GES Attitude Observers - Part I: Multiple General Vector Observations

Abstract: This paper proposes a set of observers for attitude estimation based on multiple general time-varying reference vectors, in inertial coordinates, and corresponding vectors, in body-fixed coordinates, in addition to angular velocity readings. The observer error dynamics are globally exponentially stable (GES) and problems such as singularities, unwinding phenomena, or topological limitations for achieving global asymptotic stability are absent. Although the observer estimates do not evolve on the Special Orthogonal Group SO(3), a final solution is provided, on SO(3), whose error is shown to converge to zero for all initial conditions. The proposed solutions are computationally efficient and simulation results are shown that illustrate the achievable performance.