Disturbance presence / absence determination device, method, and program

Abstract

To provide a technique for determining whether disturbance is present or absent in distance measurement.SOLUTION: A disturbance presence / absence determination device includes: an acquisition unit that acquires measurement results including a distance to a marker from a 3D distance sensor, with the marker placed at a known distance from the 3D distance sensor and within an angle of view of the 3D distance sensor; and a determination unit that determines whether or not there is a disturbance that causes a measurement error by the 3D distance sensor, based on the measurement results and the distance being acquired.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an apparatus, method, and program for determining the presence or absence of a disturbance. [Background technology]

[0002] In situations that require monitoring, such as production sites, distance sensors are used to detect objects such as human bodies. In order to reliably detect objects in the area to be monitored, distance sensors must be installed in appropriate positions and orientations. However, it is not easy for users to determine whether the installation position of a distance sensor is appropriate.

[0003] Patent Document 1 discloses a system that uses 3D sensors to monitor a workspace for safety purposes. In this system, the 3D sensors are aligned with each other, for example, by comparing images from each sensor with images from other sensors and identifying correspondences in the images. Patent Document 1 shows that the 3D sensors are not positioned in the proper positions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2020-511325 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, it is not possible to know whether the current sensor placement position is a position where there is a disturbance that may affect the measurement results of the sensor. Therefore, in order for a user to determine whether the installation position and orientation of the distance sensor are appropriate, it is necessary to understand the presence or absence of disturbance that may cause a measurement error. The applicant has considered, as examples of the disturbance, multipath caused by reflection of light or the like from objects other than the measurement target, high reflectors in close proximity, external light, dust, or vibration.

[0006] An object of the present invention is to provide a technique for determining the presence or absence of disturbance in distance measurement. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention employs the following configuration.

[0008] A first aspect of the present invention provides a disturbance presence / absence determination device comprising: an acquisition means for acquiring a measurement result including a distance to a marker by a three-dimensional distance sensor, the marker being positioned at a known distance from the three-dimensional distance sensor and within the angle of view of the three-dimensional distance sensor; and a determination means for determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor, based on the measurement result acquired by the acquisition means and the known distance.

[0009] An example of the "three-dimensional distance sensor" is a Time of Flight (TOF) sensor.

[0010] According to this configuration, a marker is placed at a known distance from the three-dimensional distance sensor, and based on a measurement result including the distance to the marker by the three-dimensional distance sensor acquired while the marker is within the angle of view of the three-dimensional distance sensor and the known distance, it is determined whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor. This makes it possible to determine the presence or absence of a disturbance in the three-dimensional distance measurement. An example of the disturbance is a disturbance caused by the reflection of light or the like from something other than the measurement target. These may be due to multipath interference, nearby highly reflective objects, external light, dust, or vibration.

[0011] For example, the three-dimensional distance sensor is a sensor that obtains distance information to the measurement target based on light reflected from the measurement target, and the determination means may determine that there is a multipath disturbance caused by reflections other than the measurement target when the measurement result indicates that the distance to the marker is longer than the known distance.

[0012] In addition, the three-dimensional distance sensor is a sensor that obtains distance information to the measurement target based on light reflected from the measurement target, and the measurement result includes light amount information at each position within the angle of view, and the determination means may determine that there is a disturbance due to a highly reflecting object in the vicinity when the measurement result indicates that the distance to the marker is shorter than the known distance and there is a position within the angle of view other than the marker where the light amount exceeds a first threshold light amount.

[0013] In addition, the measurement result may include light amount information for each position within the angle of view, and the determination means may determine that there is a disturbance due to external light if there is a position within the angle of view other than the marker where the light amount exceeds a second threshold light amount.

[0014] The determination means may determine that there is a disturbance due to dust when the distance to the marker indicated by the measurement result changes beyond a first threshold distance within a first predetermined time.

[0015] The determination means may determine that there is a disturbance due to vibration when the position of the marker within the angle of view indicated by the measurement result changes by more than a second threshold distance within a second predetermined time.

[0016] A second aspect of the present invention provides a disturbance presence / absence determination device comprising: an acquisition means for acquiring measurement results including distances to two markers by a three-dimensional distance sensor, with the two markers arranged at a known interval and the two markers falling within the angle of view of the three-dimensional distance sensor; and a determination means for determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor, based on the measurement results acquired by the acquisition means and the known interval.

[0017] According to this configuration, two markers are arranged at a known distance and are obtained with the two markers within the angle of view of the three-dimensional distance sensor. Based on the measurement results including the distances to the two markers by the three-dimensional distance sensor and the known distance, it is determined whether or not there is a disturbance within the angle of view that could cause a measurement error by the three-dimensional distance sensor.

[0018] For example, the three-dimensional distance sensor is a sensor that obtains distance information to the measurement target based on light reflected from the measurement target, and the determination means calculates the distance between the two markers based on the distances to the two markers acquired by the acquisition means, and if the calculated distance between the two markers does not match the known distance, it may determine that there is a disturbance due to either multipath caused by reflections other than the measurement target, a high-reflector in close range, or dust.

[0019] In addition, the determination means may calculate the distance between the two markers based on the distances to the two markers acquired by the acquisition means, and may determine that there is a dust disturbance if the calculated distance between the two markers changes to exceed a third threshold distance within a third specified time.

[0020] The determining means determines the distances to the two markers acquired by the acquiring means. If at least one of the above changes by more than a fourth threshold distance within a fourth predetermined time, it may be determined that there is a disturbance due to dust.

[0021] In addition, the three-dimensional distance sensor is a sensor that obtains distance information to the object to be measured based on light reflected from the object to be measured, and the measurement result includes light amount information at each position within the angle of view, and the determination means may determine that there is a disturbance due to either a highly reflecting object in the vicinity or external light if there is a position within the angle of view other than the two markers where the light amount exceeds a threshold light amount.

[0022] In addition, the determination means may determine that there is a disturbance due to vibration if the position within the angle of view of at least one of the two markers indicated by the measurement result changes by more than a fifth threshold distance within a fifth predetermined time.

[0023] The present invention may further comprise a notification means for notifying a result of the determination made by the determination means.The three-dimensional distance sensor may be a TOF sensor.

[0024] A third aspect of the present invention provides a method for determining the presence or absence of a disturbance, comprising: an acquisition step for acquiring a measurement result including a distance to a marker by a three-dimensional distance sensor, with the marker being positioned at a known distance from the three-dimensional distance sensor and the marker being within the angle of view of the three-dimensional distance sensor; and a determination step for determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor, based on the measurement result acquired by the acquisition step and the known distance.

[0025] A fourth aspect of the present invention provides a method for determining whether or not there is a disturbance, comprising: an acquisition step of acquiring measurement results including distances to two markers by a three-dimensional distance sensor, with two markers arranged at a known interval and the two markers falling within the angle of view of the three-dimensional distance sensor; and a determination step of determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor, based on the measurement results acquired by the acquisition step and the known interval.

[0026] A fifth aspect of the present invention provides a program for causing a computer to execute each step of the above-mentioned disturbance presence / absence determination method.

[0027] The present invention may be understood as a disturbance presence / absence determining device, a disturbance presence / absence determining system, or a disturbance presence / absence determining method having at least some of the above-mentioned means. The present invention may also be understood as a program for implementing such a method, or a recording medium on which such a program is non-temporarily recorded. Note that the above-mentioned means and processes can be combined with each other as much as possible to constitute the present invention. Effect of the Invention

[0028] According to the present invention, it is possible to determine the presence or absence of disturbance in distance measurement. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a block diagram of a determination system including a disturbance presence / absence determining device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic side view of a site where the presence or absence of a disturbance is determined. [Diagram 3] FIG. 3 is a schematic plan view of a site where the presence or absence of a disturbance is determined. [Figure 4] FIG. 4 is a diagram showing an example of a displayed luminance image. [Diagram 5] FIG. 5 is a functional block diagram of the control unit. [Figure 6] FIG. 6 is a schematic diagram of the sensor. [Figure 7] FIG. 7 is a flowchart showing the sensor installation process and the disturbance determination process. [Figure 8] FIG. 8 is a schematic diagram of a marker body including a pair of markers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] <Application Examples> An application example of the disturbance presence / absence determination device according to the present invention will be described with reference to Figs. 1 to 5. Fig. 1 is a block diagram of a determination system including a disturbance presence / absence determination device 50 according to an embodiment of the present invention. Figs. 2 and 3 are respectively a schematic side view and a schematic plan view of a site where the presence / absence of a disturbance is determined. Fig. 4 is a diagram showing an example of a displayed luminance image. Fig. 5 is a functional block diagram of a control unit. The directions of each unit are designated based on the X, Y, and Z coordinate axes shown in Figs. 2 and 3. As viewed from the sensor 10, the front is the +Y direction, the upward direction is the +Z direction, and the rightward direction is the +X direction.

[0031] The site shown in FIG. 2 and FIG. 3 is assumed to be a place where monitoring of objects is required, such as a production site where a hazard source 13 such as a robot works with a worker to carry out production. The hazard source 13 is installed on a workbench 12. A virtual hazard area 14 is set around or near the hazard source 13, taking into consideration the range of motion of the hazard source 13. A three-dimensional distance sensor 10 (hereinafter, referred to as sensor 10) is installed to detect an object such as a human body before it approaches the hazard area 14. The monitoring area of ​​the three-dimensional distance sensor 10 can be set arbitrarily. For example, the monitoring area may be 360 ​​degrees around the hazard area 14, or only a limited range may be set as the monitoring area when the access direction to the hazard source is limited (for example, when a safety fence is installed or an obstacle exists). In the example of FIG. 2, only the front (+Y direction) of the hazard area 14 is set as the monitoring area. The monitoring area may be set to include the hazard area 14, or may be set to exclude the hazard area 14. In order to ensure the reliability of object detection, it is necessary to eliminate any potential disturbances to the measurement from the angle of view of the sensor 10 and its surroundings, as disturbances may affect the measurement results and cause errors.

[0032] Therefore, in the first method (first embodiment), as shown in Fig. 2 and Fig. 3, the user places a marker 16 on the floor surface 11 at a known distance L1 from the sensor 10, and ensures that the marker 16 is within the angle of view 15 of the sensor 10. In this state, an acquisition unit 38 (Fig. 5) of the control unit 30 as an acquisition means acquires a measurement result including a measured distance L1x to the marker 16 by the sensor 10. Then, a determination unit 39 (Fig. 5) of the control unit 30 as a determination means determines whether or not there is a disturbance within the angle of view 15 that will cause a measurement error by the sensor 10, based on the acquired measurement result and the known distance L1.

[0033] Here, since the sensor 10 is placed above the danger zone 14, the actual distance from the sensor 10 to the marker 16 is the length in a direction inclined with respect to the floor surface 11 (the straight-line distance from the original position of the sensor 10 to the marker 16). However, the control unit 30 converts the actual distance into distance L1, which is the length in the Y direction parallel to the floor surface 11, and measured distance L1x. Note that the straight-line distances may be compared without converting them into lengths in the Y direction.

[0034] Examples of the disturbances include multipath caused by reflection of light and the like from objects other than the object to be measured, highly reflective objects in the vicinity, external light, dust, or vibration. FIG. 3 shows that a reflective wall 17 is within the angle of view 15 of the sensor 10 as a cause of multipath. In addition, it is shown that a highly reflective object 18 in the vicinity and external light 19 are within the angle of view 15. The luminance image obtained under such circumstances is as shown in FIG. 4. Note that, although multiple disturbance factors are shown in FIG. 4, it is also possible that only one of the disturbance factors is present.

[0035] As shown in Fig. 1, the sensor 10 includes a light emitting unit 41, a light receiving unit 42, and a calculation unit 43. The light emitting unit 41 emits light (e.g., infrared light), and the light receiving unit 42 receives the reflected light. In FIG. 10, as an example, a distance image is obtained from the time of flight (TOF) of light. A TOF sensor is used. For example, an indirect TOF sensor that estimates a time difference from a phase difference between projected light and reflected light is used. The sensor 10 outputs three-dimensional distance information and luminance information as measurement results. The measurement results by the sensor 10 include light amount information at each position within the angle of view 15. The measurement results are supplied to the control unit 30 via a sensor I / F 44 in the disturbance presence / absence determination device 50. The sensor 10 is controlled by the control unit 30 via the sensor I / F 44.

[0036] When the control unit 30 detects from the measurement results by the sensor 10 that an object such as a human body has entered the angle of view 15, it performs safety control such as slowing down or stopping the hazard. Furthermore, the control unit 30 determines the presence or absence of disturbance from the measurement results, and if there is a disturbance, determines the cause of the disturbance by utilizing the fact that the measurement results differ depending on the disturbance cause. The notification unit 40 (FIG. 5) of the control unit 30 as a notification means notifies the determination result of the presence or absence of disturbance, and if there is a disturbance, notifies the cause of the disturbance.

[0037] Examples of methods for determining the presence or absence of disturbance and the cause of the disturbance will be outlined (details will be described later). In a first method (first embodiment), for example, when the measurement result indicates that the measured distance L1x to the marker 16 is longer than the known distance L1, the control unit 30 determines that there is a disturbance due to multipath (reflection at the reflecting wall 17).

[0038] If the measurement results indicate that the measured distance L1x is shorter than the distance L1 and there is a position other than the marker 16 within the angle of view 15 where the light amount exceeds the first threshold light amount, the control unit 30 determines that there is a disturbance due to a high reflector (high reflector 18) in the vicinity.

[0039] The control unit 30 determines that there is a disturbance due to external light (external light 19) when there is a position other than the marker 16 within the angle of view 15 where the light amount exceeds the second threshold light amount. The control unit 30 determines that there is a disturbance due to dust when the measured distance L1x changes beyond the first threshold distance within a first predetermined time. The control unit 30 determines that there is a disturbance due to vibration when the position of the marker 16 within the angle of view 15 changes beyond the second threshold distance within a second predetermined time.

[0040] In addition, a second method (second embodiment) may be adopted instead of the first method, which will be described later with reference to FIG.

[0041] The above application examples are illustrative to aid in understanding the present invention, and are not intended to limit the interpretation of the present invention.

[0042] [First embodiment] Next, the configuration of the disturbance presence / absence determination device 50 and the procedure for installing the sensor 10 in the first embodiment of the present invention will be described in detail. First, the configuration of the disturbance presence / absence determination device 50 will be described with reference to FIG. 1. The disturbance presence / absence determination device 50 includes a control unit 30, a sensor I / F 44, a display unit 34, an operation input unit 35, a storage unit 36, and a communication I / F 37. The control unit 30 includes a CPU 31, a ROM 32, a RAM 33, and a timer (not shown). The ROM 32 stores a control program executed by the CPU 31. The ROM 32 also stores values ​​such as various threshold values. The RAM 33 provides a work area when the CPU 31 executes the control program.

[0043] The display unit 34 is configured with an LCD or the like, and displays various information. The display unit 34 may have two or more screens, or may have a function of displaying two or more screens by splitting the screen. The operation input unit 35 accepts input of various instructions from the user, and sends the input information to the CPU 31. The operation input unit 35 may also have a function of notifying the user by voice, lamps, etc. based on instructions from the CPU 31. The storage unit 36 ​​is, for example, composed of a non-volatile memory. The storage unit 36 ​​may be an external memory. The communication I / F 37 performs wired or wireless communication between the control unit 30 and an external device.

[0044] As shown in FIG. 5, the control unit 30 has an acquisition unit 38, a determination unit 39, and an alarm unit 40. These functions are realized in software by a program stored in the ROM 32. That is, the CPU 31 loads the necessary programs in the RAM 33 and executes them to perform various calculations and control each hardware resource, thereby providing each function. In other words, the function of the acquisition unit 38 is realized mainly by the cooperation of the CPU 31, the ROM 32, the RAM 33, and the sensor I / F 44. The function of the determination unit 39 is realized mainly by the cooperation of the CPU 31, the ROM 32, and the RAM 33. The function of the alarm unit 40 is realized mainly by the cooperation of the CPU 31, the ROM 32, the RAM 33, and the operation input unit 35.

[0045] 2, the marker 16 is, as an example, a three-dimensional object that is easy to place, but the shape of the marker 16 is not limited, and it may be a flat shape. The brightness of the marker 16 is preferably high. The reference surface on which the marker 16 is placed is not limited to the floor surface 11, and may be a flat surface such as a desk surface.

[0046] Next, a method of determining the presence or absence of disturbance and the cause of disturbance in this embodiment will be described in detail. The control unit 30 compares the measured distance L1x to the marker 16 indicated by the measurement result with the known distance L1, and if the measured distance L1x is longer than the distance L1, it determines that there is a disturbance due to multipath. Here, a threshold value for determination may be used in the comparison between the measured distance L1x and the distance L1, and the control unit 30 may determine that the measured distance L1x is longer than the distance L1 when "measured distance L1x = distance L1 + predetermined value" is established. This predetermined value is set to a value larger than the error of the measured distance L1x that may occur when there is no disturbance, and the value is stored in the ROM 32 in advance.

[0047] Consider the case where a reflecting wall 17 is present within the angle of view 15 as shown in FIG. 3. Assume that the reflecting wall is located at a position shifted to the side from the straight line connecting the sensor 10 and the marker 16. In principle, the light emitted from the light emitting unit 41 of the sensor 10 is directly reflected by the marker 16, which is the object to be measured, and is received by the light receiving unit 42. If only the direct light reflected by the marker 16 is received, the measurement distance L1x is equal to the distance L1. However, a part of the light emitted from the light emitting unit 41 may be reflected by the marker 16 via the reflecting wall 17 and received. The path via the reflecting wall 17 is longer than the path on the straight line between the sensor 10 and the marker 16. Therefore, the timing of receiving the light via the reflecting wall 17 is delayed compared to the light that does not pass through the reflecting wall 17. As a result, the measurement distance L1x may be longer than the distance L1. For these reasons, it can be determined that there is a disturbance due to multipath when the measurement distance L1x is longer than the distance L1. Regarding multipath, the degree of influence on the marker 16 may vary depending on the position of the reflecting wall 17. In other words, in the case of the arrangement example of Fig. 3, the occurrence of multipath caused by the reflecting wall 17 can be found from the fluctuation of the measurement distance of the marker 16, but it is not necessarily possible to find objects causing multipath in other positions. Therefore, in actual use, it is desirable to change the position of the marker 16 and perform measurements multiple times to find and deal with all objects causing multipath that exist inside and outside the monitoring area.

[0048] Next, as shown in FIG. 3, consider the case where a high reflector 18 is present near the sensor 10 within the angle of view 15. The high reflector 18 may be, for example, an object that is always placed, or an operator's foot. If the high reflector 18 is located at a position sufficiently closer to the sensor 10 than the marker 16, the sensor 10 receives strong reflected light from the high reflector 18. Therefore, the control unit 30 determines from the measurement result that there is a disturbance due to a nearby high reflector 18 when the measured distance L1x is shorter than the distance L1 and there is a position other than the marker 16 within the angle of view 15 where the light amount exceeds the first threshold light amount. The reason for this determination will be explained with reference to FIG. 6.

[0049] FIG. 6 is a schematic diagram of the sensor 10. The sensor 10 has a lens 20 as an optical system. The light 22 from the marker 16 passes through the lens 20 and is received by the light receiving unit 42. If the light received is only the light 22, the measured distance L1x is equal to the distance L1. However, there is a case where the light 23 reflected by the high reflector 18 passes through the lens 20 and is received by the light receiving unit 42 after passing through internal reflection between the light receiving unit 42 and the lens 20. In this case, the timing of receiving the internally reflected light 23 and the light 22 from the marker 16 is shifted. As a result, the distance as the measurement result is shorter than the actual distance. Moreover, since the high reflector 18 is located close to the sensor 10, the part corresponding to the high reflector 18 becomes brighter in the luminance image shown in FIG. 4. Therefore, if the light amount of the part corresponding to the high reflector 18 exceeds the first threshold light amount, it can be determined that there is a disturbance due to the high reflector 18 at a close distance.

[0050] Next, consider a case where external light 19 is present at a position other than marker 16 within angle of view 15, as shown in FIG. 3. When the amount of light at a position corresponding to external light 19 in the luminance screen shown in FIG. 4 exceeds a second threshold amount of light, control unit 30 determines that there is a disturbance due to external light 19. This is because the presence of external light 19 may cause an error in the measurement result. Here, the second threshold amount of light is set based on a value assumed as the amount of light at the portion corresponding to marker 16, and this value is stored in ROM 32 in advance. For example, the second threshold amount of light is a value greater than the assumed amount of light at the portion corresponding to marker 16.

[0051] Next, dust (not shown) floating at the work site is considered as another disturbance. The control unit 30 continuously acquires the measurement result for at least a first predetermined time. Then, if the measured distance L1x obtained from the measurement result changes beyond the first threshold distance within the first predetermined time, the control unit 30 determines that there is a disturbance due to dust. This is because the presence of dust may cause an error in the measurement result. For example, when light reflected by dust moving across the marker 16 is received by the sensor 10, the measured distance L1x is calculated as a short value temporarily, and it is detected that an object is located at a distance shorter than the distance L1 to the marker 16. Here, the first threshold distance is set to a value larger than the error of the measured distance L1x that may occur in the absence of disturbance, and the value is stored in the ROM 32 in advance. The first predetermined time is stored in the ROM 32, and the value is not limited. In addition, even if an operator or a machine frequently crosses the road, it is detected as a disturbance in the same way as dust.

[0052] Next, consider a case where there is vibration at the site as another disturbance. The vibration is assumed to be vibration caused by other machines, but vibration of the part where the sensor 10 is attached is also assumed. The control unit 30 continuously acquires the measurement result for at least a second predetermined time. Then, when the position (two-dimensional coordinates on the screen) of the marker 16 within the angle of view 15 obtained from the measurement result changes beyond the second threshold distance within the second predetermined time, the control unit 30 determines that there is a disturbance due to vibration. This is because when there is vibration, the position of the marker 16 changes relatively to the sensor 10 in small increments, which may cause an error in the measurement result. Here, the second threshold distance is set to a value larger than the error of the measurement distance L1x that may occur when there is no disturbance, and the value is stored in the ROM 32 in advance. The second predetermined time is stored in the ROM 32, and the value is not limited.

[0053] In this embodiment, the detectable disturbances are assumed to be multipath, a highly reflective object in a short distance, external light, dust, and vibration, but among these, a combination of possible disturbances may be used as the detection target. For example, it is possible to combine two or more of multipath, a highly reflective object in a short distance, dust, and vibration, and detect them in parallel. Alternatively, it is possible to combine two or more of multipath, external light, dust, and vibration, and detect them in parallel.

[0054] Next, the sensor installation process and the disturbance determination process will be described with reference to the flowchart of Fig. 7. Fig. 7 is a flowchart showing the sensor installation process and the disturbance determination process. This sensor installation process is executed by a user. The disturbance determination process is realized by the CPU 31 expanding a program stored in the ROM 32 into the RAM 33 and executing it. The disturbance determination process is started by a user's instruction and is executed by the CPU 31 in parallel with the sensor installation process.

[0055] First, in step S101, the user places the marker 16 on the floor surface 11 at a known distance L1 from the sensor 10. If the marker 16 has already been installed, the user may redo the installation of the marker 16. In step S102, the user installs the sensor 10, or adjusts the position as necessary if the marker 16 has already been installed. The user determines the position and orientation of the sensor 10 so that the marker 16 is within the angle of view 15 (field of view) of the sensor 10. In step S103, the user instructs the CPU 31 to perform distance measurement by the sensor 10 (distance measurement instruction). Distance measurement here includes obtaining not only distance information but also brightness information.

[0056] Meanwhile, in step S201, CPU 31 waits for a distance measurement instruction from the user, and proceeds to step S202 when the distance measurement instruction is received. In step S202, CPU 31 causes sensor 10 to perform distance measurement. Measurement results are supplied from sensor 10 to CPU 31. After obtaining measurement results for a certain period of time, CPU 31 executes a process of determining the presence or absence of disturbance and its cause based on the measurement results and known distance L1 in step S203. That is, the presence or absence of disturbance is determined using various discrimination methods for the presence or absence of disturbance and the disturbance cause described above, and if it is determined that a disturbance exists, its cause is also determined.

[0057] In step S204, the CPU 31 determines whether or not a disturbance has occurred as a result of the determination process in step S203. If it is not determined that a disturbance has occurred, the CPU 31 issues an OK notification in step S207. For example, the CPU 31 displays a notification such as a message indicating that there is no disturbance on the display unit 34. On the other hand, if it is determined that a disturbance has occurred, the CPU 31 issues an error notification in step S205. In this error notification, for example, the CPU 31 displays a notification such as a message indicating that there is a disturbance and the cause of the disturbance on the display unit 34. Note that in the OK notification and error notification, a voice notification may be issued instead of or in addition to a display.

[0058] In step S104, if the user receives the notified information and determines that there is no disturbance and that the current installation position of the sensor 10 is acceptable, the user inputs an OK command to end the disturbance determination process, or if the user wishes to redo the installation because it is not appropriate, the user inputs a command to redo the installation.

[0059] On the other hand, after steps S205 and S207, in step S206, CPU 31 waits for an OK instruction or a redo instruction from the user. If a redo instruction is input, the process returns from step S105 to step S101, and from step S206 to step S201. Therefore, in this case, the user can redo the installation of the marker in step S101, and can also perform processing to remove disturbance. In step S102, the installation of sensor 10 can be redo. In disturbance presence / absence determination device 50, distance measurement is performed again upon waiting for a distance measurement instruction.

[0060] If an OK command is input, the process shown in Fig. 7 ends. In this case, the CPU 31 can proceed to subsequent processes such as object detection and safety control.

[0061] According to this embodiment, the control unit 30 (acquisition unit 38) detects the marker 16 at a known distance L1 from the sensor 10 and within the angle of view 15 of the sensor 10. The control unit 30 (determination unit 39) obtains a measurement result including the measured distance L1x to the marker 16 by the sensor 10. Then, the control unit 30 (determination unit 39) determines whether or not there is a disturbance that may cause a measurement error within the angle of view 15 based on the measurement result and the distance L1. This makes it possible to determine the presence or absence of a disturbance in the three-dimensional distance measurement. Also, if there is a disturbance factor, it can be removed and then the distance to the marker 16 can be actually measured to perform calibration. Therefore, it is possible to perform the disturbance determination process and calibration in parallel.

[0062] Moreover, the presence or absence of multiple disturbance factors can be determined simultaneously, which is efficient. If there is a disturbance, the factor is notified, so the user can easily remove the disturbance factor.

[0063] [Second embodiment] Next, the configuration of a disturbance presence / absence determination device 50 and the procedure for installing the sensor 10 in a second embodiment of the present invention will be described. The basic configuration of the disturbance presence / absence determination device 50 is similar to that in the first embodiment. In this embodiment, the markers used are different from those in the first embodiment. Also, the installation of the markers in step S101 in Fig. 7 and a part of the discrimination method used in the process of determining the presence or absence of a disturbance and its cause executed in step S203 are different from those in the first embodiment.

[0064] 8 is a schematic diagram of a marker body including a pair of markers 16A and 16B. In the first embodiment, one marker 16 is placed at a known distance L1 from the sensor 10. In contrast, in the present embodiment, a pair of markers 16A and 16B are placed at arbitrary positions.

[0065] In the marker body, the markers 16A and 16B are integrally connected to each other so that the distance L2 between them is determined. Therefore, the distance L2 is known. Note that the markers 16A and 16B do not have to be integral, and the user may place the markers 16A and 16B so as to maintain the distance L2 during the placement stage.

[0066] In step S101, the user places markers 16A and 16B on the floor surface 11. At this time, the distance of the marker bodies from the sensor 10 does not matter. If the markers 16A and 16B have already been placed, the user may redo the placement. In step S102, the user adjusts the position and orientation of the sensor 10 so that the markers 16A and 16B are within the angle of view 15 (field of view) of the sensor 10.

[0067] In step S203, CPU 31 executes a process of determining the presence or absence of disturbance and its cause based on the measurement result and the known interval L2. The measurement result here includes the three-dimensional distance from sensor 10 to each of markers 16A and 16B. From these three-dimensional distances, CPU 31 calculates the measurement interval L2x between markers 16A and 16B.

[0068] First, the CPU 31 judges whether the calculated measurement interval L2x matches the known interval L2. At that time, a threshold value for judgment may be used, and the CPU 31 may judge that the measurement interval L2x matches the interval L2 when "interval L2-predetermined value<measurement interval L2x<interval L2+predetermined value" is established. This predetermined value is set to a value larger than the error of the measured distance L2x that may occur in the absence of disturbance, and the value is stored in the ROM 32 in advance. Then, when the measurement interval L2x does not match the interval L2, the CPU 31 judges that there is a disturbance due to any one of multipath caused by reflections other than the markers 16A and 16B, a high reflector at a short distance, or dust.

[0069] Furthermore, if the measurement interval L2x changes beyond the third threshold distance within a third predetermined time, the CPU 31 determines that there is a disturbance due to dust. Furthermore, if at least one of the distances to the two markers 16A, 16B changes beyond the fourth threshold distance within a fourth predetermined time, the CPU 31 determines that there is a disturbance due to dust. The value distance may be the same as the first predetermined time and the first threshold distance in the first embodiment, respectively.

[0070] 4, when there is a position within the angle of view 15 other than the markers 16A and 16B where the light amount exceeds the threshold light amount, the CPU 31 determines that there is a disturbance due to a nearby highly reflective object 18. Note that this threshold light amount may be the same value as the first threshold light amount in the first embodiment.

[0071] Furthermore, when the amount of light at a position corresponding to the external light 19 on a luminance screen corresponding to the screen shown in Fig. 4 exceeds a threshold amount of light, the CPU 31 determines that there is a disturbance due to the external light 19. Note that this threshold amount of light may be the same value as the second threshold amount of light in the first embodiment.

[0072] Furthermore, by appropriately setting the above-mentioned threshold light amount, the CPU 31 may determine that there is a disturbance due to either a highly reflective object in the vicinity or external light when there is a position other than the markers 16A and 16B where the light amount exceeds the threshold light amount.

[0073] Furthermore, when the position of at least one of the markers 16A and 16B within the angle of view 15 changes beyond a fifth threshold distance within a fifth predetermined time, the CPU 31 determines that there is a disturbance due to vibration. Note that the fifth predetermined time and the fifth threshold distance may be the same values ​​as the second predetermined time and the second threshold distance in the first embodiment, respectively.

[0074] According to this embodiment, the control unit 30 (acquisition unit 38) acquires a measurement result including the distances to the markers 16A and 16B by the sensor 10, in a state where the two markers 16A and 16B are arranged with a known interval L2 and the markers 16A and 16B are within the angle of view 15 of the sensor 10. Then, the control unit 30 (determination unit 39) determines whether or not there is a disturbance within the angle of view 15 that may cause a measurement error by the sensor 10, based on the measurement result and the interval L2. This makes it possible to achieve the same effect as the first embodiment in determining the presence or absence of a disturbance in three-dimensional distance measurement.

[0075] In addition, the same effects as those of the first embodiment can be achieved with respect to performing the disturbance determination process and the calibration in parallel, being able to simultaneously determine the presence or absence of multiple disturbance factors, and being notified of the disturbance factors.

[0076] In this embodiment, the detection target may be a combination of multiple possible disturbance factors among multipath, highly reflective objects in close range, external light, dust, and vibration. Also, it is not necessary to limit the disturbance factor to one, and it is useful to be able to identify the presence of any one of two or more disturbance factors.

[0077] <Modification> The above-described embodiment merely describes an exemplary configuration of the present invention. The present invention is not limited to the above-described specific embodiment, and various modifications are possible within the scope of the technical concept thereof.

[0078] It should be noted that if the effect of notifying the presence or absence of a disturbance and its cause is not desired, it is not essential for the control unit 30 to have the notification unit 40.

[0079] However, from the viewpoint of obtaining the effect of determining the presence or absence of disturbance in three-dimensional distance measurement, other types of sensors may be used as the three-dimensional distance sensor as long as they output three-dimensional distance information. When a TOF sensor is used, either a direct type or an indirect type may be used. In particular, the presence or absence of disturbance factors such as dust or vibrations When determining whether the object is a 3D object or not, the 3D distance sensor does not necessarily have to output light quantity information. Also, depending on the disturbance factor to be determined, a sensor that uses something other than light, such as radio waves, can be used.

[0080] Note that even if an OK command is input in step S206, the process shown in Fig. 7 may not end, but may be returned to step S201 and steps S201 to S206 may be repeated. In other words, the presence or absence of a disturbance may be continuously determined. For example, if the presence or absence of a disturbance is continuously determined while the hazard 13 is in operation, even if a disturbance occurs suddenly, it can be detected and immediately reported.

[0081] As another method different from the first and second embodiments, disturbance determination may be performed using two sensors with different angles of view. For example, on the condition that the marker is included in the angle of view, after obtaining a measurement result with the sensor 10, a measurement result is obtained using a second sensor with a narrower angle of view than the sensor 10. Then, if the measured distances to the marker indicated by both measurement results differ to a significant degree, it may be determined that there is some disturbance factor. For example, if the disturbance factor of interest is a multipath, a close-range high reflector, or external light, a disturbance presence / absence determination device with a simple configuration and high effectiveness can be realized.

[0082] The disturbance presence / absence determination device 50 may be configured by, for example, a computer including a processor, a memory, a storage, and the like. In this case, the configuration shown in FIG. 5 is realized by loading a program stored in the storage into the memory and executing the program by the processor. Such a computer may be a general-purpose computer such as a personal computer, a server computer, a tablet terminal, or a smartphone, or may be an embedded computer such as an on-board computer. Alternatively, all or a part of the configuration shown in FIG. 5 may be configured by ASIC, FPGA, or the like. Alternatively, all or a part of the configuration shown in FIG. 5 may be realized by cloud computing or distributed computing.

[0083] <Additional Notes> [1] An acquisition means (38) for acquiring a measurement result including a distance (L1x) to a marker (16) measured by a 3D distance sensor, the marker being placed at a known distance (L1) from the 3D distance sensor and the marker being within an angle of view of the 3D distance sensor; and a judgment means (39) for determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor, based on the measurement result acquired by the acquisition means and the known distance.

[0084] [2] An acquisition means (38) for acquiring a measurement result including the distances to the two markers by the three-dimensional distance sensor, in a state in which the two markers are arranged at a known interval (L2) and the two markers are within the angle of view of the three-dimensional distance sensor; and a judgment means (39) for determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor, based on the measurement result acquired by the acquisition means and the known interval.

[0085] [3] an acquisition step (S202) of acquiring a measurement result including a distance to the marker by the three-dimensional distance sensor, in a state in which a marker is placed at a known distance from the three-dimensional distance sensor and the marker is within an angle of view of the three-dimensional distance sensor; a determination step (S203) of determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor based on the measurement result acquired by the acquisition step and the known distance; A disturbance presence / absence determination method comprising:

[0086] [4] an acquisition step (S202) of acquiring a measurement result including each distance to the two markers by the three-dimensional distance sensor, in a state where the two markers are arranged at a known interval and the two markers are within the angle of view of the three-dimensional distance sensor; a determination step (S203) of determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional distance sensor based on the measurement result acquired by the acquisition step and the known interval; A disturbance presence / absence determination method comprising: [Explanation of symbols]

[0087] 10: Sensor 16, 16A, 16B: Markers 38: Acquisition part 39: Judgment section 40: Notification Department 50: Disturbance detection device L1: distance L1x: Measurement distance

Claims

1. A disturbance presence / absence determination device that determines whether or not there is a disturbance that may cause a measurement error within a monitoring area of ​​a three-dimensional TOF sensor, an acquisition means for acquiring a measurement result including a distance to the marker by the three-dimensional TOF sensor, the measurement result including a distance to the marker being placed at a known distance from the three-dimensional TOF sensor in the monitoring area and the marker being within an angle of view of the three-dimensional TOF sensor; a determination means for performing a first determination process for determining whether or not there is a disturbance based on the measurement result acquired by the acquisition means and the known distance, and a second determination process for determining that there is a disturbance due to dust when the distance to the marker indicated by the measurement result acquired by the acquisition means changes by exceeding a first threshold distance within a first predetermined time; A disturbance presence / absence determining device comprising:

2. The three-dimensional TOF sensor is a sensor that obtains distance information to a measurement target based on light reflected by the measurement target, 2. The disturbance presence / absence determining device according to claim 1, wherein the first determination process includes a process of determining that there is a disturbance due to a multipath caused by reflections other than the object to be measured when the measurement result indicates that the distance to the marker is longer than the known distance.

3. The three-dimensional TOF sensor is a sensor that obtains distance information to a measurement target based on light reflected by the measurement target, the measurement result includes light amount information for each position within the angle of view, 3. The disturbance determination device according to claim 1, wherein the first determination process includes a process of determining that there is a disturbance caused by a highly reflective object in the vicinity when the measurement result indicates that the distance to the marker is shorter than the known distance and when there is a position other than the marker within the angle of view where the light amount exceeds a first threshold light amount.

4. the measurement result includes light amount information for each position within the angle of view, The determining means further performs a third determining process for determining that there is a disturbance due to external light when there is a position other than the marker within the angle of view where the light amount exceeds a second threshold light amount.

3. The disturbance determination device according to claim 1, further comprising a process for determining whether or not a disturbance has occurred.

5. The disturbance presence / absence determination device according to any one of claims 1 to 4, characterized in that the determination means further performs a fourth determination process of determining that there is a disturbance due to vibration if the position of the marker within the angle of view indicated by the measurement result changes by more than a second threshold distance within a second predetermined time.

6. A disturbance presence / absence determination device that determines whether or not there is a disturbance that may cause a measurement error within a monitoring area of ​​a three-dimensional TOF sensor, an acquisition means for acquiring a measurement result including each distance to the two markers by the three-dimensional TOF sensor, in a state in which two markers are arranged at any position in the monitoring area with a known interval therebetween and the two markers are within an angle of view of the three-dimensional TOF sensor; a determination means for performing a first determination process for determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional TOF sensor, based on the measurement result acquired by the acquisition means and the known interval; having The first determination process includes a process of calculating the distance between the two markers based on the distances to the two markers acquired by the acquisition means, and determining that there is a disturbance due to dust if the calculated distance between the two markers changes by more than a third threshold distance within a third predetermined time.

7. A disturbance presence / absence determination device for determining whether or not there is a disturbance that may cause a measurement error within a monitoring area of ​​a three-dimensional TOF sensor, an acquisition means for acquiring a measurement result including each distance to the two markers by the three-dimensional TOF sensor, in a state in which two markers are arranged at any position in the monitoring area with a known interval therebetween and the two markers are within an angle of view of the three-dimensional TOF sensor; a determination means for performing a first determination process for determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional TOF sensor, based on the measurement result acquired by the acquisition means and the known interval; having The disturbance determination device is further characterized in that the determination means performs a second determination process to determine that there is a disturbance caused by dust if at least one of the distances to the two markers acquired by the acquisition means changes by more than a fourth threshold distance within a fourth predetermined time.

8. The three-dimensional TOF sensor is a sensor that obtains distance information to a measurement target based on light reflected by the measurement target, the measurement result includes light amount information for each position within the angle of view, 8. The disturbance presence / absence determining device according to claim 6 or 7, characterized in that the determining means further performs a third determination process of determining that there is a disturbance due to either a highly reflective object in the vicinity or external light when there is a position within the angle of view other than the two markers where the light amount exceeds a threshold light amount.

9. The disturbance presence / absence determining device according to any one of claims 6 to 8, characterized in that the determination means further performs a fourth determination process of determining that there is a disturbance due to vibration when a position within the angle of view of at least one of the two markers indicated by the measurement result has changed by more than a fifth threshold distance within a fifth predetermined time.

10. 10. The disturbance presence / absence determining device according to claim 1, further comprising a notification means for notifying a result of the determination made by said determination means.

11. A disturbance presence / absence determination method for determining whether or not there is a disturbance that may cause a measurement error within a monitoring area of ​​a three-dimensional TOF sensor, comprising: an acquisition step of acquiring a measurement result including a distance to the marker by the three-dimensional TOF sensor, the measurement result including the distance to the marker being placed at a known distance from the three-dimensional TOF sensor in the monitoring area and the marker being within an angle of view of the three-dimensional TOF sensor; A method for determining whether or not there is a disturbance, comprising: a determination step of performing a first determination process of determining whether or not there is a disturbance based on the measurement result obtained by the acquisition step and the known distance; and a second determination process of determining that there is a disturbance due to dust if the distance to the marker indicated by the measurement result obtained by the acquisition step changes by more than a first threshold distance within a first predetermined time.

12. A disturbance presence / absence determination method for determining whether or not there is a disturbance that may cause a measurement error within a monitoring area of ​​a three-dimensional TOF sensor, comprising: an acquisition step of acquiring a measurement result including each distance to the two markers by the three-dimensional TOF sensor, in a state where two markers are arranged at any position in the monitoring area with a known interval therebetween and the two markers are within an angle of view of the three-dimensional TOF sensor; A determination step of performing a first determination process of determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional TOF sensor, based on the measurement result acquired by the acquisition step and the known interval, The first determination process includes a process of calculating the distance between the two markers based on the distances to the two markers acquired in the acquisition step, and determining that there is a disturbance due to dust if the calculated distance between the two markers changes by more than a third threshold distance within a third predetermined time.

13. A disturbance presence / absence determination method for determining whether or not there is a disturbance that causes a measurement error within a monitoring area of ​​a three-dimensional TOF sensor, comprising: an acquisition step of acquiring a measurement result including each distance to the two markers by the three-dimensional TOF sensor, in a state where two markers are arranged at any position in the monitoring area with a known interval therebetween and the two markers are within an angle of view of the three-dimensional TOF sensor; A determination step of performing a first determination process of determining whether or not there is a disturbance that may cause a measurement error by the three-dimensional TOF sensor, based on the measurement result acquired by the acquisition step and the known interval, The method for determining whether or not there is a disturbance is characterized in that, in the determination step, a second determination process is performed in which, if at least one of the distances to the two markers acquired in the acquisition step changes by more than a fourth threshold distance within a fourth predetermined time, it is determined that there is a disturbance caused by dust.

14. A program for causing a computer to execute each step of the disturbance determination method according to claim 12 or 13.

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