Refinining the Drift Model of a Strapdown ESG for Orbital Spacecraft

Abstract

Refinement of the electrostatic gyroscope (ESG) drift model aboard an orbital maneuverable satellite for remote sensing of the Earth’s surface is considered. Some changes of the drift model also hold for the ESG ground-based applications. The paper also analyzes the quasi-continuous correction mode of the ESG-based strapdown inertial attitude reference system (SIARS) using raw (unsmoothed) data from the star tracker and the extended Kalman filter (EKF) algorithm. A special feature of solving the problem of SIARS output data correction and the calibration problem in this mode is rejection of incorrect measurements. The algorithm for this problem solution is described. The ESG drift model is given both for the SIARS calibration mode in order to ensure an adequate prediction of ESG drifts over a long time interval and for the quasi-continuous correction mode under spacecraft maneuvering conditions. The results of data processing of the flight tests of the SIARS and the star tracker aboard one of the spacecraft are discussed.