Optical sensing system and optical sensing method

Abstract

Provided is a system for a scheme in which an optical fiber cable is used to connect a signal processing unit and individual scanner units, wherein the overall shape of a target object can be recognized. This optical sensing system (100) comprises a plurality of scanner devices (1) that are disposed at different sites and a signal processing device (2) that is connected to the plurality of scanner devices (1) by using a plurality of optical fiber cables (3), wherein: the plurality of scanner devices (1) emit laser beams toward a subject and receive reflected light reflected by the subject; and the signal processing device (2) outputs a first optical signal, which corresponds to the laser beams to be emitted by the plurality of scanner devices (1), to the plurality of scanner devices (1) via the plurality of optical fiber cables (3) and acquires a second optical signal, which corresponds to the reflected light received by the plurality of scanner devices (1), from the plurality of scanner devices (1) via the plurality of optical fiber cables (3).

Description

[Technical field]

[0001] The present invention relates to an optical sensing system. [Background technology]

[0002] There is known a system that performs optical sensing based on the principle of LiDAR (Light Detection and Ranging). In addition, in such a system, a method is known in which a scanner unit for LiDAR and a signal processor for LiDAR are connected by an optical fiber cable (for example, see Patent Document 1).

[0003] Patent Document 1 discloses an in-vehicle LiDAR system. As shown in FIG. 1A and FIG. 1B of Patent Document 1, the LiDAR system includes a plurality of scanner units (lidar scanners 110A-110F) and one signal processing unit (centralized laser delivery system 101). Each scanner unit is connected to the signal processing unit using an optical fiber cable (optical fiber channels 112A-112F). The plurality of scanner units, one signal processing unit, and a plurality of optical fiber cables are mounted on one vehicle (vehicle 100). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2020-504301 Summary of the Invention [Problem to be solved by the invention]

[0005] In the LiDAR system described in Patent Document 1, a vehicle is equipped with a plurality of scanner units, and the plurality of scanner units scan different spatial ranges (for example, see paragraphs

[0036] to

[0038] of Patent Document 1). That is, for a certain spatial range, only one scanner unit scans from one direction. Therefore, in the LiDAR system described in Patent Document 1, for an object existing in the certain spatial range, the shape of the object in the range scanned from the one direction can be recognized, but the shape of the object in the other ranges cannot be recognized. That is, the shape of the part of the shape of the object that corresponds to the back side as seen from the corresponding one scanner unit cannot be recognized. As a result, there is a problem that it is difficult to grasp the overall shape of the object.

[0006] In view of the above-mentioned problems, an object of the present invention is to enable the recognition of the overall shape of a target object in a system in which a signal processing unit and individual scanner units are connected using optical fiber cables. [Means for solving the problem]

[0007] The optical sensing system of the present invention comprises a plurality of scanner devices installed at different locations, and a signal processing device connected to the plurality of scanner devices using a plurality of optical fiber cables, wherein the plurality of scanner devices emit laser light toward an object and receive reflected light reflected by the object, and the signal processing device outputs a first optical signal corresponding to the laser light emitted by the plurality of scanner devices via the plurality of optical fiber cables to the plurality of scanner devices, and obtains a second optical signal corresponding to the reflected light received by the plurality of scanner devices from the plurality of scanner devices via the plurality of optical fiber cables.

[0008] In the optical sensing method of the present invention, a plurality of scanner devices installed at different locations emit laser light toward an object and receive reflected light reflected by the object, and a signal processing device connected to the plurality of scanner devices using a plurality of optical fiber cables outputs a first optical signal corresponding to the laser light emitted by the plurality of scanner devices to the plurality of scanner devices via the plurality of optical fiber cables, and obtains a second optical signal corresponding to the reflected light received by the plurality of scanner devices from the plurality of scanner devices via the plurality of optical fiber cables. Effect of the Invention

[0009] According to the present invention, in a system in which a signal processing unit and individual scanner units are connected using optical fiber cables, it is possible to recognize the overall shape of a target object. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing an optical sensing system according to the first embodiment. [Diagram 2] FIG. 2 is a block diagram showing an individual scanner device in the optical sensing system according to the first embodiment. [Diagram 3] FIG. 3 is a block diagram showing the hardware configuration of each scanner device in the optical sensing system according to the first embodiment. [Figure 4] FIG. 4 is a block diagram showing a signal processing device in the optical sensing system according to the first embodiment. [Diagram 5] FIG. 5 is a block diagram showing a signal processing unit of the signal processing device in the optical sensing system according to the first embodiment. [Figure 6] FIG. 6 is a block diagram showing a hardware configuration of a signal processing device in the optical sensing system according to the first embodiment. [Figure 7] FIG. 7 is a block diagram showing another hardware configuration of the signal processing device in the optical sensing system according to the first embodiment. [Figure 8] FIG. 8 is a block diagram showing another hardware configuration of the signal processing device in the optical sensing system according to the first embodiment. [Figure 9] FIG. 9 is a flowchart showing the operation of the signal processing device in the optical sensing system according to the first embodiment. [Figure 10] FIG. 10 is a flowchart showing the operation of the signal processing unit of the signal processing device in the optical sensing system according to the first embodiment. [Figure 11] FIG. 11 is an explanatory diagram showing a specific example of the optical sensing system according to the first embodiment. [Figure 12] FIG. 12 is an explanatory diagram showing a specific example of an optical sensing system for comparison with the optical sensing system according to the first embodiment. [Figure 13] FIG. 13 is an explanatory diagram showing a modified example of the optical sensing system according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0012] [First embodiment] FIG. 1 is a block diagram showing an optical sensing system according to a first embodiment. FIG. 2 is a block diagram showing an individual scanner device in the optical sensing system according to the first embodiment. FIG. 3 is a block diagram showing a hardware configuration of an individual scanner device in the optical sensing system according to the first embodiment. FIG. 4 is a block diagram showing a signal processing device in the optical sensing system according to the first embodiment. FIG. 5 is a block diagram showing a signal processing unit of the signal processing device in the optical sensing system according to the first embodiment. The optical sensing system according to the first embodiment will be described with reference to FIGS. 1 to 5.

[0013] As shown in FIG. 1, the optical sensing system 100 includes a plurality of scanner devices 1 and one signal processing device 2. The plurality of scanner devices 1 are connected to the signal processing device 2 using a plurality of optical fiber cables 3. In the example shown in FIG. 1, the optical sensing system 100 includes N scanner devices 1_1 to 1_N. Each of the scanner devices 1_1 to 1_N is connected to the signal processing device 2 using a corresponding one of the N optical fiber cables 3_1 to 3_N. That is, in the example shown in FIG. 1, the optical fiber cables 3_1 to 3_N and the scanner devices 1_1 to 1_N correspond one-to-one. Here, N is an arbitrary integer of 2 or more. However, as described later, such a correspondence is not limited to one-to-one.

[0014] Each scanner device 1 is installed in a space (hereinafter sometimes referred to as a "target space") that contains an object (hereinafter sometimes referred to as a "target object") to be sensed by the optical sensing system 100. Moreover, each scanner device 1 is installed facing the target object. Here, the multiple scanner devices 1 are installed independently of each other. That is, the multiple scanner devices 1 are installed at different points in the target space. As a result, the multiple scanner devices 1 are directed toward the target object from different positions. In other words, the multiple scanner devices 1 are directed toward the target object from different directions.

[0015] More specifically, the multiple scanner devices 1 are arranged around the object. That is, the multiple scanner devices 1 are arranged so as to surround the object. For example, at a position corresponding to each vertex of an N-sided polygonal area including the object, one of the N scanner devices 1 is arranged. As a result, as will be described later with reference to FIG. 11, the entire or substantially entire object is irradiated with the sensing laser light. Hereinafter, the entire or substantially entire object may be collectively referred to simply as "the entire object."

[0016] The target object is, for example, a plurality of piles of raw materials in a raw material yard. In this case, the raw material yard is the target space. Usually, the plurality of piles of raw materials are arranged in a row or in a plurality of rows in the raw material yard. Also, usually, the area of ​​the raw material yard is several tens to several hundreds of meters square. That is, the area of ​​the target space is, for example, several tens to several hundreds of meters square.

[0017] Specifically, for example, a plurality of types of raw materials for steel making are stored in a raw material yard of a steelworks. At this time, a plurality of scanner devices 1 are arranged in the raw material yard of the steelworks so as to surround the piles of these raw materials.

[0018] 1, the signal processing device 2 is connected to a higher-level system 200 using an electric communication line 4. This allows the signal processing device 2 to freely communicate with the higher-level system 200. The higher-level system 200 is a higher-level system relative to the optical sensing system 100. The higher-level system 200 is provided outside the optical sensing system 100. The electric communication line 4 is, for example, composed of a cable for electric communication. Specifically, for example, the electric communication line 4 is composed of a LAN (Local Area Network) cable.

[0019] As shown in FIG. 2, each scanner device 1 includes a light emitting unit 11 and a light receiving unit 12. The light emitting unit 11 emits laser light for sensing toward an object. The emitted laser light is irradiated onto the object. Here, in each scanner device 1, the direction in which the laser light is emitted by the light emitting unit 11 is variable. The light emitting unit 11 sequentially emits laser light in a plurality of directions. In this way, the laser light is irradiated so as to scan the object. The irradiated laser light is reflected by the object. A backscattered component of the reflected light (hereinafter sometimes referred to as "reflected light") is received by the light receiving unit 12. Hereinafter, the light of the reflected light received by the light receiving unit 12 may be referred to as "received light."

[0020] Here, each scanner device 1 does not have a function of generating laser light. Also, each scanner device 1 does not have a function of converting received light into an electrical signal. As will be described later with reference to FIG. 4, these functions are provided in the signal processing device 2.

[0021] 3, each scanner device 1 includes an optical system 21 corresponding to the light emitting unit 11 and the light receiving unit 12. In other words, the functions of the light emitting unit 11 and the light receiving unit 12 are realized by the optical system 21. Note that the optical system 21 may include a first optical system (not shown) corresponding to the light emitting unit 11 and a second optical system (not shown) corresponding to the light receiving unit 12.

[0022] As will be described later with reference to Fig. 4, the signal processing device 2 generates an optical signal (hereinafter sometimes referred to as a "first optical signal") composed of laser light, and outputs the generated first optical signal to each optical fiber cable 3. The output first optical signal propagates inside the optical fiber cable 3, and is input to the corresponding scanner device 1. The optical system 21 emits the input first optical signal (i.e., laser light) as laser light for sensing. In this manner, the function of the light emitting unit 11 is realized.

[0023] Furthermore, the optical system 21 of each scanner device 1 receives the reflected light and outputs the received reflected light (i.e., received light) to the corresponding optical fiber cable 3. In this manner, the function of the light receiving unit 12 is realized. The output received light propagates inside the optical fiber cable 3 as an optical signal (hereinafter sometimes referred to as a "second optical signal") and is input to the signal processing device 2. The input second optical signal is converted into an electrical signal in the signal processing device 2, as will be described later with reference to FIG. 4.

[0024] 4, the signal processing device 2 includes an optical signal output unit 31, an optical signal acquisition unit 32, an optical switch unit 33, a signal processing unit 34, and a communication unit 35. The optical switch unit 33 is provided between the optical signal output unit 31 and the optical signal acquisition unit 32 and the multiple optical fiber cables 3.

[0025] The optical signal output unit 31 generates a first optical signal and outputs the generated first optical signal. As described above, the first optical signal is composed of a laser beam. The output first optical signal is output to each optical fiber cable 3 via the optical switch unit 33. The optical signal output unit 31 is composed of, for example, an optical transmitter for LiDAR.

[0026] On the other hand, the second optical signals input to the signal processing device 2 via the individual optical fiber cables 3 are input to the optical signal acquiring unit 32 via the optical switch unit 33. The optical signal acquiring unit 32 acquires the second optical signals and converts the acquired second optical signals into electrical signals. The optical signal acquiring unit 32 is configured, for example, by an optical receiver for LiDAR.

[0027] The optical switch unit 33 is a switch for switching the output destination of the first optical signal and the acquisition source of the second optical signal, and is configured by one or more optical switches.

[0028] For example, three scanner devices 1_1 to 1_3 are respectively connected to the signal processing device 2 using three optical fiber cables 3_1 to 3_3. In this case, the optical switch unit 33 can freely switch between the following first connection state, second connection state, and third connection state. That is, the first connection state is a state in which the optical signal output unit 31 and the optical signal acquisition unit 32 are optically connected to the first optical fiber cable 3_1. The second connection state is a state in which the optical signal output unit 31 and the optical signal acquisition unit 32 are optically connected to the second optical fiber cable 3_2. The third connection state is a state in which the optical signal output unit 31 and the optical signal acquisition unit 32 are optically connected to the third optical fiber cable 3_3.

[0029] In the first connection state, the first optical signal output by the optical signal output unit 31 is input to the first scanner device 1_1 via the optical switch unit 33 and the first optical fiber cable 3_1. Also, the second optical signal output by the first scanner device 1_1 is input to the optical signal acquisition unit 32 via the first optical fiber cable 3_1 and the optical switch unit 33.

[0030] In the second connection state, the first optical signal output by the optical signal output unit 31 is input to the second scanner device 1_2 via the optical switch unit 33 and the second optical fiber cable 3_2. Also, the second optical signal output by the second scanner device 1_2 is input to the optical signal acquisition unit 32 via the second optical fiber cable 3_2 and the optical switch unit 33.

[0031] In the third connection state, the first optical signal output by the optical signal output unit 31 is input to the third scanner device 1_3 via the optical switch unit 33 and the third optical fiber cable 3_3. Also, the second optical signal output by the third scanner device 1_3 is input to the optical signal acquisition unit 32 via the third optical fiber cable 3_3 and the optical switch unit 33.

[0032] In this manner, the first optical signal is output to each of the scanner devices 1_1 to 1_3. In other words, a plurality of first optical signals are output to the plurality of scanner devices 1 respectively. In addition, the second optical signal is acquired from each of the scanner devices 1_1 to 1_3. In other words, a plurality of second optical signals are acquired from the plurality of scanner devices 1 respectively.

[0033] The optical switch unit 33 sequentially switches between the first connection state, the second connection state, and the third connection state. As a result, the emission of laser light for sensing and the reception of the corresponding reflected light are sequentially performed by the first scanner device 1_1, the second scanner device 1_2, and the third scanner device 1_3. The optical signal acquisition unit 32 sequentially acquires second optical signals corresponding to these received lights, and sequentially converts these second optical signals into electrical signals. The optical signal acquisition unit 32 outputs the converted electrical signals to the signal processing unit 34.

[0034] The signal processing unit 34 executes a predetermined signal processing using the electrical signal output by the optical signal acquiring unit 32. The signal processing executed by the signal processing unit 34 includes, for example, measurement of a distance D based on the principle of LiDAR, and generation of point cloud data based on the measured distance D. In this case, as shown in Fig. 6, the signal processing unit 34 includes a distance measuring unit 41 and a point cloud data generating unit 42.

[0035] The distance measurement unit 41 executes measurement of the distance D based on the principle of LiDAR. For example, the measurement uses a Time of Flight (ToF) method or a Frequency Modulated Continuous Wave (FMCW) method.

[0036] When using ToF When ToF is used, the optical signal output unit 31 outputs a pulsed first optical signal. Each pulse (i.e., each first optical signal) corresponds to a laser beam emitted in each direction by each scanner device 1. In other words, the switching of the connection in the optical switch unit 33 and the change in the emission direction of the laser beam in each scanner device 1 are set so as to realize such a correspondence.

[0037] The distance measurement unit 41 acquires information indicating the timing T1' at which the optical signal output unit 31 outputs the first optical signal. Such information is acquired, for example, from the optical signal output unit 31. Furthermore, the distance measurement unit 41 detects the timing T2' at which the optical signal acquisition unit 32 acquires a second optical signal corresponding to the output first optical signal, using the electrical signal output by the optical signal acquisition unit 32. Specifically, for example, the distance measurement unit 41 detects the timing T2' by comparing the amplitude in the time waveform of the output electrical signal with a predetermined threshold and detecting the timing at which the amplitude exceeds the threshold.

[0038] Here, the time difference ΔT' between the timings T1' and T2' is equivalent to the time difference ΔT between the timing T1 at which the sensing laser light corresponding to the output first optical signal is emitted and the timing T2 at which the reflected light corresponding to the input second optical signal is received. In other words, the time difference ΔT' is equivalent to the round-trip propagation time of these lights (i.e., the corresponding sensing laser light and the corresponding reflected light). Therefore, the distance measurement unit 41 calculates the one-way propagation distance (i.e., the distance D) corresponding to this round-trip propagation time using a predetermined formula related to ToF. In this manner, the distance D is measured.

[0039] <When using FMCW> When FMCW is used, the optical signal output unit 31 outputs a chirp-shaped first optical signal by executing a predetermined frequency modulation process for FMCW. As a result, the laser light emitted in each direction by each scanner device 1 also becomes chirp-shaped. In addition, the optical signal acquisition unit 32 executes coherent detection of the second optical signal (i.e., the received light). As a result, the electrical signal output by the optical signal acquisition unit 32 contains the frequency and phase of the corresponding second optical signal (i.e., the received light).

[0040] The distance measurement unit 41 acquires information indicating the frequency of the first optical signal. Such information is acquired, for example, from the optical signal output unit 31. Furthermore, the distance measurement unit 41 detects the frequency of the corresponding second optical signal using the electrical signal output by the optical signal acquisition unit 32. The distance measurement unit 41 calculates a difference value between these frequencies (so-called "beat frequency"). Based on the calculated beat frequency, the distance measurement unit 41 calculates the distance D using a predetermined formula related to FMCW. In this manner, the distance D is measured.

[0041] The method of measuring the distance D is not limited to these specific examples. Various known techniques can be used to measure the distance D. Detailed explanations of these techniques will be omitted. For example, the distance measurement unit 41 may calculate the distance D based on the phase difference between the first optical signal and the corresponding second optical signal (i.e., the phase difference between the sensing laser light and the corresponding received light) (so-called "indirect ToF").

[0042] The distance measurement unit 41 generates information indicating the distance D measured in this manner (hereinafter sometimes referred to as "distance information"). The distance measurement unit 41 outputs the generated distance information to the point cloud data generation unit 42. Here, the distance information is output in association with information indicating the installation position of the scanner device 1 that emitted the laser light corresponding to each distance D (hereinafter sometimes referred to as "emission position information"). The distance information is also output in association with information indicating the emission direction of the laser light corresponding to each distance D (hereinafter sometimes referred to as "emission direction information"). These associations are realized, for example, as follows.

[0043] That is, after each scanner device 1 is installed and before use of the optical sensing system 100 begins, a person (e.g., a user of the optical sensing system 100) inputs information indicating the installation position and installation direction of each scanner device 1 into the signal processing device 2.

[0044] In the optical sensing system 100, the order in which the multiple scanner devices 1 emit laser light and the order in which each scanner device 1 emits laser light in multiple directions are set in advance. Information indicating these orders is stored in the signal processing device 2. Note that the timing at which the optical signal output unit 31 outputs the first optical signal, the timing and order at which the optical switch unit 33 switches the connection state, and the change in the emission direction of the laser light in each scanner device 1 are controlled so as to realize these orders.

[0045] By using these pieces of information, it is possible to identify the position of the scanner device 1 and the direction in which the laser light corresponding to each distance D is emitted. In this way, the distance information is linked to the emission position information and the emission direction information. Such linking is performed by the signal processing device 2 (for example, the distance measurement unit 41).

[0046] The point cloud data generating unit 42 generates point cloud data using the distance information output by the distance measuring unit 41, and the emission position information and emission direction information linked to the distance information. That is, the point cloud data generating unit 42 uses this information to calculate the positions of the points (hereinafter referred to as "reflection points") where the laser light corresponding to each distance D is reflected. As a result, data indicating a point cloud corresponding to the positions of these reflection points, i.e., point cloud data, is generated.

[0047] Here, as described above, the distance information includes the distance D corresponding to the laser light emitted by each of the multiple scanner devices 1. The point cloud in the point cloud data generated by the point cloud data generating unit 42 indicates the positions of the reflection points corresponding to the multiple scanner devices 1. That is, the generation of the point cloud data by the point cloud data generating unit 42 is based on so-called "point cloud synthesis." In other words, the point cloud data generating unit 42 generates the point cloud data by executing point cloud synthesis for the multiple scanner devices 1.

[0048] In addition, when the sensing laser light is irradiated onto an object other than the target object (for example, the ground surrounding the target object), the point cloud data may include a point cloud corresponding to the other object in addition to the point cloud corresponding to the target object. In such a case, the point cloud data generating unit 42 may extract a point cloud corresponding to the target object from among these point clouds by grouping the point clouds based on the inter-point distance or the result of plane detection. As a result, the point cloud data generating unit 42 may exclude the point cloud corresponding to the other object from the point cloud data.

[0049] The communication unit 35 (see FIG. 4) transmits information indicating the result of the signal processing by the signal processing unit 34 (hereinafter, sometimes referred to as "result information") to the outside. More specifically, the communication unit 35 transmits the result information to the upper system 200. The electric communication line 4 is used to transmit the result information.

[0050] In this manner, the optical sensing system 100 is configured. That is, the optical sensing system 100 is a system that performs optical sensing based on the principle of LiDAR.

[0051] The result information can be used for various applications by the host system 200. Specifically, for example, the host system 200 generates a three-dimensional model of the object using the point cloud data included in the result information. The host system 200 estimates the volume of the object (e.g., a pile of raw materials) using the generated three-dimensional model. Alternatively, for example, the host system 200 detects the occurrence of an abnormality in the object (e.g., a state in which the pile of raw materials has collapsed) based on the shape of the generated three-dimensional model.

[0052] Here, the host system 200 may generate an image as follows and display the generated image on a display device (e.g., a display) not shown. Specifically, for example, the host system 200 uses point cloud data included in the result information to generate an image (hereinafter, sometimes referred to as a "point cloud image") in which the point cloud included in the point cloud data is arranged in a virtual three-dimensional space. Alternatively, for example, the host system 200 generates a three-dimensional model as described above and generates an image (hereinafter, sometimes referred to as a "three-dimensional model image") including the generated three-dimensional model. By displaying the point cloud image or the three-dimensional model image on a display, a person (e.g., a user of the host system 200) can easily visually recognize the shape of the target object.

[0053] Next, the hardware configuration of the signal processing device 2 will be described with reference to FIGS.

[0054] 6 to 8, the signal processing device 2 includes an optical transmitter 51, an optical receiver 52, an optical switch 53, a transmitter 54, and a receiver 55. The function of the optical signal output unit 31 is realized by the optical transmitter 51. The function of the optical signal acquisition unit 32 is realized by the optical receiver 52. The function of the optical switch unit 33 is realized by the optical switch 53. The function of the communication unit 35 is realized by the transmitter 54 and the receiver 55.

[0055] 6, the signal processing device 2 includes a processor 56 and a memory 57. In this case, the memory 57 stores a program corresponding to the function of the signal processing unit 34. The processor 56 reads out and executes the program stored in the memory 57. In this way, the function of the signal processing unit 34 is realized.

[0056] 7, the signal processing device 2 includes a processing circuit 58. In this case, the processing circuit 58 executes processing corresponding to the function of the signal processing unit 34. In this way, the function of the signal processing unit 34 is realized.

[0057] 8 , the signal processing device 2 includes a processor 56, a memory 57, and a processing circuit 58. In this case, some of the functions of the signal processing unit 34 are realized by the processor 56 and the memory 57, and the remaining functions of the signal processing unit 34 are realized by the processing circuit 58.

[0058] The processor 56 is configured with one or more processors. Each processor may be, for example, a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, a microcontroller, or a digital signal processor (DSP).

[0059] The memory 57 is composed of one or more memories. Each memory is a volatile memory or a non-volatile memory. That is, each memory is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory), a solid state drive, a hard disk drive, a flexible disk, a compact disk, a DVD (Digital Versatile Disc), a Blu-ray disc, an MO (Magneto Optical) disc, or a mini disc.

[0060] The processing circuit 58 is composed of one or more processing circuits. Each processing circuit is, for example, an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), a system on a chip (SoC), or a large scale integration (LSI).

[0061] Next, a description will be given of the operation of the optical sensing system 100. More specifically, a description will be given of the operation of the signal processing device 2 with reference to the flowchart shown in FIG.

[0062] First, the optical signal output unit 31 outputs a first optical signal (step ST1). Next, the optical signal acquisition unit 32 acquires a corresponding second optical signal and converts the acquired second optical signal into an electrical signal (step ST2). These processes are repeatedly executed, for example, until all the scanner devices 1 included in the optical sensing system 100 emit sensing laser light in all the preset directions. In the flowchart shown in FIG. 9, the conditions for such repetition are omitted.

[0063] Next, the signal processing unit 34 executes a predetermined signal processing using the converted electric signal (step ST3). A specific example of the signal processing executed by the signal processing unit 34 has already been described, and therefore a detailed description thereof will be omitted.

[0064] Next, the communication unit 35 transmits information indicating the result of the signal processing in step ST3 (i.e., result information) to the outside (step ST4). More specifically, the communication unit 35 transmits the result information to the upper system 200 using the electric communication line 4.

[0065] Next, the operation of the signal processing unit 34 will be described with reference to the flowchart shown in Fig. 10. That is, a specific example of the signal processing executed in step ST3 will be described.

[0066] First, the distance measurement unit 41 executes measurement of the distance D based on the principle of LiDAR (step ST11). As a result, distance information is generated. A specific example of such a measurement method has already been described. Therefore, a detailed description will be omitted.

[0067] Next, the point cloud data generating unit 42 generates point cloud data using the distance information generated in step ST11 and the associated emission position information and emission direction information (step ST12). That is, the point cloud data generating unit 42 generates point cloud data by executing point cloud synthesis. In this case, the result information transmitted in step ST4 is information including the generated point cloud data.

[0068] Next, a specific example of the optical sensing system 100 will be described with reference to FIG.

[0069] In the figure, O indicates an object. As described above, the object is, for example, a pile of raw materials in a raw material yard. In the example shown in FIG. 11, three piles of raw materials are arranged in a row. The object space in this case ("S" in the figure) is the raw material yard.

[0070] In the example shown in FIG. 11, the optical sensing system 100 includes three scanner devices 1_1 to 1_3. Each of the scanner devices 1_1 to 1_3 is connected to the signal processing device 2 using a corresponding one of the three optical fiber cables 3_1 to 3_3. As described above, the scanner devices 1_1 to 1_3 are installed in the target space. In addition, in the example shown in FIG. 11, the signal processing device 2 is also installed in the target space. Also, the upper system 200 is installed in the target space.

[0071] Each of the scanner devices 1_1 to 1_3 is installed facing the target object. Here, the scanner devices 1_1 to 1_3 are installed independently of each other. That is, the scanner devices 1_1 to 1_3 are installed at different points in the target space. More specifically, the scanner devices 1_1 to 1_3 are arranged around the target object. That is, the scanner devices 1_1 to 1_3 are arranged so as to surround the target object. In the example shown in FIG. 11, the scanner devices 1_1 to 1_3 are arranged at positions corresponding to the vertices of a triangular area (not shown) including the target object. As a result, the entire target object is irradiated with the laser light for sensing.

[0072] Next, an optical sensing system 100' for comparison with the optical sensing system 100 will be described with reference to Fig. 12. In Fig. 12, elements similar to those shown in Fig. 11 are denoted by the same reference numerals and description thereof will be omitted.

[0073] As shown in Fig. 12, the optical sensing system 100' includes a plurality of optical sensing devices 6'. Each optical sensing device 6' is configured by a LiDAR device. That is, each optical sensing device 6' includes a scanner unit 1' and a signal processing unit 2'. The scanner unit 1' corresponds to the scanner device 1 in the optical sensing system 100. The signal processing unit 2' corresponds to the signal processing device 2 in the optical sensing system 100.

[0074] The scanner unit 1' emits a laser light for sensing toward an object and receives the corresponding reflected light. However, the scanner unit 1' has a function of generating a laser light for sensing and a function of converting the received light into an electrical signal. That is, the scanner unit 1' is composed of, for example, an optical transmitter, an optical receiver, and an optical system for LiDAR.

[0075] The signal processing unit 2' measures the distance D based on the principle of LiDAR. As a result, distance information is generated. In addition, the signal processing unit 2' may generate point cloud data using the generated distance information. As a result, point cloud data indicating the point cloud obtained by each light sensing device 6' is generated.

[0076] Each signal processing unit 2' is connected to the host system 200' via an electric communication line 4'. This allows each signal processing unit 2' to freely communicate with the host system 200'. In other words, the electric communication line 4' corresponds to the electric communication line 4 in the optical sensing system 100. Each signal processing unit 2' transmits the generated point cloud data to the host system 200'. The host system 200' generates a three-dimensional model of the object by synthesizing these point cloud data (i.e., by executing point cloud synthesis).

[0077] Each telecommunication line 4' is composed of a cable for telecommunication. Specifically, for example, each telecommunication line 4' is composed of a LAN cable. Usually, the distance over which a signal can be transmitted using one wired telecommunication line is shorter than the distance over which a signal can be transmitted using one optical fiber cable. For this reason, particularly when the area of ​​the target space is large, the length of one wired telecommunication line may become long, making it difficult to transmit such signals. Therefore, a repeater 5' is installed to amplify such signals.

[0078] In the example shown in FIG. 12, the optical sensing system 100' includes three optical sensing devices 6'_1 to 6'_3. The optical sensing devices 6'_1 to 6'_3 include scanner units 1'_1 to 1'_3, respectively. The optical sensing devices 6'_1 to 6'_3 also include signal processing units 2'_1 to 2'_3, respectively. The signal processing units 2'_1 to 2'_3 are connected to the upper system 200' using a corresponding one of the three electric communication lines 4'_1 to 4'_3. However, an amplifying repeater 5'_1 is provided in the middle of the electric communication line 4'_1. As a result, the one electric communication line 4'_1 is divided into two electric communication lines 4'_1_1 and 4'_1_2.

[0079] Next, a modification of the optical sensing system 100 will be described with reference to FIG.

[0080] Usually, the distance over which a signal can be transmitted using one optical fiber cable is longer than the distance over which a signal can be transmitted using one wired electric communication line. In particular, the distance over which a signal can be transmitted using one optical fiber cable is sufficiently long relative to the area of ​​the target space. For this reason, in principle, an optical repeater equivalent to the repeater 5' is not required in the optical sensing system 100.

[0081] However, depending on the manner in which each optical fiber cable 3 is laid, the laying length of each optical fiber cable 3 may become longer than the distance over which the signal can be transmitted. For example, the laying length of the optical fiber cable 3 may become longer if the optical fiber cable 3 is laid in a meandering manner or is laid to make a large detour around an obstacle. In such a case, exceptionally, the optical sensing system 100 may include an optical repeater 5 equivalent to the repeater 5'. That is, the optical repeater 5 is provided in the middle of at least one of the optical fiber cables 3. The optical repeater 5 is, for example, composed of an optical amplifier.

[0082] 13, an optical repeater 5_1 for amplification is provided midway along the optical fiber cable 3_1, thereby dividing the single optical fiber cable 3_1 into two optical fiber cables 3_1_1 and 3_1_2.

[0083] Next, another modification of the optical sensing system 100 will be described.

[0084] The target object is not limited to a pile of raw materials in a raw materials yard. The target object may be any object that is the subject of point cloud data acquisition (i.e., the subject of a three-dimensional model generation). For example, the target object may be an airplane parked at an airport. In this case, the airport is the target space.

[0085] Moreover, the signal processing executed by the signal processing unit 34 may be any processing that uses an electrical signal corresponding to the second optical signal, and is not limited to the above specific example.

[0086] For example, the signal processing unit 34 may generate a three-dimensional model of the object using the generated point cloud data, in addition to measuring the distance D and generating the point cloud data. That is, the generation of the three-dimensional model may be performed by the signal processing unit 34 instead of by the host system 200. In this case, the signal processing unit 34 includes a three-dimensional model generating unit (not shown) in addition to the distance measurement unit 41 and the point cloud data generating unit 42. The result information transmitted by the communication unit 35 includes the three-dimensional model generated by the three-dimensional model generating unit. The host system 200 uses the generated three-dimensional model to estimate the volume of the object or detect the occurrence of an abnormality in the object.

[0087] Alternatively, for example, the signal processing unit 34 may only measure the distance D out of the measurement of the distance D and the generation of the point cloud data. That is, the signal processing unit 34 may only include the distance measurement unit 41 out of the distance measurement unit 41 and the point cloud data generation unit 42. In this case, the result information transmitted by the communication unit 35 includes distance information indicating the measured distance D, and the associated emission position information and emission direction information. The host system 200 generates point cloud data by executing point cloud synthesis using these pieces of information. The host system 200 generates a three-dimensional model of the object using the generated point cloud data.

[0088] Furthermore, the signal processing device 2 may not have the signal processing unit 34. In this case, instead of transmitting the result information to the host system 200, the communication unit 35 transmits information indicating the electrical signal output by the optical signal acquisition unit 32 to the host system 200. Furthermore, the communication unit 35 transmits to the host system 200 emission position information and emission direction information corresponding to each second optical signal. The host system 200 uses this information to measure the distance D and generate point cloud data. The host system 200 uses the generated point cloud data to generate a three-dimensional model of the object.

[0089] At least one of the multiple scanner devices 1 may be a mobile scanner device 1. The mobile scanner device 1 is movable independently of the other scanner devices 1. The mobile scanner device 1 moves to emit laser light for sensing toward an object from each of a plurality of different positions.

[0090] Moreover, the generation and display of the point cloud image may be performed by the signal processing device 2 instead of by the host system 200. Moreover, the generation and display of the three-dimensional model image may be performed by the signal processing device 2 instead of by the host system 200. That is, the signal processing device 2 generates a point cloud image or a three-dimensional model image, and displays the generated image on a display unit (e.g., a display) not shown. By displaying the point cloud image or the three-dimensional model image, a person (e.g., a user of the optical sensing system 100) can easily visually recognize the shape of the target object.

[0091] Furthermore, the correspondence between the multiple optical fiber cables 3 and the multiple scanner devices 1 is not limited to a one-to-one relationship. For example, one of the multiple optical fiber cables 3 may be configured as a branch cable, and the single optical fiber cable 3 may be connected to two or more scanner devices 1 out of the multiple scanner devices 1.

[0092] Next, the effects of the optical sensing system 100 will be described.

[0093] As described above, the optical sensing system 100 includes a plurality of scanner devices 1 installed at different locations, and a signal processing device 2 connected to the plurality of scanner devices 1 via a plurality of optical fiber cables 3. The plurality of scanner devices 1 emit laser light toward an object, and receive light reflected by the object. The signal processing device 2 outputs a first optical signal corresponding to the laser light emitted by the plurality of scanner devices 1 to the plurality of scanner devices 1 via the plurality of optical fiber cables 3, and acquires a second optical signal corresponding to the reflected light received by the plurality of scanner devices 1 from the plurality of scanner devices 1 via the plurality of optical fiber cables 3. This provides the following effects.

[0094] First, by using a plurality of scanner devices 1 installed at different locations, the following advantageous effects are achieved compared to the LiDAR system described in Patent Document 1.

[0095] That is, by using a plurality of scanner devices 1 installed at different locations, these scanner devices 1 can be arranged around the object (see FIG. 11). As a result, the same object is irradiated with sensing laser light from a plurality of different positions. In other words, the same object is irradiated with sensing laser light from a plurality of different directions. As a result, it is possible to prevent the occurrence of a portion of the object that is not irradiated with the sensing laser light. As a result, when generating a three-dimensional model of the object, it is possible to prevent the occurrence of a missing portion caused by not being irradiated with the sensing laser light.

[0096] More specifically, by using a plurality of scanner devices 1 installed at different locations, the plurality of scanner devices 1 can be arranged so as to surround the object (see Fig. 11). As a result, the entire object is irradiated with sensing laser light. As a result, the occurrence of missing parts in the three-dimensional model can be avoided. In this way, in the optical sensing system 100 in which the signal processing device 2 and the individual scanner devices 1 are connected using the optical fiber cable 3, the overall shape of the object can be recognized.

[0097] Second, by using the method in which the signal processing device 2 and the individual scanner devices 1 are connected using the optical fiber cable 3, the following advantageous effects can be obtained as compared with the comparative optical sensing system 100'.

[0098] That is, in suppressing the occurrence of missing parts as described above, the number of signal processing devices 2 in the optical sensing system 100 can be reduced compared to the number of signal processing units 2' in the optical sensing system 100' (see Figs. 11 and 12). As a result, the configuration of the optical sensing system 100 can be simplified compared to the configuration of the optical sensing system 100'. Also, usually, the signal processing device 2 is more expensive than the individual scanner devices 1. That is, each signal processing unit 2' is more expensive than each scanner unit 1'. Therefore, by reducing the number of signal processing devices 2 compared to the number of signal processing units 2', the optical sensing system 100 can be realized at a lower cost than the optical sensing system 100'.

[0099] Furthermore, the attenuation of a signal over distance in an optical fiber cable is usually smaller than the attenuation of a signal over distance in a wired electric communication line (e.g., a LAN cable). Therefore, the number of optical repeaters 5 in the optical sensing system 100 can be reduced compared to the number of repeaters 5' in the optical sensing system 100' (see Figs. 11 and 12). In particular, when the area of ​​the target space is large and the targets are arranged over a wide range, the number of optical repeaters 5 can be significantly reduced compared to the number of repeaters 5'. This makes it possible to further simplify the configuration of the optical sensing system 100 compared to the configuration of the optical sensing system 100'.

[0100] Next, other effects of the optical sensing system 100 will be described.

[0101] The multiple scanner devices 1 are arranged around the target object. As a result, as described above, the same target object is irradiated with sensing laser light from multiple different positions. In other words, the same target object is irradiated with sensing laser light from multiple different directions. As a result, it is possible to prevent the occurrence of a portion of the target object that is not irradiated with the sensing laser light.

[0102] In addition, the multiple scanner devices 1 emit laser light from different directions toward the same object. As a result, as described above, it is possible to prevent the occurrence of areas on the object that are not irradiated with the sensing laser light. As a result, when generating a three-dimensional model of the object, it is possible to prevent the occurrence of missing parts caused by not being irradiated with the sensing laser light.

[0103] Further, at least one of the plurality of scanner devices 1 is movable independently of the other scanner devices 1 among the plurality of scanner devices 1. The movable scanner device 1 can emit sensing laser light toward the same object from each of a plurality of different positions by moving. Therefore, by using the movable scanner device 1, the number of scanner devices 1 required for irradiating the entire object with sensing laser light can be reduced. That is, the number of scanner devices 1 included in the optical sensing system 100 can be reduced. As a result, the configuration of the optical sensing system 100 can be made simpler.

[0104] Further, the optical sensing system 100 includes an optical repeater 5 provided in at least one of the plurality of optical fiber cables 3. Thereby, even when the laying length of such one optical fiber cable 3 becomes long, the optical sensing system 100 can be realized.

[0105] Further, the signal processing device 2 includes an optical switch 53 for switching the output destination of the first optical signal and the acquisition source of the second optical signal. Thereby, in the signal processing device 2, it is possible to avoid the occurrence of mixing of optical signals between the scanner devices 1.

[0106] Further, the object is a pile of raw materials in the raw material yard. The plurality of scanner devices 1 are installed in the raw material yard. Thereby, for example, the optical sensing system 100 can be used for estimating the volume of the pile of raw materials or detecting the occurrence of an abnormality in the pile of raw materials.

[0107] Further, the object is an aircraft parked at the airport. The plurality of scanner devices 1 are installed at the airport. Thereby, for example, the optical sensing system 100 can be used for detecting the occurrence of an abnormality in the parked aircraft.

[0108] Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the above embodiment. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0109] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes.

[0110] [Note] [Appendix 1] A signal processing device connected to a plurality of scanner devices installed at different locations using a plurality of optical fiber cables, The plurality of scanner devices emit laser light toward an object and receive light reflected by the object; The signal processing device outputs a first optical signal corresponding to the laser light emitted by the plurality of scanner devices to the plurality of scanner devices via the plurality of optical fiber cables, and acquires a second optical signal corresponding to the reflected light received by the plurality of scanner devices from the plurality of scanner devices via the plurality of optical fiber cables. An optical sensing system comprising: [Appendix 2] The optical sensing system described in Appendix 1, wherein the multiple scanner devices are arranged around the target object. [Appendix 3] The optical sensing system according to claim 1 or 2, wherein the plurality of scanner devices emit the laser light toward the same target object from different directions. [Appendix 4] 4. The optical sensing system of claim 1, wherein at least one of the plurality of scanner devices is movable independently of other scanner devices of the plurality of scanner devices. [Appendix 5] 5. The optical sensing system according to claim 1, further comprising an optical repeater provided in at least one of the plurality of optical fiber cables. [Appendix 6] The optical sensing system described in any one of Supplementary Note 1 to Supplementary Note 5, characterized in that the signal processing device is provided with an optical switch for switching the output destination of the first optical signal and the source of the second optical signal. [Appendix 7] The object is a pile of raw materials in a raw material yard, The plurality of scanner devices are installed in the raw material yard. 7. The optical sensing system according to claim 1, [Appendix 8] the object is an aircraft parked at an airport, The plurality of scanner devices are installed at the airport. 7. The optical sensing system according to claim 1, [Appendix 9] A plurality of scanner devices installed at different locations emit laser light toward an object and receive light reflected by the object; A signal processing device connected to the plurality of scanner devices using a plurality of optical fiber cables outputs a first optical signal corresponding to the laser light emitted by the plurality of scanner devices to the plurality of scanner devices via the plurality of optical fiber cables, and acquires a second optical signal corresponding to the reflected light received by the plurality of scanner devices from the plurality of scanner devices via the plurality of optical fiber cables. Optical sensing method. [Appendix 10] 10. The optical sensing method of claim 9, wherein the multiple scanner devices are arranged around the target object. [Appendix 11] The optical sensing method according to claim 9 or 10, wherein the plurality of scanner devices emit the laser light toward the same target object from different directions. [Appendix 12] 12. The optical sensing method of claim 9, wherein at least one of the plurality of scanner devices moves independently of other scanner devices of the plurality of scanner devices. [Appendix 13] 13. The optical sensing method according to claim 9, wherein an optical repeater is provided in at least one of the plurality of optical fiber cables. [Appendix 14] The optical sensing method described in any one of Supplementary Note 9 to Supplementary Note 13, characterized in that an optical switch of the signal processing device switches the output destination of the first optical signal and the source of the second optical signal. [Appendix 15] The object is a pile of raw materials in a raw material yard, The plurality of scanner devices are installed in the raw material yard. 15. The optical sensing method according to any one of claims 9 to 14, [Appendix 16] the object is an aircraft parked at an airport, The plurality of scanner devices are installed at the airport. 15. The optical sensing method according to any one of claims 9 to 14, [Explanation of symbols]

[0111] 1 Scanner device 2. Signal Processing Device 3. Fiber optic cable 4. Telecommunications Lines 5 Optical repeater 11 Light emitting part 12 Light receiving part 21 Optical system 31 Optical signal output section 32 Optical signal acquisition unit 33 Optical switch section 34 Signal Processing Section 35 Communications Department 41 Distance measurement unit 42 Point cloud data generator 51 Optical transmitter 52 Optical Receiver 53 Optical Switch 54 Transmitter 55 Receiver 56 processors 57 Memory 58 Processing Circuit 100 Optical Sensing System 200 Upper System

Claims

1. A system including a plurality of scanner devices installed at different locations, and a signal processing device connected to each of the plurality of scanner devices by an optical fiber, Each of the plurality of scanner devices emits light output from the signal processing device through the optical fiber toward an object, and transmits reflected light of the light reflected by the object to the signal processing device through the optical fiber; The signal processing device outputs the light through the optical fiber connected to the scanner device while switching the scanner device as the output destination, and generates point cloud data of the object based on the reflected light transmitted from the scanner device as the output destination. An optical sensing system comprising:

2. The plurality of scanner devices are arranged around the object.

2. The optical sensing system of claim 1.

3. The plurality of scanner devices emit the light from different directions toward the same object.

3. The optical sensing system according to claim 1 or 2.

4. At least one of the plurality of scanner devices is movable independently of other scanner devices of the plurality of scanner devices.

4. The optical sensing system according to claim 1, wherein the optical sensing system comprises: a first optical fiber;

5. An optical repeater is provided on at least one of the optical fibers.

5. The optical sensing system according to claim 1, wherein the optical sensing system comprises: a first optical fiber;

6. The signal processing device includes an optical switch for switching the scanner device that is the output destination.

6. The optical sensing system according to claim 1, wherein the optical sensing system comprises:

7. The object is a pile of raw materials in a raw material yard, The plurality of scanner devices are installed in the raw material yard.

7. The optical sensing system according to claim 1, wherein the optical sensing system comprises:

8. the object is an aircraft parked at an airport, The plurality of scanner devices are installed at the airport.

7. The optical sensing system according to claim 1, wherein the optical sensing system comprises:

9. Each of a plurality of scanner devices installed at different locations emits light output from a signal processing device through an optical fiber toward an object, and transmits reflected light reflected by the object to the signal processing device through the optical fiber; The signal processing device, which is connected to each of the plurality of scanner devices by an optical fiber, outputs the light through the optical fiber connected to the scanner device while switching the scanner device that is the output destination, and generates point cloud data of the object based on the reflected light transmitted from the scanner device that is the output destination.

13. An optical sensing method comprising:

10. The plurality of scanner devices are arranged around the object.

10. The optical sensing method according to claim 9.

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