Event

Guidance, Control, and Astrodynamics Seminar Series: "Ascent Flight Control of Ares-I Crew Launch Vehicle in the Event of Uncontrolled Roll Drift," Wei Du, AER E Ph.D. Candidate

Wei Du, AER E Ph.D. Candidate

Wei Du, AER E Ph.D. Candidate

Major Professor, Bong Wie

Thursday, November 12, 2009
Room 1235 Howe Hall
4:10 - 5:00 PM

Ascent Flight Control of Ares-I Crew Launch Vehicle in the Event of Uncontrolled roll Drift

The research objective is to develop a quaternion-based pitch/yaw control system for the Ares-I Crew Launch Vehicle without an active control of its roll motion. The roll motion of Ares-I CLV under nominal flight conditions is actively stabilized by its roll control system employing thrusters. This work describes the ascent flight control design problem of Ares-I in the event of disabled or failed roll control. A simple pitch/yaw control logic is developed for such a technically challenging problem by exploiting the inherent versatility of a quaternion-based attitude control system. The proposed scheme requires only the desired inertial attitude quaternions to be re-computed using the actual uncontrolled roll angle information to achieve an ascent flight trajectory identical as the nominal flight case with active roll control. Another approach that utilizes a simple adjustment of the proportional-derivative gains of the quaternion-based flight control system without active roll control is also presented. This approach doesn't require the re-computation of desired inertial attitude quaternions. A linear stability criterion is developed for proper adjustments of attitude and rate gains. The linear stability analysis results are validated by nonlinear simulations of the ascent flight phase. However, the first approach requiring a simple modification of the desired attitude quaternions is recommended for the Ares-I as well as other launch vehicles in the event of no active roll control. At last, the comparison of attitude quaternions feedback and Euler angles feedback shows the limitation of Euler angles scheme in this kind of application.Brief Bio:Wei Du is a Ph.D. candidate in the Department of Aerospace Engineering, whose advisor is Prof. Bong Wie. His research focuses on the flight dynamics and control, especially the launch vehicle control system design. He is also interested in spacecraft modeling, advanced control theory and application. Wei Du received his MS in Spacecraft Design from Beijing University of Aeronautics and Astronautics (Beihang University) in April 2007. And he earned his BS in Automation from Tsinghua University in July.