21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-1.6.3

ROBUSTNESS ANALYSIS APPLIED TO AUTOPILOT DESIGN PART 3: PHYSICAL MODELING OF AIRCRAFT FOR AUTOMATED LFT GENERATION APPLIED TO THE RESEARCH CIVIL AIRCRAFT MODEL

Moormann D., Varga A., Looye G., Grubel G.
DLR, Germany

Keywords: robustness analysis, autopilot design, physical modeling of aircraft , automated lft generation, civil aircraft model

In this contribution the automated generation of LFT-based parametric uncertainty descriptions from a generic nonlinear aircraft dynamics model, as used for the GARTEUR RCAM Design Challenge on Robust Flight Control, is described. For this purpose an object-oriented, equation-based modeling approach using the modeling environment Dymola was applied. Using this technique allows the modeling of physical systems as physical objects and phenomena, which are connected according to their physical interactions. This modeling in form of equations (not assignments!), as required for automated LFT generation, is different from modeling via signal flows or input-output block diagrams, as traditionally used for controller modeling. All necessary components are taken from an aircraft object library developed for this purpose. Different representations of one component may be present to allow model building of different complexity or various functionalities. By automatic equation manipulation a symbolic model code is generated from the parameter instantiated equations of each object and from the equations derived from the interconnection structure. This code is the base for an automated generation of the LFT-based parametric uncertainty description.

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