Sub-Optimal Analytic Guidance Laws for Reusable Launch Vehicles

Abstract

This paper presents a guidance scheme for the Terminal Area Energy Management (TAEM) and Approach and Landing phases of flight for the next generation of reusable launch vehicles (RLVs). the guidance scheme presented is developed in two parts, the kappa guidance section and the touchdown trajectory section. the kappa guidance section begins at the TAEM interface and continues until 475m slant range before the desired touchdown point. the touchdown trajectory section begins at the 475m slant range interface and continues until the RLV reaches the desired touchdown point. the guidance algorithm for the kappa guidance section is an approximate analytic solution to the nonlinear optimization of minimizing the final velocity of the trajectory while meeting a constraint on the final flight path angle. the assumptions used to develop the approximate analytic solution begin to degrade this guidance algorithm's performance near the touchdown point; therefore, the touchdown trajectory section was incorporated into the guidance scheme. This guidance algorithm uses linear quadratic regulator control theory to find the change in angle of attack from the nominal that produces a desired touchdown rate at the touchdown point. Both guidance algorithms have "trajectory shaping parameters" which help meet the final constraints for each section. These parameters have a relationship with both velocity and flight path angle which is approximated by neural networks. the combination of these two guidance algorithms yield a wide range of allowable initial conditions that an RLV can have and still be able to land with a desirable touchdown rate at the touchdown point. © 2003 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Department(s)

Engineering Management and Systems Engineering

International Standard Book Number (ISBN)

978-156347978-6;978-162410090-1

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Institute of Aeronautics and Astronautics, All rights reserved.

Publication Date

01 Dec 2003

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