VSTOL aircraft control system design using scheduled H∞ controllers

An approach to designing robust control laws for nonlinear plants where the main nonlinearities of the plant can be captured by one or more scheduling parameters is developed. It is shown that this approach can easily meet the performance specifications for the generic VSTOL aircraft model, and gives rise to an overall system with good robustness margins. These robustness levels can be very close to optimal with a modest number of design points. The H∞/loop-shaping approach is found straightforward to use, particularly in that selection of weighting functions to meet performance requirements is very intuitive. The scheduled observer approach outlined also lends itself well to analysis using the structured singular value