Evaluation of attitude determination methods for aircraft using GPS signals13;

In this paper,several efficient algorithms are implemented and evaluated for estimating the attitude of an aircraft using global positioning system(GPS)signals and validated with simulated data set. Algorithms for GPS attitude determination using carrier phase measurements can be broken into integer resolution and attitude calculations. In the current work,it is assumed that the integer ambiguity is solved. The phase difference between the signals arriving at the GPS receivers is measured.The phase difference can also be calculated analytically using the attitude matrix(which is unknown)and other parameters.A cost function is defined as the difference between the measured phase difference value and the calculated value.The algorithms discussed tend to minimize the cost function by updating the attitude matrix(or equivalent attitude parameters).13; It can be seen that all the algorithms except QUEST(Question Estimators) have better final attitude quaternion.But since QUEST being as the numbers of satellites tracked are reduced.The number of satellites tracked is desired to be minimum as it reduces the number of calculations. One of the advantages of QUEST is that it does not need to be initialized with an initial quaternion.Also the QUEST algorithm provides the optimal starting value of quaternion for the attitude estimation using other iterative approaches. Other algorithms like Newton-Raphson discrete, Newton-Raphson continuous and eigenvalue problem have better accuracy and less number of iterations,but coplex calculations like matrix inversion(5*5 matrix),estimation of eigenvalues and eigenvectors are involved