Monitoring device, monitoring system, monitoring method, and program

Abstract

Depending on the distance from the receiver, it detects the intrusion of other objects that cannot be distinguished from objects originally present within the monitoring area. [Solution] The acquisition unit 112 acquires the received signal from the radar 2. The analysis unit 113 analyzes the acquired received signal and extracts the frequency components. The estimation unit 114 estimates the direction of the detected object and the distance to this object based on the obtained frequency components. The setting unit 115 stores the monitoring area and a background pattern showing reflected waves from objects other than reflectors in the monitoring area, using the recognized direction and distance of the reflector, during initialization. The detection unit 116 detects objects that have entered the monitoring area during monitoring, based on the difference between the monitoring pattern showing reflected waves received by the radar 2 from objects in the monitoring area and the background pattern stored during initialization.

Description

Technical Field

[0001] The present invention relates to a monitoring device, a monitoring system, a monitoring method, and a program for detecting an object that has entered a monitoring area in order to ensure safety in transportation and the like.

Background Art

[0002] For ensuring safe transportation, various traffic control systems have been developed. In particular, avoiding collisions between vehicles and obstacles is an important issue in traffic control systems such as railways, and a technology for detecting obstacles is required.

[0003] Patent Document 1 discloses a railroad crossing obstacle detection device having a transceiver that transmits radio waves in an area including a railroad crossing and receives reflected waves of the radio waves and converts them into electrical signals, and a reflector that is disposed outside the railroad crossing and reflects the radio waves transmitted from the transceiver toward the transceiver. This railroad crossing obstacle detection device stores background pattern information in a monitoring area set at a position in front of the reflector with respect to the transceiver, and a signal processing unit analyzes the electrical signals supplied from the transceiver, cancels the electrical signals belonging to the reflected waves of the background pattern by the stored background pattern information, and detects an obstacle based on the reflected waves from the obstacle in the monitoring area.

[0004] Further, Patent Document 2 discloses a railroad crossing obstacle detection device that transmits radio waves into an obstacle detection area set in a railroad crossing from at least three or more detection sensor units arranged outside the track line, calculates the distance to those obstacles based on the signal processing information of the reflected radio waves received by each detection sensor unit from the obstacles, and specifies the position of the obstacles based on the calculated distance data.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] Incidentally, in recent years, surveillance devices that use millimeter waves (radio waves with frequencies of 30 to 300 GHz) to detect objects have been attracting attention. Sensors using millimeter waves have superior characteristics, such as higher resolution compared to sensors using microwaves, ultrasound, etc., and the ability to detect objects at longer distances compared to infrared lasers, etc. However, because of these superior characteristics, sensors using millimeter waves can be affected by buildings inside and outside the surveillance area, which has led to problems such as the need for relocation work on existing buildings. To address this problem, for example, the technology described in Patent Document 1 prevents false detections by installing a reflector at a predetermined distance from the receiver, defining the area in front of the reflector as the surveillance area, and excluding areas farther from the reflector from surveillance.

[0007] However, the level crossing obstacle detection device described in Patent Document 1 only sets the monitoring area in front of the reflector. Therefore, if an object such as a person is present at an equidistant distance from a building, the object may overlap with the background pattern and may not be detected.

[0008] One of the objectives of this invention is to detect the intrusion of other objects that cannot be distinguished from objects originally present in the monitoring area, based on their distance from the receiver. [Means for solving the problem]

[0009] The present invention provides, in a first embodiment, a monitoring device that stores, based on reflected waves received by a receiver from two or more pre-installed reflectors, a monitoring area enclosed by a line connecting the reflectors and the receiver, and the pattern of reflected waves received by the receiver from an object in the monitoring area, and detects an object that has entered the monitoring area based on the difference between the pattern of reflected waves received by the receiver from an object in the monitoring area and the stored pattern.

[0010] According to the monitoring device of the first embodiment, the intrusion of other objects that are indistinguishable from objects originally present in the monitoring area can be detected based on the distance from the receiver.

[0011] In the monitoring device of the first embodiment, a configuration in which reflected waves arriving from a position more than a predetermined distance away from the receiver are recognized as reflected waves from the reflector may be adopted as a second embodiment.

[0012] According to the monitoring device of the second embodiment, it is possible to distinguish between reflected waves from the reflector and other waves.

[0013] The present invention provides a third embodiment of a monitoring system comprising a control device, a transmitter that transmits radio waves, and a receiver that receives reflected waves of the radio waves, wherein the control device stores a monitoring area enclosed by a line connecting the reflectors and the receiver, and a pattern of reflected waves received by the receiver from an object in the monitoring area, based on reflected waves received by the receiver from two or more reflectors that have been installed in advance, and the control device detects an object that has entered the monitoring area based on the difference between the pattern of reflected waves received by the receiver from an object in the monitoring area and the stored pattern.

[0014] According to the third embodiment of the monitoring system, the intrusion of other objects that are indistinguishable from objects originally present in the monitoring area can be detected based on the distance from the receiver.

[0015] The present invention provides a fourth aspect of a monitoring method in which a transmitter transmits radio waves, a receiver receives the reflected waves of the radio waves, and a control device stores, based on the reflected waves received by the receiver from two or more pre-installed reflectors, a monitoring area enclosed by a line connecting the reflectors and the receiver, and the pattern of the reflected waves received by the receiver from an object in the monitoring area, and the control device detects an object that has entered the monitoring area based on the difference between the pattern of the reflected waves received by the receiver from an object in the monitoring area and the stored pattern.

[0016] According to the monitoring method of the fourth aspect, it is possible to detect the intrusion of other objects that cannot be distinguished from the objects originally existing in the monitoring area depending on the distance from the receiver.

[0017] The present invention provides, as a fifth aspect, a program that causes a computer that controls a transmitter that transmits radio waves and a receiver that receives reflected waves of the radio waves to store, based on the reflected waves received from two or more reflectors where the receiver is pre-installed, a monitoring area surrounded by a line connecting the reflector and the receiver, and a pattern of the reflected waves received by the receiver from an object in the monitoring area, and to detect an object that has entered the monitoring area based on the difference between the pattern of the reflected waves received by the receiver from an object in the monitoring area and the stored pattern.

[0018] According to the program of the fifth aspect, it is possible to detect the intrusion of other objects that cannot be distinguished from the objects originally existing in the monitoring area depending on the distance from the receiver.

Brief Description of Drawings

[0019] [Figure 1] A block diagram showing an example of the configuration of a monitoring system 9 according to an embodiment of the present invention. [Figure 2] A diagram showing an example of the arrangement of the radar 2 at a railroad crossing. [Figure 3] A diagram showing an example of the areas scanned by each of the two radars 2. [Figure 4] A diagram showing an example of the configuration of the monitoring device 1. [Figure 5] A diagram showing an example of the background pattern DB121. [Figure 6] A diagram showing an example of the monitoring area defined when the number of reflectors is 2. [Figure 7] A diagram showing an example of the monitoring area defined when the number of reflectors is 1. [Figure 8] A diagram showing an example of the configuration of the radar 2. [Figure 9] A diagram showing an example of the arrangement of each array antenna. [Figure 10]A diagram showing an example of the functional configuration of the monitoring device 1. [Figure 11] A flowchart showing an example of the operation flow of the initialization process. [Figure 12] A flowchart showing an example of the operation flow of the monitoring process.

Modes for Carrying Out the Invention

[0020] <Embodiment> <Configuration of the Monitoring System> FIG. 1 is a block diagram showing an example of the configuration of a monitoring system 9 according to an embodiment of the present invention. The monitoring system 9 shown in FIG. 1 includes a monitoring device 1, a communication line 3, and a management device 4. Further, this monitoring system 9 includes radars 2a and 2b (hereinafter, when not distinguishing between them, simply referred to as "radar 2") connected to the monitoring device 1. Further, this monitoring system 9 includes an alarm 6 connected to the monitoring device 1. Further, this monitoring system 9 includes cut-off devices 5a and 5b (hereinafter, when not distinguishing between them, simply referred to as "cut-off device 5") connected to the management device 4. Note that any of these configurations may be plural or one in the monitoring system 9.

[0021] The monitoring device 1 is a device that controls a radar 2 for monitoring an object that enters a determined space, and estimates the direction and distance of the object as seen from the radar 2 based on a signal (hereinafter, also referred to as a received signal) received by this radar 2. The monitoring device 1 is, for example, a computer.

[0022] The radar 2 is a device that transmits and receives radio waves and outputs a signal corresponding to the direction and distance of an object by the TOF (Time of Flight) method. That is, this radar 2 is an example of a transmitter that transmits radio waves. Further, this radar 2 is also an example of a receiver that receives the reflected wave of the transmitted radio wave. Therefore, the above-described monitoring device 1 is an example of a control device that controls a transmitter that transmits radio waves and a receiver that receives the reflected wave of this radio wave.

[0023] The radar 2 shown in Figure 1 is a phased array radar having multiple antenna elements arranged at predetermined positions. Phased array radars can perform beam scanning by controlling the phase of radio waves transmitted from each antenna, and therefore have the advantage of faster scanning compared to mechanical scanning.

[0024] Furthermore, radar 2 may employ a MIMO (Multiple-Input Multiple-Output) system, for example, by combining multiple transmitting and receiving antennas. This allows radar 2 to form more virtual antenna elements than the actual number of antenna elements, thereby improving angular resolution.

[0025] Communication line 3 is a line that connects monitoring device 1 and management device 4 to enable communication via wired or wireless connection. Communication line 3 may be, for example, a LAN (Local Area Network), a WAN (Wide Area Network), the Internet, or a combination thereof. Furthermore, communication line 3 may include public switched telephone networks (PSTN), integrated services digital networks (ISDN), etc.

[0026] The barrier 5 is a device that blocks the roadway when a train enters the tracks in the area of ​​a level crossing where the tracks and the roadway intersect at grade. The barrier 5 is controlled by the control device 4.

[0027] The control device 4 is a device that controls and manages the barrier gates 5 installed at level crossings, and is, for example, a computer. The control device 4 determines the position of the train on the track and controls the barrier gates 5 according to that position. The position of the train is determined by, for example, sensors installed along the track, positioning devices installed on the train, etc. This control device 4 may be installed at each level crossing or at each station. Alternatively, this control device 4 may be a central control device that manages all the barrier gates 5 installed at multiple level crossings together.

[0028] Furthermore, the management device 4 shown in Figure 1 is connected to the monitoring device 1 via a communication line 3. Before a train enters the level crossing, the management device 4 activates the barrier 5 installed at the level crossing to block the roadway and notifies the monitoring device 1 of this fact. When the monitoring device 1 receives the above notification from the management device 4 via the communication line 3, it activates the radar 2 to determine whether there is an obstacle that has entered the level crossing. The monitoring device 1 does not need to receive this notification. In this case, the monitoring device 1 may keep the radar 2 activated at all times to monitor the inside of the level crossing.

[0029] The alarm device 6 has a speaker, an alarm light, etc., and outputs an alarm under the control of the monitoring device 1. The alarm device 6 may be embedded in or attached to the circuit breaker 5. In this case, the monitoring device 1 controls the alarm device 6 via the communication line 3 and the management device 4.

[0030] Figure 2 shows an example of the arrangement of radar 2 at a level crossing. The radar 2 shown in Figure 2 consists of radar 2a and radar 2b, respectively, positioned at different locations around the scan area R. Here, the scan area R is the area scanned by radar 2. The scan area R includes the area of ​​the level crossing where the railway track and the road intersect at the same level. Barriers 5a and 5b each block the road to prevent automobile C from entering the scan area R before the train enters the level crossing area. Barriers 5a and 5b then cease blocking the road after the train has left the level crossing area.

[0031] Figure 3 shows an example of the areas scanned by each of the two radars 2. Radar 2a, shown in Figure 3, scans the scan area Ra with a radio wave beam. Radar 2b scans the scan area Rb with a radio wave beam. Both the scan area Ra and the scan area Rb are fan-shaped regions within a predetermined angle and radius centered on radar 2a and radar 2b, respectively. The scan area R is covered by the union of the scan areas Ra and Rb. Because radars 2a and radar 2b are positioned at different locations, they can compensate for each other's blind spots.

[0032] <Configuration of the monitoring device> Figure 4 shows an example of the configuration of monitoring device 1. Monitoring device 1 includes a processor 11, memory 12, and communication unit 13. These are connected to each other via a bus so that they can communicate with one another.

[0033] The processor 11 controls the monitoring device 1 by reading and executing a program from the memory 12. The processor 11 is, for example, a CPU (Central Processing Unit). Alternatively, the processor 11 may be, for example, an FPGA (Field Programmable Gate Array), or may include an FPGA. Furthermore, this processor may have an ASIC (Application Specific Integrated Circuit) or other programmable logic device, and control may be performed by these.

[0034] The communication unit 13 is a communication circuit that connects the monitoring device 1 to the radar 2 via wired or wireless means, enabling communication. The communication unit 13 is also a communication circuit that connects to the management device 4 (see Figure 1) via wired or wireless means, through a communication line 3. In addition to these, the communication unit 13 may also connect various external devices to the monitoring device 1.

[0035] Memory 12 is a storage means for storing the operating system, various computer programs (hereinafter simply referred to as "programs"), data, etc., which are loaded into the processor 11. Memory 12 has RAM (Random Access Memory) and ROM (Read Only Memory). Memory 12 may also have a solid-state drive, a hard disk drive, etc. Memory 12 also stores the background pattern DB 121.

[0036] Figure 5 shows an example of the background pattern DB121. This background pattern DB121 has a monitoring area list 1211 and a background pattern table 1212. The monitoring area list 1211 is a list of monitoring area IDs, which are identification information for identifying each of the areas monitored by the radar 2 (called monitoring areas). The background pattern table 1212 is a table provided for each monitoring area ID listed in the monitoring area list 1211. This background pattern table 1212 stores the definition of the monitoring area identified by the corresponding monitoring area ID and the "background pattern".

[0037] In the example shown in Figure 5, background pattern table 1212 stores the items: number of reflectors, reflector coordinates (1), reflector coordinates (2), and background pattern. The number of reflectors is the number of reflectors used to define the monitoring area. Reflector coordinates (1) and reflector coordinates (2) are the coordinates of the reflectors mentioned above. The background pattern is data that shows the pattern of reflected waves from objects in the monitoring area when there are no abnormalities.

[0038] In the example shown in Figure 5, for instance, the background pattern table 1212 associated with monitoring area ID "N01" shows a reflector count of "2". This indicates that two reflectors are used to define the monitoring area for monitoring area ID "N01". In this case, for example, monitoring device 1 defines the area enclosed by the lines connecting the coordinates of the two reflectors and the coordinates of radar 2 (receiver) as the monitoring area.

[0039] On the other hand, in the background pattern table 1212 associated with the monitoring area ID "N02" shown in Figure 5, the number of reflectors is "1". This indicates that there is only one reflector used to define the monitoring area for monitoring area ID "N02". Therefore, this background pattern table 1212 stores "(x3, y3)" which represents the coordinates of the one reflector mentioned above in reflector coordinate (1), but stores nothing in reflector coordinate (2). In this case, for example, monitoring device 1 defines the monitoring area only by the distance between the coordinates of the one reflector mentioned above and the coordinates of radar 2 (receiver).

[0040] Figure 6 shows an example of a monitoring area defined when there are two reflectors. During initialization, when radar 2a scans the scan area Ra and receives reflected waves from two or more reflectors and supplies the received signals to monitoring device 1, the processor 11 of monitoring device 1 stores the area enclosed by the lines connecting these two or more reflectors and radar 2a as a monitoring area in the background pattern DB 121 of memory 12. If there are three or more reflectors in the scan area, monitoring device 1 may split these reflectors into pairs, assign a monitoring area ID to each, and store them in the background pattern DB 121. In this case, the background pattern table 1212 of background pattern DB 121 may be configured to increase the number of reflector coordinate (n) columns (where n is an integer of 3 or more) according to the number of reflectors.

[0041] In other words, in the example shown in Figure 6, radar 2a receives reflected waves from two reflectors, reflector P1 and reflector P2. Therefore, the processor 11 of the monitoring device 1, which receives the received signal from radar 2a, stores the area enclosed by three lines as the monitoring area Rs in the background pattern DB121: line L01 connecting the coordinates of radar 2a (x0,y0) to reflector P1 (x1,y1), line L02 connecting the coordinates of radar 2a (x0,y0) to reflector P2 (x2,y2), and line L12 connecting the coordinates of reflector P1 (x1,y1) to reflector P2 (x2,y2). The lines L01, L02, and L12 mentioned above may be straight lines, but any of these lines may be curved, such as an arc.

[0042] Therefore, this monitoring device 1 is an example of a monitoring device that stores, based on reflected waves received by the receiver from two or more pre-installed reflectors, a monitoring area enclosed by lines connecting these reflectors and the receiver, and the pattern of reflected waves received by the receiver from objects in this monitoring area.

[0043] Figure 7 shows an example of a monitoring area defined when there is one reflector. During initialization, when radar 2a scans the area to be scanned Ra and receives a reflected wave from only one reflector P3 and supplies the received signal to monitoring device 1, the processor 11 of monitoring device 1 stores the area of ​​the area to be scanned Ra up to the point in front of this reflector P3 from the perspective of radar 2a as the monitoring area in the background pattern DB121 of memory 12.

[0044] In other words, in the example shown in Figure 7, the only reflector that receives reflected waves from radar 2a is reflector P3. Therefore, the processor 11 of the monitoring device 1, which receives the received signal from radar 2a, determines the distance r from the coordinates (x0, y0) of radar 2a to the coordinates (x3, y3) of reflector P3. The processor 11 then stores the area within the scanned region Ra that is within the distance of "r" from radar 2a as the monitoring region Rs in the background pattern DB121. In addition, since there is only one reflector, the processor 11 stores the central angle φ of the scanned region Ra centered on radar 2a as the central angle of the monitoring region Rs in the background pattern DB121.

[0045] <Radar Configuration> Figure 8 shows an example of the configuration of radar 2. Radar 2 includes a transmitting array antenna 20, an oscillator 21, a modulation unit 22, a transmitting unit 23, a receiving array antenna 24, a receiving unit 25, an amplification unit 26, a demodulation unit 27, and a communication unit 28.

[0046] The transmitting array antenna 20 and the receiving array antenna 24 are both array antennas. An array antenna is an antenna composed of multiple antenna elements (radiating elements) arranged at predetermined positions. The arrangement of the multiple antenna elements can be, for example, linear. This arrangement can also be circular, grid-like, or the like.

[0047] Figure 9 shows an example of the arrangement of each array antenna. The transmitting array antenna 20 shown in Figure 9(a) consists of six transmitting antenna elements 200. These six transmitting antenna elements 200 are arranged in a straight line at equal intervals, and the distance between two adjacent transmitting antenna elements 200 is "d1". d1 is set to, for example, 32 millimeters.

[0048] On the other hand, the receiving array antenna 24 is composed of eight receiving array antenna elements 240. Figure 9(b) shows an enlarged view of the receiving array antenna 24 shown in Figure 9(a). As shown in Figure 9(b), the eight receiving array antenna elements 240 are arranged at equal intervals in a straight line. Furthermore, this receiving array antenna 24 shown in Figure 9(a) is arranged parallel to the transmitting array antenna 20.

[0049] The total length of the receiving array antenna 24 is the length from the left end to the right end when the eight receiving array antenna elements 240 are extended to the right by one element at equal intervals. Here, the total length of the receiving array antenna 24 is set to be the same as d1, which is the distance between two adjacent transmitting antenna elements 200. The distance between two adjacent receiving array antenna elements 240 is "d2". d2 is set to, for example, 0.5 times the wavelength λ of the radio wave used (λ / 2). Therefore, d2 × 8 = d1. For example, when d1 is set to 32 millimeters, d2 is set to 4 millimeters. In this case, the wavelength λ is 8 millimeters, and the millimeter wave frequency used is 37.5 GHz.

[0050] Returning to Figure 8, the oscillator 21 is a device that emits coherent radio waves. The radio waves emitted by this oscillator 21 are millimeter waves. Note that the oscillator 21 may also emit microwaves, terahertz waves, etc.

[0051] The modulation unit 22 is a device that frequency modulates the radio waves emitted by the oscillator 21 to obtain a chirp signal. This chirp signal may be a linear chirp signal in which the frequency increases and decreases at a predetermined rate with respect to time, or it may be a nonlinear chirp signal. For example, the modulation unit 22 may use a surface acoustic wave (SAW) device that converts electrical signals into ultrasonic vibrations to provide delay characteristics.

[0052] The transmitting unit 23 controls the transmitting array antenna 20 based on instructions from the monitoring device 1 and transmits the chirp signal generated by the modulation unit 22 toward the scanned area R. The monitoring device 1 causes each antenna element constituting the transmitting array antenna 20 to transmit a chirp signal with a phase corresponding to the beam scanning direction. As a result, the transmitting array antenna 20 transmits radio waves indicating the chirp signal in a predetermined direction.

[0053] The receiving unit 25 acquires a received signal representing the radio waves from the receiving array antenna 24, which receives the radio waves that have struck an object and been reflected. The amplification unit 26 amplifies the received signal received by the receiving unit 25.

[0054] The demodulation unit 27 detects and demodulates the received signal amplified by, for example, the amplification unit 26. This demodulation corresponds to the frequency modulation performed by the modulation unit 22. The demodulation unit 27 includes, for example, a mixer, and uses the signal transmitted by the transmission unit 23 (referred to as the transmitted signal) to convert the received signal into an intermediate frequency signal (hereinafter also referred to as the IF signal). By converting the received signal into an IF signal, pulse compression is performed.

[0055] The communication unit 28 transmits the IF signal converted by the demodulation unit 27 as a received signal to the monitoring device 1. The communication unit 28 also receives control signals from the monitoring device 1 for controlling the radar 2.

[0056] <Functional configuration of the monitoring device> Figure 10 shows an example of the functional configuration of the monitoring device 1. The processor 11 of the monitoring device 1 functions as an instruction unit 111, an acquisition unit 112, an analysis unit 113, an estimation unit 114, a setting unit 115, and a detection unit 116 by reading and executing a program stored in the memory 12.

[0057] During initialization, the instruction unit 111 instructs the radar 2 via the communication unit 13 to scan the entire scan area R. The radar 2 receives this instruction, performs the scan, and generates a received signal.

[0058] The acquisition unit 112 acquires the received signal from the radar 2 via the communication unit 13. The analysis unit 113 performs a discrete Fourier transform on the acquired received signal to extract the frequency components. For example, the Fast Fourier Transform (FFT) is used for the discrete Fourier transform.

[0059] The estimation unit 114 estimates the direction of the detected object and the distance to this object based on the frequency components obtained by the analysis unit 113.

[0060] The setting unit 115 identifies an object located at a predetermined distance or greater from among the objects whose direction and distance have been estimated, and recognizes that object as a reflector. In other words, the monitoring device 1, which has a processor 11 that functions as this setting unit 115, is an example of a monitoring device that recognizes reflected waves arriving from a position at a predetermined distance or greater from the receiver as reflected waves from a reflector. The monitoring device 1 may also recognize reflected waves from a reflector by other methods. For example, the monitoring device 1 may recognize reflected waves arriving from the same distance over a predetermined angular range as reflected waves from a reflector.

[0061] The setting unit 115 then uses the recognized direction and distance of the reflector to calculate the coordinates of the reflector and stores them in the background pattern DB 121. The setting unit 115 also stores the pattern of reflected waves received from objects other than the reflector as a background pattern in the background pattern DB 121.

[0062] Once initialization is complete, the instruction unit 111 instructs the radar 2 via the communication unit 13 to begin scanning for actual monitoring. At this time, the instruction unit 111 sends the definition of the monitoring area stored in the background pattern DB 121 to the radar 2. Upon receiving this instruction, the radar 2 scans the monitoring area and generates a received signal.

[0063] The acquisition unit 112 acquires the received signal from the radar 2 via the communication unit 13. The analysis unit 113 performs a discrete Fourier transform on the received signal to extract the frequency components. The estimation unit 114 estimates the direction and distance of each object in the monitoring area based on the frequency components obtained by the analysis unit 113. The estimation unit 114 then transmits the estimated distance to each object and the direction of each object to the detection unit 116.

[0064] The detection unit 116 identifies the pattern of reflected waves received by the radar 2 from an object in the monitoring area (hereinafter also referred to as the "monitoring pattern") based on the distance and direction information transmitted from the estimation unit 114. Next, the detection unit 116 identifies the difference between this identified monitoring pattern and the background pattern of the monitoring area stored in the background pattern DB 121. Then, based on the identified difference, the detection unit 116 communicates to the instruction unit 111, for example, if the difference satisfies a predetermined condition.

[0065] Here, both the monitoring pattern and the background pattern are patterns of reflected waves received by radar 2, and the reflected waves have multiple elements such as direction of arrival and intensity. Therefore, the monitoring pattern and the background pattern are often represented by vectors or matrices having multiple elements. For this reason, the difference between the monitoring pattern and the background pattern is also generally represented by a vector or matrix. The predetermined conditions used to determine this identified difference can take various forms. These predetermined conditions can be determined, for example, by whether the ratio of the change in the intensity of the reflected wave to the change in the direction of arrival of the reflected wave, or by whether various indicators of the statistical values ​​of the difference in reflected intensity (mean, variance, standard deviation, sum, median, maximum, etc.) exceed predetermined thresholds. There may be one indicator or multiple thresholds. If there are multiple indicators or thresholds, the predetermined conditions described above may be determined by the logical OR or logical AND of the conditions determined by their combination.

[0066] The instruction unit 111 recognizes that an object has entered the environment when it is informed by the detection unit 116 that the difference between the monitoring pattern and the background pattern meets a predetermined condition. Upon recognizing that an object has entered the environment, the instruction unit 111 instructs the alarm device 6 to output an alarm via the communication unit 13.

[0067] In other words, monitoring device 1, which implements these functions, is an example of a monitoring device that detects an object that has entered the monitoring area based on the difference between the pattern of the reflected wave received by the receiver from an object in the monitoring area and a stored pattern.

[0068] <Operation of monitoring device> <Overall processing> The processor 11 of the monitoring device 1 performs the initialization process shown in step S100 (see Figure 11) below, and then performs the monitoring process shown in step S200 (see Figure 12) below.

[0069] <Initialization process> Figure 11 is a flowchart showing an example of the operation flow of the initialization process. This initialization process is performed when initializing the monitoring device 1, and is step S100 described above. The processor 11 of the monitoring device 1 instructs the radar 2 to emit (transmit) radio waves (step S101). Next, the processor 11 acquires a received signal from the radar 2 (step S102).

[0070] When the processor 11 receives a signal from radar 2, it analyzes this received signal (step S103). Here, the processor 11 performs a fast Fourier transform analysis on the received signal. Based on the results of this analysis, the processor 11 estimates the position of the reflector (i.e., distance and angle) (step S104).

[0071] After estimating the position of the reflectors, the processor 11 determines whether there are two or more reflectors (step S105). If it determines that there are two or more reflectors (step S105; YES), the processor 11 stores the area enclosed by the lines connecting these two or more reflectors and the radar 2 (receiver) in the memory 12 as a monitoring area (step S106). Then, the processor 11 stores the pattern of reflected waves from objects in the monitoring area in the memory 12 as a background pattern (step S107).

[0072] On the other hand, if it is determined that the number of reflectors is not two or more (step S105; NO), the processor 11 identifies the distance from the radar 2 to the one reflector whose position has been estimated, and stores the monitoring area determined by this distance (step S108). In this case, since there is only one reflector, the processor 11 stores all directions of the radio waves that the radar 2 scans toward the area being scanned as the monitoring area. Then, the processor 11 executes step S107 described above.

[0073] Although not shown in Figure 11, if the processor determines that the number of reflectors is less than one, it may record and report the occurrence of an error.

[0074] <Monitoring process> Figure 12 is a flowchart showing an example of the operation flow of the monitoring process. This monitoring process is the process that actually performs monitoring after initialization is complete, and is step S200 described above. The processor 11 of the monitoring device 1 instructs the radar 2 to emit (transmit) radio waves toward the monitoring area stored in step S106 or step S108 of the initialization process (step S201).

[0075] Next, the processor 11 acquires the received signal from the radar 2 for the monitoring area (step S202). After acquiring the received signal from the radar 2, the processor 11 analyzes this received signal using the Fast Fourier Transform (step S203). Based on the analysis results, the processor 11 identifies the radio wave pattern shown by the received signal for the monitoring area as the monitoring pattern (step S204).

[0076] Once a monitoring pattern is identified, the processor 11 compares this monitoring pattern with the background pattern stored in memory 12 (step S205). Then, the processor 11 determines whether the difference between these patterns satisfies the condition (step S206).

[0077] If it is determined that the difference between the monitoring pattern and the background pattern does not satisfy the condition (step S206; NO), the processor 11 returns to step S201 in order to continue the measurement.

[0078] On the other hand, if it is determined that the difference between the monitoring pattern and the background pattern satisfies the condition (step S206; YES), the processor 11 instructs the alarm device 6 to output an alarm (step S207) and terminates the process.

[0079] By performing the process described above, if two or more reflectors are installed in advance, the monitoring device 1 can detect the intrusion of other objects that are indistinguishable from objects that were originally present in the monitoring area, based solely on the difference in distance from the radar 2 (receiver).

[0080] The configurations, shapes, sizes, and arrangements described in the above embodiments are merely schematic representations to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the described embodiments and can be modified in various forms as long as it does not deviate from the scope of the technical idea set forth in the claims.

[0081] <Variation> The above describes the embodiment, but the contents of this embodiment can be modified as follows. Furthermore, the following modifications may be combined.

[0082] <1> In the embodiments described above, the scanned area R may be scanned by one-dimensional scanning that changes the azimuth, or by two-dimensional scanning that changes both the azimuth and elevation. When performing two-dimensional scanning, the monitoring device 1 may rotate the radar 2 in either the azimuth direction or the elevation direction by mechanical drive. The radar 2 may also transmit radio waves in the elevation direction using a wide fan beam. Furthermore, when receiving radio waves that include reflected waves reflected by an object, the radar 2 may simultaneously form multiple received beams with different directional directions by using digital beamforming (DBF).

[0083] <2> In the embodiments described above, the operation of the processor 11 may not be performed solely by a single processor 11, but may also be performed collaboratively by multiple processors located in physically separate locations. Furthermore, the order of the operations of the processor 11 is not limited to the order described above and may be changed as appropriate.

[0084] <3> In the embodiment described above, the monitoring system 9 comprises a control device, a transmitter that transmits radio waves, and a receiver that receives reflected waves from the radio waves. Based on the reflected waves received by the receiver from two or more pre-installed reflectors, the control device stores a monitoring area enclosed by a line connecting the reflectors and the receiver, and the pattern of the reflected waves received by the receiver from an object in the monitoring area. Based on the difference between the pattern of the reflected waves received by the receiver from an object in the monitoring area and the stored pattern, the control device detects an object that has entered the monitoring area.

[0085] <4> In the embodiment described above, the method for monitoring a monitoring area using the monitoring system 9 is an example of a monitoring method in which a transmitter transmits radio waves, a receiver receives the reflected waves of the radio waves, and based on the reflected waves received by the receiver from two or more reflectors that have been installed in advance, a control device stores a monitoring area enclosed by a line connecting the reflectors and the receiver, and the pattern of the reflected waves received by the receiver from an object in the monitoring area, and the control device detects an object that has entered the monitoring area based on the difference between the pattern of the reflected waves received by the receiver from an object in the monitoring area and the stored pattern.

[0086] <5> In the embodiments described above, the program executed by the processor 11 of the monitoring device 1 may be provided stored on a recording medium readable by a computer device, such as a magnetic recording medium like a magnetic tape or magnetic disk, an optical recording medium like an optical disk, a magneto-optical recording medium, or a semiconductor memory. Alternatively, this program may be downloaded via a communication line such as the Internet.

[0087] The program executed by the processor 11 described above is an example of a program that causes a computer that controls a transmitter that transmits radio waves and a receiver that receives the reflected waves of the radio waves to store, based on the reflected waves received by the receiver from two or more reflectors that are pre-installed, a monitoring area enclosed by lines connecting the reflectors and the receiver, and the pattern of the reflected waves received by the receiver from an object in the monitoring area; and a step of detecting an object that has entered the monitoring area based on the difference between the pattern of the reflected waves received by the receiver from an object in the monitoring area and the stored pattern. [Explanation of Symbols]

[0088] 1...Monitoring device, 11...Processor, 111...Instruction unit, 112...Acquisition unit, 113...Analysis unit, 114...Estimation unit, 115...Setting unit, 116...Detection unit, 12...Memory, 121...Background pattern DB, 1211...Monitoring area list, 1212...Background pattern table, 13...Communication unit, 2, 2a, 2b...Radar, 20...Transmitting array antenna, 200...Transmitting antenna element, 21...Oscillator, 22...Modulation unit, 23...Transmitting unit, 24...Receiving array antenna, 240...Receiving array antenna element, 25...Receiving unit, 26...Amplification unit, 27...Demodulation unit, 28...Communication unit, 3...Communication line, 4...Management device, 5, 5a, 5b...Breakdown device, 6...Alarm device, 9...Monitoring system, L01...Line, L02...Line, L12...Line, P1, P2, P3...Reflector

Claims

1. Based on the reflected waves received by the receiver from two or more pre-installed reflectors, the receiver stores a monitoring area enclosed by a line connecting the reflectors and the receiver, and the pattern of the reflected waves received by the receiver from an object in the monitoring area. An object that has entered the monitoring area is detected based on the difference between the pattern of the reflected wave received by the receiver from an object in the monitoring area and the stored pattern. Monitoring equipment.

2. A reflected wave arriving from a position more than a predetermined distance away from the receiver is recognized as a reflected wave from the reflector. The monitoring device according to claim 1.

3. It comprises a control device, a transmitter that transmits radio waves, and a receiver that receives the reflected waves of the radio waves, Based on the reflected waves received by the receiver from two or more pre-installed reflectors, the control device stores a monitoring area enclosed by a line connecting the reflectors and the receiver, and the pattern of the reflected waves received by the receiver from an object in the monitoring area. The control device detects an object that has entered the monitoring area based on the difference between the pattern of the reflected wave received by the receiver from an object in the monitoring area and the stored pattern. A monitoring system.

4. The transmitter sends out radio waves, The receiver receives the reflected waves of the aforementioned radio waves, Based on the reflected waves received by the receiver from two or more pre-installed reflectors, the control device stores a monitoring area enclosed by a line connecting the reflectors and the receiver, and the pattern of the reflected waves received by the receiver from an object in the monitoring area. The control device detects an object that has entered the monitoring area based on the difference between the pattern of the reflected wave received by the receiver from an object in the monitoring area and the stored pattern. Monitoring method.

5. A computer controls a transmitter that transmits radio waves and a receiver that receives the reflected waves of the radio waves, The receiver stores, based on the reflected waves it has received from two or more pre-installed reflectors, a monitoring area enclosed by a line connecting the reflectors and the receiver, and the pattern of the reflected waves it has received from an object in the monitoring area. The steps include detecting an object that has entered the monitoring area based on the difference between the pattern of the reflected wave received by the receiver from an object in the monitoring area and the stored pattern, A program that executes the command.

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