CN115578889A

CN115578889A - Spatial target collision early warning method based on distribution

Info

Publication number: CN115578889A
Application number: CN202211331897.7A
Authority: CN
Inventors: 杜国超; 亢瑞卿; 李达; 张伟祺; 李亚亚; 李小波; 亢志邦
Original assignee: Beijing Creatunion Information Technology Group Co Ltd
Current assignee: Beijing Creatunion Information Technology Group Co Ltd
Priority date: 2022-10-28
Filing date: 2022-10-28
Publication date: 2023-01-06

Abstract

The invention relates to the technical field of space target collision early warning, and discloses a distributed space target collision early warning method, which comprises the following steps of S1, preliminarily screening space targets, and preliminarily screening the space targets based on three steps of epoch time, near place, far place, minimum distance and the like; s2, accurately screening the space target, and further screening the space target discharged in the step S1; and S3, performing track forecasting and early warning calculation, and performing space target collision early warning calculation based on track data of the space target and a corresponding track forecasting model.

Description

Spatial target collision early warning method based on distribution

Technical Field

The invention relates to the technical field of space target collision early warning, in particular to a distributed space target collision early warning method.

Background

With the continuous exploration of space by human beings, a large amount of space debris is accumulated in the earth peripheral orbit, and the space debris flies around the earth at a high speed, so that the space debris has great destructive power on an on-orbit spacecraft and particularly has more possibly disastrous effects on a manned spacecraft. In order to protect the safety of the spacecraft, the spacecraft needs to be subjected to space debris collision risk assessment and calculation, and the dangerous orbit crossing time which may occur in the future is forecasted, so that measures are taken in advance to avoid collision of the spacecraft.

As published (bulletin) No.: the invention of CN114327919A discloses a method and a system for early warning collision of spatial targets, which are described in the specification, that the number of compiled on-orbit spatial targets already exceeds 22000, most of these compiled targets are targets with a size greater than 10cm, and this only accounts for a small part of the whole space debris, even if only the compiled spatial targets are considered, the calculation amount of the collision early warning is still huge: (1) the track extrapolation calculation amount is large: track forecasting is carried out on the catalogued space target for 7 days, and the position and the speed of the space target are calculated at intervals of 1 minute, so that 2.2 hundred million track forecasting calculations are needed; (2) the cross-over relationship is calculated in a large amount: calculating the meeting time and distance between the spacecraft and the space target, which are the modules with the largest calculated amount of a collision early warning system, and designing the contents of a plurality of parts such as interpolation, iteration and numerical integration, wherein the low-orbit spacecraft can meet another low-orbit target for 100 times within 7 days, and if the number of the early warning spacecrafts is 500 and the number of the space targets is 22000, billions of meeting events can be generated; as another example, publication (bulletin) No.: the invention of CN108197420B provides a spatial target collision early warning distance calculation method based on UT transformation, which combines a spatial target dynamics model, introduces UT transformation according to the nonlinear characteristics of the spatial target dynamics model, ensures that a Sigma point set and system state distribution have the same mean value and variance, and improves the estimation precision of the spatial target collision early warning distance, however, because perturbation compensation for orbit calculation is introduced in screening, the complexity of calculation is increased, and the total calculation time is increased on the contrary.

Disclosure of Invention

The invention aims to provide a distributed space target collision early warning method aiming at the defects of the prior art.

The technical purpose of the invention is realized by the following technical scheme: a distributed space target collision early warning method comprises the following steps:

the method comprises the following steps of S1, preliminarily screening a space target, and preliminarily screening the space target based on three steps of epoch time, near place, far place, minimum distance and the like;

s2, accurately screening the space target, and further screening the space target discharged in the step S1;

and S3, track forecasting and early warning calculation, and performing space target collision early warning calculation based on the track data of the space target and a corresponding track forecasting model.

Preferably, the following steps: and the epoch time screening of the step S1 screens out TLE numbers at the forecast epoch time 15 d.

Preferably, the method comprises the following steps: and S2, accurately screening the space target, wherein the space target comprises a coplanar high-risk time domain and a non-coplanar high-risk time domain, and the dangerous points of the spacecraft and the space target are extrapolated for 0.5min before and after the moment.

Preferably, the following steps: and the step S2 is that the high-risk time domain of the non-coplanar condition is determined by a Kepler equation system.

Preferably, the method comprises the following steps: the collision probability calculation in the step S3 comprises a geocentric inertial system and a UNW coordinate system, and the transformation matrix of the geocentric inertial system and the UNW coordinate system is as follows

Preferably, the following steps: and the spatial target forecasting model in the step S3 adopts SGP4.

Preferably, the following steps: and S3, the spacecraft orbit parameters of the space target forecasting model comprise the julian day, the number of rotation cycles per day, the ascension of the ascending intersection point, the argument of the perigee, the eccentricity, the approach angle and the orbit inclination angle.

Preferably, the following steps: and the collision early warning calculation step length of the step S3 is selected to be 0.1min, and the collision critical distance is selected to be 50km.

Compared with the prior art, the scheme of the invention has the following beneficial effects:

according to the invention, according to the characteristics of space flight of the spacecraft and the space debris, a multi-screening space target collision early warning algorithm combining the close number and the TLE number, a two-body model and an SGP4/SDP4 model is provided, the effectiveness and the accuracy of the early warning algorithm are proved through simulation, and the early warning efficiency and the early warning time of collision of the spacecraft and the space debris target are improved.

Drawings

Shown in the figure

FIG. 1 is a spatial target trajectory early warning model based on a distributed spatial target collision early warning method;

FIG. 2 is a schematic diagram of an early warning result of an embodiment of a distributed spatial target collision early warning method according to the present invention;

fig. 3 is a schematic flow chart of a distributed spatial target collision warning method according to the present invention.

Detailed Description

The invention provides a distributed space target collision early warning method, which comprises the following steps:

For a space target with a larger size (such as the diameter is larger than 10 cm), the spacecraft can ensure safety only by avoiding maneuver, the targets of the type need to be tracked and cataloged, approach analysis and collision early warning are carried out by utilizing real-time updated orbit data, the operation safety of the spacecraft can be improved, because errors inevitably exist in target observation, orbit determination and orbit prediction, error analysis is an inevitable problem in space target collision risk assessment, and factors such as orbit determination and prediction errors, covariance estimation errors, avoidance maneuver momentum errors and the like need to be considered in the space target collision early warning and avoidance maneuver process.

Referring to fig. 1, spatial target trajectory data is a basis for collision warning, and only if spatial target trajectory data as much as possible and as accurate as possible is mastered, an accurate and effective warning result can be obtained, a spatial target trajectory model finds and tracks motion parameters of a spatial target in real time through various observation means, further determines trajectory characteristics of the spatial target, catalogs large-space targets, and continuously updates trajectory data according to observed trajectory data to form a target dynamic database, wherein NORAD spatial cataloging root TLE is an average trajectory root, and a corresponding SGP4/SDP4 model is an analytic model.

The TLE orbit number is the average orbit number with periodic disturbance items removed by a specific method, comprises the orbit number of a space target and other related information, and consists of two lines of 69 character data, and comprises information about the target, such as a target number, an international number, an atmospheric resistance item and the like, six independent orbit numbers describe the motion of a satellite, a time reference point is defined at epoch time, an atmospheric resistance related item is also arranged in the TLE and describes the degree of the space target influenced by the atmospheric resistance, in order to obtain a prediction result with higher accuracy, the prediction model must rebuild the disturbance in the same method, therefore, the TLE must be used together with an SGP4/SDP4 orbit prediction model to predict the state of the space target, and if the TLE orbit number is input into other models, even if the model has higher accuracy or even a numerical integration model, only a result with lower accuracy can be obtained.

In order to improve the precision of collision early warning, the collision early warning based on collision probability utilizes the specific position error information of a target to evaluate the risk of an approaching event, how to obtain the orbit error covariance information of a space target and how to obtain the precision of the information, and is one of the key problems of the collision early warning based on the collision probability, how to directly influence the feasibility and the confidence coefficient of the collision early warning based on the collision probability is solved, two forms of inner coincidence precision and outer coincidence precision are commonly used in the actual work to define the track determination precision, according to two evaluation methods of the orbit determination precision, in combination with the reality of the space target collision early warning project, aiming at different targets and the track information sources thereof, the track error analysis methods mainly comprise the following three steps:

(1) Based on error extrapolation of an orbit model, acquiring observation data with high target precision by using methods such as a foundation or space-based observation station, a satellite-borne inertia sensitive device or satellite-borne navigation equipment, and the like, acquiring orbit root and motion state vectors from the observation data by using an orbit determination theory, and simultaneously acquiring error information or an initial covariance matrix determined by an orbit, wherein the initial covariance matrix can be derived by using a transfer matrix, the transfer matrix is determined by the orbit model, and due to nonlinearity of the orbit dynamics model, the transfer matrix in an analytic form can not be generally obtained, except for numerical analysis, a covariance analysis description function method is a common linearized error analysis tool, can be used for analyzing the statistical characteristics of a linear or nonlinear system containing random errors, and has the characteristics of time saving, high precision and high reliability;

(2) Compared with the high-precision orbit prediction result, the orbit prediction precision can be evaluated by comparing a TLE orbit prediction ephemeris with a high-precision ephemeris, orbit data with higher precision is used as a reference, and the high-precision orbit data generally come from an owner of a spacecraft, orbit determination observation data or a predicted orbit obtained by using a high-precision orbit predictor;

(3) Based on the error analysis and application of historical orbit data, for most space non-cooperative targets (such as non-own or failed satellites, rocket bodies, space debris and the like) which can not provide cooperative information, due to the fact that the number is large and high-precision observation data are lacked, only orbit flat root numbers are given in a general space catalogue, corresponding to an analytic model, and most of the analytic space target catalogs do not contain precision or covariance information. Therefore, a space target orbit prediction error evaluation method with high precision and convenient use is needed in the collision early warning engineering, and a feasible method for non-cooperative targets is to perform error statistical analysis by using historical orbit data. The basic idea of the historical data-based approach is to obtain covariance information using statistical analysis methods by comparing the TLE forecast state (or state estimate obtained by TLE processing) near epoch time with the state propagated by previous TLE to that time to obtain residual. The premise of this approach is that inventory management of the target is stable, i.e., the level of accuracy of its corresponding series of track counts should be roughly comparable. Most current methods can be divided into two categories: initial error analysis and error evolution analysis.

According to the method, the collision probability with higher precision can be obtained for the proximity event through the collision probability calculation method, but direct and explicit connection between the collision probability and the collision parameters is not given through the methods, the relation between the collision probability and the influence factors of the collision probability is difficult to obtain, and the relation between the collision probability and the influence factors is very important in maximum collision probability analysis, collision probability sensitivity analysis, confidence degree analysis and avoidance maneuver strategy research based on the collision probability.

The approach distance, the components thereof and the collision probability are two important collision risk evaluation criteria in space target collision early warning, the collision probability comprehensively considers the intersection geometric relationship, the position error covariance and the target size, and is a relatively comprehensive risk evaluation parameter, and meanwhile, the information of the approach distance, the relative position, the relative speed, the intersection angle and the like is also an important risk evaluation index. The collision probability is more precise than the approach distance but is easily influenced by covariance uncertainty, in some cases, the approach distance-based method is a more reliable but more conservative method, and the two types of risk assessment parameters are generally given simultaneously in the spatial target collision early warning, so it is necessary to know the relationship between the collision probability and the intersection geometry, which is of great significance for more deeply understanding the two types of indexes and reasonably applying the two types of indexes in the collision early warning engineering.

Because the parameters for calculating the collision probability are uncertain, the sensitivity of the calculated collision probability to the parameter change needs to be determined, the sensitivity analysis of the collision probability refers to the research on the influence of the change of all influencing factors (intersection geometric parameters, position error covariance, target size and the like) of the collision probability on the collision probability, the analysis on the sensitivity of the intersection geometric relationship can determine how to select an avoidance maneuver strategy and analyze the influence of track forecast system errors on the collision probability, the calculation of the collision probability is most sensitive to the size of the covariance, the improper covariance value can cause false alarms and false alarms, and the sensitivity analysis on the track error covariance can be used for maximum collision probability analysis, false alarm rate analysis and probability dilution analysis.

Examples

Referring to fig. 1 and 3, the invention provides a spatial target collision early warning method based on distribution, which includes the following steps:

s2, accurately screening the space targets, and further screening the space targets discharged in the step S1;

and S3, track forecasting and early warning calculation, and performing collision early warning calculation on the space target based on the track data of the space target and a corresponding track forecasting model.

In the embodiment, through the screening of the targets and the orbit prediction calculation, the time and the orbit position of a dangerous space target and a possible collision can be determined, the distance change between two space targets which are close to each other is shown in fig. 2, and the space target finally determined through the rapid screening and the rapid orbit prediction and the time of the possible collision can be used as the calculation input for accurately predicting the collision early warning of the important spacecraft and the space target.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications without inventive contribution to the present embodiment as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims

1. A distributed space target collision early warning method is characterized by comprising the following steps:

2. The distributed spatial target collision warning method according to claim 1, wherein the epoch time filtering of step S1 filters out TLE numbers of forecast epoch time 15 d.

3. The distributed space target collision early warning method according to claim 1, wherein the step S2 of accurately screening the space target comprises a coplanar condition high risk time domain and a non-coplanar condition high risk time domain, and the spacecraft and the space target dangerous point are extrapolated for 0.5min before and after the moment.

4. The distributed space target collision early warning method according to claim 3, wherein the high risk time domain in the non-coplanar condition in the step S2 is determined by Keplerian equations.

5. The distributed spatial target collision warning method according to claim 1, wherein the collision probability calculation of step S3 includes geocentric inertial system and UNW coordinate system, and the transformation matrix of the geocentric inertial system and the UNW coordinate system is as follows,

。

6. the distributed spatial target collision warning method according to claim 1, wherein the spatial target forecasting model in step S3 adopts SGP4.

7. The distributed space target collision warning method according to claim 6, wherein the spacecraft orbit parameters of the space target forecasting model in the step S3 include julian day, number of turns per day, ascension of ascending intersection, argument of near place, eccentricity, mean angle and inclination of orbit.

8. The distributed space target collision early warning method based on the claim 7 is characterized in that the collision early warning calculation step length of the step S3 is selected to be 0.1min, and the collision critical distance is selected to be 50km.