Designing for damage—robust flight control design using sliding mode techniques

Abstract

Abstract

A brief review of sliding mode control is undertaken, with particular emphasis upon the effects of neglected parasitic dynamics. Sliding mode control as implemented with boundary layers is then interpreted in the frequency domain. The inclusion of asymptotic observers and reference model “hedging” is shown to reduce the effects of neglected parasitic dynamics. Application of the resulting observer/hedging-based sliding mode technique to the design of a robust longitudinal control system for a highly unstable aircraft is described. The sliding mode controller is shown to exhibit stability and performance robustness superior to that of a classical loop-shaped design when significant changes in vehicle and actuator dynamics are employed to model airframe damage.