A retrospective calculation method for rocket launch point parameters

Abstract

The present invention discloses a method for retrospective calculation of rocket launch point parameters, comprising the following steps: step 1, calculating the observation vector from the satellite to the rocket target in the J2000 inertial coordinate system through the rocket target data observed by the satellite; step 2, calculating the linear equation of the observation vector in the J2000.0 inertial coordinate system; step 3, calculating the position vector of the rocket target in the earth-fixed coordinate system using radar external measurement data; step 4, calculating the plane equation of the launch orbit surface in the J2000.0 inertial coordinate system; step 5, calculating the coordinates of the rocket launch point by combining the plane equation of the launch orbit surface and the linear equation of the observation vector; step 6, calculating the longitude and latitude parameters of the rocket launch point in the earth-fixed coordinate system. The present invention discloses a method for retrospective calculation of rocket launch point parameters, which is aimed at measuring the active segment of the rocket in a non-cooperative manner based on the ground and the sky, and quickly determining the calculation problem of the launch point parameters with high precision, showing accuracy and effectiveness.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace measurement and control methods, and in particular relates to a backtracking calculation method for rocket launch point parameters. Background Art

[0002] Rockets are usually launched vertically. After a few seconds of vertical ascent, the rocket performs an attitude turn maneuver to enter the ballistic operation stage, and the launch orbit plane remains unchanged for a certain period of time. In order to provide important support for subsequent tasks and decision-making, it is very necessary to quickly and accurately calculate the parameters of the rocket launch point. Ground-based radar measurement data can usually be tracked for a considerable period of time after launch, and there is a large delay with the launch time, and the error of the rocket launch point parameters is large when back-calculating; at the same time, the satellite can detect the target in a short time after the rocket is launched by infrared means, but the calculation of the launch point parameters based only on the starting point observation vector requires the assumption of a priori flight altitude, and its calculation error is unavoidable. The present invention combines the observation data of the ground and the earth to calculate the parameters of the rocket launch point quickly and with high precision. Summary of the invention

[0003] The purpose of the present invention is to provide a method for back-calculating rocket launch point parameters, which solves the problem that the rocket launch point parameters obtained by the existing method have large errors.

[0004] The technical solution adopted by the present invention is: a method for backtracking calculation of rocket launch point parameters, comprising the following steps:

[0005] Step 1: Calculate the observation vector from the satellite to the rocket target in the J2000 inertial coordinate system using the rocket target data observed by the satellite;

[0006] Step 2: Calculate the linear equation of the observation vector in the J2000.0 inertial coordinate system;

[0007] Step 3: Calculate the position vector of the rocket target in the ground-fixed coordinate system using the radar external measurement data;

[0008] Step 4, calculate the plane equation of the launch orbital plane in the J2000.0 inertial coordinate system;

[0009] Step 5, calculate the coordinates of the rocket launch point by combining the plane equation of the launch orbit plane and the straight line equation of the observation vector;

[0010] Step 6: Calculate the longitude and latitude parameters of the rocket launch point in the Earth-fixed coordinate system.

[0011] The present invention is also characterized in that:

[0012] The observation vector from the satellite to the rocket target in the J2000 inertial coordinate system calculated in step 1 is expressed as follows:

[0013]

[0014] In formula (1), the subscript c represents the satellite observation camera coordinate system, M c2b is the transformation matrix from the observation camera coordinate system to the star coordinate system, M b2j2000 is the transformation matrix from the stellar coordinate system to the J2000.0 inertial coordinate system.

[0015] Step 2 is as follows: Assume that the vector unit of the observation direction from the satellite to the launch point at the starting time is [LMN] T , the satellite fixed position is [x sat y sat z sat ] T , then the linear equation of the observation vector in the J2000.0 inertial coordinate system is expressed as follows:

[0016]

[0017] Step 3 is as follows: Assume that the observed values ​​in the spherical coordinate system of the station's horizontal coordinate system are the distance, elevation angle, and azimuth angle ρ k ,E k ,A k , then the rocket target is expressed in the earth-fixed coordinate system as follows:

[0018]

[0019] In formula (3), R is the coordinate of the measuring station, M is the transformation matrix from the measuring station horizontal coordinate system to the earth-fixed coordinate system, and P is the transformation matrix from the earth-fixed coordinate system to the J2000 inertial coordinate system.

[0020] Step 4 is as follows: Assume that the radar measurement data in the J2000.0 inertial coordinate system is converted to the coordinates of any two points on the launch orbit plane as X1 = [x1 y1 z1] T and X2 = [x2 y2 z2] T , and the launch orbit plane contains the origin of the earth's center, then the plane equation of the launch orbit plane in the J2000.0 inertial coordinate system is described as follows:

[0021] Ax+By+Cz=0 (4)

[0022] In formula (5), n = [ABC] T The unit normal vector of the launch orbit plane is the cross product of the coordinate vectors of any two points on the plane, that is,

[0023]

[0024] Step 5 is as follows: By solving equations (2) and (4) together, the rocket launch point parameters in the J2000.0 inertial coordinate system can be expressed as follows:

[0025]

[0026] In formula (6),

[0027] The beneficial effects of the present invention are as follows: the present invention provides a backtracking calculation method for rocket launch point parameters, which measures the active segment of the rocket in a non-cooperative manner based on the ground and the sky, and can quickly determine the calculation problem of the launch point parameters with high precision, showing accuracy and effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a full-view schematic diagram of the launch process of a space-based exploration rocket;

[0029] Figure 2 It is a side view schematic diagram of the launch process of a space-based exploration rocket;

[0030] Figure 3 The present invention is a flowchart of a method for backtracking calculation of rocket launch point parameters. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] 1. Basic coordinates definition

[0033]

[0034] The geodetic coordinate system is based on the earth's reference ellipsoid and is usually expressed in geodetic latitude, geodetic longitude, and geodetic height (B, L, H).

[0035] 2. Basic Methods

[0036] (1) A satellite can generally detect a target quickly after a rocket is launched. At this time, the rocket is in the vertical ascent phase immediately after launch and has not made a programmed turn or has traveled very little in the direction of the track. The first point detected by the satellite should be above the launch point, and its latitude and longitude coordinates should be basically the same as those of the launch point.

[0037] (2) The launch process of the rocket generally keeps the launch orbit plane unchanged in the J2000.0 geocentric inertial coordinate system. The launch orbit plane of the geocentric inertial coordinate system can be determined by the positions of any two points on the trajectory and the center of the earth measured by the ground-based radar. The trajectory data obtained by multi-point radar measurement can improve the accuracy of the launch orbit plane through smoothing filtering.

[0038] (3) Based on the observation vector equation from the satellite to the observation target at the starting time obtained by the satellite and the launch orbit plane equation obtained by radar measurement, a set of equations is established to obtain the coordinates of the intersection of the satellite line of sight and the launch orbit plane in the geocentric inertial coordinate system, and then convert them to the earth-fixed coordinate system to calculate the longitude and latitude.

[0039] The launch process of the space-based exploration rocket is as follows Figure 1 and Figure 2 shown.

[0040] 3. Technical Solution

[0041] The present invention provides a method for backtracking calculation of rocket launch point parameters, such as Figure 3 As shown, including:

[0042] Step 1: Calculate the observation vector from the satellite to the rocket target in the J2000 inertial coordinate system using the rocket target data observed by the satellite

[0043] Step 1 reads the observation vector data of the rocket target in the satellite camera coordinate system;

[0044] Step 2 calculates the unit vector of the rocket target in the satellite body coordinate system;

[0045] Step 3 calculates the observation vector from the satellite to the rocket target in the J2000 inertial coordinate system;

[0046] Step 2: Calculate the normal direction vector of the launch orbit plane through ground radar observation data

[0047] Step 1 Read the radar station site, coordinate file and rocket target observation data;

[0048] Step 2 calculates the position vector of the rocket target in the horizontal coordinate system of the measuring station;

[0049] Step 3 calculates the position vector of the rocket target in the ground-fixed coordinate system;

[0050] Step 4 Calculate the position vector of the rocket target in the J2000 inertial coordinate system;

[0051] Step 5 Use the cross product of the position vectors at any two moments in the J2000 inertial coordinate system to solve the normal direction vector of the launch orbital plane;

[0052] Step 3: Combine the results of the first two steps to solve the rocket target launch point parameters

[0053] Step 1 Combine the observation vector and the launch orbit plane equation in the J2000 inertial coordinate system to solve the launch point parameters;

[0054] Step 2 calculates the parameters of the rocket launch point in the earth-fixed coordinate system;

[0055] Simulation example:

[0056] By using simulation data of a real-time monitoring mission of a rocket launch and adopting the calculation method of combining ground-based single radar detection data and satellite observation vector provided by the present invention, rapid and accurate estimation of launch point parameters can be achieved.

[0057] Table 1 Simulation object parameters

[0058]

[0059] Step 1: The sight direction vector of a rocket target in the J2000.0 coordinate system of the satellite observation camera is:

[0060]

[0061] Step 2: Select the azimuth, elevation and distance observation data of the radar at two moments in the ground-fixed coordinate system:

[0062] Time t1: 43.789769 degrees 6.511051 degrees 382624.129 meters

[0063] Time t2: 47.619171 degrees 11.018595 degrees 367428.361 meters

[0064] The normal direction vector of the launch orbit plane can be obtained as:

[0065]

[0066] Step 3: Unite and The longitude, latitude and altitude of the rocket target launch point are calculated to be 40.0 degrees, 125.0 degrees and 999.9 meters. The simulation results of the rocket launch point are consistent with the theoretical values, showing the accuracy and effectiveness of the calculation method of the present invention.

Claims

1. A method for backtracking calculation of rocket launch point parameters, characterized in that: The following steps are involved: Step 1: Calculate the observation vector from the satellite to the rocket target in the J2000 inertial coordinate system using the rocket target data observed by the satellite; Step 2: Calculate the linear equation of the observation vector in the J2000.0 inertial coordinate system; Step 3: Calculate the position vector of the rocket target in the ground-fixed coordinate system using the radar external measurement data; Step 4, calculate the plane equation of the launch orbital plane in the J2000.0 inertial coordinate system; Step 5: Calculate the coordinates of the rocket launch point by combining the plane equation of the launch orbit plane and the straight line equation of the observation vector; specifically: Assume that the vector unit of the observation direction from the satellite to the launch point at the starting time is , the satellite fixed position is , then the linear equation of the observation vector in the J2000.0 inertial coordinate system is expressed as follows: （2） Assume that the radar measurement data in the J2000.0 inertial coordinate system are converted to the coordinates of any two points on the launch orbit plane: and , and the launch orbit plane contains the origin of the earth's center, then the plane equation of the launch orbit plane in the J2000.0 inertial coordinate system is described as follows: （4） In formula (5), The unit normal vector of the launch orbit plane is the cross product of the coordinate vectors of any two points on the plane, that is, （5） By solving formulas (2) and (4) together, the parameters of the rocket launch point in the J2000.0 inertial coordinate system can be expressed as follows: （6） In formula (6), ; Step 6: Calculate the longitude and latitude parameters of the rocket launch point in the Earth-fixed coordinate system.

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