Object Detection Systems and Infrastructure Sensors

Abstract

This object detection system comprises: an infrastructure sensor attached to an arm that extends from a static object secured to a road surface or to a facility, the arm being capable of rotating in the circumferential direction of the static object; and an angle sensor disposed at a site at which the arm is connected to the static object, the angle sensor detecting the angle of rotation of the arm. The infrastructure sensor includes a detection unit for detecting the position of an object present in an area subject to detection by the infrastructure sensor, and a correction unit for correcting the position of the object as detected by the detection unit on the basis of the angle of rotation detected by the angle sensor.

Description

[Technical Field]

[0001] This disclosure relates to an object detection system and an infrastructure sensor. This application claims priority to Japanese Patent Application No. 2021-112775, filed on July 7, 2021, and incorporates the entire contents of said Japanese application by reference. [Background technology]

[0002] Patent Document 1 discloses a road condition assessment device that detects the intensity and spectrum of reflected signals from vehicles using multiple radio radars installed on lanes, determines the position and speed of the vehicle in the direction of the lane using the intensity and spectrum of reflected signals from the vehicle detected by the radio radar, determines that the reflected signals from the same traveling vehicle are from the same vehicle when they are detected by at least two or more radio radars installed on each lane, calculates the maximum value of the amplitude of the reflected signals from the same traveling vehicle for each radio radar within a predetermined fixed time period, and compares the maximum values ​​to estimate the lane in which the vehicle is located and its position in the direction of the road width. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-48296 Summary of the Invention

[0004] An object detection system according to one aspect of the present disclosure comprises an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or equipment and rotatable in a circumferential direction of the stationary object, and an angle sensor positioned at a point where the arm connects to the stationary object and detecting a rotation angle of the arm, wherein the infrastructure sensor includes a detection unit that detects the position of an object present in a detection area of ​​the infrastructure sensor, and a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle detected by the angle sensor.

[0005] An object detection system according to another aspect of the present disclosure includes an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or equipment and rotatable in a circumferential direction of the stationary object, and a gyro sensor that detects the angular velocity of the arm, wherein the infrastructure sensor includes a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor, and a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle of the arm relative to the stationary object obtained based on the angular velocity detected by the gyro sensor.

[0006] An infrastructure sensor according to one aspect of the present disclosure is an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or equipment, the arm being rotatable in a circumferential direction of the stationary object, and comprising: a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor; and a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle of the arm relative to the stationary object detected by an angle sensor located at the point where the arm connects to the stationary object.

[0007] An infrastructure sensor according to another aspect of the present disclosure is an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or equipment and capable of rotating circumferentially around the stationary object, and includes: a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor; and a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle of the arm relative to the stationary object obtained based on the angular velocity of the arm detected by a gyro sensor disposed on the arm.

[0008] The present disclosure can be realized not only as an object detection system and an infrastructure sensor having the above-described characteristic configuration, but also as a method having steps corresponding to characteristic processes of the object detection system, or as a computer program causing a computer to execute the above-described method. The present disclosure can also be realized by using a semiconductor integrated circuit as part of the infrastructure sensor. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of use of an infrastructure sensor according to an embodiment. [Figure 2] 1 is a diagram illustrating an example of the configuration of a traffic monitoring system according to an embodiment. [Figure 3A] FIG. 2 is a side view illustrating an example of the configuration of an angle sensor according to the embodiment. [Figure 3B] FIG. 1 is a plan view illustrating an example of a configuration of an angle sensor according to an embodiment. [Figure 4] FIG. 2 is a diagram illustrating an example of an electric circuit of the angle sensor according to the embodiment. [Figure 5] FIG. 2 is a block diagram illustrating an example of an internal configuration of an infrastructure sensor according to the embodiment. [Figure 6] FIG. 2 is a functional block diagram illustrating an example of a function of an infrastructure sensor according to the embodiment. [Figure 7] 5A and 5B are diagrams for explaining the principle of correction of detection results of infrastructure sensors according to an embodiment. [Figure 8A] 10 is a diagram illustrating an example of a detection range of an infrastructure sensor when an arm is not rotating relative to a pole. FIG. [Figure 8B] 10A and 10B are diagrams illustrating an example of a detection range of an infrastructure sensor when an arm rotates relative to a pole. [Figure 8C] 10A and 10B are diagrams illustrating another example of the detection range of the infrastructure sensor when the arm rotates relative to the pole. [Figure 9] 10 is a flowchart illustrating an example of an operation procedure of an infrastructure sensor according to the embodiment. [Figure 10]FIG. 10 is a diagram showing a modified example in which a rotary encoder is used as an angle sensor according to the embodiment. [Figure 11A] FIG. 10 is a diagram showing a modified example in which a reflective optical sensor is used as the angle sensor according to the embodiment. [Figure 11B] FIG. 10 is a diagram showing another modified example in which a reflective optical sensor is used as the angle sensor according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Problems to be solved by this disclosure> Sensors used for traffic monitoring (also called "infrastructure sensors") are attached to arms that extend over the road from poles or utility poles (also called "supports") fixed to the side of the road. If the arms rotate relative to the support poles due to strong winds, vibrations, etc., the installation position of the infrastructure sensors shifts, making it impossible to accurately detect vehicles.

[0011] <Advantages of this disclosure> According to the present disclosure, even if the installation position of the infrastructure sensor is shifted, an object such as a vehicle can be accurately detected.

[0012] <Summary of Embodiments of the Present Disclosure> The following provides an outline of embodiments of the present disclosure.

[0013] (1) The object detection system according to this embodiment includes an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or a facility and rotatable in a circumferential direction of the stationary object; and an angle sensor disposed at a point where the arm connects to the stationary object and detecting a rotation angle of the arm. The infrastructure sensor includes a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor, and a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle detected by the angle sensor. This allows the detection results of the infrastructure sensor to be corrected if the installation position of the infrastructure sensor is shifted. Therefore, the infrastructure sensor can accurately detect objects such as vehicles.

[0014] (2) The angle sensor may include a first member fixed to the stationary object and a second member fixed to the arm and rotating in a circumferential direction of the first member in accordance with the rotation of the arm, and may detect the rotation angle of the arm relative to the stationary object by detecting the rotation angle of the second member relative to the first member. This makes it possible to realize an angle sensor that detects the rotation angle of the arm relative to the stationary object.

[0015] (3) The arm is rotatably supported by a support member relative to the stationary object, and the support member rotates in a circumferential direction of the stationary object in accordance with the rotation of the arm. The angle sensor includes a first member fixed to the stationary object and a second member fixed to the support member and rotating in a circumferential direction of the first member in accordance with the rotation of the support member. By detecting the rotation angle of the second member relative to the first member, the angle sensor can detect the rotation angle of the arm relative to the stationary object. rotate Angle detection may also be performed, whereby an angle sensor can be attached to the connection point between the stationary object and the arm to enable detection of the angle of rotation of the arm relative to the stationary object.

[0016] (4) When the rotation angle detected by the angle sensor exceeds a first threshold, the correction unit may output abnormality information without correcting the position of the object. This makes it possible to output abnormality information without correcting the detection result of the infrastructure sensor when the amount of positional deviation of the infrastructure sensor is unacceptably large.

[0017] (5) The object detection system may further include an inclination sensor that detects an inclination angle of the stationary object with respect to a reference direction, and the correction unit may output abnormality information without correcting the position of the object when the inclination angle detected by the inclination sensor exceeds a second threshold. This makes it possible to output abnormality information without correcting the detection result of the infrastructure sensor when the inclination of the stationary object is unacceptably large.

[0018] (6) The infrastructure sensor according to this embodiment is an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or equipment and rotatable in a circumferential direction of the stationary object. The infrastructure sensor includes: a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor; and a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle of the arm relative to the stationary object detected by an angle sensor located at a point where the arm connects to the stationary object. This allows the detection results of the infrastructure sensor to be corrected if the installation position of the infrastructure sensor is shifted. Therefore, the infrastructure sensor can accurately detect objects such as vehicles.

[0019] (7) The object detection system according to this embodiment includes an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or a facility and rotatable in a circumferential direction of the stationary object, and a gyro sensor detecting the angular velocity of the arm. The infrastructure sensor includes a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor, and a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle of the arm relative to the stationary object obtained based on the angular velocity detected by the gyro sensor. This allows the detection results of the infrastructure sensor to be corrected if the installation position of the infrastructure sensor is shifted. Therefore, the infrastructure sensor can accurately detect objects such as vehicles.

[0020] (8) The infrastructure sensor according to this embodiment is an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or equipment and rotatable in a circumferential direction of the stationary object. The infrastructure sensor includes: a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor; and a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle of the arm relative to the stationary object, which is obtained based on the angular velocity of the arm detected by a gyro sensor disposed on the arm. This allows the detection results of the infrastructure sensor to be corrected if the installation position of the infrastructure sensor is shifted. Therefore, the infrastructure sensor can accurately detect objects such as vehicles.

[0021] <Details of the embodiment of the present disclosure> DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. At least some of the following preferred embodiments may be combined in any desired manner.

[0022] [1. Traffic monitoring system] FIG. 1 is a diagram illustrating an example of use of an infrastructure sensor according to an embodiment. The infrastructure sensor 100 according to this embodiment is a radio wave radar for traffic monitoring. The infrastructure sensor 100 is attached to an arm 220 connected to a pole 210, which is a stationary object provided on or near a road. The infrastructure sensor 100 irradiates a target area 300 (detection target area) on the road with radio waves (millimeter waves) and detects an object (e.g., a vehicle V) within the target area 300 by receiving the reflected waves. More specifically, the infrastructure sensor 100 can detect the distance from the infrastructure sensor 100 to the vehicle V traveling on the road, the speed of the vehicle V, and the horizontal angle of the position of the vehicle V relative to the radio wave irradiation axis of the infrastructure sensor 100.

[0023] The infrastructure sensor 100 is installed so that the direction of the radio wave emission axis (the direction shown by the dashed line in FIG. 1; hereinafter referred to as the "radio wave emission direction") faces the target area 300. If the radio wave emission direction is not correctly facing the target area 300, the infrastructure sensor 100 cannot accurately detect objects within the target area 300. For this reason, the angle of the infrastructure sensor 100 is adjusted so that the radio wave emission direction faces the target area 300.

[0024] In the following description, the lane length direction in the target area 300 is defined as Y, the lane width direction as X, and the height direction as Z. The origin is a point on the road surface vertically below the infrastructure sensor 100. The coordinate system defined by X, Y, and Z is used by the infrastructure sensor 100. That is, the infrastructure sensor 100 identifies the coordinates of the detected vehicle V in the XYZ coordinate space.

[0025] 2 is a diagram showing an example of the configuration of a traffic monitoring system (object detection system) 10 according to an embodiment. The traffic monitoring system 10 includes an infrastructure sensor 100, an angle sensor 150, and an inclination sensor 160.

[0026] The pole 210 extends vertically and is fixed to the ground. An arm 220 is connected to the pole 210 so as to be rotatable around the axis (vertical axis) of the pole 210. Specifically, the arm 220 is connected to the pole 210 via support members 231, 232, and 233. The arm 220 includes an arm main body 221, a lower support arm 222, and an upper support arm 223. The arm main body 221 is a rod-shaped member that extends linearly in the horizontal direction. The arm main body 221 is connected to the pole 210 via the support member 231. The support member 232 is disposed below the support member 231 on the pole 210. The lower support arm 222 is an inclined rod-shaped member that connects a lower portion of the arm main body 221 to the pole 210. The lower support arm 222 is connected to the pole 210 via the support member 232 at a position below the connection position of the arm main body 221 on the pole 210. Support member 233 is disposed above support member 231 on pole 210. Upper support arm 223 is an inclined rod-shaped member that connects the upper portion of arm main body 221 to pole 210. Upper support arm 223 is connected to pole 210 via support member 233 at a position above the connection position of arm main body 221 on pole 210.

[0027] The support members 231, 232, and 233 support the arm 220 rotatably relative to the pole 210. That is, the support member 231 supports the arm main body 221 rotatably in a circumferential direction about the axis of the pole 210. The support member 232 supports the lower support arm 222 rotatably in a circumferential direction about the axis of the pole 210. The support member 233 supports the upper support arm 223 rotatably in a circumferential direction about the axis of the pole 210. As a result, when a force in a rotational direction about the axis of the pole 210 acts on the arm 220 due to wind, vibration, or the like, for example, the arm 220 rotates in the circumferential direction about the axis, and damage to the arm 220 is suppressed.

[0028] The angle sensor 150 is disposed at a connection point where the pole 210 and the arm 220 are connected. For example, the angle sensor 150 is disposed at a connection point where the pole 210 and the arm body 221 are connected. The "connection point" may include not only the portion where the pole 210 and the arm 220 are in contact with each other (hereinafter referred to as the "joint portion"), but also the surrounding area of ​​the joint portion. For example, when the angle sensor 150 is in contact with the surrounding area of ​​the joint portion of the pole 210 and is in contact with the surrounding area of ​​the joint portion of the arm 220, the angle sensor 150 is disposed at the "connection point."

[0029] The connection point between the pole 210 and the arm 220 includes not only the connection point between the pole 210 and the arm main body 221 but also the connection point between the pole 210 and the lower support arm 222 and the connection point between the pole 210 and the upper support arm 223. The angle sensor 150 may be disposed at the connection point between the pole 210 and the lower support arm 222 or the connection point between the pole 210 and the upper support arm 223, instead of at the connection point between the pole 210 and the arm main body 221.

[0030] The tilt sensor 160 is disposed on the pole 210. The tilt sensor 160 can detect the tilt angle of the axis of the pole 210 relative to the vertical axis. The tilt sensor 160 outputs tilt data indicating the detected tilt angle. The vertical axis direction is an example of a "reference direction."

[0031] The angle sensor 150 and the tilt sensor 160 are connected to the infrastructure sensor 100 by signal lines (not shown). The output signals of the angle sensor 150 and the tilt sensor 160 are provided to the infrastructure sensor 100.

[0032] [2. Angle sensor] 3A and 3B are diagrams illustrating an example of the configuration of an angle sensor according to an embodiment. FIG. 3A is a side view of an angle sensor 150, and FIG. 3B is a plan view of the angle sensor 150. As illustrated in FIGS. 3A and 3B, the angle sensor 150 according to the embodiment includes a first member 151 and a second member 152. The first member 151 is attached to a pole 210, and the second member 152 is attached to an arm main body 221. More specifically, the second member 152 is attached to a support member 231. The angle sensor 150 detects the rotation angle of the second member 152 relative to the first member 151, thereby detecting the rotation angle of the arm 220 relative to the pole 210. The rotation angle of the arm 220 relative to the pole 210 is the displacement angle of the arm 220 when the arm 220 rotates in a circumferential direction around the axis of the pole 210. The rotation angle of the second member 152 relative to the first member 151 is the displacement angle of the second member 152 when the second member 152 rotates relative to the axis of the pole 210 to which the first member 151 is fixed.

[0033] The configuration of the angle sensor 150 according to the embodiment will be described in more detail. The support member 231 includes an annular portion 231a and an arm fixing portion 231b. The annular portion 231a is formed in a circular ring shape and is wound around the outer periphery of the pole 210. The annular portion 231a includes, for example, an inner ring portion and an outer ring portion, and the outer ring portion is configured to be rotatable relative to the inner ring portion. This allows a portion of the annular portion 231a (the outer ring portion) to rotate in the circumferential direction around the axis of the pole 210. The arm fixing portion 231b is attached to the outer ring portion of the annular portion 231a. Therefore, the arm fixing portion 231b is rotatable in the circumferential direction around the axis of the pole 210. The arm fixing portion 231b is formed in a cylindrical shape and is attached to the arm main body 221 so as to wrap around the end of the arm main body 221.

[0034] The second member 152 is attached to the arm fixing portion 231b. Therefore, when the arm 220 rotates relative to the pole 210, the second member 152 also rotates integrally with the arm 220. On the other hand, the first member 151 is fixed to the pole 210. When the arm 220 rotates relative to the pole 210, the first member 151 does not rotate. Therefore, the first member 151 and the second member 152 rotate relative to each other.

[0035] In this embodiment, the angle sensor 150 is a potentiometer. A small gap is provided between the first member 151 and the second member 152. The angle sensor 150 includes a brush 151a extending from the first member 151 to the second member 152.

[0036] FIG. 4 is a diagram illustrating an example of an electrical circuit of the angle sensor 150 according to the embodiment. The angle sensor 150 includes a first circuit 151C and a second circuit 152C. The first circuit 151C is provided on the first member 151. The second circuit 152C is provided on the second member 152. The first circuit 151C includes a brush 151a, and the second circuit 152C includes a resistor 152R. The brush 151a contacts the resistor 152R, and when the arm 220 rotates relative to the pole 210, the brush 151a moves across the resistor 152R. An input voltage Vi is applied across the resistor 152R. A voltage Vo is output between the brush 151a and one end of the resistor 152R. The output voltage Vo changes depending on the position of the brush 151a relative to the resistor 152R. In other words, the output voltage Vo indicates the rotation angle of the arm 220 relative to the pole 210. The angle sensor 150 outputs angle data indicating the detected rotation angle.

[0037] Alternatively, the first circuit 151C may be provided in the second member 152, and the second circuit 152C may be provided in the first member 151. The angle sensor 150 configured in this manner can also detect the rotation angle of the arm 220 relative to the pole 210.

[0038] [3. Infrastructure Sensor Configuration] 5 is a block diagram showing an example of the internal configuration of the infrastructure sensor 100 according to the embodiment. The infrastructure sensor 100 includes a processor 111, a nonvolatile memory 112, a volatile memory 113, a transmitting circuit 114, a receiving circuit 115, and an input / output interface (I / O) 116.

[0039] The volatile memory 113 is, for example, a semiconductor memory such as an SRAM (Static Random Access Memory) or a DRAM (Dynamic Random Access Memory). The non-volatile memory 112 is, for example, a flash memory, a hard disk, a ROM (Read Only Memory), or the like. The non-volatile memory 112 stores a correction program 117, which is a computer program, and data used to execute the correction program 117. The infrastructure sensor 100 is configured with a computer, and each function of the infrastructure sensor 100 is achieved by the processor 111 executing the correction program 117, which is a computer program stored in a storage device of the computer. The correction program 117 can be stored in a recording medium such as a flash memory, a ROM, or a CD-ROM. The processor 111 executes the correction program 117 and corrects the detected position of the vehicle V according to the rotation angle of the arm 220, as will be described later.

[0040] The processor 111 is, for example, a CPU (Central Processing Unit). However, the processor 111 is not limited to a CPU. The processor 111 may also be a GPU (Graphics Processing Unit). The processor 111 may also be, for example, an ASIC (Application Specific Integrated Circuit) or a programmable logic device such as a gate array or FPGA (Field Programmable Gate Array). In this case, the ASIC or programmable logic device is configured to be able to execute processing similar to that of the correction program 117.

[0041] The transmitting circuit 114 includes a transmitting antenna 114a. The transmitting circuit 114 generates a modulated wave and transmits the generated modulated wave from the transmitting antenna 114a. The transmitted modulated wave hits an object (e.g., a vehicle V) and is reflected.

[0042] The receiving circuit 115 includes receiving antennas 115a and 115b. The receiving antennas 115a and 115b receive reflected waves from the vehicle V. The receiving circuit 115 performs signal processing on the received reflected waves. The reflected wave data generated by the signal processing is provided to the processor 111. The processor 111 analyzes the reflected wave data and detects the position and speed of the vehicle V.

[0043] The I / O 116 is connected to the angle sensor 150 and the tilt sensor 160 via a signal line. The I / O 116 receives angle data output from the angle sensor 150 and tilt data output from the tilt sensor 160. Furthermore, the I / O 116 may be able to communicate with an external device via a wired or wireless connection. For example, the I / O 116 may transmit information about the vehicle V detected by the infrastructure sensor 100 to an external device. For example, the I / O 116 may include a wireless communication interface for Dedicated Short Range Communications (DSRC). The I / O 116 may transmit position information and speed information about the vehicle V detected by road-to-vehicle communication to the vehicle V traveling in the target area 300. Furthermore, the I / O 116 may be connectable to an external terminal used by an installer who installs the infrastructure sensor 100. The I / O 116 may be able to output information used for maintenance of the infrastructure sensor 100, such as abnormality information, to the external terminal.

[0044] [4. Infrastructure Sensor Functions] 6 is a functional block diagram showing an example of functions of the infrastructure sensor 100 according to the embodiment. When the processor 111 executes the correction program 117, the infrastructure sensor 100 exhibits the functions of an input unit 121, a detection unit 122, and a correction unit 123.

[0045] The input unit 121 receives the reflected wave data generated by the receiving circuit 115. The input unit 121 receives the angle data output from the angle sensor 150. Furthermore, the input unit 121 receives the tilt data output from the tilt sensor 160.

[0046] The detection unit 122 detects the position of an object present in the detection target area of ​​the infrastructure sensor 100 based on the reflected wave data received by the input unit 121. Specifically, the detection unit 122 extracts reflection points, which are peak points included in the reflected wave. The reflected wave data includes data indicating the waveform of the reflected wave for distance and data indicating the waveform of the reflected wave for angle. The detection unit 122 extracts peak points from each of the waveform of the reflected wave for distance and the waveform of the reflected wave for angle. The detection unit 122 determines the reflection points by associating the peak points in the reflected wave for distance with the peak points in the reflected wave for angle.

[0047] Radio waves emitted from the infrastructure sensor 100 may be reflected simultaneously by multiple vehicles V. The detection unit 122 groups reflection points on the same vehicle V. The detection unit 122 identifies the position of the vehicle V based on the reflected waves received by the receiving antennas 115a and 115b. The position of the vehicle is expressed as coordinate values ​​in the XYZ coordinate system. Specifically, the detection unit 122 determines a representative value of the reflection points belonging to the same group and sets the determined representative value as the position of the vehicle. For example, the representative value is the center of gravity. However, the position of the vehicle may also be a representative value other than the center of gravity of the multiple reflection points. For example, the representative value may be the average value of the reflection points or the median value of the reflection points. The detection unit 122 outputs position information indicating the detected position of the vehicle V.

[0048] The correction unit 123 corrects the position of the vehicle V detected by the detection unit 122 based on the rotation angle detected by the angle sensor 150. If the arm 220 does not rotate with respect to the pole 210, that is, if the rotation angle is not detected by the angle sensor 150, the correction unit 123 does not correct the position of the vehicle V detected by the detection unit 122. In this case, the position information of the vehicle V detected by the detection unit 122 is output.

[0049] The principle of correction of the position of the vehicle V by the correction unit 123 will be described below. FIG. 7 is a diagram for explaining the principle of correction of the detection result of the infrastructure sensor according to the embodiment. As shown in FIG. 7, consider a case where the arm 220 rotates counterclockwise around the axis of the pole 210 by an angle θ in the drawing. The detection range 400 of the infrastructure sensor 100 before the rotation changes to a detection range 400A due to the rotation of the arm 220. The XYZ coordinate system of the infrastructure sensor 100 is changed as follows due to the change in the position of the infrastructure sensor 100: solid line from Dashed line After the arm 220 rotates, when the infrastructure sensor 100 detects the position of the vehicle V, coordinates (Xm, Ym, Zm) are obtained as the detection result. However, because the coordinate system set in the infrastructure sensor 100 has not been corrected after the arm 220 rotates, the coordinates (Xm, Ym, Zm) are deviated from the actual vehicle position (X, Y, Z). In other words, although the actual vehicle V is located at the position indicated by the solid line, the detection result by the infrastructure sensor 100 is the position indicated by the dashed line. The correction unit 123 corrects this deviated detected position.

[0050] When the correction unit 123 corrects the detection result of the infrastructure sensor 100, an xyz coordinate system different from the XYZ coordinate system is used. The xyz coordinate system is an orthogonal coordinate system with its origin on the central axis of the pole 210. The z axis is the central axis of the pole 210, and the origin is the intersection of the ground surface and the z axis. The x axis is parallel to the longitudinal direction of the arm 220, and the y axis is an axis perpendicular to the x axis and z axis. The correction unit 123 converts the coordinates (Xm, Ym, Zm) of the detected vehicle position into coordinates (xm, ym, zm) in the xyz coordinate system. toHere, the Z axis and the z axis are the same, and the height of the infrastructure sensor 100 does not change due to the rotation of the arm 220, so Zm, zm, Z, and z are all the same value.

[0051] The correction unit 123 corrects the coordinate values ​​(xm, ym, zm) of the detected position using the following equation (1) to calculate the corrected coordinate values ​​(x, y, z).

number

[0052] The coordinate value (x, y, z) is the coordinate value obtained by rotating the coordinate value (xm, ym, zm) counterclockwise by θ around the origin of the xyz coordinate system. In other words, the coordinate value (x, y, z) indicates the actual position of the vehicle V.

[0053] The correction unit 123 inversely converts the calculated corrected coordinate values ​​(x, y, z) into coordinates (X, Y, Z) in the XYZ coordinate system, thereby completing the correction of the detection result of the infrastructure sensor 100.

[0054] Referring again to FIG. 6 , the correction unit 123 corrects the position of the vehicle V when the rotation angle detected by the angle sensor 150 is within the first range. When the rotation angle detected by the angle sensor 150 is outside the first range, the correction unit 123 does not correct the position of the vehicle V and outputs abnormality information. The first range is defined by a first limit value (e.g., an upper limit value) and a second limit value (e.g., a lower limit value). The rotation angle detected by the angle sensor 150 being outside the first range is synonymous with the rotation angle exceeding either the first limit value or the second limit value. In other words, when the rotation angle exceeds a threshold value (the first limit value or the second limit value), the correction unit 123 does not correct the position of the vehicle V and outputs abnormality information. The first limit value and the second limit value of the first range are examples of a “first threshold value.”

[0055] FIG. 8A is a diagram illustrating the detection range of the infrastructure sensor 100 when the arm 220 is not rotated relative to the pole 210, and FIGS. 8B and 8C are diagrams illustrating the detection range of the infrastructure sensor 100 when the arm 220 is rotated relative to the pole 210. The infrastructure sensor 100 can emit radio waves to a certain detection range 400 and can detect the position of an object by receiving reflected waves from an object within the detection range 400. In the example shown in FIG. 8A, a target area 300, which is a guaranteed detection range of the infrastructure sensor 100, is set on a road. In FIG. 8A, the target area 300 is included within the detection range 400. Therefore, the infrastructure sensor 100 can detect the position of the vehicle V within the target area 300.

[0056] When arm 220 rotates relative to pole 210, detection range 400 moves. In the example shown in Fig. 8B, target area 300 is included within detection range 400 after the movement. Therefore, in this case as well, infrastructure sensor 100 can detect the position of vehicle V in target area 300. In this case, correction unit 123 corrects the position of vehicle V detected by detection unit 122 in accordance with rotation angle θ.

[0057] If the positional deviation of the infrastructure sensor 100 is too large, it will be impossible to detect the vehicle V traveling on the road. In the example shown in FIG. 8C , the movement of the detection range 400 is too large, and part of the target area 300 is outside the detection range 400. In this case, the infrastructure sensor 100 cannot detect the position of the vehicle V in the target area 300. Therefore, the correction unit 123 does not correct the position of the vehicle V detected by the detection unit 122, and outputs abnormality information.

[0058] For example, a first range for determining whether correction can be performed by correction unit 123 can be set in advance in infrastructure sensor 100. For example, the first range can be set as a range in which target area 300 can be included within detection range 400. That is, in the example shown in Fig. 8B, rotation angle θ is included in the first range, and in the example shown in Fig. 8C, rotation angle θ is outside the first range.

[0059] Referring again to FIG. 6, if the tilt angle φ detected by the tilt sensor 160 is outside the second range, the correction unit 123 does not correct the position of the vehicle V and outputs abnormality information. When the pole 210 tilts, the angle of the infrastructure sensor 100 with respect to the horizontal plane changes, and the height of the infrastructure sensor 100 from the ground also changes. For this reason, the infrastructure sensor 100 cannot accurately detect the position of the vehicle V. V The position of the vehicle V cannot be detected. Therefore, the second range can be set to a small range. For example, the second range can be set based on the elastic limit of the pole 210. That is, if the inclination angle φ of the pole 210 falls outside the second range, the deformation of the pole 210 exceeds the elastic limit and undergoes plastic deformation. If the pole 210 undergoes plastic deformation, the accurate position of the vehicle V cannot be determined even if the correction unit 123 corrects the detection result of the infrastructure sensor 100. The second range is defined by a first limit value (e.g., an upper limit value) and a second limit value (e.g., a lower limit value). The inclination angle detected by the inclination sensor 160 falling outside the second range is equivalent to the inclination angle exceeding either the first limit value or the second limit value. In other words, if the inclination angle exceeds a threshold value (the first limit value or the second limit value), the correction unit 123 does not correct the position of the vehicle V and outputs abnormality information. The first limit value and the second limit value of the second range are examples of a "second threshold value."

[0060] The abnormality information is output to, for example, an external terminal connected to the infrastructure sensor 100. If the external terminal is not connected to the infrastructure sensor 100, the abnormality information output from the correction unit 123 is stored in, for example, the nonvolatile memory 112. When the external terminal is connected to the infrastructure sensor 100, the abnormality information stored in the nonvolatile memory 112 is transmitted to the external terminal.

[0061] [5. Operation of infrastructure sensors] 9 is a flowchart showing an example of an operation procedure of the infrastructure sensor 100 according to the embodiment. When the processor 111 starts the correction program 117, the infrastructure sensor 100 executes the following process.

[0062] The transmitting circuit 114 generates a modulated wave and transmits the generated modulated wave from the transmitting antenna 114a. The transmitted modulated wave hits the vehicle V, and the reflected wave from the vehicle V is received by the receiving antennas 115a and 115b. The receiving circuit 115 processes the reflected wave signal and generates reflected wave data. The processor 111 receives the reflected wave data (step S101).

[0063] The processor 111 analyzes the reflected wave data and detects reflection points. The processor 111 groups reflection points on the same vehicle V and detects the position of the vehicle V (step S102).

[0064] The tilt sensor 160 outputs tilt data indicating the tilt angle φ of the pole 210. The processor 111 receives the tilt data (step S103).

[0065] Processor 111 compares tilt angle φ with the second range and determines whether φ falls within the second range (step S104). If φ falls within the second range (YES in step S104), processor 111 proceeds to step S106. If φ falls outside the second range (NO in step S104), processor 111 outputs abnormality information (step S105).

[0066] The angle sensor 150 outputs angle data indicating the rotation angle θ of the arm 220 relative to the pole 210. The processor 111 receives the angle data (step S106).

[0067] The processor 111 determines whether the rotation angle θ is 0 (step S107). Here, it is sufficient to be able to determine that the arm 220 is not rotating with respect to the pole 210, and therefore it is sufficient to be able to determine that the rotation angle θ is substantially 0. For example, a range including the detection error of the angle sensor 150 can be used as the range of 0.

[0068] If θ is 0 (YES in step S107), processor 111 outputs the position of vehicle V detected in step S102 (step S108). That is, in this case, processor 111 does not correct the position of vehicle V that is detected.

[0069] If θ is not 0 (NO in step S107), processor 111 determines whether θ is within a first range (step S109). If θ is within the first range (YES in step S109), processor 111 proceeds to step S110. If θ is outside the first range (NO in step S109), processor 111 outputs abnormality information (step S105).

[0070] In step S110, the processor 111 performs coordinate transformation of the detected position of the vehicle V from the XYZ coordinate system to the xyz coordinate system. The processor 111 applies equation (1) to the position of the vehicle V after the coordinate transformation, and corrects the position of the vehicle V by θ (step S111). Furthermore, the processor 111 performs inverse coordinate transformation of the corrected position of the vehicle V from the xyz coordinate system to the XYZ coordinate system (step S112).

[0071] The processor 111 outputs the corrected position of the vehicle V in the XYZ coordinate system (step S113). The infrastructure sensor 100 repeats the above operations. The order of the steps does not have to be the order described above. For example, steps S101 and S102 may be performed between steps S109 and S110. In this way, when outputting abnormality information, it is not necessary to receive reflected wave data, analyze the reflected wave data, and perform processing to detect the position of the vehicle V.

[0072] [6. Variation Examples] The angle sensor 150 may be a non-contact sensor such as a rotary encoder instead of a potentiometer. FIG. 10 is a diagram showing a modified example in which a rotary encoder is used as the angle sensor according to the embodiment. For example, the angle sensor 150 may include a light-emitting element 153a such as an LED, a light-receiving element 153b, and slit plates 153c and 153d having a plurality of slits. The slit plates 153c and 153d are light-emitting elements. 153a and a light receiving element 153b The first member 151 may include a light-emitting element 153a, a light-receiving element 153b, and a slit plate 153d, and the second member 152 may include a slit plate 153c. As a result, when the second member 152 rotates relative to the first member 151, the positional relationship between the light-emitting element 153a, the light-receiving element 153b, and the slit plate 153c changes. The slit plate 153d is fixedly disposed relative to the light-emitting element 153a and the light-receiving element 153b. As a result, depending on the position of the slit plate 153c, the light irradiated from the light-emitting element 153a may or may not be received by the light-receiving element 153b. The rotation angle θ is detected by counting the pulses output from the light-receiving element 153b.

[0073] Alternatively, the light-emitting element 153a, the light-receiving element 153b, and the slit plate 153d may be disposed on the second member 152, and the slit plate 153c may be disposed on the first member 151. The angle sensor 150 configured in this manner can also detect the rotation angle θ of the arm 220 with respect to the pole 210.

[0074] In another modified example, the angle sensor 150 can be configured using a reflective optical sensor. FIGS. 11A and 11B are diagrams showing a modified example in which a reflective optical sensor is used as the angle sensor according to the embodiment. In the example shown in FIG. 11A, a reflective optical sensor is disposed in a first member 151. In this modified example, the second member 152 is omitted, and multiple slits 155 are provided in the arm fixing portion 231b. In the example shown in FIG. 11B, a reflective optical sensor is disposed in the second member 152. In this modified example, the first member 151 is omitted, and multiple slits 155 are provided in the pole 210.

[0075] When arm 220 rotates relative to pole 210, the positional relationship between slit 155 and the reflective optical sensor changes. If the reflection point of light emitted from the reflective optical sensor is between two adjacent slits 155, the light reflected by arm fixing portion 231b or the surface of pole 210 is received by the reflective optical sensor, and the light reception level of the reflective optical sensor increases. If the reflection point of light emitted from the reflective optical sensor is slit 155, the light emitted from the reflective optical sensor is not reflected, and the light reception level of the reflective optical sensor decreases. The rotation angle θ is detected by counting the pulses output from the reflective optical sensor.

[0076] As yet another modification, the angle sensor 150 may be a gyro sensor. That is, in this modification, the angle sensor 150 detects the angular velocity of the arm 220. A rotation angle θ of the arm 220 with respect to the pole 210 is calculated based on the angular velocity detected by the angle sensor 150. That is, the rotation angle θ of the arm 220 with respect to the pole 210 can be calculated by integrating the detected angular velocity. The calculation of the rotation angle θ may be performed by the angle sensor 150 or by the processor 111. The correction unit 123 corrects the position of the vehicle V detected by the detection unit 122 based on the calculated rotation angle.

[0077] If the angle sensor 150 is a gyro sensor, it is not necessary to place the angle sensor 150 at the connection point between the pole 210 and the arm 220. The angle sensor 150 may be placed at any position on the arm 220. For example, the angle sensor 150 may be placed inside the housing of the infrastructure sensor 100.

[0078] In the above embodiment, the infrastructure sensor 100 is a radio wave radar, but is not limited to this. The infrastructure sensor 100 may be a LiDAR (Light Detection and Ranging) that detects the position of an object using a laser, or a camera.

[0079] [7. Effects] The traffic monitoring system 10 according to the embodiment includes an infrastructure sensor 100 and an angle sensor 150. The infrastructure sensor 100 includes an arm 220 It can be attached to the arm. 220 extends from a pole 210, which is a stationary object fixed to a road surface or a facility, and is rotatable in a circumferential direction of the pole 210. An angle sensor 150 is disposed at a point where the arm 220 connects to the pole 210. The angle sensor 150 detects the rotation angle of the arm 220 relative to the pole 210. The infrastructure sensor 100 includes a detection unit 122 and a correction unit 123. The detection unit 122 detects the position of a vehicle V (object) present in a target area 300, which is a detection target area of ​​the infrastructure sensor 100. The correction unit 123 corrects the position of the vehicle V detected by the detection unit 122 based on the rotation angle detected by the angle sensor 150. This makes it possible to correct the detection result of the infrastructure sensor 100 if the installation position of the infrastructure sensor 100 is shifted. Therefore, the infrastructure sensor 100 can accurately detect the vehicle V.

[0080] The angle sensor 150 may include a first member 151 and a second member 152. The first member 151 is fixed to the pole 210. The second member 152 is fixed to the arm 220. The second member 152 rotates in the circumferential direction of the first member 151 in accordance with the rotation of the arm 220. The angle sensor 150 detects the rotation angle of the arm 220 relative to the pole 210 by detecting the rotation angle of the second member 152 relative to the first member 151. In this way, the angle sensor 150 that detects the rotation angle of the arm 220 relative to the pole 210 can be realized.

[0081] The arm 220 may be rotatably supported relative to the pole 210 by a support member 231. The support member 231 rotates in the circumferential direction of the pole 210 in accordance with the rotation of the arm 220. The angle sensor 150 may include a first member 151 and a second member 152. The first member 151 is fixed to the pole 210. The second member 152 is fixed to the support member 231, and rotates in the circumferential direction of the first member 151 in accordance with the rotation of the support member 231. The angle sensor 150 detects the rotation angle of the second member 152 relative to the first member 151, thereby determining the rotation angle of the arm 220 relative to the pole 210. rotate Thus, the angle sensor 150 can be attached to the connection point between the pole 210 and the arm 220 so as to be able to detect the angle of rotation of the arm 220 relative to the pole 210.

[0082] When the rotation angle detected by the angle sensor 150 exceeds the first threshold (the rotation angle is outside the first range), the correction unit 123 may output abnormality information without correcting the position of the vehicle V. This makes it possible to output abnormality information without correcting the detection result of the infrastructure sensor 100 when the amount of deviation in the position of the infrastructure sensor 100 is unacceptably large.

[0083] The traffic monitoring system 10 may further include an inclination sensor 160. The inclination sensor 160 detects the inclination angle of the pole 210 relative to the vertical axis (reference direction). If the inclination angle detected by the inclination sensor 160 exceeds a second threshold (if the inclination angle is outside a second range), the correction unit 123 may output abnormality information without correcting the position of the vehicle V. This makes it possible to output abnormality information without correcting the detection result of the infrastructure sensor 100 when the inclination of the pole 210 is unacceptably large.

[0084] The traffic monitoring system 10 according to the embodiment includes an infrastructure sensor 100 and an angle sensor 150, which is a gyro sensor. 220 It can be attached to the arm. 220extends from a pole 210, which is a stationary object fixed to a road surface or a facility, and is rotatable in a circumferential direction of the pole 210. The angle sensor 150 detects the angular velocity of the arm 220. The infrastructure sensor 100 includes a detection unit 122 and a correction unit 123. The detection unit 122 detects the position of a vehicle V present in a target area 300, which is a detection target area of ​​the infrastructure sensor 100. The correction unit 123 corrects the position of the vehicle V detected by the detection unit 122 based on the rotation angle of the arm 220 with respect to the pole 210, which is obtained based on the angular velocity detected by the angle sensor 150. This makes it possible to correct the detection result of the infrastructure sensor 100 if the installation position of the infrastructure sensor 100 is shifted. Therefore, the infrastructure sensor 100 can accurately detect the vehicle V.

[0085] [8. Supplementary Notes] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims rather than the above-described embodiments, and includes meanings equivalent to the claims and all modifications within the scope thereof. [Explanation of symbols]

[0086] 10 Traffic monitoring system (object detection system) 100 Infrastructure Sensors 111 processors 112 Non-volatile memory 113 Volatile Memory 114 Transmitting circuit 114a Transmitting antenna 115 Receiving circuit 115a, 115b receiving antenna 116 Input / Output Interface (I / O) 117 Correction Program 121 Input section 122 Detector 123 Correction Unit 150 Angle Sensor 151 First member 151a Brush 151C 1st circuit 152 Second member 152C 2nd circuit 152R Resistor 153a Light-emitting element 153b Photodetector 153c, 153d Slit plate 155 Slit 160 Inclination Sensor 210 Paul 220 Arm 221 Arm body 222 Lower Support Arm 223 Upper Support Arm 231, 232, 233 Support members 231a Circular section 231b Arm fixing part 300 target area 400 detection range 400A detection range V vehicle

Claims

1. an infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or a facility and rotatable in a circumferential direction of the stationary object; an angle sensor disposed at a location where the arm is connected to the stationary object and detecting a rotation angle of the arm; Equipped with The infrastructure sensor includes: a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor; a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle detected by the angle sensor; Including, The angle sensor a first member fixed to the stationary object; a second member fixed to the arm and rotating in a circumferential direction of the first member in accordance with the rotation of the arm; Including, detecting a rotation angle of the arm relative to the stationary object by detecting a rotation angle of the second member relative to the first member; Object detection system.

2. An infrastructure sensor attached to an arm extending from a stationary object fixed to a road surface or a facility and capable of rotating in a circumferential direction of the stationary object; an angle sensor disposed at a location where the arm is connected to the stationary object and detecting a rotation angle of the arm; Equipped with The infrastructure sensor includes: a detection unit that detects the position of an object present in a detection target area of ​​the infrastructure sensor; a correction unit that corrects the position of the object detected by the detection unit based on the rotation angle detected by the angle sensor; Including, the arm is rotatably supported by a support member relative to the stationary object, the support member rotates in a circumferential direction of the stationary object in accordance with the rotation of the arm, The angle sensor a first member fixed to the stationary object; a second member fixed to the support member and rotating in a circumferential direction of the first member in accordance with the rotation of the support member; Including, detecting a rotation angle of the arm relative to the stationary object by detecting a rotation angle of the second member relative to the first member; Object detection system.

3. the correction unit does not correct the position of the object and outputs abnormality information when the rotation angle detected by the angle sensor exceeds a first threshold value. The object detection system of claim 1 .

4. When the rotation angle detected by the angle sensor exceeds a first threshold, the correction unit does not correct the position of the object and outputs abnormality information. The object detection system of claim 2 .

5. further comprising an inclination sensor for detecting an inclination angle of the stationary object relative to a reference direction; the correction unit does not correct the position of the object and outputs abnormality information when the tilt angle detected by the tilt sensor exceeds a second threshold value. The object detection system according to any one of claims 1 to 4.

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