Research On Strapdown Compass Alignment In Dynamic Environment Based On Forward And Reverse Navigation Solution

Initial alignment of strapdown compass is a process of closed-loop adjustment through control algorithm based on compass effect.Accuracy and rapidity of the alignment algorithm are mutually restricted.With the rapid development and upgrading of inertial devices,the problem of accuracy has been gradually solved.The problem of rapidity is one of the urgent problems to be solved in strapdown compass alignment.In this paper,the principle of initial alignment of platform compass,the principle of initial alignment of strapdown compass and the configuration of compass parameters are deeply analyzed.Coarse and fine alignment algorithms of strapdown compass are deduced,and an improved compass alignment algorithm is proposed,which improves the conventional four-step alignment of strapdown compass to threestep alignment.The principle of reverse navigation is analyzed,the application of reverse navigation solution in initial alignment of strapdown compass is studied.The precise alignment algorithm of static and moving base is deduced.The strapdown compass alignment based on forward and reverse navigation solution is completed,and the full cycle forward and reverse alignment method and half cycle forward and reverse alignment method are proposed.Aiming at improving real-time performance in alignment of moving base,an alignment method based on attitude compensation is proposed,and two compensation methods,one-time attitude compensation and continuous attitude update,are designed.Aiming at the problem that the coarse alignment error is too large to prolong the fine alignment time,a forward and reverse two-stage parameter configuration method is proposed.Through using the simulated IMU data generated by the trajectory generator designed in the paper,the algorithm deduced in the paper is simulated and verified in three states of stationary,swaying and traveling respectively.The full cycle method and the half cycle method can improve the alignment accuracy under the same parameters and time conditions,and compared with the conventional strapdown compass alignment method,the alignment time is shortened.The static alignment test was carried out by using laboratory three-axis turntable and inertial navigation system.The practicability of strapdown compass alignment algorithm based on forward and reverse navigation solution was verified by offline data processing,and the expected effect was achieved.