Drag-Tracking Guidance for Entry Vehicles Without Drag Rate Measurement
This work addresses the practical challenge of drag rate measurement in entry vehicles, offering a robust solution for guidance without requiring additional sensors.
The paper presents a robust entry guidance law for drag-tracking that eliminates the need for drag rate measurement by using a high gain observer to estimate it, achieving input-to-state stability with respect to uncertainties.
A robust entry guidance law without drag rate measurement is designed for drag-tracking in this paper. The bank angle is regarded as the control variable. First, a state feedback guidance law (bank angle magnitude) that requires the drag and its rate as feedback information is designed to make the drag-tracking error be input-to-state stable (ISS) with respect to uncertainties. Then a high gain observer is utilized to estimate the drag rate which is difficult for a vehicle to measure accurately in practice. Stability analysis as well as simulation results show the efficiency of the presented approach.