JP5971028B2 - Rotation angle measuring device and method - Google Patents

Description

  The present invention relates to a rotation angle measurement apparatus and method in which a measurement sensor measures a rotation angle of a rotating body in a non-contact manner by image processing.

  As a device for measuring the rotation angle of a rotating body, a device that measures a rotation angle by installing a measurement sensor such as a rotary encoder or a potentiometer on a rotating shaft of the rotating body is generally used.

  There is also an apparatus for measuring the number of rotations by attaching a reflection tape to a rotating shaft and receiving reflected light of irradiated light (see Non-Patent Document 1).

  Furthermore, a method for measuring the rotation angle of a rotating body by image processing has been proposed. For example, by registering an image of the circumferential surface (all circumferences) of a cylindrical can and finding out whether the input image hits the position of the registered image by extracting the correlation peak using two-dimensional discrete Fourier transform, the rotation angle is calculated. There is a method for measuring the rotation angle of the motor (see Patent Document 1) and a method for obtaining the rotation angle from the positional relationship between the two markers by arranging markers respectively in the vicinity of the rotation axis and at a position away from the rotation axis. (See Patent Document 2).

JP 2002-163659 A Japanese Patent Laid-Open No. 10-78311

Ono Sokki Co., Ltd. <URL: http://www.onosokki.co.jp/HP-WK/products/category/h_revo.htm>

  In the method of installing a sensor such as the rotary encoder or potentiometer described above on the rotating shaft of the rotating body, the measurement sensor cannot measure the rotation angle without contact.

  In the method of detecting the reflected light of the reflective tape attached to the rotating body as in Non-Patent Document 1, the number of rotations can be measured, but the rotation angle cannot be measured.

  In the method of calculating the rotation angle by collating the registered peripheral surface image and the input image as in Patent Document 1, there is a possibility that the wrong rotation angle is calculated when there is a similar pattern portion. Moreover, the calculation cost for obtaining the correlation between the input image and the registered image is high.

  In the method of obtaining the rotation angle from the positional relationship between the two markers as in Patent Document 2, in order to improve the detectable rotation angle accuracy, it is necessary to handle large image data using a high-resolution CCD camera, and the calculation cost is high. Will increase. Conversely, if an attempt is made to reduce the calculation cost using a normal CCD camera, high detection angle accuracy cannot be expected.

  An object of the present invention is to provide a rotation angle measuring device and method for measuring the rotation angle of a rotating body with high accuracy while suppressing calculation cost by image processing so as to solve the above-mentioned problems without contact with a total of 100 million sensors. It is to be.

A rotation angle measuring device according to a first invention for solving the above-mentioned problems is as follows.
A marker installed on a rotating object to be measured;
A line sensor that images the marker pattern of the marker;
A high-definition camera that captures the marker pattern as a high-definition image from the same direction as the line sensor;
An analyzer for analyzing the image taken by the line sensor and obtaining the rotation angle of the rotating body ,
The analysis device obtains data of a three-dimensional boundary line that is a three-dimensional position of the boundary line of the marker pattern from the high-definition image photographed by the high-definition camera, and based on the data, the line sensor After deriving in advance the relationship between the rotation position and the marker pattern boundary line position on the image when shooting by obtaining the marker pattern boundary line position from the image captured by the line sensor, Based on the relationship, a boundary line position of the marker pattern is converted into the rotation angle .

A rotation angle measuring device according to a second invention for solving the above-mentioned problems is as follows.
In the rotation angle measuring apparatus according to the first aspect of the invention,
The marker pattern boundary line position of the marker is uniquely associated with the rotation angle of the rotating body.

A rotation angle measuring device according to a third invention for solving the above-mentioned problem is as follows.
In the rotation angle measuring device according to the first or second invention,
The marker pattern boundary line position of the marker is directly proportional to the rotation angle of the rotating body.

A rotation angle measuring device according to a fourth invention for solving the above-mentioned problems is as follows.
In the rotation angle measurement apparatus according to any one of the first to third aspects,
The line sensor is arranged in a positional relationship in which the rotation axis of the rotating body and the optical axis of the line sensor are parallel and the marker and the line sensor face each other with respect to the rotating body on which the marker is installed on the upper surface or the bottom surface. And
The marker has a spiral marker pattern boundary line.

A rotation angle measuring device according to a fifth invention for solving the above-mentioned problems is as follows.
In the rotation angle measurement apparatus according to any one of the first to third aspects,
The line sensor has a rotation axis of the rotation body and the optical axis of the line sensor perpendicular to each other and the imaging axis of the line sensor is parallel to the rotation body on which the marker is installed on the side surface. Are arranged in various positional relationships,
The marker has a boundary line of a spiral marker pattern.

A rotation angle measuring device according to a sixth invention for solving the above-described problem is as follows.
In the rotation angle measurement device according to any one of the first to fifth inventions,
The analysis device includes:
A threshold value used for detecting a boundary position of the marker pattern, a lens focal length of the high-definition camera, an image element size, a position of the line sensor and the high-definition camera, and shape data of an installation surface of the marker; A process setting unit for setting as a process parameter;
An image input unit for inputting luminance information photographed by the line sensor or the high-definition camera;
A high-definition camera image boundary line position detection unit that detects a boundary line position of the marker pattern on the image captured by the high-definition camera as first boundary line position data;
Based on the first boundary line position data and the processing parameters, a boundary line three-dimensional position calculation unit that creates data of the boundary line three-dimensional position photographed by the high-definition camera;
Based on the processing parameter and the plurality of boundary line 3D position data photographed by the high-definition camera while changing the rotation angle of the rotating body, the boundary line 3D position data is synthesized, and the rotating body A boundary line three-dimensional position synthesis unit that creates the boundary line three-dimensional position data over the entire circumference,
A pixel-angle graph creating unit for deriving the relationship based on the processing parameters and the boundary line three-dimensional position data over the entire circumference of the rotating body;
A boundary position detection unit for detecting a boundary line position of the marker pattern on the image captured by the line sensor as second boundary line position data;
A rotation angle conversion unit that converts the boundary line position of the marker pattern on the image of the line sensor into a rotation angle with reference to the relationship based on the second boundary line position data. .

A rotation angle measurement method according to a seventh invention for solving the above-described problem is as follows.
The marker was placed on the rotating body to be measured, an image obtained by photographing the marker pattern of the marker in the line sensor, by analyzing with the analysis apparatus, a rotational angle measuring method asking you to rotation angle of the rotating body,
The marker pattern is photographed as a high-definition image from the same direction as the line sensor by a high-definition camera, and the boundary that is a three-dimensional position of the boundary line of the marker pattern from the high-definition image by the analyzer Obtaining the data of the line three-dimensional position, and based on the data, after deriving in advance the relationship between the position of the marker pattern boundary line on the image when the image is taken by the line sensor and the rotation angle, A boundary line position of the marker pattern is obtained from an image captured by a line sensor, and the boundary line position of the marker pattern is converted into the rotation angle based on the relationship .

A rotation angle measuring method according to an eighth invention for solving the above-mentioned problem is as follows.
In the rotation angle measurement method according to the seventh invention,
The relationship between the marker pattern boundary line position of the marker and the rotation angle of the rotating body is uniquely associated.

A rotation angle measuring method according to a ninth invention for solving the above-described problem is
In the rotation angle measurement method according to the seventh or eighth invention,
The relationship between the marker pattern boundary line position of the marker and the rotation angle of the rotator is directly proportional.

Rotation angle measuring method according to the invention of the first 0 for solving the above-
In the rotation angle measurement method according to any one of the seventh to ninth inventions,
The line sensor is positioned so that the rotation axis of the rotating body and the optical axis of the line sensor are parallel to each other and the marker and the line sensor face each other with respect to the rotating body on which the marker is installed on the upper surface or the bottom surface. Placed in
The marker has a spiral marker pattern boundary line.

Rotation angle measuring method according to the first aspect of the present invention for solving the above-
In the rotation angle measurement method according to any one of the seventh to ninth inventions,
The line sensor has a rotation axis of the rotation body and the optical axis of the line sensor perpendicular to each other and the imaging axis of the line sensor is parallel to the rotation body on which the marker is installed on the side surface. Arranged so that the position
The marker has a boundary line of a spiral marker pattern.

According to the rotation angle measuring device or method according to the first, sixth, and seventh aspects of the present invention, an analysis device is used to analyze an image obtained by photographing a marker pattern of a marker installed on a rotating body with a line sensor. Can be obtained. Furthermore, by deriving in advance the relationship between the position of the marker pattern boundary line and the rotation angle based on the high-definition image, the rotation angle can be measured without requiring high-precision processing for marker installation. Can be simplified.

According to the rotation angle measuring apparatus or method according to the second and eighth aspects of the invention, the rotation angle of the rotating body can be uniquely obtained from the boundary line position of the marker pattern.

According to the rotation angle measuring apparatus or method according to the third, fourth, fifth, ninth, tenth, and eleventh aspects of the present invention, since the detection of the marker pattern boundary line position is a simple method, the calculation cost can be reduced. Can do.

It is a side view of the rotary body which installed the helical marker in Example 1 of this invention. It is the front view which looked at the rotary body which installed the spiral marker in Example 2 of this invention from the marker installation surface. It is a schematic diagram which shows the positional relationship of the rotary body and line sensor which installed the helical marker in Example 1 of this invention. It is a schematic diagram which shows the positional relationship of the rotary body and line sensor which installed the spiral marker in Example 2 of this invention. It is a graph showing the relationship between the rotation angle of a rotary body, and the boundary line position of a marker pattern by the rotation angle measuring device which concerns on Example 1, 2 of this invention. It is a graph which shows the relationship between the position on an image, and the luminance signal of a marker pattern when the spiral marker installed in the rotary body is image | photographed with the line sensor. The time obtained by obtaining the boundary position of the marker pattern from the time-series image when the rotating body is rotated several times by the rotation angle measuring device according to the first and second embodiments of the present invention, and the image taken by the line sensor It is a graph which shows the relationship of the boundary line position of an upper marker pattern. It is a flowchart explaining the action | operation of the rotation angle measuring device which concerns on Example 1, 2 of this invention. It is a block diagram of the analyzer in Example 1, 2 of this invention. It is a schematic diagram which shows the rotation angle measuring device which concerns on Example 3 of this invention. It is a block diagram of the analyzer in Example 3 of this invention. It is a graph showing the relationship between the rotation angle of a rotary body, and the boundary line position of a marker pattern by the rotation angle measuring device which concerns on Example 3 of this invention. It is a flowchart explaining the action | operation of the rotation angle measuring device which concerns on Example 3 of this invention. It is a schematic diagram which shows the method of calculating | requiring the boundary line three-dimensional position of a marker pattern by the rotation angle measuring device which concerns on Example 3 of this invention. It is a schematic diagram which shows the example which calculated | required the boundary line three-dimensional position of the partial marker pattern with respect to a rotary body by the rotation angle measuring device which concerns on Example 3 of this invention. It is a schematic diagram which shows the method of calculating | requiring the position on the imaging line of a line sensor from the boundary line three-dimensional position of a marker pattern by the rotation angle measuring device which concerns on Example 3 of this invention.

  In the rotation angle measurement apparatus according to the present invention, a rotation angle is obtained by installing a marker on a rotating object to be measured and analyzing an image obtained by capturing a marker pattern of the marker with a line sensor. Hereinafter, a rotation angle measuring device according to the present invention will be described with reference to the drawings by way of examples.

  As shown in FIG. 3, the rotation angle measurement device according to the first embodiment of the present invention includes a marker 2, a line sensor 4, and an analysis device 5 that are installed on a rotating body 1 to be measured. Here, the rotation axis of the rotating body 1 to be measured and the optical axis of the line sensor 4 are perpendicular to each other, and the rotation axis of the rotating body 1 and the imaging line of the line sensor 4 are parallel to each other. Yes.

  The line sensor 4 used as a measurement sensor of this apparatus is a camera that can photograph one line with high resolution. The number of pixels for one line is higher than that of a normal CCD camera, but since only one line is photographed, the data amount of the entire image is much smaller than that of the CCD camera.

  As shown in FIG. 1, the marker uses a spiral marker 2 in which the boundary line of the marker pattern is drawn in a spiral shape. This marker pattern is designed so that the relationship between the rotation angle θ of the rotating body 1 on which the spiral marker 2 is installed and the boundary line position L of the marker pattern is as follows.

  L = {(L2-L1) / 2π} θ + L1

  When such a spiral marker 2 is installed on the rotator 1, the rotation angle of the rotator 1 and the boundary line of the marker pattern have a direct proportional relationship as shown in FIG. That is, the rotation angle of the rotator 1 and the boundary line of the marker pattern uniquely correspond to each other.

  Also, if the difference in brightness between the marker base and the marker pattern is made large, the brightness difference at the boundary line position of the marker pattern changes abruptly on the image captured by the line sensor 4. As shown in FIG. 6, the marker pattern boundary line position on the image can be obtained as a position where a luminance difference equal to or greater than a threshold exists or a position where the second-order differential image crosses zero.

  Therefore, the analysis device 5 detects the image position where the luminance difference changes abruptly from the image captured by the line sensor 4, and calculates the rotation angle by converting the image position to the rotation angle of the rotating body 1. As shown in FIG. 9, the analysis device 5 includes an image input unit 12, a time-series image creation unit 13, a boundary line position detection unit 14, a rotation angle calculation unit 17, a processing setting unit 11, and a boundary line position movement range measurement unit 15. A rotation angle calculation formula setting unit 16, a data output unit 19, and a storage unit 18.

  In the process setting unit 11 described above, the threshold value of the luminance difference used for detecting the border line position of the marker pattern is set as a process parameter.

  In the image input unit 12 described above, image data for one line captured by the line sensor 4 is input.

  The above-described time-series image creation unit 13 creates time-series image data in which the image data input from the image input unit 12 are arranged in time series.

  The above-described boundary line position detection unit 14 detects the boundary line position of the marker pattern of the time-series image data based on the threshold set by the process setting unit 11, and creates boundary line position data.

  The above-described boundary line position movement range measurement unit 15 obtains the movement range of the boundary line position of the marker pattern from the boundary line position data when the rotator 1 is rotated several times, and creates boundary line position movement range data.

  The rotation angle calculation formula setting unit 16 determines a formula for calculating the rotation angle of the rotating body 1 (hereinafter referred to as a rotation angle calculation formula) from the boundary line position movement range data.

  The rotation angle calculation unit 17 described above calculates the rotation angle of the rotating body 1 from the boundary line position data of the marker pattern and creates rotation angle data.

  The storage unit 18 stores the above-described data (excluding boundary line position movement range data) and processing parameters (including the rotation angle calculation formula).

  The data output unit 19 outputs the rotation angle data of the rotating body 1.

  Hereinafter, the measurement procedure of the rotation angle measurement apparatus according to the first embodiment of the present invention will be described with reference to FIG.

  In step S1, the movement range of the boundary position of the marker pattern on the image is measured in advance.

  First, the process setting unit 11 sets a threshold value of a luminance difference used for detecting the border line position of the marker pattern. Thereafter, the rotating object 1 to be measured is rotated several times while being photographed by the line sensor 4, the image data is taken in from the image input unit 12, and the time-series image creating unit 13 creates time-series image data.

  Then, when the boundary position of the marker pattern is obtained from the time-series image data based on the threshold set by the processing setting unit 11, the boundary position of the marker pattern on the image with respect to the time on the saw blade as shown in FIG. A graph of data (hereinafter referred to as a boundary line time series graph) can be obtained. In this graph, the range from P1 to P2 is the movement range of the boundary position of the marker pattern (hereinafter referred to as the boundary position movement range).

  Therefore, the boundary line position detection unit 14 creates a boundary line position time series graph, and the boundary line position movement range measurement unit 15 determines the point where the boundary line position of the marker pattern in the boundary line position time series graph is closest to zero. P1 is obtained, and a point at which the boundary line position of the marker pattern is farthest from 0 is obtained as P2. As a method of obtaining P1 and P2, the upper and lower peaks of the graph on the saw blade may be obtained, the average of the lower peak may be P1, and the average of the upper peak may be P2. P1 and P2 thus obtained are actually the positions L1 and L2 of the spiral marker 2.

  In step S2, the rotation angle calculation formula setting unit 16 obtains a rotation angle calculation formula in advance.

  First, if the movement range of the marker pattern boundary line position can be calculated in step 1 described above, the marker pattern boundary line position P on the image and the rotation angle θ have the following relationship.

  P = {(P2-P1) / 2π} θ + P1

  Therefore, the rotation angle calculation formula is obtained as follows.

θ = aP−b
a = {2π / (P2-P1)}
b = {2π / (P2-P1)} P1

  From step 3, measurement of the actual rotation angle is started. First, in step S3, the rotating object 1 to be measured is photographed.

  As shown in FIG. 6, the marker pattern of the marker 2 installed on the rotator 1 is photographed by the line sensor 4, the image data photographed from the image input unit 12 is taken in, and the time-series image creation unit 13 captures one line. Save the image data in time series to create time series image data.

  In step S4, the boundary line position detection unit 14 obtains the boundary line position of the marker pattern from the time-series image data created in step 3.

  As a procedure, as described above, the border line position of the marker pattern on the image is obtained as a position where the luminance equal to or higher than the threshold exists or a position where the second-order differential image crosses zero. Therefore, luminance information for one line is sequentially read from the time-series image, and the boundary line position of the marker pattern on the image is obtained by the above-described method.

  In step S5, the rotation angle of the rotating body 1 is obtained from the boundary line position data of the marker pattern on the image.

  In the rotation angle calculation unit 17, the boundary line position data of the marker pattern on the image is substituted into the above-described equation θ = aP−b to obtain the rotation angle. The calculated result is output from the data output unit 19 as rotation angle data.

  Incidentally, in the above-described steps S1 to S5, each data (excluding boundary line position movement range data) and each processing parameter (including a rotation angle calculation formula) are stored in the storage unit 18 each time.

  In the apparatus according to the first embodiment of the present invention, the line sensor 4 is perpendicular to the rotating body 1 to be measured and the optical axis of the line sensor 4 is perpendicular to the rotating axis of the rotating body 1 and the line sensor. The lines to be photographed 4 are arranged in a parallel positional relationship, and the measurement sensor can measure the rotation angle of the rotating body 1 without contact. Further, by using the line sensor 4 as a measurement sensor, it is possible to obtain high detection angle accuracy while suppressing calculation cost. Further, by converting the boundary line position of the marker pattern with a clear luminance difference into a rotation angle by the analysis device 5, high-speed calculation can be performed without using complicated processing.

  As illustrated in FIG. 4, the rotation angle measurement device according to the second embodiment of the present invention includes a marker 3, a line sensor 4, and an analysis device 5 that are installed on a rotating body 1 to be measured. Here, the rotation axis of the rotating body 1 to be measured and the optical axis of the line sensor 4 are parallel and the marker 3 and the line sensor 4 face each other.

  Since the line sensor 4 is the same as that of the first embodiment, the description thereof is omitted.

  As shown in FIG. 2, the marker uses a spiral marker 3 in which the boundary line of the marker pattern is drawn in a spiral shape. This marker pattern is designed so that the relationship between the rotation angle θ of the rotating body 1 on which the spiral marker 3 is installed and the boundary line position R of the marker pattern is as follows.

  R = {(R2-R1) / 2π} θ + R1

  When such a spiral marker 3 is installed on the rotating body 1, the rotation angle and the boundary line of the marker pattern have a direct proportional relationship as shown in FIG. That is, the boundary line of the marker pattern uniquely corresponds to the rotation angle.

  Also, if the difference in brightness between the marker base and the marker pattern is made large, the brightness difference at the boundary line position of the marker pattern changes abruptly on the image captured by the line sensor 4. The border line position of the marker pattern on the image can be obtained as a position where a luminance difference equal to or greater than a threshold exists or a position where the second-order differential image crosses zero.

  Therefore, the analysis device 5 detects the image position where the luminance difference changes abruptly from the image captured by the line sensor 4, and calculates the rotation angle by converting the image position to the rotation angle of the rotating body 1. As shown in FIG. 9, the analysis device 5 includes an image input unit 12, a time-series image creation unit 13, a boundary line position detection unit 14, a rotation angle calculation unit 17, a processing setting unit 11, and a boundary line position movement range measurement unit 15. A rotation angle calculation formula setting unit 16, a data output unit 19, and a storage unit 18.

  In the process setting unit 11 described above, the threshold value of the luminance difference used for detecting the border line position of the marker pattern is set as a process parameter.

  In the image input unit 12 described above, image data for one line captured by the line sensor 4 is input.

  The above-described time-series image creation unit 13 creates time-series image data in which the image data input from the image input unit 12 are arranged in time series.

  The above-described boundary line position detection unit 14 detects the boundary line position of the marker pattern of the time-series image data based on the threshold set by the process setting unit 11, and creates boundary line position data.

  The above-described boundary line position movement range measurement unit 15 obtains the movement range of the boundary line position of the marker pattern from the boundary line position data when the rotator 1 is rotated several times, and creates boundary line position movement range data.

  The above-described rotation angle calculation formula setting unit 16 determines a rotation angle calculation formula for calculating the rotation angle of the rotator 1 from the boundary line position movement range data.

  The rotation angle calculation unit 17 described above calculates the rotation angle of the rotating body 1 from the boundary line position data of the marker pattern and creates rotation angle data.

  The storage unit 18 stores the above-described data (excluding boundary line position movement range data) and processing parameters (including the rotation angle calculation formula).

  The data output unit 19 outputs the rotation angle data of the rotating body 1.

  Hereinafter, the measurement procedure of the rotation angle measurement apparatus according to the second embodiment of the present invention will be described with reference to FIG.

  In step S1, the movement range of the boundary position of the marker pattern on the image is measured in advance.

  First, the process setting unit 11 sets a threshold value of a luminance difference used for detecting the border line position of the marker pattern. Thereafter, the rotating object 1 to be measured is rotated several times while being photographed by the line sensor 4, the image data is taken in from the image input unit 12, and the time-series image creating unit 13 creates and stores the time-series image data.

  Then, when the boundary line position of the marker pattern is obtained from the time series image data based on the threshold set by the process setting unit 11, a boundary line position time series graph as shown in FIG. 7 can be obtained. In this graph, the range from P1 to P2 is the boundary line position movement range of the marker pattern.

  Therefore, the boundary line position detection unit 14 creates a boundary line position time series graph, and the boundary line position movement range measurement unit 15 determines the point of the boundary line position time series graph where the boundary line position of the marker pattern is closest to 0 P1. In addition, a point where the boundary line position of the marker pattern is farthest from 0 is obtained as P2. As a method of obtaining P1 and P2, the upper and lower peaks of the graph on the saw blade may be obtained, the average of the lower peak may be P1, and the average of the upper peak may be P2. P1 and P2 thus determined are actually the positions of R1 and R2 of the spiral marker.

  In step S2, the rotation angle calculation formula setting unit 16 obtains a rotation angle calculation formula in advance.

  First, if the boundary position movement range of the marker pattern can be calculated in step 1 described above, the boundary position P of the marker pattern on the image and the rotation angle θ have the following relationship.

  P = {(P2-P1) / 2π} θ + P1

  Therefore, the rotation angle calculation formula is obtained as follows.

θ = aP−b
a = {2π / (P2-P1)}
b = {2π / (P2-P1)} P1

  From step 3, measurement of the actual rotation angle is started. First, in step S3, the rotating object 1 to be measured is photographed.

  As shown in FIG. 6, the marker pattern of the marker 2 installed on the rotator 1 is photographed by the line sensor 4, the image data photographed from the image input unit 12 is taken in, and the time-series image creation unit 13 captures one line. Save the image data in time series to create time series image data.

  In step S4, the boundary line position detection unit 14 obtains the boundary line position of the marker pattern from the time-series image data created in step 3.

  As a procedure, as described above, the border line position of the marker pattern on the image is obtained as a position where the luminance equal to or higher than the threshold exists or a position where the second-order differential image crosses zero. Therefore, luminance information for one line is sequentially read from the time-series image, and the boundary line position of the marker pattern on the image is obtained by the above-described method.

  In step S5, the rotation angle of the rotating body 1 is obtained from the boundary line position data of the marker pattern on the image.

  In the rotation angle calculation unit 17, the boundary line position data of the marker pattern on the image is substituted into the above-described equation θ = aP−b to obtain the rotation angle. The calculated result is output from the data output unit 19 as rotation angle data.

  Incidentally, in the above-described steps S1 to S5, each data (excluding boundary line position movement range data) and each processing parameter (including a rotation angle calculation formula) are stored in the storage unit 18 each time.

  In the apparatus according to the second embodiment of the present invention, the line sensor 4 is parallel to the rotating body 1 to be measured, the rotational axis of the rotating body 1 is parallel to the optical axis of the line sensor 4, and the spiral marker 3 and the line sensor 4 are connected. It is installed in a positional relationship facing each other, and the measurement sensor can measure the rotation angle of the rotating body 1 without contact. Further, by using the line sensor 4 as a measurement sensor, it is possible to obtain high detection angle accuracy while suppressing calculation cost. Further, by converting the boundary line position of the marker pattern with a clear luminance difference into a rotation angle by the analysis device 5, high-speed calculation can be performed without using complicated processing.

  In the rotation angle measuring device according to the first and second embodiments of the present invention, the marker needs to be installed on the rotating body with high accuracy. It is good to place a machined marker on a rotating body, but if the marker is manually attached to an existing rotating shaft, etc., high accuracy cannot be expected for marker placement, resulting from distortion of the boundary line position. The detection accuracy of the rotation angle is lowered.

  Therefore, the rotation angle measuring device according to the third embodiment of the present invention has a function of calibrating the marker position.

That is, in the rotation angle measuring apparatus according to the first and second embodiments, the rotation is performed from the boundary position of the marker pattern according to the relational expressions in paragraphs [005 1 ] and [008 5 ] on the assumption that the marker is accurately installed. Although the angle is converted, if there is distortion in the marker installation, the graph is not a straight line but a curve. In the rotation angle measuring apparatus according to the third embodiment, the three-dimensional position of the boundary line of the marker pattern (hereinafter referred to as the three-dimensional position of the boundary line of the marker pattern) is considered in consideration of distortion in the marker installation. By performing measurement in advance, a graph (hereinafter referred to as pixel-angle graph) showing the relationship between the position of the boundary line of the marker pattern on the image and the rotation angle is created, and measurement is performed with a line sensor by referring to the graph. The rotation angle is obtained from the boundary line position of the marker pattern. A method for creating the pixel-angle graph will be described later.

  As shown in FIG. 10, the rotation angle measurement apparatus according to the third embodiment of the present invention includes a spiral marker 2, a line sensor 4, an analysis apparatus 20, and a high-definition camera 31 that are installed on a rotating body 1 to be measured. With.

  The helical marker 2 and the line sensor 4 described above are the same as those in the first embodiment, and thus description thereof is omitted.

  The high definition camera 31 captures the marker pattern as a high definition image from the same direction as the line sensor 4. Here, the high definition indicates a high definition as compared with the line sensor 4 and an accuracy with which the boundary line position of the marker pattern can be obtained (for example, about 2 million pixels).

  As shown in FIG. 11, the analysis device 20 includes a process setting unit 21, an image input unit 22, a high-definition camera image boundary line position detection unit 23, a boundary line three-dimensional position calculation unit 24, and a boundary line three-dimensional image. The position synthesis unit 25, the pixel-angle graph creation unit 26, the boundary line position detection unit 27, the rotation angle conversion unit 28, the storage unit 29, and the data output unit 30 are provided.

  The above-described processing setting unit 21 is configured to detect the threshold value used for detecting the border line position of the marker pattern, the lens focal length of the high-definition camera 31, the image element size, the position of the line sensor 4 and the high-definition camera 31, and the installation of the spiral marker 2. Surface shape (cylinder side surface) data and the like are set as processing parameters.

  The image input unit 22 described above inputs luminance information captured by the line sensor 4 or the high-definition camera 31 as image data.

  The high-definition camera image boundary line position detection unit 23 detects the boundary line position of the marker pattern on the image captured by the high-definition camera 31 as boundary line position data.

  The above-described boundary line three-dimensional position calculation unit 24 creates boundary line three-dimensional position data of the marker pattern photographed by the high-definition camera 31 based on the boundary line position data and the processing parameters.

  The boundary line three-dimensional position synthesis unit 25 described above is based on processing parameters and boundary line three-dimensional position data of marker patterns on a plurality of images taken by the high-definition camera 31 while changing the rotation angle of the rotating body 1. Then, the boundary pattern three-dimensional position data of the marker pattern is synthesized, and the boundary line three-dimensional position data of the marker pattern over the entire circumference of the rotating body 1 is created.

  The pixel-angle graph creating unit 26 described above creates pixel-angle graph data based on the processing parameters and the boundary pattern three-dimensional position data of the marker pattern over the entire circumference of the rotating body 1.

  The boundary position detection unit 27 described above detects the boundary line position of the marker pattern on the image captured by the line sensor 4 as boundary line position data.

  The rotation angle conversion unit 28 described above creates rotation angle data by referring to the pixel-angle graph based on the boundary line position data and converting the boundary line position of the marker pattern on the image of the line sensor 4 into a rotation angle. To do.

  The above-described storage unit 29 stores the above-described data and processing parameters.

  The data output unit 30 described above outputs rotation angle data.

  In other words, the analysis device 20 uses the threshold value used for detecting the border line position of the marker pattern, the lens focal length of the high-definition camera 31, the image element size, the positions of the line sensor 4 and the high-definition camera 31, and the marker. A processing setting unit 21 that sets the shape data of the installation surface of the image as processing parameters, an image input unit 22 that inputs luminance information captured by the line sensor 4 or the high-definition camera 31, and an image captured by the high-definition camera 31 A high-definition camera image boundary line position detection unit 23 that detects the boundary line position of the marker pattern as first boundary line position data, and the high-definition camera 31 based on the first boundary line position data and processing parameters. A boundary 3D position calculation unit 24 that creates data of the captured 3D position of the boundary line, a high-definition camera 31 that changes processing parameters and the rotation angle of the rotating body 1 Boundary line 3D position synthesis unit that synthesizes the boundary line 3D position data based on a plurality of captured boundary line 3D position data and creates boundary 3D position data over the entire circumference of the rotating body 1 25, the processing parameter, and the boundary line position of the marker pattern on the image and the rotation of the rotating body 1 when the image is captured by the line sensor 4 based on the processing parameter and the boundary three-dimensional position data over the entire circumference of the rotating body 1. A pixel-angle graph creation unit 26 for deriving an angle relationship; a boundary position detection unit that detects a boundary line position of a marker pattern on an image captured by the line sensor 4 as second boundary line position data; A rotation angle conversion unit that converts the boundary line position of the marker pattern on the image of the line sensor 4 into the rotation angle of the rotator 1 with reference to the above relationship based on the boundary line position data.

  Hereinafter, the measurement procedure of the rotation angle measurement apparatus according to the third embodiment of the present invention will be described with reference to FIG.

In step S11, a pixel-angle graph is created according to the following paragraphs [01 16 ] to [01 24 ].

  It is assumed that the shape (cylindrical side surface) of the installation portion of the spiral marker 2 of the rotator 1 to be measured and the distance from the line sensor 4 to the rotator 1 to be measured are known in advance. Under this condition, a pixel-angle graph is created by obtaining the three-dimensional position of the boundary line of the marker pattern. The marker pattern boundary line three-dimensional position measurement is performed by the following procedure.

  First, as a first procedure, as shown in FIG. 10, not the line sensor 4 but the high-definition camera 31 is connected to the analysis device 20.

As a second procedure, the high-definition camera 31 takes a high-definition image of the spiral marker 2 provided on the rotating body 1 and the high-definition camera image boundary position detection unit 23 performs a marker pattern on the image. Find the boundary position of. Determination of the boundary line position on the image, Ru using the same method as taken by the line sensor 4 described in the first embodiment.

  As a third procedure, the boundary line three-dimensional position calculation unit 24 inputs boundary line position data from the boundary line position detection unit 23 for high-definition camera images, and as shown in FIG. The position is obtained as a point a that intersects the installation position of the spiral marker 2 of the rotator 1 from the lens focus c of the high-definition camera 31 through the boundary position on the imaging surface b. As a result, as shown in FIG. 15, the boundary pattern three-dimensional position (curved portion in the figure) of the partial marker pattern is obtained with respect to the rotator 1 (the straight line in the figure is the rotation axis d of the rotator 1). Is shown).

  As a fourth procedure, the rotating body 1 is rotated about the rotation axis d, the angle is changed, the third procedure is sequentially performed, and the boundary line three-dimensional position of the marker pattern is measured over the entire side surface of the rotating body 1. .

  As a fifth procedure, the boundary line three-dimensional position calculation unit 24 inputs the boundary line three-dimensional position data of the marker pattern obtained by dividing the plurality of times in the fourth procedure by the boundary line three-dimensional position synthesis unit 25. Then, the boundary pattern three-dimensional position data of the marker pattern over the entire circumference of the side surface of the rotating body 1 is created.

  As a sixth procedure, the high-definition camera 31 is replaced with the line sensor 4.

  Next, the pixel-angle graph creation unit 26 uses the marker-pattern boundary line three-dimensional position data that is input from the boundary line three-dimensional position synthesis unit 25 and covers the entire circumference of the side surface of the rotating body 1. Create

  That is, assuming that the image is taken by the line sensor 4, a point where the straight line connecting the three-dimensional position of the boundary line of the marker pattern and the lens focal point c ′ of the line sensor 4 intersects the imaging line e of the line sensor 4 as shown in FIG. Find f and g. This becomes the boundary line position of the marker pattern on the image of the line sensor 4. By doing this over the entire circumference of the side surface, a pixel-angle graph is created. When the spiral marker 2 is attached to the rotating body 1 manually, the created pixel-angle graph is as shown in FIG. The above is step S11.

  In step S12, the rotating object 1 to be measured is photographed by the line sensor 4 as shown in FIG.

  In step S13, the position of the boundary line of the marker pattern is obtained from the image captured by the line sensor 4. That is, the boundary line position detection unit 27 obtains a position where a luminance difference equal to or larger than a threshold value on the image or a position where the second-order differential image crosses zero as the boundary line position of the marker pattern on the image.

  In step S14, the rotation angle is obtained from the boundary line position of the marker pattern on the image.

  That is, the rotation angle conversion unit 28 refers to the pixel-angle graph based on the boundary line position on the image, converts the marker line boundary line position on the image into a rotation angle, and obtains the rotation angle.

  In this way, in the rotation angle measurement apparatus according to the third embodiment, in consideration of the distortion in the marker installation, a pixel-angle graph is created by measuring the boundary line three-dimensional position of the marker pattern in advance. The rotation angle is obtained by referring to the pixel-angle graph from the boundary position of the marker pattern measured by the line sensor.

  In the rotation angle measurement device according to the third embodiment, the relationship between the marker pattern boundary line position and the rotation angle is derived in advance based on the high-definition image as compared with the rotation angle measurement devices according to the first and second embodiments. Thus, the rotation angle can be measured without requiring high-precision processing for installing the marker, and the work can be simplified.

  In the present embodiment, the spiral marker 2 used in the first embodiment has been described as an example, but the spiral marker 3 used in the second embodiment can also be applied. However, in the spiral marker 3, the three-dimensional position of the boundary line of the marker pattern is obtained with the shape of the marker installation surface as the plane of the upper surface or the bottom surface of the rotating body 1. Furthermore, any marker can be applied as long as it has a marker pattern boundary line position that uniquely corresponds to the rotation angle of the rotating body 1.

  INDUSTRIAL APPLICABILITY The present invention is suitable as an apparatus and method for a rotation angle measurement apparatus and method in which a measurement sensor measures the rotation angle of a rotating body in a non-contact manner through image processing.

DESCRIPTION OF SYMBOLS 1 Rotating body 2 Spiral marker 3 Spiral marker 4 Line sensor 5, 20 Analysis apparatus 11, 21 Process setting part 12, 22 Image input part 13 Time series image creation part 14 Boundary line position detection part 15 Boundary line position movement range measurement Unit 16 rotation angle calculation formula setting 17 rotation angle calculation unit 18, 29 storage unit 19, 30 data output unit 23 boundary line position detection unit for high-definition camera image 24 boundary line 3D position calculation unit 25 boundary line 3D position synthesis unit 26 Pixel-angle graph creation unit 27 Boundary line position detection unit 28 Rotation angle conversion unit 31 High-definition camera

Claims (11)

A marker installed on a rotating object to be measured;
A line sensor that images the marker pattern of the marker;
A high-definition camera that captures the marker pattern as a high-definition image from the same direction as the line sensor;
An analyzer for analyzing the image taken by the line sensor and obtaining the rotation angle of the rotating body ,
The analysis device obtains data of a three-dimensional boundary line that is a three-dimensional position of the boundary line of the marker pattern from the high-definition image photographed by the high-definition camera, and based on the data, the line sensor After deriving in advance the relationship between the rotation position and the marker pattern boundary line position on the image when shooting by obtaining the marker pattern boundary line position from the image captured by the line sensor, A rotation angle measuring device that converts a boundary line position of the marker pattern into the rotation angle based on the relationship .   The rotation angle measuring device according to claim 1, wherein the marker line boundary position of the marker uniquely corresponds to the rotation angle of the rotating body.   The rotation angle measuring device according to claim 1, wherein the marker line boundary position of the marker is directly proportional to the rotation angle of the rotating body. The line sensor is arranged in a positional relationship in which the rotation axis of the rotating body and the optical axis of the line sensor are parallel and the marker and the line sensor face each other with respect to the rotating body on which the marker is installed on the upper surface or the bottom surface. And
The rotation angle measuring device according to any one of claims 1 to 3, wherein the marker has a spiral marker pattern boundary line. The line sensor has a rotation axis of the rotation body and the optical axis of the line sensor perpendicular to each other and the imaging axis of the line sensor is parallel to the rotation body on which the marker is installed on the side surface. Are arranged in various positional relationships,
The rotation angle measuring device according to any one of claims 1 to 3, wherein the marker has a boundary line of a spiral marker pattern. The analysis device includes:
A threshold value used for detecting a boundary position of the marker pattern, a lens focal length of the high-definition camera, an image element size, a position of the line sensor and the high-definition camera, and shape data of an installation surface of the marker; A process setting unit for setting as a process parameter;
An image input unit for inputting luminance information photographed by the line sensor or the high-definition camera;
A high-definition camera image boundary line position detection unit that detects a boundary line position of the marker pattern on the image captured by the high-definition camera as first boundary line position data;
Based on the first boundary line position data and the processing parameters, a boundary line three-dimensional position calculation unit that creates data of the boundary line three-dimensional position photographed by the high-definition camera;
Based on the processing parameter and the plurality of boundary line 3D position data photographed by the high-definition camera while changing the rotation angle of the rotating body, the boundary line 3D position data is synthesized, and the rotating body A boundary line three-dimensional position synthesis unit that creates the boundary line three-dimensional position data over the entire circumference,
A pixel-angle graph creating unit for deriving the relationship based on the processing parameters and the boundary line three-dimensional position data over the entire circumference of the rotating body;
A boundary position detection unit for detecting a boundary line position of the marker pattern on the image captured by the line sensor as second boundary line position data;
A rotation angle conversion unit that converts the boundary line position of the marker pattern on the image of the line sensor into a rotation angle with reference to the relationship based on the second boundary line position data. The rotation angle measuring device according to any one of claims 1 to 5 . The marker was placed on the rotating body to be measured, an image obtained by photographing the marker pattern of the marker in the line sensor, by analyzing with the analysis apparatus, a rotational angle measuring method asking you to rotation angle of the rotating body,
The marker pattern is photographed as a high-definition image from the same direction as the line sensor by a high-definition camera, and the boundary that is a three-dimensional position of the boundary line of the marker pattern from the high-definition image by the analyzer Obtaining the data of the line three-dimensional position, and based on the data, after deriving in advance the relationship between the position of the marker pattern boundary line on the image when the image is taken by the line sensor and the rotation angle, A rotation angle measurement method comprising: obtaining a boundary line position of the marker pattern from an image photographed by a line sensor; and converting the boundary line position of the marker pattern into the rotation angle based on the relationship . The rotation angle measurement method according to claim 7 , wherein a relationship between a marker pattern boundary line position of the marker and a rotation angle of the rotating body is uniquely associated. The rotation angle measurement method according to claim 7 or 8 , wherein a relationship between a marker line boundary line position of the marker and a rotation angle of the rotating body is directly proportional. The line sensor is positioned so that the rotation axis of the rotation body and the optical axis of the line sensor are parallel to each other and the marker and the line sensor face each other with respect to the rotation body on which the marker is installed on the upper surface or the bottom surface. Placed in
The marker is the rotational angle measuring method according to any one of claims 7 to 9, characterized in that it has a boundary line of the spiral marker pattern. With respect to the rotating body on which the marker is installed on the side surface, the line sensor is arranged such that the rotation axis of the rotating body and the optical axis of the line sensor are perpendicular, and the rotation axis of the rotating body and the imaging line of the line sensor are parallel. Arranged so that the position
The marker is the rotational angle measuring method according to any one of claims 7 to 9, characterized in that it has a boundary line of the helical marker pattern.

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