Résumé:
In this thesis, we treated four attitude nonlinear observers, where the attitude is represented by an orthogonal matrix belonging to the special orthogonal group SO(3).
First, we studied two versions of nonlinear complementary filter recently developed by Soulaimane Berkane, where the gains depend on the state of the system which give an amelioration of robustness
for the perturbations of gyroscopic measures.
Then, we studied also another two nonlinear observers namely, the invariant and the cascaded, developed by Minh-Duc Hua, which use INS/GPS measurements.
Finally, we compared between the four to know which one of them gives a good accuracy at estimating the attitude using MATLAB for simulate the results.
