Design for Robust Aircraft Flight Control

A frequency-domain-based synthesis technique using pseudosliding-mode control has been previously introduced and exercised in the literature. The current research is aimed at presenting the design framework in a detailed, step-by-step fashion for use by those who may initially be unfamiliar with the robust flight control design methodology. The technique is exercised by designing a longitudinal flight control system for a model of a flexible aircraft. The resulting design is evaluated in a computer simulation that includes a model of the human pilot. Handling qualities predictions are included. To assess robustness, the simulations include abrupt variations in the characteristics of the aircraft control system and vehicle dynamics. A brief, human-in-the-loop tracking study is also undertaken to corroborate the results. Of particular relevance to the practicality of the design approach is the fact that no adaptation occurs (i.e., the sliding-mode control system elements remain invariant throughout).