CN117498964A - Method for capturing and tracking space laser communication by using star detection device - Google Patents
Method for capturing and tracking space laser communication by using star detection device Download PDFInfo
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Abstract
The invention discloses a method for capturing and tracking space laser communication by using a star detection device, belonging to the technical field of information transmission and processing. The invention uses the design of the common optical axis of the star detection device optical axis and the laser communication rough tracking optical axis, simplifies the process of star calibration, uses the star sensor to complete the pointing control and rough tracking closed loop in the scanning capturing stage, can provide more accurate pointing of the laser communication optical axis, partially inhibits the optical axis shake caused by the vibration of the spacecraft platform, and realizes the purpose of greatly reducing the capture uncertainty area, thereby shortening the capture time. The invention can be applied to laser communication platforms with various architectures, has the advantages of simple structure, low cost, good producibility and high capturing speed, and is an important improvement on the prior art.
Description
Technical Field
The invention relates to the technical field of information transmission and processing, in particular to a method for capturing and tracking space laser communication by using a star detection device in a space laser communication system.
Background
In a space orbit motion spacecraft platform or satellite platform, due to the stress deformation and the change of a working environment during emission, the error of an optical axis of a laser communication terminal obtained by platform posture information output by a platform posture sensor is more than ten milliradians, so that an uncertain capture area in the magnitude of thirty milliradians is caused. When the laser communication terminal performs initial capturing of the beaconing light, the beam divergence angle of the communication laser is only tens of micro radians, the capturing time required for capturing an uncertain region with thirty milliradians is too long, and the capturing process is too complex. The current solution is to add an independent star sensor for the laser communication system and perform optical axis calibration, and the pointing error of the laser communication optical axis can be reduced to a few milliradians after the calibration is provided, but the current measure cannot restrain the optical axis pointing error caused by platform vibration, and in addition, the defects of complex design and debugging, long capturing time, high cost, large volume weight and the like are brought.
Disclosure of Invention
In view of the above, the invention provides a method for performing space laser communication capturing and tracking by using a star detection device, wherein the method designs an optical axis of the star detection device and an optical axis of laser communication rough tracking to be coaxial, thereby simplifying the process of pointing and calibrating the optical axis; in the initial stage of communication link establishment, the star detection device is used for accurately tracking the initial direction of an optical axis, and during scanning and capturing, the star detection device can output off-target quantity based on the star position to realize coarse tracking, can inhibit a low-frequency part of optical axis shake caused by platform vibration, and can greatly reduce the capture uncertainty area, thereby simplifying the scanning and capturing process and shortening the scanning and capturing time.
In order to achieve the above purpose, the technical scheme provided by the invention is as follows:
a method for capturing and tracking space laser communication by using a star detection device is realized based on the star detection device and a space laser communication terminal, wherein the space laser communication terminal comprises a spectroscope, a communication terminal rear light path and communication processor, a capturing and tracking controller, a coarse tracking mechanism and a fine tracking mechanism, and comprises the following processes:
(1) The optical axis of the star detection device and the rough tracking optical axis of the space laser communication terminal are arranged by adopting a common optical axis, and the rough tracking mechanism drives the optical axis of the star detection device and the rough tracking optical axis of the space laser communication terminal to synchronously rotate;
(2) The space light enters the spectroscope through the rough tracking optical axis, and the spectroscope separates the light beams according to the light wavelength: the energy of the laser communication wavelength received by the space enters the communication terminal after being totally reflected by the spectroscope, and then enters the optical path and the communication processor, and the light energy of other wavelengths which do not contain the laser communication wavelength received by the space enters the star detection device through the spectroscope; meanwhile, the laser energy of the light path behind the communication terminal and the emission wavelength output by the communication processor enters a space through a coarse tracking optical axis after being totally reflected by a spectroscope;
(3) The star detection device calculates the visual axis pointing angle and the attitude information of the star detection device according to the received light energy, and sends the calculation result to a capture tracking controller of the space laser communication terminal; meanwhile, the rear light path of the communication terminal and the communication processor process the received laser to form spot position information of the laser, and the spot position information of the laser is sent to the capture tracking controller through the fine tracking mechanism;
(4) The capture tracking controller controls the coarse tracking mechanism and the fine tracking mechanism according to the current working state, information input by the star detection device and spot position information of laser, and completes scanning capture and tracking control of laser communication.
Further, the star detection device used is a photoelectric system capable of calculating the visual axis pointing angle and the light spot position by utilizing star detection, including but not limited to a star sensor.
Furthermore, the optical axis of the star detecting device in the step (1) and the rough tracking optical axis of the space laser communication terminal adopt a common optical axis installation mode, and the optical axes of the star detecting device and the rough tracking optical axis are parallel or on the same optical axis.
Further, the calculation result of the star detecting device in the step (3) further includes spot position information of a certain star in the detection field.
Further, when calculating the spot position information of a certain fixed star in the detection view field, any single fixed star in the detection view field is selected by fixed star, and the selection modes include, but are not limited to, the relative position and the relative brightness of the fixed star.
Further, the controlling the coarse tracking mechanism in the step (4) specifically includes:
in the initial pointing stage or the star calibration stage, the visual axis pointing angle and posture information output by the star detection device are used for driving the coarse tracking mechanism to accurately point the optical axis to a preset target direction;
in the scanning and capturing stage, the spot position information of a certain fixed star output by the fixed star detection device is used as the off-target quantity to perform the closed-loop control of the coarse tracking mechanism;
in the stable tracking stage, the spot position information of laser or the spot position information of a certain fixed star output by the fixed star detection device is used for carrying out closed-loop control of the coarse tracking mechanism.
From the above description, the beneficial effects of the invention are as follows:
1. the invention carries out the coaxial design of the optical axis of the star detecting device and the rough tracking optical axis of the laser communication, realizes the coaxial direction of the optical axis of the star detecting device and the rough tracking optical axis of the laser communication, and greatly simplifies the star calibration process because the pointing direction of the star detecting device is the pointing direction of the tracking optical axis.
2. The invention can design the star detecting device and the laser communication coarse tracking on the same optical axis, and the star detecting device and the laser communication coarse tracking can share the shell shielding of the laser communication system, and the star detecting device and the laser communication coarse tracking are designed and modulated simultaneously, so that the research and development cost of the system is reduced, and the reliability of the system is improved.
3. The invention adopts the modified star detection device to provide the off-target quantity to complete the closed loop of the laser communication coarse tracking, can save the design of the image detector of the coarse tracking, and can restrain the optical axis shake caused by the low-frequency part of the platform vibration during the scanning capture of the communication link establishment, thereby greatly reducing the capture uncertainty area and further reducing the scanning capture time. The equipment manufactured by the principle has the advantages of high integration degree, low cost, good producibility, high reliability, advanced performance and the like.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic block diagram of a method for capturing and tracking a spatial laser communication by using a star detection device, wherein the star detection device and a spatial laser communication terminal are on the same optical axis.
Detailed Description
The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.
The method for capturing and tracking space laser communication by using the star detection device is realized based on the star detection device and a space laser communication terminal as shown in fig. 1, wherein the space laser communication terminal comprises a spectroscope, a communication terminal rear light path and communication processor, a capturing and tracking controller, a coarse tracking mechanism and a fine tracking mechanism, and specifically comprises the following steps:
(1) The optical axis of the star detecting device and the rough tracking optical axis of the space laser communication terminal are installed by adopting a common optical axis, and the rough tracking mechanism drives the optical axis of the star detecting device and the rough tracking optical axis of the space laser communication terminal to synchronously rotate.
The star detection device used is any optoelectronic system capable of calculating the visual axis pointing angle and the spot position using star detection, including but not limited to star sensors. The star detecting device is shown in figure 1 and can be regarded as a special star sensor after function expansion and performance upgrading.
The optical axis of the star detecting device and the rough tracking optical axis of the space laser communication terminal adopt a common optical axis installation mode, and the optical axes of the star detecting device and the rough tracking optical axis are parallel or on the same optical axis.
The embodiment adopts the same optical axis of the star detecting device and the space laser communication terminal, and the star detecting device realizes the same optical axis after precise adjustment and correction.
(2) The space light enters the spectroscope through the rough tracking optical axis, and the spectroscope separates the light beams according to the light wavelength: the energy of the laser communication wavelength received by the space enters the communication terminal after being totally reflected by the spectroscope, and then enters the optical path and the communication processor, and the light energy of other wavelengths which do not contain the laser communication wavelength received by the space enters the star detection device through the spectroscope; and meanwhile, the laser energy of the light path behind the communication terminal and the emission wavelength output by the communication processor enters a space through the rough tracking optical axis after being totally reflected by the spectroscope.
The optical energy of the laser communication receiving and transmitting wavelength enters the post-optical path processing, so that the rough tracking optical axis of the laser communication antenna and the optical axis of the star detection device are the same optical axis, and the direction detected by the star detection device is the direction of the rough tracking optical axis, so that special star calibration is not needed.
The light entering the rear light path after passing through the spectroscope only comprises the laser communication light energy of the received wavelength and part of star light energy, the precisely tracked image sensor is insufficient for imaging most stars, and normally, the stars can not interfere with the off-target detection of the precisely tracked image sensor. If stars with high light intensity are imaged on the image sensor for fine tracking, the light spots imaged by the stars can be identified through the rough tracking optical axis pointing direction and the star map.
Light energy of other wavelengths, not including the laser communication wavelength, enters the star detection device. The image sensor of the star detection device can sense the star light energy with a wider wavelength range (hundreds of nm wavelength), and the wavelength range of laser communication is very small (hundreds of nm), so that the spectroscope only removes the star light energy with very small part of wavelengths, and the spectroscope has very small influence on the star imaging of the star detection device.
In addition, the diameter of the laser communication antenna is usually far larger than that of a common star sensor, and the star detection device can have higher receiving sensitivity by using the laser communication light antenna.
(3) The star detection device calculates the visual axis pointing angle and the attitude information of the star detection device according to the received light energy, and sends the calculation result to a capture tracking controller of the space laser communication terminal; meanwhile, the rear light path of the communication terminal and the communication processor process the received laser to form spot position information of the laser, and the spot position information of the laser is sent to the capture tracking controller through the fine tracking mechanism.
The star detection device detects the direction of the receiving optical axis as the basic function, and in the first step of the scanning and capturing process of the laser communication system link establishment, the rough tracking optical axis of the system needs to be corrected by the star detection device and then is pointed in the direction of a preset target.
Further, the calculation result of the star detection device also comprises spot position information of a certain star in the detection view field.
The image sensor of the star detecting device can sense at least more than three stars, can calculate the received facula position information of all the stars, and then calculate the visual axis pointing angle according to the facula position information of the stars. Where it is necessary to select an appropriate star spot location for output to the capture tracking controller.
Further, spot position information of a certain fixed star in the detection view field is calculated, and the fixed star can select any single fixed star in the view field, wherein the selection mode comprises, but is not limited to, relative position, relative brightness and the like of the fixed star.
The light spots formed by multiple stars such as double stars in the space at close distance are irregular, and the calculated position information is inaccurate, so that single stars need to be selected as much as possible.
The stronger the relative brightness of the single star, the higher the signal to noise ratio of the light spot, and the more accurate the calculated position information. The position using the single star output with stronger relative brightness has higher signal to noise ratio, after the frequency of the output position is increased, the accumulation time of the image sensor to the star light energy is reduced, and the single star with weaker light intensity may not be sensitive.
The single star with stronger light intensity near the center of the image sensor is used as much as possible, so that when the star at the edge of the image sensor is used, the star image is prevented from deviating from the sensitive area of the image sensor due to shaking of the platform.
Meanwhile, the rear light path of the communication terminal and the communication processor process the received laser to form spot position information of the laser, and the spot position information of the laser is sent to the capture tracking controller through the fine tracking mechanism.
The received laser is processed to form spot position information, which is a source of off-target quantity of closed-loop control of the fine tracking mechanism.
(4) The capture tracking controller controls the coarse tracking mechanism and the fine tracking mechanism according to the current working state, information input by the star detection device and spot position information of laser, and completes scanning capture and tracking control of laser communication.
Further, the control coarse tracking mechanism specifically includes:
(400) In the initial pointing stage or the star calibration stage, the visual axis pointing angle and posture information output by the star detection device are used for driving the coarse tracking mechanism to accurately point the optical axis to a preset target direction.
Since the optical axis of the star detecting means is the same as the receiving optical axis, the target is directed, i.e. the star detecting means is directed.
(401) In the scanning and capturing stage, the spot position information of a certain fixed star output by the fixed star detection device is used as the off-target quantity to perform the closed-loop control of the coarse tracking mechanism.
And selecting the position of the single star which is close to the center of the image and has the brightest relative brightness as the reference position of the rough tracking closed loop, and performing the rough tracking by taking the position of the single star as the off-target quantity. The refresh rate of the star sensor output receiving optical axis direction in the market is below 20Hz, because the star detection device does not need the star with weaker sensitive brightness and the calculation of the optical axis direction when the coarse tracking is closed, the refresh frequency of the star detection device output selected star position (such as above 100 Hz) can be greatly improved, thereby the closed loop bandwidth of the coarse tracking loop can be improved, the inhibition of the low-frequency part of the platform vibration is enhanced, the uncertainty area of scanning capture is reduced, and the link establishment time of the system is further shortened.
(402) In the stable tracking stage, the light spot position information of the communication laser or the light spot position information of a certain fixed star output by the fixed star detection device is used for carrying out closed-loop control of the coarse tracking mechanism.
In the tracking stage after the establishment of the communication link, a fine tracking closed loop and a coarse tracking closed loop can be realized by using a fine tracking image detector, and a coarse tracking closed loop can also be realized by using an image sensor to provide the off-target quantity of a single star with stronger light intensity.
Those of ordinary skill in the art will appreciate that: the discussion of any of the embodiments above is merely exemplary and is not intended to suggest that the scope of the invention, including the claims, is limited to these examples. Any omission, modification, equivalent replacement, improvement, etc. of the above embodiments should be included in the protection scope of the present invention, while remaining within the spirit and principle of the present invention.
Claims (6)
1. The method for capturing and tracking space laser communication by using the star detection device is realized based on the star detection device and a space laser communication terminal, wherein the space laser communication terminal comprises a spectroscope, a communication terminal rear light path and communication processor, a capturing and tracking controller, a coarse tracking mechanism and a fine tracking mechanism, and is characterized by comprising the following steps:
(1) The optical axis of the star detection device and the rough tracking optical axis of the space laser communication terminal are arranged by adopting a common optical axis, and the rough tracking mechanism drives the optical axis of the star detection device and the rough tracking optical axis of the space laser communication terminal to synchronously rotate;
(2) The space light enters the spectroscope through the rough tracking optical axis, and the spectroscope separates the light beams according to the light wavelength: the energy of the laser communication wavelength received by the space enters the communication terminal after being totally reflected by the spectroscope, and then enters the optical path and the communication processor, and the light energy of other wavelengths which do not contain the laser communication wavelength received by the space enters the star detection device through the spectroscope; meanwhile, the laser energy of the light path behind the communication terminal and the emission wavelength output by the communication processor enters a space through a coarse tracking optical axis after being totally reflected by a spectroscope;
(3) The star detection device calculates the visual axis pointing angle and the attitude information of the star detection device according to the received light energy, and sends the calculation result to a capture tracking controller of the space laser communication terminal; meanwhile, the rear light path of the communication terminal and the communication processor process the received laser to form spot position information of the laser, and the spot position information of the laser is sent to the capture tracking controller through the fine tracking mechanism;
(4) The capture tracking controller controls the coarse tracking mechanism and the fine tracking mechanism according to the current working state, information input by the star detection device and spot position information of laser, and completes scanning capture and tracking control of laser communication.
2. The method of claim 1, wherein the star detector is a photoelectric system capable of calculating the visual axis pointing angle and the spot position by using star detection, including but not limited to a star sensor.
3. The method for capturing and tracking space laser communication by using a star detector according to claim 1, wherein the optical axis of the star detector in the step (1) and the rough tracking optical axis of the space laser communication terminal adopt a common optical axis installation mode, and the optical axes of the star detector and the rough tracking optical axis are parallel or on the same optical axis.
4. The method of claim 1, wherein the calculation of the sidereal detection apparatus in step (3) further comprises detecting the spot position information of a sidereal in the field of view.
5. The method of claim 4, wherein when calculating the spot position information of a certain star in the detection field, the star selects any single star in the field, and the selection method includes but is not limited to the relative position and relative brightness of the star.
6. The method for capturing and tracking space laser communication using a star detector as defined in claim 4, wherein the controlling the coarse tracking mechanism in step (4) specifically comprises:
in the initial pointing stage or the star calibration stage, the visual axis pointing angle and posture information output by the star detection device are used for driving the coarse tracking mechanism to accurately point the optical axis to a preset target direction;
in the scanning and capturing stage, the spot position information of a certain fixed star output by the fixed star detection device is used as the off-target quantity to perform the closed-loop control of the coarse tracking mechanism;
in the stable tracking stage, the spot position information of laser or the spot position information of a certain fixed star output by the fixed star detection device is used for carrying out closed-loop control of the coarse tracking mechanism.
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