ETD system

Electronic theses and dissertations repository


Tesi etd-11242008-231134

Thesis type
Tesi di dottorato di ricerca
H_infinity Loop-Shaping Control of Aerospace Systems
Settore scientifico disciplinare
Corso di studi
Relatore Prof. Mengali, Giovanni
Parole chiave
  • multivariable
  • loop-shaping
  • H_infinity
  • control
  • robust
  • singular values
Data inizio appello
Riassunto analitico
Loop-Shaping design with H_infinity controller synthesis plays a role of primary importance for the synthesis of robust multi-variable controllers. However, a typical difficulty is that<br>the designer has to develop considerable expertise in this matter before obtaining good results. In fact, the choice of the weighing matrices, that are at the heart of the loop-shaping design, is not an easy issue.<br>The aim of the work described in this dissertation is to improve the well known H_infinity loop-shaping approach, by simplifying the shaping procedure and by extending its range of effectiveness, through some useful additions helping the designer in the controller synthesis.<br>The first major improvement consists in the definition of a scaling method aiming to minimize the condition number of the plant. This simplifies the choice of weights and increases the closed-loop robustness.<br>A second important addition is the development of a design procedure helping the designer in the selection of non-diagonal weights, which seems the best solution to overcome difficulties related to plants with highly coupled dynamics.<br>A Matlab software package has been created, which implements the proposed design procedures and assists the designer by simplifying the shaping activity and reducing his/her amount of work.<br>The exposed design methodologies are validated through some case studies, where typical problems of flight control system design are dealt with. These applications are illustrated with the aid of a Matlab/Simulink linearized model of an aircraft.