Segment Measurement System

Abstract

A segment measurement system is provided that improves measurement accuracy by directly measuring segment positions. [Solution] The segment measurement system S is a segment measurement system S that measures the tail clearance, segment circularity, and / or segment end face of an earth pressure shield 1 as a shield tunneling machine, and is equipped with a measurement unit 40 having a non-contact distance sensor 41, a rotation mechanism 42 that rotates the distance sensor 41, and a rotation position detection unit 43 that detects the rotation position of the distance sensor 41 by the rotation mechanism 42; and a calculation unit 60 that calculates the tail clearance, segment circularity, and / or orientation of the segment end face based on the measurement results of the reflection intensity of the end face 90a of the segment 90 and the measurement results of multiple points on the inner surface of the skin plate 2.

Description

[Technical Field]

[0001] The present invention relates to a segment measurement system that measures tail clearance, segment roundness, and / or segment surface orientation in a non-contact manner. [Background technology]

[0002] A technique for measuring tail clearance without contact when excavating a tunnel with a shield machine has been known for some time. Here, tail clearance refers to the gap between the skin plate of the shield machine and the segments. Tail clearance must be controlled within an allowable range to prevent contact between the skin plate and the segments during curved construction, etc.

[0003] Existing tail clearance measurement methods require the angular positions of the segment end faces to be recognized, which requires the calculation of multiple line segments from point cloud data obtained by a sensor. For example, the measurement method described in Patent Document 1 estimates the tail clearance by estimating the lines tangent to the segment inner surface, segment end face, and shield inner surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-214834 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although conventional measurement methods are based on measured values, they estimate tail clearance by extrapolating multiple survey line data from the measured values, which means that errors during scanning can accumulate exponentially.

[0006] Therefore, an object of the present invention is to provide a segment measurement system that improves measurement accuracy by directly measuring the segment position. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the segment measurement system of the present invention is a segment measurement system that measures the tail clearance and / or end faces of segments of a shield tunneling machine, and is equipped with a measurement unit having a non-contact distance sensor, a rotation mechanism that rotates the distance sensor, and a rotation position detection unit that detects the rotation position of the distance sensor by the rotation mechanism; and a calculation unit that calculates the tail clearance, segment circularity, and / or orientation of the segment end face based on the measurement results of the reflection intensity of the end face of the segment and the measurement results of multiple points on the inner surface of the skin plate. [Effects of the Invention]

[0008] The segment measurement system of the present invention is a segment measurement system that measures the tail clearance, segment roundness, and / or segment end faces of a shield tunneling machine, and is equipped with a measurement unit that has a non-contact distance sensor, a rotation mechanism that rotates the distance sensor, and a rotation position detection unit that detects the rotation position of the distance sensor using the rotation mechanism; and a calculation unit that calculates the tail clearance, segment roundness, and / or the orientation of the segment end face based on the measurement results of the reflection intensity of the segment end face and the measurement results of multiple points on the inner surface of the skin plate. With this configuration, the segment position is directly measured, resulting in a segment measurement system with improved measurement accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view illustrating the internal structure of a shield tunneling machine. [Figure 2] FIG. 2 is a side view of a measurement unit of the segment measurement system. [Figure 3] FIG. 2 is a perspective view of a measurement unit of the segment measurement system. [Figure 4] FIG. 1 is a block diagram illustrating a system configuration of a segment measurement system. [Figure 5] FIG. 10 is an explanatory diagram illustrating measurement of a skin plate. [Figure 6] 1A and 1B are explanatory views illustrating painting on the end faces of the segments, where (a) is a front view of the entire segment and (b) is an enlarged front view. [Figure 7] FIG. 10 is an explanatory diagram illustrating measurement of a segment end face. [Figure 8] 1A and 1B are explanatory diagrams illustrating the surface orientation of a segment end face, where (a) is an explanatory diagram illustrating the concept of surface orientation, and (b) is an explanatory diagram of a direction correcting segment. [Figure 9] 1A and 1B are explanatory diagrams illustrating concepts related to the circularity of a segment, where FIG. 1A is an explanatory diagram illustrating the concept of circularity, and FIG. 1B is an explanatory diagram illustrating tail clearance at an arbitrary position. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the components described in the following embodiments are merely examples and are not intended to limit the technical scope of the present invention to those alone. Note that, although the following description will be given using an earth pressure shield 1 as an example, the present invention can also be applied to other types of shield tunneling machines. [Example]

[0011] (Shield tunneling machine configuration) Fig. 1 is a longitudinal side view showing a first embodiment of the present invention. As shown in Fig. 1, the earth pressure shield 1 as a shield tunneling machine of this embodiment is equipped with a skin plate (shield main body cylinder) 2, a partition wall 3, a cutter head 5, a cutter rotation shaft 10, a cutter drive unit 12, a chamber 16, an earth removal device 17, a shield propulsion jack 18, a mud-making material supply pipe 21, an earth pressure gauge 22, and a monitor (71; see Fig. 4) and a control unit (60; see Fig. 4) including a calculation unit, which are arranged inside an operation room.

[0012] The cutter head 5 has cutter spokes 51, a plurality of cutter bits 52, ... provided on the front surface of the cutter spokes 51, a fishtail bit 53 provided in the center of the front surface of the cutter spokes 51, and a plurality of stirring blades 54 provided on the back surface of the cutter spokes 51. The cutter head 5 is attached integrally to the cutter rotation shaft 10.

[0013] The cutter rotation shaft 10 is rotatably supported by a bearing 11 provided in the partition wall 3 and a bearing provided at the rear of a gear box 13 (described later). The cutter rotation shaft 10 is connected to a cutter drive unit 12. The cutter drive unit 12 has a gear box 13 installed on the rear side of the partition wall 3, a rotary drive source 14 connected to the gear box 13, and a reduction gear (disposed within the gear box 13; not shown) interposed between the output shaft of the rotary drive source 14 and the cutter rotation shaft 10.

[0014] The chamber 16 is formed as a space surrounded by the hood portion of the skin plate 2, the partition wall 3, and the tunnel face F. A screw conveyor is used as the earth removal device 17. The mud intake port of the earth removal device 17 is open and installed so as to face the chamber 16. Furthermore, an erector 15 for assembling the segments 90 is installed at the tail portion of the skin plate 2.

[0015] As shown in FIG. 6( a), the segment 90 of this embodiment has a predetermined width painted white (light) in the center (half) of the girder height on its end face 90a facing the face, and the remaining area painted black (dark). While the case where the entire 360-degree circumference is colored has been described here, this is not a limitation, and the coloring may be applied only to the four locations that are actually measured. Furthermore, the distinction between light and dark is not limited to coloring; colored stickers or colored panels (plates) can also be used. In this embodiment, the colored position (predetermined position) is described as being in the area including the center (half) of the girder height. However, this area is not limited to the area including the center (half). For example, the coloring may be in the area including one-third of the girder height or two-thirds of the girder height.

[0016] A plurality of shield propulsion jacks 18 are installed at required intervals in the circumferential direction inside the skin plate 2. Each shield propulsion jack 18 is composed of a piston portion 18a and a spreader portion 18b. In addition, a tail seal 19 is provided at the rear end portion of the skin plate 2. A measurement portion 40 of the segment measurement system S is installed near the shield propulsion jack 18 of this embodiment.

[0017] That is, the distance sensor 41 constituting the measurement unit 40 is disposed radially outward of the inner surface of the segment 90, as shown in Fig. 2. However, the distance sensor 41 can also be disposed radially inward of the shield. Specifically, the measurement unit 40 including the distance sensor 41 is disposed near the center position of the shield propulsion jack 18 in the radial direction of the shield by a bracket 40a protruding from the bulkhead 3. The measurement unit 40 including the distance sensor 41 may be fixed to the skin plate 2 side, or may be attached directly to the bulkhead 3 without the bracket 40a.

[0018] (Configuration of segment measurement system) Next, the configuration of the segment measurement system S will be described with reference to Figures 2 to 4. As shown in Figure 4, the segment measurement system S is mainly composed of a measurement unit 40 and a control unit 60 as a calculation unit.

[0019] 2 and 4, the measurement unit 40 is a so-called 2D-LIDAR and has a non-contact distance sensor 41, a rotation mechanism 42 such as a motor and gear that rotates the distance sensor 41, and a rotation position detection unit 43 that detects the rotation position of the distance sensor 41 caused by the rotation mechanism 42. Of these, the rotation mechanism 42 has a rotation axis that is perpendicular to the shield radial direction (and perpendicular to the tunnel longitudinal direction). Therefore, the distance sensor 41 of the measurement unit 40 can scan the face-facing end face 90a of the segment 90 and the inner surface of the tail portion of the skin plate 2 along a plane parallel to the tunnel longitudinal direction (scanning plane; plane passing through the shield central axis).

[0020] As described above with reference to Figure 2, the measurement unit 40 including the distance sensor 41 is preferably (but not limited to) positioned radially outward of the inner surface of the segment 90. Furthermore, the measurement unit 40 (distance sensor 41) in this embodiment is positioned exactly in the vicinity of the center of the two shield propulsion jacks 18, 18 in the circumferential direction of the earth pressure shield 1 as a shield tunneling machine, as shown in Figure 3.

[0021] The position of the distance sensor 41 in the tunnel longitudinal direction (shield excavation direction) may be closer to the tunnel face (forward) than the spreader section 18b when the shield propulsion jack 18 is in its most shortened state. Furthermore, although not shown, it is preferable that the measurement section 40 including the distance sensor 41 be installed in at least three or more locations in the shield circumferential direction.

[0022] More specifically, as will be described later in Example 2, it is preferable that the measurement units 40 be installed at four locations: near the top (0 o'clock; 90 degrees), near the left end (9 o'clock; 180 degrees), near the bottom (6 o'clock; 270 degrees), and near the right end (3 o'clock; 0 degrees). However, the number of measurement units 40 should be at least three, and may be five or more. Furthermore, the arrangement of the measurement units 40 is not limited to the example described here.

[0023] The measurement value (reflected pulse) by the distance sensor 41 has a reflection intensity (relative strength and magnitude of the reflected pulse). Possible object characteristics that affect this reflection intensity include the reflectivity of the material at the LIDAR wavelength, the smoothness or roughness of the surface, and the orientation of the reflecting surface relative to the sensor. In this embodiment, the difference in reflectivity based on whether or not a special shape is scanned is detected as reflection intensity.

[0024] The control unit 60 serving as a calculation unit is, for example, a general-purpose personal computer having a memory, a CPU, an SSD, etc. The control unit 60 has an end face holding unit (which can also be called an "end face storage unit" that temporarily stores coordinates and reflection intensity) 61 that holds the coordinates and reflection intensity of the end face 90a of the segment 90 based on the measurement results of multiple points on the end face 90a of the segment 90, and an inner face holding unit 62 that holds the coordinates of the inner face of the skin plate 2 based on the measurement results of multiple points on the inner face of the skin plate 2.

[0025] Of these, the end face holding unit 61 holds the point cloud coordinates of the end face 90a of the segment 90 acquired by moving the measurement unit 40, and the reflection intensity is also held for each point cloud. That is, the coordinates and reflection intensity of the surface of the segment 90 are temporarily stored as two-dimensional coordinates at equal intervals (for example, every 1 cm). In other words, the point cloud data also includes the reflection intensity due to the difference in brightness on the end face of the segment 90, making it possible to identify the white band located at the center of the segment 90. Conversely, the center position of the segment end face 90a can be identified.

[0026] The inner surface holding unit 62 also holds point cloud coordinates of the inner surface (near the tail) of the skin plate 2 acquired by moving the measuring unit 40. Specifically, the coordinates of the surface of the skin plate 2 are temporarily stored as two-dimensional coordinates at equal intervals (for example, every 1 cm).

[0027] The control unit 60 as a calculation unit may be installed on the shield trailing vehicle, on the ground, or both. The measurement data from the distance sensor 41 is sent to the control unit 60 via a cable. The data sent to the ground can also be transferred to a remote terminal via the Internet, etc.

[0028] In addition to the above, the control unit 60 is connected to input means such as a keyboard 65 and a mouse 66, as well as input values ​​from the measurement unit 40. Furthermore, the control unit 60 is connected to output means such as a monitor 71 and a separate PC 72 for excavation management.

[0029] Furthermore, the control unit 60 serving as a calculation unit in this embodiment has a tail clearance calculation unit 63 that calculates tail clearance c. This tail clearance calculation unit 63 calculates the distance between the center position coordinate of the end face of the segment 90 and a position corresponding to the previously measured Y coordinate (see FIG. 7) of the skin plate 2. Then, tail clearance c is calculated by subtracting 1 / 2 the girder height of the segment 90 (known) from the distance between the two points.

[0030] As mentioned above, the tail clearance c data from the segment measurement system S can be transmitted to another PC 72 and incorporated into software that performs comprehensive shield excavation management, thereby enabling more advanced linear excavation management.

[0031] (Measurement procedure) Next, a measurement procedure using the segment measurement system S of this embodiment will be described.

[0032] 1) Measuring units 40 are installed at four locations (e.g., 0, 3, 6, and 9 o'clock) on the shield jack 18 mounting points (girder sections) of the shield machine and fixed so that they do not move. It is desirable to install the measuring units 40 so that the scanning line faces the center of the shield machine. After installation, the measuring units 40 are moved to acquire point cloud coordinates on the inner surface of the skin plate 2 (near the tail). At this time, the distance from an arbitrary fixed point on the skin plate 2 is recognized as two-dimensional coordinates at equal intervals (e.g., every 1 cm). At this time, the positional relationship between the measuring units 40 and the skin plate on the scanning line remains fixed. The skin plate 2 may be measured once, or measurements may be taken during construction to perform calibration (see Figure 5).

[0033] 2) With the coordinates of the skin plate 2 known, segment measurements are carried out while shield excavation is being carried out. At this time, the segment end faces 90a are painted, for example, with a black base so that light and dark can be distinguished, and a white stripe (the width of the stripe is the same all around, for example 1 cm) is painted at the center of the segment. The coloring to represent light and dark does not have to be black and white; as long as there is a difference in reflection intensity, the black and white can be reversed, or other colors can be used. Also, methods other than painting, such as installing a panel, can be used (see Figure 6). Also, it is not necessary to paint the entire circumference; only the four locations scanned by the measurement unit 40 can be used.

[0034] The segment end face 90a facing each measurement unit 40 is scanned to measure the entire end face. At this time, the point cloud data measured on the scanning line can simultaneously acquire the reflection intensity due to the difference in brightness specific to the measurement unit 40, making it possible to identify the white band located at the center. Because the white band is located at the center of the segment end face, if one point is identified as the position of the white band, its coordinates can be estimated; if two points are identified, the average coordinates can be calculated; if three points are identified, the center point coordinates can be calculated; and similar methods can be used to estimate the coordinates near the segment center position.

[0035] 3) The two-dimensional coordinates recognized by the measurement unit 40 have the Y direction in the axial direction of the shield machine and the X direction perpendicular to the axis of the shield machine. If the fixed point where the measurement unit 40 is attached is taken as the starting point, the Y coordinate of the segment coordinate during excavation changes in response to the extension of the jack stroke. The positional relationship between the skin plate and the segment center position can be estimated by calculating the distance between the two points at a position corresponding to the skin plate Y coordinate measured in advance in 1) and the center position coordinate of the segment end face measured in 2). The segment tail clearance c can be obtained by subtracting half the segment girder height from the distance between the two points mentioned above (see Figure 7).

[0036] As mentioned at the beginning, the relationship between the skin plate tail and the measuring unit 40 is such that the measuring unit 40 is fixed in the same position and does not move, eliminating the need for constant measurement, and offering the advantage of being less likely to become unable to measure, even on the bottom surface (6 o'clock position) where water and mud tend to accumulate. Also, when measuring the segment end face 90a, there is no need to measure the outer position of the segment (position near the outer periphery), so even if mud or water accumulates on the outside (lower side at 6 o'clock), measurement will not become impossible as long as the light and dark areas near the center of the segment can be read.

[0037] 4) As shown in Figure 8, by measuring the segment end face and comparing the axial positions (here, Y coordinates) of the shield machine recognized at four points diagonally, the orientation of the segment end face can be estimated. For example, the vertical inclination can be estimated from the measurements at 0 o'clock and 6 o'clock, and the vertical inclination can be estimated from the measurements at 3 o'clock and 9 o'clock. The horizontal inclination can be estimated from the measured value of . Similarly, the circularity of the segment can be estimated from the distance between two diagonal points of the segment center position (this will be described later using Figure 9). By knowing the segment face orientation and segment circularity in this way, it is possible to use this information in excavation management, such as considering the use of direction correction segment 100 in the next and subsequent segment assembly.

[0038] (Segment circularity estimation) Furthermore, as shown in Figures 9(a) and (b), the roundness of the segment 90 can be estimated. That is, as shown in Figure 9(a), the assembled segment 90 and the tail portion of the shield machine are not necessarily perfectly round due to the influence of assembly accuracy, product errors, and soil and water pressure. Therefore, by using the segment measurement system S of this embodiment, the roundness of the segment 90 can be estimated. Specifically, the roundness of the segment 90 is calculated based on the distance between two points at the center positions of the segment girder heights located diagonally. For example, the roundness in the height direction can be estimated from the distance between two points at 0 o'clock and 6 o'clock, and the roundness in the width direction can be estimated from the distance between two points at 3 o'clock and 9 o'clock. The installation positions and rotation directions of the multiple measurement units 40,... within the earth pressure shield 1, as well as the relative positions of the measurement units 40,... are known by installing the measurement units 40,... at accurate positions in advance. For example, it is known in advance that the multiple measurement units 40,... are on the same known radius.

[0039] The roundness of the segment 90 is one of the important control items in ensuring the durability of the tunnel structure and the finished shape of the tunnel cross section. Normally, measurements are taken using surveying equipment and scales after excavation work has finished (to accommodate overtime work) or by interrupting excavation work, but by using this method, it is possible to obtain roundness information in parallel with excavation work.

[0040] Furthermore, as shown in Figure 9(b), when measuring the tail clearance c of the segment 90, due to issues of circularity, only information on the measurement line of each measuring device can be obtained (if a measuring device is attached at the 3 o'clock position, only the segment tail clearance at the 3 o'clock position can be obtained). For this reason, if information on eight locations on the circumference is required, for example, eight measuring devices would be required, which would be extremely uneconomical. In contrast, by measuring using multiple measuring units 40, ... of the present invention, the circularity of the segment 90 and the shield machine can be estimated, and by understanding the elliptical shape of each from the estimated circularity, it is possible to estimate the tail clearance c at any position on the circumference.

[0041] (effect) Next, the effects achieved by the segment measurement system S of this embodiment will be listed and explained.

[0042] (1) As described above, the segment measurement system S of this embodiment is a segment measurement system S that measures the tail clearance, segment roundness, and / or segment end face of an earth pressure shield 1 as a shield tunneling machine, and is equipped with a measurement unit 40 having a non-contact distance sensor 41, a rotation mechanism 42 that rotates the distance sensor 41, and a rotation position detection unit 43 that detects the rotation position of the distance sensor 41 by the rotation mechanism 42; and a calculation unit 60 that calculates the tail clearance, segment roundness, and / or segment end face based on the measurement results of the reflection intensity of the end face 90a of the segment 90 and the measurement results of multiple points on the inner surface of the skin plate 2. With this configuration, the segment measurement system S can directly measure the segment position without using complex calculations, thereby improving measurement accuracy.

[0043] (2) Furthermore, the end face 90a of the segment 90 has bright and dark regions, and the measurement unit 40 can obtain measurement results of high-contrast reflection intensity, making it easier to identify the position of the segment 90 through measurement.

[0044] (3) Furthermore, there are at least three measurement units 40, each positioned near the top end, right end, bottom end, or left end of the cross section of the earth pressure shield 1 as a shield tunneling machine, making it easier to grasp and estimate the shape of the entire circumference of the segment 90 from the measurement results obtained.

[0045] (4) Furthermore, since the measuring unit 40 is positioned approximately midway between the two shield propulsion jacks 18, 18 of the earth pressure shield 1 as a shield tunneling machine in the circumferential direction of the shield tunneling machine, it is possible to continue measuring the position of the segment 90 even while the shield propulsion jack 18 is operating.

[0046] (5) Furthermore, on the end face 90a of the segment 90, a bright region is provided at a predetermined position (e.g., the center position) of the girder height of the segment 90, and dark regions are provided elsewhere, and the control unit 60, which serves as a calculation unit, calculates the tail clearance c based on the inner surface position of the skin plate 2 and the outer surface position of the segment 90 calculated from the predetermined position (e.g., the center position) of the girder height of the segment 90. This makes it possible to accurately calculate the tail clearance c based on the measurement value. In addition, even if water or mud has accumulated inside the shield, for example, it is only necessary to measure the predetermined position (e.g., the center position) of the girder height of the segment 90, making it less likely that measurement will become impossible.

[0047] (6) Furthermore, on the end face 90a of the segment 90, a bright area is provided at a predetermined position (e.g., the center position) of the digit height of the segment 90, and dark areas are provided elsewhere. The control unit 60, which serves as a calculation unit, calculates the circularity of the segment 90 based on the distance between two points at the predetermined positions (e.g., the center positions) of the digit height of the diagonally positioned segments. This allows the circularity to be accurately calculated based on the measurement value.

[0048] (7) Furthermore, on the end face 90a of the segment 90, a bright area is provided at a predetermined position (for example, the center position) of the girder height of the segment 90, and dark areas are provided elsewhere. The control unit 60, which serves as an arithmetic unit, calculates the orientation of the end face 90a of the segment 90 based on the distance to the end face 90a of the segment 90. Therefore, in subsequent segment assembly processes, the direction correction segment 100 can be used to manage excavation.

[0049] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes that do not deviate from the gist of the present invention are included in the present invention. [Explanation of symbols]

[0050] 1: Earth pressure shield; 2: Skin plate; 3: Bulkhead; 5: Cutter head; 10: Cutter rotating shaft; 11: Bearing; 12: Cutter drive unit; 13: Gearbox; 14: Rotation drive source; 15: Erector; 16: Chamber; 17: Soil removal device; 18: Shield propulsion jack; 18a: Piston part; 18b: Spreader part; 19: Tail seal; 21: Mud supply pipe; 22: Soil pressure gauge; 40: Measuring part; 40a: Bracket; 41: distance sensor; 42: rotation mechanism; 43: rotation position detection unit; 51: Cutter spoke; 52: Cutter bit; 53: Fishtail bit; 54: Mixing blade; 60: Control unit; 61: End face holding part; 62: Inner face holding part; 63: Tail clearance calculation part; 65: keyboard; 66: mouse; 71: monitor; 90:segment; 100:Direction correction segment; S: Segment measurement system; c: Tail clearance

Claims

1. A segment measurement system for measuring a tail clearance of a shield machine, a roundness of a segment, and / or an orientation of an end face of a segment, A predetermined position on the end surface of the segment is colored to enable distinction between light and dark; a measurement unit including a non-contact distance sensor, a rotation mechanism for rotating the distance sensor, and a rotation position detection unit for detecting a rotation position of the distance sensor caused by the rotation mechanism; A segment measurement system comprising: a calculation unit that calculates tail clearance, segment circularity, and / or orientation of the segment end face based on the measurement results of the reflection intensity of the segment end face by the measurement unit and the measurement results of multiple points on the inner surface of the skin plate by the measurement unit, and also based on the measurement results of the point cloud coordinates of the segment end face by the measurement unit.

2. 2. The segment measurement system according to claim 1, wherein the end face of the segment has a bright area and a dark area, and the measurement unit is capable of obtaining measurement results of reflection intensity with high contrast.

3. A segment measurement system as described in claim 2, wherein there are at least three measurement units, each of which is positioned near the top end position, the right end position, the bottom end position, or the left end position in the cross section of the shield tunneling machine.

4. 4. The segment measurement system according to claim 3, wherein the measurement unit is disposed at a substantially midpoint between two shield propulsion jacks of the shield machine in the circumferential direction of the shield machine.

5. 5. The segment measurement system according to claim 2, wherein a bright area is provided at a predetermined position of the girder height of the segment on the end face of the segment, and a dark area is provided in other areas, and the calculation unit calculates a tail clearance based on the inner surface position of the skin plate and the outer surface position of the segment calculated from the predetermined position of the girder height of the segment.

6. 5. A segment measurement system as claimed in any one of claims 2 to 4, wherein a bright area is provided at a predetermined position of the segment's digit height on the end face of the segment, and a dark area is provided elsewhere, and the calculation unit is configured to calculate the circularity of the segment based on the distance between two points at the predetermined positions of the segment's digit height located diagonally.

7. 5. A segment measurement system as claimed in any one of claims 2 to 4, wherein the end face of the segment has a bright area at a predetermined position of the segment's girder height and a dark area elsewhere, and the calculation unit calculates the orientation of the end face of the segment based on the distance to the end face of the segment.

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