Research On The Key Technology Of Short/Mid-range SINS/GNSS Navigation System

Strapdown Inertial Navigation System(SINS),Global Navigation Satellite System(GNSS)and their integration are the important parts of modern navigation systems.In the fields of guided weapons,small unmanned aerial vehicals,the navigation systems are designed to work in a short range and time and reserve the pure INS mode.The operation condition tends to suffer from high dynamic maneuver and the change of the temperature.Therefore,the key technologies of a short/mid-range SINS/GNSS navigation system are the calibration of a inertial measurement unite,the SINS numerical computation algorithm in high dynamic condition,the airbone transfer alignment technology and the integration of SINS/GNSS.In this paper,we focus on the accuracy improvement of short/midrange SINS/GNSS and finish such researches as follows:(1)The error characters of MEMS-IMU are investigated and the error models of the gyroscope and accelerometer are established.In order to overcome the problem that the error of a MEMS gyroscope is highly dependent on the ambient temperature and we can not achieve sufficient accuracy if it is modeled with polynomials,a Parameter-Interpolation method is proposed to model and calibrate the error of a MEMS gyroscope.A multi-position experiment test using a thermal turntable to calibrate the IMU and test the traditional and the Parameter-Interpolation methods.Results show that the calibration experiment is valid to improve the accuracy of a MEMS IMU and the Parameter-Interpolation method is more effective to calibrate a gyroscope.(2)Considering the coning effect,scrolling effect,etc,which are caused by the unchangeable character of the attitude,a high speed SINS numerical computation algorithm is designed based on the rotation vector.This method has the advantage that it is concise and has high updating rates.Besides,the error character of SINS is analyzed and its state-space model is established.(3)The factors that have influence on the SINS transfer alignment are analyzed and modeled.A transfer alignment algorithm based on ?attitude + velocity accumulation? is designed and a digital simulation test is carried out.The results show that under the environment that existing bending deformation and vibration disturbance,estimation accuracy of roll Angle error is increased by 34.3%,the X axis misalignment is increased by 30% and the three axis accelerometer bias estimation is improved by 34.7%,81.3% and 75% compared with the traditional ?attitude + velocity? matching method.(4)The GNSS positioning principle,error sources,positioning method are introduced and the advantages and disadvantages of various observation information and positioning methods are sum up.Aiming at improving accuracy of mid/short-range SINS/GNSS application,we proposed the epoch-satellite double differential carrier phase positioning method of tightly coupled SINS/GNSS integration.A semi-physical experiment is designed to test the method and results show that the horizontal error is less than 0.5m and the vertical error is better than 1m,which is superior to the traditional integration method.The proposed method needs no base station assistance or ambiguity solution,which facilitates the practical application.