Research On High-precision North-seeking Technology Based On Single Fiber Optic Gyroscope

The development of inertial technology provides a new method for the independent high-precision north-seeking system.The FOG(Fiber optic gyroscope)is widely used because of its unique advantages.Compared with a complete inertial system,the north seeker consisting of a single FOG has low cost relatively.Based on the analysis of the FOG and north-seeking principle,the north-seeking schemes and error propagation law of the single-FOG north seeker is studied,and the angular velocity measurement model with installation error is established.In addition,several improved schemes are proposed.The main contents of this paper are as follows:(1)Firstly,the working principle,performance indexes and main noise of the FOG are introduced.The random noise of the FOG is analyzed by Allan variance,and it is found that the main error source affecting the accuracy is angle random walk.Then the principle of the FOG north seeker is introduced,and the commonly used north seeking schemes are deduced and compared.An angular velocity measurement model is established with the installation error of FOG and shaft.It describes the relationship between the azimuth and the angular velocity measured by FOG at each point.(2)The influence of error sources on the north-seeking accuracy is deduced,including gyro error,geophysical error,installation error and so on.The main error sources are founded and the GUI(Graphical User Interface)is designed to provide reference for FOG selection and mechanical structure design of north seeker.(3)According to the law of error propagation and the characteristics of FOG,several improved north-seeking schemes are proposed.The angle of inclination is compensated by adding an accelerometer.An improved two-position north-seeking scheme is proposed to restrain the influence of trend items on the accuracy of north-seeking.Aiming at the large random walk coefficient of FOG,an improved four-position north-seeking scheme is proposed.The accuracy of north seeker is further improved by allocating sampling time reasonably under the same total time.