Radio wave sensor, terminal device, signal controller, detection method, and computer program

Abstract

One aspect of the present disclosure is an infrastructural radio wave sensor that uses radio waves of a prescribed frequency for remote sensing. The radio wave sensor comprises a transmission / reception unit that transmits the radio waves and receives reflected waves and a processor that outputs detection results related to objects crossing a road on the basis of the radio waves transmitted and the reflected waves received. The detection results include range data that represents the area in which at least one of the objects is present.

Description

Radio wave sensor, terminal device, signal controller, detection method, and computer program

[0001] This disclosure relates to a radio wave sensor, a terminal device, a signal controller, a detection method, and a computer program. This application claims priority to Japanese Application No. 2023-117367 filed on July 19, 2023, and incorporates by reference all of the contents of that Japanese application.

[0002] Patent document 1 describes a radio wave sensor that includes a transmitter that transmits radio waves to a target area including a crosswalk, a receiver that receives reflected waves of the radio waves, a calculator that calculates the direction from the sensor to an object and the distance between the sensor and the object based on the transmitted radio waves and the received reflected waves, and a setting unit that sets multiple sub-areas in the target area based on the calculated direction and distance.

[0003] Japanese Patent Application Laid-Open No. 2017-090078

[0004] A device according to one aspect of the present disclosure is an infrastructure-type radio wave sensor that performs remote sensing using radio waves of a predetermined frequency, and includes a transceiver that transmits the radio waves and receives reflected waves of the radio waves, and a processor that outputs detection results regarding objects traveling on a road based on the transmitted radio waves and the received reflected waves, and the detection results include range data that represent the range of existence of at least one of the objects.

[0005] FIG. 1 is a perspective view showing an example of an intersection where a radio wave sensor is installed. FIG. 2 is a road plan view showing an example of a detection area of ​​the radio wave sensor. FIG. 3 is a block diagram showing an example of the hardware configuration of a radio wave sensor. FIG. 4 is a block diagram showing an example of the hardware configuration of a management terminal. FIG. 5 is a block diagram showing an example of the hardware configuration of a traffic light controller. FIG. 6 is a flowchart showing an example of detection processing by a radio wave sensor. FIG. 7 is a flowchart showing an example of range data generation processing. FIG. 8 is a conceptual diagram showing an example of point cloud data. FIG. 7 is a flowchart showing another example of range data generation processing. FIG. 10 is a conceptual diagram showing an example of an S / N ratio distribution of reflected waves. FIG. 11 is a conceptual diagram showing an example of a reception intensity distribution of reflected waves. FIG. 12 is a conceptual diagram showing an example of a method for calculating denotation information. FIG. 13 is an explanatory diagram showing an example of a display of the traffic status of a crosswalk. FIG. 14 is a road plan view showing an example of a traffic light control system. FIG. 15 is an explanatory diagram showing an example of an indication table. FIG. 16 is a flowchart showing an example of pedestrian passage assistance control.

[0006] <Problem to be Solved by the Present Disclosure> Infrastructure-type radio wave sensors such as those described in Patent Document 1 may not be able to identify the number of multiple pedestrians crossing a crosswalk in close proximity. However, even if the number of pedestrians is unknown, if the outer boundary position of the presence range of at least one pedestrian and the pedestrian's speed can be provided to a traffic light controller, it is believed that the sensor can be used for signal control such as pedestrian passage assistance control. In view of the above problem, the present disclosure aims to provide a radio wave sensor that can output information regarding the presence range of an object.

[0007] Effect of the Present Disclosure According to the present disclosure, a radio wave sensor capable of outputting information relating to the range in which an object exists can be obtained.

[0008] <Outline of Embodiments of the Present Disclosure> Below, an outline of embodiments of the present disclosure will be listed and described.

[0009] (1) A device according to one embodiment of the present disclosure is an infrastructure-type radio wave sensor that performs remote sensing using radio waves of a predetermined frequency, and includes a transceiver that transmits the radio waves and receives reflected waves of the radio waves, and a processor that outputs a detection result regarding an object traveling on a road based on the transmitted radio waves and the received reflected waves, and the detection result includes range data that represents the range of existence of at least one of the objects.

[0010] According to the radio wave sensor of this embodiment, the detection result output by the processor includes range data representing the range of existence of at least one object, and therefore, by connecting the radio wave sensor to an external device, information regarding the range of existence of objects passing on the road can be provided to the external device.

[0011] (2) In the radio wave sensor described in (1) above, the range data may include extension information indicating the location of the extension of the presence range at the time the presence range was generated, and the moving speed of the presence range on the road. In this case, for example, the accuracy of the presence range can be confirmed by displaying an image on a display device in which a range icon indicating the extension information of the presence range is superimposed on an actual captured image. Furthermore, for example, in pedestrian passage assistance control, the extension information of the presence range and the moving speed included in the range data can be used to determine whether to extend the green lighting duration or the green flashing duration of a pedestrian traffic light.

[0012] (3) In the radio wave sensor of (1) or (2) above, the detection result may further include specific point data representing a specific point identified as the location of the object. In this way, a radio wave sensor capable of simultaneously outputting both range data and specific point data can be obtained.

[0013] (4) In the radio wave sensor of (3) above, the specific point data may include location information of the specific point at a specific time and a moving speed of the specific point on the road. In this case, for example, the accuracy of the detected position can be confirmed by displaying an image on a display device in which a point icon representing the location of the specific point is superimposed on an actual captured image.

[0014] (5) In the radio wave sensor of (4), the processor may execute a first generation process to generate the range data based on a plurality of the specific point data. In this case, the plurality of specific point data can be used to generate the range data.

[0015] (6) In the radio wave sensor of (5), the first generation process may include a process of generating at least one group based on position information and movement speeds of the plurality of specific points, and a process of calculating the extension information based on the position information of the specific points belonging to the group. In this case, the extension information of the existence range of at least one group including a plurality of specific points having roughly the same position information and movement speed can be calculated.

[0016] (7) In the radio wave sensor according to any one of (1) to (4), the processor may execute a second generation process to generate the range data based on the signal-to-noise ratio distribution of the reflected waves and the reception intensity distribution of the reflected waves. In this case, the range data can be generated without using specific point data.

[0017] (8) In the radio wave sensor of (7), the second generation process may include a process of determining a range in the distance direction in which the maximum value of the S / N ratio distribution can be reduced and a range in the azimuth angle direction in which the maximum value of the reception intensity distribution can be reduced, and a process of calculating the extensional information based on the range in the distance direction and the range in the azimuth angle direction. In this case, extensional information of a presence range extending in the distance direction and the azimuth angle direction can be calculated from the position of the maximum value that can be detected as an object.

[0018] (9) The terminal device of this embodiment is a terminal device that communicates with the radio wave sensor described in (4) above, and includes a graphics controller that outputs a captured image of a crosswalk, and a display device that displays the output captured image, and the graphics controller superimposes a range icon, which is an icon representing the descriptive information of the presence range, on the captured image.

[0019] According to the terminal device of this embodiment, the graphics controller superimposes a range icon, which is an icon representing the descriptive information of the existence range, onto the captured image of the crosswalk, so that the accuracy of the existence range can be confirmed based on whether or not an actual object (e.g., a pedestrian) is included in the range icon.

[0020] (10) In the terminal device of (9) above, when a plurality of range data having the same generation time are acquired, the graphic controller may superimpose a plurality of range icons corresponding to the plurality of range data on the captured image. In this way, it is possible to check whether the grouping by the radio wave sensor is appropriate based on the positional relationship of the range icons displayed simultaneously.

[0021] (11) In the terminal device of (9) or (10) above, the graphic controller may further superimpose a point icon representing the position of the specific point on the captured image. In this way, the accuracy of object detection can be confirmed based on the degree of deviation between an actual object (e.g., a pedestrian) and the point icon.

[0022] (12) The traffic light controller of this embodiment is a traffic light controller that communicates with any of the radio wave sensors (2) to (8) described above, and includes a memory unit that stores control information that defines the light colors of the traffic lights at an intersection for each level, and a control unit that switches the light colors of the traffic lights based on the control information, wherein the traffic lights include vehicle traffic lights and pedestrian traffic lights, and the control unit performs passage assistance control for pedestrians crossing the crosswalk based on the range data.

[0023] According to the traffic light controller of this embodiment, the control unit executes traffic assistance control for pedestrians crossing the crosswalk based on the range data, so the range data output by the radio wave sensor can be effectively used for traffic light control at the intersection. Furthermore, because radio wave sensors are not easily affected by brightness or weather, traffic light control with better weather resistance can be realized compared to when surveillance cameras are used.

[0024] (13) In the traffic light controller of (12), the passage assistance control may include a process of extending the green lighting time or the green flashing time of the pedestrian signal light if the trailing edge of the denotation information is located inside the crosswalk when the pedestrian signal light starts to light red. In this way, even if an elderly person or a disabled person with a slow walking speed is within the range of presence, the pedestrian can be assisted to complete the crosswalk.

[0025] (14) In the traffic light controller of (12) or (13), the passage assistance control may include a process of shortening the extended green light duration or flashing green light duration when the leading end of the denotation information indicating that the speed remains zero for a predetermined period of time or more is outside the crosswalk. This makes it possible to suppress adverse effects on traffic flow at adjacent intersections that may be caused by leaving the green light duration or flashing green light duration of the pedestrian signal lamp extended.

[0026] (15) A method according to one aspect of the present disclosure is a detection method performed by the radio wave sensors described above in (1) to (8). Therefore, the detection method has the same effects as the radio wave sensors described above in (1) to (8).

[0027] (16) A computer program according to one aspect of the present disclosure is a computer program for causing a computer to function as the radio wave sensor described above in (1) to (8). Therefore, the computer program has the same effects as the radio wave sensors described above in (1) to (8).

[0028] The present disclosure can be realized not only as a system and device having the above-described characteristic configuration, but also as a program for causing a computer to execute such characteristic configuration. Furthermore, the present disclosure can be realized as a semiconductor integrated circuit that realizes part or all of the system and device.

[0029] <Details of the embodiments of the present disclosure> Hereinafter, the details of the embodiments of the present disclosure will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any manner.

[0030] [Installation of Radio Wave Sensor] Fig. 1 is a perspective view showing an example of a portion of an intersection 70 where a radio wave sensor 10 is installed. The intersection 70 illustrated in this embodiment is, for example, a crossroads intersection where a roadway 60 and a roadway 65 intersect (see Fig. 2). In this embodiment, the roadways 60, 65 (e.g., roadways in Japan) are used for left-hand traffic, but the technology disclosed in this embodiment, such as the radio wave sensor 10, can also be applied to roadways for right-hand traffic.

[0031] 1, the radio wave sensor 10 of this embodiment is a sensor that performs remote sensing using radio waves of a predetermined frequency. Specifically, the radio wave sensor 10 is a millimeter-wave radar. Therefore, the predetermined frequency may be, for example, 24 GHz, 60 GHz, 76 GHz, or 79 GHz.

[0032] There are two types of radio wave sensors: "mobile type" sensors mounted on moving objects such as vehicles, and "infrastructure type" sensors installed on road structures 50. As shown in the figure, the radio wave sensor 10 of this embodiment is a radio wave radar for traffic monitoring that detects objects (pedestrians, bicycles, vehicles, etc.) present in a detection area 30 on the road side, and is attached to a structure 50 installed on the road. Therefore, the radio wave sensor 10 of this embodiment is a type of infrastructure type radio wave sensor 10, but in the following, the infrastructure type radio wave sensor 10 will be abbreviated as "radio wave sensor 10."

[0033] The structure 50 includes a pole 51 and an arm 52 protruding from the top of the pole 51, and the radio wave sensor 10 is attached to the arm 52. This allows the radio wave sensor 10 to be installed several meters above ground. The radio wave sensor 10 detects people passing by on the crosswalk 20 (for example, pedestrians and cyclists) by emitting radio waves (millimeter waves) from a height of several meters above ground toward the crosswalk 20 and receiving reflected waves.

[0034] Specifically, the radio wave sensor 10 detects the distance from its antenna to an object on the road, the horizontal angle (also called the "azimuth angle") of the direction connecting its antenna to the object, and the speed of the object. The horizontal angle (azimuth angle) of the object is the horizontal angle with respect to a predetermined reference direction (for example, the normal direction to the radio wave irradiation surface of the radio wave sensor 10).

[0035] The speed of an object directly detected by the radio wave sensor 10 is the speed in the distance direction from the radio wave sensor 10 to the object. Therefore, the speed of an object moving toward or away from the radio wave sensor 10 is detected, but the speed of an object moving perpendicular to the distance direction is not detected.

[0036] The radio wave sensor 10 sets a detection area 30, which is an area on the road where an object can be detected. The detection area 30 is included within a radio wave irradiation range 40 of the radio wave sensor 10, which covers the entire detection area 30. In order to monitor the traffic conditions at the crosswalk 20, the radio wave sensor 10 normally sets a detection area 30 that includes the entire crosswalk 20.

[0037] The radio wave irradiation range 40 is a range in which an object reflects radio waves irradiated by the radio wave sensor 10 and the object can be detected by the radio wave sensor 10 based on the waves reflected from the object. The range does not include a range in which the radio wave sensor 10 cannot detect an object even if it can irradiate radio waves. However, the radio wave irradiation range 40 is not limited to this range and may be the entire range in which the radio wave sensor 10 can irradiate radio waves.

[0038] The crosswalk 20 is provided on a roadway 60 near an intersection 70. The intersection 70 in Fig. 1 is a point where one roadway 60 intersects with another roadway 65, and sidewalks 63a, 63b are provided adjacent to both sides of the roadway 60. The roadway 60 includes oncoming lanes 61a, 61b through which vehicles enter the intersection 70 and outgoing lanes 62a, 62b through which vehicles exit the intersection 70.

[0039] The oncoming lane 61a is a lane for going straight and turning left. Therefore, a vehicle traveling on the oncoming lane 61a in the x1 direction as shown in the figure either goes straight through the intersection 70 or turns left (changing its direction of travel in the y1 direction as shown in the figure) to enter the roadway 65. The oncoming lane 61b is a lane for going straight and turning right. Therefore, a vehicle traveling on the oncoming lane 61b in the x1 direction as shown in the figure either goes straight through the intersection 70 or turns right (changing its direction of travel in the y2 direction as shown in the figure) to enter the roadway 65.

[0040] The outgoing lane 62a is entered by vehicles traveling straight on the roadway 60 in the illustrated direction x2 and passing through the intersection 70, and by vehicles traveling on the roadway 65 in the illustrated direction y1 and turning left at the intersection 70. In addition, vehicles traveling on the roadway 65 in the illustrated direction y2 may turn right at the intersection 70 and enter the outgoing lane 62a. The outgoing lane 62b is entered by vehicles traveling straight on the roadway 60 in the illustrated direction x2 and passing through the intersection 70, and by vehicles traveling on the roadway 65 in the illustrated direction y2 and turning right at the intersection 70. In addition, vehicles may turn left from direction y1 to direction x2 and enter the oncoming lane 62b.

[0041] As shown in Figure 1, an intersection 70 is equipped with vehicle signal lights 1 that indicate whether vehicles traveling on roadways 60, 65 have the right of way, and pedestrian signal lights 2 that indicate whether pedestrians and other passersby on a crosswalk 20 have the right of way. The intersection 70 is also equipped with a signal controller 300 that supplies power to each of the signal lights 1, 2 and determines the timing for changing the light color of each of the signal lights 1, 2. The hardware configuration of the signal controller 300 will be described later.

[0042] [Detection Area of ​​Radio Wave Sensor] Fig. 2 is a road plan view showing an example of the detection area of ​​the radio wave sensor 10. As shown in Fig. 2, the detection area 30 includes a zebra area 31, which is a traffic area, and waiting areas 32a and 32b where passersby (pedestrians, cyclists, etc.) wait to pass. The waiting areas 32a and 32b are provided on both sides of the detection area 30 in the longitudinal direction (the width direction of the roadway 60). In the illustrated example, the waiting area 32a is located on the sidewalk 63a adjacent to the incoming lane 61a, and the waiting area 32b is located on the sidewalk 63b adjacent to the outgoing lane 62a.

[0043] 2, arc-shaped corner cuttings 61c, 62c are provided at the junction between the roadways 60 and 65. Specifically, the corner cutting 61c exists at the junction between the oncoming lane 61a and 65, and the corner cutting 62c exists at the junction between the outgoing lane 62a and 65. The widthwise range of the zebra area 31 extends from the straight portion of the roadway 60 to partway between the corner cuttings 61c, 62c. In other words, the widthwise range of the zebra area 31 overlaps with part of the corner cuttings 61c, 62c.

[0044] Boundary line 33a between zebra area 31 and waiting area 32a has a shape that follows the boundary line between incoming lane 61a and sidewalk 63a, and includes a straight portion parallel to incoming lane 61a and an inclined portion corresponding to corner cutting 61c. Boundary line 33b between zebra area 31 and waiting area 32b has a shape that follows the boundary line between outgoing lane 62a and sidewalk 63b, and includes a straight portion parallel to outgoing lane 62a and an inclined portion corresponding to corner cutting 62c.

[0045] [Coordinate Systems of the Radio Wave Sensor] A "polar coordinate system" and a "plane coordinate system" are defined for the radio wave sensor 10. The polar coordinate system is a coordinate system that defines the position of an object by the distance from the antenna 106a of the radio wave sensor 10 and the azimuth angle of the object as seen from the antenna 106a of the radio wave sensor 10. The reference line of the azimuth angle (the line of angle 0) is the intersection line between the ground and a vertical plane that includes the radio wave emission axis of the radio wave sensor 10 (the normal direction of the radio wave emission surface of the radio wave sensor 10). Hereinafter, a position specified by the distance and azimuth angle in the polar coordinate system will be referred to as a "polar position."

[0046] The plane coordinate system is an orthogonal coordinate system that defines the position of an object using two orthogonal horizontal axes (X-axis and Y-axis) on the ground surface, with the origin being a position vertically below the radio wave sensor 10 (installation position). Similar to the reference line for the azimuth angle, the Y-axis is the intersection line between the ground and a vertical plane containing the radio wave emission axis of the radio wave sensor 10 (the normal direction of the radio wave emission surface of the radio wave sensor 10). Hereinafter, a position specified by XY coordinate values ​​in the plane coordinate system will be referred to as a "plane position."

[0047] The radio wave sensor 10 is installed on-site so that its reference line (Y-axis) is parallel to the direction of travel of the crosswalk 20, and the delineation information 111 of the detection area 30, defined by its planar position, is pre-registered in the radio wave sensor 10. The position of a detected object is output in the form of planar position data. The detection area 30 is set by a traffic manager or the like using a management terminal 200, such as a laptop PC, communicatively connected to the radio wave sensor 10. If, during on-site installation, it is determined that the reference line and the direction of travel of the crosswalk are not parallel, the direction of the reference line is calibrated, for example, by software installed on the management terminal 200.

[0048] [Hardware Configuration of Radio Wave Sensor] Fig. 3 is a block diagram showing an example of the hardware configuration of the radio wave sensor 10. As shown in Fig. 3, the radio wave sensor 10 includes a processor 101, a non-volatile memory 102, a volatile memory 103, a transmitter / receiver 104, and a communication interface (I / F) 107.

[0049] The volatile memory 103 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 102 is, for example, a flash memory, a hard disk, or a ROM (Read Only Memory). The non-volatile memory 102 stores extension information 111 of the detection area 30. The extension information 111 is information that represents the planar position of the extension of the detection area 30. If the detection area 30 is rectangular, for example, the planar positions of the four vertices of the rectangle may be used as the extension information 111.

[0050] The non-volatile memory 102 stores a control program 110 and data used to execute the control program 110. The functions of the radio wave sensor 10 are realized by the processor 101 executing the control program 110. The control program 110 can be stored in a recording medium such as a flash memory, a ROM, or a CD-ROM. The control program 110 includes a computer program that causes the processor 101 to execute the detection process (FIG. 6) described below.

[0051] The processor 101 is, for example, a CPU (Central Processing Unit). However, the processor 101 is not limited to a CPU. The processor 101 may also be a GPU (Graphics Processing Unit). The processor 101 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 the same processing as the control program 110.

[0052] The transmitter / receiver 104 includes a transmitter circuit 105 and a receiver circuit 106. The transmitter circuit 105 includes a transmitter antenna 105a. While FIG. 3 illustrates an example in which only one transmitter antenna 105a is provided, multiple transmitter antennas 105a may be provided. The transmitter circuit 105 generates a modulated wave (radio wave) of a predetermined frequency and transmits the generated modulated wave from the transmitter antenna 105a. When the transmitted modulated wave hits an object (e.g., a pedestrian, a bicycle, a vehicle, etc.), a portion of the modulated wave becomes a reflected wave.

[0053] The receiving circuit 106 includes multiple receiving antennas 106a. That is, multiple (four in the figure) receiving antennas 106a are provided to detect the azimuth angle of an object. The receiving circuit 106 performs signal processing on the received reflected wave to generate reflected wave data. The generated reflected wave data is provided to the processor 101. The processor 101 analyzes the reflected wave data to detect the position (distance and azimuth angle) and speed of the object.

[0054] The communication interface 107 is a communication module for communicating with an external device (for example, at least one of the management terminal 200 and the signal controller 300). The communication method with the external device may be wired or wireless, or may be via a network. The communication interface 107 transmits, for example, detection result data to the management terminal 200 and the signal controller 300. The communication interface 107 receives, from the management terminal 200, the denotation information 111 generated by the management terminal 200.

[0055] [Hardware Configuration of Management Terminal] Fig. 4 is a block diagram showing an example of the hardware configuration of the management terminal 200. The management terminal 200 is a terminal device used for setting the detection area 30, displaying detection results, etc. As shown in Fig. 4, the management terminal 200 includes a processor 201, non-volatile memory 202, volatile memory 203, an input / output interface (I / F) 204, a graphics controller 205, a communication interface (I / F) 206, an input device 211, and a display device 212.

[0056] The input device 211 and the display device 212 may be external devices that can be connected to dedicated ports attached to the housing of the management terminal 200. The volatile memory 203 is, for example, a semiconductor memory such as an SRAM or a DRAM. The non-volatile memory 202 is, for example, a flash memory, a hard disk, or a ROM.

[0057] The non-volatile memory 202 stores a control program 210 and data used to execute the control program 210. The functions of the management terminal 200 are realized by the processor 201 executing the control program 210. The control program 210 can be stored in a recording medium such as a flash memory, a ROM, or a CD-ROM. The control program 210 includes a computer program for calibrating the denotation information 111 of the detection area 30, and a computer program for image processing that superimposes the detection results of the radio wave sensor 10 on digital images.

[0058] The processor 201 is, for example, a CPU. However, the processor 201 is not limited to a CPU. The processor 201 may be a GPU. The processor 201 may be, for example, an ASIC, or a programmable logic device such as a gate array or FPGA. In this case, the ASIC or programmable logic device is configured to be able to execute the same processing as the control program 210.

[0059] The input device 211 includes a keyboard and a pointing device such as a mouse. The input device 211 may be a capacitive or pressure-sensitive touchpad overlaid on the screen of the display device 212. The input device 211 is used for input operations to the management terminal 200. The input / output interface 204 is connected to the input device 211. The input / output interface 204 receives input data from the input device 211 and provides the received data to the processor 201.

[0060] The display device 212 includes, for example, a liquid crystal panel or an OEL (organic electroluminescence) panel. The display device 212 is capable of displaying characters, figures, and digital images. The graphics controller 205 is connected to the display device 212 and controls the display on the display device 212. The graphics controller 205 includes, for example, a GPU and a VRAM (Video RAM), stores data to be displayed on the display device 212 in the VRAM, periodically reads one frame of video data from the VRAM, and generates a video signal.

[0061] The generated video signal is output to the display device 212, whereby the video is displayed on the display device 212. The function of the graphics controller 205 may be included in the processor 201. A portion of the area of ​​the volatile memory 203 may be used as a VRAM. The graphics controller is capable of compositing digital video, and generates a video in which a predetermined icon is superimposed on video including the crosswalk 20 captured by a surveillance camera (not shown), for example. The display device 212 outputs the generated composite image.

[0062] The communication interface 206 is a communication module for communicating with an external device (e.g., the radio wave sensor 10). The communication method with the external device may be wired or wireless, or may be via a network. The communication interface 206 transmits the denotation information 111 generated by the processor 101 in the setting process to the radio wave sensor 10. The communication interface 206 receives detection result data from the radio wave sensor 10.

[0063] [Hardware Configuration of Signal Controller] Fig. 5 is a block diagram showing an example of the hardware configuration of the signal controller 300. As shown in Fig. 5, the signal controller 300 includes a control unit 301, a storage unit 302, a communication interface (I / F) 303, and a lamp drive unit 304. The control unit 301 is connected to the storage unit 302, the communication interface 303, and the lamp drive unit 304 via an internal bus. The control unit 301 controls the operation of each of these units.

[0064] The control unit 301 is an arithmetic processing unit including a processor such as a CPU and a main memory which is a volatile memory. The control unit 301 loads a control program 305 stored in the storage unit 302 into the memory and performs various information processing in accordance with the loaded control program 305. The storage unit 302 is configured with a nonvolatile memory such as a flash memory and a hard disk, and stores control information for signal control (for example, the indication table TA in FIG. 15 ) and the control program 305.

[0065] The communication interface 303 is a communication module for communicating with roadside sensors such as the radio wave sensor 10. The communication method with the roadside sensor may be either wireless or wired. In the case of the signal controller 300 that is remotely controlled by the central device of the traffic control center, the communication interface 303 is also equipped with a communication module for realizing the communication function with the central device.

[0066] The control program 305 includes a computer program for signal control that determines the timing of turning on and off the vehicle signal lights 1 and the pedestrian signal lights 2. The control unit 301 determines the timing of switching the signal light color in one cycle based on predefined control information (aspect table TA), and outputs a switching signal to the light drive unit 304 when the current time reaches the determined timing.

[0067] The lamp driver 304 includes a semiconductor relay (not shown). The semiconductor relay of the lamp driver 304 turns on or off the power to the lights included in the signal lamps 1 and 2 in accordance with a switching signal input from the control unit 301. The control unit 301 is capable of executing pedestrian passage assistance control ( FIG. 16 ) based on the detection results received from the radio wave sensor 10. The passage assistance control will be described in detail later.

[0068] [Detection Process by Radio Wave Sensor] Fig. 6 is a flowchart showing an example of detection process executed by the processor 101 of the radio wave sensor 10. The detection process of Fig. 6 is executed by the processor 101 of the radio wave sensor 10 at predetermined control intervals (for example, every 100 ms).

[0069] 6, the processor 101 first executes a "reflected wave data generation process" (step S101). This generation process includes the following processes 1 to 3. Process 1: The modulated wave signal input from the transmitting circuit 105 and the reflected wave signal input from the receiving circuit 106 are combined to generate an intermediate frequency signal (hereinafter referred to as an "IF signal").

[0070] Process 2: A fast Fourier transform (FFT) is performed on the IF signal to calculate the polar position (distance and azimuth angle) of the reflected wave. Process 3: Based on the calculated polar position, reflected wave data is generated. The reflected wave data includes waveform data related to distance and waveform data related to azimuth angle.

[0071] Next, the processor 101 executes "object position and velocity identification process" (step S102). This identification process includes the following processes 4 to 6. Process 4: In the waveform data of the reflected wave, a peak point where the waveform height exceeds a predetermined value is identified as an object. Hereinafter, a peak point identified as an object from the reception intensity is referred to as a "identified point."

[0072] Process 5: Based on the polar position of the peak point, calculate the planar position (XY coordinate values) of the peak point. The calculated planar position is set as the position of the specific point (object). Process 6: Calculate the velocity of the specific point (object) from the phase difference of multiple IF signals corresponding to the chirp signal.

[0073] Next, the processor 101 executes an "object tracking process" (step S103). This tracking process includes the following processes 7 and 8. Process 7: If a specific point (object) that appears in the current cycle was not detected in the previous cycle, identification information (ID) is assigned to the specific point (object) in the current cycle. Process 8: For specific points (objects) whose positions have already been identified in the previous cycle, the identification information is retained. Identity is identified by an estimation process using the movement direction and speed.

[0074] Next, the processor 101 executes a "range data generation process" (step S104). "Range data" refers to data that represents the range of existence of at least one object (e.g., a pedestrian crossing the crosswalk 20). When there is one object, the range of existence is, for example, a range within a circle whose radius is a predetermined planar distance from the center of the object (e.g., the standard shoulder width of a human being) (hereinafter referred to as the "circular range"). When there are multiple objects, the range of existence is, for example, a range within a predetermined area that can encompass all of the multiple objects (hereinafter referred to as the "inclusion range"). Specific examples of the range data generation process (FIGS. 7 and 9) will be described later.

[0075] Next, the processor 101 executes a "detection result output process" (step S105). This output process generates a communication frame including the detection result and causes the communication interface 107 to transmit the generated communication frame. The destination of the communication frame includes, for example, at least one of the management terminal 200 and the signal controller 300. The detection result of the radio wave sensor 10 also includes at least one of the above-mentioned "specific point data" and "range data."

[0076] Specific point data is data that expresses a specific point that can be considered as the location of an object as a concept of a point. In this embodiment, for example, the peak point of the reflected wave is taken as the specific point. The specific point data can be composed of, for example, the following information: Information 1: Position information of the specific point (plane coordinate system) Information 2: Travel speed of the specific point on the road Information 3: Identification information of the specific point (for example, an identification number) Information 4: Specific time of the specific point (absolute time or relative time)

[0077] As described above, range data is data that expresses the existence range (the above-mentioned circular range or inclusive range) of at least one object (peak point of reflected waves) as a plane, and can be composed of, for example, the following information 5 to 8. Note that the "extension information" of information 5 is information that indicates the planar position of the extension of the existence range. Information 5: Extension information of the existence range (planar coordinate system; position only or position and length) Information 6: Travel speed on roads in the existence range Information 7: Identification information of the existence range (e.g., identification number) Information 8: Generation time of the existence range (absolute time or relative time)

[0078] Since the velocity can be calculated by dividing the difference in position by the difference in time, the specific point data may be data that omits either information 2 or information 4. For the same reason, the range data may be data that omits either information 6 or information 8.

[0079] [First Generation Process of Presence Range] Figure 7 is a flowchart showing an example of a process for generating range data (first generation process) executed by the processor 101 of the radio wave sensor 10. The first generation process of Figure 7 is one type of generation process that can be employed in step S104 in the detection process of Figure 6. Therefore, the first generation process of Figure 7 is also executed at predetermined control intervals (for example, every 100 milliseconds).

[0080] As shown in Fig. 7, the processor 101 first collects point cloud data for the current cycle (step S204). The "point cloud data" refers to a plurality of specific point data obtained by the "object position and velocity identification process" (step S102 in Fig. 6) for the current cycle. Next, the processor 101 groups the point cloud data HD (step S202). Fig. 8 is a conceptual diagram showing an example of the point cloud data HD. The meanings of the variables in Fig. 8 are as follows:

[0081] V: Velocity axis of the object (peak point of the reflected wave) X: X axis of the plane coordinate system Y: Y axis of the plane coordinate system di: Specific point data (i is an identification number; for example, i = 1, 2, etc.) Gj: Group including specific point data di (j is an identification number; for example, j = 1, 2, etc.)

[0082] The grouping in step S202 is a process of dividing a plurality of specific point data di included in the point cloud data HD of the current cycle into at least one group having similar planar positions (XY coordinate values) and velocities V. A predetermined clustering algorithm is used for the grouping. Examples of the predetermined clustering algorithm that can be adopted include the shortest distance method, the group average method, and the k-means method.

[0083] 8 illustrates an example in which the point cloud data HD for the current cycle is divided into group G1 including specific point data d1, d2, d3, d4, d5, d6, and d7, group G2 including specific point data d8, d9, d10, d11, and d12, and group G3 including groups d12, d13, d14, d15, d16, and d17. As illustrated, groups G1 and G2 are above the zero velocity plane, and group G3 is below the zero velocity plane. This is because groups G1 and G2, whose velocity V is positive, are moving away from the radio wave sensor 10, and group G3, whose velocity V is negative, is moving toward the radio wave sensor 10.

[0084] 7, the processor 101 determines whether one or more groups Gj exist (step S203). If the result of the determination is negative, the processor 101 ends the process. If the result of the determination is positive, the processor 101 repeats, for each group Gj, the process of calculating denotation information of the existence range from the specific point data di belonging to the group Gj (step S204) and the process of creating range data (step S205).

[0085] The calculation of extension information (step S204) is a process of calculating extension information of the existence range that includes all of the specific point data di included in one group Gj based on the planar positions (XY coordinate values) of the specific point data di. The shape of the existence range may be various shapes, such as a rectangle, a polygon with five or more sides, or an ellipse. When a rectangle is used, the following extension information may be used, for example, based on the maximum values ​​Xmax, Ymax and minimum values ​​Xmin, Ymin of the planar positions of the multiple specific point data di included in the group Gj.

[0086] Extension information 1: Extension information that defines a rectangle with the following four vertices: First vertex: (Xmin, Ymin) Second vertex: (Xmin, Ymax) Third vertex: (Xmax, Ymin) Fourth vertex: (Xmax, Ymax)

[0087] Extension information 2: Extension information that defines a rectangle with the following one vertex and two distances: First vertex: (Xmin, Ymin) First distance: Distance between two sides in the X direction (=Xmax-Xmin) Second distance: Distance between two sides in the Y direction (=Ymax-Ymin)

[0088] In the above-mentioned denotational information 1, a predetermined margin may be added to at least one of the first vertex to the fourth vertex. Similarly, in the denotational information 2, a predetermined margin may be added to at least one of the first vertex, the first distance, and the second distance. Employing such a margin has the advantage of allowing the shape or size of the denotational information 1 or the denotational information 2 to be adjusted according to the sensor sensitivity. Furthermore, depending on how the margin is set, the shape of the denotational information 1 or the denotational information 2 may be a shape other than a rectangle, such as a trapezoid.

[0089] When a polygon is used, for example, a predetermined algorithm is used to convert all of the specific point data di in the group Gj into a mesh, and the outer periphery of the mesh is used as the existence range. As the predetermined algorithm, for example, a "Ball-Pivoting Algorithm" or the like can be used. When an ellipse is used, for example, the minimum minor axis and major axis that can encompass all of the specific point data di and are centered on the center of gravity of the position information of all of the specific point data di in the group Gj are used as the extension information of the existence range.

[0090] The creation of range data (step S205) is a process of associating the movement speed of the existence range, the identification information of the existence range, and the generation time of the existence range with the extension information of the existence range. For example, the following speeds can be used as the movement speed of the existence range: Speed ​​V1: The movement speed of one specific point data di arbitrarily selected from within the group Gj Speed ​​V2: The representative value (average or median) of the movement speeds of the specific point data di within the group Gj

[0091] The identification information of the existence range is assigned, for example, each time the number of specific point data dj that constitutes the group Gj changes. Therefore, if the number of specific point data dj that constitutes the group Gj is the same as in the previous cycle, the identification information of the existence range of the group Gj is carried over to the current cycle.

[0092] [Second Generation Process of Presence Range] Figure 9 is a flowchart showing another example of the range data generation process (second generation process) executed by the processor 101 of the radio wave sensor 10. The second generation process of Figure 9 is one type of generation process that can be used in step S104 of the detection process of Figure 6. Therefore, the second generation process of Figure 9 is also executed at predetermined control intervals (for example, 100 ms).

[0093] As shown in Fig. 9, the processor 101 first extracts the maximum value SNmax of the S / N ratio from the S / N ratio distribution SD of the reflected wave (step S301). Fig. 10 is a conceptual diagram showing an example of the S / N ratio distribution SD of the reflected wave. The meanings of the variables in Fig. 10 are as follows, except for variables that have already been explained.

[0094] ΔB: distance sampling unit (for example, approximately the same length as the distance resolution) Bk: distance axis of the object (however, a discrete value calculated by Bk = k × ΔB) k: natural number equal to or greater than 1 SN: axis of the SN ratio of the object (reflection point) SNk: SN ratio value at distance Bk Br: blur range in the distance direction SNmax: maximum value of the SN ratio in the SN ratio distribution SD THs: SN ratio threshold that can be reduced from the maximum value SNmax

[0095] The extraction in step S301 is a process of searching for the maximum value SNmax of the S / N ratio based on, for example, the S / N ratio distribution SD of the reflected wave on the distance-velocity plane shown in Fig. 10. Next, the processor 101 determines a blur range Br in the distance direction based on the extracted maximum value SNmax (step S302). The "blur range Br in the distance direction" refers to the range in the distance direction in which an object can be detected even if the maximum value SNmax of the S / N ratio is reduced by a predetermined threshold value THs.

[0096] Specifically, the processor 101 extracts a plurality of points Qm (m=1, 2, ...) on the distribution that satisfy the following inequality (1), and sets the range of distance Bk corresponding to the extracted points Qm as the blur range Br. SNk≧SNmax−THs (1) For example, as shown in FIG. 10 , if the correspondence between points Qm (m=1, 2, ...) on the distribution that satisfy inequality (1) and distance Br is as follows, the processor 101 sets the range from B11 corresponding to point Q1 to points Q5 to B15 as the blur range Br.

[0097] (Correspondence between Qm and Bk) Distance Bk of point Q1 = B11 Distance Bk of point Q2 = B12 Distance Bk of point Q3 = B13 Distance Bk of point Q4 = B14 Distance Bk of point Q5 = B15

[0098] Next, the processor 101 extracts the maximum value Pmax of the reception intensity from the reception intensity distribution PD of the reflected wave (step S303). Fig. 11 is a conceptual diagram showing an example of the reception intensity distribution PD. The meanings of the variables in Fig. 11 are as follows, except for variables that have already been explained.

[0099] θ: Azimuth angle relative to the reference direction P: Reception strength of reflected waves (dB) Pmax1: First maximum value of reception strength Pmax2: Second maximum value of reception strength θr: Blur range in azimuth angle direction θa: Azimuth angle with a smaller angle value at which the reception strength is equal to or less than (Pmax1-THp) θb: Azimuth angle with a larger angle value at which the reception strength is equal to or less than (Pmax1-THp) THp: Threshold of reception strength that can be reduced from the maximum values ​​Pmax1 and Pmax2

[0100] 11, the reception intensity distribution PD includes the following five distributions. Distribution PD1: Two-dimensional distribution of reception intensity at distance B11 with azimuth angle θ as the horizontal axis Distribution PD2: Two-dimensional distribution of reception intensity at distance B12 with azimuth angle θ as a variable Distribution PD3: Two-dimensional distribution of reception intensity at distance B13 with azimuth angle θ as a variable Distribution PD4: Two-dimensional distribution of reception intensity at distance B14 with azimuth angle θ as a variable Distribution PD5: Two-dimensional distribution of reception intensity at distance B15 with azimuth angle θ as a variable

[0101] The processing of steps S303 and S304 will be described below using distribution PD3 at distance B13 as an example. However, the processor 101 performs similar processing for the other distributions PD1, PD2, PD4, and PD5. The extraction in step S303 is processing to search for the maximum value Pmax of the reception intensity based on the reception intensity distribution PD on the distance-azimuth angle plane shown in Fig. 11. Fig. 11 shows a case where distribution PD3 for distance B13 is sorted in the azimuth angle θ direction, and two maximum values ​​Pmax1 and Pmax2 are obtained.

[0102] Next, the processor 101 determines a blurring range θr in the azimuth direction based on the extracted maximum value Pmax1 (step S304). The "blurring range θr in the azimuth direction" refers to the range in the azimuth direction in which an object can be detected even if the maximum value Pmax1 of the reception intensity distribution PD is reduced by a predetermined threshold THp.

[0103] Specifically, the processor 101 searches for a smaller azimuth angle θa and a larger azimuth angle θb in the distribution PD3 where the reception strength is equal to or less than (Pmax1-THp), and determines the range that satisfies the following inequality (2) as the blurring range θr: θa≦θr≦θb (2) Although Fig. 11 illustrates the blurring range θr for the first maximum value Pmax1, a similar blurring range θr is also determined for the second maximum value Pmax2.

[0104] Next, the processor 101 calculates the denotation information of the existence range based on the two blur ranges Br and θr (step S305). Fig. 12 is a conceptual diagram showing an example of a method for calculating the denotation information. The meanings of the variables in Fig. 12 are as described above.

[0105] The calculation of the denotation information (step S305) is a process of calculating denotation information of the existence range that includes, for example, all of the following starting points θa and ending points θb: The starting point θa and ending point θb of the blur range θr at distance B11; The starting point θa and ending point θb of the blur range θr at distance B12; The starting point θa and ending point θb of the blur range θr at distance B13; The starting point θa and ending point θb of the blur range θr at distance B14; The starting point θa and ending point θb of the blur range θr at distance B15.

[0106] The shape of the existence range can be various shapes, such as a rectangle, a polygon with five or more sides, an ellipse, etc. For example, as shown in Figure 12, when a rectangle is used, the above-mentioned extension information 1 and extension information 2 can be used, which are based on the maximum values ​​Xmax, Ymax and minimum values ​​Xmin, Ymin of the planar positions of the starting point θa and the ending point θb.

[0107] When a polygon is used, for example, a polygon formed by the following multiple line segments may be used as the existence range. Line segment 1: A line segment connecting a start point θa and an end point θb at a distance B11 Line segment 2: A line segment connecting start points θa adjacent to each other in the distance direction Line segment 3: A line segment connecting end points θb adjacent to each other in the distance direction Line segment 4: A line segment connecting start points θa and end points θb at a distance B15

[0108] When an ellipse is used, for example, the center of gravity of all the starting points θa and ending points θb is set as the center, and the minimum minor axis and major axis that can include all the starting points θa and ending points θb are used as the extension information of the existence range.

[0109] Next, the processor 101 creates range data (step S306). Creating range data (step S306) is a process of associating the movement speed of the existence range, the identification information of the existence range, and the generation time of the existence range with the extension information of the existence range. The movement speed of the existence range is the speed at the maximum value SNmax in the S / N ratio distribution SD (FIG. 10). The identification information of the existence range is assigned, for example, each time a presence range is generated. Therefore, in the case of the same reflection point as in the previous cycle, the identification information of the existence range is carried over.

[0110] 13 is an explanatory diagram showing an example of a display of the traffic status of the crosswalk 20 that can be displayed on the display device 212 of the management terminal 200. The display example of Fig. 13 is an image in which the graphic controller 205 of the management terminal 200 adds data extracted from the detection results received from the radio wave sensor 10 to an image of the crosswalk 20 captured by a surveillance camera.

[0111] As described above, the detection results of the radio wave sensor 10 include at least one of "specific point data" that represents a specific point that identifies a peak point of the reception strength as the location of an object, and "range data" that represents the range of the location of at least one object (peak point). The display example in Figure 13 is an example of a display in which both the specific point data and the range data are superimposed. The displayed objects in this case include the following images and icons.

[0112] Hi (i is an identification number): An image of an actual pedestrian acquired from a surveillance camera. Hereinafter referred to as "actual pedestrian Hi". Fj (j is an identification number): An icon representing the position of a specific point output by the radio wave sensor 10. Hereinafter referred to as "point icon Fj". Ak (k is an identification number): An icon representing the descriptive information of the existence range (a rectangle in the illustrated example) output by the radio wave sensor 10. Hereinafter referred to as "range icon Ak".

[0113] 13 , when a plurality of specific point data having the same specific time are acquired, the graphic controller 205 superimposes a plurality of point icons Fj corresponding to the plurality of specific point data on the captured image. Similarly, when a plurality of range data having the same generation time are acquired, the graphic controller 205 superimposes a plurality of range icons Ak corresponding to the plurality of range data on the captured image.

[0114] In Figure 13, "P" indicates the installation location of the radio wave sensor 10, and the arrow extending from the range icon Ak indicates the direction of travel of the presence range. In the display example of Figure 13, the following correspondence relationships are recognized between the actual pedestrian Hi and the point icon Fj. Correspondence relationship 1: H1, H2, H3 correspond one-to-one to F1, F2, F3. Correspondence relationship 2: One F4 exists near H4, H5, and H6. Correspondence relationship 3: One F5 exists near H7 and H8.

[0115] Furthermore, the following correspondence relationships are recognized between actual pedestrians Hi and range icons Ak. Correspondence relationship 4: There exists A1 that includes H1 and H2. A1 moves in the positive direction of the Y axis. Correspondence relationship 5: There exists A2 that includes H3. A2 moves in the negative direction of the Y axis. Correspondence relationship 6: There exists A3 that includes H4, H5, H6, H7, and H8. A3 moves in the negative direction of the Y axis.

[0116] As shown in Correspondence Relationships 1 to 3, the point icon Fj representing a specific point may be able to distinguish a single pedestrian (Correspondence Relationship 1), but may not be able to distinguish between multiple pedestrians who are crowded together (Correspondence Relationships 2 and 3). This is thought to be because the radio wave sensor 10, which is made up of millimeter-wave radar, does not have a high resolution compared to a surveillance camera. Therefore, it is not advisable to use the radio wave sensor 10 for the purpose of counting pedestrians.

[0117] As shown in correspondence relationships 4 to 6, the range icon Ak representing the presence range surrounds a group of pedestrians passing in the same direction at approximately the same speed (correspondence relationship 4 and opposite relationship 6), while surrounding a pedestrian passing alone with a wider area (correspondence relationship 5). In this way, in the case of the range icon Ak, it is almost certain that at least one actual pedestrian Hi is present inside. Therefore, if range data is used as trigger information for pedestrian passage assistance control ( FIG. 16 ), it is believed that passage assistance control can be applied even if individual pedestrians cannot be identified.

[0118] 13, superimposing the dot icon Fj and the range icon Ak on the image of the crosswalk 20 including the actual pedestrian Hi has the following advantages: Advantage 1: The accuracy of object detection by the radio wave sensor 10 can be confirmed based on the degree of deviation between the actual pedestrian Hi and the dot icon Fj.

[0119] Advantage 2: Depending on whether or not the actual pedestrian Hi is included in the range icon Ak, it is possible to confirm the accuracy of the presence range generated by the radio wave sensor 10. Advantage 3: When multiple range icons Ak are displayed simultaneously, it is possible to confirm whether or not the grouping logic of the radio wave sensor 10 is functioning properly.

[0120] 14 is a road plan view showing an example of a signal control system 400. Here, the intersection 70 controlled by the signal controller 300 is assumed to be a crossroads intersection where roads in a first direction (e.g., east-west) and a second direction (e.g., north-south) intersect.

[0121] 14, the signal control system 400 includes a plurality of vehicle signal lights 1A, 1B, a plurality of pedestrian signal lights 2A, 2B, a signal controller 300 provided on the sidewalk, and the above-mentioned radio wave sensor 10 that communicates with the signal controller 300. Hereinafter, when the vehicle signal lights 1A, 1B and the pedestrian signal lights 2A, 2B are collectively referred to as "signal lights 1, 2."

[0122] Vehicle signal light 1A indicates whether or not vehicles moving in a first direction (east-west) have the right of way. Pedestrian signal light 2A indicates whether or not pedestrians on crosswalk 20 moving in the first direction (east-west) have the right of way. Vehicle signal light 1B indicates whether or not vehicles moving in a second direction (north-south) have the right of way. Pedestrian signal light 2B indicates whether or not pedestrians on crosswalk 20 moving in the second direction (north-south) have the right of way.

[0123] In the signal control system 400 of this embodiment, a plurality of (for example, four) of the radio wave sensors 10 described above are installed. These installation positions are assumed to be, for example, the following points: Point P1: Point at a sidewalk corner on the southeast side of the intersection 70 Point P2: Point at a sidewalk corner on the northeast side of the intersection 70 Point P3: Point at a sidewalk corner on the northwest side of the intersection 70 Point P4: Point at a sidewalk corner on the southwest side of the intersection 70

[0124] The radio wave sensor 10 at point P1 has a detection area 30 that is the crosswalk 20 on the east side, where the direction of travel is the second direction (north-south). The radio wave sensor 10 at point P2 has a detection area 30 that is the crosswalk 20 on the north side, where the direction of travel is the first direction (east-west). The radio wave sensor 10 at point P3 has a detection area 30 that is the crosswalk 20 on the west side, where the direction of travel is the second direction (north-south). The radio wave sensor 10 at point P4 has a detection area 30 that is the crosswalk 20 on the south side, where the direction of travel is the first direction (east-west).

[0125] Therefore, the signal controller 300 of this embodiment can receive range data related to pedestrians on all crosswalks 20 included in the intersection 70 from multiple radio wave sensors 10. The memory unit 302 of the signal controller 300 stores the Y coordinate values ​​of the edges in the direction of travel of all crosswalks 20 included in the intersection 70. These edges of the crosswalks 20 are used to determine whether the range of an object's existence has completely crossed the crosswalk 20.

[0126] [Indication Table Used for Signal Control] Figure 15 is an explanatory diagram showing an example of an indication table TA stored in the memory unit 302 of the signal controller 300. In Figure 15, a straight line represents "green light on," a dotted line represents "green flashing," a wavy line represents "yellow light on," and a double line represents "red light on." The indication table TA is a type of control information that defines the light colors of the signal lamps 1 and 2 for each stage Ji (i = 1 to 11). The control unit 301 of the signal control 300 switches the light colors of the signal lamps 1 and 2 as the stage in the indication table TA progresses.

[0127] The total number of stairs Ji in the display table TA (11 in the illustrated example) is just an example, and in the case of an intersection that includes a right-turn arrow light or the like, the total number of stairs may exceed 11. Also, in the case of an intersection that has a crosswalk 20 in only one direction, the total number of stairs may be less than 11. Therefore, the total number of stairs may be more than 11 or less than 11. For example,

[0128] In the case of the aspect table TA in Figure 15, the control unit 301 sets all signal lamps 1 and 2 to red (all red) at stairway J1, and sets pedestrian signal lamp 2A and vehicle signal lamp 1A to green and pedestrian signal lamp 2B and vehicle signal lamp 1B to red at stairway J2. At stairway J3, the control unit 301 sets pedestrian signal lamp 2A to flashing green, vehicle signal lamp 1A to green, and pedestrian signal lamp 2B and vehicle signal lamp 1B to red. At stairway J4 to J11, the light colors of signal lamps 1 and 2 are similarly switched according to the aspect table TA.

[0129] The display table TA defines a "holding time in seconds" that indicates the lighting time or flashing time. The total value of the holding time in seconds for all steps Ji (i = 1 to 11) is called one cycle time, and after the last step J10, the cycle returns to the first step J1 and repeats. The "variable step" circle in the display table TA means that the lighting time or flashing time can be extended or shortened. The "reception step" circle means that this is the period during which a decision to extend or shorten the lighting time or flashing time is accepted.

[0130] 16 is a flowchart showing an example of pedestrian passage assistance control executed by the control unit 301 of the signal controller 300. As shown in Fig. 16, the control unit 301 of the signal controller 300 first determines whether range data has been received from the radio wave sensor 10 (step ST11).

[0131] If the determination result in step ST11 is positive, the control unit 301 determines whether the current time point when the range data was received is the reception level (step ST12). Specifically, the control unit 301 determines whether the current level is level J2 or level J8. If the determination result in step ST12 is negative, the control unit 301 returns the process to before step ST11. If the determination result in step ST12 is positive, the control unit 301 determines the "progression level of the existence range" based on the range data (step ST14).

[0132] The "degree of progression of the presence range" includes any of the following states 1 to 3: a) State 1 (smooth): If the average speed of the current presence range (for example, the average value over two seconds) continues, the rear end of the extension information of the presence range will be located closer to the sidewalk than the edge of the crosswalk 20 (i.e., outside the crosswalk 20) ​​at the start of Step 4 or Step 10 (when the pedestrian signal light starts to turn red).

[0133] b) State 2 (Delay): If the average speed of the current existence range (e.g., the average value over 2 seconds) continues, at the start of Step 4 or Step 10 (when the pedestrian signal light starts to turn red), the rear end of the existence range's extension information will be located closer to the roadway than the edge of the crosswalk 20 (i.e., inside the crosswalk 20).

[0134] c) State 3 (Stopped): The leading end of the denotational information of the range of existence where zero speed continues for a predetermined time (for example, 4 seconds) or more is closer to the sidewalk than the edge of the crosswalk 20 (i.e., outside the crosswalk 20). Note that the "rear end of the denotational information" is the Y coordinate value of the denotational information on the rear side in the direction of travel, and the "leading end of the denotational information" is the Y coordinate value of the denotational information on the front side in the direction of travel.

[0135] When the control unit 301 receives multiple range data, it executes the above-described progress degree determination (step ST14) for the different denotation information included in the multiple range data. If the progress degrees of all the presence ranges are "state 1," the control unit 301 returns the process to before step ST11 without extending the hold time. This is because in this case, it is estimated that all the presence ranges will be able to cross the crosswalk 20 without extending the hold time (green light duration) for step J2 or step J8.

[0136] If the progress degree of at least one existence range is "State 2", the control unit 301 extends the number of seconds to be held for staircase J2 or staircase J8 and returns the process to before step ST11. That is, the control unit 301 adds a predetermined countable value (e.g., 10 seconds) to the current number of seconds to be held for staircase J2 or staircase J8, and updates the number of seconds to be held for staircase J2 or staircase J8. The number of seconds to be held for the staircase J2 or staircase J8 may be extended for staircase J3 or staircase J9, which causes the pedestrian signal lamps 2A and 2B to flash green.

[0137] By extending the above-mentioned holding time (the green lighting time or the green flashing time of the pedestrian signal lamps 2A, 2B), even if an elderly person or a disabled person who walks slowly is within the range of their presence, it is possible to help such a pedestrian to complete crossing the crosswalk 20.

[0138] If the progress degree of all the presence ranges is "State 3," it can be assumed that there are no pedestrians intending to cross the crosswalk 20, for example, because they are waiting for a traffic light. Also, if the determination result in step ST11 is negative, it can be assumed that there are no pedestrians at the intersection 70. In this case, the control unit 301 determines whether the hold time has already been extended (step ST13). The reason is that if there are no pedestrians crossing the crosswalk 20, it is acceptable to cancel the extension of the hold time in preparation for the next cycle or later.

[0139] If the determination result of step ST13 is positive, the control unit 301 shortens the hold time for the stairs J2, J3, J8, or J9 (step ST16), and returns the process to before step ST11. In this way, it is possible to prevent the negative impact on traffic flow at adjacent intersections caused by leaving the hold time for the variable stairs extended.

[0140] If the determination result in step ST13 is negative, the process returns to before step ST11 without shortening the number of seconds to be held. Note that in the signal control system 400 of Fig. 14, the pedestrian passage assistance control (Fig. 16) may be performed only in either the first direction or the second direction, for example, by subjecting only the pedestrian signal lamp 2A in the first direction with the shorter green illumination time (step J2) to the passage assistance control.

[0141] [Other Modifications] The embodiments disclosed herein are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and includes meanings equivalent to the claims and all modifications within the scope of the claims.

[0142] In the above-described embodiment, the detection result output by the radio wave sensor 10 does not need to be both specific point data and range data, and only range data may be output. In the above-described embodiment, the radio wave sensor 10 may be configured as two physically separated devices, for example, by separating the housing into one housing containing the transceiver 104 and the other housing containing the processor 101 and the communication interface 107.

[0143] DESCRIPTION OF SYMBOLS 1, 1A, 1B Vehicular signal light device 2, 2A, 2B Pedestrian signal light device 10 Radio wave sensor 20 Crosswalk 30 Detection area 31 Zebra area 32a, 32b Waiting area 33a, 33b Boundary line 40 Radio wave irradiation range 50 Structure 51 Pole 52 Arm 63a, 63b Sidewalk 60, 65 Roadway 61a, 61b Entering lane 62a, 62b Exiting lane 61c, 62c Corner cutting 70 Intersection 101 Processor 102 Non-volatile memory 103 Volatile memory 104 Transmitting / receiving unit 105 Transmitting circuit 106 Receiving circuit 105a Transmitting antenna 106a Receiving antenna 107 Communication interface (communication I / F) 110 Control program 111 Denotation information 200 Management terminal (terminal device) 201 Processor 202 Non-volatile memory 203 Volatile memory 204 Input / output interface (I / O) 205 Graphic controller 206 Communication interface (communication I / F) 210 Control program 211 Input device 212 Display device 300 Signal controller 301 Control unit 302 Storage unit 303 Communication interface (communication I / F) 304 Light unit drive unit 305 Control program 400 Signal control system Hi Actual pedestrian Fj Point icon Ak Range icon TA Display table (control information)

Claims

1. An infrastructure-type radio wave sensor that performs remote sensing using radio waves of a specified frequency, comprising: a transceiver unit that transmits the radio waves and receives the reflected waves of the radio waves; and a processor that outputs detection results regarding objects passing on a road based on the transmitted radio waves and the received reflected waves, wherein the detection results include range data that expresses the presence range of at least one of the objects.

2. The radio wave sensor according to claim 1, wherein the range data includes extension information indicating the position of the extension of the presence range at the time when the presence range was generated, and the travel speed of the presence range on the road.

3. The radio wave sensor according to claim 1 or 2, wherein the detection result further includes specific point data expressing a specific point identified as the location of the object.

4. The radio wave sensor according to claim 3, wherein the specific point data includes location information of the specific point at a specific time and a moving speed of the specific point on the road.

5. The radio wave sensor according to claim 3 or 4, wherein the processor executes a first generation process for generating the range data based on a plurality of the specific point data.

6. The radio wave sensor of claim 5, wherein the first generation process includes: a process of generating at least one group from position information and moving speeds of a plurality of the specific points; and a process of calculating the extension information based on the position information of the specific points belonging to the group.

7. A radio wave sensor as described in any one of claims 1 to 4, wherein the processor executes a second generation process to generate the range data based on the signal-to-noise ratio distribution of the reflected wave and the reception intensity distribution of the reflected wave.

8. The radio wave sensor described in claim 7, wherein the second generation process includes: a process of determining a distance range in which the maximum value of the S / N ratio distribution can be reduced, and an azimuth range in which the maximum value of the reception intensity distribution can be reduced; and a process of calculating the extension information based on the distance range and the azimuth range.

9. A terminal device that communicates with the radio wave sensor described in claim 4, comprising: a graphics controller that outputs a captured image of a pedestrian crossing; and a display device that displays the output captured image, wherein the graphics controller superimposes a range icon, which is an icon representing the descriptive information of the existence range, on the captured image.

10. The terminal device according to claim 9, wherein when a plurality of range data having the same generation time are acquired, the graphic controller superimposes a plurality of range icons respectively corresponding to the plurality of range data on the captured image.

11. The terminal device according to claim 9 or 10, wherein the graphic controller further superimposes a point icon, which is an icon representing the position of the specific point, on the captured image.

12. A traffic light controller that communicates with a radio wave sensor described in any one of claims 2 to 8, comprising: a memory unit that stores control information that defines the light colors of traffic lights at an intersection for each stage; and a control unit that switches the light colors of the traffic lights based on the control information, wherein the traffic lights include vehicle traffic lights and pedestrian traffic lights, and the control unit performs passage assistance control for pedestrians crossing the crosswalk based on the range data.

13. A traffic signal controller as described in claim 12, wherein the traffic assistance control includes a process of extending a green lighting time or a flashing green lighting time of the pedestrian signal light when the rear end of the denotation information is located inside the crosswalk at the time when the pedestrian signal light starts to turn red.

14. A traffic light controller as described in claim 12 or claim 13, wherein the traffic assistance control includes a process of shortening the extended green light time or flashing green light time when the leading end of the denotation information in which zero speed continues for a predetermined period of time or more is outside the crosswalk.

15. A detection method performed by an infrastructure-type radio wave sensor that performs remote sensing using radio waves of a predetermined frequency, comprising the steps of transmitting the radio waves and receiving reflected waves of the radio waves, and outputting a detection result regarding an object passing on a road based on the transmitted radio waves and the received reflected waves, wherein the detection result includes range data that represents the presence range of at least one of the objects.

16. A computer program for causing a computer to function as an infrastructure-type radio wave sensor that performs remote sensing using radio waves of a specified frequency, the computer program comprising: a step of transmitting the radio waves and receiving the reflected waves of the radio waves; and a step of outputting a detection result regarding an object passing on a road based on the transmitted radio waves and the received reflected waves, the detection result including range data that expresses the existence range of at least one of the objects.

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