Injection State Vector Estimation from Flight Data Analysis of a Spinning Apogee Stage

Abstract

In the present paper, a procedure is presented to estimate the injection state vector from the data of a single-axis velocity encoder and Horizon Crossing Sensors mounted on a spinning apogee stage together with Inertial Navigation System information at the separation of previous stage. The attitude information is obtained through a new global approach using only horizon crossing sensors. The inertial pitch angle is obtained from local pitch angle history by separating the low frequency component due to translational motion. The yaw angle is derived from the pattern of dynamical coupling of the pitch and yaw motions in frequency domain. The attitude information is combined with the output of a single axis velocity encoder and trajectory information is generated. The test results obtained from present approach are com-pared with a dynamics simulator and it is established that the injection point can be estimated with an accuracy sufficient for preliminary orbit determination.