Research On On-orbit Calibration Technology Of Redundant MEMS-SINS

Compared with the traditional inertial elements,the inertial elements of MEMS have the advantages of small space proportion,low cost and high adaptability,and have been widely used in the navigation field in various environments.Because of its high reliability,the redundancy-based MEMS-IMU is often used in various navigation systems,which effectively prolongs the service life of the system.However,in practical engineering and application,the calibration of redundant MEMS-SINS is different from that of traditional three-axis inertial devices.The error model of devices has changed.There is no unified high-precision calibration method for the redundant configuration of the MEMS-IMU.At present,the application field of the MEMS navigation is more and more extensive,the environment used is more complex,and the performance of the navigation equipment such as volume,reliability and accuracy is important.Seek to become higher.In this case,in order to improve the accuracy and reliability of redundant MEMS-SINS,the key technologies of redundant MEMS-SINS,such as error characteristics,on-orbit calibration error compensation and noise suppression,are studied in this paper.The main work is as follows:(1)Error analysis of redundant MEMS.In this paper,the error characteristics of redundant MEMS-SINS are studied.Aiming at the device error,the installation error,scale factor error and constant error of redundant MEMS-SINS are analyzed,and the error model is determined.The random error of redundant MEMS is analyzed,and the common methods of laboratory calibration and on-orbit calibration are introduced.The existing problems of calibration methods prepare for on-orbit calibration of redundant MEMS-SINS.(2)EMD denoising of redundant MEMS signal with limited amplitude.The advantages of EMD denoising method,Fourier transform denoising method and wavelet transform denoising method are compared.The principle and steps of EMD denoising method are described in detail,and the problems of overshoot and undershoot in EMD algorithm are analyzed.Based on the analysis of error characteristics of redundant MEMS-SINS,EMD denoising is applied to the acquisition signal of MEMS.Aiming at the problem of overshoot and undershoot when EMD is used directly to reduce the noise of the MEMS signal,a method of limiting EMD noise reduction is proposed,which can filter out the peak noise and white noise in the signal of the MEMS.The simulation test is carried out under the environment of Matlab to prepare for the on-orbit calibration of the MEMS and improve the measurementaccuracy.(3)Design on-orbit calibration scheme of redundant MEMS-SINS gyroscope.Aiming at the redundant MEMS inertial devices,the attitude measurement information provided by high precision sensors is used in the MEMS-SINS.The calibration scheme of the redundant MEMS gyroscope is designed,including the state equation of the calibration filter and the design of the measurement equation.The measurement equation with the measurement error of the redundant gyroscope as the observation quantity is proposed.The standard Kalman filter is used as the estimation algorithm.The simulation results show that the calibration scheme of the redundant MEMS gyroscope The improved algorithm improves the calibration accuracy.(4)The noise reduction and calibration experiments of tetrahedron redundant MEMS are carried out.Taking the tetrahedron redundant MEMS-SINS as an example,the effectiveness of the noise reduction and calibration algorithm is verified by combining the three-axis turntable in the laboratory.The experimental results show that the noise reduction algorithm can effectively remove noise,and the accuracy of the calibration compensated MEMS gyroscope is improved by an order of magnitude.