JP4803545B2 - Straightness measurement method and apparatus - Google Patents

Description

  The present invention relates to a straightness measurement method and apparatus used for measuring a movement error of a micromechanical element.

When the stage (object) that moves linearly shows a motion trajectory (motion error) as shown in FIG. 10, the minimum interval f between the two planes when this trajectory is sandwiched between two parallel planes I and II is defined in JIS It is defined as the straightness of the movement.
As a method for measuring such a movement error, there is a conventional sequential two-point method.

  FIG. 11 is an explanatory diagram showing the principle of the sequential two-point method.

  In the sequential two-point method, two sensors A and B are fixed to a movable stage 101, and relative displacement with a measurement reference object 103 fixed at a place other than the stage 101 is used by using these two sensors A and B. taking measurement. From this measurement value, the shape error 105 of the measurement reference object 103 and the stage movement error 107 can be obtained independently.

More specifically, when the measurement start point (right end point) shown in FIG. 11 is set to 0 and the stage is sent in the right direction at intervals d between the two sensors A and B, the reference line (ideal straight line) The displacement of the stage with respect to 109 is assumed to be X ₁ , X ₂ ,.
On the other hand, the measurement reference object 103 is based on a straight line 111 parallel to the reference line 109 of the stage 101, and the displacement of the measurement reference object 103 corresponding to the sensor B at the 0 position of the stage 101 is expressed as Y ₁ , Y ₂ ,. Do it.
_Assuming that the outputs V _KA and V _KB of the sensors A and B with respect to the displacements X _K , Y _K , X _{K + 1} and Y _{K + 1 at the} K-th stage position, the following relationship is derived.
V _0B −V _0A = Y ₁ −X ₀
V _1A -V _0A = Y ₁ -X ₁ V _1B -V _0B = Y ₂ -Y ₁ -X _{1
V 2A -V 0A = Y 2 -X} 2 V 2B -V 0B = Y 3 -Y 1 -X 2
Thus, the general term at the Kth position is
_{V KA -V 0A = Y K -X} K V (K-1) B -V 0B = Y K -Y 1 -X K - 1
From the relationship described above, the displacements X _K and Y _K of the stage 101 and the measurement reference object 103 can be expressed as follows.
_{X K = V (K-1} ) B -V KA + X K - 1
_{Y K = V (K-1} ) B -V (K-1) A + Y K - 1
Here, by giving values of X ₀ = 0 and Y ₀ = 0 as initial values, X _K and Y _K can be obtained in order from X ₁ and Y ₁ , and the stage motion error is measured and evaluated quantitatively. It becomes possible to do.

  However, in the conventional sequential two-point method, the moving distance of the stage 101 and the distance between the two sensors A and B are problematic. That is, since the measurement interval d depends on the sizes of the two sensors A and B, measurement becomes difficult when the moving distance of the stage 101 as the measurement target is small.

  Further, the relationship between the dimension of the stage 101 and the dimensions of the two sensors A and B becomes a problem, and when the stage 101 to be measured is small, the two sensors A and B cannot be fixed here. Measurement becomes difficult.

JP 2001-157951 A

  The problem to be solved is that the measurement distance becomes difficult when the movement distance of the measurement object or the measurement object is small.

The present invention enables measurement even when the moving distance of the measuring object or the measuring object is small , and can be moved and stopped linearly at a predetermined measuring interval along a fixed measuring reference object. A stage, and a single displacement sensor that is supported by a moving mechanism provided on the stage and detects a relative displacement between a surface shape of the measurement reference object and a movement locus of the stage, and the stage includes the displacement sensor The moving mechanism can be arbitrarily moved from one sensor position to the other sensor position according to the measurement interval and can be positioned at each sensor position, and the displacement sensor is positioned at the one sensor position. The stage is moved and stopped at intervals to measure the relative displacement, and the displacement sensor is moved to the other sensor position for positioning. The relative displacement is measured by repeatedly moving and stopping at the measurement interval to measure the relative displacement at each of the two points for each measurement interval, and based on the measurement results of each of the two points for each measurement interval The straightness measurement method is characterized by obtaining the shape error of the measurement reference object and the movement error of the stage .

Further, a fixed measurement reference object , a stage that can be linearly moved and stopped at a predetermined measurement interval along the measurement reference object, a surface shape of the measurement reference object supported by a moving mechanism provided on the stage, and A single displacement sensor for detecting a relative displacement between the movement trajectories of the stage, and the stage arbitrarily moves the displacement sensor from one sensor position to the other sensor position according to the measurement interval by the moving mechanism. The displacement sensor is movable and can be positioned at each sensor position, the displacement sensor is positioned at the one sensor position, the stage is moved and stopped at the measurement interval, the relative displacement is measured, and the displacement sensor is moved to the other sensor position. The relative displacement is measured by repeatedly moving and stopping the stage at the measurement interval. Perform measurements versus displacement in the two points of each of the measurement interval, based on said measurement result of each two points for each measurement interval the metric object straightness measuring device to seek motion errors of shape error and the stage of It is characterized by.

The straightness measurement method of the present invention is supported by a fixed measurement reference object , a stage that can be linearly moved and stopped along the measurement reference object at a predetermined measurement interval, and a moving mechanism provided on the stage. A single displacement sensor for detecting a relative displacement between the surface shape of the measurement reference object and the movement locus of the stage, and the stage moves the displacement sensor from one sensor position according to the measurement interval by the moving mechanism. The position can be arbitrarily moved to the other sensor position and can be positioned at each sensor position, the displacement sensor is positioned at the one sensor position, the stage is moved and stopped at the measurement interval, and the relative displacement is measured. The displacement sensor is moved to the other sensor position and the positioning stage is repeatedly moved and stopped at the measurement interval to Perform measurements of the relative displacement by the constant in each two points of each of the measurement interval, obtains the motion errors of shape error and the stage of the metric object on the basis of the measurement result of the two points of each of the measurement interval Therefore, even when the moving distance of the movable body or the movable body is small, the measurement can be performed.

The straightness measuring apparatus of the present invention is supported by a fixed measurement reference object , a stage that can be linearly moved and stopped at a predetermined measurement interval along the measurement reference object , and a moving mechanism provided on the stage. A single displacement sensor for detecting a relative displacement between the surface shape of the measurement reference object and the movement locus of the stage, and the stage moves the displacement sensor from one sensor position according to the measurement interval by the moving mechanism. The position can be arbitrarily moved to the other sensor position and can be positioned at each sensor position, the displacement sensor is positioned at the one sensor position, the stage is moved and stopped at the measurement interval, and the relative displacement is measured. The displacement sensor is moved to the other sensor position and the positioning stage is repeatedly moved and stopped at the measurement interval to Perform measurements of the relative displacement by the constant in each two points of each of the measurement interval, obtains the motion errors of shape error and the stage of the metric object on the basis of the measurement result of the two points of each of the measurement interval be able to.

  For the purpose of enabling measurement even when the measurement object is moved or the measurement object is small, by measuring the relative displacement of the two points of the movable body or the fixed body separately by repeating the movement of the movable body It was realized.

  1 and 2 are explanatory views showing the principle of a straightness measurement method and apparatus according to Embodiment 1 of the present invention.

[Straightness measuring device]
In the straightness measuring apparatus of the present embodiment, the measurement reference object 1 is constituted by a block gauge, for example, and the movable body is a uniaxial stage 3 that can move linearly. The stage 3 is provided with, for example, a single sensor support portion 5. The sensor support portion 5 is arbitrarily moved from the sensor position A1 to the sensor position B1 by a moving mechanism on the stage 3, and is controlled at an arbitrary position. Thus, the displacement sensor 7 can be positioned. The moving mechanism is such that the sensor support 5 is supported on a fine rail, and the sensor support 5 is driven by a fine rack and pinion mechanism and a motor. However, the structure of the moving mechanism is arbitrary, and a manual moving mechanism is also possible.

  The stage 3 can be linearly moved and stopped along the measurement reference object 1 at a constant measurement interval d1. The measurement interval d1 corresponds to the interval between the sensor positions A1 and B1, and can be arbitrarily changed according to the size of the stage 3 and the movement distance.

  A displacement sensor 7 for detecting the relative displacement between the surface shapes of the fixed body and the movable body and the movement locus is detachably supported on the sensor support portion 5 of the stage 3. The displacement sensor 7 includes, for example, a laser displacement meter, an eddy current displacement meter, a capacitance displacement meter, and the like. Of these, the laser displacement meter is most suitable because it has a small measurement range (spot diameter).

  Based on the measurement result of the relative displacement between the surface shape and the motion trajectory of the measurement reference object 1 and the stage 3 at two points on the stage 3, for example, sensor positions A1 and B1, based on the measurement interval d1. And the movement error of the stage 3 are obtained.

  The measured shape error and motion error can be confirmed by displaying them on a display or used for controlling a machine tool.

[Straightness measurement method]
The relative displacement is measured at each measurement interval d1 by repeatedly moving the stage 3 at the sensor positions A1 and B1 of the stage 3 and disposing the displacement sensors 7 at the sensor positions A1 and B1, respectively. In the present embodiment, the measurement of the relative displacement at every measurement interval d1 is performed by disposing the displacement sensor 7 at the sensor position A1, which is one point of the stage 3, and moving the stage 3 at the measurement interval d1. After performing up to the Kth, the displacement sensor 7 is arranged at the other one sensor position B1, and the stage 3 is repeatedly moved at the measurement interval d1 until the position 0 to the Kth.

  Accordingly, the measurement of the relative displacement at every measurement interval d1 is performed separately by moving the stage 3 at the measurement interval d1 and repeating from the position 0 to the Kth position. That is, a method is adopted in which measurement is performed for each sensor position B1 after measuring the relative displacement measurement interval d1 for the sensor position A1 of the stage 3.

More specifically, as shown in FIG. 1, the displacement sensor 7 is supported by the sensor support portion 5 and is arranged at the sensor position A1. The stage 3 is moved at a constant measurement interval d1, and the relative displacement between the stage 3 and the measurement reference object 1 is measured from the position 0 to the Kth position. Thereafter, as shown in FIG. 2, the sensor support 5 is moved, the displacement sensor 7 is shifted to the sensor position B1, and similarly, measurement is repeated from position 0 to position K.
_{X K = V (K-1} ) B -V KA + X K - 1
_{Y K = V (K-1} ) B -V (K-1) A + Y K - 1
X _K and Y _K are sequentially measured using the relationship. Therefore, the straightness measurement method of the present embodiment can be said to be a repetitive two-point method with respect to the conventional sequential two-point method.

  FIG. 3 is an explanatory diagram showing a comparison between a conventional sequential two-point method and a repeated two-point method, in which (a) is a sequential two-point method and (b) is a repeated two-point method.

  The solid lines in FIGS. 3A and 3B indicate the stage movement error, and ● indicates the position of the stage at every measurement interval.

  As shown in FIG. 3A, in the sequential two-point method, the movement distance (measurement interval) of the stage is affected by the sensor interval, and thus the measurement interval cannot be reduced beyond a certain level. On the other hand, as shown in FIG. 3B, in the repetitive two-point method, the movement distance (measurement interval) of the stage 3 is not affected by the sensor interval, so that it was possible to measure at a finer measurement interval.

[When stage is small]
When the stage 3 is small, the displacement sensor 7 cannot be fixed on the stage 3, so that the positional relationship between the displacement sensor 7 and the measurement reference object 1 is switched. That is, the displacement sensor 7 is arranged on the fixed side other than the stage 3, and the measurement reference object 1 is fixed on the stage 3. In this case, the measurement reference object 1 having a size according to the size of the stage 3 is created. Further, the operation of moving the displacement sensor 7 from the sensor position A1 to the sensor position B1 is performed by the moving mechanism using the motor or the manually moving mechanism as described above. Therefore, the measurement reference object 7 becomes a movable body, and the mounting counterpart of the displacement sensor 7 becomes a fixed body.

  The measurement principle in this case is basically the same as that of the conventional sequential two-point method, but is as follows because the movement relationship between the displacement sensor 7 and the measurement reference object 1 is switched.

  4 and 5 are explanatory diagrams showing an outline of measurement at the sensor position A1 and the sensor position B1.

Similar to the above method, the relationship between the displacements X _K + Y _K and X _{K +} X _{K + 1} at the K-th sensor position and the sensor outputs V _KA and V _KB is as follows.
X ₀ + Y ₀ + = V _0A X ₀ + Y ₁ = V _0B
X ₁ + Y ₁ + = V _1A X ₁ + Y ₂ = V _1B
Therefore, the general formula can be expressed as follows.

_{X K - 1 + Y K -} 1 = V (K-1) A X K - 1 + Y K = V (K-1) B
From this relationship, X _K and Y _K can be expressed as follows.

X _K = _{V KA over V (K-1) B -} + X K - 1
_{Y K = V (K-1} ) B -V (K-1) A + Y K - 1
Here, X _K and Y _K can be obtained sequentially by setting initial values X ₀ = 0 and Y ₀ = 0 as in the conventional method.

[Experiment]
6 and 7 show an experimental apparatus for evaluating the performance of the measurement based on the repeated two-point method, FIG. 6 is a perspective view, and FIG. 7 is a perspective view seen from another direction.

  As shown in FIG. 6, this apparatus includes a measurement reference object 1, a single-axis stage 3, and a displacement sensor 7 that is a measurement sensor. In addition, a trigger sensor 9, a corner cube 11, and a laser length measuring device 13 are provided. I have.

  The stage 3 is manual in this experimental example, and is moved from the lower left to the upper right as indicated by the arrow E. However, the direction of movement may be reversed. The measurement reference object 1 is fixed on the stage 3, and the relative displacement with the measurement reference object 1 is measured by a measurement displacement sensor 7 fixed at a place other than the stage. In addition, a trigger sensor 9 for determining the measurement start point and end point is fixed to the opposite side of the displacement sensor 7. On the other hand, in order to measure the position of the stage 3 in the feeding direction, the corner cube 11 was fixed on the stage 3 and measured with a laser length measuring device 13 fixed outside. The trigger sensor 9, the corner cube 11, and the laser length measuring device 13 shown here are used for verifying the proposed principle and are not necessarily required.

  Using the above apparatus, the measurement was performed under the conditions that the distance between the sensor positions A1 and B1 was 0.2 mm and the total moving distance was 5 mm. In changing the sensor position A1 and the sensor position B1, a manual stage fixed on the stage 3 was used.

From the relative distance between the displacement sensor 7 and the measurement reference object 1 obtained from this experiment,
X _K = _{V KA over V (K-1) B -} + X K - 1
_{Y K = V (K-1} ) B -V (K-1) A + Y K - 1
The motion trajectory (motion error) of the stage 3 and the shape of the measurement reference object 1 obtained by using FIG. 8 are as shown in FIGS. FIG. 8 is a graph showing the motion trajectory of the stage, and FIG. 9 is a graph showing the shape of the measurement reference object.
As shown in FIGS. 8 and 9, it was confirmed that the method and apparatus of the proposed embodiment of the present invention were able to measure without interference between the movement of the measurement reference object 1 and the stage 3. As a result, the straightness of the stage 3 was 13.4 μm, and the straightness of the measurement reference object 1 was 1.7 μm. The stage 3 shows a large swell with a period of 1 mm, which coincides with the lead of the feed screw used for driving the stage 3 and is caused by the swirling of the screw. I understand that.
As described above, when the proposed method and apparatus of the embodiment of the present invention is used, it is possible to measure the straightness of the micromachine element that moves straight.

[Effect of Example]
According to the embodiment of the present invention, the number of displacement sensors 7 can be reduced from the conventional two to one, and the measurement interval limited by the sensor interval can be reduced.

  By exchanging the positional relationship between the displacement sensor 7 and the measurement reference object 1, there are no restrictions on the size and movement distance of the stage 3 to be measured, and in principle the minute stage 3 on the order of micrometers moves by a minute amount. Even in cases, it was possible to measure and evaluate the motion accuracy.

  That is, the straightness measurement method of the embodiment of the present invention includes the measurement reference object 1 and the stage 3 that can be linearly moved and stopped along the measurement reference object 1 at a constant measurement interval d1, and the measurement reference object 1 and the stage 3 Displacement sensor 7 for detecting the relative displacement between the surface shape and the movement locus of the measurement reference object 1 or two points on the stage 3 based on the measurement results for each measurement interval d1 and the measurement reference object 1 and A straightness measurement method for obtaining a shape error and a motion error of the stage 3, wherein the measurement of the relative displacement at every measurement interval is performed separately by repeatedly moving the stage 3 at two points of the stage 3. The measurement can be performed even when the moving distance is smaller or the stage 3 is small.

  Since the measurement for each relative displacement measurement interval d1 is performed for one point of the stage 3 and then for the other one point, the measurement is surely performed even when the moving distance of the stage 3 or the stage 3 is small. Can do.

  The straightness measuring apparatus of the embodiment of the present invention includes a measurement reference object 1 and a stage 3 that can be linearly moved and stopped along the measurement reference object 1 at a constant measurement interval d1, and the surfaces of the measurement reference object 1 and the stage 3 A displacement sensor 7 for detecting a relative displacement between the shape and the movement locus, and the shape error and the movement error of the measurement reference object 1 and the stage 3 based on the measurement result of the two points of the stage 3 at the measurement interval d1. A straightness measuring device for obtaining the relative displacement of the stage 3 in order to measure the relative displacement at every measurement interval d1 by repeatedly moving the stage 3 at two points of the stage 3 and arranging the displacement sensors separately. The measurement can be performed even when the moving distance is smaller or the stage 3 is small.

  After the displacement sensor 7 is placed at one point of the stage 3 and the displacement sensor 7 is placed at another point after the measurement of the relative displacement measurement interval d1, the stage 3 Even when the moving distance or the stage 3 is small, the measurement can be reliably performed.

It is explanatory drawing which shows the principle of a straightness measuring method and an apparatus (Example 1). It is explanatory drawing which shows the principle of a straightness measuring method and an apparatus (Example 1). It is explanatory drawing which shows the comparison with a sequential 2 point method and a repetition 2 point method, (a) is a sequential 2 point method, (b) is a repetition 2 point method (Example 1). It is explanatory drawing which shows the outline | summary of the measurement in sensor position A1 and sensor position B1 (Example 1). It is explanatory drawing which shows the outline | summary of the measurement in sensor position A1 and sensor position B1 (Example 1). It is a perspective view which shows the experimental apparatus for evaluating the performance of the measurement based on the two-point method repeatedly (Example 1). (Example 1) which is the perspective view seen from the other direction. It is a graph which shows the movement locus | trajectory of a stage (Example 1). It is a graph which shows the shape of a measurement reference object (Example 1). It is explanatory drawing which shows the movement locus | trajectory (movement error) of the stage (object) which carries out rectilinear movement (conventional example). It is explanatory drawing which shows the principle of a sequential two-point method (Example 1).

Explanation of symbols

1 Measurement standard (fixed body)
3 Stage (movable body)
5 Sensor support 7 Displacement sensor

Claims (4)

A fixed metric, and
A stage that can be linearly moved and stopped at predetermined measurement intervals along the measurement reference ;
A single displacement sensor that is supported by a moving mechanism provided on the stage and detects a relative displacement between the surface shape of the measurement reference object and the movement trajectory of the stage ;
The stage can arbitrarily move the displacement sensor from one sensor position to the other sensor position according to the measurement interval by the moving mechanism and can be positioned at each sensor position.
Positioning the displacement sensor to the one sensor position The stage is moved and stopped at the measurement interval to measure the relative displacement, and the displacement sensor is moved to the other sensor position to position the stage. By measuring the relative displacement by repeatedly moving and stopping at a measurement interval, the relative displacement is measured at each of the two points for each measurement interval,
Obtaining the shape error of the measurement reference object and the movement error of the stage based on the measurement results of each two points for each measurement interval;
A straightness measurement method characterized by the above. A single fixed displacement sensor;
A stage capable of linear movement and stopping at a predetermined measurement interval with respect to the displacement sensor;
A measurement reference object supported by a moving mechanism provided on the stage,
The single displacement sensor can detect a relative distance from the surface shape of the measurement reference object,
The stage is capable of arbitrarily moving the measurement reference object from one measurement position to the other measurement position according to the measurement interval by the moving mechanism and positioning at each measurement position.
Positioning the measurement reference object at the one measurement position The stage is moved and stopped at the measurement interval to measure the relative distance, and the measurement reference object is moved to the other measurement position for positioning. Measuring the relative distance by repeatedly moving and stopping the stage at the measurement interval and measuring the relative distance at two points for each measurement interval,
Obtaining the shape error of the measurement reference object and the movement error of the stage based on the measurement results of each two points for each measurement interval;
A straightness measurement method characterized by the above. A fixed metric, and
A stage that can be linearly moved and stopped at predetermined measurement intervals along the measurement reference ;
A single displacement sensor that is supported by a moving mechanism provided on the stage and detects a relative displacement between the surface shape of the measurement reference object and the movement trajectory of the stage ;
The stage can arbitrarily move the displacement sensor from one sensor position to the other sensor position according to the measurement interval by the moving mechanism and can be positioned at each sensor position.
Positioning the displacement sensor to the one sensor position The stage is moved and stopped at the measurement interval to measure the relative displacement, and the displacement sensor is moved to the other sensor position to position the stage. By measuring the relative displacement by repeatedly moving and stopping at a measurement interval, the relative displacement is measured at each of the two points for each measurement interval,
Obtaining the shape error of the measurement reference object and the movement error of the stage based on the measurement results of each two points for each measurement interval;
Straightness measuring device characterized by that. A single fixed displacement sensor;
A stage capable of linear movement and stopping at a predetermined measurement interval with respect to the displacement sensor;
A measurement reference object supported by a moving mechanism provided on the stage,
The single displacement sensor can detect a relative distance from the surface shape of the measurement reference object,
The stage is capable of arbitrarily moving the measurement reference object from one measurement position to the other measurement position according to the measurement interval by the moving mechanism and positioning at each measurement position.
Positioning the measurement reference object at the one measurement position The stage is moved and stopped at the measurement interval to measure the relative distance, and the measurement reference object is moved to the other measurement position for positioning. Measuring the relative distance by repeatedly moving and stopping the stage at the measurement interval and measuring the relative distance at two points for each measurement interval,
Obtaining the shape error of the measurement reference object and the movement error of the stage based on the measurement results of each two points for each measurement interval;
Straightness measuring device characterized by that.

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