EP3283898A1 - Method for readjusting a parallactic or azimuthal mounting - Google Patents
Method for readjusting a parallactic or azimuthal mountingInfo
- Publication number
- EP3283898A1 EP3283898A1 EP16716002.7A EP16716002A EP3283898A1 EP 3283898 A1 EP3283898 A1 EP 3283898A1 EP 16716002 A EP16716002 A EP 16716002A EP 3283898 A1 EP3283898 A1 EP 3283898A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- image
- control
- offset
- time difference
- main
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
Classifications
-
- 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
- G01S3/7867—Star trackers
-
- 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
-
- 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
- G01S3/7864—T.V. type tracking systems
-
- 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
- G01S3/7864—T.V. type tracking systems
- G01S3/7865—T.V. type tracking systems using correlation of the live video image with a stored image
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16M—FRAMES, CASINGS OR BEDS OF ENGINES, MACHINES OR APPARATUS, NOT SPECIFIC TO ENGINES, MACHINES OR APPARATUS PROVIDED FOR ELSEWHERE; STANDS; SUPPORTS
- F16M11/00—Stands or trestles as supports for apparatus or articles placed thereon Stands for scientific apparatus such as gravitational force meters
- F16M11/02—Heads
- F16M11/18—Heads with mechanism for moving the apparatus relatively to the stand
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/16—Housings; Caps; Mountings; Supports, e.g. with counterweight
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/16—Housings; Caps; Mountings; Supports, e.g. with counterweight
- G02B23/165—Equatorial mounts
Definitions
- the present invention relates to a method for tracking a parallactic or azimuthal mount, comprising an alignable by means of at least one image sensor and an electromotive controller and trackable device for positioning and movement of a telescope with a camera.
- Parallactic mounts are pivotable for this purpose in the right ascension axis and the declination axis.
- the polar axis must be aligned parallel to the earth's axis in order to counteract the earth's rotation at a constant speed (sidereal) in the driven right ascension axis. Since this setup is very error-intensive, both axes are increasingly equipped with motors and driven to compensate for the error of misalignment.
- astrophotography telescopes with larger focal lengths (> 300mm) are used and larger (> 5min) exposure times chosen to create recordings.
- autoguiders have increasingly been used to measure the movement of the axes, these systems needing a second image sensor which observes a guide star and determines its position If a deviation from the target position occurs, a correction is made for the movement
- Autoguiders exist in various designs, either as an additional image sensor in special cameras, with their own optics mounted on the telescope or in the beam path of the main optics
- the disadvantage of the autoguider is that the complexity of the entire system increases and the operability is hampered, because, inter alia, a control system, depending on optics and mounting, must be parameterized through the second camera and given if by a second Tauschutz for the guide tube.
- Another known method is the creation of a pointing model. With the help of the assembled optics and camera the position of celestial objects is determined exactly. After measuring the position of several objects, a model is calculated with which such a mount can be exactly positioned and tracked.
- the disadvantage of this method is that the models lose their validity when the mount changes position. For this, the smallest changes in position or orientation between the mount and the celestial object are sufficient. Such changes can occur on the tripod, on the telescope and on the camera. This is the case, in particular, in mobile operation (eg due to sinking of the stand or due to thermal expansion in the mount).
- a pointing model for the mount is created. This happens before the actual creation of the main shots.
- the main sensor does not function as a tracking control sensor, but as a sensor for the one-time creation of the pointing model.
- the US 2013/0 265 639 AI also describes the calibration of rotation with the help of astronomical methods, so that cheaper rotary encoders can be used.
- the actual tracking takes place via a previously determined pointing model and does not use the main sensor for follow-up control.
- US 2014/0 085 717 A1 also describes a system which integrates a tracking control camera and optics in the mount.
- a further imaging sensor and optics are provided, with which an exact measurement of the position in the sky is possible.
- For the actual main recording an additional camera and optics is necessary, with the sensors and optics used no main recording is created.
- the present invention has for its object to provide a method that is capable of eliminating the complexity of the operation and the system structure in the use of autoguiders and the error rate of systems based on pointing models.
- a method of the type mentioned above is characterized in that the image sensor acts as a main image sensor of the camera and equally as an alignment sensor and NachInstitutkontrollsensor, wherein before and after a main recording at least one control recording performed with shorter exposure time and these control recordings are compared with each other, or at least one main image itself acts as a control image and is compared with at least one previous main image, or a short-exposure control image is compared with the main image itself and the correction values for the tracking of the mount are determined by the image offset and the time difference of the images taken.
- the orientation of the camera is calibrated in right ascension and declination to determine the image offset in the axes.
- the method is characterized in that a correction value for the movement of the axes is determined and the error in the tracking is measured regularly with the following steps:
- the image offset of the images is determined by image processing subpixelgenau.
- the temporal angle change caused by the misplacement of the mount is determined.
- the setup error is calculated and transformed this back to the time-lagging image offset for the next main exposure.
- a function of the error curve Ra (t) and Dek (t) is calculated and passed to the controller in order to operate the axes with a calculated angular velocity, whereby the differential refraction (deltaRaRefract and deltaDecRefract) is also taken into account.
- Ra (t) Vsiderian * ⁇
- VRaKorr (HVRa - deltaRaRefract) / dt + Vsiderisch,
- VDekKorr (HVDek - deltaDecRefrakt) / dt
- Ra (t) VRaCorr * t
- Dek (t) VDekKorr * t IV. Determination of the new angular velocity on the basis of the time difference and the offset taking into account the differential refraction
- VRa orr (HVRa - deltaRaRefract) / dt + VRa orr
- VDek orr (HVDek - deltaDecRefract) / dt + VDek orr
- an imaging sensor detects a correction for the tracking to eliminate the tracking error controlled in both axes and to respond to changes in position or orientation between the mount and celestial object because the correction calculation is performed at a time interval of the main shots , As a result, longer exposure times without image errors possible.
- the system consists of an equatorial mount with high resolution encoders and stepper motors on both axes.
- the motor control of the system allows the evaluation of the encoders, control of the motors and precise control of the axes.
- a digital SLR camera with live view mode is used in this case.
- the evaluation is carried out on an additional computer (laptop) with the help of software.
- the software includes built-in functions such as complete control of the DSLR, two-star method for calculating the misalignment due to the position of two stars, calculation and transfer of the correction values to the controller and image processing algorithms for offset determination.
- the mount is leveled using a spirit level and aligned by compass and pitch circle parallel to the earth's axis.
- the geographic coordinates of the location are entered into the software for calculation.
- the simplified design of the alignment and operation by the use of inclination (leveling) and directional sensors (elevation) and a GPS sensor for automatic determination of the location.
- the leveling can be dispensed with by determining the differential angle of the azimuthal coordinate systems of the mount and the earth and taking this into account in the correction.
- the automatic camera calibration feature detects the alignment of the camera with the optics by causing the controller to first sweep a monitored star with the right ascension axis to one edge of the image, store the image coordinates, and then move to the other edge of the image to calculate the camera's orientation angle ,
- the controller executes the two-star method to minimize the setup error.
- the known star is automatically moved to the center of the image, the axis positions are calibrated by the rotary encoders and swiveled to another known star in order to compare the deviation of the axis position to the star position.
- the software calculates the misplacement of the mount and visually displays to the user the correction values in azimuth and elevation that can be corrected in the live image on a star. After the correction has been completed, the camera orientation will be automatically checked again and adjusted if necessary. After that The user can drive to a desired object, set the exposure times and number of shots, and start the capture cycle.
- the Soffware automatically takes before and after each main recording short onfroll goods, which are then compared.
- An image processing algorithm eg FOCAS Automatic Catalog Mapping Algorithm
- the exposure time and ISO value of the control images are automatically adjusted by the algorithm ejecting the control image and looking for enough details. If not enough or no details are visible, the exposure time and / or the ISO throw of the control images is automatically increased.
- a local error model is created at the desired location in order to obtain the correct desired position as a function of the time for the declinafion and recta ascension axes.
- the effect of the refraction is well known and can therefore be corrected in the S mecanicungssoffware.
- the atmospheric refraction depends on the luff pressure, temperafur and height of the objecf. However, since only differential refraction is necessary in this method, the height of the object is mainly relevant.
- the local error model calculates the Aufsfaueautechnik and transforms them back to the temporally ongoing Syndromeversafz for the next main exposure.
- a polynomial of the error curve is calculated and passed to the controller to operate the axes with a dynamic tracking speed. This procedure is repeated for further main shots, with the tracking speeds of the axes being recalculated and adjusted each time.
- the mount is first set up and the polar axis is aligned as accurately as possible.
- the alignment can be done using a polar finder or compass and angle scale. The more accurate the setup, the smaller the image field rotation, depending on the length of the exposure, position in the sky and the size of the image field. The horizon can be completely omitted, as this has no effect on the tracking.
- the orientation of the camera is set.
- a star is brought into the image field and the camera oriented so that the star during a movement of the right ascension axis is horizontal.
- the position of the object to be exposed is controlled, activated the control for the right ascension and started with a short exposure control recording. It immediately follows a long main shot, which in turn is completed with a short control shot.
- the image offset is now determined by a suitable image processing algorithm. The most common method is triangulation. The algorithm searches for as many largest triangles as possible that connect the stars and calculates the offset and rotation between the reference and control images.
- Another possibility for determining the offset is an algorithm that works with two-dimensional cross-correlation in the image plane.
- the signal of the first reference image is compared with the signal of the second control image and the maximum searched.
- the calculated offset from pixel to angle is converted.
- the value depends on the focal length of the optics and the pixel size of the camera.
- a temporal angular velocity can be calculated based on the target and actual position.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102015101781.4A DE102015101781B4 (en) | 2015-02-09 | 2015-02-09 | Method for tracking a parallactic mount |
PCT/DE2016/100044 WO2016127977A1 (en) | 2015-02-09 | 2016-02-01 | Method for readjusting a parallactic or azimuthal mounting |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3283898A1 true EP3283898A1 (en) | 2018-02-21 |
Family
ID=55750277
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP16716002.7A Withdrawn EP3283898A1 (en) | 2015-02-09 | 2016-02-01 | Method for readjusting a parallactic or azimuthal mounting |
Country Status (7)
Country | Link |
---|---|
US (1) | US10698069B2 (en) |
EP (1) | EP3283898A1 (en) |
JP (1) | JP2018510390A (en) |
CA (1) | CA2976010A1 (en) |
DE (2) | DE102015101781B4 (en) |
GB (1) | GB2556389A (en) |
WO (1) | WO2016127977A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2018055619A1 (en) * | 2016-09-25 | 2018-03-29 | Israel Aerospace Industries Ltd. | Celestial compass and method of calibrating |
US11847157B2 (en) * | 2018-09-13 | 2023-12-19 | Jiazhi Chen | Telescope star searching method and device based on image recognition and telescope |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5365269A (en) | 1992-10-22 | 1994-11-15 | Santa Barbara Instrument Group, Inc. | Electronic camera with automatic image tracking and multi-frame registration and accumulation |
AU759445B2 (en) * | 1998-09-25 | 2003-04-17 | Unisearch Limited | CCD readout method |
GB2344951B (en) * | 1998-12-17 | 2003-07-30 | Starlight Xpress Ltd | Method and apparatus for tracking a selected distant object |
US7339731B2 (en) * | 2005-04-20 | 2008-03-04 | Meade Instruments Corporation | Self-aligning telescope |
US8278702B2 (en) | 2008-09-16 | 2012-10-02 | Fairchild Semiconductor Corporation | High density trench field effect transistor |
JP5779968B2 (en) * | 2010-05-19 | 2015-09-16 | リコーイメージング株式会社 | Astronomical tracking method and camera |
GB2485596A (en) * | 2010-11-20 | 2012-05-23 | Astrotrac Ltd | Self-guiding equatorial or altitude/azimuth telescope mount |
DE102012003796A1 (en) | 2011-03-18 | 2012-09-20 | Merck Patent Gmbh | Liquid crystalline medium |
US20130265639A1 (en) * | 2012-04-09 | 2013-10-10 | Andrey Borissov Batchvarov | Accurate Telescope Tracking System with a Calibrated Rotary Encoder |
US20140085717A1 (en) * | 2012-09-21 | 2014-03-27 | Kenneth W. Baun | Systems and methods for closed-loop telescope control |
-
2015
- 2015-02-09 DE DE102015101781.4A patent/DE102015101781B4/en active Active
-
2016
- 2016-02-01 CA CA2976010A patent/CA2976010A1/en not_active Abandoned
- 2016-02-01 DE DE112016000658.6T patent/DE112016000658A5/en not_active Withdrawn
- 2016-02-01 WO PCT/DE2016/100044 patent/WO2016127977A1/en active Application Filing
- 2016-02-01 EP EP16716002.7A patent/EP3283898A1/en not_active Withdrawn
- 2016-02-01 JP JP2017559757A patent/JP2018510390A/en active Pending
- 2016-02-01 GB GB1714370.2A patent/GB2556389A/en not_active Withdrawn
- 2016-02-01 US US15/549,149 patent/US10698069B2/en active Active
Also Published As
Publication number | Publication date |
---|---|
JP2018510390A (en) | 2018-04-12 |
GB2556389A (en) | 2018-05-30 |
CA2976010A1 (en) | 2016-08-18 |
GB201714370D0 (en) | 2017-10-25 |
US20180172796A1 (en) | 2018-06-21 |
WO2016127977A1 (en) | 2016-08-18 |
US10698069B2 (en) | 2020-06-30 |
DE102015101781B4 (en) | 2017-11-09 |
DE112016000658A5 (en) | 2017-10-19 |
DE102015101781A1 (en) | 2016-08-11 |
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