Research On Key Technologies Of Projectile-borne Semi Strapdown Inertial-based Integrated Navigation System

The guided transformation of conventional munitions is an important direction of information and intelligence development in modern warfare.Acquiring the information of projectile body navigation parameters reliably and accurately is the key to the precise strike of guided munitions.The inertial-based integrated navigation system based on MEMS technology makes it possible to meet the requirements of guided munitions in terms of“dynamic,overload,accuracy,and cost”.Therefore,developing high-precision and high-reliability inertial-based integrated navigation technology is the focus of research in the field of projectile-borne navigation,which has great practical significance for the development of guided munitions.Based on the research of semi strapdown inertial navigation system carried out by the research group in the early stage,and aiming at improving the environmental adaptability,reliability and navigation performance of semi strapdown inertial-based integrated navigation system under complex projectile-borne environment,this dissertation studies the key technologies of the semi strapdown inertial-based integrated navigation system from the aspects of integrated navigation algorithm,navigation performance maintenance and in-flight alignment method.The designed experiments of different schemes verified the effectiveness of the proposed high precision and reliability methods of integrated navigation system suitable for complex projectile-borne environment.On the basis of consulting literature and analyzing the relevant research status,the technical challenges of integrated navigation system for guided munition are analyzed,and the research contents and methods of this dissertation are determined.The main contents of the study include the following aspects:(1)In order to further improve the anti-overload ability and environmental adaptability of integrated navigation system,an optimized structure based on multi-stage composite bearing and counter-top hemisphere is designed according to the motion characteristics and navigation requirements of guided ammunition.The anti-overload capability of the existing navigation system is improved by designing a mechanical structure based on counter-top hemisphere,and the influence of the high-spin environment of guided munition on the measurement system is further isolated by developing an anti rotation device based on composite bearing,which effectively alleviates the contradiction between the range and accuracy of inertial sensors for rotating guided munition.Finally,the adaptability of the semi strapdown inertial based integrated navigation system to the projectile-borne environment is improved.(2)Aiming at the problem that the sensors of integrated navigation system,especially GNSS,are susceptible to interference causing performance changes and abnormal output in the complex projectile-borne environment,which seriously affects the system measurement accuracy,a strong robust integrated navigation algorithm based on factor graph optimization is proposed.On the basis of fully considering the key parameters of each sensor in the integrated navigation system,the SSINS/GNSS integrated navigation factor graph model is constructed by using factor graph technology,which avoids the complicated process of re-establishing the filter model when the sensor information is abnormal,and improves the accuracy and real-time performance of the integrated navigation system when the sensor output is abnormal caused by the complex environment;based on this,a dynamic weight function that can realize weight adjustment and fault isolation is designed to adjust the weight of each factor reasonably and dynamically.Finally,the navigation performance and robustness of SSINS/GNSS integrated navigation system are improved when the sensor measurement is abnormal in complex missile borne environment.Finally,the navigation performance and robustness of SSINS/GNSS integrated navigation system are improved when sensor measurement is abnormal under the complex projectile-borne environment.(3)Aiming at the problem that GNSS outages shortly after the SSINS/GNSS integrated navigation system works normally due to the complex projectile-borne and combat environment,resulting in the sharp decline of system navigation performance,a random forest regression-based wavelet neural network and dynamics information hybrid-assisted seamless navigation method is proposed.Random forest regression is introduced to optimize the wavelet neural network,which avoids the defects of easy overfitting,low prediction accuracy and instability of the single neural network due to fewer training samples,and improves the prediction accuracy of the neural network under the training condition of small samples;in addition,the system dynamics information-assisted SSINS is derived and introduced to further improve system navigation performance during GNSS outages without adding additional sensors.Finally,the navigation performance of the SSINS/GNSS integrated navigation system is maintained under the satellite denied condition.(4)Aiming at the problem that the low or medium precision MEMS inertial device-based SSINS/GNSS cannot effectively achieve fast in-flight alignment with shortendurance,an improved alignment method based on backtracking navigation dynamic correction is proposed.On the basis of fully considering the inertial sensor biases that can not be ignored,an alignment scheme based on backtracking navigation for projectile-borne SSINS/GNSS integrated navigation system is designed.The inertial device deviation and construction errors of related attitude determination vectors during backtracking alignment process are effectively estimated and corrected through constructing a simplified cubature Kalman filter based on Lie group,which improves the alignment accuracy while simplifying the alignment process,and the conflict between alignment accuracy and alignment speed is effectively alleviated.In addition,the concept of Lie group is introduced to discuss the whole alignment process,which makes the alignment process more concise.Finally,the fast and high-precision in-flight alignment for projectile-borne SSINS/GNSS integrated navigation system under the condition of short endurance is realized.(5)On the basis of above theoretical research,the feasibility and superiority of the proposed algorithm and method are validated by different ground vehicle experiments respectively.The research works of this dissertation have important reference significance for the inertial/satellite integrated navigation system in application of guided munition.