CN-118859175-B - Method for acquiring satellite laser time sequence pointing

CN118859175BCN 118859175 BCN118859175 BCN 118859175BCN-118859175-B

Abstract

The invention discloses a method for acquiring satellite laser time sequence pointing, which acquires satellite point tracks and foot point tracks through six pieces of information of satellite orbits, completes calculation of satellite continuous laser pointing by combining an elevation database, greatly simplifies the calculation process of laser pointing and improves the simulation calculation rate.

Inventors

JIAN CHAOCHAO
XU XIANGCHEN
WU XIN
WANG YUCHENG
SUN HAO
LI JINZE

Assignees

西安电子科技大学

Dates

Publication Date: 20260505
Application Date: 20240703

Claims (7)

1. The method for acquiring the satellite laser time sequence pointing is characterized by comprising the following steps of: step 1, acquiring six-number information of different satellite orbits at different times, wherein the six-number information of the satellite orbits comprises an orbit inclination angle The right ascent and descent points Eccentricity of track Amplitude angle of near-spot Angle of plane and near point The circle number of the earth is wound every day ; Step 2, calculating the geocentric earth fixed coordinate system of the satellite orbit at the current t moment based on six-root information of the satellite orbit ; Step 3, according to the earth long half shaft And the earth's short half axle Calculating earth's flatness ; Step 4, according to the geocentric geodetic coordinates of the satellite orbit in the step 2 And earth's flatness in step 3 Calculating the coordinates of the track of the satellite point below the satellite at the current t moment Satellite under-satellite point track coordinates Longitude by satellite Latitude and longitude A representation; step 5, passing through the satellite under-satellite point track coordinates in step 4 Calculating six foot point offset distances of the satellite, each foot point offset distance comprising a foot point longitude offset distance Offset distance from foot point latitude ; Step 6, respectively calculating longitude and latitude coordinates of the six foot points according to the six foot point offset distances obtained in the step 5 ; Step 7, the longitude and latitude coordinates of six foot points at the current t moment are calculated Inputting the elevation database, and inquiring the elevation under the longitude and latitude of the corresponding foot point Through the elevation under the longitude and latitude of the corresponding inquired foot point Calculating the geocentric and geodetic coordinates of the corresponding foot points ; Step 8, according to the earth-centered earth-fixed coordinates of the satellite foot point at the current t moment in the step7 Geodetic coordinates with the satellite in step3 Calculating laser pointing direction of satellite foot point at current t moment 。
2. The method for acquiring the satellite laser time sequence pointing according to claim 1, wherein in the step 2, the earth-centered earth-fixed coordinate system of the satellite orbit at the current time t is The specific calculation process of (2) is as follows: according to the number of turns around the earth per day Calculating the semi-long axis of the track The expression is as follows: Wherein, the Is the gravitational constant, the value is ; The angle of the closest point in the six-root information according to the satellite orbit And track eccentricity Calculating the angle of the closest point The expression is as follows: Based on the orbital eccentricity in six-root information of satellite orbits And a near point angle Calculating true near point angle The expression is as follows: Based on six-root information and true near point angle Calculating the geocentric and geodetic coordinates of the satellite orbit at the current t moment The expression is as follows: Wherein, the In order to achieve the eccentricity of the track, For a true angle of the near point, Is a semi-long axis of the track, For the inclination angle of the track, In order to raise the right-hand meridian of the intersection point, Is the near-place argument.
3. The method for acquiring satellite laser timing and directing according to claim 1, the method is characterized in that the satellite point track coordinates of the satellite at the current t moment in the step 4 The specific calculation process of (2) is as follows: Fixing the geocentric ground coordinates of the satellite orbit in the step 2 Projected onto the z plane and then based on the geodetic coordinates of the satellite at the current time t Respectively calculating the distance from the satellite to the earth center at the current t moment Longitude of satellite And latitude of The expressions are as follows: Calculating the latitude of the satellite by an iterative method The expression is as follows: Wherein, the The initial latitude value of the satellite at the current t moment, For satellite iteration at the current t moment The next latitude value is used to determine, For satellite iteration at the current t moment The latitude value after the times can obtain the accurate latitude value of the satellite after a certain iteration times As the latitude of the satellite at the current time t N represents a conversion process coefficient; The expression of the conversion process coefficient N is as follows: Wherein, the The earth's flatness is represented by the earth's flatness, Representing the long half-axis of the earth, For satellite iteration at the current t moment Secondary latitude values.
4. The method for acquiring the satellite laser time sequence pointing according to claim 1, wherein the specific calculation process of the six-pin point offset distance of the satellite in the step 5 is as follows: satellite-based point trajectory coordinates through satellites Calculating the speed direction of the satellite in terms of longitude and latitude at the current t moment The expression is as follows: Wherein, the Representing the coordinates of the track of the satellite's point under the current t+1 moment, Representing the coordinates of the satellite's point track under the satellite at the current t moment, A time interval representing the satellite orbit; According to the speed direction of the satellite taking longitude and latitude as a unit at the current t moment Horizontal displacement of satellite orbit And displacement in the vertical direction Calculating six foot point offset distances of satellite scanning according to the geometric position relation of the satellite motion track and six foot points, wherein each foot point offset distance comprises a foot point longitude offset distance Offset distance from foot point latitude The expression is as follows: Wherein, the Velocity vector representing satellite The component in the latitude of the person, Representing velocity vectors The component in terms of longitude and latitude, Is a velocity vector Is of a size of (2); representing the horizontal distance between two adjacent strong pulses or two weak pulses of a satellite scan respectively, Representing the vertical distance between a strong pulse and a weak pulse of a satellite scan, The satellite is scanned for horizontal distances between strong and weak pulses.
5. The method for acquiring satellite laser time sequence pointing according to claim 1, wherein the longitude and latitude coordinates of the six foot points in step 6 The specific calculation process of (2) is as follows: Calculating the longitude offset of six foot points relative to the satellite according to the six foot point offset distances obtained in the step 5 And six foot point latitude offsets relative to the satellite's undersea point The expression is as follows: Wherein, the Is the latitude offset distance of the foot point, Is the foot point longitude offset distance, Is the latitude value of the satellite under-satellite point at the current t moment; Based on the longitude offset of six foot points relative to the satellite's undersea point And six foot point latitude offsets relative to the satellite's undersea point Respectively calculating longitude and latitude coordinates of six foot points at current t moment (I=1, 2,3,4,5, 6) as follows: 。
6. The method for acquiring satellite laser time sequence pointing according to claim 1, wherein the geocentric-earth coordinates of the corresponding foot point in step 7 The expression of (2) is as follows: where N represents the conversion process coefficient, derived from the geometric formula, And The longitude and latitude values of the satellite foot point at the current t moment are respectively, The elevation of the satellite foot point at the current t moment.
7. The method for acquiring satellite laser time sequence pointing according to claim 1, wherein in the step 8, the laser pointing of the satellite foot point at the current time t is performed The specific expression of (2) is as follows: Wherein, the Representing the geodetic coordinates of the satellite at the current time t, And the geocentric-geodesic coordinates of the satellite foot point at the current t moment are shown.

Description

Method for acquiring satellite laser time sequence pointing Technical Field The invention belongs to the technical field of satellite laser time sequence pointing, and particularly relates to a method for acquiring satellite laser time sequence pointing. Background In the geometric positioning of a satellite-borne laser altimeter and laser radar simulation, the precision of a laser pointing angle is critical to positioning and calculation results. Currently, the on-orbit acquisition method of the laser pointing angle of the satellite-borne laser altimeter mainly comprises a ground detector acquisition method and an on-board infrared camera imaging acquisition method, but the methods have the problems of high cost and low success rate. Therefore, the research on the efficient on-orbit laser pointing angle acquisition method has important significance for improving mapping precision. The Chinese patent publication No. CN110646782B discloses an on-orbit pointing calibration method of satellite-borne laser based on waveform matching, which comprises the steps of simulating echo waveforms of the satellite-borne laser altimeter based on airborne lidar data, matching real waveforms according to the obtained simulated waveforms, determining the centroid coordinates of satellite-borne laser foot points according to the method of matching the real waveforms with the simulated waveforms, and calibrating the pointing angles of the satellite-borne laser according to the geometric calibration model of the satellite-borne laser altimeter and the centroid coordinates of the laser foot points. The above-mentioned simulated laser pointing angle has the following disadvantages: the method requires high-quality airborne LiDAR data to carry out waveform simulation, and the data is high in acquisition and processing cost and not easy to obtain. The method has high calculation complexity, namely the step involves multiple waveform simulation and matching, a large amount of calculation resources and time are needed for carrying out layer-by-layer search and surface fitting, the calculation complexity is high, and the requirement of time sequence simulation cannot be met. Disclosure of Invention In order to overcome the defects in the prior art, the invention aims to provide the method for acquiring the satellite laser time sequence pointing, which acquires the satellite point track and the foot point track through six pieces of information of a satellite orbit, completes the calculation of the satellite continuous laser pointing by combining an elevation database, greatly simplifies the calculation process of the laser pointing and improves the simulation calculation rate, uses the input which does not relate to complex parameters such as a laser attitude angle, only needs to input TLE calendar and elevation data, has low requirement on the functional configuration of scene simulation software, and has low calculation cost. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: A method for acquiring satellite laser time sequence pointing comprises the following steps: step 1, acquiring six-number information of different satellite orbits at different times, wherein the six-number information of the satellite orbits comprises an orbit inclination angle The right ascent and descent pointsEccentricity of trackAmplitude angle of near-spotAngle of plane and near pointThe circle number of the earth is wound every day; Step 2, calculating the geocentric earth fixed coordinate system of the satellite orbit at the current t moment based on six-root information of the satellite orbit; Step 3, according to the earth long half shaftAnd the earth's short half axleCalculating earth's flatness; Step 4, according to the geocentric geodetic coordinates of the satellite orbit in the step 2And earth's flatness in step 3Calculating the coordinates of the track of the satellite point below the satellite at the current t momentSatellite under-satellite point track coordinatesLongitude by satelliteLatitude and longitudeA representation; step 5, passing through the satellite under-satellite point track coordinates in step 4 Calculating six foot point offset distances of the satellite, each foot point offset distance comprising a foot point longitude offset distanceOffset distance from foot point latitude; Step 6, respectively calculating longitude and latitude coordinates of the six foot points according to the six foot point offset distances obtained in the step 5; Step 7, the longitude and latitude coordinates of six foot points at the current t moment are calculatedInputting the elevation database, and inquiring the elevation under the longitude and latitude of the corresponding foot pointThrough the elevation under the longitude and latitude of the corresponding inquired foot pointCalculating the geocentric and geodetic coordinates of the corresponding foot points; Step 8, according to the earth-centered