Theta-D Control Technique for Ascent Phase of Reusable Launch Vehicles


Current flight control of reusable launch vehicles is based on table look-up gains for specific flight conditions. A new suboptimal nonlinear control technique for the complete ascent phase of reusable launch vehicles is presented in this paper. The new technique, called the θ-D method, is synthesized by adding perturbations to a typical optimal control formulation with a quadratic cost function. The controller expressions are obtained by getting an approximate closed-form solution to the Hamilton-Jacobi-Bellman equation. The θ-D method avoids iterative online solutions. A controller using this new method has been designed for the ascent phase of a reusable launch vehicle and implemented in a six degrees-of-freedom high fidelity simulator being run at the NASA Marshall Space Flight Center. Simulation results show that the θ-D controller achieves accurate tracking for the ascent phase of the reusable launch vehicle while being robust to external disturbances and plant uncertainties.

Meeting Name

AIAA Guidance, Navigation, and Control Conference and Exhibit 2004 (2004: Aug. 16-19, Providence, RI)


Mechanical and Aerospace Engineering

Keywords and Phrases

Ascent Phase; Reusable Launch Vehicles; Θ-D Method

Document Type

Article - Conference proceedings

Document Version


File Type





© 2004 American Institute of Aeronautics and Astronautics (AIAA), All rights reserved.

Publication Date

19 Aug 2004

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