JP7793398B2 - Object detection device and object detection system - Google Patents

Description

The present invention relates to an object detection device and an object detection system.

Conventionally, object detection devices have been disclosed that detect the intrusion of a person or other object into a detection area based on a distance image obtained from the reflected light of laser light irradiated onto the detection area.

Japanese Patent Application Laid-Open No. 2006-46961

However, when an object detection device such as the one described above is installed on an indoor ceiling or similar surface and used as a security sensor, if there is a mirror, window, or other reflective surface in the detection area, the laser light will be reflected by the mirror, resulting in the object being detected twice.

The present invention has been made in consideration of the above, and aims to provide an object detection device and object detection system that can detect mirrored surfaces in a detection area, but does not detect objects reflected by the mirrored surface.

To solve the above-mentioned problems and achieve the objectives, the present invention provides an object detection device that includes a sensor unit that obtains the distance to an object in a detection area and detects objects based on that distance. When two objects are detected, and the appearance characteristics of the two objects match and the movement directions of the two objects are symmetrical with respect to a certain plane, the device determines that one of the detected objects is an image reflected on the plane, and sets an area where the object detection device cannot detect the object due to the plane as a non-detection area that ignores images reflected on the plane.

This invention has the advantage of being able to detect mirrored surfaces in the detection area while preventing the detection of objects reflected by the mirrored surfaces.

FIG. 1 is a diagram illustrating an example of a schematic configuration of a security system using an object detection device according to the present invention. FIG. 2 is a perspective view illustrating an example of an object detection device. FIG. 3 is a diagram showing an example of installation of an object detection device. FIG. 4 is a block diagram showing an example of the configuration of an object detection device. FIG. 5 is a diagram showing a case where a mirror surface is present in the detection area. FIG. 6 is a diagram illustrating an example of object detection. FIG. 7 is a diagram illustrating an example of object detection. FIG. 8A is a flowchart illustrating the operation of the object detection device. FIG. 8B is a flowchart showing the flow of the mirror surface position determination process (setting mode). FIG. 8C is a flowchart showing the flow of the mirror surface position determination process (operation mode).

Embodiments of an object detection device and an object detection system according to the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.

Figure 1 is a diagram illustrating an exemplary schematic configuration of a security system 1 using an object detection device 10 according to the present invention. As shown in Figure 1, the security system 1 includes the object detection device 10 installed at a security target 20, a security device 40, and a monitoring center 30 located remotely from the security target 20.

The object detection device 10 and security device 40 that make up the object detection system are connected via a network 50, such as a local area network (LAN), and are capable of communicating with each other. The communication method between the object detection device 10 and security device 40 may be wireless or wired.

The security device 40 is also connected to a fire sensor and a human body detection sensor (not shown) via a network, and is capable of receiving fire signals from the fire sensor and detection signals from the human body detection sensor. Furthermore, the security device 40 is capable of communicating with a monitoring center 30 located remotely from the security target 20 via an external network 60, such as the Internet. Here, the security target 20 is assumed to be a building such as a store, office, tenant building, apartment building, or residence.

The security device 40 has at least two operating modes: "security mode" and "security release mode," and notifies the object detection device 10 of the operating mode set in response to an operation by the administrator of the security target 20. The operating modes will be described later.

The object detection device 10 transmits information about the detection of an object at the security target 20 to the security device 40 via the network 50. Note that the object detection device 10 may choose not to transmit information about the detection of an object at the security target 20 depending on the operating mode of the security device 40.

When the security device 40 receives object detection information from the object detection device 10, it reports an abnormality in the security target 20, including the received object detection information, to the monitoring center 30 via the external network 60, depending on the operating mode. Furthermore, when the security device 40 receives a fire signal from a fire sensor or a detection signal from a human body detection sensor, it reports the received signal as an abnormality to the monitoring center 30, depending on the operating mode.

Next, we will briefly explain the operating modes of the security device 40.

"Security mode" is an operating mode for guarding an unattended police target 20. When a security device 40 set to "security mode" receives object detection information from the object detection device 10, a fire signal from the fire sensor, or a detection signal from the human body detection sensor, it reports the object detection information or the received signal as an abnormality to the monitoring center 30. The security device 40 may also record a history of the abnormality in addition to reporting it, or may alert the security target 20 to the abnormality with an alarm sound or light, etc.

"Security Disabled Mode" is an operating mode when there is a relevant person inside the security object 20 and security is not required. When the security device 40 is set to "security disabled mode," even if it receives object detection information from the object detection device 10 or a detection signal from the human body detection sensor, it does not determine that there is an abnormality in the security object 20 and does not take any action to report the abnormality to the monitoring center 30. This is because even if the object detection device 10 or the like detects the presence of an object, it determines that a relevant person has been detected.

When an abnormality is reported from the security device 40, the monitoring center 30 displays the content of the report on a monitor. For example, a supervisor monitors whether or not an abnormality has occurred at the security object 20 based on the displays on these monitors. If the supervisor recognizes that an abnormality has occurred within the security object 20, he or she will instruct a security guard on standby to head to the security object 20, and if necessary, will notify relevant authorities such as the police or fire department. The monitoring center 30 also records the content of the abnormality reported from the security device 40 in a recording device. The monitoring center 30 may also be configured to send a notification of the abnormality to the mobile terminal (e.g., mobile phone) of the user (contractor, etc.) of the security system 1.

Next, we will explain the configuration of the object detection device 10.

Figure 2 is a perspective view showing an example of an object detection device 10, and Figure 3 is a diagram showing an example of an installation of the object detection device 10. As shown in Figure 3, the object detection device 10 is installed on the ceiling of the security target 20. Note that Figure 2 shows the installation position of the object detection device 10 when installed on the ceiling 90.

As shown in Figure 2, the object detection device 10 is equipped with a light-transmitting protective cover 11, which houses a light-emitting unit 12a that radially irradiates laser light at regular intervals toward the security target 20, and a light-receiving unit 12b that detects reflected light, which is laser light reflected by objects within the detection area A1. The object detection device 10 is equipped with, for example, a 3D-LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) sensor, which is a three-dimensional ranging sensor capable of measuring distance. 3D-LiDAR measures scattered light in response to pulsed laser irradiation and analyzes the distance to a distant object.

A laser beam scanned from the light-emitting unit 12a reaches the periphery of the object detection device 10 at regular intervals, and when the laser beam is reflected by a moving object O located at the position where it reaches, the reflected light reaches the light-receiving unit 12b and is detected. As shown in Figure 3, this forms a detection area A1, which is an area in which the object detection device 10 can detect the moving object O.

Figure 4 is a block diagram showing an example of the configuration of the object detection device 10. As shown in Figure 4, the object detection device 10 includes a sensor unit 12, a control unit 13, a memory unit 14, a notification unit 15, and a setting switch 16, which is a setting unit.

The sensor unit 12 is, for example, a 3D-LiDAR. The sensor unit 12 includes a light-emitting unit 12a that emits laser light radially at regular intervals, and a light-receiving unit 12b that detects reflected light, which is laser light reflected by objects within the detection area A1.

The control unit 13 is configured as a computer equipped with, for example, a CPU (Central Processing Unit), ROM (Read Only Memory) for storing programs, and RAM (Random Access Memory) used as a work area. The control unit 13 performs control operations and calculations for the detection process of a moving object O by the object detection device 10 according to the operating mode of the security device 40, etc., by the CPU executing programs stored in the ROM.

By the way, an object detection device 10 equipped with 3D-LiDAR that can measure the distance to a moving object O within a predetermined detection area A1 recognizes a collection of data (such as a point cloud) that has similar distances and reflectivities and moves as a single unit as a single moving object O.

Here, Figure 5 is a diagram showing a case where there is a mirrored surface 100 in the detection area A1. Figure 5(a) shows the real world, and Figure 5(b) shows the world detected by the object detection device 10. The example shown in Figure 5 is an example where the object detection device 10 is installed looking down from the ceiling of the security target 20, and there is a mirrored surface 100 such as a window or mirror on the wall. When a mirrored surface 100 is present in this way, as shown in Figure 5(b), two things are detected: the direct reflection of the actual moving object O (real object), and the moving object O' (mirror image) resulting from the reflection of the laser reflected by the mirrored surface 100 (reflected behind the moving object O). This detection occurs because the laser is reflected by the mirrored surface 100, and it cannot be considered a wall.

Here, Figures 6 and 7 are diagrams showing examples of object detection. Figure 6(a) shows an example in which the window in detection area A1 is a mirrored surface 100, and Figure 6(b) shows detection area A1 and non-detection area A2 viewed from above. Figure 7(a) shows an example in which mirrored surface 100 appears in detection area A1, Figure 7(b) shows detection area A1 and non-detection area A2 viewed from above, Figure 7(c) shows another view of detection area A1 and non-detection area A2 viewed from above, and Figure 7(d) shows a case in which a moving object O is present only in non-detection area A2. Note that the installation manner of mirrored surface 100 differs between the example shown in Figure 7(b) and the example shown in Figure 7(c).

As shown in FIG. 6(b), when the control unit 13 of the object detection device 10 detects two moving objects O, O' that have the same movement speed, height, width, and other appearance characteristics, it infers that one of the detected objects is an object reflected on the mirror surface 100 and calculates to confirm whether the mirror surface 100 is located between the moving objects O, O'. Specifically, the control unit 13 of the object detection device 10 determines whether the trajectory of the midpoints of the two moving objects O, O' is a straight line. If the trajectory of the midpoints of the two moving objects O, O' is a straight line, the control unit 13 of the object detection device 10 determines that the straight line is the position of the mirror surface 100. In other words, the control unit 13 of the object detection device 10 determines only the moving object O on the near side (the object detection device 10 side) of the mirror surface 100 to be the main body, and determines that the moving object O' on the far side of the mirror surface 100 is a mirror image reflected on the mirror surface 100. In this embodiment, to simplify the calculations, the mirror surface 100 is assumed to be installed perpendicular to the floor, and when projected onto the floor it forms a straight line.

As shown in Figure 6(b), the control unit 13 of the object detection device 10 sets the area beyond the midpoint between the two moving objects O and O', indicated by the thick line L in Figure 6(b) (the area beyond the reach of the laser emitted by the object detection device 10), as a non-detection area A2 for ignoring the moving object O' reflected by the mirror surface 100, and does not adopt the detection information for the non-detection area A2 (see Figure 6(b)) received from the sensor unit 12.

When the window within the detection area A1 is a mirrored surface 100 as shown in Figure 6(a), the area where the laser emitted by the object detection device 10 does not reach due to the mirrored surface 100 as shown in Figure 6(b) is set as a non-detection area A2 in order to ignore the moving object O' reflected by the mirrored surface 100.

When a mirror surface 100 appears within the detection area A1 as shown in Figure 7(a), the area where the laser emitted by the object detection device 10 does not reach due to the mirror surface 100 as shown in Figures 7(b) and 7(c) is set as a non-detection area A2 in which the moving object O' reflected by the mirror surface 100 is ignored.

In addition, as shown in Figure 7(d), if a moving object O is present only in the non-detection area A2 and the paired main body cannot be detected, the control unit 13 of the object detection device 10 determines that the mirror surface 100 has been removed and cancels the setting of the non-detection area A2.

When the control unit 13 is set to the setting mode by the setting switch 16, if the mirror surface 100 is estimated as described above, it sets the moving object O' reflected on the mirror surface 100 as a non-detection area A2 for ignoring the reflected object O' and stores this in the memory unit 14. In the setting mode, the worker performing the installation work moves along the mirror surface 100, so another moving object O' moving parallel to the direction of movement of one moving object O is detected. The control unit 13 compares the moving direction, moving speed, height, width, etc. of the two moving objects O and O', and if they match, it determines that only the moving object O on the front side of the mirror surface 100 (the object detection device 10 side) is the main body, and determines that the moving object O' on the back side of the mirror surface 100 is a mirror image reflected on the mirror surface 100.

When the control unit 13 is set to operation mode by the setting switch 16, it determines whether or not a moving object O, such as an intruder, is present in the detection area A1 based on the distance to the object obtained from the sensor unit 12 and the non-detection area A2 stored in the memory unit 14. If it determines that an object is present, it outputs detection information to the security device 40. Furthermore, if it detects the presence of a mirror surface 100, it sets the moving object O' reflected on the mirror surface 100 as a non-detection area A2 to be ignored and stores this in the memory unit 14. If it detects that the mirror surface 100 has been removed, it cancels the setting of the non-detection area A2.

The memory unit 14 is a rewritable memory unit, such as a Flash ROM. The memory unit 14 stores various information (such as the non-detection area A2) used in the detection process for the moving object O.

The notification unit 15 includes a speaker 15a that emits a notification sound based on the output of the control unit 13, and a display unit 15b such as an LED that emits light based on the output of the control unit 13.

The setting switch 16 is operated by the operator to set the control unit 13 from operation mode to setting mode. The operation mode and setting mode are as described above.

The operation of the object detection device 10 will be described below. Figures 8-1 to 8-3 are flowcharts explaining the operation of the object detection device 10.

When a mirrored surface 100, such as a mirror or window, is present in the detection area A1, the object detection device 10 detects two things: a direct reflection from the actual moving object O, and a moving object O' resulting from the reflection of the laser beam reflected by the mirrored surface 100 (reflected behind the moving object O). Therefore, the installation worker sets up a non-detection area A2 to ignore the moving object O' reflected by the mirrored surface 100.

If the detection area A1 contains a mirror, window, or other mirrored surface 100 and therefore requires the setting of a non-detection area A2, the worker performing the installation operates the setting switch 16 to place the object detection device 10 in setting mode, and walks along the mirrored surface 100 within the detection area A1.

The control unit 13 controls the sensor unit 12 to recognize and detect a collection of data (such as a point cloud) that has similar distances and reflectivities and moves as a single unit as a single object (step S1).

If the setting switch 16 is operated to the setting mode (Yes in step S2), the control unit 13 executes the mirror surface position determination process (setting mode) (step S3).

Figure 8-2 is a flowchart showing the flow of the mirror surface position determination process (setting mode). As shown in Figure 8-2, the control unit 13 detects two or more moving objects (Yes in step S31), and if it detects two moving objects O, O' among the moving objects that have the same movement speed, height, width, or other appearance characteristics (Yes in step S32), it determines whether the two moving objects O, O' are moving in parallel (step S33). Note that if the control unit 13 detects only one moving object (No in step S31) or does not detect two moving objects O, O' that have the same movement speed, height, width, or other appearance characteristics (No in step S32), it terminates the process.

If the two moving objects O, O' are moving in parallel (Yes in step S33), the control unit 13 determines that the midpoint between the two moving objects O, O' is the position of the mirror surface 100 (step S34). That is, the control unit 13 determines that only the moving object O on the near side of the mirror surface 100 (the object detection device 10 side) is the main body, and determines that the moving object O' on the far side of the mirror surface 100 is a mirror image reflected on the mirror surface 100.

On the other hand, if the two moving objects O and O' are not moving in parallel (No in step S33), the control unit 13 terminates the processing.

The control unit 13 sets the area beyond the midpoint between the two moving objects O and O' (the area beyond the reach of the laser emitted by the object detection device 10) in the memory unit 14 as a non-detection area A2 for ignoring the moving object O' reflected by the mirror surface 100 (step S35), and ends the processing by not adopting the detection information for the non-detection area A2 (see Figure 6(b)) received from the sensor unit 12.

On the other hand, if the setting switch 16 is operated to the operation mode (No in step S2), the control unit 13 determines whether the object is present in the detection area A1 or the non-detection area A2 based on the non-detection area A2 stored in the memory unit 14 (steps S4 and S5).

When the control unit 13 determines that an object exists only in the detection area A1 based on the non-detection area A2 stored in the memory unit 14 (Yes in step S4), the control unit 13 executes the mirror position determination process (operation mode) (step S6).

Figure 8-3 is a flowchart showing the flow of the mirror surface position determination process (operation mode). As shown in Figure 8-3, the control unit 13 detects two or more moving objects (Yes in step S61), and if it detects two moving objects O, O' that have the same movement speed, height, width, or other appearance characteristics among the moving objects (Yes in step S62), it determines whether the trajectory of the midpoints of the two moving objects O, O' is a straight line (step S63). Note that if the control unit 13 detects only one moving object (No in step S61) or does not detect two moving objects O, O' that have the same movement speed, height, width, or other appearance characteristics (No in step S62), it terminates the process.

If the control unit 13 determines that the trajectory of the midpoints of the two moving objects O, O' is a straight line (Yes in step S63), it determines that the trajectory of the midpoints of the two moving objects O, O' is the position of the mirror surface 100 (step S64). That is, the control unit 13 determines only the moving object O on the near side (the object detection device 10 side) of the mirror surface 100 to be the main body, and determines that the moving object O' on the far side of the mirror surface 100 is a mirror image reflected on the mirror surface 100. In this way, the position of the mirror surface can be determined even if the two moving objects O, O' do not move parallel to the mirror surface 100, as shown in FIG. 7(b).

On the other hand, if the trajectory of the midpoints of the two moving objects O and O' is not a straight line (No in step S63), the control unit 13 terminates the processing.

The control unit 13 sets the area beyond the midpoint between the two moving objects O and O' (the area beyond the reach of the laser emitted by the object detection device 10) in the memory unit 14 as a non-detection area A2 for ignoring the moving object O' reflected by the mirror surface 100 (step S65), ignores the object in the non-detection area A2 (see Figure 6(b)) received from the sensor unit 12 (step S66), and ends the processing.

The control unit 13 then outputs the detection information to the security device 40 (step S7) and ends the process.

On the other hand, if the control unit 13 determines that an object is present in the detection area A1 and the non-detection area A2 based on the non-detection area A2 stored in the memory unit 14 (No in step S4, Yes in step S5), it determines whether the object detected in the non-detection area A2 is a mirror image of the object in the detection area A1 (step S8).

If the control unit 13 determines that the object detected in the non-detection area A2 is a mirror image of the object in the detection area A1 (Yes in step S8), it ignores the object present in the non-detection area A2 (step S9), outputs the detection information to the security device 40 (step S7), and ends the process.

In addition, if the control unit 13 determines, based on the non-detection area A2 stored in the memory unit 14, that an object paired with the object in the non-detection area A2 cannot be detected in the detection area A1 (see Figure 7(d)), i.e., that the object is present only in the non-detection area A2 (No in step S4, No in step S5), or that the object detected in the non-detection area A2 is not a mirror image of the object in the detection area A1 (No in step S8), it determines that the mirror surface 100 has been removed and cancels the setting of the non-detection area A2 (step S10). The control unit 13 then executes the same mirror surface position determination process (operation mode) as in step S6 (step S11), outputs the detection information to the security device 40 (step S7), and ends the process.

If the mirror surface 100 is removed and then reinstalled, the non-detection area A2 can be set in the setting mode, or the mirror surface 100 can be detected in the operation mode and the non-detection area A2 can be set.

As described above, according to the object detection device of this embodiment, if the appearance characteristics of two objects, such as their movement speed, height, and width, match, and the movement directions of the two objects are symmetrical with respect to a certain plane (mirror surface 100), the detected object is determined to be an image reflected on the plane (mirror surface 100), and an area where the object detection device 10 cannot detect due to the plane (mirror surface 100) is set as a non-detection area A2 for ignoring images reflected on the plane. This allows the mirror surface 100 in the detection area A1 to be detected, while preventing the detection of objects reflected on the mirror surface 100. Furthermore, the operator can easily set the non-detection area A2, automating the effort of excluding the mirror surface 100 from the detection range. Furthermore, because objects reflected on the mirror surface 100 are not detected, there is no need to consider whether they are reflected images when checking for abnormalities. Furthermore, because objects reflected on the mirror surface 100 are not detected, the location of an intruder's movements can be accurately determined.

In this embodiment, the sensor unit 12 is, for example, a 3D LiDAR, but this is not limited to this. The sensor unit 12 may also be configured as a stereo camera, which is a type of three-dimensional ranging sensor that is composed of two cameras and can measure distance. Even if the sensor unit 12 is configured as a stereo camera, if it is installed looking down from the ceiling and there is a mirror surface 100 on the wall, two images will be detected: a parallax image of the actual object and a parallax image of the object reflected on the mirror surface 100 (the image reflected in the mirror). This is because the image of the object to be detected is reflected by the reflective object, and it cannot be considered a wall. The present invention is effective even when the sensor unit 12 is configured as a stereo camera in this way.

In this embodiment, the object detection device 10 stores the non-detection areas A2, etc., and performs processes such as determining whether an object has been detected. However, this is not limited to this. The security device 40, which constitutes an object detection system together with the object detection device, may store the non-detection areas A2, etc., and function as an object detection unit that performs processes such as determining whether an object has been detected.

10 Object detection device 12 Sensor unit 13 Control unit 16 Setting unit 40 Security device 100 Mirror surface

Claims (7)

An object detection device comprising a sensor unit that obtains a distance to an object in a detection area and detects an object based on the distance,
and a control unit that, when two objects are detected and the appearance features of the two objects match and the moving directions of the two objects are symmetrical with respect to a certain plane, determines that one of the detected objects is an image reflected on the plane, and sets an area in which the object detection device cannot detect due to the plane as a non-detection area in which the image reflected on the plane is ignored.
An object detection device characterized by: When the locus of the midpoints of the two objects is a straight line, the control unit determines the straight line as the position of the plane.
2. The object detection device according to claim 1. the control unit determines that the plane has been removed and cancels the setting of the non-detection area when an object paired with the object in the non-detection area cannot be detected in the detection area.
3. The object detection device according to claim 1 or 2. the control unit determines that the detected object is an image reflected on a plane when the moving direction, moving speed, height, and width of the two objects are the same, and designates an area in which the object detection device cannot detect the object due to the plane located at the midpoint between the distances of the two moving objects as a non-detection area in which the image reflected on the plane is ignored.
4. The object detection device according to claim 1, wherein the object detection device is a sensor. The sensor unit is a 3D-LiDAR.
5. The object detection device according to claim 1, wherein the object detection device is a sensor. The sensor unit is a stereo camera that is composed of two cameras and is capable of measuring distance.
5. The object detection device according to claim 1, wherein the object detection device is a sensor. An object detection system including: a sensor unit that obtains a distance to an object in a detection area; and an object detection unit that receives the distance from the sensor unit and detects an object based on the distance,
and a control unit that, when two objects are detected and the appearance features of the two objects match and the moving directions of the two objects are symmetrical with respect to a certain plane, determines that one of the detected objects is an image reflected on the plane, and sets an area in which the object detection device cannot detect due to the plane as a non-detection area in which the image reflected on the plane is ignored.
1. An object detection system comprising: