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space launch system ascent flight control designA robust and flexible autopilot architecture for NASA's Space Launch System (SLS) family of launch vehicles is presented. As the SLS configurations represent a potentially significant increase in complexity and performance capability of the integrated flight vehicle, it was recognized early in the program that a new, generalized autopilot design should be formulated to fulfill the needs of this new space launch architecture. The present design concept is intended to leverage existing NASA and industry launch vehicle design experience and maintain the extensibility and modularity necessary to accommodate multiple vehicle configurations while relying on proven and flight-tested control design principles for large boost vehicles. The SLS flight control architecture combines a digital three-axis autopilot with traditional bending filters to support robust active or passive stabilization of the vehicle's bending and sloshing dynamics using optimally blended measurements from multiple rate gyros on the vehicle structure. The algorithm also relies on a pseudo-optimal control allocation scheme to maximize the performance capability of multiple vectored engines while accommodating throttling and engine failure contingencies in real time with negligible impact to stability characteristics. The architecture supports active in-flight load relief through the use of a nonlinear observer driven by acceleration measurements, and envelope expansion and robustness enhancement is obtained through the use of a multiplicative forward gain modulation law based upon a simple model reference adaptive control scheme.
Document ID
Document Type
Conference Paper
VanZwieten, Tannen S.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Orr, Jeb S.
(Draper (Charles Stark) Lab., Inc. Huntsville, AL, United States)
Wall, John H.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Hall, Charles E.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
June 12, 2014
Publication Date
January 31, 2014
Subject Category
Launch Vehicles and Launch Operations
Report/Patent Number
Meeting Information
2014 American Astronautical Society (AAS) Guidance, Navigation, and Control Conference(Breckenridge,CO)
Funding Number(s)
Distribution Limits
Public Use Permitted.

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IDRelationTitle20140008731See AlsoSpace Launch System Ascent Flight Control Design