Surface profile measuring device and surface profile measuring method

Abstract

A surface shape measurement device (10) measures the surface shape of a belt driven in an advancing direction by a driving means. The surface shape measurement device (10) is provided with: a plurality of laser sensors (11) for measuring the surface shape of a belt by irradiating the belt with a linear laser that extends in the width direction of the belt, a portion of the irradiation range of mutual linear lasers being adjacent; and a calculation device (12) for controlling the irradiation timing of the laser sensors so that the irradiation timing of the plurality of laser sensors do not overlap each other, acquiring measurement data from the laser sensors, and calculating the surface shape of the belt on the basis of the acquired measurement data.

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to a surface profile measuring device and a surface profile measuring method, and more particularly to a surface profile measuring device and a surface profile measuring method for measuring the surface profile of a belt driven in a traveling direction by a driving means. [Background technology]

[0002] A belt conveyor, which includes a conveyor belt (an example of a belt) wound around a pair of pulleys as a driving means, is known as a conveying device for conveying raw materials, etc. With long-term operation of a belt conveyor, the conveying surface wears and the thickness of the conveyor belt decreases, so the thickness of the conveyor belt must be periodically controlled to prevent the conveyor belt from breaking.

[0003] As a method for measuring the thickness of a conveyor belt, for example, Patent Documents 1 and 2 disclose an apparatus and system for measuring the unevenness of the surface of a conveyor belt by a light cutting method using a line laser. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-32346 [Patent Document 2] Japanese Patent Publication No. 2020-76767 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, only one laser sensor is installed to project a line laser onto the conveyor belt, making it difficult to accommodate belt conveyors wider than the line laser's irradiation width. Furthermore, in a configuration in which multiple laser sensors are arranged across the width of the conveyor belt and project a line laser across the entire width of the conveyor belt using multiple laser sensors, the line laser's irradiation ranges must partially overlap to eliminate non-measurement areas. However, in areas where the line lasers overlap, the lasers interfere with each other, making it impossible to obtain accurate measurements. Patent Document 2 describes a configuration with multiple line laser projectors, but does not consider laser interference.

[0006] The purpose of the present disclosure, made in consideration of the above circumstances, is to provide a surface shape measuring device and a surface shape measuring method that can accommodate belts wider than the irradiation width of a single line laser and can accurately measure the thickness of the belt without interference from the line laser. [Means for solving the problem]

[0007] (1) A surface profile measuring device according to an embodiment of the present disclosure, A surface profile measuring device for measuring the surface profile of a belt driven in a traveling direction by a driving means, a plurality of laser sensors that measure the surface shape of the belt by irradiating the belt with a line laser extending in a width direction of the belt, the laser sensors having portions of the irradiation ranges of the line lasers that are close to each other; and a calculation device that controls the irradiation timing of the laser sensors so that the irradiation timings of the multiple laser sensors do not overlap with each other, acquires measurement data from the laser sensors, and calculates the surface shape of the belt based on the acquired measurement data.

[0008] (2) As one embodiment of the present disclosure, in (1), The laser sensor measures the surface shape of the belt while the belt is in operation; The calculation device acquires measurement data of the entire length of the belt in the traveling direction, and calculates the surface shape of the belt based on the acquired measurement data.

[0009] (3) As an embodiment of the present disclosure, in (1) or (2), the plurality of laser sensors are arranged side by side in the width direction of the belt, and the irradiation ranges of the line lasers overlap in the width direction of the belt, The calculation device calculates the surface shape of the entire width of the belt by combining the measurement data from the plurality of laser sensors.

[0010] (4) As an embodiment of the present disclosure, in any one of (1) to (3), The belt is wound around a pulley serving as the driving means, The laser sensor measures the surface shape of the belt at the portion where the belt contacts the pulley.

[0011] (5) As an embodiment of the present disclosure, in any one of (1) to (4), The sampling frequency of the laser sensor is 1 kHz or higher.

[0012] (6) A surface profile measuring method according to an embodiment of the present disclosure includes: A surface shape measuring method for measuring a surface shape of a belt driven in a traveling direction by a driving means, comprising: a measuring step of measuring the surface shape of the belt by using a plurality of laser sensors whose irradiation ranges of line lasers are close to each other, controlling the irradiation timings of the laser sensors so that the irradiation timings of the plurality of laser sensors do not overlap with each other, and irradiating the belt with a line laser extending in the width direction of the belt; and a calculation step of acquiring measurement data from the laser sensor and calculating the surface shape of the belt based on the acquired measurement data. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide a surface profile measuring device and a surface profile measuring method that can accommodate belts wider than the irradiation width of a single line laser and can accurately measure the thickness of the belt without interference from the line laser. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a surface profile measuring apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a side view of a belt conveyor measured by the surface shape measuring apparatus of FIG. [Figure 3] FIG. 3 is a plan view of a belt conveyor measured by the surface shape measuring apparatus of FIG. [Figure 4] FIG. 4 is a diagram illustrating an example of a waveform of a signal that controls the timing of irradiating a line laser in the surface shape measuring apparatus of FIG. [Figure 5] FIG. 5 is a diagram for explaining the measurement of the surface shape by a plurality of laser sensors 11. In FIG. [Figure 6] FIG. 6 is a diagram showing an example of the configuration of a surface shape measuring device according to a modified example. [Figure 7] FIG. 7 is a diagram illustrating an example of a waveform of a signal that controls the timing of irradiating a line laser in the surface shape measuring apparatus of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] A surface profile measuring apparatus and a surface profile measuring method according to an embodiment of the present disclosure will be described below with reference to the drawings. In each drawing, identical or corresponding parts are designated by the same reference numerals. In the description of this embodiment, the description of identical or corresponding parts will be omitted or simplified as appropriate.

[0016] <Surface shape measuring device> FIG. 1 shows an example configuration of a surface profile measuring apparatus 10 according to an embodiment of the present disclosure. FIG. 2 is a side view of a belt conveyor 1 measured by the surface profile measuring apparatus 10 of FIG. 1. FIG. 3 is a plan view of the belt conveyor 1 measured by the surface profile measuring apparatus 10 of FIG. 1. As shown in FIG. 2, the surface profile measuring apparatus 10 measures the surface profile of a conveyor belt 30 wound around a pulley 20. Here, the pulley 20 is an example of a driving means. The conveyor belt 30 is also an example of a belt. The surface profile measuring apparatus 10 is an apparatus for measuring the surface profile of a belt driven in a traveling direction by a driving means. Although the belt is not limited to the conveyor belt 30, in this embodiment, the belt is described as a conveyor belt 30 driven by the pulley 20. Here, the traveling direction is the direction in which the belt moves due to the driving force from the driving means. In this embodiment, the traveling direction is also referred to as the conveying direction. The conveying direction is the direction in which an object loaded on the surface 31 of the conveyor belt 30 moves while the conveyor belt 30 is in operation.

[0017] In the belt conveyor 1, it is necessary to control the thickness of the conveyor belt 30 so that the conveyor belt 30 does not break. The thickness of the conveyor belt 30 can be controlled by calculating the thickness of the conveyor belt 30 from the surface profile measured by the surface profile measuring device 10. If the surface profile can be measured accurately, the thickness of the conveyor belt 30 can be accurately obtained by calculation. Here, the surface profile refers to the shape including the irregularities of the surface 31 of the conveyor belt 30. For example, a portion of the surface 31 of the conveyor belt 30 that is recessed from the surrounding area can indicate that the thickness of the conveyor belt 30 is thinner than the surrounding area.

[0018] 1, a surface profile measuring apparatus 10 according to this embodiment includes a laser sensor 11, a computing device 12, and a signal generating device 13. In the surface profile measuring apparatus 10, the laser sensor 11, the computing device 12, and the signal generating device 13 work in coordination to measure the surface profile of a conveyor belt 30. The laser sensor 11, the computing device 12, and the signal generating device 13 are connected via a network such as a LAN (Local Area Network), and may be able to send and receive information obtained by measurement (measurement data). Details of the components of the surface profile measuring apparatus 10 will be described later.

[0019] 2, a conveyor belt 30, which is the object of measurement by the surface profile measuring device 10, is wound around a pair of pulleys 20. When the pulleys 20 rotate, the conveyor belt 30 moves, and an object placed on the surface 31 can be moved. Here, the surface 31 of the conveyor belt 30 is the surface (outer surface) opposite to the surface of the conveyor belt 30 facing the pulleys 20 (inner surface).

[0020] <Laser sensor> The surface profile measuring device 10 of this embodiment includes multiple laser sensors 11. As shown in FIGS. 2 and 3 , the multiple laser sensors 11 are sometimes referred to as laser sensor 11a and laser sensor 11b so that they can be distinguished from one another. In this embodiment, the laser sensor 11 is a laser light cutting device. The laser sensor 11 is capable of measuring the surface profile of the conveyor belt 30 in a non-contact manner by emitting a line laser and capturing an image of the irradiated laser with a camera. That is, the laser sensor 11 measures the distance to the surface 31 of the conveyor belt 30 by emitting a line laser and receiving the reflected light with an optical sensor. Then, the surface profile of the surface 31 of the conveyor belt 30 can be measured based on the distance information. Here, the line laser is a line-shaped laser beam.

[0021] The laser sensor 11 preferably performs measurements while the pulley 20 and the conveyor belt 30 are rotating. As shown in FIGS. 2 and 3 , in this embodiment, two laser sensors 11a and 11b are arranged side by side in the width direction of the pulley 20 (in other words, the width direction of the conveyor belt 30) so that the entire width (total length in the width direction) of the pulley 20 can be measured. The laser beams (line lasers) from the laser sensors 11a and 11b extend in the width direction of the conveyor belt 30, and their irradiation ranges are close to each other. Here, in this embodiment, "close to each other" refers to a state in which at least a portion of the laser beams overlap each other, or a state in which when one laser beam is captured by a camera, the other laser beam is included in the camera's capture range. In this embodiment, the laser beams from the laser sensors 11a and 11b overlap each other by several millimeters to several tens of millimeters to avoid leaving any unmeasured areas. The end of the line laser opposite the overlapping end extends beyond the end of the conveyor belt 30 in the width direction on the pulley 20.

[0022] In this embodiment, the surface shape of the entire width of the conveyor belt 30 can be measured by irradiating laser light onto the conveyor belt 30 using multiple laser sensors 11a and 11b. The laser sensor 11 may be installed at a position where it can irradiate the conveyor belt 30 with laser light from diagonally above the pulley 20 so that the surface shape of the conveyor belt 30 can be measured at the portion where the conveyor belt 30 contacts the pulley 20. At this time, in order to accurately measure the thickness direction of the conveyor belt 30, the laser sensor 11 is installed so that the direction of irradiation of the laser light passes through the center 21 of the pulley 20. Here, the position of the laser sensor 11 is not limited to diagonally above the pulley 20. For example, when viewed from the side as shown in FIG. 2, the laser sensor 11 can be installed at any position as long as the laser light is irradiated between the 6 o'clock and 12 o'clock directions of the pulley 20 closest to the laser sensor 11 (the left half of the pulley 20 on the paper). By measuring the surface shape of the conveyor belt 30 at the portion in contact with the pulley 20, the conveyor belt 30 does not shake up and down, and the conveyor belt 30 can be measured in a stable position. In this way, the laser sensor 11 performs measurements and can obtain information on the surface shape of the conveyor belt 30, including the unevenness. Because the laser sensor 11 is a non-contact type, it is possible to measure the surface shape of the conveyor belt 30 while the conveyor belt 30 is in operation.

[0023] <Arithmetic device> The calculation device 12 calculates the surface shape of the conveyor belt 30 based on the measurement data of the surface of the conveyor belt 30 obtained by the measurement using the laser sensor 11 and operation information of the conveyor belt 30 acquired as needed. Here, the operation information of the conveyor belt 30 includes information indicating that the conveyor belt 30 is in operation.

[0024] The arithmetic unit 12 controls the timing of laser light irradiation from the laser sensors 11a and 11b based on the signal (pulse waveform) generated by the signal generator 13.

[0025] The arithmetic device 12 includes a processor that executes calculations and a storage unit that stores data used in the calculations (e.g., information on the surface shape). The arithmetic device 12 may be, for example, a computer. The processor may be, for example, a general-purpose processor or a dedicated processor specialized for a specific process, but is not limited to these and may be any processor. The storage unit is one or more memories. The memory may be, for example, a semiconductor memory, a magnetic memory, an optical memory, etc., but is not limited to these and may be any memory.

[0026] <Signal Generator> The signal generating device 13 generates a signal that determines the timing and duration of laser light irradiation by the laser sensors 11a and 11b. The signal generated by the signal generating device 13 has a pulse waveform as described above, and is generated so that the laser sensors 11a and 11b do not simultaneously emit laser light. Here, the signal generating device 13, together with the arithmetic device 12, may be realized by a computer.

[0027] <Surface shape measurement method> A method for measuring the surface shape of a conveyor belt 30 using a laser sensor 11 will be described with reference to Figures 4 and 5. Figure 4 shows the waveform of a signal that controls the timing of irradiating a line laser, generated by a signal generator 13. Figure 5 is a diagram for explaining the measurement of the surface shape using multiple laser sensors 11.

[0028] While the conveyor belt 30 is in operation, the signal generator 13 generates pulse waveforms for two channels as shown in Figure 4. The pulse waveform is a signal that takes on two values, High and Low. The arithmetic unit 12 receives the pulse waveform from the signal generator 13, and when the pulse waveform is High, outputs a laser light emission command to cause the corresponding laser sensor 11 to emit laser light. Channel 1 (CH1) corresponds to laser sensor 11a, and channel 2 (CH2) corresponds to laser sensor 11b. The horizontal axis in Figure 4 represents time.

[0029] The waveform of CH1 changes from Low to High at the time indicated by A. The calculation device 12 outputs a laser light irradiation command to the laser sensor 11a, and the laser sensor 11a measures the surface shape of approximately half of the width of one end of the conveyor belt 30. After time L1 has elapsed, the waveform of CH1 changes from High to Low, and the calculation device 12 outputs a laser light irradiation stop command to the laser sensor 11a to stop emitting the laser light. This completes the surface shape measurement of the conveyor belt 30 by the laser sensor 11a in response to one pulse waveform. In FIG. 5, one rectangular area indicated as surface shape data obtained by the laser sensor 11a corresponds to the surface shape of the conveyor belt 30 measured in response to one pulse waveform of CH1.

[0030] At the same time that the CH1 waveform changes from High to Low, the CH2 waveform changes from Low to High. To reliably prevent interference between the line lasers, a slight time lag may be provided between the time that the CH1 waveform changes from High to Low and the time that the CH2 waveform changes from Low to High. The calculation device 12 outputs a laser beam irradiation command to the laser sensor 11b, and the laser sensor 11b measures the surface shape of approximately half of the width of the other end of the conveyor belt 30. After time L2 has elapsed, the CH2 waveform changes from High to Low, and the calculation device 12 outputs a laser beam irradiation stop command to the laser sensor 11b. This completes the surface shape measurement of the conveyor belt 30 by the laser sensor 11b in response to one pulse waveform. In FIG. 5, one rectangular area labeled "surface shape data obtained by the laser sensor 11b" corresponds to the surface shape of the conveyor belt 30 measured in response to one pulse waveform of CH2.

[0031] At the timing when the CH2 waveform changes from High to Low, the CH1 waveform changes from Low to High again. To reliably prevent interference between the line lasers, a slight time lag may be provided between the timing when the CH2 waveform changes from High to Low and the timing when the CH1 waveform changes from Low to High. The calculation device 12 outputs a laser light irradiation command to the laser sensor 11a, and the laser sensor 11a performs surface shape measurement of approximately half of the width of one end of the conveyor belt 30. The sum of the above times L1 and L2 is set as a period L, and surface shape measurement of the conveyor belt 30 by the laser sensors 11a and 11b is repeated in accordance with changes in the CH1 and CH2 waveforms. Surface shape measurement of approximately half of the width of the conveyor belt 30 is performed alternately at one end and the other end, and the measurement data is accumulated in the calculation device 12.

[0032] This surface profile measurement is continued for one revolution of the conveyor belt 30, thereby accumulating measurement data for the entire length of the conveyor belt 30 in the longitudinal direction (travel direction). Here, as shown in FIG. 5, because laser sensors 11a and 11b alternately operate, the surface profile data for the conveyor belt 30 may be composed of a discontinuous group of measurement data, including missing portions that have not been actually measured. For example, even if a portion of the conveyor belt 30 in the traveling direction has not been actually measured, the calculation device 12 can estimate the surface profile by using a known interpolation method (e.g., linear interpolation) based on the actual measurement data before and after the portion to calculate the surface profile. The calculation device 12 then calculates the surface profile of the entire width of the conveyor belt 30 by combining the measurement data from the multiple laser sensors 11. Here, to improve the accuracy of the estimation, it is necessary that the length of the area measured in response to one pulse waveform in the traveling direction, indicated by B in FIG. 5, be sufficiently small. For example, if B is equal to or less than a predetermined length (e.g., 10 mm), it is considered that the surface profile does not change significantly in adjacent non-measured areas, enabling sufficiently accurate estimation by interpolation. On the other hand, if B is greater than a predetermined length (e.g., 10 mm), the surface shape may change significantly in adjacent non-measurement areas, for example, due to the presence of scratches. This may result in a decrease in estimation accuracy. The length of B in FIG. 5 depends on the period L in FIG. 4. To obtain highly accurate surface shape data of the conveyor belt 30, it is desirable that the period L be as small as possible. Since the period L is determined by the sampling frequency of the laser sensor 11, it is desirable that the sampling frequency be as large as possible. For example, the sampling frequency of the laser sensor 11 can be approximately 1 kHz (1,000 times per second), which is sufficiently fast compared to the driving speed (conveying speed) of the conveyor belt 30, thereby enabling highly accurate surface shape data of the conveyor belt 30 to be obtained. The sampling frequency of the laser sensor 11 may be 1 kHz or higher. Here, although it is possible to actually measure all of the surface shape data of the conveyor belt 30, it is necessary to perform surface shape measurement by rotating the conveyor belt 30 once for each of the multiple laser sensors 11.For example, when the laser sensors 11a and 11b are provided, the conveyor belt 30 needs to be rotated twice to actually measure the overall length and width of the conveyor belt 30, which doubles the measurement time. In other words, the surface shape measuring method of this embodiment makes it possible to obtain highly accurate surface shape data of the conveyor belt 30 in a short time.

[0033] As described above, the surface profile measuring method executed by the surface profile measuring apparatus 10 according to this embodiment includes the following steps. First, in the measurement step, multiple laser sensors with line laser irradiation ranges close to each other are used, and control is performed, for example, using pulse waveforms, so that the irradiation timings of the multiple laser sensors do not overlap. In the measurement step, the irradiation timings of the laser sensors are controlled, and a line laser extending in the width direction of the belt is irradiated onto the belt, thereby measuring the belt surface profile. Then, in the calculation step, the calculation device 12 acquires measurement data from the laser sensors and calculates the belt surface profile based on the acquired measurement data.

[0034] <How to manage your belt> Using the above-described surface profile measurement method, the conveyor belt 30 can be managed (monitored) based on the calculated surface profile of the conveyor belt 30. The surface profile measuring device 10 determines whether the thickness of the conveyor belt 30 is sufficient, for example, based on the calculated surface profile of the conveyor belt 30. If the surface profile measuring device 10 determines that the thickness is insufficient, it can notify an operator of an abnormality in the conveyor belt 30 or stop the conveyor belt 30. In this way, by managing the conveyor belt 30 based on the calculated surface profile of the conveyor belt 30, it becomes possible to accurately detect abnormalities in the conveyor belt 30 and to respond to the abnormality early.

[0035] As described above, the surface profile measuring device 10 and surface profile measuring method according to the present embodiment, with the above-described configuration, can accommodate belts wider than the irradiation width of a single line laser and can accurately measure the surface profile of the conveyor belt 30 without line laser interference. Furthermore, based on highly accurate surface profile data of the conveyor belt 30, the thickness of the belt can be accurately measured, enabling appropriate management to prevent belt breakage and other issues. Here, the belt thickness may be calculated by, for example, the computing device 12 using the difference between the distance to the surface 31 obtained as the surface profile of the conveyor belt 30 and the distance to the pulley 20, which can be measured simultaneously, but is not limited to a specific calculation method. The distance to the pulley 20 may be obtained by measuring the exposed portion of the laser sensor 11 (a portion not wrapped around the conveyor belt 30).

[0036] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art would easily be able to make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included within the scope of the present disclosure. For example, functions included in each component or step (process) can be rearranged so as not to cause logical inconsistencies, and multiple components or steps can be combined or divided into one. The embodiments of the present disclosure can also be realized as a program executed by a processor included in an apparatus or a storage medium on which a program is recorded. It should be understood that these are also included within the scope of the present disclosure.

[0037] In the above embodiment, two laser sensors 11 are used, but three or more may be used. Increasing the number of laser sensors 11 makes it possible to accommodate wider belts. A surface profile measuring apparatus 10 according to a modified example will be described below. FIG. 6 is a diagram showing an example of the configuration of the surface profile measuring apparatus 10 according to a modified example. FIG. 7 is a diagram showing an example of the waveform of a signal that controls the timing of irradiating the line laser in the surface profile measuring apparatus 10 according to a modified example.

[0038] In the example of FIG. 6, the width of pulley 20 is wider than that of FIG. 3, and three laser sensors 11 are arranged side by side in the width direction of pulley 20. As shown in FIG. 7, signal generator 13 generates signals that determine the timing and duration of laser light irradiation from laser sensors 11a, 11b, and 11c. That is, FIG. 7 shows pulse waveforms for three channels generated by signal generator 13. Channel 1 (CH1) corresponds to laser sensor 11a, channel 2 (CH2) corresponds to laser sensor 11b, and channel 3 (CH3) corresponds to laser sensor 11c. As in the above embodiment, signal generator 13 shifts the timing of laser light irradiation from laser sensors 11a, 11b, and 11c to control the laser light so that interference does not occur, thereby obtaining surface shape measurement data for conveyor belt 30. 6, the laser beam irradiation range of laser sensor 11a overlaps with the laser beam irradiation range of laser sensor 11b, and the laser beam irradiation range of laser sensor 11b overlaps with the laser beam irradiation range of laser sensor 11c. On the other hand, the laser beam irradiation range of laser sensor 11a does not overlap with the laser beam irradiation range of laser sensor 11c. Therefore, the laser beam irradiation timing of laser sensors 11a and 11c may be the same. [Explanation of symbols]

[0039] 1 conveyor belt 10 Surface profile measuring device 11, 11a, 11b, 11c Laser sensors 12 Arithmetic unit 13 Signal Generator 20 pulleys 21 Pulley center 30 Conveyor Belt 31 Conveyor belt surface

Claims

1. A surface profile measuring device for measuring the surface profile of a belt driven in a traveling direction by a driving means, a plurality of laser sensors that measure the surface shape of the belt by irradiating the belt with a line laser extending in the width direction of the belt, the laser sensors having irradiation ranges of the line lasers that are close to each other; a calculation device that controls the irradiation timings of the laser sensors so that the irradiation timings of the plurality of laser sensors do not overlap with each other, acquires discontinuous measurement data including missing portions that have not been actually measured from the laser sensors, and calculates the surface shape of the belt while estimating the missing portions by an interpolation method based on the acquired measurement data, A surface shape measuring apparatus, wherein the sampling frequency of the laser sensor is 1 kHz or more.

2. The laser sensor measures the surface shape of the belt while the belt is in operation; 2. The surface profile measuring device according to claim 1, wherein the calculation device acquires measurement data of the entire length of the belt in the traveling direction, and calculates the surface profile of the belt based on the acquired measurement data.

3. the plurality of laser sensors are arranged side by side in the width direction of the belt, and the irradiation ranges of the line lasers overlap in the width direction of the belt, 3. The surface profile measuring device according to claim 1, wherein the calculation device calculates the surface profile across the entire width of the belt by combining the measurement data from the plurality of laser sensors.

4. The belt is wound around a pulley serving as the driving means, 3. The surface profile measuring device according to claim 1, wherein the laser sensor measures the surface profile of the belt at a portion where the belt contacts the pulley.

5. A surface shape measuring method for measuring a surface shape of a belt driven in a traveling direction by a driving means, comprising: a measuring step of measuring the surface shape of the belt by using a plurality of laser sensors whose irradiation ranges of line lasers are close to each other, controlling the irradiation timings of the laser sensors so that the irradiation timings of the plurality of laser sensors do not overlap with each other, and irradiating the belt with a line laser extending in the width direction of the belt; a calculation step of acquiring discontinuous measurement data including missing portions that have not been actually measured from the laser sensor, and calculating the surface shape of the belt while estimating the missing portions by an interpolation method based on the acquired measurement data, A surface shape measuring method, wherein the sampling frequency of the laser sensor is 1 kHz or more.

Images