Application of an Optimization-based Design Process for Robust Autoland Control Laws

Abstract

The design of a robust autoland controller using an optimization based design process is described. A modular controller architecture is developed first. Inner loops are based on Dynamic Inversion, speed and longitudinal path tracking loops are based on the Total Energy Control System. Functions for lateral path tracking, ILS guidance, flare and runway alignment are based on classical PID structures. The free parameters in the controller functions are tuned using multi-objective optimization. Performance criteria are directly derived from the imposed design requirements and computed from linear or nonlinear analysis (e.g. eigenvalues, simulations). Robustness is addressed via a multi-model approach, via optimization criteria (e.g. gain/phase margins), and, as a new contribution, via statistical criteria computed from on-line Monte-Carlo analysis. The design process and selected architecture have been applied to a wide-body as well as a small passenger aircraft to demonstrate controller robustness and efficiency of the process. In both cases, JAR-AWO specifications had to be met. The latter design was successfully flight tested.