JP2018159603A - Projector, measuring device, system, and method for manufacturing goods - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection that suppresses influences due to the fluctuation of projected pattern light.SOLUTION: Provided is a projector 110 comprising a pattern light generation unit 113 for generating line pattern light from the light emitted from a plurality of light sources discretely arranged from each other and a projection optical system 114 for projecting the generated line pattern light to an inspection object W, the projector 110 further including a measurement unit 115 for measuring a value relating to the optical intensity of light on the pupil surface of the projection optical system 114 and a control unit 200 for adjusting the light amount of the light emitted from the plurality of light sources on the basis of the measured value obtained by the measurement unit 115, the control unit 200 adjusting the light amount of the light emitted from the plurality of light sources so that the measured values of a plurality of divided areas obtained by dividing the pupil surface into a plurality in the cyclic direction (direction x) of the light pattern light come close to each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a projection device, a measurement device, a system, and an article manufacturing method.

  As a device for recognizing an arrangement (for example, at least one of a position and a posture) of an object in a non-contact manner, a measurement device using a pattern projection method is known. In the pattern projection method, an object on which pattern light is projected is picked up, and distance information at each pixel position is calculated based on the principle of triangulation using the picked-up image to obtain the arrangement of the object. The distance information is calculated by approximating a projection optical system that projects pattern light and an imaging optical system that captures an object to a pinhole camera model.

  For example, when a plurality of LEDs are used as the light source of the projection optical system, if there is a variation in the amount of light between the LEDs, unevenness in the light intensity distribution of the pattern light occurs at the pupil of the projection optical system, resulting in an image shift of the projection pattern To do. When such uneven light intensity distribution occurs, the accuracy of the distance information calculated by approximation of the pinhole camera model decreases. As for the uniform light intensity distribution, there is an illuminating device including a light guide that emits light having a uniform intensity distribution from the exit by reflecting light entering from the entrance multiple times on the inner surface (Patent Document 1). A calibration device for calibrating a non-pinhole optical system is also known (Patent Document 2).

JP 2003-26295 A JP 2014-131091 A

  However, in the technique of Patent Document 1, depending on the number of LEDs or the amount of variation in the amount of light between LEDs, for example, it is necessary to increase the length of the light guide path, which leads to an increase in size and cost of the device. . Further, since the amount of light emitted from the LED can change with time, the calibration device of Patent Document 2 needs to be calibrated periodically, which can be disadvantageous in terms of measurement efficiency.

  For example, an object of the present invention is to provide a projection apparatus that suppresses the influence of fluctuations in projected pattern light.

  In order to solve the above-described problems, the present invention provides a pattern light generation unit that generates line pattern light from light emitted from a plurality of light sources, and a projection optical system that projects the generated line pattern light onto a test object. A measurement unit that measures a value related to the light intensity of light on the pupil plane of the projection optical system, and a control unit that adjusts the amount of light based on the measurement value obtained by the measurement unit. And the control unit adjusts the amount of light so that the light intensity between a plurality of divided areas obtained by dividing the pupil plane in the periodic direction of the line pattern light generated by the pattern light generation unit is made closer. To do.

  ADVANTAGE OF THE INVENTION According to this invention, the projection apparatus which suppresses the influence by the fluctuation | variation of the pattern light to project can be provided.

It is the schematic which shows the structure of the measuring device which concerns on embodiment. It is a schematic diagram which shows the light intensity distribution in the pupil plane of each light radiate | emitted from the several light source. It is a schematic diagram which shows the example of the arrangement | sequence of several light sources (effective light source distribution). It is a figure which represents typically the light intensity distribution of a state without the light quantity difference between division areas. It is a figure showing symmetrical pupil intensity distribution before and behind a condensing position. It is a figure which represents typically light intensity distribution in case there exists a light quantity difference between division areas. It is a figure showing the asymmetric pupil intensity distribution before and behind a condensing position. It is a figure explaining the mode of a pinhole model and an optical system. It is a figure which shows the control system containing the holding | gripping apparatus with which the measuring device was equipped.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a schematic diagram illustrating a configuration of a measurement apparatus according to the present embodiment. The measurement device includes a measurement head 100 and a control unit 200. The measurement head 100 includes a projection device 110 and an imaging device 120. The projection device 110 projects the pattern light P onto the test object W. As shown in FIG. 1, the pattern light P of the present embodiment is periodic line pattern light in which bright portions formed by bright lines and dark portions formed by dark lines are alternately arranged.

  The projection apparatus 110 includes a light emitting unit 111 having a plurality of light sources that are discretely arranged, an optical integrator 112, a pattern light generation unit 113, a projection optical system 114, and a measurement unit 115. The projection device 110 may include an optical element that changes the optical path (for example, a plane mirror, a prism, and the like) and an optical element that efficiently guides the light to the optical integrator 112 (for example, a condensing mirror). As the plurality of light sources included in the light emitting unit 111, light emitting elements such as LED chips, LED arrays in which LED chips are one-dimensionally arranged, and LED matrices in which two-dimensionally are arranged can be used.

  The optical integrator 112 adjusts the light intensity distribution of the light emitted from the light emitting unit 111. In the present embodiment, as the optical integrator 112, a rod integrator whose cross-sectional shape viewed from the light incident end face side is symmetric with respect to the center of the incident end face is used. In addition, an optical integrator whose cross-sectional shape is symmetric with respect to the center of the incident end face (for example, circular or rectangular) can be used.

  In the present embodiment, the optical integrator 112 makes the light intensity distribution uniform and illuminates the pattern light generation unit 113 uniformly. Note that the optical integrator 112 may intentionally make the light intensity distribution non-uniform, for example, by making the light intensity at the periphery of the angle of view greater than the light intensity at the center of the angle of view. The light intensity distribution is adjusted by adjusting the distance between the light source of the light emitting unit 111 and the incident end face of the optical integrator 112, the relationship between the area of the incident end face and the area of the light emitting face of the light source, or the length of the optical integrator 112 and the area of the incident end face. This can be done by adjusting the ratio. For example, if a rod integrator having a short length with respect to the area of the incident end face of the rod integrator is used, the light intensity at the periphery of the angle of view can be made larger than the center of the angle of view.

  The pattern light generator 113 receives the light emitted from the optical integrator 112 and generates line pattern light. Here, the periodic direction of the line of the line pattern light generated by the pattern light generating unit 113 is the x axis, and the direction perpendicular to the periodic direction of the line of the line pattern light (the direction in which the line extends) is the y axis. The direction orthogonal to is the z-axis. For example, when the projection device 110 includes an optical element that bends the optical path, the periodic direction of the line pattern light generated by the pattern light generation unit 113 and the periodic direction of the pattern light P projected onto the test object W are as follows: May not match. In the present embodiment, for the sake of simplicity of description, the periodic directions of both are made coincident. The z axis is a direction parallel to the optical axis of the projection optical system 114 of the projection apparatus 110. The xz plane is a plane including the object side principal point of the projection optical system 114, the image side principal point and the object point of the imaging optical system 121. Further, the pattern light generation unit 113 can also generate uniform light.

  As the pattern light generation unit 113, a liquid crystal element, DMD (digital mirror device) or the like is used, and the pattern light generation unit 113 can set an arbitrary pattern. In addition, as the pattern light generation part 113, the glass plate which produces | generates the predetermined pattern light by which the predetermined pattern was drawn can also be used. Further, the pattern light P is not limited to the line pattern as in the present embodiment, and may be a dot line pattern or a circular pattern array in which the line is interrupted. The wavelength of the pattern light P is not limited to one, and a plurality of wavelengths may be used by using a plurality of types of LEDs.

  The projection optical system 114 is an optical system that projects the pattern light generated by the pattern light generation unit 113 onto the test object W. In the present embodiment, the periodic direction of the line of the pattern light P projected onto the object W is matched with the periodic direction of the line pattern light generated by the pattern light generator 113. The same applies to the direction perpendicular to the periodic direction.

  The measurement unit 115 measures a value related to the light intensity on the pupil plane of the projection optical system 114. For example, when the measuring unit 115 is disposed in the vicinity of the light emitting unit 111 as shown in FIG. 1, the amount of light emitted from the light emitting unit 111 is measured. The measurement unit 115 or the control unit 200 can obtain an estimated value of the light intensity on the pupil plane of the projection optical system 114 from the measured light quantity. The estimated value of the light intensity can be obtained, for example, by previously storing the relationship between the light amount and the light intensity on the pupil plane in the control unit 200 and referring to the relationship based on the measured light amount. It is also possible to obtain an estimated value of light intensity from the luminance values of pixels constituting a grayscale image to be described later. Further, the measurement unit 115 can measure the light intensity on the pupil plane of the projection optical system 114.

  The imaging device 120 images the test object W on which the pattern light P is projected. The imaging device 120 includes an imaging optical system 121 including an imaging lens, a housing 122, and an image sensor 123 having a light receiving surface. The imaging optical system 121 and the image sensor 123 are disposed inside the housing 122. The image sensor 123 is a photoelectric conversion element such as a CMOS or a CCD, and functions as an imaging unit that receives light of the test object W on the light receiving surface and acquires an image of the test object W.

  Note that the captured image acquired by the imaging device 120 is obtained by imaging the distance image obtained by imaging the test object W on which the line pattern light is projected and the test object W on which uniform light is projected. Including gray images.

  The control unit 200 is a control circuit including, for example, a CPU (processing unit), a memory, and the like, and calculates distance information to the object W from the distance image acquired by the imaging device 120 based on the principle of triangulation. . The control unit 200 controls the amount of light emitted from the light emitting unit 111, generates the shape (line width, etc.) of the pattern light P projected by the projection device 110, the projection timing of the projection device 110, and the imaging device 120. Synchronize with the imaging timing. The measurement apparatus of the present embodiment calculates distance information of the test object W by a spatial encoding method, but may use a phase shift method, a light cutting method, or the like.

  The control unit 200 controls the projection device 110 to project a plurality of types of pattern light P onto the test object W. The control unit 200 controls the imaging device 120 to image the test object W for each pattern light P, and obtain a signal (data) of the captured image. The control unit 200 divides the measurement space from the set values of the bright and dark stripes of the pattern light P and the captured image data for each set value. Then, the control unit 200 determines the pixel position of the pattern light generation unit 113 of the projection device 110 and the pixel position of the image sensor 123 of the imaging device 120 with respect to the object point on the surface of the object W in the measurement space. Associate.

  The control unit 200 calculates the distance (position) of the points on the surface of the object W based on the principle of triangulation using the relationship between the relative position and orientation of the projection device 110 and the imaging device 120 acquired in advance. calculate. In the present embodiment, the distance is calculated using the positions of points in the direction perpendicular to the direction in which the line of the pattern light P extends (= X-axis direction). This calculation is performed for a plurality of points on the surface of the test object W on which the pattern light P is projected, and point cloud data having distance information is acquired. Moreover, the arrangement | positioning (for example, position and attitude | position) of the to-be-tested object W can be calculated | required using distance point cloud data and a 3D-CAD model.

  FIG. 2 is a schematic diagram showing the light intensity distribution on the pupil plane of each light emitted from a plurality of light sources included in the light emitting unit 111 of the projection device 110 according to the present embodiment. In the present embodiment, the pupil plane and the xy plane determined based on the periodic direction of the line pattern light generated by the pattern light generation unit 113 are parallel. The coordinate axis shown in FIG. 2 has the same definition as the coordinate axis. For the sake of simplicity, the influence of the optical integrator 112 is not shown.

  In the present embodiment, the light emitting unit 111 has four light sources 101 to 104. Here, the light sources 101 to 104 use square-shaped surface emitting light sources, and the shape of the light intensity distribution (also referred to as effective light source distribution) on the pupil plane by the light sources 101 to 104 is also square. The edges of the light sources (effective light source distributions) 101 to 104 are parallel to the x axis or the y axis.

  In addition, a plurality of divided regions obtained by dividing the pupil plane by a dividing line L1 including the optical axis c1 of the projection optical system 114 and parallel to the direction (y direction) in which the line of the pattern light P extends are a region a1 and a region a2. And The method of dividing the pupil plane is not limited to this, and the pupil plane may be divided in the periodic direction of the line of the pattern light P.

  FIG. 3 is a schematic diagram illustrating an example of an array of a plurality of light sources. In FIG. 2, the edge of the light source is parallel to the x-axis or y-axis, but in the example shown in FIG. 3, the edges of the light sources 105 to 108 are inclined with respect to the x-axis or y-axis. A plurality of divided regions obtained by dividing the pupil plane along a dividing line L1 including the optical axis c1 of the projection optical system 114 and parallel to the y direction are defined as a region a3 and a region a4.

  FIG. 4 schematically shows the light intensity distribution 601 on the pupil plane in a state where there is no light amount difference between the divided areas of the areas a1 and a2 in FIG. 2 or between the divided areas of the areas a3 and a4 in FIG. ing. The horizontal axis is the x direction of the pupil plane of the projection optical system 114, the origin is the position through which the principal ray of light emitted from the projection optical system 114 passes, and the vertical axis is the light intensity. When there is no light amount difference between the divided areas, the shape of the light intensity distribution 601 is symmetric with respect to the origin.

  FIG. 5 is a diagram showing a light intensity distribution 606 in the vicinity of a light collection position 605 of a light beam having a symmetrical distribution shape with respect to the origin as shown in FIG. A principal ray 604 of the light beam is a light ray determined by an optical system (not shown). The position of the image formed by the light flux changes in a direction connecting the peaks of the light intensity distribution 606. In the case of FIG. 5, the position direction of the image coincides with the traveling direction of the principal ray 604.

  FIG. 6 is a diagram illustrating a light intensity distribution 602 when there is a light amount difference between the divided regions. The light intensity distribution 602 is asymmetric with respect to the origin. FIG. 7 is a diagram showing a light intensity distribution 606 in the vicinity of a light collection position 605 of a light beam having an asymmetric distribution shape with respect to the origin as shown in FIG. The light intensity distribution 606 is asymmetric with respect to the principal ray 604 of the light flux, and the image position direction 607 does not coincide with the traveling direction of the principal ray 604.

  FIG. 8 is a diagram for explaining the influence on the measurement accuracy caused by the light intensity distribution on the pupil plane of the projection optical system becoming asymmetric with respect to the principal ray of the light beam. FIG. 8 shows the pinhole camera model and the projection optical system 114 having the light intensity distribution 602 shown in FIG. 6 together. The light ray passing through the pinhole 608 used in the pinhole camera model corresponds to the principal ray 604 defined by the projection optical system 114. Therefore, if the position direction of the image is on the principal ray, the position can be detected with high accuracy using the pinhole model. However, if the image position direction 607 does not coincide with the chief ray 604, the image position direction 607 does not pass through the pinhole 608 and has a non-pinhole characteristic that cannot be described by the pinhole camera model, resulting in a position detection error. Occurs and the measurement accuracy decreases.

  In other words, even if the amount of light varies between the plurality of light sources, the difference in light intensity between the plurality of divided regions obtained by dividing the pupil plane in the periodic direction (x direction) of the pattern light P is minimized. Is important in suppressing position detection errors.

  As the difference in light intensity, a difference in values such as a total value, an average value, a median value, or a mode value of the light intensity measured in the divided area can be used. In order to reduce the difference in light intensity between the divided regions, the control unit 200 determines the amount of light emitted from the light emitting unit 111 based on the measured value or estimated value of the light intensity of the divided regions obtained by the measuring unit 115. adjust. The adjustment amount of the light amount can be determined based on the relationship between the light amount obtained in advance and the light intensity. Further, the light amount can be adjusted by adjusting the magnitude of the current supplied to the light emitting unit 111. The range in which the current value can be adjusted is determined by the characteristics of the light source included in the light emitting unit 111. The light amount may be adjusted by providing a light shielding unit in the projector 110 and adjusting the light shielding amount. When reducing the difference in light intensity, the light intensity distribution of each of the plurality of divided regions may be aligned with a high light intensity or may be aligned with a low light intensity.

  As described above, by adjusting the amount of light, it is possible to suppress the influence of fluctuations in the projected pattern light, and to suppress the position detection error of the measuring apparatus. The amount of light is adjusted by adjusting the input current to the light source, and there is no need to use an expensive optical integrator or a large optical integrator. Furthermore, even if the variation in the amount of light between the light sources changes with time, no complicated calibration work is required.

  The pattern light P in the above description assumes black and white binary stripes, but is not limited to this, and may be stripes having a value greater than binary values or stripes of a plurality of other colors. Further, the number, shape, and arrangement of the light emitting units are not limited to the above description.

  Regarding the light amount control, a plurality of light sources may be individually controlled in units of light sources, or a plurality of light sources may be classified into a plurality of groups and controlled in units of groups. The light intensity may be measured by turning on the light sources one by one or by turning them on in groups.

(Embodiment related to article manufacturing method)
The above-described measuring device can be used while being supported by a certain support member. In the present embodiment, as an example, a control system that is provided and used in a robot arm 400 (grip device) as shown in FIG. 9 will be described. The measuring device 500 projects the pattern light onto the test object W placed on the support table T to capture an image. Then, the control unit (not shown) of the measurement device 500 or the arm control unit 310 that has acquired the image data output from the control unit (not shown) of the measurement device 500 determines the position of the object W and The posture is obtained, and the arm control unit 310 obtains information on the obtained position and posture. The arm control unit 310 controls the robot arm 400 by sending a drive command to the robot arm 400 based on the position and orientation information (measurement result). The robot arm 400 holds the object W with a robot hand or the like (gripping part) at the tip and moves it by translation or rotation. Further, by assembling (assembling) the test object W to other parts by the robot arm 400, an article composed of a plurality of parts, for example, an electronic circuit board or a machine can be manufactured. Further, an article can be manufactured by processing (processing) the moved specimen W. The arm control unit 310 includes an arithmetic device such as a CPU and a storage device such as a memory. A control unit that controls the robot may be provided outside the arm control unit 310. Further, the measurement data measured by the measurement apparatus 500 and the obtained image may be displayed on the display unit 320 such as a display.

(Other embodiments)
As mentioned above, although embodiment of this invention has been described, this invention is not limited to these embodiment, A various change is possible within the range of the summary.

DESCRIPTION OF SYMBOLS 100 Measuring head 101-108 Light source 110 Projection apparatus 111 Light emission part 113 Pattern light generation part 114 Projection optical system 115 Measurement part 120 Imaging device 200 Control part

Claims (12)

A projection having a pattern light generation unit that generates line pattern light from light emitted from a plurality of light sources that are discretely arranged, and a projection optical system that projects the generated line pattern light onto a test object A device,
A measurement unit that measures a value related to the light intensity of the light on the pupil plane of the projection optical system;
A control unit that adjusts the amount of light emitted from the plurality of light sources based on the measurement value obtained by the measurement unit;
The controller is
Adjusting the amount of light emitted from the plurality of light sources so that the measurement values of the plurality of divided regions obtained by dividing the pupil plane into a plurality of parts in the periodic direction of the line pattern light are close to each other;
A projection apparatus characterized by that. The measurement unit measures the light intensity on the pupil plane,
The control unit is configured to determine whether the light intensity measured by each of the measurement units in the plurality of divided regions is based on a relationship between a light amount emitted from the plurality of light sources and the light intensity on the pupil plane. Adjusting the amount of light emitted from the plurality of light sources so as to approach each other;
The projection apparatus according to claim 1. The measurement unit measures the amount of light emitted from the plurality of light sources,
The control unit is configured to determine the light intensity in each of the plurality of divided regions from the measured light amount based on a relationship between the light amount of light emitted from the plurality of light sources and the light intensity on the pupil plane. Obtaining an estimated value, and adjusting the amount of light emitted from the plurality of light sources so that the estimated values of the plurality of divided regions approach each other;
The projection apparatus according to claim 1, wherein: The measurement unit performs the measurement in a state where any one of the plurality of light sources emits the light,
The control unit controls the plurality of light sources in units of the light source so that the light intensity approaches based on the obtained measurement value.
The projection apparatus according to claim 1, wherein the projection apparatus is a projection apparatus. The measurement unit performs the measurement in a state where any one of the plurality of light sources classified into a plurality of groups emits the light,
The control unit controls the plurality of light sources in units of the group so that the light intensity approaches based on the obtained measurement value.
The projection apparatus according to claim 1, wherein the projection apparatus is a projection apparatus.   The projection apparatus according to claim 1, wherein the control unit adjusts the light amount by adjusting a magnitude of a current supplied to the plurality of light sources. Including a light shielding portion disposed in an optical path from the plurality of light sources to the pupil plane,
7. The projection apparatus according to claim 1, wherein the control unit adjusts a light shielding amount by the light shielding unit so that the light intensities between the plurality of divided regions are made closer to each other. .   The projection apparatus according to claim 1, wherein the plurality of light sources are a plurality of LEDs arranged discretely from each other. A projection device according to any one of claims 1 to 8,
A measuring apparatus comprising: an imaging device that images the test object. The pattern light generation unit of the projection device generates uniform light,
The imaging device images the test object onto which the generated uniform light is projected by the projection optical system, and acquires a grayscale image,
The measurement unit obtains a luminance value of a pixel constituting the acquired grayscale image,
The controller is
Obtaining an estimated value of the light intensity in each of the plurality of divided regions based on the luminance value, and adjusting the light amount so as to bring the estimated value between the plurality of divided regions closer to each other;
The measuring apparatus according to claim 9. The measuring device according to claim 9 or 10,
A robot that holds and moves the object,
The system in which the robot holds the object based on the measurement result of the object output from the measurement device. A method for manufacturing an article, comprising:
An object is measured using the measuring device according to claim 9 or 10,
An article is manufactured by processing the measured object.
A method for manufacturing an article.

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