Research On Methods Of Error Assessment And Allocation In Fog Strapdown Inertial Navigation System

In strapdown inertial navigation system(SINS), initial alignment errors, inertialinstruments errors and algorithm errors could propagate with navigation computation,leading to final navigation parameters containing errors. Error assessment and errorallocation are the nassessary requirements to ensure the navigation accuracy and the twoalso constitute the main questions studied in this paper.Firstly, SINS error model is derivated based on SINS basic equations and islinearized simultaneously. Futher, inertial intrument errors, especially fiber opticgyro(FOG) errors, are analyzed and the state space method for analyzing quantizationerror in inertial instruments is studied.Secondly, the paper makes a study of SINS errors on static base. Solving method ofnavigation parameters errors caused by the determinstic errors in inertial intsruments isgiven and their types are summarized. Further, based on simplified SINS error model,navigation parameter errors covariance equation is built, solving method of which isdesigned and the analytical solutions of3σ envelopes of navigation parameter errorscaused by the sochastic errors in inertial instruments are derivated and are verified bysimulation. The effects of initial alignment errors on navigation accuracy are analyzed.Thirdly, in order to meet the needs of studying SINS errors on dynamic conditions,SINS error assessment simulation test platform is built. Inertial instruments errosmodule(providing inertial instruments error data) and trajestory generator(providingvehicle motion information) serving for simulation test platform are designed. SINSerror propagation property on dynamic conditions is investigated. And degree ofinfulence inertial instruments errors and initial alignment errors have on navigationaccuracy is anlyzed quantitatively. Meanwhile, SINS algorithm errors on high dynamicconditions are considered.Finally, based on error assessment, three principles used for SINS allocation arestudied, including principle of equal allocation and principle of proportionate allocation.Under the direction of the two principles, SINS error allocation processes and samplesare prestented. It is proved that allocation results satisfy the accuracy requirement bysimulation and the advantages and disadvantages of the two principles are analyzedcomparatively. Further a summary of guidance is given. And error allocation method ofSINS on dynamic conditions is probed. With the same time, the overall idea of SINSerror allocation is discussed.