Research On Error Characteristic Of Marine Inertial Navigation System Based On Single-axis Rotation

Rotation modulation is one of the key technologies to improve the accuracy of inertial navigation system(INS).However,in the single-axis rotation INS,errors of the inertial sensors along rotating axis can't be modulated due to the constraint of structure.Two-axis rotation and three-axis rotation are proposed to solve this problem,which are effective but make the structure of INS more complex,and new sources of error introduced.Therefore,how to improve the accuracy of system without increasing complexity of the system configuration becomes a hot topic for researchers.Based on this,the error characteristics of rotary inertial navigation system is analyzed,also the error factors of shipboard inertial navigation system.Moreover,a non-orthogonal installation scheme of inertial sensors was put forward for single-axis rotating SINS in this paper.The main work includes:1.The basic theory of INS based on single-axis rotation is described,and error modulation of inertial sensors when using single-axis rotation is analyzed.Then,the analytical solution between sensor errors and systematic errors is solved;also the influences of sensor errors on position accuracy before and after rotation are analyzed in frequency and time domain.The analysis shows that the horizontal errors of inertial sensors can be modulated when using the single-axis rotation and the position error can be obviously decreased.2.The influences of angle measurement error and angular acceleration on rotation modulation are analyzed to the influence of rotation platform introduced for single-axis rotation.Analysis shows that heading angle error changes linearly with the angle measurement error and the rotation platform causes the constant error at the acceleration stage,which indicates that the right acceleration time should be selected in actual system.Otherwise,the effects of vehicle tilt angle motion on the rotation modulation are analyzed considering the actual work environment of vehicle INS.Theoretical analysis and simulation experiments show that the vehicle angle motion can bring attitude error,and the errors increase with speed of angular movement.However,the effect of magnitude of movement on attitude error is not large.3.A new installation scheme of inertial sensors was put forward for single-axis rotating SINS in this paper,namely non-orthogonal installation method of sensitive axes of inertial sensors.Analysis shows that the errors of inertial sensors can be modulated in three directions.Experiments show that the new method can reduce the positioning error and velocity error of marine INS,and effects of error depression vary with the angles between two axes.When choosing the right installation angles,speed error can be reduced to a maximum of 2/5 of its original position error,and position error can be reduced to a maximum of 1/5.