JP6363436B2 - Shape measuring apparatus and shape measuring method - Google Patents

Description

  The present invention relates to a shape measuring apparatus and a shape measuring method for measuring the surface shape of an object to be measured.

Conventionally, a probe having a probe for measuring an object to be measured, a moving mechanism for moving the probe, and a control device for controlling the moving mechanism are provided, and the object to be measured is moved by moving the probe along the surface of the object to be measured. A shape measuring device for measuring the shape of a measurement object is known (see, for example, Patent Document 1).
The shape measuring device described in Patent Document 1 generates a PCC (Parametric Cubic Curves) curve group from design values (NURBS (Non-Uniform Rational B-Spline) data) based on CAD data and the like. Then, the design value copying is performed to measure the surface shape of the object to be measured based on the PCC curve group. Here, the shape measuring apparatus performs normal design value scanning control (normal control) based on the PCC curve group, and even when the probe position deviates from the path based on the PCC curve group by a predetermined amount, Is within the allowable range, active control is performed to correct the error. Specifically, in Patent Document 1, a path velocity vector, an indentation correction vector, and a trajectory correction vector are calculated, and a speed vector is calculated for each vector using a scanning drive gain, an indentation direction correction gain, and a trajectory correction gain. It is corrected.

JP 2013-238573 A

Incidentally, as described above, in the shape measuring apparatus, when the active control of the design value scanning is performed, it is necessary to perform the normal control and to control the pushing amount of the probe to a constant value.
In the above Patent Document 1, the velocity vector is corrected by using a correction gain for each vector. However, depending on the direction of the vector, the control may become unstable or a measurement error may occur. There is a problem that there is sex.

  An object of the present invention is to provide a shape measuring device and a shape measuring method capable of measuring a shape with high accuracy.

  The shape measuring device of the present invention detects a probe having a probe at the tip, a moving mechanism for moving the probe along the surface of the object to be measured, and contact between the probe and the surface of the object to be measured. A shape measuring apparatus for measuring the shape of the object to be measured, wherein the command output unit outputs a measurement command for instructing a movement path of the probe based on design data of the object to be measured; and based on the measurement command A path component calculation unit that calculates a path velocity vector that is a velocity component vector of the probe along the movement path, and an amount by which the probe is pushed into the object to be measured. A pushing direction component calculating unit that calculates a pushing correction vector that is a velocity component vector for correcting the pushing amount; and the probe calculated based on the current position of the probe and the moving path. A trajectory correction component calculation unit that calculates a trajectory correction vector, which is a velocity component vector for returning the position of the probe onto the movement path, from a trajectory error amount and a trajectory deviation direction between the position of the probe and the movement path; A speed synthesis unit that calculates a speed synthesis vector obtained by synthesizing the path speed vector, the indentation correction vector, and the trajectory correction vector; and a drive control unit that moves the probe based on the speed synthesis vector, The command output unit outputs the measurement command including a trajectory correction term coefficient set with respect to the angle formed by the indentation correction vector and the trajectory correction vector, and the speed synthesis unit is corrected by the trajectory correction term coefficient. The trajectory correction vector, the path velocity vector, and the indentation correction vector are synthesized.

  In the present invention, the trajectory correction term coefficient K set with respect to the angle θ (0 ° to 180 °) formed by the indentation correction vector and the trajectory correction vector is acquired as a measurement command, and the speed synthesis means is obtained by the path component calculation unit. The route velocity vector along the calculated route, the indentation correction vector calculated by the indentation direction component calculation unit, and the vector obtained by correcting the trajectory correction vector calculated by the trajectory correction component calculation unit with the trajectory correction term coefficient are combined. The speed synthesis vector is calculated, and the drive control means drives the probe according to the speed synthesis vector.

When combining the path speed vector, the indentation correction vector, and the trajectory correction vector by the speed compositing means, if the angle formed by the indentation correction vector and the trajectory correction vector is near 180 ° (opposite direction), the indentation correction function In addition, it may be difficult to achieve compatibility with the function of correcting the trajectory, and it may be difficult to control the scanning measurement and vibration may occur. When such vibration occurs, the position of the probe probe changes and the measurement accuracy decreases.
In contrast, in the present invention, as described above, the trajectory correction vector is corrected by the trajectory correction term coefficient to reduce the size of the trajectory correction vector. Thereby, the influence of the trajectory correction vector can be reduced and the occurrence of vibration can be suppressed. Therefore, highly accurate shape measurement with suppressed vibration generation can be performed.

In the shape measuring apparatus of the present invention, the command output unit outputs the measurement command including angle coefficient correspondence data in which the trajectory correction term coefficient is set for each of a plurality of angle ranges, and the speed synthesis unit includes: It is preferable that the trajectory correction vector is corrected from the angle coefficient correspondence data using the trajectory correction term coefficient for the angle range to which the angle formed by the indentation correction vector and the trajectory correction vector belongs.
In the present invention, the trajectory correction vector is corrected using the trajectory correction term coefficient for the angle formed by the indentation correction vector and the trajectory correction vector based on the angle coefficient correspondence data. Thereby, for example, the process can be simplified and the measurement time can be shortened as compared with the case of calculating the trajectory correction term coefficient based on the angle formed by the indentation correction vector and the trajectory correction vector.

In the shape measuring apparatus of the present invention, a coefficient data storage unit that stores a plurality of pieces of angle coefficient correspondence data having different trajectory correction term coefficients for the angle range, and a maximum change amount of the trajectory error amount is less than a predetermined allowable value An accuracy determining unit that determines whether or not the command output unit is determined when the accuracy determining unit determines that the maximum change amount of the trajectory error amount is equal to or greater than the allowable value, It is preferable to change the angle coefficient correspondence data included in the measurement command.
In the present invention, when it is determined by the accuracy determination means that the maximum change amount of the trajectory error amount is equal to or greater than the allowable value, that is, when it is determined that the trajectory error amount due to vibration is large and the measurement accuracy is low, The angle coefficient correspondence data for correcting the trajectory correction vector can be switched. Thereby, the optimal trajectory correction term coefficient according to the measurement conditions can be selected, and a decrease in measurement accuracy can be suppressed.

In the shape measuring apparatus of the present invention, a combination storage unit that stores a plurality of combination data in which the combination of the angle ranges is recorded, and determines whether or not the maximum change amount of the trajectory error amount is less than a predetermined tolerance An accuracy determination unit, wherein the command output unit outputs the measurement command including the combination data, and the accuracy determination unit determines that the maximum change amount of the trajectory error amount is equal to or greater than the allowable value. In this case, it is preferable to change the combination data included in the measurement command.
In the present invention, for example, combination data in which the angle range is a combination of 0 ° ≦ α1 <90 °, 90 ° ≦ α2 <120 °, 120 ° ≦ α3 <180 °, the angle range is 0 ° ≦ α1 <60 °, A plurality of combination data such as combination data that is a combination of 60 ° ≦ α2 <90 ° and 90 ° ≦ α3 <180 ° is stored in the combination storage unit. When the accuracy determination unit determines that the measurement accuracy is low, the velocity synthesis unit changes the angle range to which the angle formed by the indentation correction vector and the trajectory correction vector belongs by changing the combination data to be used. Thereby, similarly to the said invention, the optimal track correction term coefficient according to measurement conditions can be selected, and the fall of a measurement precision can be suppressed.

  In the shape measuring apparatus of the present invention, the command output unit outputs the measurement command including a curvature of the measurement target section of the object to be measured, and the shape measuring apparatus corresponds to the measurement target section corresponding to the position of the probe. When the curvature of is equal to or greater than a threshold value, a curve equation is calculated from the positions of the probe at three or more points, the tangential direction of the surface of the object to be measured is calculated, and the curvature is less than the threshold value, It is preferable to provide a normal direction calculation unit that calculates a direction perpendicular to a straight line connecting the positions of the two probes as a tangential direction of the surface of the object to be measured.

  In the active control of design value copying, as described above, it is necessary to control the push-in amount of the probe to a constant value. At this time, an indentation correction vector is calculated in the wrong direction due to friction between the object to be measured and the probe probe, which may cause a measurement error. On the other hand, Japanese Patent Laid-Open No. 2013-238573 discloses a method for calculating an indentation correction vector in consideration of friction between an object to be measured and a measuring element. The direction perpendicular to the straight line connecting the center position of the previous probe sampled before is regarded as the normal direction of the object to be measured. This method is effective when the radius of curvature is large (the curvature is small) and the surface of the object to be measured is flat (the probe movement trajectory is a straight line or a substantially straight line), but the shape of the object to be measured (the curvature of the surface) ), The normal direction may contain an error.

On the other hand, in the present invention, when the curvature is less than the threshold and the curvature radius is large according to the curvature of the object to be measured, the normal direction using the above method is calculated, and the curvature is equal to or greater than the threshold. Yes, when the radius of curvature is small, a curve equation is calculated based on three or more probe positions (measured values), and a normal direction at the probe position corresponding to the measurement point is calculated. For example, if the center position (measurement point) of the target stylus and the previous measurement point sampled before the target measurement point are buffered and the next measurement point is measured after the target measurement point, Based on these three points, a quadratic curve is calculated, and the perpendicular direction of the tangent line at the target measurement point in the quadratic curve is calculated as the normal direction.
As a result, even when there is friction between the object to be measured and the probe, the normal direction to the measurement point can be calculated with higher accuracy, and highly accurate coordinate calculation that suppresses the influence of measurement errors is performed. Measurement accuracy can be improved.

The shape measuring method according to the present invention includes a probe having a probe at the tip, a moving mechanism for moving the probe along the surface of the object to be measured, and detecting contact between the probe and the surface of the object to be measured. A shape measuring method of a shape measuring apparatus for measuring the shape of the object to be measured, the command output step for outputting a measurement command for instructing a movement path of the probe based on design data of the object to be measured; Based on a measurement command, a path component calculating step for calculating a path speed vector that is a speed component vector of the probe along the movement path, and detecting a pressing amount of the probe into the object to be measured, and the pressing amount A pressing direction component calculating step for calculating a pressing correction vector, which is a velocity component vector for correcting the predetermined reference pressing amount, a current position of the probe and the movement A trajectory correction vector, which is a velocity component vector for returning the probe position onto the moving path, is calculated from the trajectory error amount and the trajectory deviation direction between the probe position and the moving path calculated based on the path. A trajectory correcting component calculating step, a speed synthesizing step for calculating a speed synthesized vector obtained by synthesizing the path velocity vector, the indentation correcting vector, and the trajectory correcting vector, and a drive for moving the probe based on the velocity synthesized vector. Control step, and in the command output step, output the measurement command including a trajectory correction term coefficient set with respect to the angle formed by the indentation correction vector and the trajectory correction vector, and in the velocity synthesis step The trajectory correction vector is corrected by the trajectory correction term coefficient and corrected. Serial trajectory correction vector, the path velocity vector, and characterized by combining said push correction vector.
In the present invention, similarly to the above-described invention, the trajectory correction vector is corrected by the trajectory correction term coefficient to reduce the size of the trajectory correction vector. Thereby, the influence of the trajectory correction vector can be reduced and the occurrence of vibration can be suppressed. Therefore, highly accurate shape measurement with suppressed vibration generation can be performed.

The whole schematic diagram which shows the three-dimensional measuring machine which is the shape measuring apparatus of one Embodiment which concerns on this invention. The block diagram which shows schematic structure of the coordinate measuring machine of this embodiment. The figure which shows the track | orbit of a measuring element, and each velocity component vector which concerns on a measuring element. The flowchart which shows the method of calculating the velocity vector of the probe of this embodiment. The figure which shows an example of a PCC curve group. The figure which shows the track | orbit of a measuring element, and each velocity component vector which concerns on a measuring element. The flowchart which shows the calculation method of the normal line direction in the shape measuring method of 2nd embodiment. The figure for demonstrating the setting method of the normal line direction using 2 points | pieces. The model figure when a frictional force acts when moving a measuring element to a scanning direction in case a curvature is less than a threshold value. The figure for demonstrating the setting method of the normal direction using 3 points | pieces. The model figure when a frictional force acts when moving a measuring element to a scanning direction in case a curvature is more than a threshold value. The figure which shows the model of the scanning measurement in case friction does not generate | occur | produce. The figure which shows the model of the scanning measurement when friction generate | occur | produces.

[First embodiment]
Hereinafter, a first embodiment according to the present invention will be described with reference to the drawings.
[Schematic configuration of CMM]
FIG. 1 is an overall schematic diagram showing a coordinate measuring machine 1 which is a shape measuring apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of the coordinate measuring machine 1.
In FIG. 1, the upper direction is defined as the + Z-axis direction, and two axes orthogonal to the Z-axis are described as the X-axis and the Y-axis, respectively. The machine coordinate system is defined by the X-axis direction, the Y-axis direction, and the Z-axis direction. The same applies to the following drawings.
As shown in FIG. 1, the coordinate measuring machine 1 instructs the motion controller 3 through a coordinate measuring machine body 2, a motion controller 3 that performs drive control of the coordinate measuring machine body 2, and an operation lever. And a host computer 5 for manually operating the coordinate measuring machine main body 2 and for giving a predetermined command to the motion controller 3 and executing arithmetic processing.

[Configuration of CMM body]
As shown in FIG. 1, the coordinate measuring machine main body 2 includes a probe 21 having a spherical probe 211 </ b> A for measuring an object to be measured, a moving mechanism 22 that holds the probe 21 and moves the probe 21. And a surface plate 23 on which the moving mechanism 22 is erected.
As shown in FIG. 1, the probe 21 includes a stylus 211 having a probe 211A on the distal end side (−Z axis direction side) and a support mechanism 212 that supports the proximal end side (+ Z axis direction side) of the stylus 211. Prepare.

The support mechanism 212 supports the stylus 211 so as to be positioned at a predetermined position by urging the stylus 211 in the X, Y, and Z axis directions. The support mechanism 212 can move the stylus 211 in the X, Y, and Z axis directions within a certain range when an external force is applied, that is, when the probe 211A contacts the object to be measured. It is said.
Although not specifically shown, the support mechanism 212 includes a probe sensor for detecting the position of the stylus 211 in each axial direction.
Each probe sensor is a position sensor that outputs a pulse signal corresponding to the amount of movement of the stylus 211 in each axial direction.

As shown in FIG. 1 or FIG. 2, the moving mechanism 22 holds the probe 21 and allows the probe 21 to move by driving the slide mechanism 24 and the slide mechanism 24. And a mechanism 25.
As shown in FIG. 1, the slide mechanism 24 includes two columns 241 that extend in the + Z-axis direction from both ends of the surface plate 23 in the X-axis direction and are slidable along the Y-axis direction, and each column 241. And a slider that is formed in a cylindrical shape that extends along the Z-axis direction and is slidable along the X-axis direction. 243, and a ram 244 that is inserted into the slider 243 and is slidable along the Z-axis direction inside the slider 243.

  As shown in FIG. 1 or 2, the drive mechanism 25 supports a column 241 on the + X-axis direction side among the columns 241, and slides along the Y-axis direction, and a beam 251Y. X-axis drive unit 251X (FIG. 2) that slides 242 and moves slider 243 along the X-axis direction, and Z-axis drive that slides inside slider 243 and moves ram 244 along the Z-axis direction Part 251Z (FIG. 2).

Although not specifically shown in the X-axis drive unit 251X, the Y-axis drive unit 251Y, and the Z-axis drive unit 251Z, in order to detect the position of the slider 243, each column 241, and the ram 244 in each axial direction. Each of the scale sensors is provided.
Each scale sensor is a position sensor that outputs a pulse signal corresponding to the amount of movement of the slider 243, each column 241, and the ram 244.

[Configuration of motion controller]
As shown in FIG. 2, the motion controller 3 includes a command acquisition unit 31, a counter unit 32, an arithmetic processing unit 33, a probe command unit 34, a drive control unit 35, and a storage unit 36. The storage unit 36 has a storage area for storing measurement data obtained by the scanning measurement process, trajectory errors (described later), and the like. The storage unit 36 also functions as a buffer that temporarily stores the center point of the measuring element.

The command acquisition unit 31 acquires a measurement command including PCC data, angle coefficient correspondence data, and combination data for driving the probe 21 from the host computer 5. The angle coefficient correspondence data and the combination data will be described later.
The counter unit 32 counts the pulse signals output from the scale sensors described above to measure the movement amount of the slide mechanism 24, and counts the pulse signals output from the probe sensors described above to move the stylus 211. Measure the amount.
The arithmetic processing unit 33 calculates the position of the probe 211A (hereinafter referred to as probe position) based on the movement amounts of the slide mechanism 24 and the stylus 211 measured by the counter unit 32. Then, the arithmetic processing unit 33 stores the calculated probe position in the storage unit 36.
Further, the arithmetic processing unit 33 is based on the movement amount of the stylus 211 (detected values (Px, Py, Pz) of each probe sensor) measured by the counter unit 32 as shown in the following formula (1). Then, the pressing amount of the measuring element 211A (absolute value of the vector Ep) is calculated.

The probe command unit 34 has pushed the probe 211A into the workpiece W based on the probe position and the push amount calculated by the arithmetic processing unit 33 and the measurement command acquired by the command acquisition unit 31. Thus, a probe command value (velocity synthesis vector) for moving the probe 211A along the surface of the workpiece W is calculated.
Specifically, the probe command unit 34 includes a path component calculation unit 341, a pushing direction component calculation unit 342, a trajectory correction component calculation unit 343, and a speed synthesis unit 344.

The path component calculation unit 341 calculates a speed component vector (path speed vector) along the path of the probe 21 based on the PCC data.
The pushing direction component calculation unit 342 generates a velocity component vector (push correction vector) in the pushing direction for returning the pushing amount to a preset reference pushing amount based on the pushing amount calculated by the arithmetic processing unit 33. calculate.

The trajectory correction component calculation unit 343 calculates a velocity component vector (trajectory correction vector) for returning the measure 211A to the path based on the current position of the measure 211A and the path of the path information.
The speed synthesis unit 344 detects the angle formed by the indentation correction vector and the trajectory correction vector, and selects the trajectory correction term coefficient based on the angle coefficient data and the angle range combination data included in the measurement command. Then, the route speed vector, the push correction vector, and the trajectory correction vector corrected by the trajectory correction term coefficient are combined to calculate a speed composite vector, which is output to the drive control unit 35.
Detailed processing by the probe command unit 34 will be described later.
The drive control unit 35 moves the probe 21 by controlling the drive mechanism 25 based on the probe command value calculated by the probe command unit 34.

[Configuration of host computer]
The host computer 5 includes a CPU (Central Processing Unit), a memory, and the like, and controls the coordinate measuring machine main body 2 by giving a predetermined command to the motion controller 3. The host computer 5 includes input means 61 and output means 62. The input means 61 is for inputting measurement conditions and the like in the coordinate measuring machine 1 to the host computer 5, and the output means 62 is for outputting a measurement result by the coordinate measuring machine 1.
As shown in FIG. 2, the host computer 5 includes a storage unit 51, and various data and various programs for controlling the coordinate measuring machine 1 are stored in the storage unit 51.
The storage unit 51 includes a coefficient database (coefficient DB) and a combination database (combination DB). The coefficient DB stores a plurality of angle coefficient correspondence data, and the combination database stores a plurality of combination data. That is, the storage unit 51 constitutes a coefficient data storage unit and a combination storage unit of the present invention.
In the coefficient DB, angle coefficient correspondence data indicating the trajectory correction term coefficient with respect to the angle θ formed by the indentation correction vector and the trajectory correction vector is recorded. Further, combination data indicating a combination of angle ranges of the angle θ formed by the indentation correction vector and the trajectory correction vector is recorded in the combination DB.

Here, the angle θ and the angle range formed by the indentation correction vector and the trajectory correction vector will be described.
FIG. 3 is a diagram for explaining the angle θ formed by the indentation correction vector and the trajectory correction vector.
As shown in FIG. 3, when the starting point of the indentation correction vector (Ve) is the origin and the vector direction is 0 °, the direction that the trajectory correction vector (Vc) can take can be all directions around the origin.
Here, in this embodiment, as shown in FIG. 3, the direction of the trajectory correction vector (Vc) when the indentation correction vector (Ve) is taken as the X axis is divided for each angle. Specifically, the angle θ is divided into an angle range where 0 ≦ θ <α1, an angle range where α1 ≦ θ <α1 + α2, and an angle range where α1 + α2 ≦ θ ≦ α1 + α2 + α3 (= 180 °). In FIG. 3, an example of the angular range segmentation is shown in a plane, but in reality, it is a three-dimensional range with the indentation correction vector (Ve) as the axis, and 0 ≦ θ <α1, α1 + α2 ≦ The angle range of θ ≦ α1 + α2 + α3 is a conical region with the direction of the indentation correction vector (Ve) as an axis, and the angle range of α1 ≦ θ <α1 + α2 is a region other than the two conical regions.
In this embodiment, an example in which an angle range is set by dividing an angle from 0 ° to 180 ° into three by α1, α2, and α3, but two angles from 0 ° to 180 °, or An angle range αk divided into four or more may be set.

Table 1 below shows an example of the coefficient DB.
As shown in Table 1, the coefficient DB records a plurality (for example, two in this embodiment) of angle coefficient correspondence data. In each angle coefficient correspondence data, the trajectory correction term coefficient Ki for each angle range described above is recorded. In the present embodiment, the trajectory correction term coefficient K1 in Table 1 is the default value, and the trajectory error becomes large in the scanning measurement, and the trajectory correction term coefficient K2 is switched to when a separation error or a push-in error occurs.

Table 2 below shows an example of the combination DB.
As shown in Table 2, the combination DB records a plurality of (for example, two in this embodiment) combination data. In each combination data, a combination βj of the segment angles αk in each angle range described above is recorded. That is, in the present embodiment, the angles of segment angles α1, α2, and α3 are recorded for each combination βj. In the present embodiment, the combination β1 in Table 2 is the default value, and the trajectory error increases due to the vibrational behavior, and when the separation error or the push-in error occurs, the combination β2 is switched.

In addition, the CPU of the host computer 5 reads and executes the program stored in the storage unit 51, so that the information acquisition unit 52, the route setting unit 53, the command output unit 54, the accuracy determination unit 55, and the shape analysis unit 56 are used. Function.
The information acquisition unit 52 acquires design information (CAD data, NURBS data, etc.) of the workpiece W from a CAD system (not shown).
The route setting unit 53 sets a movement route (PCC data) for moving the probe 21 based on the design information acquired by the information acquisition unit 52.
The command output unit 54 outputs to the motion controller 3 a measurement command including the set PCC data, the angle coefficient corresponding data in which the trajectory correction term coefficient Ki is recorded, and the angle range combination βj.

The accuracy determination unit 55 determines whether or not the measurement accuracy is sufficient based on the trajectory error calculated during the scanning measurement. Specifically, a change amount of the maximum trajectory error is acquired, and it is determined whether or not the change amount is less than an allowable value.
The shape analysis unit 56 calculates the surface shape data of the object to be measured based on the measurement data output from the motion controller 3, and performs shape analysis to obtain errors, distortions, and the like of the calculated surface shape data of the object to be measured.

[Operation of CMM]
Next, the operation of the coordinate measuring machine 1 as described above will be described.
FIG. 4 is a flowchart showing the shape measuring method in the present embodiment.
In this embodiment, when measuring the surface shape of the workpiece W, the information acquisition unit 52 of the host computer 5 acquires design data (NURBS) from the CAD system (step S1).

Thereafter, the path setting unit 53 calculates PCC data based on the acquired design data (step S2).
FIG. 5 is measured when the PCC curve (probe movement path), the interpolation point, the surface of the object to be measured, and the surface of the object to be measured, which are set for the design data in this embodiment, are copied. It is a figure which shows an example of an actual CMM orbit. The actual CMM trajectory indicates the trajectory of the probe position PP calculated by the arithmetic processing unit 33.
Specifically, as shown in FIG. 5, the path setting unit 53 uses the value obtained by subtracting the reference push amount E ₀ from the radius R of the measuring element 211A as an offset amount, and from the design data in the normal direction by the offset amount. The moved curve is set as the PCC curve. A plurality of interpolation points are set on the calculated PCC curve. A straight line connecting these interpolation points becomes a movement path when the probe is moved.
Further, in the active control scanning measurement, the path setting unit 53 sets a predetermined allowable range (in this embodiment, a cylinder having a radius r = 1.5 mm as shown in FIG. 5) for the PCC curve. . If the probe position is within the allowable range, an error outside the allowable range of trajectory error does not occur.

Next, the command output unit 54 initializes variables i and j (i = 1, j = 1) for setting the trajectory correction term coefficient Ki and the combination β (step S3).
Then, the command output unit 54 measures, from the coefficient DB of the storage unit 51, the angle coefficient corresponding data for recording the trajectory correction term coefficient Ki corresponding to the variables i and j, and the combination βj corresponding to the variable j from the combination DB to the measurement command value. Get as data included in. That is, DATA (K) = Ki and DATA (β) = βj are set (step S4).
Then, the command output unit 54 outputs a measurement command including the PCC data calculated in step S2, the angle coefficient corresponding data DATA (K), and the combination DATA (β) to the motion controller 3 (step S5).

  In the motion controller 3, when the command acquisition unit 31 acquires a measurement command from the host computer 5, the path component calculation unit 341, based on the acquired PCC data and the curvature of each divided PCC curve divided by the interpolation points, A route speed vector Vf is calculated (step S6). Here, when the PCC curve group is divided into M divided PCC curves, the path component calculation unit 341 generates a path velocity vector Vf for each divided PCC curve (l) (l = 1 to M). To do.

Thereafter, the scanning control is performed by the drive control unit 35 (step S7). In step S <b> 7, the arithmetic processing unit 33 takes in the movement amounts of the slide mechanism 24 and the stylus 211 measured by the counter unit 32 at a constant sampling interval, for example. Then, the arithmetic processing unit 33 calculates the probe position based on the taken movement amounts of the slide mechanism 24 and the stylus 211, and calculates the pushing amount of the measuring element 211A based on the above-described equation (1). Further, a change amount dL of the trajectory error L, which is a distance between the probe position PP and a straight line (interpolation straight line (i)) between adjacent interpolation points (i) and (i + 1) in the PCC curve, is calculated. A change amount differential value d ² L is calculated to determine whether or not the error L changes in vibration (step S8).
Specifically, the arithmetic processing unit 33 calculates dL _n = L _n −L _n−1 using the previously sampled trajectory error as L _n−1 and the current sampled trajectory error as L _n , and d ² L _n. = calculates the _{dL n -dL n-1.}

After step S8, the probe command unit 34 determines whether or not the calculated probe position PP is the end point of the PCC curve (step S9).
When it is determined as “No” in step S9, the driving speed of the probe 21 is calculated, and the probe 21 is driven at the calculated driving speed.
FIG. 6 is a diagram showing the trajectory of the probe 211A and the velocity component vectors related to the probe 211A.
First, push direction component computing unit 342 calculates the push correction vector for correcting the reference pressing amount E ₀ pre set amount of deflection of the workpiece W of the probe 21 (step S10).
Specifically, the indentation direction component calculation unit 342 calculates an indentation correction vector Ve based on the following formula (2).

In Expression (2), A is a constant, E ₀ is a reference indentation amount, and a preset value can be used. The absolute value of the vector Ep is the indentation of the probe 21 that is calculated in step S8, the vector e _u, is a unit vector in the push-in direction. In the present embodiment, as a vector e _u, calculates the unit vector in the displacement direction (vibration direction) of the probe 21.

Next, the trajectory correction component calculation unit 343 calculates the trajectory correction vector Vc when the probe position PP deviates from the path based on the probe position PP and the movement path (PCC curve) set in step S2. (Step S11).
Specifically, the trajectory correction component calculation unit 343 calculates the trajectory correction vector Vc with the absolute value of the trajectory error L as the vector size and the direction from the probe position PP toward the point P as the trajectory correction direction.

Next, the speed synthesizing unit 344 calculates an angle θ between the push correction vector Ve and the trajectory correction vector Vc (step S12). The angle θ can be calculated as cos θ = (Ve, Vc) / | Ve || Vc | by calculating a vector inner product (Ve, Vc).
Thereafter, the speed synthesizer 344 specifies the angle range to which the angle θ calculated in step S12 belongs from the combination DATA (β) included in the measurement command, and the angle coefficient corresponding data DATA (K) included in the measurement command. Then, the trajectory correction term coefficient Ki corresponding to the specified angle range is acquired (step S13).
Then, the speed synthesizer 344 corrects the trajectory correction vector Vc calculated in step S11 by multiplying the trajectory correction term coefficient Ki, and corrects the corrected trajectory correction vector Vc, the path speed vector Vf, and the indentation. The speed vector V is calculated by synthesizing the correction vector Ve and the trajectory correction vector Vc (step S14).
As the path velocity vector Vf, a velocity vector corresponding to the divided PCC curve corresponding to the probe position PP detected in step S8 is used. When the probe position PP is out of the path, a path velocity vector on the divided PCC curve to which the point P that is a leg of a perpendicular line descending from the probe position PP belongs may be acquired.
Specifically, in step S14, the speed synthesis unit 344 calculates a speed synthesis vector V based on the following equation (3).

In the above equation (3), Gf is a scanning drive gain (path speed gain), Ge is a pushing direction correction gain, and Gc is a trajectory correction gain.
Here, assuming that the difference value between the push amount calculated in step S8 (the absolute value of the vector Ep) and a preset reference push amount (E ₀ ) is E, and the trajectory error is L, the scanning drive gain Gf is The function f ₁ (L, E) is applied. This function f ₁ (L, E) is obtained when the difference value E is less than or equal to the first threshold when the difference value E is greater than the predetermined first threshold and the trajectory error L is greater than the predetermined second threshold. , And a function that returns a smaller value than when satisfying at least one of the cases where the trajectory error L is equal to or less than the second threshold value.
Further, the function f ₂ (E) is applied to the pushing direction correction gain Ge. This function f ₂ (E) is a function that returns a smaller value when the difference value E is less than or equal to the first threshold value, compared to when the difference value E is greater than the first threshold value.
Further, the function f ₃ (L) is applied to the trajectory correction gain Gc. This function f ₃ (L) is a function that returns a smaller value when the trajectory error L is less than or equal to the second threshold value compared to when the trajectory error L is greater than the second threshold value.

  Then, the speed synthesis unit 344 inputs the calculated speed synthesis vector V to the drive control unit 35 as a probe command value. Thereby, the probe 21 is driven based on the velocity synthesis vector V (step S15). Thereafter, the process returns to step S8, the probe position PP and the push-in amount are calculated at the sampling interval, and the processes from step S8 to step S15 are repeated until the probe position PP reaches the end point.

On the other hand, when the probe position PP reaches the end point, “Yes” is determined in the process of step S9 described above. In this case, the host computer 5 receives from the motion controller 3 measurement data (measured value of each probe position PP and maximum value d ² Lmax of variation differential value d ² L _n of trajectory error L (maximum variation differential value)). Is acquired (step S16).

Then, the accuracy determining unit 55 determines whether or not the acquired change amount differential maximum value d ² Lmax is less than a predetermined allowable value d ² La (step S17). That is, when the change amount differential maximum value d ² Lmax is equal to or greater than the predetermined allowable value d ² La, the maximum value of the change amount of the trajectory error L is large, and the measurement data changes in a vibrational manner. It is determined that the accuracy is low. The allowable value d ² La is a value set in advance based on a trajectory error determined from the combination of the coordinate measuring machine 1 and the probe 21.
If it is determined as “Yes” in step S <b> 17, the shape analysis process of the workpiece W based on the measurement data obtained by the shape analysis unit 56 is performed, and the measurement process is ended.
On the other hand, if “No” is determined in step S17, the command output unit 54 adds 1 to the variable i (step S18), and the variable i is the maximum value imax (in the example of Table 1 above, imax = It is determined whether or not 2) has been exceeded (step S19). If it is determined “No” in step S19, the process returns to step S4. That is, the command output unit 54 sets angle coefficient correspondence data corresponding to the next trajectory correction term coefficient Ki as DATA (K), and outputs it to the motion controller 3. As a result, the trajectory correction term coefficient Ki is switched and the scanning measurement process is performed again, and it is determined whether or not the trajectory error L is changing in vibration.

If “Yes” is determined in step S19, the command output unit 54 initializes the variable i (i = 1) and adds 1 to the variable j (step S20). Then, it is determined whether or not the variable j exceeds the maximum value jmax (in the example of Table 2, jmax = 2) (step S21).
If it is determined “No” in step S21, the process returns to step S4. That is, the command output unit 54 sets the next combination βj as DATA (β) and outputs it to the motion controller 3. As a result, the angle range for setting the trajectory correction term coefficient Ki is changed, the scanning measurement process is performed again, and it is determined whether or not the trajectory error L is changing in vibration.

  If “Yes” is determined in step S21, the host computer 5 issues a warning notification from an output unit such as a display, for example. That is, since the trajectory correction term coefficient Ki and the combination βj recorded in the coefficient DB and the combination DB cannot obtain sufficient trajectory accuracy, a notice for prompting the review of the trajectory correction term coefficient Ki and the combination βj, and other vibration causes Notification of.

[Operational effects of this embodiment]
In the present embodiment, the command output unit 54 outputs a measurement command including a trajectory correction term coefficient Ki for the angle θ formed by the indentation correction vector Ve and the trajectory correction vector Vc, and the speed synthesizer 344 of the motion controller A speed synthesis vector V is calculated by synthesizing Vf, the indentation correction vector Ve, and the trajectory correction vector Vc corrected by the trajectory correction term coefficient Ki.
In this way, even when the indentation correction vector Ve and the trajectory correction vector Vc work in the direction of canceling each other, the trajectory correction vector Vc is corrected by the trajectory correction term coefficient Ki to reduce the size of the trajectory correction vector. The influence of the trajectory correction vector can be reduced. Therefore, generation | occurrence | production of a vibration can be suppressed and a highly accurate shape measurement can be implemented.

In the present embodiment, the command output unit 54 outputs the angle coefficient correspondence data DATA (K) in which the trajectory correction term coefficient Ki is set for each of a plurality of angle ranges to the motion controller 3. Then, the speed synthesizer 344 identifies the angle range to which the angle θ belongs, and acquires the trajectory correction term coefficient Ki corresponding to the identified angle range from the angle coefficient correspondence data DATA (K).
As a result, the trajectory correction term coefficient Ki can be obtained more easily than when the trajectory correction term coefficient Ki is calculated, and the processing can be simplified and the measurement time can be shortened.

In the present embodiment, the accuracy determination unit 55 has low measurement accuracy when the maximum value d ² Lmax of the variation differential value d ² L _n of the trajectory error L _n is equal to or greater than the allowable value d ² La. Is determined. In this case, the command output unit 54 adds 1 to the variable i, switches the angle coefficient correspondence data, sets it to DATA (K), and outputs it to the motion controller 3 by including it in the measurement command.
Therefore, when it is determined that the measurement accuracy is low, the trajectory correction term coefficient Ki is sequentially switched. Thereby, the optimal trajectory correction term coefficient Ki according to the measurement conditions can be selected, and a decrease in measurement accuracy can be suppressed.

In the present embodiment, when the accuracy determination unit 55 determines that the measurement accuracy is low, the command output unit 54 adds 1 to the variable j, switches the angle range combination βj, and sets it to DATA (β). And output to the motion controller 3 in the measurement command.
Thereby, the angle range to which the angle θ formed by the push correction vector Ve and the trajectory correction vector Vc belongs can be changed, and the trajectory correction term coefficient Ki is also switched. Therefore, similarly to the above-described invention, the optimum trajectory correction term coefficient corresponding to the measurement condition can be selected, and a decrease in measurement accuracy can be suppressed.

[Second Embodiment]
Hereinafter, a second embodiment according to the present invention will be described with reference to the drawings.
In the first embodiment, the influence of friction between the probe 211A and the workpiece W is not taken into consideration. However, in the second embodiment, the first measurement is performed in that the scanning measurement is performed in consideration of the influence of the friction. It is different from the embodiment.

In this embodiment, it has the same structure as the coordinate measuring machine 1 of 1st embodiment shown in FIG.1 and FIG.2. Therefore, the description of the schematic configuration of the coordinate measuring machine in this embodiment is omitted.
In the present embodiment, the command output unit 54 acquires the curvature in the measurement section of the device under test from the design data, and includes the curvature in the measurement command.

  The arithmetic processing unit 33 of the motion controller 3 also functions as a normal direction calculation unit of the present invention. That is, the arithmetic processing unit 33 acquires the curvature (curvature included in the measurement command) in the segment section corresponding to the probe position PP, and determines whether the curvature is equal to or greater than a predetermined threshold value set in advance. When the curvature is equal to or greater than the threshold, the arithmetic processing unit 33 calculates the normal direction of the object W to be measured based on the quadratic curve passing through the coordinates of the three probe positions measured at the sampling interval. . In addition, when the curvature is less than the threshold, the arithmetic processing unit 33 calculates the normal direction of the workpiece W based on a straight line passing through the coordinates of the two probe positions measured at the sampling interval.

Hereinafter, the shape measuring method in this embodiment will be described.
In the present embodiment, for example, the command output unit 54 outputs a measurement command including the curvature of the measurement target section of the workpiece W based on the design data to the motion controller 3. For example, in step S5 in FIG. 4, a measurement command including the curvature of the workpiece W is output.
Thereafter, in the scanning measurement process (for example, step S7 to step S9 in FIG. 4), the following process is performed.
FIG. 7 is a flowchart showing a scanning measurement process considering the friction countermeasure process in the shape measurement method according to the second embodiment.
As shown in FIG. 7, in the present embodiment, first, a copying approach process is performed (step S31). In this step S31, the probe 211A is moved to the scanning start point (the first interpolation point in the PCC curve) to position the probe center.
Next, the drive control unit 35 initializes a probe center point registration buffer (hereinafter simply referred to as a buffer) for registering the center point of the probe 211A in the storage unit 36 (step S32). That is, the buffer value is set to zero.

  Thereafter, the drive control unit 35 performs a copying measurement process (step S33). In step S33, active control of design value copying is performed and the buffer is updated as in the first embodiment described above. That is, the center point coordinates of the probe 211A for each sampling interval are sequentially recorded and updated in the buffer. In the present embodiment, the center point coordinates of the measuring elements recorded in the buffer may be at least three or more. In the present embodiment, the coordinates of the center points of the five measuring elements can be recorded in the buffer and updated sequentially. I will do it.

  Next, the drive control unit 35 determines whether or not the probe 21 has arrived at the end point in the PCC curve, that is, whether or not the end condition is satisfied (step S34). If “Yes” is determined in step S34, the copying measurement process is terminated.

  If it is determined as “No” in step S34, the arithmetic processing unit 33 determines whether there is a command indicating the friction countermeasure process, for example, by an operator setting input (step S35). If it is determined as “No” in step S <b> 35, the process proceeds to step S <b> 42 described later, and the arithmetic processing unit 33 calculates contact coordinates. A method for calculating the contact coordinates will be described later.

If it is determined as “Yes” in step S <b> 35, the arithmetic processing unit 33 specifies the curvature corresponding to the current probe position from the curvature of the workpiece W included in the measurement command, and the curvature is a predetermined threshold value. It is determined whether or not this is the case (step S36).
The curvature is a reciprocal 1 / R of the radius of curvature R, and for example, R = 100 mm can be adopted as the threshold value in the present embodiment. That is, in this embodiment, it is determined whether the curvature is 1/100 or more.
If it is determined “No” in step S36, the arithmetic processing unit 33 calculates the normal direction of the object W to be measured at a predetermined position based on the center point of the two measuring elements 211A recorded in the buffer. (Step S37).

Hereinafter, the process of step S37 will be described.
FIG. 8 is a diagram for explaining a normal direction setting method using two points. In the present embodiment, as shown in FIG. 8, the case where the coordinates of the center point of the four measuring elements 211A are recorded in the buffer will be described. In step S <b> 37, the arithmetic processing unit 33 determines the center position (x0, y0) of the measuring element 211 </ b> A sampled before the position (for example, the point (x1, y1.z1) for which the normal direction is to be obtained. , Z0)). Then, the arithmetic processing unit 33 calculates the direction N1 orthogonal to the straight line connecting these two points as the normal direction. At the point (x2, y2, z2), the normal direction N2 can be calculated by the same method.

The process of step S37 will be described in more detail using FIG. FIG. 9 is a model diagram in the case where the frictional force is applied when the tracing stylus 211A is moved in the scanning direction when the curvature is less than the threshold value. In FIG. 9, the center position of the current probe 211A is O (x1, y1, z1), and the center position of the previous probe 211A (the center position of the probe 211A before a predetermined time) is O ′ (x0, y0, z0), the center position (probe origin) when the probe 211A is not in contact with the workpiece W is calculated based on C (Cx, Cy, Cz) and the movement amount of the slide mechanism at the current position O. The coordinate position calculated based on the movement amount of the stylus 211 at the current position O (probe deflection amount from the probe origin) (Px, Py, Pz) and the current position O The normal direction vector (N1 in FIG. 8) of the workpiece W at (Nx) is (Nx, Ny, Nz), and the radius of the probe 211A is R.
In FIG. 9, when the perpendicular foot from the probe origin C to the straight line OO ′ is Q, the vector CQ is on a plane perpendicular to the scanning direction, and is the normal direction of the object W to be measured.
The vector CQ is expressed as shown in the following formula (4), and the formula (5) can be derived from the formula (4).

Therefore, the unit vector e _u ′ with respect to the normal direction of the object W to be measured is e = (Nx ² + Ny ² + Nz ² ) ^1/2 , where e _u ′ = (Nx / e, Ny / e, Nz / e). Ny, Nx, Nz can be obtained by the above equation (5).

Returning to FIG. 7, when it is determined “No” in step S <b> 36, the arithmetic processing unit 33 determines a plane using the center points of the three measuring elements 211 </ b> A recorded in the buffer (step S <b> 38).
FIG. 10 is a diagram for explaining a normal direction setting method using three points.
In this step S38, as shown in FIG. 10, for example, a plane coordinate system (uv plane) passing through the three points acquired at the sampling interval is constructed, and the coordinates of the three points are converted into the constructed plane. For example, three points (x ₁ , y ₁ , z ₁ ), (x ₂ , y ₂ , z ₂ ), (x ₃ , y ₃ , z ₃ ) are 3 points (u ₁ , v ₁ ), (u ₂ , v ₂ ), (u ₃ , v ₃ ).

Next, the arithmetic processing unit 33 calculates a quadratic curve (v = au ² + bu + c) passing through three points coordinate-transformed with respect to the constructed work coordinate system (planar coordinate system (uv plane)). (Step S39). This quadratic curve can be easily calculated by using a known interpolation method such as Newton interpolation.

Thereafter, the arithmetic processing unit 33 differentiates the quadratic curve calculated in step S39, and uses the final point (third sampling point) of the three points as a target point to be calculated in the normal direction. The tangent at the target point is determined (step S40). For example, 3-point _{(u 1, v 1),} (u 2, v 2), (u 3, v 3) to the secondary curve passing through ^{(v = au 2 + bu +} c), tangential _(v-v 3) = (2au ₃ + b) × (u−u ₃ ) is calculated. Further, the arithmetic processing unit 33 can calculate the tangent formula in the three-dimensional coordinate system by reconverting the calculated tangent formula from the work coordinate system to the xyz coordinate system.

Thereafter, the arithmetic processing unit 33 determines a direction orthogonal to step S40 as the work normal direction (N1 ′, N2 ′ in FIG. 10) (step S41).
FIG. 11 is a model diagram when a frictional force is applied when the tracing stylus 211A is moved in the scanning direction when the curvature is equal to or greater than the threshold value. In FIG. 11, the center position of the current probe 211A is O (x1, y1, z1), and an arbitrary point on the tangent calculated in step S40 is O ″ (x0 ′, y0 ′, z0 ′). The center position (probe origin) when the child 211A is not in contact with the workpiece W is C (Cx, Cy, Cz), and the coordinate position calculated based on the movement amount of the slide mechanism at the current position O is (Mx , My, Mz), the coordinate position calculated based on the amount of movement of the stylus 211 at the current position O (probe deflection from the probe origin) (Px, Py, Pz), and the measured object W at the current position O. The normal vector (N1 ′ in FIG. 10) is (Nx, Ny, Nz), and the radius of the probe 211A is R.
In FIG. 11, the vector CQ is in the normal direction of the object W to be measured, where Q is a perpendicular line extending from the probe origin C to the straight line OO ″. Therefore, the arithmetic processing unit 33 can calculate the vector CQ (vector in the normal direction of the object W to be measured) by replacing the point O ′ with the point O ″ in the above formulas (4) and (5).

Returning to FIG. 7, the arithmetic processing unit 33 calculates the contact coordinates (measurement data) between the workpiece W and the probe 211A based on the normal direction obtained in step S37 or step S41 (step S42). ), The process returns to step S33.
Here, the calculation method of the contact coordinate by step S42 is demonstrated.
FIG. 12 is a diagram illustrating a model for scanning measurement when friction does not occur, and FIG. 13 is a diagram illustrating a model for scanning measurement when friction is generated.
12 and 13, a point D indicates a contact point between the measuring element 211A and the workpiece W, a point O indicates a center point of the measuring element 211A, and R indicates a radius of the measuring element. As shown in FIG. 12, when there is no influence of friction, the displacement direction of the probe is the normal direction of the workpiece W, and the contact coordinates are calculated based on the normal direction.
On the other hand, as shown in FIG. 13, in the case where friction is taken into consideration between the probe 211A and the workpiece W, in this case, in the normal direction of the workpiece W calculated in step S37 or step S42. Based on this, contact coordinates are calculated.

In the following description, the contact coordinates between the stylus 211 and the object W to be measured in the probe coordinate system are D (Dx, Dy, Dz), and the contact coordinates between the stylus 211 and the object W to be measured in the coordinate system of the coordinate measuring machine 1 are described. Is T (Tx, Ty, Tz).
Specifically, when it is determined as “No” in Step S35 (when the frictional force is not considered), the unit vector eu of the normal vector e with respect to the normal direction indicates the magnitude of the vector e as e = (Px ² + Py ² + Pz ² ) ^1/2 , and expressed by eu = (Px / e, Py / e, Pz / e). Therefore, the arithmetic processing unit 33 calculates the contact coordinate positions D and T as shown in the following equations (6) and (7).

On the other hand, when it is determined as “Yes” in step S35 (when the frictional force is taken into consideration), the normal vector of the workpiece W comes into contact with the workpiece W as shown in FIGS. The stylus 211 is projected onto a plane orthogonal to the relative movement direction from the origin C of the stylus 211 in a state where the stylus 211 is not. Therefore, the arithmetic processing unit 33 uses the normal vector of the workpiece W calculated in step S37 or step S42, and removes the influence of the frictional force generated in the counter-movement direction of the probe 21. In this case, the unit vector eu' of the normal vector, as described ^{above, e'=} as ^{(Nx 2 + Ny 2 + Nz} 2) 1/2, e u '= (Nx / e, Ny / e, Nz / e ) Further, (Nx, Ny, Nz) is calculated based on the coordinate position (Px, Py, Pz) calculated based on the movement amount of the stylus 211 at the current position O, as shown in Expression (5). Can do.
Therefore, the arithmetic processing unit 33 calculates the contact coordinate positions D and T as shown in the following equations (8) and (9).

  Note that by determining Nx, Ny, and Nz so that e ′ = 1, the arithmetic processing unit 33 can easily calculate the contact coordinates using the following formula (10).

  Thereby, in step S34, the measurement data output to the host computer 5 after the measurement is completed becomes an appropriate value in which the frictional force is considered based on the normal direction of the workpiece W, and the measurement accuracy is improved. be able to.

  In the present embodiment, FIG. 7 shows the process of returning to step S33 after step S42. At this time, the processes of step S10 to step S15 shown in FIG. 4 of the first embodiment may be performed. . Similarly, when it is determined “Yes” in step S34, the processing from step S16 to step S22 illustrated in FIG. 4 may be performed.

[Operational effects of this embodiment]
In the present embodiment, according to the curvature of the workpiece W, when the curvature is less than the threshold and the curvature radius is large, a straight line between the two center points of the sampled probe 211A is used. Is calculated as the normal direction of the workpiece W, and when the curvature is equal to or greater than the threshold and the radius of curvature is small, a quadratic curve is calculated from the three central points of the probe 211A. The direction perpendicular to the tangent of the midpoint is calculated as the normal direction.
Thereby, the normal direction with respect to the measurement point can be calculated with high accuracy according to the curvature of the workpiece W. Therefore, by calculating the contact coordinates using the normal direction, it is possible to perform highly accurate measurement while suppressing the influence of measurement error.

[Other Embodiments]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the first embodiment, the example in which the angle range to which the angle θ belongs is specified from the angle coefficient correspondence data stored in the coefficient DB and the trajectory correction term coefficient Ki of the angle range is obtained has been described. However, the present invention is not limited to this. Not. For example, the trajectory correction term coefficient may be calculated using a predetermined function equation K (θ) with respect to the angle θ.
Further, although an example in which two angle coefficient correspondence data is recorded in the coefficient DB is shown, for example, three or more angle coefficient correspondence data may be recorded, or only one angle coefficient correspondence data may be used. Good. The same applies to the combination β recorded in the combination DB, and three or more combinations may be recorded, or only one combination may be recorded.
In addition, the example in which the trajectory correction term coefficient Ki is set through three angle ranges using α1, α2, and α3 as the angle ranges has been shown. However, the angle range is set using three or more angle ranges. Further, angle coefficient correspondence data and combinations classified in detail may be used.

In the second embodiment described above, an example in which the normal direction of the object W to be measured is obtained and the measurement value is calculated based on the normal line direction has been described. However, in the second embodiment, the calculated object W to be measured is calculated. The measurement accuracy can be further improved by applying the normal direction to the first embodiment.
That is, in the first embodiment, when calculating the push correction vector Ve, as a vector e _u, but using the unit vector in the displacement direction (vibration direction) of the probe 21, it is calculated this in the second embodiment By setting the normal direction, it is possible to carry out highly accurate scanning measurement. Specifically, the indentation direction component calculation unit 342 substitutes the unit vector e _u ′ in the normal direction calculated in step S37 or step 41 in FIG.

  In the second embodiment, when the curvature is equal to or greater than the threshold, a quadratic curve passing through the coordinates of the three probe positions PP is calculated, and the direction orthogonal to the tangential direction of the quadratic curve is the normal direction. It was. On the other hand, a curve formula (such as a cubic curve) passing through the coordinates of four or more probe positions may be calculated. Even in this case, in the calculated curve formula, a tangent line at a target point which is a calculation target of the normal direction may be calculated, and a direction orthogonal to the tangent line may be calculated as the normal direction.

In the first embodiment, the speed synthesizer 344 uses the gain functions f ₁ (E, C), f ₂ (E), and f _{3 as} the scanning drive gain Gf, the pushing direction correction gain Ge, and the trajectory correction gain Gc, respectively. Although an example in which (C) is applied has been shown, a velocity composite vector may be calculated using a preset gain. Even in this case, the measuring element 211A can be moved along the surface of the object W to be measured based on the path, and the shape is measured in consideration of the pushing amount, so that the shape measurement is performed quickly and with high accuracy. be able to.

  In addition, the specific structure for carrying out the present invention can be appropriately changed to other structures and the like within a range in which the object of the present invention can be achieved.

  The present invention can be applied to a shape measuring apparatus that measures the shape of an object to be measured by design value copying based on a design value.

DESCRIPTION OF SYMBOLS 1 ... CMM (shape measuring device), 2 ... CMM main body, 3 ... Motion controller, 5 ... Host computer, 21 ... Probe, 22 ... Movement mechanism, 31 ... Command acquisition part, 32 ... Counter part, DESCRIPTION OF SYMBOLS 33 ... Operation processing part, 34 ... Probe command part, 35 ... Drive control part, 36 ... Memory | storage part, 51 ... Memory | storage part, 52 ... Information acquisition part, 53 ... Path | route setting part, 54 ... Command output part, 55 ... Accuracy determination , 56 ... Shape analysis unit, 211 ... Stylus, 211A ... Measuring element, 341 ... Path component calculation unit, 342 ... Push-in direction component calculation unit, 343 ... Trajectory correction component calculation unit, 344 ... Speed synthesis unit, C ... Probe origin , E ₀ ... reference pushing amount, L ... orbit error, N1, N2, N1 ', N2' ... normal direction, O ... current position, PP ... probe position, R ... radius of measuring element, V ... velocity combined vector, Vc ... Road correction vector, Ve ... push correction vector, Vf ... path velocity vector, W ... DUT, eu, eu' ... unit vector, α1, α2, α3 ... partition angle, theta ... angle.

Claims (6)

A probe having a probe at the tip, a moving mechanism for moving the probe along the surface of the object to be measured, and the shape of the object to be measured by detecting contact between the probe and the surface of the object to be measured A shape measuring device for measuring
A command output unit for outputting a measurement command for commanding a movement path of the probe based on design data of the measurement object;
A path component calculation unit that calculates a path speed vector that is a speed component vector of the probe along the movement path based on the measurement command;
A pressing direction component calculation unit that detects a pressing amount of the probe into the object to be measured and calculates a pressing correction vector that is a speed component vector for correcting the pressing amount to a predetermined reference pressing amount;
A velocity component for returning the position of the probe onto the moving path from the amount of trajectory error and the direction of the trajectory deviation between the probe position and the moving path, calculated based on the current position of the probe and the moving path. A trajectory correction component calculation unit for calculating a trajectory correction vector that is a vector;
A speed synthesis unit that calculates a speed synthesis vector obtained by synthesizing the path speed vector, the indentation correction vector, and the trajectory correction vector;
A drive control unit that moves the probe based on the velocity composite vector, and
The command output unit outputs the measurement command including a trajectory correction term coefficient set with respect to an angle formed by the indentation correction vector and the trajectory correction vector;
The shape measuring apparatus, wherein the speed synthesis unit synthesizes the trajectory correction vector, the path speed vector, and the indentation correction vector corrected by the trajectory correction term coefficient. In the shape measuring apparatus according to claim 1,
The command output unit outputs the measurement command including angle coefficient corresponding data in which the trajectory correction term coefficient is set for each of a plurality of angle ranges,
The velocity synthesis unit corrects the trajectory correction vector from the angle coefficient correspondence data using the trajectory correction term coefficient for an angle range to which an angle formed by the indentation correction vector and the trajectory correction vector belongs. Shape measuring device. In the shape measuring apparatus according to claim 2,
A coefficient data storage unit for storing a plurality of the angle coefficient corresponding data in which the trajectory correction term coefficient for the angle range is different;
An accuracy determination unit that determines whether or not the maximum change amount of the trajectory error amount is less than a predetermined allowable value,
The command output unit changes the angle coefficient correspondence data included in the measurement command when the accuracy determination unit determines that the maximum change amount of the trajectory error amount is equal to or greater than the allowable value. A shape measuring device. In the shape measuring device according to claim 2 or 3,
A combination storage unit that stores a plurality of combination data in which combinations of the angle ranges are recorded;
An accuracy determination unit that determines whether or not the maximum change amount of the trajectory error amount is less than a predetermined allowable value,
The command output unit outputs the measurement command including the combination data, and when the accuracy determination unit determines that the maximum change amount of the trajectory error amount is equal to or greater than the allowable value, The shape measurement apparatus characterized by changing the combination data to be included. In the shape measuring device according to any one of claims 1 to 4,
The command output unit outputs the measurement command including a curvature of a measurement target section of the object to be measured,
When the curvature of the section to be measured corresponding to the position of the probe is equal to or greater than a threshold, the shape measuring apparatus calculates a curve equation from three or more positions of the probe, and calculates the surface of the object to be measured. A normal direction calculation unit that calculates a tangential direction and calculates a direction perpendicular to a straight line connecting the positions of the two probes when the curvature is less than the threshold as the tangential direction of the surface of the object to be measured. A shape measuring device comprising: A probe having a probe at the tip, a moving mechanism for moving the probe along the surface of the object to be measured, and the shape of the object to be measured by detecting contact between the probe and the surface of the object to be measured A shape measuring method of a shape measuring device for measuring
A command output step for outputting a measurement command for commanding a movement path of the probe based on design data of the object to be measured;
A path component calculating step for calculating a path speed vector that is a speed component vector of the probe along the movement path based on the measurement command;
A pressing direction component calculating step of detecting a pressing amount of the probe into the object to be measured and calculating a pressing correction vector which is a speed component vector for correcting the pressing amount to a predetermined reference pressing amount;
A velocity component for returning the position of the probe onto the moving path from the amount of trajectory error and the direction of the trajectory deviation between the probe position and the moving path, calculated based on the current position of the probe and the moving path. A trajectory correction component calculating step for calculating a trajectory correction vector that is a vector;
A velocity synthesis step of calculating a velocity synthesis vector obtained by synthesizing the path velocity vector, the indentation correction vector, and the trajectory correction vector;
Performing a drive control step of moving the probe based on the velocity composite vector;
In the command output step, the measurement command including a trajectory correction term coefficient set for an angle formed by the indentation correction vector and the trajectory correction vector is output,
In the velocity synthesis step, the trajectory correction vector is corrected by the trajectory correction term coefficient, and the corrected trajectory correction vector, the path velocity vector, and the indentation correction vector are synthesized.

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