Radar system

Abstract

To provide a radar system that can perform appropriate imaging of an object.SOLUTION: A radar system according to an embodiment is provided with a plurality of antennas, and a processing unit that drives the plurality of antennas in a first mode or a second mode according to an object. When driving the plurality of antennas in the first mode, the processing unit causes the plurality of antennas to operate in cooperation with each other, and performs imaging of the object based on reflection wave signals received by the plurality of antennas. When driving the plurality of antennas in the second mode, the processing unit causes a first antenna group of the plurality of antennas to operate in cooperation with each other, performs imaging of the object based on reflection wave signals received by the first antenna group, causes a second antenna group of the plurality of antennas to operate in cooperation with each other, and performs imaging of the object based on reflection wave signals received by the second antenna group.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] Embodiments of the present invention relate to a radar system.

Background Art

[0002] In recent years, radar systems that perform imaging of a target object using reflected waves of radar signals (transmitted waves) have been developed.

[0003] Here, the spatial resolution in the above-described imaging is generally set according to the range where the target object is estimated to exist (the distance to the target object).

[0004] However, for example, when the radar system is operated in an environment where the distance to the target object changes (is indefinite), the spatial resolution achieved in imaging varies, which may make it impossible to perform appropriate imaging of the target object.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Accordingly, a problem to be solved by the present invention is to provide a radar system capable of performing appropriate imaging of a target object.

Means for Solving the Problems

[0007] The radar system according to the embodiment comprises a plurality of antennas configured to transmit radar signals and receive reflected wave signals based on the reflected waves of the radar signals, and a processing unit that drives the plurality of antennas in first and second modes depending on the object. When the plurality of antennas are driven in the first mode, the processing unit causes the plurality of antennas to operate in coordination and performs imaging of the object based on the reflected wave signals received by the plurality of antennas. When the plurality of antennas are driven in the second mode, the processing unit causes a first group of antennas to operate in coordination as a first group and performs imaging of the object based on the reflected wave signals received by the first group of antennas, and causes a second group of antennas to operate in coordination as a second group and performs imaging of the object based on the reflected wave signals received by the second group of antennas. The second group of antennas differs from the first group of antennas in at least some of its antennas. When the processing unit drives the plurality of antennas in the third mode, it coordinates the operation of the third antenna group as the third group and performs imaging of the object based on the reflected wave signal received by the third antenna group; it coordinates the operation of the fourth antenna group as the fourth group and performs imaging of the object based on the reflected wave signal received by the fourth antenna group; and it coordinates the operation of the fifth antenna group as the fifth group and performs imaging of the object based on the reflected wave signal received by the fifth antenna group. The third to fifth antenna groups differ from each other in at least some of their antennas. The first mode is selected when the distance between the object and the plurality of antennas is greater than or equal to a first predetermined value. The second mode is selected when the distance between the object and the plurality of antennas is less than the first predetermined value and greater than or equal to a second predetermined value. The third mode is selected when the distance between the object and the plurality of antennas is less than the second predetermined value. The first predetermined value is greater than the second predetermined value. The first and second predetermined values ​​are determined based on the spatial resolution achieved in the radar system. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram illustrating the FMCW system used in radar equipment. [Figure 2] A diagram illustrating the overview of MIMO radar. [Figure 3] A diagram illustrating spatial resolution. [Figure 4] A diagram illustrating the spatial resolution achieved by a single antenna. [Figure 5] A diagram illustrating the spatial resolution achieved by multiple antennas. [Figure 6] A diagram illustrating an example of the application of a radar system assumed in the embodiment. [Figure 7] A diagram illustrating the relationship between the distance to an object and spatial resolution. [Figure 8] A diagram illustrating the relationship between the distance to an object and spatial resolution. [Figure 9]The diagram for explaining the outline of the operation of the radar system according to the present embodiment. [Figure 10] The diagram showing an example of the configuration of the radar system. [Figure 11] The flowchart showing an example of the processing procedure of the radar system. [Figure 12] The diagram for explaining a comparative example of the present embodiment. [Figure 13] The diagram for explaining a comparative example of the present embodiment. [Figure 14] The diagram for explaining a comparative example of the present embodiment. [Figure 15] The diagram for explaining the radar image obtained in the present embodiment. [Figure 16] The diagram for explaining an example of performing imaging of a target object using a plurality of radar apparatuses. [Figure 17] The diagram showing an example of the result of performing complex domain synthesis and the result of performing image domain synthesis. [Figure 18] The diagram for explaining an example of the radar image synthesis method applied in the present embodiment. [Figure 19] The diagram showing an example of radar image synthesis that combines complex domain synthesis, image domain synthesis, and image combination. [Mode for Carrying Out the Invention]

[0009] Hereinafter, the embodiment will be described with reference to the drawings. The radar system according to the present embodiment is configured to measure the azimuth where the target object is located and the distance to the target object using the reflected wave from the target object of the radar signal transmitted (irradiated) to the target object, and perform imaging of the target object (generate an image). Note that the radar signal transmitted to the target object in such a radar system is a radio wave such as a millimeter wave (EHF: Extra High Frequency), for example.

[0010] Hereinafter, an outline of the radar system will be briefly described. First, as an example of a radar modulation scheme that performs frequency modulation, the FMCW (Frequency Modulated Continuous Wave) scheme will be described.

[0011] According to the FMCW scheme, as shown in Figure 1, a modulated radar signal (transmitted wave) whose frequency changes with the passage of time is transmitted, and the distance to the target object is measured based on the frequency difference (hereinafter referred to as the beat frequency) between the radar signal and the reflected wave signal (received wave) based on the reflected wave of the radar signal.

[0012] Specifically, in the FMCW scheme, an intermediate frequency (IF: Intermediate Frequency) signal (hereinafter referred to as an IF signal) is obtained by mixing the radar signal and the reflected wave signal. This IF signal corresponds to the time waveform (sine wave) of the beat frequency described above. Note that the beat frequency is f b , the slope (frequency change rate) of the radar signal called a chirp rate is γ (Hz / s), and the delay time of the reflected wave signal relative to the radar signal is τ, then the f b , γ and τ have a relationship of f b =γτ.

[0013] When, for example, a Fast Fourier Transform (FFT) is applied to the above-described IF signal, the IF signal is converted into a frequency domain representation. In the result of this FFT, a peak appears at the position of the beat frequency f b , and a distance corresponding to the position of the peak (that is, the distance to the target object that reflected the radar signal) can be obtained.

[0014] Note that the FMCW scheme that performs linear frequency modulation as shown in Figure 1 is particularly referred to as Linear-FMCW.

[0015] Here, the radar system includes a radar device having a transmitting antenna (transmitting element) and a receiving antenna (receiving element), and a MIMO (Multi-Input Multi-Output) radar can be used as the radar device. A MIMO radar has multiple transmitting antennas (transmitting antenna arrays) and multiple receiving antennas (receiving antenna arrays), and each transmitting antenna transmits a radar signal in time division, and multiple receiving antennas receive reflected wave signals based on the reflected waves of the radar signal, thereby enabling the reception of many reflected wave signals (i.e., radar observation) with a small number of radar signal transmissions (i.e., radar irradiations).

[0016] Specifically, as shown in Figure 2, we assume that the MIMO radar has, for example, two transmitting antennas 1a and 1b and four receiving antennas 2a to 2d arranged linearly in a predetermined spatial direction.

[0017] In this case, for example, if a radar signal is transmitted from transmitting antenna 1a, a reflected signal based on the reflected wave of that radar signal is received by receiving antenna 2a. Here, we have described receiving antenna 2a, but the reflected signal based on the reflected wave of the radar signal transmitted from transmitting antenna 1a is similarly received by receiving antennas 2b to 2d.

[0018] Similarly, if, for example, a radar signal is transmitted from transmitting antenna 1b, a reflected signal based on the reflected wave of that radar signal is received by receiving antenna 2a. Although receiving antenna 2a has been described here, reflected signals based on the reflected wave of the radar signal transmitted from transmitting antenna 1b are similarly received by receiving antennas 2b to 2d.

[0019] In other words, in the MIMO radar described above, when a radar signal is transmitted from transmitting antenna 1a, radar observation is performed at each of the receiving antennas 2a to 2d, and similarly when a radar signal is transmitted from transmitting antenna 1b, radar observation is performed at the receiving antennas 2a to 2d.

[0020] According to this, a MIMO radar having two transmitting antennas 1a and 1b and four receiving antennas 2a to 2d, as shown in Figure 2, can realize eight observation points 3a to 3h arranged in the spatial direction by emitting radar signals only once each from transmitting antennas 1a and 1b. For example, observation point 3a is realized when receiving antenna 2a receives a reflected wave signal based on the reflected wave of the radar signal transmitted from transmitting antenna 1a. Similarly, observation points 3b to 3d are realized when receiving antennas 2b to 2d receive reflected wave signals based on the reflected wave of the radar signal transmitted from transmitting antenna 1a. Furthermore, observation point 3e is realized when receiving antenna 2a receives a reflected wave signal based on the reflected wave of the radar signal transmitted from transmitting antenna 1b. Similarly, observation points 3f to 3h are realized when receiving antennas 2b to 2d receive reflected wave signals based on the reflected wave of the radar signal transmitted from transmitting antenna 1b. In other words, in MIMO radar, one observation point is realized by combining one transmitting antenna and one receiving antenna.

[0021] With such a MIMO radar, it becomes possible to measure the distance to an object using the IF signals observed at each of the observation points 3a to 3h (IF signals acquired based on radar signals transmitted in time division from transmitting antennas 1a and 1b and reflected wave signals received by each of the receiving antennas 2a to 2d).

[0022] Incidentally, when the MIMO radar described above is used to image an object in the radar system according to this embodiment, a time difference occurs in the reflected wave signals observed at each observation point. Therefore, the spatial resolution in imaging the object can be improved by calculating the correlation of these reflected wave signals through radar signal processing, for example.

[0023] The following describes the spatial resolution in imaging objects. In the MIMO radar described above, multiple observation points can be realized by combining each of the multiple transmitting antennas and each of the multiple receiving antennas. Each of these observation points can be considered as a single antenna (transmitting antenna) in the radar system that transmits a radar signal and receives a reflected wave signal based on the reflected wave of that radar signal. Therefore, in the following explanation, each of the multiple observation points realized in MIMO radar may be simply referred to as an antenna.

[0024] The azimuth resolution of a radar is defined by the angular resolution, which is determined by the beamwidth of the radio waves transmitted (irradiated) from the transmitting antenna. Here, as shown in Figure 3, the beamwidth is the width (half-power width) in a radar system where the power of the reflected wave signal is half of the peak value. The angular resolution is the resolution that allows two or more objects (targets) to be detected separately in the azimuth direction, depending on the beamwidth.

[0025] The angular resolution achieved in a radar system depends on the antenna aperture length. Specifically, increasing the antenna aperture length narrows the beam width (resulting in a thinner beam) and improves the azimuth resolution. Here, the antenna aperture length corresponds to the size of the antenna's aperture surface.

[0026] Figure 4 shows the angular resolution achievable with a single antenna (observation point). With a single antenna, there are limitations on the aperture length of the antenna that can be operated, making it impossible to perform imaging with high azimuthal resolution.

[0027] On the other hand, Figure 5 shows the angular resolution achieved by multiple antennas. Note that multiple antennas mean, for example, multiple observation points in the case of MIMO radar. In this case, by transmitting and receiving radar signals and reflected wave signals in different spatial coordinates and calculating the correlation between the spatial filter and each reflected wave signal (observation signal) through signal processing, the aperture length of the antenna can be virtually increased, thereby improving the azimuth resolution.

[0028] As shown in Figure 3, the spatial resolution d in this embodiment is assumed to be the angular resolution θ converted to distance (m), and this spatial resolution d changes not only with the antenna aperture length but also with the distance of the object reflecting the radar signal in the direction of radar signal irradiation. For example, the spatial resolution d decreases as the distance to the object increases and improves as the distance to the object decreases.

[0029] Incidentally, in radar systems that perform imaging of an object, the distance to the object is generally set, and then the antenna aperture length and imaging range (field of view) required to achieve the desired spatial resolution are determined. Therefore, when the distance between the antenna and the object in the radar system is constant, the desired spatial resolution can be achieved in imaging of that object.

[0030] However, in radar systems operating in environments where the distance to the object (the distance between the object and the antenna) changes dynamically with each imaging, the range in which reflected wave signals from the object can be received changes, leading to changes in the achieved spatial resolution, the generation of redundant computational processing, and degradation of imaging.

[0031] Here, with reference to Figure 6, an example of the application of the radar system assumed in this embodiment will be briefly described. In this embodiment, the radar system 10 can be applied to a security inspection system installed in facilities such as airports, train stations, shopping malls, concert halls, and exhibition halls.

[0032] As shown in Figure 6, the radar system 10 is equipped with multiple radar modules 3, each having multiple transmitting antennas 1 and multiple receiving antennas 2 corresponding to the MIMO radar described above. In each of the multiple radar modules 3, for example, the multiple transmitting antennas 1 and multiple receiving antennas 2 are arranged in corresponding positions (translation or rotation). Alternatively, for example, the arrangement of the multiple transmitting antennas 1 and multiple receiving antennas 2 in one radar module 3 corresponds to the arrangement of the multiple transmitting antennas 1 and multiple receiving antennas 2 in other radar modules 3, either symmetrically along a line or point-symmetrically.

[0033] The radar system 10 images an object by receiving reflected wave signals based on reflected waves of radar signals transmitted from each of the multiple transmitting antennas 1 provided in each radar module 3 using multiple receiving antennas 2. In this embodiment, when the radar system 10 is applied to a security inspection system, the object being imaged by the radar system 10 is, for example, a person using the facility or an item (personal belongings) that the person possesses.

[0034] The imaging results of a person or an item possessed by such a radar system 10 can be used to determine whether or not the person is possessing dangerous goods.

[0035] Furthermore, the objects being imaged in the radar system 10 applied to the security inspection system may be, for example, luggage being transported on a conveyor belt installed within the facility.

[0036] When imaging an object in such a radar system 10, the distance between the object and the radar module 3 (distance to the object) changes dynamically, which may prevent proper imaging of the object (i.e., it may not be possible to achieve the set spatial resolution).

[0037] Here, referring to Figures 7 and 8, we will explain the relationship between the distance to the object and the spatial resolution. Here, we assume the object is a person.

[0038] Figure 7 illustrates a scenario where the radar system 10 (radar module 3) is designed to achieve a desired spatial resolution for an object 10a located at close range by reducing the antenna aperture length (for example, by reducing the number of observation points realized in a MIMO radar). In such a radar system 10, as shown on the left side of Figure 7, if the object 10a is located close to the radar module 3, the desired spatial resolution can be achieved, but it may not be possible to image (capture) the entire object 10a. On the other hand, as shown on the right side of Figure 7, if the object 10a is located far from the radar module 3, it is possible to image the entire object 10a, but the desired spatial resolution cannot be achieved.

[0039] Figure 8 illustrates a scenario where the radar system 10 (radar module 3) is designed to achieve a desired spatial resolution for a distant object 10a by increasing the antenna aperture length (for example, by increasing the number of observation points realized in a MIMO radar). In such a radar system 10, as shown on the left side of Figure 8, when the object 10a is far away from the radar module 3, the desired spatial resolution can be achieved, and imaging of the entire object 10a is also possible. On the other hand, as shown on the right side of Figure 8, when the object 10a is close to the radar module 3, although the spatial resolution is excessive, the desired spatial resolution can be achieved, and imaging of the entire object 10a is also possible.

[0040] As shown in Figures 7 and 8 above, from the viewpoint of achieving the desired spatial resolution and imaging the entire object 10a, it is preferable to design the radar system 10 to achieve the desired spatial resolution for objects 10a located at a distance (i.e., by increasing the antenna aperture length). However, when the antenna aperture length is increased, compared to when the antenna aperture length is small, it becomes necessary to perform radar signal processing on observation signals (reflected wave signals) observed at more observation points, for example, as realized in MIMO radar, thus increasing the processing load (computation load). Furthermore, when the antenna aperture length is large, there is a possibility that observation signals that do not contribute to imaging of the object 10a may be observed depending on the distance to the object 10a, raising concerns about redundant computation and degradation of imaging.

[0041] Therefore, in this embodiment, a radar system 10 is provided that has a configuration capable of performing appropriate imaging even in environments where the distance to the target object changes dynamically.

[0042] The following describes the general operation of the radar system 10 according to this embodiment, with reference to Figure 9. Figure 9 assumes that an object 10a (for example, a person) is moving toward the radar module 3.

[0043] First, let's assume that the object 10a is located at a distance a from the radar module 3. In this case, the reflected wave signal based on the reflected radar signal from the object 10a can be received by all of the antennas. Therefore, the radar system 10 can achieve the desired spatial resolution by coordinating the operation of all of these antennas to image the object 10a.

[0044] Next, let's assume that the object 10a is located at a distance b from the radar module 3. Here, assuming that the object 10a, as viewed from a vertical direction from the floor of the facility on which the object 10a is moving, has a roughly cylindrical shape, the reflected wave signal based on the reflected wave from the right portion 10b of the object 10a in the direction of movement will be received by the antenna group belonging to the first group 31a among the multiple antennas, but will not be received by antennas other than those belonging to the first group 31a. Also, the reflected wave signal based on the reflected wave from the left portion 10c of the object 10a in the direction of movement will be received by the antenna group belonging to the second group 31b among the multiple antennas, but will not be received by antennas other than those belonging to the second group 31b. In other words, if the object 10a is located at a distance b from the radar module 3, even if all of the antennas provided in the radar module 3 are operated in coordination, the spatial resolution achieved in the radar system 10 will be limited to the range in which the reflected wave signal can be received by the first and second groups 31a and 31b respectively (i.e., the range in which reflections can be picked up), which may result in unnecessary computational processing and degradation of imaging.

[0045] Furthermore, consider the case where the object 10a is located at a distance c from the radar module 3. In this case, the reflected wave signal based on the reflected wave from the right-hand portion 10d of the object 10a in the direction of movement is received by the antennas belonging to the first group 32a among the multiple antennas, but is not received by antennas other than those belonging to the first group 32a. Also, the reflected wave signal based on the reflected wave from the left-hand portion 10e of the object 10a in the direction of movement is received by the antenna group belonging to the second group 32b among the multiple antennas, but is not received by antennas other than those belonging to the second group 32b. In addition, the reflected wave signal based on the reflected wave from the portion 10f corresponding to the direction of movement of the object 10a (i.e., the portion other than the right-hand portion 10d and the left-hand portion 10e) is received by the antenna group belonging to the third group 32c among the multiple antennas, but is not received by antennas other than those belonging to the third group 32c. In other words, if the object 10a is located at a distance c from the radar module 3, even if all of the antennas provided on the radar module 3 are operated in coordination, the spatial resolution achieved in the radar system 10 will be limited to the range in which reflected wave signals can be received by each of the first to third groups 32a to 32c (i.e., the range in which reflections can be picked up), which may result in unnecessary computational processing and degradation of imaging.

[0046] Here, we have described the case where the object has a roughly cylindrical shape, but if the object has a planar shape, for example, the range in which reflected wave signals can be received is likely to be different.

[0047] Therefore, in order to avoid unnecessary computational processing and degradation of imaging, the radar system 10 according to this embodiment operates by grouping and coordinating the multiple antennas provided by the radar module 3 according to the distance to the object (location of the object) and / or the shape of the object (i.e., the object).

[0048] Figure 10 shows an example of the configuration of the radar system 10 according to this embodiment. As shown in Figure 10, the radar system 10 includes a radar device 11, a sensor 12, and a processing unit 13.

[0049] The radar device 11 includes a plurality of antennas configured to transmit radar signals and receive reflected wave signals based on the reflected waves of said radar signals. If the radar device 11 is, for example, a MIMO radar as described above, the plurality of antennas provided in the radar device 11 may be multiple observation points realized by combinations of each of the plurality of transmitting antennas and each of the plurality of receiving antennas in the MIMO radar. Furthermore, the radar device 11 may be configured to mount multiple radar modules, each equipped with multiple antennas (antenna elements) as described in Figure 6, and to operate these multiple radar modules 3 in synchronous manner. Additionally, although only one radar device 11 is shown in Figure 10, the radar device 11 may be composed of multiple radar devices.

[0050] Sensor 12 is configured to measure (detect) the distance to an object and / or the shape of the object. Sensor 12 includes, for example, a distance measuring sensor and a camera.

[0051] The processing unit 13 drives a plurality of antennas provided in the radar device 11 according to the object (distance to the object and / or the shape of the object) and performs imaging of the object. The processing unit 13 may be implemented by hardware such as an IC (Integrated Circuit), by software (a processor such as a CPU or microcontroller executing a predetermined program), or by a combination of hardware and software.

[0052] The processing unit 13 includes a mode determination unit 131, a radar drive unit 132, a grouping unit 133, an imaging unit 134, and a radar image output unit 135.

[0053] The mode determination unit 131 determines the mode for driving the radar device 11 (and the multiple antennas provided therein) based on the measurement results from the sensor 12 (i.e., the object measured by the sensor 12).

[0054] The radar drive unit 132 drives the radar device 11 in the mode determined by the mode determination unit 131. In this case, the radar drive unit 132 sets a group to which each of the multiple antennas provided in the radar device 11 belongs according to the mode determined by the mode determination unit 131, and causes the antenna groups belonging to the set group to operate in coordination. By driving the radar device 11 (multiple antennas), the radar drive unit 132 acquires multiple reflected wave signals (observation signals) received by each of the multiple antennas from the radar device 11.

[0055] The grouping unit 133 groups multiple reflected wave signals acquired by the radar drive unit 132 based on the groups set by the radar drive unit 132.

[0056] The imaging unit 134 performs imaging of the target object based on the reflected wave signals grouped by the grouping unit 133.

[0057] The radar image output unit 135 outputs the imaging result from the imaging unit 134 (i.e., a radar image including the target object).

[0058] Although the radar device 11 and sensor 12 are shown separately in Figure 10, the sensor 12 may be integrated into the radar device 11.

[0059] Furthermore, in the radar system 10, the radar device 11, the sensor 12, and the processing unit 13 may be configured as a single device. On the other hand, the radar device 11, the sensor 12, and the processing unit 13 may each be configured as separate devices. In this case, the processing unit 13 may be located remotely from the radar device 11 and the sensor 12, and may be configured to communicate with the radar device 11 and the sensor 12 via a network.

[0060] The following describes an example of the processing procedure for the radar system 10, referring to the flowchart in Figure 11.

[0061] When imaging an object, the sensor 12 provided in the radar system 10 measures, for example, the distance to the object (step S1). Here, the sensor 12 is integrated with the radar device 11, and the distance measured by the sensor 12 corresponds to the distance between the object and the multiple antennas provided in the radar device 11 (i.e., the distance from the radar device 11 to the object). It is also assumed that the shape of the object (i.e., the object is, for example, a person) is known in advance.

[0062] When the process of step S1 is executed, the processing unit 13 provided in the radar system 10 acquires the distance (data) measured in step S1 from the sensor 12. The mode determination unit 131 included in the processing unit 13 determines the mode for driving the radar device 11 based on the distance acquired by the processing unit 13 (step S2).

[0063] Next, the radar drive unit 132 sets a group to which each of the multiple antennas provided in the radar device 11 belongs, according to the mode determined in step S2 (step S3).

[0064] When the process in step S3 is executed, the radar drive unit 132 drives the radar device 11 to coordinate the operation of the antenna groups belonging to the group set in step S3.

[0065] The processes in steps S2 to S4 will be explained in detail below with reference to Figure 9 mentioned above.

[0066] First, let's assume that the distance measured in step S1 is distance a as shown in Figure 9. In this case, in step S2, the first mode is determined as the mode for driving the radar device 11. Next, in step S3, all of the multiple antennas are set as one group as shown in Figure 9. In this case, in step S4, the radar device 11 is driven to operate all of the multiple antennas in a coordinated manner.

[0067] Next, let's assume that the distance measured in step S1 is distance b shown in Figure 9. In this case, in step S2, the second mode is determined as the mode for driving the radar device 11. Next, in step S3, the first and second groups 31a and 31b shown in Figure 9 are set. The first group 31a includes the first group of antennas selected based on the distance to the object 10a, etc. The second group 31b includes the second group of antennas selected based on the distance to the object 10a, etc. In this case, in step S4, the radar device 11 is driven to operate the first group of antennas in a coordinated manner as the first group 31a, and the second group of antennas in a coordinated manner as the second group 31b.

[0068] Furthermore, let's assume that the distance measured in step S1 is distance c as shown in Figure 9. In this case, in step S2, the third mode is determined as the drive mode for the radar device 11. Next, in step S3, the first to third groups 32a to 32c shown in Figure 9 are set. The first group 32a includes the first antenna group, which is one of several antennas selected based on the distance to the object 10a, etc. The second group 32b includes the second antenna group, which is one of several antennas selected based on the distance to the object 10a, etc. The third group 32c includes the third antenna group, which is one of several antennas selected based on the distance to the object 10a, etc. In this case, in step S4, the radar device 11 is driven to operate the first antenna group in a coordinated manner as the first group 32a, the second antenna group in a coordinated manner as the second group 32b, and the third antenna group as the third group 32c. Distance a is greater than distance b, and distance b is greater than distance c. In other words, the first mode is selected when the distance to the object 10a is greater than or equal to the first predetermined value; the second mode is selected when the distance to the object 10a is less than the first predetermined value but greater than or equal to the second predetermined value; and the third mode is selected when the distance to the object 10a is less than or equal to the second predetermined value. The first predetermined value is a value greater than the second predetermined value, and the first and second predetermined values ​​are determined based on the spatial resolution achieved in the radar system 10.

[0069] Furthermore, if the second or third mode is determined in step S2 as described above, in step S3, the groups shall be set up so that at least some of the antennas are different. In other words, as shown in Figure 9, some antennas may overlap between groups 31a and 31b (the antenna groups belonging to them). Also, as shown in Figure 9, as shown in groups 32a to 32c, there may be no overlap of antennas between groups 32a to 32c (the antenna groups belonging to them).

[0070] Furthermore, the multiple groups (and the antenna groups belonging to each of them) that are set when the second or third mode is determined shall be set based on, for example, the range in which reflected wave signals based on reflected waves from the object can be received (the range in which reflections can be picked up). In this case, since the range in which reflected wave signals based on reflected waves from the object can be received is thought to differ depending on the shape of the object, the multiple groups (and the antenna groups belonging to each of them) that are set when the second or third mode is determined may be set based on the shape of the object. Here, it is explained that the shape of the object is known (knowledged in advance), but if the shape of the object is unknown, the multiple groups may be set based on the shape of the object measured by the sensor 12.

[0071] Furthermore, information indicating the correspondence between the results measured by the sensor 12 (distance to the object and / or the shape of the object) and the modes determined based on those measurement results (e.g., the first to third modes) (hereinafter referred to as mode information) may be pre-stored in, for example, the mode determination unit 131 (or the memory area allocated to it). With such a configuration, the mode determination unit 131 can determine the mode to drive the radar device 11 based on the results measured in step S1 and the mode information.

[0072] Furthermore, information indicating the correspondence between a determined mode and a group (or group of antennas belonging to that mode) set according to that mode (hereinafter referred to as group information) may be pre-stored in, for example, the radar drive unit 132 (or a memory area allocated to it). With such a configuration, the radar drive unit 132 can set a group based on the mode and group information determined in step S2.

[0073] As described above, when the radar device 11 is driven in step S4, the radar drive unit 132 acquires multiple reflected wave signals (observation signals) received by multiple antennas provided in the radar device 11 from the radar device 11. The grouping unit 133 groups the multiple reflected wave signals acquired by the radar drive unit 132 based on groups set by the radar device 11 (step S5). Specifically, the grouping unit 133 performs a process of grouping the reflected wave signals received by the antenna groups belonging to each group set by the radar drive unit 132.

[0074] Once the process in step S5 is executed, the imaging unit 134 performs imaging (cooperative operation imaging) for each of the reflected wave signals grouped in step S5 (i.e., groups set by the radar drive unit 132) (step S6).

[0075] In step S6, radar signal processing is performed to calculate the correlation between the grouped reflected wave signals and the spatial filter (spatial correlation between reflected wave signals). Radar signal processing includes signal processing based on Synthetic Aperture Radar (SAR). SAR is a signal processing technique that achieves high-resolution imaging, similar to observation with a large-aperture antenna, by performing multiple observations while moving a low-resolution, small-aperture antenna and synthesizing the results of these observations. In SAR, high resolution can be achieved by synthesizing the reflected wave signals while aligning the relative distance between each observation point and the target.

[0076] Here, we have briefly explained signal processing based on SAR, but radar signal processing may also be signal processing based on beamforming for direction of arrival estimation, etc.

[0077] Once the radar signal processing described above is performed, the imaging unit 134 can generate a radar image (complex number) that includes the target object.

[0078] When the process in step S6 is executed, the radar image output unit 135 outputs the radar images generated for each group as a result of the process in step S6 (step S7). In this case, the radar image output unit 135 may also output the result of further imaging (i.e., combining) the radar images generated for each group. The radar images output by the radar image output unit 135 may be displayed on a display provided by the radar system 10, for example, or transmitted to a server device or the like outside the radar system 10.

[0079] Furthermore, when the radar system 10 according to this embodiment is applied to the security inspection system described above, the radar image output from the radar system 10 can be used, for example, to determine whether the person being inspected (subject) is concealing dangerous goods. In this case, dangerous goods are just one example of the objects described above, and include, for example, objects that are not permitted to be possessed in the facility (area) where the radar system 10 (security inspection system) is installed. Specific examples of dangerous goods include metals such as handguns and knives, and powders such as explosives. Dangerous goods may also be illegally brought in items such as powders of narcotics or ingots.

[0080] Whether or not the person described above is concealing dangerous goods may be determined by an operator who refers to the radar image, or it may be determined automatically by performing image analysis on the radar image. When it is determined automatically whether or not a person is concealing dangerous goods, the determination process may be performed, for example, within the radar system 10, or on a server device or the like outside the radar system 10.

[0081] Furthermore, the radar image output from the radar system 10 (radar image output unit 135) may be an image that reflects the determination result of whether or not a person is concealing a dangerous object (for example, an image that highlights the dangerous object).

[0082] Furthermore, the process shown in Figure 11 above is executed each time the object moves. This makes it possible to realize a configuration that switches between, for example, the first to third modes depending on the distance to the object.

[0083] As described above, the radar system 10 according to this embodiment includes a plurality of antennas configured to transmit radar signals and receive reflected wave signals based on the reflected waves of the radar signals, and a processing unit 13 that drives the plurality of antennas (a radar device 11) in first and second modes according to the object (for example, the distance to the object).

[0084] In this embodiment, when the processing unit 13 drives multiple antennas in the first mode, it coordinates the operation of the multiple antennas and performs imaging of the target object (coordinated operation imaging) based on the reflected wave signals received by the multiple antennas.

[0085] Furthermore, in this embodiment, when the processing unit 13 drives multiple antennas in the second mode, it causes the first group of antennas to operate in coordination as the first group, and performs imaging of the target object (coordinated operation imaging) based on the reflected wave signals received by the first group of antennas. In addition, the processing unit 13 causes the second group of antennas to operate in coordination as the second group, and performs imaging of the target object (coordinated operation imaging) based on the reflected wave signals received by the second group of antennas. Note that the second group of antennas described above differs from the first group of antennas in at least some of its antennas.

[0086] In this description, multiple antennas are driven in first and second modes depending on the object. However, the processing unit 13 in this embodiment may operate such that, when the distance between the object and the multiple antennas (the radar device 11) is less than a predetermined value, it coordinates the operation of a first group of antennas as a first group and performs imaging of the object based on the reflected wave signals received by the first group of antennas, and then coordinates the operation of a second group of antennas as a second group and performs imaging of the object based on the reflected wave signals received by the second group of antennas.

[0087] In this embodiment, the above-described configuration makes it possible to achieve the desired spatial resolution and perform appropriate imaging of the object even in environments where the distance to the object changes dynamically.

[0088] Here, we assume, for example, that when an object is located 2m away from the radar module (multiple antennas), the radar device 11 is designed to achieve a spatial resolution of 4mm by driving the radar device 11 in the first mode described above (i.e., by coordinating the operation of all of the multiple antennas).

[0089] In this case, assuming that the object moves to a position 1m away from the radar module, the radar device 11 is driven in the second mode described above, causing, for example, the antenna group belonging to the first group 31a shown in Figure 9 to operate in coordination, and the antenna group belonging to the second group 31b to operate in coordination. As a result, although the number of antennas to operate in coordination (antenna aperture length) is roughly halved, the distance to the object is also halved, so a spatial resolution of 4mm can be achieved in imaging performed for each group.

[0090] Furthermore, assuming that the object moves to a position 0.66m away from multiple antennas, driving the radar device 11 in the third mode described above allows, for example, the antenna group belonging to the first group 32a shown in Figure 9 to operate in coordination, the antenna group belonging to the second group 32b to operate in coordination, and the antenna group belonging to the third group 32c to operate in coordination. As a result, the number of antennas operating in coordination (antenna aperture length) is reduced to 1 / 3, and the distance to the object is also reduced to approximately 1 / 3, so that a spatial resolution of 4mm can be achieved in imaging performed for each group.

[0091] In other words, in this embodiment, a predetermined spatial resolution can be achieved by dynamically selecting a group of antennas that perform coordinated motion imaging according to the distance to the object (i.e., the position of the object).

[0092] Furthermore, in this embodiment, multiple antennas are grouped together in a range where reflected wave signals that do not contribute to imaging the target object are not received (i.e., reflected wave signals based on reflected waves from the target object can be received), thus making it possible to avoid unnecessary computational processing and degradation of imaging.

[0093] In this embodiment, the configuration drives multiple antennas in first and second modes depending on the object. However, in this embodiment, the mode in which the multiple antennas are driven may be determined according to the distance to the object (position of the object) or according to the shape of the object (type of object). Furthermore, the mode in which the multiple antennas are driven may be determined according to both the distance to the object and the shape of the object. That is, in this embodiment, for example, the first and second modes (or first to third modes) can be switched according to at least one of the distance to the object (distance between the object and the multiple antennas) and the shape of the object. The distance to the object and the shape of the object are to be measured by the sensor 12 (distance measuring sensor or camera, etc.).

[0094] Furthermore, the mode for driving the multiple antennas in this embodiment may be determined according to the spatial resolution specified for imaging the object (i.e., the spatial resolution for the object). In this case, the multiple antennas should be grouped in such a way that the specified spatial resolution can be achieved. The specified spatial resolution may be a single value or one of several ranges.

[0095] Furthermore, in this embodiment, the radar device 11 may be configured to have multiple radar modules, with some of the multiple antennas provided on the first radar module and the other parts of the multiple antennas provided on the second radar module which is spaced apart from the first radar module. In this case, for example, the group of antennas provided on the first radar module may be called the first group, and the group of antennas provided on the second radar module may be called the second group. Note that the radar device 11 may also be configured to have only a single radar module.

[0096] Furthermore, the radar device 11 may consist of multiple radar devices (for example, a first and a second radar device). In this case, for example, multiple antennas (antenna groups) provided in the first radar device may be referred to as the first group, and multiple antennas (antenna groups) provided in the second radar device may be referred to as the second group.

[0097] Furthermore, the radar system 10 according to this embodiment may be configured to drive the radar device 11 (multiple antennas) in at least the first and second modes depending on the object, but it may also be configured to drive the radar device 11 in the first to third modes, as explained in Figure 9, or it may be configured to drive the radar device 11 in four or more modes.

[0098] Incidentally, as described above, in this embodiment, the radar images generated for each group may be further imaged (i.e., radar image synthesis). Such imaging methods (synthesis methods) include complex domain synthesis (cooperative operation imaging of complex domains), image domain synthesis (cooperative operation imaging of image domains), and image merging.

[0099] Complex domain synthesis is an imaging technique that takes multiple radar images (complex numbers) as input and outputs the result of combining them in a complex domain. Complex domain synthesis is expected to further increase the resolution of radar images.

[0100] Image region synthesis is an imaging technique that takes multiple radar images (complex numbers) as input, calculates the absolute value (amplitude) of each, and outputs the result of synthesizing them in the amplitude region. In image region synthesis, complex numbers are not combined with each other, so even if the distance to the object is short (the object is close), for example, image degradation does not occur, and the signal-to-noise ratio of the image is improved (i.e., noise can be suppressed). In addition, image region synthesis can reduce the computational load compared to complex region synthesis.

[0101] Image stitching is an imaging technique that takes multiple radar images (complex numbers) as input, calculates the absolute value (amplitude) of each, and then stitches the images together in a spatially continuous manner.

[0102] Here, in order to reduce the computational complexity of the BP (Back-Projection) method, which is a radar signal processing method for increasing resolution, we consider a configuration (hereinafter referred to as the comparative example of this embodiment) in which, when multiple observation signals (reflected wave signals) are received, only the signals that contribute significantly to imaging the target object (contributing data) are extracted, and a radar image (radar image of the target object) is generated by performing a convolutional process between the contributing data and reference data (matched filter).

[0103] In the comparative example of this embodiment, only the antennas important for imaging the object are dynamically selected from all observed signals, and the spatial correlation in the complex domain is calculated. This is expected to enable imaging of the object while reducing the computational load, even when the distance to the object fluctuates.

[0104] However, in the comparative example of this embodiment, if a transmit-receive separate antenna system such as MIMO radar (i.e., a configuration with separate transmitting and receiving antennas) is adopted, the image quality may deteriorate or the desired resolution may not be achieved even if the contribution is high, under conditions where the spherical wave, which is the radar wave, cannot be sufficiently approximated as a plane wave. This frequently occurs in environments where the distance to the target object is very short (near-field), such as the security inspection system (millimeter-wave security) described above.

[0105] Here, a comparative example of this embodiment will be described, in which a MIMO radar configuration consisting of transmitting antennas 1a and 1b and receiving antennas 2a to 2z as shown in Figure 12 is employed. In this comparative example of this embodiment, as shown in Figure 13, when the distance to the object is sufficiently large (the object is sufficiently far away), radar signal processing is performed on the observation signal 1 obtained by the irradiation of the radar signal by transmitting antenna 1a and the observation signal 2 obtained by the irradiation of the radar signal by transmitting antenna 1b, thereby obtaining a suitable imaging result of the object, and achieving a desired spatial resolution in the imaging result.

[0106] Next, referring to Figure 14, we will describe the spatial resolution when the comparative example of this embodiment is applied in an environment where the distance to the object is very short, as described above.

[0107] In this case, Figure 14 shows observation signals 1 and 2, which have a high contribution (high correlation value) as reflection components from the object. However, according to Figure 14, as described above, spherical waves cannot be sufficiently approximated as plane waves. Therefore, even if radar image 1, which is generated by performing radar signal processing on observation signal 1, and radar image 2, which is generated by performing radar signal processing on observation signal 2, are combined, the object image will be split into multiple parts, and the object cannot be properly imaged.

[0108] On the other hand, when this embodiment is applied in an environment where the distance to the object is very short, the desired spatial resolution can be achieved in both the radar image 1 (i.e., imaging using only observation signal 1) generated by performing radar signal processing (calculating the spatial correlation of each observation signal in the complex domain) on the observation signal 1 received by the first group (the group of transmitting antenna 1a and receiving antennas 2a to 2m), and the radar image 2 (i.e., imaging using only observation signal 2) generated by performing radar signal processing (calculating the spatial correlation of each observation signal in the complex domain) on the observation signal 2 received by the second group (the group of transmitting antenna 1b and receiving antennas 2n to 2z). In this embodiment, by performing complex domain synthesis or image domain synthesis (or image merging) on ​​the radar images 1 and 2 thus generated, it is possible to reduce the amount of computation while avoiding degradation of the image. Note that Figure 15 assumes that image domain synthesis is performed on radar images 1 and 2.

[0109] Furthermore, this embodiment may also be applied when imaging an object using multiple radar devices (MIMO radars), as shown in Figure 16. In Figure 16, for example, the transmitting antennas 1a and 1b and receiving antennas 2a to 2z provided in the first radar device (first MIMO radar) 11a are referred to as the first group, and the transmitting antennas 1a' and 1b' and receiving antennas 2a' to 2z' provided in the second radar device (second MIMO radar) 11b are referred to as the second group. Also, Figure 16 assumes that there are three objects a to c.

[0110] In this case, as shown in Figure 17, the radar image 1 (imaging result 1) generated by performing radar signal processing on the observation signal 1 received by the first group through observation by the first radar device 11a, and the radar image (imaging result 2) generated by performing radar signal processing on the observation signal 2 received by the second group through observation by the second radar device 11b, are combined (i.e., coordinated operation imaging is performed between the groups).

[0111] In this case, for example, the complex region synthesis or image region synthesis described above can be selected as the coordinated motion imaging method.

[0112] Here, as described above, when there are three objects a to c, the first and second radar images generated by performing radar signal processing on the first and second groups fail to properly image objects located far from each of the first and second groups. Specifically, object c disappears in radar image 1, and object a disappears in radar image 2.

[0113] When complex domain synthesis is performed on these first and second radar images, an improvement in spatial resolution can be obtained. Furthermore, since objects that were previously missing appear in the complex domain synthesis result, a reduction in blind spots can also be achieved.

[0114] On the other hand, when image region synthesis is performed on the first and second radar images, the effect of reducing the noise level can be obtained. In addition, since the disappearing objects reappear as a result of image region synthesis, it is also possible to obtain a blind spot reduction effect.

[0115] In other words, when combining the first and second radar images to image the three objects a to c shown in Figures 16 and 17 above, either complex region synthesis or image region synthesis may be used.

[0116] Now, referring to Figure 18, we will describe an example of a radar image synthesis method that is applicable when the radar system 10 is operated in an environment where an object 10a (for example, a person) moves toward the radar module 3, as explained in Figure 9 above.

[0117] As shown in Figure 18, for example, if an object (person) 10a is located at a distance a from the radar module 3, the radar module 3 is configured to operate all of its antennas as a single group, and a radar image is generated by calculating the spatial correlation in the complex domain for the observation signals between each antenna.

[0118] On the other hand, if, for example, an object (person) 10a is located at a distance b from the radar module 3, the first and second groups of antennas among the multiple antennas provided in the radar module 3 are made to operate in coordination as the first groups 31a and 31b. In this case, a first radar image is generated by calculating the spatial correlation in the complex domain for the observation signals between each antenna in the first group 31a. A second radar image is generated by calculating the spatial correlation in the complex domain for the observation signals between each antenna in the second group 31b. When combining the first and second radar images thus generated, a combined radar image can be generated by applying, for example, image region synthesis (coordinated operation imaging of the image region) to the first and second radar images.

[0119] Furthermore, if, for example, an object (person) 10a is located at a distance c from the radar module 3, the first to third antennas among the multiple antennas provided on the radar module 3 are made to operate in coordination as the first to third groups 32a to 32c. In this case, a first radar image is generated by calculating the spatial correlation in the complex domain for the observation signals between each antenna in the first group 32a. A second radar image is generated by calculating the spatial correlation in the complex domain for the observation signals between each antenna in the second group 32b. A third radar image is generated by calculating the spatial correlation in the complex domain for the observation signals between each antenna in the third group 32c. When combining the first to third radar images generated in this way, a combined radar image can be generated by applying, for example, image region synthesis (coordinated operation imaging of image regions) to the first to third radar images.

[0120] Although this description assumes that image region synthesis is applied to multiple radar images (cooperative imaging of image regions is performed between multiple groups), this embodiment may be configured to apply complex region synthesis, image region synthesis, or image merging selected according to, for example, the object (distance to the object, shape of the object, or spatial resolution relative to the object).

[0121] In other words, in this embodiment, as described above, by applying complex domain synthesis, image domain synthesis, or image merging to multiple radar images generated by performing radar signal processing on the observation signals (reflected wave signals) received in each of the multiple groups, it becomes possible to obtain a composite radar image with higher accuracy.

[0122] In this embodiment, a combination of the complex region synthesis, image region synthesis, and image merging described above may be used to obtain a composite radar image.

[0123] Figure 19 shows an example of a combination of complex region synthesis, image region synthesis, and image merging that can be applied in this embodiment. In Figure 19, it is assumed that imaging of an object is performed using radar modules 301 to 304 (equipped with radar device 11).

[0124] In the example shown in Figure 19, multiple antennas provided in the radar module 301 are operated in coordination as a single group, and radar image A is generated by performing radar signal processing on the observation signals (reflected wave signals) received by these multiple antennas.

[0125] Furthermore, the multiple antennas provided in the radar module 302 are divided into two groups, and radar signal processing is performed on the observation signals (reflected wave signals) received in each of the two groups (the antenna groups belonging to each group) to generate two radar images. By further performing complex domain synthesis on these two radar images, radar image B is generated.

[0126] Furthermore, the radar module 303 is divided into two groups, and radar signal processing is performed on the observation signals (reflected wave signals) received by each of the two groups (the antenna groups belonging to each group) to generate two radar images. By performing image region synthesis on these two radar images, radar image C is generated.

[0127] Furthermore, the radar module 304 is equipped with multiple antennas which are divided into two groups, and radar signal processing is performed on the observation signals (reflected wave signals) received in each of the two groups (the antenna groups belonging to each group) to generate two radar images, and the radar image D is generated by combining these two radar images.

[0128] Furthermore, the example shown in Figure 19 demonstrates that radar image AB is generated by further complex region synthesis of radar images A and B described above. It also demonstrates that radar image CD is generated by further image region synthesis of radar images C and D described above.

[0129] In this embodiment, it is also possible to configure the system to repeatedly perform multiple synthesis processes (complex region synthesis, image region synthesis, and image merging) as shown in Figure 19 until a single image is obtained.

[0130] In this description, we have explained a configuration in which multiple radar images are synthesized by coordinating the operation of antenna groups for each group. However, the radar system 10 according to this embodiment only needs to be configured to drive the multiple antennas provided by the radar device 11 in first and second modes according to the object (i.e., to divide the multiple antennas used for high-resolution imaging into groups), and the radar image synthesis process does not necessarily have to be performed in the radar system 10 according to this embodiment (i.e., it may be performed by an external device of the radar system 10, etc.).

[0131] Furthermore, although this embodiment has described a MIMO radar system equipped with multiple transmitting antennas and multiple receiving antennas as the radar system 11, the radar system 11 may also be configured such that multiple transmitting and receiving antennas are arranged to transmit radar signals and receive reflected wave signals based on the reflected waves of said radar signals.

[0132] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0133] With regard to the embodiments described above, the following additional information is disclosed. [1] Multiple antennas configured to transmit radar signals and receive reflected signals based on the reflected waves of said radar signals, A processing unit that drives the plurality of antennas in first and second modes depending on the object, It is equipped with, The aforementioned processing unit, When the plurality of antennas are driven in the first mode, the plurality of antennas are operated in coordination, and imaging of the object is performed based on the reflected wave signals received by the plurality of antennas. When the plurality of antennas are driven in the second mode, the first group of antennas is operated in coordination as the first group, and imaging of the object is performed based on the reflected wave signal received by the first group of antennas, and the second group of antennas is operated in coordination as the second group, and imaging of the object is performed based on the reflected wave signal received by the second group of antennas. The aforementioned second antenna group differs from the aforementioned first antenna group in at least some of its antennas. Radar system. [2] Some of the aforementioned multiple antennas are provided in the first radar module, The other parts of the aforementioned plurality of antennas are provided in a second radar module, which is positioned at a distance from the first radar module. [1] The radar system described. [3] Some of the aforementioned multiple antennas are provided in the first radar device, The other parts of the aforementioned plurality of antennas are provided in a second radar device, which is different from the first radar device. [1] The radar system described. [4] The radar system according to any one of the following [1] to [3], wherein the processing unit performs further imaging based on the imaging result of the object based on the reflected wave signal received by the first antenna group and the imaging result of the object based on the reflected wave signal received by the second antenna group. [5] When the processing unit drives the plurality of antennas in the third mode, it performs imaging of the object based on the reflected wave signal received by the first antenna group, performs imaging of the object based on the reflected wave signal received by the second antenna group, and operates the third antenna group of the plurality of antennas in a coordinated manner as the third group, and performs imaging of the object based on the reflected wave signal received by the third antenna group. The third antenna group differs from the first and second antenna groups in at least some of its antennas. A radar system as described in any one of the items [1] to [4]. [6] The radar system according to any one of [1] to [5], wherein the first and second modes are switched depending on the distance between the object and the plurality of antennas or the shape of the object. [7] The radar system according to [6] further comprising sensors for measuring the distance between the object and the plurality of antennas or the shape of the object. [8] The radar system according to [7], wherein the processing unit switches the first and second modes based on mode information indicating the correspondence between the measurement result and the mode determined based on the measurement result. [9] The first mode is selected when the distance between the object and the plurality of antennas is greater than or equal to a first predetermined value. If the distance between the object and the plurality of antennas is less than the first predetermined value and greater than or equal to the second predetermined value, the second mode is selected. If the distance between the object and the plurality of antennas is less than the second predetermined value, the third mode is selected. The first predetermined value is a value greater than the second predetermined value, The first and second predetermined values ​​are determined based on the spatial resolution achieved in the radar system. [5] The radar system described.

[10] Multiple antennas configured to transmit radar signals and receive reflected signals based on the reflected waves of said radar signals, A processing unit that, when the distance between the object and the plurality of antennas is less than a predetermined value, causes the first group of antennas to operate in coordination as the first group, and performs imaging of the object based on the reflected wave signal received by the first group of antennas, and causes the second group of antennas to operate in coordination as the second group, and performs imaging of the object based on the reflected wave signal received by the second group of antennas, and It is equipped with, The aforementioned second antenna group differs from the aforementioned first antenna group in at least some of its antennas. Radar system. [Explanation of Symbols]

[0134] 10...Radar system, 11...Radar device, 12...Sensor, 13...Processing unit, 131...Mode determination unit, 132...Radar drive unit, 133...Grouping unit, 134...Imaging unit, 135...Radar image output unit.

Claims

1. Multiple antennas configured to transmit radar signals and receive reflected signals based on the reflected waves of said radar signals, A processing unit that drives the plurality of antennas in first and second modes according to the object, It is equipped with, The aforementioned processing unit, When the plurality of antennas are driven in the first mode, the plurality of antennas are operated in coordination, and imaging of the object is performed based on the reflected wave signals received by the plurality of antennas. When the plurality of antennas are driven in the second mode, the first group of antennas is operated in coordination as the first group, and imaging of the object is performed based on the reflected wave signal received by the first group of antennas, and the second group of antennas is operated in coordination as the second group, and imaging of the object is performed based on the reflected wave signal received by the second group of antennas. The second antenna group differs from the first antenna group in at least some of its antennas. When the processing unit drives the plurality of antennas in the third mode, it coordinates the operation of the third antenna group among the plurality of antennas as the third group, and performs imaging of the object based on the reflected wave signal received by the third antenna group; it coordinates the operation of the fourth antenna group among the plurality of antennas as the fourth group, and performs imaging of the object based on the reflected wave signal received by the fourth antenna group; it coordinates the operation of the fifth antenna group among the plurality of antennas as the fifth group, and performs imaging of the object based on the reflected wave signal received by the fifth antenna group; The third to fifth antenna groups differ from each other in at least some of their antennas. If the distance between the object and the plurality of antennas is greater than or equal to a first predetermined value, the first mode is selected. If the distance between the object and the plurality of antennas is less than the first predetermined value and greater than or equal to the second predetermined value, the second mode is selected. If the distance between the object and the plurality of antennas is less than the second predetermined value, the third mode is selected. The first predetermined value is a value greater than the second predetermined value. The first and second predetermined values ​​are determined based on the spatial resolution achieved in the radar system. Radar system.

2. Some of the aforementioned multiple antennas are provided in the first radar module. The other parts of the aforementioned plurality of antennas are provided in a second radar module, which is positioned at a distance from the first radar module. The radar system according to claim 1.

3. Some of the aforementioned multiple antennas are provided in the first radar device, The other parts of the aforementioned plurality of antennas are provided in a second radar device, which is different from the first radar device. The radar system according to claim 1.

4. The radar system according to claim 1, wherein the first to third modes are switched according to the distance between the object and the plurality of antennas or the shape of the object.

5. The radar system according to claim 4, further comprising a sensor for measuring the distance between the object and the plurality of antennas or the shape of the object.

6. The radar system according to claim 5, wherein the processing unit switches the first to third modes based on mode information indicating the correspondence between the measured result and the mode determined based on the measured result.

Images