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Angular-Rate Estimation using Star Tracker MeasurementsThis paper presents algorithms for estimating the angular-rate vector of satellites using quaternion measurements. Two approaches are compared, one that uses differentiated quaternion measurements to yield coarse rate measurements which are then fed into two different estimators. In the other approach the raw quaternion measurements themselves are fed directly into the two estimators. The two estimators rely on the ability to decompose the non-linear rate dependent part of the rotational dynamics equation of a rigid body into a product of an angular-rate dependent matrix and the angular-rate vector itself. This decomposition, which is not unique, enables the treatment of the nonlinear spacecraft dynamics model as a linear one and, consequently, the application of a Pseudo-Linear Kalman Filter (PSELIKA). It also enables the application of a special Kalman filter which is based on the use of the solution of the State Dependent Algebraic Riccati Equation (SDARE) in order to compute the Kalman gain matrix and thus eliminates the need to propagate and update the filter covariance matrix. The replacement of the elaborate rotational dynamics by a simple first order Markov model is also examined. In this paper a special consideration is given to the problem of delayed quaternion measurements. Two solutions to this problem are suggested and tested. Real Rossi X-Ray Timing Explorer (RXTE) data is used to test these algorithms, and results of these tests are presented.
Document ID
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Azor, R.
(Israel Aircraft Industries Ltd. Yehud, Israel)
Bar-Itzhack, Itzhack Y.
(Technion - Israel Inst. of Tech. Haifa, Israel)
Deutschmann, Julie K.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Harman, Richard R.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
August 19, 2013
Publication Date
May 1, 1999
Publication Information
Publication: 1999 Flight Mechanics Symposium
Subject Category
Distribution Limits
Work of the US Gov. Public Use Permitted.
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