JPH1047943A - Three-dimensional measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform three-dimensional measurement accurately. SOLUTION: When a measuring point is subject to measurement, the contact pressure of a measuring probe 14 is detected by a torque sensor 20. When the obtained value is judged to be larger than a reference pressure value by a judging part 32 of contact pressure, the contact angle of the probe 14 is changed within such a range where an interference checking part 28 judges it to have no interference, and the measuring point is measured again. When the obtained value still exceeds the reference pressure value, the approaching speed of the probe 14 to an object to be measured is made low by a measuring speed control part 34. Thus, even when the object has a small rigidity, it can be measured accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional measuring device for measuring, for example, a three-dimensional shape of a vehicle panel.

[0002]

2. Description of the Related Art Conventionally, in a trial manufacturing process or an inspection process, a three-dimensional automatic determination is made as to whether the shape of a body or the shape of a part such as a door panel is as designed or whether the dimensions of a produced vehicle are as designed. Measured with a measuring device.

For example, when measuring the shape of a door panel, the tip of a measuring probe provided in a three-dimensional automatic measuring device is moved to a preset measuring point based on position data created by CAD, and the position of the measuring point is measured. The operation of measuring the coordinates is performed for all the measurement points of the vehicle.

In this measurement, the contact pressure at which the measurement probe is brought into contact with the door panel greatly affects the measurement accuracy (for example, when the door panel is formed of a thin steel plate, The contact pressure of the measurement probe causes the deflection, which greatly affects the measurement accuracy.) Therefore, usually, the contact angle of the measurement probe is determined in advance for each measurement point (in a portion where the measurement point is easily bent). In some cases, the contact angle is set small, and conversely, in areas where the strength is high, the contact angle is set large.) The measurement is made as accurate as possible.

[0005]

According to such a conventional three-dimensional automatic measuring apparatus, since the contact angle of the measuring probe is set in consideration of the strength of the door panel at the measuring point, a certain degree of measuring accuracy is obtained. Can be obtained,
If more accurate measurement is required, it is very difficult to meet the requirement.

Of course, it is possible to calculate the optimum contact angle for each measurement point and set it for each measurement point. However, the strength of each measurement point on the door panel is not always the same, and the door panel is not always the same. Since the strength of each measurement point should differ slightly depending on how is placed on the measurement jig, the contact angle obtained by the calculation is not always optimal.

The present invention has been made to solve such a conventional problem. An optimum contact angle of a measurement probe with respect to a measurement object is calculated at the time of measurement, and the measurement at this contact angle is performed. It is an object of the present invention to provide a three-dimensional measuring device that can be used.

[0008]

The present invention for achieving the above object is constituted as follows for each claim.

According to the first aspect of the present invention, in a three-dimensional measuring apparatus having a contact-type measuring probe, when measuring the measuring object, the range in which the measuring object and the measuring probe do not interfere with each other. A three-dimensional measuring apparatus, comprising: a control unit that controls a contact angle of the measurement probe with respect to the measurement target such that a contact pressure of the measurement probe with respect to the measurement target within the measurement target is optimized. .

With this configuration, the contact pressure on the object to be measured is changed by changing the contact angle within a range where the object and the measurement probe do not interfere with each other (the contact angle is reduced for a flexible object). Since it can be adjusted freely, it is possible to perform high-precision measurement even if the measurement object is easily bent.

In the three-dimensional measuring apparatus having a contact-type measuring probe, the contact pressure of the measuring probe with respect to the measuring object is measured when measuring the measuring object. A three-dimensional measuring apparatus comprising a control means for controlling an approach speed of the measurement probe so as not to exceed a value.

With this configuration, the reference speed is not exceeded by changing the approach speed of the measurement probe to the object to be measured (by making the measurement probe slowly contact an object that is easily bent). Adjustment can be performed, and high-precision measurement can be performed even when the measurement target is easily bent.

According to the third aspect of the present invention, in the three-dimensional measuring apparatus having the contact-type measuring probe, when the measuring object is measured, the measuring object interferes with the probe before fixed measurement. While controlling the contact angle of the measurement probe to the measurement object so that the contact pressure of the measurement probe to the measurement object is optimal within a range not to be measured, the measurement is performed so that the contact pressure does not exceed a reference value. A three-dimensional measuring apparatus comprising a control means for controlling an approach speed of a probe.

With this configuration, since both the contact angle and the approach speed of the measurement probe can be changed, the range of the contact pressure that can be adjusted can be further expanded, and the range of the contact pressure that can be adjusted can be widened so as not to exceed the reference value. It is possible to perform high-accuracy measurement even if the object to be measured is easily bent.

According to a fourth aspect of the present invention, there is provided a measuring probe which is brought into contact with a measuring object to detect the coordinates of the measuring point, and a contact pressure of the measuring probe at the measuring point with respect to the measuring object. Contact pressure detecting means for detecting the contact pressure, if the contact pressure by the contact pressure detecting means exceeds a reference value, so that the contact pressure is within the reference value, the contact angle of the measurement probe with respect to the object to be measured A three-dimensional measuring device, characterized by having a control means for changing.

With such a configuration, the contact pressure on the object to be measured can be freely adjusted by changing the contact angle (or decreasing the contact angle for a flexible object). Even if the object is easy to bend, high-precision measurement can be performed.

According to a fifth aspect of the present invention, there is provided a measuring point storing means for storing measuring points on a measuring object, and a CA for storing CAD data of the measuring object.
D data storage means, wherein the control means determines the measurement probe from the measurement points stored in the measurement point storage means and the CAD data stored in the CAD data storage means. The three-dimensional measuring apparatus according to claim 2, wherein a contact angle of the measurement probe with respect to the measurement target is changed such that the contact pressure is within a reference value within a range that does not interfere with an object. .

With this configuration, the contact pressure on the object to be measured can be freely changed by changing the contact angle within a range in which the measuring probe does not interfere with the object to be measured (reducing the contact angle for a flexible object). Therefore, it is possible to perform high-precision measurement even if the object to be measured is easily bent.

According to a sixth aspect of the present invention, the control means further includes means for adjusting an approach speed of the measurement probe to the object to be measured such that the contact pressure is within a reference value. The three-dimensional measuring apparatus according to claim 4 or 5, wherein:

With such a configuration, the reference speed is not exceeded by changing the approach speed of the measurement probe to the object to be measured (by making the measurement probe slowly contact an object that is easily bent). Adjustment can be performed, and high-precision measurement can be performed even when the measurement target is easily bent.

According to a seventh aspect of the present invention, there is provided a measuring probe which is brought into contact with a measuring object to detect the coordinates of the measuring point, and a measuring point storage means for storing the measuring point on the measuring object. A CAD data storage unit that stores CAD data of the measurement target; a contact pressure detection unit that detects a contact pressure of a measurement probe with respect to the measurement target; a measurement point stored in the measurement point storage unit; Based on the CAD data stored in the CAD data storage means, calculate a non-interference range in which the measurement probe does not interfere with the measurement target,
Calculating the contact angle of the measurement probe within the non-interference range, the first control means for bringing the measurement probe into contact with the measurement point with the contact angle, and when the contact pressure at the measurement point exceeds a reference value, A second control unit that changes a contact angle of the measurement probe within the non-interference range so as not to exceed the reference value, and causes the measurement probe to contact the measurement point with the contact angle; A third control unit that adjusts an approach speed of the measurement probe to the measurement object so that the measurement probe does not exceed the reference value and makes the measurement probe contact a measurement point when the reference value is not exceeded. 3D measurement device.

With this configuration, since both the contact angle and the approach speed of the measuring probe can be changed, the range of the contact pressure that can be adjusted can be further expanded, and the range of the contact pressure that can be adjusted can be widened so as not to exceed the reference value. It is possible to perform high-accuracy measurement even if the object to be measured is easily bent.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an external view of a three-dimensional measuring apparatus according to the present invention. As shown in the figure, a body 12 of a vehicle is positioned and mounted on the measuring device 10 with high accuracy in a predetermined posture. The measurement device 10 is provided with arms 16 and 18 for moving the measurement probe 14 in the X, Y, and Z directions.

The measurement probe 14 is supported so that it can rotate and change the contact angle in the direction shown in FIG. In addition, X, Y, Z
A torque sensor 20 for measuring the contact force (contact pressure) in the three-dimensional direction is provided, and the tip portion is spherical.

In order to generate three-dimensional position data of a position where the tip of the measuring probe 14 is to come into contact with the body 12, data indicating a measuring point, that is, measuring point data, and design position data are generated at the time of designing the body 12. The CAD data obtained is used. In the present embodiment, the measurement point data is stored in a database described later, but the number is the number of points necessary and sufficient to recognize the shape of the body 12. Also,
The contact angle of the measurement probe 14 is also set in the measurement point data.

Therefore, the measurement probe 14 comes into contact with the coordinates on the CAD data specified by the measurement point data on the body 12 with the contact angle included in the measurement point data.

FIG. 3 is a block diagram showing a control system of the three-dimensional measuring apparatus according to the present invention. Database 2 in the figure
5 stores a measurement location on the body 12 and a contact angle of the measurement probe 14 at the measurement location. A sufficient number of measurement points are prepared in advance for measuring the shape of the body 12, and the contact angles are set in advance based on experience so that highly accurate measurement can be performed.

The database 12 contains the body 12
The design position data, which is CAD data created when designing the data, is stored.

When the measurement probe 14 is brought into contact with a specified contact angle on the coordinates of the measurement point based on the measurement point data and the CAD data, the interference check unit 28 This is a part for checking whether interference with the supporting part occurs, that is, whether measurement becomes impossible.

The probe angle controller 30 sets the measuring probe 14 to an angle determined not to interfere by the interference checker 28. Specifically, in FIG. 2, the spherical portion at the tip of the measurement probe 14 is moved up and down about its support axis.

The contact pressure judging section 32 detects the three-dimensional contact pressure of the measuring probe detected by the torque sensor 20 for each direction, and these contact pressures are stored in the pressure reference data stored in the database 33. This is to determine how much larger or smaller than the value.

The measuring speed control unit 34 changes the measuring speed of the measuring probe 14 based on the result of the judgment by the contact pressure judging unit 32. That is, if the measurement probe 14 approaches the body 12 relatively quickly, the contact pressure increases (due to the effect of overrun), and if it approaches very slowly, the contact pressure decreases.
When the contact pressure determining section 32 determines that the contact pressure has exceeded the reference pressure value, the approach speed is reduced so that the contact pressure falls within the reference pressure value.

Specifically, it has the following table. This table is common to the three axes X, Y, and Z.

Exceeding standard value ratio Speed adjustment + 50% or more -50% + 40% or more to less than 50% -40% + 30% or more to less than 40% -30% + 20% or more to less than 30% -20% + 10% or more to 20% % Less than -10% -10% or more to less than + 10% 0 ·········· The probe angle calculation unit 36 changes the contact angle of the measurement probe 14 based on the result of the determination by the contact pressure determination unit 32. Things. That is, when the measurement probe 14 is measured at a large contact angle with respect to the body 12, the contact pressure generally increases, and when measured at a small angle, the contact pressure decreases. When it is determined that the pressure exceeds the pressure reference value, the contact angle is reduced so that the contact pressure falls within the pressure reference value.

Specifically, it has the following table. The following table is for the X axis. Actually, such a table is provided on each of the X, Y, and Z axes.

Reference value excess ratio Contact angle adjustment amount + 50% or more −50 ° + 40% or more to less than 50% −40 ° + 30% or more to less than 40% −30 ° + 20% to less than 30% −20 ° + 10% or more未 満 <20% −10% -10% or more to less than + 10% 0 ゜... The three-dimensional measuring instrument of the present invention configured as described above operates roughly as follows. The following operation is related to the invention described in claims 1 to 7.

The three-dimensional measuring device 10 moves the spherical portion of the measuring probe 14 to the coordinates of the measuring point based on the measuring point data and the CAD data, and moves the measuring probe 14 toward the body 12 at a predetermined angle. Let it. This spherical portion comes into contact with the body 12 and the measuring probe 14
Is further lowered, a "click" sound is heard, and a switch (not shown) is turned on. At the same time as this switch is turned on, the position of each arm of the three-dimensional measuring apparatus is recognized, and the measurement is completed.

At this time, if the contact pressure of the measurement probe 14 is larger than the reference pressure, the reliability of the measurement accuracy becomes a problem (due to the bending of the object to be measured). change. When the measurement angle becomes small, the above-mentioned switch can be turned on with a small force. Therefore, when the contact pressure is larger than the reference value, the previous contact angle is further reduced and the measurement is performed again. For example, if the contact pressure exceeds the reference pressure by 20%, look at the table in the direction in which the contact pressure exceeds the reference pressure (for example, the Z axis) and reduce the direction by -20 °. In other words, if the contact pressure exceeds the reference pressure by 20% when the measurement probe 14 is measured at an angle of 60 °, the next measurement is performed at 40 °.

When changing the angle, an interference check with the body is performed. Even if the angle is set to an ideal angle, the measurement probe 14 may interfere with the body 12, and in such a case, the angle can be changed only within a range that does not interfere. .

In such a case, the approach pressure of the measuring probe 14 is changed so that the contact pressure falls within the reference pressure. If the approach speed of the measurement probe 14 to the body 12 is reduced, the overrun of the measurement probe 14 (it is desirable to stop at the moment when the switch is turned on) can be reduced, and the contact pressure is reduced accordingly. Because you can do it.

For example, in the above case, since the contact pressure is 20% higher than the reference pressure, in the next measurement, the approach speed is reduced by 0.8 times as shown in the above table. I do.

It is also possible to change both the contact angle and the approach speed.

For example, in the above case, the measurement probe 14
Can be set to -10 °, ie, 50 °, and at the same time, the approach speed can be set to -10%, ie, 0.9 times the normal speed.

As described above, when both the contact angle and the approach speed are to be changed, which one is to be preferentially changed, and when both are to be changed, which one is to be shared in such a manner is determined by a program. Of course you have to keep it.

Although the above description has been given of the case where the strong body 12 is used as the object to be measured, the three-dimensional measuring apparatus of the present invention is particularly suitable for measuring the shape of a thin panel as shown in FIG. It is effective. Hereinafter, the present invention will be described in more detail with reference to the flowchart of FIG. 7 taking the measurement of this panel as an example.

Before describing the flowchart, a method for fixing the panel and a method for measuring the shape of the thin panel shown in FIG. 4 will be described. Panel 40
Is placed on a dedicated jig 42 on which the
2 and is firmly fixed by a suction plate or the like provided on the upper part of the device 2. However, the end portions of the panel 40 and the central portion between the jigs are not very strong, and are easily bent by the contact pressure of the measurement probe 14.

The measurement point extends over the entire surface of the panel 40. Therefore, the measurement points are as shown in FIG.
End A that is relatively easy to bend the panel away from jig 42
In addition, it is set to all portions such as a central portion B which is relatively rigid and easy to measure, and an end portion C which has an L-shaped bent portion and has a small degree of freedom in changing the measurement and the contact angle. For each of the measurement points A, B, and C, the contact angle of the measurement probe is set in advance, and measurement is initially performed at the contact angle. At the time of this measurement, the contact pressure in the X, Y, and Z directions applied to the measurement probe 14 is detected. When the contact pressure is measured from above as shown in FIG. When the measurement is performed from below, the force is detected as a negative force (for example, see FIG. 5).

When the measurement probe 14 moves to the measurement point fixed as shown in FIG. 4 and picks this point at a predetermined contact angle (the above-mentioned switch is clicked) (S1), The contact pressure judging section 32 reads the contact pressures detected by the torque sensor 20 in, for example, three directions of X, Y, and Z as shown in FIG. 5 (S2), and compares this with the pressure reference value (S2). S3). In this comparison, if the contact pressure was appropriate (S
4) Since the measurement is completed without bending the panel 40, the position of each arm of the three-dimensional measuring device is recognized, and the three-dimensional coordinates of the measurement point are recognized. On the other hand, when the contact pressure exceeds at least one direction as shown in FIG. 5, the measurement point data and the CAD data are read and the contact angle is changed so that the contact pressure is within the reference value. . For example, in FIG. 5, since the contact pressure in the Z-axis direction exceeds the reference value, the angle of the measuring probe 14 with respect to the Z-axis as shown in FIG. Fold it down in the direction of panel 40 so that it becomes larger. As described above, the tilting angle differs depending on how much the contact pressure exceeds the reference pressure (S5, S6).

Next, it is determined whether measurement can be performed with the contact angle changed in this way. Specifically, it is determined whether or not the measurement probe 14 and the portion supporting the same are in contact with the panel 40. In the case of contact, a non-contact area is searched from the input CAD data, and the contact angle is changed within the area (S7, S7).
8). If an angle that does not interfere is found, measure probe 1
4 is set to the angle, and the measurement point is picked again (S9). The contact pressure detected at the time of picking is input from the torque sensor 20 and compared with a pressure reference value (S1).
1) If the contact pressure is equal to or lower than the pressure reference value, the measurement has been completed without bending the panel 40. Therefore, the position of each arm of the three-dimensional measuring device is recognized, and the three-dimensional coordinates of the measurement point are obtained. Is recognized (S12). If the contact pressure is still not appropriate, then the measuring probe 14
The speed of approaching to the panel 40 is slowed down to pick a measurement point. The approach speed differs depending on how much the contact pressure exceeds the reference pressure. The approach speed is gradually reduced until the contact pressure reaches an appropriate value.

As described above, in the flowchart of FIG.
First, measure the measurement point at the set contact angle,
If the contact pressure at that time exceeds the specified pressure, change the contact angle within a range that does not cause interference, measure the measurement point again at that contact angle, and even if the contact pressure still exceeds the specified pressure If it exceeds, the approach speed is reduced and the measurement point is measured again, and the approach speed is gradually reduced until the contact pressure falls within the specified pressure.

In the above flowchart, the contact angle is changed only once. However, similar to the case of changing the approach speed, a plurality of contact angles are set so that the contact pressure is within the reference pressure within a range where no interference occurs. The number of times may be changed.

Further, in the above example, the contact angle is determined in advance for each measurement point. However, it is also possible to search for a range that does not interfere and calculate the contact angle within that range.

[0053]

As described above, the present invention has the following effects for each claim. In the invention according to claim 1 and claim 5, the measurement probe is adjusted so that the contact pressure of the measurement probe with respect to the measurement object is optimum within a range where the measurement object does not interfere with the measurement probe. Since the contact angle with respect to the measurement target is controlled, the optimal contact pressure can be set for each measurement point, and even if the measurement target is easily bent,
High-precision measurement becomes possible.

According to the second and sixth aspects of the present invention, the approach speed of the measurement probe is controlled so that the contact pressure of the measurement probe with respect to the measurement object does not exceed the reference value. The measurement can be performed with the contact pressure within the reference value for each measurement point, and high-precision measurement can be performed even if the measurement target is easily bent.

According to the third aspect of the present invention, the measuring probe is so contacted that the contact pressure of the measuring probe with the measuring object is optimized within a range where the measuring object and the measuring probe do not interfere with each other. The contact angle with respect to the measurement target is controlled, and further, the approach speed of the measurement probe is controlled so that the contact pressure of the measurement probe with respect to the measurement target does not exceed a reference value. It is possible to perform measurement at an optimum contact pressure while changing both the approach speed and the approach speed.

According to the fourth aspect of the present invention, the contact angle of the measurement probe with respect to the measurement object is controlled such that the contact pressure of the measurement probe with the measurement object is optimized. The optimum contact pressure can be set for each measurement point, and high-precision measurement can be performed even when the measurement target is easily bent.

According to the seventh aspect of the present invention, a non-interference range in which the measurement probe does not interfere with the object to be measured is calculated,
The contact angle of the measurement probe is calculated within the non-interference range, the measurement probe is brought into contact with the measurement point with the contact angle, and when the contact pressure at the measurement point exceeds the reference value, the measurement value exceeds the reference value. Change the contact angle of the measurement probe within the non-interference range, contact the measurement probe with the measurement point with the contact angle, further, if the contact pressure at the measurement point exceeds the reference value, Since the approach speed of the measurement probe to the measurement target is adjusted so as not to exceed the reference value and the measurement probe is brought into contact with the measurement point, the range of the adjustable contact pressure can be further expanded. In addition, even if the object to be measured is easily bent, it is possible to perform highly accurate measurement.

[Brief description of the drawings]

FIG. 1 is an external view of a three-dimensional measuring apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram of a measurement probe.

FIG. 3 is a block diagram showing a control system of the three-dimensional measuring device according to the present invention.

FIG. 4 is an explanatory diagram of measurement by a measurement probe.

FIG. 5 is a diagram showing an example of an actually measured contact pressure value.

FIG. 6 is a diagram illustrating an example of an angle change of a measurement probe.

FIG. 7 is a flowchart showing a specific operation of the three-dimensional measuring apparatus according to the present invention.

[Explanation of symbols]

10 measuring device, 12 body, 14 measuring probe, 16, 18 arm, 20 torque sensor,
25, 26 ... database, 40 ... panel.

Claims (7)

[Claims] In a three-dimensional measuring apparatus having a contact type measurement probe (14), when measuring a measurement target (12), the measurement target (12) and the measurement probe (14) interfere with each other. The measurement object (1
Control means (2) for controlling a contact angle of the measurement probe (14) with respect to the measurement object (12) such that a contact pressure of the measurement probe (14) with respect to 2) is optimized.
8, 30). A three-dimensional measuring device comprising: 2. A three-dimensional measuring apparatus having a contact-type measuring probe (14), when measuring a measuring object (12), a contact pressure of the measuring probe (14) against the measuring object (12). Control means (3) for controlling the approach speed of the measuring probe (14) so that the value does not exceed the reference value.
A three-dimensional measuring apparatus characterized by comprising (4). 3. A three-dimensional measuring apparatus having a contact-type measuring probe (14), when measuring a measuring object (12), the measuring object (12) and the measuring probe (14) interfere with each other. The measurement object (1
The contact angle of the measurement probe (14) with respect to the measurement object (12) is controlled such that the contact pressure of the measurement probe (14) with respect to 2) is optimized, while the contact pressure does not exceed a reference value. The measuring probe (14)
A three-dimensional measuring apparatus comprising control means (28, 30, 34) for controlling the approach speed of a vehicle. 4. A measuring probe (14) which is brought into contact with a measuring object (12) to detect the coordinates of the measuring point.
Contact pressure detecting means (20) for detecting a contact pressure of the measurement probe (14) with respect to the measurement target (12) at the measurement point, and a contact pressure by the contact pressure detection means (20) is a reference value. A control means (30) for changing a contact angle of the measurement probe (14) with respect to the measurement object (12) so that the contact pressure is within a reference value when the pressure exceeds the reference value. 3D measuring device. 5. A measurement point storage means (25) for storing measurement points on a measurement object (12), and a CAD data storage means (26) for storing CAD data of the measurement object (12). And the control means determines that the measurement probe (14) performs the measurement based on the measurement points stored in the measurement point storage means (25) and the CAD data stored in the CAD data storage means (26). The contact angle of the measurement probe (14) with respect to the measurement object (12) is changed such that the contact pressure is within a reference value within a range that does not interfere with the object (12). 3. The three-dimensional measuring device according to 2. 6. The control means further comprises means for adjusting an approach speed of the measurement probe (14) to the object to be measured (12) such that the contact pressure is within a reference value. The three-dimensional measuring device according to claim 4 or 5, wherein 7. A measurement probe (14) which is brought into contact with a measurement object (12) to detect the coordinates of the measurement point.
Measurement point storage means (25) for storing measurement points on the measurement object (12); and CA for storing CAD data of the measurement object (12).
D data storage means (26), and a measurement probe (14) for the measurement object (12)
A contact pressure detecting means (20) for detecting a contact pressure of the object; a measuring point stored in the measuring point storing means (25); and CAD data stored in the CAD data storing means (26). Calculating a non-interference range in which the measurement probe (14) does not interfere with the measurement object (12); calculating a contact angle of the measurement probe (14) within the non-interference range; First control means (30) for bringing the probe (14) into contact with the measurement point; and when the contact pressure at the measurement point exceeds a reference value, the measurement is performed within the non-interference range so as not to exceed the reference value. A second control means (30) for changing a contact angle of the probe (14) and bringing the measurement probe (14) into contact with a measurement point at the contact angle; If the contact pressure at the measurement point exceeds a reference value, the approach speed of the measurement probe (14) to the measurement object (12) is adjusted so that the measurement pressure of the measurement probe (14) does not exceed the reference value. A three-dimensional measuring apparatus, comprising: third control means (34) for bringing the point into contact with the point.