AAS 97-606
ON COORDINATE SELECTION AND COVARIANCE ESTIMATION IN ORBIT DETERMINATION
J.L. Junkins, M.R. Akella and K.T. Alfriend - Texas A&M University
Abstract
The choice of coordinates forms a very important aspect in the study and analysis of dynamical systems. Given a physical system, certain sets of coordinates yield near linear differential equations while others lead to highly nonlinear systems containing singularities. Extending previous work we discuss first in this paper the role of coordinates choice in an orbit determination problem. The system we discuss includes the dominant earth oblateness (J2) and the effects of atmospheric drag. The state vector is augmented with atmospheric drag and the Extended Kalman filter is used to compare the covariance predictions in rectangular coordinates and polar coordinates.