Detection device, detection system and program

Abstract

To provide a detection device capable of reducing a calculation amount for identifying a location of a detection target.SOLUTION: According to one embodiment, a detection device comprises a first radar unit, a second radar unit, a data processing unit, and a determination unit. The first radar unit transmits radar signals. The second radar unit receives the radar signals. The data processing unit processes radar information acquired by the second radar unit, and outputs a first value representing a relation between signal strength and a first distance determined by a distance between the first radar unit and the second radar unit. The determination unit determines that a target object is present at a position between the first radar unit and the second radar unit when the first value output from the data processing unit is equal to or less than a threshold value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a detection device, a detection system, and a program. [Background technology]

[0002] A system has been proposed that uses multiple radar transceivers (UWB: Ultra Wide Band) to receive direct line-of-sight pulses and pulses reflected from a target, and uses the channel impulse response (CIR) data obtained from both of these pulses to determine the time delay between the time of flight of the direct line-of-sight signal and the time of flight of the reflected signal, thereby locating and tracking the target. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-536216 Summary of the Invention [Problem to be solved by the invention]

[0004] In the system of Patent Document 1, in order to identify the target's location, it is necessary to analyze the CIR obtained from both the line-of-sight signal and the target's reflected signal using a relatively computationally intensive process.

[0005] An object of the present invention is to provide a detection device, a detection system, and a detection method that can reduce the amount of calculation required to identify the position of a detection target. [Means for solving the problem]

[0006] According to an embodiment, a detection device includes a first radar unit, a second radar unit, a data processing unit, and a determination unit. The first radar unit transmits a radar signal. The second radar unit receives the radar signal. The data processing unit processes radar information acquired by the second radar unit and outputs a first value representing a relationship between a first distance determined by the distance between the first radar unit and the second radar unit and signal strength. If the first value output from the data processing unit is equal to or less than a threshold, the determination unit determines that an object is present at a position between the first radar unit and the second radar unit. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a detection system according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing an application example of the detection device of the first embodiment. [Figure 3] FIG. 1 is a diagram showing an example of the configuration of a detection device according to a first embodiment. [Figure 4] FIG. 10 is a diagram showing an example of radar information after range FFT processing. [Figure 5] 4 is a flowchart showing an example of a processing flow of the detection system of the first embodiment. [Figure 6] FIG. 10 is a diagram showing an example of the configuration of a detection device according to a second embodiment. [Figure 7] FIG. 2 is a diagram showing an example of the waveform of an FMCW signal. [Figure 8] FIG. 2 is a diagram showing an example of a received signal. [Figure 9] FIG. 10 is a diagram showing an example of a reflection intensity distribution. [Figure 10] 10 is a flowchart showing an example of a processing flow of a detection system according to a second embodiment. [Figure 11] FIG. 10 is a diagram showing an example of the configuration of a detection device according to a third embodiment. [Figure 12] FIG. 10 is a diagram showing an example of the configuration of a detection device according to a fourth embodiment. [Figure 13] FIG. 10 is a diagram showing an example of the configuration of a detection device according to a fifth embodiment. [Figure 14] FIG. 13 is a diagram showing an example of the configuration of a detection device according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. The following description exemplifies devices and methods for embodying the technical concepts of the embodiments. The technical concepts of the embodiments are not limited to the structures, shapes, arrangements, materials, etc. of the components described below. Modifications that can be easily conceived by those skilled in the art are naturally included within the scope of the disclosure. For clarity of explanation, the drawings may schematically depict elements with different sizes, thicknesses, planar dimensions, shapes, etc., compared to the actual embodiment. Elements with different dimensional relationships or ratios may be included in multiple drawings. Corresponding elements may be designated by the same reference numerals in multiple drawings, and redundant description may be omitted. Some elements may be designated by multiple names, but these designations are merely examples and do not necessarily mean that these elements may be designated by other names. Furthermore, elements that do not have multiple names may also be designated by other names. In the following description, "connection" may include not only direct connection but also connection via other elements.

[0009] (First embodiment) First, the first embodiment will be described.

[0010] FIG. 1 is a diagram showing an example of the configuration of a detection system 100 according to the first embodiment.

[0011] The detection system 100 includes a detection device 1 and a display device 2. The detection device 1 and the display device 2 are connected to each other by wire or wirelessly.

[0012] The detection device 1 detects whether or not a detection target is present within the detection range. If a detection target is present within the detection range, the detection device 1 can also identify the position of the detection target. The detection device 1 of the first embodiment is equipped with a unique method that can significantly reduce the amount of calculation required to identify the position of the detection target compared to conventional methods. The unique method equipped in the detection device 1 will be described in detail below.

[0013] The display device 2 displays the detection results of the detection device 1. The display device 2 of the first embodiment displays, for example, whether or not a detection target has been detected, the position of the detection target, and the like.

[0014] Fig. 2 is a diagram showing an application example of the detection device 1. Here, as shown in Fig. 2, a situation is assumed in which a detection target 53 enters and leaves a space (detection range) 52 in which a plurality of radars 51 are arranged. The radars 51 operate synchronously under the control of a synchronization unit 13, which will be described later, and a radar signal transmitted by one radar 51 can be received by the other radars 51. Note that each radar 51 may also autonomously transmit radar signals and acquire radar information at predetermined timings, without being controlled by the synchronization unit 13, which will be described later.

[0015] Radar normally obtains information such as the position, size, and material of an object by analyzing the backscattered signal from the object. There are various existing methods for this analysis, and for example, by performing direction of arrival estimation processing, it is possible to analyze from which direction the backscattered signal from the object is arriving.

[0016] However, if the target position is completely unknown, the analysis range must be sufficiently wide, which results in a relatively large amount of calculation.On the other hand, if the target position can be narrowed down to a certain extent, the amount of calculation can be reduced by analyzing only the expected range.

[0017] Against this background, the detection device 1 of the first embodiment is provided with a unique method for easily identifying the position of an object. The solid double-headed arrows in Fig. 1 represent straight lines connecting different radars 51. As mentioned above, radars can obtain various information by using backscattered signals from an object, so conventionally, signals that are not backscattered from an object but are directly incident on another radar from one radar have hardly been utilized.

[0018] 1 , assuming a situation in which radars 51 are arranged and a detection target 53 passes through a space (detection range) 52, when the detection target 53 exists between two radars 51, the line of sight between the two radars 51 is obstructed. As a result, the signal power drops significantly compared to when the detection target 53 does not exist. Therefore, the detection device 1 of the first embodiment uses this information to detect the presence of the detection target 53 between the two radars 51.

[0019] FIG. 3 is a diagram showing an example of the configuration of the detection device 1 of the first embodiment.

[0020] The detection device 1 of the first embodiment has a first radar unit 11, a second radar unit 12, a synchronization unit 13, a data processing unit 14, and a line-of-sight determination unit 15. The data processing unit 14 and the line-of-sight determination unit 15 are realized, for example, by the CPU 30 executing a program. Alternatively, the data processing unit 14 and the line-of-sight determination unit 15 may be realized by hardware such as an electrical circuit. Note that solid arrows represent the flow of electrical signals, and dashed arrows represent the flow of radar signals.

[0021] The first radar unit 11 is a device that transmits a radar signal. The first radar unit 11 is, for example, a frequency modulated continuous wave (FMCW) radar. The first radar unit 11 is, for example, one radar 51 that is selected at a certain point in time from the multiple radars 51 shown in FIG. 1 , sequentially and cyclically selected one by one at predetermined intervals by the synchronization unit 13. The first radar unit 11 can also receive its own transmitted radar signal that is reflected by a detection target 53, similar to the usage of a general radar.

[0022] The second radar unit 12 is a device that receives radar signals. The second radar unit 12 is, for example, an FMCW radar. The second radar unit 12 is, for example, one of the multiple radars 51 shown in FIG. 1 other than the radar 51 selected as the first radar unit 11 by the synchronization unit 13. The radar signal from the radar 51 selected as the first radar unit 11 can be received by all the other radars 51. The radar signals received by these radars can include signals that are attenuated by being obstructed by the detection target 53 and signals that are reflected by the detection target 53.

[0023] For example, during a period in which a certain radar 51 is selected as the first radar section 11, the radar 51 to be applied as the second radar section 12 is selected one by one at a predetermined interval by the synchronization section 13 from among all or some of the other radars 51.

[0024] The synchronization unit 13 is a device for causing the first radar unit 11 and the second radar unit 12 to operate cooperatively. More specifically, the synchronization unit 13 instructs the first radar unit 11 as to when to transmit a radar signal, and instructs the second radar unit 12 as to when to acquire radar information. As described above, when each radar 51 operates autonomously, the synchronization unit 13 is not necessary.

[0025] For example, as shown in FIG. 1, when multiple radars 51 that can be selected as the first radar unit 11 or the second radar unit 12 are arranged in the detection range 52, the synchronization unit 13 can set a combination of two radars 51, namely, a radar 51 to be used as the first radar unit 11 and a radar 51 to be used as the second radar unit 12, in accordance with a predetermined rule or arbitrarily.

[0026] The data processing unit 14 is a device that processes radar information acquired by the second radar unit 12 when the first radar unit 11 transmits a radar signal. For example, the data processing unit 14 performs a fast Fourier transform (FFT) process (range FFT process) on the radar information to calculate the signal strength of the radar signal corresponding to the distance between the first radar unit 11 and the second radar unit 12.

[0027] The line-of-sight determination unit 15 determines whether the first radar unit 11 and the second radar unit are in a line-of-sight (LOS) state where they can see each other directly, or whether they are in a non-line-of-sight (NLOS) state where they cannot see each other directly, based on the signal strength calculated by the data processing unit 14. In other words, the line-of-sight determination unit 15 determines whether a detection target 53 exists between the first radar unit 11 and the second radar unit.

[0028] Here, with reference to FIG. 4, an example of a method by which the line-of-sight determining unit 15 determines whether or not the detection target 53 exists in a position between the first radar unit 11 and the second radar unit will be described.

[0029] In the case of FMCW radar, it is possible to classify the distance to a reflector by performing range FFT processing on the acquired radar information.

[0030] FIG. 4 is a diagram showing an example of radar information after range FFT processing.

[0031] The graph in FIG. 4(a) shows data after range FFT processing when no target is present between radar A and radar B.

[0032] In this case, the signal strength at the point corresponding to half the distance between radar A and radar B (dist(A,B)) is very high.

[0033] On the other hand, the graph at the bottom shows the case where the target is between the relevant radars, and it can be seen that the signal strength in the area corresponding to dist(A,B) / 2 is significantly lower than in the LOS state.

[0034] From the above, as shown in FIG. 4, by setting an appropriate threshold, LOS / NLOS determination can be realized very easily.

[0035] FIG. 5 is a flowchart showing an example of the processing flow of the detection system 100 of the first embodiment.

[0036] First, under the control of the synchronization unit 13, radar transmission and reception is performed between the first radar unit 11 and the second radar unit 12 (S101). The radar transmission and reception in S101 is performed sequentially at a predetermined interval, for example, the number of all patterns of combinations of two radars 51 among the multiple radars 51, or twice that number (when radar transmission and reception are performed by switching the transmitting and receiving sides).

[0037] The data processing unit 14 performs FFT processing on the radar information acquired by the second radar unit 12 (S102). Next, the line-of-sight determination unit 15 observes the signal power corresponding to the distance between the target radars (half the distance between the radars) based on the radar information after range FFT processing (S103). If the power value is equal to or less than the threshold (S103: Yes), the line-of-sight determination unit 15 determines that the state is NLOS and identifies that the target is located between the relevant radars.

[0038] The detection result of the detection device 1 is supplied to the display device 2, and the display device 2 displays the detection result of the detection device 1 (S104). The display device 2 in the first embodiment displays, for example, the position of the detection target.

[0039] Previous methods identified the target's location by analyzing the CIR obtained from both the line-of-sight signal and the target's reflected signal, which requires a relatively computationally intensive process, and did not distinguish between LOS / NLOS variations and utilize this information for target location estimation.

[0040] In contrast, the detection device 1 of the first embodiment acquires the radar signal reflection characteristics of a target within a certain range under conditions where multiple radars operating in cooperation exist. If the signal strength of the line of sight between the radars is equal to or greater than a threshold, the detection device 1 determines that the target is LOS, and if the signal strength of the line of sight is equal to or less than the threshold, the detection device 1 determines that the target is NLOS. In the case of NLOS, the detection device 1 can detect that the target is located between the corresponding radars. In other words, the position of the target can be identified.

[0041] Furthermore, the radar information after range FFT processing by the data processing unit 14 is the same as that used in the object classification process (more specifically, the pre-processing arrival direction estimation process) in the second embodiment described later, so data processing for LOS / NLOS detection by the line-of-sight / non-line-of-sight determination unit 15 can be performed without particularly increasing the amount of data processing.

[0042] As described above, the detection device 1 of the first embodiment can identify the position of the target by determining whether the signal strength is equal to or less than the threshold value. In other words, the detection device 1 of the first embodiment can reduce the amount of calculation required to identify the position of the detection target.

[0043] (Second embodiment) Next, a second embodiment will be described.

[0044] FIG. 6 is a diagram showing an example of the configuration of a detection device 1-2 according to the second embodiment.

[0045] Compared to the detection device 1 of the first embodiment, the detection device 1-2 of the second embodiment further includes a detection target classifying unit 16. The detection target classifying unit 16 is realized, for example, by the CPU 30 executing a program. Alternatively, the detection target classifying unit 16 may be realized by hardware such as an electric circuit.

[0046] The radar information used in the LOS / NLOS detection process by the line-of-sight determination unit 15 described in the first embodiment is data that is also used when performing general radar data processing (e.g., direction-of-arrival estimation processing), and is not additional data generated solely for performing the LOS / NLOS detection process. Furthermore, the fact that the LOS / NLOS detection process reveals that an object exists between radars means that the position of the object is limited to a certain extent. Therefore, for example, it is possible to limit the area to be focused on when performing object classification processing based on the result of direction-of-arrival estimation processing.

[0047] The detection target classification unit 16 receives the results of the direction of arrival estimation processing from the data processing unit 14 and the results of the LOS / NLOS detection processing from the line-of-sight determination unit 15, and performs object classification processing while limiting the area to be noted, thereby identifying the type of detection target.

[0048] Here, an example of the object classification process performed by the detection object classifying unit 16 will be described with reference to FIGS.

[0049] 7 is a diagram showing an example of the waveform of an FMCW signal used in the detection device 1-2. The FMCW signal is also called a chirp signal.

[0050] When the amplitude A of a chirp signal is expressed as a function of time t, it becomes as shown in Figure 7(a). When the frequency f of a chirp signal is expressed as a function of time t, it becomes as shown in Figure 7(b). As shown in Figure 7(b), a chirp signal is represented by a center frequency fc, a modulation bandwidth fb, and a signal time width Tb. The slope of a chirp signal is called the frequency change rate (chirp rate) γ.

[0051] The transmission wave St(t) of the FMCW signal transmitted by the first radar unit 11 is expressed by Equation 1. St(t)=cos[2π(fct+γt 2 / 2)] … Formula 1

[0052] The chirp rate γ is expressed by Equation 2. γ=fb / Tb … Formula 2

[0053] At this time, the reflected wave from an object a distance R away from the first radar unit 11 is observed with a delay of Δt = 2R / c from the transmission timing, where c is the speed of light. The received signal Sr(t) is expressed by Equation 3, where a is the reflection intensity from the object. Sr(t)=a·cos[2πfc(t-Δt)+πγ(t-Δt) 2 ] … Formula 3

[0054] FIG. 8 is a diagram showing an example of a received signal when a plurality of, for example, three objects are present.

[0055] Figure 8(a) shows the relationship between the transmitted signal / received signal and time. As shown in Figure 8(a), the frequency of the transmitted signal changes linearly over time. The received signal is delayed by Δt relative to the transmitted signal. When there are multiple objects, the reflected wave from the nearest object is received first, as shown by the dashed line, and the reflected wave from the farthest object is received last, as shown by the dashed line.

[0056] The received signal is multiplied by the transmitted signal in the data processing unit 14, and then frequency components higher than the cutoff frequency are attenuated. The signal obtained as a result is called an IF signal z(t) and is expressed by Equation 4. z(t)=a·cos(2πΔtγt) … Equation 4

[0057] Figure 8(b) shows the relationship between the frequency of the IF signal and time. In an ideal noise-free environment, the frequency of each reflected wave is constant. Here, the frequency of the reflected wave from the nearest object is the lowest, as shown by the dashed line, and the frequency of the reflected wave from the farthest object is the highest, as shown by the dashed-dotted line.

[0058] The reflection intensity in the frequency domain can be calculated by performing FFT on the time domain IF signal z(t) shown in Equation 4 in the data processing unit 14. Therefore, the amplitude at each point in the frequency domain, which is the result of the FFT of the IF signal, corresponds to the reflection intensity for each distance from the radar. The relationship between frequency and distance from the radar is expressed by Equation 5. f if =Δtγ=2Rγ / c … Equation 5

[0059] If the distance to the person is n meters, then from Equation 5, the frequency f of the IF signal corresponding to the point at distance R = n meters if By calculating the reflection intensity of the received signal, the frequency f if The reflection intensity can be extracted as the reflection intensity of the object.

[0060] The reflection intensity can be expressed as a heat map that shows the relationship between the reception angle by the radar and the distance from the radar by performing direction-of-arrival estimation processing, which is a common radar processing. By looking at the change in reflection intensity along the distance direction (scanning direction) in the heat map, information about the object can be obtained.

[0061] FIG. 9 is a diagram showing an example of the reflection intensity distribution obtained by the detection device 1-2. As shown in Figure 9, the distribution of the reflection intensity of radio waves along the scanning line varies depending on the material that reflects the radio waves.

[0062] Figure 9(a) shows the reflection intensity distribution of radio waves when a person is not carrying anything. In this case, the radio waves are reflected by the person's skin, so the reflection intensity of the radio waves does not change and the reflection intensity distribution is flat. The reflection intensity distribution in Figure 9(a) is a standard reflection intensity distribution corresponding to standard test results.

[0063] Figure 9(b) shows the distribution of radio wave reflection intensity when a person is holding a handgun (metal) in the center of the scanning direction. In this case, metal has a higher reflection intensity than skin, so the reflection intensity of radio waves is also high. The horizontal axis represents reflection intensity (higher reflection intensity on the right), so the reflection intensity of radio waves is distributed in a convex shape to the right.

[0064] Figure 9(c) shows the distribution of radio wave reflection intensity when a person is holding an explosive in the center of the scanning direction. Because explosives absorb radio waves better than skin, the radio wave reflection intensity is lower and the distribution of radio wave reflection intensity is convex to the left.

[0065] In this way, by determining the shape of the reflection intensity distribution from the reflection intensities acquired at a plurality of points on the scanning line, the detection object classifying unit 16 can identify the type of detection object. Furthermore, the data used for LOS / NLOS determination can be directly used to perform direction-of-arrival estimation, which is a general radar data processing method, and then the shape of the reflection intensity distribution can be determined by displaying the result as a heat map. In other words, LOS / NLOS determination does not require any complex processing other than general radar data processing.

[0066] FIG. 10 is a flowchart showing an example of the processing flow of the detection system 100 according to the second embodiment.

[0067] Steps S101 to S103 are the same as those in the first embodiment. In step S103, if the power value is equal to or less than the threshold value (S103: Yes), in the second embodiment, the data processing unit 14 executes a direction-of-arrival estimation process (S201). Subsequently, the detection target classification unit 16 executes a target classification process using the result of the direction-of-arrival estimation process to identify the type of the detection target (S202).

[0068] As in the first embodiment, the detection result of the detection device 1-2 is supplied to the display device 2, and the display device 2 displays the detection result of the detection device 1 (S104). The display device 2 in the second embodiment can, for example, display the type of the detection target in addition to the position of the detection target.

[0069] As described above, the detection device 1-2 of the second embodiment can limit the target range of the direction-of-arrival estimation process based on the LOS / NLOS detection process performed by the line-of-sight / non-line-of-sight determination unit 15. Furthermore, by limiting the area of interest during the object classification process, the process can be simplified. Alternatively, if the detection result of the LOS / NLOS detection is LOS, it is determined that no object is present in the radar intercept position, eliminating the need for radar data processing within that range. In this respect, the detection device 1-2 of the second embodiment can also reduce the amount of data processing and processing time. In this way, the detection device 1-2 of the second embodiment can directly use the information used for LOS / NLOS determination in the detection object classification process, thereby eliminating unnecessary processing. Accordingly, the display device 2 connected to the detection device 1-2 of the second embodiment can further display the type of detection object.

[0070] (Third embodiment) Next, a third embodiment will be described.

[0071] FIG. 11 is a diagram showing an example of the configuration of a detection device 1-3 according to the third embodiment.

[0072] In the first and second embodiments, the first radar unit 11 performs a transmitting operation, and the second radar unit 12 performs a receiving operation. In contrast, in the detection device 1-3 of the third embodiment, the first radar unit 11 and the second radar unit 12 each perform both a transmitting operation and a receiving operation. In Fig. 11, the dashed double-headed arrow between the first radar unit 11 and the second radar unit 12 represents the flow of radar signals in both directions.

[0073] That is, in the detection device 1-3 of the third embodiment, the first radar unit 11 transmits a radar signal and the second radar unit 12 acquires radar information, and the second radar unit 12 transmits a radar signal and the first radar unit 11 acquires radar information.

[0074] In the detection device 1-3 of the third embodiment, the data processing unit 14 processes not only the output from the second radar unit 12 but also the output from the first radar unit 11. More specifically, the data processing unit 14 further performs range FFT processing on the radar information acquired by the first radar unit 11. In addition, the line-of-sight determination unit 15 receives each signal strength from the data processing unit 14 and performs LOS / NLOS detection processing in both directions.

[0075] As a result, the detection device 1-3 of the third embodiment can improve detection accuracy compared to the first and second embodiments.

[0076] (Fourth embodiment) Next, a fourth embodiment will be described.

[0077] FIG. 12 is a diagram showing an example of the configuration of a detection device 1-4 according to the fourth embodiment.

[0078] 12, the detection device 1-4 of the fourth embodiment has a third radar unit 17 in addition to the first radar unit 11 and the second radar unit 12. The third radar unit 17 is also connected to the synchronization unit 13, and all the radars (the first radar unit 11, the second radar unit 12, and the third radar unit 17) operate in synchronization with each other.

[0079] More specifically, the synchronization unit 13 in the fourth embodiment instructs the first radar unit 11 as to when to transmit a radar signal, and instructs the second radar unit 12 and the third radar unit 17 as to when to acquire radar information.

[0080] In the detection device 1-4 of the fourth embodiment, the data processing unit 14 processes not only the output from the second radar unit 12 but also the output from the third radar unit 17. More specifically, the data processing unit 14 further performs range FFT processing on the radar information acquired by the third radar unit 17. In addition, the line-of-sight determination unit 15 receives each signal strength from the data processing unit 14 and performs LOS / NLOS detection processing for two points: one between the first radar unit 11 and the second radar unit 12, and the other between the first radar unit 11 and the third radar unit 17.

[0081] In this way, the detection device 1-4 of the fourth embodiment can simultaneously perform LOS / NLOS detection at two points.

[0082] Furthermore, in the detection device 1-4 of the fourth embodiment, when the presence of an object is detected and the process of identifying the type of object described above is executed, the object is limited to the area where NLOS was detected out of the two locations. This makes it possible to reduce the amount of data processing and the processing time in the detection device 1-4 of the fourth embodiment as well.

[0083] Here, an example has been shown in which one third radar unit 17 is added as a radar for acquiring radar information, but this is not limited to this, and it is also possible to add two or more radars and perform LOS / NLOS detection at three or more points simultaneously.

[0084] (Fifth embodiment) Next, a fifth embodiment will be described.

[0085] FIG. 13 is a diagram showing an example of the configuration of a detection device 1-5 according to the fifth embodiment.

[0086] The detection device 1-5 of the fifth embodiment further includes a target speed estimation unit 18, as compared with the detection device 1-4 of the fourth embodiment. The target speed estimation unit 18 is realized, for example, by the CPU 30 executing a program. Alternatively, the target speed estimation unit 18 may be realized by hardware such as an electric circuit.

[0087] The target speed estimation unit 18 estimates the speed of the detection target 53 using the LOS / NLOS detection results of two points by the line-of-sight determination unit 15. Assuming that the detection target 53 is moving at a substantially constant speed, the target speed estimation unit 18 can estimate the approximate speed of the detection target 53 from the time interval between when the two points change to NLOS.

[0088] In this way, the detection device 1-5 of the fifth embodiment can estimate not only the rough position of the detection target 53 but also the speed of the detection target 53. Accordingly, the display device 2 connected to the detection device 1-5 of the fifth embodiment can further display the speed of the detection target 53.

[0089] (Sixth embodiment) Next, a sixth embodiment will be described.

[0090] FIG. 14 is a diagram showing an example of the configuration of a detection device 1-5 according to the sixth embodiment.

[0091] The detection device 1-6 of the sixth embodiment further includes an object dimension estimation unit 19, as compared with the detection device 1-4 of the fourth embodiment. The object dimension estimation unit 19 is realized, for example, by the CPU 30 executing a program. Alternatively, the object dimension estimation unit 19 may be realized by hardware such as an electric circuit.

[0092] The object size estimation unit 19 estimates the size of the detection object 53 using the LOS / NLOS detection results at two points by the line-of-sight determination unit 15. If NLOS detection at a first point is followed by NLOS detection at a second point without interruption, the object size estimation unit 19 can estimate that the size of the detection object 53 is at least equal to or greater than the distance from the first point to the second point.

[0093] In this way, the detection device 1-6 of the sixth embodiment can estimate not only the rough position of the detection target 53 but also the dimensions of the detection target 53. Accordingly, the display device 2 connected to the detection device 1-6 of the sixth embodiment can further display the dimensions of the detection target 53.

[0094] The methods of the above-described embodiments are examples in which the detection target is a human and is used to determine whether the human is carrying a dangerous object. However, the present invention is not limited to this example, and the fifth embodiment and the method described in the fifth embodiment can also be used to estimate the speed and dimensions of a train or the like.

[0095] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0096] 1...detection device, 2...display device, 11...first radar section, 12...second radar section, 13...synchronization section, 14...data processing section, 15...line of sight / non-line of sight determination section, 16...detection object classification section, 17...third radar section, 18...object speed estimation section, 19...object size estimation section, 51...radar, 52...detection range, 53...detection object, 100...detection system.

Claims

1. a first radar unit that transmits a radar signal; a second radar unit that receives a radar signal; a data processing unit that processes radar information acquired by the second radar unit and outputs a first value that represents a relationship between a first distance determined by a distance between the first radar unit and the second radar unit and a signal strength; a determination unit that determines that an object is present at a position between the first radar unit and the second radar unit when the first value output from the data processing unit is equal to or smaller than a threshold value; A detection device comprising:

2. The detection device according to claim 1 , further comprising a synchronization unit that causes the first radar unit and the second radar unit to operate in coordination with each other.

3. The detection device according to claim 1 , further comprising a detection object classifying unit that identifies the type of the object based on the first value output from the data processing unit and used in the determination unit.

4. the first radar unit and the second radar unit are frequency modulated continuous wave (FMCW) radars, The data processing unit performs a fast Fourier transform (FFT) process on the radar information to obtain FFT data and outputs the FFT data as the first value. The detection device of claim 1 .

5. The detection device according to claim 1 , wherein the first distance is half the distance between the first radar unit and the second radar unit.

6. the second radar unit is capable of transmitting a radar signal, the first radar unit is capable of receiving a radar signal, The data processing unit processes the radar information acquired by the first radar unit and outputs a second value representing a relationship between the first distance and a signal strength. The detection device of claim 1 .

7. a third radar unit for receiving a radar signal; the data processing unit processes the radar information acquired by the third radar unit, and outputs a third value representing a relationship between a second distance determined by a distance between the first radar unit and the third radar unit and a signal strength; the determination unit determines that an object is present at a position between the first radar unit and the third radar unit when the third value output from the data processing unit is equal to or smaller than a threshold value. The detection device of claim 1 .

8. a detection object classifying unit that identifies the type of the object based on the first value or the third value output from the data processing unit and that is used in the determination unit; The detection object classification unit when it is determined that an object is present at a position between the first radar unit and the second radar unit, identifying the type of the object using only the first value of the first value and the third value; when it is determined that an object is present at a position between the first radar unit and the third radar unit, identifying the type of the object using only the third value of the first value and the third value; The detection device of claim 7.

9. 8. The detection device according to claim 7, further comprising a speed estimation unit that estimates the speed of the object based on the difference between the time when it is determined that the object is present at a position between the first radar unit and the second radar unit and the time when it is determined that the object is present at a position between the first radar unit and the third radar unit, and the distance between the position between the first radar unit and the second radar unit and the position between the first radar unit and the third radar unit.

10. 8. The detection device according to claim 7, further comprising: a dimension estimation unit that, when it is determined that the object is present at a position between the first radar unit and the third radar unit, estimates the dimension of the object to be equal to or greater than the distance between a position between the first radar unit and the second radar unit and a position between the first radar unit and the third radar unit, when it is continuously determined that the object is present between the first radar unit and the second radar unit.

11. A detection device according to any one of claims 1 to 6; a display device; Equipped with The display device displays the position of the object detected by the detection device. Detection system.

12. A detection device according to claim 7 or 8; a display device; Equipped with the display device displays the position of the object detected by the detection device and the type of the object identified by the detection device. Detection system.

13. A detection device according to claim 9; a display device; Equipped with the display device displays the position of the object detected by the detection device and the velocity of the object estimated by the detection device. Detection system.

14. The detection device according to claim 10; a display device; Equipped with the display device displays the position of the object detected by the detection device and the size of the object estimated by the detection device. Detection system.

15. Computer, transmitting a radar signal by a first radar unit; receiving the radar signal by a second radar unit; processing the radar information acquired by the second radar unit to acquire a first value representing a relationship between a first distance determined by a distance between the first radar unit and the second radar unit and a signal strength; If the first value is equal to or smaller than a threshold value, it is determined that an object is present at a position between the first radar unit and the second radar unit. A program to make it work like this.

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