JP2023147387A - Radar device, object detection method and program - Google Patents

Abstract

To make it possible to process a received signal similar to that of an equally spaced linear array by interpolation processing that converts an unequally spaced array antenna to an equally spaced array antenna.SOLUTION: A radar device 100 includes: a receiving unit 52 that receives a signal reflected by one or more objects using a receiving antenna 8, which is an unequally spaced array antenna comprising a plurality of antenna elements arranged at unequal intervals; an interpolation processing unit 121 that performs interpolation processing on the received signal received by each antenna element of the receiving antenna 8 forming the unequally spaced array antenna and converts the received signal into a received signal at a virtually equally spaced array antenna having the same aperture length as the unequally spaced array antenna; and an angle estimation unit 122 that estimates an angle of the object using the converted received signal.SELECTED DRAWING: Figure 4

Description

The present invention relates to a radar device, an object detection method, and a program.

Array antennas formed by arranging a plurality of antenna elements are classified into linear array antennas, planar array antennas, etc. depending on the shape of the arrangement, and are used in radar devices for target detection. Generally, in a linear array antenna formed by arranging a plurality of antenna elements in series, the angular resolution can be improved as the aperture length, which is the length of the entire antenna array, is increased. On the other hand, if the spacing between antenna elements in a linear array antenna is increased to, for example, one wavelength, there is a problem in that unnecessary radiation called a grating lobe occurs. In this respect, it is desirable to suppress the spacing between the antenna elements to about half a wavelength. In other words, when the aperture length is expanded to improve angular resolution, the antenna spacing must be kept to about half a wavelength (λ/2) in order to simultaneously suppress grating lobes, which reduces the number of antenna elements required. The problem is that it increases.

In order to improve or eliminate the above trade-off problem between improving angular resolution and suppressing grating lobes, an unevenly spaced array antenna in which the spacing between the antenna elements of the array antenna is uneven has been proposed. ing. For example, Patent Document 1 describes a radar device that includes an array antenna including a plurality of antenna elements arranged at unequal intervals, and a grating determination unit that performs grating determination to determine whether a target object is a grating ghost. has been done. Patent Document 2 describes a radar device equipped with a transmitting array antenna and a receiving array antenna that have antenna groups arranged differently in order to maximize the aperture length in a virtual receiving array without deteriorating the detection performance of the radar. has been done. Patent Document 3 describes a radar device in which a group of transmitting antennas and a group of receiving antennas are arranged in a line at irregular intervals in order to suppress the detection of ghosts and further suppress the degree of cross-correlation. There is.

JP2021-162448A JP 2019-70595 Publication Japanese Patent Application Publication No. 2011-64567

Unequally spaced array antennas are a useful technology for realizing antenna characteristics that meet various requirements, while uniformly spaced array antennas are widely used for processing received signals such as angle estimation processing. The problem is that the algorithm cannot be used. The above-mentioned patent documents also employ complex algorithms such as digital beamforming and the Capon method.

One object of the present invention is to perform interpolation processing to convert the received signal of the non-uniformly spaced array antenna into the received signal of the equally spaced array antenna, thereby making it possible to perform the same received signal processing as in the case of the equally spaced array antenna. An object of the present invention is to provide a radar device, an object detection method, and a program.

In order to achieve the above and other objects, a radar device according to the present invention transmits a signal reflected by one or more targets to a radar device comprising a plurality of antenna elements arranged at unequal intervals. A signal transmitting/receiving unit that receives signals from the evenly spaced array antenna performs interpolation processing on the received signals received by each antenna element that constitutes the unevenly spaced array antenna, and generates a virtual signal that has the same aperture length as the unevenly spaced array antenna. The apparatus includes an interpolation processing section that converts the signal received by the equally spaced array antenna, and an angle estimating section that estimates the angle of the target object using the converted reception signal.

The angle estimating unit estimates the angle of the target object using an angle estimation algorithm applied to the received signal of the equidistant array antenna with respect to the received signal of the virtual equidistant array antenna obtained by the interpolation process. Good too.

The unevenly spaced array antenna may include an unevenly spaced linear array antenna.

The interpolation processing unit may perform interpolation processing using any one of linear interpolation, spline interpolation, akima interpolation, cubic interpolation, nearest neighbor interpolation, and piecewise cubic Hermite interpolation polynomial interpolation.

The interpolation processing unit executes a process of converting a received signal of an unevenly spaced array antenna having n antennas into a received signal of a virtual equally spaced array antenna having the same aperture length and having m antennas, where n is , may be an integer of 4 or more, and m may be an integer of n+1 or more.

Another aspect of the present invention is to receive a signal reflected by one or more targets by an unequal array antenna comprising a plurality of antenna elements arranged at unequal intervals, Performing interpolation processing on the received signal received by each antenna element constituting the antenna, converting it into a received signal in a virtual equidistant array antenna having the same aperture length as the irregularly spaced array antenna, and converting the received signal This is a target object detection method that estimates the angle of the target using the following.

Yet another aspect of the present invention provides an information processing device that receives signals reflected by one or more targets using an unequal array antenna comprising a plurality of antenna elements arranged at unequal intervals. processing, and performing interpolation processing on the received signal received by each antenna element constituting the unevenly spaced array antenna to convert it into a received signal at a virtual equally spaced array antenna having the same aperture length as the unevenly spaced array antenna. This program executes a process of estimating the angle of the target object using the converted received signal.

According to the present invention, by performing interpolation processing to convert a received signal of an irregularly spaced array antenna into a received signal of an evenly spaced array antenna, it is possible to perform the same received signal processing as in the case of a uniformly spaced array antenna.

FIG. 1 is a schematic diagram showing an example of antenna element arrangement of a uniformly spaced linear array antenna and an unequal spaced array antenna. FIG. 2 is an IQ diagram schematically showing interpolation processing. FIG. 3 is a schematic diagram showing interpolation processing for converting an unevenly spaced array antenna into an equally spaced array antenna. FIG. 4 is a block diagram showing a configuration example of a radar device according to an embodiment of the present invention. FIG. 5 is a block diagram showing an example of the configuration of the interpolation processing section. FIG. 6 is a block diagram showing an example of the configuration of the angle estimation section. FIG. 7 is a flowchart illustrating an overview of received signal processing in this embodiment. FIG. 8 is a flowchart showing the procedure of the target object detection method in this embodiment. FIG. 9 is a graph showing the angle estimation results by the radar device in this embodiment. FIG. 10 is a diagram showing the configuration of a computer. FIG. 11 is a diagram showing another configuration of the computer.

Hereinafter, a radar device according to an embodiment of the present invention will be described. Note that the present invention is not limited to the following embodiments. Furthermore, the figures referred to in the following description merely schematically illustrate the shape, size, and positional relationship to the extent that the content of the present invention can be understood. That is, the present invention is not limited to the shapes, sizes, and positional relationships illustrated in each figure.

<About terms>
An antenna formed by arranging a plurality of antenna elements in series at equal intervals is generally referred to as an evenly spaced linear array antenna, but in this specification, for simplicity, it will be referred to as an "equally spaced array antenna." Furthermore, an antenna in which a plurality of antenna elements are arranged in series at unequal intervals is generally referred to as an unequal array antenna, but in this specification, any antenna element of an evenly spaced array antenna is removed. In other words, an antenna with a configuration in which the spacing between antenna elements is an integral multiple of the antenna element spacing of an evenly spaced linear array antenna is called an "unequal spacing linear array antenna." An irregularly spaced array antenna having an antenna arrangement of 1 is simply referred to as an "unequally spaced array antenna." The term "non-uniformly spaced array antenna" encompasses "non-uniformly spaced linear array antenna."

<The concept of interpolation processing to convert an unevenly spaced array antenna to an equally spaced array antenna>
First, interpolation processing for converting an unevenly spaced array antenna into an equally spaced array antenna in the present invention will be explained. In this embodiment, in a radar device, when a reflected wave from a target object of a transmission wave transmitted from a transmission antenna is received by a reception antenna configured as an array antenna in which a plurality of antenna elements are arranged in series. think of. FIG. 1 shows a schematic diagram of a receiving antenna. FIG. 1A shows an equally spaced array antenna in which eight antenna elements are arranged in series at equal intervals d. The spacing d between the antenna elements is typically a half wavelength, which is 1/2 of the wavelength λ of the transmitted wave. Various angle estimation methods have been developed and used for received signals received by the equidistant array antenna having such a configuration. Examples of such angle estimation methods include a method using an autoregressive model (AR model), the Root-MUSIC method, the Root-WSF method, the ESPRIT method, and the Pisarenko method. A received signal received by an irregularly spaced array antenna cannot be processed using such a commonly used angle estimation method for a uniformly spaced array antenna. Therefore, in the present invention, by performing interpolation processing on the received signal from each antenna element of the irregularly spaced array antenna, it is converted into a received signal of a virtual equally spaced array antenna, and the various etc. This makes it possible to utilize the angle estimation method for spaced array antennas.

<Interpolation processing method>
As shown in FIG. 1, the unequal spacing array antenna includes an unequal spacing linear array antenna (FIG. 1(b)) obtained by thinning out some of the plurality of antenna elements constituting the unequal spacing array antenna, and an unequal spacing linear array antenna (FIG. A non-uniform array antenna (Fig. 1(c)). Now, in the equally spaced array antenna of FIG. 1(a), each antenna element is assigned an antenna ID of 1 to 8 from the left end to the right. The unevenly spaced linear array antenna in FIG. 1(b) has a configuration in which the two antenna elements with antenna IDs=5 and 7 in the equally spaced array antenna in FIG. 1(a) are removed. On the other hand, the non-uniformly spaced array antenna shown in FIG. 1(c) has two antenna elements removed, similar to the non-uniformly spaced linear array antenna shown in FIG. 1(b), but the non-uniformly spaced array antenna shown in FIG. The position of the antenna element corresponding to antenna ID=6 is shifted to the left. Therefore, if we assign antenna IDs = 1 to 6 from the left end to the right to the six antenna elements in the unequal spacing array antenna of FIG. The antenna element with ID=5 is arranged at a position that does not correspond to the position of antenna ID=6 of the equally spaced array antenna.

In the interpolation process in this embodiment, the received signal from each antenna element is converted to can be converted into a received signal from each antenna element of the equally spaced array antenna. Therefore, the received signals from the non-uniformly spaced linear array antenna as shown in FIG. 1(b) and the non-uniformly spaced array antenna as shown in FIG. 1(c) are processed using the angle estimation method for the uniformly spaced array antenna. be able to. A more detailed explanation will be given below using specific examples.

In the array antennas illustrated in FIGS. 1A to 1C, received signals are acquired as two-dimensional data consisting of a time series and an antenna ID, regardless of the applied radar format. For example, if the number of time series samples is 512 and the number of spatial samples, that is, the number of antenna elements is 6, as shown in FIGS. becomes. Here, in order to simplify the explanation, a case will be considered in which a reception signal of an antenna ID string seen in a specific time section in a time series is focused and extracted. In this case, in the example of the array antenna shown in FIGS. 1(b) and 1(c), the received signal is a 6-point data string corresponding to each antenna element.

<In the case of the unevenly spaced linear array antenna illustrated in FIG. 1(b)>
Interpolation processing from the received signal of the unevenly spaced linear array antenna illustrated in FIG. 1(b) to the received signal of the equally spaced array antenna (FIG. 1(a)) having the same aperture length is performed as follows. Ru.
- The received signal at the antenna element specified by antenna ID=i is expressed as z(i). At this time, the received signals actually received by each antenna element (antenna ID = 1 to 6) of the unevenly spaced linear array antenna in FIG. 1(b) are expressed as z(1) to z(6). Ru. On the other hand, the received signal received by each antenna element of the virtual equidistant array antenna determined by the interpolation process is represented by the symbol z'. In the example of FIG. 1, the interval between antenna elements of each array antenna is defined as follows.
d: Antenna spacing di,i+1 in the equally spaced array antenna of FIG. 1(a): Distance between the i-th antenna element and the i+1-th antenna element Unequally spaced linear array illustrated in FIG. 1(b) The antenna has a configuration in which two antennas with ID=5 and 7 are thinned out from an equally spaced array antenna with the same aperture length. Therefore, received signals z'(1) to z'(4), z'(6), z'(8) of antenna ID=1 to 4, 6, and 8 in the virtual equidistant array antenna after interpolation processing are equal to the received signals z(1) to z(4), z'(5), and z'(6) of the antenna ID=1 to 4, 6, and 8 of the nonuniform linear array antenna, respectively. On the other hand, the received signals z'(5) and z'(7) of the antenna ID=5 and 7 of the evenly spaced array antenna, which do not have antenna elements corresponding to the unevenly spaced linear array antenna, are It is necessary to calculate it from the received signals z(4), z(5), and z(6) of the linear array antenna with antenna ID=4, 5, and 6. When this calculation is performed by linear interpolation, it is as follows.
The spacing between antenna elements of the unevenly spaced linear array antenna illustrated in FIG. 1(b) is
d1,2 = d2,3 = d3,4 = d
d4,5 = d5,6 = 2d
It becomes. Therefore, according to linear interpolation, the received signals z'(5) and z'(7) of antenna ID=5 and 7 of the virtual equidistant array antenna (FIG. 1(a)) are respectively
z'(5) = ((d4,5-d)*z(5)+d*z(4))/d4,5 = (z(5)+z(4))/2
z'(7) = ((d5,6-d)*z(6)+d*z(5))/d5,6 = (z(6)+z(5))/2
can be asked.

<In the case of the unevenly spaced array antenna illustrated in FIG. 1(c)>
In the case of the irregularly spaced array antenna illustrated in FIG. 1(c), there are no corresponding antenna elements for the three antennas ID=5, 6, and 7 of the equally spaced array antenna in FIG. 1(a). Therefore, it is necessary to generate received signals z'(5), z'(6), and z'(7) of antenna ID=5, 6, and 7 by interpolation processing.
The spacing between antenna elements of the unevenly spaced linear array antenna illustrated in FIG. 1(c) is
d1,2 = d2,3 = d3,4 = d
d4,5 = 1.5d
d5,6 = 2.5d
It becomes. Therefore, according to linear interpolation, the received signals z'(5), z'(6), z'(7) of antenna ID=5, 6, and 7 of the virtual equidistant array antenna (FIG. 1(a)) are respectively
z'(5) = ((d4,5-d)*z(5)+d*z(4))/d4,5 = (0.5d*z(5)+d*z(4))/1.5 d
z'(6) = ((d5,6-0.5d)*z(6)+3.0d*z(5))/d5,6 = (2.0d*z(6)+0.5z(5))/ 2.5d
z'(7) = ((d5,6-d)*z(6)+d*z(5))/d5,6 = (1.5d*z(6)+d*z(5))/2.5 d
can be asked.

The received signals z(1) to z(6) at the non-uniformly spaced linear array antenna (Fig. 1(b)) obtained by the above interpolation processing method and the received signals from the virtual equally spaced array antenna after the interpolation processing The received signals z'(1) to z'(8) are illustrated in the IQ plane of FIG. Looking at the signal points shown in the figure, the received signals z'(1) to z'(4), z'(6), z'( The signal point indicating 8) corresponds to the signal point indicating the received signals z(1) to z(6) of antenna ID=1 to 6 in the unevenly spaced linear array antenna. On the other hand, regarding the received signals z'(5) and z'(7) of antenna ID=5 and 7 in the evenly spaced array antenna, there is no received signal corresponding to the unevenly spaced linear array antenna. It is generated as described above from antenna ID=4, 5, and 6 of the antenna. For example, the received signal z'(5) of the evenly spaced array antenna with antenna ID = 5 is generated from the received signals z(4) and z(5) of the unevenly spaced linear array antenna, and its amplitude and phase angle are As shown in the example.

<Example of interpolation processing of received signal>
Although an example of the interpolation process of this embodiment has been explained using the antenna element arrangement illustrated in FIG. 1, the antenna arrangement to which the present invention can be applied is not limited to the example shown in FIG. 1, and may have any antenna element arrangement. It is possible to convert a received signal of an irregularly spaced array antenna into a received signal of a virtual equally spaced array antenna having the same aperture length. An example is shown in FIG. As shown in FIG. 3, for example, the received signals of unequally spaced array antennas with various antenna arrangements having 4 to 6 antenna elements can be processed by the interpolation process exemplified in this embodiment to have the same aperture length. , it can be converted into a received signal of an equally spaced linear array antenna with 6 or 15 antenna elements. What kind of interpolation processing to perform can be appropriately determined through simulations such as angle estimation processing, which will be described later. In the example shown in FIG. 3, when converting an unequal array antenna with six antenna elements to an evenly spaced array antenna with eight antenna elements, a relatively good The results were obtained. Note that the example of the interpolation process described above is as follows: ``When n is an integer of 4 or more, and m is an integer of n+1 or more, the received signal of an unevenly spaced array antenna having n antennas is It can also be generalized and expressed as "can be converted into a received signal of a virtual equidistant array antenna having the same aperture length."

Note that in the above example of interpolation processing, linear interpolation was adopted as the processing method. Although linear interpolation is a method that is easy to calculate, versatile, and easy to use, the interpolation processing method is not limited to this, and can be executed by various methods. Techniques that can be used for interpolation processing include, for example, spline interpolation, akima interpolation, cubic interpolation, nearest neighbor interpolation, and piecewise cubic Hermite interpolation polynomial interpolation, but are not particularly limited to these. The specific arithmetic processing performed by each interpolation processing method and the characteristics of each method are well-known information, so a description thereof will be omitted.

As described above, according to the interpolation process of the received signal in this embodiment, the received signal of a general unevenly spaced array antenna, not limited to the unevenly spaced linear array antenna, can be It can be converted into a received signal of a spaced array antenna.

<Radar equipment that applies interpolation processing of received signals>
Next, a radar apparatus to which interpolation processing of antenna reception signals in this embodiment is applied will be described. FIG. 4 is a block diagram showing a configuration example of the radar device 100 according to an embodiment of the present invention. The radar apparatus 100 illustrated in FIG. 4 adopts a pulse method in which a plurality of pulse signals having different center frequencies are transmitted, the transmitted signals are reflected by a target object, and the reflected signals are received. This method may also be used. Further, it is assumed that the receiving antenna of this radar device 100 uses an unequal spacing array antenna having an arbitrary number of antenna elements and an arbitrary element arrangement.

As shown in FIG. 4, the radar device 100 includes a transmitter 51, a receiver 52, an orthogonal demodulator 10, an ADC (Analog to Digital Converter) 11, a signal processor 12, and a data processor 13. Be prepared.

The transmitter 51 has a function of transmitting a plurality of transmission signals in different frequency bands. The transmitting section 51 includes a local oscillation control section 1, a local oscillation section 2, a local oscillation frequency monitoring section 3, a modulation signal generation section 4, a modulation section 5, an amplification section 6, and a transmission antenna 7.

The local oscillation control section 1 controls each section of the radar device 100 and also controls the frequency of the local oscillation signal generated by the local oscillation section 2.

The local oscillator 2 generates and outputs a local oscillator signal having a frequency according to the control of the local oscillator controller 1. The modulation signal generation section 4 generates a modulation signal for modulating the local oscillation signal supplied from the local oscillation section 2 into a pulse waveform, and supplies it to the modulation section 5 . In addition to pulse modulation, modulation may be performed using other methods such as phase modulation and frequency modulation.

The modulation section 5 modulates the local oscillation signal supplied from the local oscillation section 2 based on the modulation signal supplied from the modulation signal generation section 4 and supplies it to the amplification section 6 .

The amplification section 6 amplifies the power of the pulse signal supplied from the modulation section 5 and supplies it to the transmission antenna 7.

The transmitting antenna 7 is composed of one or more antenna elements, and transmits the pulse signal supplied from the amplifying section 6 as an electromagnetic wave toward a target object.

The receiving unit 52 receives respective received signals obtained by reflecting a plurality of transmission signals having different frequency bands, which are transmitted by the transmitting unit 51, by one or a plurality of targets. The receiving section 52 includes a receiving antenna 8 and an amplifying section 9.

The receiving antenna 8 is composed of one or more antenna elements, captures electromagnetic waves (reflected signals) reflected by a target object, converts them into electrical signals, and supplies the electrical signals to the amplifying section 9 . As described above, in this embodiment, the receiving antenna 8 is an irregularly spaced array antenna configured with an appropriate number of antenna elements and antenna element arrangement. The amplifying section 9 amplifies the power of the electrical signal supplied from the receiving antenna 8 and supplies it to the quadrature demodulating section 10 .

The orthogonal demodulation section 10 down-converts (converts the frequency to a lower frequency) the electric signal supplied from the amplification section 9 using the local oscillation signal supplied from the local oscillation section 2, and performs orthogonal demodulation using mutually orthogonal signals. The obtained I and Q components are supplied to an AD converter (ADC) 11.

The ADC 11 converts the I and Q components as analog signals supplied from the orthogonal demodulator 10 into digital data and outputs the digital data.

The signal processing unit 12 performs predetermined signal processing on the digital data from the ADC 11 based on information indicating the frequency of the local oscillation signal supplied from the local oscillation frequency monitor unit 3, and performs data processing on the result of the signal processing. 13. Specifically, the signal processing section 12 includes an interpolation processing section 121 and an angle estimating section 122.

The interpolation processing unit 121 has an interpolation processing function that converts the received signal from the non-uniformly spaced array antenna in this embodiment into the received signal from the equally spaced array antenna having the same aperture length. The received signal interpolated by the interpolation processing unit 121 can be processed as a received signal from the equally spaced array antenna in the angle estimating unit 122 at the subsequent stage. An example of the configuration of the interpolation processing section 121 is shown in the block diagram of FIG. As shown in FIG. 5, the interpolation processing section 121 includes an ADC data storage section 1211, an antenna coordinate storage section 1213, a signal interpolation processing section 1212, and an interpolation data storage section 1214.

The ADC data storage unit 1211 is a memory that stores I and Q component digital data of the received signal output from the ADC 11. The antenna coordinate storage unit 1213 is a memory that stores data on antenna coordinates used for interpolating an unevenly spaced array antenna into an equally spaced array antenna having the same aperture length. Specifically, the antenna coordinate storage unit 1213 stores the number and arrangement of antenna elements of the unevenly spaced array antenna used as the receiving antenna 8 of the radar device 100, and the number of antenna elements of the equally spaced array antenna after interpolation processing. and their arrangement (inter-element spacing) are stored. In the case of this embodiment, the following description will be made assuming that the number of antenna elements of the equidistant array antenna after interpolation processing is eight.

The signal interpolation processing unit 1212 executes interpolation processing to convert the received signal from the ADC data storage unit 1211 into a received signal of the equally spaced array antenna based on the antenna coordinate data read from the antenna coordinate storage unit 1213. A specific example of the interpolation process has already been described. The interpolation data storage unit 1214 is a memory that stores I and Q component digital data as a reception signal of the equally spaced array antenna generated by the signal interpolation processing unit 1212. The processing performed by the subsequent functional blocks is performed on the received signal generated by the signal interpolation processing unit 1212 as if received by a regular equidistant array antenna having eight antenna elements.

The angle estimator 122 has a function of estimating the angle (direction of arrival estimation) of the received signal based on the interpolated received signal. FIG. 6 shows a block diagram of a configuration example of the angle estimation section 122. The angle estimation section 122 includes an AR degree storage section 1222, an AR coefficient calculation section 1221, an AR coefficient storage section 1223, a signal expansion section 1224, and an angle FFT section 1225. In this embodiment, the angle estimation process of the object based on the received signal is performed using an autoregressive (AR) model estimated by the Yule-Walker method. As described above, the angle estimation process can also be performed using other estimation methods such as the Root-MUSIC method, the Root-WSF method, the ESPRIT method, and the Pisarenko method.

The AR coefficient calculation unit 1221 calculates coefficients (AR coefficients) of an auto regressive model based on eight received signals (array antenna signals after interpolation (hereinafter referred to as "signals after interpolation")). calculate. The calculated AR coefficient is stored in the AR coefficient storage section 1223. The AR order storage unit 1222 stores order data that is set in advance to be used for prediction using the AR model.

The signal expansion unit 1224 performs arithmetic processing using an autoregressive model based on the interpolated signal and the AR coefficient read from the AR coefficient storage unit 1223, and estimates and expands the interpolated signal in the array antenna direction. Hereinafter, this expanded array antenna signal train will be referred to as an "extended array antenna signal train."

Angle FFT section 1225 performs Fourier transform on the extended array antenna signal string expanded by signal expansion section 1224, thereby processing the amplitude information of the expanded array antenna signal string to be separated for each target object. That is, the angle FFT unit 1225 calculates the result of the calculation using the interpolated signal obtained by interpolating the received signal received by the receiving unit 52 in the interpolation processing unit 121 and the coefficients of the autoregressive model. Based on this, the interpolated signal is separated into target signals reflected from each target.

The data processing unit 13 performs clustering processing on the digital data (information regarding the position of each target estimated based on each target signal separated in the angle estimation unit 122) supplied from the signal processing unit 12. and tracking processing, etc., to perform processing to detect the target object. Note that the data processing unit 13 may be configured to be provided outside the radar device 100.

As described above, the radar device 100 according to the present embodiment receives a reception signal received by the reception antenna 8, which is an irregularly spaced array antenna, using an equally spaced linear array antenna having the same aperture length and having eight antenna elements. The eight received signals can be converted into received signals, and the angular FFT section 1225 can separate the eight received signals into target signals reflected from the respective targets. For this reason, it has become possible to perform angle estimation and subsequent position estimation for the received signal of the non-uniformly spaced array antenna by angle estimation processing that can be applied only to the processing of the received signal by the evenly spaced array antenna. There is.

Note that in this embodiment, an AR model estimated by the Yule-Walker method is applied to the angle estimation process after the signal is converted into a reception signal of the equally spaced array antenna. However, the angle estimation process is not limited to this method, and various signal processing methods that can be applied to the reception signal processing of the equidistant array antenna can be adopted. This embodiment is particularly advantageous in that it is possible to employ a technique that can be applied only to the reception signal processing of the equidistant array antenna. Non-limiting examples of such signal processing methods include the Root-MUSIC method, the Root-WSF method, the ESPRIT method, and the Pisarenko method.

<Signal processing flow by radar device 100>
Next, specific operations of the radar device 100, particularly the signal processing section 12, will be explained.
<<Reception processing of reflected waves from target object>>
FIG. 7 shows a processing flow example of reflected wave reception processing by the radar device 100 of this embodiment.

First, the receiving unit 52 receives reflected waves from a target object using the receiving antenna 8, which is an irregularly spaced array antenna, while switching antenna elements (step S1).

The received signal passes through the orthogonal demodulator 10 and the ADC 11, and is stored in the ADC data storage unit 1211 as a received signal of the receiving antenna 8, which is an unequal array antenna (step S2).

The signal interpolation processing unit 1212 converts the received signal from the receiving antenna 8, which is an irregularly spaced array antenna, into a received signal of a virtual equally spaced array antenna by interpolation processing (step S3). The converted received signal is stored in interpolated data storage section 1214.

The reception signals of the equally spaced array antennas obtained by the interpolation process and stored in the interpolation data storage unit 1214 are subjected to an angle estimation process (direction of arrival estimation process) in the angle estimation unit 122, and are separated for each object. Ru. Through the above data processing, the received signal received by the receiving antenna 8 configured as an irregularly spaced array antenna is converted into a received signal of a virtual equally spaced array antenna by interpolation processing, and The angle estimation process executes angle estimation of the object.

<<Signal processing for interpolated received signals>>
Next, the angle estimation process in the signal processing section 12 of the radar device 100 will be explained. As already explained, this processing is performed after converting the received signal of the receiving antenna 8, which is an irregularly spaced array antenna, into a received signal of a virtual equally spaced array antenna. In this respect, it is similar to the case of a radar device that uses a normal equidistant array antenna as the receiving antenna 8, but an overview will be given below to show the operation of the radar device 100. FIG. 8 is a flowchart illustrating the procedure of signal processing by the angle estimation unit 122 of the radar device 100. Note that data processing for which the processing entity is not specified is executed by a control block (not shown) that manages data input/output processing and the like for the angle estimating unit 122.

In order to process the interpolated received signal, in step S10, the chronological number "j" of the first received signal is set to j=0.

In step S11, the j-th time-series received signal sequence is read out from the interpolated received signals for eight antennas stored in the interpolated data storage unit 1214 of the interpolation processing unit 121. The read received signal sequence is transmitted to the AR coefficient calculation section 1221 and the signal expansion section 1224.

In step S12, the AR coefficient calculation unit 1221 generates a matrix-format equation from the transmitted received signal sequence. The AR coefficient calculation unit 1221 calculates an AR coefficient from an equation generated based on the AR degree (the number p of AR coefficients) stored in the AR degree storage unit 1222.

In step S13, the AR coefficient calculation unit 1221 stores the AR coefficient calculated in step S12 in the AR coefficient storage unit 1223.

In step S14, the signal expansion unit 1224 calculates an extended signal sequence in which the signal is expanded in the frequency direction using the AR model, based on the AR coefficients stored in the AR coefficient storage unit 1223 and the extracted received signal sequence. .

In step S15, the signal extension unit 1224 stores the extended signal sequence in chronological order.

In step S16, the chronological number "j" of the received signal sequence is incremented to "j=j+1".

In step S17, it is determined whether the number "j" of the time series signal updated in step S16 has reached a predetermined number "M-1". M indicates the number of samples of the time series signal. If "j=M-1" (step S17: Yes), the process proceeds to step S18, and if "j=M-1" does not exist (step S17: No), the process returns to step S11.

In step S18, acquisition of the extended time series signal (extended received signal sequence) by frequency is completed and saved.

In step S19, the angle FFT unit 1225 of the angle estimation unit 122 performs FFT processing on the extended received signal sequence to calculate an angle spectrum signal, and returns the process to the main routine.

In this way, the angular spectrum of the object is acquired by the radar device 100 in this embodiment.

<Explanation of angle estimation processing results>
FIG. 9 shows the results of estimating the angle of the reflected wave from the target using the radar device 100 in this embodiment. FIG. 9 is a spectrum diagram showing the result of converting the reception signal received by the irregularly spaced array antenna of the radar device 100 into the reception signal of the equally spaced linear array antenna by interpolation processing and performing angle estimation processing. The horizontal axis shows the receiving angle of the receiving antenna, and the vertical axis shows the amplitude with respect to the receiving angle. In this simulation, targets were set at two locations: +20 degrees and -10 degrees. As a receiving antenna, an equally spaced linear array antenna with antenna ID = 0 to 7 is used, and an unequal antenna having a configuration in which two antenna elements with antenna ID = 1 and 3 are removed from the equally spaced array antenna. It is assumed that a spaced linear array antenna is used. Then, based on the received signal of the above-mentioned unevenly spaced linear array antenna, the received signal of the equally spaced array antenna having eight antenna elements with antenna ID=0 to 7 is converted by interpolation processing. We performed angle estimation processing for the cases and compared the results. As shown in FIG. 9, in the case of the equidistant array antenna having eight antenna elements, the two targets are clearly separated and the grating lobes are suppressed, resulting in good results. On the other hand, in the case of an unevenly spaced linear array antenna with two antenna elements removed (indicated by the label "6 antennas, #1, 3 removed"), the amplitude with respect to the target decreases, while the grating lobe It can be seen that the angle estimation performance decreases as the angle increases. However, if the received signal is converted by interpolation into a received signal from an equally spaced array antenna having 8 antenna elements (labeled "8 antennas, #1, 3 interpolation"), the amplitude for the target will be equal. The second highest value is obtained for the spaced linear array antenna, and the grating lobes are significantly lower than those for the unevenly spaced linear array antenna with 6 antenna elements, and are almost on par with the evenly spaced array antenna with 8 antenna elements. It has become. In this way, in this embodiment, by converting the received signal of the non-uniformly spaced array antenna into the received signal of the uniformly spaced array antenna with the same aperture length by interpolation processing, the radar using the non-uniformly spaced array antenna as a receiving antenna can be constructed. This shows that it is possible to improve the angle estimation performance of the device.

<About the program>
The data processing of the radar device 100 described above can also be realized by causing a computer (information processing device) to execute a program that describes the function of the data processing. The configuration and operation of the computer will be explained using FIG. 10. FIG. 10 is a diagram showing the configuration of the computer 200. As shown in FIG. 10, the computer 200 includes a processor 201, a memory 202, a storage 203, an input/output I/F 204, and a communication I/F 205 connected on a bus A. The functions and/or methods described in this embodiment are realized by cooperation of each of these components.

The memory 202 is composed of RAM (Random Access Memory). RAM is comprised of volatile memory or nonvolatile memory.

The storage 203 is composed of ROM (Read Only Memory). The ROM is composed of nonvolatile memory, and is realized by, for example, a HDD (Hard Disc Drive), an SSD (Solid State Drive), or a Flash Memory. The storage 203 stores various programs such as programs that implement the functions of the radar device 100 in this embodiment.

An RF circuit 300 is connected to the input/output I/F 204. One or more transmitting antennas 7 and one or more receiving antennas 8 are connected to the RF circuit 300. The RF circuit 300 has functions such as a local oscillation control section 1, a local oscillation section 2, a local oscillation frequency monitoring section 3, a modulation signal generation section 4, a modulation section 5, and amplification sections 6 and 9.

Processor 201 controls the overall operation of computer 200. The processor 201 is an arithmetic device that loads an operating system and various programs that implement various functions from the storage 203 into the memory 202 and executes instructions included in the loaded programs.

Specifically, when receiving a user operation, the processor 201 reads a program (for example, a program according to the present invention) stored in the storage 203, expands the read program to the memory 202, and executes the program. do. In addition, each function of the signal processing section 12, the data processing section 13, etc. is realized by the processor 201 executing the processing program.

Here, the configuration of the processor 201 will be explained. The processor 201 is realized by, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), various other arithmetic units, or a combination thereof.

In addition, in order to realize the functions and/or methods described in this embodiment, some or all of the functions such as the processor 201, the memory 202, and the storage 203 are implemented by a computer (hereinafter referred to as (referred to as a processing circuit) 400. FIG. 11 is a diagram showing the configuration of the processing circuit 400. The processing circuit 400 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. It is. An RF circuit 300 is connected to the processing circuit 400 . One or more transmitting antennas 7 and one or more receiving antennas 8 are connected to the RF circuit 300.

Further, although the processor 201 has been described as a single component, the processor 201 is not limited to this, and may be configured as a set of a plurality of physically separate processors. In this specification, a program described as being executed by the processor 201 or instructions included in the program may be executed by a single processor 201 or may be executed in a distributed manner by a plurality of processors. . Further, the program executed by the processor 201 or the instructions included in the program may be executed by a plurality of virtual processors.

The communication I/F 205 is an interface that complies with a predetermined communication standard (for example, CAN (Controller Area Network)), and communicates with an external device by wire or wirelessly.

In this way, the program, when executed by the computers 200 and 400, converts the received signals of the non-uniformly spaced array antennas into the received signals of the equally spaced array antennas with the same aperture length, and performs angle estimation processing to The received signal is separated into target signals reflected from each target. By doing so, it is possible to reduce the processing load and improve the angle estimation performance by applying an angle estimation algorithm that can process only the received signals of the equally spaced array antenna.

According to the embodiment described above, the following effects are achieved.

The radar device 100 according to the present embodiment receives signals reflected by one or more target objects using a receiving antenna 8, which is an irregularly spaced array antenna including a plurality of antenna elements arranged at irregular intervals. The receiving unit 52 performs interpolation processing on the received signals received by each antenna element of the receiving antenna 8 constituting the non-uniformly spaced array antenna, and performs interpolation processing on the received signals received by the receiving unit 52 and each antenna element of the receiving antenna 8 that constitutes the non-uniformly spaced array antenna. It includes an interpolation processing section 121 that converts into a received signal at an array antenna, and an angle estimating section 122 that estimates the angle of the target using the converted received signal.

Thereby, it is possible to perform angle estimation processing on the received signal received by the irregularly spaced array antenna using an algorithm for processing the received signal by the receiving antenna of the equally spaced array antenna.

In the radar device 100, the angle estimating unit 122 calculates the angle of the target object using an angle estimation algorithm applied to the received signal of the equidistant array antenna with respect to the received signal of the virtual equidistant array antenna obtained by the interpolation process. The angle may also be estimated.

This makes it possible to reduce the computational processing load for the angle estimation algorithm.

The unevenly spaced array antenna may include an unevenly spaced linear array antenna.

As a result, the algorithm for estimating the received signal angle of the evenly spaced array antenna can be applied to a wide variety of non-uniformly spaced array antennas.

In the radar device 100, the interpolation processing unit 121 may perform interpolation processing using any one of linear interpolation, spline interpolation, akima interpolation, cubic interpolation, nearest neighbor interpolation, and piecewise cubic Hermite interpolation polynomial interpolation.

Thereby, it is possible to employ an interpolation processing method suitable for the specifications, required performance, etc. of the radar device 100.

In the radar device 100, the interpolation processing unit 121 performs a process of converting a received signal of an unevenly spaced array antenna having n antennas into a received signal of a virtual equally spaced array antenna having the same aperture length and having m antennas. n may be an integer greater than or equal to 4, and m may be an integer greater than or equal to n+1.

Thereby, the angle estimation performance can be suitably improved.

In the target object detection method according to the present embodiment, a signal reflected by one or more target objects is transmitted by a receiving antenna 8 as an irregularly spaced array antenna comprising a plurality of antenna elements arranged at irregular intervals. Interpolation processing is performed on the received signals received by each antenna element of the receiving antenna 8 constituting the non-uniform array antenna, and a virtual equidistant array antenna having the same aperture length as the non-uniform array antenna. The angle of the target object is estimated using the converted received signal.

Thereby, it is possible to perform angle estimation processing on the received signal received by the irregularly spaced array antenna using an algorithm for processing the received signal by the receiving antenna of the equally spaced array antenna.

The program of this embodiment causes the computer 200 to transmit signals reflected by one or more target objects using a receiving antenna 8 as an unequal-spaced array antenna comprising a plurality of antenna elements arranged at unequal intervals. A virtual equidistant array having the same aperture length as the irregularly spaced array antenna is created by performing reception processing and interpolation processing on the received signals received by each antenna element of the receiving antenna 8 constituting the irregularly spaced array antenna. A process of converting into a received signal at an antenna and a process of estimating the angle of the target object using the converted received signal are executed.

Thereby, it is possible to perform angle estimation processing on the received signal received by the irregularly spaced array antenna using an algorithm for processing the received signal by the receiving antenna of the equally spaced array antenna.

Some of the embodiments of the present application have been described above in detail based on the drawings, but these are merely examples, and various modifications and improvements can be made based on the knowledge of those skilled in the art, including the embodiments described in this specification. It is possible to implement the present invention in other forms.

1 Local oscillation control section 2 Local oscillation section 3 Local oscillation frequency monitor section 4 Modulation signal generation section 5 Modulation section 6 Amplification section 7 Transmission antenna 8 Reception antenna 9 Amplification section 10 Quadrature demodulation section 11 ADC
12 Signal Processing Unit 13 Data Processing Unit 121 Interpolation Processing Unit 122 Angle Estimating Unit 51 Transmitting Unit 52 Receiving Unit 100 Radar Device

Claims (7)

a signal transmitting/receiving unit that receives signals reflected by one or more targets using an unequal-spaced array antenna comprising a plurality of antenna elements arranged at unequal intervals;
Interpolation processing that performs interpolation processing on the received signal received by each antenna element constituting the unevenly spaced array antenna, and converts it into a received signal at a virtual equally spaced array antenna having the same aperture length as the unevenly spaced array antenna. Department and
an angle estimation unit that estimates the angle of the target using the converted received signal;
A radar device equipped with.
The angle estimating unit estimates the angle of the target object using an angle estimation algorithm applied to the received signal of the equidistant array antenna with respect to the received signal of the virtual equidistant array antenna obtained by the interpolation process. The radar device according to claim 1.
The radar device according to claim 1 or 2, wherein the unevenly spaced array antenna includes an unevenly spaced linear array antenna.
4. The interpolation processing unit according to claim 1, wherein the interpolation processing unit performs interpolation processing by any one of linear interpolation, spline interpolation, akima interpolation, cubic interpolation, nearest neighbor interpolation, and piecewise cubic Hermite interpolation polynomial interpolation. Radar equipment described in section.
The interpolation processing unit executes a process of converting a received signal of an unevenly spaced array antenna having n antennas into a received signal of a virtual equally spaced array antenna having the same aperture length and having m antennas,
n is an integer of 4 or more,
The radar device according to any one of claims 1 to 4, wherein m is an integer greater than or equal to n+1.
Receiving a signal reflected by one or more targets by an irregularly spaced array antenna comprising a plurality of antenna elements arranged at irregular intervals,
Performing interpolation processing on the received signal received by each antenna element constituting the unevenly spaced array antenna, converting it into a received signal at a virtual equally spaced array antenna having the same aperture length as the unevenly spaced array antenna,
estimating the angle of the target using the converted received signal;
Object detection method.
In the information processing device,
A process of receiving a signal reflected by one or more targets using an irregularly spaced array antenna comprising a plurality of antenna elements arranged at irregular intervals;
A process of performing interpolation processing on the received signal received by each antenna element constituting the unevenly spaced array antenna to convert it into a received signal at a virtual equally spaced array antenna having the same aperture length as the unevenly spaced array antenna. ,
a process of estimating the angle of the target using the converted received signal;
A program to run.

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