JPH05272934A - Shape measuring method - Google Patents

Abstract

PURPOSE:To display the measured data, which are measured at each measuring position on the single three-dimensional coordinate-axis system, wherein the measured data are integrated with the measured data, which are measured at a plurality of other measuring positions, even if a measuring device is moved and the shape of a material to be measured is measured at a plurality of measuring positions with regard to the shape measuring method with the three- dimensional shape measuring device using a spot projection method. CONSTITUTION:With regard to, e.g. first and second measuring positions, which are appropriately selected, at least three common measuring points (e.g. the apexes of a defined triangle) are provided on a material to be measured. The laser light is individually projected from each of measuring devices, which are provided at the first measuring positions (a) and the second measuring position (b), respectively, to the measuring points. The position coordinates associated with the measuring point in the coordinate system at each measuring position are operated. The function associated with coordinate conversion is computed. The data of the position coordinates, e.g. at the second measuring position, are converted into the data of the position coordinates at the first measuring position.

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 the three-dimensional shape of a large object to be measured such as a building structure, car body, hull, pressure vessel and the like.

[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. The three-dimensional shape measuring apparatus 51 includes a theodolite 54 that projects a spot light (for example, a laser light) 53 on a measured object 52 with a variable projection angle.
A TV camera 56 for picking up a spot image 55 projected on the object to be measured 52 is provided. The theodolite 54 and the TV camera 56 are arranged at a predetermined distance (for example, L) from each other as schematically shown in FIG. Laser light 53 emitted from the theodolite 54
The spot image 55 formed by the TV camera 56
The TV camera 56 is rotated and controlled based on the image processing information of the image processing device 57 so as to come to a predetermined point (for example, the center point) on the image pickup surface of the TV camera 56.
The spot image 55 is tracked. The projection angle of the laser light 53 when the imaged spot image reaches the center point of the TV camera 56 (eg, θ ₁ and φ ₁ shown in FIG. 7), T
A spot image 55 on the object to be measured 52 having the midpoint 58 of the distance L as the origin, based on the image pickup angle (θ ₂ , φ ₂ shown in the figure) of the spot image picked up by the V camera 56 and the value of the distance L. The position coordinates (X, Y, Z) of are measured in accordance with the following formula, for example, based on the principle of triangulation, and the three-dimensional shape of the measured object 52 is measured. 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 a coordinate system with the measurement position where the device is installed as the origin. Given based on. 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]

By the way, when the shape of the object to be measured is large and the shape cannot be measured from only a single measuring 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 measurement device is moved to measure the shape of the object to be measured from a plurality of measurement positions, the measurement data measured at each measurement position is obtained. It is an object of the present invention to provide a shape measuring method capable of performing more effective shape measurement so that it can be displayed on one three-dimensional coordinate axis unified with measurement data measured at a plurality of other measurement positions.

[0004]

In order to achieve the above-mentioned object, the main means adopted by the present invention is to provide a spot light from a predetermined measuring position toward an object to be measured. The spot image projected on the object to be measured is imaged on the imaging surface, the projection angle of the spot light, the imaging angle of the spot image, and the distance between the spot where the spot light is projected and the imaging surface. In the shape measuring method for calculating the position coordinates of the spot image on the measured object in the coordinate system with this measured position as the origin, at least three points common to the measured object with respect to a plurality of appropriately selected measuring positions. The measurement point is set, and spot light is separately projected toward the measurement point from one measurement position and the other measurement position, and the position coordinates related to the measurement point are calculated in the coordinate system at each measurement position. And functions related to coordinate transformation Calculated, a shape measuring method according to the points to convert the data in the position coordinate data of the position coordinates in one measurement position to another measurement 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 of the nature 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. , FIG. 3 is an explanatory view showing a measurement situation by the shape measuring method, FIG. 4 is a block diagram of an example in which a moving function is added to the three-dimensional shape measuring apparatus, and FIG. 5 is used in each of the three-dimensional shape measuring apparatus. It is explanatory drawing which shows the possible four-division optical sensor typically. First, FIG. 1 shows a three-dimensional shape measuring apparatus 1 to which an example of the shape measuring method can be applied. 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 beam) 2, and the light source 3 is the above-mentioned three.
It is attached to the rotary structure portion 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. In addition, the first mirror 4 with the light source 3 interposed therebetween.
A second mirror 5 is attached to the opposite side of the above so as to be rotatable around an axis 5a parallel to the axis 4a of the first mirror 4 integrally with the light source in the rotary structure 9a. The rotating structure 9a, which integrally houses the light source 3, the first mirror 4, the second mirror 5, etc., is rotatable on the supporting structure 9b of the three-dimensional shape measuring apparatus 1 as shown by an arrow D. It is installed. 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 is condensed on a condensing unit 8 including a lens or the like mounted integrally with the light source 3 in the rotating structure 9. The spot image collected by the light collecting unit 8 is imaged on the optical sensor 8 a 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 driver 11 and the second driver 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. Subsequently, the three-dimensional shape measuring apparatus 1 according to the above configuration
The three-dimensional shape measurement process in 3 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 9a, and further the first mirror 4 is moved.
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, the spot image 7 is reflected by the second mirror 5, and the optical sensor 8a
Imaged above. The position of the spot image formed is
The image position detection unit 1 detected by the optical sensor 8a.
It is converted into the image forming position information of the spot image via 3 and 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, at least three measurement points (for example, defined triangular vertices) common to the DUT 6 are set with respect to appropriately selected, for example, first and second measurement positions (see FIG. 3). The laser beam 2 is separately projected from the three-dimensional shape measuring device 1 installed at the first measurement position and the second measurement position toward the measurement point, and the measurement is performed in the coordinate system at each measurement position. The position coordinates related to the point are calculated, and the function related to the 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.

In this case, the two
Triangles are originally the same triangle, but due to measurement error
There is a possibility that the appearance may be slightly off. Therefore,
The error can be corrected by using such a method.
Be done. As shown in Fig. 2, for example, the measurement is performed at the first measurement position.
Specified X₁, Y₁, Z₁Common measurement points on three-dimensional coordinate axes
A, B, C and X measured at the second measurement position₂，
Y₂, Z₂The common measurement points a, b, and c on the three-dimensional coordinate axes
When considering a triangle with three points as vertices, coordinate system
The coordinate transformation for one is that the two triangles are substantially the same.
Can be obtained from the condition that So point A,
Plane F including B and C₁And a plane F including points a, b and c₂
The two sides are set, and the average is calculated from the lengths of side AB and side ab.
Value L₁Is calculated. Similarly, from side BC and side bc to the flat
Average L₂, The average value L from the side AC and the side ac₃Is that
Is calculated. And, of the points A, B, C
Expected to have the smallest measurement error due to the short distance from the fixed position
The point (eg, A) to be selected is selected. Continuing, plane F
₁Points A to L above₁Away from the point on the extension of line segment AB
It is designated as point B '. Similarly, plane F₂Points a to L above₁Is
A point on the extension of the line segment ab away from each other is defined as a point b ′. Change
On the plane F₁Points A to L above₃Away from point B '
₂Is defined as a point C ', and the plane F₂From point a above
L₃Away from point b '₂Point apart by point c '
To be done. Plane F obtained as described above₁Upper triangle
AB'C 'and plane F₂The upper triangle ab'c 'is geometric
Is logically congruent. Therefore, X₂, Y₂, Z₂Three-dimensional seat
Each point of coordinate points a and b'c 'on the standard axis is X.₁, Y₁, Z₁
Coordinate points A, B ', C'on the three-dimensional coordinate axes
By performing coordinate transformation using the relationship corresponding to
₂, Y₂, Z₂X on any point on the 3D coordinate axis₁，
Y₁, Z₁It is converted as a point on the three-dimensional coordinate axis.

By using the above method,
For example, at a plant construction site, even if it is not possible to cover all of 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 equipment or facility, by providing three common measurement points The 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.

[0010]

As described above, according to the present invention, spot light is projected from a predetermined measurement position toward an object to be measured, and a spot image projected on the object to be measured is imaged on an image pickup surface. From the projection angle of the spot light, the imaging angle of the spot image, and the distance between the point where the spot light is projected and the imaging surface, a coordinate system having this measurement position of the spot image on the object to be measured as the origin. In the shape measuring method for calculating the position coordinate in, at least three measurement points common to the object to be measured are set for a plurality of appropriately selected measurement positions, and one measurement position is set toward this measurement point. Spot light is separately projected from other measurement positions to calculate the position coordinates related to the above measurement points in the coordinate system at each measurement position, and the function related to coordinate conversion is calculated, and other measurement is performed based on the above function. The position coordinate data at the position Since the shape measurement method is characterized by converting the position coordinate data at the measurement positions, even if the measurement device is moved to measure the shape of the measured object from a plurality of measurement positions, The measurement data measured at the measurement position can be displayed on a single three-dimensional coordinate axis that is unified with the measurement data measured at other measurement positions, 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 view showing a measurement situation by the shape measuring method.

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 between a theodolite and a TV camera 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 the front page (72) Inventor Yoshiro Nishimoto 5-18-7 Takenodai, Nishi-ku, Kobe (72) Inventor Taizo Yoshida 983-1 Fujie, Akashi-shi

Claims (1)

[Claims] 1. A spot light is projected from a predetermined measurement position toward an object to be measured, and a spot image projected on the object to be measured is imaged on an image pickup surface. Shape measurement that calculates the position coordinates in the coordinate system with this measurement position of the spot image on the DUT as the origin from the imaging angle of the spot image and the distance between the point where the spot light is projected and the imaging surface. In the method, at least three common measurement points are set on the object to be measured with respect to a plurality of appropriately selected measurement positions, and spot lights are separately directed toward the measurement points from one measurement position and another measurement position. By projecting light, the position coordinate related to the above measurement point is calculated in the coordinate system at each measurement position, and the function related to coordinate conversion is calculated, and the data of the position coordinates at other measurement positions is calculated based on the above function. Position seat at one measurement position Shape measurement method is characterized in that so as to convert the data.