Estimation of aerodynamic angles and wind components for a launch vehicle

A technique based on sequential filtering for the estimation of aerodynamic angles and wind components for a launch vehicle (LV) in atmospheric flight is proposed. The estimator is based on an Iterated Extended Kalman Filter, and uses measurement provided by Inertial Measurement Unit, Global Positioning system, and Air Data System. The filter model features the classical equations of aerodynamic angles dynamics in the flight-path frame, together with Gauss-Markov processes for wind velocity and acceleration components, and only relies on a simplified model of lateral accelerations based on the attitude dynamics of LV. The atmospheric phase of flight of a Ares-I LV model is considered in order to assess estimator performance, and the reported results, obtained by simulation, show the suitability of the proposed approach for the estimation of angle of attack and sideslip angle and, with a somewhat higher level of uncertainty, wind speed components. In particular, the method appears satisfying in terms of convergence and capability of extracting the information content, even in cases with limited level of excitation resulting form atmospheric winds and operations on near-nominal flight trajectory.