JP2018072201A - Shape measurement method and shape measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measurement method and a shape measurement device capable of improving a measurement accuracy when the measurement of the shape of a measurement object is performed in combination of plural kinds of measurement sensors.SOLUTION: A shape measurement method includes: measurement data acquisition steps S3 and S6 of acquiring plural kinds of measurement data acquired by measuring a shape of the same measurement object by plural kinds of measurement sensors each different in repetition accuracy, respectively; and a shape calculation step S8 of performing weighting corresponding to the repetition accuracy of a measurement sensor corresponding to the respective measurement data for plural kinds of measurement data acquired by the step of acquiring measurement data and calculating the shape based on the weighted plural kinds of measurement data.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a shape measuring method and a shape measuring apparatus for measuring the shape of a measurement object with a plurality of types of measurement sensors.

  As a shape measuring device for measuring the shape of a measuring object, for example, a three-dimensional measuring device that obtains the shape of a measuring object by detecting three-dimensional coordinate values of various measurement points of the measuring object using a measurement sensor ( A three-dimensional coordinate measuring device or a three-dimensional (coordinate) measuring machine is also known. As a measurement sensor used in such a three-dimensional measurement apparatus, a contact type measurement sensor and a non-contact type measurement sensor are well known.

  For example, a probe described in Patent Document 1 is known as a contact-type measurement sensor, and is a measurement sensor that performs measurement by directly contacting a measurement point of a measurement object. Although this contact-type measurement sensor has a merit that the repeatability is high, there is a demerit that the measurement time becomes long (the number of measurements per unit time is small).

  On the other hand, as a non-contact type measurement sensor, for example, an optical probe (line sensor) described in Patent Document 2 is known, and a measurement sensor that optically measures without contacting a measurement point of a measurement object. It is. Although this non-contact type measurement sensor has the merit that the measurement time is short (the number of measurements per unit time is large), there is a demerit that the repeatability is lower than that of the contact type measurement sensor.

  As described above, the contact-type measurement sensor and the non-contact-type measurement sensor have merits and demerits opposite to each other. For this reason, the measurement points of the measurement object are measured with a contact-type measurement sensor at intervals, and a large number of measurement points between the measurement points measured by the contact-type measurement sensor are measured with a non-contact type measurement sensor. By measuring, the merit and demerit of both measurement sensors can be balanced.

JP2015-75431A JP2015-59825A

  However, when a measurement object is measured using both a contact-type measurement sensor and a non-contact-type measurement sensor, measurement data of both measurement sensors having different repeatability are mixed. For this reason, for example, when the measurement data of both measurement sensors is subjected to fitting by the least square method to calculate the shape of the measurement object, the non-contact type has a low repetition accuracy (large variation) and a large number of measurements. Under the influence of the measurement data of the measurement sensor, there is a problem that the measurement accuracy of the shape of the measurement object is lowered.

  The present invention has been made in view of such circumstances, and a shape measuring method and a shape measuring apparatus capable of improving measurement accuracy when measuring the shape of an object to be measured in combination with different repeat accuracy. The purpose is to provide.

  A shape measurement method for achieving the object of the present invention is a measurement data acquisition for acquiring a plurality of types of measurement data obtained by measuring the shape of the same measurement object with a plurality of types of measurement sensors having different repeatability. Shape calculation that performs weighting corresponding to the repetition accuracy of the corresponding measurement sensor for the multiple types of measurement data acquired in the step and measurement data acquisition step, and calculates the shape based on the multiple types of weighted measurement data Steps.

  According to this shape measurement method, weighting corresponding to the repetition accuracy of the corresponding measurement sensors is performed on a plurality of types of measurement data, compared with the case where the shape of the measurement object is calculated without weighting. Thus, the measurement accuracy of the shape of the measurement object can be improved.

  In the shape measurement method according to another aspect of the present invention, in the shape calculation step, a plurality of types of measurement data are weighted with a weighting coefficient obtained by squaring the reciprocal of the repeat accuracy of the corresponding measurement sensor. Thereby, the measurement accuracy of the shape of the measurement object can be improved.

  In the shape measurement method according to another aspect of the present invention, the plurality of types of measurement sensors include a contact-type first measurement sensor and a non-contact-type second measurement sensor having a lower repeatability than the first measurement sensor. The measurement data acquisition step is included as a plurality of types of measurement data, the first measurement data obtained by measuring the shape with the first measurement sensor, the first measurement data obtained by measuring the shape with the second measurement sensor, and the first Second measurement data having a larger number of measurements than measurement data is acquired. When measuring a large number of measurement points in a short time using a measurement sensor with a high repeatability and a long measurement time and a measurement sensor with a low repeatability and a short measurement time. Even so, the measurement accuracy of the shape of the measurement object can be improved.

  In the shape measurement method according to another aspect of the present invention, when a plurality of types of measurement sensors includes a third measurement sensor having different repeatability in a plurality of axial directions, the shape calculation step uses the third measurement sensor. Weighting corresponding to the repetition accuracy for each of the plurality of axis directions is performed on each component in the plurality of axis directions of the obtained measurement data. Thereby, the measurement precision of the shape of a measuring object can be improved more.

  In the shape measurement method according to another aspect of the present invention, the shape calculation step weights a plurality of types of measurement data with reference to a storage unit that stores the repetition accuracy for each type of measurement sensor. Thereby, it is possible to perform weighting corresponding to the repetition accuracy of the corresponding measurement sensors for a plurality of types of measurement data.

  In the shape measuring method according to another aspect of the present invention, the shape calculating step calculates a shape using a least square method based on a plurality of weighted types of measurement data. Accordingly, the shape of the measurement object can be easily calculated using a known least square method.

  A shape measuring apparatus for achieving the object of the present invention is a measurement data acquisition for acquiring a plurality of types of measurement data obtained by measuring the shape of the same measurement object with a plurality of types of measurement sensors having different repeatability. Shape calculation that calculates the shape based on the weighted multiple types of measurement data and weights corresponding to the repeatability of the corresponding measurement sensors for the multiple types of measurement data acquired by the measurement unit and the measurement data acquisition unit A section.

  The shape measuring method and the shape measuring apparatus of the present invention can improve the measurement accuracy when measuring the shape of the measurement object in combination with different repeatability.

It is a front view of the three-dimensional measuring apparatus which is an example of the shape measuring apparatus of this invention. It is a side view of a three-dimensional measuring apparatus. It is an external appearance perspective view of the measurement head which hold | maintains the probe so that attachment or detachment is possible. It is an external appearance perspective view of the measuring head holding the line sensor so that attachment or detachment is possible. It is the schematic which showed schematic structure of the line sensor. It is the schematic of the measuring object whose length of a X-axis direction is X. 6 is a graph showing a distribution of measurement data (actual measurement length x) obtained by repeatedly measuring the length of a measurement object in the X-axis direction with a probe and a line sensor, respectively. It is explanatory drawing for demonstrating an example in the case of measuring the same measuring object using a probe and a line sensor together. It is a block diagram which shows the electric constitution of a control part. It is a flowchart which shows the flow of the shape measurement of the measuring object by a three-dimensional measuring apparatus. It is explanatory drawing for demonstrating the effect of a three-dimensional measuring apparatus. 3 is a schematic view of a measurement object used in Example 1 and Example 2. FIG. 3 is a graph showing measurement results of Example 1. 6 is a graph showing measurement results of Example 2. 6 is a schematic view of a measurement object used in Example 3. FIG. 10 is a graph showing measurement results of Example 3. It is a block diagram which shows the electric constitution of the control part of other embodiment. It is explanatory drawing for demonstrating an example of non-contact-type measurement sensors other than a line sensor.

[Configuration of three-dimensional measuring device]
FIG. 1 is a front view of a three-dimensional measuring apparatus 10 as an example of the shape measuring apparatus of the present invention, and FIG. 2 is a side view of the three-dimensional measuring apparatus 10. This three-dimensional measuring apparatus 10 uses a plurality of types (two types in this embodiment) of measurement sensors 11 having different repeatability, and uses the three-dimensional coordinate values (measurement positions) of the same measurement object W (measurement positions). X-axis direction, Y-axis direction, and Z-axis direction coordinate values) are measured, and the shape of the measuring object W is calculated. The shape of the measurement target W here includes the three-dimensional shape, the two-dimensional shape, the surface shape, the contour shape, and various dimensional shapes such as a length or a diameter of the measurement target W.

  Note that the X axis, the Y axis, and the Z axis in FIGS. 1 and 2 are a machine coordinate system that is a coordinate system determined based on a machine coordinate origin unique to the three-dimensional measurement apparatus 10. Further, the repeatability is a variation width (standard deviation σ) of measurement values by repeated measurement.

  As shown in FIGS. 1 and 2, the three-dimensional measuring apparatus 10 includes a gantry 12, a table 14 (surface plate) provided on the gantry 12, and a right Y carriage 16 </ b> R erected on both ends of the table 14. And a left Y carriage 16L, and an X guide 18 that connects upper portions of the right Y carriage 16R and the left Y carriage 16L. The right Y carriage 16R, the left Y carriage 16L, and the X guide 18 constitute a portal frame 19.

  On the upper surface of the table 14, a measurement object W and a replacement magazine 27 (also referred to as a replacement rack) to be described later are arranged. Further, on the upper surface and side surfaces of both ends of the table 14, sliding surfaces are formed on which the right Y carriage 16R and the left Y carriage 16L slide along the Y-axis direction. The right Y carriage 16R and the left Y carriage 16L are provided with air bearings (not shown) at positions facing the sliding surface of the table 14. Thus, the right Y carriage 16R and the left Y carriage 16L can move in the Y-axis direction together with the X guide 18.

  An X carriage 20 is attached to the X guide 18. A sliding surface on which the X carriage 20 slides is formed in the X guide 18 along the X-axis direction. The X carriage 20 is provided with an air bearing (not shown) at a position facing the sliding surface of the X guide 18. Thereby, the X carriage 20 is movable in the X-axis direction.

  A Z carriage (also referred to as a Z spindle) 22 is attached to the X carriage 20. The X carriage 20 is provided with an air bearing (not shown) for guiding the Z carriage 22 in the Z axis direction. Thus, the Z carriage 22 is held by the X carriage 20 so as to be movable in the Z-axis direction. At the lower end of the Z carriage 22, a measurement head 24 that selectively holds a plurality of types of measurement sensors 11 in a detachable manner is attached.

  Although not shown, the three-dimensional measuring apparatus 10 includes a Y-axis drive unit that moves the portal frame 19 in the Y-axis direction, an X-axis drive unit that moves the X carriage 20 in the X-axis direction, and a Z carriage. A first drive unit 32 (see FIG. 9) including a Z-axis drive unit that moves 22 in the Z-axis direction is provided. Thereby, the measurement head 24 and the measurement sensor 11 can be moved in the triaxial direction (XYZ axial direction) orthogonal to each other.

  A Y-axis linear scale (not shown) is provided at the end of the table 14 on the right Y carriage 16R side. The X guide 18 is provided with an X-axis linear scale (not shown), and the Z carriage 22 is provided with a Z-axis linear scale (not shown).

  On the other hand, the right Y carriage 16R is provided with a Y-axis detector (not shown) that reads the Y-axis linear scale. The X carriage 20 is provided with an X-axis detector (not shown) and a Z-axis detector (not shown) for reading the X-axis linear scale and the Z-axis linear scale, respectively. The detection result of each detection unit is output to the control unit 26 via the controller 25.

  The measurement head 24 selectively holds a plurality of types of measurement sensors 11 set in the exchange magazine 27 in a detachable manner. As a method for detachably holding the measurement sensor 11 by the measurement head 24, various methods such as a connector method or a magnet attaching / detaching method can be adopted.

  The exchange magazine 27 is placed on one end of the upper surface of the table 14 in the Y-axis direction. The replacement magazine 27 has sensor support portions 27a that individually support a plurality of types of measurement sensors 11. In addition, the support system of the measurement sensor 11 by the sensor support part 27a is not specifically limited.

  The three-dimensional position information of each sensor support portion 27a of the exchange magazine 27 is input to the control unit 26 of the three-dimensional measurement apparatus 10 in advance. For this reason, the control unit 26 drives the carriages 16R, 16L, 20, and 22 in accordance with an instruction from the operator or a program created in advance, and the measurement sensor 11 that uses the measurement head 24 to measure the measurement object W. After being moved to (sensor support portion 27a), the measurement sensor 11 is detachably held by the measurement head 24.

  In addition, when replacing the measurement sensor 11 held by the measurement head 24, the control unit 26 drives each carriage 16R, 16L, 20, 22 to move the measurement head 24 to the corresponding sensor support 27a. After the movement, the holding of the measurement sensor 11 by the measurement head 24 is released, and the measurement sensor 11 is returned to the original sensor support portion 27a. Next, the control unit 26 drives each carriage 16R, 16L, 20, 22 to move the measurement head 24 to the next measurement sensor 11 (sensor support unit 27a), and then moves the measurement head 24 to the measurement sensor 24. 11 is detachably held. Thereby, replacement | exchange of the measurement sensor 11 of the measurement head 24 can be performed automatically.

  In this embodiment, two types of probes 29 of a contact type touch trigger and a line sensor 30 are used as the plurality of types of measurement sensors 11, and the shape of the measurement object W is formed by using these probes 29 and the line sensor 30 together. taking measurement.

  FIG. 3 is an external perspective view of the measuring head 24 holding the probe 29 in a detachable manner. FIG. 4 is an external perspective view of the measurement head 24 holding the line sensor 30 in a detachable manner.

  As shown in FIGS. 3 and 4, the measurement head 24 is, for example, a 5-axis simultaneous control measurement head provided with a stepless positioning mechanism. The measurement head 24 includes a second drive unit 33 such as a motor (see FIG. 9) that holds and rotates the probe 29 and the line sensor 30 around two rotation axes R1 and R2 that are orthogonal to each other. ) Is provided. As a result, the measurement head 24 steps the rotation angle φ around the rotation axis R1 of the probe 29 and the line sensor 30 and the rotation angle θ around the rotation axis R2 of the probe 29 and the line sensor 30 steplessly. Can be adjusted. As a result, the measurement head 24 can arbitrarily displace (rotate) the postures of the probe 29 and the line sensor 30.

  The measurement head 24 is provided with a rotation angle detection unit (not shown) such as a rotary encoder that detects the rotation angles θ and φ of the probe 29 and the line sensor 30. The detection result by the rotation angle detection unit is output to the control unit 26 via the controller 25. Hereinafter, the aforementioned X-axis / Y-axis / Z-axis detection unit and rotation angle detection unit are simply referred to as each detection unit 35 (see FIG. 9).

  Returning to FIG. 1, the controller 25 is provided with an operation unit (not shown) for adjusting the positions and postures of the probe 29 and the line sensor 30 when the three-dimensional measuring apparatus 10 is in the manual measurement mode. Yes. The controller 25 controls the position and posture of the probe 29 and the line sensor 30 by controlling the first drive unit 32 and the second drive unit 33 (see FIG. 9) according to the operation input to the operation unit in the manual measurement mode. And displace. On the other hand, when the three-dimensional measuring apparatus 10 is in the automatic measurement mode, the controller 25 controls the first driving unit 32 and the second driving unit 33 under the control of the control unit 26 to control the probe 29 and the line sensor 30. Displace the position and posture.

  The controller 25 is connected to the above-described detection units 35 (see FIG. 9), the probe 29, the line sensor 30, and the like, and outputs signals output from these units to the control unit 26.

  The control unit 26 uses various arithmetic processing devices such as a personal computer, for example, and comprehensively controls the operation of each unit of the three-dimensional measurement apparatus 10. In the automatic measurement mode described above, the control unit 26 controls the first drive unit 32 and the second drive unit 33 to cause the probe 29 and the line sensor 30 to measure the measurement point of the measurement target W.

  Further, the control unit 26 calculates the shape of the measurement object W based on the measurement results (three-dimensional coordinates) of the measurement points of the measurement object W by the probe 29 and the line sensor 30, as will be described in detail later.

  Returning to FIG. 3, the probe 29 corresponds to a contact-type measurement sensor (second measurement sensor) of the present invention, and a base end side thereof is detachably held by the measurement head 24. A proximal end of a stylus 29a is attached to the distal end of the probe 29, and a contact 29b (also referred to as a distal sphere) is attached to the distal end of the stylus 29a.

  Further, the probe 29 has a contact detection sensor (not shown) for detecting the presence or absence of contact of the contact 29b with the measurement object W and the amount of displacement of the stylus 29a caused by the contact of the contact 29b with the measurement object W. Is provided. A detection signal of the contact detection sensor is output to the control unit 26 via the controller 25. Thereby, the control unit 26 determines the three-dimensional coordinates of the measurement point based on the detection result of each detection unit 35 at the moment when the contact 29b at the tip of the probe 29 (stylus 29a) contacts the measurement point of the measurement object W. To detect.

  FIG. 5 is a schematic diagram showing a schematic configuration of a line sensor 30 corresponding to the non-contact type measurement sensor (first measurement sensor) of the present invention. As shown in FIG. 5, the line sensor 30 uses, for example, a diffuse reflection light receiving type laser displacement meter (also referred to as a laser probe) that employs a triangulation method in this embodiment. The diffuse reflection light receiving type line sensor 30 includes an incident part 30a and a detection part 30b.

  The incident portion 30 a is configured by a semiconductor laser light source (not shown), a light projecting lens, and the like, and makes the laser light LA incident on the measurement point of the measurement target W. The laser beam LA incident on the measurement point is diffusely reflected, and the diffusely reflected laser beam LA enters the detection unit 30b.

  The detection unit 30b includes a light receiving lens (not shown) and a CCD (Charge Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type imaging device, and laser light diffusely reflected at the measurement point. LA is incident on the imaging surface of the imaging device. This imaging device has an imaging surface in which a plurality of pixels are two-dimensionally arranged, and detects light for each pixel. The laser beam LA described above is incident on the imaging surface as spot light.

  Here, the incident position (spot position) of the laser beam LA on the imaging surface of the imaging device is displaced according to the positional relationship between the line sensor 30 and the measurement point at which the laser beam LA is diffusely reflected. For this reason, the distance from the line sensor 30 to the measurement point, which is the reflection point of the laser beam LA, can be detected based on the detection result of the received light amount for each pixel of the image sensor.

  The detection unit 30 b outputs a light reception signal indicating the amount of light received for each pixel of the image sensor to the control unit 26 via the controller 25 as a detection result of the diffusely reflected laser light LA. Thereby, the control part 26 detects the three-dimensional coordinate of the measurement point of the measuring object W based on the distance detection result by the line sensor 30, and the detection result of each above-mentioned detection part 35 (refer FIG. 9). Then, by moving the line sensor 30 along the measurement surface of the measurement object W, the three-dimensional coordinates of each measurement point on the measurement surface can be detected continuously along the movement direction of the line sensor 30. .

  FIG. 6 is a schematic view of the measuring object W having a length X in the X-axis direction. FIG. 7 is a graph showing a distribution of measurement data (actual length x) obtained by repeatedly measuring the length in the X-axis direction of the measurement object W shown in FIG. 6 with the probe 29 and the line sensor 30, respectively. It is. The actual measurement length x is a length from the reference position RP measured by the probe 29 and the line sensor 30 as the length in the X-axis direction of the measurement object W to the actual measurement point AP.

  The probe 29 that is a contact-type measurement sensor and the line sensor 30 that is a non-contact-type measurement sensor have different repeatability and measurement time (number of measurements per unit time). Specifically, the repeatability (standard deviation σ1) of the probe 29 is higher than the repeatability (standard deviation σ2) of the line sensor 30 (σ1 <σ2). For this reason, when the probe 29 and the line sensor 30 repeatedly measure the length of the measurement target W in the X-axis direction, the probe 29 has less variation in measurement data (actual measurement length x) than the line sensor 30. Become.

  On the other hand, since the measurement time of the probe 29 is longer than the measurement time of the line sensor 30, the line sensor 30 can increase the number of measurements compared to the probe 29.

  As described above, the probe 29 and the line sensor 30 having different repeatability have the merits and demerits that are mutually contradictory. For this reason, in this embodiment, in order to balance both merit and demerit, the measurement object W is measured using the probe 29 and the line sensor 30 together.

  FIG. 8 is an explanatory diagram for explaining an example when the same measurement object W is measured using the probe 29 and the line sensor 30 together. As shown in FIG. 8, in the present embodiment, the measurement points (contact measurement points P1) of the measurement object W are measured with the probe 29 at intervals, and a plurality of measurement points are set between the measurement points measured by the probe 29. The line sensor 30 measures a number of measured points (non-contact measurement point P2).

  In this embodiment, when calculating the shape of the measurement object W from the measurement data measured by both the probe 29 and the line sensor 30, the measurement data of the line sensor 30 having a low repeatability and a large number of measurements is calculated. The shape is calculated so that the influence does not become dominant, that is, the shape of the measurement object W is not dragged by the measurement data of the line sensor 30. Specifically, when calculating the shape of the measurement object W from the measurement data obtained by the probe 29 and the line sensor 30, the control unit 26 takes into account the repetition accuracy of both the probe 29 and the line sensor 30. Perform the operation.

[Configuration of control unit]
FIG. 9 is a block diagram showing an electrical configuration of the control unit 26. As illustrated in FIG. 9, the control unit 26 includes various arithmetic units including a CPU (Central Processing Unit) or an FPGA (field-programmable gate array), a processing unit, a memory, and the like. The control unit 26 executes a control program (not shown) read out from a memory or the like, whereby a measurement control unit 40, a measurement data acquisition unit 41, a storage unit 42, a shape calculation unit 43, and a display control unit 44. Function as.

  The measurement control unit 40 is configured so that the first drive unit 32 and the second drive unit 33 are connected via the controller 25 based on a part program (measurement path information) (not shown) created in advance when the coordinate measuring apparatus 10 is in the automatic measurement mode. And the measurement points (contact measurement point P1, non-contact measurement point P2) of the measuring object W are automatically measured by the probe 29 and the line sensor 30, respectively.

  In addition, when the measurement by either one of the probe 29 and the line sensor 30 is completed, the measurement control unit 40, based on a sensor replacement program (not shown) created in advance, the first drive unit 32 and the first sensor via the controller 25. 2 The driving unit 33 is driven to move the measuring head 24 to the other of the probe 29 and the line sensor 30 supported by the sensor support unit 27a. Next, the measurement control unit 40 drives the measurement head 24 to replace one of the probe 29 and the line sensor 30 held by the measurement head 24 with the other.

  When the three-dimensional measuring apparatus 10 is in the manual measurement mode, the operator operates the controller 25 to drive the first drive unit 32, the second drive unit 33, and the measurement head 24, thereby causing the probe 29 and the line sensor 30 to operate. Move, measure, and replace

  When the probe 29 is detachably held on the measurement head 24, the measurement data acquisition unit 41 uses the controller 25 to detect the detection result of the contact detection sensor of the probe 29 and the detection result of each detection unit 35. To get. Thereby, the measurement data acquisition part 41 acquires the measurement data (1st measurement data) which show the three-dimensional coordinate of each contact measurement point P1 of the measurement target object W which the probe 29 contacted. Then, the measurement data acquisition unit 41 outputs measurement data for each contact measurement point P <b> 1 of the measurement object W to the shape calculation unit 43.

  On the other hand, when the line sensor 30 is detachably held on the measurement head 24, the measurement data acquisition unit 41 detects the detection result of the detection unit 30b (imaging element) and the detection result of each detection unit 35 via the controller 25. And get. Thereby, the measurement data acquisition part 41 acquires the measurement data (2nd measurement data) which shows the three-dimensional coordinate of each non-contact measurement point P2 of the measurement object W in which the laser beam LA was incident from the line sensor 30. Can do. Then, the measurement data acquisition unit 41 outputs measurement data for each non-contact measurement point P <b> 2 of the measurement object W to the shape calculation unit 43.

  The storage unit 42 stores repetition accuracy information 46 indicating the repetition accuracy for each type of each measurement sensor 11 (probe 29, line sensor 30). Since the repetition accuracy for each type of the measurement sensor 11 is known information, the repetition accuracy information 46 is created in advance and stored in the storage unit 42. In addition, although illustration is abbreviate | omitted in the memory | storage part 42, the part program mentioned above, a sensor exchange program, the calculation result of the shape calculating part 43 mentioned later, etc. are memorize | stored.

<Calculation processing of the shape of the measurement object>
The shape calculation unit 43 is based on the repetition accuracy information 46 acquired by referring to the storage unit 42 and the measurement data for each contact measurement point P1 and each non-contact measurement point P2 acquired from the measurement data acquisition unit 41. The shape of the object W is calculated. Specifically, the shape calculation unit 43 performs weighting on the measurement data for each contact measurement point P1 and each non-contact measurement point P2 based on the repetition accuracy of the corresponding measurement sensor 11 (probe 29, line sensor 30). Then, the shape is calculated using the least square method based on each weighted measurement data. In this embodiment, when the repetition accuracy of the probe 29 and the line sensor 30 is σ1 and σ2, respectively, each measurement data is weighted by the square of the reciprocal of σ1 and σ2. That is, the measurement data at the contact measurement point P1 is weighted using a weight coefficient of (1 / σ1) ² , and the measurement data at the non-contact measurement point P2 is weighted by (1 / σ2) ² Is used for weighting.

  Hereinafter, as an example of the calculation processing of the shape of the measurement target W by the shape calculation unit 43, a case where the length of the measurement target W shown in FIG. 6 is measured will be described. In order to clarify the difference in the shape calculation process in the comparative example (conventional example), first, the calculation process in the comparative example will be described.

(Comparison example calculation processing)
In the comparative example, when the measurement data (measurement point) for each contact measurement point P1 by the probe 29 is x1, and the measurement data (measurement point) for each non-contact measurement point P2 by the line sensor 30 is x2, the measurement data x1, The length X (estimation) of the measuring object W is calculated from x2. In the comparative example, since the calculation using the repeatability (standard deviation) of the probe 29 and the line sensor 30 is not performed, the same repeatability “σ” is assumed here.

  When the probability distribution of the measurement data x1 is P (x1) and the probability distribution of the measurement data x2 is P (x2), the probability distribution P (x1) is expressed by the following [Equation 1], and the probability distribution P ( x2) is expressed by the following [Equation 2].

  Based on the above [Equation 1] and the above [Equation 2], the joint probability distribution of the measurement data x1 and x2 is expressed by the following [Equation 3].

The length X of the measuring object W that maximizes the above [Equation 3] _{Conventionally} , the following [Equation 4], which is an ordinary least square method, is obtained from the maximum X, and [Expression 5]

(Calculation processing of this embodiment)
In addition to the measurement data x1 and x2, the shape calculation unit 43 according to the present embodiment acquires information on the repeat accuracy σ1 of the probe 29 and the repeat accuracy σ2 of the line sensor 30, and thus the probability distribution P ( x1) is expressed by the following [Equation 6], and the probability distribution P (x2) of the measurement data x2 is expressed by the following [Equation 7].

  Based on the above [Equation 6] and the above [Equation 7], the simultaneous probability distribution of the measurement data x1 and x2 is expressed by the following [Equation 8].

The _{improvement in} the length X of the measuring object W that maximizes the above [Equation 8] is X that maximizes the following [Equation 9], which is an equation of the least square method that reflects the repeatability σ1 and σ2. And is represented by the following [Equation 10].

As described above, the shape calculation unit 43 is based on the repetition accuracy information 46 acquired from the storage unit 42 and the measurement data for each contact measurement point P1 and each non-contact measurement point P2 acquired from the measurement data acquisition unit 41. The length X _improvement of the object W is processed.

Here, it expressed when finding the Equation 5 standard deviation σ _conventional length X _conventional computed by the comparative example in the number 11 the following formula. On the other hand, when the standard deviation σ _improvement of the length X _improvement of the above [Equation 10] calculated in the present embodiment is obtained, it is expressed by the following [Equation 12].

  When the above [Equation 11] and [Equation 12] are compared, the following [Equation 13] is established from the known arithmetic mean geometrical relationship.

In the above [Equation 13], the measurement data x1 and x2 measured at different measurement numbers by the probe 29 and the line sensor 30 having different repetition accuracy are x1 ≠ x2, and therefore, the upper part of the above [Equation 13] The shown inequality relation always holds. Therefore, since the direction of length X _improvement is calculated in the present embodiment it is not fluctuated values than the length X _{conventionally} calculated by the comparative example, thereby improving the measurement accuracy.

  In the above example, the case where the length of the measurement object W shown in FIG. 6 is calculated has been described, but the measurement sensor 11 is similarly applied to the measurement of various shapes of various measurement objects W. The shape is calculated by weighting with repetition accuracy for each type. The shape calculation unit 43 stores the calculation result of the shape of the measurement object W in the storage unit 42 and outputs the result to the display control unit 44.

  The display control unit 44 displays the calculation result of the shape of the measurement object W input from the shape calculation unit 43 on the display unit 48 that is wired or wirelessly connected to the control unit 26.

[Operation of three-dimensional measuring device]
Next, a method for measuring the shape of the measuring object W by the three-dimensional measuring apparatus 10 having the above configuration will be described with reference to FIG. Here, FIG. 10 is a flowchart showing a flow of measuring the shape of the measuring object W by the three-dimensional measuring apparatus 10. The three-dimensional measuring apparatus 10 has an automatic measurement mode and a manual measurement mode. Here, the case where the automatic measurement mode is set will be described as an example. In addition, it is assumed that the part program for measuring the measurement object W and the sensor replacement program for replacing the measurement sensor 11 (probe 29, line sensor 30) are created in advance and stored in the storage unit 42 or the like. Do.

  After the operator sets the measurement object W on the table 14, when the measurement start operation is performed by operating the controller 25, the measurement control unit 40 is based on the sensor replacement program stored in the storage unit 42 or the like. The first drive unit 32 and the second drive unit 33 are driven via the reference numeral 25 to move the measurement head 24 to the probe 29 supported by the sensor support unit 27a. Next, the measurement control unit 40 drives the measurement head 24 to cause the measurement head 24 to hold the probe 29 detachably (step S1).

  After the probe 29 is detachably held on the measuring head 24, the probe 29 is calibrated automatically or manually using a known calibration jig. Since the calibration method of the probe 29 is known, a specific description is omitted here.

  Next, the measurement control unit 40 drives the first drive unit 32 and the second drive unit 33 via the controller 25 based on the part program stored in the storage unit 42 and the like, and the probe 29 measures each measurement object. Each contact measurement point P1 of W is automatically measured (step S2).

  At this time, the measurement data acquisition unit 41 makes contact with the probe 29 based on the detection result of the contact detection sensor (not shown) of the probe 29 acquired via the controller 25 and the detection result of each detection unit 35. Measurement data indicating the three-dimensional coordinates of each contact measurement point P1 of the measured object W is acquired (step S3, corresponding to the measurement data acquisition step of the present invention). Thereby, although the number of measurements is small, highly accurate measurement data with few variations can be obtained. Then, the measurement data acquisition unit 41 outputs the acquired measurement data for each contact measurement point P1 to the shape calculation unit 43.

  When the measurement of the measurement object W by the probe 29 is completed, the measurement control unit 40, based on the sensor replacement program stored in the storage unit 42 and the like, via the controller 25, the first drive unit 32 and the second drive unit 33. And the measurement head 24 is moved to the sensor support portion 27a that has supported the probe 29. Then, the measurement control unit 40 drives the measurement head 24 to release the holding of the probe 29 by the measurement head 24. As a result, the probe 29 is removed from the measurement head 24 and supported by the original sensor support portion 27a.

  Next, the measurement control unit 40 drives the first drive unit 32 and the second drive unit 33 through the controller 25 to move the measurement head 24 to the line sensor 30 supported by the sensor support unit 27a. Next, the measurement control unit 40 drives the measurement head 24 to cause the measurement head 24 to hold the line sensor 30 detachably (step S4). As a result, the probe 29 held by the measurement head 24 is replaced with the line sensor 30. Note that the line sensor 30 may be calibrated using a calibration jig or the like after replacement with the line sensor 30.

  When the line sensor 30 is detachably held on the measurement head 24, the measurement control unit 40 drives the first drive unit 32 and the second drive unit 33 via the controller 25 based on the part program, and the line sensor 30 30, each non-contact measurement point P2 of the measurement object W is automatically measured (step S5).

  At this time, the measurement data acquisition unit 41 receives the laser beam LA from the incident unit 30a based on the detection result of the detection unit 30b (imaging element) acquired via the controller 25 and the detection result of each detection unit 35. The measurement data indicating the three-dimensional coordinates of each non-contact measurement point P2 of the measured object W is acquired (step S6, corresponding to the measurement data acquisition step of the present invention). Thereby, although variation becomes large, the measurement data of many non-contact measurement points P2 can be acquired in a short time. Then, the measurement data acquisition unit 41 outputs the acquired measurement data for each non-contact measurement point P2 to the shape calculation unit 43.

  3 and 4, the measurement head 24 can arbitrarily displace (rotate) the postures of the probe 29 and the line sensor 30 in the present embodiment. Even if it has a complicated shape, each contact measurement point P1 and each non-contact measurement point P2 of the measuring object W can be measured. That is, the shape of the measurement object W having a complicated shape can be measured.

  The shape calculation unit 43 acquires the repetition accuracy information 46 with reference to the storage unit 42 before and after the input of each measurement data from the measurement data acquisition unit 41, and sets the repetition accuracy of the probe 29 and the line sensor 30. It discriminate | determines (step S7). In addition, the timing of acquisition of the repetition accuracy information 46 by the shape calculation unit 43 is not particularly limited, and the repetition accuracy information 46 may be acquired in a step before step S6.

  Then, the shape calculation unit 43 performs weighting corresponding to the repetition accuracy of the probe 29 on the measurement data for each contact measurement point P1, and the repetition accuracy of the line sensor 30 on the measurement data for each non-contact measurement point P2. Are weighted, and the weighted measurement data is subjected to fitting by the least square method to calculate the shape of the measuring object W. Specifically, the shape calculation unit 43 calculates the shape of the measurement object W using the above-described [Expression 5] to [Expression 10] (step S8, corresponding to the shape calculation step of the present invention).

  Next, the shape calculation unit 43 outputs the calculation result of the shape of the measurement object W to the storage unit 42 and the display control unit 44, respectively. Thereby, the calculation result of the shape of the measurement object W is stored in the storage unit 42 and displayed on the display unit 48 by the display control unit 44 (step S9).

[Effects of the three-dimensional measuring apparatus of this embodiment]
FIG. 11 is an explanatory diagram for explaining the effect of the three-dimensional measuring apparatus 10 of the present embodiment. In addition, in FIG. 11, the case where the shape of the surface of the measuring object W is calculated will be described as an example. When the measurement data obtained by the probe 29 and the line sensor 30 having different repeatability are simply fitted by the least square method, as in the comparative example (conventional example) indicated by reference numeral 50 in the upper part of FIG. The calculation result of the shape of the measurement object W is affected by the measurement data of the line sensor 30 having a low repetition accuracy and a large number of measurements. As a result, the measurement accuracy of the shape of the measuring object W decreases.

  On the other hand, in the present embodiment, the measurement data obtained by the probe 29 and the line sensor 30 having different repetition accuracy is weighted corresponding to the repetition accuracy, and the weighted measurement data is measured by the least square method. Fitting is performed. As a result, the influence of the measurement data of the line sensor 30 on the calculation result of the shape of the measurement object W is suppressed as in the present embodiment indicated by reference numeral 51 in the lower part of FIG. The influence of the measurement data of the few probes 29 on the calculation result of the shape of the measurement object W increases. As a result, the measurement with the probe 29 with a high repeatability and a long measurement time and the measurement with the line sensor 30 with a low repeatability and a short measurement time are used together, and a large number of measurement points of the measurement object W are measured in a short time. Even in this case, the measurement accuracy of the shape of the measuring object W can be improved.

  Examples 1 to 3 performed for the present invention will be described below to specifically explain the present invention. However, the present invention is not limited to these examples.

<Example 1>
FIG. 12 is a schematic view of a measurement object W1 used in Example 1 and Example 2 described later. As shown in FIG. 12, in the first embodiment, a three-dimensional measuring device 10 (Zyzax SVA NEX manufactured by Tokyo Seimitsu Co., Ltd.) is used to provide a cylinder having a central axis parallel to the Z axis and a radius r of 1.0 mm. The radius r of the measurement object W1 that is a body was measured. First, the radius r of the measurement object W1 was measured at five points using a probe 29 (TP manufactured by Renishaw Co., Ltd.) having a repetition accuracy of σ1 = 1 μm. Further, the radius r of the measurement object W1 was measured at 500 points using a line sensor 30 (TDS manufactured by Renishaw Co., Ltd.) having a repetition accuracy of σ2 = 10 μm.

  Next, after weighting the measurement data of the probe 29 and the line sensor 30 with the corresponding repeatability σ1 and σ2 respectively by the control unit 26 (shape calculation unit 43), the fitting by the least square method is performed. Then, the distribution of the radius r of the measurement object W1 (deviation δr from the radius r = 1.0 mm) was calculated (see the above-mentioned [Equation 5] to [Equation 10]). And the measurement by the probe 29 and the line sensor 30, and the calculation by the shape calculating part 43 were repeated 1000 times.

  FIG. 13 is a graph showing the measurement results of Example 1 (distribution of deviation δr from radius r = 1.0 mm). In FIG. 13, “improvement 505_Point” indicates the distribution of the radius r of the measurement object W1 calculated by the shape calculation unit 43 of the present embodiment (deviation amount δr from radius r = 1.0 mm). Further, “conventional 505_Point” is a distribution of the radius r of the measurement object W1 calculated by performing the fitting by the least square method without performing the weighting with the repetition accuracy σ1 and σ2.

  Furthermore, “SI1 — 5Point” is a distribution of the radius r of the measurement object W1 calculated by fitting the measurement data of the five points measured by the probe 29 by the least square method. Furthermore, “SI10_500Point” is a distribution of the radius r of the measurement object W1 calculated by fitting the measurement data of 500 points measured by the line sensor 30 by the least square method. Each distribution shown in FIG. 13 shows an average value of 1000 measurements.

  As shown in FIG. 13, “improvement 505_Point” of the present embodiment has the largest number of data of “δr = 0 μmm”, and the radius r of the measurement object W1 is larger than that of “conventional 505_Point” of the comparative example. It was confirmed that the measurement accuracy was improved.

<Example 2>
In Example 2, the number of measurements of the line sensor 30 with respect to the measurement object W1 was reduced to 5 points, and the same measurement as in Example 1 was performed.

  FIG. 14 is a graph showing the measurement results of Example 2 (distribution of deviation δr from radius r = 1.0 mm). In FIG. 14, “Improved 10_Point” indicates the distribution of the radius r of the measurement target W <b> 1 calculated by the shape calculation unit 43 of the present embodiment. “Conventional 10_Point” is a distribution of the radius r of the measurement object W1 calculated by performing the fitting by the least square method without performing the weighting with the repetition accuracy σ1 and σ2. Further, “SI1_5Point” is the same as that in the first embodiment, and “SI10_5Point” is the radius r of the measurement object W1 calculated by performing fitting by the least square method on the five measurement data measured by the line sensor 30. Distribution.

  As shown in FIG. 14, in the “conventional 10_Point” of the comparative example, the distribution of the radius r of the measurement object W1 (the deviation δr from the radius r = 1.0 mm) is influenced by the measurement data of the line sensor 30. It was confirmed that the variation width of the was increased. On the other hand, “improvement 10_Point” of the present embodiment performs weighting with repetition accuracy σ1 and σ2 to suppress the influence of the measurement data of the line sensor 30, and the radius r of the measurement object W1 than the comparative example. It was confirmed that the variation width of the distribution was small. In addition, it was confirmed that “improvement 10_Point” of the present embodiment has the largest number of data of “δr = 0 μmm” than the comparative example. As a result, in this embodiment, it was confirmed that the measurement accuracy of the radius r of the measurement object W1 was improved as compared with the comparative example.

<Example 3>
FIG. 15 is a schematic diagram of the measurement object W2 used in the third embodiment. In the third embodiment, the three-dimensional measuring apparatus 10 is used to measure the radius r in the X-axis direction with reference to the center coordinates (0, 0, 0) of the measuring object W2 that is a sphere having a radius r of 1.0 mm. 29 and the line sensor 30 were measured under the same conditions as in Example 1.

  FIG. 16 is a graph showing the measurement results of Example 3 (distribution of deviation amount δr from radius r = 1.0 mm). As shown in FIG. 16, the “improved 505_Point” of the present embodiment has the largest number of data of “δr = 0 μmm”, and the radius r of the measurement object W2 compared to “Conventional 505_Point” of the comparative example and the like. It was confirmed that the measurement accuracy of (radius r in the X axis direction: X coordinate) was improved.

  As described above, when calculating various shapes (radius r) of the measurement objects W1 and W2 based on the measurement data of the probe 29 and the line sensor 30, the repetition accuracy σ1 and σ1 corresponding to the measurement data, respectively. It was confirmed that the shape measurement accuracy is improved by weighting with σ2.

[Others]
FIG. 17 is a block diagram illustrating an electrical configuration of the control unit 26 according to another embodiment. In the above embodiment, the description has been made assuming that the repeat accuracy of the probe 29 and the line sensor 30 in the XYZ axis directions (multiple axis directions) are all the same. On the other hand, the present invention is also applied to the case where measurement is performed using the measurement sensor 11 (corresponding to the third measurement sensor of the present invention) such as the probe 29 and the line sensor 30 in which all the repeatability in the XYZ axis directions are not the same. Applicable.

  Specifically, as illustrated in FIG. 17, when the shape calculation unit 43 performs weighting based on repetition accuracy on the measurement data obtained by the measurement sensor 11 (third measurement sensor), the measurement data Each component in the XYZ axis direction is weighted corresponding to the repetition accuracy for each XYZ axis direction. In this case, the repeat accuracy information 46A in the storage unit 42 stores the repeat accuracy for each XYZ-axis direction of the measurement sensor 11 (third measurement sensor).

  For example, since “probe A” in the drawing has different repeatability in the XY axis and repeatability in the Z axis, the repeatability (σA1) in the XY axis and the repeatability (σA2) in the Z axis are different. Each is stored in the repetition accuracy information 46A. Therefore, when weighting the measurement data measured by the “probe A”, the shape calculation unit 43 weights the XY-axis direction components (X coordinate, Y coordinate) of the measurement data based on the repetition accuracy σA1. And weighting is performed on the Z-axis direction component (Z coordinate) of the measurement data based on the repetition accuracy σA2. In addition, when the repetition accuracy of each direction of the “probe A” in the XYZ-axis directions is different from each other, weighting is performed on each component of the measurement data in the XYZ-axis directions based on different repetition accuracy.

  In addition, since the “microscope B” in the drawing is the measurement sensor 11 that can measure only in the XY axis direction, only the repeat accuracy (σB1) in the XY axis direction is stored in the repeat accuracy information 46A, and the repeat accuracy in the Z axis direction. Is not stored in the repeat accuracy information 46A. Therefore, when weighting the measurement data measured by the “microscope B”, the shape calculation unit 43 weights the XY-axis direction component (X coordinate, Y coordinate) of the measurement data based on the repeatability σB1. And the weight of the Z-axis direction component is set to zero.

  Thus, when weighting based on repetition accuracy is performed on the measurement data obtained by the measurement sensor 11 (third measurement sensor), each component in the XYZ axis direction of this measurement data for each XYZ axis direction. By performing weighting corresponding to the repetition accuracy, the measurement accuracy of the shape of the measurement object W can be further improved.

  FIG. 18 is an explanatory diagram for explaining an example of the non-contact measurement sensor 11 other than the line sensor 30. In the above-described embodiment, the line sensor 30 (laser probe, laser displacement meter) has been described as an example of the non-contact type measurement sensor 11. However, for example, an image probe 56 is used instead of the line sensor 30 as shown in FIG. The present invention can also be applied when used. In this case, the control unit 26 is provided with an image processing unit that analyzes a captured image of the measurement target W obtained by the image probe 56 and measures various shapes of the measurement target W. Since the shape measurement of the measuring object W using the image probe 56 is a known technique, a detailed description is omitted.

  The non-contact type measurement sensor 11 is not limited to the line sensor 30 and the image probe 56 described above, and various known non-contact type measurement sensors 11 can be used. Further, the contact-type measurement sensor 11 is not limited to the probe 29, and various known contact-type measurement sensors 11 can be used.

  In the above embodiment, the shape calculation unit 43 weights the measurement data based on the repetition accuracy information 46 and 46A stored in the storage unit 42 in the control unit 26. However, the repetition accuracy information 46 and 46A is externally provided. You may memorize | store in the memory | storage part. That is, the shape calculation unit 43 accesses an external storage unit (database or the like) via various communication networks such as the Internet, for example, and based on the repetition accuracy information 46 and 46A stored in the storage unit, the measurement data Weighting may be performed.

  In the above embodiment, the replacement sensor 27 of the measurement head 24 is automatically replaced using the replacement magazine 27, but the automatic replacement method of the measurement sensor 11 is not particularly limited. Further, instead of automatically replacing the measurement sensor 11, for example, an operator may directly replace the measurement sensor 11.

  Instead of exchanging the measurement sensor 11 of the measurement head 24, measurement of the measurement object W for each measurement sensor 11 is sequentially or simultaneously performed using a measurement head that can detachably hold a plurality of types of measurement sensors 11 simultaneously. You may go.

  In the above embodiment, the measurement object W is measured using two types of measurement sensors 11 including the probe 29 and the line sensor 30, but the measurement object W is measured using three or more types of measurement sensors 11. May be performed. Further, instead of performing the measurement using the contact-type measurement sensor 11 (probe 29 or the like) and the non-contact-type measurement sensor 11 (line sensor 30), the measurement object W is obtained using only the same type of measurement sensor 11. May be measured. That is, when the measurement object W is measured using only a plurality of types of contact-type measurement sensors 11 having different repeatability, or measured using only a plurality of types of non-contact-type measurement sensors 11 having different repeatability. The present invention can also be applied when the object W is measured.

  In the above embodiment, the measurement data of the probe 29 and the line sensor 30 are weighted by the weighting coefficient obtained by squaring the reciprocals of the repetitive accuracy σ1 and σ2 of the corresponding probe 29 and line sensor 30, respectively. The weighting factors may be changed as appropriate as long as the weighting factors correspond to σ1 and σ2, respectively. In the above embodiment, the shape of the measurement object W is calculated by performing fitting by the least square method based on each weighted measurement data. However, a shape calculation method other than the least square method may be used.

  In the above embodiment, the three-dimensional measuring device 10 has been described as an example of the shape measuring device of the present invention. However, in various shape measuring devices that measure the shape of the measuring object W other than the three-dimensional measuring device 10, the repeatability is high. The present invention can be applied when measurement is performed using a plurality of different types of measurement sensors 11.

DESCRIPTION OF SYMBOLS 10 ... Three-dimensional measuring apparatus, 11 ... Measurement sensor, 24 ... Measuring head, 26 ... Control part, 29 ... Probe, 30 ... Line sensor, 41 ... Measurement data acquisition part, 42 ... Memory | storage part, 43 ... Shape calculating part, 46 46A ... Repeatability information 56 ... Image probe

Claims (7)

A measurement data acquisition step for acquiring a plurality of types of measurement data obtained by measuring the shape of the same measurement object with a plurality of types of measurement sensors having different repeatability,
The plurality of types of measurement data acquired in the measurement data acquisition step are weighted corresponding to the repetition accuracy of the corresponding measurement sensors, and the shape is determined based on the weighted types of measurement data. A shape calculation step to be calculated;
A shape measuring method comprising:   The shape measurement method according to claim 1, wherein in the shape calculation step, a plurality of types of measurement data are weighted with a weighting coefficient obtained by squaring the reciprocal of the repeatability of the corresponding measurement sensor. The plurality of types of measurement sensors include a contact-type first measurement sensor and a non-contact-type second measurement sensor having a lower repeatability than the first measurement sensor,
The measurement data acquisition step is obtained by measuring the shape with the first measurement sensor and the shape with the second measurement sensor, as the plurality of types of measurement data, and the first measurement data obtained by measuring the shape with the first measurement sensor. The shape measurement method according to claim 1, wherein second measurement data having a larger number of measurements than the first measurement data is acquired.   When the plurality of types of measurement sensors include a third measurement sensor having different repeatability in a plurality of axial directions, the shape calculation step includes the plurality of the measurement data obtained by the third measurement sensor. The shape measurement method according to claim 1, wherein weighting corresponding to the repetition accuracy for each of the plurality of axial directions is performed on each component in the axial direction.   The said shape calculation step refers to the memory | storage part which memorize | stored the said repetition precision for every kind of said measurement sensor, The said weighting is performed with respect to several types of said measurement data in any one of Claim 1 to 4 The shape measuring method described.   6. The shape measuring method according to claim 1, wherein the shape calculating step calculates the shape using a least square method based on the weighted plural types of measurement data. A measurement data acquisition unit for acquiring a plurality of types of measurement data obtained by measuring the shape of the same measurement object with a plurality of types of measurement sensors having different repeatability;
The plurality of types of measurement data acquired by the measurement data acquisition unit are weighted corresponding to the repetition accuracy of the corresponding measurement sensors, and the shape is determined based on the weighted types of measurement data. A shape calculation unit to calculate,
A shape measuring apparatus comprising:

Images