Research On Dual-Axial Rotary Inertial Navigation System Modulation Schemes And Alignment Technique

Inertial navigation system uses the inertial measurement unit which includes gyroscope and accelerometer to measure the movement of vehicle relative to the inertial space.Then the position,attitude and velocity of the vehicle can be obtained through calculation of the data measured in real-time.In the several decades,inertial technology has developed fast,especially in military fields.It come to attention by the features of autonomy,real-timing and unconstrained to time and space.The rotation modulation technology belongs to error compensation which periodically changes the forms of sensitive sensors to compensate the navigation error,improving the precision significantly.The main works are as follows:Firstly,common coordinate frame of rotating FOG strapdown inertial navigation system and its conversion relation is expounded.Then dual-axial 4-position and 16-order rotation scheme is introduced.And to verify the effectiveness of the scheme,the simulation results of the dual-axial rotary scheme are showed.Secondly,on the basis of the scheme mentioned above,optimal design of the parameters in the rotary process and the compensation of the errors are studied.And the modulation results of the improved rotation schemes are proposed theoretically and in simulations.To further improve the precision of navigation,how the angle measurement device affect the vehicle's attitude angle is analyzed.And the error of the angle measurement is modeled and compensated.Second-order hold is designed to solve the problem that the output of the IMU and the output of the angle measurement device are out of sync.Finally,rotary strapdown inertial navigation system is difficult to realize self-alignment on dynamic base.To solve the problem,an alignment method based on inertial reference frame is designed.Based on the coarse alignment results in the inertial frame,the initial fine alignment error model of a dual-axis rotation modulation of rotary SINS in the inertial frame is derived.Then,aiming at the noise uncertainty of the observation model,by changing the embedded manner of fading factors,an improved adaptive Kalman filter based on multiple fading factors is proposed to realize rapid and accurate alignment.