KR102052119B1 - Linear virtual fence system using radar and reflector - Google Patents

Abstract

According to the present invention, the reflector is disposed at a certain distance from the radar and the radar to reflect the electromagnetic wave transmitted from the radar to measure and record the reception sensitivity of the electromagnetic wave received from the radar sensor as a reference value, and then reflected from the reflector. When a sudden change in the reception sensitivity of the electromagnetic wave occurs, it is determined that an intrusion has occurred in the boundary area, thereby providing a straight virtual fence that can take action including an alarm.
As the distance between the radar and the reflector increases in the straight virtual fence, the amount of reflection of electromagnetic waves decreases, so that the intrusion monitoring can not be performed reliably.

Description

LINEAR VIRTUAL FENCE SYSTEM USING RADAR AND REFLECTOR}

The present invention relates to a boundary system, and more particularly, to a straight virtual fence boundary system that radiates electromagnetic waves in a region to be bound and detects intrusion using a reflector.

Perimeters where people are not allowed to access are usually physically fenced and surveillance equipment such as CCTVs are installed. If immediate judgment on intrusion other than CCTV is required, a laser beam or radar may be used as shown in FIG. 1. In the case of a laser, the beam width is sharpened like an arrowhead, and the technology for launching is widely used. If the transmitter / receiver is placed 1: 1, the security boundary can be set very precisely in the case of a straight line. However, due to the nature of light, it is mainly used for indoors rather than outside because it has a high probability of erroneous detection due to scattering, reflection, and absorption in natural environments such as dust, insects, fog, and rain.

Meanwhile, the bottom of FIG. 1 shows an example and a problem of boundary setting by electromagnetic waves. The electromagnetic wave emitted from the radar is suitable for the external boundary system because there is almost no erroneous detection problem caused by the environment such as fog, rain and dust, compared to the laser beam. However, electromagnetic waves are linear, but as they progress, they spread radially, which causes them to be bound to areas other than the original boundary area. That is, if the original boundary area is a straight fence, it is a malfunction that is detected as a chip because the place outside the area should be free to be carried by humans, but the boundary area becomes wider and farther away from the radar due to the spread of electromagnetic waves. There is a problem with this happening. In other words, a radar sensor is not suitable for a straight line of precise boundary like a laser.

In other words, if you want to install a virtual fence in the outside and look out for the boundary, the sharp straightness of the laser is preferable when using the laser beam, but the malfunction due to the influence of the external environment is problematic, and when using the radar, the influence of the external environment is overcome. Due to the spread of electromagnetic waves, malfunctions due to sensing outside the monitoring area may be a problem.

Republic of Korea Patent No. 10-1507238 is to form a virtual fence by arranging the radar at regular intervals, but there is a possibility of false detection due to the spread of electromagnetic waves, and above all, the radar sensor must be arranged in each node, so a lot of expensive radar sensors are required. Done.

Therefore, an object of the present invention is to provide a virtual fence of a straight line that can minimize the number of installation by minimizing the false detection rate by using the radar and the reflector and extend the monitoring distance without changing the performance of the radar itself.

In addition, another object of the present invention is to develop a suitable type of module combining the radar sensor and the reflector by analyzing the reflection characteristics of the reflector in order to commercialize a straight virtual fence, the environment, such as the terrain where the virtual fence of the straight line is installed It is intended to design the module appropriately.

In accordance with the above object, the present invention, by placing a reflector at a certain distance from the radar and the radar reflects the electromagnetic wave transmitted from the radar reflector reflects and measures the reception sensitivity of the electromagnetic wave received from the radar sensor as a reference value, and then, When a sudden change in the reception sensitivity of the electromagnetic wave reflected from the reflector occurs, it is determined that an intrusion has occurred in the boundary area, and a straight virtual fence is provided to take an action including an alarm.

As the distance between the radar and the reflector increases in the straight virtual fence, the amount of reflection of electromagnetic waves decreases, so that the intrusion monitoring can not be performed reliably. As the distance between the radar and the reflector increases, the size of the reflector is increased and arranged. .

In addition, when the height of the radar sensor and the reflector does not match, including when the terrain of the area monitored by the virtual fence is not the same plane but the height is different from each other, the inclination of the reflector in the vertical direction is adjusted to face the radar sensor. To see and transmit electromagnetic waves in a straight line.

In a straight line virtual boundary system,

A radar sensor having a transmitting antenna and a receiving antenna;

A reflector disposed at a predetermined distance from the radar sensor; And

And a control module for detecting an alarm and detecting an intrusion event between the radar sensor and the reflector with respect to the amount of reflection from the reflector received by the radar sensor.

Reflecting the electromagnetic wave transmitted from the transmitting antenna of the radar sensor at the reflector and receiving the radio wave reflected from the receiving antenna of the radar to measure the amount of reflection,

The radar sensor and the reflector are arranged to face each other in a straight line, so that the azimuth and altitude of the radar sensor or the reflector are aligned with respect to each other so that electromagnetic waves emitted from the radar sensor can reach and reflect the reflector. Let's

The radar sensor analyzes a Doppler signal and ignores received electromagnetic waves from an object having a displacement other than the signal reflected and received from the reflector, without sensing them.

When there is no intrusion event between the radar and the reflector provides a virtual boundary system of a straight line characterized in that it is determined that the occurrence of the intrusion event is a situation where the reflected amount is sharply reduced or changed based on a known reflection amount.

In the above, the reflector is not only a reflector manufactured in the vertical form using a flat plate or a dihedral corner reflector, but also includes a reflector in the form of a longitudinally long combination in the form of a column using various reflectors. It provides a straight line virtual boundary system.

In the above, the radar sensor and the reflector are provided separately, or together in one case to provide a straight virtual boundary system, characterized in that consisting of a base module arranged at the starting point of the boundary zone.

In the above, the origin module further comprises a position adjusting device for adjusting the altitude and azimuth of the reflector, the radar sensor for transmitting the electromagnetic wave by the reflector according to the size of the reflector included in the ups and downs of the terrain or the origin module It provides a straight line virtual boundary system characterized in that the adjustment is possible.

In the above, a virtual boundary system of a straight line is characterized in that the size of the reflector is increased as the distance from the radar sensor reflector increases in the virtual boundary system.

The starting module may include a battery or a photovoltaic module; And moving means; further provides a virtual virtual boundary system characterized in that the virtual boundary zone can be moved to the required place.

Provides a straight virtual border system characterized in that a plurality of the base module is arranged to form a closed virtual border zone and is controlled and managed through a central server by applying a wired or wireless communication network between the plurality of base module.

In the above, the origin module provides a straight virtual boundary system configured by placing one or more radar sensors or one or more reflectors in one case to be disposed at the intersection of the plurality of virtual boundary lines.

In the above, the case of the base module includes a columnar, CCTV camera, GPS sensor, warning lights, lights, speakers, or cover for minimizing attenuation of radio waves during snowfall / snowfall for the purpose of preventing snow accumulation It provides a straight virtual boundary system characterized in that it further comprises a form.

Provides a straight virtual boundary system, characterized in that for forming one or more reflectors reflecting electromagnetic waves to one radar sensor to form a plurality of virtual boundaries of a straight line by one radar sensor.

According to the present invention, in spite of the fact that the electromagnetic wave transmitted from the radar is spreadable by using the radar and the reflector, if the amount of reflection is drastically reduced or changed based on the fact that the amount of reflection of the electromagnetic wave returned to the radar sensor is constant by the reflector, It can be assured with high confidence that an intrusion has occurred between and the reflector. That is, the erroneous detection phenomena outside the boundary area due to the spreading of the electromagnetic wave of the radar sensor can be removed by the reflector, so that a virtual fence by a straight beam such as a laser can be realized as the electromagnetic wave.

In the present invention, since the intrusion is detected by electromagnetic waves, unlike a laser beam, malfunction due to an environment such as fog, dust, or rain rarely occurs and does not react to a small object that is not large enough to cover the reflector regardless of distance. It can increase the reliability of the sensor.

In addition, the present invention prevents the phenomenon that the amount of reflection of electromagnetic waves is reduced by placing a larger reflector when the distance between the radar sensor and the reflector is far, significantly increasing the monitoring distance without increasing the number of radar sensors, as well as reliability High boundary system can be realized.

In addition, when the height of the radar sensor and the reflector does not match, including when the terrain of the area monitored by the virtual fence is not the same plane but the height is different from each other, the inclination of the reflector in the vertical direction is adjusted to face the radar sensor. To see and transmit electromagnetic waves in a straight line.

1 is a diagram for explaining problems of a boundary system by a laser beam and a boundary system by electromagnetic waves.
FIG. 2 is a diagram showing the behavior of electromagnetic waves caused by the radar sensor and the reflector and explaining the principle of virtual fence implementation.
3 is a diagram illustrating the operation of a virtual fence implemented using a radar sensor and a reflector according to the present invention.
4 is a diagram illustrating the use of a reflector having a larger size as the length of the virtual fence becomes longer according to the present invention.
5 is a diagram to help explain the sensitivity control according to the monitoring target in the algorithm flow chart and the virtual fence to which the present invention is applied.
FIG. 6 is a block diagram illustrating various types of modules combining a virtual fence model and a radar and a reflector applicable to the virtual fence model for a predetermined area formed by connecting a plurality of linear virtual fences of the present invention.
7 is a diagram illustrating a correction method according to the terrain of the non-flat structure when installing the virtual fence of the present invention.
FIG. 8 shows a straight line array arranged up and down as a modified embodiment of the straight virtual fence of the present invention.
Figure 9 shows that the battery is made of a mobile or installed in a straight virtual fence of the present invention by moving.
FIG. 10 shows a cctv camera, a GPS sensor, a warning light, an illumination, a speaker, and the like made in the straight virtual fence of the present invention.
Figure 11 shows an example of the appearance made in the shape of a reverse lozenge put a hot wire inside the case in order to reduce water condensation and ice freezing in the straight virtual fence of the present invention.
FIG. 12 shows an example of generating a plurality of straight virtual fences by using the radar propagation radiation region in the straight virtual fence of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

In the case of fences or fences installed in areas requiring security, the inside of the physical boundary is allowed to be moved by the insider and the outside of the boundary is a free zone to the outsider. In most cases, the normal entrance is through the entrance, and if the fence or fence is crossed outside the entrance, it can be regarded as an illegal intrusion. Entrances are generally shorter than fences and can be fully monitored by humans or CCTVs, but for very long fences such as borders or airfields, it is very difficult to monitor the entire boundary with CCTCs or people. Therefore, it is necessary to implement an electronic virtual fence that immediately recognizes when an illegal intrusion occurs at such a straight line boundary.

When using the laser beam as shown in the upper figure of FIG. 1, the linear section can be precisely bounded, but malfunctions are severe because the environment, such as dust, rain, and fog, is alarmed due to light scattering, reflection, and absorption characteristics. It is difficult to apply outdoors. When using the radar as in the case of the lower part of Figure 1, due to the radiation effect of radio waves, it is impossible to monitor the precise straight section like a laser beam.

2 is a conceptual diagram illustrating a principle of implementing a virtual fence of a straight line by using a radar electromagnetic wave but applying a reflector. 2 shows a reflector disposed at a certain distance from a radar having a transmitting antenna and a receiving antenna. The electromagnetic waves emitted by the transmitting antenna are radially spread and go straight as indicated by the red spheres. The propagated electromagnetic wave is thus incident on the standard reflector, and the incident electromagnetic wave is reflected toward the receiving antenna of the radar by the reflector.

By using the basic functions of the radar and the reflector, a straight virtual fence such as a laser beam can be made between the radar and the reflector as shown in FIG.

3 illustrates an intrusion monitoring function of a virtual fence implemented using a radar sensor and a reflector. If an intrusion occurs in the straight section between the radar and the reflector as shown in FIG. 3, the amount of reflection returned from the reflector is drastically reduced, and this may be determined as the intrusion.

The reflector may be triangular pyramid shaped as shown in FIG. 3, but may have other shapes such as square pyramid and flat plate. In the present invention, the shape of the reflector may be used as a standard reflector, it may be used to produce a separate reflector.

A standard reflector is used to measure the radar performance. If the frequency or output of electromagnetic waves is known in advance, a reflector representing the amount of standard reflection reflected by the distance between the radar sensor and the reflector can be manufactured in advance by size. As shown in the upper formula of FIG. 4, the standard reflector has a larger radar cross section (RCS) according to the surface area of the reflector, and of course, increasing the reflector size can increase the detected distance. Therefore, when the reflector is disposed at a certain distance from the radar, if there is no obstruction between the radar and the reflector, the anticipated amount of electromagnetic wave reflection (RCS) may be known depending on the size of the reflector.

The radar can also measure the distance of the detected object using the time difference between the transmitted and reflected radio waves through Doppler signal analysis. This function perfectly reflects the reflected waves generated at distances other than the previously installed reflectors. It can be applied to ignore.

That is, the radar can measure the amount of reflection of the radio wave returning from the reflector at a certain distance, and can completely ignore the reflected wave outside the specific distance.

Therefore, based on this logic, using a radar and a reflector can easily implement a straight virtual fence. In this case, the size of the reflector used is much higher than the amount of reflection of the surrounding general object. The reason is that when other objects appear around the reflector, the variation in the amount of reflection coming back from the installation position of the reflector becomes large, which may affect the reliability of the virtual fence of the straight line. In the case of using the frequency band of 24 GHz, the actual size of the metal reflector, which reflects the reflection amount several ten times larger than the human reflection at a distance of 100 meters, is sufficient, so there is no problem in the virtual fence.

4 is a diagram illustrating the use of a reflector having a larger size as the length of the virtual fence becomes longer according to the present invention.

The standard reflector for radar is known in relation to the geometric size of the reflector with respect to the amount of electromagnetic wave reflection, as shown at the top of FIG. That is, if the material of the reflector is a metal reflecting 100% of electromagnetic waves, the reflecting amount is proportional to the maximum square root of the size. Therefore, even if the size of the reflector is increased a little, the amount of reflection can be significantly increased. 4 shows that the length of the virtual fence is increased by increasing the size of the reflector.

Such a method of determining the intrusion of the virtual fence based on a simple metal reflector and the reflection attenuation received by the radar can dramatically increase the length of the virtual fence, that is, the monitoring distance without increasing the number of radar sensors.

In general, electromagnetic waves have output limitations for each frequency band and according to the characteristics of electromagnetic waves spreading according to distance, as the distance increases, the amount of electromagnetic waves reflected by the object decreases in proportion to the distance. The detection of the object becomes impossible.

In order to solve this problem, the present invention, when the distance from the radar sensor to the standard reflector (which becomes the length of the virtual fence) increases, the size of the standard reflector is arranged to be large so that the amount of reflection by the standard reflector is not reduced. That is, as the distance from the radar sensor increases, the degree of spread of electromagnetic waves increases, so the amount of electromagnetic waves reflected by the small reflector decreases, so that the amount of reflection is small and the sensitivity decreases when an intrusion event occurs. However, if the distance from the radar sensor is large, if the size of the standard reflector is large, the spread electromagnetic waves can be reflected from the reflector, so the amount of reflection on the radar receiving antenna is not reduced. can do.

In other words, if an object enters between the receiving antenna and the reflector, the standard reflectance disappears or changes significantly. This can be recognized as an intrusion.

For example, a 1dBsm standard reflector is placed at 30m from the radar sensor, a 10dBsm standard reflector is placed at 100m, and a 20dBsm standard reflector is placed at 200m. If the radar sensor and the reflector are to be placed farther apart, a larger reflector is fabricated to perform the reflectance performance test, and then the reflectance result is obtained to construct a virtual fence.

In this way, even if the length of the virtual fence is increased, only the size of the reflector, which is a simple metal sheet, needs to be increased, thus eliminating the need to arrange multiple radar sensors and improving the technical performance of the radar sensor itself. Both ease of operation and ease of maintenance can be obtained.

5 is an example of an algorithm flow chart and intrusion determination based on the above logic. Electromagnetic waves radiated from the radar are reflected by reaching the reflector at a specific position. The distance and the amount of reflection of the initial reflector are measured and stored as initial values, and the amount of reflection is continuously measured and compared. The Doppler signal analysis completely ignores the incoming radio waves coming back from the reflector's installation location and at a different distance, thus creating a straight virtual fence between the radar and the standard reflector. If the amount of reflection of the reflector at the position where the radar was received decreases rapidly, it may be determined that an intrusion has occurred in the straight virtual fence formed by the radar sensor and the reflector. Therefore, only a radar and a reflector can produce a reliable straight virtual fence like a laser beam, and no misdetection of other free zones occurs.

 In addition, the virtual fence generated between the radar and the reflector in this way has a volume of X * Y size, as shown in the figure below, similar to managing arrays of dozens of laser pointers simultaneously. This has the advantage of controlling the sensitivity of the virtual fence. In the case of covering the entire virtual fence as shown in the case A on the right side of FIG. 5 and only partially covering the case as in the B case, the amount of reflection received from the radar is different. Can be controlled to respond only to large objects. This is also a great advantage in terms of preventing false detection.

Accordingly, the boundary area of the straight section like the laser beam can be formed by the radar sensor, and unlike the laser beam, it can adjust the sensitivity without any misunderstanding caused by environmental factors such as dust, fog, and rainwater, and adapts to the external environment. To excellent reliability.

 FIG. 6 shows a boundary system for a certain zone using a straight virtual fence. At this time, the system for the virtual fence of the straight line can operate the radar and the reflector, respectively, but can also be integrated into one case as shown in the bottom of FIG. The combination of radar and reflector in one module offers many advantages when creating a continuous virtual fence. Since the module is arranged at the starting point of the virtual fence, it will be referred to as a starting point module for convenience. As shown in the upper part of FIG. 6, the two-sided corner-shaped reflector having a flat plate or V-shaped cross section increases the amount of reflection even when only the height Y is increased, thereby producing and mass producing a reflector and a case having the same size with respect to X. In general, it is possible to make a module including two radars and one reflector in the case of a module disposed at the point E of FIG. 6 by including one radar and one reflector in the module. The starting module may be configured by putting the radar sensor and the reflector together in one case, but may be installed separately without the case. For example, depending on the environment, the radar sensor may be installed on a support capable of supporting and the reflector may be installed by another support.

In addition, when the case is made cylindrical, the direction of the reflector and the radar can be concealed, so it is easy to set up a secret surveillance zone.

6 illustrates one example of a starting module of various configurations, but may be modified in various ways.

7 is a diagram illustrating a correction method according to the topography of the reflector shape, size or non-flat structure when installing the virtual fence of the present invention.

7 shows a situation in which the reflector cannot reflect electromagnetic waves as the reflector is installed at the lower end of the starting module facing and placing the radar at the upper end of the starting module, and such a work is performed even when the terrain is not flat. This shows what is happening. In other words, the reflectors facing the radar should be horizontal to each other to have a high sensitivity boundary. Therefore, the radar and the corresponding reflector constituting the straight virtual fence boundary area should be able to level or adjust the vertical inclination of the reflector or radar sensor to face each other when it cannot be leveled.

7 shows that the radar and the reflector reflecting the electromagnetic waves emitted from the radar adjust the vertical angle and / or the position of the reflector so as to face each other through the electromagnetic waves. A position adjusting device that adjusts this automatically is placed in the starting module so that it can be automatically aligned. The device to adjust the angle and position can be easily made manually or automatically by using the support, spring adjustment knob or motor.

And it may include a server, a monitor, a mobile system for the alarm and control of the virtual fence using the radar sensor and the reflector as shown in FIG. In case of intrusion detection, the server may be provided with a control module that generates an alarm alarm such as a voice or a warning light and displays the corresponding area using an electronic map such as Google Map on the monitor.

FIG. 8 shows a straight line array arranged up and down as a modified embodiment of the straight virtual fence of the present invention. It is advantageous to the boundaries of large objects, and if the application module of this origin is modified more, a plurality of virtual fences can be realized.

Figure 9 shows that the battery is made of a mobile or installed in a straight virtual fence of the present invention by moving. Depending on the area of need and changes in the environment, the perimeter system can be deployed appropriately and can be installed in areas without electrical wiring.

Figure 10 shows the inclusion of a CCTV camera, a warning light, lighting, speakers, GPS sensors, etc. in the starting module of the present invention. By integrating them, the result of the boundary operation is notified to the target person and the administrator. The GPS ensures the positional accuracy of the boundary system from installation to management.

11 is a case constituting the base module of the present invention has a cylindrical exterior of a cylindrical cylinder or rhombus cross-section, including a hot wire is composed of a large horn of the inclined surface so that rainwater flows down or removed as fast as possible. Shows. This configuration helps to solve the boundary disturbance caused by rain or freezing.

FIG. 12 shows a principle of generating a plurality of straight virtual fences using the entire radio wave radiation region of one radar sensor as a modified embodiment of the present invention. This may further reduce the number of installation of the racer sensor. That is, due to the propagation characteristics of the radar, one or more reflectors reflecting the radio waves corresponding to one radar sensor by using the spreading of the radio waves are placed at different points in the radio wave region radiated from the radar sensor. In the case of FIG. 12, it is shown that two different virtual reflectors are formed at different points in the radio emission region for one radar sensor to form two straight virtual fences. It is shown that the rectangular boundary system was created by allowing two straight virtual fences with a ratio of 1: 2 of radar sensor to reflector to be adjacent to each other. The two reflectors at the bottom are arranged with a gap to serve as a kind of gate. This configuration allows for the implementation of many applied virtual boundary zones, while also reducing equipment costs and effort.

The rights of the present invention are not limited to the examples described above, but are defined by the claims, and it is understood that those skilled in the art can make various modifications and adaptations within the scope of the claims. Self-explanatory

No reference sign.

Claims (10)

In a straight line virtual boundary system,
A radar sensor having a transmitting antenna and a receiving antenna;
A reflector disposed at a predetermined distance from the radar sensor; And
And a control module for detecting an alarm and detecting an intrusion event between the radar sensor and the reflector with respect to the amount of reflection from the reflector received by the radar sensor.
Reflecting the electromagnetic wave transmitted from the transmitting antenna of the radar sensor at the reflector and receiving the radio wave reflected from the receiving antenna of the radar to measure the amount of reflection,
When there is no intrusion event between the radar and the reflector, it is determined that an incidence event is caused by a situation where the reflected amount is sharply reduced or changed based on a previously known reflection amount.
At least one of the radar sensor and the at least one reflector is installed inside the cross starting module so as to face in different directions,
The crossing origin module is disposed at a starting point of a boundary region, and is configured to transmit and receive electromagnetic waves with at least one other starting module disposed adjacent to the crossing origin module to form at least one virtual fence,
A first virtual fence is formed between the cross starting module and the first starting module through at least one radar sensor and at least one reflector installed to face the different directions, and the cross starting module and the second starting module of the A second virtual fence is formed therebetween, and a third virtual fence is formed between the cross origin module and the third origin module,
Some of the first virtual fence, the second virtual fence, and the third virtual fence formed through the cross starting module are formed based on electromagnetic waves emitted from the radar sensor installed inside the cross starting module, and the other part of the It is formed based on the electromagnetic wave transmitted from the radar sensor installed outside of the cross-point module,
The reflector is the size of the reflector is determined based on the standard amount of reflection reflected back by the distance between the radar sensor and the reflector,
The virtual boundary system of a straight line that can increase the distance for detecting the intrusion in accordance with the magnitude of the reflection amount. The straight line virtual boundary system according to claim 1, wherein the reflector includes a flat reflector, a columnar reflector having a length, or a dihedral corner reflector. The straight line virtual boundary system according to claim 1 or 2, wherein the radar sensor and the reflector are separately installed or are installed together in one case and configured as a starting point module arranged at the starting point of the boundary area. . The radar sensor of claim 3, wherein the origin module further comprises a position adjusting device for adjusting the altitude and azimuth of the reflector, wherein the reflector emits electromagnetic waves according to the size of the reflector included in the ups and downs of the terrain or the origin module. Virtual boundary system of a straight line, characterized in that the adjustable for. The straight line virtual boundary system according to claim 2, wherein the larger the distance from the radar sensor reflector in the virtual boundary system is, the larger the size of the reflector is. The method of claim 3, wherein the starting module comprises: a battery or a photovoltaic module; And moving means. The virtual boundary system of a straight line, further comprising a virtual boundary zone. The virtual boundary system of claim 3, wherein a plurality of baseline modules are arranged to form a closed virtual boundary zone, and a wired / wireless communication network is applied between the plurality of baseline modules to be controlled and managed through a central server. 8. The virtual boundary system of claim 7, wherein the origin module is configured by placing one or more radar sensors or one or more reflectors in one case to be disposed at intersections of the plurality of virtual boundary lines. The straight line virtual boundary system according to claim 3, wherein the case of the starting module includes a columnar shape, and further includes a CCTV camera, a GPS sensor, a warning light, an illumination, a speaker, a cover, or a heating wire. The straight line virtual boundary system according to claim 1, wherein at least one reflector reflecting electromagnetic waves is disposed on the one radar sensor to form a plurality of virtual boundaries of the straight line by one radar sensor.

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