JPH06167316A - Measuring method for shape - Google Patents

Abstract

PURPOSE:To display the measuring data at each measuring position along with measuring data measured at the other measuring positions unitedly on the single three-dimensional coordinate axis even when the shape of a to-be- measured object is measured at a plurality of measuring positions by moving a three-dimensional shape measuring apparatus according to a shape measuring method using a spot projection method. CONSTITUTION:Two measuring points common to, for example, suitably selected first and second measuring positions are set on a to-be-measured object 6. A laser light 2 is cast to the measuring points from the first and second measuring positions by a measuring device 1 set with the axial core in the Z-axis direction kept vertical. The positional coordinates of the measuring points are operated in coordinate systems at the measuring positions. At the same time, a function related to the coordinate transformation is calculated. Accordingly, for instance, the data of the positional coordinate at the second measuring position is converted to the data of the positional coordinate at the first measuring position basing on the function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a three-dimensional shape of a large object to be measured such as a building structure, a car body, a hull, and a pressure vessel.

[0002]

2. Description of the Related Art Conventionally, various measuring methods such as an AM optical phase difference measuring method and a spot light projecting method have been proposed as a method for measuring a three-dimensional shape of an object to be measured without contact. Among them, as described below, the spot light projection method, which projects spot light onto the object to be measured, uses the principle of triangulation, and is generally known to be highly reliable and highly accurate. FIG. 6 shows an example of a three-dimensional shape measuring apparatus using the spot light projection method. This three-dimensional shape measuring device 51 is projected onto the object to be measured 52, and a theodolite 54 having a built-in laser light source for projecting a spot light (for example, a laser beam) 53 to the object to be measured 52 with a variable projection angle. The theodolite 56 having a built-in TV camera for picking up the spot image 55 is provided. The theodolites 54 and 56 are arranged at a predetermined distance (for example, L) from each other as schematically shown in FIG. The theodolite 54
The spot image 55 formed by the laser beam 53 projected from the image is picked up by the theodolite 56, and the image processing information of the image processing device 57 is set so as to come to a predetermined point (for example, the center point) on the image pickup surface of the theodolite 56. The theodolite 56 is rotationally controlled based on, and the spot image 55 is tracked. Then, the projection angle of the laser beam 53 when the spot image picked up comes to the center point of the theodolite 56 (for example, θ ₁ and φ ₁ shown in FIG. 7), the picking angle of the spot image picked up by the theodolite 56 ( From the values of θ ₂ , φ ₂ ) and the distance L shown in FIG.
The position coordinates (X, Y, Z) of the spot image 55 on the object to be measured 52 whose origin is 8 are obtained according to the following formula based on the principle of triangulation, and the three-dimensional shape of the object to be measured 52 is measured. It X = (L · (tan θ ₂ + tan θ ₁ )) / (2 · (tan θ ₂ −tan θ ₁ )) Y = (L · tan θ ₂ · tan θ ₁ ) / (tan θ ₂ −tan θ ₁ ) Z = (L ・ tan θ ₂・ tan θ ₁・ tan φ ₁ ) / ((tan θ ₂ −tan θ ₁ ) ・ sin θ ₁ ) = (L ・ tan θ ₂・ tan θ ₁・ tan φ ₂ ) / ((Tan θ ₂ −tan θ ₁ ) · sin θ ₂ ) The three-dimensional shape of the object to be measured 52 in this case is the position coordinate in the coordinate system with the measurement position where the device is installed as the origin. Given based on. Here, the measurement position is a concept including a projection position by the theodolite 54 and an imaging position by the theodolite 56. The above-described three-dimensional shape measuring apparatus 51 is disclosed, for example, in SICE'89, Proceedings of 28th Academic Lecture Meeting, JS7-1, P69.

[0003]

When the shape of the object to be measured is large and the shape cannot be measured from only a single measurement position, the measurement by the three-dimensional shape measuring device 51 is performed. It is necessary to change the position and perform shape measurement. When shape measurement is performed at two or more measurement positions in this way, one measurement position has its own coordinate axis. Therefore, for example, the coordinates for the first measurement position shown in FIG. It is possible to calculate the respective distances between the values ○ and ○ and the coordinate values ● and ● related to the second measurement position, but between the coordinate values ○ and ●. The three-dimensional coordinate axes on which each three-dimensional coordinate value is given are different, and it is impossible to effectively use the three-dimensional coordinate values by calculating the distance between them and other numerical analysis. As a result, there is a problem in that it is impossible to quickly and easily perform shape measurement on a large object to be measured. Therefore, the present invention was devised in view of the above circumstances, and even when the shape of an object to be measured is measured from a plurality of points by moving the measuring device, the measurement data measured at each point is not It is an object of the present invention to provide a shape measuring method capable of performing more effective shape measurement by simply displaying on one three-dimensional coordinate axis unified with measurement data measured at a plurality of points.

[0004]

In order to achieve the above-mentioned object, the main means adopted by the present invention is the gist of the invention, in which the spot light is projected from the projection position toward the object to be measured. The spot image projected on the object to be measured is imaged by the image pickup means, and the light projection angle of the spot light, the image pickup angle of the spot image, and the light projection position of the spot light and the image pickup position of the image pickup means. In a shape measuring method for calculating the position coordinates of a spot image on an object to be measured from a distance in a three-axis coordinate system, arbitrary two measurement points common to a plurality of appropriately selected image pickup positions are set, and each image pickup is performed. The two measuring points are imaged by the image pickup means set such that one axis of the three-axis coordinate system is parallel to each other at the position, and the position coordinate relating to the measuring point is obtained in the coordinate system at each image pickup position. Coordinate conversion with calculation Calculates according function, a shape measuring method according to the points to convert the data in the position coordinate data of the position coordinates in an imaging position to another imaging position based on the function.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. Here, FIG. 1 is a block diagram showing a three-dimensional shape measuring apparatus to which a shape measuring method according to an embodiment of the present invention can be applied, and FIG. 2 is an explanatory diagram showing a method for implementing the shape measuring method. 3 is an explanatory view showing a method for carrying out a shape measuring method according to another embodiment of the present invention, FIG. 4 is a block diagram of an example in which a moving function is added to the above three-dimensional shape measuring apparatus, and FIG. 5 is It is explanatory drawing which shows typically the four-division optical sensor which can be used for each said three-dimensional shape measuring device. First, an example of the shape measuring method can be applied.
A dimensional shape measuring device 1 is shown in FIG. As shown in FIG. 1, the three-dimensional shape measuring apparatus 1 includes a light source 3 including a lens (not shown) that projects a spot light (for example, a laser light) 2.
The light source 3 is attached to the rotary structure 9a that constitutes the three-dimensional shape measuring apparatus 1. A first mirror 4 is mounted on the optical axis 2a of the laser beam 2 integrally with the light source 3 in the rotary structure 9a so as to be rotatable around an axis 4a orthogonal to the optical axis 2a. . Further, on the opposite side of the first mirror 4 with the light source 3 interposed, the light source 3 in the rotary structure 9a is integrally rotated about an axis 5a parallel to the axis 4a of the first mirror 4. The second mirror 5 is freely attached. The light source 3, the first mirror 4,
The rotating structure 9 that integrally houses the second mirror 5 and the like.
The symbol a is rotatably mounted on the support structure 9b of the three-dimensional shape measuring apparatus 1 as indicated by arrow D. When the laser light 2 is projected from the light source 3, the laser light 2 is reflected by the first mirror 4 and a spot image 7 is formed on the DUT 6. The spot image 7 is reflected by the second mirror 5, and the light source 3 is reflected in the rotary structure 9a.
The light is condensed on the light condensing unit 8 including a lens and the like attached integrally with the. The spot image collected by the light collecting unit 8 is
An image is picked up on the optical sensor 8a provided in the light collecting unit 8.

The optical sensor 8a is composed of, for example, a PSD (position sensitive detector) capable of detecting the position of the spot image thus picked up. The control circuit of the three-dimensional shape measuring apparatus 1 is a microcomputer CPU
A control unit 10 including the above is configured as a center, and a first drive unit 11 that rotationally drives the first mirror 4 and a second drive unit 12 that rotationally drives the second mirror 5,
An image position detection unit 13 that processes an output signal from the optical sensor 8a, a third drive unit 14 that rotationally drives the rotary structure unit 9a, and an operation unit 15 that gives various commands to the three-dimensional shape measuring apparatus 1 are connected. Has been done. First mirror 4
The rotation angle of the first mirror 11 and the rotation angle of the second mirror 5 are the same as those of the first and second driving units 11 and 12, respectively.
It is detected by the encoder 16 and the second encoder 17 and input to the control unit 10. In addition, the rotating structure portion 9a
The rotation angle is detected by the third encoder 18 incorporated in the third drive unit 14 and input to the control unit 10. The triangulation reference distance L of the three-dimensional shape measuring apparatus 1 is determined by the axial center 4a of the first mirror 4 and the second mirror 5
Is the distance from the axis 5a of the shaft, and this distance is always constant. Here, the position of the axis 4a of the first mirror 4 corresponds to the projection position, and the position of the axis 5a of the second mirror 5 corresponds to the imaging position. These may be provided separately from the device body, but they are integrated considering the handleability of the device, and each position is conceptually handled collectively as a measurement position.
Further, the present apparatus is also provided with a level mechanism capable of vertically extending and contracting each leg portion provided on the support structure portion 9b to make the axis center of the apparatus in the Z-axis direction vertical. Subsequently, the measurement processing of the three-dimensional shape in the three-dimensional shape measuring apparatus 1 having the above configuration will be described. When the operation section 15 is operated in a predetermined manner, the third drive section 14 is driven to rotate the rotary structure section 9
a is rotated, the first mirror 4 is rotated, and the laser beam 2 is projected onto the DUT 6. As a result, the spot image 7 is projected on the DUT 6. Then, the second mirror 5 is rotated so that the spot image 7 is formed on the second mirror 5.
Is reflected by and is imaged on the optical sensor 8a. The position of the imaged spot image is detected by the optical sensor 8a, is converted into the imaged position information of the spot image via the image position detection unit 13, and is input to the control unit 10.

Based on the image formation position information, the second
When the mirror 5 is rotationally controlled and the spot image formed on the optical sensor 8a reaches a predetermined position (for example, the center point of the optical sensor 8a), the rotation angle of the second mirror 5 and the first mirror 4 The rotation angle of is calculated. Since the image pickup processing in which the spot image formed on the optical sensor 8a is at a predetermined position is only the uniaxial rotation processing of the second mirror 5 as described above, high speed processing is possible. Then, the determined rotation angle of the first mirror 4, the rotation angle of the second mirror 5, the axis 4a of the first mirror 4 and the axis 5 of the second mirror 5 are obtained.
The position coordinates of the spot image 7 on the object 6 to be measured are calculated from the distance to the object a. In this case, the above position coordinates are
This is in a coordinate system whose origin is the measurement position where the three-dimensional shape measuring apparatus 1 is installed. Hereinafter, similarly, the rotating structure 9a,
The first mirror 4 and the second mirror 5 are sequentially rotated and controlled, and the three-dimensional shape of the entire DUT 6 is obtained. Here, when the shape of the measured object 6 to be measured is large and the shape cannot be measured only from a single measurement position, the following method is performed. That is, two arbitrary measurement points common to the DUT 6 are set with respect to appropriately selected, for example, first and second measurement positions (see FIG. 2), and X, Y, Z are set at each measurement position. Of the three-axis coordinate system of, for example, Z
The above-mentioned three-dimensional shape measuring apparatus 1 adjusted by a level mechanism so that its axes are vertical (parallel to each other) is installed. The laser beam 2 is separately projected from the first measurement position and the second measurement position toward the measurement point by the three-dimensional shape measuring apparatus 1, and the position related to the measurement point in the coordinate system at each measurement position. Coordinates are calculated and a function related to coordinate conversion is calculated. Then, based on the above-mentioned function, for example, the data of the position coordinates at the second measurement position is converted into the data of the position coordinates at the first measurement position. As a specific procedure in this case, first, for example, X measured at the first measurement position is measured.
A common measurement point in the YZ 3-axis coordinate system is A (X ₁ , Y ₁ ,
Z ₁ ), B (X ₂ , Y ₂ , Z ₂ ), and the common measurement point in the xyz triaxial coordinate system measured at the second measurement position is a (x
₁ , y ₁ , z ₁ ) and b (x ₂ , y ₂ , z ₂ ).

Then, for example, the coordinate point c (x ₃ , y ₃ , z ₃ ) measured at the second measurement position is converted into the coordinate value C in the XYZ triaxial coordinate system at the first measurement position. Is the value z ₃ in the z-axis direction in the xyz _3- axis coordinate system of the coordinate point c and Z in the Z-axis direction in the XYZ _3- axis coordinate system.
₃ and the relationship is obtained as _{Z 3 = z 3 + Δz Δz} = 1/2 · (Z 1 + Z 2 -z 1 -z 2). Subsequently, the coordinate values of the measurement points A and B on the XY axis plane and the coordinate values of the measurement points a and b on the xy axis plane are used to perform the calculation on the two-dimensional plane. First, the lengths of the line segment AB and the line segment ab are averaged, and the average value L is obtained.

[Equation 1] Then, the measurement point A is fixed, and a point separated from the measurement point A by a distance L on the extension line of the line segment AB is point B '(X ₂ ',
Y ₂ ′). Similarly, the measurement point a is fixed, and the point on the extension line of the line segment ab which is separated from the measurement point a by the distance L is defined as b ′ point (x ₂ ′, y ₂ ′).
Then, for example, the angle θ formed by the line segment AB ′ and the line segment ab ′ from the determinant of 2 rows and 2 columns representing the rotational movement described below (the rotation angle of the coordinate system regarding the second measurement position relative to the coordinate system regarding the first measurement position ) Is required.

[Equation 2] Subsequently, the coordinate value (x ₃ , y ₃ ) in the xy coordinate system of the point c to be subjected to coordinate conversion and the coordinate value to be obtained in the XY coordinate system after the coordinate conversion, that is, the point C (X ₃ , Y ₃ ). The relation can be obtained by the following equation by using the value of θ obtained as described above. That is,

[Equation 3] Becomes Therefore, point c (x ₃ , y in the xyz _3- axis coordinate system
₃ , z ₃ ) and the point C (X ₃ , Y ₃ , Z ₃ ) after coordinate conversion are

[Equation 4] Becomes

Thereafter, other arbitrary points in the xyz 3-axis coordinate system are substituted into the conversion formula shown in the same manner as described above, so that each measurement data can be extremely easily converted into the XYZ 3-axis coordinate system at the first measurement position. It can be obtained as a value. That is, when converting the position coordinates in the three-dimensional space, only addition and subtraction are performed in the Z-axis direction, and X
Since it is only necessary to execute complicated arithmetic processing on the Y plane, the amount of arithmetic processing, required time, etc. can be reduced.
In the above embodiment, the case where the X-axis of the three-dimensional shape measuring apparatus 1 is installed vertically at each measurement position to perform shape measurement has been described as an example, but instead of the Z-axis, the X-axis or Y-axis is used. The axes may be parallel and the procedure described above may be performed. Subsequently, the processing procedure of the shape measuring method according to another embodiment of the present invention will be described with reference to FIG. When converting the coordinate values of x ₃ , y ₃ other than the coordinate values of z ₃ among the points c (x ₃ , y ₃ , z ₃ ) described above, L ₁ and L ₂ shown in FIG. It is performed by obtaining each value. _{Here, L 1 = [(x 3} -x 1) 2 + (y 3 -y 1) 2] 1/2 L 2 = [(x 3 -x 2) 2 + (y 3 -y 2) 2] is expressed by ^{_{1/2, (X 3, Y 3}} ) for ^{_{(X 3 -X 1) 2 +}} (Y 3 -Y 1) 2 = L 1 2 (X 3 -X 2) 2 + (Y 3 - When the simultaneous equations of Y ₂ ) ² = L ₂ ² are solved, two solutions are obtained. These two points are designated as C ₁ and C ₂ . That is, which of the points C ₁ and C ₂ is to be obtained in the XY coordinate system is determined by the following method. That is, line segment AB and line segment BC ₁
The positive and negative sign of the cross product value and the sign of the cross product value of the line segment AB and the line segment BC ₂ , and the same sign as the positive and negative sign of the cross product value of the line segment ab and the line segment bc (C ₁ or C ₂ ) By selecting, C (x ₃ , y ₃ , z ₃ ) is transformed into C after coordinate transformation.
The point of (X ₃ , Y ₃ , Z ₃ ) is determined.

By using the above method,
For example, at a plant construction site, even if it is not possible to cover the measurement because there is a place where the laser light does not hit directly from one measurement position due to the entry of each device or equipment, by providing two common measurement points , Data obtained from multiple measurement positions can be obtained as coordinate values equivalent to those obtained when measuring at a single measurement position by unifying the coordinate axes. Furthermore, when measuring the shape in a wide measurement area, even if the single measurement position exceeds the measurable range guaranteed by the measuring device, common measurement points are set and the measurement area is gradually increased. And can be obtained as data on a single coordinate axis. As described above, when the object to be measured becomes large and the distance between the three-dimensional shape measuring apparatus 1 and the object to be measured 6 becomes long and the light of the spot image 7 becomes weak, the optical sensor 8a in the above embodiment is used. In the PSD used, the output current value becomes small and the position detection resolution decreases. Therefore, this PSD is shown in FIG.
It may be replaced with the four-division optical sensor 19 schematically shown in FIG. The four-division optical sensor 19 is composed of, for example, a silicon photodiode, and its detection surface is divided into four independent surfaces 19a, 19b, 19c, and 19d as shown in FIG. Can be detected. Therefore, the position of the spot image formed on the surface of the four-division optical sensor 19 can be processed as binary information in the X and Y axis directions, and the output signal from each surface of the four-division optical sensor 19 can be processed. Can be controlled to be in a predetermined balance state (for example, all are equal). As a result, by using the four-division optical sensor 19, even if the light intensity of the spot image is weak, the position of the spot image can be detected with a constant resolution. In addition, FIG. 4 shows that the three-dimensional shape measuring apparatus 1 is mounted on a moving mechanism section 22 having wheels 20, 21 and the like.
The figure shows a configuration of the three-dimensional shape measuring apparatus 1a.
This makes it easy to move the measuring device,
It becomes easier to carry out the above-described shape measuring method.

[0011]

As described above, according to the present invention, the spot light is projected from the light projecting position toward the object to be measured, and the spot image projected on the object to be measured is imaged by the image pickup means. The position coordinate of the spot image on the object to be measured in the three-axis coordinate system from the projection angle of the spot light, the imaging angle of the spot image, and the distance between the projection position of the spot light and the imaging position of the imaging means. In the shape measuring method for calculating, two arbitrary measurement points common to a plurality of appropriately selected image pickup positions are set, and one axis of the three-axis coordinate system is parallel to each other at each image pickup position. Each of the two measurement points is imaged by the set image pickup means, the position coordinate related to the measurement point is calculated in the coordinate system at each image pickup position, and the function related to the coordinate conversion is calculated. Position coordinates at the image pickup position of Since the shape measuring method is characterized in that the data is converted into position coordinate data at one imaging position, for example, when the measuring device is moved to measure the shape of the measured object from a plurality of locations. However, the measurement data measured at each location can be displayed on a single three-dimensional coordinate axis that is unified with the measurement data measured at a plurality of other locations, and more effective shape measurement can be easily performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a three-dimensional shape measuring apparatus to which a shape measuring method according to an embodiment of the present invention can be applied.

FIG. 2 is an explanatory diagram showing a method for carrying out the shape measuring method.

FIG. 3 is an explanatory diagram showing a method for performing a shape measuring method according to another embodiment of the present invention.

FIG. 4 is a block diagram of an example in which a moving function is added to the three-dimensional shape measuring apparatus.

FIG. 5 is an explanatory diagram schematically showing a four-division optical sensor that can be used in each of the three-dimensional shape measuring devices.

FIG. 6 is a block diagram showing an example of a conventional three-dimensional shape measuring apparatus.

FIG. 7 is an explanatory diagram showing a positional relationship of each theodolite and the like of the conventional three-dimensional shape measuring apparatus.

FIG. 8 is an explanatory diagram showing a measurement situation by a conventional shape measuring method.

[Explanation of symbols]

 1, 1a ... Three-dimensional shape measuring device 2 ... Laser light (spot light) 6 ... Object to be measured 7 ... Spot image 8a ... Optical sensor 10 ... Control unit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Taizo Yoshida 4-5-22 Iwayakitamachi, Nada-ku, Kobe-shi, Hyogo Shinko Plant Construction Co., Ltd.

Claims (1)

[Claims] 1. A spot image is projected from a light projecting position toward an object to be measured and a spot image projected on the object to be measured is imaged by an image pickup means. In the shape measuring method, the position coordinates of the spot image on the object to be measured in the triaxial coordinate system are calculated from the image capturing angle of the image and the distance between the projecting position of the spot light and the image capturing position of the image capturing means. Two arbitrary measurement points common to a plurality of selected image pickup positions are set, and the two image pickup means are set so that one axis of the three-axis coordinate system is parallel to each other at each image pickup position. Each measurement point is imaged and the position coordinate related to the above measurement point is calculated in the coordinate system at each image pickup position, and the function related to coordinate conversion is calculated. Based on the above function, the position coordinates at other image pickup positions are calculated. Put the data in one imaging position A shape measuring method characterized in that it is converted into position coordinate data.