AAS 97-611
RANGE LIMITS OF ATTITUDE DETERMINATION ACCURACY
D. Mortari - Universita degli Studi "La Sapienaz" di Roma, Italy
Abstract
This paper quantifies the error associated with the optimal attitude estimation based on vectors observation and identifies the limit conditions for the input unit-vectors which assure the attitude error be less than a given requested value. The error is originated by the observed vectors spatial distribution and accuracies. When n=2 vectors are available the attitude error is analytically evaluated and the "quasi-parallel limit condition" is defined. When n>2, some parameters indicating the error are shown. The paper then establishes which are the known optimal attitude estimation algorithms for which the approaching of a quasi-parallel limit condition can be detected. These parameters indicate the reliability of the attitude estimation and can be used, as weights, to improve the attitude estimation evaluated by statistical filtering.