Strapdown Inertial / Od / Pseudo Satellite Navigation System For Research

Considering the independence and reliability of navigation system for vehicle, SINS/OD(Strapdown Inertial Navigation System/Odometer) independently integrated navigation technology and SINS/OD/Pseudo-Satellite integrated navigation technology are studied in this thesis. Integrated navigation system can effectively reduce the system error, improve the performances of navigation system, and also can cut down its cost.The main efforts done in the thesis are as follows:Firstly, ZUPT (Zero Velocity Update) can diminish the error of inertial navigation system for vehicle, but this method needs periodic stopping, can't meet practical demands. The error accumulation of inertial navigation system can be restrained via OD, however, OD scale factor error has remarkable effect on the positioning precision. In order to reduce OD scale factor error efficiently, this paper presents the tightly coupled form of SINS/OD integrated system. Take advantage of the pinpoint accuracy of SINS in the short time after initial alignment, OD scale factor error is rectified via velocity coupled mode. Simulation results show that after real time rectification, OD scale factor error can be reduced to 10^-4 quantity from 0.01, and the positioning accuracy of tightly coupled system is prior to loose coupled system. Furthermore, the fault detection and disposal methods for OD racing, sliding, rolling with sliding and sideslipping errors are analyzed briefly.Secondly, this paper dissects the influences of the drifts of gyros and the initial error of azimuth angle on the positioning precision of SINS/OD system. Simulation results indicate that the drift of up gyro and the initial error of azimuth angle have significant effect on the positioning precision, however, compared with the drift of up gyro, the drifts of east and north gyros have less effect on the positioning precision. Therefore, we can choose a little worse east and north gyros to cut down the cost of the navigation system.Thirdly, SINS/OD integrated system fails to diminish the error of azimuth angle, this paper introduces the regional positioning system based on Pseudo-Satellite as a member of the integrated system to diminish the error of azimuth angle in the moving state, and further improve the precision of positioning and orientation. Compared with the land mark setting method, this method hasadvantages of continuous measuring, avoiding stop and serving multi-user at the same time. It also can install the Pseudo-Satellite station according to the actual path of vehicle. The influence of GDOP (Geometric Dilution of Precision) on the positioning accuracy of Pseudo-Satellite is investigated. Simulation of SINS/OD/Pseudo-Satellite integrated navigation system is performed. The simulation results indicate that Pseudo-Satellite can effectively diminish the error of azimuth angle and position. Then it can reduce the accumulation of error after vehicle depart from effective range of Pseudo-Satellite, and the low-cost, middle-precision positioning and orientation has been achieved.