Research Of Alignment Technology For Shipboard Fog Strapdown Inertial Navigation System

With a series of advantages, such as small size, easy to install and easy tomaintain, SINS is the main development direction of inertial navigation system.With the development of fiber optic gyro technology, marine fiber optic gyrostrap-down inertial navigation system has developed rapidly. Initial alignment erroris directly related to the navigation system navigation accuracy, therefore, the initialalignment study is particularly urgent. In this article, contrary to the characteristicsof marine fiber optic gyro SINS, SINS initial alignment is simulated. The maincontents include:The basic theory of SINS is introduced, including the common coordinatesystem, gyroscope and accelerometer error model, the speed error equation, theposition error equation and attitude error equation. Introducing the principle ofKalman filtering, Kalman filter equations are derived. It Analyzed the basicprinciples of the INS coarse alignment and fine alignment. Simulation is wellbehind the theoretical foundation.Introducing the basic principles and Square of compass alignment, thenestablished compass alignment error equations. Under the same conditions,simulating with the Kalman filtering method, the simulation results were compared.In the theoretical view, based on feedback control, compass alignment and Kalmanfiltering method steady-state error formula is derived. Comparative analysis on thesteady-state error, pointed out the various error factors. Compass alignment’ssteady-state error will vary with the control parameters. According to a set ofmeasured data, it used compass alignment to simulation and verification.For ship’s transfer alignment technology, primary INS and sub INS velocityand attitude error equations are derived. It Established a lever-arm effective andflexural dynamic error model to simulate reality. Derived velocity matchingalignment, posture matching alignment and posture matching acceleration filtermodel matching method, using gesture acceleration matching alignment method tosimulate. Building error models, set various parameters to simulate in threedifferent sea conditions. Useing Kalman filtering method to complete the transferalignment simulation, and simulation results were compared and analyzed. In the condition of large misalignment angles, SINS additive attitude errorquaternion equations and velocity error equations were derived. Introducing theprinciple of the extended Kalman filter and unscented Kalman filter, thenestablished error models. Setting three different sets of initial misalignment angle,respectively EKF and UKF simulation, compared the two filtering algorithm impacton the simulation results.