Research On Error Compensation Technologies For Tri-Axis Rotation Inertial Navigation System With Laser Gyros

With the application and development of inertial navigation technology,the accuracy requirement of ultra-long endurance navigation is increasing day by day.Considering the cost,implementation and stability,it is necessary to study the calibration technology and rotation modulation technology to realize the automatic compensation of inertial sensors’ errors.The designs of calibration paths and the arrangements of rotation schemes are important research contents of calibration technology and rotation modulation technology of the inertial navigation system.At present,there are still some problems,such as the inertial sensors’ errors cannot all be modulated by the dual-axis rotation schemes,the calibration paths and rotation schemes are relatively independent,and the error modulation effects of the dual-axis rotational INS are seriously influenced by the angular motions of the vehicle.In this paper,the design of tri-axis rotation modulation scheme,the design of unified scheme for rotation modulation and self-calibration,and the technology of vehicle angular motion isolation are studied,which provide technical support for the tri-axis rotational inertial navigation system equipped with high-precision laser gyros and improve the navigation accuracy of ultra-long endurance inertial navigation system.The main work of this paper includes the following four parts:1.Design and error analysis of tri-axis rotation modulation scheme for SINS.Based on the error propagation equations of the rotational inertial navigation system,the modulation principles of gyro drifts,scale-factor errors and misalignments in the case of single-axis and dual-axis are discussed,and the limitations of the single-axis and dual-axis schemes on error modulation are pointed out.The error modulation principles of the rotation scheme based on the geocentric inertial frame are analyzed,and a16-sequence tri-axis rotation scheme is designed.The propagation characteristics of each error in the dual-axis scheme and the tri-axis scheme are compared and analyzed,and the navigation simulations are carried out.The results show that the tri-axis scheme can eliminate the coupling between the earth rotation and inertial sensors’ errors and effectively improve the navigation accuracy.2.Design of the unified scheme for self-calibration and rotation modulation of SINS.Six design principles of the schemes with both self-calibration function and rotation modulation function are proposed,and a 48-sequence unified rotation scheme is designed in detail.The observability analysis and error analysis results show that the48-sequence scheme has better observability than the 18-position scheme,and the misalignment angle errors and sawtooth type velocity errors caused by the misalignments are smaller than the 16-sequence scheme.Simulations and experiments show that the 48-sequence scheme can effectively improve the error calibration and modulation effects and reduce navigation errors.3.Research on vehicle angular motion isolation technology of tri-axis rotation SINS.The influences of complex vehicle angular motions on the error modulation effects are analyzed in the case of 16-sequence dual-axis rotation modulation.The results show that the complex vehicle angular motions are coupled with gyro errors,which seriously affect the navigation accuracy of inertial navigation system.A vehicle angular motion isolation technology of tri-axis rotational SINS based on attitude feedback is proposed.Simulation results show that the navigation errors are reduced obviously after the application of this technology,which proves that it can effectively isolate various kinds of complex vehicle angular motions.4.Development of tri-axis rotational strapdown inertial navigation simulation system and long-endurance navigation experiments.The functions of the data generation module,the initial alignment module and the navigation solution module of the tri-axis rotation strapdown inertial navigation simulation system are briefly explained through the operation demonstrations.The ultra-long endurance navigation experiments of the rotational SINS are carried out.The results show that the position error of the system in 30 days is X.Xn mile(MAX)and the velocity error is X.Xm/s(RMS).