阅读说明：本技术 一种基于地表模型图的星下点地表属性预报方法 (Earth surface model graph-based method for forecasting earth surface attributes of subsatellite points ) 是由 刘洁 黄缙 莫凡 田科丰 王淑一 周剑敏 陈超 程莉 杨晓龙 刘彤 于 2020-05-07 设计创作，主要内容包括：一种基于地表模型图的星下点地表属性预报方法,属于航天器姿态控制领域,首先预装地表模型图,地表模型图采用等间隔的经度条带,每一个条带给出该条带区域内为“境内或者陆地”的地理纬度上限和下限,以简化星上地表定位算法。其次星上自主预报目标t时刻星下点的地理经度L和地理纬度δ。最后根据预装的中国境内地图进行境内或者境外的预报,根据预装的陆地地图进行陆地或者海洋的预报。本发明方法解决了存储DEM数字高程模型数据存储量较大、搜索算法对软件计算要求较高的问题。(A method for forecasting earth surface attributes of points under a satellite based on an earth surface model map belongs to the field of spacecraft attitude control. And secondly, autonomously forecasting the geographical longitude L and the geographical latitude of the subsatellite point at the target time t on the satellite. Finally, performing indoor or outdoor forecast according to a pre-installed Chinese indoor map, and performing land or ocean forecast according to a pre-installed land map. The method solves the problems that the storage capacity for storing DEM digital elevation model data is large, and the requirement of a search algorithm on software calculation is high.)

1. A method for forecasting the earth surface attribute of an interstellar point based on an earth surface model diagram is used for forecasting the earth surface attribute of the interstellar point on a satellite, and is characterized by comprising the following steps:

s1, establishing a terrain model diagram, wherein the terrain model diagram is divided into a plurality of longitude strips according to geographic longitude;

s2, marking the upper geographic latitude limit and the lower geographic latitude limit of all the land areas on the boundary of each longitude strip according to the world land map; marking the upper limit of the Chinese geographical latitude and the lower limit of the Chinese geographical latitude on the boundary of the longitude strip where China is located according to the Chinese map;

s3, forecasting coordinates of the satellite points in real time according to the orbit of the satellite; determining a longitude strip by utilizing the longitude strip range of the coordinate of the sub-satellite point at S3; then, in the longitude strip, determining the relation between the coordinate of the substellar point and the upper limit and the lower limit of the geographical latitude, and forecasting whether the substellar point is on land or sea; and in the longitude strip, determining the relation between the coordinates of the subsatellite point and the upper limit and the lower limit of the Chinese geographical latitude, and forecasting whether the subsatellite point is in the Chinese environment.

2. The method for forecasting the earth surface attribute of a sub-satellite based on a terrain model map as claimed in claim 1, wherein in S1, the terrain model map is divided into a plurality of longitude strips at equal geographic longitude intervals.

3. The method for forecasting the surface properties of the sub-satellite points based on the surface model map as claimed in claim 2, wherein in S1, the surface model map is divided into a plurality of longitude strips with equal intervals of not more than 1 °.

4. The method for forecasting the earth surface properties of the sub-satellite points based on the earth surface model map as claimed in claim 1, wherein in S3, the relationship between the coordinates of the sub-satellite points and the upper and lower geographic latitudes is determined within a certain longitude band, and the method for forecasting the sub-satellite points to be on land or sea is:

correspondingly connecting one or more groups of upper geographic latitude limits and one or more groups of lower geographic latitude limits on two boundaries of the longitude strip to form one or more convex polygons; when the coordinates of the subsatellite point are positioned in any convex polygon, the earth surface attribute of the subsatellite point is forecasted to be land;

in a certain longitude strip, determining the relationship between the coordinates of the subsatellite point and the upper limit of Chinese geographical latitude and the lower limit of Chinese geographical latitude, and forecasting whether the subsatellite point is in Chinese environment or not comprises the following steps:

if two boundaries of the longitude strip are provided with upper Chinese geographical latitude limits and lower Chinese geographical latitude limits, one or more groups of upper Chinese geographical latitude limits are correspondingly connected, and one or more groups of lower Chinese geographical latitude limits are correspondingly connected to form one or more convex polygons; and when the coordinates of the subsatellite point are positioned in any convex polygon, forecasting the subsatellite point to be positioned in the Chinese environment.

5. The method according to claim 4, wherein linear interpolation is used to form one or more convex polygons when the geographic latitude upper limit and the geographic latitude lower limit are connected correspondingly; when the upper limit of the Chinese geographical latitude is correspondingly connected and the lower limit of the Chinese geographical latitude is correspondingly connected, linear interpolation is adopted to form one or more convex polygons.

6. The method of claim 5, wherein the convex polygon is a trapezoid.

7. The method for forecasting the earth surface attribute of the sub-satellite points based on the earth surface model map as claimed in any one of claims 1 to 6, wherein the latitude range of the earth surface model map covers 90 ° north latitude to 90 ° south latitude.

8. The method for forecasting the earth surface attribute of the sub-satellite based on the earth surface model map as claimed in claim 1, wherein in S1, the earth surface model map is first divided into a plurality of longitude bands at equal geographic longitude intervals;

in S2, marking the upper geographic latitude limits and the lower geographic latitude limits of all the land areas on the boundary of each longitude strip according to the world land map, and correspondingly connecting one or more groups of upper geographic latitude limits and one or more groups of lower geographic latitude limits on the two boundaries of each longitude strip to form one or more land convex polygons; marking Chinese geographical latitude upper limits and Chinese geographical latitude lower limits on the boundaries of longitude strips where China is located according to a Chinese map, and correspondingly connecting one or more groups of Chinese geographical latitude upper limits and one or more groups of Chinese geographical latitude lower limits on two boundaries of each longitude strip where China is located to form one or more convex polygons in China;

when the number of the land convex polygons in the two adjacent longitude strips is equal and the number of the convex polygons in the Chinese world is equal, the land convex polygons in the two longitude strips share one edge in pairs, and the convex polygons in the Chinese world in the two longitude strips share one edge in pairs; each paired land convex polygon and each paired international convex polygon comprise 8 edges, except for 4 edges located on the boundary of each longitude strip, if the other 4 edges are intersected in two groups, and the included angle between the two intersected edges of each group is 179-181 degrees, returning to S1 to merge the two adjacent longitude strips into one longitude strip.

9. The method for forecasting the earth surface attribute of a sub-satellite based on a terrain model map as claimed in claim 8, wherein in S1, before the two adjacent longitude strips are merged, the terrain model map is divided into a plurality of longitude strips by using an equal interval not exceeding 0.2 °.

Technical Field

The invention relates to a method for forecasting earth surface attributes of an off-satellite point based on an earth surface model diagram, belongs to the field of spacecraft attitude control, and is suitable for a spacecraft with off-satellite point attribute forecasting requirements.

Background

For the prediction of surface attributes, especially for the prediction of land/ocean, the existing method generally stores a DEM digital elevation model on a satellite specially, and judges whether the model is land or ocean according to the elevation of a sub-satellite point. The method has large data storage capacity, the search algorithm has high software calculation requirements, and the current DEM digital elevation model has no data at the latitude of more than 80 degrees, so that the accurate judgment of the earth surface attribute can not be carried out.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the method comprises the steps of firstly pre-installing a surface model diagram, wherein the surface model diagram adopts equally spaced longitude strips, and each strip gives an upper limit and a lower limit of geographical latitude which are 'domestic or terrestrial' in the strip region so as to simplify an on-satellite surface positioning algorithm. And secondly, autonomously forecasting the geographical longitude L and the geographical latitude of the subsatellite point at the target time t on the satellite. Finally, performing indoor or outdoor forecast according to a pre-installed Chinese indoor map, and performing land or ocean forecast according to a pre-installed land map.

The purpose of the invention is realized by the following technical scheme:

a method for forecasting the earth surface attribute of an interstellar point based on an earth surface model diagram is used for forecasting the earth surface attribute of the interstellar point on a satellite and comprises the following steps:

s1, establishing a terrain model diagram, wherein the terrain model diagram is divided into a plurality of longitude strips according to geographic longitude;

s2, marking the upper geographic latitude limit and the lower geographic latitude limit of all the land areas on the boundary of each longitude strip according to the world land map; marking the upper limit of the Chinese geographical latitude and the lower limit of the Chinese geographical latitude on the boundary of the longitude strip where China is located according to the Chinese map;

s3, forecasting coordinates of the satellite points in real time according to the orbit of the satellite; determining a longitude strip by utilizing the longitude strip range of the coordinate of the sub-satellite point at S3; then, in the longitude strip, determining the relation between the coordinate of the substellar point and the upper limit and the lower limit of the geographical latitude, and forecasting whether the substellar point is on land or sea; and in the longitude strip, determining the relation between the coordinates of the subsatellite point and the upper limit and the lower limit of the Chinese geographical latitude, and forecasting whether the subsatellite point is in the Chinese environment.

In the method for forecasting the surface attribute of the sub-satellite based on the surface model map, in S1, the surface model map is preferably divided into a plurality of longitude strips at equal geographic longitude intervals.

In the method for predicting the surface attribute of the sub-satellite based on the surface model map, in S1, the surface model map is preferably divided into a plurality of longitude strips at equal intervals of not more than 1 °.

Preferably, in step S3, the relationship between the coordinate of the substellar point and the upper and lower geographic latitudes is determined in a certain longitude band, and the method for predicting whether the substellar point is located on land or in the sea includes:

correspondingly connecting one or more groups of upper geographic latitude limits and one or more groups of lower geographic latitude limits on two boundaries of the longitude strip to form one or more convex polygons; when the coordinates of the subsatellite point are positioned in any convex polygon, the earth surface attribute of the subsatellite point is forecasted to be land;

in a certain longitude strip, determining the relationship between the coordinates of the subsatellite point and the upper limit of Chinese geographical latitude and the lower limit of Chinese geographical latitude, and forecasting whether the subsatellite point is in Chinese environment or not comprises the following steps:

if two boundaries of the longitude strip are provided with upper Chinese geographical latitude limits and lower Chinese geographical latitude limits, one or more groups of upper Chinese geographical latitude limits are correspondingly connected, and one or more groups of lower Chinese geographical latitude limits are correspondingly connected to form one or more convex polygons; and when the coordinates of the subsatellite point are positioned in any convex polygon, forecasting the subsatellite point to be positioned in the Chinese environment.

Preferably, when the geographic latitude upper limit is correspondingly connected and the geographic latitude lower limit is correspondingly connected, linear interpolation is adopted to form one or more convex polygons; when the upper limit of the Chinese geographical latitude is correspondingly connected and the lower limit of the Chinese geographical latitude is correspondingly connected, linear interpolation is adopted to form one or more convex polygons.

Preferably, in the above method for forecasting the earth surface attribute of the sub-satellite based on the earth surface model map, the convex polygon is a trapezoid.

Preferably, in the method for forecasting the earth surface attribute of the sub-satellite based on the earth surface model map, the latitude range of the earth surface model map covers 90 ° of north latitude to 90 ° of south latitude.

In the above method for forecasting the earth surface attribute of the sub-satellite based on the earth surface model map, preferably, in S1, the earth surface model map is first divided into a plurality of longitude strips at equal geographic longitude intervals;

in S2, marking the upper geographic latitude limits and the lower geographic latitude limits of all the land areas on the boundary of each longitude strip according to the world land map, and correspondingly connecting one or more groups of upper geographic latitude limits and one or more groups of lower geographic latitude limits on the two boundaries of each longitude strip to form one or more land convex polygons; marking Chinese geographical latitude upper limits and Chinese geographical latitude lower limits on the boundaries of longitude strips where China is located according to a Chinese map, and correspondingly connecting one or more groups of Chinese geographical latitude upper limits and one or more groups of Chinese geographical latitude lower limits on two boundaries of each longitude strip where China is located to form one or more convex polygons in China;

when the number of the land convex polygons in the two adjacent longitude strips is equal and the number of the convex polygons in the Chinese world is equal, the land convex polygons in the two longitude strips share one edge in pairs, and the convex polygons in the Chinese world in the two longitude strips share one edge in pairs; each paired land convex polygon and each paired international convex polygon comprise 8 edges, except for 4 edges located on the boundary of each longitude strip, if the other 4 edges are intersected in two groups, and the included angle between the two intersected edges of each group is 179-181 degrees, returning to S1 to merge the two adjacent longitude strips into one longitude strip.

In the method for predicting the surface attribute of the sub-satellite based on the surface model map, in S1, before two adjacent longitude strips are merged, the surface model map is divided into a plurality of longitude strips at equal intervals of not more than 0.2 °.

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

(1) the method solves the problems that the storage capacity for storing DEM digital elevation model data is large, and the requirement of a search algorithm on software calculation is high;

(2) the method is a new method aiming at the function of forecasting the earth surface attribute of the sub-satellite points, and can give a high-precision forecasting result based on a high-precision earth surface model diagram, so that the autonomous mission planning capability of the spacecraft is greatly improved;

(3) the method can also adaptively adjust the width of the width stripes, reduce the number of the longitude stripes in a simple terrain area, keep the number of the longitude stripes in a complex terrain area, and improve the forecasting efficiency on the premise of improving the accuracy.

Drawings

FIG. 1 is a flow chart of the steps of the method of the present invention.

FIG. 2 is a schematic diagram of the method of the present invention.

FIG. 3 is a diagram illustrating the verification result of the method of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In order to ensure that a high-precision detection task is successfully realized, higher requirements are put forward on the attitude measurement and control capability of a satellite, a function of forecasting the earth surface attribute of an intersatellite point is put forward to a control subsystem in the normal flight process, and the earth surface attribute forecasting function requires forecasting of the intersatellite point internal or external, land or sea. A method for forecasting the earth surface attribute of the points under the satellite based on an earth surface model map includes such steps as pre-installing the earth surface model map, using longitude strips at intervals, and defining the upper and lower geographical latitudes of "domestic or terrestrial" in the strip region by each strip to simplify the algorithm for locating the earth surface on the satellite. And secondly, autonomously forecasting the geographical longitude L and the geographical latitude of the subsatellite point at the target time t on the satellite. Finally, performing indoor or outdoor forecast according to a pre-installed Chinese indoor map, and performing land or ocean forecast according to a pre-installed land map. The method solves the problems that the data storage capacity for storing the DEM digital elevation model is large, and the requirement of a search algorithm on software calculation is high, and the algorithm is already applied to the prediction of the earth surface attribute of the target time sub-satellite in the CM-1 satellite.

A method for forecasting the earth surface attribute of an interstellar point based on an earth surface model diagram is used for forecasting the earth surface attribute of the interstellar point on a satellite and comprises the following steps:

s1, establishing a terrain model diagram, wherein the terrain model diagram is divided into a plurality of longitude strips according to geographical longitudes, and the longitude intervals do not exceed 1 degree; the latitude range of the surface model map covers 90 degrees of north latitude to 90 degrees of south latitude;

s2, marking the upper geographic latitude limit and the lower geographic latitude limit of all the land areas on the boundary of each longitude strip according to the world land map; marking the upper limit of the Chinese geographical latitude and the lower limit of the Chinese geographical latitude on the boundary of the longitude strip where China is located according to the Chinese map;

s3, forecasting coordinates of the satellite points in real time according to the orbit of the satellite; determining a longitude strip by utilizing the longitude strip range of the coordinate of the sub-satellite point at S3; then, in the longitude strip, determining the relation between the coordinate of the substellar point and the upper limit and the lower limit of the geographical latitude, and forecasting whether the substellar point is on land or sea; and in the longitude strip, determining the relation between the coordinates of the subsatellite point and the upper limit and the lower limit of the Chinese geographical latitude, and forecasting whether the subsatellite point is in the Chinese environment.

In S3, in a certain longitude band, the relationship between the coordinates of the substellar point and the upper and lower geographic latitudes is determined, and the method for predicting whether the substellar point is on land or sea is:

correspondingly connecting one or more groups of upper geographic latitude limits and one or more groups of lower geographic latitude limits on two boundaries of the longitude strip to form one or more convex polygons; when the coordinates of the subsatellite point are positioned in any convex polygon, the earth surface attribute of the subsatellite point is forecasted to be land;

in a certain longitude strip, determining the relationship between the coordinates of the subsatellite point and the upper limit of Chinese geographical latitude and the lower limit of Chinese geographical latitude, and forecasting whether the subsatellite point is in Chinese environment or not comprises the following steps:

if two boundaries of the longitude strip are provided with upper Chinese geographical latitude limits and lower Chinese geographical latitude limits, one or more groups of upper Chinese geographical latitude limits are correspondingly connected, and one or more groups of lower Chinese geographical latitude limits are correspondingly connected to form one or more convex polygons; and when the coordinates of the subsatellite point are positioned in any convex polygon, forecasting the subsatellite point to be positioned in the Chinese environment. When the upper geographic latitude limit is correspondingly connected and the lower geographic latitude limit is correspondingly connected, linear interpolation is adopted to form one or more convex polygons; when the upper limit of the Chinese geographical latitude is correspondingly connected and the lower limit of the Chinese geographical latitude is correspondingly connected, linear interpolation is adopted to form one or more convex polygons. The convex polygon is a trapezoid.

In S1, the map may be divided into a plurality of longitude strips at equal geographic longitude intervals, or may be divided into a plurality of longitude strips at unequal geographic longitude intervals. The method for dividing the longitude strips into a plurality of longitude strips according to unequal geographical longitude intervals comprises the following steps:

the method comprises the steps of firstly dividing the longitude strips into a plurality of longitude strips according to equal geographic longitude intervals, namely dividing the longitude strips into a plurality of longitude strips by taking not more than 0.2 degrees as equal intervals. Then, in S2, marking the upper geographic latitude limit and the lower geographic latitude limit of all the land areas on the boundary of each longitude strip according to the world land map, and correspondingly connecting one or more groups of upper geographic latitude limits and one or more groups of lower geographic latitude limits on the two boundaries of each longitude strip to form one or more land convex polygons; marking the upper limit of Chinese geographical latitude and the lower limit of Chinese geographical latitude on the boundary of the longitude strip where China is located according to the Chinese map, and correspondingly connecting one or more groups of upper limits of Chinese geographical latitude and one or more groups of lower limits of Chinese geographical latitude on two boundaries of each longitude strip where China is located to form one or more convex polygons in China. When the number of the land convex polygons in the two adjacent longitude strips is equal and the number of the convex polygons in the Chinese world is equal, the land convex polygons in the two longitude strips share one edge in pairs, and the convex polygons in the Chinese world in the two longitude strips share one edge in pairs; each paired land convex polygon and each paired international convex polygon comprise 8 edges, except for 4 edges located on the boundary of each longitude strip, if the other 4 edges are intersected in two groups, and the included angle between the two intersected edges of each group is 179-181 degrees, returning to S1 to merge the two adjacent longitude strips into one longitude strip. The method is characterized in that two adjacent longitude strips are combined in a self-adaptive mode (the combination condition is that all earth surface attributes in the two adjacent longitude strips are connected, a land part is combined to belong to an integral land block, a Chinese interior part is combined to belong to an integral Chinese interior, and the combined earth surface attribute shape is basically consistent with that before combination), the number of the longitude strips can be reduced under the condition that the earth surface feature precision is guaranteed, the number of latitude upper and lower limits is greatly reduced, the data capacity of an earth surface model graph is reduced, the prediction speed is improved, and the prediction accuracy is kept.