A low-cost INS/GPS tight integration for re-entry navigation

In this paper a sensor fusion algorithm is presented, providing accurate and reliable Position, Velocity and Attitude estimations during a reentry flight. This algorithm continuously corrects the IMU outputs using the raw information coming from the GPS receiver such as pseudoranges and pseudorange rates. The main peculiarities of this algorithm are the use of a low-cost IMU and the tight integration of the Drag Derived Altitude, pseudo-measurement typically involved in the vertical channel stabilization during reentry missions. The shown accuracies are comparable to obtained ones using a high-grade IMU but with relevant saving of money, dimension and weight, features of paramount importance for Reusable Launch Vehicles but for aeronautical applications too.