JP2013108946A - Surface property measuring machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface property measuring machine to generate a measuring force appropriate for a measuring arm.SOLUTION: A surface property measuring machine includes: a stylus displacement detection means 20 including a measuring arm supported to a bracket to allow an arc motion around a rotation shaft, a stylus provided at a tip of the measuring arm, and a measuring arm attitude switching mechanism 60 having a voice coil to urge the measuring arm to a direction of the arc motion and applying a measuring force to the stylus; and a control unit 100. The control unit 100 includes hysteresis error obtaining means 124 to obtain a hysteresis error, target measuring force obtaining means 121 to obtain a target measuring force, command value calculation means 125 to calculate a measuring force command value on the basis of the target measuring force and the hysteresis error, and drive control means 122 to input current to the voice coil on the basis of the measuring force command value.

Description

  The present invention relates to a surface texture measuring machine. More specifically, the present invention relates to a surface property measuring machine including a measurement arm having a stylus that is brought into contact with the surface of a measurement object.

2. Description of the Related Art Conventionally, a surface property measuring machine that measures the surface property of an object to be measured by bringing a stylus into contact with the surface of the object to be measured is known (see, for example, Patent Document 1).
The surface follow-up type measuring instrument (surface texture measuring instrument) described in Patent Document 1 has a measuring arm having a stylus attached to the tip, and this measuring arm is provided so as to be swingable about an axis. Further, the measurement arm is driven by being rotated by the rotational force generator, and the measurement force can be applied in a predetermined direction. At this time, in the apparatus of Patent Document 1, it is possible to change the measurement direction upward or downward by controlling the rotational direction of the rotational force generating unit.

  The surface texture measuring machine further includes a memory for storing a measurement force command value for applying an optimum measurement force to the measurement arm with respect to the stylus type, the measurement direction, and the inclination of the detector. Then, a command value suitable for the condition is read from the measurement force command value stored in the memory, and the measurement force is applied to the measurement arm.

JP 2000-111334 A

By the way, in Patent Document 1 described above, the measurement force command value for optimizing the downward measurement force and the upward measurement force is stored in the storage unit, but an arbitrary measurement force is generated. When it is desired to add a new stylus, it is necessary to reset the measurement force command value.
However, if the same measurement force command value is set when the downward measurement force is applied to the measurement arm and when the upward measurement force is applied, a difference (hysteresis error) occurs in the actually generated measurement force. For example, even when the downward measuring force is adjusted to generate a measuring force of 10 mN, if the hysteresis error is 1 mN, the upward measuring force is 9 mN. Therefore, when it is desired to generate an arbitrary measurement force or when a new stylus is added, it is necessary to calculate the measurement force according to the measurement direction, and there is a problem that the operation becomes complicated.

  An object of the present invention is to provide a surface texture measuring machine that can easily generate an optimum measuring force on a measuring arm.

  A surface texture measuring machine according to the present invention includes a measuring arm supported on a main body so as to be capable of moving in a circular arc with a supporting shaft as a fulcrum, a stylus provided at a tip of the measuring arm and capable of contacting an object to be measured, and the measuring arm in an arc. A detecting means provided with a measuring force applying means for applying a measuring force to the stylus by urging in a moving direction; and a control unit for calculating a command value corresponding to the measuring force and controlling the driving of the measuring force applying means. The measuring force applying means includes a voice coil that urges the measuring arm in the arc motion direction with the support shaft as a fulcrum, and the control unit includes Hysteresis error acquisition means for acquiring a hysteresis error when the measurement arm is moved in a circular arc, target measurement force acquisition means for acquiring a target measurement force generated by the measurement arm, and the target measurement force And a command value calculation means for calculating a measurement force command value to be input to the voice coil with respect to the target measurement force based on the hysteresis error, and a current is input to the voice coil based on the measurement force command value. Drive control means.

  In the present invention, the command value calculation means calculates the measurement force command value based on the target measurement force acquired by the target measurement force acquisition means and the hysteresis error acquired by the hysteresis error acquisition means. In such a configuration, for example, a measurement force command value in which the target measurement force is corrected can be calculated so as to reduce the influence of the hysteresis error as compared with the case where the measurement force command value is obtained only from the target measurement force. . Therefore, by driving the measurement arm based on such a measurement force command value, it is possible to easily generate the optimum target measurement force for the measurement arm, and to perform highly accurate measurement with reduced influence of hysteresis error. Can be implemented.

  In the surface texture measuring instrument according to the present invention, the detection means includes a displacement detection unit that detects a movement amount of the measurement arm, and the control unit is a speed − that is a relationship of the measurement force with respect to the movement speed of the measurement arm. Storage means for storing measurement force data, a first moving speed when the predetermined arming command value is input to the voice coil and the measuring arm is moved in the first direction in the arc motion direction, and the provisional command A second movement speed when a value is input to the voice coil and the measurement arm is moved in a second direction opposite to the first direction is calculated from the movement amount detected by the displacement detection unit. And calculating the hysteresis error based on the first moving speed, the second moving speed, and the speed-measuring force data. Arbitrariness.

In this invention, the speed calculation means moves the measurement arm in the second direction based on the first moving speed when the measurement arm is moved in the first direction based on the temporary command value and the temporary command value. The second moving speed at the time is calculated. Then, the hysteresis error acquisition means calculates a hysteresis error based on the first movement speed, the second movement speed, and the speed-measurement force data stored in the storage means.
Hysteresis error is the difference between the measurement force generated when the measurement arm is moved in the first direction and the measurement force generated when the measurement arm is moved in the second direction. Is proportional. For this reason, the measuring force with respect to the difference (hysteresis amount) between the first moving speed and the second moving speed becomes a hysteresis error. Therefore, the hysteresis error acquisition means can calculate the hysteresis error by a simple calculation process based on the first movement speed, the second movement speed, and the speed-measurement force data stored in the storage means.

In the surface texture measuring machine according to the present invention, the control unit may include a storage unit that stores the hysteresis error, and the hysteresis error acquisition unit may acquire the hysteresis error from the storage unit.
The hysteresis error is a constant value regardless of the measurement force generated in the measurement arm. Therefore, when the hysteresis error is stored in advance in the storage unit and the measurement force command value is calculated, the hysteresis error stored in the storage unit is read out by the hysteresis error acquisition unit, so that the measurement force command value can be calculated more quickly. Calculation processing can be performed.

In the surface texture measuring machine according to the present invention, the storage means includes a predetermined reference command value and a measurement force generated by an arc motion of the measurement arm when a current corresponding to the reference command value is input to the voice coil. Preferably, the command value calculation means calculates the measurement force command value based on the target measurement force, the hysteresis error, and the gain error.
In the present invention, the target command value calculation means can calculate a measurement command value that reduces the gain error in addition to the hysteresis error. As a result, a more optimal measurement force command value can be calculated for the target measurement force acquired by the target measurement force acquisition means, and the influence of errors during measurement can be further reduced.

  In the surface texture measuring machine according to the present invention, when the target measurement force is A, the reference command value is S, the gain error is G, the hysteresis error is H, and the measurement force command value is X, the command value calculation is performed. The means preferably calculates the measurement force command value by the following equation.

[Equation 1]
X = A− (A × G / S) ± (H / 2) (1)

  In the present invention, a command value for causing the measurement arm to generate the target measurement force is calculated based on the above equation (1). Thereby, the hysteresis error can be distributed to the center with respect to the target measuring force, and the gain error correction corresponding to the target measuring force can be performed. As a result, an appropriate command value that is not affected by the error can be quickly calculated.

The perspective view which shows the surface texture measuring machine which concerns on embodiment of this invention. The figure which shows the X-axis drive mechanism and stylus displacement detection means of this embodiment. The top view which shows the relationship between the measurement arm of this embodiment, and a displacement detector. The figure which shows the measurement arm and measurement arm attitude | position switching mechanism of this embodiment. The block diagram which shows the system configuration | structure of this embodiment. The flowchart which shows the calculation process of the measurement force command value in the surface texture measuring machine of this embodiment.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
[Configuration of surface texture measuring instrument]
FIG. 1 is a perspective view showing a configuration of a surface texture measuring instrument according to this embodiment.
As shown in FIG. 1, the surface texture measuring machine includes a base 1, a stage 10 that is placed on the base 1 and places an object to be measured on the upper surface, and a stylus 26A that is in contact with the surface of the object to be measured. The stylus displacement detecting means 20 having 26B, and a relative movement mechanism 40 for relatively moving the stylus displacement detecting means 20 and the stage 10 are provided.

  The relative movement mechanism 40 is provided between the base 1 and the stage 10 and moves the stage 10 in one horizontal direction (Y-axis direction), and a column erected on the upper surface of the base 1. 42, a Z slider 43 provided on the column 42 so as to be movable in the vertical direction (Z-axis direction), a Z-axis drive mechanism 44 for raising and lowering the Z slider 43 in the vertical direction, and a stylus provided on the Z slider 43. An X-axis drive mechanism 45 that moves the displacement detection means 20 in a direction (X-axis direction) orthogonal to the movement direction (Y-axis direction) of the stage 10 and the movement direction (Z-axis direction) of the Z slider 43; Accordingly, the relative movement mechanism 40 includes the Y-axis drive mechanism 41 that moves the stage 10 in the Y-axis direction, the Z-axis drive mechanism 44 that moves the stylus displacement detection means 20 in the Z-axis direction, and the stylus displacement detection means 20 as X. The three-dimensional moving mechanism includes an X-axis driving mechanism 45 that moves in the axial direction.

The Y-axis drive mechanism 41 and the Z-axis drive mechanism 44 are not shown in the figure, but are constituted by, for example, a feed screw mechanism having a ball screw shaft and a nut member screwed to the ball screw shaft.
FIG. 2 is a diagram showing the configuration of the X-axis drive mechanism 45 and the stylus displacement detection means.
As shown in FIG. 2, the X-axis drive mechanism 45 includes a drive mechanism main body 46 fixed to the Z slider 43, a guide rail 47 provided on the drive mechanism main body 46 in parallel with the X-axis direction, and the guide rail. 47, an X slider 48 provided so as to be movable in the X axis direction, an X axis position detector 49 for detecting the position of the X slider 48 in the X axis direction, and the X slider 48 is moved along the guide rail 47. And a feeding mechanism 50 to be operated.
The feed mechanism 50 is provided in the drive mechanism main body 46 in parallel with the guide rail 47 and the X slider 4.
8, a feed screw shaft 51, a motor 52 as a drive source, and a rotation transmission mechanism 53 that transmits the rotation of the motor 52 to the feed screw shaft 51. The rotation transmission mechanism 53 is configured by mechanisms such as a gear train, a belt, and a pulley, for example.

  As shown in FIG. 2, the stylus displacement detecting means 20 includes a bracket 22 as a main body that is detachably supported by a X slider 48 via bolts 21, and a rotating shaft 23 as a support shaft attached to the bracket 22. The measurement arm 24 supported as a fulcrum so as to be swingable in the vertical direction (arc movement is possible), a pair of styluses 26A and 26B provided at the tip of the measurement arm 24, and the arc movement of the measurement arm 24 (this embodiment) Then, a displacement detector 27 that detects the amount of displacement in the Z-axis direction, a balance weight 29 that can be adjusted in position on the measurement arm 24, and a first direction (for example, a downward direction) in which the measurement arm 24 moves in the arc motion direction. ) And the bracket 22, the measurement arm posture switching mechanism 60 that switches between the posture biased in the second direction and the posture biased in the second direction (for example, upward). Over arm 24, the displacement detector 27 is configured to include a casing 28 which balance weight 29, the measurement arm position switching mechanism 60 covers.

The measurement arm 24 is mounted on the bracket 22 so as to be exchangeable via a detachable mechanism 25 at the tip of the first measurement arm 24A supported by the bracket 22 so as to be capable of circular motion in the vertical direction about the rotation shaft 23 as a fulcrum. And the second measurement arm 24B. The attachment / detachment mechanism 25 connects the first measurement arm 24A and the second measurement arm 24B so that they are arranged in a straight line.
The styluss 26A and 26B are provided so as to protrude in the arc motion direction with respect to the second measurement arm 24B. That is, an upward stylus 26A and a downward stylus 26B are provided to protrude perpendicularly to the vertical direction with respect to the second measurement arm 24B.

FIG. 3 is a plan view showing the relationship between the measurement arm 24 and the displacement detector 27.
As shown in FIG. 3, the displacement detector 27 is provided along the arc motion range of the measurement arm 24, and is configured by a position detector that outputs a number of pulse signals corresponding to the amount of arc motion of the measurement arm 24. . Specifically, a scale 27A provided on the measurement arm 24 and curved in the arc movement direction of the measurement arm 24, and a detection head 27B attached to a bracket 22 as a main body facing the scale 27A are provided. The detection surface of the scale 27 </ b> A is arranged on the axis line of the measurement arm 24 and on the arc motion surface of the measurement arm 24. Accordingly, the detection surface of the scale 27A, the measurement arm 24, and the tips of the styluses 26A and 26B (see FIGS. 1 and 2 for the stylus 26B) are arranged on the same axis.
The balance weight 29 is provided so that its position in the axial direction of the measurement arm 24 can be adjusted so that the weight on the first measurement arm 24A side and the weight on the second measurement arm 24B side are balanced with the rotation shaft 23 as a fulcrum. Yes.

FIG. 4 is a diagram showing the measurement arm 24 and the measurement arm posture switching mechanism 60.
As shown in FIG. 4, the measurement arm posture switching mechanism 60 is fixed to the bracket 22 through the inside of the magnet 61 and a cylindrical magnet 61 provided in the middle of the first measurement arm 24A. It is constituted by a voice coil 62 that urges the rotating shaft 23 as a fulcrum in the first direction and the second direction of the arc motion direction, and is controlled by a command from the measuring force control circuit 70 (see FIG. 5). When a current is passed through the voice coil 62 according to a command from the measuring force control circuit 70, the magnet 61 of the measuring arm 24 is attracted to the voice coil 62 by the electromagnetic force generated from the voice coil 62 and the magnetic force of the magnet 61, and the measurement is performed. The posture is switched to a posture in which the tip of the arm 24 is urged upward or downward.
Here, the measurement arm posture switching mechanism 60 includes a voice coil 62 that urges the measurement arm 24 in the arc motion direction with the rotating shaft 23 as a fulcrum, and urges the measurement arm 24 in the arc motion direction to the stylus 26A, 26B. It also serves as the measuring force applying means of the present invention that applies the measuring force.

FIG. 5 is a block diagram showing a system configuration of the surface texture measuring machine.
As shown in FIG. 5, the surface texture measuring device includes a stylus displacement detection unit 20, a relative movement mechanism 40, a control unit 100, an input unit 101, an output unit 102, and a measurement force control circuit 70.
The control unit 100 is configured by, for example, a CPU and a memory. The control unit 100 includes a Y-axis drive mechanism 41, a Z-axis drive mechanism 44, an X-axis drive mechanism 45 of the relative movement mechanism 40, a displacement detector 27 included in the stylus displacement detection means 20, and a measurement arm posture switching mechanism 60 ( With respect to the measurement arm posture switching mechanism 60, an input unit 101, an output unit 102, and the like are connected via a measurement force control circuit 70).

The control unit 100 includes a storage unit 110 as shown in FIG. The storage unit 110 stores various programs and various data for controlling the surface texture measuring machine.
The storage means 110 stores speed-measuring force data indicating the relationship of the measuring force with respect to the moving speed of the measuring arm 24. In this speed-measuring force data, for example, a reference measuring force generated when the measuring arm 24 is moved in one direction in the arc motion direction at a predetermined reference moving speed is stored. Since the moving speed of the measuring arm 24 and the generated measuring force are in a proportional relationship, it is only necessary to store one piece of data as speed-measuring force data. Therefore, as the velocity-measurement force data, for example, when the reference movement speed of the measurement arm 24 is 5.2 mm / s, it is only necessary to store one actual measurement data indicating that the reference measurement force is 52 mN. Further, the speed-measuring force data may be stored in advance in the storage means 110 in an inspection process or the like at the time of manufacturing the surface shape measuring machine, and the measured value is measured by the measurer using an electronic balance or the like. May be data input from the input means 101.

Further, the storage means 110 stores command value-gain error data indicating the relationship between the reference command value and a gain error generated when a current corresponding to the reference command value is input to the voice coil 62. Since the gain error has a proportional relationship with the measuring force, it is only necessary to store one data as the command value-gain error data. For example, when the reference command value is 50 mN and the measured value of the measured force when a current is applied to the voice coil 62 based on the reference command value is 52 mN, the gain error is 2 mN. In this case, it is only necessary to store one command value-gain error data indicating that the gain error is 2 mN with respect to the reference command value 50 mN.
Further, the command value-gain error data may be measured together with the speed-measurement force data and stored in the storage unit 110 in advance, for example, in an inspection process at the time of manufacturing the surface shape measuring machine. The data may be input from the input unit 101 by the measurer. Further, the control unit 100 may be configured to calculate based on velocity-measurement force data input from the input unit 101 by the measurer.

As shown in FIG. 5, the control unit 100 includes a target measurement force acquisition unit 121, a drive control unit 122, a speed calculation unit 123, a hysteresis error acquisition unit 124, a command value calculation unit 125, and a measurement unit 126.
The target measurement force acquisition unit 121 acquires the target measurement force input from the input unit 101 by the measurer. This target measurement force is a measurement force that is actually desired to be generated when the measurement arm 24 is moved in a circular arc.

The drive control unit 122 outputs a command value such as a measurement force command value calculated by a command value calculation unit 125 described later to the measurement arm posture switching mechanism 60 via the measurement force control circuit 70.
Although not shown, the measuring force control circuit 70 is a command signal generating means for outputting a command speed signal (digital signal) corresponding to the input measurement force command value, and a D / A for converting the command speed signal into an analog signal. The converter includes a constant current circuit that converts the command speed signal converted into an analog signal into a current and inputs the current to the voice coil 62. A frequency voltage converter that outputs an operation speed signal (voltage) corresponding to the operation speed of the measurement arm 24 based on a pulse signal (frequency) from the displacement detector 27 is provided, and a command speed signal and an operation speed signal are output by a subtractor. The constant current circuit may convert the difference voltage into a current and input the current to the voice coil 62 of the measurement arm posture switching mechanism 60.

The speed calculation unit 123 monitors the pulse signal output from the displacement detector 27 and calculates the moving speed based on the arc driving amount of the measurement arm 24.
The hysteresis error acquisition unit 124 calculates the first moving speed when the measurement arm 24 is moved in the first direction and the second movement rate when the measurement arm 24 is moved in the second direction, which is calculated by the speed calculation unit 123. The difference value of the moving speed is calculated as the hysteresis amount. Further, the hysteresis error acquisition unit 124 calculates a force (hysteresis error) corresponding to the hysteresis amount based on the speed-measurement force data.
The command value calculation means 125 calculates a measurement force command value for generating the target measurement force based on the target measurement force, the hysteresis error, and the gain error.
The calculation method of the measurement force command value by the control unit 100 will be described in detail in the description of the calculation process of the measurement force command value described later.

  The measuring means 126 measures the surface property of the measurement target based on the arc motion amount of the measuring arm 24 detected by the displacement detector 27.

[Calculation process of measuring force command value]
Next, the measurement force command value calculation process in the above surface texture measuring machine will be described with reference to the drawings.
FIG. 6 is a flowchart showing the calculation process of the measurement force command value in the surface texture measuring instrument of the present embodiment.
In the surface texture measuring machine of this embodiment, in order to set a measurement force command value, first, a hysteresis error is calculated. For this purpose, first, the drive control means 122 moves the measurement arm 24 (stylus 26A, 26B) to the uppermost end along the arc motion direction (S1).

Thereafter, the drive control means 122 generates a temporary command value for moving the measurement arm 24 in the first direction (downward), and inputs it to the voice coil 62 via the measurement force control circuit 70 (S2). As a result, the measurement arm 24 moves from the uppermost end along the arc motion direction to the lowermost end.
At this time, the speed calculation means 123 monitors the pulse signal output from the displacement detector 27 of the stylus displacement detection means 20, and the arc movement amount (displacement amount) of the measurement arm 24 in the first direction of the measurement arm 24. A moving speed (first moving speed) is calculated (S3).

Thereafter, the second moving speed in the second direction is obtained in the same manner. That is, the drive control means 122 moves the measurement arm 24 (stylus 26A, 26B) to the lowest end along the arc motion direction (S4).
And the drive control means 122 produces | generates the temporary command value which moves the measurement arm 24 to a 2nd direction (upward), and inputs it into the voice coil 62 via the measurement force control circuit 70 (S5). As this temporary command value, the same value as S2 is used. As a result, the measurement arm 24 moves from the lowest end along the arc motion direction to the highest end.
At this time, the speed calculation means 123 monitors the pulse signal output from the displacement detector 27 of the stylus displacement detection means 20, and from the arc motion amount (displacement amount) of the measurement arm 24 in the second direction of the measurement arm 24. A moving speed (second moving speed) is calculated (S6).

Next, the hysteresis error acquisition unit 124 calculates a hysteresis amount that is a difference value between the first movement speed and the second movement speed (S7).
For example, in S2 and S4, the generation of a measuring force of 50 mN is commanded as a temporary command value, the first moving speed calculated in S3 is 5.2 mm / s, and the second moving speed calculated in S6 is 6. In the case of 4 mm / s, the hysteresis amount is 1.2 mm / s.
Further, the hysteresis error acquisition unit 124 reads the speed-measurement force data from the storage unit 110 and calculates a hysteresis error which is a measurement force corresponding to the hysteresis amount (S8).
For example, when the fact that the measurement force for the speed of 5.2 mm / s is 52 mN is stored as the speed-measurement force data, the hysteresis error for the hysteresis amount of 1.2 mm / s is 1.2 mN.

Thereafter, the target measurement force acquisition unit 121 acquires the target measurement force in accordance with, for example, an input instruction from the input unit 101 by the measurer (S9).
The command value calculation means 125 generates a target setting force based on the target measurement force calculated in S9, the hysteresis error calculated in S8, and the command value-gain error data stored in the storage means 110. Is calculated (S10).
Here, when the target measurement force is A, the hysteresis error is H, the reference command value of the command value-gain error data is S, and the gain error is G, the command value calculation means 125 is the expression “ Based on “X = A− (A × G / S) ± (H / 2)”, the measurement force command value X is calculated.

For example, when the hysteresis error is 1.2 mN, the target measuring force is 30 mN, the reference command value S is 50 mN, and the gain error G is 2 mN,
The measurement force command value X1 for the first direction is X1 = 30 mN− (30 mN × 2 mN / 50 mN) − (1.2 mN / 2) = 28.2 mN. The measurement force command value X2 for the second direction is X2 = 30 mN− (30 mN × 2 mN / 50 mN) + (1.2 mN / 2) = 29.4 mN.

[Effects of Embodiment]
As described above, in the surface texture measuring instrument according to the present embodiment, the hysteresis error is calculated by the hysteresis error acquisition unit 124, and the command value calculation unit 125 calculates the target measurement force acquired by the target measurement force acquisition unit 121 and the calculation. Based on the hysteresis error, a measurement force command value is calculated. For this reason, it is possible to calculate a measurement force command value that reduces the effect of hysteresis error compared to the case where the measurement force command value is obtained only from the target measurement force, etc. Can be implemented.

The speed calculation means 123 moves the measurement arm 24 in the second direction based on the first moving speed when the measurement arm 24 is moved in the first direction based on the predetermined temporary command value and the temporary command value. The second moving speed is calculated. The hysteresis error acquisition unit 124 calculates a hysteresis error corresponding to a difference value (hysteresis amount) between the first movement speed and the second movement speed based on the speed-measurement force data stored in the storage unit 110.
By adopting such a configuration, it is possible to calculate the amount of hysteresis generated for a predetermined command value from the first moving speed and the second moving speed that are actually measured values, and to calculate an accurate hysteresis error. it can. In addition, since the moving speed and the measuring force are in a proportional relationship in the measuring arm 24, by storing speed-measuring force data in the storage means 110, the actual measuring force with respect to the moving speed can be calculated again when calculating the hysteresis error. There is no need to measure, and the hysteresis error can be calculated by simple arithmetic processing. For example, in the velocity-measurement force data, when the measurement force B is stored with respect to the velocity V, the hysteresis error H with respect to the hysteresis amount v can be calculated by H = B × v / V.
As described above, the hysteresis error acquisition unit 124 can easily and accurately acquire the hysteresis error, and realizes highly accurate measurement by calculating the measurement force command value based on such hysteresis error. be able to.

The storage means 110 stores command value-gain error data in which the gain error with respect to the reference command value is recorded. Then, the command value calculation means 125 calculates a measurement force command value based on this command value-gain error data.
Thereby, the command value calculation means 125 can reduce both the hysteresis error and the gain error, and can calculate a more optimal measurement force command value for generating the target measurement force.
At this time, the command value calculation means 125 calculates a measurement force command value based on the above-described equation (1). Thereby, it is possible to calculate the measurement force command value in consideration of the gain error corresponding to the target measurement force. Further, in order to calculate the measurement force command value when moving the measurement arm 24 in the first direction and the measurement force command value when moving the measurement arm 24 in the second direction, using the hysteresis error as the central distribution, the measurement arm is moved in the first direction. The measuring force generated when moved and the measuring force generated when moved in the second direction can be made the same.
Therefore, by using the measurement force command value calculated based on the equation (1), it is possible to carry out highly accurate measurement with reduced effects of gain error and hysteresis error.

<Other embodiments>
The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

For example, in the above-described embodiment, the hysteresis error acquisition unit 124 determines the hysteresis based on the first movement speed calculated by the speed calculation unit 123, the second movement speed, and the speed-measurement force data stored in the storage unit 110. The error was calculated.
However, as described above, the hysteresis error is a constant value regardless of the measurement force. Therefore, for example, in an inspection process at the time of factory shipment or the like, a hysteresis error is measured in advance, and the measured hysteresis error is stored in the storage unit 110. The hysteresis error acquisition unit 124 stores the hysteresis error stored in the storage unit 110. It is good also as a structure which reads an error.
In such a configuration, for example, it is not necessary to calculate a hysteresis error each time measurement is performed, and the measurement force command value can be calculated and measured more easily and quickly.

Although the example in which the speed-measuring force data is stored in the storage unit 110 has been shown, for example, when the measuring force command value is calculated, the relationship between the speed and the measuring force may be acquired based on the actual measurement value.
In this case, for example, after moving the measurement arm 24 to the uppermost position, the drive control means 122 inputs the reference command value to the voice coil 62 and moves it in the first direction (downward), and moves the stylus 26A (26B). ) Is brought into contact with a measuring force measuring instrument capable of measuring a measuring force such as an electronic balance. This makes it possible to measure the actual measurement force with respect to the reference command value.
Then, the speed calculation unit 123 detects the speed of the measurement arm 24 based on the pulse signal from the displacement detector 27. Thereby, the speed of the measurement arm 24 and the measurement force for the speed can be acquired.
Further, a gain error with respect to the reference command value can be acquired by acquiring a difference value between the reference command value and the measuring force actually measured by the measuring force measuring instrument.

  The present invention can be used, for example, in a surface texture measuring machine including a measuring arm having a stylus that is brought into contact with the surface of an object to be measured.

  DESCRIPTION OF SYMBOLS 20 ... Stylus displacement detection means (detection means), 22 ... Bracket (main body), 23 ... Rotating shaft (support shaft), 24 ... Measurement arm, 26A, 26B ... Stylus, 27 ... Displacement detector (displacement detector), 60 ... Measurement arm posture switching mechanism (measuring force applying means), 62 ... voice coil, 70 ... measuring force control circuit, 100 ... control unit, 110 ... storage means, 121 ... target measuring force acquisition means, 122 ... drive control means, 123 ... speed calculation means, 124 ... hysteresis error acquisition means, 125 ... command value calculation means.

Claims (5)

A measurement arm that is supported on the main body so as to be capable of moving in a circular arc with a support shaft as a fulcrum, a stylus that is provided at the tip of the measurement arm and that can contact an object to be measured; A detecting means comprising a measuring force applying means for applying a measuring force;
A control unit that calculates a command value corresponding to the measurement force and controls the driving of the measurement force application unit;
A surface texture measuring machine comprising:
The measurement force applying means includes a voice coil that urges the measurement arm in the arc motion direction with the support shaft as a fulcrum,
The controller is
Hysteresis error acquisition means for acquiring a hysteresis error when the measurement arm is moved in a circular arc;
Target measurement force acquisition means for acquiring a target measurement force generated by the measurement arm;
Based on the target measurement force and the hysteresis error, command value calculation means for calculating a measurement force command value input to the voice coil with respect to the target measurement force;
Drive control means for inputting a current to the voice coil based on the measured force command value;
A surface texture measuring machine comprising: In the surface texture measuring machine according to claim 1,
The detection means includes a displacement detection unit that detects a movement amount of the measurement arm,
The controller is
Storage means for storing speed-measuring force data which is a relationship of the measuring force with respect to the moving speed of the measuring arm;
When a predetermined temporary command value is input to the voice coil and the measurement arm is moved in the first direction in the arc movement direction, the first moving speed and the temporary command value are input to the voice coil. Speed calculating means for calculating a second moving speed when the measuring arm is moved in the second direction opposite to the first direction from the moving amount detected by the displacement detecting unit;
The surface texture measuring machine, wherein the hysteresis error acquisition means calculates a hysteresis error based on the first moving speed, the second moving speed, and the speed-measurement force data. In the surface texture measuring machine according to claim 1,
The control unit includes storage means for storing the hysteresis error,
The surface texture measuring instrument, wherein the hysteresis error acquisition means acquires the hysteresis error from the storage means. In the surface texture measuring instrument according to any one of claims 1 to 3,
The storage means stores a gain error which is a difference between a predetermined reference command value and a measurement force generated by an arc motion of the measurement arm when a current corresponding to the reference command value is input to the voice coil. ,
The surface property measuring instrument, wherein the command value calculation means calculates the measurement force command value based on the target measurement force, the hysteresis error, and the gain error. In the surface texture measuring machine according to claim 4,
When the target measurement force is A, the reference command value is S, the gain error is G, the hysteresis error is H, and the measurement force command value is X,
The command value calculation means calculates the measurement force command value by the following equation.
X = A− (A × G / S) ± (H / 2)
A surface texture measuring machine characterized by that.

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