# Way to clarify the parameters of the motion of the center of mass of the spacecraft

(57) Abstract:

The invention relates to the field of space navigation, in particular for systems of Autonomous navigation. Measure the altitude above the surface of the planet. Perform cyclic calculation of Zenith distances of two stars on the basis of measurements of the angles of orientation of the SPACECRAFT and orientation of the optical axes Astrovirus device relative to the associated coordinate system. Define the navigation settings AC in static processing measurement information for measuring the plot. In each cycle additionally verify the orientation angles of the SPACECRAFT. Based on the updated values of the angles and the orientation of the optical axes Astrovirus devices specify the values of the Zenith distances of the stars. Use more accurate values when solving the navigation task in the current period. Improved the accuracy of the navigation of SPACECRAFT parameters. 1 Il. The proposed invention relates to the field of space navigation, in particular, to methods for Autonomous navigation of SPACECRAFT.Known methods of Autonomous navigation [1-3], based on measuring Zenith distances of 2 stars and the angular diameter of the planet or on the measurement sopralene a star.Attracting excessive primary navigation information obtained from measurements on one or more measuring stations, a priori data about its statistical characteristics in the subsequent statistical processing this information using on-Board digital computer (computer) allows estimation of the vector defined navigation parameters. The General lack of navigation tasks using the following methods Autonomous navigation is the low accuracy of determination of parameters of the motion of the center of mass of the SPACECRAFT, due to instrumental and methodological errors of onboard navigation measurements, under-registration in the navigation algorithms forces actually acting on the SPACECRAFT in flight, the errors of the physical constants that determine the law of motion, errors account on the computer, etc.Closest to the proposed composition of the navigation measurement is a method for determining motion parameters of the center of mass of the SPACECRAFT [4], which consists in measuring Zenith distances of 2 stars and a flying height above the surface of the planet, when aggregated this information to determine the parameters of motion of the center of mass of the SPACECRAFT. Ismtii vertical radioterminal-altimeter (RVV). The main stars are determined by two astrovision devices (AVA). The disadvantage of this method is the low accuracy on the basis of parameters of the motion of the center of mass of the SPACECRAFT.Found that of the above reasons error solution navigation parameters the most weight are the errors of the onboard measurements, and in particular, to a considerable extent, the accuracy of determining the parameters of motion of the center of mass of the SPACECRAFT depends on the accuracy of measuring Zenith distances of the stars. Analysis of existing measurement tools shows that the basic error in their determination makes used to measure the angles of deflection of the vertical axis of the SPACECRAFT from the local geographic vertical RVV [3]. These angles are the angles of orientation of the SPACECRAFT pitch and roll.The aim of the invention is to improve the accuracy of navigation Autonomous navigation of SPACECRAFT.This goal is achieved by the organization (after solving the navigation task in a known manner) in the framework of the 2nd phase of the cyclic solution to the problem of determining the orientation of the SPACECRAFT by the stars using the previously obtained parameters of price movements), and navigation tasks for these specified values.The invention consists in the following. Using the information on the orientation of the optical axes AVA relative to the associated coordinate system, the knowledge of the guides of the cosines vizireanu stars in the geocentric Equatorial coordinate system, and the parameters of motion of the center of mass of the SPACECRAFT can solve the problem of determining the angles of deflection of the associated coordinate system, relative to the movable orbital coordinate system, i.e. the problem of determining the orientation.Obviously, using more accurate values of the angles of orientation of the SPACECRAFT for the formation of the adjusted values of Zenith distances of stars and solving them navigation task in the next step, for a certain number of cycles of sequential decision task orientation and navigation, you can improve the accuracy of the navigation parameters.The drawing shows a functional diagram of the proposed method for refining the parameters of the motion of the SPACECRAFT.The algorithm for solving navigation tasks using the proposed method consists in the following. At the 1st stage is solved the navigation problem [2], the initial data for which ablauts>RVVand_{RVV}(these data are calculated Zenith distance according to the expression = arccos[coscos(-)+sinsin]), and the height H of the flight SPACECRAFT above the Earth's surface, measured at the current time measured interval;

nominal values of the parameters of the motion of the SPACECRAFT in the initial moment of time;

the covariance matrix of the measurement errors TO

_{d}.The result of statistical processing of all this information by using the method of least squares is determined corrections calculated according to expression

q = (W

^{T}K

_{d}W)

^{-1}W

^{T}K

_{d}d,

where W is the matrix of partial derivatives of the measured parameters defined by the parameters vector of the navigation parameters

d - vector of deviations of the measured parameters from the calculated values.Adding these corrections to the nominal values of the motion parameters for a certain number of iterations is formed vector navigation parameters qAt the 2nd stage of collaborative problem solving navigation and attitude determination algorithm is divided into cycles of consecutive executions of the modes of orientation and navigation.In each cycle the solution to the problem of determining the orientation occurs when the tasks orientation by the stars is based on the existence of a functional dependence of the angles of orientation of the SPACECRAFT from the orientation angles of the optical axes of AVA in the mobile-orbital system of coordinates and parameters of movement of the center of mass of the SPACECRAFT [5].The essence of collaborative problem solving navigation and attitude determination is that the measured orientation angles of the optical axes of AVA and calculated their true values, which are obtained at the previous step, the coordinates of the center of mass of the SPACECRAFT is calculated orientation angles

_{p}and

_{p}. For more accurate values of the orientation angles are calculated the adjusted values of the Zenith distances of the stars, which are then used when solving the navigation task in the next step. Cyclic solution of the problems of navigation and attitude determination is repeated several times until such time as amendments to the defined vector navigation parameters will be less than the threshold.Thus, the proposed method for Autonomous navigation can improve the accuracy of determining the parameters of motion of the center of mass of the SPACECRAFT through the use when solving navigation tasks more precise measurements of primary navigation options - Zenith distances of the stars.The list of used literature

1. A. P. Razygraev. The basics of flight control space flights. - M.: Mechanical Engineering, 1990.2. In. A. Smirnov, A. A., KASKO, Y. P. Makovetsky. Fundamentals of AB is impressive. Analytical assessment of the accuracy of the offline methods of orbit determination. - M.: Mechanical Engineering, 1987.4. Mathematical and software systems Autonomous navigation KA "amber". - M.: the USSR Ministry of defense, 1986.5. C. I. Kochetkov. System of astronomical orientation of the spacecraft. - M.: Mechanical Engineering, 1980. Way to clarify the parameters of the motion of the center of mass of the SPACECRAFT, which consists in measuring the altitude above the surface of the planet, cyclic calculation of Zenith distances of two stars on the basis of measurements of the angles of orientation of the SPACECRAFT and orientation of the optical axes Astrovirus devices (AVA) relative to the associated coordinate system and the definition of the navigation of SPACECRAFT parameters in static processing measurement data for measuring area, characterized in that in each cycle additionally verify, using a sample measurement vector navigation parameters obtained in the previous cycle, the angles of orientation of the SPACECRAFT and on the basis of the adjusted values of these angles and information about a specified orientation of the optical axes AVA specify the values of the Zenith distances of the stars used in the solution of the navigation problem in the current cycle.

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