Project Summary

Proposal Number: 970114
Project Title: Intelligent, Gain Scheduled, Differential Throttling, H? Control of Aerospike Space Transportation Systems
Small Business Concern:: American GNC Corporation
9131 Mason Avenue
Chatsworth, CA 91311
Research Institution:: University of Southern California
3440 S Hope St.
Los Angeles, CA 90089-2563
Principal Investigator/Project Manager:: Ching-Fang Lin
Technical Abstract:: NASA is considering the Single Stage To Orbit (STTO) concept. The breakthrough technology of aerospike engines has made rocket propulsion so much more efficient that STTO vehicles can now be seriously considered in a foreseeable future. Both the X-33 and the Venture Star will be equipped with aerospike engines. However, aerospike engines pose new control challenges -- they cannot be gimballed like conventional rocket engines; they are fixed relative to the rocket structure; therefore, aerospike engine rockets will have to be controlled by differential throttling. This project is aimed to transfer our experience and techniques in Propulsion Controlled Aircraft (PCA) control system design to NASA and solve this challenging problem. Especially, a multilevel aerospike space transportation control system based on H? model matching, and topological, intelligent, robust/nonlinear gain scheduling control will be designed to ensure good performance of the control system over the whole flight envelope. Design and analysis algorithms will be developed and a software environment with a graphical user interface will be implemented to synthesize, simulate, and evaluate the designed control system. Our experience makes us uniquely qualified to design the differential throttling control system of such advanced aerospike space transportation systems as the X-33 and Venture Star.
Potential Commercial Applications:: With the commercialization of space afforded by aerospike engines, the need for "fly-by-throttle" concepts will be increasing. With more and more sophesticated aeropace structures being considered -- stealth aircraft without vertical fins, flying wings -- that do not have conventional control surfaces but that will be flown by pilots used to fly aircraft with conventional control surfaces, the need to make these structures "feel" like a conventional aircraft will make our model matching concept more and more important.