A self-calibration method for temperature errors of non-orthogonal angles between gimbals in rotational inertial navigation system

Abstract

The Rotational Inertial Navigation System (RINS) employs a rotating modulation technique by introducing rotation gimbals, thereby enhancing RINS' accuracy in position and velocity estimation. Furthermore, the rotation gimbals provide the ability for self-calibration in RINS. However, it introduces new sources of error, such as non-orthogonal angles between gimbals, which result in inaccuracies in attitude outputs and thus require precise calibration and compensation. Previous research employs RINS attitude errors as measurements in the Kalman filter (KF) for calibration. However, attitude measurements are susceptible to various factors, and the influence of temperature on non-orthogonal angles has been largely overlooked before. In this paper, we discuss the causes of temperature-induced errors in non-orthogonal angles between gimbals and their impact on attitude estimation. And a self-calibration method based on outputs from fiber optic gyroscopes and optical angle encoders is proposed. The results of navigation experiments validate the effectiveness of the calibration and compensation method. After compensating the temperature errors of the non-orthogonal angles between gimbals, we can see a decrease in the amplitude of attitude output oscillation from 80" to less than 10".