Abstract:

In this research, a new Integrated Adaptive Guidance algorithm is developed for a class of Reusable Launch Vehicles (RLVs) that perform suborbital flight. This simple and elegant guidance approach can cater to ascent as well as re-entry phases (from lift off to touch down) of any RLV mission, irrespective of the type of propulsion being employed, rocket or air-breathing. This poses a challenging task to a guidance designer as the ascent and descent flight of the vehicle is completely within dense atmosphere where aerodynamics plays a key role in defining the flight path of the vehicle. An adaptive guidance scheme is proposed for this class of missions. To be called "adaptive", guidance approach should have one or both of the following elements. (i) The reference trajectory should be generated on-line in response to actual flight conditions, or (ii) there are on-line closed-loop adjustments of guidance parameters. This new improved algorithm has both the above mentioned features, namdy, on-line generation of optimal reference trajectory based on energy state approximation approach and a non-linear guidance law with adaptive gains for tracking the trajectory generated on-board. The scheme is simple and suitable for on-board implementation. Accuracy achieved is also high since the guidance strategy is based on reference trajectory and guidance gains that are computed online based on actual flight conditions. This work has resulted in the formulation of a single integrated guidance scheme from lift off to touch down, that is independent of the type of RLV mission, nature of propulsion being employed, or phases of flight.