Sensor synchronization system and sensor synchronization method

Abstract

To provide a technique for enabling synchronization of timing to start measurement between a plurality of sensors.SOLUTION: A sensor synchronization system 1 includes: a first sensor 10 for generating first point group information; a first controller 11; a second sensor 20 for generating second point group information; and a second controller 21. The first controller 11 has: a first control section 12 for recording a first start time; and a first analysis section 13 for recording a first reception time when the first point group information is acquired first. The second controller 21 has: a second control section 22 for recording a second start time; a second analysis section 23 for recording a second reception time when the second point group information is acquired first; a calculation section 25 for calculating a delay time between the first sensor 10 and the second sensor 20; and an adjustment section 26 for instructing a stop of measurement in the first sensor 10 and the second sensor 20, instructing a start of measurement in one delaying sensor, and instructing a start of measurement of the other sensor by deviating the delay time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a sensor synchronization system and method. [Background technology]

[0002] There is a known technology for synthesizing the measurement results of multiple sensors. Patent Document 1 discloses a technology for performing coordinate alignment processing between sensors in a sensor system equipped with multiple distance measurement sensors. The technology described in Patent Document 1 performs coordinate alignment processing between sensors by converting the detection coordinates of each sensor using the trajectory of a moving object moving within a detection target area. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-106475 A Summary of the Invention [Problem to be solved by the invention]

[0004] There may be delays or operational variations within the device between the multiple sensors, which may result in differences in the timing at which measurements are started between the multiple sensors.

[0005] An object of the present disclosure is to provide a technique capable of synchronizing the timing of starting measurement among multiple sensors. [Means for solving the problem]

[0006] A sensor synchronization system according to one aspect of the present disclosure includes a first sensor that measures a monitoring range and generates first point cloud information, a first controller that controls the measurement of the first sensor, a second sensor that measures the monitoring range and generates second point cloud information, and a second controller that controls the measurement of the second sensor. The first controller has a first control unit that starts the measurement of the first sensor and records a first start time that is the start time of the measurement of the first sensor, and a first analysis unit that acquires the first point cloud information and records a first reception time when the first point cloud information was initially acquired. The second controller has a second control unit that starts measurement by the second sensor and records a second start time which is the start time of measurement by the second sensor; a second analysis unit that acquires second point cloud information and records a second reception time when the second point cloud information was first acquired; a calculation unit that calculates a delay time between the first sensor and the second sensor using the difference between the first start time and the first reception time and the difference between the second start time and the second reception time; and an adjustment unit that instructs the first sensor and the second sensor to stop measurement, instructs the start of measurement by one of the first sensor and the second sensor that is delayed, and instructs the start of measurement by the other sensor by shifting the delay time.

[0007] A sensor synchronization method according to one aspect of the present disclosure is performed by a sensor synchronization system including a first sensor that measures a monitoring range and generates first point cloud information, a first controller that controls the measurement of the first sensor, a second sensor that measures the monitoring range and generates second point cloud information, and a second controller that controls the measurement of the second sensor. The sensor synchronization method includes the steps of starting measurement of a first sensor and recording a first start time which is the start time of the measurement of the first sensor, starting measurement of a second sensor and recording a second start time which is the start time of the measurement of the second sensor, acquiring first point cloud information and recording a first reception time when the first point cloud information was first acquired, acquiring second point cloud information and recording a second reception time when the second point cloud information was first acquired, calculating a delay time between the first sensor and the second sensor using the difference between the first start time and the first reception time and the difference between the second start time and the second reception time, instructing to stop measurement of the first sensor and the second sensor, and instructing to start measurement of one of the first sensor and the second sensor which is delayed, and instructing to start measurement of the other sensor by shifting the delay time.

[0008] In the sensor synchronization system and the sensor synchronization method according to one aspect of the present disclosure, a first start time when the measurement of the first sensor is started and a first reception time when the first point cloud information is first acquired from the first sensor are recorded. Also, a second start time when the measurement of the second sensor is started and a second reception time when the second point cloud information is first acquired from the second sensor are recorded. Then, a delay time between the first sensor and the second sensor is calculated from the difference between the first start time and the first reception time and the difference between the second start time and the second reception time. The measurements of the first sensor and the second sensor are stopped, and the measurements of the first sensor and the second sensor are started at a timing shifted by the delay time. This makes it possible to correct the shift between the first sensor and the second sensor by the delay time. As a result, the timing of starting measurement can be synchronized between a plurality of sensors.

[0009] A sensor synchronization system according to one aspect of the present disclosure includes a first sensor that measures a monitoring range and generates first point cloud information, a first controller that controls the measurement of the first sensor, a second sensor that measures the monitoring range and generates second point cloud information, a second controller that controls the measurement of the second sensor, and a terminal that accepts an input of reference coordinates that indicate the coordinate position of a reference object that is a specific object present in the monitoring range. The first controller has a first control unit that starts the measurement of the first sensor and records a first start time that is the start time of the measurement of the first sensor, and a first analysis unit that acquires the first point cloud information and records a first reference coordinate time at which coordinates that approximate the reference coordinates are detected using the first point cloud information. The second controller has a second control unit that starts measurement by the second sensor and records a second start time that is the start time of the measurement by the second sensor; a second analysis unit that acquires second point cloud information and records a second reference coordinate time at which a coordinate approximating the reference coordinate is detected using the second point cloud information; a calculation unit that calculates a delay time between the first sensor and the second sensor using the difference between the first start time and the first reference coordinate time and the difference between the second start time and the second reference coordinate time; and an adjustment unit that instructs the first sensor and the second sensor to stop measurement, instructs one of the first sensor and the second sensor to start measurement that is delayed, and instructs the other sensor to start measurement by shifting the delay time.

[0010] A sensor synchronization method according to one aspect of the present disclosure is executed by a sensor synchronization system including a first sensor that measures a monitoring range and generates first point cloud information, a first controller that controls the measurement of the first sensor, a second sensor that measures the monitoring range and generates second point cloud information, a second controller that controls the measurement of the second sensor, and a terminal that accepts input of reference coordinates indicating the coordinate position of a reference object, which is a specific object present in the monitoring range. The sensor synchronization method includes the steps of starting measurement of a first sensor and recording a first start time which is the start time of the measurement of the first sensor, starting measurement of a second sensor and recording a second start time which is the start time of the measurement of the second sensor, acquiring first point cloud information and using the first point cloud information to record a first reference coordinate time at which coordinates approximating the reference coordinates are detected, acquiring second point cloud information and using the second point cloud information to record a second reference coordinate time at which coordinates approximating the reference coordinates are detected, calculating a delay time between the first sensor and the second sensor using a difference between the first start time and the first reference coordinate time and a difference between the second start time and the second reference coordinate time, instructing to stop measurement of the first sensor and the second sensor, and instructing to start measurement of one of the first sensor and the second sensor which is delayed, and shifting the delay time to start measurement of the other sensor.

[0011] In the sensor synchronization system and the sensor synchronization method according to one aspect of the present disclosure, a first start time when the measurement of the first sensor is started and a first reference coordinate time when the coordinates approximating the input reference coordinates are detected using the first point cloud information are recorded. Also, a second start time when the measurement of the second sensor is started and a second reference coordinate time when the coordinates approximating the reference coordinates are detected using the second point cloud information are recorded. Then, a delay time between the first sensor and the second sensor is calculated from the difference between the first start time and the first reference coordinate time and the difference between the second start time and the second reference coordinate time. The measurements of the first sensor and the second sensor are stopped, and the measurements of the first sensor and the second sensor are started at a timing shifted by the delay time. This makes it possible to correct the shift between the first sensor and the second sensor by the delay time. As a result, the timing of starting measurement can be synchronized between a plurality of sensors. Effect of the Invention

[0012] According to the present disclosure, it is possible to provide a technique capable of synchronizing the timing of starting measurement among a plurality of sensors. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a sensor synchronization system according to the first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing an example of an arrangement of a plurality of sensors. [Diagram 3] FIG. 3 is a sequence diagram showing an example of the operation of the sensor synchronization system according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating a schematic configuration of a sensor synchronization system according to the second embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of a screen displaying the first point cloud information. [Figure 6] FIG. 6 is a diagram showing an example of a screen displaying the second point cloud information. [Figure 7] FIG. 7 is a diagram showing an example of the first reference coordinate time. [Figure 8] FIG. 8 is a diagram illustrating an example of a hardware configuration related to the system. [Figure 9] FIG. 9 is a diagram illustrating an example of a hardware configuration related to the sensor synchronization system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated description will be omitted.

[0015] [First embodiment] FIG. 1 is a diagram illustrating a schematic configuration of a sensor synchronization system 1 according to a first embodiment. The sensor synchronization system 1 synchronizes the timing of starting measurement among multiple sensors. In the first embodiment, the multiple sensors start scanning from a common origin position. Each of the multiple sensors monitors a monitoring range. The monitoring range is an area to be monitored. Examples of the monitoring range include, but are not limited to, intersections, junctions, and roads. The measurement results of the multiple sensors can be combined and used.

[0016] The sensor synchronization system 1 includes a first sensor 10, a second sensor 20, a first controller 11, and a second controller 21. The first sensor 10 and the first controller 11 are connected to each other by wire or wireless communication. The second sensor 20 and the second controller 21 are connected to each other by wire or wireless communication. The first controller 11 and the second controller 21 are connected to each other by a communication line N. The communication line N may be either wired or wireless. The communication line N may be a non-dedicated line such as an Internet line or a mobile communication network, or may be a dedicated line. In the sensor synchronization system 1, each device performs time synchronization using NTP (Network Time Protocol) or the like. That is, the times inside the first sensor 10, the second sensor 20, the first controller 11, and the second controller 21 are synchronized.

[0017] The first sensor 10 is a device that measures a monitoring range and generates first point cloud information. The first sensor 10 is, for example, a LiDAR (Light Detection And Ranging) sensor or a three-dimensional laser radar (3DLR). The first sensor 10 has a first monitoring range that monitors a part or the whole of the monitoring range. The first monitoring range is a range in which the first sensor 10 can irradiate a laser. The first sensor 10 irradiates a laser beam toward the first monitoring range. The first sensor 10 receives reflected light of the laser beam and generates first point cloud information. The first point cloud information is a collection of measurement point information within the first monitoring range. The measurement point information includes time information and position information.

[0018] The second sensor 20 is a device that measures the monitoring range and generates second point cloud information. The second sensor 20 has a configuration similar to that of the first sensor 10. The second sensor 20 has a second monitoring range that monitors a part or all of the monitoring range. The second monitoring range is a range in which the second sensor 20 can irradiate a laser. The second monitoring range overlaps with a part or all of the first monitoring range. The second sensor 20 irradiates a laser light toward the second monitoring range. The second sensor 20 receives reflected light of the laser light and generates second point cloud information. The second point cloud information is a collection of measurement point information within the second monitoring range.

[0019] In one example, the first sensor 10 and the second sensor 20 are 3DLRs. In this case, the first sensor 10 and the second sensor 20 each include a swing mirror for performing laser scanning. The swing mirror returns to an origin position before starting measurement. The origin position of the swing mirror is common between the first sensor 10 and the second sensor 20. In contrast, the swing center position of the swing mirror is different between the first sensor 10 and the second sensor 20. Therefore, the time from the origin position to the actual start of scanning is different between the first sensor 10 and the second sensor 20. That is, a delay time may occur between the first sensor 10 and the second sensor 20.

[0020] The first controller 11 is a device that controls the measurement of the first sensor 10. The first controller 11 includes a first control unit 12, a first analysis unit 13, and a first communication unit 14 as functional elements.

[0021] The first control unit 12 controls the measurement of the first sensor 10. The first control unit 12 starts the measurement of the first sensor 10. The first control unit 12 records a first start time, which is the start time of the measurement, in a predetermined storage device. For example, the first start time is the time when the first control unit 12 transmits a control signal to the first sensor 10 to start the measurement of the first sensor 10. The first control unit 12 stops the measurement of the first sensor 10.

[0022] The first analysis unit 13 acquires the first point cloud information from the first sensor 10. The first analysis unit 13 records the first reception time when the first point cloud information is acquired for the first time in a predetermined storage device. For example, the first reception time is the time when the first analysis unit 13 first receives the first point cloud information transmitted from the first sensor 10 after the measurement of the first sensor 10 is started. The first analysis unit 13 determines the first measurement point information in the first point cloud information. For example, the first analysis unit 13 determines the first measurement point information based on the serial number of each measurement point information, the angle information in the measurement point information being the end of the angle of view, or the presence of a value in the measurement point information, etc.

[0023] The first communication unit 14 transmits and receives information to and from the second controller 21. The first communication unit 14 transmits a first start time and a first reception time to the second controller 21. The first communication unit 14 receives a start signal or a stop signal, which will be described later, from the second controller 21.

[0024] The second controller 21 is a device that controls the measurement of the second sensor 20. The second controller 21 includes a second control unit 22, a second analysis unit 23, a second communication unit 24, a calculation unit 25, and an adjustment unit 26 as functional elements.

[0025] The second control unit 22 controls the measurement of the second sensor 20. The second control unit 22 starts the measurement of the second sensor 20. The second control unit 22 records a second start time, which is the start time of the measurement, in a predetermined storage device. For example, the second start time is the time when the second control unit 22 transmits a control signal to start the measurement of the second sensor 20. The second control unit 22 stops the measurement of the second sensor 20.

[0026] The second analysis unit 23 acquires the second point cloud information from the second sensor 20. The second analysis unit 23 records the second reception time when the second point cloud information is first acquired in a predetermined storage device. For example, the second reception time is the time when the second analysis unit 23 first receives the second point cloud information from the second sensor 20 after the measurement of the second sensor 20 is started. The second analysis unit 23 determines the first measurement point information in the second point cloud information. For example, the second analysis unit 23 determines the first measurement point information based on the serial number of each measurement point information, the angle information in the measurement point information being the end of the angle of view, or the presence of a value in the measurement point information, etc.

[0027] The second communication unit 24 transmits and receives information to and from the first controller 11. The second communication unit 24 receives a first start time and a first reception time from the first controller 11. The second communication unit 24 transmits a start signal or a stop signal, which will be described later, to the first controller 11.

[0028] The calculation unit 25 calculates the delay time between the first sensor 10 and the second sensor 20. For example, the calculation unit 25 calculates the delay time between the first sensor 10 and the second sensor 20 using the first start time, the first reception time, the second start time, and the second reception time.

[0029] The adjustment unit 26 instructs the first sensor 10 and the second sensor to stop measurement, instructs one of the first sensor 10 and the second sensor 20 that is delayed to start measurement, and instructs the other sensor to start measurement after shifting the delay time. In other words, the adjustment unit 26 shifts the delay time and restarts the measurements of the first sensor 10 and the second sensor 20.

[0030] The adjustment unit 26 outputs a first stop signal to instruct the first sensor 10 to stop the measurement. The second communication unit 24 transmits the first stop signal to the first controller 11. The first control unit 12 of the first controller 11 stops the measurement of the first sensor 10 in accordance with the first stop signal. In addition, the adjustment unit 26 outputs a second stop signal to instruct the second sensor 20 to stop the measurement. The second control unit 22 stops the measurement of the second sensor 20 in accordance with the second stop signal.

[0031] The adjustment unit 26 outputs a first start signal that instructs the first sensor 10 to start measurement. The second communication unit 24 transmits the first start signal to the first controller 11. The first control unit 12 of the first controller 11 starts the measurement of the first sensor 10 in accordance with the first start signal. Furthermore, the adjustment unit 26 outputs a second start signal that instructs the second sensor 20 to start measurement. The second control unit 22 starts the measurement of the second sensor 20 in accordance with the second start signal. The adjustment unit 26 shifts the output timing of the first start signal and the second start signal by a delay time.

[0032] 2 is a schematic diagram showing an example of an arrangement of multiple sensors. The multiple sensors monitor, for example, a rectangular monitoring range R. The monitoring range R is, for example, an intersection. In one example, the sensor synchronization system 1 may monitor the monitoring range R by a first sensor 10 and a second sensor 20.

[0033] In another example, the sensor synchronization system 1 may monitor the monitoring range R with three or more sensors. For example, the sensor synchronization system 1 may include a first sensor 10, a second sensor 20, a third sensor 30, and a fourth sensor 40. The third sensor 30 and the fourth sensor 40 may have a similar configuration to the first sensor 10, for example. The first controller 11 may control the third sensor 30 and the fourth sensor 40. The sensor synchronization system 1 may also include one or more separate controllers that control the third sensor 30 and the fourth sensor 40.

[0034] The first sensor 10, the second sensor 20, the third sensor 30, and the fourth sensor 40 are each fixed to a support member P installed on the ground. The support member P is, for example, a columnar structure installed on the ground at the roadside of a road. The support member P may be a utility pole or a wall of a warehouse. The first sensor 10, the second sensor 20, the third sensor 30, and the fourth sensor 40 may be arranged at positions shifted by 90 degrees from each other. The first sensor 10 and the third sensor 30 may be arranged so as to face each other on a diagonal line of the monitoring range R. The second sensor 20 and the fourth sensor 40 may be arranged so as to face each other on a diagonal line of the monitoring range R. The first controller 11, the second controller 21, and other controllers may be arranged near the corresponding sensors.

[0035] The first sensor 10 has a first monitoring range R1 that monitors part or all of the monitoring range R. The second sensor 20 has a second monitoring range R2 that monitors part or all of the monitoring range R. The third sensor 30 has a third monitoring range R3 that monitors part or all of the monitoring range R. The fourth sensor 40 has a fourth monitoring range R4 that monitors part or all of the monitoring range R. The first monitoring range R1, the second monitoring range R2, the third monitoring range R3, and the fourth monitoring range R4 overlap with each other.

[0036] An example of an operation method (sensor synchronization method) of the sensor synchronization system 1 will be described with reference to Fig. 3. Fig. 3 is a sequence diagram showing an example of the operation of the sensor synchronization system 1 as a process flow M1.

[0037] In the process flow M1, it is assumed that a coordinate system unification process has been performed in advance. For example, the sensor synchronization system 1 unifies the coordinate system of the first sensor 10 and the coordinate system of the second sensor 20 into latitude and longitude. The first sensor 10 and the second sensor 20 each measure the coordinates and latitude and longitude of three or more objects. The three or more objects are located in a monitoring range R. More specifically, the three or more objects are located in both the first monitoring range R1 and the second monitoring range R2. The sensor synchronization system 1 performs coordinate conversion using the measurement results of the first sensor 10 and the measurement results of the second sensor 20.

[0038] In step S1, the sensor synchronization system 1 starts measurements of multiple sensors and records the time when the measurements are started. For example, the first control unit 12 of the first controller 11 starts the measurement of the first sensor 10. The first control unit 12 records the first start time in a predetermined storage device. The second control unit 22 of the second controller 21 starts the measurement of the second sensor 20. The second control unit 22 records the second start time in a predetermined storage device.

[0039] In step S2, the sensor synchronization system 1 acquires point cloud information from multiple sensors and records the reception time when the point cloud information was first acquired. For example, the first analysis unit 13 of the first controller 11 acquires the first point cloud information from the first sensor 10. The first analysis unit 13 records the first reception time when the first point cloud information was first acquired in a predetermined storage device. The second analysis unit 23 of the second controller 21 acquires the second point cloud information from the second sensor 20. The second analysis unit 23 records the second reception time when the second point cloud information was first acquired in a predetermined storage device.

[0040] In step S3, the sensor synchronization system 1 coordinates the first start time and the first reception time. For example, the first communication unit 14 of the first controller 11 transmits the first start time and the first reception time to the second controller 21. The second communication unit 24 of the second controller 21 receives the first start time and the first reception time from the first controller 11.

[0041] In step S4, the sensor synchronization system 1 calculates the delay time between the multiple sensors. For example, the calculation unit 25 of the second controller 21 calculates the delay time between the first sensor 10 and the second sensor 20 using the first start time, the first reception time, the second start time, and the second reception time. More specifically, the calculation unit 25 calculates the delay time using the difference between the first reception time and the first start time, and the difference between the second reception time and the second start time. The delay time can be calculated, for example, using the first sensor 10 as a reference, by the following formula. Delay time = (first reception time - first start time) - (second reception time - second start time)

[0042] In one example, when the delay time based on the first sensor 10 is a positive number, it can be said that the first sensor 10 starts measurement later than the second sensor 20 by the delay time. In other words, it can be said that the second sensor 20 starts measurement earlier than the first sensor 10 by the delay time. In another example, when the delay time based on the first sensor 10 is a negative number, it can be said that the second sensor 20 starts measurement later than the first sensor 10 by the delay time. In other words, it can be said that the first sensor 10 starts measurement earlier than the second sensor 20 by the delay time.

[0043] In step S5, the sensor synchronization system 1 instructs the plurality of sensors to stop measuring. For example, the adjustment unit 26 of the second controller 21 outputs a first stop signal to instruct the first sensor 10 to stop measuring. The second communication unit 24 transmits the first stop signal to the first controller 11. The first communication unit 14 receives the first stop signal from the second controller 21. In addition, the adjustment unit 26 outputs a second stop signal to instruct the second sensor 20 to stop measuring.

[0044] In step S6, the sensor synchronization system 1 stops the measurements of the multiple sensors. For example, the first control unit 12 stops the measurement of the first sensor 10 in response to the first stop signal. The second control unit 22 stops the measurement of the second sensor 20 in response to the second stop signal.

[0045] In step S7, the sensor synchronization system 1 instructs the start of measurement by the multiple sensors. For example, the adjustment unit 26 outputs a first start signal that instructs the start of measurement by the first sensor 10. The second communication unit 24 transmits the first start signal to the first controller 11. The first communication unit 14 receives the first start signal from the second controller 21. In addition, the adjustment unit 26 outputs a second start signal that instructs the start of measurement by the second sensor 20.

[0046] The adjustment unit 26 adjusts the output timing of the first start signal and the second start signal in response to the delay time. In one example, when the first sensor 10 is delayed relative to the second sensor 20, the adjustment unit 26 outputs the second start time by delaying the output of the first start time by the delay time. In another example, when the second sensor 20 is delayed relative to the first sensor 10, the adjustment unit 26 outputs the first start time by delaying the output of the second start time by the delay time.

[0047] In step S8, the sensor synchronization system 1 starts measurements of the multiple sensors. For example, the first control unit 12 starts the measurement of the first sensor 10 in response to a first start signal. Also, the second control unit 22 starts the measurement of the second sensor 20 in response to a second start signal.

[0048] The time when the first sensor 10 starts measurement and the time when the second sensor 20 starts measurement are shifted by the delay time. In one example, when the first sensor 10 lags behind the second sensor 20, the first sensor 10 starts measurement first, and the second sensor 20 starts measurement with a delay of the delay time. In another example, when the second sensor 20 lags behind the first sensor 10, the second sensor 20 starts measurement first, and the first sensor 10 starts measurement with a delay of the delay time.

[0049] The first sensor 10 and the second sensor 20 start measurement in a synchronized state. The first point cloud information and the second point cloud information for the angle of view measured at a predetermined timing can be cut out and combined. By performing measurement in a synchronized state, it becomes possible to measure the same angle of view. This improves the accuracy of combining the first point cloud information and the second point cloud information. Such a combined point cloud improves the measurement accuracy of the monitoring range.

[0050] As described above, the sensor synchronization system 1 according to one aspect of the present disclosure includes a first sensor 10 that measures a monitoring range R and generates first point cloud information, a first controller 11 that controls the measurement of the first sensor 10, a second sensor 20 that measures a monitoring range R and generates second point cloud information, and a second controller 21 that controls the measurement of the second sensor 20. The first controller 11 includes a first control unit 12 that starts the measurement of the first sensor 10 and records a first start time that is the start time of the measurement of the first sensor 10, and a first analysis unit 13 that acquires the first point cloud information and records a first reception time when the first point cloud information was initially acquired. The second controller 21 has a second control unit 22 that starts measurement by the second sensor 20 and records a second start time, which is the start time of measurement by the second sensor 20; a second analysis unit 23 that acquires second point cloud information and records a second reception time when the second point cloud information was first acquired; a calculation unit 25 that calculates the delay time between the first sensor 10 and the second sensor 20 using the difference between the first start time and the first reception time and the difference between the second start time and the second reception time; and an adjustment unit 26 that instructs the first sensor 10 and the second sensor 20 to stop measurement, instructs the start of measurement by one of the first sensor 10 and the second sensor 20 that is delayed, and instructs the start of measurement by the other sensor by shifting the delay time.

[0051] A sensor synchronization method according to one aspect of the present disclosure is executed by a sensor synchronization system 1 including a first sensor that measures a monitoring range and generates first point cloud information, a first controller that controls the measurement of the first sensor, a second sensor that measures the monitoring range and generates second point cloud information, and a second controller that controls the measurement of the second sensor. The sensor synchronization method includes the steps of starting measurement of a first sensor and recording a first start time which is the start time of the measurement of the first sensor, starting measurement of a second sensor and recording a second start time which is the start time of the measurement of the second sensor, acquiring first point cloud information and recording a first reception time when the first point cloud information was first acquired, acquiring second point cloud information and recording a second reception time when the second point cloud information was first acquired, calculating a delay time between the first sensor and the second sensor using the difference between the first start time and the first reception time and the difference between the second start time and the second reception time, instructing to stop measurement of the first sensor and the second sensor, and instructing to start measurement of one of the first sensor and the second sensor which is delayed, and instructing to start measurement of the other sensor by shifting the delay time.

[0052] In the sensor synchronization system 1 and the sensor synchronization method according to one aspect of the present disclosure, a first start time when the measurement of the first sensor 10 is started and a first reception time when the first point cloud information is first acquired from the first sensor 10 are recorded. In addition, a second start time when the measurement of the second sensor 20 is started and a second reception time when the second point cloud information is first acquired from the second sensor 20 are recorded. Then, a delay time between the first sensor 10 and the second sensor 20 is calculated from the difference between the first start time and the first reception time and the difference between the second start time and the second reception time. The measurement of the first sensor 10 and the second sensor 20 is stopped, and the measurement of the first sensor 10 and the second sensor 20 is started at a timing shifted by the delay time. This makes it possible to correct the shift of the first sensor 10 and the second sensor 20 by the delay time. As a result, the timing of starting measurement can be synchronized between multiple sensors.

[0053] [Second embodiment] 4 is a diagram showing a schematic configuration of a sensor synchronization system 1A according to the second embodiment. The sensor synchronization system 1A synchronizes the timing of starting measurement between multiple sensors with different scan start positions or between multiple sensors of different models. The following describes the sensor synchronization system 1A, focusing on differences between the sensor synchronization system 1 according to the first embodiment. The sensor synchronization system 1A includes a first sensor 10A, a second sensor 20A, a first controller 11A, a second controller 21A, and a terminal 50.

[0054] The terminal 50 is one or more computers used by a user of the sensor synchronization system 1A. The terminal 50 is, for example, but not limited to, a personal computer. The terminal 50 is connected to, for example, the first controller 11A and the second controller 21A. The terminal 50 displays the first point cloud information and the second point cloud information on a display device. The terminal 50 accepts input of reference coordinates indicating the coordinate position of a reference object from the first point cloud information and the second point cloud information. The reference object is a specific object present in the monitoring range R. The reference object may be an object that temporarily exists in the monitoring range R. Examples of the reference object include, but are not limited to, a vehicle, a traffic light, or a white line. The reference coordinates are, for example, but are not limited to, the center position of the reference object.

[0055] The first sensor 10A and the second sensor 20A have different scan start positions. In one example, the first sensor 10A and the second sensor 20A have a scan range of 30 degrees in vertical angle of view. The first sensor 10A starts scanning from a vertical angle of view of 0 degrees. The second sensor 20A starts scanning from a vertical angle of view of 10 degrees. In another example, the first sensor 10A and the second sensor 20A are sensors of different models.

[0056] The first controller 11A includes a first analysis unit 13A instead of the first analysis unit 13. The first analysis unit 13A acquires the first point cloud information from the first sensor 10. The first analysis unit 13A records the first reference coordinate time at which the coordinates approximating the reference coordinates are detected in a predetermined storage device using the first point cloud information. For example, the first reference coordinate time is the time at which the first analysis unit 13A detects the coordinates approximating the reference coordinates in the first point cloud information transmitted from the first sensor 10 after the measurement of the first sensor 10A is started. In one example, the first analysis unit 13A determines the time at which the measurement point information of the coordinates closest to the reference coordinates in the first point cloud information is received as the first reference coordinate time. The first communication unit 14 transmits the first start time and the first reference coordinate time to the second controller 21.

[0057] The second controller 21A includes a second analysis unit 23A and a calculation unit 25A instead of the second analysis unit 23 and the calculation unit 25. The second analysis unit 23A acquires the second point cloud information from the second sensor 20. The second analysis unit 23A records the second reference coordinate time at which the coordinates approximating the reference coordinates are detected using the second point cloud information in a predetermined storage device. For example, the second reference coordinate time is the time at which the second analysis unit 23A detects the coordinates approximating the reference coordinates in the second point cloud information transmitted from the second sensor 20 after the measurement of the second sensor 20A is started. In one example, the second analysis unit 23A determines the time at which the measurement point information of the coordinates closest to the reference coordinates in the second point cloud information is received as the second reference coordinate time.

[0058] The calculation unit 25A calculates the delay time between the first sensor 10 and the second sensor 20. For example, the calculation unit 25A calculates the delay time between the first sensor 10 and the second sensor 20 using the first start time, the first reference coordinate time, the second start time, and the second reference coordinate time.

[0059] An example of input of a reference object will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a diagram showing an example of a screen displaying first point cloud information. Fig. 6 is a diagram showing an example of a screen displaying second point cloud information. A screen V1 shown in Fig. 5 and a screen V2 shown in Fig. 6 are displayed on a terminal 50. In the second embodiment, the first sensor 10 and the second sensor 20 are disposed at positions shifted by 90 degrees from each other. Therefore, the first point cloud information and the second point cloud information are also shifted by 90 degrees from each other.

[0060] On the screen V1, the terminal 50 accepts input of reference coordinates C1 from the user. On the screen V1, the reference object indicates a vehicle. The reference coordinates C1 indicate the center position of the reference object. The terminal 50 accepts input from the user specifying the center of the point cloud indicating the reference object in the first point cloud information.

[0061] On screen V2, terminal 50 accepts input of reference coordinates C2 from the user. On screen V2, the reference object indicates a vehicle. The reference object shown on screens V1 and V2 is the same vehicle. The reference coordinates C2 indicate the center position of the reference object. Terminal 50 accepts input from the user specifying the center of the point cloud indicating the reference object among the second point cloud information.

[0062] Fig. 7 is a diagram showing an example of the first reference coordinate time. In Fig. 7, the first point cloud information is shown along the X coordinate and the Y coordinate. The X coordinate corresponds to the horizontal direction of the scan of the first sensor 10. The Y coordinate corresponds to the vertical direction of the scan of the first sensor 10.

[0063] In one example, the first sensor 10 has a vertical angle of view of 30 degrees. 0 degrees is located at the top end in the vertical direction, and 30 degrees is located at the bottom end in the vertical direction. The first sensor 10 scans from the 0 degree position toward the 30 degree position. The first sensor 10 turns back when the scan reaches the 30 degree position. The first sensor 10 scans from the 30 degree position toward the 0 degree position. The first sensor 10 turns back when the scan reaches the 0 degree position. That is, the first sensor 10 scans while turning back in the vertical direction.

[0064] In Fig. 7, the X and Y coordinates of the reference coordinate C1 are (10m, -10m). The X and Y coordinates of the coordinate P1 closest to the reference coordinate C1 are (9.5m, -10.2m). For example, the first analysis unit 13A determines the time when it receives the measurement point information of the coordinate P1 closest to the reference coordinate C1 as the first reference coordinate time. Fig. 7 shows an example of the first reference coordinate time, but the second reference coordinate time can also be determined in a similar manner.

[0065] An example of an operation method (sensor synchronization method) by the sensor synchronization system 1A will be described with reference to Fig. 8. Fig. 8 is a sequence diagram showing an example of the operation of the sensor synchronization system 1A as a process flow M2. The process flow M2 will be described on the assumption that a coordinate system unification process has been performed in advance, similar to the process flow M1.

[0066] In step S11, the sensor synchronization system 1A starts measurement of multiple sensors and records the time when the measurement started. For example, the first control unit 12 of the first controller 11A starts measurement of the first sensor 10A. The first control unit 12 records the first start time in a predetermined storage device. The second control unit 22 of the second controller 21A starts measurement of the second sensor 20A. The second control unit 22 records the second start time in a predetermined storage device.

[0067] In step S12, the sensor synchronization system 1A accepts the input of reference coordinates. For example, the terminal 50 displays a screen V1 shown in Fig. 5 and a screen V2 shown in Fig. 6. In the screen V1, the terminal 50 accepts the input of a reference coordinate C1 from the user. In the screen V2, the terminal 50 accepts the input of a reference coordinate C2 from the user.

[0068] In step S13, the sensor synchronization system 1A acquires point cloud information of a plurality of sensors and records the reference coordinate time when coordinates approximating the reference coordinates are detected. For example, the first analysis unit 13A of the first controller 11A acquires the first point cloud information from the first sensor 10. The first analysis unit 13A uses the first point cloud information to record the first reference coordinate time when coordinates approximating the reference coordinates are detected in a predetermined storage device. The second analysis unit 23A of the second controller 21A acquires the second point cloud information from the second sensor 20. The second analysis unit 23A uses the second point cloud information to record the second reference coordinate time when coordinates approximating the reference coordinates are detected in a predetermined storage device.

[0069] In step S14, the sensor synchronization system 1A coordinates the first start time and the first reference coordinate time. For example, the first communication unit 14 transmits the first start time and the first reference coordinate time to the second controller 21A. The second communication unit 24 of the second controller 21A receives the first start time and the first reference coordinate time from the first controller 11A.

[0070] In step S15, the sensor synchronization system 1A calculates the delay time between the multiple sensors. For example, the calculation unit 25A of the second controller 21A calculates the delay time between the first sensor 10A and the second sensor 20A using the first start time, the first reference coordinate time, the second start time, and the second reference coordinate time. More specifically, the calculation unit 25A calculates the delay time using the difference between the first start time and the first reference coordinate time, and the difference between the second start time and the second reference coordinate time. The delay time can be calculated, for example, by the following formula when the first sensor 10A is used as a reference. Delay time = (1st reference coordinate time - 1st start time) - (2nd reference coordinate time - 2nd start time)

[0071] In one example, when the delay time based on the first sensor 10A is a positive number, it can be said that the first sensor 10A starts measurement later than the second sensor 20A by the delay time. In other words, it can be said that the second sensor 20A starts measurement earlier than the first sensor 10A by the delay time. In another example, when the delay time based on the first sensor 10A is a negative number, it can be said that the second sensor 20A starts measurement later than the first sensor 10A by the delay time. In other words, it can be said that the first sensor 10A starts measurement earlier than the second sensor 20A by the delay time.

[0072] In step S16, the sensor synchronization system 1A instructs the plurality of sensors to stop measuring. For example, the adjustment unit 26 of the second controller 21A outputs a first stop signal that instructs the first sensor 10A to stop measuring. The second communication unit 24 transmits the first stop signal to the first controller 11A. The first communication unit 14 receives the first stop signal from the second controller 21A. In addition, the adjustment unit 26 outputs a second stop signal that instructs the second sensor 20A to stop measuring.

[0073] In step S17, the sensor synchronization system 1A stops the measurements of the multiple sensors. For example, the first control unit 12 stops the first sensor 10A in response to the first stop signal. The second control unit 22 stops the second sensor 20A in response to the second stop signal.

[0074] In step S18, the sensor synchronization system 1A instructs the start of measurement by the multiple sensors. For example, the adjustment unit 26 outputs a first start signal that instructs the start of measurement by the first sensor 10A. The second communication unit 24 transmits the first start signal to the first controller 11A. The first communication unit 14 receives the first start signal from the second controller 21A. In addition, the adjustment unit 26 outputs a second start signal that instructs the start of measurement by the second sensor 20A.

[0075] The adjustment unit 26 adjusts the output timing of the first start signal and the second start signal in response to the delay time. In one example, when the first sensor 10A is delayed compared to the second sensor 20A, the adjustment unit 26 outputs the second start time delayed by the delay time from the output of the first start time. In another example, when the second sensor 20A is delayed compared to the first sensor 10A, the adjustment unit 26 outputs the first start time delayed by the delay time from the output of the second start time.

[0076] The adjustment unit 26 adjusts the output timing of the first start signal and the second start signal in response to the delay time. In one example, when the first sensor 10A is delayed compared to the second sensor 20A, the adjustment unit 26 outputs the second start time delayed by the delay time from the output of the first start time. In another example, when the second sensor 20A is delayed compared to the first sensor 10A, the adjustment unit 26 outputs the first start time delayed by the delay time from the output of the second start time.

[0077] In step S19, the sensor synchronization system 1A starts measurements of the multiple sensors. For example, the first control unit 12 starts the first sensor 10A in response to a first start signal. In addition, the adjustment unit 26 and the second control unit 22 start the second sensor 20A in response to a second start signal.

[0078] The time when the first sensor 10A starts measuring and the time when the second sensor 20A starts measuring are shifted by the delay time. In one example, when the first sensor 10A is delayed from the second sensor 20A, the first sensor 10A starts measuring first, and the second sensor 20A starts measuring after a delay of the delay time. In another example, when the second sensor 20A is delayed from the first sensor 10A, the second sensor 20A starts measuring first, and the first sensor 10A starts measuring after a delay of the delay time.

[0079] In the sensor synchronization system 1A, like the sensor synchronization system 1, it is possible to combine the first point cloud information and the second point cloud information.

[0080] As described above, the sensor synchronization system 1A according to one aspect of the present disclosure includes a first sensor 10 that measures a monitoring range R and generates first point cloud information, a first controller 11 that controls the measurement of the first sensor 10, a second sensor 20 that measures a monitoring range R and generates second point cloud information, a second controller 21 that controls the measurement of the second sensor 20, and a terminal 50 that accepts an input of reference coordinates that indicate the coordinate position of a reference object that is a specific object present in the monitoring range R. The first controller 11 includes a first control unit 12 that starts the measurement of the first sensor 10 and records a first start time that is the start time of the measurement of the first sensor 10, and a first analysis unit 13 that acquires the first point cloud information and records a first reference coordinate time at which a coordinate that approximates the reference coordinate is detected using the first point cloud information. The second controller 21 has a second control unit 22 that starts measurement by the second sensor 20 and records a second start time, which is the start time of the measurement by the second sensor 20; a second analysis unit 23 that acquires second point cloud information and records a second reference coordinate time at which a coordinate approximating the reference coordinate is detected using the second point cloud information; a calculation unit 25 that calculates the delay time between the first sensor 10 and the second sensor 20 using the difference between the first start time and the first reference coordinate time and the difference between the second start time and the second reference coordinate time; and an adjustment unit 26 that instructs the first sensor 10 and the second sensor 20 to stop measurement, instructs the start of measurement by one of the first sensor 10 and the second sensor 20 that is delayed, and instructs the start of measurement by the other sensor by shifting the delay time.

[0081] A sensor synchronization method according to one aspect of the present disclosure is executed by a sensor synchronization system 1A including a first sensor 10 that measures a monitoring range R and generates first point cloud information, a first controller 11 that controls the measurement of the first sensor 10, a second sensor 20 that measures the monitoring range R and generates second point cloud information, a second controller 21 that controls the measurement of the second sensor 20, and a terminal 50 that accepts input of reference coordinates indicating the coordinate position of a reference object, which is a specific object present in the monitoring range R. The sensor synchronization method includes the steps of starting measurement by the first sensor 10 and recording a first start time which is the start time of the measurement by the first sensor 10, starting measurement by the second sensor 20 and recording a second start time which is the start time of the measurement by the second sensor 20, acquiring first point cloud information and using the first point cloud information to record a first reference coordinate time at which coordinates approximating the reference coordinates are detected, acquiring second point cloud information and using the second point cloud information to record a second reference coordinate time at which coordinates approximating the reference coordinates are detected, calculating a delay time between the first sensor 10 and the second sensor 20 using a difference between the first start time and the first reference coordinate time and a difference between the second start time and the second reference coordinate time, instructing the first sensor 10 and the second sensor 20 to stop measuring, and instructing the start of measurement by one of the first sensor 10 and the second sensor 20 which is delayed, and shifting the delay time to instruct the start of measurement by the other sensor.

[0082] In the sensor synchronization system 1A and the sensor synchronization method according to one aspect of the present disclosure, a first start time when the measurement of the first sensor 10A is started and a first reference coordinate time when the coordinates approximating the input reference coordinates are detected using the first point cloud information are recorded. Also, a second start time when the measurement of the second sensor 20 is started and a second reference coordinate time when the coordinates approximating the reference coordinates are detected using the second point cloud information are recorded. Then, a delay time between the first sensor 10A and the second sensor 20A is calculated from the difference between the first start time and the first reference coordinate time and the difference between the second start time and the second reference coordinate time. The measurement of the first sensor 10A and the second sensor 20A is stopped, and the measurement of the first sensor 10A and the second sensor 20A is started at a timing shifted by the delay time. This makes it possible to correct the shift of the first sensor 10A and the second sensor 20A by the delay time. As a result, the timing of starting measurement can be synchronized between a plurality of sensors.

[0083] [Hardware configuration] Fig. 9 is a diagram showing an example of a hardware configuration related to the sensor synchronization system 1, 1A. Fig. 9 shows a computer 100 functioning as the first controllers 11, 11A, the second controllers 21, 21A, and the terminal 50. The computer 100 has a processor 101, a main memory unit 102, an auxiliary memory unit 103, a communication control unit 104, an input device 105, and an output device 106. The first controllers 11, 11A, the second controllers 21, 21A, and the terminal 50 are configured by one or more computers 100 configured by these hardware and software such as programs.

[0084] When the first controllers 11, 11A, the second controllers 21, 21A and the terminal 50 are configured by multiple computers 100, these computers 100 may be connected locally or via a communication network such as the Internet or an intranet.

[0085] The processor 101 is a CPU (Central Processing Unit) that executes an operating system, application programs, and the like. The main memory 102 is composed of a ROM (Read Only Memory) and a RAM (Random Access Memory). The auxiliary memory 103 is a storage medium composed of a hard disk, a flash memory, and the like. The auxiliary memory 103 generally stores a larger amount of data than the main memory 102. The communication control unit 104 is composed of a network card or a wireless communication module. At least a part of the communication function with other devices in the first controller 11, 11A, the second controller 21, 21A, and the terminal 50 may be realized by the communication control unit 104. The input device 105 is composed of a keyboard, a mouse, a touch panel, a microphone for voice input, and the like. The output device 106 is composed of a display, a printer, and the like.

[0086] The auxiliary storage unit 103 stores in advance a program 110 (sensor synchronization program) and data necessary for processing. The program 110 causes the computer 100 to execute each functional element of the first controller 11, 11A, the second controller 21, 21A, and the terminal 50. The program 110 causes, for example, processing related to the above-mentioned sensor synchronization method to be executed in the computer 100. For example, the program 110 is read by the processor 101 or the main storage unit 102, and causes at least one of the processor 101, the main storage unit 102, the auxiliary storage unit 103, the communication control unit 104, the input device 105, and the output device 106 to operate. For example, the program 110 reads and writes data in the main storage unit 102 and the auxiliary storage unit 103.

[0087] The program 110 may be provided in a form recorded on a tangible storage medium such as a CD-ROM, a DVD-ROM, a semiconductor memory, etc. The program 110 may be provided as a data signal via a communication network.

[0088] For example, the sensor synchronization system 1 includes at least one processor 101. The sensor synchronization method by the sensor synchronization system 1 is executed by the at least one processor 101. Similarly, the sensor synchronization system 1A includes at least one processor 101. The sensor synchronization method by the sensor synchronization system 1A is executed by the at least one processor 101.

[0089] [Variations] The present disclosure is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit and scope of the present disclosure.

[0090] In the above embodiment, the number of sensors is two, but three or more sensors may be used. Even in this case, the same effect as the above embodiment can be achieved by calculating the delay time between the sensors and adjusting the output timing of the start signal for each sensor.

[0091] The multiple sensors may be of a model that cannot control the start and stop. For example, the multiple sensors may be of a model that starts measurement when the power is turned on. In this case, each of the multiple sensors may further have an external switch that controls the power on and off. The first control unit 12 or the second control unit 22 may control the external switch by shifting the delay time. Even in this case, the same effects as the first and second embodiments are achieved.

[0092] In the second embodiment, an input from a user specifying the center position of the reference object is received, but this is not limited to this. For example, depending on the irradiation direction of the laser light of the first sensor 10A and the second sensor 20A, the center position of the reference object may not be detected. In this case, the first analysis unit 13A and the second analysis unit 23A may estimate the size of the reference object. It is assumed that the reference object is a vehicle, the first sensor 10A measures the front of the vehicle, and the second sensor 20A measures the side of the vehicle. In this case, the first analysis unit 13A assumes the size of the vehicle to be 2 m wide and 4 m long, and sets the center position of the vehicle to a coordinate 2 m behind the center position of the front. The second analysis unit 23A sets the center position of the vehicle to a coordinate 1 m behind the center position of the side. This makes it possible to align the reference coordinates in the first point cloud information and the second point cloud information. [Explanation of symbols]

[0093] 1,1A Sensor Synchronization System 10,10A 1st sensor 11,11A First Controller 12 First Control Section 13,13A 1st analysis section 14 First Communications Department 20,20A Second Sensor 21,21A Second controller 22 Second Control Section 23,23A 2nd analysis section 24 2nd Communications Department 25,25A calculation section 26 Adjustment part 30 3rd Sensor 40 4th Sensor 50 terminals R Monitoring range R1 First monitoring range R2 Second monitoring range R3 3rd monitoring range R4 4th monitoring range

Claims

1. a first sensor that measures a monitoring range and generates first point cloud information; A first controller that controls the measurement of the first sensor; a second sensor that measures the monitoring range and generates second point cloud information; A second controller that controls the measurement of the second sensor, The first controller is a first control unit that starts measurement by the first sensor and records a first start time that is a start time of the measurement by the first sensor; a first analysis unit that acquires the first point cloud information and records a first reception time when the first point cloud information is first acquired; The second controller is a second control unit that starts measurement by the second sensor and records a second start time that is a start time of the measurement by the second sensor; a second analysis unit that acquires the second point cloud information and records a second reception time when the second point cloud information is first acquired; a calculation unit that calculates a delay time between the first sensor and the second sensor using a difference between the first start time and the first reception time and a difference between the second start time and the second reception time; an adjustment unit that instructs the first sensor and the second sensor to stop measuring, instructs one of the first sensor and the second sensor to start measuring which is delayed, and instructs the other sensor to start measuring by shifting the delay time. Sensor synchronization system.

2. A sensor synchronization method executed by a sensor synchronization system including: a first sensor that measures a monitoring range and generates first point cloud information; a first controller that controls the measurement of the first sensor; a second sensor that measures the monitoring range and generates second point cloud information; and a second controller that controls the measurement of the second sensor, starting a measurement by the first sensor and recording a first start time which is a start time of the measurement by the first sensor, starting a measurement by the second sensor and recording a second start time which is a start time of the measurement by the second sensor; acquiring the first point cloud information, recording a first reception time when the first point cloud information was first acquired, acquiring the second point cloud information, and recording a second reception time when the second point cloud information was first acquired; calculating a delay time between the first sensor and the second sensor using a difference between the first start time and the first reception time and a difference between the second start time and the second reception time; instructing the first sensor and the second sensor to stop measuring; instructing one of the first and second sensors to start measurement, the one being delayed, and instructing the other sensor to start measurement by shifting the delay time. Sensor synchronization method.

3. a first sensor that measures a monitoring range and generates first point cloud information; A first controller that controls the measurement of the first sensor; a second sensor that measures the monitoring range and generates second point cloud information; A second controller that controls the measurement of the second sensor; a terminal that receives an input of a reference coordinate indicating a coordinate position of a reference object that is a specific object present in the monitoring range, The first controller is a first control unit that starts measurement by the first sensor and records a first start time that is a start time of the measurement by the first sensor; a first analysis unit that acquires the first point cloud information and records a first reference coordinate time at which a coordinate that is approximate to the reference coordinate is detected using the first point cloud information; The second controller is a second control unit that starts measurement by the second sensor and records a second start time that is a start time of the measurement by the second sensor; a second analysis unit that acquires the second point cloud information and records a second reference coordinate time at which coordinates that are approximate to the reference coordinates are detected using the second point cloud information; a calculation unit that calculates a delay time between the first sensor and the second sensor using a difference between the first start time and the first reference coordinate time and a difference between the second start time and the second reference coordinate time; an adjustment unit that instructs the first sensor and the second sensor to stop measuring, instructs one of the first sensor and the second sensor to start measuring which is delayed, and instructs the other sensor to start measuring by shifting the delay time. Sensor synchronization system.

4. 1. A sensor synchronization method executed by a sensor synchronization system including: a first sensor that measures a monitoring range and generates first point cloud information; a first controller that controls the measurement of the first sensor; a second sensor that measures the monitoring range and generates second point cloud information; a second controller that controls the measurement of the second sensor; and a terminal that accepts input of reference coordinates that indicate a coordinate position of a reference object that is a specific object present in the monitoring range, starting a measurement by the first sensor and recording a first start time which is a start time of the measurement by the first sensor, starting a measurement by the second sensor and recording a second start time which is a start time of the measurement by the second sensor; acquiring the first point cloud information, and recording a first reference coordinate time at which coordinates approximating the reference coordinates are detected using the first point cloud information; acquiring the second point cloud information, and recording a second reference coordinate time at which coordinates approximating the reference coordinates are detected using the second point cloud information; calculating a delay time between the first sensor and the second sensor using a difference between the first start time and the first reference coordinate time and a difference between the second start time and the second reference coordinate time; instructing the first sensor and the second sensor to stop measuring; instructing one of the first and second sensors to start measurement, the one being delayed, and instructing the other sensor to start measurement by shifting the delay time. Sensor synchronization method.

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