JP7074617B2 - Shooting timing control device, imaging system and imaging method - Google Patents

Description

The present invention relates to imaging performed under cyclically fluctuating ambient light, particularly control of imaging timing in such imaging.

High-speed imaging devices are used for inspection of various products and visual sensors for robots. In such an image pickup device, the exposure time is short, for example, about 1 ms. Therefore, when the ambient light in the space where the image pickup is performed fluctuates periodically, such as under certain indoor lighting, it can be obtained by the timing of photographing. The brightness of the image varies.

To solve this problem, Patent Document 1 describes an image from the relationship between the field frequency of photography and the flicker frequency of a light source for the purpose of suppressing the flicker of a high-speed camera that performs high-speed photography with a phosphorescent time shorter than the blinking cycle of illumination. A flicker that obtains the number of shots M per period in which the signal level fluctuates, stores the difference between the signal level for the M field and the average value, and corrects the signal level using the information before the M field for each shot. Suppressors are described.

Japanese Unexamined Patent Publication No. 2013-187603

However, the method described in Patent Document 1 is premised on continuous shooting at a constant field frequency, and when shooting is performed each time as necessary or when continuous shooting is performed at non-constant intervals. Cannot be used. Further, since the flicker cycle is detected from the captured image, it is not possible to detect the flicker whose cycle is shorter than the imaging time.

The present invention has been made in consideration of the above, and is an imaging timing control device, an imaging system, and an imaging method that can suppress variations in brightness between images even when imaging is performed under cyclically fluctuating ambient light. The purpose is to provide.

The shooting timing control device of the present invention is a shooting timing control device used together with an image pickup device that shoots under ambient light that fluctuates periodically, and is a light amount sensor that measures the amount of ambient light and the light amount sensor. Analysis of the periodic fluctuation of the intensity of the ambient light based on the measured value according to the above, the exposure start phase in the periodic fluctuation is determined, and the exposure start instruction for starting the exposure in accordance with the exposure start phase is captured. It has an analysis unit that transmits to the device.

Here, the exposure start instruction indicates the timing at which the exposure should be started to the image pickup device, and the image pickup device receives the instruction that the image pickup device that has received the instruction should immediately start the exposure. It is a concept that includes both those that should wait for the specified time and then start the exposure. With this configuration, even if the intensity of the ambient light fluctuates periodically, it is possible to suppress the variation in brightness between the images captured by the image pickup apparatus.

Preferably, the photographing timing control device is configured as a device separate from the image pickup device, and is used in connection with the image pickup device. As a result, the shooting timing control device can be used by connecting to a commercially available FA camera or the like for automating the production process, and the versatility of the shooting timing control device is enhanced.

The image pickup system of the present invention includes the shooting timing control device and the image pickup device that starts exposure according to the exposure start instruction.

Preferably, the image pickup device instructs the image pickup device to end the exposure.

Preferably, the image pickup system has an image processing unit that performs image processing using the image captured by the image pickup device. In this case, more preferably, the image pickup device is a three-dimensional measurement device having a built-in image processing unit of the image pickup target.

Alternatively, the image pickup device is preferably an image pickup device that transfers the captured image to an image processing device.

Preferably, the image pickup device is a stereo camera having a plurality of image pickup units. As a result, when the image pickup device has an image processing unit, the image pickup device can be a stereoscopic three-dimensional measurement device, and when the image pickup device does not have an image processing unit, the image pickup device which is a stereo camera can be used. By transferring the image to the image processing device of the above, three-dimensional measurement by the stereo method becomes possible.

Alternatively, preferably, the image pickup apparatus includes a pattern projection unit that projects a pattern onto an object, one or more image pickup units that image the object on which the pattern is projected, and the pattern projection unit and the image pickup unit. It may have a control unit to control. As a result, when the image pickup device has an image processing unit, the image pickup device can be used as a pattern projection type three-dimensional measurement device, and when the image pickup device does not have an image processing unit, another image processing from the image pickup device can be performed. By transferring the image to the device, three-dimensional measurement by the pattern projection method becomes possible.

The imaging method of the present invention includes an ambient light analysis step for analyzing periodic fluctuations in the intensity of ambient light, a step for determining an exposure start phase in the periodic fluctuations in the intensity of the analyzed ambient light, and the ambient light. It has an imaging step of starting exposure when the exposure start phase is reached.

According to the imaging timing control device, the imaging system, or the imaging method of the present invention, the exposure is started when the ambient light reaches a predetermined phase of the periodic fluctuation, so that the imaging is performed under the cyclically varying ambient light. However, the variation in brightness between images taken at different times is suppressed.

It is a figure which shows the structure of the image pickup system of 1st Embodiment. It is a figure which shows the flow of operation of the image pickup system of 1st Embodiment. It is a figure for demonstrating the analysis of the periodic fluctuation of the ambient light by the image pickup system of 1st Embodiment, and the setting of the phase which starts the exposure. It is a figure for demonstrating the method of monitoring the change of the intensity of ambient light by the image pickup system of 1st Embodiment, and determining the timing of exposure. It is a figure which shows the structure of the image pickup system of 2nd Embodiment. It is a figure which shows the structure of the image pickup system of 3rd Embodiment. It is a figure which shows the flow of operation of the image pickup system of 3rd Embodiment. It is a figure for demonstrating the relationship between the periodic fluctuation of the intensity of ambient light, and the timing of photography. It is a figure for demonstrating the relationship between the periodic fluctuation of the intensity of ambient light, and the timing of photography.

Prior to the description of the embodiment of the present invention, the reason why the light and darkness varies between images due to the periodic fluctuation of the ambient light will be described.

FIGS. 8 and 9 show periodic fluctuations in the intensity of ambient light (hereinafter, simply referred to as “periodic _fluctuations in ambient light”). It shows the progress of or the change of the phase θ. In FIGS. 8 and 9, the periodic fluctuation of the ambient light is represented by a sine curve, but unlike this, the actual ambient light takes various waveforms depending on the type of the light source that causes the periodic fluctuation. For example, in a non-inverter fluorescent lamp, the intensity varies in proportion to the square of the voltage at a frequency of 100 Hz or 120 Hz derived from a commercial power source. Further, in the LED pulse lighting method, the LED blinks at a frequency of several hundred Hz to several tens of kHz, which differs depending on the manufacturer, and the amount of light is increased or decreased depending on the length of lighting time (pulse width).

In FIG. 8, the intensity _IA of the ambient light fluctuates in the period _TA with the passage of time t. At this time, the phase θ of the ambient light moves from 0 to 2π during one cycle _TA . The amount of ambient light _LA recorded in the image when the image is taken with the exposure time τ _E corresponds to the area of the shaded area in the figure. When the exposure time τ _E is shorter than the period _TA of the ambient light, even if the exposure time τ _E is the same, the brightness of the obtained image differs depending on the timing at which the exposure is started. For example, in FIG. 8, there is a difference in the brightness of the obtained image between the case of exposure from time ta to t _b and the case of exposure from time _{t c} to t _d . The smaller the ratio τ _E / _TA of the exposure time τ _E and the period _TA , the greater the variation in brightness between images captured at different times. In order to suppress the variation in brightness between images, it is necessary to keep the integrated light amount _LA of the ambient light within the exposure time τ _E constant.

With reference to FIG. 9, the same phenomenon can occur when the exposure time τ _E is longer than the ambient light period _TA . The degree of influence of the periodic fluctuation of the ambient light largely depends on the waveform of the ambient light, but when the exposure time τ _E is 10 times or less of the cycle _TA of the ambient light, the variation of light and dark is ignored among multiple images. There are things I can't do. For example, if the exposure time τ _E is 1 ms and the fluctuation period _TA of the ambient light is 100 μs or more (frequency 10 kHz or less), the variation in brightness between a plurality of images may not be negligible.

A first embodiment of the imaging system of the present invention will be described with reference to FIGS. 1 to 4.

With reference to FIG. 1, the imaging system 10 of the present embodiment captures an object O. The image pickup system 10 includes an image pickup device 11 and a shooting timing control device 16. The image pickup apparatus 11 has a single image pickup unit 12, a control unit 14, and an image processing unit 15. The photographing timing control device 16 has a light amount sensor 17 and an analysis unit 18.

The image pickup unit 12 of the image pickup apparatus 11 collects light on the image pickup element with a lens and takes an image. As the image pickup element, a CCD, a CMOS sensor, or the like can be used. The image sensor is preferably a global shutter type.

The control unit 14 controls the entire image pickup device 11 including the image pickup unit 12 and the image processing unit 15. Specifically, the control unit 14 instructs the image pickup unit 12 to start exposure, end exposure, transfer an image from the image pickup element, and the like. In the present specification, "exposure start", "shooting start", "imaging start" and "shutter open" are used interchangeably, and "exposure end", "shooting end" and "shutter closed" have the same meaning. Used in. After the shooting is completed, the control unit 14 transfers the image from the image pickup unit 12 to the image processing unit 15.

The image processing unit 15 processes the captured image. The contents of image processing include comparison, difference, and composition of a plurality of images. When the image pickup device 11 is a three-dimensional measurement device, the image processing unit 15 performs image processing for calculating the three-dimensional coordinates of the image pickup target O. The image processing method for calculating the three-dimensional coordinates will be described later. In the image pickup system 10 of the present embodiment shown in FIG. 1, the image pickup device 11 has a built-in image processing unit 15, but the configuration of the image pickup system is not limited to this, and the image pickup device 11 includes the image processing unit 15. Instead, the image may be processed by using a personal computer or the like provided outside the image pickup system 10 as an image processing device. In that case, the control unit 14 transfers the image from the image pickup unit 12 to an external image processing device.

The light amount sensor 17 of the shooting timing control device 16 measures the amount of ambient light. The light amount sensor does not necessarily have to measure toward the object O, and may be arranged in a direction in which fluctuations in ambient light can be easily observed. Further, a diffuser plate may be provided on the front surface of the light amount sensor, whereby the amount of ambient light can be measured while suppressing the influence of changes in the shape and position of the object O.

The analysis unit 18 analyzes the periodic fluctuation of the ambient light based on the time-dependent change of the measured value of the light amount sensor. Specifically, the analysis unit calculates the period and waveform of the periodic fluctuation of the ambient light. Further, in order to measure the timing of the start of exposure, the analysis unit monitors the change in the intensity of the ambient light based on the measured value of the light amount sensor (hereinafter, simply referred to as "surveillance of the ambient light"), and calculates the periodicity. The phase of the ambient light is specified by comparison with the fluctuation waveform. The analysis unit is further connected to the control unit 14 of the image pickup apparatus 11 to perform various communications.

The analysis unit 18 of the shooting timing control device 16 and the control unit 14 of the image pickup device 11 may be physically composed of one computer or the like. On the other hand, the light amount sensor 17 for monitoring the ambient light is provided separately from the image pickup unit 12 of the image pickup device 11. It is possible to measure the amount of ambient light using the image sensor of the image pickup unit 12, but by providing a separate light amount sensor, the procedure for switching from monitoring to imaging to specify the phase of the ambient light is simple. Because it becomes. Further, by providing a separate light amount sensor, the light amount sensor can be arranged in a direction in which it is easy to observe the periodic fluctuation of the ambient light, and only the periodic fluctuation of the ambient light excluding the influence of the reflected light from the object O is observed. Because it can be done.

Preferably, the imaging timing control device 16 and the imaging device 11 are configured as physically separate devices. As a result, the imaging system of the present embodiment can be realized by using a commercially available FA camera or the like for automating the production process in a factory or the like as an imaging device and connecting the imaging timing control device 16 to the imaging device, so that imaging timing control can be achieved. Increases the versatility of the device.

Next, the operation of the image pickup system 10 of the present embodiment will be described.

With reference to FIG. 2, in the imaging by the imaging system 10, the photographing timing control device 16 analyzes the ambient light (S1) and sets the exposure start phase (S2). At the time of imaging, the imaging timing control device monitors the ambient light (S3) and transmits an exposure start instruction to the imaging device 11 (S4). On the other hand, when the image pickup device 11 receives an exposure start instruction from the shooting timing control device, the image pickup device 11 performs image pickup (S5). In FIG. 2, communication between the photographing timing control device 16 and the image pickup device 11 is performed between the analysis unit 18 and the control unit 14. The details of each step will be described below.

First, the photographing timing control device 16 analyzes the periodic fluctuation of the ambient light (S1). The light amount sensor 17 repeatedly measures the light amount _ΔLA of the ambient light every minute time Δτ (FIG. 3A). Here, the intensity _IA of the ambient light is obtained by _IA = _ΔLA / Δτ. If Δτ is made sufficiently short, the intensity _IA of the ambient light can be observed in substantially real time. For example, if sampling is performed at intervals of 1/10 to 1/100 of the fluctuation period of ambient light, observation can be performed in substantially real time. The analysis unit 18 calculates the period _TA and the waveform of the periodic fluctuation of the ambient light based on the time-dependent change of the value measured by the light amount sensor (FIG. 3B). The waveform obtained here does not have to be a waveform of an absolute value of the intensity of the ambient light, and may be a waveform that shows a relative change in the intensity of the ambient light.

Based on the obtained waveform, the analysis unit 18 sets the phase θ _* to start the exposure as the exposure start phase (S2). The analysis unit can determine the exposure start phase θ _* by focusing on, for example, a characteristic portion of the waveform. In FIG. 3C, the phase of the maximum point at which the intensity _IA of the ambient light changes from increasing to decreasing is set as the exposure start phase θ _* . Alternatively, the analysis unit may use the phase at the point where a certain time has passed from the characteristic portion of the waveform as the exposure start phase θ _* .

When the imaging timing control device 16 receives the imaging preparation completion notification from the imaging device 11, the light amount sensor 17 repeatedly measures the light amount _ΔLA of the ambient light every minute time Δτ, referring to FIG. , The analysis unit 18 starts monitoring the ambient light (S3).

The analysis unit 18 compares the change in the intensity of the ambient light with the waveform of the ambient light obtained in step S1, and when the ambient light reaches the exposure start phase θ _* , sends an exposure start instruction to the image pickup apparatus 11 (S4). Upon receiving the instruction, the image pickup apparatus starts exposure (S51). By the way, since the value measured by the light amount sensor is a small amount but a light amount _ΔLA with a constant time interval Δτ, the exposure starts at the “moment” when the ambient light reaches the exposure start phase θ _* while monitoring the light amount. It can be difficult to tell. In that case, when the analysis unit finds that the ambient light has reached the exposure start _phase θ _* at time t1 from the measured value of the light amount sensor, the time obtained by adding the period _TA obtained in step S1 to time t1, that is, Next, the time t ₂ at which the phase of the ambient light becomes the exposure start phase θ _* is obtained, and the exposure start instruction is transmitted to the image pickup apparatus 11 at the time t ₂ . In other words, the exposure start instruction is transmitted based on the change of the ambient light one cycle before.

Alternatively, the analysis unit 18 may transmit an exposure start instruction to start the exposure at _time t2 in advance to the image pickup apparatus 11. For example, the predetermined time is set to _τD milliseconds, and the analysis unit sends an instruction to the image pickup apparatus to start the exposure _τD milliseconds before _{τD milliseconds} at time t2. In this case, the image pickup apparatus waits for _time t2 to start the exposure according to the exposure start instruction from the analysis unit (S51). As described above, in the present specification, the exposure start instruction indicates the timing at which the exposure should be started to the image pickup apparatus, and the image pickup apparatus that has received the instruction should immediately start the exposure. It is a concept that includes both those in which the image pickup device should wait for the specified time after receiving the instruction and start the exposure.

When the image pickup device 11 receives an exposure start instruction from the shooting timing control device 16, the image pickup device 11 performs image pickup (S5). The control unit 14 of the image pickup apparatus 11 controls the image pickup unit 12 to open the shutter to start exposure (S51), and when the predetermined exposure time _τE elapses, the shutter is closed to end the exposure (S52). Is transferred from the image pickup unit 12 to the image processing unit 15. This completes one imaging.

When the image is continuously imaged, the image pickup device 11 sends a picture pickup preparation completion notification to the picture shooting timing control device 16, and the subsequent operations are repeated. If the monitoring of the ambient light (S3) by the photographing timing control device 16 is continued even after the transmission of the exposure start instruction, there is an advantage that the imaging interval can be shortened when continuous imaging is performed.

After the required number of imagings is completed, the image processing unit 15 performs processing on the captured images according to the purpose of imaging (S6).

As a modification of the above operation, the shooting timing control device 16 may transmit an exposure start instruction to the image pickup device 11, and then an exposure end instruction may be transmitted after a predetermined exposure time _τE has elapsed. After transmitting the exposure start instruction, an instruction to end the exposure after a predetermined exposure time _τE may be transmitted in advance to the image pickup apparatus 11. Alternatively, the shooting timing control device may set the phase of the ambient light to end the exposure, and when the ambient light reaches the exposure end phase, the exposure end may be transmitted to the image pickup apparatus 11. Even in this case, since the exposure start phase θ _* and the exposure end phase are constant, the exposure time τ _E is constant. That is, in the present specification, the exposure end instruction indicates the timing at which the exposure should be ended to the image pickup device, and the image pickup device that has received the instruction should immediately end the exposure. Is a concept that includes both those who should wait for the specified time after receiving the instruction to finish the exposure.

In the imaging system 10 of the present embodiment, the exposure is started when the ambient light reaches a constant phase (exposure start phase θ _* ) of the periodic fluctuation, and the exposure is terminated after the predetermined exposure time _τE elapses. The amount of ambient light _LA recorded in the image is constant. As a result, it is possible to suppress variations in brightness between images captured at different times. Due to this effect, the imaging system 10 can be suitably used for comparing images captured in the same field of view or images captured in the same object. The image pickup system 10 determines, for example, a defect or color of a part by comparing with a good image image captured in the same field of view in inspection of various products, or determines the position of a work flowing on a conveyor for picking up by a robot. It can be suitably used as a visual sensor for performing.

Further, since the imaging system 10 of the present embodiment focuses on the phase of the ambient light and waits for the next exposure start phase θ _* to perform imaging, it functions regardless of the length of the period _TA of the ambient light. In order to take advantage of the features of the image pickup system 10, it is preferable that the exposure time τ _E is shorter than the period _TA of the ambient light. This is because the smaller the ratio τ _E / _TA of the two, the larger the variation in brightness between the images captured at different times. From this viewpoint, the exposure time τ _E is preferably 10 times or less, more preferably 5 times or less, still more preferably 1 time or less of the period _TA of the ambient light. For example, in a room where a fluorescent lamp is installed, the period _TA of the ambient light is about 8.3 ms or 10 ms, whereas the exposure time τ _E is about 83 ms or less or 100 ms or less, respectively, in the present embodiment. There is a merit of using the image pickup system 10 of the above.

A second embodiment of the imaging system of the present invention will be described with reference to FIG.

With reference to FIG. 5, the image pickup system 20 of the present embodiment includes an image pickup device 21 and a shooting timing control device 16. The image pickup device 21 is a stereo type three-dimensional measurement device. The photographing timing control device 16 is the same as that of the first embodiment.

The image pickup apparatus 21 has two image pickup units 22A and 22B, a control unit 24, and an image processing unit 25. The image pickup units 22A and 22B simultaneously image the object O from different viewpoints. The control unit 24 controls the entire image pickup device 21 including the image pickup units 22A and 22B and the image processing unit 25. The image processing unit 25 processes the captured image to calculate the three-dimensional position and shape of the object O. It should be noted that the image processing device 21 does not have the image processing unit 25, and the image processing device may be provided outside the image processing system 20 to perform image processing, as in the first embodiment.

The operation of the image pickup system 20 of the present embodiment is different from that of the first embodiment shown in FIG. 2 in that the image pickup step (S5) is performed by the two image pickup units 22A and 22B. The image processing (S6) by the image processing unit 25 is a three-dimensional calculation for calculating the three-dimensional position and shape of the object O. Although the present embodiment uses a two-lens stereo camera having two imaging units, the present invention can be applied to a multi-lens stereo camera that performs three-dimensional measurement by a stereo method such as a three-eye stereo camera. can. As the number of image pickup units increases, three-dimensional measurement can be performed from more image data, so that more accurate three-dimensional measurement becomes possible.

Three-dimensional measurement by the stereo method is a method that uses the parallax of two cameras, finds the corresponding points of the points to be measured on two images with different viewpoints, and finds the corresponding points on each image and the two cameras. This is a method of calculating the three-dimensional position of a measurement point from the positional relationship of the above by the principle of triangulation.

The search for the corresponding point is performed by extracting feature points such as edges of the object by image processing. Since the two images are captured at the same time, the brightness (luminance level) of the corresponding two images is the same. Further, in the present embodiment, the brightness of the images captured at different times is the same, so that the intensities of the edges and the like are the same in all the images, and the accuracy of extracting the feature points is improved.

In addition, a stereo method using a color camera is being developed as an image sensor when operating a wire harness or various cables with a robot. In this method, it is difficult to determine the corresponding point when a large number of cables exist in the image, but this method is a method of first selecting the target cable by color by image processing and then searching for the corresponding point. This enables high-speed three-dimensional measurement, and it is possible to track the target cable while repeating imaging according to the movement of the robot. However, since the color tone of the cable changes when the brightness (luminance level) of the image is different, the color selection process may fail during the tracking of the cable due to the variation in brightness between the images. According to the image pickup system 20 of the present embodiment, since the brightnesses between the images captured at different times are the same, it is possible to stably select by the color of the cable.

A third embodiment of the imaging system of the present invention will be described with reference to FIGS. 6 and 7.

With reference to FIG. 6, the image pickup system 30 of the present embodiment includes an image pickup device 31 and a shooting timing control device 16. The image pickup apparatus 31 includes an image pickup unit 32, a pattern projection unit 33, a control unit 34, and an image processing unit 35. The image pickup device 31 is a pattern projection type three-dimensional measurement device. The photographing timing control device 16 is the same as that of the first embodiment.

In 3D measurement by the stereo method, one camera is replaced with a projector that projects a light / dark pattern, and the pattern projected on the object is observed by the other camera, so that the three-dimensional shape of the object can be measured. This so-called pattern projection method includes a light cutting method in which a simple linear pattern is projected while sequentially shifting in the width direction of the line, and two patterns in which the brightness and color change smoothly and the direction of change is reversed. Inclined light projection method for projecting, time-series coding method for sequentially projecting patterns with light and shade with binary codes such as gray code, phase for projecting fringe patterns with sine wave modulation of projection intensity while shifting the phase There is a method such as a shift method in which a plurality of patterns are sequentially projected for imaging. There is also a method of performing three-dimensional measurement by projecting only one type of more complicated pattern and performing imaging.

The three-dimensional measurement method in which a pattern is projected and imaged has an advantage that it is easier to search for a corresponding point than a passive stereo method in which the pattern is not projected. However, if the light and darkness varies among a plurality of acquired images, for example, in the binarization process of the Gray code image, the bright and dark points may be misidentified, and accurate three-dimensional measurement may not be possible.

Hereinafter, in this embodiment, a method of sequentially projecting a plurality of patterns will be described. In FIG. 6, the image pickup unit 32 of the image pickup apparatus 31 is the same as the image pickup unit 22A of the second embodiment. The image pickup apparatus 31 may include a plurality of image pickup units 32. As the number of image pickup units increases, three-dimensional measurement can be performed from more image data, so that more accurate three-dimensional measurement becomes possible. The pattern projection unit 33 generates a plurality of patterns by a liquid crystal element or the like, irradiates them with a light source, and sequentially projects different patterns on the object O. The light source of the pattern projection unit is preferably a light source without flicker.

The control unit 34 controls the entire image pickup device 31 including the image pickup unit 32, the pattern projection unit 33, and the image processing unit 35. Specifically, the control unit 34 instructs the image pickup unit 32 to start exposure, end exposure, transfer an image from the image pickup element, and instruct the pattern projection unit to select a pattern, start projection, end projection, and the like. do. After the shooting is completed, the control unit 34 transfers the image from the image pickup unit 32 to the image processing unit 35.

The image processing unit 35 processes a plurality of images obtained by capturing a plurality of patterns to calculate the three-dimensional position and shape of the object O. It should be noted that the image processing device 31 does not have the image processing unit 35, and the image processing device may be provided outside the image processing system 30 to perform image processing, as in the first and second embodiments.

Next, the operation of the image pickup system 30 of the present embodiment will be described.

With reference to FIG. 7, the shooting timing control device 16 analyzes the ambient light (S1), sets the exposure start phase (S2), monitors the ambient light (S3), and transmits an exposure start instruction to the image pickup device 31 (S4). ) Is the same as that of the first embodiment shown in FIG. In the imaging step (S7) by the imaging device 31, imaging is performed while projecting a pattern. Further, after imaging a plurality of patterns, the three-dimensional position and shape of the object O are calculated (S8).

When the image pickup device 31 receives an exposure start instruction from the shooting timing control device 16, the image pickup device 31 performs image pickup (S7). The control unit 34 of the image pickup apparatus 31 controls the pattern projection unit 33 to project a pattern, and at the same time, the control unit 34 controls the image pickup unit 32 to open the shutter and start exposure (S71). Then, when the predetermined exposure time _τE elapses, the image pickup apparatus 31 closes the shutter, ends the exposure, and ends the pattern projection (S72). The captured image is transferred from the image pickup unit 32 to the image processing unit 35. This completes one imaging.

When the next imaging becomes possible, the imaging device 31 sends an imaging preparation completion notification to the imaging timing control device 16, and imaging is repeated for the next pattern.

After the imaging of the plurality of patterns is completed, the three-dimensional position of the object O is determined by the image processing unit 35 of the image pickup apparatus 31 based on the plurality of images captured and the positional relationship between the pattern projection unit 33 and the image pickup unit 32. And the shape is calculated (S8).

According to the image pickup system 30 of the present embodiment, the brightness of a plurality of images obtained by capturing a plurality of patterns is uniform, so that the accuracy of three-dimensional measurement is improved. In the present embodiment, the three-dimensional position and shape of the object O are calculated from a plurality of images obtained by capturing a plurality of patterns, but the three-dimensional position and shape of the object O are calculated from the images obtained by capturing one type of pattern. You can also do it. When measuring a moving object over time, the brightness of multiple images taken at different times is the same, so the accuracy of three-dimensional measurement for measuring mutations in the object is improved.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the technical idea thereof.

10, 20, 30 Imaging system 11, 21, 31 Imaging device 12, 22A, 22B, 32 Imaging unit 33 Pattern projection unit 14, 24, 34 Control unit 15, 25, 35 Image processing unit 16 Imaging timing control device 17 Light intensity sensor 18 Analytical unit _IA Environmental light intensity _LA Environmental light integrated light amount O Object t Time _TA Environmental light fluctuation cycle τ _E Exposure time θ Phase θ _* Exposure start phase

Claims (9)

It is a shooting timing control device used together with an imaging device that shoots under ambient light that fluctuates periodically.
A light amount sensor that measures the amount of ambient light, and
An exposure start instruction for analyzing the periodic fluctuation of the intensity of the ambient light based on the measured value by the light amount sensor, determining the exposure start phase in the periodic fluctuation, and starting the exposure in accordance with the exposure start phase. With an analysis unit that transmits the image to the image pickup device .
It is configured as a device separate from the image pickup device and is used by connecting to the image pickup device.
Shooting timing control device. The shooting timing control device according to claim 1 and
The image pickup device that starts exposure according to the exposure start instruction, and
Imaging system with. The shooting timing control device instructs the image pickup device to end the exposure.
The imaging system according to claim 2 . It has an image processing unit that performs image processing using the image captured by the image pickup device.
The imaging system according to claim 2 or 3 . The image pickup device is a three-dimensional measurement device having a built-in image processing unit.
The imaging system according to claim 4 . The image captured by the image pickup device is transferred to the image processing device.
The imaging system according to claim 2 or 3 . The image pickup device is a stereo camera having a plurality of image pickup units.
The imaging system according to any one of claims 2 to 6 . The image pickup device
A pattern projection unit that projects a pattern on an object,
One or more image pickup units that image the object on which the pattern is projected, and
It has a pattern projection unit and a control unit that controls the image pickup unit.
The imaging system according to any one of claims 2 to 6 . The ambient light analysis process in which the shooting timing control device analyzes the periodic fluctuations in the intensity of the ambient light,
A step of determining the exposure start phase in the periodic variation of the intensity of the ambient light analyzed by the photographing timing control device, and
The shooting timing control device may be used as a device separate from the shooting timing control device.
The image pickup device, which is formed and connected to the shooting timing control device, is adjusted to the exposure start phase.
And the process of sending an exposure start instruction to start exposure
An imaging step in which the imaging device starts exposure when the ambient light reaches the exposure start phase.
Imaging method having.

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