JP2018004513A - Radar device and angle detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an arrival angle of a plurality of reflection waves without relying upon the number of pieces of arrival angles.SOLUTION: A radar device according to one embodiment of the present invention comprises an angle estimation unit, an adjustment unit, and a determination unit. The angle estimation unit is configured to estimate an arrival angle in a first direction of a plurality of reflection waves and an arrival angle in a second direction different from the first direction, respectively, on the basis of a reception signal with at least one reflection wave arrived by which transmission signal is reflected upon at least one target received via a plurality of antennas. The adjustment unit is configured to, when the number of pieces of arrival angles in the first direction estimated by the angle estimation unit are different from the number of pieces of arrival angles in the second direction, adjust the number of pieces of arrival angles so that the number of pieces of arrival angles agree with each other in the first direction and the second direction. The determination unit is configured to determine a combination of the arrival angle in the first direction and the arrival angle in the second direction on the basis of the number of pieces of arrival angles adjusted by the adjustment unit.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a radar apparatus and an angle detection method.

  2. Description of the Related Art Conventionally, a radar device that detects a distance to a plurality of targets and an arrival angle of the reflected waves by receiving a plurality of reflected waves reflected by a plurality of targets respectively is known. In such a radar device, the arrival angles of the plurality of reflected waves in the vertical direction and the arrival angles of the plurality of reflected waves in the horizontal direction are combined to detect the horizontal direction and the vertical direction arrival angles of the plurality of reflected waves. (For example, refer to Patent Document 1).

JP-A-11-287857

  However, in the above-described radar apparatus, it is assumed that the number of arrival angles in the vertical direction is the same as the number of arrival angles in the horizontal direction, and the case where the numbers are different is not considered. When actually detecting the distance to the target and the arrival angle of the reflected wave using the radar device, the number of arrival angles may be different in the vertical direction and the horizontal direction due to the influence of noise or the like. Thus, it is desirable to detect the arrival angles of a plurality of reflected waves even when the number of arrival angles is different.

  The present invention has been made in view of the above, and an object of the present invention is to provide a radar apparatus and an angle detection method capable of detecting the arrival angles of a plurality of reflected waves regardless of the number of arrival angles.

  In order to solve the above problems and achieve the object, the radar apparatus of the present invention includes an angle estimation unit, an adjustment unit, and a determination unit. The angle estimation unit is configured to receive arrival angles of the plurality of reflected waves in the first direction based on reception signals obtained by receiving at least one reflected wave reflected from at least one target via the plurality of antennas. And an arrival angle in a second direction different from the first direction is estimated. When the number of the arrival angles in the first direction estimated by the angle estimation unit is different from the number of the arrival angles in the second direction, the adjustment unit is configured such that the number of arrival angles is the first direction and The number is adjusted to match in the second direction. The determination unit determines a combination of the arrival angle in the first direction and the arrival angle in the second direction based on the number of arrival angles adjusted by the adjustment unit.

  ADVANTAGE OF THE INVENTION According to this invention, the radar apparatus and angle detection method which can detect the arrival angle of several reflected waves irrespective of the number of arrival angles can be provided.

FIG. 1A is an explanatory diagram illustrating an angle detection method according to the embodiment. FIG. 1B is a diagram illustrating a combination example of arrival angles. FIG. 2 is a diagram illustrating the radar device according to the embodiment. FIG. 3 is a schematic diagram for explaining a transmission signal and a reflected wave. FIG. 4 is a flowchart illustrating a procedure of angle detection processing executed by the radar apparatus according to the embodiment. FIG. 5 is a diagram illustrating a configuration of a radar apparatus according to a modification of the embodiment. FIG. 6 is a flowchart illustrating a procedure of angle detection processing executed by the radar apparatus according to the modification of the embodiment.

  Hereinafter, embodiments of a radar apparatus and an angle detection method disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

<Angle detection method>
An angle detection method according to an embodiment of the present invention will be described with reference to FIG. 1A. FIG. 1A is an explanatory diagram illustrating an angle detection method according to the present embodiment. The angle detection method according to the present embodiment is executed by a radar apparatus. This embodiment demonstrates the case where a radar apparatus is mounted, for example in a motor vehicle, and is used as a vehicle detection apparatus which detects the preceding vehicle of the said motor vehicle as a target.

  The radar apparatus according to the present embodiment includes a plurality of reception antennas Rx that receive reflected waves of transmission signals transmitted from transmission antennas reflected on a plurality of targets.

  First, the radar apparatus, based on a plurality of reflected waves, has an arrival angle θ in the horizontal direction (hereinafter referred to as horizontal angle θ) and an arrival angle φ in the vertical direction (hereinafter referred to as vertical angle φ). Is estimated (step S1). For example, the horizontal direction refers to a direction horizontal to the road surface, and the vertical direction refers to a direction perpendicular to the road surface.

  The radar apparatus estimates the horizontal angle θ using, for example, a plurality of reception antennas Rx1h to Rx5h arranged in the horizontal direction among the plurality of reception antennas Rx. Further, the radar apparatus estimates the vertical angle φ using a plurality of receiving antennas Rx1v to Rx3v arranged in the vertical direction. The radar apparatus estimates the horizontal angle θ and the vertical angle φ by using, for example, ESPRIT (Estimation of Signal Parameters via Rotation Invariance Techniques) method with respect to the reflected waves received via the plurality of receiving antennas Rx.

  As described above, when the radar apparatus performs estimation using ESPRIT, a plurality of targets having different angles existing at the same frequency can be detected. For example, the radar apparatus can estimate up to four targets at different angles existing at the same frequency by using a plurality of receiving antennas Rx1h to Rx5h arranged in the horizontal direction. Further, the radar apparatus can estimate up to two targets at different angles existing at the same frequency by using a plurality of receiving antenna antennas Rx1v to Rx3v arranged in the vertical direction. Here, the target is information corresponding to the position of a reflection point at which the transmission wave output from the radar apparatus is reflected by the object. In this way, in the estimation method using ESPRIT, the number of receiving antennas minus one angle can be detected as the maximum number.

  Here, it is assumed that the radar apparatus estimates three horizontal angles θ1 to θ3 and estimates two vertical angles φ1 and φ2, for example.

  In this case, the radar apparatus detects the arrival angles of the plurality of reflected waves by determining a combination of the horizontal angle θ and the vertical angle φ estimated for each target. That is, since the horizontal angle and the vertical angle are determined on a one-to-one basis for each target, the correct horizontal angle θ and vertical angle φ for each target are selected from the plurality of horizontal angles θ1 to θ3 and the plurality of vertical angles φ1 and φ2. Determine the combination.

  For example, as shown in FIG. 1B, there are six possible combinations for the horizontal angle θ and the vertical angle φ estimated by the radar apparatus. The radar apparatus detects the arrival angles of the reflected waves in the horizontal direction and the vertical direction by determining at least two correct combinations among the six combinations shown in FIG. 1B. For example, the vertical angle corresponding to the target with the horizontal angle θ1 is φ1 (a combination indicated by “1” circled in FIG. 1B), and the vertical angle corresponding to the target with the horizontal angle θ2 is φ2 (in FIG. 1B). A combination indicated by a circled “5”). FIG. 1B is a diagram illustrating an example of combinations of arrival angles.

  The radar apparatus adjusts the number of horizontal angles θ or vertical angles φ (step S2). The radar apparatus determines the correspondence of the arrival angles so as to match the smaller number of the horizontal angle θ and the vertical angle φ. For example, the radar apparatus adjusts the number of horizontal angles so that it matches the number of vertical angles that are smaller than the horizontal angle θ. Specifically, the radar apparatus performs association so that a combination of both the horizontal angle θ and the vertical angle φ forms a square matrix.

  Specifically, in the example illustrated in FIG. 1B, the radar apparatus adjusts the number of horizontal angles θ according to the number of angles 2 of the small vertical angle φ. As illustrated in FIG. 1B, the radar apparatus generates a group R1 that forms a square matrix with horizontal angles θ1 and θ2 and vertical angles φ1 and φ2, for example. In addition, the radar apparatus generates a group R2 that forms a square matrix with horizontal angles θ2 and θ3 and vertical angles φ1 and φ2, for example. As described above, the radar apparatus sets the groups R1 and R2 so that the number of angles is equal, in other words, a square matrix, so that the number of horizontal angles θ and the number of vertical angles φ are the same. Adjust to the number.

  The radar apparatus determines a combination of the horizontal angle θ and the vertical angle φ based on the adjusted horizontal angle θ and vertical angle φ (step S3). For example, the radar apparatus performs a correlation calculation regarding the power of the reflected wave described later in each of the groups R1 and R2. That is, the radar apparatus calculates the power of the reflected wave using information regarding the horizontal angles θ1 and θ2 and the vertical angles φ1 and φ2, and performs a correlation operation based on the power of the reflected wave. Further, the radar apparatus calculates the power of the reflected wave using information on the horizontal angles θ2 and θ3 and the vertical angles φ1 and φ2, and performs a correlation operation based on the power of the reflected wave. The radar apparatus determines the combination of the horizontal angle and the vertical angle based on the correlation of the power of the reflected wave from the target. Specifically, the radar apparatus determines the combination having the highest correlation between the power of the reflected wave related to the horizontal angle and the power of the reflected wave related to the vertical angle as the correct combination.

  As described above, even if the number of horizontal angles θ and the number of vertical angles φ are different, the radar apparatus adjusts the number of each angle so that the number of horizontal angles θ and the number of vertical angles φ match. By doing so, the combination of the horizontal angle θ and the vertical angle φ can be determined. Thereby, the radar apparatus can detect the arrival angle of the reflected wave even when the number of horizontal angles θ and the number of vertical angles φ are different.

  Although the radar apparatus estimates the horizontal angle and the vertical angle here, the present invention is not limited to this. For example, the radar apparatus may estimate the arrival angle in the first direction and the arrival angle in the second direction different from the first direction, and the first direction and the second direction do not necessarily have to be orthogonal. Hereinafter, a radar apparatus that executes such an angle detection method will be further described.

<Radar device 1>
FIG. 2 is a diagram showing the radar apparatus 1 according to the embodiment of the present invention. The radar device 1 includes a signal processing device 10, a transmission unit 20, and a reception unit 30.

  The transmission unit 20 includes a signal generation unit 21, an oscillator 22, and a transmission antenna Tx. The signal generation unit 15 is controlled by the signal processing device 10. The signal generator 21 supplies, for example, a triangular wave modulation signal to the oscillator 22. The oscillator 22 generates a transmission signal having a predetermined frequency in accordance with the modulation signal generated by the signal generation unit 21. The transmission signal is transmitted via the transmission antenna Tx. As described above, the transmission unit 20 transmits the transmission signal subjected to frequency modulation according to the signal processing device 10.

  In the present embodiment, the radar apparatus 1 detects a target using, for example, an FM-CW (Frequency-Modulated Continuous Wave) method. Therefore, the oscillator 22 generates a transmission signal that changes at a constant repetition period according to the triangular wave-shaped modulation signal generated by the signal generation unit 21. The transmission unit 20 may include an amplifier (not shown), and the transmission signal generated by the oscillator 22 may be amplified by the amplifier and transmitted.

  The radar apparatus 1 according to the present embodiment is mounted on a vehicle, for example. For example, the radar device 1 transmits a transmission wave toward the front or rear of the vehicle. A transmission wave transmitted from the transmission antenna Tx is reflected by a target such as a preceding vehicle, a rear vehicle, or a stationary object. The reflected wave reflected by the target returns toward the vehicle and is received by the receiving unit 30 of the radar apparatus 1.

  The reception unit 30 includes a plurality of reception antennas Rx and a plurality of reception processing units 40 corresponding to the reception antennas Rx.

  The plurality of reception antennas Rx receive a plurality of reflected waves that arrive when the transmission signal is reflected by a plurality of targets. The plurality of receiving antennas Rx include horizontal antennas Rx1h to Rx5h (hereinafter collectively referred to as horizontal antennas Rxh) arranged in the horizontal direction and vertical antennas Rx1v to Rx3v (hereinafter collectively referred to as vertical antennas) arranged in the vertical direction. Rxv). The horizontal antennas Rxh are arranged at equal intervals for each predetermined interval d. Further, the vertical antennas Rxv are arranged at equal intervals for each predetermined interval d.

  The plurality of reception processing units 40 include horizontal receiving units 410h to 450h corresponding to the horizontal antennas Rxh and vertical receiving units 410v to 430v corresponding to the vertical antennas Rxv. Although the horizontal receiving units 410h to 450h and the vertical receiving units 410v to 430v are different in the arrangement of antenna elements that receive reflected waves, the configuration of the antenna elements and the processing after receiving the reflected waves are basically the same. Therefore, the horizontal receiving unit 410h will be described as an example.

  The horizontal reception unit 410h includes a mixer 411h and an A / D conversion unit 412h. The mixer 411h mixes the reflected wave received via the horizontal antenna Rx1h and the transmission signal, and generates a beat signal. The bead signal has a frequency difference between the frequency of the transmission signal and the frequency of the reflected wave. The A / D conversion unit 412h performs A / D conversion processing on the beat signal generated by the mixer 411h to generate a reception signal that is a digital signal. The A / D conversion unit 412h outputs the generated reception signal to the signal processing device 10.

  In addition, although the case where the horizontal receiving part 410h is provided with the mixer 411h and the A / D conversion part 412h was demonstrated here, it is not limited to this. For example, the horizontal receiving unit 410h may include an amplifier or a filter (not shown).

  The signal processing device 10 is a microcomputer including a CPU (Central Processing Unit), a storage unit (not shown), and the like, and controls the entire radar device 1. The signal processing device 10 is implemented by software using a microcomputer, and includes a transmission control unit 110, a horizontal FFT processing unit 120, a vertical FFT processing unit 130, an angle estimation unit 140, and an adjustment unit 150. Unit 160.

  The transmission control unit 110 controls the transmission unit 20 to transmit a transmission signal corresponding to the triangular wave-like modulation signal. The horizontal FFT processing unit 120 performs FFT processing on each reception signal received via the horizontal antenna Rxh, and generates a frequency domain reception signal for each horizontal antenna Rxh. More specifically, since the peak signal appears at the frequency position corresponding to the distance of each target by the FFT processing, the horizontal FFT processing unit 120 extracts the peak signal for each of the horizontal antennas Rx1h to Rx5h by the FFT processing and receives the frequency domain. Generate as a signal.

  Also, the vertical FFT processing unit 130 performs FFT processing on each received signal received via the vertical antenna Rxv, and generates a frequency domain received signal for each vertical antenna Rxv. More specifically, the vertical FFT processing unit 130 extracts a peak signal for each of the horizontal antennas Rx1v to Rx3v by FFT processing and generates a received signal in the frequency domain. The horizontal FFT processing unit 120 and the vertical FFT processing unit 130 output the frequency domain received signal to the angle estimation unit 140.

  The angle estimation unit 140 estimates the horizontal angle θ and the vertical angle φ of each reflected wave based on the plurality of reflected waves received by the plurality of receiving antennas Rx. The angle estimation unit 140 includes a horizontal angle estimation unit 141 and a vertical angle estimation unit 142.

  The horizontal angle estimation unit 141 estimates a horizontal angle for each peak signal based on a plurality of reflected waves received via the horizontal antenna Rxh. Here, a plurality of horizontal angles θ1 to θ3 in a certain peak signal are estimated. More specifically, since each peak signal obtained by the horizontal FFT processing unit 120 may have a plurality of targets having the same distance but different horizontal angles, the FFT processing result of the horizontal FFT processing unit 120 Then, a plurality of peak signals are obtained at frequency positions corresponding to the distances between the targets. Therefore, the horizontal angle estimation unit 141 estimates the horizontal angle for each peak signal exceeding a predetermined level.

  The vertical angle estimation unit 142 estimates a plurality of vertical angles φ1 and φ2 based on a plurality of reflected waves received via the vertical antenna Rxv. The horizontal angle estimation unit 141 and the vertical angle estimation unit 142 estimate the horizontal angle θ and the vertical angle φ from a plurality of reflected waves based on, for example, the ESPRIT method and the MUSIC (Multiple Signal Classification) method. The horizontal angle estimation unit 141 and the vertical angle estimation unit 142 output the estimated horizontal angle θ and vertical angle φ to the adjustment unit 150.

  Note that the number of horizontal angles θ and vertical angles φ estimated by the angle estimation unit 140 may be at least one, and is not limited to the above-described example.

  When the number of horizontal angles θ and the number of vertical angles φ are different, the adjustment unit 150 adjusts the number of each angle so that the number matches the horizontal angle θ and the vertical angle φ. For example, the adjusting unit 150 adjusts the number of angles so that the same number as the smaller number of angles is obtained.

  When the number of one of the horizontal angle θ and the vertical angle φ is greater than the number of the other, the adjustment unit 150 selects the same number of angles as the number of the other from the one. Here, a case where the number of horizontal angles θ = {θ1, θ2, θ3} is three and the number of vertical angles φ = {φ1, φ2} is two will be described.

  In this case, the adjustment unit 150 selects two angles that are the same as the number of the vertical angles φ from the horizontal angle θ. Specifically, the adjustment unit 150 selects, for example, the group R1 of the horizontal angles θ1 and θ2 and the vertical angles φ1 and φ2 as a candidate T1 that is one candidate for the correspondence between the horizontal angle θ and the vertical angle φ, and the horizontal angle The group R2 of θ2, θ3 and the vertical angles φ1, φ2 is selected as a candidate T2, which is another candidate for the correspondence between the horizontal angle and the vertical angle. When each candidate T1, T2 is expressed in a matrix format, it can be expressed as the following equation (1).

  The adjustment unit 150 outputs the selected candidates T1 and T2 to the determination unit 160. As described above, the adjustment unit 150 selects the candidates T1 and T2, so that each angle can be represented by a square matrix even when the numbers of the horizontal angle θ and the vertical angle φ are different.

  The determination unit 160 determines a combination of the horizontal angle θ and the vertical angle φ based on the candidates T1 and T2 selected by the adjustment unit 150. The determination unit 160 includes an estimation unit 161, a calculation unit 162, and a combination determination unit 163.

  The estimation unit 161 estimates the reflected wave reflected by the target based on the horizontal angle θ = {θ1, θ2} and the vertical angle φ = {φ1, φ2} included in the candidate T1. The estimation unit 161 includes a first reflection estimation unit 161a and a second reflection estimation unit 161b.

  The first reflection estimation unit 161a estimates the power of the reflected wave reflected by a plurality of targets based on information (for example, a mode matrix described later) regarding the horizontal angle θ = {θ1, θ2}. The second reflection estimation unit 161b estimates information about the vertical angle φ = {φ1, φ2} (for example, the power of the reflected wave reflected by a plurality of targets based on the mode matrix. First and second reflection estimation units The estimation of the power of the reflected wave by 161a and 161b is the same except that either the horizontal angle θ or the vertical angle φ is used, so that the second reflection estimation unit 161b here uses the vertical angle φ = {φ1, φ2 }, The case where the power of the reflected wave is estimated will be described.

  First, transmission signals and reflected waves will be described with reference to FIG. FIG. 3 is a schematic diagram for explaining a transmission signal and a reflected wave. As shown in FIG. 3, the transmission signal ST transmitted from the transmission antenna Tx is reflected by the targets A1 and A2 to become reflected waves RW1 and RW2. The reflected wave RW1 is received by the plurality of vertical antennas Rxv as reflected signals SR11 to SR13, respectively. The reflected wave RW2 is received as reflected signals SR21 to SR23 by the plurality of vertical antennas Rxv, respectively. Therefore, the vertical antenna Rxv is a signal in which the reflected signals SR11 to SR13 and SR21 to SR23 are superimposed for each vertical antenna Rxv. The signals are received as received signals R1 to R3, respectively.

  Here, in order to make the explanation easy to understand, a mode vector a (φ1) is obtained by arranging ideal signals of the vertical antennas Rxv of an amplitude 1 signal from the vertical angle φ1. Then, it is considered that the reference of the equal moving surface at the predetermined time is the vertical antenna Rx1v. At this time, the phases of the reflected signals SR2 and SR3 are expressed as shown in equations (2) and (3) according to the arrangement interval d of the vertical antennas Rxv.

  Therefore, when the mode vector a (φ1) at this time is expressed as a mode matrix, it is expressed as shown in Expression (4). Similarly, when the mode vector a (φ2) is expressed as a mode matrix, it is expressed as shown in Expression (5).

  Note that λ is the wavelength of the reflected wave RW.

Further, at this time, assuming that the power of the reflected wave at every two angles is RW_φ, the power RW_φ = {RW_φ1, RW_φ2} ^T of the reflected wave can be estimated using the equation (6). One of RW_φ1 and RW_φ2 is the power of the reflected wave corresponding to the reflected wave RW1, and the other is the power of the reflected wave corresponding to RW2.

A is a mode matrix calculated based on the results of the equations (4) and (5), and A = {a (φ1), a (φ2)} ^T. R is a matrix of received signals at each vertical antenna Rxv, and R = {R1, R2, R3} ^T. T represents a transposed matrix, and H represents an adjoint matrix.

  As described above, the second reflection estimation unit 161b estimates the power RW_φ1 and RW_φ2 of the reflected wave in the vertical direction using the information regarding the vertical angle φ = {φ1, φ2}. Similarly, the first reflection estimation unit 161a estimates the power RW_θ1 and RW_θ2 of the reflected wave in the horizontal direction using information regarding the horizontal angle θ = {θ1, θ2}. Note that one of RW_θ1 and RW_θ2 is the power of the reflected wave corresponding to the reflected wave RW1, and the other is the power of the reflected wave corresponding to the reflected wave RW2.

  The first and second reflection estimation units 161a and 161b output the estimated reflected wave power RW_θ = {RW_θ1, RW_θ2}, RW_φ = {RW_φ1, RW_φ2} to the calculation unit 162.

  The second reflection estimation unit 161b estimates the power of the reflected waves RW1 and RW2 using all the vertical antennas Rxv, but is not limited to this. The first and second reflection estimation units 161a and 161b may estimate the powers of the reflected waves RW1 and RW2 using some reception antennas Rx. For example, the power of the reflected waves RW1 and RW2 may be estimated using the reception signals SR11 to SR13 received by the three horizontal antennas Rxh among the five horizontal antennas Rxh by the first reflection estimation unit 161a. Thus, by reducing the number of receiving antennas Rx used for estimation, the amount of calculation of reflected wave estimation can be reduced, and the processing speed can be increased.

  The computing unit 162 performs correlation computation based on the power of the reflected waves RW1 and RW2 at the horizontal angle θ and the vertical angle φ, respectively. The computing unit 162 includes a first computing unit 162a and a second computing unit 162b.

  The first calculation unit 162a performs correlation calculation of the power of the reflected wave RW estimated by either the first reflection estimation unit 161a or the second reflection estimation unit 161b, and generates a correlation matrix Am1. Here, the correlation calculation of the power RW_θ of the reflected wave estimated by the first reflection estimation unit 161a is performed.

  As described above, the first calculation unit 162a performs a correlation calculation of the power of the reflected wave RW corresponding to the horizontal angle θ estimated based on the received signal received by the horizontal antenna Rxh having a large number, for example. Thereby, the 1st calculating part 162a can detect an arrival angle with higher precision by performing the correlation calculation of the power of the reflected wave RW estimated with higher precision. This is because the angle estimation unit 140 can estimate the arrival angle with higher accuracy as the number of reception antennas Rx increases.

  The second calculator 162b performs a cross-correlation calculation of the reflected wave powers RW_θ and RW_φ estimated by the first and second reflection estimators 161a and 161b to generate a cross-correlation matrix Cm1. The first and second calculation units 162a and 162b output the calculation results to the combination determination unit 163.

  In the example described above, the estimation unit 161 estimates the power of the reflected wave RW based on the candidate T1, and the calculation unit 162 performs correlation calculation. Similarly, the estimation unit 161 is based on the candidate T2. Then, the power of the reflected wave RW is estimated, and the calculation unit 162 performs correlation calculation to generate the correlation matrix Am2 and the cross-correlation matrix Cm2.

  In the above processing, the radar apparatus 1 generates a plurality of groups (for example, two groups R1 and R2) so as to form a square matrix in accordance with the smaller number of horizontal angles θ and the smaller number of vertical angles φ. In the above example, since the horizontal angle is three of θ1 to θ3 and the vertical angles are two of φ1 and φ2, the radar apparatus 1 generates two groups R1 and R2 so as to form a 2 × 2 square matrix. To do. The radar apparatus 1 generates a cross-correlation matrix of reflected wave power as described above for each of the groups R1 and R2.

  The combination determination unit 163 detects the arrival directions of the reflected waves RW1 and RW2 by determining the combination of the horizontal angle θ and the vertical angle φ based on the calculation results of the first and second calculation units 162a and 162b.

  Here, in order to simplify the explanation, it is assumed that the horizontal angle θ1 and the vertical angle φ1 are the arrival angles of the reflected wave RW1, and the horizontal angle θ2 and the vertical angle φ2 are the arrival angles of the reflected wave RW2.

  In this case, the power RW_θ1 of the reflected wave estimated based on the information about the horizontal angle θ1 and the power RW_φ1 of the reflected wave estimated based on the information about the vertical angle φ1 are the power of the reflected wave RW1 from the same target. As a result, the correlation is high. Moreover, since the power RW_θ2 of the reflected wave estimated based on the information about the horizontal angle θ2 and the power RW_φ2 of the reflected wave estimated based on the information about the vertical angle φ2 are the power of the reflected wave RW2 from the same target, The correlation is high with almost the same power. The reflected wave power RW_θ3 estimated based on the information related to the horizontal angle θ3 is, for example, the power of a signal corresponding to noise, and is different from the power of the reflected waves RW1 and RW2 reflected by the transmission signal.

  Therefore, the correlation coefficient of RW_θ1 in the correlation matrix Am1 and the correlation coefficient of RW_θ1 and RW_φ1 in the cross-correlation matrix Cm1 are close to each other and large values. Similarly, the correlation coefficient of RW_θ2 and the correlation coefficient of RW_θ2 and RW_φ2 are close to each other and large.

  On the other hand, the correlation coefficient of RW_θ3 in correlation matrix Am2, the correlation coefficient of RW_θ3 and RW_φ1 and the correlation coefficient of RW_θ3 and RW_φ2 in cross-correlation matrix Cm2 are not close values. This is because RW_θ3 and RW_φ1 and RW_φ2 are not the result of estimating the same reflected wave RW.

  From this, the combination determination unit 163 determines a combination of the horizontal angle θ and the vertical angle φ by determining a combination of correlation coefficients having values close to each other from the correlation matrices Am1 and Am2 and the cross-correlation matrices Cm1 and Cm2. The combination determining unit 163 determines the determined horizontal angle θ and vertical angle φ as the arrival angle of the reflected wave RW.

  As described above, in the radar apparatus 1, the combination determination unit 163 can determine the combination of the horizontal angle θ and the vertical angle φ with higher accuracy by the calculation unit 162 performing the correlation calculation. In addition, the first calculation unit 162a performs a correlation calculation of incoming waves in the horizontal direction, and the second calculation unit 162b performs a cross-correlation calculation of incoming waves in the horizontal direction and the vertical direction. Thereby, the combination determination part 163 can determine the combination of horizontal angle (theta) and vertical angle (phi) more accurately.

  The candidates T1 and T2 selected by the adjustment unit 150 include overlapping combinations as shown in FIG. 1B. When determining the combination of the horizontal angle θ and the vertical angle φ, the combination determination unit 163 selects one of the candidate combinations for the overlapping combinations.

<Angle detection processing>
Next, a processing procedure executed by the radar apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing a procedure of angle detection processing executed by the radar apparatus 1. For example, the radar apparatus 1 performs the angle detection process illustrated in FIG. 4 while transmitting a transmission signal from the transmission antenna Tx.

  As shown in FIG. 4, the radar apparatus 1 performs FFT processing on the received signal (step S101). Next, the radar apparatus 1 estimates the arrival angle based on the reception signal subjected to the FFT process (step S102). For example, the radar apparatus 1 estimates the horizontal angle θ and the vertical angle φ.

  The radar apparatus 1 compares the estimated number of horizontal angles θ and the number of vertical angles φ (step S103). As a result of comparison, when the number of horizontal angles θ and vertical angles φ is equal (No in step S103), the process proceeds to step S105.

  As a result of comparison, when the number of horizontal angles θ and vertical angles φ is different (Yes in step S103), the radar apparatus 1 assigns groups R1 and R2 having the same number of horizontal angles θ and vertical angles φ to the horizontal angle θ and the vertical angle, respectively. Selection is made as candidates T1 and T2 for association with φ (step S104). The radar apparatus 1 estimates the power of the reflected wave RW for each angle included in the candidates T1 and T2 (step S105).

  The radar apparatus 1 performs a correlation calculation based on the estimated power of the reflected wave RW (step S106), and determines a combination of the horizontal angle θ and the vertical angle φ based on the calculation result (step S107).

  As described above, when the number of horizontal angles θ and vertical angles φ is different, the radar apparatus 1 according to the present embodiment selects candidates T1 and T2 so that the numbers match. Thus, the radar apparatus 1 can detect the arrival angle regardless of the number of horizontal angles θ and vertical angles φ. Further, by performing matrix calculation using the candidates T1 and T2 of the horizontal angle θ and vertical angle φ selected so that the numbers match, calculations and correlation calculations for estimating the power of the reflected wave RW with respect to the square matrix are performed. This can be done, and the load of arithmetic processing can be reduced. Furthermore, since the radar apparatus 1 detects the arrival angle using the information about the horizontal angle θ and the vertical angle φ without using the angle spectrum or the power spectrum, the influence of the spectrum estimation error can be suppressed. Therefore, the arrival angle can be detected with high accuracy.

<Modification>
A modification of the radar apparatus 1 according to the present embodiment will be described with reference to FIGS. FIG. 5 is a diagram illustrating a configuration of a radar apparatus 1A according to a modification. In the radar apparatus 1A according to the modification, the adjustment unit 150A adjusts the numbers of the horizontal angle θ and the vertical angle φ by adding dummy angles instead of selecting candidates for correspondence between the horizontal angle θ and the vertical angle φ. This is different from the radar apparatus 1 shown in FIG. Since other configurations and operations are the same as those of the radar apparatus 1 shown in FIG. 2, the same reference numerals are given and description thereof is omitted.

  The radar apparatus 1A according to the present modification includes an adjustment unit 150A that adds a dummy angle so that the number of horizontal angles θ and the number of vertical angles φ match when the number of horizontal angles θ is different from the number of vertical angles φ. For example, as described above, when the angles estimated by the angle estimation unit 140 are the horizontal angles θ = {θ1, θ2, θ3} and the vertical angles φ = {φ1, φ2}, the adjustment unit 150A sets the vertical angle φ3. to add. Thereby, the determination unit 160 performs estimation of the power of the reflected wave RW and correlation calculation based on the information on the horizontal angle θ = {θ1, θ2, θ3} and the vertical angle φ = {φ1, φ2, φ3}, and arrives. Detect the angle.

  FIG. 6 is a flowchart showing a procedure of angle detection processing executed by the radar apparatus 1A according to this modification. The flowchart shown in FIG. 6 is the same as the angle detection process shown in FIG. 4 except that a dummy angle is added in step S201 instead of step S104. .

  If the number of horizontal angles θ and the number of vertical angles φ are different (Yes in step S103), the radar apparatus 1A adds a dummy angle φ3 so that the number of horizontal angles θ and vertical angles φ is equal (step S201). ).

  In the above embodiment, when the numbers of the horizontal angle θ and the vertical angle φ are different, the combination candidates are selected according to the small number of angles, but for example, as shown in the present modification, dummy candidates are selected according to the large number of angles. An angle φ3 can also be added.

  Thus, in the present modification, the adjustment unit 150A of the radar apparatus 1A adds the dummy angle φ3, so that the number of horizontal angles θ and vertical angles φ can be matched. Thus, the arrival angle of the reflected wave RW can be detected regardless of the number of horizontal angles θ and vertical angles φ as in the first embodiment. Furthermore, by adding the dummy angle φ3, it is possible to reduce the number of candidates for the calculation performed by the determination unit 160, and it is possible to perform the calculation using a square matrix. Thereby, the processing load of the calculation performed by the determination unit 160 can be further reduced.

  As described above, the radar devices 1 and 1A according to the present embodiment and the modification include the angle estimation unit 140, the adjustment units 150 and 150A, and the determination unit 160. The angle estimation unit 140 receives the at least one reflected wave RW that is reflected by the transmission signal from at least one target and receives the received signal via the plurality of receiving antennas Rx in the first direction of the reflected wave RW ( The arrival angle θ in the horizontal direction) and the arrival angle φ in the second direction (vertical direction) different from the first direction are estimated.

  When the number of arrival angles θ in the first direction estimated by the angle estimation unit 140 is different from the number of arrival angles φ in the second direction, the adjustment unit 150 determines that the numbers of arrival angles θ and φ are in the first direction and The number is adjusted so as to match in the second direction. The determination unit 160 determines a combination of the arrival angle θ in the first direction and the arrival angle φ in the second direction based on the number of arrival angles θ and φ adjusted by the adjustment unit 150.

  Accordingly, the radar devices 1 and 1A can detect the arrival angle of the reflected wave RW even when the number of horizontal angles θ and the number of vertical angles φ are different.

  In addition, the adjustment unit 150 of the radar apparatus 1 according to the present embodiment, when the number of arrival angles of one of the first direction and the second direction is larger than the number of arrival angles of the other, The same number of arrival angles as the number of the other arrival angles is selected from the inside.

  Accordingly, the radar apparatus 1 can detect the arrival angle of the reflected wave RW even when the number of horizontal angles θ and the number of vertical angles φ are different.

  In addition, the adjustment unit 150A of the radar apparatus 1A according to the modification has the number of one arrival angle when the number of arrival angles of one of the first direction and the second direction is smaller than the number of arrival angles of the other. A dummy angle is added to one arrival angle so that is equal to the number of the other arrival angles.

  Thus, the radar apparatus 1A can detect the arrival angle of the reflected wave RW even when the number of horizontal angles θ and the number of vertical angles φ are different.

  Further, the determination unit 160 of the radar devices 1 and 1A according to the present embodiment and the modification includes a calculation unit 162 and a combination determination unit 163. The calculation unit 162 performs a correlation calculation based on the arrival angle adjusted by the adjustment unit 150. The combination determination unit 163 determines a combination according to the calculation result by the calculation unit 162.

  Accordingly, the radar devices 1 and 1A can detect the arrival angle of the reflected wave RW with high accuracy by performing the correlation calculation even when the number of the horizontal angles θ and the number of the vertical angles φ are different. .

  Further, the determination unit 160 of the radar devices 1 and 1A according to the present embodiment and the modification includes a first reflection estimation unit 161a and a second reflection estimation unit 161b. The first reflection estimation unit 161a estimates the power of the reflected wave based on the arrival angle θ in the first direction. The second reflection estimation unit 161b estimates the power of the reflected wave based on the arrival angle φ in the second direction.

  The computing unit 162 includes a first computing unit 162a and a second computing unit 162b. The first calculation unit 162a performs correlation calculation of the power of the reflected wave estimated by either the first reflection estimation unit 161a or the second reflection estimation unit 161b. The second calculation unit 162b performs a cross-correlation calculation between the reflected wave power estimated by the first reflection estimation unit 161a and the reflected wave power estimated by the second reflection estimation unit 161b.

  Accordingly, the radar devices 1 and 1A can detect the arrival angle of the reflected wave RW with high accuracy by performing the correlation calculation even when the number of the horizontal angles θ and the number of the vertical angles φ are different. .

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1, 1A Radar apparatus 10 Signal processing apparatus 20 Transmitting part 30 Receiving part 140 Angle estimation part 150, 150A Adjustment part 160 Determination part 161 Estimation part 161a 1st reflection estimation part 161b 2nd reflection estimation part 162 Calculation part 162a 1st calculation part 162b 2nd operation part 163 Combination determination part

Claims (6)

Based on a reception signal received via a plurality of antennas of at least one reflected wave that is reflected from at least one target, the arrival angle of the reflected wave in the first direction and the first direction are: An angle estimator for estimating the angles of arrival in different second directions;
When the number of arrival angles in the first direction estimated by the angle estimation unit is different from the number of arrival angles in the second direction, the number of arrival angles is the first direction and the second direction. An adjustment unit that adjusts the number so as to match,
A determination unit that determines a combination of the arrival angle in the first direction and the arrival angle in the second direction based on the number of the arrival angles adjusted by the adjustment unit;
A radar apparatus comprising: The adjustment unit is
When the number of the arrival angles in one of the first direction and the second direction is greater than the number of the other arrival angles, the number of the other arrival angles from the one of the arrival angles. The radar apparatus according to claim 1, wherein the same number of arrival angles are selected. The adjustment unit is
When the number of the arrival angles in one of the first direction and the second direction is smaller than the number of the other arrival angles, the number of the one arrival angles is the number of the other arrival angles. The radar apparatus according to claim 1, wherein a dummy angle is added to the one of the arrival angles so as to coincide with the first angle. The determination unit
A calculation unit for performing a correlation calculation based on the arrival angle adjusted by the adjustment unit;
A combination determining unit that determines the combination according to a calculation result by the calculating unit;
The radar apparatus according to claim 1, 2 or 3. The determination unit
A first reflection estimation unit configured to estimate the power of the reflected wave based on the arrival angle in the first direction;
A second reflection estimation unit that estimates the power of the reflected wave based on the arrival angle in the second direction,
The computing unit is
A first calculation unit that performs a correlation calculation of the power of the reflected wave estimated by either the first reflection estimation unit or the second reflection estimation unit;
5. A second operation unit that performs a cross-correlation operation between the reflected wave estimated by the first reflection estimation unit and the power of the reflected wave estimated by the second reflection estimation unit. The radar apparatus described. Based on a reception signal obtained by receiving at least one reflected wave reflected from at least one target via a plurality of antennas, the arrival angle in the first direction and the arrival angle in the second direction of the reflected wave An angle estimation step for estimating
When the number of arrival angles in the first direction estimated in the angle estimation step is different from the number of arrival angles in the second direction, the number of arrival angles is the first direction and the second direction. An adjustment step of adjusting the number so as to match,
A determination step of determining a combination of the arrival angle in the first direction and the arrival angle in the second direction based on the number of the arrival angles adjusted in the adjustment step;
An angle detection method comprising:

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