TOPIC Approximate Dynamic Programming Based Control
SPEAKER Professor S. N. Balakrishnan 

Department of Mechanical and Aerospace Engineering

Missouri University of Science and Technology
DATE 1 Feb 2011 (Tuesday)
TIME 10:30 am to 11:30 am
VENUE Level 2, Social Robotics Lab, I3 Building,

Interactive Digital Media Institute, 21 Heng Mui Keng Terrace, NUS.
FEES No Charge
ABSTRACT
Current flight control of reusable launch vehicles is based on table look-up values for specific flight conditions.  A new suboptimal nonlinear control technique for the ascent phase of reusable launch vehicles is presented in this paper.  This technique, called the Theta-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 Theta-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 Theta-D controller achieves accurate tracking for the ascent phase of the RLV while being robust to external disturbances and plant uncertainties.
BIOGRAPHY
Professor S. N. Balakrishnan received the Ph.D. degree in aerospace engineering from the University of Texas at Austin, Austin.

He has been with the University of Missouri—Rolla, Rolla, since 1985. Currently, he is a professor with the Department of Mechanical and Aerospace Engineering. His nonteaching experience includes work as a lead engineer in the Space Shuttle program, Fellow, Center for Space Research at the University of Texas at Austin, summer Faculty Fellow at Air Force Research Laboratory, Eglin, FL, and engineer, Indian Space Program. His research interests include areas of system theory and applications. His current research uses neural networks and classical methods in the identification and robust control of missiles, airplanes, rockets, and other “interesting” systems. His research has been sponsored by the National Science Foundation (NSF), the Air Force, the Naval Surface Warfare Center, the Army Space and Missile Defense Command, and NASA.

Dr. Balakrishnan is a member of Sigma Gamma Tau. He is an Associate Fellow of the American Institute of Aeronautics and Astronautics (AIAA)