Research On Air Alignment Method Of Inertial Navigation System For Rotating Guided Ammunition

Compared with traditional conventional ammunition,guided ammunition has the advantages of precision strikes,long-range combat,and flexible use.They are the main weaponry of the future military.Inertial navigation system,as the key equipment for guided ammunition,is faced with many problems such as short alignment time,low survival probability of sensors,and complicated dynamic environment when aligning on the moving base in the air.Aligning on the moving base in the air is the key method to inertial navigation system for guided ammunition,which is researched widely in the world.In order to improve the performance and reliability of the alignment of the inertial navigation system for guided ammunition,the air moving base aligning algorithm was researched.The research includes five parts: Error modeling and compensation technology,coarse alignment method based on inertial solution,fine alignment in the high dynamic conditions,air moving base alignment method based on the characteristics of the inertial information of the rotating projectile,aerial motion assisted by wireless beacons.The main research and innovation work were as follows:Aiming at the characteristics of the sensors and the environment of the inertial navigation system for guided ammunition appiled,the research on the dynamic error compensation method was carried out.A random error modeling and compensation method based on Allan variance was proposed.In addition,the error compensation method in high dynamic conditions of the rotating ammunition was researched.A simplified dimension compensation algorithm was proposed.It reduced the calculation amount of the size effect compensation algorithm,and improved the system operating efficiency.Linear acceleration disturbance can invalidate the performance of the coarse alignment.In order to slove this problem,an alignment method of moving base assisted by satellite navigation was proposed.It can eliminate the influence of harmful linear acceleration.Combined with the inertial error characteristics of rotating ammunition,an optimized coarse alignment algorithm was proposed.The algorithm changed the constant period coarse alignment calculation to a variable period calculation,which is consistent with the shell rotation period.It can eliminate the impact of ammunition rotation on coarse alignment results,and improve the alignment accuracy.Traditional observability analysis method is difficult to determine the alignment state accurately.In order to solve this problem,observability analysis algorithm of alignment model based on singular value decomposition(SVD)was proposed.It adopt the PWCS method to analyze the observability of the aligning inertial navigation system,which is in the time-varying state.This method can analyze the current filter estimation state accurately.In addition,nonlinear error can reduce the accuracy of alignment.In order to solve this problem,an adaptive Kalman filter estimation algorithm based on noise estimation was proposed.This algorithm compensated linearized model errors with virtual time-varying noise.It can improve the accuracy of alignment.Because of large overload,the inertial sensors was invalid in large probability.It caused the INS hard to align.In order to solve this problem,alignment method of air moving base based on inertial information characteristics of rotating projectile was reasearched.According to the dynamic characteristics of rotating projectile and the carrier phase tracking technology,a roll alignment method based on carrier phase tracking was proposed.Combined with the loop order selection strategy and the window function integration threshold selection strategy,the algorithm was optimized.In order to improve the adaptability of the alignment algrithom,a parallel dual-tracking rolling angle alignment method was proposed.This method can tracks the output results of the Y-axis gyroscope and the Z-axis gyroscope simultaneously.Using the optimization algorithm of the optimized roll tracking result based on the noise floor estimation,the optimal roll tracking result was obtained.The simulation results show that the method can adaptively remove the abnormal tracking results,and output the optimal roll tracking results.It can improve the robustness and environmental adaptability of INS for guided ammunition.The large overload could cause that the non-rotating projectile sensor was faulty or only the X-axis gyro survived.In order to slove this problem,the alignment method of air moving base assisted by wireless beacons was researched.Firstly,the model for the alignment of moving bases in the air assisted by wireless beacons was established.In addition,the alignment algorithm of moving base based on dead zone judgment assisted by track pitch was proposed.It can solve the binary problems in alignment of airborne base.Simulation results show that the algorithm is feasible and effective.It can improve the usability of the guided ammunition navigation system,and reduces the difficulty of inertial navigation system for guided ammunition with the aid of wireless beacons.