Point cloud measurement method and point cloud measurement device

Abstract

To provide a point cloud measurement device and a point cloud measurement device capable of accurately calculating a shape of a structure even in foggy environment.SOLUTION: A point cloud measurement method for measuring the shapes of structures 11 to 13 comprises a first step of acquiring each measurement point of a point cloud sensor 2 and a millimeter wave radar 1, a second step of grouping point clouds, which are a collection of measurement points of the point cloud sensor 2, such that a distance between any measurement point of one group and any measurement point of another group is equal to or greater than a predetermined threshold, a third step of determining whether or not a measurement point of the millimeter wave radar 1 exists within a range of each grouped point cloud, and a fourth step of calculating the shapes of the structures 11 to 13 based on each point cloud of groups 21 to 23 in which it is determined that a measurement point of the millimeter wave radar 1 exists.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method or apparatus for point cloud measurement of a structure.

Background Art

[0002] There is a point cloud measurement technique for measuring the shape of the surface of a structure by transmitting visible light or near-infrared light from a sensor while scanning in the transmission direction, receiving the light reflected from the surface of the structure with the sensor, and measuring the propagation time until the reflected light returns to the sensor. When performing such point cloud measurement in an environment where fog is present, there are problems such as a decrease in measurement sensitivity due to light shielding by fog particles and erroneous measurement due to light scattering by fog particles. For this reason, even in an environment where fog is present, a method has been proposed for reducing the influence of fog and reliably measuring the shape of the structure that should originally be measured. As a technique for reliably measuring the point cloud of a structure in a fog environment, for example, Patent Document 1 can be cited.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above technique discriminates the measured reflection point cloud by utilizing the difference that light reflects but does not transmit on the surface of a physical structure, and light reflects and transmits in irregularly shaped fog. A plurality of reflection points are grouped into a reflection point cloud. When a second reflection point exists on the scanning line passing through the first group and the ratio of the second reflection point to the first reflection point is a predetermined value or more, the first group is determined to be fog.

[0005] This method carries the risk of misidentification if only one group exists on the scan line of light, as it cannot compare the second and first reflection points. Furthermore, while it can distinguish between the reflection points of a structure and those of the fog when only one group of fog is present, it also carries the risk of misidentification when two or more groups of fog are present.

[0006] The present invention has been made in view of the above problems, and its purpose is to provide a point cloud measurement method and a point cloud measurement device that can accurately calculate the shape of a structure even in a foggy environment. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a point cloud measurement method for measuring the shape of a structure, comprising a first step of acquiring each measurement point of a point cloud sensor and a millimeter-wave radar, If there are no measurement points of the point cloud sensor near each measurement point of the millimeter-wave radar, the second step is to switch the sensitivity of the point cloud sensor and then perform the first step again; and if there are measurement points of the point cloud sensor near each measurement point of the millimeter-wave radar, The point cloud, which is a collection of measurement points from the point cloud sensor, is grouped such that the distance between any measurement point in one group and any measurement point in another group is greater than or equal to a predetermined threshold. Step 3 Then, it is determined whether or not a measurement point of the millimeter-wave radar exists within the range of each grouped point cloud. Step 4 Then, the shape of the structure is calculated based on the point clouds of each group in which the millimeter-wave radar measurement points are determined to exist. Step 5 It shall have the following characteristics.

[0008] Furthermore, the present invention relates to a point cloud measurement device for measuring the shape of a structure, comprising a point cloud sensor, a millimeter-wave radar, and a computing device, wherein the computing device acquires each measurement point of the point cloud sensor and the millimeter-wave radar. If there are no measurement points of the point cloud sensor near any of the measurement points of the millimeter-wave radar, the sensitivity of the point cloud sensor is switched, and then the measurement points of the point cloud sensor and the millimeter-wave radar are acquired again. If there are measurement points of the point cloud sensor near any of the measurement points of the millimeter-wave radar, The point cloud, which is a collection of measurement points from the point cloud sensor, is grouped such that the distance between any measurement point in one group and any measurement point in another group is greater than or equal to a predetermined threshold. It is then determined whether or not measurement points of the millimeter-wave radar exist within the range of each grouped point cloud, and the shape of the structure is calculated based on the point cloud of the group in which it is determined that measurement points of the millimeter-wave radar exist. [Effects of the Invention]

[0009] According to the present invention, by distinguishing between the point cloud of structures and the point cloud of fog based on measurement points of millimeter-wave radar, it becomes possible to accurately calculate the shape of structures even in foggy environments. [Brief explanation of the drawing]

[0010] [Figure 1] This is an explanatory diagram showing the arrangement of the structure to be measured and the measurement sensor in the first embodiment of the present invention. [Figure 2] This is a configuration diagram showing the configuration of the measuring instrument in the first embodiment of the present invention. [Figure 3] This is a flowchart showing the work procedure in the first embodiment of the present invention. [Figure 4] This is an explanatory diagram showing the measurement results when the sensitivity of the point cloud sensor is inappropriate in the first embodiment of the present invention. [Figure 5] This is an explanatory diagram showing the measurement results when the sensitivity of the point cloud sensor is appropriate in the first embodiment of the present invention. [Figure 6] This is an explanatory diagram illustrating the grouping of measured point clouds in the first embodiment of the present invention. [Figure 7] This is an explanatory diagram illustrating the calculation of the outer diameter of a structure in the first embodiment of the present invention. [Figure 8] This is an explanatory diagram illustrating the calculation of the distance of a structure in the first embodiment of the present invention. [Figure 9] This is an explanatory diagram showing the arrangement of the structure to be measured and the measurement sensor in a second embodiment of the present invention. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In each figure, equivalent elements are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. [Examples]

[0012] A first embodiment of the present invention will be described with reference to Figures 1 to 8.

[0013] In the first embodiment, two pipes and one rectangular structure, which are part of the equipment installed indoors, are the measurement targets. There is a risk that the outer wall of the building (not shown) may collapse due to an earthquake and part of the equipment may also be deformed. Also, since the outer wall has collapsed, the environment inside the building is such that fog is generated. As shown in FIG. 1, part of the equipment is composed of pipe 11, pipe 12, and rectangular structure 13. There are a plurality of structures (not shown) in the back of the building, but since some paths have become impassable due to the earthquake, to reach the back of the building, it is necessary to pass between pipe 11 and pipe 12, or between pipe 12 and rectangular structure 13. Since there is a risk that the building and the structures inside the building may further collapse, it is desired to investigate and perform restoration work on the back of the building with a remote device. However, when selecting an investigation device or a work device, it is necessary to know the distance between pipe 11 and pipe 12, and the distance between pipe 12 and rectangular structure 13.

[0014] A millimeter-wave radar 1 for measuring a structure and an active stereo type point cloud sensor 2 were arranged on a stand 3 (FIG. 1). Note that the data of the millimeter-wave radar 1 is recorded by a millimeter-wave data recording unit 4, and the data of the point cloud sensor 2 is recorded by a point cloud data recording unit 5. The millimeter-wave data and the point cloud data are configured to be calculated and analyzed by a PC 6 (FIG. 2).

[0015] The following steps will be followed according to the flowchart in Figure 3. First, the structure is measured using millimeter-wave radar 1 and point cloud sensor 2 (steps F1, F2). A plan view of the measurement results is shown in Figure 4. Measurement points measured by millimeter-wave radar 1 are indicated by diamonds, and measurement points measured by point cloud sensor 2 are indicated by circles. At the time of measurement, fog 14 and fog 15 were present. Since millimeter-wave radar 1 receives reflected waves from the direct opposite direction without being affected by fog, it measured one reflection point each at pipe 11, pipe 12, and rectangular structure 13, and did not measure reflection points at the locations of fog 14 and fog 15. Check whether there are point clouds measured by point cloud sensor 2 near each measurement point of millimeter-wave radar 1 (step F3). Since no point clouds were measured, it is determined that the sensitivity of point cloud sensor 2 is inappropriate. The sensitivity of point cloud sensor 2 is switched to the high-sensitivity side (step F4), and measurements are retaken with millimeter-wave radar 1 and point cloud sensor 2 (steps F1, F2). A plan view of the retake results is shown in Figure 5. Because the sensitivity of point cloud sensor 2 was optimized, point clouds were measured on the surfaces of pipes 11 and 12 and rectangular structure 13 facing the sensor, but point clouds were also measured at the locations of fog 14 and fog 15.

[0016] The point cloud, which is a collection of measurement points from point cloud sensor 2, is grouped such that the distance between any measurement point in one group and any measurement point in another group is greater than or equal to a predetermined threshold (step F5). The result of grouping the point cloud is shown in Figure 6. Note that even when the fog and structure are close together, if the fog density is constant, the signal strength is high at the front of the fog, and the signal strength gradually decreases as the distance from the sensor increases. Therefore, if the sensor, fog, and structure are arranged in that order, the front of the fog is easily measured as a point cloud, and the back side is not easily measured as a point cloud, so it is unlikely that the fog point cloud and the structure point cloud will be recognized as belonging to the same group. Also, fog consists of lightweight, small-diameter water droplets that can float in the air, and each droplet moves randomly in the air. When a water droplet comes into contact with a structure as it moves, that droplet adheres to the structure and ceases to be fog. For this reason, a gap is created between the structure and the fog up to a distance corresponding to the average value of the random movement of the water droplets from the surface of the structure. Even if fog and structures appear close together, the existence of this gap allows us to separate the fog from the structure.

[0017] When checking whether there are measurement points of the millimeter-wave radar 1 within the ranges of each of the groups 21 to 25 (step F6), it is found that there are measurement points of the millimeter-wave radar within the ranges of groups 21 to 23, and there are no measurement points of the millimeter-wave radar within the ranges of groups 24 and 25. It is determined that groups 24 and 25 are fog groups and made non-display (step F7), and it is determined that groups 21 to 23 are groups of the structures 11 to 13. Based on groups 21 to 23, the shapes of the structures 11 to 13 are calculated and displayed (step F8). With groups 24 and 25 made non-display, a plan sectional view showing the shape 31 of the pipe 11, the shape 33 of the pipe 12, and the shape 33 of the rectangular structure 13 is shown in FIG. 7. Also, for groups 21 and 22, since the point groups are located in a semi-cylindrical shape, it can be determined that they are cylindrical structures, so the extrapolated shapes 36 and 37 of the shapes 33 and 34 are also calculated and displayed. By calculating the shortest distance between the calculated shape 31 or extrapolated shape 36 and the shape 32 or extrapolated shape 37 (step F9), the distance 38 between the pipe 11 and the pipe 12 can be calculated. Also, by calculating the shortest distance between the shape 32 or extrapolated shape 37 and the shape 33, the distance 39 between the pipe 12 and the rectangular structure 13 can be calculated. The results are shown in FIG. 8.

[0018] As described above, when performing arithmetic processing on the measurement points of the millimeter-wave radar 1 and the point groups measured by the point group sensor 2, even in an environment where fog is occurring, it is possible to calculate the outer shapes of the structures 11 to 13 without being affected by the fog, and calculate the distances 38 and 39 between the structures 11 to 13.

[0019] In this embodiment, in the point group measurement method for measuring the shapes of the structures 11 to 13, a first step of acquiring each measurement point of the point group sensor 2 and the millimeter-wave radar 1, and If there are no measurement points of the point cloud sensor 2 near each measurement point of the millimeter-wave radar 1, the second step is to switch the sensitivity of the point cloud sensor 2 and then perform the first step again, and if there are measurement points of the point cloud sensor 2 near each measurement point of the millimeter-wave radar 1, grouping the point groups, which are the set of measurement points of the point group sensor 2, such that the distance between an arbitrary measurement point of one group and an arbitrary measurement point of another group is equal to or greater than a predetermined threshold value Step 3 and determining whether there are measurement points of the millimeter-wave radar 1 within the ranges of each of the grouped point groups Step 4Based on the point clouds of groups 21-23, where millimeter-wave radar 1 measurement points were determined to exist, the shapes of structures 11-13 are calculated. Step 5 It has the following. Alternatively, in this embodiment, the point cloud measuring device 10 for measuring the shape of structures 11 to 13 comprises a point cloud sensor 2, a millimeter-wave radar 1, and a PC 6 (computer), and the PC 6 (computer) acquires each measurement point of the point cloud sensor 2 and the millimeter-wave radar 1. If there are no measurement points of point cloud sensor 2 near each measurement point of millimeter-wave radar 1, the sensitivity of point cloud sensor 2 is switched, and then each measurement point of point cloud sensor 2 and millimeter-wave radar 1 is acquired again. If there are measurement points of point cloud sensor 2 near each measurement point of millimeter-wave radar 1, The point cloud, which is a collection of measurement points from the point cloud sensor 2, is grouped such that the distance between any measurement point in one group and any measurement point in another group is greater than or equal to a predetermined threshold. It is then determined whether or not measurement points of the millimeter-wave radar 1 exist within the range of each grouped point cloud. Based on the point clouds of groups 21 to 23, in which it is determined that measurement points of the millimeter-wave radar 1 exist, the shapes of structures 11 to 13 are calculated.

[0020] According to this embodiment configured as described above, by distinguishing between the point clouds of structures 11-13 and the point clouds of fog 14 and 15 based on the measurement points of the millimeter-wave radar 1, it becomes possible to accurately calculate the shapes of structures 11-13 even in a foggy environment.

[0021] Furthermore, the point cloud measurement method in this embodiment is as described above. Step 5 The spacing 38 and 39 between two adjacent shapes of structures 11 to 13, calculated from the shapes of structures 11 to 13, is used as the gap width between structures 11 to 13. Step 6 It has the following characteristics. Alternatively, in this embodiment, the PC6 (calculation unit) calculates the gap width between structures 11 to 13 by the intervals 38 and 39 between two adjacent shapes from among the shapes of structures 11 to 13. This makes it possible to accurately calculate the gap width (intervals 38 and 39) between structures 11 to 13.

[0022] Furthermore, in the point cloud measurement method of this embodiment, Step 4 Then, if it is determined that there are no measurement points of the millimeter-wave radar 1 within the range of each grouped point cloud, the sensitivity of the point cloud sensor 2 is switched, and then the process proceeds from the first step to the first step. Step 4 Run the process again. This will ensure that the point cloud data for structures 11-13 is acquired.

[0023] Furthermore, in this embodiment Step 5 The method includes the steps of determining whether each grouped point cloud is located in a semi-cylindrical shape, and calculating the shape of structures 11 and 12 by extrapolating the point clouds of groups 21 and 22 that have been determined to be located in a semi-cylindrical shape. This makes it possible to calculate the overall shape of structures 11 and 12 even if only a portion of the point clouds of the cylindrical structures 11 and 12 can be measured. [Examples]

[0024] A second embodiment of the present invention will be described with reference to Figure 9.

[0025] In the second embodiment, when an unintended chemical reaction occurs in a tank storing chemicals, causing the tank to rupture and some of its contents to leak out, the constraint dimensions of an investigation device to be inserted into the tank through an opening are investigated.

[0026] As shown in Figure 9, an opening 62 has formed in tank 61, and reaction products 63 are leaking out. A mist (not shown) due to smoke continues to form near tank 61. Furthermore, because the composition of the reaction products 63 is unknown, workers cannot approach tank 61. In order to select a remote device to investigate the inside of tank 61, it is necessary to know the dimensions of the opening 62.

[0027] A millimeter-wave radar 51 and a point cloud sensor 52 for measuring structures are placed on the traveling device 53. Data from the millimeter-wave radar 51 is recorded by the millimeter-wave data acquisition unit 54, and data from the point cloud sensor 52 is recorded by the point cloud data acquisition unit 55. The millimeter-wave data and point cloud data are processed and analyzed by the PC 56. The traveling device 53 can move according to instructions from the travel instruction unit 57, and the device position and angle (orientation) after movement can be calculated by the device position / angle detection unit 58 based on sensor signals such as a distance meter and a magnetic sensor (not shown) attached to the traveling device 53.

[0028] Similar to the first embodiment, measurements are performed using the millimeter-wave radar 51 and point cloud sensor 52 according to the procedure shown in Figure 3, making it possible to calculate the outline of the structure 61 and refer to the dimensions of the opening 62 without being affected by fog, even in a foggy environment. Furthermore, if it is desired to further improve the measurement accuracy, the traveling device 53 can be moved to other positions (positions A, B) and measurements can be repeated, and the point clouds measured at different positions or directions can be analyzed together to improve the measurement accuracy.

[0029] (summary) In the point cloud measurement method of this embodiment, the first step of acquiring each measurement point of the point cloud sensor 52 and millimeter-wave radar 51 includes the steps of acquiring each measurement point of the point cloud sensor 52 and millimeter-wave radar 51 at a plurality of measurement positions or measurement directions, and summing the measurement points of the point cloud sensor 52 and millimeter-wave radar 51 measured at the plurality of measurement positions or measurement directions in a coordinate system fixed to the environment. Alternatively, the point cloud measurement device 50 in this embodiment is equipped with a point cloud sensor 52 and a millimeter-wave radar 51, and includes a travel device 53 that can change the measurement position or measurement direction of the point cloud sensor 52 and millimeter-wave radar 51, and the PC 56 (calculation unit) acquires each measurement point of the point cloud sensor 52 and millimeter-wave radar 51 at a plurality of measurement positions or measurement directions, and sums the measurement points of the point cloud sensor 52 and millimeter-wave radar 51 measured at the plurality of measurement positions or measurement directions in a coordinate system fixed to the environment.

[0030] According to this embodiment configured as described above, by measuring the structure 61 with the point cloud sensor 52 and millimeter-wave radar 51 at multiple measurement positions or directions, it becomes possible to more accurately calculate the shape of the structure 61 and the gap width of the structure 61 (width of the opening 62).

[0031] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above and includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Furthermore, it is possible to add parts of the configuration of one embodiment to the configuration of another embodiment, and it is also possible to delete parts of the configuration of one embodiment or replace parts of parts of another embodiment. [Explanation of Symbols]

[0032] 1...Millimeter-wave radar, 2...Point cloud sensor, 3...Unit, 4...Millimeter-wave data acquisition unit, 5...Point cloud data acquisition unit, 6...PC (Computer Programming Unit), 10...Point cloud measurement device, 11,12...Piping (structure), 13...Rectangular structure, 14,15...Fog, 21~25...Group, 31~34...Shape, 36,37...Extrapolated shape, 38,39...Spacing, 50...Point cloud measurement device, 51...Millimeter-wave radar, 52...Point cloud sensor, 53...Traveling device, 54...Millimeter-wave data acquisition unit, 55...Point cloud data acquisition unit, 56...PC (Computer Programming Unit), 57...Travel instruction unit, 58...Device position / angle detection unit, 61...Tank (structure), 62...Opening, 63...Reaction product.

Claims

1. In a point cloud measurement method for measuring the shape of a structure, The first step involves acquiring each measurement point from the point cloud sensor and millimeter-wave radar, If there are no measurement points of the point cloud sensor near any of the measurement points of the millimeter-wave radar, the second step involves switching the sensitivity of the point cloud sensor and then repeating the first step. A third step is to group the point cloud, which is a collection of measurement points of the point cloud sensor, in the case where a measurement point of the point cloud sensor is located near each measurement point of the millimeter-wave radar, such that the distance between any measurement point in one group and any measurement point in another group is greater than or equal to a predetermined threshold, A fourth step involves determining whether or not a measurement point of the millimeter-wave radar exists within the range of each grouped point cloud, The fifth step involves calculating the shape of the structure based on the point clouds of the group in which measurement points of the millimeter-wave radar are determined to exist. A point cloud measurement method characterized by the following:

2. In the point cloud measurement method described in claim 1, The process includes a sixth step in which the distance between two adjacent shapes of the structure calculated in the fifth step is calculated as the gap width of the structure. A point cloud measurement method characterized by the following:

3. In the point cloud measurement method described in claim 1, The fifth step described above is: A step to determine whether each grouped point cloud is positioned in a semi-cylindrical shape, The method comprises the steps of calculating the shape of the structure by extrapolating the point cloud of the group determined to be located in a semi-cylindrical shape. A point cloud measurement method characterized by the following:

4. In the point cloud measurement method described in claim 1, The first step is, The steps include acquiring each measurement point of the point cloud sensor and the millimeter-wave radar at multiple measurement positions or measurement directions, The method includes the step of summing the measurement points of the point cloud sensor and the millimeter-wave radar, measured at the plurality of measurement positions or measurement directions, in a coordinate system fixed to the environment. A point cloud measurement method characterized by the following:

5. In a point cloud measurement device for measuring the shape of a structure, Point cloud sensor and, Millimeter-wave radar and, Equipped with a computing device, The aforementioned computing device is The measurement points of the point cloud sensor and the millimeter-wave radar are acquired, If no measurement points of the point cloud sensor are present near any of the measurement points of the millimeter-wave radar, the sensitivity of the point cloud sensor is switched, and then the measurement points of the point cloud sensor and the millimeter-wave radar are acquired again. When a measurement point of the point cloud sensor is located near each measurement point of the millimeter-wave radar, the point cloud, which is a collection of measurement points of the point cloud sensor, is grouped such that the distance between any measurement point in one group and any measurement point in another group is greater than or equal to a predetermined threshold. Determine whether or not a measurement point of the millimeter-wave radar exists within the range of each grouped point cloud. The shape of the structure is calculated based on the point cloud of the group in which measurement points of the millimeter-wave radar are determined to exist. A point cloud measurement device characterized by the following features.

6. In the point cloud measuring device according to claim 5, The calculation device calculates the gap width of the structure by determining the distance between two adjacent shapes among the shapes of the structure. A point cloud measurement device characterized by the following features.

7. In the point cloud measuring device according to claim 5, The point cloud sensor and the millimeter-wave radar are mounted on a traveling device capable of changing the measurement position or measurement direction of the point cloud sensor and the millimeter-wave radar, The calculation device acquires measurement points from the point cloud sensor and the millimeter-wave radar at multiple measurement positions or directions, and sums the measurement points from the point cloud sensor and the millimeter-wave radar measured at the multiple measurement positions or directions in a coordinate system fixed to the environment. A point cloud measurement device characterized by the following features.

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