An Invariant Observer for Earth-Velocity-Aided Attitude Heading Reference Systems

Abstract : In this paper we propose an invariant nonlinear observer (i.e. a “filter”) for estimating the velocity vector and orientation of a flying rigid body, using measurements from low-cost Earth-fixed velocity, inertial and magnetic sensors. It has a nice geometric structure which respects meaningful physical symmetries of the system. It can be seen as an easier-to-tune and computationally much simpler alternative to an Extended Kalman Filter.