A regional security radar and a method for automatically setting a security area

Abstract

The present invention discloses a regional security radar and a method for automatically setting a security area. The regional security radar includes a radar controller and a radar sensor; the radar controller includes a control circuit board and a touch screen; the radar sensor includes a radar cover, a radio frequency circuit board, a radio frequency shielding cover, a signal processing circuit board and a sensor housing; the control circuit board is connected to the touch screen through a cable; the radio frequency circuit board, the radio frequency shielding cover and the signal processing circuit board are located in the internal space formed by the radar cover and the sensor housing; the radio frequency circuit board is installed on the radio frequency shielding cover and connected to the signal processing circuit board through a cable; a transmitting antenna and a receiving antenna are provided on the radio frequency circuit board; the control circuit board is connected to the signal processing circuit board through a cable. The present invention can implement security monitoring of the area and can provide real-time and accurate distance and azimuth information of the target.

Description

Technical Field

[0001] The invention relates to a regional security radar and a method for automatically setting a security area based on the regional security radar. Background Art

[0002] Common security systems, such as physical fences, infrared counter-radiation products, electronic fences and video surveillance, all have various defensive defects. They are either limited by the principle itself and can only form a warning line; or are affected by the weather and the product performance drops significantly in bad weather (rain, snow, fog, strong wind); or are affected by light and the security effect varies greatly during the day or at night, resulting in false alarms and missed alarms, and cannot accurately provide the distance and angle information of the target.

[0003] In addition, after the radar or other monitoring system obtains the target coordinates, it is necessary to determine whether the target is within the warning zone, so the boundary of the warning zone needs to be set. For example, the warning zone of the oil tank area of ​​a gas station is generally a quadrilateral. At present, the boundary of the warning zone is mostly measured on the spot, which is time-consuming and labor-intensive. Complex intelligent algorithms often require more memory and computing resources, and often require computers or cloud computing. Cloud computing involves network communication, which increases the complexity of the system. Summary of the invention

[0004] The purpose of the present invention is to provide a regional security radar so as to implement security monitoring on the region, and when a target enters the monitoring area, the distance and direction information of the target can be provided in real time and accurately.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A regional security radar, comprising a radar controller and a radar sensor;

[0007] Among them, the radar controller includes a control circuit board and a touch display screen;

[0008] The radar sensor includes a radar cover, a radio frequency circuit board, a radio frequency shielding cover, a signal processing circuit board and a sensor housing;

[0009] The control circuit board is connected to the touch display screen via a cable;

[0010] The radio frequency circuit board, the radio frequency shielding cover and the signal processing circuit board are located in the inner space formed by the radar cover and the sensor housing;

[0011] The radio frequency circuit board is mounted on the radio frequency shielding cover and is connected to the signal processing circuit board through a cable;

[0012] A transmitting antenna and a receiving antenna are provided on the radio frequency circuit board;

[0013] The control circuit board is connected to the signal processing circuit board through a cable.

[0014] Preferably, the regional security radar further comprises an audible and visual alarm, which is mounted on the outside of the sensor housing;

[0015] The control circuit board is connected with the sound and light alarm through a cable.

[0016] Preferably, there is one transmitting antenna and three receiving antennas on the radio frequency circuit board; wherein,

[0017] Both the transmitting antenna and the receiving antenna are planar microstrip array antennas.

[0018] Preferably, the transmitting antenna and the receiving antenna are arranged in parallel, and the three receiving antennas are located on the same side of the transmitting antenna;

[0019] In order from near to far distance from the transmitting antenna, the three receiving antennas are as follows:

[0020] a first receiving antenna, a second receiving antenna, and a third receiving antenna;

[0021] Define λ as a wavelength, then:

[0022] The distance between the first receiving antenna and the second receiving antenna is λ; the distance between the second receiving antenna and the third receiving antenna is 1.5λ.

[0023] Preferably, a sealing ring is provided on the inner side of the radome.

[0024] Preferably, a radio frequency shielding cavity is provided on the radio frequency shielding cover corresponding to the transmitting antenna and the receiving antenna respectively;

[0025] Wave absorbing material is installed in each radio frequency shielding cavity.

[0026] Preferably, the control circuit board adopts an STM32 single-chip microcomputer circuit board, and the signal processing circuit board adopts a DSP circuit board.

[0027] Preferably, the radar controller further comprises a controller housing, on which a display screen mounting opening and a wire outlet hole are provided;

[0028] The control circuit board is installed on the inner side of the controller housing, and the touch screen is installed on the screen installation opening;

[0029] The cable wire led out from the control circuit board passes through the controller housing through the wire outlet hole.

[0030] In addition, the present invention also proposes a method for automatically setting a security area, which is based on the above-mentioned regional security radar so as to automatically set the security area according to the walking trajectory of the staff.

[0031] In order to achieve the above object, the present invention adopts the following technical scheme:

[0032] A method for automatically setting a security zone comprises the following steps:

[0033] s1. First, ten sets of short trajectories are calculated to track the target points detected by the regional security radar in real time;

[0034] s2. Then select three groups of middle trajectories from the target points of the short trajectories;

[0035] s3. Then select a set of long trajectories from the target points of the three sets of trajectories;

[0036] s4. Find the target points that form a closed area in the long trajectory, and then divide these target points into four groups. Perform straight line fitting on each group to obtain a straight line. The intersection of each straight line is the vertex of the security area, and the security area is thus fitted.

[0037] The present invention has the following advantages:

[0038] The present invention provides a regional security radar that can provide real-time and accurate information on the distance and azimuth of a target, so as to solve the problem of existing security products being affected by the environment, realize regional monitoring, and avoid underreporting. The present invention also provides a method for automatically setting a security area, which does not require excessive computing and memory resources, realizes automatic trajectory capture based on the regional security radar, automatically selects effective points, and automatically draws a security area according to the walking trajectory of the staff. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the structure of the radar controller in Example 1 of the present invention.

[0040] Figure 2 Schematic diagram of the structure of the radar sensor in Example 1 of the present invention.

[0041] Figure 3 This is an exploded view of the radar sensor in Example 1 of the present invention.

[0042] Figure 4 The structural principle of the regional security radar in Example 1 of the present invention is shown in the figure.

[0043] Figure 5 This is a simplified flow chart of the regional security radar in Example 1 of the present invention.

[0044] Figure 6 Schematic diagram of the structure of the microstrip unit in Example 1 of the present invention.

[0045] Figure 7 Schematic diagram of a person's behavior trajectory in Example 2 of the present invention.

[0046] Figure 8 Schematic diagram of the short trajectory in Example 2 of the present invention.

[0047] Fig. 9 This is a schematic diagram of the trajectory in Example 2 of the present invention.

[0048] Fig.10 This is a schematic diagram of a real human walking trajectory captured in Example 2 of the present invention.

[0049] Fig.11 This is a schematic diagram of determining points surrounding a security zone in Embodiment 2 of the present invention.

[0050] Fig.12 To determine Fig.11 Schematic diagram of the two points A and B farthest from the center.

[0051] Fig.13 To determine Fig.12 Schematic diagram of the two points C and D farthest from the line connecting points A and B.

[0052] Fig.14 Based on Fig.13 The obtained points are fitted into a schematic diagram of a straight line.

[0053] Fig.15 Schematic diagram of the process of automatically setting the security area in Embodiment 2 of the present invention.

[0054] Fig.16 This is a schematic diagram of the process of obtaining a short trajectory in Embodiment 2 of the present invention.

[0055] Fig.17 This is a schematic diagram of the process of obtaining the medium trajectory and the long trajectory in Example 2 of the present invention.

[0056] Fig.18 The figure is a schematic diagram of the process of determining a security area in Embodiment 2 of the present invention.

[0057] Among them, 1-radar controller, 2-radar sensor, 3-sound and light alarm, 4-controller housing, 5-touch screen, 6-screen installation port, 7-radar cover, 8-RF circuit board;

[0058] 9-RF shielding cover, 10-signal processing circuit board, 11-sensor housing, 12-bolts, 13-transmitting antenna, 14-receiving antenna, 15-intermediate frequency amplifier, 16-conductor unit, 17-dielectric substrate, 18-ground plate. DETAILED DESCRIPTION

[0059] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0060] Example 1

[0061] This embodiment 1 describes a regional security radar, which is applicable to but not limited to the security of the tank area of ​​a gas station.

[0062] like Figures 1 to 3 As shown, the regional security radar includes a radar controller 1, a radar sensor 2 and an audible and visual alarm 3.

[0063] The radar controller 1 comprises a controller housing 4 , a power supply circuit board (not shown), a control circuit board (not shown) and a touch display screen 5 . The power supply circuit board and the control circuit board are both located inside the controller housing 4 .

[0064] The power supply circuit board and the control circuit board can be fixed to the controller housing 4 by bolts, for example.

[0065] The control circuit board is connected to the touch display screen 5 via a cable to achieve human-computer interaction. The information displayed on the touch display screen 5 at least includes the debugging settings and interface display of the radar system.

[0066] In addition, a display screen installation opening 6 and a wire outlet hole (not shown) are provided on the controller housing 4 .

[0067] The touch screen 5 is installed on the display screen installation opening 6 (sealing rings can be provided at each corner of the installation opening to ensure tightness between the touch screen 5 and the display screen installation opening 6).

[0068] The cables led out from the control circuit board pass through the controller housing 4 through the cable outlet hole.

[0069] In addition, an interface is reserved on the radar controller 1 to realize signal interlocking control with other devices or function expansion.

[0070] The control circuit board in this embodiment 1 preferably adopts an STM32 single-chip computer circuit board.

[0071] like Figure 2 and Figure 3 As shown, the radar sensor 2 includes a radar cover 7, a radio frequency circuit board 8, a radio frequency shielding cover 9, a signal processing circuit board 10 and a sensor housing 11.

[0072] The radome 7 can be mounted together with the sensor housing 11 by means of bolts 12 , for example.

[0073] An inner space is formed between the radome 7 and the sensor housing 11 .

[0074] The radio frequency circuit board 8, the radio frequency shielding cover 9 and the signal processing circuit board 10 are all located in the above-mentioned internal space.

[0075] The radio frequency circuit board 8 is mounted on the radio frequency shielding cover 9 and connected to the signal processing circuit board 10 via a cable. Specifically, the radio frequency circuit board 8 can be connected to the signal processing circuit board 10 via a cable with a PIN socket.

[0076] A transmitting antenna 13 and a receiving antenna 14 are provided on the radio frequency circuit board 8 .

[0077] The transmitting antenna 13 transmits a radio frequency signal, the radio frequency signal is reflected by an object, and the receiving antenna 14 receives the returned radio frequency signal.

[0078] In addition, components such as an intermediate frequency amplifier 15 are also provided on the radio frequency circuit board 8 .

[0079] The returned radio frequency signal is amplified by the intermediate frequency amplifier 15 and then processed by the signal processing circuit board 10, thereby obtaining the distance and azimuth angle information of the target. The principle of radar is introduced below.

[0080] The control circuit board is connected to the signal processing circuit board 10 via a cable to realize power supply and signal transmission functions.

[0081] The signal processing circuit board 10 in the present embodiment 1 may be, for example, a DSP circuit board.

[0082] The sound and light alarm 3 in the present embodiment 1 can be installed on the outside of the sensor housing 11 by means of bolts.

[0083] The control circuit board is connected to the sound and light alarm 3 through a cable.

[0084] The radar controller 1 serves as a human-computer interaction window for the FMCW radar system, including equipment debugging, display of target distance and azimuth information, and sound and light alarms.

[0085] The working status of radar sensor 2, "normal", "alarm" and "fault", are all displayed on the controller side.

[0086] When the radar sensor 2 is correctly connected to the radar controller 1 via the cable, a "normal" status indication is displayed on the touch screen 5. In this state, the corresponding settings of the radar sensor 2 and other function settings of the system are performed.

[0087] When the setting is completed and an alarm occurs, the touch display screen 5 switches to the "alarm" status indication and a voice alarm is issued at the same time.

[0088] When the radar sensor 2 is correctly connected to the radar controller 1 , the radar sensor 2 is powered normally.

[0089] The transmitting antenna 13 transmits a radio frequency signal, which is reflected by an object, and the receiving antenna 14 receives the returned radio frequency signal. The signal is amplified and processed by the signal processing circuit board 10 to obtain the distance and azimuth angle information of the target.

[0090] The radar sensor 2 communicates with the radar controller 1 to implement corresponding functions, including alarm and signal output.

[0091] This embodiment solves the problem of existing security products being affected by the environment, realizes regional monitoring, and avoids missed reports.

[0092] like Figure 4 As shown, there is one transmitting antenna 13 and three receiving antennas 14 on the radio frequency circuit board.

[0093] The radio frequency signal is transmitted into space via the transmitting antenna 13 . When encountering a target, the signal is reflected and received by the receiving antenna 14 . After being mixed and amplified, the signal enters the signal processing circuit board 10 .

[0094] After performing a series of processing on the received signal, the signal processing circuit board 10 analyzes the target distance, angle and other information contained in the signal for subsequent processing (sending this information to the control circuit board).

[0095] like Figure 5 As shown in the figure, the general processing flow of radar signals is as follows:

[0096] The received radar echo signal enters the signal processing circuit board 10 after being amplified, and after Fourier transformation and adaptive cancellation in the signal processing circuit board 10, the distance and angle information of the target contained in the signal are analyzed through calculation.

[0097] This embodiment uses the above radar signal processing flow to accurately obtain the distance and azimuth angle information of the target in real time.

[0098] Wherein, both the transmitting antenna 13 and the receiving antenna 14 are planar microstrip array antennas.

[0099] Each planar microstrip array antenna is composed of multiple microstrip units. The structure of the microstrip unit is as follows: Figure 6 shown.

[0100] like Figure 6 As shown, each microstrip unit includes a conductor unit 16 (including a feed line), a dielectric substrate 17 and a ground plane 18.

[0101] The structures of the microstrip unit and the planar microstrip array antenna are both known structures and are only briefly described here.

[0102] The transmitting antenna 13 and the receiving antenna 14 are arranged in parallel, and the three receiving antennas are located on the same side of the transmitting antenna.

[0103] The parallel arrangement here means that the transmitting antenna 13 and the receiving antenna 14 are arranged in parallel on the radio frequency circuit board 8 .

[0104] In order from near to far distance from the transmitting antenna 13, the three receiving antennas 14 are arranged as follows:

[0105] A first receiving antenna a, a second receiving antenna b and a third receiving antenna c.

[0106] This embodiment uses the structure of one transmitting antenna and three receiving antennas to parse the distance and angle information of the target contained in the signal, and at the same time solve the deambiguation problem of existing antenna angle measurement.

[0107] The principle of deambiguation of existing antenna angle measurement in this embodiment 1 is described in detail below:

[0108] The current more effective method is to use three antennas to measure angles, that is, the first receiving antenna a and the third receiving antenna c with a large spacing are used to obtain high-precision measurements, while the first receiving antenna a and the second receiving antenna b with a small spacing are used to solve the multi-value problem.

[0109] Assume the target is in the direction of θ, λ is a wavelength, and the distance between the first receiving antenna a and the second receiving antenna b is d ab , the distance between the first receiving antenna a and the third receiving antenna c is d ac .

[0110] Choose d appropriately ab , so that the phase difference between the signals received by antennas a and b satisfies within the angle measurement range:

[0111]

[0112] However, when the difference between the measurement targets is too large (such as large vehicles and pedestrians), the echo intensity of the large vehicle outside the 6db angle of the antenna will be greater than that of the pedestrian within the 6db angle. In this case, d ab Needs to be less than λ / 2.

[0113] If the distance between two receiving antennas is limited to λ / 2, the array size of each receiving antenna will be affected. At this time, the receiving antenna can only be a single-row antenna, so the antenna gain is insufficient, which affects the detection distance.

[0114] In order to solve the contradiction between the requirement of deblurring that the distance between receiving antennas is small enough and the requirement of antenna array size that the distance between receiving antennas is large enough, the present embodiment sets the distances between the three receiving antennas to be d ab=λ,d bc =1.5λ,d ac =2.5λ.

[0115] The purpose of deblurring can be achieved by setting the above distance. ac The result is a five-fold improvement in measurement accuracy.

[0116] In addition, in order to ensure the sealing performance of the radar sensor 2 , the present embodiment further provides a sealing ring (not shown) on the inner side of the radar cover 7 to ensure the waterproof and dustproof performance of the radar sensor 2 .

[0117] A radio frequency shielding cavity (not shown) is respectively provided on the radio frequency shielding cover 9 corresponding to the transmitting antenna and the receiving antenna to realize the separate cavity protection of the antenna. In addition, absorbing materials are installed in each radio frequency shielding cavity to avoid interference of radio frequency signals.

[0118] Example 2

[0119] This embodiment 2 describes a method for automatically setting a security area, so as to automatically set the security area according to the walking trajectory of the staff, eliminating the shortcomings of field measurement and complex calculations.

[0120] The implementation of the automatic security zone setting method in this embodiment 2 is based on the regional security radar in the above-mentioned embodiment 1.

[0121] It can be seen from the description of Example 1 that the distance and azimuth information of the target point can be obtained through the regional security radar.

[0122] In the second embodiment, only one person needs to walk around the security area to automatically form a circle. Any starting point can be selected and the normal speed can be used. There is no need to deliberately control the speed. It does not matter if it is interrupted in the middle, just walk around one more circle.

[0123] The process of determining the security area does not require any operating equipment, the calculation process takes up few resources, it can be implemented on a single-chip microcomputer, and eliminates the errors caused by the randomness of people's walking trajectories.

[0124] The steps and principles of the method for automatically setting security areas in this embodiment 2 are described in detail below.

[0125] like Fig.15 As shown, a method for automatically setting a security area includes the following steps:

[0126] s1. First, ten sets of short trajectories are calculated to track the target points detected by the regional security radar in real time.

[0127] Each group of short trajectories has 10 target points.

[0128] s2. Then select three groups of medium trajectories from the target points of the short trajectories.

[0129] Each set of trajectories includes 100 target points.

[0130] s3. Then select a set of long trajectories from the target points of the three sets of trajectories;

[0131] Among them, each long trajectory has 800 target points.

[0132] s4. Find the target points that form a closed area in the long trajectory, and then divide these target points into four groups. Perform straight line fitting on each group to obtain straight lines. The intersection points of the straight lines are the vertices of the (quadrilateral) security area, and the security area is thus fitted.

[0133] A person goes from indoors to the security area and walks around the security area. The person's behavior trajectory is as follows: Figure 7 shown.

[0134] Depend on Figure 7 It is not difficult to see that people walking cannot guarantee that the landing point is uniform at every moment, and it is impossible to walk in a standard straight line. In addition, interference points will pop up from time to time around (although the staff will try to let irrelevant people leave when automatically setting the area, it cannot guarantee 100% interference-free), and the memory space of the single-chip computer cannot store all the points for a long time for processing, so data must be collected and processed at the same time.

[0135] like Fig.16 As shown in the figure, a temporary storage array with 10 storage spaces and 10 points is established. Each point represents the coordinates of the target point measured at a moment. The continuous coordinates of the same array are used for quadratic regression to predict the coordinates of the next point. When the next moment comes, the target points near the predicted point are placed in the temporary storage array space to form 10 tracks. When the track is interrupted, the track is cleared. When a new track appears, it is placed in an empty temporary storage array. Figure 8 The points are grouped into short trajectories as shown.

[0136] like Fig.17 As shown in the figure, three middle track spaces are established (each space can accommodate 100 points), and the three short tracks with the largest dispersion are stored in the middle track space. When the track is interrupted, the track space is cleared. If it is always concentrated in a small area, it is also cleared. If it is not interrupted and is not concentrated in one area, the new points that appear in the track are continuously put into the middle track. Fig. 9 As shown, establishing three intermediate trajectory spaces can effectively ensure that the required target trajectory can be effectively captured.

[0137] A long trajectory space is established to accommodate 800 coordinate points at a time, and the one with the largest dispersion among the three medium trajectories is placed in the long trajectory space. 800 points can ensure that a person can walk around the security area at a normal walking speed. The 100-point medium trajectory can also ensure that the real pedestrians can be selected. 10 groups of short trajectories ensure that all trajectories appearing on the scene can be tracked, and the space occupied is small, and the number to be processed is small.

[0138] The three types of trajectory spaces only require 1,200 points of storage space in total, and the microcontroller has enough resources for calculation. This can capture the real walking trajectory of a person and exclude other unnecessary interference trajectories. Fig.10 shown.

[0139] like Fig.18 As shown in the figure, in a person's walking trajectory, when there are enough points (more than 50 points) and the distance is close enough (less than 0.7 meters), it is judged that a closed loop is formed, and the trajectory points between the two points are taken out and judged as points surrounding the security area. Fig.11 As shown. In the previous step, find the maximum X coordinate, the maximum Y coordinate, the minimum X coordinate, the minimum Y coordinate of all the points around the security area, calculate the average, get the center point, find the point farthest from the center: point A, and then find the point farthest from A: point B. Fig.12 As shown. Find the point farthest from line segments A and B: point D, and the point farthest from point D: point C. Fig.13 As shown. The points between A and C are divided into group 1, the points between C and B are divided into group 2, the points between B and D are divided into group 3, and the points between D and A are divided into group 4. Linear fitting is performed on the points of the four groups to obtain four lines. The intersection of the four lines is the four vertices of the quadrilateral that needs to be secured or alerted, as shown in Fig.14 shown.

[0140] The method of solving the scope of the security area through the above steps is simple and does not require too much computing and memory resources. It can automatically capture the trajectory, automatically screen out the valid points, and automatically draw the security area according to the walking trajectory of the staff.

[0141] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any technician familiar with the field under the guidance of this specification fall within the essential scope of this specification and should be protected by the present invention.

Claims

1. A regional security radar, characterized in that: including a radar controller and a radar sensor; Among them, the radar controller includes a control circuit board and a touch display screen; The radar sensor includes a radar cover, a radio frequency circuit board, a radio frequency shielding cover, a signal processing circuit board and a sensor housing; The control circuit board is connected to the touch display screen via a cable; The radio frequency circuit board, the radio frequency shielding cover and the signal processing circuit board are located in the inner space formed by the radar cover and the sensor housing; The radio frequency circuit board is mounted on the radio frequency shielding cover and is connected to the signal processing circuit board through a cable; A transmitting antenna and a receiving antenna are provided on the radio frequency circuit board; The control circuit board is connected to the signal processing circuit board through a cable; The radio frequency circuit board has one transmitting antenna and three receiving antennas; wherein, Both the transmitting antenna and the receiving antenna adopt planar microstrip array antenna; The transmitting antenna and the receiving antenna are arranged in parallel, and the three receiving antennas are located on the same side of the transmitting antenna; In order from near to far distance from the transmitting antenna, the three receiving antennas are as follows: a first receiving antenna, a second receiving antenna, and a third receiving antenna; Define λ as a wavelength, then: The distance between the first receiving antenna and the second receiving antenna is λ; the distance between the second receiving antenna and the third receiving antenna is 1.5λ.

2. The regional security radar according to claim 1, characterized in that: The regional security radar also includes an audible and visual alarm, which is installed on the outside of the sensor housing; The control circuit board is connected with the sound and light alarm through a cable.

3. The regional security radar according to claim 1, characterized in that: A sealing ring is arranged inside the radome.

4. The regional security radar according to claim 1, characterized in that: The radio frequency shielding cover is provided with a radio frequency shielding cavity corresponding to the transmitting antenna and the receiving antenna respectively; Wave absorbing material is installed in each radio frequency shielding cavity.

5. The regional security radar according to claim 1, characterized in that: The control circuit board adopts an STM32 single-chip computer circuit board, and the signal processing circuit board adopts a DSP circuit board.

6. The regional security radar according to claim 1, characterized in that: The radar controller also includes a controller housing, on which a display screen mounting opening and a wire outlet hole are provided; The control circuit board is installed on the inner side of the controller housing, and the touch screen is installed on the screen installation opening; The cable wire led out from the control circuit board passes through the controller housing through the wire outlet hole.

7. A method for automatically setting a security area, based on the regional security radar according to any one of claims 1 to 6; It is characterized in that The method for automatically setting a security area comprises the following steps: s1. First, ten sets of short trajectories are calculated to track the target points detected by the regional security radar in real time; s2. Then select three groups of middle trajectories from the target points of the short trajectories; s3. Then select a set of long trajectories from the target points of the three sets of trajectories; s4. Find the target points that form a closed area in the long trajectory, and then divide these target points into four groups. Perform straight line fitting on each group to obtain straight lines. The intersection of each straight line is the vertex of the security area, and the security area is thus fitted.

8. The method for automatically setting security areas according to claim 7, characterized in that: Each group of short trajectories has 10 target points, each group of medium trajectories has 100 target points, and each group of long trajectories has 800 target points.

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