Research On The Technology Of Gravimeter Error Compensation And Auxiliary Navigation

With the promotion of the position of submarine in the national military strategy,the improvement of the underwater navigation accuracy is becoming the core issue in the field of navigation research at present.Inertial navigation system has been equipped in the various types of underwater vehicle,the advantage is that can achieve autonomous navigation without any external signal.But how to keep high navigation accuracy for a long time,has always been a focus in the study of inertial navigation,which is not just about submarine's own security problems and the ability to survive,but is also related to the accuracy of its strategy to combat.Obviously,relying on navigation of inertial itself is unable to keep its high accuracy,to reset inertial navigation system periodically with outside information is necessary.Now commonly used methods such as GPS satellite navigation,usually requires the submarine surfaced,although this can achieve high navigation accuracy,but it's easy to expose the submarine's location;Doppler Log,though it can measure the submarine's speed relative to the water or the ground and mileage,but in practice,due to the complex underwater environment,making the measurement results inaccuracy.Although celestial navigation does not need transmit signals to the outside world,but its accuracy can be affected by the weather.Gravity anomaly is an inherent physical parameters of the earth,the measurement not affected by the external Marine environmental interference,we can use the gravity anomaly information to correct the inertial navigation system.Therefore,gravity aided inertial navigation is an ideal method.In this paper,sea gravimeter is the research object,the main works of my paper includes:Firstly,introduce the Chekan-AM marine gravimeter's structure,measurement equations are derived,and some issues of gravity measurements are discussed,including basic measurement theory,static error and dynamic error correction,and use the river test measurement data to verify the proposed algorithm.Secondly,in order to effectively eliminate the noise of the marine gravimeter measurement signal and improve the measurement accuracy,two de-noising methods of Mallat algorithm and wavelet packet decomposition are proposed based on multiresolution analysis.Then we introduce some basic wavelet function and threshold processing method,analyze the relationship between wavelet decomposition scales and filtering effect.This study also involves the comparison of the computing efficiency and filtering accuracy of two algorithms.Finally,we select the most suitable method for gravity signal.Thirdly,in order to eliminate the horizontal error of gravimeter stabilized platform,we analyze why the horizontal error angle can generate by deriving the error equation of gyroscope and accelerometer.Combined with the error equations,we design an error correction scheme by using external speed information.Finally,the basic principle of inertial navigation systems is introduced,the error equation of inertial navigation system is derived,and Extended Kalman Filter equations for nonlinear gravitational field model is established.According to issue of gravimeter output delay,we propose a time delay compensation algorithm.Then we calculate the delay time of gravimeter on the basis of Eotvos(5)(5)(5)(5)effect and apply the compensation algorithm to the gravity aided inertial navigation system.