JP2001241928A - Shape measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measuring apparatus capable of accurately measuring the three-dimensional shape of an object to be measured, irrespective of the position or attitude of a measuring head. SOLUTION: The shape measuring apparatus comprises a measuring head 10 freely movable by a measuring person for measuring the object 100, to be measured markers 14-17 disposed on a plurality of faces of the measuring head 10, stereo cameras 21, 22 for imaging the markers 14-17 from specified positions, and controller 30 for obtaining the three-dimensional shape of the object 100, based on the outputs of the measuring head 10 and the stereo cameras 21, 22, and according to the attitude of the measuring head 10, the markers 14-17 are switched over to select some markers for use in measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring device for measuring a three-dimensional shape of an object by freely moving a measuring head by a user.

[0002]

2. Description of the Related Art Conventionally, there has been known an active stereo type shape measuring apparatus which irradiates spot light or slit light to an object to be measured and restores a shape from a position of an optical image observed on a surface.

As an active stereo shape measuring device, there is one that scans slit light with a rotating mirror.
In a shape measuring device provided with such a scanning mechanism,
Although the shape of the surface of the measured object observed from the measuring instrument can be measured, the shape of the entire measured object cannot be measured.

On the other hand, in order to measure the shape of the whole object to be measured, a rotary stage is used to move the object to be measured in 360.
An active stereo shape measuring device for observing from all around the degree has been developed. However, when the object to be measured has a complicated shape, there is an area that cannot be observed even with the use of the rotary stage, so that the shape of the entire object to be measured cannot be measured.

In view of the above, there has been proposed a shape measuring apparatus capable of measuring the entire shape of an object having a complicated shape by holding the measuring head and moving the measuring head around the object to perform measurement. ing.

[0006]

However, in this shape measuring apparatus, in order to measure the position and orientation of the measuring head, a marker arranged on the upper surface of the measuring head is used.
Since it is necessary to take an image with two cameras from above, depending on the position and orientation of the measurement head, the marker may enter the blind spot of the camera and measurement may not be possible.

Accordingly, an object of the present invention is to provide a shape measuring apparatus capable of accurately measuring a three-dimensional shape of an object to be measured irrespective of the position and posture of a measuring head.

[0008]

A shape measuring apparatus according to the present invention comprises a measuring head which is freely moved by a measurer to measure an object to be measured, a marker disposed on the measuring head, and a predetermined marker. A measuring head imaging means for imaging from a position of the measuring head, and a calculating means for calculating a three-dimensional shape of the object to be measured based on an output of the measuring head and the measuring head imaging means, wherein Marker switching means for arranging on a plurality of surfaces and switching a marker to be used for measurement from the markers is provided.

In such a configuration, the coordinates of the object measured by the measuring head are converted into coordinates on a predetermined coordinate axis based on the coordinates of the marker imaged by the measuring head imaging means. You. Then, by performing this measurement at a plurality of locations on the measured object, a three-dimensional shape of the measured object is obtained. At this time, the marker used for conversion is a marker provided on a plurality of surfaces of the measurement head, which is at a position suitable for measurement, that is, a marker at a position imaged by the measurement head imaging unit. You.

The marker switching means switches a marker used for measurement for each surface from among markers arranged on a plurality of surfaces of the measuring head.

With such a configuration, the markers used for measurement are switched for each surface of the measurement head.

Further, the apparatus further includes an inclination detecting means for detecting an inclination of the measuring head, and the marker switching means is controlled based on a detection result of the inclination detecting means.

With this configuration, a marker imaged by the measuring head image pickup means is automatically obtained in accordance with the inclination of the measuring head, and the obtained marker is used for measurement. Preferably, among the plurality of surfaces of the measuring head,
For the measurement head imaging means, the marker arranged on the plane closest to the vertical may be used for measurement. For example, when the measurement head imaging means is composed of a plurality of video cameras, each video camera The marker arranged on the plane where the average of the angles with respect to is closest to the vertical may be used for the measurement.

The measuring head measures the position of a measuring point on an object to be measured by an active stereo measuring method.

The calculating means obtains the coordinates of the measurement point on the object to be measured in the coordinate system of the center of the measuring head using the output of the measuring head, and obtains the world from the position of the marker obtained using the output of the imaging means. Finds information about the position of the measuring head in the coordinate system, and converts the coordinates of the measuring point on the DUT in the coordinate system of the center of the measuring head into coordinates in the world coordinate system based on the obtained information about the position of the measuring head. By doing so, the three-dimensional shape of the measured object is obtained.

[0016] The measuring head imaging means includes one or a plurality of video cameras for imaging the measuring head.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.

FIG. 1 shows a schematic configuration of a shape measuring apparatus according to an embodiment of the present invention.

The device under test 100 is placed on a table 201. The support 201 is attached to the base 201. A horizontal bar 203 is attached to an upper part of the support column 202.

The shape measuring apparatus is composed of a measuring head 10 which can be freely moved by a measurer, stereo cameras 21 and 22 attached to both ends of a horizontal bar 203, and a personal computer which controls them and performs various calculations. And a control device 30. The imaging lens of each of the stereo cameras 21 and 22 has a marker 14 shown in FIG.
A band-pass filter 23 for selectively transmitting the frequency band of light emitted by the light-emitting devices 17 to 17 is attached.

FIGS. 2 and 3 show a schematic configuration of the measuring head 10.

The measuring head 10 includes a casing 11 having a rectangular parallelepiped shape and having a front opening, and a casing 11 housed in the casing 11.
Markers 14 to 12 comprising a CCD camera 12, a slit light source 13, a tilt angle sensor 18, and six LED light sources provided on each of four surfaces of a casing 11 surrounding them.
17 are provided. As the slit light source 13, a semiconductor laser is used.

The tilt angle sensor 18 detects the tilt angle in the direction of rotation about a vertical line passing through the center O of the surface of the casing 11 of the measuring head 10 where no marker is disposed. Here, the angle with respect to the vertical direction is detected based on the posture of the measuring head 10 in which the surface on which the marker 14 is arranged is horizontal in the casing 11.

Six LED light sources 1 constituting the marker 14
In order to specify the direction of the measuring head 10, the positions 4 a to 14 f are not symmetrical with respect to a point but are symmetrical with respect to the center line of the measuring head 10. Here, the casing 1
5 are arranged on the upper surface of the LED light source 14b to 14f so as to form a rectangle.
4a is arranged. Similarly, for each of the remaining markers 15 to 17, each 5 of the 6 LED light sources is also used.
The points are arranged so as to form a rectangle, and the remaining LED light sources are arranged at the center of gravity of the five points.

In order to measure the position and orientation of the measuring head 10 in a three-dimensional space, it is sufficient to use at least three LED light sources as markers, but it is necessary to use four or more LED light sources. As a result, the measurement accuracy of the position and orientation of the measuring head 10 is improved in a least square manner.

FIG. 4 shows the measurement principle of the shape measuring device.

The coordinates of a measurement point A are measured using the measurement head 10 which can be freely moved by a measurer.
The measured coordinates are represented by coordinates (x, y, z) in the coordinate system of the center of the measuring head. This coordinate system corresponds to the measuring head 10
Is a coordinate system that moves with the movement of.

On the other hand, the shape of the DUT 100 is represented by a fixed coordinate system, and this coordinate system is called world coordinates. The coordinates of the measurement point measured by the measurement head 10 in the world coordinate system are (X, Y, Z). DUT 10
Since the shape of 0 needs to be described in the world coordinate system,
The coordinates (x, y, z) of the measurement point A measured by the measurement head 10 in the coordinate system of the center of the measurement head are converted to the world coordinate system. This conversion is performed using the rotation matrix R representing the movement of the measuring head 10 and the translation vector t based on the following equation 1.

[0029]

(Equation 1)

Therefore, by obtaining the position and orientation of the measuring head 10 in the world coordinate system as a rotation matrix R and a translation vector t, the coordinates (x, y, z) in the coordinate system of the center of the measuring head can be calculated in the world coordinate system. Can be converted to

The above-described processing is performed while moving the measuring head 10 around the measured object 100, and as a set of coordinates (X, Y, Z) of the measuring points obtained in each case in the world coordinate system, is measured. 100 shapes are described.

The shape measurement by this shape measuring device is executed according to the following processing procedure.

First step: A marker to be used for measurement is determined from the markers 14 to 17 using the inclination angle sensor 18 arranged in the measuring head 10.

Second step: Using the measuring head 10,
The coordinates of the measurement point on the measured object in the coordinate system of the center of the measurement head are obtained.

Third step: Information on the position of the measuring head 10 in the world coordinate system, that is, the rotation matrix R and the translation vector t representing the movement of the measuring head 10 in the world coordinate system are selected in step 1. Measuring head 10
The upper marker is obtained by measuring a stereo image with the stereo cameras 21 and 22.

Fourth step: Based on the rotation matrix R and the translation vector t obtained in the third step, the coordinates of the measuring point on the object to be measured in the coordinate system of the measuring head center obtained in the second step are Convert to world coordinates.

By performing these series of steps at a plurality of locations on the object to be measured, the shape of the object to be measured is measured.

Hereinafter, each of these steps will be described. [1] Description of First Step FIG. 5 is a flowchart showing the processing order of the first step. The processing described below is performed by the control device 30 based on the output of the tilt angle sensor 18 arranged in the measuring head 10.

In the first step, first, the inclination angle sensor 1
8 (step S01), the measuring head 1
A tilt angle with respect to the vertical direction of 0 is detected, and a marker to be turned on is determined based on the obtained tilt angle. That is, when the inclination angle is 45 degrees to 135 degrees, the marker 15 is selected (steps S02 and S03), and the inclination angle is 13 degrees.
When the angle is 5 degrees to 225 degrees, the marker 16 is selected (steps S04 and S05). When the inclination angle is 225 degrees to 315 degrees, the marker 17 is selected (steps S06 and S0).
7) When the inclination angle is 315 degrees to 45 degrees, the marker 14
Is selected (step S08). Then, a current is supplied only to the LED light sources constituting the selected marker, and the LED light sources are turned on.

Thus, the marker arranged on the surface closest to the horizontal in the casing 11 is turned on. For this reason, the lit marker is not hidden by the blind spots of the stereo cameras 21 and 22 located above the marker, and a good captured image of the marker can be obtained. [2] Description of Second Step FIG. 5 shows a method of measuring the position of a measuring point by the measuring head 10. Hereinafter, a case will be described in which the marker 14 is selected as a marker used for measurement.

The coordinate system of the center of the measuring head is such that the optical center of the CCD camera 12 is the origin, the optical axis direction is the z axis, and the CCD
This is a coordinate system in which the horizontal direction of the camera 12 is the x axis and the vertical direction of the CCD camera 12 is the y axis. The image plane S of the CCD camera 12 is located at a focal distance f from the origin. That is, the image plane S is a plane parallel to the xy plane and z = f.

The position measuring method itself by the measuring head 10 is a known measuring method called a light section method. A predetermined point on a line on the surface of the DUT 100 on which the slit light from the slit light source 13 is irradiated is referred to as a measurement point A.

Let the coordinates of the center of the measuring head of the measuring point A be (x,
y, z), the coordinates of the observation point A ′ corresponding to the measurement point A on the image plane S are (xs, ys, f), and the equation of the plane representing the slit light is ax + by + cz + d = 0.
F at the coordinates (xs, ys, f) of the observation point A 'is C
Known as the focal length of the CD camera 12, (xs,
ys) is obtained from the pixel position of the slit light observed on the image plane.

The equation of the plane representing the slit light is obtained in advance by calibration of the measuring head 10. Therefore, (x, y, z) is obtained by solving a simultaneous equation represented by the following equation 2 with x, y, z, and α as unknowns.

[0045]

(Equation 2)

Such processing is performed by the control device 30 based on the output of the CCD camera 12. [3] Description of Third Step In the third step, first, the stereo cameras 21 and 22 measure the world coordinates of the marker used for the measurement determined in the first step. This position measurement method
Since it is well known as the stereo method, its description is omitted. Each LED light source 14a-1 constituting the marker 14
The calculation of the world coordinates of 4f is performed by the stereo cameras 21 and 2
2 is performed by the control device 30 based on the output of the control unit 2.

Next, a rotation matrix R representing the movement of the measuring head 10 and a translation vector t are obtained. That is, the coordinates of the center of the measurement head of each of the LED light sources 14a to 14f which are known in advance are (xi, xi, xi). Where i is
1, 2,... The world coordinates of each of the LED light sources 14a to 14f measured by the stereo cameras 21 and 22 are defined as (Xi, Yi, Zi). Measuring head 10
Is obtained as a matrix R and a vector t satisfying the following equation (3). The calculation of the rotation matrix R and the translation vector t is performed by the control device 30.

[0048]

(Equation 3)

[4] Description of Fourth Step Rotation matrix R and translation vector t obtained in the third step
And coordinates (x, y, z) of the center of the measurement head at the measurement point measured by the measurement head 10 using Equation 1 above.
Is converted into world coordinates (X, Y, Z), thereby obtaining world coordinates of the measurement point. This coordinate conversion is also performed by the control device 30.

In order to obtain the rotation matrix R and the translation vector t representing the movement of the measuring head 10, the required minimum number of LED light sources constituting the marker 14 is three (a plane is determined by three points). In order to increase the accuracy, six are provided here.

As described above, according to the present embodiment, the markers are arranged on a plurality of surfaces of the casing 11 of the measuring head 10 and the markers to be used for the measurement are switched according to the attitude of the measuring head 10. With this configuration, the marker does not enter the blind spot of the stereo cameras 21 and 22. Thereby, the three-dimensional shape of the object to be measured can be obtained regardless of the position and orientation of the measuring head 10, so that the accuracy and reliability of the measuring device itself can be improved.

Further, according to the present embodiment, since the markers provided on the plurality of surfaces of the casing 11 of the measuring head 10 are controlled to be switched for each surface, the markers used for the measurement are on the same plane. It will be in. This allows
Not only can the position of the marker be easily obtained, but also the identification of the LED light source constituting the marker can be easily performed.

In the present embodiment, the marker used for measurement is controlled to be automatically switched based on the output of the inclination angle sensor 18, so that the measurer is conscious of the posture of the measuring head 10. The measurement can be freely performed without using it, and thus the usability can be improved.

In the above embodiment, the rotation vector R representing the movement of the measuring head 10 in the world coordinate system is used.
In order to determine the translation vector t, the markers are imaged by the two cameras (stereo cameras) 21 and 22, and the LEDs constituting each marker are formed based on the captured images.
Although the world coordinates of the light source are calculated, each marker may be imaged by one camera, and the world coordinates of the LED light source constituting each marker may be calculated based on the captured image.

Further, a sheet having a predetermined pattern is fixed on a table 201 or the like, and a camera for picking up an image of the sheet is attached to the measuring head. Based on an image picked up by the camera, the measuring head in the world coordinate system is used. A rotation vector R and a translation vector t representing ten movements may be obtained.

The measuring head 10 may be different from the above-described embodiment as long as it measures the position of the measuring point on the object to be measured by an active stereo measuring method. For example, a spot light source may be used instead of the slit light source 13. Alternatively, the position of the measurement point (the coordinates of the center of the measurement head) may be measured by two CCD cameras.

In the above embodiment, the case where the stereo cameras 21 and 22 are arranged above the device under test 100 has been described. It may be arranged. In this case, even if the position of the measurement head 10 with respect to the DUT 100 is the same, the marker that is turned on differs depending on the position of the stereo cameras 21 and 22.

In the present embodiment, the marker used for measurement is determined based on the output of the tilt angle sensor 18. However, not only the attitude of the measuring head 10 based on the output of the tilt angle sensor 18 but also the measurement is performed. A marker to be used for measurement may be determined in consideration of the approximate position of the head 10, or the marker may be manually switched.

Further, in the above-described embodiment, the case has been described where the markers are provided on four surfaces surrounding the front opening out of the five surfaces of the measuring head 10, but the marker is provided on any two or more surfaces. May be.

[0060]

According to the present invention, the markers are arranged on a plurality of surfaces of the measuring head, and the marker to be used for the measurement is switched according to the posture of the measuring head. It does not enter the blind spot of the head imaging means. Thus, the three-dimensional shape of the object to be measured can be obtained regardless of the position and the posture of the measuring head, so that the accuracy and reliability of the measuring device itself can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a schematic configuration of a shape measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a front view showing a schematic configuration of a measuring head in the shape measuring apparatus of FIG.

FIG. 3 is a perspective view showing a schematic configuration of a measuring head in the shape measuring device of FIG. 1;

FIG. 4 is an explanatory diagram illustrating a measurement principle.

FIG. 5 is a flowchart illustrating a processing procedure of a first step.

FIG. 6 is an explanatory diagram illustrating a method for measuring the position of a measurement point using a measurement head.

[Explanation of symbols]

 10: Measuring head 12: CCD camera 13: Slit light source 14 to 17: Marker 18: Inclination angle sensor 21: Stereo camera 22: Stereo camera

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Kamosono 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term (reference) in Sanyo Electric Co., Ltd. 2F065 AA04 AA17 AA19 AA37 AA53 BB05 BB29 DD03 FF05 FF07 FF61 FF65 GG06 GG07 GG12 GG16 HH04 HH05 JJ03 JJ05 JJ07 JJ26 LL21 LL28 MM06 QQ21 QQ29 QQ32 QQ38

Claims (6)

[Claims] Claims 1. An operator is free to move a subject,
A measuring head for measuring the object to be measured, a marker disposed on the measuring head, a measuring head imaging unit for imaging the marker from a predetermined position, and the measurement head based on outputs from the measuring head and the measurement head imaging unit. Claims: 1. A shape measuring device comprising: a calculating means for obtaining a three-dimensional shape of an object to be measured; a marker switching means for arranging the markers on a plurality of surfaces of the measuring head and switching a marker to be used for measurement from the markers A shape measuring device comprising: 2. The shape measuring apparatus according to claim 1, wherein the marker switching means switches a marker used for measurement for each surface from markers arranged on a plurality of surfaces of the measuring head. 3. The shape measuring apparatus according to claim 1, further comprising an inclination detecting unit that detects an inclination of the measuring head, wherein the marker switching unit is controlled based on a detection result of the inclination detecting unit. 4. The shape measuring apparatus according to claim 1, wherein said measuring head measures a position of a measuring point on an object to be measured by an active stereo measuring method. 5. The calculation means obtains the coordinates of a measurement point on the object to be measured in a coordinate system of the measurement head center using the output of the measurement head, and obtains the coordinates obtained using the output of the imaging means. Finding information on the position of the measurement head in the world coordinate system from the position of the marker,
Based on the obtained information on the position of the measurement head, the coordinates of the measurement point on the measurement object in the coordinate system of the measurement head center are converted into the coordinates of the world coordinate system, so that the three-dimensional 5. The shape measuring device according to claim 1, wherein the shape is determined. 6. The shape measuring apparatus according to claim 1, wherein said measuring head imaging means includes one or a plurality of video cameras for imaging said measuring head.