Research Of The Transfer Alignment Base On Fiber-Optic Strapdown Navigation System

Transfer alignment is a kind of dynamic alignment, which uses high precision MasterInertial Navigation System (MINS) to calibration the non-alignment Slave Inertial NavigationSystem (SINS). Because of short alignment time and high alignment accuracy, transferalignment has been used in weapon system now. There are some interference factors, such asarm effect, ship deformation and time delay, which affect the alignment accuracy, so in thispaper, it studies those factors and takes a certain approach which compensates the error.The most study object in this paper is Stapdown inertial navigation and some baseknowledge of Stapdowm inertial navigation are been introduced. Error equation, such asvelocity error equation, location error equation and attitude error equation are been derivationbased on basic equations of inertial navigation. Kalman filter which usually used in the inertianavigation system is introduced.In connection with time delay, first, affect is studied which causes by time delay. Thenthe compensation of time delay is introduced which uses velocity plus attitude matchingmethod. Two methods are introduced in this paper: the first method is introduced in rigid. Inthis method, time delay is increased in Kalman filter. The error model is established byupdating the attitude matrix and delay time is estimate as a random value. The second methodis introduced in deflection, and delay time is designed as a constant. The error which causesby time delay is got by updating the attitude matrix, and is compensated by using directioncosine method.In connection with arm effect, the theory of arm effect is introduced, and then the affectwhich causes by arm effect is studied. Based on ship deformation, arm effect is divided intorigid arm effect and flexibility arm effect. To the problem of rigid arm effect, the calculatedmethod is used. The velocity error which causes by arm effect can be calculated in the case ofarm length is known, and is decreased in the velocity observations of Kalman filter, then itcan get compensation effect. But in practice, arm length can be changed in the case ofdeformation, so to the problem of flexibility arm effect, it derived the connection between armlength and deformation angle, and then the error model is established, last the error can becompensated.To the problem of ship deformation, first it introduces some measurement methods, buttransfer alignment is studied in this paper, so inertia match method is used to measure the shipdeformation. Iteration and Kalman method are introduced in inertia match method. ButIteration is a kind of recurrence method, and the error is cumulative as time, so Kalman method is used to simulate. Simulation shows that Kalman methods can effectively measurethe ship deformation.