Model following flight control system design for ATTAS, DFVLR's new in-flight simulator

Abstract

The content of this paper describes the theoretical development and nonlinear digital simulation results of the model following flight control system for DFVLR's new in-flight simulator ATTAS. A detailed description of the manner in which the feedforward and feedback gains are obtained using an interactive computer aided design technique is given. The feedforward gain matrices are obtained using the controllable companion form. Additional filters in the forward loop enables the gains to be made independent of the model aircraft parameters. The feedback gains are obtained by using a vector optimization technique. Several time and frequency domain criteria are used to obtain the required performance. Modified robustness measures based on singular value decomposition are derived and used to constrain the feedback gains. The sensitivity of the model following system to changes in flight condition is minimized using a multi model formulation. Non-linear simulation results are presented to show the quality of model following and substantiate the theory and procedure.