The Research Of Filter Technic In Initial Alignment Of INS/GPS Integrated Navigation System

The initial alignment precision impacts directly on the precision of the inertial navigation system(INS).The time used in initial alignment processing is an important military tactics technique index of the INS.So the initial alignment is one of the most important key technical of the INS.At present,the Kalman filter is the most well rounded and widely used filter.Kalman filter requires the known statistical character of system disturbance,which can't be strictly satisfied in practice system usually.H~∞filtering requires the disturbance is energy bounded other than known accurate statistic.H~∞filter has robustness both in uncertain noise and in uncertain system parameter,and it can be completed in the conditions mentioned above.In this paper,in INS/GPS(Global Position System) intergrated navigation system,with information of GPS assistance,main investigation is the application of H~∞filter in initial alignment.In this paper,the error models of INS and GPS are analysed,then basic theories of the Kalman filter and H~∞filter are expatiated and deduce the connection of them,post the real reason why the robustness of H~∞filter is more than Kalman filter.And when the statistic characteristics of noises are precise white noise,H~∞filter has bad error precision than Kalman filter.So we introduce a improved H~∞filter.In this paper,Kalman filter,H~∞filter and improved H~∞filter are designed in inertial initial alignment of integrated navigation system.In the simulation,the Matlab is used to realize them,and simulation is done.We contrast the two simulation result. When the statistic characteristics of noises are precise white noise,the Kalman filter can keep less error precision in the initial alignment than H~∞filter.When the statistic characteristics of noises are coloured noise or unknwon,Kalman filter has bad error precision,or can not compute the results sometimes,but H~∞filter can keep upper precision in this cases.That is the reason why H~∞filter is more conformable than other filter means.In this paper,we also simulate that some parameters of H~∞filter influence for H~∞filter.