The Rresearch Of Integrated Navigation And Data Fusion Technology For Autonomous Underwater Vehicle

The high precision integrated navigation system(INS) is not only the necessary condition of obtaining effective information about Underwater Vehicle,but also the determining whether it can safely work and return or not.So,the high precision navigation and position technology is one of the key technologies of underwater vehicle.Because the Faraday cage formed by water,many navigation methods based on electromagnetism transiting(such as GPS) are difficult to be realized underwater.The position precision of Dead Reckoning(DR) and Strap-down Inertial Navigation System(SINS) is higher in little time,but the error will be more and more emanative along with time.The information amalgamation of GPS,DR,and SINS is of benefit to increase the precision,reliability,and applicability,which is a developing direction.According to the practical demands,an underwater INS is designed of which the main system is SINS and the accessorial system is DR.DR consists of Doppler Velocity Log (DVL),Electronic Compass(EC),GPS and the speed which is transformed from airscrew. The nonlinear mathematic model of INS is established with the help of the used sensors.The Standard Kalman Filter can not solve the nonlinear mathematic model,and the Extending Kalman Filter(EKF) will consume much more calculation,so Unscented Kalman Filter(UKF) is adopted in this system.Due to the instability of sensors and the uncertainty of outer environment factors,it's difficult to analyze the statistical characteristic of system and observational noise exactly and to ensure the convergence and stability of UKF.Then a self-adaptive UKF is advanced in this paper,and the algorithm is proved by simulation. Federated Kalman Filter will be chosen to be a basic fusion algorithm of INS,which is good at error-allow and design convenience.In order to show the actual course and enhance the precision of DR,not only the new type angle and velocity measurement instruments should be developed,but also the estimate error compensation methods should be researched.The corresponding error compensation methods aiming at different error origins are put forward through the establishing of the error model of DR,and the methods are proved by test.The initial alignment error is one of the main errors of SINS,and it affects the precision directly.An error model of initial alignment with stationary base is advanced,the observation analysis is done,and the corresponding test research is achieved.It is necessary to research the initial alignment technology with moving base because of the environment effects (especially the water waving) on plane-carried,ship-carried,or vehicle-carried during the practical operating.How to quickly achieve a higher precision initial alignment in an abominable environment has a very important significance to enhance the flexibility of INS, and which is researched in the thesis.