Design of Fixed Gain Compensator System for the Longitudinal Axis of the C-141 Fly-by-Wire Aircraft

摘要

The report presents an attempt to design a fixed gain control system for the longitudinal axis of the C-141 fly-by-wire aircraft. Classical control theory using root locus and frequency response (Bode) techniques was used throughout the design process. It was found that a quadratic over quadratic compensator, inserted in the forward path of the C* control loop, improved the system response even with the original discrete gains. With slightly relaxed constraints on the C* performance (* envelope was originally designed for fighter aircraft), a single fixed gain in the C* loop produced acceptable C* Category 3 responses. An additional quadratic over quadratic compensator was designed for the pitch attitude control loop; however, the acceptability of the attitude response with a fixed gain is questionable. (Modified author abstract)