3D Camera

Abstract

To provide a three-dimensional camera capable of inspecting an object to be photographed by one-time scanning by eliminating the influence of occurrence of blind spot and multiple reflection of laser.SOLUTION: A three-dimensional camera 100 includes a first light projecting unit 102, a second light projecting unit 103, a first imaging unit 104, and a second imaging unit 105. The first light projecting unit 102 and the second light projecting unit 103 alternately emit light for three-dimensional distance measurement, and the first imaging unit 104 and the second imaging unit 105 capture respectively images of the light for three-dimensional distance measurement that is reflected by an object to be imaged.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a three-dimensional camera of the light-section type used in three-dimensional inspection such as a welding inspection system. [Background technology]

[0002] In three-dimensional inspections such as welding inspection systems, three-dimensional cameras that use the light-cutting method, which irradiates a line-shaped (slit-shaped) laser light onto the object to be photographed (workpiece) and obtains the reflected light as height data (profile), are widely used. Three-dimensional cameras that use this type of light-cutting method measure the distance to the object to be photographed based on the principle of triangulation while moving the three-dimensional camera or the object to be photographed. With conventional 3D cameras, when photographing uneven workpieces such as welded workpieces, blind spots (due to pits or spatters when the photographed object is a welded workpiece) as shown by hatching in Fig. 12 and Fig. 13 occur, which causes problems such as false detection or non-detection during inspection. To solve this problem, measures have been taken such as changing the viewpoint of the 3D camera and performing multiple scans. However, multiple scans by changing the viewpoint of the 3D camera require inspection time according to the number of scans, which causes the takt time to increase. In addition, teaching the robot (the task of teaching the robot the scanning position) is also cumbersome. Furthermore, when the object to be photographed is, for example, metal, even if multiple scans are performed, there is a problem that the height information cannot be obtained correctly when the laser light is multiple-reflected as shown by reference numeral 363 in FIG. 14 . Therefore, for example, as shown in FIG. 11, there exist three-dimensional cameras equipped with multiple imaging units. The three-dimensional camera 300 shown in FIG. 11 includes a light projecting unit 301 that projects laser slit light, a first imaging unit 302, and a second imaging unit 303. Such a 3D camera makes it possible to obtain profiles from different viewpoints with a single scan. However, since there is only one light projecting unit 301 in the center, it is not possible to eliminate the effects of blind spots and multiple reflections of the laser light. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, an object of the present invention is to provide a three-dimensional camera that can eliminate the effects of blind spots and multiple reflections of a laser and can inspect an object to be photographed with a single scan. [Means for solving the problem]

[0004] In order to solve the above problems, the three-dimensional camera of the present invention is a three-dimensional camera comprising a light-projecting unit that emits light for three-dimensional distance measurement toward an object to be photographed, and an imaging unit that captures the light reflected from the object to be photographed, wherein the three-dimensional camera comprises a first light-projecting unit and a second light-projecting unit as the light-projecting unit, and a first imaging unit and a second imaging unit as the imaging unit, and the first light-projecting unit and the second light-projecting unit alternately emit light, and the first imaging unit and the second imaging unit respectively capture the light that is alternately emitted from the first light-projecting unit and the second light-projecting unit and reflected from the object to be photographed.

[0005] Furthermore, in the three-dimensional camera of the present invention, when the first light-projecting unit and the first imaging unit are grouped as a first group with the first light-projecting unit in front, and the second light-projecting unit and the second imaging unit are grouped as a second group with the second light-projecting unit in front, the first group and the second group are arranged adjacent to each other on the left and right, with the front and back reversed with respect to the movement direction of the three-dimensional camera or the movement direction of the object to be photographed, and the first light-projecting unit and the second light-projecting unit may be arranged in a position closer to the center than the first imaging unit and the second imaging unit.

[0006] In the three-dimensional camera according to the present invention, the light emitted from the first light-projecting unit and the second light-projecting unit may be laser slit light whose laser planes are not parallel to each other.

[0007] In addition, the three-dimensional camera of the present invention may be configured so that the optical axes of the first light-projecting unit and the second light-projecting unit and the imaging axes of the first imaging unit and the second imaging unit are angled inward when the three-dimensional camera is viewed from the front. Effect of the Invention

[0008] According to the present invention, it is possible to provide a three-dimensional camera that can eliminate the effects of blind spots and multiple reflections of a laser and can inspect an object to be photographed with a single scan. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view of a three-dimensional camera according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a configuration diagram of a processing unit of a three-dimensional camera according to an embodiment of the present invention. [Diagram 3] 5A to 5C are perspective views illustrating the operation of a three-dimensional camera according to an embodiment of the present invention. [Figure 4] 5A to 5C are perspective views illustrating the operation of a three-dimensional camera according to an embodiment of the present invention. [Diagram 5] 5A to 5C are side views illustrating the operation of a three-dimensional camera according to an embodiment of the present invention. [Figure 6] FIG. 2 is a bottom view of the three-dimensional camera according to the embodiment of the present invention. [Figure 7] FIG. 2 is a bottom view of the three-dimensional camera according to the embodiment of the present invention. [Figure 8] 5A to 5C are front views illustrating the operation of a three-dimensional camera according to an embodiment of the present invention. [Figure 9] 5A to 5C are side views illustrating the operation of a three-dimensional camera according to an embodiment of the present invention. [Figure 10] 4 is an operation flow of a three-dimensional camera according to an embodiment of the present invention. [Figure 11] FIG. 1 is a bottom view showing an example of a conventional three-dimensional camera. [Figure 12] FIG. 1 is a front view showing an example of a blind spot that occurs in a conventional three-dimensional camera. [Figure 13]FIG. 1 is a side view showing an example of a blind spot that occurs in a conventional three-dimensional camera. [Figure 14] FIG. 11 is a perspective view showing an example of multiple reflection of laser light. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The configuration of a three-dimensional camera according to the present invention will be described below. Note that the same reference numerals are used throughout the drawings to denote the same or equivalent parts.

[0011] First, a three-dimensional camera 100 according to the present invention will be described with reference to FIG.

[0012] 1 is a perspective view showing a three-dimensional camera 100. Here, the y direction indicates the movement direction of the three-dimensional camera 100 (or the object to be photographed). As shown in the figure, the three-dimensional camera 100 includes a first light projecting unit 102, a second light projecting unit 103, a first imaging unit 104, and a second imaging unit 105 inside a housing 101.

[0013] The first light-projecting unit 102 and the second light-projecting unit 103 are light-projecting units that emit light for three-dimensional distance measurement to the object to be photographed, and are configured, for example, with a semiconductor laser (not shown) and a lens (not shown). Here, the first light-projecting unit 102 and the second light-projecting unit 103 are configured to alternately emit light for three-dimensional distance measurement to the object to be photographed in order to prevent mutual interference of light. The light emitted by the first light-projecting unit 102 and the second light-projecting unit 103 is slit light, and can be, for example, laser slit light. Hereinafter, the light emitted by the first light-projecting unit 102 and the second light-projecting unit 103 will be described as laser slit light.

[0014] The first imaging unit 1004 and the second imaging unit 105 are imaging units (light receiving units) that capture the laser slit light reflected from the object to be photographed, and are composed of, for example, lenses (reference numerals 128 and 129) and an imaging element (not shown) such as a CMOS. Here, both the first imaging unit 104 and the second imaging unit 105 capture the laser slit light emitted from the first light projecting unit 102 and reflected from the object to be photographed, and the laser slit light emitted from the second light projecting unit 103 and reflected from the object to be photographed, respectively. That is, both the first imaging unit 104 and the second imaging unit 105 capture the laser slit light reflected from the object to be photographed when the first light projecting unit 102 emits the laser slit light to the object to be photographed, and capture the laser slit light reflected from the object to be photographed when the second light projecting unit 103 emits the laser slit light to the object to be photographed.

[0015] Next, the configuration of the three-dimensional camera 100 according to the present invention will be described with reference to FIG.

[0016] 2 is a diagram showing the configuration of the processing unit 120 of the three-dimensional camera 100. The processing unit 120 may be integrated with the three-dimensional camera 100 by being built into the housing 101 of the three-dimensional camera 100, or a part or the whole of the processing unit 120 may be configured by an external computer device or the like.

[0017] As shown in the figure, the processing unit 120 includes a storage unit 121, a control unit 122, a light projection control unit 123, a light reception control unit (imaging control unit) 124, a profile acquisition unit 125, a calculation unit 126, and an output unit 127.

[0018] The storage unit 121 is configured with a RAM (random access memory), a ROM (read only memory), a hard disk, or a semiconductor memory, and stores various programs such as a program for performing calculations such as viewpoint conversion and superimposition of profiles.

[0019] The control unit 122 is, for example, a CPU (Central Processing Unit), and various functional units of the processing unit 120 including the calculation unit 126 are realized by the control unit 122 executing a program stored in the storage unit 121. Note that some or all of the various functional units of the processing unit 120 may be realized by hardware such as an electronic circuit.

[0020] The light projection control unit 123 controls the emission timing (irradiation timing) of the laser slit light from the first light projection unit 102 and the second light projection unit 103, the intensity of the laser slit light, etc. Note that the light projection control unit 123 may be integrated into the control unit 122.

[0021] The light reception control unit 124 controls the imaging (light reception) timing of the first imaging unit 104 and the second imaging unit 105. The light reception control unit 124 may be integrated into the control unit 122.

[0022] The profile acquisition section 125 acquires data indicating a profile of the object 130 to be photographed, based on the distribution of the amount of received light acquired by the first imaging section 104 and the second imaging section 105 .

[0023] The calculation unit 126 performs processes such as calculations on the profile data acquired by the profile acquisition unit 125. Here, the calculations include, for example, viewpoint conversion and superimposition of the profiles.

[0024] The output unit 127 outputs the result of the calculation by the calculation unit 126 to an external device (not shown) such as a display. Note that the output unit 127 may be omitted when there is no need to output to an external device such as a display.

[0025] Next, the operation of the three-dimensional camera 100 according to the present invention will be described with reference to FIGS.

[0026] 3 is a perspective view showing a state in which the first light projecting unit 102 emits a laser slit light to the object 130, and the first and second imaging units 104 and 105 capture the laser slit light reflected from the object 130. As shown in the figure, when the first light projecting unit 102 is activated to project the laser slit light 140 onto the object 130, the first imaging unit 104 captures an image (reference symbol 141) of the laser slit light 140 reflected from the object 130, and the second imaging unit 105 captures an image (reference symbol 142) of the laser slit light 140. Note that the arrow indicated by reference symbol 143 indicates the direction of movement of the three-dimensional camera 100 (or the object 130), and the alphabet a indicates the width (horizontal width) of the object 130.

[0027] 4 is a perspective view showing a state in which the second light projecting unit 103 emits a laser slit light to the object 130, and the first imaging unit 104 and the second imaging unit 105 capture the laser slit light reflected from the object 130. As shown in the figure, when the second light projecting unit 103 is activated to project a laser slit light 160 onto the object 130, the first imaging unit 104 captures an image (reference symbol 161) of the laser slit light 160 reflected from the object 130, and the second imaging unit 105 captures an image (reference symbol 162) of the laser slit light 160.

[0028] Next, laser slit light 140 emitted from first light-projecting unit 102 and laser slit light 160 emitted from second light-projecting unit 103 will be described with reference to FIG.

[0029] FIG. 5 is a side view of the three-dimensional camera 100, showing the laser slit light 140 emitted from the first light projector 102 and the laser slit light 160 emitted from the second light projector 103. As shown in the figure, the laser slit light 140 emitted from the first light projector 102 and the laser slit light 160 emitted from the second light projector 103 can be configured so that their laser planes are not parallel to each other. By configuring in this way, the reflection modes of the laser slit light 140 and the laser slit light 160 change, so that the location where multiple reflections appear changes. This makes it possible to distinguish whether multiple reflections are caused in the process of integrating the profile data, and the effects of multiple reflections can be removed. In order to change the reflection mode between the laser slit light 140 and the laser slit light 160, the laser planes of the laser slit light 140 emitted from the first light-projecting unit 102 and the laser slit light 160 emitted from the second light-projecting unit 103 need not be parallel to each other. Therefore, in addition to the configuration shown in FIG. 5, for example, the laser planes may be configured to intersect in a V-shape or X-shape when the three-dimensional camera 100 is viewed from above.

[0030] Next, the arrangement (relative positional relationship) of the first light projecting unit 102, the second light projecting unit 103, the first imaging unit 104, and the second imaging unit 105 will be described with reference to FIGS.

[0031] 6 is a bottom view of the three-dimensional camera 100 according to a first arrangement pattern of the first light projecting unit 102, the second light projecting unit 103, the first imaging unit 104, and the second imaging unit 105. As shown in the figure, the first light projecting unit 102 and the first imaging unit 104 form a first group 200, and the second light projecting unit 103 and the second imaging unit 105 form a second group 201. Here, when the light projecting unit side of each group is the front, the first group 200 and the second group 201 are arranged so as to be inverted (i.e., switched) in the front-rear direction with respect to the moving direction (reference numeral 143) of the three-dimensional camera 100 (or the photographing object 130) and adjacent to each other on the left and right. In addition, when the position indicated by the reference numeral 202 is the center of the three-dimensional camera 100, the first light projecting unit 102 and the second light projecting unit 103 are arranged closer to the center than the first imaging unit 104 and the second imaging unit 105.

[0032] 7 is a bottom view of the three-dimensional camera 100 according to the second arrangement pattern of the first light projecting unit 102, the second light projecting unit 103, the first imaging unit 104, and the second imaging unit 105. As shown in the figure, the first light projecting unit 102 and the first imaging unit 104 form a first group 200, and the second light projecting unit 103 and the second imaging unit 105 form a second group 201. Here, when the light projecting unit side of each group is the front, the first group 200 and the second group 201 are arranged so as to be inverted (i.e., switched) in the front-rear direction with respect to the moving direction (reference numeral 143) of the three-dimensional camera 100 (or the photographing object 130) and adjacent to each other on the left and right. In addition, when the position indicated by the reference numeral 202 is the center of the three-dimensional camera 100, the first imaging unit 104 and the second imaging unit 105 are arranged at a position closer to the center than the first light projecting unit 102 and the second light projecting unit 103.

[0033] The arrangement of the first light projecting unit 102, the second light projecting unit 103, the first imaging unit 104, and the second imaging unit 105 may be either the first arrangement pattern or the second arrangement pattern described above, but the first arrangement pattern has an advantage over the second arrangement pattern in that it is easier to align the images (profile data) captured by the two imaging units when combining them. This is because the laser plane is used as the reference when combining the images (profile data) captured by the two imaging units.

[0034] In addition, by making the distance between the center of the first light-projecting unit 102 and the first imaging unit 104 and the center of the second light-projecting unit 103 and the second imaging unit 105 (letter b in Figures 6 and 7) greater than the width of the object to be photographed 130 (letter a in Figures 3 and 4), or by making it greater than the field of view of the first imaging unit 104 and the second imaging unit 105, the occurrence of blind spots in the left-right direction (width direction) can be suppressed.

[0035] Next, with reference to Figures 8 and 9, we will explain the optical axis of the laser slit light emitted from the first light-emitting section 102 and the second light-emitting section 103, and the imaging axis (center of the imaging area) of the first imaging section 104 and the second imaging section 105.

[0036] FIG. 8 is a front view of the three-dimensional camera 100, and shows the laser slit light 140 emitted from the first light projector 102, the laser slit light 160 emitted from the second light projector 103, the imaging axis 240 of the first imaging unit 104, and the imaging axis 241 of the second imaging unit 105. As shown in the figure, the first light projector 102 and the second light projector 103 can be provided so that the optical axis of the first light projector 102 and the optical axis of the second light projector 103 have an inward angle. By providing the first light projector 102 and the second light projector 103 in this way, the width of the overlap between the laser slit light 140 and the laser slit light 160 in the left-right direction is expanded, and a larger width (alphabetical letter a in FIG. 3 and FIG. 4) of the object 130 to be photographed can be inspected. In addition, the first imaging unit 104 and the second imaging unit 105 can be provided so that the imaging axis 240 and the imaging axis 241 have an inward angle. By providing the first imaging section 104 and the second imaging section 105 in this manner, it is possible to accommodate a subject 130 to be photographed having a larger width (the letter a in FIGS. 3 and 4) in the imaging area.

[0037] FIG. 9 is a side view of the three-dimensional camera 100, and shows the laser slit light 140 emitted from the first light projector 102, the laser slit light 160 emitted from the second light projector 103, the imaging axis 240 of the first imaging unit 104, and the imaging axis 241 of the second imaging unit 105. As shown in the figure, the first light projector 102 and the second light projector 103 can be provided so that the optical axis of the first light projector 102 and the optical axis of the second light projector 103 have an inward angle. By providing the first light projector 102 and the second light projector 103 in this way, the deviation of the positions at which the laser slit light 140 and 160 are reflected on the shooting target 130 is reduced. This reduces errors in the composition of profile data even when the moving speed of the robot cannot be completely traced due to variations in the moving speed. In addition, the first imaging unit 104 and the second imaging unit 105 can be provided so that the imaging axis 240 and the imaging axis 241 have an inward angle. By providing the first imaging section 104 and the second imaging section 105 in this manner, a profile is formed at a position closer to the center of the imaging area.

[0038] Next, the flow of operations of the three-dimensional camera 100 according to the present invention will be described with reference to FIG.

[0039] 10 is a flow diagram showing the flow of the operation of the three-dimensional camera 100. First, in step S280, the light-projection control unit 123 operates the first light-projection unit 102 to emit the laser slit light 140. Next, in step S281, the light-reception control unit 124 operates the first imaging unit 104 and the second imaging unit 105 to capture an image of the laser slit light 140 emitted from the first light-projection unit 102 and reflected by the shooting target 130. Next, in step S282, the light-projection control unit 123 causes the first light-projection unit 102 to end and stop emitting the laser slit light 140. Next, in step S283, the light-projection control unit 123 operates the second light-projection unit 103 to emit the laser slit light 160. Next, in step S284, the light-receiving control unit 124 operates the first imaging unit 104 and the second imaging unit 105 to capture an image of the laser slit light 160 emitted from the second light-projecting unit 103 and reflected by the object to be photographed 130. Next, in step S285, the light-projecting control unit 123 causes the second light-projecting unit 103 to end and stop emitting the laser slit light 160. Next, in step S286, the control unit 122 determines whether or not photographing of the object to be photographed 130 has been completed. If it is determined in step S286 that photographing has been completed, the operation of the three-dimensional camera is terminated, and if it is determined in step S286 that photographing has not been completed, the process returns to step S280 and the operation of the three-dimensional camera 100 continues. In addition, data such as the distribution of received light amounts acquired by the first imaging unit 104 and the second imaging unit 105 in steps S281 and S284 may be acquired at any time by the profile acquisition unit 125 in steps S281 and S284, or may be acquired collectively by the profile acquisition unit 125 in step S284.

[0040] In generating each profile from the obtained image, since there are multiple laser slit beams, profiles with different coordinates are obtained for the number of laser slit beams. Here, since the three-dimensional camera 100 or the photographed object 130 moves to generate a three-dimensional shape, the viewpoint of each of the obtained profiles is converted to a profile based on the center of the camera. When the profiles after the viewpoint conversion are superimposed, it is easy to distinguish the profile due to multiple reflections from the correct profile, since the profile can only be obtained by one camera. Even if the correct profile can only be obtained by one camera due to specular reflection, it is easy to distinguish whether it is due to multiple reflections from the front, back, left and right positional relationship.

[0041] The 3D camera 100 according to the present invention, which has the configuration and operation described above, can reduce tact time by scanning only once, whereas conventional 3D cameras require multiple imaging (scanning) to reduce blind spots. In addition, the effect of multiple reflections is eliminated, which contributes to improving the performance of the inspection device.

[0042] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0043] For example, the three-dimensional camera 100 according to the present invention can be used to inspect the presence and absence of parts such as bolts, rather than welding inspection. [Explanation of symbols]

[0044] 100 3D Camera 101 Case 102 First light projection section 103 Second light projection unit 104 First imaging unit 105 Second imaging unit 120 Processing section 121 Storage section 122 Control section 123 Light projection control section 124 Light receiving control section 125 Profile Acquisition Unit 126 Arithmetic section 127 Output section 128 Lens 129 Lens 130 Photographing subject 140 Laser Slit Light 141 Reflected light 142 Reflected light 143 Direction of movement (forward / backward) 160 Laser Slit Light 161 Reflected light 162 Reflected light 200 First Group 201 Second Group 202 Center 240 Imaging axis 241 Imaging axis 300 3D Camera 301 Light projector 302 First imaging unit 303 Second Imaging Unit 320 Imaging unit 321 Photographed Objects 322 Imaging area (camera field of view) 324 Blind spot 340 3D Camera 341 Photographed Objects 342 Laser Slit Light 343 Imaging axis 360 Shooting Object 361 Welding 362 Laser Slit Light 363 Multiple reflections of laser slit light

Claims

1. A three-dimensional camera including a light projecting unit that projects light for three-dimensional distance measurement onto a photographing object, and an imaging unit that images the light reflected by the photographing object, the three-dimensional camera comprising: The light-projecting unit includes a first light-projecting unit and a second light-projecting unit, The imaging unit includes a first imaging unit and a second imaging unit, the first light-emitting unit and the second light-emitting unit alternately emit the light, the first imaging unit and the second imaging unit respectively capture images of the light alternately emitted from the first light projecting unit and the second light projecting unit and reflected by the object to be photographed; When the first light-projecting unit and the first imaging unit are grouped together in a first group with the first light-projecting unit in front, and the second light-projecting unit and the second imaging unit are grouped together in a second group with the second light-projecting unit in front, A three-dimensional camera in which the first group and the second group are arranged adjacent to each other on the left and right, with the front and back reversed with respect to the movement direction of the three-dimensional camera or the movement direction of the object to be photographed, and the first light-projecting unit and the second light-projecting unit are arranged at a position closer to the center than the first imaging unit and the second imaging unit.

2. 2. The three-dimensional camera according to claim 1, A three-dimensional camera, wherein the light emitted from the first light-projecting unit and the second light-projecting unit is laser slit light whose laser planes are not parallel to each other.

3. 3. The three-dimensional camera according to claim 2, A three-dimensional camera, wherein the optical axes of the first light-projecting unit and the second light-projecting unit and the imaging axes of the first imaging unit and the second imaging unit are angled inward when the three-dimensional camera is viewed from the front.

Images