Research On Some Key Technologies Based On Single-axis Rotary Inertial Navigation System

Rotary modulation technology is an important method to improve the precision of navigation system under the condition of existing accuracy of inertial devices.In order to meet the actual needs of ship navigation and positioning,single-axis rotary modulation technology is taken as the research object to explore relevant key technologies.The research contents mainly include:Firstly,according to the requirements of high-precision navigation algorithm,the computation structure of angle modulation is adopted to avoid the influence of the error of rotation mechanism's angle on the positioning accuracy.In the process of attitude calculation,the trapezoidal algorithm of rotation vector is proposed to decrease the noncommutativity errors,and simulation indicates that the algorithm meets the requirements of attitude calculation.Secondly,based on the error form of inertial measurement unit(IMU),the rotation scheme based on single-axis rotary modulation is adopted.In this scheme,the modulation effects of various errors of the system are analyzed,which is verified by the simulation.Aiming at the problem that course motion of carrier may weaken the modulation effects,the rotation scheme is changed to make IMU rotate directly relative to the navigation coordinate system.Thirdly,the quaternion Kalman filter algorithm is used to accomplish the coarse alignment of the system.In order to achieve the fine alignment and the estimation of IMU's errors,the Kalman filter model is adopted according to observability and degree of observability analysis.Simulation results verify the effectiveness of the alignment method and show that rotary modulation can improve the alignment effect and the ability of error estimation effectively.At last,aiming at the problem of slow estimation speed of scale factor error,a scheme of oblique installation of IMU to rotation axis is proposed.The simulation result shows that the scheme is effective and feasible.