WO2007145489A1 - Device for tracking solar position and method thereof - Google Patents

Device for tracking solar position and method thereof Download PDF

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Publication number
WO2007145489A1
WO2007145489A1 PCT/KR2007/002929 KR2007002929W WO2007145489A1 WO 2007145489 A1 WO2007145489 A1 WO 2007145489A1 KR 2007002929 W KR2007002929 W KR 2007002929W WO 2007145489 A1 WO2007145489 A1 WO 2007145489A1
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WO
WIPO (PCT)
Prior art keywords
sun
image
brightness
boundaries
calculating
Prior art date
Application number
PCT/KR2007/002929
Other languages
French (fr)
Inventor
Jin Woo Hong
Hee Joon Lee
Original Assignee
Mirae Energy Technology Co.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mirae Energy Technology Co. filed Critical Mirae Energy Technology Co.
Publication of WO2007145489A1 publication Critical patent/WO2007145489A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/10—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void
    • G01J1/20—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle
    • G01J1/28—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle using variation of intensity or distance of source
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/78—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using electromagnetic waves other than radio waves
    • G01S3/782—Systems for determining direction or deviation from predetermined direction
    • G01S3/785—Systems for determining direction or deviation from predetermined direction using adjustment of orientation of directivity characteristics of a detector or detector system to give a desired condition of signal derived from that detector or detector system
    • G01S3/786—Systems for determining direction or deviation from predetermined direction using adjustment of orientation of directivity characteristics of a detector or detector system to give a desired condition of signal derived from that detector or detector system the desired condition being maintained automatically
    • G01S3/7861—Solar tracking systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S50/00—Arrangements for controlling solar heat collectors
    • F24S50/20—Arrangements for controlling solar heat collectors for tracking
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/40—Solar thermal energy, e.g. solar towers
    • Y02E10/47—Mountings or tracking

Definitions

  • the present invention relates, in general, to a device and method for tracking the position of the sun and, more particularly, to a device for detecting an image of the celestial sphere and tracking the position of the sun based on brightness and a method of tracking the path of the sun by retracking the position of the sun at regular intervals .
  • Conventional methods of tracking the position of the sun include a method using optical sensors, and a method using electromotive force that is generated by solar light.
  • the above-described methods have shortcomings in that they incur a large amount of computational load in order to correct errors in the case where there are clouds, abnormal atmospheric conditions, or physical interference, so that efficiency is low because a long time is required, and so that it is impossible to accurately track the position of the sun.
  • FIG. 1 is a block diagram schematically showing technology that is disclosed in prior art 1 (Korean Unexamined Patent Publication No. 10-2006-0011286) .
  • the microcomputer 16 measures the position of the sun by performing operations on three pieces of data, input from the GPS 12, the digital clock 13 and the light receiving sensor 14, using an input program.
  • the characteristics of the area to be measured such as the presence of adjacent high-rise buildings and trees, may be set as variable input 15.
  • FIG. 2 is a block diagram schematically showing the technology that is disclosed in prior art 2 (Korean Patent No. 10-0317811) for tracking the sun through image recognition.
  • prior art 2 relates to a method and device for tracking the sun, which includes an image input means 29 for receiving image signals by converting an image, captured by the lens of a camera installed at a specific location on a heat collection plate 30, into electrical signals, and a control means for detecting the shape of the sun from the input image signals, calculating the coordinates of the movement of the sun at a location at which the shape of the sun is placed on the camera image, calculating the displacement from the coordinates of the movement of the sun to the central coordinates of the camera image, and controlling a motor driving means 26 so that the direction of the camera is charged by the displacement .
  • Prior art 2 also has a shortcoming in that it is difficult to accurately track the position of the sun in the case where there is clouds, abnormal atmospheric conditions, or physical interference.
  • an object of the present invention is to provide a device and method for tracking the accurate position of the sun, which track the position of a light source based on the characteristic of brightness in which the brightness of the light of the light source decreases as the light moves away from the light source, so that it can effectively accurately track the position of the sun even in the case where there are clouds, abnormal atmospheric conditions, or physical interference.
  • the present invention provides a device for tracking the position of the sun, including an image capture unit for capturing an image of the celestial sphere; a region calculation unit for calculating brightness of the image received from the image capture unit, dividing the image into a plurality of regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions; a central processing unit for calculating the position of the sun in the image based on the boundaries; and an output unit for outputting the position of the sun calculated by the central processing unit.
  • the central processing unit recognizes the sun as being located within the circle.
  • the central processing unit recognizes the sun as being located within the range.
  • the region calculation unit performs division into respective regions based on subdivided levels of brightness, and the central processing unit calculates the position of the sun based on the respective regions and boundaries of the regions .
  • the image capture unit captures respective preset regions of a celestial sphere using one or more cameras.
  • the device further includes a control unit for enabling a user to control the device for tracking a position of a sun.
  • the present invention provides a method of tracking the position of the sun, including capturing an image of the celestial sphere using an image capture unit; calculating the brightness of the captured image using a region calculation unit, dividing the image into respective regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions; and calculating the position of the sun in the image from the regions and the boundaries using a central processing unit.
  • the method further includes setting the calculated position of the sun as a reference point; calculating a position of the sun by capturing an image of the celestial sphere again using the image capture unit and repeating the steps of calculating the position of the sun in the image; and tracking the position of the sun by comparing the reference point with the position of the sun in the image.
  • the method may further include recognizing an initiation signal so as to initiate tracking of the position of the sun. Any one of current time reached after sunrise, an amount of solar light, equal to or greater than a predetermined amount, detected by an optical sensor, and the input of an initiation signal performed by a user may be recognized as the initiation signal .
  • the method further include recognizing an initiation signal, performing division into respective regions based on subdivided levels of brightness using the region calculation unit, and calculating the position of the sun by repeating the steps of calculating the position of the sun in the image. Furthermore, if the position of the sun in the image is not recognized, the method further includes performing division into respective regions based on subdivided levels of brightness using the region calculation unit, and calculating the position of the sun by repeating the steps of calculating the position of the sun in the image. Preferably, the method further includes recognizing a termination signal so as to terminate the tracking of the position of the sun. Any one of current time reached after sunset, an amount of solar light, equal to or less than a predetermined amount, detected by an optical sensor, and input of a termination signal performed by a user may be recognized as the termination.
  • the position of the sun is calculated by repeating the steps of calculating the position of the sun in the image.
  • the method further includes storing the calculated path of the sun in a storage unit, converting data about the path of the sun, stored in the storage unit or output from an output unit, into coordinates, and calculating an altitude and azimuth of the sun using the coordinates .
  • the position of a light source is tracked based on brightness, so that the accurate position of the sun can be effectively tracked even in the case where there are clouds, abnormal atmospheric conditions, or physical inference.
  • cameras can be made to capture respective predetermined regions of the celestial sphere using a plurality of cameras, so that the entire celestial sphere can be captured at one time, and so that images can be captured at fixed locations without moving the cameras, thereby more accurately detecting the path of the sun in the celestial sphere instantaneously.
  • the present invention includes a control unit for enabling a user to control the device for tracking the position of the sun, so that the regions of the celestial sphere desired by a user can be captured and levels of brightness and the error range can be set by a user, with the result that the position of the sun can be tracked more accurately and the path of the sun can be detected more accurately.
  • the present invention recognizes an initiation signal and a termination signal, and thus does not track the sun in atmospheric conditions in which it is impossible to track the position of the sun or at night, so that unnecessary power consumption does not occur.
  • the path of the sun can be converted into coordinates and can be used for other sun-related devices .
  • FIG. 1 is a block diagram schematically showing an embodiment of prior art 1 (Korean Unexamined Patent Publication No. 10-2006-0011286);
  • FIG. 2 is a block diagram schematically showing an embodiment of prior art 2 (Korean Patent No. 10-0317811);
  • FIG. 3 is a block diagram showing the schematic structure of an embodiment of a device for tracking the position of the sun according to the present invention
  • FIG. 4 shows an embodiment in which division into regions is performed based on brightness
  • FIG. 5 shows an embodiment in which an image of the celestial sphere is divided into regions based on brightness according to the present invention
  • FIG. 6 is a flowchart schematically showing a process in which the central processing unit of the device for tracking the position of the sun according to the present invention calculates the position of the sun;
  • FIG. 7 shows an embodiment in which the position of the sun is tracked on a clear day according to the present invention
  • FIG. 8 shows an embodiment in which the position of the sun is tracked on a cloudy day according to the present invention
  • FIG. 9 shows an embodiment in which the position of the sun is tracked according to the present invention in the case where the sun is hidden by an obstacle
  • FIG. 10 shows an embodiment in which the position of the sun is tracked according to the present invention in the case where the sun is hidden by clouds
  • FIG. 11 shows an embodiment in which the position of the sun calculated according to the present invention is converted into coordinates
  • FIG. 12 shows an embodiment in which a user controls the device for tracking the position of the sun according to the present invention
  • FIG. 13 shows an embodiment in which the position of the sun, calculated according to the present invention, is displayed such that a user can easily recognize the position of the sun;
  • FIG. 14 is a block diagram schematically showing an embodiment of a method of tracking the position of the sun according to the present invention.
  • FIG. 15 is an embodiment showing the position of the sun obtained according to the present invention.
  • a device for tracking the position of the sun includes an image capture unit 50 for capturing an image of the celestial sphere; a region calculation unit 60 for calculating the brightness of the image received from the image capture unit, dividing the image into a plurality of regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions; a central processing unit 70 for calculating the position of the sun in the image based on the boundaries; and an output unit 80 for outputting the position of the sun calculated by the central processing unit.
  • a method of tracking the position of the sun includes capturing an image of the celestial sphere using an image capture unit 50; calculating the brightness of the captured image using a region calculation unit 60, dividing the image into respective regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions; and calculating the position of the sun in the image from the regions and the boundaries using a central processing unit 70.
  • the method of tracking the position of the sun according to the present invention may further include setting the calculated position of the sun as a reference point; calculating the position of the sun by capturing an image of the celestial sphere again using the image capture unit 50 and repeating the steps of calculating the position of the sun in the image; and tracking the position of the sun by comparing the reference point with the position of the sun in the image.
  • FIG. 3 shows the schematic structure of an embodiment of the device for tracking the position of the sun according to the present invention.
  • the device for tracking the position of the sun includes an image capture unit 50, a region calculation unit 60, a central processing unit 70, an output unit 80, a control unit 100, and a peripheral device 90.
  • the image capture unit 50 captures images of the celestial sphere.
  • a camera equipped with a lens capable of collecting images across a wide range or a fisheye lens may be used as the image capture unit 30.
  • the entire celestial sphere can be captured at one time, and images can be captured at fixed locations without moving cameras regardless of the movement of the sun in the celestial sphere, thereby more accurately detecting the path of the sun in the celestial sphere instantaneously.
  • the region calculation -unit 60 divides the image of the celestial sphere, received from the image capture unit 50, into a plurality of brightness sections based on levels of brightness, distinguishes the regions, and defines the boundaries of the regions. A method of dividing an image into regions based on levels of brightness is described with reference to FIGS. 4 and 5.
  • FIG. 4 (a) is a photo in which the brightness of an image is divided into 256 levels ranging from the brightest level to the darkest level .
  • portions ranging from the darkest portion to the brightest portion are divided based on 256 levels of brightness and a minute difference in the amount of brightness is shown. Then, natural transition from a dark portion to a bright portion seems to occur.
  • the maximum number of levels of brightness into which subdivision is performed is set to a maximum of 256 levels of brightness.
  • FIG. 4(b) is a photo that represents the image of FIG. 4 (a) based on 30 levels of brightness, with levels having similar brightness being integrated together.
  • FIG. 4(c) is a photo that represents the image based on 16 levels of brightness, simplified compared to those of FIG. 4 (b) .
  • brightness is highest near the center portion of the sun and brightness decreases in proportion to the distance from the center of the sun.
  • brightness sections having similar levels can be presented as a single region.
  • FIG. 5 (a) shows an image of the celestial sphere on a clear day.
  • the photo shown in FIG. 5 (b) is obtained.
  • the photo shown in FIG. 5 (c) is obtained.
  • FIG. 5 (b) or FIG. 5(c) when the image is divided into brightness sections having similar levels, semicircle-shaped regions are obtained around the sun.
  • the region calculation unit 60 calculates the brightness of the image captured as described above, and divides the image into a plurality of brightness sections based on levels of brightness, such as 256 levels of brightness, 30 levels of brightness, or 16 levels of brightness. The resulting brightness sections are distinguished as respective regions, so that the entire image of the celestial sphere can be divided into respective regions.
  • the present invention allows appropriate levels of brightness to be searched for while causing the levels of brightness to proceed from simple levels to subdivided levels. Furthermore, the number of levels may be adjusted so as to cause the levels of brightness to be finer or rougher according to a user's necessity or the state of an image, attributable to weather or clouds.
  • the central processing unit 70 calculates the position of the sun based on the boundaries of the respective regions, which will be described in detail below with reference to FIGS. 6 to 11.
  • FIG. 6 is a flowchart schematically showing a process in which the central processing unit 70 calculates the position of the sun.
  • the image is divided into a plurality of brightness sections based on levels of brightness, the image is divided into respective regions at step 61.
  • Whether circles are formed is determined based on the boundaries of the calculated regions at step 71.
  • the process searches for appropriate levels of brightness while causing the levels of brightness to proceed from simple levels to subdivided levels, and forms circles in optimum conditions at step 72.
  • the forming of circles in optimum conditions refers to the forming of most appropriate circles while forming an inscribed circle, a circumscribed circle and a proximity circle based on the levels of brightness .
  • one of the formed circles, including the region having the highest brightness, is determined at step 73.
  • an error range for the determined circle is calculated at step 77, and step 78 of determining whether the error range exceeds a tolerance range is performed. If the error range falls within the tolerance range, the position of the sun is determined at step 79. If the error range exceeds the tolerance range, an image of the celestial sphere is captured again at step 51 and the above-described steps of tracking the position of the sun are repeated.
  • the calculation of the error range is the measurement of the size of the determined circle, and the tolerance range refers to the range of the size of a circle, which is determined in the captured image, in which the circle can be considered the center of a light source.
  • the tolerance range may vary depending on the state of the captured image, and the variation is determined depending on accumulated data and a user's setting.
  • step 74 determines whether the boundaries of the regions and the extended lines of the boundaries have specific directionality. If the boundaries and the extended lines of the boundaries have specific directionality, the range in which intersections, at which the boundaries of the respective regions intersect the extended lines of the respective boundaries, are formed at step 75 is searched for by searching for optimum conditions using the most appropriate levels of brightness while causing the levels of brightness to proceed from simple levels to subdivided levels . Thereafter, the range in which the intersections are formed is determined at step 76.
  • an error range for the determined center is calculated, and whether the error range exceeds the tolerance range is determined at step 78. If the error range falls within the tolerance range, the position of the sun is determined at step 79. In contrast, if the error range exceeds the tolerance range, an image of the celestial sphere is captured again.
  • the calculation of the error range is the measurement of the size of the determined range
  • the tolerance range refers to the range of the size of a range, which is determined in the captured image, in which the range can be considered the center of a light source.
  • the tolerance range may vary depending on the state of the captured image, and the variation is determined depending on accumulated data and a user's setting.
  • FIG. 7 (a) shows an image of the celestial sphere that was captured in broad daylight using a typical camera.
  • FIG. 7 (b) is a photo that represents the image of FIG. 7 (a) based on 8 levels of brightness.
  • the size of the region having the brightest center brightness can be seen to be two times as large as that of FIG. 7 (a) .
  • the reason for this is that the portion, other than an original center portion, can also be recognized as a center region by applying the same color to levels having similar brightness. Accordingly, in the case of the image, when division into regions is performed based on 8 levels of brightness shown in FIG.
  • FIG. 7 (c) is a photo that represents the image of FIG. 7 (a) based on 16 levels of brightness
  • FIG. 7 (d) is a photo that represents the image of FIG. 7 (a) based on 30 levels of brightness
  • FIG. 7 (e) is a photo that represents the image of FIG. 7 (a) based on 60 levels of brightness.
  • the size of the center portion decreases accordingly when the number of levels of brightness is increased by dividing brightness into finer levels. Since the load to be processed is increased in proportion to the number of levels of brightness, it is necessary to form circles based on appropriate levels of brightness.
  • the number of levels is adjusted to perform classification into an appropriate number of levels so as to search for optimum conditions and thus reduce the error range.
  • the number of levels is adjusted according to a user's necessity or the state of an image attributable to weather.
  • FIG. 7(f) is a photo in which the levels of brightness are set according to a user's necessity
  • FIG. 7 (g) is a photo that is set such that the boundaries of the regions of FIG. 7(f) are represented.
  • FIG. 7 (h) is a photo showing imaginary circles based on the boundaries of respective regions, obtained through division based on the brightness of FIG. 7(f). The circles may be implemented as proximity circles, inscribed circles, and circumscribed circles based on the distribution of the same brightness . Error can be reduced by repeatedly implementing the shapes of respective circles and accumulating processing results.
  • FIG. 7 (h) shows an embodiment in which circles near genuine circles are gradually searched for based on the boundaries of respective regions, and proximity circles are formed.
  • 7(i) is a photo in which the levels of brightness are adjusted for optimum conditions according to a user's necessity or in consideration of error attributable to some other factor, such as weather, and the boundaries of regions are formed to be complete circles accordingly. Since the circles are arranged around a center light source, the center circle having the highest brightness can be estimated to be the center of the sun.
  • FIG. 8 (a) shows an image of the celestial sphere on an overcast day having heavy cloud. It is impossible to track the position of the sun using only the image.
  • the region calculation unit 20 divides the image into regions according to brightness based on levels having specific ranges at step 61 and the boundaries thereof are represented, FIG. 9 (b) is obtained.
  • An optimum condition is searched for by implementing proximity circles, inscribed circles, and circumscribed circles based on the boundaries of the resulting regions.
  • proximity circles or inscribed circles are formed, the upper end portions of regions having the same brightness levels are not included. Accordingly, circles most suitable for the present case are circumscribed circles that can include the portions.
  • FIG. 8(c) When circumscribed circles having the boundaries of the regions are formed at step 72, FIG. 8(c) is obtained.
  • an error range is calculated based on accumulated error, and the circle having the conditions most suitable for the error range is obtained, the region of FIG. 8 (d) is realized.
  • the determined circle is included in the tolerance range of error, that is, in a predetermined area, the sun is recognized as being located in the circle, as shown in FIG. 8(e) .
  • FIG. 9 (a) shows an image of the celestial sphere in the situation in which the sun is hidden by an obstacle. According to the prior art, it is difficult to track the position of the sun using only the image of FIG. 9 (a) .
  • FIG. 9 (b) is a photo that represents FIG. 9 (a) based on 16 levels of brightness according to the present invention, from which it can be visually confirmed that a vague difference in brightness appears.
  • FIG. 9(c) is a photo that represents the boundaries of respective regions according to the difference in brightness.
  • FIG. 9 (d) is a photo that is controlled according to conditions set by a user in order to more clearly distinguish regions for FIG. 9(c). Such control by the user will be described in detail below.
  • FIG. 10 (a) is an image of the celestial sphere in which it is difficult to detect the location of the sun because the sun is hidden by clouds. Although, even in this case, it is possible to perform division into regions based on levels of brightness, it is difficult to form circles based on obtained regions due to a distortion phenomenon, because light from the sun is scattered by interfering objects or clouds. In this case, when inappropriate circles are formed unreasonably, an error in which the light source is found to have a plurality of locations occurs.
  • the center of the sun is searched for through another process. Since light has a characteristic of traveling in a straight line, it can be found that a light is located at the intersection at which light beams meet and which is found by retro-tracking the light beams.
  • the present invention tracks the position of the sun using a characteristic in which light travels in a straight line. Another process of tracking the position of the sun using the characteristic of light of traveling in a straight line according to the present invention is described in detail with reference to FIG. 10 below.
  • FIGS. 10 (b) and 10 (c) are photos that represent the image of FIG. 10 (a) based on 8 levels of brightness and 16 levels of brightness, respectively.
  • FIGS. 10 (b) and 10 (c) are divided into regions based on levels of brightness, appropriate circles based on regions are not formed.
  • the present invention tracks the position of the sun using another method based on the characteristic in which light travels in a straight line.
  • FIG. 10 (d) is obtained. As shown in FIG. 10 (d) , it can be seen that the boundaries and the extended lines of the boundaries have specific directionality at step 74 and that intersections are formed between the boundaries and the extended lines within a certain range at step 75.
  • the range for the intersections are determined at step 76, as shown in FIG. 10 (e) .
  • An error range is calculated for the range where the intersections are formed, and the sun is recognized as being located within the range where the intersections are formed if the error range is smaller than a predetermined area, which is a tolerance range.
  • the present invention can track the position of the sun using the characteristic in which light travels in a straight line even in the case where it is difficult to detect the position of the sun because the sun is hidden by clouds and in the case where it is difficult to search for the sun due to distortion because light from the sun is scattered by an interfering object or clouds .
  • the central processing unit 30 calculates the position of the sun as described above, data about the calculated position of the sun is output through the output unit 80 and is then input to a monitor for displaying the calculated position of the sun, a storage unit, or a sun- related device.
  • the storage unit can store data, calculated by tracking the position of the sun, in the form of coordinate data.
  • the device for tracking the position of the sun according to the present invention can accurately track the position of the sun even in a situation in which undesired weather, clouds or an obstacle is present.
  • the present invention further includes a control unit 100 for allowing a user to control the device for tracking the position of the sun.
  • the control unit 100 controls the image capture unit 50 so that it can capture the region of the celestial sphere desired by a user, as shown in FIG. 12. Furthermore, in order to more accurately calculate the position of the sun, it is possible to set the above- described levels of brightness or error range. Furthermore, in order to allow a user to accurately determine the position of the sun, the position of the sun is indicated, as shown in FIG. 13, so that a user can determine the position of the sun more conveniently.
  • the present invention includes a method of tracking the position of the sun.
  • the method of tracking the position of the sun according to the present invention is described below.
  • the image capture unit 50 captures an image of the celestial sphere
  • the region calculation unit 60 distinguishes respective regions by dividing the captured image into a plurality of brightness sections based on levels of brightness, and defines the boundaries of the regions.
  • the central processing unit 70 obtains the position of the sun from the image based on the regions and the boundaries .
  • the position of the sun in the obtained image is set as a reference point
  • the image capture unit captures an image again
  • the region calculation unit 60 perform division into regions
  • the central processing unit 70 calculates the position of the sun by processing the regions of the image
  • the path of the sun is calculated by comparing the set reference point with the calculated position of the sun.
  • an image of the celestial sphere for calculating a reference point is designated as a first image
  • an image of the celestial sphere to be used for comparison with the reference point is designated as a second image
  • the method of tracking the position of the sun receives a first image of the celestial sphere through step SlIO of capturing the first image of the celestial sphere using the image capture unit 50, and distinguishes respective regions through step S120 of dividing the first image into the respective regions based on levels of brightness using the region calculation unit 60.
  • step S130 of obtaining the position of the sun for the first image by- processing the respective regions using the central processing unit 70.
  • the position of the sun is obtained through the process described above in conjunction with FIG. 6.
  • step S140 the method goes through step S140 of setting the position of the sun as a reference point. However, if the position of the sun for the first image has not been obtained, the method returns to step SlOO of recognizing an initiation signal, and then repeats the steps of obtaining the position of the sun from the above-described first image.
  • the method receives a second image through step S150 of capturing a second image of the celestial sphere using the image capture unit 50, and distinguishes respective regions through step S120 of dividing the second image of the celestial sphere into the respective regions based on levels of brightness using the region calculation unit 60.
  • step S170 of obtaining the position of the sun for the second image by processing the respective regions using the central processing unit 70.
  • step S170 of obtaining the position of the sun for the second image the position of the sun is also obtained through the process described above in conjunction with FIG. 6.
  • step S180 If the position of the sun for the second image has been obtained, data about the path of the sun is obtained through step S180 of calculating the path of the sun by comparing the set reference point with the position of the sun obtained from the second image. However, if the position of the sun for the second image has not been obtained, the method returns to step S150 of capturing a second image of the celestial sphere using the image capture unit 50 and repeating the steps of obtaining the position of the sun from the second image.
  • step S190 of recognizing a termination signal after data about the path of the sun has been obtained the method of tracking the position of the sun is terminated. If the termination signal is not recognized, the method returns to step S150 of capturing a second image of the celestial sphere using the image capture unit 50 and tracks the path of the sun by repeating the steps of calculating the position of the sun for the above-described second image.
  • step SlOO of recognizing an initiation signal the current time reached after sunrise, an amount of solar light, equal to or greater than a predetermined amount, detected by an optical sensor, or the input of an initiation signal performed intentionally by a user is recognized as an initiation signal.
  • step S190 of recognizing a termination signal the current time reached after sunset, an amount of solar light, equal to or less than a predetermined amount, detected by an optical sensor, or the input of a termination signal performed intentionally by a user is recognized as a termination signal.
  • data about the calculated path of the sun is stored in a storage unit, or the stored data about the path of the sun is converted into coordinates and the altitude and azimuth of the sun can be calculated using the coordinates .
  • FIG. 15 is photos showing a method of tracking the path of the sun in such a way as to track the position of the sun, convert the tracked position into coordinates, calculate the azimuth and altitude of a reference point using the coordinates, and perform relative coordinate analysis by comparing the position of the sun after the reference time with a reference point.
  • the photos are collected at time intervals of 30 minutes, and an azimuth of two degrees and an altitude of one degree are assigned to one grid square.
  • the device and method for tracking the position of the sun according to the present invention can be modified and applied in various forms within the scope of the technical spirit of the present invention, and are not limited to the above-described embodiments.
  • the embodiments and the drawings are intended only to describe the content of the present invention in detail, and are not intended to limit the scope of the technical spirit of the present invention. It is apparent to those having ordinary skill in the field to which the present invention pertains that various substitutions, modifications and variations can be made without departing from the technical spirit of the present invention. Accordingly, the present invention is not limited to the embodiments, and the accompanying drawings and the present invention must be interpreted as including not only the attached claims, but also ranges equivalent to the attached claims .
  • the position of a light source is tracked based on brightness, so that the position of the sun can be accurately and efficiently tracked even in the case where clouds, abnormal atmospheric conditions or physical interference are present, thus being able to be used in all systems and devices requiring the tracking of the position of the sun, including power generation apparatuses using solar light or solar heat.

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Abstract

Disclosed herein are a device and method of tracking the position of the sun. The device for tracking a position of a sun includes an image capture unit for capturing an image of the celestial sphere, a region calculation unit for calculating the brightness of the image received from the image capture unit, dividing the image into a plurality of regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions, a central processing unit for calculating the position of the sun in the image based on the boundaries, and an output unit for outputting the position of the sun calculated by the central processing unit. As a result, the device and method can efficiently track the accurate position of the sun even in the case where clouds, an abnormal atmospheric phenomenon, or physical inference are present.

Description

[DESCRIPTION]
[invention Title]
DEVICE FOR TRACKING SOIiAR POSITION AND METHOD THEREOF
[Technical Field] The present invention relates, in general, to a device and method for tracking the position of the sun and, more particularly, to a device for detecting an image of the celestial sphere and tracking the position of the sun based on brightness and a method of tracking the path of the sun by retracking the position of the sun at regular intervals .
[Background Art]
Conventional methods of tracking the position of the sun include a method using optical sensors, and a method using electromotive force that is generated by solar light.
The above-described methods have shortcomings in that they incur a large amount of computational load in order to correct errors in the case where there are clouds, abnormal atmospheric conditions, or physical interference, so that efficiency is low because a long time is required, and so that it is impossible to accurately track the position of the sun.
FIG. 1 is a block diagram schematically showing technology that is disclosed in prior art 1 (Korean Unexamined Patent Publication No. 10-2006-0011286) .
In prior art 1, data about the latitude and longitude of the location on the earth to be determined is received using a Global Positioning System (GPS) 12, signals related to year, month, day and time are combined using a digital clock 13, the collective result is sent to a microcomputer 16, and a light receiving sensor 14 measures the intensity of brightness of the light of the sun and inputs measurement results to the microcomputer 16.
The microcomputer 16 measures the position of the sun by performing operations on three pieces of data, input from the GPS 12, the digital clock 13 and the light receiving sensor 14, using an input program. In this case, in order to measure the position of the sun more accurately, the characteristics of the area to be measured, such as the presence of adjacent high-rise buildings and trees, may be set as variable input 15.
The prior art 1 has a shortcoming in that it is difficult to accurately track the position of the sun in the case where there are clouds, abnormal atmospheric conditions or physical interference. Whenever the location to be measured is changed, the characteristics of the location must be set. FIG. 2 is a block diagram schematically showing the technology that is disclosed in prior art 2 (Korean Patent No. 10-0317811) for tracking the sun through image recognition.
As shown in FIG. 2, prior art 2 relates to a method and device for tracking the sun, which includes an image input means 29 for receiving image signals by converting an image, captured by the lens of a camera installed at a specific location on a heat collection plate 30, into electrical signals, and a control means for detecting the shape of the sun from the input image signals, calculating the coordinates of the movement of the sun at a location at which the shape of the sun is placed on the camera image, calculating the displacement from the coordinates of the movement of the sun to the central coordinates of the camera image, and controlling a motor driving means 26 so that the direction of the camera is charged by the displacement .
Prior art 2 also has a shortcoming in that it is difficult to accurately track the position of the sun in the case where there is clouds, abnormal atmospheric conditions, or physical interference.
[Disclosure] [Technical Problem]
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a device and method for tracking the accurate position of the sun, which track the position of a light source based on the characteristic of brightness in which the brightness of the light of the light source decreases as the light moves away from the light source, so that it can effectively accurately track the position of the sun even in the case where there are clouds, abnormal atmospheric conditions, or physical interference.
[Technical Solution] In order to accomplish the above object, the present invention provides a device for tracking the position of the sun, including an image capture unit for capturing an image of the celestial sphere; a region calculation unit for calculating brightness of the image received from the image capture unit, dividing the image into a plurality of regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions; a central processing unit for calculating the position of the sun in the image based on the boundaries; and an output unit for outputting the position of the sun calculated by the central processing unit.
In the present invention, if circles are formed based on the boundaries, and a circle, belonging to the circles for the respective regions and including a highest brightness section, forms a predetermined area, the central processing unit recognizes the sun as being located within the circle. Alternatively, if the boundaries of the regions and the extended lines of the boundaries have specific directionality and the intersections between the boundaries of the regions and the extended lines of the boundaries are formed within a predetermined range, the central processing unit recognizes the sun as being located within the range.
Meanwhile, if the central processing unit does not recognize the position of the sun, the region calculation unit performs division into respective regions based on subdivided levels of brightness, and the central processing unit calculates the position of the sun based on the respective regions and boundaries of the regions . The image capture unit captures respective preset regions of a celestial sphere using one or more cameras. The device further includes a control unit for enabling a user to control the device for tracking a position of a sun. Additionally, the present invention provides a method of tracking the position of the sun, including capturing an image of the celestial sphere using an image capture unit; calculating the brightness of the captured image using a region calculation unit, dividing the image into respective regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions; and calculating the position of the sun in the image from the regions and the boundaries using a central processing unit.
Furthermore, the method further includes setting the calculated position of the sun as a reference point; calculating a position of the sun by capturing an image of the celestial sphere again using the image capture unit and repeating the steps of calculating the position of the sun in the image; and tracking the position of the sun by comparing the reference point with the position of the sun in the image.
Preferably, the method may further include recognizing an initiation signal so as to initiate tracking of the position of the sun. Any one of current time reached after sunrise, an amount of solar light, equal to or greater than a predetermined amount, detected by an optical sensor, and the input of an initiation signal performed by a user may be recognized as the initiation signal .
If the reference point is not set, the method further include recognizing an initiation signal, performing division into respective regions based on subdivided levels of brightness using the region calculation unit, and calculating the position of the sun by repeating the steps of calculating the position of the sun in the image. Furthermore, if the position of the sun in the image is not recognized, the method further includes performing division into respective regions based on subdivided levels of brightness using the region calculation unit, and calculating the position of the sun by repeating the steps of calculating the position of the sun in the image. Preferably, the method further includes recognizing a termination signal so as to terminate the tracking of the position of the sun. Any one of current time reached after sunset, an amount of solar light, equal to or less than a predetermined amount, detected by an optical sensor, and input of a termination signal performed by a user may be recognized as the termination.
More preferably, if the termination signal is not input, the position of the sun is calculated by repeating the steps of calculating the position of the sun in the image.
Furthermore, the method further includes storing the calculated path of the sun in a storage unit, converting data about the path of the sun, stored in the storage unit or output from an output unit, into coordinates, and calculating an altitude and azimuth of the sun using the coordinates .
[Advantageous Effects]
According to the present invention, the position of a light source is tracked based on brightness, so that the accurate position of the sun can be effectively tracked even in the case where there are clouds, abnormal atmospheric conditions, or physical inference.
Furthermore, in the present invention, cameras can be made to capture respective predetermined regions of the celestial sphere using a plurality of cameras, so that the entire celestial sphere can be captured at one time, and so that images can be captured at fixed locations without moving the cameras, thereby more accurately detecting the path of the sun in the celestial sphere instantaneously. The present invention includes a control unit for enabling a user to control the device for tracking the position of the sun, so that the regions of the celestial sphere desired by a user can be captured and levels of brightness and the error range can be set by a user, with the result that the position of the sun can be tracked more accurately and the path of the sun can be detected more accurately.
Furthermore, the present invention recognizes an initiation signal and a termination signal, and thus does not track the sun in atmospheric conditions in which it is impossible to track the position of the sun or at night, so that unnecessary power consumption does not occur.
Moreover, the path of the sun can be converted into coordinates and can be used for other sun-related devices .
[Description of Drawings] FIG. 1 is a block diagram schematically showing an embodiment of prior art 1 (Korean Unexamined Patent Publication No. 10-2006-0011286);
FIG. 2 is a block diagram schematically showing an embodiment of prior art 2 (Korean Patent No. 10-0317811);
FIG. 3 is a block diagram showing the schematic structure of an embodiment of a device for tracking the position of the sun according to the present invention;
FIG. 4 shows an embodiment in which division into regions is performed based on brightness;
FIG. 5 shows an embodiment in which an image of the celestial sphere is divided into regions based on brightness according to the present invention;
FIG. 6 is a flowchart schematically showing a process in which the central processing unit of the device for tracking the position of the sun according to the present invention calculates the position of the sun;
FIG. 7 shows an embodiment in which the position of the sun is tracked on a clear day according to the present invention;
FIG. 8 shows an embodiment in which the position of the sun is tracked on a cloudy day according to the present invention;
FIG. 9 shows an embodiment in which the position of the sun is tracked according to the present invention in the case where the sun is hidden by an obstacle; FIG. 10 shows an embodiment in which the position of the sun is tracked according to the present invention in the case where the sun is hidden by clouds;
FIG. 11 shows an embodiment in which the position of the sun calculated according to the present invention is converted into coordinates;
FIG. 12 shows an embodiment in which a user controls the device for tracking the position of the sun according to the present invention; FIG. 13 shows an embodiment in which the position of the sun, calculated according to the present invention, is displayed such that a user can easily recognize the position of the sun;
FIG. 14 is a block diagram schematically showing an embodiment of a method of tracking the position of the sun according to the present invention; and
FIG. 15 is an embodiment showing the position of the sun obtained according to the present invention.
[Best Mode] A device for tracking the position of the sun according to the present invention, with reference to FIG. 3, includes an image capture unit 50 for capturing an image of the celestial sphere; a region calculation unit 60 for calculating the brightness of the image received from the image capture unit, dividing the image into a plurality of regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions; a central processing unit 70 for calculating the position of the sun in the image based on the boundaries; and an output unit 80 for outputting the position of the sun calculated by the central processing unit.
A method of tracking the position of the sun according to the present invention, with reference to FIGS. 3 and 14, includes capturing an image of the celestial sphere using an image capture unit 50; calculating the brightness of the captured image using a region calculation unit 60, dividing the image into respective regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining the boundaries of the respective regions; and calculating the position of the sun in the image from the regions and the boundaries using a central processing unit 70.
The method of tracking the position of the sun according to the present invention may further include setting the calculated position of the sun as a reference point; calculating the position of the sun by capturing an image of the celestial sphere again using the image capture unit 50 and repeating the steps of calculating the position of the sun in the image; and tracking the position of the sun by comparing the reference point with the position of the sun in the image.
[Mode for Invention]
With reference to the accompanying drawings, a device and method for tracking the position of the sun according to the present invention are described in detail below.
FIG. 3 shows the schematic structure of an embodiment of the device for tracking the position of the sun according to the present invention.
The device for tracking the position of the sun includes an image capture unit 50, a region calculation unit 60, a central processing unit 70, an output unit 80, a control unit 100, and a peripheral device 90.
The image capture unit 50 captures images of the celestial sphere. A camera equipped with a lens capable of collecting images across a wide range or a fisheye lens may be used as the image capture unit 30. When cameras are caused to capture respective predetermined regions of the celestial sphere using a plurality of cameras, the entire celestial sphere can be captured at one time, and images can be captured at fixed locations without moving cameras regardless of the movement of the sun in the celestial sphere, thereby more accurately detecting the path of the sun in the celestial sphere instantaneously.
The region calculation -unit 60 divides the image of the celestial sphere, received from the image capture unit 50, into a plurality of brightness sections based on levels of brightness, distinguishes the regions, and defines the boundaries of the regions. A method of dividing an image into regions based on levels of brightness is described with reference to FIGS. 4 and 5.
FIG. 4 (a) is a photo in which the brightness of an image is divided into 256 levels ranging from the brightest level to the darkest level . When the image captured by the digital camera is displayed on a personal computer, portions ranging from the darkest portion to the brightest portion are divided based on 256 levels of brightness and a minute difference in the amount of brightness is shown. Then, natural transition from a dark portion to a bright portion seems to occur. In the present invention, the maximum number of levels of brightness into which subdivision is performed is set to a maximum of 256 levels of brightness.
FIG. 4(b) is a photo that represents the image of FIG. 4 (a) based on 30 levels of brightness, with levels having similar brightness being integrated together. Furthermore, FIG. 4(c) is a photo that represents the image based on 16 levels of brightness, simplified compared to those of FIG. 4 (b) . In the image of the celestial sphere captured by the image capture unit 50, brightness is highest near the center portion of the sun and brightness decreases in proportion to the distance from the center of the sun.
When the brightness of the image is calculated and the image is divided into a plurality of brightness sections based on levels of brightness, brightness sections having similar levels can be presented as a single region.
FIG. 5 (a) shows an image of the celestial sphere on a clear day. When the image is represented based on 16 levels according to brightness, the photo shown in FIG. 5 (b) is obtained. When the image is represented based on 30 levels according to brightness, the photo shown in FIG. 5 (c) is obtained. As shown in FIG. 5 (b) or FIG. 5(c), when the image is divided into brightness sections having similar levels, semicircle-shaped regions are obtained around the sun. The region calculation unit 60 calculates the brightness of the image captured as described above, and divides the image into a plurality of brightness sections based on levels of brightness, such as 256 levels of brightness, 30 levels of brightness, or 16 levels of brightness. The resulting brightness sections are distinguished as respective regions, so that the entire image of the celestial sphere can be divided into respective regions.
The present invention allows appropriate levels of brightness to be searched for while causing the levels of brightness to proceed from simple levels to subdivided levels. Furthermore, the number of levels may be adjusted so as to cause the levels of brightness to be finer or rougher according to a user's necessity or the state of an image, attributable to weather or clouds. The central processing unit 70 calculates the position of the sun based on the boundaries of the respective regions, which will be described in detail below with reference to FIGS. 6 to 11.
FIG. 6 is a flowchart schematically showing a process in which the central processing unit 70 calculates the position of the sun.
When the brightness of an image 51 of the celestial sphere input by the region calculation unit 50 is calculated and the image is divided into a plurality of brightness sections based on levels of brightness, the image is divided into respective regions at step 61.
Whether circles are formed is determined based on the boundaries of the calculated regions at step 71.
If circles are formed, the process searches for appropriate levels of brightness while causing the levels of brightness to proceed from simple levels to subdivided levels, and forms circles in optimum conditions at step 72. Here, the forming of circles in optimum conditions refers to the forming of most appropriate circles while forming an inscribed circle, a circumscribed circle and a proximity circle based on the levels of brightness . Thereafter, one of the formed circles, including the region having the highest brightness, is determined at step 73.
When a circle is determined at step 73, an error range for the determined circle is calculated at step 77, and step 78 of determining whether the error range exceeds a tolerance range is performed. If the error range falls within the tolerance range, the position of the sun is determined at step 79. If the error range exceeds the tolerance range, an image of the celestial sphere is captured again at step 51 and the above-described steps of tracking the position of the sun are repeated. Here, the calculation of the error range is the measurement of the size of the determined circle, and the tolerance range refers to the range of the size of a circle, which is determined in the captured image, in which the circle can be considered the center of a light source. The tolerance range may vary depending on the state of the captured image, and the variation is determined depending on accumulated data and a user's setting.
Meanwhile, if it is determined that circles are not formed at step 71 of determining whether circles are formed based on the boundaries of the calculated regions, whether the boundaries of the regions and the extended lines of the boundaries have specific directionality is determined at step 74. If the boundaries and the extended lines of the boundaries have specific directionality, the range in which intersections, at which the boundaries of the respective regions intersect the extended lines of the respective boundaries, are formed at step 75 is searched for by searching for optimum conditions using the most appropriate levels of brightness while causing the levels of brightness to proceed from simple levels to subdivided levels . Thereafter, the range in which the intersections are formed is determined at step 76.
When the range of intersections is determined at step 73, an error range for the determined center is calculated, and whether the error range exceeds the tolerance range is determined at step 78. If the error range falls within the tolerance range, the position of the sun is determined at step 79. In contrast, if the error range exceeds the tolerance range, an image of the celestial sphere is captured again. Here, the calculation of the error range is the measurement of the size of the determined range, and the tolerance range refers to the range of the size of a range, which is determined in the captured image, in which the range can be considered the center of a light source. The tolerance range may vary depending on the state of the captured image, and the variation is determined depending on accumulated data and a user's setting.
A process in which the above-described central processing unit 70 calculates the position of the sun will be described in detail in conjunction with the embodiments below.
FIG. 7 (a) shows an image of the celestial sphere that was captured in broad daylight using a typical camera. FIG. 7 (b) is a photo that represents the image of FIG. 7 (a) based on 8 levels of brightness. In this photo, the size of the region having the brightest center brightness can be seen to be two times as large as that of FIG. 7 (a) . The reason for this is that the portion, other than an original center portion, can also be recognized as a center region by applying the same color to levels having similar brightness. Accordingly, in the case of the image, when division into regions is performed based on 8 levels of brightness shown in FIG. 7 (b) at step 61, circles are formed based on the boundaries of the regions at step 71, and the circle having the highest brightness can be obtained at step 73. However, when an error range for the calculated circle is calculated and the error range is compared with a tolerance range at step 78, the size of the calculated circle is excessively large, so that the error range exceeds the tolerance range. Therefore, in this case, the process returns to step 51 of capturing an image of the celestial sphere, and the steps of calculating the position of the sun are repeated. In this case, the process searches for appropriate levels of brightness while causing the levels of brightness to proceed from simple levels to subdivided levels, and circles are formed in an optimum condition.
FIG. 7 (c) is a photo that represents the image of FIG. 7 (a) based on 16 levels of brightness, FIG. 7 (d) is a photo that represents the image of FIG. 7 (a) based on 30 levels of brightness, and FIG. 7 (e) is a photo that represents the image of FIG. 7 (a) based on 60 levels of brightness. As shown in the photos, it can be seen that the size of the center portion decreases accordingly when the number of levels of brightness is increased by dividing brightness into finer levels. Since the load to be processed is increased in proportion to the number of levels of brightness, it is necessary to form circles based on appropriate levels of brightness. As a result, the number of levels is adjusted to perform classification into an appropriate number of levels so as to search for optimum conditions and thus reduce the error range. Alternatively, the number of levels is adjusted according to a user's necessity or the state of an image attributable to weather.
FIG. 7(f) is a photo in which the levels of brightness are set according to a user's necessity, and FIG. 7 (g) is a photo that is set such that the boundaries of the regions of FIG. 7(f) are represented. FIG. 7 (h) is a photo showing imaginary circles based on the boundaries of respective regions, obtained through division based on the brightness of FIG. 7(f). The circles may be implemented as proximity circles, inscribed circles, and circumscribed circles based on the distribution of the same brightness . Error can be reduced by repeatedly implementing the shapes of respective circles and accumulating processing results. FIG. 7 (h) shows an embodiment in which circles near genuine circles are gradually searched for based on the boundaries of respective regions, and proximity circles are formed. FIG. 7(i) is a photo in which the levels of brightness are adjusted for optimum conditions according to a user's necessity or in consideration of error attributable to some other factor, such as weather, and the boundaries of regions are formed to be complete circles accordingly. Since the circles are arranged around a center light source, the center circle having the highest brightness can be estimated to be the center of the sun.
FIG. 8 (a) shows an image of the celestial sphere on an overcast day having heavy cloud. It is impossible to track the position of the sun using only the image. However, when, according to the present invention, the region calculation unit 20 divides the image into regions according to brightness based on levels having specific ranges at step 61 and the boundaries thereof are represented, FIG. 9 (b) is obtained. An optimum condition is searched for by implementing proximity circles, inscribed circles, and circumscribed circles based on the boundaries of the resulting regions. In the case of the present embodiment, when proximity circles or inscribed circles are formed, the upper end portions of regions having the same brightness levels are not included. Accordingly, circles most suitable for the present case are circumscribed circles that can include the portions. When circumscribed circles having the boundaries of the regions are formed at step 72, FIG. 8(c) is obtained. When the implementation of a circle is repeated, an error range is calculated based on accumulated error, and the circle having the conditions most suitable for the error range is obtained, the region of FIG. 8 (d) is realized. According to the present invention, when the determined circle is included in the tolerance range of error, that is, in a predetermined area, the sun is recognized as being located in the circle, as shown in FIG. 8(e) .
FIG. 9 (a) shows an image of the celestial sphere in the situation in which the sun is hidden by an obstacle. According to the prior art, it is difficult to track the position of the sun using only the image of FIG. 9 (a) . FIG. 9 (b) is a photo that represents FIG. 9 (a) based on 16 levels of brightness according to the present invention, from which it can be visually confirmed that a vague difference in brightness appears. FIG. 9(c) is a photo that represents the boundaries of respective regions according to the difference in brightness. FIG. 9 (d) is a photo that is controlled according to conditions set by a user in order to more clearly distinguish regions for FIG. 9(c). Such control by the user will be described in detail below. When the regions are clearly distinguished as described above at step 61, circles corresponding to an optimum condition are formed using a proximity circle, an inscribed circles and a circumscribed circle based on the boundaries of respective circles at step 73. When a proximity circle or an inscribed circle is formed in the above case, a large part of a region having the same brightness levels is located outside the average circle or inscribed circle. In this case, when a circle formed of an average circle or an inscribed circle is determined to be a center, an error occurs in the accurate tracking of the position of the sun. Accordingly, in the present invention, in the case where a circle formed of an average circle or an inscribed circle does not include a predetermined percentage of a region having the same brightness levels, a circle is formed using a circumscribed circle.
When the most appropriate circle is formed through the above-described process of repeatedly forming circles at step 72, circumscribed circles suitable for the boundaries of respective regions can be formed, as shown in FIG. 9(e) . When an error range for the formed circumscribed circles is calculated and the error range falls within the tolerance range of error at step 78, that is, when the center region is included in a predetermined area, the sun is recognized as being located inside the center region, as shown in FIG. 9 (f) .
FIG. 10 (a) is an image of the celestial sphere in which it is difficult to detect the location of the sun because the sun is hidden by clouds. Although, even in this case, it is possible to perform division into regions based on levels of brightness, it is difficult to form circles based on obtained regions due to a distortion phenomenon, because light from the sun is scattered by interfering objects or clouds. In this case, when inappropriate circles are formed unreasonably, an error in which the light source is found to have a plurality of locations occurs.
Accordingly, in the present invention, in the above case, the center of the sun is searched for through another process. Since light has a characteristic of traveling in a straight line, it can be found that a light is located at the intersection at which light beams meet and which is found by retro-tracking the light beams. The present invention tracks the position of the sun using a characteristic in which light travels in a straight line. Another process of tracking the position of the sun using the characteristic of light of traveling in a straight line according to the present invention is described in detail with reference to FIG. 10 below.
FIGS. 10 (b) and 10 (c) are photos that represent the image of FIG. 10 (a) based on 8 levels of brightness and 16 levels of brightness, respectively. When the images of FIG. 10 (b) and FIG. 10 (c) are divided into regions based on levels of brightness, appropriate circles based on regions are not formed.
Accordingly, in this case, the present invention tracks the position of the sun using another method based on the characteristic in which light travels in a straight line.
From FIG. 10 (b) and FIG. 10 (c), it can be seen that portions where brightness abruptly changes are present between regions. In this case, when the boundaries of the portions where the abrupt difference in brightness appears between respective regions are present, it can be seen that the boundaries have straight line shapes having specific directionality. When the boundaries and the extended lines of the boundaries are illustrated, FIG. 10 (d) is obtained. As shown in FIG. 10 (d) , it can be seen that the boundaries and the extended lines of the boundaries have specific directionality at step 74 and that intersections are formed between the boundaries and the extended lines within a certain range at step 75.
When the boundaries of respective regions and the extended lines are represented in optimum conditions based on the repeated implementation of intersections and accumulated error in order to determine the range within which the intersections are formed, the range for the intersections are determined at step 76, as shown in FIG. 10 (e) . An error range is calculated for the range where the intersections are formed, and the sun is recognized as being located within the range where the intersections are formed if the error range is smaller than a predetermined area, which is a tolerance range.
As described above, the present invention can track the position of the sun using the characteristic in which light travels in a straight line even in the case where it is difficult to detect the position of the sun because the sun is hidden by clouds and in the case where it is difficult to search for the sun due to distortion because light from the sun is scattered by an interfering object or clouds .
When the central processing unit 30 calculates the position of the sun as described above, data about the calculated position of the sun is output through the output unit 80 and is then input to a monitor for displaying the calculated position of the sun, a storage unit, or a sun- related device. As shown in FIG. 11, the storage unit can store data, calculated by tracking the position of the sun, in the form of coordinate data.
As described above, the device for tracking the position of the sun according to the present invention can accurately track the position of the sun even in a situation in which undesired weather, clouds or an obstacle is present.
The present invention further includes a control unit 100 for allowing a user to control the device for tracking the position of the sun. The control unit 100 controls the image capture unit 50 so that it can capture the region of the celestial sphere desired by a user, as shown in FIG. 12. Furthermore, in order to more accurately calculate the position of the sun, it is possible to set the above- described levels of brightness or error range. Furthermore, in order to allow a user to accurately determine the position of the sun, the position of the sun is indicated, as shown in FIG. 13, so that a user can determine the position of the sun more conveniently.
The present invention includes a method of tracking the position of the sun. The method of tracking the position of the sun according to the present invention is described below.
In the method of tracking the position of the sun according to the present invention, the image capture unit 50 captures an image of the celestial sphere, and the region calculation unit 60 distinguishes respective regions by dividing the captured image into a plurality of brightness sections based on levels of brightness, and defines the boundaries of the regions. Thereafter, the central processing unit 70 obtains the position of the sun from the image based on the regions and the boundaries .
Moreover, the position of the sun in the obtained image is set as a reference point, the image capture unit captures an image again, the region calculation unit 60 perform division into regions, the central processing unit 70 calculates the position of the sun by processing the regions of the image, and the path of the sun is calculated by comparing the set reference point with the calculated position of the sun.
The method of tracking the position of the sun according to the present invention is described in greater detail with reference to FIG. 14 (in the following description, an image of the celestial sphere for calculating a reference point is designated as a first image, and an image of the celestial sphere to be used for comparison with the reference point is designated as a second image) .
When an initiation signal is recognized at step SlOO, the method of tracking the position of the sun receives a first image of the celestial sphere through step SlIO of capturing the first image of the celestial sphere using the image capture unit 50, and distinguishes respective regions through step S120 of dividing the first image into the respective regions based on levels of brightness using the region calculation unit 60.
Thereafter, the method goes through step S130 of obtaining the position of the sun for the first image by- processing the respective regions using the central processing unit 70. At step S130 of obtaining the position of the sun for the first image, the position of the sun is obtained through the process described above in conjunction with FIG. 6.
If the position of the sun for the first image has been obtained, the method goes through step S140 of setting the position of the sun as a reference point. However, if the position of the sun for the first image has not been obtained, the method returns to step SlOO of recognizing an initiation signal, and then repeats the steps of obtaining the position of the sun from the above-described first image.
When the reference point is set, the method receives a second image through step S150 of capturing a second image of the celestial sphere using the image capture unit 50, and distinguishes respective regions through step S120 of dividing the second image of the celestial sphere into the respective regions based on levels of brightness using the region calculation unit 60.
Thereafter, the method goes through step S170 of obtaining the position of the sun for the second image by processing the respective regions using the central processing unit 70. At step S170 of obtaining the position of the sun for the second image, the position of the sun is also obtained through the process described above in conjunction with FIG. 6.
If the position of the sun for the second image has been obtained, data about the path of the sun is obtained through step S180 of calculating the path of the sun by comparing the set reference point with the position of the sun obtained from the second image. However, if the position of the sun for the second image has not been obtained, the method returns to step S150 of capturing a second image of the celestial sphere using the image capture unit 50 and repeating the steps of obtaining the position of the sun from the second image.
When a termination signal is recognized at step S190 of recognizing a termination signal after data about the path of the sun has been obtained, the method of tracking the position of the sun is terminated. If the termination signal is not recognized, the method returns to step S150 of capturing a second image of the celestial sphere using the image capture unit 50 and tracks the path of the sun by repeating the steps of calculating the position of the sun for the above-described second image.
At step SlOO of recognizing an initiation signal, the current time reached after sunrise, an amount of solar light, equal to or greater than a predetermined amount, detected by an optical sensor, or the input of an initiation signal performed intentionally by a user is recognized as an initiation signal.
Furthermore, at step S190 of recognizing a termination signal, the current time reached after sunset, an amount of solar light, equal to or less than a predetermined amount, detected by an optical sensor, or the input of a termination signal performed intentionally by a user is recognized as a termination signal.
Furthermore, data about the calculated path of the sun is stored in a storage unit, or the stored data about the path of the sun is converted into coordinates and the altitude and azimuth of the sun can be calculated using the coordinates .
FIG. 15 is photos showing a method of tracking the path of the sun in such a way as to track the position of the sun, convert the tracked position into coordinates, calculate the azimuth and altitude of a reference point using the coordinates, and perform relative coordinate analysis by comparing the position of the sun after the reference time with a reference point. The photos are collected at time intervals of 30 minutes, and an azimuth of two degrees and an altitude of one degree are assigned to one grid square. Using the method of tracking the position of the sun according to the above-described present invention, the path of the sun is detected more accurately, the calculated path of the sun is converted into coordinates, and the coordinates can be used in other sun-related devices.
The device and method for tracking the position of the sun according to the present invention can be modified and applied in various forms within the scope of the technical spirit of the present invention, and are not limited to the above-described embodiments. Furthermore, the embodiments and the drawings are intended only to describe the content of the present invention in detail, and are not intended to limit the scope of the technical spirit of the present invention. It is apparent to those having ordinary skill in the field to which the present invention pertains that various substitutions, modifications and variations can be made without departing from the technical spirit of the present invention. Accordingly, the present invention is not limited to the embodiments, and the accompanying drawings and the present invention must be interpreted as including not only the attached claims, but also ranges equivalent to the attached claims .
[industrial Applicability] In the device and method for tracking the position of the sun according to the present invention, the position of a light source is tracked based on brightness, so that the position of the sun can be accurately and efficiently tracked even in the case where clouds, abnormal atmospheric conditions or physical interference are present, thus being able to be used in all systems and devices requiring the tracking of the position of the sun, including power generation apparatuses using solar light or solar heat.

Claims

[CLAIMS] [Claim l]
A device for tracking a position of a sun, comprising: an image capture unit for capturing an image of a celestial sphere; a region calculation unit for calculating brightness of the image received from the image capture unit, dividing the image into a plurality of regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining boundaries of the respective regions; a central processing unit for calculating the position of the sun in the image based on the boundaries; and an output unit for outputting the position of the sun calculated by the central processing unit.
[Claim 2]
The device as set forth in claim 1, wherein, if circles are formed based on the boundaries, and a circle, belonging to the circles for the respective regions and including a highest brightness section, forms a predetermined area, the central processing unit recognizes the sun as being located within the circle.
[Claim 3]
The device as set forth in claim 1, wherein, if the boundaries of the regions and extended lines of the boundaries have specific directionality and intersections between the boundaries of the regions and the extended lines of the boundaries are formed within a predetermined range, the central processing unit recognizes the sun as being located within the range.
[Claim 4] The device as set forth in claim 2 or 3, wherein, if the central processing unit does not recognize the position of the sun, the region calculation unit performs division into respective regions based on subdivided levels of brightness, and the central processing unit calculates the position of the sun based on the respective regions and boundaries of the regions .
[Claim 5]
The device as set forth in claim 2 or 3, wherein the image capture unit captures respective preset regions of a celestial sphere using one or more cameras.
[Claim 6]
The device as set forth in claim 2 or 3, further comprising a control unit for enabling a user to control the device for tracking a position of a sun .
[Claim 7]
A method of tracking a position of a sun, comprising: capturing an image of a celestial sphere using an image capture unit; calculating brightness of the captured image using a region calculation unit, dividing the image into respective regions by dividing the image into a plurality of brightness sections based on levels of brightness, and defining boundaries of the respective regions; and calculating the position of the sun in the image from the regions and the boundaries using a central processing unit.
[Claim 8] The method as set forth in claim 7, further comprising: setting the calculated position of the sun as a reference point; calculating a position of the sun by capturing an image of the celestial sphere again using the image capture unit and repeating the steps of calculating the position of the sun in the image; and tracking the position of the sun by comparing the reference point with the position of the sun in the image.
[Claim 9]
The method as set forth in claim 8, further comprising recognizing an initiation signal so as to initiate tracking of the position of the sun.
[Claim 10]
The method as set forth in claim 9, wherein any one of current time reached after sunrise, an amount of solar light, equal to or greater than a predetermined amount, detected by an optical sensor, and an input of an initiation signal performed by a user is recognized as the initiation signal .
[Claim 11]
The method as set forth in claim 9, further comprising, if the reference point is not set, recognizing an initiation signal, performing division into respective regions based on subdivided levels of brightness using the region calculation unit, and calculating the position of the sun by repeating the steps of calculating the position of the sun in the image.
[Claim 12]
The method as set forth in claim 8, further comprising, if the position of the sun in the image is not recognized, performing division into respective regions based on subdivided levels of brightness using the region calculation unit, and calculating the position of the sun by repeating the steps of calculating the position of the sun in the image.
[Claim 13]
The method as set forth in claim 8, further comprising recognizing a termination signal so as to terminate the tracking of the position of the sun.
[Claim 14]
The method as set forth in claim 13, wherein any one of current time reached after sunset, an amount of solar light, equal to or less than a predetermined amount, detected by an optical sensor, and input of a termination signal performed by a user is recognized as the termination.
[Claim 15]
The method as set forth in claim 13, wherein, if the termination signal is not input, the position of the sun is calculated by repeating the steps of calculating the position of the sun in the image.
[Claim 16] The method as set forth in claim 8, further comprising storing the calculated path of the sun in a storage unit, converting data about the path of the sun, stored in the storage unit or output from an output unit, into coordinates, and calculating an altitude and azimuth of the sun using the coordinates.
PCT/KR2007/002929 2006-06-16 2007-06-15 Device for tracking solar position and method thereof WO2007145489A1 (en)

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