Research On The Technology Of Online Calibration And Compensation And Dynamic Accuracy Evaluation For High-precision Inertial Navigation System

Inertial Navigation System is a completely autonomous navigation system widely used in aerospace, aviation, navigation and other fields, and has a prominent position in the field of navigation. The flexible-mobility and multimodal flight characteristics and serious flight environment of the newfashioned high-performance aircrafts put forward higher requirements for the autonomy, reliability and precision of the airborne high-precision Inertial Navigation System. So, how to improve the navigation performance of the airborne Inertial Navigation System is a problem which is needed to be solved urgently. Therefore, this paper researched the technology of online calibration and compensation and dynamic accuracy evaluation for high-precision Inertial Navigation System, in order to realize the high-precision, autonomous and reliable navigation of the airborne navigation system for the newfashioned high-performance aircrafts, and provide the theoretical basis and method reference for the newfashioned high-performance aircrafts’ high-precision navigation.This paper studied the key technology of the inertial navigation, designed an online calibration method for IMU’s deterministic errors of the high-precision Inertial Navigation System, established the high-precision error models of the inertial sensors and the high-order online calibration filtering models of the system. The observability of Inertial Navigation System’s errors was analyzed, the excitation characteristics of all errors were studied. The online calibration on the inertial sensors’ installation errors, scale factor errors and random constant errors was finally realized, and it can improve the precision of Inertial Navigation System effectively in the process of vehicle’s dynamic flight.Based on the establishment of the error models and online calibration filtering models of the high-precision Strapdown Inertial Navigation System, this paper proposed an online calibration method for IMU errors based on the innovation-based adaptive filter. The method can dynamically adjust the system noise covariance matrix and measurement noise covariance matrix to realize the IMU errors’ adaptive online calibration, which can solve the problem that the noise model parameters are not accurate when using the conventional Kalman Filter for online calibration in the serious flight environment, and improve the accuracy and adaptability of the online calibration method effectively. Based on the simulation, it was proved that the designed online calibration method for IMU errors based on the innovation-based adaptive filter was effective.For effective evaluation of Inertial Navigation System’s navigation performance, this paper researched the dynamic accuracy evaluation method for the high-precision Inertial Navigation System, designed the evaluation scheme for the navigation system’s dynamic accuracy, analyzed the algorithm principle of the fixed interval smoothing filter, and improved the existing algorithm to achieve better smoothing effect. Considering the different flight environment, the simulation results of the modified fixed interval smoothing filter’s open loop correction, fixed interval smoothing filter’s open loop correction and Kalman Filter’s open loop correction were compared. And it showed that compared to Kalman Filter, the navigation precision of Inertial Navigation System was improved further when open loop corrected by the fixed interval smoothing filter, and the modified fixed interval smoothing filter algorithm had better smoothing effect. Therefore, using fixed interval smoothing filtering algorithm can get high-precision navigation benchmark parameters. It can be used as the reference for the system’s offline performance evaluation, and realize the dynamic accuracy assessment of Inertial Navigation System.On the basis of the theoretical research on the online calibration method and dynamic accuracy evaluation algorithm of Inertial Navigation System, this paper built the digital simulation platform and semi-physical simulation platform for the online calibration and compensation and dynamic accuracy assessment of the high-precision Inertial Navigation System. It can provide a good means of validation for the technology of online calibration and compensation and dynamic accuracy evaluation of the high-precision Inertial Navigation System.