Digital Control Of Highly Augmented Combat Rotorcraft PDF Download

Proposed concepts for the next generation of combat (scout/attack) helicopters are to be embodied in a complex, highly maneuverable, multiroled vehicle with avionics systems which are as important to mission success as the airframe itself. Single pilot and nap-of-the-Earth operations require handling qualities which minimize the involvement of the pilot in basic stabilization tasks. To meet these requirements will demand a full authority, high-gain, multimode, multiply-redundant, digital flight-control system. The gap between these requirements and current low-authority, low-bandwidth operational rotorcraft flight-control technology is considerable. this research aims at smoothing the transition between current technology and advanced concept requirements. The report: (a) extensively reviews the state of the art of high-bandwidth digital flight-control systems; (b) illustrates the important concepts in design and analysis of high-gain, digital systems with a detailed case study involving a current rotorcraft system. Frequency-domain methods for design and analysis are stressed in this report as essential for the practical implementation of high-gain control systems for rotorcraft. Approximate and exact methods are explained and illustrated for treating the important concerns which are unique to digital systems. Proposed specifications and flight-test data concerning the handling qualities of scout/attack rotorcraft imply restrictions on the maximum effective time delay which must be carefully considered in the design process.