# Nonlinear Explicit Stochastic Attitude Filter on SO(3)

## TL;DR

This paper introduces a nonlinear stochastic attitude filter on SO(3) that effectively manages measurement noise, ensuring errors remain bounded and demonstrating robustness through simulations.

## Contribution

It develops a stochastic filter on SO(3) with convergence guarantees and noise attenuation, using Rodriguez vector mapping for improved attitude estimation.

## Key findings

- Errors remain close to the origin in Rodriguez vector space
- The filter is semi-globally uniformly ultimately bounded in mean square
- Simulation shows robustness under high measurement uncertainties

## Abstract

This work proposes a nonlinear stochastic filter evolved on the Special Orthogonal Group SO(3) as a solution to the attitude filtering problem. One of the most common potential functions for nonlinear deterministic attitude observers is studied and reformulated to address the noise attached to the attitude dynamics. The resultant estimator and correction factor demonstrate convergence properties and remarkable ability to attenuate the noise. The stochastic dynamics of the attitude problem are mapped from SO(3) to Rodriguez vector. The proposed stochastic filter evolved on SO(3) guarantees that errors in the Rodriguez vector and estimates steer very close to the neighborhood of the origin and that the errors are semi-globally uniformly ultimately bounded in mean square. Simulation results illustrate the robustness of the proposed filter in the presence of high uncertainties in measurements. Keywords: Attitude, estimate, estimator, observer, filter, stochastic differential equations, SDEs, Ito, Rodriguez vector, special orthogonal group, Euler angles, Brownian motion process, Angle-axis, Mapping, Parameterization, Representation, Partial derivative, asymptotic, unknown, time-varying, global, stable, stability, uncertain, white noise, Gaussian, colored, bias, vectorial, vector measurement, angular velocity, rotational matrix, identity, orientation, body frame, inertial frame, rigid body, three dimensional, micro electromechanical systems, Gyroscope, sensor, Inertial measurement units, IMUs, MEMS, Roll, Pitch, Yaw, autonomous, Robotic System, Spacecraft, submarine, Vehicles, Robot, Underwater vehicle, derivative, explicit complementary filter.