Systematic convergence of nonlinear stochastic estimators on the Special Orthogonal Group SO(3)

This paper introduces two novel nonlinear stochastic attitude estimators developed on the Special Orthogonal Group \mathbb{SO}\left(3\right) with the tracking error of the normalized Euclidean distance meeting predefined transient and steady-state characteristics. The tracking error is confined to initially start within a predetermined large set such that the transient performance is guaranteed to obey dynamically reducing boundaries and decrease smoothly and asymptotically to the origin in probability from almost any initial condition. The proposed estimators produce accurate attitude estimates with remarkable convergence properties using measurements obtained from low-cost inertial measurement units. Unit-quaternion representation of the proposed filters are presented. The estimators proposed in continuous form are complemented by their discrete versions for the implementation purposes. The simulation results illustrate the effectiveness and robustness of the proposed estimators against uncertain measurements and large initialization error, whether in continuous or discrete form. Keywods: Attitude estimates, transient, steady-state error, nonlinear filter, special orthogonal group, SO(3), stochastic system, stochastic differential equations, Ito, Stratonovich, asymptotic stability, Wong-Zakai, inertial measurment unit, IMU, prescribed performance function, Euler Angles, roll, bitch, yaw, color noise, white noise, Nonlinear attitude filter, Nonlinear attitude observer, Orientation, nonlinear stochastic attitude filter on SO(3), unit-quaternion based nonlinear stochastic attitude filter, discrete stochastic attitude filter.