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

The rotational inertial navigation system (RINS) employs a rotating modulation technique by introducing rotation gimbals, thereby enhancing accuracy of the RINS in position and velocity estimation. Furthermore, the rotation gimbals provide the self-calibration ability in the 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 has largely overlooked the influence of temperature on non-orthogonal angles and the calibration accuracy are susceptible to various factors. In this paper, we discuss the causes of temperature-induced errors in non-orthogonal angles and their impact on attitude estimation, and a self-calibration method based on outputs from fiber optic gyroscopes and optical angle encoders is proposed, showing good repeatability by using periodic averaging. The rapid rotation scheme adopted is suitable for calibrating temperature errors during system operation and a temperature-stabilized chamber is not required. The results of navigation experiments validate the effectiveness of the calibration and compensation method. After compensating the temperature errors of non-orthogonal angles, we can see a decrease in the amplitude of attitude output oscillation from 80 '' to less than 10 ''.