Moving object detection system, processing device, and computer program

Abstract

To improve the detection accuracy of a moving object based on radar principles.SOLUTION: A transmitting antenna 11 transmits radio waves W toward a detection area 20. A first receiving antenna 121 receives, at a first position P1, the radio waves W arriving from the detection area 20, and outputs a first detection signal S1 corresponding to radio wave intensity at the first position P1. A second receiving antenna 122 receives, at a second position P2, the radio waves W arriving from the detection area 20, and outputs a second detection signal S2 corresponding to radio wave intensity at the second position P2. A processing device 13 estimates the presence or absence of a moving object 30 in the detection area 20 based on an index value corresponding to the magnitude of directional statistical variance related to a phase difference between the first detection signal S1 and the second detection signal S2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a moving object detection system. The present disclosure also relates to a processing device that can be included in the system and a computer program executable by a processor mounted on the device.

Background Art

[0002] Patent Document 1 discloses a technique for estimating the presence or absence of a moving object in a detection area from a signal corresponding to the reception intensity of radio waves arriving from the detection area based on the radar principle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a need to improve the detection accuracy of moving objects based on the radar principle.

Means for Solving the Problems

[0005] One example aspect provided by the present disclosure is a moving object detection system, a transmission antenna that transmits radio waves toward a detection area, a first reception antenna that receives radio waves arriving from the detection area at a first position and outputs a first detection signal corresponding to the radio wave intensity at the first position, a second reception antenna that receives radio waves arriving from the detection area at a second position and outputs a second detection signal corresponding to the radio wave intensity at the second position, a processing device that estimates the presence or absence of a moving object in the detection area based on an index value corresponding to the magnitude of the statistical dispersion in the direction related to the phase difference between the first detection signal and the second detection signal, is provided with.

[0006] One of the example aspects provided by the present disclosure is a processing device, a processor that causes a transmission antenna to transmit radio waves toward a detection area, an interface that receives a first detection signal corresponding to the radio wave intensity at a first position from a first reception antenna that receives radio waves arriving from the detection area at the first position, and receives a second detection signal corresponding to the radio wave intensity at a second position from a second reception antenna that receives radio waves arriving from the detection area at the second position, and is provided with, the processor estimates the presence or absence of a moving object in the detection area based on an index value corresponding to the magnitude of the directional statistical variance related to the phase difference between the first detection signal and the second detection signal.

[0007] One of the example aspects provided by the present disclosure is a computer program executable by a processor mounted on a processing device, which, when executed, causes the processing device to cause a transmission antenna to transmit radio waves toward a detection area, receive a first detection signal corresponding to the radio wave intensity at a first position from a first reception antenna that receives radio waves arriving from the detection area at the first position, receive a second detection signal corresponding to the radio wave intensity at a second position from a second reception antenna that receives radio waves arriving from the detection area at the second position, and estimate the presence or absence of a moving object in the detection area based on an index value corresponding to the magnitude of the directional statistical variance related to the phase difference between the first detection signal and the second detection signal.

[0008] The inventors of the present application have found that the magnitude of the statistical variance of the phase difference generated between the radio waves transmitted from the transmission antenna and received by the first receiving antenna and the second receiving antenna correlates with the presence or absence of a moving object in the detection area. Since the phase difference can be obtained regardless of the reception intensity of the radio wave by defining different first and second positions, by estimating the presence or absence of a moving object based on the index value corresponding to the magnitude of the variance, the influence of the fluctuation of the reception intensity of the radio wave on moving object detection can be suppressed. Therefore, the detection accuracy of a moving object based on the radar principle can be improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 6

Embodiments for Carrying Out the Invention

[0010] While referring to the accompanying drawings, examples of embodiments will be described in detail below. In each of the drawings used in the following description, the scale is appropriately changed in order to make each element recognizable in size.

[0011] FIG. 1 illustrates the functional configuration of a moving object detection system 10 according to an exemplary embodiment. The moving object detection system 10 is configured to detect a moving object 30 located within a detection area 20 based on the radar principle.

[0012] The moving object detection system 10 includes a transmission antenna 11. The transmission antenna 11 is configured to transmit a radio wave W toward the detection area 20. The frequency of the radio wave W can be determined as appropriate. The radio wave W according to this example has a frequency classified as a microwave.

[0013] The moving object detection system 10 includes a first reception antenna 121. The first reception antenna 121 is configured to receive the radio wave W arriving from the detection area 20 at the first position P1. That is, the first reception antenna 121 is configured to have sensitivity to the frequency of the radio wave W.

[0014] The first reception antenna 121 is configured to output a first detection signal S1 corresponding to the radio wave intensity at the first position P1. The first detection signal S1 may be an analog signal or a digital signal according to the specifications of the first reception antenna 121.

[0015] The moving object detection system 10 includes a second reception antenna 122. The second reception antenna 122 is configured to receive the radio wave W arriving from the detection area 20 at a second position P2 different from the first position P1. That is, the second reception antenna 122 is also configured to have sensitivity to the frequency of the radio wave W.

[0016] The second reception antenna 122 is configured to output a second detection signal S2 corresponding to the radio wave intensity at the second position P2. The second detection signal S2 may be an analog signal or a digital signal according to the specifications of the second reception antenna 122.

[0017] The moving object detection system 10 includes a processing device 13. The processing device 13 includes an input interface 131, a processor 132, and an output interface 133.

[0018] The input interface 131 is configured as a hardware interface capable of receiving a first detection signal S1 and a second detection signal S2. When each of the first detection signal S1 and the second detection signal S2 is an analog signal, the input interface 131 includes an appropriate conversion circuit including an A / D converter.

[0019] The processor 132 is configured to output a transmission control signal TC for causing the transmission antenna 11 to transmit the radio wave W from an output interface 133 configured as a hardware interface. The transmission control signal TC includes information capable of specifying the time point at which the radio wave W is transmitted to the transmission antenna 11.

[0020] The transmission control signal TC may be an analog signal or a digital signal according to the specification of the transmission antenna 11. When the transmission control signal TC is an analog signal, the output interface 133 includes an appropriate conversion circuit including a D / A converter. This description is similarly applicable to other signals that can be output from the output interface 133 described later.

[0021] The processor 132 is configured to execute a process of estimating the presence or absence of the moving body 30 in the detection area 20 based on the first detection signal S1 and the second detection signal S2. The details of the process will be described with reference to FIGS. 2 and 3.

[0022] The processor 132 of the processing device 13 causes the transmission antenna 11 to repeatedly transmit the radio wave W by outputting the transmission control signal TC from the output interface 133. The radio wave W is reflected by an object existing in the detection area 20 and received by the first reception antenna 121 and the second reception antenna 122.

[0023] The processor 132 specifies the I component and the Q component of the radio wave W received by the first reception antenna 121 based on the first detection signal S1 output from the first reception antenna 121. The specified I component and Q component correspond to one point in the complex coordinate plane illustrated in FIG. 2.

[0024] For all radio waves W transmitted from the transmission antenna 11 and received by the first reception antenna 121, the I component and the Q component are specified, whereby a first data set is acquired. The first data set corresponds to a first point distribution D1 formed on the complex coordinate plane. Similar processing is performed on the second detection signal S2 output from the second reception antenna 122, whereby a second data set is acquired. The second data set corresponds to a second point distribution D2 formed on the complex coordinate plane.

[0025] When there is a moving body 30 that vibrates periodically within the detection region 20, a periodic variation occurs in the time until the reflected radio wave W reaches the first reception antenna 121 and the second reception antenna 122. As a result, each of the first point distribution D1 and the second point distribution D2 exhibits an arc shape on the complex coordinate plane.

[0026] Subsequently, the processor 132 calculates the average value of the Q coordinate values and the average value of the I coordinate values of all the points forming the first point distribution D1. This process corresponds to specifying the average position AP1 in the first point distribution D1. Similarly, the processor 132 calculates the average value of the Q coordinate values and the average value of the I coordinate values of all the points forming the second point distribution D2. This process corresponds to specifying the average position AP2 in the second point distribution D2.

[0027] Subsequently, the processor 132 performs processing corresponding to the operation of moving each of the average position AP1 and the average position AP2 to the origin O of the complex coordinate plane on each of the first data set and the second data set.

[0028] As described above, since the transmission control signal TC output from the processing device 13 includes information related to the time when the radio wave W is transmitted from the transmission antenna 11, the processor 132 can identify which point in the complex coordinate plane is obtained by the radio wave W transmitted at which time point. Thereby, the processor 132 can identify the data acquired along with the reception of the same radio wave W from each of the first data set and the second data set. This process corresponds to identifying the point p1 included in the first point distribution D1 and the point p2 included in the second point distribution D2 in the complex coordinate plane.

[0029] The two identified data correspond to the reception states at the first position P1 and the second position P2 of the radio wave W transmitted from the transmission antenna 11 at a certain time point. Since the first position P1 and the second position P2 are different, a phase difference occurs between the radio wave W received by the first reception antenna 121 and the radio wave W received by the second reception antenna 122. The processor 132 acquires information corresponding to this phase difference. Specifically, this information can be acquired by identifying the angle θ formed by the point p1 and the point p2 around the origin O of the complex coordinate plane.

[0030] By specifying the phase difference as described above for all the radio waves W transmitted from the transmission antenna 11, the processor 132 acquires time-series data TS indicating the relationship between the time when the radio wave W is received and the phase difference.

[0031] FIG. 3 illustrates the result of performing the above-described process when the moving body 30 does not exist in the detection area 20. Each of the first point distribution D1 and the second point distribution D2 in the complex coordinate plane exhibits a more aggregated form than when the periodically vibrating moving body 30 exists. The identification of the average position in each point distribution, the movement operation to the coordinate origin, the identification of the angle θ corresponding to the phase difference, and the acquisition of the time-series data TS are also performed in the same manner as the example described with reference to FIG. 2, but the illustration of the angle θ is omitted.

[0032] The processor 132 obtains an index value corresponding to the magnitude of the statistical variance of the phase difference included in the time-series data TS. Examples of the index value include, in addition to the value of the variance itself, functions of the variance, the standard deviation, functions of the standard deviation, and the like. As can be seen from the comparison between FIGS. 2 and 3, the variance of the phase difference values is larger when there is no moving object 30 in the detection area 20. Therefore, when the processor 132 obtains an index value corresponding to a situation where the magnitude of the variance is below a threshold value, it estimates that there is a moving object 30 in the detection area 20.

[0033] The inventors of the present application have found that the magnitude of the statistical variance of the phase difference generated between the radio wave W transmitted from the transmission antenna 11 and received by the first reception antenna 121 and the second reception antenna 122 correlates with the presence or absence of the moving object 30 in the detection area 20. Since the phase difference can be obtained regardless of the reception intensity of the radio wave W if different first position P1 and second position P2 are defined, by estimating the presence or absence of the moving object 30 based on the index value corresponding to the magnitude of the variance, the influence of the fluctuation of the reception intensity of the radio wave W on the moving object detection can be suppressed. Therefore, the detection accuracy of the moving object based on the radar principle can be improved.

[0034] Each of the first detection signal S1 output from the first reception antenna 121 and the second detection signal S2 output from the second reception antenna 122 includes information corresponding to the elapsed time from when the radio wave W is transmitted from the transmission antenna 11 until it is received. The elapsed time corresponds to the distance to the object that reflected the radio wave W.

[0035] FIGS. 4 and 5 illustrate the relationship between the above-mentioned elapsed time and the index value obtained as described above. The index value according to this example is defined as the reciprocal of the magnitude of the variance of the phase difference values. Therefore, it corresponds to a situation where the larger the value, the smaller the variance. FIG. 4 corresponds to the case where there is a moving object 30 in the detection area 20 (the time-series data TS illustrated in FIG. 2). FIG. 5 corresponds to the case where there is no moving object 30 in the detection area 20 (the time-series data TS illustrated in FIG. 3).

[0036] The processor 132 may be configured to estimate the distance to the moving object 30 based on the elapsed time since the radio wave W associated with each indicator value was transmitted. In this example, as illustrated in FIG. 4, the distance corresponding to the elapsed time during which the indicator value exceeds a predetermined threshold Th is specified as the distance to the moving object 30.

[0037] As illustrated in FIG. 1, the transmission antenna 11, the first reception antenna 121, and the second reception antenna 122 may be supported by a common substrate 14. Examples of the substrate 14 include a circuit board on which these antenna elements can be mounted.

[0038] When the first reception antenna 121 and the second reception antenna 122 approach the transmission antenna 11 to such an extent that they are supported by the common substrate 14, as illustrated in FIG. 1, a phenomenon called loopback may occur in which a part W’ of the radio wave transmitted from the transmission antenna 11 flows into the first reception antenna 121 and the second reception antenna 122 without passing through the detection region 20. In this case, observation results may be obtained as if there is an object in the region corresponding to the short distance indicated by the hatching in FIGS. 4 and 5.

[0039] As can be seen from FIGS. 4 and 5, in the indicator value corresponding to the magnitude of the directional statistical variance of the phase difference of the radio wave W received by the first reception antenna 121 and the second reception antenna 122, the influence of loopback can be ignored, so the detection accuracy of the moving object 30 based on the radar principle can be further improved. In addition, since additional circuits and processes for removing the phenomenon caused by loopback can be made unnecessary, the complication of the moving object detection system 10 can be suppressed.

[0040] As illustrated in FIG. 6, the moving object detection system 10 may be mounted on a vehicle 40. In this case, the detection region 20 is set to include the interior of the passenger compartment 41 of the vehicle 40. The vehicle 40 is an example of a moving object. The passenger compartment 41 is an example of a living room.

[0041] According to such a configuration, the moving body 30 located in the passenger compartment 41 can be detected. If the moving body 30 is a living body, body movements associated with vital signs (such as heartbeat and breathing) having periodicity can be detected as the moving body 30. Thereby, for example, it becomes possible to estimate a state where a child or a pet has been left unattended in the passenger compartment 41.

[0042] As illustrated in FIG. 1, when it is estimated that the moving body 30 exists in the detection area 20 based on the first detection signal S1 and the second detection signal S2, the processor 132 of the processing device 13 may be configured to output a control signal CT from the output interface 133. The control signal CT is configured to cause the controlled device 50 to perform a predetermined operation. Examples of the controlled device 50 include a notification device, a communication device, and the like.

[0043] For example, when it is estimated that a child or a pet has been left unattended in the passenger compartment 41, at least one of visual notification and auditory notification may be made to the user or the surroundings of the vehicle 40 by the notification device mounted on the vehicle 40. Examples of the notification method include sounding the horn of the vehicle 40, turning on all the lighting devices of the vehicle 40, moving to a place where people are present by automatic driving, and the like. In addition to or instead of this, the communication device mounted on the vehicle 40 may notify the mobile device carried by the user of the vehicle 40 of the estimated fact. An image taken inside the passenger compartment 41 may be transmitted together with the notification of the fact.

[0044] In addition to or instead of the above notification, an intervention process for changing the environment inside the passenger compartment 41 may be performed. Examples of the intervention process include automatically controlling air conditioning equipment (heating and cooling), opening the window of the vehicle 40, unlocking the door of the vehicle 40, opening the door of the vehicle 40, opening and closing the sunshade, and the like.

[0045] The processor 132 having the various functions described so far can be realized by a general-purpose microprocessor that operates in cooperation with a general-purpose memory. Examples of the general-purpose microprocessor can include a CPU, an MPU, and a GPU. Examples of the general-purpose memory can include a ROM and a RAM. In this case, a computer program for realizing the function can be stored in the ROM. The ROM is an example of a non-transitory computer-readable medium storing a computer program. The general-purpose microprocessor designates at least a part of the computer program stored on the ROM and expands it onto the RAM, and executes the above-described processing in cooperation with the RAM. The above computer program may be pre-installed in the general-purpose memory, or may be downloaded from an external server via a communication network and installed in the general-purpose memory. In this case, the external server is an example of a computer-readable medium storing a computer program.

[0046] The processor 132 may also be realized by an application-specific integrated circuit capable of executing the above computer program, such as a microcontroller, an ASIC, or an FPGA. In this case, the above computer program is pre-installed in a storage element included in the application-specific integrated circuit. The storage element is an example of a computer-readable medium storing a computer program. The processor 132 may also be realized by a combination of a general-purpose microprocessor and an application-specific integrated circuit.

[0047] Each configuration described so far is merely an example for facilitating the understanding of the present disclosure. Each configuration example can be appropriately modified and combined with other configuration examples without departing from the spirit of the present disclosure.

[0048] In the above-described embodiment example, two receiving antennas are assigned to one transmitting antenna 11. However, the number of receiving antennas assigned to one transmitting antenna 11 may be three or more. If a plurality of receiving antennas are assigned to one transmitting antenna 11, the number of transmitting antennas 11 included in the moving body detection system 10 may be two or more.

[0049] Alternatively, if a single receiving antenna can obtain the phase difference of the radio wave W by moving at high speed between the first position P1 and the second position P2, the single receiving antenna can be assigned to the transmitting antenna 11. In this case, the single receiving antenna located at the first position P1 is an example of the first receiving antenna, and the single receiving antenna located at the second position P2 is an example of the second receiving antenna.

[0050] The form of the vehicle 40 in FIG. 6 is merely illustrative. The number of seats and wheels in the vehicle 40 on which the moving body detection system 10 is mounted can be determined as appropriate. Note that the moving body detection system 10 does not necessarily have to be mounted on the vehicle 40. Examples of other moving bodies on which the moving body detection system 10 is mounted include railways, airplanes, ships, and the like. The moving body does not necessarily require a driver. The position and size of the detection area 20 can be determined as appropriate according to the type of the moving body.

[0051] The moving body detection system 10 does not necessarily have to be mounted on a moving body. The moving body detection system 10 can be installed in an appropriate house, facility, equipment, etc. The position and size of the detection area 20 can be determined as appropriate according to the installation location and the type of the moving body 30 to be detected. That is, the moving body 30 does not necessarily have to be a living body. Also, the moving body 30 does not necessarily have to exhibit periodic displacement.

[0052] Each of the configurations listed below also constitutes a part of the present disclosure. Item 1: A transmitting antenna that transmits radio waves toward the detection area, and A first receiving antenna that receives radio waves arriving from the detection area at a first position and outputs a first detection signal corresponding to the radio wave intensity at the first position; A second receiving antenna that receives radio waves arriving from the detection area at a second position and outputs a second detection signal corresponding to the radio wave intensity at the second position; A processing device that estimates the presence or absence of a moving object in the detection area based on an index value corresponding to the magnitude of the statistical variance in the direction related to the phase difference between the first detection signal and the second detection signal; and is provided with a moving object detection system. Item 2: The processing device estimates the distance to the moving object based on the elapsed time since the radio wave associated with the index value was transmitted. The moving object detection system according to Item 1. Item 3: The transmitting antenna, the first receiving antenna, and the second receiving antenna are supported on a common substrate. The moving object detection system according to Item 1 or 2. Item 4: When the presence of the moving object is estimated in the detection area, the processing device causes a controlled device to perform a predetermined operation. The moving object detection system according to any one of Items 1 to 3. Item 5: The moving object is a living body. The moving object detection system according to any one of Items 1 to 4. Item 6: The detection area is set to include the interior of the room of the moving object. The moving object detection system according to any one of Items 1 to 5. Item 7: The radio wave has a frequency classified as a microwave. The moving object detection system according to any one of Items 1 to 6.

Description of Signs

[0053] 10: Moving object detection system, 11: Transmission antenna, 121: First receiving antenna, 122: Second receiving antenna, 13: Processing device, 131: Input interface, 132: Processor, 14: Substrate, 20: Detection area, 30: Moving object, 40: Vehicle, 41: Passenger compartment, 50: Controlled device, P1: First position, P2: Second position, S1: First detection signal, S2: Second detection signal, W: Radio wave

Claims

1. A transmitting antenna that transmits radio waves toward a detection area, a first receiving antenna that receives radio waves arriving from the detection area at a first position and outputs a first detection signal corresponding to the radio wave intensity at the first position, a second receiving antenna that receives radio waves arriving from the detection area at a second position and outputs a second detection signal corresponding to the radio wave intensity at the second position, a processing device that estimates the presence or absence of a moving object in the detection area based on an index value corresponding to the magnitude of the directional statistical variance related to the phase difference between the first detection signal and the second detection signal, and a moving object detection system.

2. The processing device estimates the distance to the moving object based on the elapsed time since the radio wave associated with the index value was transmitted. The moving object detection system according to Claim 1.

3. The transmitting antenna, the first receiving antenna, and the second receiving antenna are supported by a common substrate. The moving object detection system according to Claim 1.

4. When the presence of a moving object is estimated in the detection area, the processing device causes a controlled device to perform a predetermined operation. The moving object detection system according to Claim 1.

5. The moving object is a living body. The moving object detection system according to Claim 1.

6. The detection area is set to include the interior of a moving body. The moving object detection system according to Claim 4.

7. The radio wave has a frequency classified as a microwave. The moving object detection system according to Claim 1.

8. A processor that causes a transmitting antenna to transmit radio waves toward a detection area, an interface that receives a first detection signal corresponding to the radio wave intensity at a first position from a first receiving antenna that receives radio waves arriving from the detection area at the first position, and receives a second detection signal corresponding to the radio wave intensity at a second position from a second receiving antenna that receives radio waves arriving from the detection area at the second position, and the processor estimates the presence or absence of a moving object in the detection area based on an index value corresponding to the magnitude of the directional statistical variance related to the phase difference between the first detection signal and the second detection signal. A processing device.

9. A computer program executable by a processor mounted on a processing device, which, when executed, causes the processing device to cause a transmitting antenna to transmit radio waves toward a detection area, Receive a first detection signal corresponding to the radio wave intensity at the first position from a first receiving antenna that receives radio waves arriving from the detection area at the first position. Receive a second detection signal corresponding to the radio wave intensity at the second position from a second receiving antenna that receives radio waves arriving from the detection area at the second position. Estimate the presence or absence of a moving object in the detection area based on an index value corresponding to the magnitude of the statistical variance in the direction related to the phase difference between the first detection signal and the second detection signal. Computer program.

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