Design And FPGA Implementation Of Dual-antenna GPS Attitude Determination System

With the rapid development of autopilot technology,high-precision and high-real-time attitude measurement system has become a very important part of navigation system.To achieve the purpose of automatic navigation that the current attitude information of the carrier is known,and the trajectory of the carrier in the future can be predicted.Using the mature global positioning system,the GPS signal receiver is placed at a specific position of the carrier,and the attitude Angle information of the carrier can be obtained by analyzing the ephemeris,pseudo-distance and carrier phase data received by the antenna.In this thesis,a GPS attitude measurement algorithm based on FPGA is proposed that based on the measurement method of two antennas placed at both ends of the carrier spindle,and on the basis of in-depth research on the GPS attitude measurement algorithm,considering the complexity,real-time performance and FPGA resource characteristics of the algorithm.The main work of this thesis is as follows:Firstly,the realization scheme of GPS attitude measurement algorithm is designed.The satellite position information is obtained by calculating the satellite ephemeris.The observation model of GPS attitude measurement is established by using the pseudo range and carrier phase data observed by dual-antenna.,the floating-point solution and integer ambiguity of baseline vector are obtained that use the weighted least square method to solve the observation model;Lambda algorithm is used to search the ambiguity of the whole cycle and get the fixed solution.Then the modified baseline vector is obtained and the attitude angle information of the carrier is calculated.Secondly,design and implementation of GPS attitude measurement algorithm based on FPGA.The design work mainly includes: design interface transmission module;Design four arithmetic modules that support floating-point number;Design solve trigonometric function module that based on pipeline structure of CORDIC algorithm;Design matrix inversion module that based on Cholesky decomposition algorithm;Design a weighted least squares operation module that based on parallel data processing and a loop iterative solution module based on finite state machine.Finally,FPGA design and implementation of GPS attitude measurement algorithm are tested.test the Ethernet port to ensure that the communication between the FPGA board and the host computer is normal;the FPGA implementation of the scheme is tested at the system level.The test results show that the standard deviations(accuracy)of the yaw angle and pitch angle in the calculated carrier attitude angle are 0.213864° and 0.256836°,The above results meet the requirements of attitude measurement accuracy,and the design of the scheme is correct.