Kinematic State Reconstruction of Miniature Atmospheric Re-Entry Vehicles

An algorithm for the reconstruction of the kinematic states of a miniature atmospheric re-entry vehicle is presented. This is motivated by the emergence of several miniature sample return vehicles, as well as novel hypersonic flight testing concepts that achieve hypersonic flight by inserting test articles into Low Earth Orbit and then deliberately de-orbiting them. Given the severe size and weight constraints of the re-entry vehicles in these concepts, the use of accurate inertial sensors is not possible. Furthermore, Global Navigation Satellite System (GNSS) measurements will not be available during all phases of re-entry. The algorithm presented uses a smoother to retroactively improve the state estimates of the vehicle during periods when GNSS is unavailable. Simulation results show that state estimates of position and velocity can be achieved with errors of around 1.5 meters and 1.0 meter per second (one standard deviation) using consumer-grade inertial sensors whenever GNSS measurements are available. When GNSS measurements are not available due to a communications blackout, the smoothing significantly reduces the estimate uncertainties. Low attitude estimate errors are achieved using a magnetometer triad. Also considered is the use of a magnetometer triad to aid in determining the initial attitude for the initialization of the estimator.