Research On Aircraft Attitude Determination Algorithms Based On Nonlinear Filtering

With the rapid development of sensor technology, computer technology, andintelligent information processing technology, various aerospace vehicles which meetdifferent functional requirements are widely used in the military and civil fields. Thedifferent functional requirements and the complexity of application environments,lead to the demand of accuracy and stability of the aircraft attitude determinationalgorithms, which are used as the moving vehicle platform, is constantly increasing.So it is of great theoretical and practical significance to research aircraft attitudedetermination algorithms.According to different demands of application scenarios and performances of theaircraft, we can use different attitude measurement systems, but the nature of thesystems is based on nonlinear filters. Currently widely used aircraft attitudedetermination algorithms, which are based on the nonlinear filter, such as EKF andUKF, have defects of relative big estimate error and low stability. In view of thedisadvantages aforementioned, firstly, we utilized a new SCKF to research the attitudedetermination algorithms of two kinds of aircrafts with different attitude sensors, andthen according to multisensor attitude measurement systems, we proposed threecentralized nonlinear fusion algorithms based on UIF, and compared and analyzed theperformance of them by the simulation of bearings-only target tracking system andmultisensor attitude measurement system. The main contributions of this thesis are asfollows:1) We propose a new attitude determination algorithm for MAV based on SCKF.Firstly, quaternion and gyro bias are regarded as state vector; Euler angles are treatedas measurement vector. Then, we establish state equation based on strapdown methodand gyro bias model, meanwhile, make use of the relationship between Euler anglesand quaternion to model measurement equation, and take the attitude information gotfrom the bi-vector method as the measurement update. Subsequently, the attitudedetermination algorithm based on SCKF is designed. At last, simulation examples areillustrated to verify the efficiency of the proposed algorithm.2) We propose a new spacecraft attitude determination algorithm based on SCKF.This paper utilizes GRPs and gyro bias as state variables, and uses quaternionkinematics equation for attitude propagation. After that, we get two unparallel vectorobservations as measurement vector, and establish the measurement equation according to star sensor observation model. At last, the SCKF algorithm used forspacecraft attitude determination is designed, and the simulation results are comparedbetween the proposed algorithm and the one based on UKF.3) For the nonlinear system, this paper proposes three centralized fusionestimation algorithms based on UIF. Then, we compare and analyze their respectiveperformance. After that, multisensor bearings-only target tracking system andmultisensor attitude measurement system based on the model of 1) are simulated toverify the conclusions of the three fusion algorithms.