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Backstepping and control allocation with applications to flight control
Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
2003 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

In this thesis we study a number of nonlinear control problems motivated by their appearance in flight control. The results are presented in a general framework and can also be applied to other areas. The two main topics are backstepping and control allocation.

Backstepping is a nonlinear control design method that provides an alternative to feedback linearization. Here, backstepping is used to derive robust linear control laws for two nonlinear systems, related to angle of attack control and flight path angle control, respectively. The resulting control laws require less modeling information than corresponding designs based on feedback linearization, and achieve global stability in cases where feedback linearization can only be performed locally. Further, a method for backstepping control of a rigid body is developed, based on a vector description of the dynamics. We also discuss how to augment an existing nonlinear controller to suppress constant input disturbances. Two methods, based on adaptive backstepping and nonlinear observer design, are proposed.

Control allocation deals with actuator utilization for overactuated systems. In this thesis we pose the control allocation problem as a constrained least squares problem to account for actuator position and rate constraints. Efficient solvers based on active set methods are developed with similar complexity to existing, approximate, pseudoinverse methods. A method for dynamic control allocation is also proposed which enables a frequency dependent control distribution among the actuators to be designed. Further, the relationship between control allocation and linear quadratic control is investigated. It is shown that under certain circumstances, the two techniques give the same freedom in distributing the control effort among the actuators. An advantage of control allocation, however, is that since the actuator constraints are considered, the control capabilities of the actuator suite can be fully exploited.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2003. , 231 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 820
Keyword [en]
backstepping, control allocation, flight control, control theory, nonlinear control, reglerteknik
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-23177Local ID: 2583ISBN: 91-7373-647-3 (print)OAI: diva2:243491
Public defence
2003-05-23, Visionen, Hus B, Campus Valla. Linköpings Universitet, Linköping, 10:15 (Swedish)
Available from: 2013-04-22 Created: 2009-10-07 Last updated: 2013-04-23Bibliographically approved

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