阅读说明：本技术 星载激光通信终端的光斑快速捕获方法及系统 (Method and system for quickly capturing light spots of satellite-borne laser communication terminal ) 是由 梅博 李梦男 杨中华 吴孟桦 张桓源 王海升 于 2021-07-27 设计创作，主要内容包括：本发明提出了一种星载激光通信终端的光斑快速捕获方法及系统。该方法为确定扫描不确定区域,将其划分为多个等步长的螺旋扫描子区域,每个扫描子区域的中心点为一个螺旋点；规划压电陶瓷偏摆镜(PZT)在扫描子区域内的扫描路径,控制PZT对该扫描子区域进行精扫描,如捕捉到光斑,则扫描结束；如该扫描子区域已扫描完毕,仍未捕捉到光斑,则控制电机按等步长螺旋扫描线走点至下一个扫描子区域的中心点,进行粗扫描,如电机走点后捕获到光斑,则扫描结束；如未捕捉到光斑,则规划PZT在当前扫描子区域内的扫描路径,控制PZT对该扫描子区域进行精扫描,如此反复,直至捕捉到光斑或电机完成全部螺旋走点。该方法具有扫描捕获快时间短,扫描捕获概率大的特点。(The invention provides a method and a system for quickly capturing light spots of a satellite-borne laser communication terminal. The method comprises the steps of determining a scanning uncertain area, dividing the scanning uncertain area into a plurality of spiral scanning sub-areas with equal step length, wherein the central point of each scanning sub-area is a spiral point; planning a scanning path of a piezoelectric ceramic deflection mirror (PZT) in a scanning subarea, controlling the PZT to perform fine scanning on the scanning subarea, and if light spots are captured, finishing the scanning; if the scanning of the scanning subarea is finished and the light spot is not captured, controlling the motor to move from the constant-step-length spiral scanning line to the central point of the next scanning subarea for rough scanning, and if the light spot is captured after the motor moves, ending the scanning; if the light spot is not captured, planning a scanning path of the PZT in the current scanning sub-area, controlling the PZT to perform fine scanning on the scanning sub-area, and repeating the steps until the light spot is captured or the motor finishes all spiral walking points. The method has the characteristics of short scanning and capturing time and high scanning and capturing probability.)

1. A method for quickly capturing light spots of a satellite-borne laser communication terminal is characterized by comprising the following steps:

determining a scanning uncertain region, dividing the scanning uncertain region into a plurality of spiral scanning sub-regions with equal step length, forming an equal step length spiral scanning line at the central point of all the scanning sub-regions, and taking the central point of each scanning sub-region as a spiral point;

planning a scanning path of the PZT in a scanning sub-area, controlling the PZT to perform fine scanning on the scanning sub-area, and if a light spot is captured, finishing the scanning; if the scanning of the scanning subarea is finished and the light spot is not captured, controlling the motor to move from the constant-step-length spiral scanning line to the central point of the next scanning subarea for rough scanning, and if the light spot is captured after the motor moves, ending the scanning; if the light spot is not captured, planning a scanning path of the PZT in the current scanning sub-area, controlling the PZT to perform fine scanning on the scanning sub-area, and repeating the steps until the light spot is captured or the motor finishes all spiral walking points.

2. The method for rapidly capturing the light spot of the satellite-borne laser communication terminal according to claim 1, wherein when the motor completes all the spiral travel points and the light spot is not captured yet, the scanning uncertainty area is divided into a plurality of spiral scanning sub-areas with equal step length again, and the light spot is captured again according to the method of claim 1.

3. The method for rapidly capturing the light spot of the satellite-borne laser communication terminal according to claim 1, wherein when scanning sub-regions are divided, a two-dimensional coordinate system is established by taking an initial aiming angle of a satellite as a scanning origin, an azimuth angle and a pitch angle of the terminal, an equal-step-length spiral scanning line is arranged in the two-dimensional coordinate system, each spiral point is a motor target walking point, and a scanning uncertain region is divided into a plurality of spiral scanning sub-regions by taking each spiral point as a center.

4. The method as claimed in claim 1, wherein before controlling PZT to scan the sub-scanning area, a polar coordinate system is established in the sub-scanning area with each spiral point as an origin, a scanning path of PZT in the sub-scanning area is planned, and coordinate point parameters of the PZT scanning path are converted from the polar coordinate system to a two-dimensional coordinate system of the terminal, so as to obtain a pitch/azimuth angle control amount during PZT scanning.

5. The method as claimed in claim 1, wherein the method for rapidly capturing the light spot of the satellite-borne laser communication terminal is characterized in that the length of the spiral line with equal step length in the uncertainty regionWherein L is the step length of the spiral point, and theta is the range of the spiral angle;

when theta is greater than pi, the crystal grain size,wherein r is the half angle of the uncertain region, and n is the total number of spiral points.

6. The method as claimed in claim 4, wherein the expression of each spiral point in the polar coordinate system of the uncertainty region isWhere ρ is_iIs the diameter of the spiral point, theta_iIs a spiral point polar angle; i refers to the ith spiral point;

the expression converted into the terminal azimuth/pitch axis two-dimensional coordinate system isWherein x is_iIs the azimuth axis angle of the spiral point; y is_iIs the pitch axis angle of the pitch point.

7. The method as claimed in claim 4, wherein the scanning mode of PZT in scanning sub-area is raster-spiral scanning mode, and PZT single step moving distance isAlpha is the signal beam divergence angle.

8. The method for rapidly capturing the light spot of the satellite-borne laser communication terminal as claimed in claim 6, wherein the PZT scan path coordinate point parameter matrix is transformed from a sub-region polar coordinate system to a terminal two-dimensional coordinate system according to the following relation:

where ρ is_NmatirxThe polar diameters of all scanning points of the PZT sub-region under the uncertain domain polar coordinate system are obtained;

θ_Nmatirxscanning point polar angles of all PZT sub-areas under an uncertain domain polar coordinate system;

x_Nmatirxcontrolling the azimuth axis control quantity of all scanning points of the PZT sub-area under a terminal two-dimensional coordinate system;

y_Nmatirxthe control quantity of the pitching axes of all scanning points of the PZT sub-area under a terminal two-dimensional coordinate system is obtained;

ρ’_Nmatirxthe polar diameters of all scanning points of PZT under a sub-region polar coordinate system;

θ’_Nmatirxthe polar angles of all scanned points of PZT are in the sub-region polar coordinate system.

9. A system for rapidly capturing light spots is characterized by comprising a control terminal, a motor and PZT, wherein the control terminal is connected with the motor and the PZT in a control mode and used for controlling the motor and the PZT to capture the light spots in an inter-satellite and/or inter-satellite laser communication link according to the method for rapidly capturing the light spots of the satellite-borne laser communication terminal of any one of claims 1-8.

Technical Field

The invention relates to the field of inter-satellite laser communication, in particular to a method and a system for quickly capturing light spots of a satellite-borne laser communication terminal.

Background

The inter-satellite laser communication system has the advantages of high communication speed, large communication capacity, strong anti-interference capability, good confidentiality, terminal miniaturization and the like, and is one of important development trends of future space networks. At present, the laser communication test among satellites is carried out successively in China, America and Europe. In the year 2020, Starlink in 8 months completes the first inter-satellite laser communication in-orbit test, and in the same month, the aerospace science and industry group cloud engineering in China also successfully develops the low-orbit satellite laser communication test. Because the inter-satellite laser communication has the characteristics of long communication distance, small signal beam divergence angle and the like, the method puts high requirements on the scanning and capturing technology of the inter-satellite laser communication system.

According to the traditional scanning technology, large-beam divergence angle beacon light is adopted for scanning, an uncertain area can be quickly covered, a terminal can quickly capture the beacon light in a short time, and after the capture is finished, small-beam divergence angle signal light is switched to perform stable tracking and link building, so that inter-satellite laser communication is finally realized. However, the beacon beam divergence angle is usually tens of times larger than the signal beam divergence angle, resulting in a large power requirement for the beacon light, which puts more stringent requirements on the power consumption index of the system. In addition, the beacon light and the signal light have different wavelengths, and an optical component needs to be additionally arranged on the terminal, so that the weight, the volume and the complexity of the system are further increased, and the light weight and the miniaturization design of the terminal are challenged.

The beacon-free scanning technology does not need to additionally arrange a beacon light assembly, and small-beam divergence angle signal light is directly adopted for scanning and capturing, so that important indexes of the satellite-borne laser terminal, such as weight, volume, power consumption, manufacturing cost and the like, are favorably reduced, and the development requirement of commercial space flight is met. However, in the current stage, the beacon-free technology is restricted by factors such as small divergence angle of signal beams, relative motion between satellites, shaking of a satellite platform and the like, so that the problems of long scanning time, high scanning and capturing difficulty and the like of the beacon-free technology are caused, and the development of the beacon-free technology is further restricted. In order to adapt to the development trend of low power consumption and light size of the current satellite laser communication terminal and better meet the requirements of China on large-scale construction and networking of low-orbit constellations in the future, research on a beacon-free rapid scanning technology of an inter-satellite laser communication system is more and more urgent.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a method and a system for quickly capturing a light spot of a satellite-borne laser communication terminal.

In order to achieve the above object, the present invention provides a method for quickly capturing a light spot of a satellite-borne laser communication terminal, comprising the following steps:

determining a scanning uncertain region, dividing the scanning uncertain region into a plurality of spiral scanning sub-regions with equal step length, forming an equal step length spiral scanning line at the central point of all the scanning sub-regions, and taking the central point of each scanning sub-region as a spiral point;

planning a scanning path of the PZT in a scanning sub-area, controlling the PZT to perform fine scanning on the scanning sub-area, and if a light spot is captured, finishing the scanning; if the scanning of the scanning subarea is finished and the light spot is not captured, controlling the motor to move from the constant-step-length spiral scanning line to the central point of the next scanning subarea for rough scanning, and if the light spot is captured after the motor moves, ending the scanning; if the light spot is not captured, planning a scanning path of the PZT in the current scanning sub-area, controlling the PZT to perform fine scanning on the scanning sub-area, and repeating the steps until the light spot is captured or the motor finishes all spiral walking points.

When the motor finishes all spiral walking points and light spots are not captured yet, dividing the scanning uncertain area into a plurality of spiral scanning sub-areas with equal step length again, and capturing the light spots again according to the method.

The method is applied to an inter-satellite and inter-satellite laser communication link, a motor is used as a coarse scanning mechanism, the method has the characteristic of large scanning range, PZT is used as a fine scanning mechanism, the method has the characteristic of high control frequency, the method of composite spiral scanning of the coarse and fine scanning mechanisms can realize the rapid full-coverage scanning of signal light with beam divergence angles of dozens of micro radians (mrads) in an uncertain domain of several milliradians (mrads), and the method has the characteristics of short scanning and capturing time and high scanning and capturing probability.

When scanning sub-areas are divided, a two-dimensional coordinate system is established by taking the initial aiming angle of the satellite as a scanning origin, the terminal azimuth angle and the pitching angle, an equal-step-length spiral scanning line is arranged in the two-dimensional coordinate system, each spiral point is a motor target walking point, and a scanning uncertain area is divided into a plurality of spiral scanning sub-areas by taking each spiral point as a center.

Before the PZT is controlled to scan the scanning sub-region, a polar coordinate system is established in the scanning sub-region by taking each spiral point as an origin, a scanning path of the PZT in the sub-region is planned, coordinate point parameters of the PZT scanning path are converted into a terminal two-dimensional coordinate system from the polar coordinate system, and the pitching/azimuth angle control quantity during PZT scanning is obtained.

The invention also provides a system for rapidly capturing the light spots, which comprises a control terminal, a motor and PZT, wherein the control terminal is in control connection with the motor and the PZT and controls the motor and the PZT to capture the light spots in the inter-satellite and/or satellite-ground laser communication link according to the method for rapidly capturing the light spots of the satellite-borne laser communication terminal.

The invention has the beneficial effects that: compared with the beacon scanning method, the method reduces the weight and power consumption of the terminal, reduces the complexity of the optical system of the terminal, effectively reduces the difficulty of non-beacon scanning and capturing, reduces the time of non-beacon scanning and capturing, and improves the on-orbit link building efficiency of the inter-satellite laser communication system.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic flow diagram of the process of the present invention;

FIG. 2 is a schematic diagram of a constant step size spiral in an uncertain region;

FIG. 3 is a schematic diagram of the PZT scanning path within a scanning sub-region;

FIG. 4 is a schematic diagram of coordinate conversion of coordinate point parameters of PZT scanning paths;

FIG. 5 is a schematic diagram illustrating the method of the present invention scanning full coverage in an uncertain region;

fig. 6 to 11 are simulation graphs of the light spot captured by the method of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, unless otherwise specified and limited, it is to be noted that the terms "mounted," "connected," and "connected" are to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, a communication between two elements, a direct connection, or an indirect connection via an intermediate medium, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.

As shown in fig. 1 and 5, based on the beacon-less technology, the invention provides a method for quickly capturing a light spot of a satellite-borne laser communication terminal, which is a composite scanning method combined with a coarse scanning mechanism, wherein a motor is used as a coarse scanning execution mechanism, a PZT (piezoelectric ceramic deflection mirror) is used as a fine scanning execution mechanism, and the method is applied to an inter-satellite and inter-satellite laser communication link, and specifically comprises the following steps:

determining a scanning uncertain area, dividing the scanning uncertain area into a plurality of spiral scanning sub-areas with equal step length, forming an equal step length spiral scanning line at the central point of all the scanning sub-areas, and taking the central point of each scanning sub-area as a spiral point.

Specifically, when scanning sub-regions are divided, a two-dimensional coordinate system is established by taking the initial aiming angle of the satellite as a scanning origin, the terminal azimuth angle and the pitching angle, an equal-step-length spiral scanning line is arranged in the two-dimensional coordinate system, each spiral point is a motor target walking point, and as shown in fig. 2, the scanning uncertain region is divided into a plurality of spiral scanning sub-regions by taking each spiral point as a center.

As shown in fig. 3, a polar coordinate system is established in the scanning sub-area with each spiral point as the origin, the scanning path of the PZT in the scanning sub-area is planned, and coordinate point parameters of the PZT scanning path are converted from the polar coordinate system to a terminal two-dimensional coordinate system, as shown in fig. 4, so as to obtain the pitch/azimuth angle control amount during PZT scanning. Controlling the PZT to perform fine scanning on the scanning sub-area according to the planned scanning path, and if the light spot is captured, finishing the scanning; if the scanning of the scanning subarea is finished and the light spot is not captured, controlling the motor to move from the constant-step-length spiral scanning line to the central point of the next scanning subarea for rough scanning, and if the light spot is captured after the motor moves, ending the scanning; if the light spot is not captured, planning a scanning path of the PZT in the current scanning sub-area, controlling the PZT to perform fine scanning on the scanning sub-area, and repeating the steps until the light spot is captured or the motor finishes all spiral walking points.

When the motor finishes all spiral walking points and light spots are not captured yet, dividing the scanning uncertain area into a plurality of spiral scanning sub-areas with equal step length again, and capturing the light spots again according to the method.

In the embodiment, the motor is preferably, but not limited to, an aerospace-grade high-precision permanent magnet synchronous motor, and when the motor is roughly scanned, the single-step travel point duration of the motor is related to the motor control bandwidth, and the single-step travel point duration is 1/motor control bandwidth. Normally, the control bandwidth of the motor is 6-10Hz, the control precision is less than or equal to 50 mu rad, and the maximum rotating speed is more than or equal to 5 degrees/s.

When the PZT scans in the scanning sub-area, the single-step scanning time is related to the PZT control bandwidth, the single-step scanning time is 1/PZT control bandwidth, and the PZT control bandwidth is more than or equal to 500 Hz.

In the preferred embodiment, when determining the equal-step helical scan line, the length of the equal-step helical scan line in the uncertainty region isWhereinL is the step length of the spiral point, and theta is the range of the spiral angle; when theta is greater than pi, the crystal grain size,wherein r is the half angle of the uncertain region, and n is the total number of spiral points.

After a polar coordinate system is established by taking each spiral point as an origin, the expression of each spiral point in the polar coordinate system of the uncertain region isWhere ρ is_iIs the diameter of the spiral point, theta_iIs a spiral point polar angle; i refers to the ith spiral point; the expression converted into the terminal azimuth/pitch axis two-dimensional coordinate system isWherein x is_iIs the azimuth axis angle of the spiral point; y is_iAnd obtaining the PZT pitching/azimuth angle control quantity for the spiral point pitching axis angle.

The scanning mode of PZT in scanning sub-area is preferably but not limited to raster-spiral scanning mode, in this embodiment, when raster-spiral scanning is adopted, the PZT single step moving distanceAlpha is the signal beam divergence angle.

And converting the PZT scanning path coordinate point parameter matrix from a scanning sub-area polar coordinate system to a terminal two-dimensional coordinate system, wherein the conversion relation is as follows:

where ρ is_NmatirxThe polar diameters of all scanning points of a PZT scanning sub-area under an uncertain domain polar coordinate system are obtained; theta_NmatirxTo be in insecurePolar angles of all scanning points of a PZT scanning sub-area under a localized polar coordinate system; x is the number of_NmatirxControlling the azimuth axis control quantity of all scanning points of a PZT scanning sub-area under a terminal two-dimensional coordinate system; y is_NmatirxThe control quantity of the pitching axes of all scanning points of the PZT scanning sub-area under a terminal two-dimensional coordinate system is obtained; rho'_NmatirxThe polar diameters of all scanning points of PZT under a sub-region polar coordinate system; theta'_NmatirxThe polar angles of all scanned points of PZT in the sub-region polar coordinate system are shown in fig. 3.

6-11 are simulation graphs of using the method to capture light spots, the average time of post-scan capture is less than 30s, and the scan capture probability is greater than 95%.

The application also provides a system for rapidly capturing the light spots, which comprises a control terminal, a motor and PZT, wherein the control terminal is connected with the motor and the PZT in a control mode and controls the motor and the PZT to capture the light spots in the inter-satellite and/or satellite-ground laser communication link according to the method for rapidly capturing the light spots of the satellite-borne laser communication terminal.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.