect to the horizontal direction (when indicated by a long broken line). Therefore, it is possible to make a judgment using one type of table instead of providing a table for each of the mounting angles and different elevation / depression angles. Of course, depending on the mounting angle and different elevation / depression angles, a table may be provided for each.

Next, the operation of the vertical detection unit 243 will be described. The vertical detection unit 243 executes the process P2 surrounded by a broken line on the right side of FIG. 23. That is, the vertical detection unit 243 acquires the data of 4 points regarding the transmitting antenna 16-1 from the data of the total of 8 systems described above, and performs zero padding to generate data of, for example, 128 points or 256 points. Then, the 4-array angle FFT process (P20) is executed on such data. As a result, for example, the processing result shown by the broken line with a long interval in FIG. 5 obtains an angle spectrum with four arrays.

Further, the vertical detection unit 243 similarly executes the 4-array angle FFT process (P21) on the 4-point data regarding the transmitting antenna 16-2. As a result, for example, the processing result shown by the broken line with a short interval in FIG. 5 obtains an angle spectrum with four arrays.

Next, the vertical detection unit 243 identifies the peak value from the processing results obtained by the 4-array angle FFT processing (P20, P21) based on the angle index specified by the processing of P11 of the horizontal detection unit 242. Then, let each peak value be the first amplitude a1 and the second amplitude a2. More specifically, the vertical detection unit 243 has a long-interval dashed line obtained by the 4-array angle FFT process (P20) when the angle index identified by the process of P11 is i1 as shown in FIG. In the case where the process (P22) for acquiring the first amplitude value a1 when the angle index is i1 is executed and the angle index is i1 in the broken line with a short interval obtained by the 4-array angle FFT process (P21). The process (P23) for acquiring the first amplitude value a2 is executed. As described above, the number of peak search processes can be reduced by specifying the amplitude value of the angle spectrum by the four arrays in the vertical direction detection unit 243 using the peak position specified by the horizontal direction detection unit 242.

Next, the vertical detection unit 243 obtains the ratio of the first amplitude a1 and the second amplitude a2 obtained by the processing of P22 and P23. For example, these ratios can be determined by a1 / a2. It should be noted that the difference value may be used instead of the ratio. When the complex FFT is executed and the I component and the Q component are obtained, AI ² + AQ ² is calculated for the received signals of the transmitting antenna 16-1 and the transmitting antenna 16-2 based on these amplitudes AI and AQ. Then, the vertical detection unit 243 may calculate the ratio by dividing AI ² + AQ ² for the transmitting antenna 16-1 by AI ² + AQ ² for the transmitting antenna 16-2. In short, it is possible to obtain the magnitude relationship between the first amplitude and the second amplitude.

Next, the vertical detection unit 243 refers to the table TA2 (corresponding to one table constituting the table group 243a) stored in advance, and executes a process (P25) for specifying the elevation / depression angle. More specifically, the vertical detection unit 243 selects and acquires a line segment corresponding to the azimuth angle specified by the horizontal detection unit 242 by the process of P12, for example, from the table group shown in FIG. For example, in the examples of FIGS. 5 and 6, since the azimuth angle with respect to the angle index i1 is about -30 degrees, a broken line (corresponding to the azimuth angle -30 degrees) shown by a broken line having a short interval between thin lines in FIG. A table that specifies the elevation / depression angle with respect to the values of a1 / a2) is acquired. Then, the vertical direction detection unit 243 applies the strength ratio obtained in the process of P24 to the acquired polygonal line to specify the elevation / depression angle. For example, when the gain difference is -6 dB, an elevation / depression angle of about -7 degrees can be obtained.

In the above, the results of the 8-array angle FFT process and the 4-array angle FFT process are subjected to zero padding so that the data becomes 128 points or 256 points as an example. However, regarding the 4-array angle FFT process, Zero padding may be performed so that the number of points is less than that of the 8-array angle FFT process. When zero padding is performed with a small number of points, the number of points can be adjusted by division, rounding, etc. in the correspondence relationship of the angle indexes. Further, the 8-array angle FFT processing result may be interpolated by Lagrange interpolation or the like without increasing the number of points. In these cases, the identification of the angle index contributes to the accuracy of the azimuth in the 8-array angle FFT, and the specification of the amplitude value contributes to the accuracy of the elevation / depression angle in the 4-array angle FFT. It is a means to reduce processing after doing so.

The processing unit 244 executes a process of integrating the distance information by the processing unit 241 and the detection result of the horizontal direction detection unit 242 and the vertical direction detection unit 243. More specifically, it is assumed that when the vehicle is moving backward, the horizontal detection unit 242 detects a signal that is a candidate for an object behind the vehicle. In this case, the processing unit 244 refers to the distance information defined in the processing unit 241 and the processing result of the vertical detection unit 243, and identifies the position of the signal that is a candidate for the existing object. Then, clustering processing, tracking processing, and the like are performed based on the position information of the signal to specify the position and speed as the object. No warning or control is given if the object is not at a height that makes contact with the vehicle. In addition, if the height is such that they come into contact with each other, warning or control can be performed.

As described above, in the embodiment of the present invention, transmission signals having different directivities in the vertical direction are transmitted, and in the vertical direction (elevation / depression angle direction) based on the intensity ratio of the reflected signals reflected by the object. Since the position of the object is detected, the position of the object in the vertical direction can be detected by a simple configuration.

Further, in the present embodiment, since the position in the vertical direction is specified after detecting the position in the horizontal direction of the object, the vertical position is detected by performing the calibration according to the horizontal direction in the detection of the position in the vertical direction. It is possible to guarantee the positional accuracy of the direction. Further, by detecting the angle in the horizontal direction first and referring to the detection angle in the horizontal direction during the detection process in the vertical direction, the calculation load related to the detection can be reduced.

Further, in the present embodiment, as shown in FIG. 13, the receiving antennas 17-1 to 17-4 and the transmitting antennas 16-1 to 16-2 are arranged side by side in the horizontal direction, so that the resolution is high in the horizontal direction. It is possible to construct a radar device 10 suitable for a vehicle that requires the above.

Next, an example of the processing executed in the embodiment shown in FIG. 1 will be described with reference to FIGS. 24 to 27.

FIG. 24 is an example of a flowchart for explaining the flow of the main processing executed in the embodiment shown in FIG. When the processing of the flowchart shown in FIG. 24 is started, the following steps are executed.

In step S10, the control unit 11 assigns the initial value 1 to the variable k for counting the number of processes.

In step S11, the control unit 11 assigns the initial value 1 to the variable j for counting the number of processes.

In step S12, the control unit 11 assigns the initial value 1 to the variable i for counting the number of processes.

In step S13, the control unit 11 controls the selection unit 15 to select the j-th transmission antenna. The transmitting antenna 16-1 and the transmitting antenna 16-2 are defined as a first transmitting antenna and a second transmitting antenna, respectively. Then, when j = 1, the transmitting antenna 16-1 is selected, and when j = 2, the transmitting antenna 16-2 is selected.

In step S14, the control unit 11 controls the selection unit 18 to select the i-th receiving antenna. It should be noted that each of the receiving antennas 17-1 to 17-4 is defined as the first receiving antenna to the fourth receiving antenna. Then, when i = 1, the receiving antenna 17-1 is used, when i = 2, the receiving antenna 17-2 is used, when i = 3, the receiving antenna 17-3 is used, and when i = 4, the receiving antenna 17-3 is used. The receiving antenna 17-4 is selected.

In step S15, the control unit 11 transmits a pulse. More specifically, the control unit 11 controls the oscillation unit 12 to output a locally generated signal, and supplies a rectangular wave having a width W as shown in FIG. 9C to the pulse shaping unit 13. As a result, the locally generated signal supplied from the oscillation unit 12 is modulated by the signal having the waveform of the pulse P supplied from the pulse shaping unit 13 in the variable amplification unit 14, and the amplitude shown in FIG. 9B is A. Pulse P is generated. Such a pulse P is transmitted from the transmitting antenna selected by the selection unit 15 in step S13.

In step S16, the pulse reception process is executed. The details of the pulse reception process will be described later with reference to FIG. 25.

In step S17, the control unit 11 increments the variable i for counting the number of processes by one.

In step S18, the control unit 11 determines whether or not the value of the variable i is greater than 4, and if it is determined to be greater than 4 (step S18: Y), the process proceeds to step S19, and in other cases. Return to step S14 and repeat the same process. By repeating the processes of steps S14 to S18, the receiving antennas 17-1 to 17-4 are sequentially selected and the receiving process is executed.

In step S19, the control unit 11 increments the variable j for counting the number of processes by one.

In step S20, the control unit 11 determines whether or not the value of the variable j is greater than 2, and if it is determined to be greater than 2 (step S20: Y), proceeds to step S21, and in other cases. Return to step S12 and repeat the same process. By repeating the processes of steps S12 to S20, the transmitting antennas 16-1 to 16-2 are sequentially selected and the transmitting process is executed.

In step S21, the control unit 11 increments the variable k for counting the number of processes by one.

In step S22, the control unit 11 determines whether or not the value of the variable k is larger than n, and if it is determined that the value is larger than n (step S22: Y), the process ends, and in other cases. Return to step S11 and repeat the same process. By repeating the processes of steps S11 to S22, the equivalent time sampling shown in FIG. 22 is executed. In addition, n is the number of repetitions, and is 12,288 in this embodiment. That is, the number of cycles and fields is 2,048 times × 6 fields are the number of repetitions, so the product of these is 12,288.

Next, the details of the pulse reception process shown in FIG. 24 will be described with reference to FIG. 25. When the processing of the flowchart shown in FIG. 25 is started, the following steps are executed.

In step S30, the control unit 11 assigns the initial value 1 to the variable m that counts the number of processes.

In step S31, the reflected signal is received. More specifically, the RF signal received by the receiving antenna selected by the selection unit 18 is amplified by the amplification unit 19 and multiplied by the localizing signal by the multiplication unit 20 to obtain an IF signal, which is an A / D conversion unit. It is supplied to 22.

In step S32, the control unit 11 controls the A / D conversion unit 22 to convert the reflected signal (IF signal) into digital data by A / D conversion.

In step S33, the control unit 11 stores the data output from the A / D conversion unit 22 in the storage unit 23.

In step S34, the control unit 11 increments the variable m for counting the number of processes by one.

In step S35, the control unit 11 determines whether or not the value of the variable m is larger than 5, and if m> 5 is satisfied (step S35: Y), the process proceeds to step S36, and in other cases (step). In S35: N), the process returns to step S32 and the same process as described above is repeated. By the processing of steps S32 to S35, as shown in FIG. 22, sampling is executed five times.

In step S36, the control unit 11 determines whether or not the result of (km mod 6) is 0, and if it is 0 (step S36: Y), the process proceeds to step S37, and in other cases (step S36: Y). In N), the process proceeds to step S38. Note that mod is an operator that finds the remainder of k divided by 6. Here, in k, one cycle shown in FIG. 18 (transmission processing by both transmitting antennas 16-1 to 16-2 and reception processing by all of receiving antennas 17-1 to 17-4 is one cycle) is executed. Is a variable whose value is incremented by 1. In the pulse reception process, in one field, one cycle is executed once to advance to the next field, and when it advances to the sixth field, it returns to the first field and repeats the same process. Therefore, when (km mod 6) becomes 0, the process returns to the first field, and in other cases, the process proceeds to the next field.

In step S37, the control unit 11 returns to the first field. For example, at present, when the processing of the sixth field in FIG. 22 is completed, the process returns to the first field.

In step S38, the control unit 11 shifts to the processing of the next field. For example, at present, when the processing of the first field of FIG. 22 is completed, the process shifts to the second field.

Next, with reference to FIG. 26, the processing executed by the processing unit 241, the horizontal detection unit 242, and the vertical detection unit 243 shown in FIG. 1 will be described. When the processing of the flowchart shown in FIG. 26 is started, the following steps are executed.

In step S50, the processing unit 241 obtains two-dimensional data related to the distance and frequency to the object by performing FFT processing on the data related to the distance and time obtained by the eight antenna systems.

In step S51, the horizontal detection unit 242 acquires data for 8 points for the region where the object exists from the data obtained by the FFT process in step S50, and performs the 8-array angle FFT process. More specifically, zero padding is performed on the data for 8 points to obtain 128 or 256 points of data, and the angle FFT process is executed on these data.

In step S52, the horizontal detection unit 242 executes the peak index detection process on the result obtained by the process of step S51. For example, in the case of the solid line in FIG. 5, i1 (about “65”) is specified as an angle index corresponding to the peak value of the solid line.

In step S53, the horizontal detection unit 242 refers to the horizontal table and specifies the azimuth angle corresponding to the angle index specified in step S52. For example, in the present example, about "-30 degrees" is specified as the azimuth angle corresponding to the angle index "65".

In step S54, the vertical detection unit 243 executes the angle FFT process on the data for 4 points corresponding to the transmitting antenna 16-1 among the data obtained by the process in step S50. More specifically, zero padding is performed on the data for 4 points to obtain 128 or 256 points of data, and the angle FFT process is executed on these data.

In step S55, the vertical detection unit 243 executes the angle FFT process on the data for 4 points corresponding to the transmitting antenna 16-2 among the data obtained by the process in step S50. More specifically, zero padding is performed on the data for 4 points to obtain 128 or 256 points of data, and the angle FFT process is executed on these data.

In step S56, the vertical detection unit 243 corresponds to the amplitude value of the FFT processing result corresponding to the transmitting antenna 16-1 and the transmitting antenna 16-2 at the angle index corresponding to the peak value specified in step S52. The intensity ratio of the FFT processing result is calculated. For example, in the example of FIG. 5, the ratio of the amplitude value at the angle index i1 of the FFT processing result corresponding to the transmitting antenna 16-1 and the amplitude value at the angle index i1 of the FFT processing result corresponding to the transmitting antenna 16-2 is set. calculate. As a result, about "-6" dB is specified as the amplitude ratio.

In step S57, the vertical detection unit 243 acquires information indicating the relationship between the intensity ratio and the elevation / depression angle at the angle acquired in step S53 from the table group 243a. For example, in the present example, since the angle specified in step S53 is −30 degrees, a polygonal line indicated by a broken line having a short interval between the thin lines in FIG. 8 is acquired.

In step S58, the vertical detection unit 243 identifies the elevation / depression angle based on the information indicating the relationship between the intensity ratio and the elevation / depression angle acquired in step S57. For example, in the present example, about “-7” degrees is specified as the elevation / depression angle corresponding to the amplitude ratio “-6” dB specified in step S56 in the polygonal line indicated by the broken line with a short interval between the thin lines in FIG. ..

In step S59, the vertical detection unit 243 outputs the elevation / depression angle specified in step S58 to the processing unit 244.

Next, an example of the processing executed by the processing unit 244 shown in FIG. 1 will be described with reference to FIG. 27. When the process shown in FIG. 27 is started, the following steps are executed.

In step S90, the processing unit 241 acquires the signal information defined by the distance and the frequency. The primary detection of the object is performed by the amplitude information.

In step S91, the processing unit 244 acquires the processing result of the horizontal detection unit 242. More specifically, the processing unit 244 acquires information (azimuth) indicating the horizontal angle of the object from the horizontal detection unit 242. In addition, secondary detection of the object is performed based on the amplitude information.

In step S92, the processing unit 244 acquires the processing result from the vertical detection unit 243. More specifically, the processing unit 244 acquires information (elevation / depression angle) indicating the vertical angle of the object from the vertical detection unit 243.

In step S93, the processing unit 244 positions the signal detected from the sensor or the own vehicle from the distance information in the processing unit 241, the azimuth angle information from the horizontal detection unit 242, and the elevation / depression angle information from the vertical detection unit 243. To identify.

In step S94, the processing unit 244 performs clustering processing, tracking processing, and the like based on the position information of the signal detected in step S93, and identifies the position and speed of the object.

In step S95, the processing unit 244 determines whether the position and speed of the object specified in step S94 is a safe object with no possibility of collision within a predetermined time, and determines that it is safe (step). The process ends in S95: Y), and if there is a possibility of a collision other than that (step S95: N), the process proceeds to step S96.

In step S96, the processing unit 244 executes a process of issuing a warning to the driver because there is a risk of collision (or contact) with the object. Alternatively, the ECU, which is a higher-level device, performs the above processing or vehicle control based on the position and speed information of the object in the processing unit 244. As a result, the ECU may notify that there is a possibility of collision by a warning sound or the like, or the ECU may operate the brake to stop the vehicle.

According to the above processing, the above-mentioned operation can be realized.

(C) Description of Modified Embodiment The above embodiment is an example, and it goes without saying that the present invention is not limited to the cases described above. For example, in the above embodiment, as shown in FIG. 22, the pulse P has 6 fields and each field is sampled 5 times. However, the pulse P has a number of fields other than this, and this It may be the number of sampling times other than.

Further, in the example of FIG. 2, both the objects O1 and O2 are in a state of being grounded to the ground, but as shown in FIG. 28, for example, the object O3 not to be grounded (for example, a pole arranged in the air). Etc.) can also be detected. In the case of such an object O3, the first reflected signal with respect to the transmitted signal having the first directivity is generally equal to or larger than the intensity of the second reflected signal with respect to the transmitted signal having the second directivity (first reflected signal). ≧ 2nd reflected signal). In the case of such an object O3, if it is determined as a result of the elevation / depression angle detection that there is a possibility of collision when the object is assumed to be in a predetermined height range, the object O3 shown in FIG. Collisions can also be avoided. Further, O4 (for example, a bridge girder existing above) can be a non-detection target. In the case of such an object O4, the first reflected signal for the transmitted signal having the first directivity characteristic is larger than the intensity of the second reflected signal for the transmitted signal having the second directivity characteristic (first reflected signal> second). Reflected signal). In such a case, if the object is assumed to be above a predetermined height range as a result of the elevation / depression angle detection, there is no possibility of collision, and it is not necessary to reflect it in the warning or control. In this way, the risk of erroneous detection can be reduced.

Further, in the above embodiment, two types of electromagnetic waves having different directivity in the vertical direction are transmitted from the two transmitting antennas 16-1 to 16-2, but the directivity in the vertical direction is transmitted from three or more transmitting antennas. Three or more types of electromagnetic waves having different characteristics may be transmitted.

Further, in the above embodiment, electromagnetic waves having different directivity in the vertical direction are transmitted by the transmitting antennas 16-1 to 16-2 having different two characteristics. For example, a transmitting antenna whose characteristics can be changed is used. , A plurality of electromagnetic waves having different directivity characteristics in the vertical direction may be transmitted by changing the characteristics each time the transmission is performed.

Further, in the above embodiment, the number of transmitting antennas 16-1 to 16-2 is two, and the number of receiving antennas 17-1 to 17-4 is four 2 × 4, but other n × m The configuration may be (n, m> 1).

Further, in the above embodiment, the pulse repetition cycle T0 shown in FIG. 9 is fixed, but for example, by changing the repetition cycle T0 for each sampling, a reflection signal for the pulse transmitted in the immediately preceding repetition cycle is obtained. It may be possible to prevent false detection due to.

Further, in the above embodiment, the object is detected based on the pulse method, but the present invention may be applied to, for example, an FMCW (Frequency Modulated Continuous Wave) type radar device. Further, it may be a real signal instead of a complex signal.

Further, in the above embodiment, the directivity of the transmitting antennas 16-1 to 16-2 is changed by adjusting the length of the feeder line, but in addition to this, the shape of the patch antenna is changed. You may try to do it. Further, the element antenna is not limited to the patch shape as shown in the figure. Further, both the transmitting antenna and the receiving antenna are not limited to the power feeding branched from the center as illustrated, and the feeding antenna may be fed in series from the end to the element antenna. Further, it is not limited to the one-row power supply configuration as shown in FIGS. 15 and 18.

Further, in the above embodiment, the height is specified based on the ratio of the electric power of the reflected signal from the object, but for example, the height is specified based on the difference in the electric power of the reflected signal. May be good. Further, it may be an amplitude dimension instead of a power dimension, or an approximate value instead of an exact value.

Further, in the example of FIG. 1, the horizontal detection unit 242 and the vertical detection unit 243 are connected in series, but as shown in FIG. 29, the horizontal detection unit 242 and the vertical detection unit 243 are connected in parallel. You may try to connect. According to such a configuration, for example, the 8-array angle FFT process (P10) and the 4-array angle FFT process (P20, P21) in FIG. 23 are processed in parallel to reduce the time required for the processing. be able to. Although a simple and high-speed FFT process is illustrated as the Fourier transform, DFT (Discrete Fourier Transform) process or the like or high resolution process may be used.

Further, in the above embodiment, a detection process is performed in which comparison is performed using some threshold value, and only data having a sufficient amplitude among all signals is narrowed down as a candidate signal for an object at an appropriate stage. As illustrated, the determination process of the object is not limited to these, and it is possible to insert it at any stage.

Further, in the above embodiment, the motorcycle has been described as an example of the vehicle, but other than this, a motorcycle, a bicycle, or the like may be detected. That is, in the present specification, the vehicle is not limited to the motorcycle.

Further, in the above embodiment, the case where the radar device is mounted at the rear of the vehicle has been described as an example, but the radar device may be mounted at the front.

Further, in the above embodiment, a plurality of transmission signals having different directivity in the vertical direction are transmitted at different timings, and the position of the object in the vertical direction is detected based on the difference in the received power. Even if a plurality of transmission signals having different directivity are transmitted in a predetermined direction other than the predetermined direction (for example, a horizontal direction) at different timings and the position of the object in the predetermined direction is detected based on the difference in the received power. Good.

Further, it goes without saying that the processing of the flowcharts shown in FIGS. 24 to 27 is an example, and the present invention is not limited to the processing of these flowcharts.

10 Radar device 11 Control unit 12 Oscillator unit 13 Pulse shaping unit 14 Variable amplification unit 15 Selection unit 16-1 to 16-2 Transmission antenna 17-1 to 17-4 Reception antenna 18 Selection unit 19 Amplification unit 20 Multiplication unit 21 IF amplification Unit 22 A / D conversion unit 23 Storage unit 24 Calculation unit 241 Processing unit 242 Horizontal detection unit 243 Vertical detection unit 243a Table 244 Processing unit

Claims (8)

In a radar device that detects an object
Multiple receiving antennas arranged in a row in the first direction,
At least two transmitting antennas having different directivities in the second direction, which is substantially orthogonal to the first direction,
With respect to the first direction, a first angle detecting means for detecting a first angle which is an angle at which the object exists, and
A second angle detecting means for detecting a second angle, which is an angle at which the object exists, in the second direction based on the intensity ratio of the received signal transmitted from each of the transmitting antennas and received by the receiving antenna. When,
It has a storage means for storing a plurality of tables showing the relationship between the intensity ratio and the second angle according to each of the first angles that can be detected by the first angle detecting means.
The second angle detecting means detects the second angle with reference to the table corresponding to the first angle detected by the first angle detecting means.
A radar device characterized by that. The first angle detecting means detects the first angle of the object based on the angle spectrum of the received signal acquired by the Fourier transform.
The radar device according to claim 1. The first angle detecting means detects the first angle based on all the received signals that are sequentially transmitted from each of the transmitting antennas and received by the receiving antenna.
The second angle detecting means sequentially transmits from each of the transmitting antennas and detects the second angle based on each of the received signals received by the receiving antenna.
The radar device according to claim 1 or 2. The first angle detecting means sequentially transmits from each of the transmitting antennas, executes a process of obtaining an angle for all the received signals received by the receiving antenna, and is based on a position at which a peak of the processing result is obtained. The first angle is detected,
The second angle detecting means sequentially transmits from each of the transmitting antennas, executes a Fourier transform process for obtaining an angle with respect to each of the received signals received by the receiving antenna, and detects by the first angle detecting means. The intensity ratio at the first angle corresponding to the peak position is detected.
The radar device according to claim 3, wherein the radar device is characterized. The first direction is a substantially horizontal direction.
The radar device according to any one of claims 1 to 4, wherein the radar device is mounted on a vehicle. The transmitting antenna and the receiving antenna are each composed of a plurality of element antennas, and the number of the element antennas constituting one transmitting antenna is smaller than the number of the element antennas constituting one receiving antenna.
The radar device according to claim 5. The receiving antenna has a plurality of element antennas adjacent to each other, including the element antenna closest to the transmitting antenna.
The power supplied to the element antenna closest to the transmitting antenna is less than or equal to the power supplied to the other plurality of element antennas.
The radar device according to claim 6, wherein the radar device is characterized. In the object detection method of a radar device having a plurality of receiving antennas arranged in a row in the first direction and at least two transmitting antennas having different directivity characteristics in the second direction substantially orthogonal to the first direction.
A first angle detection step for detecting a first angle, which is an angle at which the object exists, in the first direction.
A second angle detection step of detecting a second angle, which is an angle at which the object exists, in the second direction based on the intensity ratio of the received signal transmitted from each of the transmitting antennas and received by the receiving antenna. When,
It has a storage step for storing a plurality of tables showing the relationship between the intensity ratio and the second angle according to each of the first angles that can be detected in the first angle detection step.
The second angle detection step detects the second angle with reference to the table corresponding to the first angle detected in the first angle detection step.
An object detection method for a radar device, characterized in that.

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