IDENTIFICATION OF A SPATIAL MOTION OF A SPACECRAFT  BY  THE  TELEMETRY DATA

M.V. Levskii

The Research institute of Space systems , Khrunichev State research and production Space Center

Tihonravov street, 27, Jubilejny, Moscow region, 141092, Russia

This present article decide the problem of identification by the data of onboard measurements of a true angular motion of spacecraft (on an example of the DM-SL accelerating unit) at fulfilment by it of spatial turns and definition of principal numerical characteristics of this motion. The DM-SL accelerating unit (AU) is an orbital stage of the space rocket “Zenit-3SL”, it includes in a structure of the “Sea Launch” space-rocket complex (from the “Sea Launch” programme). The basic means of the mathematical processing of onboard measurements of parameters of spacecraft motion in a mode of spatial turn are uncovered briefly. Then, the results of post-flight processing of the telemetry information obtained during controlled turns of the Dm-SL at the ascent of satellites on a target transfer orbits within the framework of the international program Sea Launch are presented and analyzed.

Dm-SL spatial turns for the first time realised. Earlier the change of an angular location of upper stage (US) was implemented by series turns around unit bound axes. Demanded motion was provided with orientation control engines of Dm-SL.

The identification of DM-SL spatial motion was conducted by the data of the digital information reshaped motion control system and navigating (MCSN). Direct measurements of angular coordinates on a pitch, yaw, roll were used for definition of nominal motion of the DM-SL unit. The values of absolute angular velocity vector  were calculated for a capability of exact selection of model of DM-SL motion during spatial turn only.

The result of the processing was precise identification of motion and control method of turn for spatial reorientation manoeuvre, and definition of numerical values of parameters of a control algorithm by motion of DM-SL in a mode of programmed turn also. The method of teachable models was applied to processing, within the framework of which one the measurements executed on some finite interval of time, are treated jointly by least squares method and integrating of equations of station turn control algorithm. Thus the main specifications of algorithms of control system are determined, and the initial conditions of motion are updated. As the result of the processing the nominal Dm-SL motion relative to the center of mass is renovated during turns. The absolute conformity of the telemetry measurements to motion of Dm-SL unit according to known control means of turn (the patent for the invention of Russian Federation №  2093433) is shown.

At the solution of the identification problem the new variables such are entered, that they were slowly varying functions of time. The recovery of nominal motion was made from the data of telemetry measurements during controlled turn of DM-SL unit, this is a feature also. Resting only on angular parameters of motion it was possible completely to restore a having place DM-SL motion (both actual, and nominal also) during spatial turns. Having conducted indispensable count of functional connections of variation of pitch j(t), yaw y(t), roll g(t) angles in a function of angular velocity (t) in projections to bound DM-SL axes  w_x(t) , w_y(t) , w_z(t) , having compared last with behavior of angular velocity at control of turn on a known method and having compared outcomes of matching with the technical norms and standards accepted in practice generally, and tolerances, have received convincing endorsement of the fact, that the utilised method of turn control was used on DM­­-SL board.

The designed methodical and algorithmic tools enable to determine numerical values of parameters of a control algorithm by turn with large accuracy.