Shape measuring device and computer-readable storage medium

Abstract

The shape measuring device acquires the height of the surface of the object to be measured from a distance sensor that moves relative to the surface of the object to be measured, calculates, on the basis of the height, ascending or descending coordinate values present on the surface of the object to be measured, and stores a reference value for the ascending or descending coordinate values. A reference value is compared with the coordinate values calculated by the coordinate value calculation unit, the coordinate values different from the reference value are determined to be inappropriate data, the speed condition of the relative speed between the measurement object and the distance sensor is changed, the coordinate values calculated under different speed conditions are compared, and the cause of the inappropriate data is determined.

Description

Technical Field

[0001] The present disclosure relates to a shape measurement device and a computer-readable storage medium. Background Art

[0002] Conventionally, there has been a shape measurement device that irradiates a measurement object with measurement light and measures the positions of respective parts of the measurement object. For example, Patent Document 1.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-137265 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In some shape measurement devices, reference values for rising and falling of stored signals are compared with measurement results to determine the accuracy of the shape of a measurement object. False detection sometimes occurs in shape measurement.

[0008] In the field of shape measurement, a technique for determining the cause of false detection is desired.

[0009] Means for Solving the Problems

[0010] A shape measurement device according to one aspect of the present disclosure includes: a coordinate value calculation unit that obtains the height of the surface of a measurement object from a distance sensor that relatively moves with respect to the surface of the measurement object, and calculates coordinate values of rising or falling present on the surface of the measurement object based on the height; a reference value storage unit that stores reference values of the coordinate values of rising or falling; a data comparison unit that compares the reference values with the coordinate values calculated by the coordinate value calculation unit; and a cause determination unit that determines coordinate values different from the reference values as inappropriate data, changes the speed condition of the relative speed between the measurement object and the distance sensor, compares the coordinate values calculated under different speed conditions, and determines the cause of the inappropriate data. Brief Description of the Drawings

[0011] Figure 1 is a block diagram of a shape measurement device.

[0012] Figure 2 is a schematic diagram of a shape measurement device for measuring the shape of a linear measurement object.

[0013] Figure 3 is a schematic diagram of a shape measurement device for measuring the shape of a circular measurement object.

[0014] Figure 4 is a schematic diagram of coordinate values of a linear shape.

[0015] Figure 5 It is a schematic diagram of the approximate coordinate values that are circular.

[0016] Figure 6 It is a schematic diagram showing the change of coordinate values.

[0017] Figure 7 It is a schematic diagram of the coordinate values when chattering occurs.

[0018] Figure 8 It is a schematic diagram showing the change of coordinate values.

[0019] Figure 9 It is a flowchart showing the operation of the shape measurement device.

[0020] Figure 10 It is a hardware structure diagram of the shape measurement device. Detailed implementation mode

[0021] (First implementation mode)

[0022] Hereinafter, the shape measurement device 100 of the first implementation mode will be described. The shape measurement device 100 is applied to machines such as gear measuring devices for measuring the concavities and convexities of the measurement object. The shape measurement device 100 can also be applied to control devices of other devices such as numerical control devices and information processing devices such as PCs (personal computers). The constituent elements of the shape measurement device vary depending on the device to be applied.

[0023] The constituent elements of the shape measurement device are classified according to their functions, and may not be clearly distinguishable in the physical structure and the program structure.

[0024] Figure 1 It is a block diagram of the shape measurement device 100. The shape measurement device 100 includes a motor drive unit 11, a motor control unit 12, a distance sensor 13, a coordinate value calculation unit 14, a reference value storage unit 15, a data comparison unit 16, a cause determination unit 17, and a cause notification unit 18.

[0025] The motor drive unit 11 drives the motor according to the instruction of the motor control unit 12. An encoder (not shown) is provided on the motor. The encoder outputs the rotation angle of the motor.

[0026] The motor control unit 12 obtains the rotation angle of the motor and controls the rotation speed (rotation angle) of the motor. The control method of the motor is different for linear measurement objects (workpieces) and circular measurement objects.

[0027] In the case of a linear measurement object, as Figure 2As shown, the rotational motion of the motor is converted into linear motion by the ball screw. The motor control unit 12 controls the relative position of the distance sensor 13 and the measurement object (the workbench on which the measurement object is placed).

[0028] In the case of a circular measurement object, as Figure 3 shown, the motor rotates the circular measurement object. The motor control unit 12 controls the rotational speed (rotational angle) of the motor obtained from the encoder.

[0029] The distance sensor 13 irradiates the measurement object with sound waves, light, etc., and detects the height of the surface of the measurement object based on the reflection from the measurement object.

[0030] The coordinate value calculation unit 14 calculates the coordinate values of the rises and falls of the unevenness existing on the surface of the measurement object based on the height of the surface of the measurement object detected by the distance sensor 13. The calculation method of the coordinate values uses existing technologies.

[0031] The units of the coordinate values are different for linear measurement objects and circular measurement objects.

[0032] In the case of a linear measurement object, the position of the distance sensor relative to the measurement object is set as the coordinate value.

[0033] In the case of a circular measurement object, the angle of the motor is set as the coordinate value.

[0034] The reference value storage unit 15 stores the coordinate values that serve as references. The coordinate values that serve as references indicate the positions where rises and falls exist on the surface of the measurement object. For the sake of easy explanation, the cross-section of the linear measurement object in this embodiment is rectangular, but it can also be other shapes such as trapezoidal.

[0035] The reference values include the machine coordinates of the machine for measuring the measurement object, the relative coordinates with respect to the origin set on the machine coordinates, the distance between coordinates (or angle difference), etc.

[0036] The machine coordinates are the inherent coordinates that the machine itself has. The relative coordinates are the coordinates starting from an arbitrary point on the machine coordinates. The distance between coordinates is the distance between two or more reference values on the machine coordinates.

[0037] In the case where the measurement object is circular, a point on the rotation axis is set as the origin. The relative coordinates are the relative coordinates starting from an arbitrary point on the rotation axis. The distance between coordinates is the distance between two or more reference values on the rotation axis.

[0038] The reference value can be calculated based on the ideal prototype of the object to be measured, the design drawing of the object to be measured, etc. For example, the ideal prototype of the object to be measured is measured, and the coordinate values of its rise and fall are used as the reference value. In addition, the reference values of rise and fall can be calculated based on the design drawing. An allowable error can also be set for the reference value. When the allowable error is set, the cause determination unit 17 determines the coordinate values exceeding the allowable error as inappropriate data.

[0039] The data comparison unit 16 compares the coordinate values of rise and fall calculated by the coordinate value calculation unit 14 with the reference values stored in the reference value storage unit 15. When the result of the comparison is that the coordinate values of rise and fall are different from the reference values, the data is determined as inappropriate data.

[0040] When the data comparison unit 16 detects inappropriate data, the cause determination unit 17 sends an instruction to the motor control unit 12 to change the speed condition of the motor and perform re-measurement of the coordinate values.

[0041] When the result of changing the speed condition of the motor is that the same coordinate values as the previous coordinate values are detected, the cause determination unit 17 determines that the cause of the inappropriate data is the poor shape of the object to be measured. When the result of changing the speed condition of the motor is that coordinate values different from the previous coordinate values are detected, the cause determination unit 17 determines the cause of the inappropriate data as chattering. When the result of changing the speed condition of the motor is that no inappropriate data is detected, the cause determination unit 17 determines that the cause of the inappropriate data is noise or speed condition, etc.

[0042] The cause notification unit 18 notifies the determination result of the cause determination unit 17 to the user. The notification method uses an existing method.

[0043] Next, taking a linear object to be measured as an example, the operation of the shape measurement device 100 will be described. Figure 4 It is a schematic diagram of the shape measurement device 100 for measuring the shape of a linear object to be measured. The distance sensor 13 measures the height of the surface of the object to be measured while moving parallel on the object to be measured.

[0044] The shape measurement device 100 detects the coordinate values of the positions where the rise and fall of the surface of the object to be measured exist based on the height of the surface of the object to be measured detected by the distance sensor 13. The reference value storage unit 15 stores the reference values of the coordinate values of rise and fall. In Figure 4 it, as the reference value of the coordinate value, the coordinate value with the measurement start position of the distance sensor 13 as the origin and the reference value of the distance between the coordinates of two points are depicted.

[0045] The reference values with the measurement start position of the distance sensor 13 as the origin are the ascending values "3, 6, 9, …" and the descending values "4, 7, 10, …". The reference value for the distance between coordinates is the distance between the ascending and descending values "1, 2, 1, 2, 1, 3, …". The reference value for the distance between coordinates can also be that the slot holes are "all 1".

[0046] The data comparison unit 16 compares the reference values with the coordinate values (measured values) detected by the distance sensor. The measured values are set as "3, 4, 6, 7, 9, 10.1, …". The data comparison unit 16 determines the third descending coordinate value "10.1" different from the reference value as inappropriate data.

[0047] When inappropriate data is detected, the cause determination unit 17 changes the speed condition of the motor and starts re-measurement. The cause determination unit 17 sends an instruction to the motor control unit 12. The distance sensor 13 calculates the coordinate values of the ascending and descending generated under the new speed condition.

[0048] The cause determination unit 17 compares the coordinate values of the ascending and descending detected under the new speed condition with the coordinate values of the ascending and descending detected under the previous speed condition. When the coordinate value of the inappropriate data detected under the new speed condition is different from the coordinate value "10.1" of the inappropriate data detected previously, the cause determination unit 17 determines the cause of the inappropriate data as flutter.

[0049] When the coordinate value of the inappropriate data detected under the new speed condition is the same as the coordinate value "10.1" of the inappropriate data detected previously, the cause determination unit 17 determines that there is a shape defect at the position of the coordinate value "10.1".

[0050] When the inappropriate data detected previously is not detected under the new speed condition, the cause determination unit 17 determines that the cause of the inappropriate data is noise or speed condition, etc.

[0051] Next, an example of measuring a circular measurement object will be described. Figure 5 It is a schematic diagram of the shape measurement device 100 for measuring a circular measurement object. The distance sensor 13 irradiates the surface of the measurement object with laser or the like. The measurement object rotates, and the laser measures the height of the surface of the measurement object. In addition, in Figure 5 the measurement object, there is a defect at the position of "95 degrees".

[0052] The reference value storage unit 15 stores the reference values of the coordinate values of the ascending and descending. In Figure 5In the schematic diagram, as the reference value of the coordinate value, the reference value with a point on the rotation axis as the origin and the distance between the coordinates of two points on the rotation axis are depicted. The reference value with a point on the rotation axis as the origin is the ascending coordinate values "0, 45, 90, 135,..." and the descending coordinate values "15, 60, 105, 150,...". The reference value of the distance between coordinates can be expressed, for example, as "tooth tip: 15, tooth space: 30", the angle between ascending and descending "15, 30, 15, 30, 15,...", etc.

[0053] When the measurement object is rotated at a certain speed, the distance sensor 13 detects the ascending coordinate values "0, 45, 90, 100, 135,..." and the descending coordinate values "15, 60, 95, 105, 150,...".

[0054] In addition, the coordinate values detected by the distance sensor 13 can also be expressed by the angular difference between two points (tooth tip: 15, 5, tooth space: 30, 5).

[0055] The cause determination unit 17 compares the reference value with the coordinate values detected by the distance sensor 13. The fourth ascending coordinate value "100" and the third descending coordinate value "95" are different from the reference value. The cause determination unit 17 determines the coordinate values "100" and "95" different from the reference value as inappropriate data.

[0056] When the cause determination unit 17 detects inappropriate data, it changes the speed condition of the motor. The measurement object rotates at a new speed, and re-measurement can be performed under the new speed condition.

[0057] Refer to Figure 5 and Figure 6 , and an explanation is given for the process of determining that the cause of the inappropriate data is a defect.

[0058] The distance sensor 13 irradiates the surface of the measurement object with laser or the like. The measurement object rotates, and the laser measures the height of the surface of the measurement object. In addition, in Figure 5 the measurement object, there is a defect at the position of "95 degrees".

[0059] The shape measurement device 100 rotates the measurement object at a normal speed. At this time, the data comparison unit 16 compares the reference value with the coordinate values detected by the distance sensor 13, and determines the third descending coordinate value "95" as inappropriate data. When the cause determination unit 17 detects inappropriate data, it changes the speed condition of the motor.

[0060] Figure 6 is a schematic diagram showing the change of the coordinate value when the speed condition of the measurement object changes.

[0061] In this example, the speed of the motor is slowed down. When the coordinate values of inappropriate data do not change even if the speed condition of the motor is changed, the cause determination unit 17 determines that there is a defect at the position where the coordinate values of inappropriate data are generated.

[0062] Refer to Figure 7 and Figure 8 to explain that the cause of determining inappropriate data is the processing of flutter.

[0063] In Figure 7 the shape measurement device 100, flutter occurs in the distance sensor 13.

[0064] The distance sensor 13 irradiates the surface of the measurement object with laser or the like. The measurement object rotates, and the laser measures the height of the surface of the measurement object.

[0065] When the measurement object rotates at a certain speed, the distance sensor 13 detects the rising coordinate values "0, 0.4, 45, 45.4, 90, 90.4,..." and the falling coordinate values "0.2, 15, 45.2, 60, 90.2, 105,...".

[0066] In addition, the distance sensor 13 can also detect the angular difference between two points (tooth tip: 15, 0.2, tooth space: 30, 0.2) as coordinate values.

[0067] The cause determination unit 17 compares the reference value with the coordinate values detected by the distance sensor. In Figure 7 the example, the second rising coordinate value "0.4", the fourth rising coordinate value "45.4", the sixth rising coordinate value "90.4", the first falling coordinate value "0.2", the third falling coordinate value "45.2", and the fifth falling coordinate value "90.2" are different from the reference value.

[0068] The cause determination unit 17 determines these coordinate values "0.2", "0.4", "45.2", "45.4", "90.2", "90.4" as inappropriate data.

[0069] When the cause determination unit 17 detects inappropriate data, it changes the speed condition of the motor. When the measurement object is circular, if the speed condition is changed, re-measurement can be performed.

[0070] Figure 8 Indicates the change in coordinate values when the speed condition of the measurement object changes.

[0071] When the measurement object is rotated at a certain speed, inappropriate data is detected at the first descent of "0.2" and the second ascent of "0.4". When the cause determination unit 17 detects inappropriate data, it changes the speed condition of the motor. In this example, the speed of the motor is slowed down. When the flutter signal is 1 ms, if the speed of the motor is 0.2 degrees / ms, inappropriate data is generated at the coordinate values of "0.2" and "0.4". If the speed of the motor is changed to 0.1 degrees / ms, inappropriate data is generated at the coordinate values of "0.1" and "0.2".

[0072] The cause determination unit 17 changes the speed condition of the motor, and when the coordinate value of the inappropriate data changes, determines the cause of the inappropriate data as flutter.

[0073] When the result of changing the speed condition is that inappropriate data at the coordinate values of "0.2" and "0.4" is not detected, the cause determination unit 17 determines the cause of the inappropriate data as noise or speed condition, etc.

[0074] Next, the operation of the shape measurement device 100 will be described with reference to Figure 9 the flowchart. The shape measurement device 100 rotates the motor at a certain speed (step S1). Due to the rotation of the motor, the surface of the measurement object moves relative to the distance sensor 13. By moving the surface of the measurement object relative to the distance sensor 13, the coordinate value of the position detected by the distance sensor 13 changes. The distance sensor 13 measures the height of the surface of the measurement object (step S2).

[0075] The shape measurement device 100 calculates the coordinate values of the ascent and descent of the surface of the measurement object (step S3). The shape measurement device 100 compares the calculated coordinate values with a reference value (step S4).

[0076] When the detected coordinate value is the same as the reference value (step S5; same), it is determined that the measurement is normal (step S6), and the cause determination process ends. When the reference value is different from the coordinate value (step S5; different), the shape measurement device 100 determines the coordinate value detected in step S3 as inappropriate data (step S7).

[0077] When inappropriate data is detected in step S7, the shape measurement device 100 changes the speed condition of the motor (step S8). The shape measurement device 100 changes the speed of the motor and calculates the coordinate values (step S9). The shape measurement device 100 compares the coordinate values of the inappropriate data calculated under the new speed condition with the coordinate values of the inappropriate data detected in advance (step S10). When the coordinate values of the inappropriate data detected under the new speed condition are the same as the coordinate values of the inappropriate data detected in advance (step S11; same), the shape measurement device 100 determines that the cause of the inappropriate data is the shape of the measurement object (step S12), and ends the cause determination process.

[0078] When the coordinate values of the inappropriate data detected under the new speed condition are different from the coordinate values of the inappropriate data detected in advance (step S11; different), the shape measurement device 100 determines that the cause of the inappropriate data is flutter (step S13).

[0079] When inappropriate data is not detected by changing to the new speed condition (step S11; not detected), the shape measurement device 100 determines that the cause of the inappropriate data is other reasons such as noise or speed condition (step S14).

[0080] As described above, when the shape measurement device 100 of the present embodiment detects inappropriate data different from the reference value, it changes the speed of the motor and performs re-measurement. When the coordinate values of the position where inappropriate data is generated do not change as a result of changing the speed of the motor, it is determined that there is a shape defect (such as a defect) at the position where the inappropriate data is generated.

[0081] When the coordinate values of the position where inappropriate data is generated change, the shape measurement device 100 determines that flutter has occurred. Flutter changes according to the speed of the motor.

[0082] When no inappropriate data is generated as a result of the re-measurement, the shape measurement device 100 determines that the inappropriate data is generated due to other reasons such as noise or speed condition.

[0083] According to the shape measurement device 100 of the present disclosure, the cause of inappropriate data can be evaluated, so the measurement accuracy is improved. In addition, since the cause of inappropriate data is automatically determined, the number of measurements and the measurement time can be reduced.

[0084] Hereinafter, the hardware structure of the shape measurement device 100 to which the present disclosure is applied will be described. Figure 10 It is a hardware structure diagram of the shape measurement device 100. As Figure 10As shown, the shape measurement device 100 includes a CPU 111 for overall control of the shape measurement device 100, a ROM 112 for recording programs and data, and a RAM 113 for temporarily expanding data. The CPU 111 reads the system program recorded in the ROM 112 via a bus and performs shape measurement processing according to the system program.

[0085] The non-volatile memory 114 is backed up by a battery (not shown), for example, and maintains its storage state even when the power supply of the shape measurement device 100 is turned off. Various data such as programs read from an external device 120 via the interfaces 115, 118, 119 and user operations input via the input unit 30 are stored in the non-volatile memory 114. The non-volatile memory 114 can store programs and data for executing the shape measurement device 100 of the present embodiment. In addition, various data, measurement results, reasons for inappropriate data, etc. are displayed on the display unit 70.

[0086] The interface 115 is an interface for connecting the shape measurement device 100 to an external device 120 such as an adapter. Programs, various parameters, etc. are read from the external device 120 side.

[0087] The interface 118 is an interface for connecting the shape measurement device 100 to a display unit 70 such as a liquid crystal display. Each data read into the memory, data obtained as a result of executing a program, etc. are displayed on the display unit 70.

[0088] The interface 119 is an interface for connecting the shape measurement device 100 to an input unit 30 such as a keyboard and a pointing device. The input unit 30 transmits instructions, data, etc. based on the operator's operation to the CPU 111 via the interface 119.

[0089] Although the present disclosure has been described in detail, the present disclosure is not limited to the above-described respective embodiments. These embodiments can be variously added, replaced, changed, partially deleted, etc. without departing from the gist of the present disclosure or without departing from the gist of the present disclosure derived from the content described in the claimed scope and its equivalents. In addition, these embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each action and the order of each process are shown as an example and are not limited thereto.

[0090] Regarding the above-described embodiments and modified examples, the following remarks are also disclosed.

[0091] (Remark 1)

[0092] The shape measurement device 100 includes: a coordinate value calculation unit 14 that obtains the height of the surface of the measurement object from a distance sensor 13 that relatively moves with respect to the surface of the measurement object, and calculates coordinate values of rises or falls present on the surface of the measurement object based on the height; a reference value storage unit 15 that stores reference values of the coordinate values of the rises or falls; a data comparison unit 16 that compares the reference values with the coordinate values calculated by the coordinate value calculation unit; and a cause determination unit 17 that determines coordinate values different from the reference values as inappropriate data, changes the speed condition of the relative speed between the measurement object and the distance sensor, compares the coordinate values calculated under different speed conditions, and determines the cause of the inappropriate data.

[0093] (Supplementary Note 2)

[0094] If the coordinate values calculated under the different speed conditions are the same, the cause determination unit 17 determines the cause of the inappropriate data as the shape of the measurement object.

[0095] (Supplementary Note 3)

[0096] If the coordinate values calculated under the different speed conditions are different, the cause determination unit 17 determines the cause of the inappropriate data as the flutter of the distance sensor.

[0097] (Supplementary Note 4)

[0098] In the case where the inappropriate data is not detected as a result of changing the speed condition, the cause determination unit 17 determines the cause of the inappropriate data as noise or the speed condition.

[0099] (Supplementary Note 5)

[0100] The coordinate values in the shape measurement device 100 are at least one of machine coordinates, relative coordinates with respect to an arbitrary reference point, and distances between coordinates of at least two or more points.

[0101] (Supplementary Note 6)

[0102] The reference values of the coordinate values in the shape measurement device 100 are calculated based on at least one of the ideal prototype of the measurement object and the design drawing of the measurement object.

[0103] (Supplementary Note 7)

[0104] The shape measurement device 100 includes a notification unit that notifies the user of the cause of the inappropriate data.

[0105] (Supplementary Note 8)

[0106] A storage medium 112, 113, 114 stores commands that can be read by a storage processor 111. By executing the commands through one or more processors 111, the following processes are performed: obtaining the height of the surface of a measurement object from a distance sensor 13 that relatively moves with respect to the surface of the measurement object, and calculating coordinate values of rises or falls present on the surface of the measurement object based on the height; comparing a reference value of the coordinate values of the rises or falls with the coordinate values of the rises or falls present on the surface of the measurement object; determining coordinate values different from the reference value as inappropriate data, changing a speed condition of a relative speed between the measurement object and the distance sensor, comparing the coordinate values calculated under different speed conditions, and determining the cause of the inappropriate data.

[0107] Symbol Explanation

[0108] 100 Shape Measurement Device

[0109] 13 Distance Sensor

[0110] 14 Coordinate Value Calculation Unit

[0111] 15 Reference Value Storage Unit

[0112] 16 Data Comparison Unit

[0113] 17 Cause Determination Unit

[0114] 18 Cause Notification Unit

[0115] 111 CPU

[0116] 112 ROM

[0117] 113 RAM

[0118] 114 Non-Volatile Memory

Claims

1. A shape measurement device, characterized in that, it comprises: a coordinate value calculation unit that obtains the height of the surface of the measurement object from a distance sensor that relatively moves with respect to the surface of the measurement object, and calculates the coordinate value of the rise or fall existing on the surface of the measurement object based on the height; a reference value storage unit that stores a reference value of the coordinate value of the rise or fall; a data comparison unit that compares the reference value with the coordinate value calculated by the coordinate value calculation unit; and a cause determination unit that determines a coordinate value different from the reference value as inappropriate data, changes the speed condition of the relative speed between the measurement object and the distance sensor, compares the coordinate values calculated under different speed conditions, and determines the cause of the inappropriate data.

2. The shape measurement device according to claim 1, characterized in that, if the coordinate values calculated under the different speed conditions are the same, the cause determination unit determines the cause of the inappropriate data as the shape of the measurement object.

3. The shape measurement device according to claim 1, characterized in that, if the coordinate values calculated under the different speed conditions are different, the cause determination unit determines the cause of the inappropriate data as the flutter of the distance sensor.

4. The shape measurement device according to claim 1, characterized in that, in the case where no inappropriate data is detected as a result of changing the speed condition, the cause determination unit determines the cause of the inappropriate data as noise or speed condition.

5. The shape measurement device according to claim 1, characterized in that, the coordinate value is at least one of a mechanical coordinate, a relative coordinate with respect to an arbitrary reference point, and a distance between coordinates of at least two points or more.

6. The shape measurement device according to claim 1, characterized in that, the reference value of the coordinate value is calculated based on at least one of the ideal prototype of the measurement object and the design drawing of the measurement object.

7. The shape measurement device according to claim 1, characterized in that, the shape measurement device comprises a notification unit that notifies a user of the cause of the inappropriate data.

8. A storage medium that stores commands readable by a processor, characterized in that, by executing the commands by one or more of the processors to perform the following processing: obtaining the height of the surface of the measurement object from a distance sensor that relatively moves with respect to the surface of the measurement object, and calculating the coordinate value of the rise or fall existing on the surface of the measurement object based on the height; comparing the reference value of the coordinate value of the rise or fall with the coordinate value of the rise or fall existing on the surface of the measurement object; determining a coordinate value different from the reference value as inappropriate data, changing the speed condition of the relative speed between the measurement object and the distance sensor, comparing the coordinate values calculated under different speed conditions, and determining the cause of the inappropriate data.

Images