Research On Error Modulation Method Of Semi Strapdown Micro Inertial Navigation System

With the development of inertial navigation system(INS)technology,hybrid INS has become a hot spot of research.The research is mainly to solve the problem of high precision measurement of carrier information in high dynamic field.The semi strapped-down inertial navigation system(Semi-SINS),as one of the hybrid INS,solves the problem of measuring the cross range between high rotational speed and small range inertial devices,and realizes the precise measurement of the attitude of high spin ammunition using small range and high precision devices,but the precision of the measurement can not meet the precision requirements of the guided weapon.In order to further improve the measurement accuracy of Semi-SINS,this paper combines the characteristics of Semi-SINS,introduces the rotation modulation method into Semi-SINS,and conducts research on the error modulation method of semi-strapdown micro inertial navigation system.First,the principle of Semi-SINS and its realization of rotation modulation is briefly described.It is pointed out that the modulation effect of the semi-SINS roll axis selection is obviously better than that of the other two axes.Through the derivation of the system error propagation model,the main error sources affecting the measurement accuracy of Semi-SINS are found out.Secondly,the main errors affecting the Semi-SINS are introduced,and the influence of the modulation method on these errors is analyzed.The mathematical model of the error after the rotation modulation is obtained,which is convenient for the following analysis.Furthermore,the rationality of the previously selected rotational modulation axis is analyzed and verified by simulation.Then,the modulation effect of several rotation schemes is compared with one way continuous,positive and negative continuous and turn stopping schemes.It is pointed out that the modulation effect of the second rotation scheme is the best in the ideal case.Based on the positive and negative continuous rotation scheme,a multi circle positive and negative continuous rotation scheme is proposed.This scheme can effectively avoid the influence of the output angular rate error caused by motor accelerationand deceleration on the rotation modulation effect.Based on the Semi-SINS error model and the motor output error model,the optimal rotational angular rate design was carried out and simulated.The results are in perfect agreement with the previous analysis.Finally,in order to verify the previous analysis,static and dynamic navigation experiments were conducted.The static test verifies that the error of the MEMS device is the main error affecting the accuracy of the Semi-SINS,and provides a reference for the dynamic test.The dynamic navigation test is divided into two parts: the verification test of modulation angle rate and the verification test of the best modulation scheme.The experimental results show that,for the semi strapdown inertial navigation system,the optimal rotation modulation angle rate and the optimal modulation scheme should be analyzed in combination with the output characteristics of the motor in the actual system.When the system is rotated with the optimal modulation angular rate designed in this paper,the modulation effect is the best,and the multi-turn continuous rotation scheme proposed in this paper can effectively reduce the influence of the motor output error on the system measurement accuracy.