Robust Performance Analysis Applied to Loads Computation of Flexible Aircraft

This paper demonstrates how the robust performance analysis framework can be used to determine worst case loads of flexible aircraft due to 1-cos gusts. This framework is a part of control theory and is used to characterize a system by input-output norms: e.g. the induced L2-L∞ norm represents the worst case energy-to-peak gain. Two very efficient ways to compute this norm are presented. Based on the physical interpretation of this norm, an aircraft model is weighted such that the induced L2-L∞ norm of the weighted system represents a tight but guaranteed upper bound for 1-cos gusts and similar excitations. The analysis results are compared to simulations. Since the energy-to-peak gain can be computed in a very efficient way for LTI models, the norm is used to quickly obtain an upper bound for loads and to identify critical flight conditions. In a second example, the analysis is additionally performed on an uncertain model