surveillance system

Abstract

This improves the accuracy of measurement data from 3D sensors in surveillance systems that use 3D sensors to detect objects within a surveillance area. [Solution] A surveillance system according to one embodiment of the present invention comprises a 3D sensor 110 installed facing a surveillance area, and a server 140 that detects objects within the surveillance area based on measurement data obtained by the 3D sensor 110, and the server 140 controls the 3D sensor 110 to change the irradiation range of the laser light and / or the output intensity of the laser light in response to the detection of an object from the surveillance area.

Description

[Technical Field]

[0001] The present invention relates to a surveillance system that uses a 3D sensor to detect objects within a surveillance area. [Background technology]

[0002] Conventionally, surveillance systems have been developed that use 3D sensors to detect intruders, flying objects, and other intrusions in areas where safety must be ensured, such as restricted areas, highways, and railway tracks.

[0003] Prior art in the technical field of the present invention includes the following: For example, Patent Document 1 discloses that in an obstacle detection system that detects obstacles using radar reflection intensity, scan data of a partial area where the radar reflection intensity is equal to or greater than a threshold value from the start of scanning is excluded from reference data for obstacle detection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-65721 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional surveillance systems, as shown in Figure 1, it was possible to measure the position and distance of a reflection point based on the time it took for laser light 12 emitted from a 3D sensor 10 to hit an object in the surveillance area and return reflected light 14. It was also possible to determine the presence or absence of an intruder based on the number and density (point cloud) of reflected light 14, and to determine whether an intruder was in a restricted area or an area requiring safety by the distance (position) measured from the angle and time of reflected light 14.

[0006] However, the range of the laser light 12 emitted from the 3D sensor 10 remains constant regardless of whether an intruder is present, and the number of frames of measurement data that can be acquired per second is also constant. This limits the ability to track fast-moving intruders or acquire detailed data on intruders. Furthermore, the output intensity of the laser light 12 from the 3D sensor 10 is set to measure the entire monitoring area at an intensity that does not affect the human eye (eye-safe), and it cannot be adjusted depending on the subject. For these reasons, the accuracy of the measurement data acquired by the 3D sensor 10 is insufficient.

[0007] The present invention has been made in consideration of the above-described conventional circumstances, and aims to improve the accuracy of measurement data obtained by a 3D sensor. [Means for solving the problem]

[0008] A surveillance system according to one embodiment of the present invention comprises a 3D sensor installed facing a surveillance area, and a server that detects objects within the surveillance area based on measurement data obtained by the 3D sensor, and the server controls the frame rate of the measurement data of the 3D sensor to increase in response to the detection of an object from the surveillance area.

[0009] Here, in the above-mentioned surveillance system, the server may be configured to increase the frame rate of the measurement data of the 3D sensor by controlling the irradiation range of the laser light of the 3D sensor to be limited to the periphery of the object when an object is detected in the surveillance area.

[0010] In addition, in the above-mentioned monitoring system, the server may be configured to, in response to detection of an object in the monitoring area, control the laser light irradiation range of the 3D sensor to the periphery of the object, as well as control the output intensity of the laser light of the 3D sensor to be changed.

[0011] In addition, in the above surveillance system, the 3D sensor has a first operating mode in which it acquires measurement data at a first frame rate and a second operating mode in which it acquires measurement data at a second frame rate higher than the first frame rate, and is normally set to operate in the first operating mode, and the server may be configured to increase the frame rate of the measurement data of the 3D sensor by controlling the 3D sensor to switch from the first operating mode to the second operating mode in response to the detection of an object from the surveillance area.

[0012] A surveillance system according to another aspect of the present invention comprises a 3D sensor installed facing a surveillance area and a server that detects objects within the surveillance area based on measurement data obtained by the 3D sensor, and the server controls the change in output intensity of the laser light of the 3D sensor in response to the detection of an object from the surveillance area.

[0013] Here, in the above-mentioned monitoring system, the server may be configured to control the output intensity of the laser light of the 3D sensor to change to an intensity according to the characteristics of the object when an object is detected in the monitoring area.

[0014] In addition, in the above surveillance system, the server may be configured to perform control to reduce the output intensity of the laser light from the 3D sensor when the object detected from the surveillance area is a person.

[0015] In addition, in the above surveillance system, the server may be configured to control the 3D sensor to increase the output intensity of the laser light when further analysis is required regarding an object detected in the surveillance area.

[0016] In addition, in the above-mentioned monitoring system, the server may be configured to control the output intensity of the laser light of the 3D sensor to change in response to the detection of an object from the monitoring area, as well as to control the irradiation range of the laser light of the 3D sensor to be limited to the periphery of the object.

[0017] In addition, in the above surveillance system, the server may be configured to control the output intensity of the laser light of the 3D sensor to change only around the object when an object is detected in the surveillance area. [Effects of the Invention]

[0018] According to the present invention, it is possible to improve the accuracy of measurement data obtained by a 3D sensor. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating an overview of the detection principle of a 3D sensor in a conventional system. [Figure 2] 1 is a diagram showing a schematic configuration of a monitoring system according to an embodiment of the present invention; [Figure 3] FIG. 3 is a diagram illustrating an example of the configuration of a server in the monitoring system of FIG. 2. [Figure 4] FIG. 1 is a diagram illustrating an overview of a frame rate control function. [Figure 5] FIG. 10 is a diagram showing an overview of a laser output intensity control function. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described with reference to the drawings. Here, an example of a configuration will be described in which an object detection function using a 3D sensor is added to a monitoring system that performs 24-hour monitoring using a general visible light camera. An example of such a monitoring system is a track monitoring system that detects objects such as intruders and flying objects in restricted areas such as railroad tracks to ensure the safety of train operations. For example, the track monitoring system monitors restricted areas using a 3D sensor, and when an object such as an intruder or flying object is detected, the system photographs the object using a visible light camera and displays the image on a monitoring terminal.

[0021] Fig. 2 shows a schematic configuration of a monitoring system according to an embodiment of the present invention. The monitoring system in Fig. 2 includes a 3D sensor 110, a visible light camera 120, a network switch 130, a server 140, and a monitoring terminal 150.

[0022] Server 140 and monitoring terminal 150 are realized by a computer equipped with hardware resources such as a processor and memory, and are configured to implement functions and processes related to the present invention by reading a predetermined program from the memory and executing it with the processor. Server 140 and monitoring terminal 150 may be realized by a single computer, or may be realized by multiple computers operating in cooperation with each other.

[0023] One or more visible cameras 120 are installed so as to capture images of the monitored area, including restricted areas. The camera images captured by the visible cameras 120 are transmitted to a server 140 and a monitoring terminal 150 via a network switch 130. Users such as monitors can check the status of the monitored area by viewing the camera images displayed on the monitoring terminal 150.

[0024] One or more 3D sensors 110 are installed near the visible camera 120 so as to detect objects within the monitoring area. The 3D sensor 110 is used to detect foreign objects such as intruders and flying objects. In this example, a LiDAR (Light Detection and Ranging) sensor is used as the 3D sensor 110, but this is just one example, and various types of 3D sensors can be used. The 3D sensor 110 generates measurement data by irradiating the monitoring area with laser light and acquiring the return value (e.g., reflection intensity). The measurement data is generated for each frame in which the monitoring area is scanned once. Examples of the measurement data include point cloud data representing three-dimensional coordinate information and brightness information of points where reflection intensity equal to or greater than a predetermined value is obtained. Such measurement data is transmitted to the server 140 and the monitoring terminal 150 via the network switch 130.

[0025] The server 140 determines the state of objects in the monitoring area based on the measurement data received from the 3D sensor 110. The server 140 can determine the presence or absence of objects in the monitoring area and analyze the characteristics of the objects (position, distance, size, shape, type, etc.) by, for example, using a background subtraction method that calculates the difference between the current measurement data received from the 3D sensor 110 and measurement data (background information) previously obtained when there is no object to be detected (such as an intruder or flying object). Note that the background information data that can be obtained from the 3D sensor 110 is based on the use of a sensor that can consistently obtain stable data for each frame.

[0026] Furthermore, when it is determined that an object is present, the server 140 controls the visible camera 120 to capture an image of the object based on the characteristics of the object, and displays the camera image on the monitoring terminal 150 for a user such as a monitor to confirm. At this time, the measurement data obtained by the 3D sensor 110 may also be displayed on the monitoring terminal 150. Note that it is difficult to determine the state of the object in detail by simply visualizing and displaying measurement data such as point cloud data. Therefore, in order to be able to determine the state of the object in more detail, for example, a detailed data determination process may be performed on the application side of the monitoring terminal 150, and the results may also be displayed.

[0027] The above is an explanation of the object detection, which is the basic operation of the monitoring system of this example. Here, the monitoring system of this example is provided with a mechanism for improving the accuracy of the measurement data obtained by the 3D sensor 110.

[0028] 3 shows an example of the configuration of a processing unit related to a mechanism for improving the accuracy of measurement data obtained by the 3D sensor 110, among the processing units included in the server 140. The server 140 shown in FIG. 3 includes a measurement data acquisition unit 141, an object detection unit 142, and a sensor control unit 143.

[0029] The measurement data acquisition unit 141 acquires measurement data from the 3D sensor 110 via the network switch 130. In this example, point cloud data including distance information and reflection intensity information for each of a plurality of points (point cloud) within the monitoring area is acquired from the 3D sensor 110 as measurement data.

[0030] The object detection unit 142 detects objects within the monitoring area based on the measurement data acquired from the 3D sensor 110. In this example, object detection is performed using the background subtraction method described above, but other methods may also be used for object detection. Objects to be detected by the object detection unit 142 include, for example, foreign objects such as intruders and flying objects.

[0031] The sensor control unit 143 performs control to improve the accuracy of the measurement data of the 3D sensor 110 in response to the detection of an object in the monitoring area by the object detection unit 142. The sensor control unit 143 in this example has, as its main functions, a laser irradiation range control function and a laser output intensity control function. Each function will be described below.

[0032] (1) Laser irradiation range control function The laser irradiation range control function is a function that controls changing the irradiation range of the laser light of the 3D sensor 110 in response to the detection of an object (foreign object such as an intruder or a flying object) in the monitoring area. Normally, as shown in the left diagram of FIG. 4, the 3D sensor 110 irradiates the laser light so as to scan the entire laser irradiation range 201, thereby monitoring the entire monitoring area. In this case, the number of frames that can be captured per second is set to n (i.e., n frames / second). When an object is detected in the monitoring area, the sensor control unit 143 controls the laser to scan only a local range 202 that is limited to the periphery of the detected object, as shown in the right diagram of FIG. 4. That is, the sensor control unit 143 transmits a control signal to the 3D sensor 110 to instruct laser scanning limited to the local range 202.

[0033] The 3D sensor 110 changes the irradiation range of the laser light in accordance with the control signal received from the server 140, and irradiates the laser light only around the detected object (i.e., local area 202). This allows one scan to be completed in a shorter time than scanning the entire laser irradiation range 201, thereby increasing the frame rate of the measurement data related to the detected object. In other words, the frame rate of the measurement data related to the detected object can be increased from n frames / second to m frames / second (where m is greater than n). As a result, for example, when a fast-moving object is detected, the detected object can be accurately tracked. Furthermore, since the amount of measurement data related to the detected object increases, the characteristics of the detected object can be analyzed more accurately.

[0034] It should be noted that while limited laser irradiation is being performed on the local area 202, it is not possible to grasp the status of other areas within the laser irradiable area 201. In this case, if left as is, there is a possibility that an object that newly enters the monitored area will be missed. Therefore, while limited laser irradiation is being performed on the local area 202, laser irradiation may be performed on the entire laser irradiable area 201 at regular frame intervals. This makes it possible to reduce the risk of missing another object that newly enters the monitored area.

[0035] (2) Laser output intensity control function The laser output intensity control function is a function that controls the change of the output intensity of the laser light from the 3D sensor 110 in response to the detection of an object (foreign object such as an intruder or flying object) in the monitored area. Normally, the 3D sensor 110 irradiates the monitored area with laser light of a predetermined output intensity. When an object is detected in the monitored area, the sensor control unit 143 transmits a control signal to the 3D sensor 110 instructing it to change the output intensity of the laser light. The 3D sensor 110 changes the output intensity of the laser light in accordance with the control signal received from the server 140.

[0036] To give a specific example, when the detected object is a person, as shown in FIG. 5 , the laser light output from the 3D sensor 110 is changed to output intensity 114, which is lower than normal output intensity 112. This allows the detected person to be irradiated with laser light that meets eye-safe standards and acquire measurement data. On the other hand, when the detected object is something other than a person, the laser light may be changed to output intensity higher than normal. At this time, the output intensity of the laser light may be changed according to the characteristics of the detected object. Examples of the characteristics of the detected object include the distance to the detected object, the size of the detected object, and the type of detected object. That is, the laser light may be controlled to output a higher output intensity the farther the distance to the detected object. Alternatively, the laser light may be controlled to output a higher output intensity the smaller the detected object. Alternatively, the output intensity of the laser light may be controlled according to an output intensity preset for each type of detected object. Furthermore, if it is determined that further analysis of the detected object is necessary, the output intensity of the laser light may be increased. By performing these controls, the accuracy of the measurement data regarding the detected object can be improved, enabling more accurate analysis of the detected object.

[0037] Here, how the laser irradiation range control function and the laser output intensity control function are applied may be set in advance before the system is put into operation, or may be selected and changed arbitrarily by the user during system operation.

[0038] Furthermore, the laser irradiation range control function and the laser output intensity control function may be used separately or in combination. That is, in response to detection of an object in the monitoring area, control may be performed to limit the irradiation range of the laser light to the periphery of the detected object, and then control may be performed to change the output intensity of the laser light. For example, when a person is detected, control may be performed to limit the irradiation range of the laser light to the periphery of the person, and control may be performed to reduce the output intensity of the laser light. This makes it possible to perform high frame rate measurements while complying with eye-safe standards. As another example, when an object other than a person is detected, control may be performed to limit the irradiation range of the laser light to the periphery of the detected object, and control may be performed to increase the output intensity of the laser light. This makes it possible to further improve the accuracy of measurement data related to the detected object.

[0039] As described above, the monitoring system of this example includes a 3D sensor 110 installed facing a monitoring area, and a server 140 that detects objects within the monitoring area based on measurement data obtained by the 3D sensor 110. The server 140 is configured to control the 3D sensor 110 to change the irradiation range of the laser light and / or the output intensity of the laser light in response to the detection of an object within the monitoring area. This makes it possible to improve the accuracy of the measurement data obtained by the 3D sensor.

[0040] Next, modified examples of the monitoring system of this embodiment will be presented. Note that the following modified examples are merely examples, and it goes without saying that various other modifications are possible.

[0041] [First Modification] In the first modification, the 3D sensor 110 has a first operating mode in which it acquires measurement data at a first frame rate and a second operating mode in which it acquires measurement data at a second frame rate higher than the first frame rate, and is normally set to operate in the first operating mode. The server 140 controls the 3D sensor 110 to switch from the first operating mode to the second operating mode in response to detection of an object in the monitoring area based on the measurement data acquired by the 3D sensor 110. This configuration also makes it possible to increase the frame rate of the measurement data acquired by the 3D sensor, thereby improving the accuracy of the measurement data acquired by the 3D sensor.

[0042] [Second Modification] In the second modification, when an object is detected in the monitoring area based on the measurement data obtained by the 3D sensor 110, the server 140 controls the 3D sensor 110 to change the output intensity of the laser light only around the detected object. Referring to FIG. 4 , under normal circumstances, the entire laser irradiation range 201 of the 3D sensor 110 is scanned with laser light of a predetermined output intensity, and when an object is detected, the entire laser irradiation range 201 of the 3D sensor 110 is scanned, and at that time, the output intensity of the laser light is controlled to change only in a local range 202. This configuration makes it possible to achieve high frame rate measurements while complying with eye-safe standards, further improve the accuracy of measurement data related to detected objects, and reduce the number of missed objects when another object newly enters the monitoring area.

[0043] Although the embodiments of the present invention have been described above, these embodiments are merely illustrative and do not limit the technical scope of the present invention. The present invention can take on various other embodiments, and various modifications such as omissions and substitutions can be made without departing from the spirit of the present invention. These embodiments and modifications thereof are included in the scope and spirit of the invention described in this specification, etc., and are included in the invention described in the claims and their equivalents.

[0044] Furthermore, the present invention can be provided not only as devices such as those described above or as systems composed of these devices, but also as methods executed by these devices, programs for realizing the functions of these devices using a processor, and storage media for storing such programs in a computer-readable manner. [Industrial Applicability]

[0045] The present invention can be used in a surveillance system that uses a 3D sensor to detect objects within a surveillance area. [Explanation of symbols]

[0046] 10, 110: 3D sensor, 120: visible camera, 130: network switch, 140: server, 141: measurement data acquisition unit, 142: object detection unit, 143: sensor control unit, 150: monitoring terminal

Claims

1. A 3D sensor is installed facing the monitoring area, a server that detects an object within the monitoring area based on the measurement data obtained by the 3D sensor; A surveillance system characterized in that the server controls to increase the frame rate of the measurement data of the 3D sensor in response to the detection of an object in the surveillance area.

2. 2. The monitoring system according to claim 1, A surveillance system characterized in that the server increases the frame rate of the measurement data of the 3D sensor by controlling the laser light irradiation range of the 3D sensor to be limited to the periphery of the object when an object is detected in the surveillance area.

3. 3. The monitoring system according to claim 2, A monitoring system characterized in that, in response to an object being detected in the monitoring area, the server controls the 3D sensor to limit the irradiation range of the laser light to the periphery of the object, and also controls the 3D sensor to change the output intensity of the laser light.

4. 2. The monitoring system according to claim 1, the 3D sensor has a first operation mode in which measurement data is acquired at a first frame rate and a second operation mode in which measurement data is acquired at a second frame rate higher than the first frame rate, and is configured to normally operate in the first operation mode; A surveillance system characterized in that the server increases the frame rate of the measurement data of the 3D sensor by controlling the 3D sensor to switch from the first operating mode to the second operating mode in response to the detection of an object from the surveillance area.

5. A 3D sensor is installed facing the monitoring area, a server that detects an object within the monitoring area based on the measurement data obtained by the 3D sensor; A surveillance system characterized in that the server controls the change of the output intensity of the laser light of the 3D sensor in response to the detection of an object in the surveillance area.

6. 6. The monitoring system according to claim 5, A surveillance system characterized in that the server controls the output intensity of the laser light of the 3D sensor to change to an intensity that corresponds to the characteristics of the object when an object is detected in the surveillance area.

7. 6. The monitoring system according to claim 5, A surveillance system characterized in that the server controls the 3D sensor to reduce the output intensity of the laser light when an object detected in the surveillance area is a person.

8. 6. The monitoring system according to claim 5, A surveillance system characterized in that the server controls the 3D sensor to increase the output intensity of the laser light when further analysis is required of an object detected in the surveillance area.

9. 9. The monitoring system according to claim 5, A surveillance system characterized in that the server controls the output intensity of the laser light of the 3D sensor in response to the detection of an object in the surveillance area, as well as controls the irradiation range of the laser light of the 3D sensor to be limited to the periphery of the object.

10. 9. The monitoring system according to claim 5, A surveillance system characterized in that the server controls the output intensity of the laser light of the 3D sensor to change only around the object when an object is detected in the surveillance area.

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