Applications And Research Of Attitude Determination Algorithms Based On Multi-antenna Synchronized GPS System

With the development and application of GPS technology,the demand of high precision attitude determination based on GPS increase greatly.In comparison,GPS attitude determination technology based on short baseline shows great advantages in long-term stability and accuracy,while inertial navigation system has several major disadvantages,including error accumulation,longer boot time and higher cost.Especially with the advent of a new multi-antenna synchronized receiver(MS receiver in short),which can eliminate the satellite and receiver clock simultaneously through single-difference(SD)rather than double-difference(DD).Such a unique advantage indicates a potential possibility of improving the accuracy and stability of attitude determination system based on this type of receivers.However,this MS receiver is still not being fully exploited because of two reasons.First,the attitude determination system based on MS receiver still prefers to use DD model due to many popular algorithms of integer ambiguity resolution are proposed.Second,MS receivers show great potential in some precise GPS applications,while little research has been done in this field.In this paper,we explore the potential of this receiver in attitude determination algorithm and other high precision GPS applications.With the background and technological objectives of the NSFC project "The Research of High Precision Multi-antennas Beidou/GPS Receiver Modelling and Key Technologies" and the Science and Technology Commission of Shanghai project "The Research and Demonstration Application of Multi-antenna GPS/Beidou receiver",this thesis aims at investigating the potential of the MS receiver with SD model to further improve its accuracy and flexibility on attitude dtermination system or extend its applications.The main work of this research are presented as follows:1.The theoretical analysis of error and accuracy for attitude determination algorithm using SD model based on MS receiver.At first,this thesis analyzes the equivalence problem of formal uncertainty between SD model(using MS receiver)and DD model in theory,then uses asymptotic analysis to discuss the dispersion differences between two models,finally the above conclusion is verified through lot of static and kinematic experiments.Theoretical analysis and experiment results show that SD model using MS receiver performed well in attitude determination,especially the accuracy and stability of pitch angle,even can catch the tiny variation of pitch angle(1°-3°),while DD model and other commercial attitude determination systems might not achieve.2.The ambiguity substitution approach(ASA)for the SD model based on MS receiver.Although SD model has great advantages in attitude determination,the SD ambiguity is not integer and not easy to fix.ASA approach firstly merges the ambiguity of reference satellite and UPD parameter into a new UPD parameter,and avoids the problem of rank deficient due to the existence of UPD parameter,which also maintains the integer property of ambiguity.Then,based on the theory that the correlation between ambiguities decreases with the increasing number of fixed ambiguity,bootstrapping approach is used to fix the ambiguity step by step.This approach has major advantages as simple,high efficiency and high accuracy,and thus it is suitable for real-time attitude determination system.Based on this algorithm,areal-time attitude determination system(RPAD)using MS receiver are implemented.The static and kinematic experiments are carried out,and the results shows that the RPAD system has an attitude determination accuracy of 0.23° and 0.200° for yaw and pitch angles respectively under about 2 meter baseline.3.Yaw angle determination using single antenna based on GPWU effect.Based on the research of attitude determination system using MS GPS receiver,GPWU effect is extracted successfully and shows high correlation with the variation of yaw angle.According to this property,we explore the feasibility of yaw angle determination using single antenna based on GPWU effect.This approach aims at measuring the yaw angle of slowing rotating platforms,such as cars and ships,however significant error may be introduced into GPWU estimation by ionospheric delay that can be ignored in fast rotating platform.Moreover,the theoretical analysis of GPWU high order effect is important to compensate the lack in present theory.Finally,through a bunch of experiments,the feasibility and performance in real-time yaw angle determination is validated,and this method is able to determine the yaw angle with a minimum one satellite,which provides potential applications for attitude determination in the environment with poor sky visibility.4.The feasibility analysis of MHM approach in kinematic shipborne environment.On the basis of our research group proposed MHM approach,which takes advantage of the spatial repeatability of the multipath effect under an unchanged environment,we expanded the MHM approach to a kinematic shipborne environment.Considering that the attitude determination system based on MS receiver can eliminate most common errors,and ensure that the residual error mainly comes from the multipath effect,and thus it provides an "ideal"platform to verify the feasibility of MHM approach in kinematic platforms.Through static and kinematic shipborne experiments,the feasibility and performance of MHM approach is verified.The results indicate that,after MHM multipath mitigation,the RMS of residual values are reduced by 39.89%and 21.91%for the static and kinematic tests,respectively.So it provides a significant reference for multipath mitigation in kinematic platforms.