Object detection device

Abstract

To provide an object detection device capable of preventing non-detection of an object low in laser beam reflectance (low-reflectance object) such as a dark or black automobile.SOLUTION: An object detection device 1 comprises a first ranging sensor 3 and a second ranging sensor 5 that scan a monitoring region 10 with a laser beam and receive reflected light, and is configured to detect the entry of a low-reflectance object into the monitoring region 10 from the reception state of the reflected light in a first entrance / exit region 15 or a second entrance / exit region 17 set in the monitoring region 10, and detect the exit of the low-reflectance object from the monitoring region 10 from the reception state of the reflected light in the second entrance / exit region 17 or the first entrance / exit region 15.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an object detection device that detects the presence or absence of an object within a monitoring area. [Background technology]

[0002] A known example of an object detection device is the obstacle detection device described in Patent Document 1. The obstacle detection device described in Patent Document 1 is configured to detect whether or not there is an obstacle (i.e., an object) within a set area of ​​a railroad crossing by receiving reflected light of a laser beam that scans within a predetermined angle range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-227608 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the obstacle detection device described in Patent Document 1, even if an object with low reflectance of laser light, such as a dark or black automobile, is present in the installation area, it may happen that almost no reflected light from the object is received depending on the object's position, etc. As a result, there is a risk that the obstacle detection device described in Patent Document 1 will miss detecting objects with low reflectance of laser light, such as a dark or black automobile.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an object detection device capable of preventing failure to detect objects with low reflectance to laser light, such as dark or black colored automobiles. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an object detection device, which includes a distance measuring sensor that scans a monitoring area with a laser beam and receives reflected light, and is configured to detect an entry of an object into the monitoring area based on a state in which the reflected light is received at an entrance area set in the monitoring area, and to detect an exit of the object from the monitoring area based on a state in which the reflected light is received at an exit area set in the monitoring area. Effect of the Invention

[0007] According to the present invention, it is possible to provide an object detection device that can prevent failure to detect dark or black objects that have a low reflectance of laser light. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view showing a schematic configuration of an object detection device according to an embodiment. [Diagram 2] 4 is a flowchart showing an object detection process performed by a processing device of the object detection device. [Diagram 3] 4 is a flowchart showing an object detection process performed by a processing device of the object detection device. [Figure 4A] 11A and 11B are diagrams for explaining a process of determining whether or not a low-reflectivity object has entered a monitoring area. [Figure 4B] 11A and 11B are diagrams for explaining a process of determining whether or not a low-reflectivity object has entered a monitoring area. [Figure 5A] 11A and 11B are diagrams for explaining a process of determining whether or not a low-reflectivity object has exited a monitoring area. [Figure 5B] 11A and 11B are diagrams for explaining a process of determining whether or not a low-reflectivity object has exited a monitoring area. [Figure 6] FIG. 13 is a plan view showing a modified example of the object detection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the terms "first", "second", ..., etc. are used simply to distinguish similar elements and are not intended to limit the elements to which they are attached.

[0010] 1 is a plan view showing a schematic configuration of an object detection device 1 according to an embodiment of the present invention. The object detection device 1 according to the embodiment is configured to detect the presence or absence of an object in a monitoring area 10, which is a road within a railroad crossing. More specifically, the object detection device 1 is configured to detect an object in the monitoring area 10 as an obstacle. The object detection device 1 includes a first distance measurement sensor 3, a second distance measurement sensor 5, and a processing device 7. The monitoring area 10 also has two entrances 11 and 13 for entering and exiting the monitoring area 10.

[0011] The first distance measurement sensor 3 is disposed on the side (here, on the right side) of one entrance / exit (the lower entrance / exit in FIG. 1, hereinafter referred to as the "first entrance / exit") 11 of the monitored area 10. In other words, the first distance measurement sensor 3 is disposed on one side of one end of the road within the railroad crossing. The first distance measurement sensor 3 is a TOF type laser scan sensor such as a LiDAR sensor.

[0012] The second distance measurement sensor 5 is disposed on the side (here, on the left side) of the other entrance / exit (the upper entrance / exit in FIG. 1, hereinafter referred to as the "second entrance / exit") 13 of the monitored area 10. In other words, the second distance measurement sensor 5 is disposed on the other side of the other end of the road within the railroad crossing. Like the first distance measurement sensor 3, the second distance measurement sensor 5 is a TOF type laser scan sensor such as a LiDAR sensor.

[0013] The first distance measuring sensor 3 and the second distance measuring sensor 5 are configured to scan the monitoring area 10 with a laser beam and receive reflected light of the scanning laser beam. Specifically, in this embodiment, the first distance measuring sensor 3 is configured to scan the laser beam in a range including at least one entrance area set in the monitoring area 10, i.e., an entrance area (hereinafter referred to as a "first entrance area") 15 set at least on the first entrance 11 side in the monitoring area 10, and receive reflected light of the scanning laser beam. The second distance measuring sensor 5 is configured to scan the laser beam in a range including at least the other entrance area set in the monitoring area 10, i.e., an entrance area (hereinafter referred to as a "second entrance area") 17 set at least on the second entrance 13 side in the monitoring area 10, and receive reflected light of the scanning laser. The entire monitoring area 10 is covered by the scanning range of the laser beam of the first distance measuring sensor 3 and the scanning range of the laser beam of the second distance measuring sensor 5. Preferably, the scanning range of the laser light of the first distance measuring sensor 3 and the scanning range of the laser light of the second distance measuring sensor 5 have an overlapping portion.

[0014] In this embodiment, the first distance measuring sensor 3 and the second distance measuring sensor 5 are each installed at a predetermined height using a support or the like not shown in the figure, and are configured to be able to (1) emit laser light by changing the emission direction (emission angle) along a plane parallel to the road surface of the monitored area 10, (2) receive light reflected by an object of the emitted laser light, (3) measure the received light intensity (received light level) of the reflected light, and (4) calculate the distance to the reflection position of the laser light (i.e., the object (reflecting object) that reflected the laser light) based on the time difference between the emission timing of the laser light and the reception timing of the reflected light.

[0015] The processing device 7 stores information (position information and range information) related to the monitoring area 10, position information of the first distance measuring sensor 3, and position information of the second distance measuring sensor 5. The processing device 7 is connected to the first distance measuring sensor 3 and the second distance measuring sensor 5 wirelessly or by wire. The processing device 7 is configured to input information such as the emission direction of the laser light, the received intensity of the reflected light, and the distance to the reflection position of the laser light from the first distance measuring sensor 3 and the second distance measuring sensor 5, and to determine whether or not an object (i.e., an obstacle) is present in the monitoring area 10 based on the input information (object detection process). Although not described here, the processing device 7 may be configured to output an obstacle detection signal (object detection signal) to an alarm device (not shown) or the like in order to notify the outside that an obstacle (object) is present in the monitoring area 10 when it is determined that an obstacle (object) is present in the monitoring area 10.

[0016] Next, an object detection process executed by the processing device 7 of the object detection device 1 according to the embodiment will be described. 2 and 3 are flowcharts showing an example of the object detection process.

[0017] In step S1, the processing device 7 inputs and stores the "laser light emission direction," "intensity of the received reflected light," and "distance to the reflection position of the laser light" from the first distance measurement sensor 3 and the second distance measurement sensor 5.

[0018] In step S2, the processing device 7 judges whether or not "low reflectivity judgment" is enabled. If "low reflectivity judgment" is not enabled, the processing device 7 proceeds to step S3, and if "low reflectivity judgment" is enabled, the processing device 7 proceeds to step S13 (FIG. 3). Note that, as described below, "low reflectivity judgment" is enabled in step S8 when it is judged in step S7 that a low reflectivity object has entered the monitoring area 10.

[0019] In step S3, the processing device 7 judges whether or not the reflected position of the laser light is within the monitoring area 10. Specifically, the processing device 7 identifies the reflected position of the laser light based on the emission direction of the laser light and the distance to the reflected position of the laser light input in step S1, and judges whether or not the identified reflected position of the laser light is within the monitoring area 10. Then, if the reflected position of the laser light is within the monitoring area 10, the processing device 7 proceeds to step S5. In other cases, the processing device 7 judges in step S4 that "there is no obstacle" and then returns.

[0020] In step S5, the processing device 7 judges whether the reflection position of the laser light is the same as the reflection position of the previous laser light. If the reflection position of the laser light is the same as the reflection position of the previous laser light, the processing device 7 proceeds to step S6. On the other hand, if the reflection position of the laser light is different from the reflection position of the previous laser light, the processing device 7 stores the reflection position of the (current) laser light and returns.

[0021] In step S6, the processing device 7 judges whether the reflection position of the laser beam is the same N times (N≧3) in succession. If the reflection position of the laser beam is the same N times in succession, the processing device 7 proceeds to step S7, otherwise, the processing device 7 counts up the number of times the laser beam is reflected at the same position and returns.

[0022] In step S7, the processing device 7 judges whether or not a low-reflectivity object has entered the monitoring area 10. The low-reflectivity object refers to an object (particularly a moving object) with low reflectivity of laser light, and mainly refers to a dark or black automobile here. Specifically, the processing device 7 judges whether or not a low-reflectivity object has entered the monitoring area 10 from a first entrance 11, which is one of the entrances to the monitoring area 10, and whether or not a low-reflectivity object has entered the monitoring area 10 from a second entrance 13, which is the other of the entrances to the monitoring area 10. Then, when a low-reflectivity object has entered the monitoring area 10 (from the first entrance 11 or the second entrance 13), the processing device 7 activates "low reflection judgment" in step S8, judges "obstacle presence" in step S9, and then returns. On the other hand, when a low-reflectivity object has not entered the monitoring area 10, the processing device 7 proceeds to step S10. The processing of step S7 will be described later.

[0023] In step S10, the processing device 7 assigns the object that reflected the laser light (i.e., the reflecting object) to one of a plurality of meshes set in the monitoring area 10 based on the reflected position of the laser light. Specifically, in this embodiment, the monitoring area 10 is divided into N×M meshes, and the processing device 7 identifies the mesh that corresponds to the reflected position of the laser light as the mesh in which the reflecting object is located.

[0024] In step S11, the processing device 7 judges whether or not the reflecting object has been staying in the same mesh for a predetermined time or more. If the reflecting object has not been staying in the same mesh for a predetermined time or more, the processing device 7 returns. On the other hand, if the reflecting object has been staying in the same mesh for a predetermined time or more, the processing device 7 judges in step S12 that "an obstacle is present" and then returns.

[0025] In step S13 (FIG. 3), the processing device 7 judges whether or not the low reflectance object has exited the monitoring area 10. Specifically, if it is judged in step S7 that the low reflectance object has entered the monitoring area 10 from the first entrance 11, the processing device 7 judges whether or not the low reflectance object has exited from the second entrance 13, and if it is judged in step S7 that the low reflectance object has entered from the second entrance 13, the processing device 7 judges whether or not the low reflectance object has exited from the first entrance 11. If the low reflectance object has not exited from the first entrance 11 or the second entrance 13, that is, if the low reflectance object has not exited from the monitoring area 10, the processing device 7 returns. On the other hand, if the low reflectance object has exited from the monitoring area 10, the processing device 7 returns after invalidating the "low reflection judgment" in step S14. The processing of step S13 will be described later.

[0026] Here, the process of step S7 described above, that is, the process of determining whether or not a low reflectance object has entered the monitored area 10, will be described.

[0027] The first distance measuring sensor 3 and the second distance measuring sensor 5 can receive a certain amount of reflected light of the laser light emitted toward a low-reflectivity object such as a dark or black automobile. However, depending on the position of the low-reflectivity object, and more specifically, the incident angle of the laser light on the low-reflectivity object, the received light intensity of the reflected light measured by the first distance measuring sensor 3 and the second distance measuring sensor 5 may be significantly reduced. Note that a significantly reduced received light intensity of the reflected light includes a state in which the received light intensity becomes almost zero or a state in which the received light intensity becomes a level that is not significantly different from noise. In such a case, the processing device 7 may determine that there is no low-reflectivity object (i.e., an obstacle) in the monitoring area 10 even though there is a low-reflectivity object in the monitoring area 10, that is, there is a risk of failing to detect the low-reflectivity object.

[0028] On the other hand, by utilizing the light receiving state (light receiving direction, light receiving intensity, etc.) of the reflected light in the specific area, specifically, the light receiving intensity of each of the reflected lights of the multiple laser lights emitted to the specific area, it becomes possible to prevent the above-mentioned low reflectivity object from being overlooked even when the light receiving intensity of the reflected light is low. This will be specifically described below.

[0029] For example, as shown in FIG. 4A, when a low-reflectivity object (e.g., a black automobile) LO enters the monitoring area 10 from the first entrance 11 and passes through the first entrance area 15, the first distance measuring sensor 3 receives the reflected light by the low-reflectivity object LO for each of the laser beams emitted in a plurality of directions in the first entrance area 15. In this case, from the measurement result of the first distance measuring sensor 3, first data is obtained that indicates the "relationship between the emission direction (emission angle) of the laser beam and the received light intensity of the reflected light" when the low-reflectivity object LO enters the monitoring area 10 from the first entrance 11 and passes through the first entrance area 15, as shown in FIG. 4B, for example. If such first data is collected and machine learning is performed, for example, a pattern when the low-reflectivity object LO enters the monitoring area 10 from the first entrance 11 and passes through the first entrance area 15 can be obtained. The obtained pattern is a characteristic pattern of the reflected light receiving state at the first entrance / exit area 15 when the low-reflectivity object LO enters the monitored area 10, and enables detection of the low-reflectivity object LO that has entered the monitored area 10 from the first entrance / exit 11. Note that the dashed line in Fig. 4B shows, for reference, an example of data when a high-reflectivity object enters the monitored area 10 from the first entrance / exit 11 and passes through the first entrance / exit area 15.

[0030] Similarly, when the low-reflectivity object LO enters the monitoring area 10 from the second entrance 13 and passes through the second entrance area 17, the second distance measuring sensor 5 receives the reflected light from the low-reflectivity object LO for each of the laser lights emitted in multiple directions in the second entrance area 17, that is, multiple reflected lights in the second entrance area 17. In this case, the measurement result of the second distance measuring sensor 5 provides second data indicating the relationship between the emission direction (emission angle) of the laser light and the received light intensity of the reflected light when the low-reflectivity object LO enters the monitoring area 10 from the second entrance 13 and passes through the second entrance area 17. If such second data is collected and machine learning is performed, for example, a pattern when the low-reflectivity object LO enters the monitoring area 10 from the second entrance 13 and passes through the second entrance area 17 can be obtained. The obtained pattern is a characteristic pattern of the reflected light receiving state at the second entrance / exit area 17 when a low-reflectivity object LO enters the monitored area 10, and enables detection of a low-reflectivity object LO that has entered the monitored area 10 from the second entrance / exit 13.

[0031] Therefore, in this embodiment, the processing device 7 has at least one "first entry light receiving intensity pattern" which is a result of machine learning of first data obtained about various low reflectance objects that may pass through the monitoring area 10, and at least one "second entry light receiving intensity pattern" which is a result of machine learning of second data obtained about various low reflectance objects that may pass through the monitoring area 10. Note that at least one "first entry light receiving intensity pattern" indicates the "relationship between the emission direction (emission angle) of the laser light and the received light intensity of the reflected light" when the low reflectance object enters the monitoring area 10 from the first entrance / exit 11 and passes through the first entrance / exit area 15, and at least one "second entry light receiving intensity pattern" indicates the "relationship between the emission direction (emission angle) of the laser light and the received light intensity of the reflected light" when the low reflectance object enters the monitoring area 10 from the second entrance / exit 13 and passes through the second entrance / exit area 17.

[0032] Then, the processing device 7 determines that a low-reflectivity object has entered the monitored area 10 from the first entrance / exit 11 when the respective received light intensities of the laser light emitted in multiple directions within the first entrance / exit area 15 measured by the first distance measuring sensor 3 show a similar tendency to at least one of the ``first entry received light intensity patterns.''

[0033] Alternatively, the processing device 7 determines that a low-reflectivity object has entered the monitored area 10 from the second entrance / exit 13 when the respective received light intensities of the laser light emitted in multiple directions within the second entrance / exit area 17 measured by the second distance measuring sensor 5 show a similar tendency to at least one of the ``second entry received light intensity patterns.''

[0034] In this manner, the processing device 7 determines whether or not a low-reflectivity object has entered the monitored area 10 from the first entrance 11 or the second entrance 13. In other words, the processing device 7 detects the entry of a low-reflectivity object into the monitored area 10.

[0035] Next, the process of step S13 described above, that is, the process of determining whether or not a low reflectance object has entered from the monitored area 10, will be described.

[0036] As shown in FIG. 5A, when a low-reflectivity object (e.g., a black automobile) LO passes through the second entrance / exit area 17 and exits from the second entrance / exit 13 (i.e., exits from the monitoring area 10), the second distance measuring sensor 5 receives the reflected light by the low-reflectivity object LO for each of the laser lights emitted in multiple directions in the second entrance / exit area 17. In this case, from the measurement result of the second distance measuring sensor 5, third data indicating the "relationship between the emission direction (emission angle) of the laser light and the received light intensity of the reflected light" when the low-reflectivity object LO passes through the second entrance / exit area 17 and exits from the second entrance / exit 13, as shown in FIG. 5B, for example, is obtained. If such third data is collected and machine learning is performed, for example, a pattern when the low-reflectivity object LO passes through the second entrance / exit area 17 and exits from the second entrance / exit 13 can be obtained. The obtained pattern is a characteristic pattern of the light receiving state of reflected light at the second entrance / exit area 17 when the low-reflectivity object LO exits the monitored area 10, and enables detection of the low-reflectivity object that exits from the second entrance / exit 13. Note that the dashed line in Fig. 5B shows, for reference, an example of data when a high-reflectivity object passes through the second entrance / exit area 17 and exits from the second entrance / exit 13.

[0037] Similarly, when the low-reflectivity object LO passes through the first entrance / exit area 15 and exits from the first entrance / exit 11 (i.e., when exiting from the monitoring area 10), the first distance measuring sensor 3 receives the reflected light by the low-reflectivity object LO for each of the laser lights emitted in multiple directions in the first entrance / exit area 15. In this case, from the measurement result of the first distance measuring sensor 3, fourth data indicating the "relationship between the emission direction (emission angle) of the laser light and the received light intensity of the reflected light" when the low-reflectivity object LO passes through the first entrance / exit area 15 and exits from the first entrance / exit 11 is obtained. If such fourth data is collected and machine learning is performed, for example, a pattern when the low-reflectivity object LO passes through the first entrance / exit area 15 and exits from the first entrance / exit 11 can be obtained. The obtained pattern is a characteristic pattern of the light receiving state of the reflected light in the first entrance / exit area 15 when the low-reflectivity object LO exits from the monitoring area 10, and enables the detection of the low-reflectivity object that exits from the first entrance / exit 11.

[0038] Therefore, in this embodiment, the processing device 7 has at least one "first exit light receiving intensity pattern" which is a result of machine learning of third data obtained about various low reflectance objects that may pass through the monitoring area 10, and at least one "second exit light receiving intensity pattern" which is a result of machine learning of fourth data obtained about various low reflectance objects that may pass through the monitoring area 10. Note that at least one "first exit light receiving intensity pattern" indicates the "relationship between the emission direction (emission angle) of the laser light and the received intensity of the reflected light" when the low reflectance object passes through the second entrance / exit area 17 and exits from the second entrance / exit 13, and at least one "second exit light receiving intensity pattern" indicates the "relationship between the emission direction (emission angle) of the laser light and the received intensity of the reflected light" when the low reflectance object passes through the first entrance / exit area 15 and exits from the first entrance / exit 11.

[0039] Then, after it is determined that a low-reflectivity object has entered the monitored area 10 from the first entrance / exit 11, the processing device 7 determines that a low-reflectivity object has exited from the second entrance / exit 13 if the respective received light intensities of the laser light emitted in multiple directions within the second entrance / exit area 17 measured by the second distance measuring sensor 5 show a similar tendency to at least one of the ``first exit received light intensity patterns.''

[0040] Alternatively, after it is determined that a low-reflectivity object has entered the monitored area 10 from the second entrance / exit 13, the processing device 7 determines that a low-reflectivity object has exited from the first entrance / exit 11 if the respective received light intensities of laser light emitted in multiple directions within the first entrance / exit area 15 measured by the first distance measuring sensor 3 show a similar tendency to at least one of the ``second exit received light intensity patterns.''

[0041] In this manner, the processing device 7 determines whether or not the low-reflectivity object has exited through the first entrance 11 or the second entrance 13. In other words, the processing device 7 detects the exit of the low-reflectivity object from the monitoring area 10.

[0042] Furthermore, the fact that a low-reflectivity object that has entered the monitored area 10 does not exit the monitored area 10 means that the low-reflectivity object is within the monitored area 10. Therefore, by detecting the entry of a low-reflectivity object into the monitored area 10 and the exit of the low-reflectivity object from the monitored area 10, it is possible to detect whether or not a low-reflectivity object is present within the monitored area 10. In other words, if the entry of a low-reflectivity object into the monitored area 10 is detected but the exit of the low-reflectivity object from the monitored area 10 is not detected, it can be considered that a low-reflectivity object is present within the monitored area 10.

[0043] In addition, one of the first entrance / exit area 11 and the second entrance / exit area 13 in this embodiment corresponds to the "entrance of the monitored area" in the present invention, and the other of the first entrance / exit area 11 and the second entrance / exit area 13 corresponds to the "exit of the monitored area" in the present invention. In addition, one of the first entrance / exit area 15 and the second entrance / exit area 17 in this embodiment corresponds to the "entrance area" in the present invention, and the other of the first entrance / exit area 15 and the second entrance / exit area 17 in this embodiment corresponds to the "exit area" in the present invention. Furthermore, one of the first distance measurement sensor 3 and the second distance measurement sensor 5 in this embodiment corresponds to the "entrance side distance measurement sensor" in the present invention, and the other of the first distance measurement sensor 3 and the second distance measurement sensor 5 corresponds to the "exit side distance measurement sensor" in the present invention.

[0044] More specifically, when an object (low reflectivity object) enters the monitoring area 10 from the first entrance 11, the first entrance 11, the second entrance 13, the first entrance area 15, the second entrance area 17, the first distance measuring sensor 3, and the second distance measuring sensor 5 in this embodiment correspond to the "entrance of the monitoring area", the "exit of the monitoring area", the "entrance area", the "exit area", the "entrance side distance measuring sensor", and the "exit side distance measuring sensor" in the present invention, respectively. On the other hand, when an object (low reflectivity object) enters the monitoring area 10 from the second entrance 13, the first entrance 11, the second entrance 13, the first entrance area 15, the second entrance area 17, the first distance measuring sensor 3, and the second distance measuring sensor 5 in this embodiment correspond to the "exit of the monitoring area", the "entrance of the monitoring area", the "exit area", the "entrance area", the "exit side distance measuring sensor", and the "entrance side distance measuring sensor" in the present invention, respectively.

[0045] According to the object detection device 1 according to the embodiment, for example, the following effects can be obtained.

[0046] The processing device 7 of the object detection device 1 detects the entry of a low-reflectivity object into the monitoring area 10 from the state of receiving reflected light at a first entrance / exit area 15 set in the monitoring area 10, and detects the departure of a low-reflectivity object from the monitoring area 10 from the state of receiving reflected light at a second entrance / exit area 17 set in the monitoring area 10. Alternatively, the processing device 7 of the object detection device 1 detects the entry of a low-reflectivity object into the monitoring area 10 from the state of receiving reflected light at the second entrance / exit area 17, and detects the departure of a low-reflectivity object from the monitoring area 10 from the state of receiving reflected light at the first entrance / exit area 15.

[0047] Specifically, the processing device 7 of the object detection device 1 is configured to detect the entry of a low-reflectivity object into the monitoring area 10 based on the received light intensity of each reflected light of the laser light emitted in multiple directions in the first entrance / exit area 15, and is configured to detect the departure of a low-reflectivity object from the monitoring area 10 based on the received light intensity of each reflected light of the laser light emitted in multiple directions in the second entrance / exit area 17. Alternatively, the processing device 7 of the object detection device 1 is configured to detect the entry of a low-reflectivity object into the monitoring area 10 based on the received light intensity of each reflected light of the laser light emitted in multiple directions in the second entrance / exit area 17, and is configured to detect the departure of a low-reflectivity object from the monitoring area 10 based on the received light intensity of each reflected light of the laser light emitted in multiple directions in the first entrance / exit area 15.

[0048] By utilizing the light receiving state (light receiving direction and light receiving intensity) of the reflected light in the first entrance / exit area 15, specifically, the light receiving intensity of each reflected light of the laser light emitted in a plurality of directions in the first entrance / exit area 15, it is possible to detect that a low reflectance object has entered the monitoring area 10 through the first entrance / exit 11 and has exited from the monitoring area 10. In addition, by utilizing the light receiving state (light receiving direction and light receiving intensity) of the reflected light in the second entrance / exit area 17, specifically, the light receiving intensity of each reflected light of the laser light emitted in a plurality of directions in the second entrance / exit area 17, it is possible to detect that a low reflectance object has entered the monitoring area 10 through the second entrance / exit 13 and has exited from the monitoring area 10. Then, if it is possible to detect the entry of a low reflectance object into the monitoring area 10 and the exit of a low reflectance object from the monitoring area 10, it is possible to determine whether or not a low reflectance object is in the monitoring area 10. In other words, if the processing device 7 of the object detection device 1 detects the entry of a low-reflectivity object into the monitored area 10 but does not detect the exit of the low-reflectivity object from the monitored area 10, it can determine that a low-reflectivity object is present within the monitored area 10.

[0049] Therefore, the object detection device 1 according to the embodiment can prevent missed detection of low-reflectance objects, that is, objects with low reflectance to laser light, such as dark or black-colored automobiles.

[0050] In particular, the processing device 7 of the object detection device 1 generates at least one "first entry light receiving intensity pattern" that indicates the "relationship between the emission direction (emission angle) of the laser light and the received light intensity of the reflected light" when a low-reflectivity object enters the monitoring area 10 from the first entrance 11 and passes through the first entrance area 15, and (2) at least one "second entry light receiving intensity pattern" that indicates the "relationship between the emission direction (emission angle) of the laser light and the received light intensity of the reflected light" when a low-reflectivity object enters the monitoring area 10 from the second entrance 13 and passes through the second entrance area 17. (3) at least one "first exit light receiving intensity pattern" that indicates the relationship between the emission direction (emission angle) of the laser light and the received intensity of the reflected light when a low-reflectivity object passes through the second entrance / exit area 17 and exits from the second entrance / exit 13, and (4) at least one "second exit light receiving intensity pattern" that indicates the relationship between the emission direction (emission angle) of the laser light and the received intensity of the reflected light when a low-reflectivity object passes through the first entrance / exit area 15 and exits from the first entrance / exit 11.

[0051] The processing device 7 of the object detection device 1 is configured to detect the entry of a low-reflectivity object into the monitoring area 10 when the light receiving intensity of each of the laser beams emitted in multiple directions in the first entrance / exit area 15 shows a similar tendency to at least one of the "first entry light receiving intensity patterns", or when the light receiving intensity of each of the laser beams emitted in multiple directions in the second entrance / exit area 17 shows a similar tendency to at least one of the "second entry light receiving intensity patterns". The processing device 7 of the object detection device 1 is configured to detect the exit of a low-reflectivity object from the monitoring area 10 when the light receiving intensity of each of the laser beams emitted in multiple directions in the second entrance / exit area 17 shows a similar tendency to at least one of the "first exit light receiving intensity patterns", or when the light receiving intensity of each of the laser beams emitted in multiple directions in the first entrance / exit area 15 shows a similar tendency to at least one of the "second exit light receiving intensity patterns".

[0052] Therefore, according to the object detection device 1 of the embodiment, it is possible to stably detect the entry of low-reflectivity objects into the monitoring area 10 and the exit of low-reflectivity objects from the monitoring area 10, and as a result, it is possible to more effectively prevent the detection of low-reflectivity objects, i.e. objects with low laser light reflectivity such as dark or black automobiles, from being missed.

[0053] In the above embodiment, the monitored area 10 has two entrances (the first entrance 11 and the second entrance 13) for entering and exiting the monitored area 10. However, this is not limited to this. One of the first entrance 11 and the second entrance 13 may be set as the "entrance" of the monitored area 10, and the other of the first entrance 11 and the second entrance 13 may be set as the "exit" of the monitored area 10.

[0054] Also, in the above-described embodiment, the object detection device 1 includes a first distance measurement sensor 3 arranged on one side of a first entrance 11 of a monitoring area 10 and a second distance measurement sensor 5 arranged on the other side of a second entrance 13 of the monitoring area 10, and the entire monitoring area 10 is covered by the scanning range of the laser light of the first distance measurement sensor 3 and the scanning range of the laser light of the second distance measurement sensor 5. However, this is not limited to this. For example, as shown in FIG. 6, the object detection device 1 may include one distance measurement sensor 19, and the entire monitoring area 10 may be covered by the scanning range of the laser light of the one distance measurement sensor 19.

[0055] In the above-described embodiment, the object detection device 1 sets the road within the railroad crossing as the monitoring area 10, and detects objects within the monitoring area 10 as obstacles. However, this is not limited to this. The object detection device 1 can set the monitoring area 10 as an area through which various objects, including low-reflectivity objects, pass.

[0056] Furthermore, in the above-described embodiment, the processing device 7 of the object detection device 1 detects the entry of a low-reflectivity object into the monitoring area 10 and the departure of a low-reflectivity object from the monitoring area 10 by utilizing the light receiving state (light receiving direction and light receiving intensity) of the reflected light at the first entrance / exit area 15 and the light receiving state (light receiving direction and light receiving intensity) of the reflected light at the second entrance / exit area 17. However, this is not limited to this. The processing device 7 of the object detection device 1 may also detect the entry of an object other than a low-reflectivity object (e.g., a high-reflectivity object) into the monitoring area 10 and the departure of an object other than a low-reflectivity object from the monitoring area 10 by a similar method.

[0057] Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to the above-described embodiments and modifications, and it goes without saying that further modifications and changes are possible based on the technical concept of the present invention. [Explanation of symbols]

[0058] REFERENCE SIGNS LIST 1... object detection device, 3... first distance measurement sensor, 5... second distance measurement sensor, 7... processing device, 10... monitoring area, 11... first entrance / exit, 13... second entrance / exit, 15... first entrance / exit area, 17... second entrance / exit area, 19... distance measurement sensor

Claims

1. An object detection device that includes a distance measuring sensor that scans a monitoring area with laser light and receives reflected light, and detects the entry of an object into the monitoring area from the reception state of the reflected light at an entrance area set in the monitoring area, and detects the exit of the object from the reception state of the reflected light at an exit area set in the monitoring area.

2. 2. The object detection device according to claim 1, wherein the object entering the monitoring area is detected based on the received light intensity of each reflected light of laser light emitted in multiple directions within the entrance area, and the object leaving the monitoring area is detected based on the received light intensity of each reflected light of laser light emitted in multiple directions within the exit area.

3. The object detection device according to claim 1 , wherein the object is a low-reflectivity object having a low reflectivity for laser light.

4. an entry-time light receiving intensity pattern showing a relationship between the emission direction of laser light and the received intensity of reflected light when the low-reflectivity object enters the monitoring area and passes through the entrance area, and an exit-time light receiving intensity pattern showing a relationship between the emission direction of laser light and the received intensity of reflected light when the low-reflectivity object passes through the exit area and exits from the monitoring area, The entry of the low-reflectivity object into the monitoring area is detected when the received light intensities of the respective reflected lights of the laser light emitted in multiple directions within the entrance area show a similar tendency to the received light intensity pattern at the time of entry, and the exit of the low-reflectivity object from the monitoring area is detected when the received light intensities of the respective reflected lights of the laser light emitted in multiple directions within the exit area show a similar tendency to the received light intensity pattern at the time of exit. The object detection device according to claim 3 .

5. An object detection device as described in any one of claims 1 to 4, wherein if the object is detected as entering the monitoring area and then the object is not detected as leaving the monitoring area, the object is deemed to be present in the monitoring area.

6. An object detection device as described in any one of claims 1 to 4, wherein the ranging sensor includes an entrance side ranging sensor provided on the entrance side of the monitoring area and scanning laser light over a range including the entrance area, and an exit side ranging sensor provided on the exit side of the monitoring area and manipulating laser light over a range including the exit area.

7. The monitoring area is a road within a railroad crossing, and the object is detected as an obstacle. The object detection device according to any one of claims 1 to 4.

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