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NIA Seminar by Lesley Weitz |
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Date: May 22, 2007
Time: 10:30am
Location: NIA, Rm 137
Additional Information: Presentation (.pdf)
Control-Law Design and Stability Analysis for Multi-Vehicle Formations
Lesley Weitz, Texas A&M University
Cooperative control of multi-body systems is an emerging research area with applicability to several problems including formation control and autonomous inter-vehicle spacing. In many cases, these control concepts are investigated for large numbers of vehicles, and hence would require a decentralized implementation. This presentation presents an overview of our research in the area of decentralized, cooperative control design for multi-vehicle systems.
The first part of the research explored formation control using a commonly-used kinematics model that can represent vehicles with zero or negligible velocity in the lateral direction. The traditional model representation is nonlinear and underactuated, and this complicates a linear control-law design technique. However, this nonlinear model is differentially flat, which means there is a coordinate transformation that maps the original nonlinear, underactuated representation into a linear, fully actuated system with some modest restrictions. This property significantly eases control-law design. I will present some cooperative control laws based upon a leader-follower communication structure in which the control-law design exploits the differential flatness property of the nonlinear model. In addition, I will show that the structures of these control laws are amenable to evaluating stability in the presence of communication delays. Again, a coordinate transformation can be used to determine the maximum allowable time delay in a multi-vehicle system.
Whereas the previous control laws were based upon fixed-distance spacing, some autonomous vehicle-spacing concepts, such automated highway systems and terminal-area approach spacing of aircraft, have utilized constant-time spacing. We have investigated the fixed-time spacing problem by expressing a time-to-go metric using an optimal-control formulation to minimize control effort. One development follows from a prelinearized representation of the aforementioned nonlinear vehicle model that I will detail in the presentation.
Our ultimate goal is to apply the results gained from the previously mentioned research to develop optimal-control based concepts for Next-Generation Air Traffic Management Systems.
Lesley Weitz is a National Science Foundation Graduate Research Fellow in the Aerospace Engineering department at Texas A&M University in College Station, TX. She graduated with her Master of Science in Aerospace Engineering in August 2005, and she is currently pursuing her PhD in the dynamics and control area under the advisement of Dr. John Hurtado. Ms. Weitz is also an Amelia Earhart Fellow, Tau Beta Pi Fellow, and a NASA Texas Space Grant Consortium Fellow. Her research interests include dynamical modeling, cooperative control, and optimal control of multi-vehicle systems.
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