JP2007285891A - Inside surface shape measuring method and measuring apparatus using the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring the interior surface shape of an object in a noncontact manner of utilizing optical means, and to provide a measuring apparatus that uses the method. <P>SOLUTION: The interior surface shape measuring method is intended for industrial products, having internal space, such as various kinds of pipes and engine blocks and the interior of living organs, such as human oral cavity. In order to measure the cross-sectional shape of the interior to be measured 3, a disc-shaped light beam Sb is irradiated at a predetermined position of the interior to be measured; the trace of light, indicating the interior shape due to the irradiation light Sb, is imaged by an imaging sensor 2 and the image data of the trace of light are accumulated; and the distance between the reference position of an imaging system, including the imaging sensor 2 and the interior surface to be measured 3, is calculated from the accumulated image data of the trace of light, to measure the shape Ip of the interior surface to be measured 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an industrial product having an internal space such as various pipes and engine blocks, or a method for measuring the internal shape of a living organ such as the oral cavity of a human body in a non-contact manner and a measuring apparatus using the method.

  The measurement of the internal shape of various objects is in high demand in many industrial fields such as the measurement of the internal shape of engines, as well as the measurement of the internal diameter of various pipes. Moreover, there is a demand for measurement of the intraoral shape, the internal shape of the stomach, and the like even in the fields of medicine and dentistry, not limited to industrial use. Moreover, in these measurements, it is desired to perform measurement without contact with the inner surface of the object (non-contact measurement).

However, since no suitable measurement method for measuring or observing the internal shape without contact has been found so far, the method of measuring while touching the inner surface of the object or inspecting and inspecting with a fiberscope, etc. Has been adopted (see Patent Documents 1 and 2).
JP 2004-101190 A Japanese Patent Laid-Open No. 11-23237

Therefore, an object of the present invention is to provide a method for measuring the shape of the inner surface of an object in a non-contact manner using an optical means and a measuring apparatus using this method.
That is, the inside of an object is illuminated by a sheet-like light band, and a cross-section (inner surface) of the object so-called light-cut by the sheet-like light is imaged by an image sensor (hereinafter also referred to as an imaging sensor) such as a CCD. It is an object of the present invention to provide a method for measuring the inner diameter and the internal shape of the target object in a non-contact manner, and a measuring apparatus using this method.

  The configuration of the internal shape measuring method according to the present invention, which has been made for the purpose of solving the above-mentioned problems, is an object to be measured inside an industrial product having an internal space such as various pipes or engine blocks, or a living organ such as a human oral cavity. In measuring the cross-sectional shape of the inner surface of the object, a light beam is irradiated in a disk shape at a predetermined position on the inner surface to be measured, and a light trace representing the inner surface shape by the irradiated light is photographed by an imaging sensor, and The image data is accumulated, the distance between the reference position of the imaging system including the imaging sensor and the inner surface of the measurement target is calculated from the accumulated light trace image data, and the shape of the inner surface is measured. .

  Next, the configuration of the internal shape measuring device according to the present invention that can solve the above-mentioned problems is to measure the inside of a living organ such as an industrial product or an oral cavity of a human body having internal spaces such as various tubes and engine blocks. In the apparatus for measuring the inner surface shape of the target object, the cross-sectional light of the target obtained by sectioning the inner surface of the measurement target with the irradiated light beam and means for irradiating the measurement target with a light beam in a disc shape It is characterized by comprising photographing means for photographing a trace and distance calculating means for calculating the distance between the reference position of the photographing optical system and the inner surface of the measurement object from the coordinate data of the photographed light trace image.

  In the above measuring apparatus, the light trace photographing means is composed of an optical system that irradiates light from the light source in the form of a light sheet with a conical mirror or conical prism, and an imaging sensor type photographing means, and the optical system and the photographing means are moved together. After measuring the inner surface shape of the target inner surface for one cross section, the optical system and the photographing means were sequentially moved so that the inner surface shape at each moving position was measured one after another. . In this specification, light sheet-like irradiation is also referred to as disk-like irradiation of a light beam.

  In the measurement of the inner surface (cross-section) shape of an object, the present invention performs imaging without irradiating a predetermined position on the inner surface of the measurement object with a light beam in a disk shape and scanning the light beam in the circumferential direction. Instantly capture the light trace that represents it, accumulate the image data of the light trace, calculate the distance between the reference position of the imaging system and the inner surface of the measurement object from the data of the captured light trace, and measure the shape of the inner surface Therefore, the inner surface shape (including the inner diameter) of the object can be easily measured by a non-contact method.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.
In the attached drawings, FIG. 1 is a side sectional view schematically showing the measurement principle in the internal shape measurement of the present invention, FIG. 2 is a side sectional view for explaining the measurement principle, and FIG. 3 is the present invention. 4 is a side sectional view for explaining an example of the internal shape measuring apparatus, FIG. 4 is a side view for explaining the generation principle of the disc-shaped beam used in the present invention, and FIG. 5 is a measurement of the inner surface shape measured by the present invention. It is a perspective view for demonstrating an example.

  1 and 2, reference numeral 1 denotes a device (hereinafter referred to as a light source unit 1 or a light source 1) that generates a sheet-like light band (hereinafter referred to as sheet light) using laser light or the like as a light source. ) Or a conical prism eP shown in FIG. 4B, the light beam from the light source 1 is converted into a sheet-like light Sb (or disk-like light Sb) and output.

  Reference numeral 2 denotes an image sensor for capturing a linear cut surface formed by irradiating the inner surface of the object with the sheet-like light Sb, that is, a so-called light cut surface, and uses an image sensor such as a CCD camera or a digital camera. To do. The sheet-like light Sb forms a cross-sectional line by a light sheet (band), that is, a light cut surface, in the interior 3 (or the inner surface 3) of the measurement object.

  A case will be described in which this light cut surface is captured (captured) by the imaging sensor (hereinafter referred to as camera 2), and coordinates such as points A and B (see FIGS. 1 and 2) on the target inner surface are calculated.

  In FIG. 1, if the sheet-like light Sb emitted from the light source unit 1 toward the upper side of the target inner surface 3 is perpendicular to the axis G, it hits the point A on the target inner surface 3 and one point A is captured by the camera 2. The angle φ expected at that time is obtained. As a result, if the distance between the camera 2 and the light source unit 1 is set to 1, the distance QA = r from the point Q in FIG. 1 can be calculated.

  Here, it is assumed that the representative position of the light source unit 1 is represented by P and the representative position of the camera 2 is represented by C, and the distance between the axes of the camera 2 and the light source unit 1 is Δz apart. Here, when the accuracy of the optical element (for example, the conical mirror eM or the prism eP) of the light source unit 1 is not sufficient or the adjustment of the optical system is not strict, the emitted light is not perpendicular to the optical axis G. The light is emitted at an angle θ, and the light reaches point B instead of point A. As a result, the point B is measured instead of the point A. That is, instead of the point A as shown in FIG. 1, the point B separated from the point A by Δr and Δl is measured.

  In this case, the following relational expressions (1) and (2) hold from FIG.

Here, the angle φ is an angle at which the point B is viewed from the camera 2. Originally, it is desired to measure the point A at the angle φ ₀ from the camera 2, but actually the point B is measured.
Further, the angle θ is known, and the distance 1 (QC) between the camera 2 and the light source unit 1 and the optical axis distance Δz ((PQ) are also known as set values. However, the angle θ and the optical axis distance Δz are also known. Therefore, the difference Δr, Δl between the point A and the point B occurs, so the distance r + Δr from the camera axis of the point B measured in this case is obtained.
This can be easily calculated by the following equation (3) from the above equations (1) and (2).

  This indicates that the angle θ which is the beam emission angle of the light source unit 1 has a great influence, and since the relationship between the distance Δr and the distance Δl is unknown, when θ increases, a point B away from the point A is measured. It shows that it will end. On the other hand, as can be easily seen from FIG. 1, since there is a relation of the expression (4), the following expressions (5) and (6) are obtained from the expressions (3) and (1).

  As can be seen from equation (3), if angle θ is 0, equation (4) is obtained, and this can be easily understood from FIG.

  Here, if the angle θ can be reduced, the equations (5) and (6) can be approximated by the following equations (7) and (8).

  This means that if the angle θ is 0, that is, if the light beam is emitted at right angles to the optical axis G, the distances Δl and Δr can be regarded as 0, and an accurate inner surface diameter can be measured. Yes.

  From the above, for practical application, it is important to make the beam emission angle θ as small as possible so as not to cause the distance Δl and the distance Δr. If the arrangement is made such that the distance Δz between the optical axis of the camera 2 and the optical axis of the light source unit 1 is also reduced, the measuring device can be easily inserted even when the inner diameter is small. It can also prevent the surface from being vignetted and unobservable. In this case, the optical system of the measuring apparatus is as shown in FIG.

  The case of FIG. 2 corresponds to the case where the distance Δz is small in the above equation, and if the error angle θ of the light emitted from the light source unit 1 can also be reduced, the distance to the point A, that is, the inner diameter and the internal shape can be obtained by equation (4). It means that you can know.

  Actually, it is desirable that the light from the light source unit 1 is emitted as perpendicular to the optical axis G as possible, and the optical axes of the light source unit 1 and the camera 2 are also aligned. This is because the distance Δl and the distance Δr are 0 at this time, so that the point A can be specified accurately.

  In the present invention, as shown in FIG. 3, if the measuring device is configured and the coordinate data of a plurality of points on the inner surface 3 light-cut by the light beam (sheet-like light Sb) is calculated one after another, the light cutting line is obtained. The upper inner shape is obtained. Therefore, if the camera 2 and the light source unit 1 are moved, the cross-sectional shape of the inner surface 3 can be obtained one after another.

Regarding the light source unit 1 that irradiates the sheet-like light Sb, several ring beam light sources are known. The principle of the light source unit 1 is shown in FIGS. 4 (a) and 4 (b).
4 (a) and 4 (b) show the principle of the light source unit 1 for generating a ring beam. In either case, a conical mirror eM or prism eP is used, and the light beam is reflected by the apex of the conical portion and spreads in a ring shape (disc shape). FIG. 4 (a) utilizes the fact that the beam spreads in a disk shape when the light beam hits the apex of the conical mirror. In FIG. 4B, a prism having a conical gap is used, and the light spreads in a disk shape (ring shape). In the case of FIG. 4 (b), the same reflective mirror as in FIG. 4 (a) is obtained by applying a reflective coating to the surface of the conical gap.

  FIG. 5 shows an example of the actual measurement by the method of the present invention. That is, as shown in FIG. 3, by moving the light source unit 1 and the camera unit 2 in the direction of the arrow in the figure and moving in the depth direction of the inner surface, the measured inner surface shape Ip ( It is possible to obtain the cut surface shape Ip one after another. As a result, the inner shape and inner diameter of the object can be measured.

  The present invention is as described above, and in measuring the cross-sectional shape of the inner surface of an object such as an industrial product having an internal space such as various tubes and engine blocks and a living organ such as the oral cavity of a human body, A predetermined position on the inner surface to be measured is irradiated with a light beam in a disk shape, a light trace representing the inner shape of the irradiated light is photographed by an imaging sensor, and the image data of the light trace is accumulated. Since the distance between the reference position of the photographic system and the inner surface of the object to be measured is calculated and the shape of the inner surface is measured, the inner surface (cross-section) shape of various objects is not contacted, not limited to the industrial and consumer fields. Therefore, it is very useful industrially.

The sectional side view typically expressed in order to explain the measurement principle of the present invention in the internal shape measurement of the present invention. The side sectional view for demonstrating the measurement principle of this invention like FIG. The side sectional view for explaining an example of the internal shape measuring device of the present invention. The side view for demonstrating the generation principle of the disk shaped beam used by this invention. The perspective view for demonstrating the example of a measurement of the inner surface shape measured by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source part 2 Camera 3 Inner surface of measuring object
Sb sheet light
Ip Measured inner surface shape G Optical axis

Claims (3)

  When measuring the cross-sectional shape of the inner surface of an industrial product that has internal space such as various tubes and engine blocks, and the inside of a living organ such as the oral cavity of a human body, a light beam is applied to a predetermined position on the inner surface to be measured. Irradiation in a disk shape, the light trace representing the inner surface shape by the irradiated light is photographed by the imaging sensor, the image data of the light trace is accumulated, and the reference of the photographing system including the imaging sensor from the accumulated light trace image data An inner surface shape measuring method, comprising: calculating a distance between a position and an inner surface to be measured to measure a shape of the inner surface.   In a device that measures the inner surface shape of an industrial product that has internal space such as various pipes and engine blocks, and the inside of a living organ such as the oral cavity of a human body, a light beam is spread in a disk shape at a predetermined position of the measurement target Irradiating means, photographing means for photographing the cross-sectional light trace of the object obtained by sectioning the inner surface of the measurement object with the irradiated light beam, and a reference position of the photographing optical system from the coordinate data of the photographed light trace image And a distance calculating means for calculating the distance between the inner surface of the measuring object and the inner surface of the measuring object. The light trace photographing means includes an optical system that irradiates light from a light source in a light sheet shape with a conical mirror or a conical prism, and an imaging sensor type photographing means, and the optical system and the photographing means are moved together. Further, after the inner surface shape of the target inner surface is measured for one cross section, the optical system and the photographing means are sequentially moved, and the inner surface shape at each moving position is measured one after another. The inner surface shape measuring apparatus as described.

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