Study On The Crucial Technology Of SINS

Strapdown inertial navigation system (SINS) is a kind of very advanced inertial navigation technology,and it is the developing direction of inertial navigation. For SINS has a series of advantages,it has become a trend that SINS will take the place of platform inertial navigation system in new century. The crucial technologies of torpedo SINS were investigated in this paper.1 .The project of torpedo SINS was demonstrated and put forward at first;The hardware of torpedo SINS was introduced in details,which includes computer. gyroscope accelerometer;The paper described how to choose hardware and design the rebalance circuits of gyroscope and accelerometer;The working principle of torpedo SINS was illustrated;The software and flow chart oftorpedo SINS was described.2. The updating algorithm of Strapdown matrix is one of the crucial techniques of SINS. There are several kinds of attitude updating algorithms of SINS,such as direction cosine algorithm and quaternion algorithm. The attitude updating algorithms were investigated systematically in this paper. On the basis of the quaternion algorithm the coning compensation algorithms and the improved coning compensation algorithms the attitude updating algorithms were deduced when the gyro outputs are angular velocity. Existing updating algorithms analyzed the accuracy of the algorithm,i.e. the outputs of initial components have no errors. But many Strapdown inertial navigation systems work in abominable environments,the outputs of the initial components include disturbance inevitably. As viewed from practicality,several algorithms were compared with each other,and it's shown that the forth order Ronge-Kutta is an algorithm suitable forpracticality.3. The aim of initial alignment of SINS is to compute the initial values of Strapdown matrix. We have known from the analysis of error equations of SINS that the errors produced by the initial alignment will propagate with time,the precision of initial alignment will affect the precision of the whole system,and so it is very important to improve the precision of initial alignment. A kind of quick high precision SINS combined alignment algorithm on fixed base was deduced in this paper,and the error model and measurement model were described. The observability of the system was analyzed with PWCS theory,and it is shown that the system is completely observable. The validity of the algorithm is proved by simulation. Two types of alignment algorithms on moving base were put forward in this paper,one with angular velocity matching,and another with acceleration matching. The error models and measurement models in consideration of ship flexure and lever-effect were deduced respectively. Thealignment methods were verified by simulation.4.Under given conditions the alignment was finished before the torpedo was launched with the precise alignment method of fixed base alignment. After being launched the strapdown matrix was updated by quaternion algorithm. The system was simulated in four kinds of conditions. The effect of gyro drift and accelerometer bias on the evaluation error of misalignment angles and attitude error was analyzed. The conclusion was drawn that the chosen initial alignment algorithm and attitude updating algorithm can meet the requirement of torpedo SINS,and it is shown that the designed torpedo project is feasible.