Online parameters estimation for reentry vehicle in the hypersonic regime

The present work was carried out in the framework of the Unmanned Space Vehicles (USV) program, executed by the Italian Aerospace Research Centre (CIRA), with the aim of developing innovative GN&C technologies focused on a complete autonomous atmospheric reentry, including hypersonic flight and landing. In particular the investigation of advanced concepts for online trajectory generation during hypersonic re-entry with the adoption of adaptive guidance laws based on modulation of both bank angle and the angle of attack may represent a significant improvement of guidance flexibility. In order to autonomously adapt the on-board generated trajectory to the current flight conditions without violating any of the required thermal, structural and operational constraints an estimation of some vehicle parameters is necessary. In particular an identification of the aerodynamic coefficients and the velocity of the vehicle is essential to correctly evaluate the constraints during reentry. At this purpose an Extended Kalman Filter (EKF) has been implemented and tested in a reference simulated scenario.