Aerospace Instrument-Making Annotation << Back AN ATTITUDE ESTIMATION ALGORITHM FOR WSO – UV SPACECRAFT PRECISION POINTING MODE OF OPERATION A.N. Ivonin, R.A. Kamaldinova, S.N. Morgunova, V.N. Sokolov, I.V. Solovyev, M.A. Shatskiy An attitude estimation algorithm is presented designed to provide the WSO – UV spacecraft attitude and orbit control system (AOCS) with attitude information in precision pointing mode of operation. During this mode AOCS must support space telescope T-170M pointing at the observed object and its constant three-axis orientation with respect to inertial space. Deviation of the optical axis from predetermined direction must not exceed ±0.1'' (3σ) while angular rate of rotation must not exceed ±2·10–5 /s. The presented algorithm combines the measurements of the system of guide star sensors and of the Astrix 200 inertial measurement unit and forms the estimates of attitude quaternion, angular rate vector and vector of gyros biases. The estimated process being almost stationary, the information fusion is accomplished by Wiener Filter with constant gain matrix. The gain matrix elements are determined through simulation of optimal Kalman Filter performance. In order to make all linear combinations of gyros errors observable a null-space measurement is used. Test results obtained with the use of mathematical simulation tools indicate that the requirements concerning the space telescope pointing accuracy and its stabilization are guaranteed to be met. Keywords: gyroscopes; information fusion; space telescope; attitude; stabilization; pointing. DOI: 10.25791/aviakosmos.12.2020.1192 Pp. 13-25.