Feasibility Study On Integration Scheme For North-Finding And Navigation Using Constant-rate Biased/Dithered RLG

The technical advantages of fully autonomous,all-weather work and high accuracy in RLG fast north-finding system and RLG strapdown inertial navigation system make them research deepening and application expanding in the civil,military and other fields.In this thesis,based on the high accuracy and fast oriented navigation application backgrounds,a technology scheme of RLG strapdown inertial navigation system with both high accuracy fast North-finding and high accuracy inertial navigation is studied.Based on independent research and development laboratory high accuracy constant-rate biased RLG north-finding system prototype,focused on improving the technical requirements of system performance price ratio,initial alignment accuracy and speed,and also suppressing pure inertial navigation error,the feasibility of Integration Scheme for North-finding and navigation using Constant-rate Biased / Dithered RLG is deeply studied.The main work and innovations are as follows:Four possible integration scheme for north-finding and navigation are analyzed,Scheme one: integrated scheme for north-finding and navigation with constant-rate biased RLG;Scheme two: integrated scheme for north-finding with constant-rate biased model and navigation with dithered biased model;Scheme three: integrated scheme for north-finding with single / double constant-rate biased RLG and navigation with dithered RLG;Scheme four: integrated scheme for constant-rate biased / dithered RLG.Key technical problems to be solved for different schemes are discussed.An initial alignment algorithm for the integration system of the constant-rate,biased / dithered biased RLG north seeking and navigation is proposed which solves the key technical problems in scheme four.Adding a fixed dithered RLG which is not rotating with the biased mechanism on the base,to suppress the accumulation of the attitude error caused by the gyro scale factor error in the direction of the biased rotation axis.Accurate calibrating the system key parameters C_b^b_g,5 states,7 states and 11 states of the kalman filter are used for initial alignment..The results show that for scheme four,with accurately calibration of C_b^b_g,the amplitude of the horizontal attitude angle is reduced from 10 arc seconds?1 s?to 3 arc seconds?1 s?.5 states,7 states and 11 states of the kalman filter algorithm can not only effectively reduce the azimuth cyclical fluctuations,but also the azimuth accuracy of 10 min initial alignment is better than 10 arc seconds?1 s?;and for low sampling frequency,the same can reach 10 min azimuth accuracy better than 10 arc seconds?1 s?.The main problems of north-finding algorithm for single / double constant-rate biased RLG system is comparative analyzed.Although this method does not require additional precise angle measuring turret instrument,and extracting from the gyro output signal of the turntable angle information which inhibits the effects of angle measurement error on initial alignment accuracy and reduces the cost of the system.However,experimental results show that based on quadrature detection,in the single constant-rate biased RLG north seeking process,because the direction sensitive error which caused by the moving cone of rotating table and the uniform periodic rotational speed can't be compensated,eight-position heading angle accuracy only can reach 3.7687 degrees?1 s?,for a single position,the repeatability is not good,the accuracy can only reach 1.42 arc minutes?1 s?;and in the double constant-rate biased RLG north seeking process,although the turntable periodic uneven rotation angle error and direction sensitive coupling error may be partially compensated,but the accuracy is still not high,the heading accuracy can only reach 22 arc minutes?1 s?,for a single position,the repeatability is not good,and there's a big difference between the actual value and the solving value of heading angle,precision can only reach 1.24 arc minutes?1s?.So,scheme three is eliminatedNavigation algorithm and feasibility of integration scheme for north-finding and navigation of scheme one,two and four are comparatively studied.The main error factors of the pure inertial navigation system are analyzed for the three schemes.Experiment and Loop simulation experiment based on the Constant-rate biased RLG north-finding system are established.The results display that scheme one and scheme two are not feasible.But scheme four is feasible,under a static base condition,the accuracy of mid-long time navigation and pure inertial navigation can be increased to a level that both the north and east position error are better than 200 m / 4 hours.For the 24-hour long navigation,the north position error is better than 450 m / 24 hours,the east position error is better than 750 m / 24 hours.