Research On Transfer Alignment Of Carrier-Based Aircraft Strapdown Inertial Navigation System

Airpower is so important that The United States has published that who can commandthe air will win the war, and Carrier-Based Aircraft is an powerful weapon in commanding inthe air. In order to improve the Carrier-Based Aircraft’s ability of fast reaction and Precisionstrikes, The initial alignment of the INS on Carrier-Based Aircraft must be complete quickly.Therefore, we often use the high-precision MINS on the carrier to align the NINS on theCarrier-Based Aircraft. The transfer alignment of the Carrier-Based Aircraft is different fromof the Ship-borne weapons. The main difference is that in the transfer alignment ofCarrier-Based Aircraft the Lever-arm is unknown、Large Azimuth Misalignment and therapid transfer alignment in critical situation. Therefore, this paper will made research on theproblem mentioned above.First，considering with the transfer alignment of ship-based Strap-down inertial navigationtransfer, I have deduced the state equation and observational equation of the Speed matched、Attitude matched、Speed and attitude matched and Speed and angular velocity and set up thekalman filter, In view of the four methods above，I made the simulation analysis in fourkind of environment.and made deep research on the characteristics of them. Speed matchedmethod is the only one that can Complete transfer alignment when the carrier have no anymobile, But its azimuth angle converge too slowly. When the carrier has the Angle motion, theother three methods can converge quickly and have a high precision. The speed and angularvelocity matched have the fastest convergence rate, and the Speed and attitude matched havethe second. But the speed and angular velocity matched is more sensitive to the bendingdeformation, in the calm sea environment its performance of simulation is the best. But whenin a poor sea environment the Speed and attitude matched method have a stable performance.Secondly, this paper made a research in factors which Influence the precision of transferalignment. Specially in the lever-arm effect and bending deformation. When the length oflever arm is unknown, I offer two methods to deal with this station, one is Calculation methodand the other is Estimate method. When the length of lever arm is given, compensationmethod of lever arm effect is studied by compensating accelerometer’s output. Then,compensation method of flexure deformation is studied deeply. In consideration of ship’sno-rigid situations, new expressions of lever arm acceleration and velocity are derived basedon the flexure deformation model. A new compensation method is then proposed tocompensate both the flexible lever arm effect and flexible deformation by establishing a unified model of them.Finally, in the theoretical foundation mentioned above, I offer three methods about thetransfer alignment of Carrier-Based Aircraft. The first one, the NINS will make a coarsealignment before transfer alignment. The method can deal with most cases ship-bornemachine initial alignment. The second methods is according to real with the Large AzimuthMisalignment. The traditional methods is by using nonlinear filtering, general is EKF or isUKF, but when using the EKF it have to compute the Jacques than matrix, large amount ofcalculation slow the convergence speed. Although UKF have a high speed than the EKF but italso have an introducing linear error. Therefore this paper proposes using UKF+Kalmanfiltering method is the second。Can effectively improve the azimuth Angle of deviation of bigtransfer alignment precision and speed。The third design is based on the established isnominal coordinate rapid transfer alignment method.