Correction of calibration of navigation system sensors during operation by implementing non-orthogonal structure of accelerometers

In this paper, an inertial navigation system is designed based on the unorganized installation of sensors. In this design, which is performed in an inertial navigation system connected to the body, unlike the common method of installing the sensors in an orthogonal manner, the sensors, especially the accelerometers, will have unusually sensitive axes when installing. In the explanation, it should be said that the calibration of inertial navigation blocks is very important in navigation accuracy, and therefore efforts are made to calibrate the inertial navigation blocks and its sensors with the highest possible accuracy. For various reasons, the calibration coefficients of the inertial sensors lose their validity over time, which necessitates their intermittent calibration. In this paper, a pre-launch calibration method is proposed that not only compensates for the need for multiple calibration of navigation blocks, but also reduces the navigation error due to determining the initial state, ground gravity model, and computational errors. In this method, using the acceleration of local gravity and the speed of the earth, it is tried to compensate for the deviation in the coefficients of calibration and some other errors at the time before the launch. In addition, in order to solve the problem of non-observability of accelerometers perpendicular to the gravitational field, it is proposed to install the accelerometers imperfectly, which has more details and calculations related to this method in the body of the article. Finally, the results of the implementation of the non-productive structure clearly show the improvement of navigation accuracy due to the appropriate estimate of the compensation coefficients.