Robust Digital Flight Control System for an Unfanned Research Vehicle UsingDiscrete Quantitative Feedback Theory

摘要

This thesis describes application of digital multiple-input multiple-output(MIMO) Quantitative Feedback Theory (QFT) technique to the design of a three axis rate controller for the Lambda Unmanned Research Vehicle. The resulting robust controller performs well throughout the flight envelope without gain scheduling. It results from research done at the Air Force Institute of Technology. The Lambda URV was designed by the Control Systems Development Branch of the Wright Laboratory at Wright-Patterson AFB, OH for flight testing aircraft control hardware and software. The flight control system is built using a small perturbation linear model developed from flight test data. The actuators, also modelled from aircraft test data, are second order in roll and pitch and first order in yaw. Nineteen separate plants are used to represent the flight envelope of the aircraft resulting from variations in speed, altitude, center of gravity location, and weight. The sample rate is 50 Hertz. The pitch channel is decoupled from the lateral-directional resulting in a single-input single-output (SISO) system for the pitch channel and a two-by-two MIMO system for the lateral-directional channel. The design employs the Nichols Chart and is accomplished in the w'-domain.