JP2009002823A - Three-dimensional shape measuring system and three-dimensional shape measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-dimensional shape measuring system and a three-dimensional shape measuring method allowing a three-dimensional shape of a measuring object to be measured with high accuracy even if it is moved at a high speed. <P>SOLUTION: This three-dimensional shape measuring system is equipped with a light source that emits light toward a tire with the amount of light cyclically varied, four light receiving parts for receiving reflective light from the tire, an arithmetic processing part for finding three-dimensional coordinates by calculating the distance to each of measuring object positions on a tire surface for each of the object positions based on image data obtained through measurement by the respective receiving parts, and an image display part for displaying the shape of the tire based on the found three-dimensional coordinates. The processing part is used for setting four partial waveforms 29A-29D different in phase from each other for together forming a one-cycle waveform out of reflected light amounts from the respective object positions, calculating a phase lag at each of the object positions through a phase shift method by using the partial waveforms 29A-29D, and calculating the distances from the receiving positions to the respective object positions based on the calculated phase lags. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a three-dimensional shape measurement system and a three-dimensional shape measurement method, and more specifically, a three-dimensional shape measurement system that is most suitable for measuring the outer shape of a rolling tire, and 3 The present invention relates to a dimension shape measuring method.

  A moire method is known as a method for measuring the three-dimensional shape of a stationary object. On the other hand, when measuring the three-dimensional shape of a moving object, for example, a rotating tire, this moire method cannot be used.

  As a countermeasure, in Patent Document 1, a grid-shaped optical mark is projected on the tire surface, and the tire is rotated to form a rolling tire. It is disclosed to shoot with. In this way, the method of photographing with three-dimensional coordinates has an advantage that the photographing apparatus can be easily set in a short time.

  However, in Patent Document 1, it is necessary to photograph the projected light mark simultaneously with at least two photographing devices. For this reason, when the light mark is projected on the blind spot of one or both of the photographing devices due to unevenness on the tire surface, measurement is impossible, and there is a possibility that a part that cannot be measured is partially generated. This also applies to general measurement objects other than tires.

In Patent Document 2, light (increasing modulated light) whose light intensity increases with time changes is projected onto a subject, and the reflected light is photographed with a photographing device. Further, the light intensity decreases with time changes. The projected light (decreasing modulated light) is projected onto the subject, the reflected light is photographed by the same photographing device, the difference between the two reflected light is obtained, and the distance from the photographing device to the subject is calculated, thereby obtaining a three-dimensional view of the subject. Determining the shape is disclosed. In this method, since it is not necessary to use a plurality of photographing apparatuses, it is difficult to cause the blind spots as described above. However, this method cannot accurately measure when the subject is moving or when light (for example, light from indoor lighting) is projected on the subject from elsewhere.
JP 2007-085836 A Latest optical 3D measurement (published by Asakura Shoten)

  In consideration of the above facts, the present invention provides a three-dimensional shape measurement system and a three-dimensional shape measurement method capable of measuring a three-dimensional shape of a measurement object with high accuracy even when the measurement object is moved at high speed. It is an issue to provide.

  According to the first aspect of the present invention, at least one light source that emits light while periodically changing the amount of light toward the measurement object and at least one light receiving unit that can capture the reflected light from the measurement object by the light source. The light receiving / calculation processing means for calculating the distance to each measurement target position on the surface for each measurement target position to obtain the three-dimensional coordinates, and the three-dimensional coordinates obtained by the light reception / calculation processing means. Display means for displaying a three-dimensional shape of at least a part of the measurement object based on the light receiving / calculation processing means, wherein the light reception / calculation processing means has at least three types of phases and ½ period or less with respect to the light quantity period variation of the light source. The phase lag at each measurement target position is calculated based on the difference between three or more images obtained there, and the distance from the light receiving unit to each measurement target position is calculated based on the phase delay. To do And features.

  In the first aspect of the invention, the light receiving / arithmetic processing means receives the reflected light, which is emitted from the light source and reflected by the measurement object, at the light receiving unit. Since the amount of light from the light source varies periodically, this reflected light also varies periodically.

The light receiving / arithmetic processing means exposes the light receiving unit at least once in three or more phases and ½ cycle or less with respect to the light amount period variation of the light source. Then, the phase delay at each measurement target position is calculated based on the difference between the three or more types of images obtained there. Furthermore, the distance from the light receiving unit to each measurement target position is calculated based on this phase delay.
The shape of the measurement object can be obtained from the three-dimensional coordinates thus obtained.

  As described above, in the first aspect of the present invention, the light receiving unit is exposed at least once with the reflected light from the measurement object in the phase of 3 or more and 1/2 cycle or less with respect to the light amount cycle variation of the light source. Thus, the three-dimensional shape of the tire can be obtained. Therefore, it is possible to measure the three-dimensional shape of the measurement object by photographing for a very short time (for example, several tens of nanoseconds).

  In addition, it is possible to provide a single photographing device including one or a plurality of light receiving units in the light receiving / arithmetic processing means, and it is possible to have a configuration that does not require a plurality of photographing devices to be installed. is there. Therefore, it is not necessary to deal with images captured by a plurality of image capturing apparatuses, so that data processing is simple, and thus high-resolution 3D moving images can be output immediately.

  Furthermore, by providing one imaging device in the light receiving / arithmetic processing means as described above, the blind spot of the imaging device due to unevenness of the surface of the measurement object is hardly generated. Therefore, since the measurement object parts that cannot be measured are greatly reduced, measurement can be performed with high accuracy.

The invention according to claim 2 is characterized in that the light reception / calculation processing means calculates the phase delay by a phase shift method.
Thereby, the calculation of the phase delay is easy.

The invention according to claim 3 is characterized in that the light reception / calculation processing means performs processing for canceling components other than the reflected light from the light source from the measurement object by a difference between different images obtained. To do.
As a result, the time required for data processing is further reduced.

The invention according to claim 4 is characterized in that the light reception / calculation processing means performs a process of adjusting a difference in reflectance at each measurement target position of the measurement target according to a ratio of different images obtained. To do.
As a result, the time required for data processing is further reduced.

The invention described in claim 5 is characterized in that the light receiving section is exposure controlled by a microchannel plate.
Accordingly, the phase region of the waveform received by the light receiving unit can be set by opening and closing the microchannel plate, and it is not necessary to provide a light opening and closing mechanism in the light receiving unit itself.

The invention described in claim 6 is characterized in that a plurality of the light receiving parts are provided, and the reflected light from the measurement object by the light source is evenly distributed to each light receiving part by a beam splitter.
The number of installed beam splitters may be one or plural.

Note that an optical filter that attenuates light (external light) other than light from the light source may be provided in the light receiving unit. In this case, a non-attenuating wavelength region is usually set in the optical filter in accordance with the wavelength of light from the light source.
Moreover, you may make it the structure which amplifies light quantity with a microchannel plate.
Further, the light source may be formed in a ring shape, and the light source and the light receiving unit may be arranged coaxially. This makes it possible to make the optical path lengths substantially the same between the emitted light and the reflected light.
Moreover, it is good also as a structure which arrange | positions a retroreflection object (glass bead etc.) in a measuring object, and increases the reflected light from a light source.

  The invention according to claim 7 projects toward the measurement object while periodically changing the amount of light, and reflects the light from the measurement object by the light source, and at least one light receiving unit receives the light source. Exposure is performed at least once with a phase of 3 or more and 1/2 cycle or less with respect to fluctuations in the amount of light, and the phase lag at each measurement target position is calculated based on the difference between the three or more types of images obtained there. Based on this, the distance from the light receiving unit to each measurement target position is calculated.

  From the viewpoint of improving the measurement accuracy by shortening the light quantity fluctuation period, it is preferable to arrange the light source and the light receiving unit as close to each other as possible.

  As described above, in the invention according to claim 7, the reflected light with the light amount periodically fluctuated, and at the light receiving portion, at least once in three or more phases and ½ cycle or less with respect to the light amount period variation of the light source. Exposure. Then, the phase delay at each measurement target position is calculated based on the difference between the three or more types of images obtained there. Furthermore, the distance from the light receiving unit to each measurement target position is calculated based on this phase delay.

  Therefore, according to the invention described in claim 6, as in the invention described in claim 1, it is possible to measure the three-dimensional shape of the measurement object by photographing for a very short time (for example, several tens of nanoseconds).

  In addition, measurement can be performed with one imaging device including one or a plurality of light receiving units, and a measurement method that does not require measurement by installing imaging devices over a plurality of units can be provided. . Therefore, it is not necessary to deal with images captured by a plurality of image capturing apparatuses, so that data processing is simple, and thus high-resolution 3D moving images can be output immediately.

  Furthermore, by providing one imaging device in the light receiving / arithmetic processing means as described above, the blind spot of the imaging device due to unevenness of the surface of the measurement object is hardly generated. Therefore, since the measurement object parts that cannot be measured are greatly reduced, measurement can be performed with high accuracy.

  Furthermore, by measuring with one imaging device in this way, the blind spot of the imaging device due to the unevenness of the tire surface or the like is significantly less likely to occur. Therefore, since the measurement object parts that cannot be measured are greatly reduced, measurement can be performed with high accuracy.

The invention according to claim 8 is characterized in that the phase delay is calculated by the phase shift method.
Thereby, the calculation of the phase delay is easy.

The invention described in claim 9 is characterized in that when the reflected light from the measurement object is received by the light receiving unit, it is received in the same phase over two cycles or more.
Thereby, an effect equivalent to amplifying the received waveform can be obtained. This is particularly effective when the light intensity (light quantity) of the reflected light is small.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the three-dimensional shape measuring system and the three-dimensional shape measuring method which can measure the three-dimensional shape of a measuring object with high precision, even if a measuring object is moved at high speed. .

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals, and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. As shown in FIG. 1, the three-dimensional shape measurement system 10 according to this embodiment includes a light source 14 that emits light toward a rolling pneumatic tire 12 to be measured, and reflected light from the pneumatic tire 12. An imaging device (CCD camera) 16 that receives light, an arithmetic processing unit 18 that calculates the three-dimensional coordinates of the pneumatic tire 12 by calculating the image data captured by the imaging device 16, and enters the air based on the three-dimensional coordinates And an image display unit 20 for displaying a three-dimensional image of the tire 12. In the present embodiment, the optical path length until the light emitted from the light source 14 reaches the pneumatic tire 12 and the optical path length until the reflected light reflected by the pneumatic tire 12 reaches the imaging device 16 are: The distance d from the imaging device 16 to the pneumatic tire 12 is the same.

  The light source 14 is configured to emit light while changing the light amount in a short cycle. FIG. 3 shows a waveform 25 of the emitted light 24 (see FIG. 1) from the light source 14 and a waveform 29 of the reflected light 28 (see FIG. 1) reflected on the tire surface and taken into the imaging device 16. Due to the optical path length from the light source 14 to the imaging device 16, a time lag (Δt in FIG. 3) is generated between the waveform 25 and the waveform 29.

  Further, the photographing device 16 distributes the reflected light 28 reflected by the pneumatic tire 12 and transmitted through the optical filter and the photographing lens of the photographing device 16 to four light beams with equal light intensity as shown in FIG. Have beam splitters 30, 32, 34. Furthermore, the imaging device 16 includes four light receiving units 38A to 38D that receive reflected light (distributed light) emitted from the beam splitters 30, 32, and 34, respectively. The distances from the light receiving portions 38A to 38D to the pneumatic tire 12 are all the same. The light receiving portions 38A to 38D are, for example, CCD image sensors having 1024 × 768 pixels. In addition, the imaging device 16 includes MCPs (microchannel plates) 40A to 40D arranged on the incident sides of the four light receiving units 38A to 38D.

  The arithmetic processing unit 18 calculates the distance from the light receiving unit 38 for each measurement target position on the tire surface as follows, and obtains the three-dimensional coordinates of the tire surface.

As described above, the beam splitters 30, 32, and 34 distribute the reflected light 28 incident on the imaging device 16 into the four reflected lights 28A to 28D. MCP40A, as shown in FIG. 4 (A), opening the shutter only during a period from time _{T 0} so that the phase angle θ passes the reflected light 28A of 0~180 ° (0~Π radians) to _{T 2.} As a result, the partial waveform 29A is photographed by the light receiving unit 38A. MCP40B, as shown in FIG. 4 (B), opening the shutter only during a period from time _{T 2,} so that the phase angle θ passes the reflected light 28B of 180~360 ° (Π~2Π radians) to _{T 4.} As a result, the partial waveform 29B is photographed by the light receiving unit 38B. MCP40C, as shown in FIG. 4 (C), from time _{T -1} such that the phase angle θ passes reflected light 28C of -90~90 ° (-Π / 2~Π / 2 radians) to _{T 1} Open the shutter only during. As a result, the partial waveform 29C is photographed by the light receiving unit 38C. MCP40D, as shown in FIG. 4 (D), only from time _{T 1} so that the phase angle θ passes reflected light 28D of 90~270 ° (Π / 2~3Π / 2 radians) to _{T 3} Open the shutter. As a result, the partial waveform 29D is photographed by the light receiving unit 38D.

Hereinafter, the total received light amount of the reflected light 28A by the light receiving unit 38A is I ₀ , the total received light amount of the reflected light 28B by the light receiving unit 38B is I ₂ , the total received light amount of the reflected light 28C by the light receiving unit 38C is I ₋₁ , and the light receiving unit. continuing with the _{I 1} the total amount of received reflected light 28D by 38D.

  In the present embodiment, the light intensity (light quantity) of the emitted light 24 is set to a period in which a cosine wave is drawn as shown in FIG. Here, in this specification, the cosine wave refers to a waveform represented by the following expression.

ここで、Ｉは受光した反射光の光量（出力強度）、ｆは周波数、ｔは経過時間、θは位相角、ｂは主として外光などの他の光の光量、をそれぞれ示す。なお、空気入りタイヤ１２の反射率はａで反映されている。この式から判るように、位相を９０°（Π／２ラジアン）ずらすようにｂの値を設定すると上式は正弦波を示す式となる。従って、本明細書で余弦波とは正弦波をも含む定義となる。

Here, I represents the light amount (output intensity) of the received reflected light, f represents the frequency, t represents the elapsed time, θ represents the phase angle, and b represents the light amount of other light such as external light. The reflectance of the pneumatic tire 12 is reflected by a. As can be seen from this equation, when the value of b is set so that the phase is shifted by 90 ° (Π / 2 radians), the above equation becomes an equation representing a sine wave. Therefore, in this specification, the cosine wave is defined to include a sine wave.

Then, by using the phase shift method, the phase lag Tanθ at each measurement target position is calculated by the following equation by measuring I at four points while shifting the phase, that is, by obtaining I _{−1 to} I _2. Is done.

上式から判るように、このように位相シフト法で位相解析をすることによって、位相遅れＴａｎθをＩ_−１ 〜Ｉ_２ のみによって求めることができ、ａやｂの影響を、すなわち反射率や外光の影響を受けない値として算出することができる。

As can be seen from the above equation, by performing the phase analysis by the phase shift method in this way, the phase delay Tanθ can be obtained only by I _{−1 to} I ₂ , and the influence of a and b, that is, reflectance and external It can be calculated as a value that is not affected by light.

  In the present embodiment, the distance d between the photographing device 16 and the pneumatic tire 12 is set to a half wavelength of the waveform 25 (that is, a half wavelength of the waveform 29).

Further, when the light emission amount by the light source (LED) 14 is P, a fluctuation component of time delay due to the distance d is added to the light reception amount l (x, y) for each photographing pixel of the light receiving units 38A to 38D, and p, l (X, y) is obtained by the following equation. Note that x means the horizontal coordinate of the photographed image, and y means the vertical coordinate of the photographed image.

Here, p, L ₀ (x, y), and L ₁ (x, y) are a light emission amount, a background (a light amount other than the light source 14), and a fluctuation amount, respectively.

Further, T _m (m = −1 to 4) is obtained by the following equation.

ここで、Δｔは上述したように波形２５と波形２９との間に生じたタイムラグを示す。

Here, Δt represents a time lag generated between the waveform 25 and the waveform 29 as described above.

I _{−1 to} I ₂ are calculated by the following equations.

“I ₀ -I ₂ ” and “I ₋₁ -I ₁ ” used in Equation ₂ are calculated as follows. By calculating the difference in this way, the influence of background light from the background is offset.

Therefore, (I ₀ −I ₂ ) / (I ₋₁ −I ₁ ) is calculated as follows.

Therefore, Δt, which is a time lag, can be obtained as follows.

  The distance d can be obtained based on this Δt (s) and the speed of light c (m / s). When the distance d is equal to or less than the half wavelength of the waveform 29, the distance d is obtained by calculating (C / 2) × Δt. Then, by obtaining the distance d for each measurement target position, the three-dimensional coordinates of each measurement target position can be obtained, and based on this, a three-dimensional image of the pneumatic tire 12 can be displayed on the image display unit 20. it can.

  As described above, in the present embodiment, the exposure time of the light receiving unit 38 can be completed in one cycle of the waveform 29 (for example, tens of millionths of a second). Therefore, even if the pneumatic tire 12 rolls at high speed, the three-dimensional shape can be obtained with high accuracy. Further, since the measurement is performed with the reflection time, the influence of the pattern to be measured is reduced. Even when the light amount fluctuation is small, it is possible to obtain a three-dimensional shape with high accuracy by increasing the total amount of received light by repeatedly receiving light in two cycles and three cycles.

  Furthermore, in this embodiment, there is only one photographing device 16 to be installed, and there is no need to install over a plurality of devices. Therefore, since the blind spots of the imaging device due to the unevenness of the tire surface are much less likely to occur, the area where measurement is impossible is greatly reduced, and moreover, it is necessary to deal with images taken with multiple imaging devices Since there is no data processing, data processing is simple.

In addition, the brightness | luminance (light emission amount) of the reflected light 28 is calculated | required by the sum total of I < _-1 > -I < ₂ > as shown by the following formula | equation.

The reflectance R is obtained by the following formula.

なお、数１６、数１７は、それぞれ、数１４、数１５と同じ式で示される。 L ₀ (x, y) and L ₁ (x, y) are obtained by the following equations.

Expressions 16 and 17 are represented by the same expressions as Expressions 14 and 15, respectively.

Using R, L ₀ (x, y), L ₁ (x, y), etc., it is possible to confirm the reliability of the calculated value such as the distance d.

[Second Embodiment]
Next, a second embodiment will be described. As illustrated in FIG. 5, the three-dimensional shape measurement system 50 according to the present embodiment includes a light source 54 that emits light toward the pneumatic tire 12 to be measured, and an imaging device that receives reflected light from the pneumatic tire 12 ( CCD camera) 56, an arithmetic processing unit 58 for calculating the three-dimensional coordinates of the pneumatic tire 12 by calculating the image data taken by the photographing device 56, and the three-dimensional of the pneumatic tire 12 based on the three-dimensional coordinates And an image display unit 20 for displaying an image.

  As the light source 54, a ring type LED arranged coaxially on the outer periphery of the photographing lens of the photographing device 56 is provided. FIG. 7 shows a waveform 65 of the emitted light 64 from the light source 54 and a waveform 69 of the reflected light 68 reflected on the tire surface and taken into the photographing device 56. The waveform 65 and the waveform 69 have the same shape as that shown in FIG. 3, and a time lag (Δt in FIG. 7) is generated between the waveform 65 and the waveform 69 due to the optical path length from the light source 54 to the imaging device 56. .

  The imaging device 56 is different in configuration and operation from the imaging device 16 used in the first embodiment. The imaging device 56 includes a beam splitter 70 that distributes the reflected light 68 reflected by the pneumatic tire 12 and transmitted through the optical filter and the imaging lens of the imaging device 56 into three as shown in FIG. For example, a cube-type cross prism is used as the beam splitter 70.

  Furthermore, the imaging device 56 includes three light receiving units 78A to 78C that receive reflected light (distributed light) emitted from the beam splitter 70, respectively. The distances from the light receiving portions 78A to 78C to the pneumatic tire 12 are all the same. The light receiving unit 78 has the same function as the light receiving unit 38. In addition, the imaging device 56 includes MCPs (microchannel plates) 80A to 80C arranged on the incident sides of the three light receiving units 78A to 78C. The MCP 80 has a function equivalent to that of the MCP 40.

  The arithmetic processing unit 58 calculates the distance from the light receiving unit 78 for each measurement target position on the tire surface as follows, and obtains the three-dimensional coordinates of the tire surface.

  The beam splitter 70 distributes the reflected light 68 incident on the imaging device 56 into three reflected lights 68. The MCP 80A opens and closes the shutter so that the reflected light 68A (FIG. 8A) having a phase angle θ of 0 to 180 ° (0 to radians) passes. As a result, the partial waveform 69A is photographed by the light receiving unit 78A. The MCP 80B opens and closes the shutter so that the reflected light 68B (FIG. 8B) having a phase angle θ of 90 to 270 ° (Π / 2 to 3Π / 2 radians) passes. The MCP 80C opens and closes the shutter so that the reflected light 68C (FIG. 8C) having a phase angle θ of 180 to 360 ° (Π to 2Π radians) passes through. The partial waveform 69C is photographed, and therefore, in each measured reflected light, both end portions of each phase angle range overlap each other.

The phase delay Tanθ at each measurement target position is calculated by the following equation.

The principle from which this equation is derived will be described below.
Assuming that the light receiving unit 78 is composed of four light receiving units, 0 to 180 ° (0 to Π radians), 180 to 360 ° (Π to 2 Π radians), and −90 to 90 ° (−Π / 2). It is assumed that reflected light is received by each of the four light receiving portions in four phase angle ranges of ˜Π / 2 radians) and 90 to 270 ° (Π / 2 to 3Π / 2 radians). The time during which the MCP opens the shutter is from time T _{0 to} T ₂ at _{0 to} 180 °, from time T _{2 to} T ₄ at 180 to 360 °, and from time T _{−1 at} −90 to 90 °. It is assumed that it is between time T _{1 and} T ₃ at 90 to 270 ° between ˜T ₁ . In this case, the received light amounts of the four light receiving units can be I ₀ , I ₁ , I ₋₁ , and I ₁ . Here, I ₀ , I ₁ , I ₋₁ , and I ₁ are represented by the following equations.

なお、数１９〜数２２は、それぞれ、数６〜数９と同じ式で示される。

Equations 19 to 22 are represented by the same equations as Equations 6 to 9, respectively.

なお、数２３、数２４は、それぞれ、数１０、数１１と同じ式で示される。 “I ₀ -I ₂ ” and “I ₋₁ -I ₁ ” are calculated as follows. By calculating the difference in this way, the influence of background light from the background is offset.

Note that Equations 23 and 24 are represented by the same equations as Equations 10 and 11, respectively.

“I ₀ + I ₂ ” and “I ₋₁ + I ₁ ” are calculated as follows. The background is extracted by calculating the sum in this way.

If I- ₁ is eliminated from these equations and the cosine component is obtained, the following equation is obtained.

なお、数２８は数１２と同じ式で示される。 The phase angle θ is obtained by the following expression from the sine component and the cosine component of the amount of fluctuation of the light amount.

Equation 28 is expressed by the same equation as Equation 12.

なお、数２９は数１３と同じ式で示される。 Therefore, the time lag Δt (x, y) is obtained by the following equation.

Equation 29 is expressed by the same equation as Equation 13.

  As described in the first embodiment, the three-dimensional coordinates of each measurement target position can be obtained by obtaining the distance d based on the time lag Δt (x, y) for each measurement target position. A three-dimensional image of the pneumatic tire 12 can be displayed on the image display unit 20. Therefore, according to the present embodiment, even if the number of the light receiving portions 78 is set to three and the number of partial waveforms forming the waveform 69 is three instead of four, the three-dimensional shape of the pneumatic tire 12 that rolls at high speed is increased. It can be measured with accuracy.

  In the present embodiment, as the light source 54, a ring type LED arranged coaxially on the outer periphery of the photographing lens of the photographing device 56 is provided. Therefore, the outgoing light 64 and the reflected light 68 are almost identical in optical path length, and can be projected from the same direction as the optical axis of the photographing device 56.

If Δt (x, y) is handled as a complex number as in the following formula, it is convenient because one cycle can be handled continuously with one formula.

なお、数３２は数１５と同じ式で示される。 Further, the amount of fluctuation of the light quantity is obtained by the sum of squares as follows.

Equation 32 is expressed by the same equation as Equation 15.

なお、数３４は数１４と同じ式で示される。 The amount of background external light can be obtained by the following equation.

Note that Equation 34 is expressed by the same equation as Equation 14.

<Example of the second embodiment>
In the present embodiment, the light source 54 is an LED that can change the amount of light at a short cycle of 50 MHz. This is convenient for extracting the influence at the round trip distance (2 × d) due to reflection. In this embodiment, the distance d is set to 3.0 m. As a result, Δt is 20 ns when the speed of light c is 3.0 × 10 ⁵ km / s. Table 1 shows the relationship between the distance d and the frequency f when the frequency f of the emitted light 64 from the light source 54 is changed as a parameter. In this embodiment, the frequency f is set so that the wavelength of the outgoing light 64 is 2d.

  An LED that emits near infrared light is used as the LED. As a result, the sensitivity of the photodiode constituting the photographic pixel can be increased, and in addition, adverse effects such as fluorescent lamps can be reduced by combination with a near-infrared transmission optical filter.

  The column of “three partial waveforms and three light receiving units” in FIG. 9 indicates that measurement is performed by shifting the phase angle so that both ends of the phase angle range overlap each other. The light receiving unit 78A has a time range 82A for measuring the partial waveform 69A, the light receiving unit 78B has a time range 82B for measuring the partial waveform 69B, and the light receiving unit 78C has a time range 82C for measuring the partial waveform 69C. Open and expose.

  In the second cycle, the partial waveforms may be measured by exposing the light receiving units 78A to 78C in the time ranges 82A to C in the same manner. Thereby, measurement accuracy can be improved. This is particularly effective when the change in the amount of reflected light 68 is small.

  Further, as shown in the column of “three partial waveforms and one light receiving unit” in FIG. 9, one light receiving unit 78 </ b> A reflects reflected light having a phase angle of 0 to 180 ° in the first cycle and phase in the second cycle. The reflected light having an angle of 90 to 270 ° may be measured, and the reflected light having a phase angle of 180 to 360 ° may be measured in the third period. Thereby, the installation number of a light-receiving part can be made into one.

[Third Embodiment]
Next, a third embodiment will be described. In the present embodiment, the three-dimensional shape measurement system 10 described in the first embodiment is used, and four waveforms in which both ends of the phase angle range overlap each other are measured by the light receiving units 38A to 38D.

  Thus, by measuring so that the both ends of a phase angle range may mutually overlap, a measurement precision improves more compared with 1st Embodiment.

<Example of the third embodiment>
In the column of “four partial waveforms and four light receiving units” in FIG. 9, the measurement is performed by shifting the phase angle so that both ends of the phase angle range overlap each other. Exposure is performed by opening the shutters of the MCPs 40A to D in the time range 92A in the light receiving unit 38A, in the time range 92B in the light receiving unit 38B, in the time range 92C in the light receiving unit 38C, and in the time range 92D in the light receiving unit 38D.

  As in the example of the second embodiment, the partial waveforms 92A to 92D may be measured by the light receiving units 38A to 38D in the same manner in the second period.

  Further, as shown in the column of “four partial waveforms and two light receiving parts” in FIG. 9, in the first and second periods, the light receiving part 78A is exposed in the time range 92A and the light receiving part 78B in the time range 92B. In the third and fourth cycles, the light receiving unit 78A may be exposed in the time range 92C and the light receiving unit 78B may be exposed in the time range 92D. Thereby, the number of installation of a light-receiving part can be halved to two.

In this case, the same principle, as shown in FIG. 10, by exposing the light receiving portion 38A while measuring I ₁ by exposing the light receiving portion 38B in the time range 102B at the end portion E of one waveform in a time range 102A I ₀ is measured, and the light receiving portion 38A is exposed in the time range 102C at the start portion F of the waveform continuous to this waveform to measure I ₂ and the light receiving portion 38B is exposed in the time range 102D to obtain I _{−. 1} may be measured, and the three-dimensional coordinates of the pneumatic tire 12 may be obtained based on these measurement results. Thus, the three-dimensional coordinates of the pneumatic tire 12 can be obtained by exposing the light receiving portions 38A and 38B in a very short time. For example, even if the period of the waveform 69 is T _L = 1/30 seconds, the time for exposing the end portion E and the start end portion F can be set to Δt _s = 1/10000 seconds. Further, as shown in FIG. 10, it may be exposed for more than once when determining the I ₀ ~I _2.

Further, as shown in the column of “four partial waveforms and one light receiving unit” in FIG. 9, only the light receiving unit 38A is used, and I ₀ is obtained by performing exposure in the time range 92A in the first cycle, and the second cycle. in search of I ₁ by exposing a time range 92B, obtains the I ₂ by the third periods eyes to be exposed in a time range 92C, the determination of the I _-1 by the four th cycle of exposing a time range 92D You may go. Thereby, the installation number of a light-receiving part can be made into one.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. For example, in these embodiments, the emitted light emitted from the light source has been described as light having a cycle in which a sine wave or cosine wave is drawn. However, the present invention is not limited to this, and the cycle in which the triangular waveform 106 is drawn as shown in FIG. It may be light, or may be light having a period for drawing the pulse waveform 108 as shown in FIG.

  It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

It is a mimetic diagram showing the three-dimensional shape measuring system concerning a 1st embodiment. It is a schematic diagram which shows dividing the reflected light from a tire with a beam splitter, and measuring with each light-receiving part with the imaging device of the three-dimensional shape measuring system which concerns on 1st Embodiment. In 1st Embodiment, it is a graph which shows that the phase difference has arisen with the emitted light from a light source, and the reflected light from a tire. FIGS. 4A to 4D are graphs each showing a partial waveform received by each light receiving unit in the first embodiment. It is a schematic diagram which shows the three-dimensional shape measuring system which concerns on 2nd Embodiment. It is a schematic diagram which shows dividing the reflected light from a tire with a beam splitter, and measuring with each light-receiving part with the imaging device of the three-dimensional shape measuring system which concerns on 2nd Embodiment. In 2nd Embodiment, it is a graph which shows that the phase difference has arisen with the emitted light from a light source, and the reflected light from a tire. FIGS. 8A to 8C are graphs showing partial waveforms received by the respective light receiving portions in the second embodiment. In the Example of 3rd Embodiment, it is explanatory drawing which shows the phase range of the partial waveform which a light-receiving part measures. It is a modification of the Example of 3rd Embodiment, and is explanatory drawing which shows the phase range of the partial waveform which a light-receiving part measures. In 1st Embodiment-3rd Embodiment, it is a graph which shows the modification of the waveform of the emitted light which a light source emits. In 1st Embodiment-3rd Embodiment, it is a graph which shows the modification of the waveform of the emitted light which a light source emits.

Explanation of symbols

10 Three-dimensional shape measurement system 14 Light source 16 Imaging device (light reception / arithmetic processing means)
18 Arithmetic processing device (light receiving / arithmetic processing means)
28A to D Reflected light 30 Beam splitter 32 Beam splitter 34 Beam splitter 38A to D Light receiving portions 40A to D MCP (microchannel plate)
50 Three-dimensional shape measurement system 54 Light source 56 Imaging device (light receiving / arithmetic processing means)
58 Arithmetic processing device (light receiving / arithmetic processing means)
68A-C Reflected light 70 Beam splitter 78A-C Light receiving part 80A-C MCP (microchannel plate)
d Distance Tanθ Phase lag

Claims (9)

A light source that emits light while periodically varying the amount of light toward the measurement object;
A light receiving unit that has at least one light receiving unit capable of photographing reflected light from the measurement target by the light source, and calculates a distance to each measurement target position on the surface for each measurement target position to obtain a three-dimensional coordinate. -Arithmetic processing means;
Display means for displaying at least a part of the three-dimensional shape of the measurement object based on the three-dimensional coordinates obtained by the light receiving / calculating means;
With
The light reception / calculation processing means exposes at least once in a phase of 3 or more and 1/2 cycle or less with respect to a light amount cycle variation of the light source,
The phase lag at each measurement target position is calculated based on the difference between the three or more types of images obtained there,
A three-dimensional shape measurement system, wherein a distance from the light receiving unit to each measurement target position is calculated based on the phase delay.   The three-dimensional shape measurement system according to claim 1, wherein the light receiving / calculation processing means calculates the phase delay by a phase shift method.   The said light-receiving / calculation processing means performs the process which cancels components other than the reflected light by the said light source from the said measurement object by the difference of the different image obtained. 3D shape measurement system.   4. The method according to claim 1, wherein the light reception / calculation processing unit performs a process of adjusting a difference in reflectance at each measurement target position of the measurement target according to a ratio of different images obtained. The three-dimensional shape measurement system according to claim 1.   The three-dimensional shape measurement system according to any one of claims 1 to 4, wherein the light receiving unit is exposure-controlled by a microchannel plate. A plurality of the light receiving parts are provided,
6. The three-dimensional shape measurement system according to claim 5, wherein the reflected light from the measurement object by the light source is evenly distributed to each light receiving unit by a beam splitter. Aiming at the measurement object while projecting while changing the amount of light periodically,
The light reflected from the measurement object by the light source is exposed to at least one light-receiving unit at least once in a half period or less and a half period or less with respect to a light amount period variation of the light source,
The phase lag at each measurement target position is calculated based on the difference between the three or more types of images obtained there,
A method for measuring a three-dimensional shape, comprising calculating a distance from the light receiving unit to each measurement target position based on the phase delay.   The three-dimensional shape measuring method according to claim 7, wherein the phase delay is calculated by a phase shift method.   9. The three-dimensional shape measuring method according to claim 7, wherein when the reflected light from the measurement object is received by the light receiving unit, the light is received in the same phase over two periods or more.

Images