Method, computer program product and data processing system for determining a position of an object in space

Abstract

The invention relates to a method for determining at least one position of an object in space, in which an image recording apparatus (100) is used, comprising at least one camera system (10), a time synchronisation unit (30) and a computing unit (40). The camera system (10) is used to record at least one image (22, 23, 24, 25) of the object with a specified exposure time. The time synchronisation unit (30) is used to assign to the image (22, 23, 24, 25) a start time (50) and an end time (60). A start position (72) and an end position (74) of the object are determined on the image. The computing unit (40) is used to ascertain a corrected start time (54) from the start time (50) with at least one predetermined switch-on delay (52) of the camera system (10) and a corrected end time (64) from the end time (60) with at least one predetermined switch-off delay (62) of the camera system (10). The corrected start time (54) is assigned to the start position (72) of the object and the corrected end time (64) to the end position (74) of the object.

Description

[0001] Description

[0002] title

[0003] METHOD, COMPUTER PROGRAM PRODUCT AND DATA PROCESSING SYSTEM FOR DETERMINING A POSITION OF AN OBJECT IN SPACE

[0004] State of the art

[0005] The invention relates to a method for determining at least one position of an object in space, in particular an orbital object in near-Earth space, as well as a computer program product and data processing system for determining at least one position of an object in space, in particular an orbital object in near-Earth space.

[0006] Passive optical detection of space objects is known. Such a system typically comprises a camera connected to a lens that observes the starry sky.

[0007] Measurements of an object's position recorded with such a system typically exhibit a relatively small measurement error transverse to the trajectory, but a relatively large measurement error along the trajectory direction. DE 20 2017 101 831 U1 describes a system for determining and / or predicting a position and / or trajectory of orbital objects in space, particularly in near-Earth space, comprising a first optical image recording device for recording first images of space, an image processing device for processing the first images recorded with the first image recording device, and for determining position coordinates of orbital objects by comparing at least two recorded first images.The system comprises a second optical image recording device which is aligned with the position coordinates of an orbital object determined by the image processing device and is tracked to track the same.

[0008] Disclosure of the invention

[0009] The object of the invention is to provide a method for determining a position of an object in space, in particular in near-Earth space, which allows a more precise position determination.

[0010] A further object of the invention is to provide a computer program product for determining at least one position of an object in space, in particular in near-Earth space, which allows a more precise position determination.

[0011] A further object of the invention is to provide a data processing system for executing a data processing program, which comprises computer-readable program instructions for carrying out such a method.

[0012] The objects are achieved by the features of the independent claims. Advantageous embodiments and advantages of the invention emerge from the further claims, the description, and the drawings. The features listed individually in the patent claims can be combined with one another in a technologically expedient manner and can be supplemented by explanatory facts from the description and details from the figures, thereby demonstrating further embodiments of the invention.

[0013] According to one aspect of the invention, a method for determining at least one position of an object in space, in particular an orbital object in near-Earth space, is proposed, in which method an image recording device is used, comprising at least one camera system, a time synchronization unit, and a computing unit. At least one image of the object is recorded with the camera system using a predetermined exposure time. The time synchronization unit assigns a start time and an end time to the image. An start position and an end position of the object are determined in the image. The computing unit determines a corrected start time from the start time with at least one predetermined switch-on delay of the camera system, and a corrected end time from the end time with at least one predetermined switch-off delay of the camera system.The corrected start time is assigned to the start position of the object and the corrected end time is assigned to the end position of the object.

[0014] The start and end times of the image are correlated with the exposure time. Except for system-related latencies in the electronic control of the image recording device, the exposure time corresponds to the difference between the end time and the start time. The switch-on delay represents a time delay, particularly a position-dependent delay, when the camera system captures the image relative to a start signal to the camera system, and the switch-off delay represents a time delay, particularly a position-dependent delay, when the camera system stops capturing the image relative to an end signal.

[0015] If the exposure time is short compared to the movement of the object, the starting position and the end position can be the same.

[0016] The object can, in particular, be an orbital object that orbits the Earth. The at least one position can be a current position of the object and / or a future position of the object. Furthermore, the at least one position of the object can comprise multiple positions that, when added together, result in a trajectory of the object in space. Temporally, the trajectory can have a starting point in the past or the present and an end point in the present or the future.

[0017] In the proposed method, the accuracy of passive optical object detection in space, particularly with respect to the measurement error in the object's trajectory direction, is increased by assigning precise times to the object's positions via calibration, namely corrected start and end times for the object's initial and final positions when the image is captured. This calibration includes delay times both for activating or opening a shutter of a detector of the camera system in the form of at least one predetermined switch-on delay, and for deactivating or closing the shutter in the form of at least one predetermined switch-off delay relative to a start signal or end signal of the camera system.Advantageously, the proposed method can significantly reduce errors in determining at least one position of an object in space, for example, the trajectory of an orbital object in near-Earth space. In particular, a measurement error in the object's trajectory direction can be favorably reduced.

[0018] According to a favorable embodiment of the method, in order to determine the corrected starting time, a switch-on delay dependent on the starting position can be selected from the at least one predetermined switch-on delay depending on the starting position, and in order to determine the corrected end time, a switch-off delay dependent on the end position can be selected from the at least one predetermined switch-off delay depending on the end position.

[0019] The corrected start time can advantageously be determined as the sum of the start time and a switch-on delay dependent on the start position from the at least one predetermined, positive or negative, switch-on delay and the corrected end time as the sum of the end time and the at least one predetermined, positive or negative, switch-off delay.

[0020] The switch-on delay for a position on the detector of the camera system is positive if the camera system starts recording the image with a start signal and a camera shutter only releases the corresponding detector position for exposure with this switch-on delay. A negative switch-on delay can occur if the image is already imaged on the detector and only then does the start signal for the camera system come. The switch-off delay for a position on the detector of the camera system is positive if the camera system ends recording the image with an end signal and a camera shutter only covers the corresponding detector position with this switch-off delay. A negative switch-off delay can occur if the exposure of the position on the detector has already ended and only then does the end signal for the camera system come.

[0021] These at least one switch-on delay and switch-off delay can be predetermined, for example, depending on the position of the object, in particular row and column in the image on an area detector of the camera system.

[0022] Such position-dependent delay times can be conveniently recorded in a table and used to correct the start and end times of objects. Both positive and negative delay times can be added to the start and end times depending on the object's position in the image to determine the corrected start and end times.

[0023] According to a favorable embodiment of the method, the camera system can have at least one optical imaging device, in particular a telescope, and an optical detector designed as a two-dimensional area detector with pixels arranged in rows and columns for spatially resolved recording of image data. In this case, the predetermined switch-on delay and switch-off delay are predetermined pixel-dependently. Advantageously, according to the proposed method, when a start signal is sent to the camera system, which in turn triggers time signals from the time synchronization unit, such as a so-called GPS timer, with a trigger signal, the position-dependent or pixel-dependent delay time between this trigger signal and the actual activation and deactivation times of the camera system's detector or the opening and closing times of the detector's shutter can be taken into account.This delay time depends on the position of a pixel in rows and columns on the detector surface and can be influenced by the shape and operation of a mechanical or electronic shutter or the response behavior and readout method of the digital area detector.

[0024] According to a favorable embodiment of the method, the at least one image of the object can be recorded with an exposure time that is long enough for the object to be imaged as a streak and short enough for stars to be imaged as points. The initial position of the object can correspond to the beginning of the streak and the final position of the object can correspond to the end of the streak. Such a long exposure time can be, for example, one second, depending on the image recording device used and the movement of the object. To determine the corrected start time and the corrected end time, the at least one switch-on delay and the at least one switch-off delay can be used depending on a position of the beginning and end of the streak on the detector.Position-dependent delay times can advantageously be used to correct the start and end times of images from the image recording device. This advantageously allows a time-dependent position determination of the object based on the streak trace. For this purpose, the start and end positions of the streak trace are expediently determined. The angular coordinates of these positions can be determined using astrometric calibration based on stars. Here, the stars depicted in the image are detected and compared with a star catalog to convert the image coordinates into equatorial coordinates. In addition, the start and end times of the streak trace are determined via the time synchronization unit. This is done by generating a start signal that starts the long-exposure exposure and an end signal that ends the image acquisition.This long exposure can be initiated by opening a mechanical shutter or by starting data recording with an electronic trigger signal. The start and end signals are then also sent to the time synchronization unit, and the exact time, preferably a UTC time, is recorded. Additionally, the corrected start and end times are determined by the processing unit, as described above, and assigned to the start and end positions.

[0025] According to a favorable embodiment of the method, at least one image of the object can be captured with an exposure time short enough to produce a point-like image of both the object and the stars. In this case, the initial and final positions of the object are the same.

[0026] Another option for detecting objects in space is to capture and process images with a relatively short exposure time. Instead of taking images with relatively long exposure times, images are taken with shorter exposure times. In these images, an object in near-Earth space can then appear as a point or a shorter line trail, depending on the exposure time. It is particularly preferable for the object to expose only one pixel of the camera system during the exposure time. However, the point or the shorter line trail may be faint.

[0027] According to a further advantageous embodiment of the method, a series of images of the object are taken with a time shift between the images.

[0028] This advantageously allows for a time-dependent position determination of the object based on multiple streak traces. For this purpose, the beginning and end of each streak trace, and thus the starting and ending positions of the object, are determined. The angular coordinates of these positions can be determined using astrometric calibration based on stars. The stars depicted in the image are detected and compared with a star catalog to convert the image coordinates into equatorial coordinates. In addition, the corrected start and end times of the streak trace can be recorded.

[0029] From the sum of the beginning and end of each individual streak trace and the recorded corrected start and end times for the object's start and end positions, a precise orbital trajectory of the object can be determined. It can also be advantageous to use the end of a streak trace with the beginning of the streak trace from the subsequent image, with the assigned corrected start and end times, as an additional, not actually shown, streak trace when calculating the object's orbital trajectory.

[0030] The images can be shifted relative to each other in at least one direction and superimposed to form at least one composite image. In particular, the images can be superimposed to form a composite image with maximum intensity. The images can be shifted and superimposed until a point or line trace with maximum intensity is visible. The initial and final positions of the object can be determined from the composite image.

[0031] In the described so-called synthetic tracking, the images can be systematically shifted by a specific number of pixels in the x and y directions and then superimposed to form at least one composite image. If the correct shift direction and shift range have been found, the object appears in this superimposed image as a very bright point or, in the case of a somewhat longer exposure time, as a bright, short line, while the brightness of stationary or otherwise moving objects becomes very dim. The advantage of this approach is that it can increase the sensitivity for detecting weakly reflective, i.e. small, objects. It is estimated that, depending on the image recording device used, objects as small as 14 cm can be detected using this method.The object's flight direction and flight speed are then determined from the determined initial position and final position, along with the corrected initial time and final time. According to a favorable embodiment of the method, the corrected initial time of the first image in the series of images can be selected as the corrected initial time of the object's initial position in the composite image, and the corrected final time of the last image in the series of images can be selected as the corrected final time of the object's final position in the composite image. Alternatively, it is also possible to temporally correct the intermediate images.

[0032] In this case, an image can be generated with a virtually longer exposure time, where the corrected start time can correspond to the corrected start time of the object's initial position in the first image of the series of images, and the corrected end time can correspond to the corrected end time of the object's final position in the last image of the series of images. The starting point of this calculated line trace can advantageously be assigned to the starting time of the first image from the evaluated image series. The end point of the calculated line trace corresponds to the end time of the last image in the series of images.

[0033] According to a favorable embodiment of the method, the optical imaging device can be defocused, especially slightly, so that the object illuminates multiple pixels of the optical detector. In this case, a center of gravity of the object's image can be determined, which leads to higher resolution accuracy than is possible with focusing on only a single pixel. This allows for greater accuracy in determining the object's initial and final position.

[0034] According to a favorable embodiment of the method, the at least one switch-on delay and / or the at least one switch-off delay of the camera system can be determined during a calibration measurement by switching a light source with a time delay when the camera system captures an image. Advantageously, a calibration measurement can thus be performed to determine the at least one position-dependent switch-on delay and / or the at least one position-dependent switch-off delay. In particular, the switching of the light source when the camera system captures an image can occur with a variable time delay and be performed repeatedly until the at least one switch-on delay and / or the at least one switch-off delay is determined for all areas of the image.

[0035] According to a favorable embodiment, the method can comprise at least the following steps: sending a first trigger signal to a delay generator when the camera system starts recording the image; sending a time-delayed signal with a time delay to the light source; switching off the light source based on the time-delayed signal; determining a transition region between a bright area and a dark area of ​​the image; assigning the time delay of the time-delayed signal as a switch-on delay to the areas of the image that lie in or around the transition region between the bright area and the dark area. The steps are repeated with an increased or decreased time delay of the time-delayed signal until a switch-on delay is assigned to all areas of the image.

[0036] Alternatively or additionally, the method may further comprise: sending a second trigger signal to the delay generator upon completion of the image capture by the camera system; sending the time-delayed signal to the light source; switching on the light source based on the time-delayed signal; determining a transition region between the dark region and the bright region of the image; assigning a time delay of the time-delayed signal as a switch-off delay to the regions of the image that lie in or around the transition region between the bright region and the dark region. The steps are repeated with an increased or decreased time delay of the time-delayed signal until a switch-off delay is assigned to all regions of the image.

[0037] The time-delayed signal can cause the light source to be switched on or off directly or indirectly, for example via a light control unit.

[0038] For example, a computer unit sends the camera system the command to take a new image, whereupon the camera system begins doing so as soon as possible. When the image is first taken, the light source illuminates a screen, which is then sharply imaged by the camera system. When the exposure begins, when the shutter opens, the camera system sends out a first trigger signal. This is passed through a variable delay generator and delayed accordingly. The resulting signal is sent to the light source, e.g. an LED, which then changes its state from on to off. Pixels that are only exposed after the delay time appear dark, while the other pixels that have already been exposed are visible as bright. The transition area between the bright and dark area then corresponds to the line that has the corresponding switch-on delay.

[0039] The functionality is independent of the type of shutter. By repeating and statistically averaging many measurements, a table can be created containing a specific switch-on delay time for each pixel position of the detector. This delay time can also be determined for switch-off in a similar way. The camera sends a second trigger signal at the end of the exposure time to close the shutter. This signal can then be used in an analogous manner, switching the light source from off to on. This allows the switch-off delay for the pixels located in the transition region between the dark and bright areas to be advantageously determined.

[0040] Advantageously, the time delay of the time-delayed signal is varied and the recording of the image is repeated until all areas of the image are assigned a switch-on delay and / or switch-off delay.

[0041] According to a favorable embodiment of the method, the at least one switch-on delay and / or the at least one switch-off delay can be assigned to the pixels of the optical detector of the camera system that are located in the transition region between the bright area and the dark area of ​​the image or are immediately adjacent. Advantageously, position-dependent values ​​for the switch-on delay and / or switch-off delay can be determined in this way.

[0042] According to a favorable embodiment of the method, the position of the object can be determined as angular coordinates via an astrometric calibration based on stars and / or constellations captured in the image. This advantageously allows for precise position determinations of, in particular, orbital objects. According to a favorable embodiment of the method, the position of the object can be stored together with the corrected start time and the corrected end time. In particular, the position of the object can be stored together with the corrected start time and the corrected end time as data for course tracking, particularly in a web-based database. In addition, the object's position data can be stored together with weather data.

[0043] The result of the position determination can advantageously consist of a data set for the overflight of an object through the field of view of the lens. This data set contains two UTC times for each long-exposure image, namely the corrected start time and the corrected end time, as well as two angles for each of these times, which are specified in a geocentric coordinate system. This information can be combined into a so-called Tracking Data Message (TDM). This information can then be used to perform an initial trajectory calculation.

[0044] According to a further aspect of the invention, a computer program product for determining at least one position of an object in space, in particular an orbital object in near-Earth space, is proposed. It utilizes an image recording device comprising at least one camera system, a time synchronization unit, and a computing unit. The camera system captures at least one image of the object with a predetermined exposure time. The time synchronization unit assigns a start time and an end time to the image. A start position and an end position of the object are determined on the image.The computer program product comprises at least one computer-readable storage medium containing program instructions executable on a computer system that cause the computer system to execute a method, wherein the computing unit determines a corrected start time from the start time with at least one predetermined switch-on delay of the camera system and a corrected end time from the end time with at least one predetermined switch-off delay of the camera system. The corrected start time is assigned to the initial position of the object, and the corrected end time is assigned to the final position of the object.

[0045] The object can, in particular, be an orbital object that orbits the Earth. The at least one position can be a current position of the object and / or a future position of the object. Furthermore, the at least one position of the object can comprise multiple positions that, when added together, result in a trajectory of the object in space. Temporally, the trajectory can have a starting point in the past or the present and an end point in the present or the future.

[0046] Advantageously, the accuracy of passive optical object detection in space, particularly with respect to the measurement error in the object's trajectory direction, can be increased by assigning precise start and end times to the images via calibration. This calibration includes delay times both for activating or opening a shutter of a detector of the camera system in the form of at least one predetermined switch-on delay, and for deactivating or closing the shutter in the form of at least one predetermined switch-off delay relative to a trigger signal. These delay times can advantageously be determined depending on the position, in particular row and column, on an area detector of the camera system.The computer program product comprises software code sections that can be loaded directly into the memory of a digital computer and that carry out the method when the software code sections are executed by the computer.

[0047] The computer program product may be formed by a computer program or, in addition to the computer program, may comprise at least one additional component. The at least one additional component may be implemented as hardware and / or software.

[0048] An example of the at least one additional component that is embodied as hardware is a storage medium that is readable by the digital computer and / or on which the software code sections are stored.

[0049] An example of the at least one additional component embodied as software is a cloud application program that is configured to distribute the software code sections to different processing units, in particular different computers, of a cloud computing system, wherein each of the processing units is configured to execute one or more software code sections.

[0050] In particular, the method as described above can be carried out with the software code sections when the software code sections are executed by the processing units of the cloud computing system. According to a further aspect of the invention, a data processing system for executing a data processing program is proposed, which comprises computer-readable program instructions for executing a method for determining at least one position of an object in space, in particular an orbital object in near-Earth space.

[0051] drawing

[0052] Further advantages will become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0053] Examples include:

[0054] Fig. 1 shows an image recording device for determining at least one position of an object in space, in particular an orbital object in near-Earth space, using a method according to an embodiment of the invention;

[0055] Fig. 2 shows a calibration setup for determining a switch-on delay and / or a switch-off delay according to an embodiment of the invention;

[0056] Fig. 3 shows an image of an object in space taken with the image recording device according to Fig. 1;

[0057] Fig. 4 an explanation of a method for generating a

[0058] Sum image from a series of recorded images of an object according to a further embodiment of the invention; Fig. 5 shows a superposition of three images to generate a sum image according to the further embodiment of the invention;

[0059] Fig. 6 shows an evaluation of a series of images by superimposing them to form a sum image according to the further embodiment of the invention; and

[0060] Fig. 7 is a flowchart of the method for determining at least one position of an object in space, in particular an orbital object in near-Earth space, according to an embodiment of the invention.

[0061] Embodiments of the invention

[0062] In the figures, components of the same type or function similarly are designated by the same reference numerals. The figures are merely examples and are not to be construed as limiting.

[0063] Before describing the invention in detail, it should be noted that it is not limited to the specific components of the device and the specific method steps, as these components and methods may vary. The terms used herein are intended solely to describe particular embodiments and are not intended to be limiting. Furthermore, when the singular or indefinite articles are used in the description or claims, this also refers to the plural of these elements, unless the overall context clearly indicates otherwise.

[0064] The directional terminology used below, including terms such as "left," "right," "top," "bottom," "before," "behind," "after," and the like, is intended solely to enhance understanding of the figures and is in no way intended to limit the scope of the invention. The components and elements depicted, as well as their design and use, may vary according to the considerations of a person skilled in the art and may be adapted to specific applications.

[0065] Figure 1 shows an image recording device 100 for determining at least one position of an object in space, in particular an orbital object in near-Earth space, using a method according to an embodiment of the invention.

[0066] The image recording device 100 comprises at least one camera system 10, a time synchronization unit 30, and a processing unit 40. Incident light 11 is imaged by an optical imaging device 12, in particular a telescope, onto a detector 14 of the camera system 10. The detector 14 is designed as a two-dimensional area sensor with pixels 20 arranged in rows 16 and columns 18 for spatially resolved recording of image data. A digital image 22 is displayed in the enlarged area. The pixels 20 are addressable from 0 to y in rows 16 and from 0 to x in columns 18, so that the pixel coordinates range from 0,0 to x,y.

[0067] The exposure time of the camera system 10 can be set, for example, by a mechanical shutter or an electronic, in particular digital, shutter.

[0068] Digital image data 44 are sent from the camera system 10 to the computing unit 40, which may be part of a data processing system 1000. The image data 44 are also sent to the time synchronization unit 30, which receives a time signal 46 from a GPS receiver 32. Time synchronization data 48 are also sent from the time synchronization unit 30 to the computing unit 30. A data processing system 1000 can advantageously be used to execute a data processing program comprising computer-readable program instructions for carrying out the method for determining at least one position of an object in space, in particular in near-Earth space.

[0069] The camera system 10 can capture at least one image 22 with a predetermined exposure time. The time synchronization unit 30 can assign a start time 50 and an end time 60 to the image 22 and thus to the object depicted therein.

[0070] Position data of the object can be determined from the image 22. According to the proposed method, the computing unit 40 can determine a corrected start time 54 from the start time 50 with a predetermined switch-on delay 52 of the camera system 10, depending on the position data of the object, and a corrected end time 64 can be determined from the end time 60 with a predetermined switch-off delay 62 of the camera system 10. The predetermined switch-on delay 52 and switch-off delay can be dependent on the position of a pixel 20 on the detector 14 of the camera system 10. The corrected start time 54 and the corrected end time 64 can be assigned to the position data of the object.

[0071] Figure 2 shows a calibration setup 200 for determining a switch-on delay 52 and / or a switch-off delay 62 according to an embodiment of the invention. To determine the position-dependent switch-on delay 52 and / or switch-off delay 62, the camera system 10 with the imaging device 12 is arranged in a darkened room 82. The camera system 10 receives light 11 from an imaging screen 84, which is sharply imaged onto the detector 14. The imaging screen 84 can be illuminated with a light source 34. The imaging screen 84 can be seen in section in the upper part of the schematic representation and is shown again from the front, marked with an arrow.

[0072] The switch-on delay 52 and / or the switch-off delay 62 of the camera system 10 can be determined, depending on a position of a pixel 20 on the detector 14, during the calibration measurement by time-delayed switching of the light source 34 when recording an image 22 by the camera system 10.

[0073] For this purpose, the switch-on delay 52 can be determined as a time delay when the camera system 10 starts recording the image 22 relative to a first trigger signal 56 and the switch-off delay 62 can be determined as a time delay when the camera system 10 stops recording the image 22 relative to a second trigger signal 66.

[0074] To determine the switch-on delay 52, a first trigger signal 56 is first sent to a delay generator 36 when the camera system 10 starts recording the image 22. This delay generator 36 sends a time-delayed signal 38 to the light source 34. The time-delayed signal 38 turns off the light source 34, which has illuminated the imaging screen 84 until then. A transition between a bright area 28 and a dark area 29 on the image 22 is then determined. The switch-on delay 52 can then be determined as the time delay of the time-delayed signal 38, which corresponds to the transition between the bright area 28 and the dark area 29. To determine the switch-off delay 62, a second trigger signal 66 is first sent to the delay generator 36 when the camera system 10 stops recording the image 22. This sends the time-delayed signal 38 to the light source 34.The time-delayed signal 38 turns on the light source 34, which was previously off. Subsequently, a transition between the dark area 29 and the bright area 28 in the image 22 is determined. The turn-off delay 62 can then be determined as the time delay of the time-delayed signal 38, which corresponds to the transition between the dark area 29 and the bright area 28.

[0075] The switch-on delay 52 and / or the switch-off delay 62 can advantageously be determined with this method depending on a position of a pixel 20 of the optical detector 14 of the camera system 10.

[0076] By repetition and statistical averaging for many measurements, a table can then be created which contains a specific delay time as switch-on delay 52 and / or switch-off delay 62 for each pixel position of the detector 14.

[0077] The following tables show measured delay times for the start and end of exposure compared to the first and second trigger signals 56, 66 emitted by the camera system 10. Table 1: Delay time when switching on in microseconds for a number of y rows and x columns:

[0078] Table 2: Delay time when switching off in microseconds with a number of y rows and x columns:

[0079] Figure 3 shows an image 22 of an object in space taken with the image recording device 100 according to Figure 1. The image shows an object which, due to the relatively long exposure time, is represented as a streak trace 70 in the image 22. The start time 50 is assigned to the beginning 72 of the streak trace 70, and the end time 60 is assigned to the end 74. Furthermore, stars can be seen in the image 22 as dark points, from which selected reference stars 80 can be used to determine the angular coordinates of the object. Advantageously, the position data of the object can thus be determined as angular coordinates via an astrometric calibration based on stars and / or constellations captured in the image 22. The exposure time of the image 22 is selected such that the object is depicted as a streak trace 70 in the image 22.The corrected start time 54 can then be assigned to a start 72 of the line trace 70 and the corrected end time 64 can be assigned to an end 74 of the line trace 70.

[0080] The image 22 of the object was recorded with an exposure time that is long enough that the object is imaged as a streak 70 and short enough that stars are imaged as points. Using this method of recording with a relatively long exposure time, the corrected start time 54 of the object's start position 72 can be determined as the sum of the start time 50 and the position-dependent turn-on delay 52, and the corrected end time 64 of the object's end position 74 can be determined as the sum of the end time 60 and the position-dependent turn-off delay 62. Advantageously, the turn-on delay 52 and the turn-off delay 62 can be determined as a function of the object's start position 72 in the image 22 and the end position 74 of the streak 70 on the detector 14 to determine the corrected start time 54 and the corrected end time 64, as shown in the two tables 1 and 2 shown above.

[0081] Alternatively, an image 22 of the object can be taken with an exposure time that is short enough that the object is imaged as a point.

[0082] Another possibility for detecting orbital objects in space is to capture and process images with a relatively short exposure time. Instead of capturing images with relatively long exposure times, at least one image is captured with an exposure time short enough for the object to be imaged as a point. In these images, an object in near-Earth space can then appear as a point or a shorter line trail, depending on the exposure time. However, the point or the shorter line trail may possibly be faint. In order to be able to evaluate such images 22 as well, according to a further embodiment, a series of images 22, 23, 24, 25 of an object can be captured.

[0083] Figure 4 illustrates a method for generating a composite image 26 from a series of recorded images 22, 23, 24, 25 of an object according to a further exemplary embodiment of the invention. Figure 5 shows a superimposition of three images 22, 23, 24 to generate a composite image 26, while Figure 6 illustrates an evaluation of a series of images 22, 23, 24, 25 by superimposing them to form a composite image 26.

[0084] In this case, a series of images 22, 23, 24, 25 of the object is taken with a relatively short exposure time with a time shift 58 between the recording of the images 22, 23, 24, 25, as shown, for example, in step S2 in Figure 6.

[0085] The images 22, 23, 24, 25 shown in Figure 4 are shifted relative to each other in at least one direction using the so-called synthetic tracking method, indicated by the coordinates v=(-1,-1) to v=(1,1) noted in the individual stacks of images 22, 23, 24, 25, and superimposed to form a composite image 26. A corrected start time 54 and a corrected end time 64 can be determined from the composite image 26.

[0086] Images 22, 23, 24, 25 can be shifted relative to each other in at least one direction and superimposed to form at least one composite image 26. In particular, images 22, 23, 24, 25 can be superimposed to form a composite image with maximum intensity. Images 22, 23, 24, 25 can be shifted and superimposed until a point or line trace with maximum intensity is recognizable. The starting position 72 and the end position 74 of the object can be determined from the composite image.

[0087] Figure 5 shows three images 22, 23, and 24, each containing an object depicted as a point 76. By shifting the images 22, 23, and 24 relative to each other, the images 22, 23, and 24 can be positioned such that the object points 76 are superimposed and can thus be seen more clearly.

[0088] In Figure 6, in step S1, an image 22 of the object taken with a relatively long exposure time is shown for comparison, in which the object is depicted as a line trace 70 as in Figure 3.

[0089] However, this line track 70 may be too weak for small objects and therefore not visible. To increase the sensitivity, several images are taken, as shown in step S2.

[0090] 22, 23, 24, 25 were taken with a shorter exposure time. These images 22,

[0091] 23, 24, 25 still have such a long exposure time that the object moves slightly, creating very short, faintly visible streak trails 70. Each of these shorter streak trails can theoretically be assigned a start time 50 and end time 60. However, these values ​​are practically inaccessible because streak trail 70 is not bright enough. Each of the individual images 22, 23, 24, 25 is shifted by a time shift 58 because images 22, 23, 24, 25 are taken one after the other. In step S2, such a series of images 22, 23, 24, 25 is shown with a time shift 58 between images 22, 23, 24, 25.

[0092] The individual images 22, 23, 24, 25 can now be shifted in a suitable manner in different directions and with different pixel offsets and superimposed to form a composite image 26. The goal is for the object signals in images 22, 23, 24, 25 to be summed to a point or, as shown, to a short line trace. The composite image 26 is recognizable in step S3 with a clear, short line trace 70 of the object. The superimposition creates a bright point or a bright line trace that stands out from the background and for which the pixel positions of the start position and end position can be precisely determined.

[0093] Images 22, 23, 24, 25 can now be shifted in the path direction of the object according to the superposition of the combined image 26, taking into account the time shift 58. In this case, an image 27 can be generated with a virtual longer exposure time, in which the object is again represented as a longer line trace 70, corresponding to image 22 in step S1. Such a virtual image 27 is represented in step S4.

[0094] The corrected start time 54 of the object's initial position 72 corresponds to the corrected start time 54 of the first image 22 of the series of images 22, 23, 24, 25, and the corrected end time 64 of the object's final position 74 corresponds to the corrected end time 64 of the last image 25 of the series of images 22, 23, 24, 25. The determined position of the object can be saved together with the corrected start time 54 and the corrected end time 64. In particular, the position of the object can be saved together with the corrected start time 54 and the corrected end time 64 as course tracking data, in particular in a web-based database 42. It is also possible to save the object's position data together with weather data.

[0095] Figure 7 shows a flowchart of the method for determining at least one position of an object in space, in particular an orbital object in near-Earth space, according to an embodiment of the invention.

[0096] Image 22 is captured by camera system 10 in an image acquisition process S100 and time-stamped using the time synchronization unit 30 and the GPS receiver 32. Image 22 is subsequently saved, for example, in the so-called Flexible Image Transport System (FITS) format. This image 22 is then loaded by image processing software S106 via an image processing process S102. This software recognizes the star trails of the objects and the stars. Image processing software S106 also starts an astrometry program S108, which determines the coordinates of the detected objects. The stars depicted in image 22 are detected and compared with a star catalog to convert the image coordinates into equatorial coordinates.

[0097] The astrometry program S108 receives the image data via the astrometry process S104. The determined result is then time-corrected in step S110 and subsequently stored in a Tracking Data Message (TDM) file 94. All other blocks serve to control the system. An acquisition program S120, which incorporates general settings 96, controls the process flow and also a housing 98 of the image acquisition device 100.

[0098] A storage program S122 controls the storage of the data in the web database 42.

[0099] Weather data can also be saved. For this purpose, data from a weather station 90 is saved in a weather data file 92 via an environmental data program S130 and can also be stored in the web database 42.

[0100] Advantageously, the method can be implemented in a computer program product for determining at least one position of an object in space, in particular an orbital object in near-Earth space. The computer program product comprises at least one computer-readable storage medium containing program instructions that are executable on a computer system and cause the computer system to execute the method.

[0101] Reference symbol

[0102] 10 Camera system

[0103] 11 incident light

[0104] 12 Imaging device

[0105] 14 Detector

[0106] 16 lines

[0107] 18 columns

[0108] 20 pixels

[0109] 22 Image

[0110] 23 Image

[0111] 24 images

[0112] 25 images

[0113] 26 Summary image

[0114] 27 virtual image

[0115] 28 bright area

[0116] 29 dark area

[0117] 30 Time synchronization unit

[0118] 32 GPS receivers

[0119] 34 Light source

[0120] 36 Delay generator

[0121] 38 time-delayed signal

[0122] 40 computing units

[0123] 42 Database

[0124] 44 image data

[0125] 46 Time signal

[0126] 48 time synchronization data

[0127] 50 Initial period

[0128] 52 Switch-on delay

[0129] 54 corrected start time

[0130] 56 first trigger signal

[0131] 58 Time difference

[0132] 60 End Times

[0133] 62 Switch-off delay

[0134] 64 corrected end time 6 second trigger signal 0 line trace 2 initial position 4 final position 6 object point 0 reference star 2 darkened room 4 image screen

[0135] 90 weather station

[0136] 92 weather data

[0137] 94 TDM data file

[0138] 96 settings

[0139] 98 enclosure

[0140] 100 image recording device

[0141] 200 Calibration setup

[0142] 1000 data processing system, computer system

[0143] S100 image capture

[0144] S102 Image processing process

[0145] S104 Astrometric process

[0146] S106 image processing program

[0147] S108 Astrometrics program

[0148] S110 Time correction

[0149] S120 recording program

[0150] S122 storage program

[0151] S130 Environmental Data Program

Claims

Claims 1. A method for determining at least one position of an object in space, in particular an orbital object in near-Earth space, in which an image recording device (100) is used, comprising at least one camera system (10), a time synchronization unit (30), a computing unit (40), wherein at least one image (22, 23, 24, 25) of the object is recorded with a predetermined exposure time using the camera system (10), wherein a start time (50) and an end time (60) are assigned to the image (22, 23, 24, 25) using the time synchronization unit (30), wherein a start position (72) and an end position (74) of the object are determined on the image (22, 23, 24, 25),wherein the computing unit (40) determines a corrected start time (54) from the start time (50) with at least one predetermined switch-on delay (52) of the camera system (10) and a corrected end time (64) from the end time (60) with at least one predetermined switch-off delay (62) of the camera system (10), wherein the corrected start time (54) is assigned to the start position (72) of the object and the corrected end time (64) is assigned to the end position (74) of the object.

2. Method according to claim 1, wherein, to determine the corrected start time (50), a switch-on delay dependent on the start position (72) is selected from the at least one predetermined switch-on delay (52) depending on the start position (72), and to determine the corrected end time (60), a switch-off delay dependent on the end position (74) is selected from the at least one predetermined switch-off delay (62) depending on the end position (74).

3. Method according to claim 1 or 2, wherein the camera system (10) has at least one optical imaging device (12), in particular a telescope, and an optical detector (14) which is designed as a two-dimensional area detector with pixels (20) arranged in rows (16) and columns (18) for the spatially resolved recording of image data.

4. Method according to one of the preceding claims, wherein the at least one image (22, 23, 24, 25) of the object is recorded with an exposure time which is long enough that the object is imaged as a line trace (70) and short enough that stars are imaged as points, wherein the initial position (72) of the object corresponds to a start of the line trace (70) and the final position (73) of the object corresponds to an end of the line trace (70).

5. Method according to one of claims 1 to 3, wherein at least one image (22, 23, 24, 25) of the object is taken with an exposure time which is short enough that both the object and stars are imaged as points.

6. The method according to claim 5, wherein a series of images (22, 23, 24, 25) of the object is recorded with a time shift (58) between the images (22, 23, 24, 25), wherein the images (22, 23, 24, 25) are shifted relative to one another in at least one direction and superimposed to form at least one summed image (26), in particular superimposed to form a summed image (26) with maximum intensity, wherein the starting position (72) and end position (74) of the object are determined from the at least one summed image (26).

7. The method according to claim 6, wherein the corrected start time (54) of the first image (22) of the series of images (22, 23, 24, 25) is selected as the corrected start time (54) of the initial position (72) of the object in the summation image (26), and the corrected end time (64) of the last image (25) of the series of images (22, 23, 24, 25) is selected as the corrected end time (64) of the final position (72) of the object in the summation image (26).

8. Method according to one of claims 3 to 7, wherein the optical imaging device (12) is defocused, in particular slightly, so that the object exposes several pixels (20) of the optical detector (14).

9. Method according to one of the preceding claims, wherein the at least one switch-on delay (52) and / or the at least one switch-off delay (62) of the camera system (10) are determined during a calibration measurement by time-delayed switching of a light source (34) when recording an image (22, 23, 24, 25) by the camera system (10).

10. The method according to claim 9, comprising at least the steps - sending a first trigger signal (56) to a delay generator (36) when the camera system (10) starts recording the image (22, 23, 24, 25); - sending a time-delayed signal (38) with a time delay to the light source (34); - switching off the light source (34) due to the time-delayed signal (38); - determining a transition area between a bright area (28) and a dark area (29) of the image (22, 23, 24, 25); - Assigning the time delay of the time-delayed signal (38) as a switch-on delay (52) to the areas of the image (22, 23, 24, 25) which lie in or around the transition area between the light area (28) and the dark area (29); wherein the steps are repeated with an increased or decreased time delay of the time-delayed signal (38) until all areas of the image (22, 23, 24, 25) are assigned a switch-on delay (52), and / or - sending a second trigger signal (66) to the delay generator (36) when the camera system (10) stops recording the image (22, 23, 24, 25); - sending the time-delayed signal (38) to the light source (34); - switching on the light source (34) based on the time-delayed signal (38); - determining a transition area between the dark area (29) and the light area (28) of the image (22, 23, 24, 25); - Assigning the time delay of the time-delayed signal (38) as a switch-off delay (54) to the areas of the image (22, 23, 24, 25) which lie in or around the transition area between the dark area (29) and the light area (28), wherein the steps with increased or reduced time delay of the time-delayed signal (38) are repeated until all areas of the image (22, 23, 24, 25) are assigned a switch-off delay (54).

11. The method according to claim 10, wherein the at least one switch-on delay (52) and / or the at least one switch-off delay (62) are assigned to the pixels (20) of the optical detector (14) of the camera system (10) which are located in the transition region between the bright region (28) and the dark region (29) of the image (22, 23, 24, 25) or which are immediately adjacent.

12. Method according to one of the preceding claims, wherein the position of the object is determined as angular coordinates via an astrometric calibration based on stars and / or constellations detected in the image (22, 23, 24, 25).

13. Method according to one of the preceding claims, wherein the position of the object is stored together with the corrected start time (54) and the corrected end time (64), in particular wherein the position of the object is stored together with the corrected start time (54) and the corrected end time (64) as data for course tracking, in particular in a web-based database (42).

14. A computer program product for determining at least one position of an object in space, in particular an orbital object in near-Earth space, in which an image recording device (100) is used, comprising at least one camera system (10), a time synchronization unit (30), a computing unit (40), wherein at least one image (22, 23, 24, 25) of the object is recorded with a predetermined exposure time using the camera system (10), wherein a start time (50) and an end time (60) are assigned to the image (22, 23, 24, 25) using the time synchronization unit (30), wherein a start position (72) and an end position (74) of the object are determined on the image (22, 23, 24, 25), wherein the computer program product comprises at least one computer-readable storage medium which comprises program instructions that can be executed on a computer system (1000) and cause the computer system (1000) to execute a method,in particular according to at least one of the preceding claims, wherein the computing unit (40) determines a corrected start time (54) from the start time (50) with at least one predetermined switch-on delay (52) of the camera system (10) and a corrected end time (64) from the end time (60) with at least one predetermined switch-off delay (62) of the camera system (10), wherein the corrected start time (54) is assigned to the start position (72) of the object and the corrected end time (64) is assigned to the end position (74) of the object.

15. Data processing system (1000) for executing a data processing program comprising computer-readable program instructions to carry out a method for determining at least one position of an object in space, in particular in near-Earth space, according to one of claims 1 to 13.

Images