A study of passenger aircraft automatic landing systems

Abstract

This dissertation is concerned with a study for a variety of entry conditions and system disturbance of the dynamic performance of an automatic landing system for use with a large passenger aircraft which employed as its path-deviation sensor an airborne radio receiver suitable for the Instrument Landing System (ILS), the Microwave Landing System (MLS) or Global Positioning System (GPS).

A comprehensive simulation of the dynamics of the chosen aircraft (Boeing-747) was carried out to form the basis of the system simulation. Attitude control systems for both longitudinal and lateral motion were designed using two different control techniques, eigenvalue assignment and linear quadratic regulator theory. A speed control system was also designed to control the aircraft's speed during descent.

Vertical and azimuthal motions were essentially independent when the attitude control systems operated so that the research proceeded by designing a single coupling system to provide automatically horizontal and vertical control of the aircraft's path in which the path deviation sensor could be selected for ILS, MLS or GPS.

Results are shown which indicate that although ILS provides a satisfactory system it is restricted to straight approaches. MLS can provide as good dynamic performance, and for curved approaches. The GPS had a stationary error which this research has shown precludes its use for automatic landing, unless the system is complemented with a ground-based position error correcting station, in which case the new Differential Global Positioning System (DGPS) provides acceptable path deviation sensing to permit automatic landing.

A number of suggestions for further work are given.

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